Academic literature on the topic 'Cations under stress conditions'
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Journal articles on the topic "Cations under stress conditions"
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Melkani, Girish C., Robin L. Sielaff, Gustavo Zardeneta, and Jose A. Mendoza. "Divalent cations stabilize GroEL under conditions of oxidative stress." Biochemical and Biophysical Research Communications 368, no. 3 (2008): 625–30. http://dx.doi.org/10.1016/j.bbrc.2008.01.126.
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Sergeeva, L. E., and L. I. Bronnikova. "Cell selection with heavy metal ions for obtaining wheat and maize forms tolerant to osmotic stresses." Faktori eksperimental'noi evolucii organizmiv 22 (September 9, 2018): 318–22. http://dx.doi.org/10.7124/feeo.v22.968.
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Aim. The obtaining tolerant to salt and water stresses wheat and maize variants via cell selection with barium and cadmium heavy metal cations were the idea. Barium cations disrupt the cell potassium transport. Cadmium cations affect the dehydrins. The maintenance of these parameters under stress conditions provides the plant tolerance. Methods. Modified media for initial selection were developed by the supplement of the lethal doses of heavy metal ions. Wheat and maize suspension cultures were plated on selective media. The relative fresh biomass growth was the marker of variant stress tolerance. Results. Ba-resistant and Cd‑resistant plant cell lines were obtained. Those variants were tested under salinity and water stress pressure at lethal for wild type cells doses. Cell lines demonstrated the combined tolerance to abiotic stresses. Conclusions. The cell selection with heavy metal ions – is a new approach for isolation cell variants with higher levels of osmotic stresses tolerance.
 Keywords: cereals, osmotic stresses, cell selection with heavy metal ions, combined tolerance.
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Igamberdiev, Abir U., and Leszek A. Kleczkowski. "Magnesium and cell energetics in plants under anoxia." Biochemical Journal 437, no. 3 (2011): 373–79. http://dx.doi.org/10.1042/bj20110213.
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Stress conditions (e.g. anoxia) frequently result in a decrease of [ATP] and in an increase of [ADP] and [AMP], with a concomitant increase of [Mg2+] and other cations, e.g. Ca2+. The elevation of [Mg2+] is linked to the shift in the apparent equilibrium of adenylate kinase. As a result, enzymes that use Mg2+ as a cofactor are activated, Ca2+ activates calcium-dependent signalling pathways, and PPi can serve as an alternative energy source in its active form of MgPPi or Mg2PPi. Under anoxic conditions in plants, an important source of PPi may come as a result of combined reactions of PK (pyruvate kinase) and PPDK (pyruvate, phosphate dikinase). The PPi formed in the PPDK/PK cycle ignites glycolysis in conditions of low [ATP] by involving PPi-dependent reactions. This saves ATP and makes metabolism under stress conditions more energy efficient.
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JANZEN, H. H., and C. CHANG. "CATION NUTRITION OF BARLEY AS INFLUENCED BY SOIL SOLUTION COMPOSITION IN A SALINE SOIL." Canadian Journal of Soil Science 67, no. 3 (1987): 619–29. http://dx.doi.org/10.4141/cjss87-058.
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Identification of nutritional disorders in crops growing on saline soils may facilitate the development of breeding or agronomic practices that improve yields in saline areas. An investigation was conducted under controlled environment conditions to identify possible cation deficiencies in barley (Hordeum vulgare 'Gait') grown under sulfate-dominated salinity stress. Soil was artificially salinized to produce a factorial of five salinity levels (ranging from approximately 6.5 to 17.5 dS m−1) and five salt types containing various ratios of Na:Mg:Ca. A control treatment (3.1 dS m−1) was also included. Barley was grown for 75 d and harvested for analysis of dry matter yield and tissue composition. Yield response of barley to salinity stress was not differentially affected by the type of salt used in salinization. Concentrations of sodium and magnesium in the plant tissue were generally increased by salinity stress, but these accumulations did not restrict yield since no consistent relationship was found between the concentrations of these cations and barley yield. Potassium concentration in the plants was inversely related to level of soil salinity, apparently because of an antagonistic effect of sodium, but was not consistently related to barley dry matter yield. Calcium uptake was also suppressed by soil salinity. In contrast to the results observed for other cations, a very strong relationship indicative of a yield response curve was observed between yield and calcium concentration in the plant tissue, particularly when the latter was expressed as a ratio of total cation concentration (R2 = 0.94). Furthermore, calcium concentration in the plant tissue and estimated calcium activity in the soil solution in highly salinized treatments were well below those considered adequate. These results suggest that calcium deficiency may have played an important role in restricting yield under salinity stress. The apparent calcium deficiency induced by salinity stress was attributed to reduced activity of calcium in the soil solution because of precipitation with sulfate and high ionic strength. Key words: Calcium, magnesium, potassium, sodium, salinity
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LLINARES, Josep V., Inmaculada BAUTISTA, Maria del Pilar DONAT, et al. "Responses to Environmental Stress in Plants Adapted to Mediterranean Gypsum Habitats." Notulae Scientia Biologicae 7, no. 1 (2015): 37–44. http://dx.doi.org/10.15835/nsb719537.
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Gypsum areas are stressful environments inhabited by gypsophytes, plants that are exclusive for such habitats, and by plants that grow on gypsum but also on other soil types, the so-called gypsovags. To investigate possible differences between gypsovags and gypsophytes with respect to basic stress response mechanisms, two common osmolytes, glycine betaine and total soluble sugars, as well as monovalent (Na+ and K+) and bivalent (Ca2+ and Mg2+) cations, were quantified, under field conditions, in two Iberian endemic gypsophytes (Gypsophila struthium subsp. hispanica and Ononis tridentata) and two common Mediterranean gypsovags (Rosmarinus officinalis and Helianthemum syriacum). Their spatial variation according to a topographic gradient and their temporal variation over a period of three successive seasons were correlated with climatic data and soil characteristics. This analysis confirmed that water stress is the main environmental stress factor in gypsum habitats, whereas the percentage of gypsum in the soil does not seem to play any relevant role in the activation of stress responses in plants. Glycine betaine may contribute to stress tolerance in the gypsophytes, but not in the gypsovags, according to the close correlation found between the level of this osmolyte and the gypsophily of the investigated taxa. Cation contents in the plants did not correlate with those present in the soil, but the gypsophytes have higher levels of Ca2+ and Mg2+ than the gypsovags, under all environmental conditions, which may represent an adaptation mechanism to their specific habitat.
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Sergeeva, L. E., M. O. Dykun, and L. I. Bronnikova. "Protein status of winter wheat cell lines with combined tolerace to abiotic stresses." Faktori eksperimental'noi evolucii organizmiv 26 (September 1, 2020): 259–63. http://dx.doi.org/10.7124/feeo.v26.1276.
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Aim. Winter wheat cell lines were selected on medium with the addition of lethal doses of Cd2+ cations. Those variants demonstrated stable growth under osmotic stress pressure. The aim of the investigation was the estimation of cell protein status during cultivation under various conditions. Methods. Cd-resistant cell lines of winter wheat (cv. Favoritka) were cultivated under normal conditions and on cultural media with addition of lethal doses of manitol or Cd2+ (stresses I, II). From calli tissues crude protein matter was obtained and detected by Laemmli system electrophoresis. Results. Cd-resistant winter cell lines showed stable growth under any abiotic stress pressure. Electrophoregrams demonstrated peculiar features of some protein fraction accumulation that correlated with the age of cultures and type of stress agent. Conclusions. There were no decrease of total protein pools in calli tissues during cell cultivation under any (manitol, Cd2+) lethal stress pressure. The quantitative accumulation of some protein fractions were correlated with the type of stress agent. This event was especially manifested in variants, cultivated on media with manitol addition. Protein status of Cd-resistant cell lines of winter wheat is the reflection of their combined stress tolerance.
 Keywords: winter wheat, cell selection, cadmium ions, osmotic stress, tolerant cell line, protein.
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A, ARJUNAN, SRINIVASAN P.S, and VINDIYAVARMAN P. "PHYSIOLOGICAL ASPECTS OF DROUGHT TOLERANCE IN GROUNDNUT (Arachis hypogala L.)." Madras Agricultural Journal 75, January febuary (1988): 5–8. http://dx.doi.org/10.29321/maj.10.a02081.
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The groundnut cultivars viz., VG 77. JL 24 and CO 2 possess greater drought tolerance characters like higher root-shoot ratios, accumulations of cations. K+ in parti- cular. These characters have contributed for the higher pod yields in groundnut under moisture stress conditions. Thus K+ content in the leaf can also be considered as one of the criteria for the drought tolerance in groundnut.
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Zhukova, G. V., O. S. Sutormin, L. V. Stepanova, and V. A. Kratasyuk. "Forecast of Professional Success of Employee under Stress Factor: A New Approach." Fiziologiâ čeloveka 50, no. 5 (2024): 87–94. http://dx.doi.org/10.31857/s0131164624050092.
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A new personalized approach is proposed to predict the professional suitability of railway transport workers under the influence of stressful factors, based on the study of the effect of salivary fluid of subjects before and after a work shift on the intensity of the glow of the bioenzyme reaction of luminous bacteria: NADH:FMN-oxidoreductase+luciferase. The integral method, which signals the magnitude of the stress effect, is based on changes in saliva components such as lactate, ions and cations, as well as nitrate and sulfate chlorides under the influence of stress. This made it possible to identify, using the example of Russian Railways dispatchers, a risk group and a group of stress-resistant workers, which is important to reduce accidents at Russian Railways. The conditions that reduce the stressful workload necessary for the development of effective measures for the prevention of stressful situations and the preservation of workers’ ability to work have been identified.
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Anna, Hadam, Wrochna Mariola, and Karaczun Zbigniew. "Effect of hydrogel on the turf grass species growing under salt stress." Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation 43, no. 1 (2011): 47–55. http://dx.doi.org/10.2478/v10060-008-0092-4.
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Effect of hydrogel on the turf grass species growing under salt stress Hydrogels can absorb huge amount of water and so are able to decrease the drought stress in plants. They are used in horticulture and agriculture for years. It is possible that they may be applied also on the grass near - road areas. Because of water deficient and high salinity growth of plants in these conditions is however hard. Meanwhile, too high concentration of ions in soil can decrease efficacy of hydrogel, since it can absorb water and cations as well. Nevertheless there is still too less studies on such problem. From this point of view it seems that the complex assessment of hydrogels effect on urban lawn grass is needed. The aim of the study was therefore the evaluation of grasses condition after their cultivation under salt stress with and without hydrogels amendment. Experience was conducted for four months in the controlled green house conditions. The efficacy of hydrogels amendment was measured by the grass reactions (turfs height, fresh matter content and level of membranes injury) on three levels of salinity. The results allowed concluding that, concentration of the road de- icing salt was the main factor, which affected condition of all tested species. This reaction was independent on the presence of hydrogel. Nevertheless under low and medium saline conditions watersorbent weakened significantly influence of salt stress on the grass.
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KUHLMAN, Philip A. "Characterization of the actin filament capping state in human erythrocyte ghost and cytoskeletal preparations." Biochemical Journal 349, no. 1 (2000): 105–11. http://dx.doi.org/10.1042/bj3490105.
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The narrow Gaussian-length-distribution of actin filaments forming the cytoskeleton of the human erythrocyte indicates the existence of strict mechanisms for length determination and maintenance. A similar regulation is achieved in striated muscle by the capping of both the ends of the thin filaments, which consequently prevents monomer exchange. However, the ability of erythroid cytoskeletal preparations to nucleate actin polymerization has led to the proliferation of the idea that at least the barbed ends of the actin filaments are uncapped. The mechanism by which the length of the filaments is thus maintained has been left open to debate. In an effort to resolve any doubt regarding length-maintenance in human erythrocytes we have characterized the capping state of the actin filaments in a number of different ghost and cytoskeletal preparations. Under conditions of sufficiently high bivalent-cation concentration the actin filaments retain functional caps at both the barbed and pointed ends. Hence filament capping at both ends prevents redistribution of the actin monomer in a similar manner to that proposed for the thin filaments of striated muscle. Actin filament uncapping is apparently caused by the centrifugal shearing stress imposed during ghost preparation. The uncapping is more pronounced when the bivalent-cation concentration is reduced or when the membrane is removed by detergents. The effects of bivalent cations seem to be mediated through the erythroid protein spectrin, consistent with the hypothesis of Wallis et al. [Wallis, Babitch and Wenegieme (1993) Biochemistry 32, 5045-5050] that the ability of spectrin to resist shearing stress is dependent on the degree of bound bivalent cations.
Dissertations / Theses on the topic "Cations under stress conditions"
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Rose, A. P. G. "Fracture of graphite under different stress conditions." Thesis, University of Bath, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353402.
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Hackston, Abigail Jane. "Activation of faulting under controlled stress conditions." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/activation-of-faulting-under-controlled-stress-conditions(2eb0b3f9-33c4-43d3-bbf2-490744f94d23).html.
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In 1951, it was first suggested by E.M. Anderson that faults in nature will form at specific angles to the maximum principal stress. For most cases, this concept agrees with observations. However, in nature there are some notable exceptions to this rule, with some faults becoming activated in unfavourable orientations. This project was designed to examine conditions that might affect the angle of faulting and the friction coefficient for sliding. Faults that do not conform to generally accepted ‘Andersonian’ theory include low-angle detachment faults (e.g. Basin and Range Province (USA)), the San Andreas Fault (USA) the Nordfjord Sojn Detachment (Norway), high angle (steeply dipping) normal faults (Britain) and the Zuccale Fault, Italy. Various explanations have been given for sliding on these unfavourably-oriented faults, including high pressure CO2 or water infiltration (Zuccale Fault), low-friction minerals growing in fault gouge (Zuccale fault, San Andreas Fault), stress refraction (San Andreas Fault), reactivation of thrust faults (Nordfjord Sojn Detachment) and fracture under a combination of compression and tension (UK).Experiments were performed in compression and extension using a triaxial deformation rig. Darley Dale sandstone and Pennant sandstone blocks were cut into cores and tested under the following conditions: (a) intact rock failure (dry); (b) sawcut at 35°, 45° and 55° (dry) to the core axis using (i) constant confining pressure, (ii) constant normal stress (iii) constant mean stress; (c) with pore pressure in all three sawcut angles; and (d) with a gouge layer of 70% quartz to 30% kaolinite mixed with 0, 2, 5, 10, 20, 50 and 100% wt of either graphite or talc. Microstructural studies were carried out on deformed samples. These experiments showed that: The angle of failure in extension was 16-20° to the maximum principal stress for Darley Dale sandstone, and 18-21° for Pennant sandstone whereas in compression it was >30°. This angle in extension is lower than expected, but microstructural analysis indicated occurrence of stress refraction, which may help explain this result. The friction coefficient does not appear to change with pre-cut fault angle in dry samples. Pore pressure tests confirmed the general applicability of the law of effective stress, but anomalous apparent reduction of friction coefficient and production of an apparent cohesive strength in pore pressure tests suggested tests should be run slower to avoid disparity between applied pore pressure and true pore pressure in the sample. Attempts to induce hydraulic fractures showed that high overpressures may often be required to do this. Addition of a low-friction phase (talc or graphite) to fault gouge reduced friction by a disproportionately large amount for very planar faults. This was shown to be due to mechanical smearing of the weak phase over the fault plane, increasing its apparent area of coverage. It was concluded that commonly some combination of high fluid pressure in fault planes coupled with low-friction fault gouges may be required to explain slip on natural, unfavourably –oriented faults.
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Ambrose, Jasmin. "Failure of anisotropic shales under triaxial stress conditions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/19270.
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Shales are highly anisotropic in their mechanical behaviour. The strength of anisotropic shales depends not only on the magnitude of the principal stresses, but also on the bedding plane orientations relative to the principal stresses. In this study, the failure of shales are investigated using triaxial compression and extension tests, while the role of intermediate stress (sigma2) on the strength of anisotropic shale is evaluated using data from new triaxial extension tests, as well as data from the literature. Triaxial compression and extension experiments were made on two organic-rich shales, at different confining stresses and bedding angles (Beta). Examination of post-failure computed tomography (CT) and thin section images for high strength anisotropy shale show that, for large and small values of Beta, the fracture plane follows the angle that is predicted by the Coulomb’s failure criterion for an isotropic material. In the range of angles of roughly 35deg.<Beta<75deg, failure occurs along the bedding plane. Both of these results are consistent with the assumptions of Jaeger’s plane of weakness (JPW) model. However, there exists a transition regime of loading angles lying between about 10deg. and 35deg., wherein the failure surface follows an irregular path that may jump between the bedding plane and the plane defined by the Coulomb criterion. In this regime, the strength of the rock is lower than the strength predicted by JPW model. For the shale with low strength anisotropy, the failure plane angles agree with the predictions of JPW model. The triaxial compression experimental data on shales and several data sets from the literature were fit with both Pariseau’s continuum model for the failure of transversely isotropic materials and JPW model. Comparison of both models show that the Pariseau model provided a better fit for ten of the twelve rocks, whereas the JPW model provided a better fit only for two low strength anisotropy shales. It was noted that all the rocks with a strength anisotropy ratio (SAR) > 2 were fit more closely by the Pariseau model, whereas both shales that were a better fit with the JPW model had SAR < 2. Pariseau’s model is also more robust and accurate than Jaeger’s model when using a reduced numbers of data (i.e., data collected at fewer confining stresses and/or fewer angles). Finally, both the JPW model and Pariseau’s model was applied in the true-triaxial stress regime, in which sigma1 > sigma2 > sigma3. When analysed with Mogi’s experimental data on Chichibu Schist, both models could predict failure under true-triaxial stress conditions. Mogi’s data and the triaxial extension experiments for the two shales shows that an increase in the intermediate stress sigma2 increases the intact rock strength, whereas weak plane failure depends not only on intermediate stress sigma2, but also on bedding plane angle Beta and foliation direction (omega).
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Younessi, Sinaki Ahmad Reza. "Sand production simulation under true-triaxial stress conditions." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1133.
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Sand production in weakly consolidated sandstone reservoirs could result in damaging the production and surface facilities. Sanding includes two stages: the failure of sandstone around the borehole and sand grains being transported into the borehole. The first stage is related to stresses around the borehole whereas the second one is controlled by drawdown pressure. In order to avoid sanding, the stresses around the borehole and the drawdown pressure which initiate sanding are studied.This research simulated sand production through laboratory experiments and numerical simulations. The effect of three independent far-field stresses was investigated which is contrary to most of the current studies being performed under a uniaxial or triaxial stress state. Accordingly, a unique experimental setup and procedure was introduced to conduct sand production experiments under true-triaxial stress conditions. The effect of drawdown pressure and state of far-field stresses on the sanding mechanism and development of the failure zone around a borehole were investigated. The experiments were conducted on 100×100×100 mm3 cubic samples of synthetic sandstones. The samples were manufactured using an established procedure developed to produce samples with properties similar to weakly consolidated sandstone. The properties of the synthetic sandstone samples were determined by conducting a series of standard rock mechanics tests on cylindrical plugs. Using a true-triaxial stress cell (TTSC), cubic samples were subjected to three independent boundary stresses and uniform lateral fluid flow from the outer boundaries. The fluid flows through the sample radially and discharges from a hole drilled at the centre of the sample: this allows the study of sanding initiation by changing the state of stress, sample material and fluid properties.In this research, firstly, the concept of sand production from a geomechanics point of view and a summary of previous sanding experiments are explained. Thereafter, the procedure to prepare a sample suitable for sand production experiments is provided. Subsequently, the experimental equipment, setup and procedure are explained in detail. This is followed by presenting the results of two sets of experiments performed at different states of stress. The effect of changing the lateral stresses on the development of the failure zone around borehole was investigated in these experiments. During these experiments it was observed that a minimum drawdown pressure is needed to initiate sand production, regardless of the state of the boundary stresses. In addition, it was observed that the geometry (i.e. width and depth) of the failure zone developed around the borehole is a function of the state of stresses.The experiments were also simulated numerically using ABAQUS in order to gain a better understanding of sand production mechanisms. The numerical modelling procedure and results are presented in a separate section in this thesis. Good agreement was obtained between the results of both experimental and numerical methods which confirm the importance of the state of stresses on the evolution of sanding. Based on the experimental and numerical observations, it was shown that the effect of the magnitude of the maximum lateral stress on the depth of failure is more significant than the minimum lateral stress.
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Chen, Chenglu. "Regulation of Escherichia coli RNase R under Stress Conditions." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/307.
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Upon encountering stress conditions, cells must rapidly alter their gene expression and re-model their RNA complement to deal with the changing environment. As a consequence, both new RNA transcription as well as RNA degradation must take place. Accordingly, the RNA degradative machinery may adjust to the changes in RNA metabolism. Thus, a study of the response of the three major degradative exoribonucleases in Escherichia coli, polynucleotide phosphorylase, RNase II, and RNase R, to stress is of significant importance. RNase R, a processive 3' to 5' exoribonuclease, is unique among the known E. coli exoribonucleases in its ability to digest through RNAs containing extensive secondary structure without the aid of a helicase. In vivo, RNase R plays important roles in quality control of stable RNA, decay of mRNA with extensive repetitive extragenic palindromic (REP) sequences, cell-cycle regulated degradation of tmRNA in Caulobacter crescentus, as well as processing of rRNA under low temperature in P. syringae. In this dissertation, RNase R was shown to be unusual among the E. coli exoribonucleases in its dramatic response to a variety of stress conditions. Elevation of RNase R activity by as much as 10-fold was observed in response to entry into stationary phase, starvation and cold shock, and an ~3-fold increase was seen during growth in minimal medium compared to rich medium. The elevation in RNase R activity was associated with an increase in RNase R protein. Phenotypes of rnr mutants were also investigated, and RNase R was found to contribute to cell growth and viability. Further investigation of the regulation of RNase R during stress, primarily in stationary phase, revealed a novel regulation mechanism. Despite the large increase in RNase R protein and activity in stationary phase, rnr message actually decreased to only ~14% of its level in exponential phase. Further study revealed that RNase R is highly unstable in exponential phase and becomes stabilized during stationary phase, cold shock, and in minimal medium. Investigation of proteolysis on the unusual instability of RNase R indicated that both Lon and ClpXP play a role. In the absence of Lon, RNase R stability is increased ~10-fold. Based on these results, I propose that the increase in RNase R during stress is due to its enhanced stability under those conditions.
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Pereira, Jorge. "Deciphering the role of Yap4 phosphorylation under stress conditions." Doctoral thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica, 2008. http://hdl.handle.net/10362/4075.
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The existence of molecular mechanisms of response, repair and
adaptation, many of which are greatly conserved across nature, gives
to the cell with the plasticity it requires to adjust to its ever-changing
environment, a homeostatic event that is termed the stress response.
In the budding yeast Saccharomyces cerevisiae there is a particular
family of transcription factors, the Yap family, which has been shown
to have a relevant role in yeast adaptation to several stress
conditions. In particular, Yap1 is the major regulator of the
transcriptional response to oxidative stress and Yap2 and Yap8 play
important roles upon cadmium and arsenic exposure, respectively.(...)
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Zdravkovic, Lidija. "The stress-strain-strength anisotropy of a granular medium under general stress conditions." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8919.
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Watz, Johan. "Salmonid behaviour under winter conditions." Doctoral thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-38354.
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Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are relatively active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. In this doctoral thesis, I report the results from experimental field and laboratory studies on the behavioural ecology of juvenile salmonids under winter conditions. My results from the field show that salmonids grow more and use a broader range of habitats in the presence of surface ice than in its absence. Results from the laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions. These laboratory results may explain the positive effects of ice cover on growth that was found in the field experiment. Moreover, I show that drift-feeding ability is reduced at low temperatures, and that nocturnal drift foraging under winter conditions has a low efficiency.<br>Vinterförhållanden kan spela en avgörande roll för förekomsten av fisk i våra vattendrag. Laxfiskar, som till exempel lax, öring och harr, är vinteraktiva och måste därför anpassa sin fysiologi och sitt beteende till en miljö som karakteriseras av låga och föränderliga vattenflöden, liten tillgång på föda, kallt vatten, is och mörker. Trots att dessa anpassningar är avgörande för chansen att överleva vintern, vet man relativt lite om laxfiskars vinterbeteende, speciellt i vattendrag som täcks av is. I denna avhandling presenterar jag resultat från fält- och laboratoriestudier av laxfiskars beteende under vinterförhållanden och resultaten visar att närvaron av yttäckande is ökar tillväxt och födointag, minskar stress samt påverkar var fiskar uppehåller sig och hur fiskarna interagerar med varandra. Jag har också undersökt hur laxfiskars beteende i rinnande vatten påverkas av ljusintensitet och vattentemperatur i samband med födointag. Resultaten visar att den minskade dagaktiviteten som laxfiskar uppvisar på vintern medför en kostnad i form av försämrad förmåga att fånga byten.<br>Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. This doctoral thesis focuses on the behavioural ecology of salmonids under winter conditions, and results from field and laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions, with effects on growth and habitat use. Moreover, drift-feeding ability is reduced at low temperatures, and nocturnal drift foraging under winter conditions has a low efficiency.<br><p>Artikel 1 i avhandlingen som manuskript. Nu publicerad.</p>
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Das, Sanjeev. "Subcellular Localization of Tobacco SABP2 under Normal and Stress Conditions." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/honors/569.
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Subcellular Localization of Tobacco SABP2 under Normal and Stress Conditions
Salicylic acid (SA), a phytohormone, plays an important role in plant physiology. SA mediated innate immune pathway is an important pathway for plant immunity against pathogens. Plants resisting pathogen infection synthesize higher levels of Methyl Salicylate (MeSA), which is then converted to SA by the esterase activity of Salicylic Acid Binding Protein 2 (SABP2). The high level of the converted SA leads to enhanced pathogen resistance. The study of subcellular localization of a protein is critical in explaining its potential biochemical functions. SABP2 tagged with eGFP was expressed transiently in Nicotiana benthamiana leaves. The SABP2-eGFP expressing leaves were challenged with bacterial and viral pathogens and observed under confocal microscopy. Fluorescent signals were seen throughout the cell and more concentrated towards the cell periphery. To verify the localization, mCherry fluorescent organelle markers with specific targeting sequences were used. The results indicate that the SABP2 is likely a cytoplasmic protein, and there is no change in its localization upon infection by plant pathogens.
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CAVALLARO, VIVIANA. "SULFUR NUTRITION AND PARTITIONING IN RICE UNDER DIFFERENT STRESS CONDITIONS." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/881847.
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Sulfur (S) is an essential macronutrient required by plants for their correct development. This element is fundamental for the biosynthesis of different compounds, such as the two amino acids, cysteine (Cys) and methionine (Met), vitamins (biotin and thiamine), peptides involved in the response to abiotic stresses (glutathione - GSH, and phytochelatines - PCs), lipids and co-factors. Sulfate (SO42-) is the main S form taken up from soil by root system and then assimilated inside the cells during the sulfur reductive pathway. The uptake and the systemic movements of this anion are accomplished by the SULfate TRansporter (SULTR) gene family, which encode for H+/SO42- membrane co-transporters with different localization, amino acidic sequences, and affinity to sulfate. Since has been demonstrated that S has a key role in the response to different abiotic stresses (such as sulfur deficiency, heavy metal exposure or salt stress), the expression of these genes must be finely regulated, according to the different environmental conditions and requests for S reduced compounds.
The general aim of the present thesis is the description of S systemic fluxes in rice in different stress conditions, to obtain more information about the contribution of S in determining plant tolerance to abiotic stresses. To achieve the goal, we also took advantage of analysis performed with an elemental analyzer coupled with an isotope ratio mass spectrometer (EA-IRMS), a powerful instrument which utilizes stable isotopes of elements as tracers.
The entire research has been divided in three different parts.
In the first work, potential 32S/34S isotope effects occurring during SO42- uptake were investigated in a closed hydroponic system in which a limited amount of substrate (SO42- in the nutrient solution) was continuously removed from the solution by the activity of the sulfate transporters of the root and converted in a final product (total S of the plant). An isotope discrimination against 34S occurred during SO42- uptake: plants had a lighter S isotope composition, and the residual SO42- in the hydroponic solution was enriched in heavy stable isotope. Fractionation during uptake showed two phases characterized by different fractionation factors, reflecting changes in the expression of the OsSULTR deputed to the root uptake which may explain the different isotope phenotypes observed during plant sulfate acquisition. Moreover, the possible 32S/34S isotope effects associated to both S partitioning and metabolism were investigated by comparing plants pre-grown in complete nutrient solutions and then continuously maintained on media containing SO42- (steady-state) or deprived of SO42- for 72h. The SO42- pool of the steady-state shoot was significantly 32S depleted with respect to the SO42- pools of root, while the organic S (Sorg) pools were significantly depleted in 34S compared to both the SO42- pool of both the organs and the S source. These results suggested a higher S assimilation in the aerial part of plants which favor the lighter isotope. Under S starvation, S assimilation progressively enriched the Sorg pools in the lighter 32S isotope and the residual SO42- in both the organs in the heavier 34S isotope. Most pronounced isotope separations were again observed in the shoot, confirming the prominent role of this organ in SO42- assimilation and S allocation. No fractionation due to translocation activity was observed.
In the second part of the work, to validate the results previously obtained, we performed a mass balance study in rice plants exposed for 72h to different Cd concentrations, to investigate possible changes in S stable isotope fractionation due to this stress: in fact, adaptation of S metabolism has a pivotal role in responses to heavy metal exposure. As expected, Cd treatment strongly enhanced SO42- uptake and assimilation, as indicated by the analyses of the S pools (Stot, SO42-, and Sorg). S isotope analyses performed on the whole plants revealed changes in the S metabolism associated to variations in the discrimination against 34S, which was less evident as Cd concentration in the external medium increased. Transcriptional analysis suggested again that change of the ratio between relative transcripts of OsSULTR1;1 and OsSULTR1;2, as observed for S starvation, may be responsible for the progressive decreased in 34S isotope discrimination. The important role of shoot in S assimilation was confirmed: isotope fractionation associated to sulfate assimilation was higher in shoot than in root, and progressively increased as Cd concentration did.
The last part of work was focused on fully characterize, under hydroponics-controlled conditions in the absence or in the presence of salt stress (80 mM NaCl), the phenotypic behavior in the already available salt tolerant introgression line (IL) Onice 11 (O11), obtained by Marker-Assisted Back-Cross (MABC) selection starting from the cross between the Italian japonica elite cultivars Onice (sensitive recurrent parent) and the indica variety IR64-SalTol (tolerant), donor of the major QTL SalTol. Moreover, S acquisition and metabolism of O11 and both the parental lines were evaluated to investigate their possible implication in determining the different tolerance to salt stress. Results showed the beneficial effect of the introgression of the SalTol QTL from the indica variety into selected japonica rice line, based on different characteristics of selected phenotypic-biochemical-physiological parameters. However, salt stress strongly affected S uptake and assimilation, and we can reasonably suppose that these features do not justify the different salt tolerance in the considered IL O11.
In conclusions, rice plants can discriminate against 34S during SO42- uptake and assimilation. Between plants organs, shoot represents the predominant one involved in S assimilation. Abiotic stresses, such as S starvation or Cd exposure, lead to changes in the ratio of relative transcripts between the OsSULTRs involved in the uptake of sulfate, and this may be the cause of the different isotope phenotypes observed. Finally, salt tolerance in the IL O11 appears to not be dependent on different S metabolism.
Books on the topic "Cations under stress conditions"
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Alexandrov, Sergey. Elastic/Plastic Discs Under Plane Stress Conditions. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14580-8.
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Jennifer, McCoy, ed. Venezuelan democracy under stress. North-South Center Press, University of Miami, 1995.
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B, Halley Robert, and National Water Quality Assessment Program (U.S.), eds. The south Florida environment: A region under stress. U.S. G.P.O., 1996.
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Spurgin, Anthony J., and David W. Stupples. Decision-Making in High Risk Organizations Under Stress Conditions. CRC Press, 2016. http://dx.doi.org/10.1201/9781315370903.
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Jenkins, Alfan Wayne. A PSYCHOLOGICAL TRAINING PROGRAMME DESIGNED TO ENHANCE SKILLED PERFORMANCE UNDER VARYING CONDITIONS OF STRESS. S.G.I.H.E., 1986.
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Bishop, Barry C. Karnali under stress: Livelihood strategies and seasonal rhythms in a changing Nepal Himalaya. University of Chicago, 1990.
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Bishop, Barry C. Karnali under stress: Livelihood strategies and seasonal rhythms in a changing Nepal Himalaya. University of Chicago, 1990.
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(Japan), Ajia Keizai Kenkyūjo, and Nihon Bōeki Shinkō Kikō, eds. African rural livelihoods under stress: Economic liberalization and smallholder farmers in Malawi. Institute of Developing Economies, 2008.
Find full textBook chapters on the topic "Cations under stress conditions"
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Dube, A. K. "Squeezing under high stress conditions." In Assessment and Prevention of Failure Phenomena in Rock Engineering. Routledge, 2022. http://dx.doi.org/10.1201/9781315137803-119.
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Päpke, Carola, Santiago Ramirez-Aguilar, and Carla Antonio. "Oxygen Consumption Under Hypoxic Conditions." In Low-Oxygen Stress in Plants. Springer Vienna, 2013. http://dx.doi.org/10.1007/978-3-7091-1254-0_10.
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Sanders, Gregor J., and Stefan K. Arndt. "Osmotic Adjustment Under Drought Conditions." In Plant Responses to Drought Stress. Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32653-0_8.
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Hou, Peichen, Ping Yun, Mei Qu, et al. "Portulaca oleracea under Drought Stress." In Medicinal Plant Responses to Stressful Conditions. CRC Press, 2023. http://dx.doi.org/10.1201/9781003242963-18.
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Hou, Peichen, Mei Qu, Ping Yun, et al. "Avena sativa under Drought Stress." In Medicinal Plant Responses to Stressful Conditions. CRC Press, 2023. http://dx.doi.org/10.1201/9781003242963-4.
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Ahmed, Hassan Ahmed Ibraheem, Peichen Hou, and Waqas-ud-Din Khan. "Portulaca oleracea under Salt Stress." In Medicinal Plant Responses to Stressful Conditions. CRC Press, 2023. http://dx.doi.org/10.1201/9781003242963-17.
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Tsvyk, Tetiana. "Anthropogenic and Genetic Conditions for Phosphate Mobility in Individual Structural Fractions of Podzolized Chernozem." In Soils Under Stress. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68394-8_8.
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Pandey, Sanjeev. "Catharanthus roseus: Cultivation Under Stress Conditions." In Catharanthus roseus. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51620-2_17.
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Sachdev, Swati, Shamim Akhtar Ansari, and Mohammad Israil Ansari. "Peroxisomes and ROS Under Stress Conditions." In Reactive Oxygen Species in Plants. Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-9884-3_7.
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Balestrazzi, Alma, Anca Macovei, Mattia Donà, Daniela Carbonera, and Massimo Confalonieri. "Genotoxic Stress, DNA Repair, and Crop Productivity." In Crop Improvement Under Adverse Conditions. Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4633-0_7.
Full textConference papers on the topic "Cations under stress conditions"
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Henke, Tom, and Joel Carpenter. "Cracking Tendencies of Two Martensitic Stainless Alloys in Common Heavy Completion Brine Systems at Down-Hole Conditions: a Laboratory Investigation." In CORROSION 2004. NACE International, 2004. https://doi.org/10.5006/c2004-04128.
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Abstract There have been recent reports of failures of production tubulars in packer assemblies comprised of high-strength corrosion resistant alloys. This phenomenon is a result of the current trend of oil and gas development at deeper well depths and hotter down-hole temperatures. These failures have usually manifested themselves as cracking failures and resulted in severe economic penalties. While the consequences of these failures are straightforward, the causes are difficult to determine. Here we report a laboratory investigation that clarifies the role of heavy brine compositions in cracking failures. Two different Martensitic stainless steels (85 ksi and 110 ksi) in the form of stressed C-ring coupons were tested in ten different heavy brine systems at 1770C (3500F). The different brine systems examined contained combinations of zinc and calcium cations, chloride and bromide anions, and standard additives for corrosion inhibition and oxygen scavenging. Tests were conducted on deaerated solutions under 500 psi pressures, both with and without CO2 and H2S. No cracking was found on any coupon challenged in an environment free of CO2 and H2S. Cracking of the 110 ksi steel was observed in chloride-only fluids when the acid gases were present. However, no cracking was observed in the brines comprised predominately of bromides under the same conditions. These results support the conclusion that low pH, common sulfur based additives and bromides, even under sour acid gas conditions, do not promote environmental cracking.
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Abayarathna, Dharma, Ali Naraghi, and Nick Grahmann. "Inhibitor Evaluations Using Various Corrosion Measurement Techniques in Laboratory Flow Loops." In CORROSION 2000. NACE International, 2000. https://doi.org/10.5006/c2000-00021.
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Abstract The application of corrosion inhibitors for the corrosion control of carbon steel is a common practice in the oil and gas production environments. Successful corrosion control programs demand cost effective corrosion inhibitors with optimized performance. The corrosion inhibitors, which are formulated specifically for given field conditions, undergo rigorous qualification and performance evaluations at the laboratory before being submitted for a field application. In order to apply laboratory data to the field, the chemicals must be evaluated under simulated field conditions. In this study, the hydrodynamic parameter, wall shear stress value was utilized for the laboratory simulations. Chemical evaluations were conducted under simulated wall shear stress values in a pipe flow and a jet impingement. Both techniques provided similar results during the evaluation of a water soluble mixed corrosion inhibitor. During the evaluation of a water dispersible cationic inhibitor degradation of the performance was observed at relatively high shear conditions in the pipe flow. The jet impingement technique exhibited relatively poor performance of this chemical under low shear conditions. Furthermore, jet impingement technique provided additional information such as performance under extremely high shear conditions as well as whether a chemical is effective after an upset condition.
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Visser, Anna, Gregor Mori, Reinhard Pippan, et al. "Influence of Different Types of Localized Corrosion on the Fatigue Behavior of an Austenitic Stainless Steel." In CORROSION 2016. NACE International, 2016. https://doi.org/10.5006/c2016-07599.
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Abstract Materials tested under cyclic loading in aggressive electrolytes suffer different kinds of localized damage which compete or superimpose mechanical fatigue. Fatal damage is influenced by both mechanical and (electro-)chemical parameters. In the present study an austenitic stainless steel has been tested in corrosive electrolytes ranging from mild to aggressive conditions by changes in salt-cation, pH-value, chloride content, temperature and R-value. To study the effect on S/N curves and especially on the fatigue limit, the type of damage was determined by investigating fracture surfaces using scanning electron microscope (SEM). In addition electrochemical properties of the steel in the testing solutions were ascertained by cyclic polarization. Furthermore scratch tests were conducted to characterize the materials repassivation kinetics. This work aims to contribute to an improved understanding of the relation between environmental conditions and corrosion fatigue behavior of austenitic stainless steel. The results show the effect of different types of localized corrosion on the material performance under cyclic loading. Depending on the testing conditions pitting and stress corrosion cracking interfere with corrosion fatigue, leading to reduced fatigue strength. Comparing the influence of the occurring types of damage on fatigue strength, stress corrosion cracking turns out to be far more severe than pitting. Electrochemical tests and repassivation kinetics are suitable, but limited instruments to deduce the corrosion fatigue behavior.
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Stauffer, C. C., W. E. Allmon, A. F. Aschoff, and R. B. Dooley. "Experience with Water Sampling and Chemistry Monitoring Equipment." In CORROSION 1991. NACE International, 1991. https://doi.org/10.5006/c1991-91216.
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Abstract In 1986, a project contracted by the Electric Power Research Institute (EPRI) was initiated whereby measurement of cycle chemistry parameters in a variety of boiler types and under a variety of test conditions was performed for comparison to the EPRI interim consensus guidelines. To accomplish this task, a sophisticated chemistry monitoring system, which could be transported to several different power plants, was designed and fabricated. This project allowed the opportunity to gain invaluable experience in the operation of on-line chemistry monitors. One of the major findings of this program was that it brought to center stage many shortcomings of the on-line chemistry monitors and other equipment. Therefore, many improvements were made in the calibration, maintenance, and operation of this equipment. An alternate water supply and standard sample synthesizer became standard tools for determining the quality of the results obtained from the on-line monitors. One of the most common findings was that the calibration frequency needed to be increased significantly (up to seven fold) to get accurate results. The project also extended the useful temperature range of the cation resin membranes and identified a potentially serious problem regarding stress corrosion cracking of stainless steel sample coolers. Most of the findings in this paper are applicable to the on-line monitors being used in the power industry today.
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Roy, Ajit K., Subhas Pothana, and Heidi Aquino. "Stress Corrosion Cracking of Cladding Materials under Different Loading Conditions." In CORROSION 2004. NACE International, 2004. https://doi.org/10.5006/c2004-04560.
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Abstract Slow-strain-rate (SSR) and constant-load (CL) stress corrosion cracking (SCC) tests were performed using two Zr alloys in neutral and acidic environments at temperatures ranging from ambient to 90°C. The cracking susceptibility was determined with and without the application of the controlled cathodic potentials. The metallography and fractography of the tested specimens were conducted by optical microscopy and scanning electron microscopy (SEM), respectively. The results of CL SCC testing showed no failure in either environment. SCC testing by the SSR technique revealed increased ductility in the 90°C acidic environment. The magnitude of failure stress was significantly reduced due to the synergistic effect of temperature and pH. The application of cathodic controlled potential to the test specimen during SSR testing did not influence the ductility parameters and the failure stress. Even though no effect of cathodic charging on the cracking susceptibility of Zr alloys was observed, it is interesting to note that the test specimens showed damage in their gage sections under controlled potential (Econt) during both CL and SSR testing. Some indications of secondary cracking due to Econt were observed by optical microscopy. Fractographic evaluations by SEM showed dimpled microstructures indicating ductile failures in both test environments.
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Turnbull, A., and G. Hinds. "Stress Corrosion Cracking of Duplex Stainless Steel under Simulated Evaporation Conditions." In CORROSION 2007. NACE International, 2007. https://doi.org/10.5006/c2007-07474.
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Abstract The susceptibility of 22 Cr and 25 Cr duplex stainless steels to stress corrosion cracking under evaporative seawater conditions has been evaluated using a modified drop evaporation test. Failure of both steels occurred at temperatures as low as 105 °C. Observation of patchy corrosion and occasional pitting beneath the salt layer suggests that the underdeposit chemistry was aggressive for this system and a combination of this chemistry and micro-plastic deformation is considered to be responsible for cracking of the steels. The engineering implication is that existing recommendations for the critical temperature for coating of duplex stainless steel to avoid failures in service may need to be revised.
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Imhuelse, Thomas, Benny Rievers, and Marcel Vornholt. "Magnetic Surface Stress Pump Development Under Microgravity Conditions for Satellite Thermal Management." In IAF Microgravity Sciences and Processes Symposium, Held at the 75th International Astronautical Congress (IAC 2024). International Astronautical Federation (IAF), 2024. https://doi.org/10.52202/078356-0018.
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Dunn, D. S., Y. M. Pan, K. T. Chiang, and G. A. Cragnolino. "Surface Analysis of Alloy 22 under Conditions That Promote Stress Corrosion Cracking." In CORROSION 2006. NACE International, 2006. https://doi.org/10.5006/c2006-06509.
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Abstract The U.S. Department of Energy (DOE) is currently preparing a license application for the permanent disposal of high-level waste at Yucca Mountain, Nevada. The waste package design for the disposal of high-level waste could consist of an outer container made of Alloy 22, a corrosion resistant Ni-Cr-Mo-W-Fe alloy, surrounding an inner container made of Type 316 nuclear grade stainless steel. Alloy 22 is resistant to stress corrosion cracking in chloride solutions; however, under a limited range of conditions, stress corrosion cracking of Alloy 22 has been observed in laboratory tests in environments containing chloride and bicarbonate, which may be present in water entering the emplacement drifts. The initiation of stress corrosion cracking may significantly decrease waste package lifetimes. Analyses of the oxide films on Alloy 22 produced under conditions where stress corrosion cracking has and has not been observed are presented in this paper. The composition and thickness of the oxide films were found to be dependent on test conditions. Under conditions where stress corrosion cracking is possible, the film was thicker and the chromium concentration in the oxide film was significantly lower compared to oxides produced under benign conditions.
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Wilmott, M. J., T. R. Jack, G. Van Boven, and R. L. Sutherby. "Pipeline Stress Corrosion Cracking: Crack Growth Sensitivity Studies under Simulated Field Conditions." In CORROSION 1996. NACE International, 1996. https://doi.org/10.5006/c1996-96242.
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Abstract Neutral pH Stress Corrosion Cracking (SCC) has been found on a number of Canadian gas transmission pipeline systems. This paper details laboratory studies which have been carried out to investigate the growth of pre-existing SCC clusters under simulated field conditions. The influence of various environmental parameters will be discussed.
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Andersen, Helle, Poul-Erik Arnvig, Wioletta Wasielewska, Lena Wegrelius, and Christian Wolfe. "SCC of Stainless Steel under Evaporative Conditions." In CORROSION 1998. NACE International, 1998. https://doi.org/10.5006/c1998-98251.
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Abstract Three different test methods have been used to assess the susceptibility of different stainless steel grades to SCC under evaporative and immersed conditions. The methods employed were the drop evaporation test, the wick test and a high temperature, high pressure test simulating a feedwater heater tubing application in power plants. The alloys investigated were commercially produced austenitic and duplex stainless steels varying in chemical composition, plus one copper-nickel alloy. The resistance of austenitic stainless steels towards SCC increased by increasing the content of Ni, Mo and Cr, thus the super austenitic 654SMO® (UNS32654)1 did not not show any cracking in any of the three tests. The super austenitic 254SMO® (UNS31254)2 revealed only slight SCC in the simulated feed water heater tubing application while the equivalent N08367 revealed severe pitting and cracking. The drop evaporation test exhibited the most severe test conditions characterised by thermally induced fatigue effects, sensibility to onset of corrosion and severe acidic conditions generated under deposits on the test specimen. Some factors in stress corrosion cracking tests such as thermal fatigue, diffusion, heat transfer and stress condition, are discussed with regard to their influence on the test results
Reports on the topic "Cations under stress conditions"
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Taylor-Pashow, K., and D. Hobbs. EFFECT OF CATIONS ON ALUMINUM SPECIATION UNDER ALKALINE CONDITIONS. Office of Scientific and Technical Information (OSTI), 2012. http://dx.doi.org/10.2172/1050619.
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Cahaner, Avigdor, Sacit F. Bilgili, Orna Halevy, Roger J. Lien, and Kellye S. Joiner. effects of enhanced hypertrophy, reduced oxygen supply and heat load on breast meat yield and quality in broilers. United States Department of Agriculture, 2014. http://dx.doi.org/10.32747/2014.7699855.bard.
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Original objectivesThe objectives of this project were to evaluate the growth performance, meat yield and quality attributes of broiler strains widely differing in their genetic potential under normal temperature vs. warm temperature (short and long-term) conditions. Strain differences in breast muscle accretion rate, metabolic responses under heat load and, gross and histopathological changes in breast muscle under thermal load was also to be characterized. BackgroundTremendous genetic progress has been made in broiler chicken growth rate and meat yield since the 1950s. Higher growth rate is driven by higher rates of feed intake and metabolism, resulting in elevated internal heat production. Hot rearing conditions negatively affect broiler growth by hindering dissipation of heat and may lead to a lethal elevation in body temperature. To avoid heat-induced mortality, broilers reduce feed intake, leading to depressed growth rate, lower weight gain, reduce breast meat yield and quality. Thus, the genetic potential of contemporary commercial broilers (CCB) is not fully expressed under hot conditions. Major conclusions, solutions, and achievementsResearch conducted in Israel focused on three broiler strains – CCB, Featherless, Feathered sibs (i.e., sharing similar genetic background). Complimentary research trials conducted at Auburn utilized CCB (Cobb 500, Cobb 700, Ross 308, Ross 708), contrasting their performance to slow growing strains. Warm rearing conditions consistently reduced feed intake, growth rate, feed efficiency, body weight uniformity and breast muscle yield, especially pronounced with CCB and magnified with age. Breast meat quality was also negatively affected, as measured by higher drip loss and paler meat color. Exposure to continuous or short-term heat stress induced respiratory alkalosis. Breast muscle histomorphometrics confirmed enhanced myofiber hypertrophy in CCB. Featherless broilers exhibited a significant increase in blood-vessel density under warm conditions. Rapid growth and muscle accretion rate was correlated to various myopathies (white striping, woody and necrotic) as well as to increases in plasma creatinekinase levels. Whether the trigger(s) of muscle damage is loss of cellular membrane integrity due to oxidative damage or tissue lactate accumulation, or to loss of inter-compartmental cation homeostasis is yet to be determined. Based on genome-wide single-nucleotide polymorphism array genotyping, identification of the gene with the recessive mutation Scaleless (sc) facilitated the development a dCAPS assay to discriminate between sc carrier (sc/+) and non-carrier (+/+) individuals. ImplicationsThis project confirmed that featherless broiler strains grow efficiently with high yield and quality of breast meat, even under warm rearing conditions that significantly depress the overall performance of CCB. Therefore, broiler meat production in hot regions and climates can be substantially improved by introducing the featherless gene into contemporary commercial broiler stocks. This approach has become more feasible with the development of dCAPS assay. A novel modification of the PCR protocol (using whole blood samples instead of extracted DNA) may contribute to the efficient development of commercial featherless broiler strains. Such strains will allow expansion of the broiler meat production in developing countries in warm climates, where energy intensive environmental control of rearing facilities are not economical and easily achievable.
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Ryan, Joseph. Colloid-Facilitated Transport of Cations in an Unsaturated Fractured Soil Under Transient Conditions. Office of Scientific and Technical Information (OSTI), 2015. http://dx.doi.org/10.2172/1168955.
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Watson, Mark, Martyn Wilmott, and Brian Erno. GRI-96-0452_2 Stress Corrosion Cracking Under Field Simulated Conditions II. Pipeline Research Council International, Inc. (PRCI), 1997. http://dx.doi.org/10.55274/r0011974.
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The pH of solutions found under disbonded polyethylene tape coatings in the field is generally in the range of 6.5 to 7.5. Electrochemically determining corrosion rates for pipeline steels exposed to neutral pH solutions in this pH range indicate that corrosion rates are too low to account for the observed crack growth rates from field excavation programs. This suggests that for the SCC process to be based on a simple dissolution mechanism then the pH at the crack tip would have to be lower than the bulk solution pH. A computer model was developed to determine solution chemistry changes within an SCC crack under anaerobic conditions as a function of time The numerical simulation model showed that the pH at a crack tip is lower by at least one pH unit than the trapped electrolyte outside the crack. A second thermodynamic model was used to show that under appropriate conditions dilute groundwater can be converted to a concentrated carl ornately bicarbonate solution. High temperatures were not required to concentrate on this solution. The concentration of this electrolyte under coal tar or asphalt coatings can occur by a cyclical process in which groundwater levels fluctuate and in tum influence the ability of cathodic protection to reach the steel surface. The high pH is generated by effective cathodic protection and the carbonate concentration is developed by absorption of CO2 from soil gases.
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Wilmont, Martyn, Greg Van Boven, and Tom Jack. GRI-96-0452_1 Stress Corrosion Cracking Under Field Simulated Conditions I. Pipeline Research Council International, Inc. (PRCI), 1997. http://dx.doi.org/10.55274/r0011963.
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Electrochemical measurements have been performed on polished and mill scaled steel samples. The solutions investigated have included carbonate bicarbonate mixtures of varying pH as well as solutions of neutral pH such as NS4. Results indicate that the mechanism of corrosion associated with the carbonate bicarbonate environments involves passive film formation. No such passivation is observed for solutions associated with neutral pH SCC. Electrochemical corrosion rates measured on polished steel specimens exposed to NS4 solutions in the pH range 5 to 6.8 were in the region of 5 x 10e-1 to 1 x 10e-2 mm/s. However, rates obtained on mill scaled surfaces went much lower and in the region of 5 x 10e-10 mm/s. Field determined crack propagation rates are estimated to be in the region of 2 x 10e-8 mm/s. Whilst the laboratory determined corrosion rates are lower than the field propagation rate it should be remembered that the laboratory rates were obtained on unstressed specimens. The application of load would be expected to increase the corrosion rate and may indicate that stress focused dissolution process may be sufficient to explain the propagation of neutral pH stress corrosion cracks. However, as hydrogen evolution is the most likely cathodic reaction involved in the mechanism of neutral pH SCC the role of hydrogen in the crack propagation mechanism may also be important.
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Psaila-Dombrowski, M. J., W. A. Van Der Sluys, and B. P. Miglin. GRI-97-0001 Investigation of Pipeline Stress Corrosion Cracking Under Controlled Chemistry Conditions. Pipeline Research Council International, Inc. (PRCI), 1997. http://dx.doi.org/10.55274/r0012043.
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Stress corrosion cracking failures of high-pressure gas transmission pipelines have occurred. Although such failures are infrequent, there is a concern about their potentially catastrophic nature. The susceptibility of a material to this failure is controlled by crack growth kinetics which is governed by the composition of the water at the crack tip, the material composition, temperature, and stress/strain conditions. Hence, there is a need to investigate these parameters to begin to understand and develop predictive capabilities to avoid this phenomenon.
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Gillen, K. T., and G. M. Malone. Nuclear power plant accident simulations of gasket materials under simultaneous radiation plus thermal plus mechanical stress conditions. Office of Scientific and Technical Information (OSTI), 1997. http://dx.doi.org/10.2172/508139.
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Abril Castro, Jorge Leonardo, Ruth Rebeca Bonilla B., and Belisario Roncallo Fandiño. Effect of inoculation with nitrogen-fixing bacteria on the growth of Panicum maximum Jacq. under water stress conditions. Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, 2016. http://dx.doi.org/10.21930/agrosavia.poster.2016.55.
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En las áreas secas de la región caribeña de Colombia, la producción de forraje se ve afectada en términos de cantidad y calidad por condiciones de sequía presentadas durante períodos prolongados del año. La estación seca causa pérdidas en la alimentación y productividad de sistemas ganaderos. Muchas especies de bacterias nitrogenadas son asociadaa a diferentes plantas en la región, que pueden beneficiar el crecimiento y desarrollo de estas especies en condiciones de estrés hídrico. El objetivo de esta investigación fue evaluar el efecto de la inoculación con bacterias nitrogenadas en el desarrollo de Panicum maximum Jacq. bajo condiciones de sequía.
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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, 2013. http://dx.doi.org/10.32747/2013.7699850.bard.
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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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Yotsova, Ekaterina, Anelia Dobrikova, Martin Stefanov, and Emilia Apostolova. Impact of Salicylic Acid on the Growth and the Activity of Photosynthetic Apparatus in Rice under Non-stress Conditions. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, 2018. http://dx.doi.org/10.7546/crabs.2018.03.09.
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