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Journal articles on the topic "Growth stress etc as required"
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Rajput, Vishnu D., Tatiana Minkina, Arpna Kumari, Harish, Vipin Kumar Singh, Krishan K. Verma, Saglara Mandzhieva, Svetlana Sushkova, Sudhakar Srivastava, and Chetan Keswani. "Coping with the Challenges of Abiotic Stress in Plants: New Dimensions in the Field Application of Nanoparticles." Plants 10, no. 6 (June 15, 2021): 1221. http://dx.doi.org/10.3390/plants10061221.
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Abiotic stress in plants is a crucial issue worldwide, especially heavy-metal contaminants, salinity, and drought. These stresses may raise a lot of issues such as the generation of reactive oxygen species, membrane damage, loss of photosynthetic efficiency, etc. that could alter crop growth and developments by affecting biochemical, physiological, and molecular processes, causing a significant loss in productivity. To overcome the impact of these abiotic stressors, many strategies could be considered to support plant growth including the use of nanoparticles (NPs). However, the majority of studies have focused on understanding the toxicity of NPs on aquatic flora and fauna, and relatively less attention has been paid to the topic of the beneficial role of NPs in plants stress response, growth, and development. More scientific attention is required to understand the behavior of NPs on crops under these stress conditions. Therefore, the present work aims to comprehensively review the beneficial roles of NPs in plants under different abiotic stresses, especially heavy metals, salinity, and drought. This review provides deep insights about mechanisms of abiotic stress alleviation in plants under NP application.
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Adedayo, Afeez Adesina, and Olubukola Oluranti Babalola. "Rhizosphere Plant-Growth-Promoting Fungi Enhance the Growth of Crop Plants." Journal of Fungi 9, no. 2 (February 10, 2023): 239. http://dx.doi.org/10.3390/jof9020239.
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The fungi species dwelling in the rhizosphere of crop plants, revealing functions that endeavor sustainability of the plants, are commonly referred to as ‘plant-growth-promoting fungi’ (PGPF). They are biotic inducers that provide benefits and carry out important functions in agricultural sustainability. The problem encountered in the agricultural system nowadays is how to meet population demand based on crop yield and protection without putting the environment and human and animal health at risk based on crop production. PGPF including Trichoderma spp., Gliocladium virens, Penicillium digitatum, Aspergillus flavus, Actinomucor elegans, Podospora bulbillosa, Arbuscular mycorrhizal fungi, etc., have proven their ecofriendly nature to ameliorate the production of crops by improving the growth of the shoots and roots of crop plants, the germination of seeds, the production of chlorophyll for photosynthesis, and the abundant production of crops. PGPF’s potential mode of action is as follows: the mineralization of the major and minor elements required to support plants’ growth and productivity. In addition, PGPF produce phytohormones, induced resistance, and defense-related enzymes to inhibit or eradicate the invasion of pathogenic microbes, in other words, to help the plants while encountering stress. This review portrays the potential of PGPF as an effective bioagent to facilitate and promote crop production, plant growth, resistance to disease invasion, and various abiotic stresses.
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Atay, Ersin, Bruno Hucbourg, Aurore Drevet, and Pierre-Éric Lauri. "EFFECTS OF PREHARVEST DEFICIT IRRIGATION TREATMENTS IN COMBINATION WITH REDUCED NITROGEN FERTILIZATION ON ORCHARD PERFORMANCE OF NECTARINE WITH EMPHASIS ON POSTHARVEST DISEASES AND PRUNING WEIGHTS." Acta Scientiarum Polonorum Hortorum Cultus 18, no. 1 (February 22, 2019): 207–17. http://dx.doi.org/10.24326/asphc.2019.1.21.
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Fruit production should be adapted to future scenarios that are frequently associated with scarce resources, especially freshwater and fertilizers. New biologically-based fruit production strategies, i.e. taking into account tree growth and water status, are required to optimize irrigation and fertilization under abiotic stress conditions. It was hypothesized that a moderate abiotic stress, here deficit irrigation with or without nitrogen deficit, in the preharvest period, could decrease postharvest losses due to diseases and pruning weights due to reduced vegetative growth, without sacrificing the yield and fruit quality. This study was conducted over two years using the same trees of ‘Moncante’ nectarine cultivar grown in a commercial orchard. Trees were assigned to three treatments: (1) full irrigation at 80% estimated crop evapotranspiration (ETc), (2) deficit irrigation, i.e. at 75% of full irrigation, and (3) deficit irrigation and deficit nitrogen, i.e. at 75% of full irrigation and 75% of usual N-fertilization adopted by the grower in this commercial orchard. Deficit irrigation alone and in combination with deficit nitrogen reduced postharvest diseases and pruning weights without significant yield losses. Our results suggest that ETc-based approaches of reduced water irrigation may be a sustainable way to decrease phytosanitary inputs and workload in the orchard while maintaining the orchard performance.
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Barbera, S. "Video Image Analysis and Animal Welfare on Farm." Animal Welfare 12, no. 4 (November 2003): 513–15. http://dx.doi.org/10.1017/s0962728600026105.
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AbstractThe management of farmed livestock frequently creates situations of stress because of the periodical necessity for handling procedures (weight and linear measurements, veterinary procedures etc). Some of these practices can be avoided using technologies that obviate the need for direct handling. This can improve animal welfare and reduce risks to the handlers. Video image analysis is a technique that can be used for linear measurements and morphological evaluations required for growth trials, genetic studies or herd-book records. This paper describes the application of video image analysis to linear measurement and shape assessment in horses and cattle with minimal disturbance to the animals.
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Cao, Hong Wei, Cao Li, Bai Qing Zhang, Justice Kipkorir Rono, and Zhi Min Yang. "A Metallochaperone HIPP33 Is Required for Rice Zinc and Iron Homeostasis and Productivity." Agronomy 12, no. 2 (February 16, 2022): 488. http://dx.doi.org/10.3390/agronomy12020488.
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Both zinc (Zn) and iron (Fe) are essential micro-nutrients for plant growth and development, yet their levels in plants are tightly regulated to prevent either deficiency or phytotoxicity. In agronomic reality, such an imbalance of metal bioavailability to crops occurs frequently. Thus, mining genetic resources to improve crop traits relevant to metal homeostasis is a great challenge to ensure crop yield and food quality. This study functionally identified an uncharacterized metallochaperone family HIPP protein gene Heavy Metal Associated Isoprenylated Plant Proteins 33 (OsHIPP33) in rice (Oryza sativa). OsHIPP33 resides in the nucleus and plasma membrane and constitutively expresses throughout the lifespan. Transcription of OsHIPP33 is not induced by deprivation of Zn and Fe but upregulated under excessive Zn and Fe stress. In a short-term (one month) hydroponic study with the normal Zn and Fe supply, there were no significant changes in the growth and metal accumulation between the knockout (OsHIPP33) or knockdown (RNA interference) mutant lines and wild-type, while the long-term field trials (for two successive years) demonstrated that the mutation of OsHIPP33 significantly compromised the rice growth and development (such as rice leave tissues, panicle length, spikelet fertility, seed weight per plant, 1000-grain weight, etc.), with the mature grain yield of OsHIPP33 and RNAi lines reduced by 52% and 12–15% respectively, compared with wild-type. Furthermore, the accumulation of Zn and Fe in rice straw, husk and brown rice was also reduced. These results suggest that the disruption of OsHIPP33 can dampen rice agronomic traits, signifying that OsHIPP33 expression is required for Zn and Fe homeostasis and subsequent production of rice grains.
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Rajput, Vishnu D., Tatiana Minkina, Morteza Feizi, Arpna Kumari, Masudulla Khan, Saglara Mandzhieva, Svetlana Sushkova, et al. "Effects of Silicon and Silicon-Based Nanoparticles on Rhizosphere Microbiome, Plant Stress and Growth." Biology 10, no. 8 (August 17, 2021): 791. http://dx.doi.org/10.3390/biology10080791.
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Silicon (Si) is considered a non-essential element similar to cadmium, arsenic, lead, etc., for plants, yet Si is beneficial to plant growth, so it is also referred to as a quasi-essential element (similar to aluminum, cobalt, sodium and selenium). An element is considered quasi-essential if it is not required by plants but its absence results in significant negative consequences or anomalies in plant growth, reproduction and development. Si is reported to reduce the negative impacts of different stresses in plants. The significant accumulation of Si on the plant tissue surface is primarily responsible for these positive influences in plants, such as increasing antioxidant activity while reducing soil pollutant absorption. Because of these advantageous properties, the application of Si-based nanoparticles (Si-NPs) in agricultural and food production has received a great deal of interest. Furthermore, conventional Si fertilizers are reported to have low bioavailability; therefore, the development and implementation of nano-Si fertilizers with high bioavailability could be crucial for viable agricultural production. Thus, in this context, the objectives of this review are to summarize the effects of both Si and Si-NPs on soil microbes, soil properties, plant growth and various plant pathogens and diseases. Si-NPs and Si are reported to change the microbial colonies and biomass, could influence rhizospheric microbes and biomass content and are able to improve soil fertility.
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TIWARI, GIRJA SHANKER, NAVNEET PAREEK, and KIRAN P. RAVERKAR. "Increased heat and drought stress under climate change and their impact on physiological growth and development of crops: A review." Indian Journal of Agricultural Sciences 88, no. 12 (December 11, 2018): 1818–25. http://dx.doi.org/10.56093/ijas.v88i12.85374.
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Abiotic stresses are major constraints to crop production and food security worldwide, the increasing trend and projection under climate change pose further challenge and warrants close attention of researchers and policy makers. Heat and drought are judged as most common stresses having adverse impact on growth and productivity of the crops. Understanding of the physiological, biochemical, and ecological responses of these stresses is prerequisite to develop management practices. The plant responses to these stresses can be categorized into morphological, physiological, and biochemical responses quantified to assess their impact. Though plants have capability to modify their growth pattern and physiological process to cope with heat and drought stresses but it costs dearly in terms of overall performance and yield, therefore it is a must to understand plant response to various stresses in order to develop suitable adaptation strategies. This review focuses on the plant responses towards heat and drought stresses pointing on the commonalities and differences. Due to physical damages, physiological disruptions, and biochemical changes under limited water supply and elevated temperatures there is negative impact on crop growth and yields. Both conventional and modern approaches are desired to deal with heat and drought stresses. A holistic approach including short term strategy comprising management practices promoting in-situ moisture conservation, water harvesting, micro environment modification etc, and long term strategies including developing heat and drought tolerant varieties, developing irrigation infrastructure, permanent change in land configuration, etc are required. The recent government. initiative like PMKSY aiming irrigation to each field (Har Khet Ko Pani) through water harvesting, conveyance, drip irrigation in the back drop of time bound target of doubling farmers income will be a big boost to cope heat and drought stress and to induce climatic resilience.
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Sarraf, Mohammad, Kanchan Vishwakarma, Vinod Kumar, Namira Arif, Susmita Das, Riya Johnson, Edappayil Janeeshma, et al. "Metal/Metalloid-Based Nanomaterials for Plant Abiotic Stress Tolerance: An Overview of the Mechanisms." Plants 11, no. 3 (January 25, 2022): 316. http://dx.doi.org/10.3390/plants11030316.
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In agriculture, abiotic stress is one of the critical issues impacting the crop productivity and yield. Such stress factors lead to the generation of reactive oxygen species, membrane damage, and other plant metabolic activities. To neutralize the harmful effects of abiotic stress, several strategies have been employed that include the utilization of nanomaterials. Nanomaterials are now gaining attention worldwide to protect plant growth against abiotic stresses such as drought, salinity, heavy metals, extreme temperatures, flooding, etc. However, their behavior is significantly impacted by the dose in which they are being used in agriculture. Furthermore, the action of nanomaterials in plants under various stresses still require understanding. Hence, with this background, the present review envisages to highlight beneficial role of nanomaterials in plants, their mode of action, and their mechanism in overcoming various abiotic stresses. It also emphasizes upon antioxidant activities of different nanomaterials and their dose-dependent variability in plants’ growth under stress. Nevertheless, limitations of using nanomaterials in agriculture are also presented in this review.
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Шорінов, О. В. "АНАЛІЗ ІСНУЮЧИХ МОДЕЛЕЙ ВИНИКНЕННЯ НАПРУЖЕНЬ В ТОНКИХ ПЛІВКАХ І ПОКРИТТЯХ." Open Information and Computer Integrated Technologies, no. 91 (June 18, 2021): 77–96. http://dx.doi.org/10.32620/oikit.2021.91.06.
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The analysis of existing models of stress in thin films and coatings was carried out. While reaching critical value, stress can lead to defects, cracks, delamination of coating from substrate, etc. The task of prediction and controlling of the direction and magnitude of the stress of coating-substrate system is relevant nowadays regardless of coating and thin films deposition methods. Different types of coatings and thin films are widely used in almost all industries: optics, mechanical engineering, measuring technology, medicine, micro- and nanoelectronics, etc. Development and investigation of new promising methods for the formation of nanostructures, such as nanowires in a plasma environment, requires a sufficient theoretical basis for the origin and growing of stresses. Depending on the mechanism, the causes of stress in thin films and coatings can be: chemical reactions, phase transformations, inclusions and impurities, particle bombardment (the cause of internal stress during coating growing); temperature changes (the cause of thermal stress due to different values of coefficients of thermal expansion of coating and substrate materials); deformation of coating-substrate system, etc. Models of stress development in coatings and thin films can be divided into the following groups: stress that occur at the coating-substrate interface, internal coating stress, and stress at the coating-environment interface. The study presents methods of stress measuring in thin films and coatings. Based on the results of the current research, it can be concluded that the existing models of stress in the process of growth of coatings and films, as well as stress arising under the action of external forces, describe only the causes of the stress and unfortunately do not give an understanding of their complex effect on stress-strain state of coating-substrate system and need further development and improvement. Stress relaxation is also important to obtain new structures and certain properties of coatings. The development of stress management tools can be considered as one of the ways to increase the lifetime of products with coatings and thin films.
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Ferlazzo, Adriana, Cristina Cravana, Esterina Fazio, and Pietro Medica. "The different hormonal system during exercise stress coping in horses." May-2020 13, no. 5 (2020): 847–59. http://dx.doi.org/10.14202/vetworld.2020.847-859.
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The review discusses the hormonal changes during exercise stress. The exercise generally produces a rise of adrenaline (A), noradrenaline (NA), adrenocorticotropic hormone (ACTH), cortisol, glucagon, growth hormone, arginine vasopressine, etc., and a drop of insulin. The hormonal events during reestablishment of homeostasis due to exercise stress can be divided into a catabolic phase, with decreased tolerance of effort, and reversible biochemical, hormonal and immunological changes, and an anabolic phase, with a higher adaptive capacity, and enhanced performance. The two main hormonal axes activated in the catabolic phase are sympathetic–adrenal–medullary system and hypothalamic-pituitary-adrenal (HPA) axis, while in the anabolic phase, growth hormone-insulin-like factor I axis, and gonadal axes. The hormonal responses during exercise and recovery can be regarded as regulatory and integrated endocrine responses. The increase of catecholamines and ACTH is dependent on the intensity of exercise; a marked increase in plasma A occurs during exercises with high emotional content. The response of cortisol is correlated with the duration of exercise, while the effect of exercise duration on β-endorphin changes is highly dependent on the type of exercise performed. Cortisol and β-endorphin changes usually occur in phase, but not during exercises with high emotional content. Glucocorticoids and iodothyronines are involved in meeting immediate energy demands, and a model of functional interactions between HPA axis and hypothalamic-pituitary-thyroid axis during exercise stress is proposed. A modulation of coping responses to different energy demanding physical activities required for sport activities could be hypothesized. This review supports the proposed regulation of hypophysiotropic TRHergic neurons as metabolic integrators during exercise stress. Many hormonal systems (ghrelin, leptin, glucose, insulin, and cortisol) are activated to control substrate mobilizations and utilization. The cardiovascular homeostasis, the fluid and electrolyte balance during exercise are highly dependent on vasoactive hormones (antidiuretic hormone, atrial natriuretic peptide, renin–angiotensin–aldosterone, and prostaglandins) control.
Dissertations / Theses on the topic "Growth stress etc as required"
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(9823514), Stephen Ockerby. "Leaves shed light on flowering: (Vegetative growth and control of floral induction in Sorghum bicolor)." Thesis, 2001. https://figshare.com/articles/thesis/Leaves_shed_light_on_flowering_Vegetative_growth_and_control_of_floral_induction_in_Sorghum_bicolor_/13465283.
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Project tests the hypothesis that floral induction and flowering time in Sorghum bicolor L. can be "regulated by in-crop canopy modification", with the result that farmers would be better able to manage their corps to avoid severe crop water stress at flowering.
Books on the topic "Growth stress etc as required"
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Duman, Ronald S. Neurotrophic Mechanisms of Depression. Edited by Dennis S. Charney, Eric J. Nestler, Pamela Sklar, and Joseph D. Buxbaum. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.003.0027.
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Early theories of depression and treatment response were centered on the monoamine neurotransmitters, but more recent work has focused on functional and structural synaptic plasticity and the role of neurotrophic factors, particularly brain derived neurotrophic factor (BDNF). Neurotrophic factors regulate all aspects of neuronal function, including adaptive plasticity, synapse formation, and neuronal survival. Chronic stress and depression cause reductions in levels of BDNF and other key factors, including vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2), in cortical regions that contribute to atrophy and loss of neurons observed in depressed patients and rodent stress models. In contrast, these neurotrophic factors are upregulated by chronic administration of typical antidepressants and are required for antidepressant responses. Moreover, fast acting, highly efficacious antidepressant agents such as ketamine rapidly increase BDNF release and synapse formation, paving the way for a new generation of medications for the treatment of depression.
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Patel, Bela, and Eric J. Thomas. Telemedicine in critical care. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0012.
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The majority of critically-ill patients are admitted to hospitals that do not have physician intensivist coverage, despite strong evidence that clinical outcomes are improved with intensivist staffing. Telemedicine can leverage clinical resources by providing critical care expertise to patients in intensive care units (ICUs) by off-site clinicians using video, audio, and electronic links. In the past 10 years, telemedicine in critical care has seen tremendous growth in the number of ICU patients being supported by this care model across the USA. The impact of ICU telemedicine coverage has been studied rigorously only in a few studies and the outcomes have been mixed and inconsistent. Telemedicine has been shown in some studies to improve adherence to ICU best practices for the prevention of deep venous thrombosis, stress ulcers, ventilator-associated pneumonia, and catheter-related bloodstream infections. Further research in ICU telemedicine is required to understand the variability of outcomes among the telemedicine programmes studied and to effectively implement the technology to consistently improve outcomes and reduce costs in the critical care environment.
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Einstein, Andrew J. Radiation Considerations. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199392094.003.0034.
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Radiation considerations are an integral part of the practice of nuclear cardiac imaging. Concern regarding radiation has increased in recent years, reflected in statements by many professional societies, and likely attributable both to rapid growth in use of nuclear cardiology as well as high doses received by some nuclear cardiology patients. The fundamental principles of medical radiological protection are justification (ensuring that the right test is performed for the right patient at the right time), optimization (ensuring that the test is performed in the right manner), and dose limitation, which while applicable to healthcare workers is not operative regarding patients. Three "As" facilitate and serve as an organizing principle for justification: awareness, appropriateness, and audit. Awareness incorporates knowledge of the benefits and risks of testing involving radiation and effective communication of these to the patient. Appropriateness in nuclear cardiology can be assessed using the American College of Cardiology's appropriateness criteria. Methods that have been demonstrated to improve appropriateness include using a collaborative learning model, a point-of-order decision support tool, and a multifaceted intervention including threatened loss of insurance coverage. A variety of strategies should be considered for optimization to ensure patient-centered imaging. These including strategic selection of both the protocol, e.g. selecting a stress-first protocol and performing stress-only imaging in patients without a high pre-test probability of abnormal findings on stress imaging, or using PET, and also the administered activity, e.g. by using weight-based dosing and/or software- or hardware-based advances in camera technology. Special considerations are required for pregnant, nursing, and pediatric patients.
Book chapters on the topic "Growth stress etc as required"
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Kide Mengistu, Habtamu. "Abiotic and Biotic Stress Factors Affecting Storage of Legumes in Tropics." In Legumes Research - Volume 1. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99413.
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Tropical regions such as South Asia (SA) and Sub-Saharan (SSA) do have storage environment that may impose abiotic and/or biotic stress or. This book chapter aims to broaden current knowledge on the ‘Abiotic and Biotic Stress Factors Affecting Storage of Legumes in Tropics’. This book chapter is prepared by including all relevant studies and detailed literatures using various scholastic search approaches. Typically, published papers and abstracts are identified by a computerized search of electronic data bases that include PubMed, Science Direct, Scirus, ISI Web of Knowledge, Google Scholar and CENTRAL (Cochrane Central Register of Controlled Trials). Thus, diseases, insects, etc…, are biological factors that cause biotic stress in plants while abiotic stress is caused by either physical or chemical factors. Biotic and abiotic stresses create adverse effects on multiple procedures of morphology, biochemistry and physiology that are directly connected with growth and yield of legume grains. It is, therefore, clear that the most important factors of food grains loss are moisture, temperature, metabolic activity and respiration, insects, mites, micro-organisms, rodents, birds and storage structures. Initial grain condition or quality of the seed for storage can indirectly be affected by abiotic stresses like water scarcity, high salinity, extreme temperatures, and mineral deficiencies or metal toxicities which reduce the crop’s productivity. For maintenance of storage of initial grain’s quality, grain must be dried and cooled prior to storage, the store must be constructed for blocking rodents and birds, enabling protection from sun and light entrance, allowing aeration to keep the temperature uniform in the store. Also, bringing the temperature of the grain down to below 12°C is necessary, since this temperature is a threshold at which microorganisms’ reproductive activity is inhibited. Storage spaces with higher relative humidity (95%) and a temperature of 35°C, are detrimental for storage of legume grains. In general, legume grains should be attaining a temperature of about ≤ 10 °C before placing them in store. For storage safety, it is preferable to place the grain in the storage at moisture content of 13%, or less than 14% on wet basis. Also, combining drying and storage facilities in one and the same structure is economical, and allows further conditioning at later stages if required. In order to reduce postharvest loss from customs of traditional storage by farmers in tropics, governments should mobilize and integrate multidisciplinary management system of storage loss, and monitor precautionary measures of the stored grain throughout the storage period. They should be facilitating the selection and promotion of alternative, cost-effective and appropriate storage structures considering suitability to local conditions and sustainability.
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A., Kodieswari. "Early Detection of Cancer Using Smartphones." In Advances in Medical Technologies and Clinical Practice, 25–31. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-5225-6067-8.ch003.
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Cancer disease is the second largest disease in the world with high death mortality. Cancer is an abnormal growth of a normal cell. There are more than 100 types of cancer like blood cancer, brain cancer, small intestine cancer, lung cancer, liver cancer, etc. The type of cancer can be classified by the type of cell which is initially affected. When cancer grows it does not show any symptom. The symptom will appear when the cancer cell grows in mass and the symptom of cancer depends on the type of cancer. The cause of cancers is environmental pollutants, food habits, inherited genetics, tobacco, stress, etc., but in practice, it is not possible to prove the cause of cancer since various cancers do not have specific fingerprints. After the heart attack, cancer is a second killer disease in India. The death mortality is high in cancer because in most of the cases it is identified at the final stage which causes more death. According to ICMR, among 1.27 billion Indian populations, the incidence of cancer is 70-90 per 100,000 populations and 70% of cancer is identified in the last stage accounting for high morality. There are many types of treatment to treat cancer and they are surgery, radiation therapy, chemotherapy, targeted therapy, hormone therapy, stem cell transplant, etc. All cancer treatments will have side effects and the treatments will help only if the cancer cells are identified at the early stage. So time factor is important in diagnosing of cancer cells; hence, early detection of cancer will reduce the mortality rate. This chapter proposed the early detection of cancer cells using image processing techniques by the structure of circulating tumor cell. Early detection of cancer cells is very difficult because the concentration of cancer cells are extremely small and about one million malignant cell is encountered per billion of healthy cells. The circulating tumor cells, CTC, are shed into the bloodstream as a tumor grows, and it is believed these cells initiate the spread of cancer. CTC are rare, existing as only a few per one billion blood cells, and a highly efficient technology like chip-based biosensor platforms is required to capture the CTC, which in turn helps to detect cancer cell at an early stage before spreading. In proposed method, the circulating tumor cell has used a marker to detect cancer at early stage.
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Wack, Julia, Kim Ho Yeap, Zi Xin Oh, and Humaira Nisar. "Evaluation of the Application Potential of Metamaterial-based Antennas for Intelligent Street Lighting Systems." In Emerging Technologies and Applications for a Smart and Sustainable World, 175–210. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815036244122010012.
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In this chapter, metamaterials and their properties in the application of antenna designs are discussed. Although metamaterials offer great benefits in diverse areas, this work emphasizes their implementation in the development of smart cities. The world faces challenges ensued to environmental problems, population growth, and other current dynamics. New technologies are required to present solutions for cities to be organised efficiently and effectively while also supporting the environment by pursuing higher sustainability. Intelligent street lighting systems are one out of the several approaches that offer promising development opportunities. Intelligent street lights have already been implemented in some cities, with positive outcomes in terms of energy savings, reduced traffic, improved infrastructure, and supply, etc. The different concrete goals of a smart city and intelligent streetlight concepts were discussed, and the research on metamaterials was accordingly adapted. At the current state of technology, there are no metamaterial antennas on the market that are directly declared to be suitable for the installation of intelligent streetlights. However, due to the great advantages of metamaterial antennas, it would be worthwhile to look into ways to improve the functionalities of intelligent streetlights using these antennas. In this chapter, the suitability of metamaterial antennas implemented in streetlights is studied. Some existing planar antennas were enhanced by incorporating metamaterials into them. The analysis shows that the radiation performances of the enhanced antennas are significantly improved. Therefore, metamaterial antennas have the potential of being applied in a broad range of applications, including intelligent streetlights.
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Bunker, Bruce C., and William H. Casey. "Stress Corrosion Cracking: Chemically Activated Nanomechanics." In The Aqueous Chemistry of Oxides. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780199384259.003.0024.
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Although dissolution reactions involving water can etch and decompose oxides, truly catastrophic failures of oxide structures usually involve fractures and mechanical failures. Geologists and geochemists have long recognized that water and ice both play key roles in promoting the fracture and crumbling of rock (see Chapter 17). Freezing and thawing create stresses that amplify the rate at which water attacks metal–oxygen bonds at the crack tip. The interplay between water and stressed oxides also leads to common failures in man-made objects, ranging from the growth of cracks from flaws in windshields to the rupture of optical fibers in communication systems. In this chapter, we outline how mechanical deformations change the reactivity of metal–oxygen bonds with respect to water and other chemicals, and how reactions on strained model compounds have been used to predict time to failure as a function of applied stress. The basic phenomenon of stress corrosion cracking is illustrated in Figure 16.1. Cracks can propagate through oxide materials at extremely fast rates, as anyone who has dropped a wine glass on the floor can attest. High-speed photography reveals that when glass shatters, cracks can spread at speeds of hundreds of meters per second, or half the speed of sound in the glass. At the other end of the spectrum, cracks in glass can grow from preexisting flaws so slowly that only a few chemical bonds are broken at the crack tip per hour. Because mechanical failures are associated with cracking, it is critical for design engineers to understand the factors that control crack growth rates for this enormous range of crack velocities (a factor of 1012). In addition, because it is difficult to measure crack velocities slower than 10−8 m/second, it is often necessary to make major extrapolations from measured data to predict the long-term reliability of glass and ceramic objects. Will an optical fiber under stress fail in 1 year or 10 years? Answering this question can require accurate extrapolations down to crack growth rates as low as 10−10 m/second.
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Sayeed Md. Hasibuzzaman, Abu, Farzana Akter, Shamim Ara Bagum, Nilima Hossain, Tahmina Akter, and M. Shalim Uddin. "Morpho-Physiological Mechanisms of Maize for Drought Tolerance." In Plant Stress Physiology. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.91197.
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Maize is one of the mostly consumed grains in the world. It possesses a greater potentiality of being an alternative to rice and wheat in the near future. In field condition, maize encounters abiotic stresses like salinity, drought, water logging, cold, heat, etc. Physiology and production of maize are largely affected by drought. Drought has become a prime cause of agricultural disaster because of the major occurrence records of the last few decades. It leads to immense losses in plant growth (plant height and stem), water relations (relative water content), gas exchange (photosynthesis, stomatal conductance, and transpiration rate), and nutrient levels in maize. To mitigate the effect of stress, plant retreats by using multiple morphological, molecular, and physiological mechanisms. Maize alters its physiological processes like photosynthesis, oxidoreductase activities, carbohydrate metabolism, nutrient metabolism, and other drought-responsive pathways in response to drought. Synthesis of some chemicals like proline, abscisic acid (ABA), different phenolic compounds, etc. helps to fight against stress. Inoculation of plant growth-promoting rhizobacteria (PGPR) can result to the gene expression involved in the biosynthesis of abscisic acid which also helps to resist drought. Moreover, adaptation to drought and heat stress is positively influenced by the activity of chaperone proteins and proteases, protein that responds to ethylene and ripening. Some modifications generated by clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 are able to improve maize yield in drought. Forward and reverse genetics and functional and comparative genomics are being implemented now to overcome stress conditions like drought. Maize response to drought is a multifarious physiological and biochemical process. Applying data synthesis approach, this study aims toward better demonstration of its consequences to provide critical information on maize tolerance along with minimizing yield loss.
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Sharma, Akanksha, and Prashant Tandekar. "Cyber Security and Business Growth." In Cyber Security and Threats, 1208–21. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5634-3.ch059.
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Information and Communications Technologies (ICTs), particular the Internet, have been an increasingly important aspect of global social, political and economic life, and are the backbone of the global information society today. Their evolution and development has brought many benefits along with the threat of serious cyber-attacks that had been demonstrated over the past few years. Due to cybercrime business world drains huge money each year and incurs a large amount in resolving a single attack. It also damages organization's reputation and brand image, loss of intellectual property and sensitive data, loss of customer trust etc. Addressing major threats and challenges begins with setting up information security policy to ensure confidentiality, integrity and availability of company information and communication. Since telecom Sector is on its boom, a technological solution can solve the immediate challenges of identifying, investigating, and prosecuting computer- related crimes and changes required for long-term problem solving.
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Godswill Awuchi, Chinaza, Erick Nyakundi Ondari, Ifie Josiah Eseoghene, Hannington Twinomuhwezi, Ikechukwu Otuosorochi Amagwula, and Sonia Morya. "Fungal Growth and Mycotoxins Production: Types, Toxicities, Control Strategies, and Detoxification." In Fungal Reproduction and Growth [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100207.
Full textAbstract:
Fungal growth and the production of mycotoxins are influenced by several factors. Environmental conditions such as temperature, water activity, and humidity affect mycotoxin production and fungal growth. Other factors such as pH, fungal strain, and substrate also play roles. Common mycotoxins include aflatoxins, fumonisins, trichothecenes, sterigmatocystin (STC), citrinin, ergot alkaloids, ochratoxins, zearalenones (ZEAs), patulin, deoxynivalenol (DON), Alternaria toxins, tremorgenic mycotoxins, fusarins, cyclochlorotine, sporidesmin, 3-nitropropionic acid, etc. These toxins cause many health conditions in animals and humans, including death. A comprehensive approach starting from the field before planting, continuing throughout the entire food chain is required to control mycotoxin contamination. Good practices, such as proper field practices before and after planting, good harvest practices and postharvest handling, and proper drying and storage measures, help reduce mycotoxin contamination. Several physical, biological, and chemical techniques have been applied to help reduce/eliminate mycotoxin contamination. Food processing also play slight role in mycotoxins removal.
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Singh, Amanpreet, and Harmandeep Singh Chahal. "Management of Abiotic Stress in Forage Crops." In Abiotic Stress in Plants [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93852.
Full textAbstract:
Forage plays a key role in rearing ruminants and protecting the environment. Apart from serving as the primary source of food for domestic and wild animals, forages also contribute to human civilization in different ways like protecting soil through crop over and fertility by addition of organic matter. It also provides habitat for wild animals. A survival strategy plays a more important role than a growth strategy to improve the sustainability of forage production, especially in extreme environmental conditions . Climate change is likely to affect the forage production and nutritional food security for domestic animals. Long-term rainfall data in India indicate that rainfed areas experience 3 to 4 years of drought in every 10 years. Of these, one or two of it occur in severe form. Forage crop production is largely affected by abiotic factors related stress such as drought, salinity, etc. There is need to adopt various conventional and genetic approaches to improve stress tolerance of forage crops.
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EL Sabagh, Ayman, Akbar Hossain, Mohammad Sohidul Islam, Muhammad Aamir Iqbal, Ali Raza, Çetin Karademir, Emine Karademir, et al. "Elevated CO2 Concentration Improves Heat-Tolerant Ability in Crops." In Abiotic Stress in Plants [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94128.
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The rising concentration of atmospheric carbon dioxide (aCO2) and increasing temperature are the main reasons for climate change, which are significantly affecting crop production systems in this world. However, the elevated carbon dioxide (CO2) concentration can improve the growth and development of crop plants by increasing photosynthetic rate (higher availability of photoassimilates). The combined effects of elevated CO2 (eCO2) and temperature on crop growth and carbon metabolism are not adequately recognized, while both eCO2 and temperature triggered noteworthy changes in crop production. Therefore, to increase crop yields, it is important to identify the physiological mechanisms and genetic traits of crop plants which play a vital role in stress tolerance under the prevailing conditions. The eCO2 and temperature stress effects on physiological aspects as well as biochemical profile to characterize genotypes that differ in their response to stress conditions. The aim of this review is directed the open-top cavities to regulate the properties like physiological, biochemical, and yield of crops under increasing aCO2, and temperature. Overall, the extent of the effect of eCO2 and temperature response to biochemical components and antioxidants remains unclear, and therefore further studies are required to promote an unperturbed production system.
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Ali, Nawab, and Mohammad Akmal. "Morphophysiological Traits, Biochemical Characteristic and Productivity of Wheat under Water and Nitrogen-Colimitation: Pathways to Improve Water and N Uptake." In Abiotic Stress in Plants [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94355.
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Drought stress is the most prominent limiting factor and abiotic stress that manipulates the physiological pathway, biochemical traits and hence negatively affects wheat crop productivity. The global nitrogen (N) recovery indicated that about two-fifths of N inputs are lost in the ecosystems through emission, denitrification, gaseous loss, leaching, surface runoff and volatilization etc. Farmers are using higher rates of N to harvest maximum yield but about 50–60% of applied N to crop field is not utilized by the plants and are lost to environment causing environmental pollution. These deleterious environmental consequences need to be reduced by efficient management of N and/or water. N-availability is often regulated by soil water; hence crop is experiencing N- and water-limitation simultaneously. There is great impetus to optimize their uptake through interconnectedness of water and N for yield determination of wheat because of the water scarcity and N losses. It is further advocate that there is need to investigate the intricate role of economizing N rate and water simultaneously for wheat crop growth, yield and backing quality may be beneficial to be investigate.
Conference papers on the topic "Growth stress etc as required"
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Hyde, C. J., W. Sun, and T. H. Hyde. "A Novel Method for Obtaining the Multiaxiality Constant for Damage Mechanics Which is Appropriate to Crack Tip Conditions." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57166.
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Many engineering components, such as power plant steam pipes, aero-engine turbine discs, etc, operate under severe loading/temperature conditions for the majority of their service life. As a result, cracks can initiate and subsequently propagate over time due to creep. Damage mechanics is a robust method for the prediction of behaviour of components subjected to high temperature creep conditions and in particular, the Liu and Murakami model has proven to be a useful tool for the prediction of creep crack growth under such conditions. Previous methods for obtaining the constant of multiaxiality required for the use of such models, i.e. α, have relied upon the steady load testing of specimens designed to give a specific multiaxial stress-state, such as notched bars, and the failure time obtained. A series of results from finite element (FE) analyses based on the same geometry and loading/temperature conditions as the experiment, each performed with a different α-value, are then interpolated in order to identify the α-value which results in the same failure time, tf, as that of the experimental test. However, the stress-state present within such a specimen geometry (and therefore the α-value obtained) does not reflect the multiaxial severity of the stress state ahead of a crack tip. Therefore, for the application of the Liu and Murakami model to crack tip (i.e., creep crack growth) conditions, it follows that the α-value should be obtained from a multiaxial stress-state of equal severity to that to which it is to be applied, i.e. a crack tip. Therefore compact tension (CT) specimen creep crack growth data has been used in order to obtain the α-value. The process for the α-value determination is similar to that discussed for the notched bar, except that the interpolation of the time to failure is replaced with an interpolation of the time to a given crack length, ta. The resulting FE predictions based on CT and thumbnail crack specimen geometries, for a 316 stainless steel, are shown to be accurate in comparison to experimental results.
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Fourcade, Charles, Minji Fong, James Axline, Do Jun Shim, Chris Lohse, Charles Tomes, and Mohammed Farooq. "Application of ASME Code Section XI Appendix L Using 3-D Finite Element Analyses." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21729.
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Abstract As part of a fatigue management program for subsequent license renewal, a flaw tolerance evaluation based on ASME Code, Section XI, Appendix L may be performed. The current ASME Code, Section XI, Appendix L flaw tolerance methodology requires determination of the flaw aspect ratio for initial flaw size calculation. The flaw aspect ratios listed in ASME Section XI, Appendix L, Table L-3210-2, for austenitic piping for example, are listed as a function of the membrane-to-gradient cyclic stress ratio. The Code does not explicitly describe how to determine the ratio, especially when utilizing complex finite element analyses (FEA), involving different loading conditions (i.e. thermal transients, piping loads, pressure, etc.). The intent of the paper is to describe the methods being employed to determine the membrane-to-gradient cyclic stress ratios, and the corresponding flaw aspect ratios (a/l) listed in Table L-3210-2, when using finite element analysis methodology. Included will be a sample Appendix L evaluation, using finite element analysis of a pressurized water reactor (PWR) pressurizer surge line, including crack growth calculations for circumferential flaws in stainless steel piping. Based on this example, it has been demonstrated that, unless correctly separated, the membrane-to-gradient cyclic stress ratios can result in extremely long initial flaw lengths, and correspondingly short crack growth durations.
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Holtam, C. M., D. P. Baxter, I. A. Ashcroft, and R. C. Thomson. "The Behaviour of Shallow Cracks in a Pipeline Steel Operating in a Sour Environment." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57083.
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Setting conditions for the avoidance of in-service crack growth in aggressive corroding environments has long been a major challenge due to the number of variables that have a significant effect on material behaviour. One area where both experimental data and a validated assessment methodology are lacking is the behaviour of shallow cracks. This paper describes the early results of an ongoing research programme aimed at addressing the shortfall in experimental data to characterise material behaviour in the shallow crack regime, with the long-term aim of improving the understanding and assessment of the early stages of environment assisted cracking (EAC). There is an industry need for a better understanding of material behaviour under these conditions, and for the development of a more robust assessment methodology. API 5L X65 pipeline steel parent material was tested in a sour environment with initial flaw sizes in the range 1–2 mm. Fatigue crack growth rate (FCGR) tests have been performed to investigate the influence of crack depth on crack growth rate (da/dN). Initial results suggest that crack growth rates for deep flaws can increase by a factor of 5–100 compared to air depending on the applied stress intensity range (ΔK). Shallow cracks have been shown to grow up to 130 times faster in a sour environment than in air and up to an order of magnitude faster than deep cracks in a sour environment at the same value of ΔK. Constant load tests have also been performed to investigate the influence of crack depth on the threshold stress intensity factor for stress corrosion cracking (KISCC). Preliminary results suggest that in this case there is no crack depth dependence in the range of flaw sizes tested. While further experimental work is required, the results obtained to date highlight the potential non-conservatism associated with extrapolating deep-crack data. Guidance is therefore provided on how to generate appropriate experimental data to ensure that subsequent fitness for service assessments are conservative.
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Zhang, Yan-Hui. "Development of a Screening Frequency Scanning Test Method." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77068.
Full textAbstract:
Fatigue crack growth rates (FCGR) in corrosive environment depends on loading frequency. Frequency scanning testing is often used to determine this effect. However, it is well known that the effect of loading frequency also depends on the magnitude of stress intensity factor range, ΔK. It is generally found that, with decreasing loading frequency, FCGR decreases in the low ΔK regime, increases and then decreases after reaching the saturating loading frequency in the intermediate ΔK regime, and keeps increasing in the high ΔK regime. To accurately characterise the effect of loading frequency on FCGR, several frequency scanning tests are required for a particular application (corrosive environment, material, welding procedure etc), each at a different ΔK level. These are time consuming and expensive tests. A novel screening frequency scanning test method has thus been developed. The method is similar to the step load fracture toughness test method often used to make a quicker estimate of fracture toughness of material in corrosive environment. In the screening frequency scanning test, both loading frequency and ΔK are changed in steps. At a relatively low and constant ΔK level, loading frequency is reduced in steps, after a certain amount of crack growth. Once the FCGR exhibits decreasing or has achieved a saturating loading frequency with decreasing loading frequency, ΔK is then increased to another higher level and the above process is repeated; the above procedures are repeated until the target maximum ΔK and the lowest loading frequency have been achieved. This method allows an estimate of the effect of loading frequency on FCGR in a large ΔK range using a single specimen. The results of the screening frequency scanning tests demonstrated that this method was feasible and provided a good and quick estimate of the effect of loading frequency on FCGR.
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Yang, Zhengmao, Kumar Shashi, and Jens P. Tronskar. "Influence of Localized Geometric Imperfections i.e. Buckles and Wrinkles on the Integrity of Pipelines." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57066.
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Pipelines are relied upon to transport hazardous liquids and gasses over long distances. A major threat to the integrity of pipelines is mechanical damage, caused by outside natural forces. According to the AGA report [1], 39% of offshore and 37.7% land based natural gas pipeline failures were caused by outside force. During the installation of offshore pipelines the pipe wall at the 6 o’clock position sees large compressive strain and local buckling may occur. Dents may also occur by impact onto hard objects such as the rollers on the stinger or rocks on the seabed and by anchor impact etc. These kinds of imperfections change the local geometry of the pipe, and therefore, a stress concentration and local bending stress will be induced. The stress concentration factor can be up to 10 depending on the geometry of the imperfection. As a result, the local stresses will be much higher than the design stresses for the pipeline in operation subject to internal pressure and axial strain, and fracture and fatigue capacity of the pipelines with these imperfections will decrease dramatically. Because of the large local deformation, the materials in the deformed pipe region have undergone large local plastic strains i.e. 10–20% plastic deformation. The material properties of the pipe with large plastic strain will be drastically changed, and therefore the fracture resistance of the pipe is expected to be decreased, especially when the damage is located at the seam or girth welds. To assess the criticality of such damage which often can be associated with strain induced flaws in the heavily deformed parent metal and welds, ‘fitness-for-service’ assessment is required. The objective is to determine the severity of the flaws in the deformed pipe and to make the repair/replacement decision. At present there are no definitive assessment guidelines that consider these aspects and how to incorporate the behaviour and fracture capacity of the heavily deformed material. In this paper, a numerical model of typical local imperfections i.e. buckles and wrinkles was established from the in-situ geometry measurements. The local stress distributions of the pipes were analyzed. Based on this stress analyses, the stress concentration around the local imperfections in operation were obtained and the fracture capacity and fatigue life of the pipeline was assessed. The tensile and J R-curve data for deformed pipeline materials were obtained by the DNV Energy laboratory to study the influences of the large plastic strain on the material properties, and the fracture resistance and fatigue crack growth of the pipe. Based on the numerical analysis and test results, a fracture combined fatigue assessment was performed to decide on the mitigation and remediation strategies for the pipeline.
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Jelaska, Damir T., Srdjan Podrug, and Srecko Glodez. "Comparison of Numerical Models for Gear Tooth Root Fatigue Assessments." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79891.
Full textAbstract:
A several kinds of numerical models, including moving force model, for determination the service life of gears in regard to bending fatigue in a gear tooth root, is presented. The critical plane damage model, Socie and Bannantine [1], 1988, has been used to determine the number of stress cycles required for the fatigue crack initiation. This method determines also the initiated crack direction, what is good base for a further analyses of the crack propagation and the assessment of the total fatigue life. Finite element method and linear elastic fracture mechanics theories are then used for the further simulation of the fatigue crack growth under a moving load. Moving load produces a non-proportional load history in a gear’s tooth root. An approach that accounts for fatigue crack closure effects is developed to propagate crack under non-proportional load. Although some influences (non-homogeneous material, traveling of dislocations, etc.) were not taken into account in the computational simulations, the presented model seems to be very suitable for determination of service life of gears because numerical procedures used here are much faster and cheaper if compared with the experimental testing. The computational results are compared with other researchers’ numerical results and with service lives of real gears. The fatigue lives and crack paths determined in this paper exhibits a substantial agreement with experimental results and significant improvement compared with the existing numerical models.
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Gilman, Timothy. "Inverse Conduction Method for Complex Thermal Loading." In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84913.
Full textAbstract:
Abstract For U.S. nuclear power plants, transfer functions have typically been utilized in fatigue monitoring applications to characterize a pressure vessel or piping component’s local, inside fluid temperatures, which are the primary forcing functions for stress cycling and the accumulation of fatigue damage, crack nucleation, and crack growth. The transfer function approach involves using simplified, conservative thermal-hydraulic engineering principles to develop algorithms that calculate the local temperatures, using existing plant instruments, such as temperatures, flow rates, valve positions, etc. With the increased ease of adding instrumentation using modern thermocouple and wireless data technology, numerous practical uses are available to plants now, such as: • More accurately and easily characterizing local thermal loading of components for analysis or fatigue monitoring, including flaw tolerance methods. • Determining the inside temperature loading in normally-stagnant branch lines subject to thermal cycling. Accurate knowledge of inside temperatures in these lines can potentially eliminate the need for costly, frequent inspections when a significant temperature range threshold is not exceeded [1] [2]. • Inside temperate loading, based on measured data, can also provide the basis for detailed evaluations in emergent situations when cracks or new loadings are discovered. With thermocouple data, temperatures on the outside surface of components are measured, but inside surface temperatures are needed to compute accurate stresses. There are challenges with attempting to deterministically calculate inside temperatures, because of numerical instability issues caused by temperature fluctuations, measurement inaccuracies, or both. The problem becomes increasingly complex when multiple instruments are required to characterize the loading, such as with thermal stratification or with thermal cycling caused by in-leakage interacting with swirl flow at a branch nozzle. Because of stability challenges and the multivariate nature of the problem, a robust, generalized solution for computing inside temperatures at multiple different thermal zones is nontrivial. Drawing on previous work, this paper discusses the challenge along with a proposed solution.
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Lee, Younggi, Gyeongcheol Lee, Jaeseong Kim, and Boyoung Lee. "High Temperature Characteristics of Lap Joint of 15Cr Ferritic Stainless Steel." In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84132.
Full textAbstract:
Ferritic stainless steels have excellent stress corrosion resistance and a low coefficient of thermal expansion compared to austenitic stainless steels. Ferritic stainless steels of the 400 series have been available for automotive exhaust systems, heat exchangers, radiators etc. in various industries. Automotive exhaust manifolds especially require good heat resistance because the typical operation temperature(800°C) of the exhaust system is exposed to during engine operation. In this study, the effects of high temperature(800°C) characteristics on the mechanical and microstructure properties were investigated for lap joint of ferritic stainless steel(STS 429) mainly used as the automotive exhaust manifolds. The microstructure of lap joint was characterized by optical microscopy(OM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The mechanical property of lap joint was evaluated by tensile test. The tensile test results show that a significant decrease in ultimate tensile strength(between 82 and 85%) was observed for aged STS 429 when tested at the evaluated temperature(800°C). The tensile strength was significantly influenced by growth of grain in the heat affected zone(HAZ). The XRD results show that chromium carbide and chromium nitride phases such as Cr23C6, Cr7C3, Cr2N and TiN were precipitated in the heat affected zone(HAZ).
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Métais, Thomas, Sarah Plessis, The-Hiep Chau, and Jean-Christophe Le Roux. "Evolution of Fatigue Post-Processing Methods in the EDF Open-Access FEA Code ASTER." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63126.
Full textAbstract:
Fatigue is identified as a significant degradation mode that affects nuclear power plants world-wide. The various international codes and standards (ASME, RCC-M, JSME, etc...) offer rules to predict its damaging effect on the locations of the various components of an NPP. These rules, which ensure conservatism and safe operation, have grown in complexity over the years because they have integrated R&D results showing aggravating effects that were not included in the original analyses (such as Environmental Assisted Fatigue [1]) but also because an economically viable design of components has required optimization and refinement of mechanical assessment methods. EDF has been developing since 1989 its own open-source FEA code baptised code ASTER that is included in the Salome Meca mechanical package. Salome Meca is open-access and can be used freely by international users. It is continuously improved with a release at a rate of one new software version per year and it integrates the most recent results obtained by the EDF R&D, in fields as broad as fracture mechanics, XFEM and fatigue. The fatigue post-processing in code ASTER offers a span of criteria (Dang Van, Stress Intensity, etc...) to pick and choose from and even offers the possibility to make up one owns fatigue criteria. It also offers the possibility to post-process fatigue according to the RCC-M rules (POST_RCCM operator). Recent developments have enabled to update the POST_RCCM operator to make it bridge the gap with modern fatigue industrial codes as well as to integrate the EAF calculations per the methodology proposed in [2]. The work is currently ongoing within EDF R&D and will give birth to a stabilized and validated version of the code by end of 2016. This paper presents the updates and the new possibilities of the POST_RCCM operator and gives an update of the work as of early 2016.
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Miura, Naoki, Masaki Nagai, and Masaki Shiratori. "Study on Evaluation Accuracy Required for Stress Intensity Factor Solution." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97563.
Full textAbstract:
Stress intensity factor solutions are often used as a dominant fracture mechanics parameter for fatigue crack growth analysis. In ASME Boiler and Pressure Vessel Code Section XI as well as JSME Rules on Fitness-for-Service for Nuclear Power Plants, fatigue crack growth is predicted on the basis of the stress intensity factor range. Stress intensity factor solutions are frequently provided by the correction factors, which are tabulated as the functions of structure and/or crack sizes. In this study, the effect of the variation of the correction factors on the crack growth analysis results was investigated for pipes with surface cracks. The evaluation accuracy required for the correction factors of the stress intensity factor solutions was then examined and recommended from the comparison with the necessary accuracy of the parameters used for the fatigue crack growth analysis.
Reports on the topic "Growth stress etc as required"
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Tuller, Markus, Asher Bar-Tal, Hadar Heller, and Michal Amichai. Optimization of advanced greenhouse substrates based on physicochemical characterization, numerical simulations, and tomato growth experiments. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600009.bard.
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Over the last decade there has been a dramatic shift in global agricultural practice. The increase in human population, especially in underdeveloped arid and semiarid regions of the world, poses unprecedented challenges to production of an adequate and economically feasible food supply to undernourished populations. Furthermore, the increased living standard in many industrial countries has created a strong demand for high-quality, out-of-season vegetables and fruits as well as for ornamentals such as cut and potted flowers and bedding plants. As a response to these imminent challenges and demands and because of a ban on methyl bromide fumigation of horticultural field soils, soilless greenhouse production systems are regaining increased worldwide attention. Though there is considerable recent empirical and theoretical research devoted to specific issues related to control and management of soilless culture production systems, a comprehensive approach that quantitatively considers all relevant physicochemical processes within the growth substrates is lacking. Moreover, it is common practice to treat soilless growth systems as static, ignoring dynamic changes of important physicochemical and hydraulic properties due to root and microbial growth that require adaptation of management practices throughout the growth period. To overcome these shortcomings, the objectives of this project were to apply thorough physicochemical characterization of commonly used greenhouse substrates in conjunction with state-of-the-art numerical modeling (HYDRUS-3D, PARSWMS) to not only optimize management practices (i.e., irrigation frequency and rates, fertigation, container size and geometry, etc.), but to also “engineer” optimal substrates by mixing organic (e.g., coconut coir) and inorganic (e.g., perlite, pumice, etc.) base substrates and modifying relevant parameters such as the particle (aggregate) size distribution. To evaluate the proposed approach under commercial production conditions, characterization and modeling efforts were accompanied by greenhouse experiments with tomatoes. The project not only yielded novel insights regarding favorable physicochemical properties of advanced greenhouse substrates, but also provided critically needed tools for control and management of containerized soilless production systems to provide a stress-free rhizosphere environment for optimal yields, while conserving valuable production resources. Numerical modeling results provided a more scientifically sound basis for the design of commercial greenhouse production trials and selection of adequate plant-specific substrates, thereby alleviating the risk of costly mistrials.
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Chamovitz, Daniel, and Albrecht Von Arnim. Translational regulation and light signal transduction in plants: the link between eIF3 and the COP9 signalosome. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7696515.bard.
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The COP9 signalosome (CSN) is an eight-subunit protein complex that is highly conserved among eukaryotes. Genetic analysis of the signalosome in the plant model species Arabidopsis thaliana has shown that the signalosome is a repressor of light dependent seedling development as mutant Arabidopsis seedlings that lack this complex develop in complete darkness as if exposed to light. These mutant plants die following the seedling stage, even when exposed to light, indicating that the COP9 signalosome also has a central role in the regulation of normal photomorphogenic development. The biochemical mode of action of the signalosome and its position in eukaryotic cell signaling pathways is a matter of controversy and ongoing investigation, and recent results place the CSN at the juncture of kinase signaling pathways and ubiquitin-mediated protein degradation. We have shown that one of the many CSN functions may relate to the regulation of translation through the interaction of the CSN with its related complex, eukaryotic initiation factor (eIF3). While we have established a physical connection between eIF3 subunits and CSN subunits, the physiological and developmental significance of this interaction is still unknown. In an effort to understand the biochemical activity of the signalosome, and its role in regulating translation, we originally proposed to dissect the contribution of "h" subunit of eIF3 (eIF3h) along the following specific aims: (i) Isolation and phenotypic characterization of an Arabidopsis loss-of-function allele for eIF3h from insertional mutagenesis libraries; (ii) Creation of designed gain and loss of function alleles for eIF3h on the basis of its nucleocytoplasmic distribution and its yeast-two-hybrid interactions with other eIF3 and signalosome partner proteins; (iii) Determining the contribution of eIF3h and its interaction with the signalosome by expressing specific mutants of eIF3h in the eIF3h- loss-of function background. During the course of the research, these goals were modified to include examining the genetic interaction between csn and eif3h mutations. More importantly, we extended our effort toward the genetic analysis of mutations in the eIF3e subunit, which also interacts with the CSN. Through the course of this research program we have made several critical scientific discoveries, all concerned with the apparent diametrically opposed roles of eIF3h and eIF3e. We showed that: 1) While eIF3e is essential for growth and development, eIF3h is not essential for growth or basal translation; 2) While eIF3e has a negative role in translational regulation, eIF3h is positively required for efficient translation of transcripts with complex 5' UTR sequences; 3) Over-accumulation of eIF3e and loss-of-function of eIF3h both lead to cop phenotypes in dark-grown seedlings. These results were published in one publication (Kim et al., Plant Cell 2004) and in a second manuscript currently in revision for Embo J. Are results have led to a paradigm shift in translation research – eIF3 is now viewed in all systems as a dynamic entity that contains regulatory subuits that affect translational efficiency. In the long-term agronomic outlook, the proposed research has implications that may be far reaching. Many important plant processes, including developmental and physiological responses to light, abiotic stress, photosynthate, and hormones operate in part by modulating protein translation [23, 24, 40, 75]. Translational regulation is slowly coming of age as a mechanism for regulating foreign gene expression in plants, beginning with translational enhancers [84, 85] and more recently, coordinating the expression of multiple transgenes using internal ribosome entry sites. Our contribution to understanding the molecular mode of action of a protein complex as fundamental as eIF3 is likely to lead to advances that will be applicable in the foreseeable future.
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Sela, Shlomo, and Michael McClelland. Investigation of a new mechanism of desiccation-stress tolerance in Salmonella. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598155.bard.
Full textAbstract:
Low-moisture foods (LMF) are increasingly involved in foodborne illness. While bacteria cannot grow in LMF due to the low water content, pathogens such as Salmonella can still survive in dry foods and pose health risks to consumer. We recently found that Salmonella secretes a proteinaceous compound during desiccation, which we identified as OsmY, an osmotic stress response protein of 177 amino acids. To elucidate the role of OsmY in conferring tolerance against desiccation and other stresses in Salmonella entericaserovarTyphimurium (STm), our specific objectives were: (1) Characterize the involvement of OsmY in desiccation tolerance; (2) Perform structure-function analysis of OsmY; (3) Study OsmY expression under various growth- and environmental conditions of relevance to agriculture; (4) Examine the involvement of OsmY in response to other stresses of relevance to agriculture; and (5) Elucidate regulatory pathways involved in controlling osmY expression. We demonstrated that an osmY-mutant strain is impaired in both desiccation tolerance (DT) and in long-term persistence during cold storage (LTP). Genetic complementation and addition of a recombinantOsmY (rOsmY) restored the mutant survival back to that of the wild type (wt). To analyze the function of specific domains we have generated a recombinantOsmY (rOsmY) protein. A dose-response DT study showed that rOsmY has the highest protection at a concentration of 0.5 nM. This effect was protein- specific as a comparable amount of bovine serum albumin, an unrelated protein, had a three-time lower protection level. Further characterization of OsmY revealed that the protein has a surfactant activity and is involved in swarming motility. OsmY was shown to facilitate biofilm formation during dehydration but not during bacterial growth under optimal growth conditions. This finding suggests that expression and secretion of OsmY under stress conditions was potentially associated with facilitating biofilm production. OsmY contains two conserved BON domains. To better understand the role of the BON sites in OsmY-mediated dehydration tolerance, we have generated two additional rOsmY constructs, lacking either BON1 or BON2 sites. BON1-minus (but not BON2) protein has decreased dehydration tolerance compared to intact rOsmY, suggesting that BON1 is required for maximal OsmY-mediated activity. Addition of BON1-peptide at concentration below 0.4 µM did not affect STm survival. Interestingly, a toxic effect of BON1 peptide was observed in concentration as low as 0.4 µM. Higher concentrations resulted in complete abrogation of the rOsmY effect, supporting the notion that BON-mediated interaction is essential for rOsmY activity. We performed extensive analysis of RNA expression of STm undergoing desiccation after exponential and stationary growth, identifying all categories of genes that are differentially expressed during this process. We also performed massively in-parallel screening of all genes in which mutation caused changes in fitness during drying, identifying over 400 such genes, which are now undergoing confirmation. As expected OsmY is one of these genes. In conclusion, this is the first study to identify that OsmY protein secreted during dehydration contributes to desiccation tolerance in Salmonella by facilitating dehydration- mediated biofilm formation. Expression of OsmY also enhances swarming motility, apparently through its surfactant activity. The BON1 domain is required for full OsmY activity, demonstrating a potential intervention to reduce pathogen survival in food processing. Expression and fitness screens have begun to elucidate the processes of desiccation, with the potential to uncover additional specific targets for efforts to mitigate pathogen survival in desiccation.
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Mosquna, Assaf, and Sean Cutler. Systematic analyses of the roles of Solanum Lycopersicum ABA receptors in environmental stress and development. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604266.bard.
Full textAbstract:
Drought and other abiotic stresses have major negative effects on agricultural productivity. The plant hormone abscisic acid (ABA) regulates many responses to environmental stresses and can be used to improve crop performance under stress. ABA levels rise in response to diverse abiotic stresses to coordinate physiological and metabolic responses that help plants survive stressful environments. In all land plants, ABA receptors are responsible for initiating a signaling cascade that leads to stomata closure, growth arrest and large-scale changes in transcript levels required for stress tolerance. We wanted to test the meaning of root derived ABA signaling in drying soil on water balance. To this end we generated transgenic tomato lines in which ABA signaling is initiated by a synthetic agonist- mandipropamid. Initial study using a Series of grafting experiments indicate that that root ABA signaling has no effect on the immediate regulation of stomata aperture. Once concluded, these experiments will enable us to systematically dissect the physiological role of root-shoot interaction in maintaining the water balance in plants and provide new tools for targeted improvement of abiotic stress tolerance in crop plants.
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Amir, Rachel, David J. Oliver, Gad Galili, and Jacline V. Shanks. The Role of Cysteine Partitioning into Glutathione and Methionine Synthesis During Normal and Stress Conditions. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7699850.bard.
Full textAbstract:
The objective of this research is to study the nature of the competition for cysteine (Cys), the first organic sulfur-containing compound, between its two main metabolites, glutathione (GSH) and methionine (Met). GSH plays a central role in protecting plants during various stresses, while Met, an essential amino acid, regulates essential processes and metabolites in plant cells through its metabolite S-adenosyl-Met. Our results, which are based on flux analysis and measurements of Met- metabolites, show that the flux towards Met synthesis is high during non-stress conditions, however the flux is significantly reduced under stress conditions, when there is high synthesis of GSH. Under oxidative stress the expression level of the regulatory enzyme of Met synthesis, cystathionine g-synthase (CGS) was reduced. By using three different systems, we have found that that GSH down regulates the expression level of CGS, thus reducing Met synthesis. We have found that this regulation occurs at the post-transcriptional level, and further studies have shown that it occurs at post-translationaly. To reveal how oxidative stress affects the flux towards Met and GSH, flux analysis was performed. We have found that the level of Met is significantly reduced, while the level of glutathione significantly increases during stress. Under stress conditions most of the glutathione is converted from GSH to GSSG (the oxidised form of glutathione). These results suggest that under normal growth conditions, Cys is channelled towards both pathways to support GSH accumulation and the synthesis of growth-essential Met metabolites. However, during oxidative stress, when a high level of GSH is required to protect the plants, the levels of GSH increase while those of CGS are reduced. This reduction leaves more Cys available for GSH synthesis under stress conditions. In addition we have also studied the effects of high GSH level on the transcriptome profile. The analysis revealed that GSH affects the expression level of many major genes coding to enzymes or proteins associated with photosynthesis, starch degradation, hormone metabolism (especially genes associated with jasmonate), biotic stress (especially genes associated with PR-proteins), cytochrome P450 genes, regulation of transcription and signaling (especially genes associated with receptor kinases and calcium). These results suggest that indeed GSH levels affect different pathways and metabolites in plants.
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Horwitz, Benjamin A., and Barbara Gillian Turgeon. Fungal Iron Acquisition, Oxidative Stress and Virulence in the Cochliobolus-maize Interaction. United States Department of Agriculture, March 2012. http://dx.doi.org/10.32747/2012.7709885.bard.
Full textAbstract:
Our project focused on genes for high affinity iron acquisition in Cochliobolus heterostrophus, a necrotrophic pathogen of maize, and their intertwined relationship to oxidative stress status and virulence of the fungus on the host. An intriguing question was why mutants lacking the nonribosomal peptide synthetase (NRPS) gene (NPS6) responsible for synthesis of the extracellular siderophore, coprogen, are sensitive to oxidative stress. Our overall objective was to understand the mechanistic connection between iron stress and oxidative stress as related to virulence of a plant pathogen to its host. The first objective was to examine the interface where small molecule peptide and reactive oxygen species (ROS) mechanisms overlap. The second objective was to determine if the molecular explanation for common function is common signal transduction pathways. These pathways, built around sensor kinases, response regulators, and transcription factors may link sequestering of iron, production of antioxidants, resistance to oxidative stress, and virulence. We tested these hypotheses by genetic manipulation of the pathogen, virulence assays on the host plant, and by following the expression of key fungal genes. An addition to the original program, made in the first year, was to develop, for fungi, a genetically encoded indicator of redox state based on the commercially available Gfp-based probe pHyper, designed for animal cell biology. We implemented several tools including a genetically encoded indicator of redox state, a procedure to grow iron-depleted plants, and constructed a number of new mutants in regulatory genes. Lack of the major Fe acquisition pathways results in an almost completely avirulent phenotype, showing how critical Fe acquisition is for the pathogen to cause disease. Mutants in conserved signaling pathways have normal ability to regulate NPS6 in response to Fe levels, as do mutants in Lae1 and Vel1, two master regulators of gene expression. Vel1 mutants are sensitive to oxidative stress, and the reason may be underexpression of a catalase gene. In nps6 mutants, CAT3 is also underexpressed, perhaps explaining the sensitivity to oxidative stress. We constructed a deletion mutant for the Fe sensor-regulator SreA and found that it is required for down regulation of NPS6 under Fe-replete conditions. Lack of SreA, though, did not make the fungus over-sensitive to ROS, though the mutant had a slow growth rate. This suggests that overproduction of siderophore under Fe-replete conditions is not very damaging. On the other hand, increasing Fe levels protected nps6 mutants from inhibition by ROS, implying that Fe-catalyzed Fenton reactions are not the main factor in its sensitivity to ROS. We have made some progress in understanding why siderophore mutants are sensitive to oxidative stress, and in doing so, defined some novel regulatory relationships. Catalase genes, which are not directly related to siderophore biosynthesis, are underexpressed in nps6 mutants, suggesting that the siderophore product (with or without bound Fe) may act as a signal. Siderophores, therefore, could be a target for intervention in the field, either by supplying an incorrect signal or blocking a signal normally provided during infection. We already know that nps6 mutants cause smaller lesions and have difficulty establishing invasive growth in the host. Lae1 and Vel1 are the first factors shown to regulate both super virulence conferred by T-toxin, and basic pathogenicity, due to unknown factors. The mutants are also altered in oxidative stress responses, key to success in the infection court, asexual and sexual development, essential for fungal dissemination in the field, aerial hyphal growth, and pigment biosynthesis, essential for survival in the field. Mutants in genes encoding NADPH oxidase (Nox) are compromised in development and virulence. Indeed the triple mutant, which should lack all Nox activity, was nearly avirulent. Again, gene expression experiments provided us with initial evidence that superoxide produced by the fungus may be most important as a signal. Blocking oxidant production by the pathogen may be a way to protect the plant host, in interactions with necrotrophs such as C. heterostrophus which seem to thrive in an oxidant environment.
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Dudley, Lynn M., Uri Shani, and Moshe Shenker. Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586468.bard.
Full textAbstract:
Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.
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Veilleux, Richard, and David Levy. Potato Germplasm Development for Warm Climates. United States Department of Agriculture, October 1992. http://dx.doi.org/10.32747/1992.7561057.bard.
Full textAbstract:
Complex potato hybrids derived from crosses between cv. Atlantic and 11 clones of three genomic compositions, all with an unadapted component from previously identified heat tolerant accessions, were evaluated in the field in Israel and Virginia and in controlled environments in Israel. Heat tolerance was exhibited in the field by the ability of many of these hybrids to tuberize under severe heat stress when cv. Atlantic did not tuberize at all. The complex hybrids also exhibited fewer internal defects (heat necrosis, hollow heart) than Atlantic. Studies to determine if heat stress applied during anther culture or to pollen samples prior to pollination could affect gametic selection towards more heat tolerant progenies were also undertaken. There was some evidence of greater heat tolerance (longer survival under heat stress) in the anther-derived population that had been regenerated under heat stress. The seedlings resulting from crosses with heat-treated pollen also exhibited greater haulm growth under heat stress compared with controls. However, the poor adaption of the germplasm prevented a firm conclusion about gametic selection. The introduction of exotic germplasm into cultivated potato has considerable potential to adapt potato to nontraditional growing seasons and climates. However, such hybrids will require continued selection and evaluation to retain the traits required for commercial production.
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Guy, Charles, Gozal Ben-Hayyim, Gloria Moore, Doron Holland, and Yuval Eshdat. Common Mechanisms of Response to the Stresses of High Salinity and Low Temperature and Genetic Mapping of Stress Tolerance Loci in Citrus. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7613013.bard.
Full textAbstract:
The objectives that were outlined in our original proposal have largely been achieved or will be so by the end of the project in February 1995 with one exception; that of mapping cold tolerance loci based on the segregation of tolerance in the BC1 progeny population. Briefly, our goals were to 1) construct a densely populated linkage map of the citrus genome: 2) map loci important in cold and/or salt stress tolerance; and 3) characterize the expression of genes responsive to cold land salt stress. As can be seen by the preceding listing of accomplishments, our original objectives A and B have been realized, objective C has been partially tested, objective D has been completed, and work on objectives E and F will be completed by the end of 1995. Although we have yet to map any loci that contribute to an ability of citrus to maintain growth when irrigated with saline water, our very encouraging results from the 1993 experiment provides us with considerable hope that 1994's much more comprehensive and better controlled experiment will yield the desired results once the data has been fully analyzed. Part of our optimism derives from the findings that loci for growth are closely linked with loci associated with foliar Cl- and Na+ accumulation patterns under non-salinization conditions. In the 1994 experiment, if ion exclusion or sequestration traits are segregating in the population, the experimental design will permit their resolution. Our fortunes with respect to cold tolerance is another situation. In three attempts to quantitatively characterize cold tolerance as an LT50, the results have been too variable and the incremental differences between sensitive and tolerant too small to use for mapping. To adequately determine the LT50 requires many plants, many more than we have been able to generate in the time and space available by making cuttings from small greenhouse-grown stock plants. As it has turned out, with citrus, to prepare enough plants needed to be successful in this objective would have required extensive facilities for both growing and testing hardiness which simply were not available at University of Florida. The large populations necessary to overcome the variability we encountered was unanticipated and unforeseeable at the project's outset. In spite of the setbacks, this project, when it is finally complete will be exceedingly successful. Listing of Accomplishments During the funded interval we have accomplished the following objectives: Developed a reasonably high density linkage map for citrus - mapped the loci for two cold responsive genes that were cloned from Poncirus - mapped the loci for csa, the salt responsive gene for glutathione peroxidase, and ccr a circadian rhythm gene from citrus - identified loci that confer parental derived specific DNA methylation patterns in the Citrus X Poncirus cross - mapped 5 loci that determine shoot vigor - mapped 2 loci that influence leaf Na+ accumulation patterns under non-saline conditions in the BC1 population - mapped 3 loci that influence leaf Na+ accumulation paterns during salt sress - mapped 2 loci that control leaf Cl- accumulation patterns under non-saline conditions - mapped a locus that controls leaf Cl- accumulation patterns during salt stress Screened the BC1 population for growth reduction during salinization (controls and salinized), and cold tolerance - determined population variation for shoot/root ratio of Na+ and Cl- - determined levels for 12 inorganic nutrient elements in an effort to examine the influence of salinization on ion content with emphasis on foliar responses - collected data on ion distribution to reveal patterns of exclusion/sequestration/ accumulation - analyzed relationships between ion content and growth Characterization of gene expression in response to salt or cold stress - cloned the gene for the salt responsive protein csa, identified it as glutathione peroxidase, determined the potential target substrate from enzymatic studies - cloned two other genes responsive to salt stress, one for the citrus homologue of a Lea5, and the other for an "oleosin" like gene - cold regulated (cor) genes belonging to five hybridization classes were isolated from Poncirus, two belonged to the group 2 Lea superfamily of stress proteins, the others show no significant homology to other known sequences - the expression of csa during cold acclimation was examined, and the expression of some of the cor genes were examined in response to salt stress - the influence of salinization on cold tolerance has been examined with seedling populations - conducted protein blot studies for expression of cold stress proteins during salt stress and vice versa
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Yahav, Shlomo, John Brake, and Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, September 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
Full textAbstract:
: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.