Academic literature on the topic 'Growth substances. eng'

Generally speaking, models dealing with multiple limiting substances have mainly been derived from three different categories of studies, namely, multiple toxicity, multiple nutrient limitation and inhibition of enzyme catalysis. As different basic mechanisms were assumed by these models, a simple and unique theory which handles all these types of multiple-substance limited growth does not appear to exist. This paper presents a unified theory, based on a probabilistic foundation, for microbial growth controlled by multiple limiting substances (including both nutrient and toxicant). Most of the existing kinetic models in the aforementioned three areas can be generated using one theory. The theory has a broad application in many aspects, e.g. wastewater treatment, eutrophication studies, risk assessment, etc.

We evaluated two osmotic adjustment substances (glycine betaine (GB) and glycine (G) and a combination of both glycine + glycine betaine (G + GB) using two modes of application; irrigation and foliar sprays with Dracaena sanderiana plants. The plants were grown in containers and subjected to two levels of NaCl concentrations (2.0 and 7.5 dS m−1) over 8 weeks. Growth, pigment concentrations, and physiological parameters were assessed at the end of the trial. The foliar application of GB resulted in most optimal plant growth and biomass production in the presence of NaCl. The chlorophyll and carotenoid concentrations showed different trends depending on the osmotic adjustment substance applied and the mode of application. Stomatal density and dimensions varied considerably with respect to the osmotic adjustment substance supplied. The concentration of soluble sugars in leaves did not show a clear trend under the different treatments assessed. The exogenous application of G resulted in the highest concentration of free proline and proteins in leaves. The antioxidant capacity in leaves increased with both osmotic adjustment substances, and both means of application, under low and high saline conditions. We concluded that the foliar application of GB can be recommended in order to achieve cost-effective growth of D. sanderiana under saline conditions.

Various growth factors (e.g., growth hormone-releasing hormone, acidic fibroblast growth factor, nerve growth factor, brain-derived neurotrophic factor, and interleukin-1) are implicated in sleep regulation. It is hypothesized that neuronal activity enhances the production of such growth factors, and they in turn form part of the sleep regulatory mechanism. Glial cell line-derived neurotrophic factor (GDNF) promotes development, differentiation, maintenance, and regeneration of neurons, and its production is induced by well-characterized sleep regulatory substances such as interleukin-1 and tumor necrosis factor. Therefore, we investigated whether GDNF would promote sleep. Twenty-six male Sprague-Dawley rats and 30 male New Zealand White rabbits were surgically implanted with electroencephalogram (EEG) and electromyogram (EMG; rats only) electrodes, a brain thermistor, and a lateral intracerebroventricular cannula. The animals were injected intracerebroventricularly with pyrogen-free saline and on a separate day with one of the following doses of GDNF: 5, 50, and 500 ng in rabbits and 50 and 500 ng in rats. The EEG, brain temperature, EMG (in rats), and motor activity (in rabbits) were recorded for 23 h after the intracerebroventricular injection. GDNF (500-ng dose) increased the time spent in nonrapid eye movement sleep in both rats and rabbits. Rapid eye movement sleep was not affected by the lower doses of GDNF but was inhibited in rabbits after the high dose. EEG slow-wave activity was not affected by GDNF. The current results provide further evidence that various growth factors are involved in sleep regulation.

The article deals with the morphological features of spreading films of surfactants on the surface of the reservoir on the basis of experiments on the Gorky reservoir under various meteorological conditions. The test substances were: oleic acid, vegetable oil, diesel. The registration of film contamination was carried out using X-band digital coherent radar MRS-1000, located on the roof of the lighthouse at the end of the outside harbor. The processing of the obtained radar panoramas made it possible to establish that the physical properties of the pollutant are reflected in the morphological characteristics of the film slicks. In particular, the substance properties are manifested in relation of the slick axes along and across the wind direction, as well as in the effects of growth and saturation of the slick area, all other things being equal. Without claiming to be a method for identifying a substance based on the data obtained, we can conclude that these effects are present and that they can be observed using radar methods.

e15010 Background: Ovarian cancer (OC) is the fourth most common cancer in women aged 40-54 years. Despite advances in cancer research, no existing methods provide effective early diagnosis and treatment of OC, so the search for new medications is an urgent task. The effectiveness of the XAV-939 pharmacological substance, which inhibits the Wnt signaling pathway, was studied in an orthotopic patient-derived xenograft of human ovarian cancer. Methods: A PDX model was created in 20 female immunodeficient Balb/c Nude mice. A tumor fragment was implanted into the ovary, and the ovary was transposed under the skin to better visualize the xenograft growth. When the average tumor volume was 67.4 mm3, animals were divided into 4 groups: group 1 – controls (n = 5); group 2 – animals receiving paclitaxel (n = 5); group 3 – animals with XAV-939 (n = 5); group 4 – animals with combined paclitaxel+XAV-939 (n = 5). The control group received the carrier substance, and the test substances were administered at 10 mg/kg; the substances were administered intraperitoneally twice a week for 22 days. The tumor growth was assessed throughout the experiment by measuring its linear dimensions (length and width), and the volume and tumor growth index were calculated. The data were statistically processed using Microsoft Excel and STATISTICA 10. The Mann-Whitney nonparametric test was used to assess the differences between the control and experimental groups. Results: No statistically significant differences were observed in the indices of tumor growth between groups 2 (paclitaxel) and 1 (control), and groups 3 (XAV-939) and 1 (control). However, the difference was statistically significant between groups 4 (paclitaxel+XAV-939) and 1 (control). The tumor growth inhibition index was calculated at the end of the experiment. It was maximal in group 4 (paclitaxel+XAV-939) – 67.78%; in groups 2 (paclitaxel) and 3 (XAV-939), it was 21.39% and 30.33%, respectively. Conclusions: An orthotopic PDX model of ovarian cancer was generated, and the activity of XAV-939 towards the OC xenograft was studied; the greatest efficacy of the preparation was noted in combination with paclitaxel.

This study evaluated the effects of homeopathically potentized Arsenicum album, nosode, and gibberellic acid in a bioassay with arsenic-stressed duckweed (Lemna gibbaL.). The test substances were applied in nine potency levels (17x, 18x, 21x–24x, 28x, 30x, 33x) and compared with controls (unsuccussed and succussed water) regarding their influence on the plant’s growth rate. Duckweed was stressed with arsenic(V) for 48 h. Afterwards, plants grew in either potentized substances or water controls for 6 days. Growth rates of frond (leaf) area and frond number were determined with a computerized image analysis system for different time intervals (days 0–2, 2–6, 0–6). Five independent experiments were evaluated for each test substance. Additionally, five water control experiments were analyzed to investigate the stability of the experimental setup (systematic negative control experiments). All experiments were randomized and blinded. The test system exhibited a low coefficient of variation (≈1%). Unsuccussed and succussed water did not result in any significant differences in duckweed growth rate. Data from the control and treatment groups were pooled to increase statistical power. Growth rates for days 0–2 were not influenced by any homeopathic preparation. Growth rates for days 2–6 increased after application of potentized Arsenicum album regarding both frond area (p< 0.001) and frond number (p< 0.001), and by application of potentized nosode (frond area growth rate only,p< 0.01). Potencies of gibberellic acid did not influence duckweed growth rate. The systematic negative control experiments did not yield any significant effects. Thus, false-positive results can be excluded with high certainty. To conclude, the test system withL. gibbaimpaired by arsenic(V) was stable and reliable. It yielded evidence for specific effects of homeopathic Arsenicum album preparations and it will provide a valuable tool for future experiments that aim at revealing the mode of action of homeopathic preparations. It may also be useful to investigate the influence of external factors (e.g., heat, electromagnetic radiation) on the effects of homeopathic preparations.

We tested 38 legislatively recognised substances such as food additives and supplements for antifungal efficacy, with the aim of providing an alternative to synthetic conventional fungicides. These compounds were tested against 9 significant pathogenic fungal species belonging to the significant genera Fusarium, Penicillium, and Aspergillus. Of these compounds, 6 are proposed as potential candidates to provide a complementary alternative to conventional fungicides. Natamycin provided extreme efficacy expressed as MIC50 (5–31 µg/ml), followed by BHA and then BHT, CaNa2EDTA, PABA, and chitosan expressed as MIC50 (0.7–1.9 mg/ml). Safety and antifungal activity were discussed in terms of the mode of action and molecular structure, as well as in terms of potential practical use and legislative requirements for the introduction into practice. We presume that food additives and food supplements are definitely a great source of antifungal compounds. In developed areas of the world (e.g. in the EU), they could represent legislatively recognised compounds, so-called basic substances.

Background. Previously, we have shown that the polyhexamethylene guanidine hydrochloride hydrogel exhibits a pronounced wound healing. At the same time, no studies of the toxic effect of the hydrogel on animals have been conducted. Aim of the research. In the framework of this work, the acute toxicity of the hydrogel polyhexamethylene guanidine hydrochloride was studied in laboratory animals with intragastric administration. Materials and methods. The polyhexamethylene guanidine hydrochloride hydrogel was obtained by crosslinking the amino end groups with formaldehyde. An acute toxicity study was carried out (P 1.2.3156-13, GOST 32644-2014 and the Guidelines for conducting preclinical studies of drugs) in an experiment on outbred mice with a single addition of the test substance in different doses (1000, 3000, 5000, 8000 mg/kg) with fixing indicators (appearance, behavior, condition of the body hair coat, water and food consumption, excretion, body weight and its growth) during 14 days. After the animals were withdrawn from the experiment, autopsy, macroscopic evaluation and weighing of the internal organs were performed. The results showed that with the introduction of the test substance into the animal organism, death during the observation period (14 days) did not occur. It was not possible to determine the semi-lethal dose for the test compound. Conclusion. The conducted studies allow us to conclude that this substance is practically non-toxic and can be classified as hazard class V. Further research will be directed to the formation of hydrogel compositions with medicinal substances.

Androgenetic alopecia (AGA) has become a prevalent hair fall dysfunction due to genetic as well as hormonal effects distinguished by androgen-related gradual weakening of the scalp hair with a sequence. Around turn 60, 45 percent of males and 35 percent of females come down with AGA. Owing to the small number of successful AGA therapies, Platelet-rich Plasma (PRP) has been an attractive alternative therapeutic approach. Platelet-rich plasma (PRP) is being proposed for the incorporation of greater levels of growth factors and certain other biologically active substances in wounded lesions to achieve the specific healing objectives. PRP is already being included in dentistry and cosmetic surgery for about four decades. Even the usefulness of this autologous substance in both these fields seems to be well known. Notably, in treating different cosmetic procedures, PRP is already progressively seen because its high constituents of platelet-derived growth factors and cytokines may improve the biochemical mechanisms correlated with tissue repair and regeneration. After activation, platelets within the PRP secrete various growth factors that exhibit the results of hair regeneration. However, PRP may be prepared with different protocols and procedures. Differences could influence the character and possible effectiveness of the end PRP product in the availability of RBCs and WBCs, the introduction of thrombin or calcium chloride to trigger fibrin initiation, and pH-altering substances. A standard procedure for PRP preparation and application and a framework to assess results have not been developed, though many research works have been published. Thereby, the subsequent research article presents a proposed treatment protocol for AGA by platelets-rich plasma (PRP), which has been confirmed after reviewing different studies performed by researchers that exhibit PRP's efficacy in AGA.

Over the last decade, the “traditional” drug scene has been supplemented – but not replaced – by the emergence of a range of novel psychoactive substances (NPS), which are either newly created or existing drugs, including medications, now being used in novel ways. By the end of 2015, in excess of 700 NPS had been reported by a large number of countries in the world. Most recent data show however that synthetic cathinones; synthetic cannabinoids; and psychedelics/phenethylamines; account for the largest number of NPS. Given the vast range of medical and psychopathological issues associated with the molecules here described, it is crucial for health professionals to be aware of the effects and toxicity of NPS. The “Drugs 2.0.” revolution facilitated the birth and growth of an “Online Drug Culture” which finds its main expression in chats/fora/blogs as well as the diffusion of online drug marketplaces (both in the surface and deep web). The web has progressively modified the drug market from a “street” into a “virtual” one, so by increasing the availability of new drugs/NPS/“legal highs” (“legal alternatives” to the traditional illegal drugs). The rapid pace of change in the NPS online market constitutes a major challenge to the provision of current and reliable scientific knowledge on these substances. The present lecture aims at providing an overview of the NPS phenomenon, also giving an overview of the main clinical and pharmacological issues relating to these most popular NPS categories.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Orientador: Maria José Hitomi Nagata
Banca: Maurício Guimarães Araújo
Banca: Luiz Alberto Milanezi
Resumo: Objetivo: O propósito deste estudo foi avaliar, histologicamente, a influência do Plasma Rico em Plaquetas (PRP) no reparo ósseo de defeitos de tamanho crítico (DTC) criados cirurgicamente em calvárias de ratos. Material e Método: 32 ratos foram divididos em 2 grupos: C (controle) e PRP (Plasma Rico em Plaquetas). Um DTC de 8 mm de diâmetro foi criado na calvária de cada animal. No Grupo C, o defeito foi preenchido somente com coágulo sangüíneo. No Grupo PRP, o defeito foi preenchido com Plasma Rico em Plaquetas. Cada grupo foi subdividido para eutanásia em 4 ou 12 semanas pós-operatórias (n=8). Foram realizadas análises histológica e histométrica. A quantidade de osso neoformado foi calculada como uma proporção da área total do defeito original. Esses valores foram transformados em arcoseno para a análise estatística (ANOVA, Tukey, p < 0.05). Resultados: Nenhum defeito reparou completamente com tecido ósseo. O Grupo PRP apresentou significativamente mais neoformação óssea que o Grupo C, tanto em 4 semanas (17,68% e 7,20%, respectivamente) como em 12 semanas (24,69% e 11,65%, respectivamente) pós-operatórias. Conclusão: Dentro dos limites deste estudo, pode-se concluir que o PRP aumentou significativamente o reparo ósseo de defeitos de tamanho crítico em calvárias de ratos.
Abstract: The purpose of this study was to histologically analyze the influence of Platelet Rich Plasma (PRP) on bone healing in surgically created critical-size-defects (CSD) in rat calvaria. 32 rats were divided into 2 groups: C (control) and PRP (Platelet Rich Plasma). An 8 mm diameter CSD was created in the calvarium of each animal. In Group C the defect was filled by blood clot only. In Group PRP it was filled with Platelet Rich Plasma. Both groups were divided into subgroups (n=8) and euthanized at either 4 or 12 weeks post-operative. Histometric, using image analysis software, and histologic analyses were performed. Amount of new bone was calculated as percentage of total area of original defect. Percentage data were transformed into arccosine for statistical analysis (ANOVA, Tukey, p < 0.05). No defect completely regenerated with bone. Group PRP had a statistically greater amount of bone formation than Group C at both 4 (17.68% and 7.20%, respectively) and 12 weeks (24.69% and 11.65%, respectively) post-operative. Within the limits of this study, it can be concluded that PRP significantly enhanced bone healing in critical-size-defects in rat calvaria.
Mestre

Orientador: Maria José Hitomi Nagata
Banca: Mário Taba Junior
Banca: Álvaro Francisco Bosco
Banca: Ronaldo Célio Mariano
Banca: Valdir Gouveia Garcia
Resumo: O objetivo do presente trabalho foi avaliar, histologicamente, a influência da associação do plasma rico em plaquetas (PRP) ao enxerto de osso autógeno (OA) no reparo ósseo de defeitos de tamanho crítico (DTC) em calvárias de coelhos. Sessenta coelhos foram divididos em 3 grupos: C (controle), OA (osso autógeno) e OA/PRP (osso autógeno associado ao plasma rico em plaquetas). Um defeito de tamanho crítico, com 15 mm de diâmetro, foi criado na calvária de cada animal. No Grupo C, o defeito foi preenchido somente com coágulo sanguíneo. No Grupo OA, o defeito foi preenchido com osso autógeno particulado. No Grupo OA/PRP, o defeito foi preenchido com osso autógeno particulado associado ao PRP. Todos os grupos foram divididos em subgrupos (n = 10) para eutanásia aos 30 ou 90 dias pós-operatórios. Foram realizadas análises histológica e histométrica. A quantidade de osso neoformado foi calculada como uma porcentagem da área total do defeito original. Os dados em porcentagem foram transformados em raiz quadrada para análise estatística (ANOVA, teste t, p<0,05). Aos 30 dias pós-operatórios, o Grupo OA/PRP apresentou uma quantidade significativamente maior de osso neoformado que o Grupo OA (64,44% e 46,88%, respectivamente). Aos 90 dias, todos os espécimes dos Grupos OA/PRP e OA mostraram fechamento ósseo completo do defeito, com quantidades similares de osso neoformado (77,9% e 75%, respectivamente). Dentro dos limites deste trabalho, pode-se concluir que o PRP acelerou o processo de reparo do enxerto de osso autógeno em defeitos de tamanho crítico em calvária de coelhos.
Abstract: The purpose of this study was to histologically analyze the effect of platelet-rich plasma (PRP) on bone healing in an autogenous bone graft placed in surgically created criticalsize defects (CSD) in rabbit calvaria. 60 rabbits were divided into 3 groups: C (control); AB (autogenous bone graft) and AB/PRP (autogenous bone graft with platelet-rich plasma). A 15 mm diameter CSD was created in the calvarium of each animal. In Group C the defect was filled by blood clot only. In Group AB the defect was filled with particulate autogenous bone. In Group PRP it was filled with particulate autogenous bone in combination with platelet-rich plasma. All groups were divided into subgroups (n=10) and euthanized at either 30 or 90 days post-operative. Histometric, using image analysis software, and histologic analyses were performed. Amount of new bone was calculated as a percentage of the total area of the original defect. Percentage data were transformed into square root for statistical analysis (ANOVA, t test, p<0.05). At 30 days post-op, Group AB/PRP had a statistically greater amount of bone formation than Group AB (64.44% and 46.88%, respectively). At 90 days, complete bone regeneration of the defect was seen in all specimens of Groups AB/PRP and AB, with similar amounts of newly formed bone (77.9% and 75%, respectively). Within the limits of this study, it can be concluded that PRP accelerated the healing of autogenous bone graft in critical-size defects in rabbit calvaria.
Doutor

Orientador: Giuseppina Pace Pereira Lima
Banca: João Domingos Rodrigues
Banca: Moacir Pasqual
Banca: Antonio Natal Gonçalves
Banca: Alessandra Marcondes Feijó Viu
Resumo: Este trabalho teve como objetivo avaliar os efeitos da aplicacao exogena de poliaminas e TIBA (antiauxina) na micropropagacao e anatomia foliar de plantulas de abacaxizeiro eIAC Gomo-de-melf e analisar os teores de poliaminas endogenas, atividade de peroxidase, proteina, IAA-oxidase e a provavel relacao com as diferentes fases da micropropagacao. Inicialmente, retiraram-se as gemas da coroa de frutos sadios e a assepsia foi realizada com hipoclorito de sodio comercial (2 a 2,5% de cloro ativo) a 30% por 20 minutos e lavadas por 3 vezes em agua destilada e autoclavada. Em seguida, inocularam-se as gemas em meio MS solido contendo diferentes combinacoes de BAP (0; 0,5; 1,0 e 1,5 mg L-1) e NAA (0; 0,5 e 1,0 mg L-1). Apos 60 dias, foram selecionados os melhores tratamentos para proliferacao das brotacoes, que foram individualizadas e transferidas para estes meios por mais trinta dias, em meio MS liquido. Plantas oriundas do experimento anterior tiveram as folhas cortadas e apenas segmentos de 1 cm foram inoculados em meio MS liquido contendo os diferentes tratamentos: T1-MS, T2-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA, T3-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM SPD, T4-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM SPM, T5-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM PUT, T6-MS + 10 mM SPD, T7-MS + 10 mM SPM e T8-MS + 10 mM PUT. Na ultima fase, segmentos foram inoculados em meio MS liquido contendo os tratamentos: T1-MS, T2-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA, T3-MS + 0,5 ƒÊM TIBA, T4-MS + 1,0 ƒÊM TIBA, T5-MS + 2,0 ƒÊM TIBA, T6-MS + 4,0 ƒÊM TIBA, T7-MS + 8,0 ƒÊM TIBA e T8-MS + 16,0 ƒÊM TIBA. Apos, as plantas foram aclimatizadas em substrato Plantmax e houve 100% de sobrevivencia, independente do tratamento. Foram realizados cortes histologicos foliares para estudar a influencia das poliaminas e TIBA na anatomia foliar...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The effects of exogenous polyamines and TIBA (antiauxin) application in the micropropagation, leaf anatomy of pineapple plants ‘IAC Gomo-de-mel’ and the contents of endogenous polyamines, peroxidase activity, protein, IAA-oxidase and probable relationship with the different micropropagation phases were studied. Initially, the axillary bud explants were excised from the crown of healthy fruits and the asepsis was accomplished with sodium hypochloride (2 to 2,5% of active chlorine) 30% for 20 minutes and washed 3 times in distilled and autoclaveted water. After, the axillary buds were inoculated in MS solid medium containing the different BAP (0; 0,5; 1,0 and 1,5 mg L-1) and NAA (0; 0,5 and 1,0 mg L-1) combinations. After 60 days, the best treatments were selected for shoot proliferation that were individualized and transferred to these media for more 30 days, in MS liquid medium. Plants from the previous experiment had the leaves cut and just 1 cm segments were inoculated in MS liquid medium containing the different treatments: T1-MS, T2-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA, T3-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM SPD, T4- MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM SPM, T5-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA + 10 mM PUT, T6-MS + 10 mM SPD, T7-MS + 10 mM SPM and T8-MS + 10 mM PUT. In the last phase, segments were inoculated in MS liquid medium containing the treatments: T1-MS, T2-MS + 1,0 mg L-1 BAP + 0,5 mg L-1 NAA, T3-MS + 0,5 mM TIBA, T4-MS + 1,0 mM TIBA, T5-MS + 2,0 mM TIBA, T6-MS + 4,0 mM TIBA, T7-MS + 8,0 mM TIBA and T8-MS + 16,0 mM TIBA. After, the plants were acclimatizated in Plantmax substrate and there were 100% survival, independent of the treatment. Leaf cuts were made to study polyamines and TIBA influence in the leaf anatomy. The highest shoot number wasobserved with 1,0 mg L-1 BAP + 0,5 mg L-1 NAA, however with hyperhydricity...(Complete abstract click electronic access below)
Doutor

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

Early scientific knowledge recognized two basic types of substances: beneficial ones (such as foods and medicines), and harmful ones (those that cause sickness or death). The latter were designated as poisons. Modern science acknowledges that such a strict division is not justified. As early as the sixteenth century, Paracelsus recognized that ‘‘the right dose differentiates a poison and a remedy.’’ Many chemical substances or mixtures exert a whole spectrum of activities, ranging from beneficial to neutral to lethal. Their effect depends not only on the quantity of the substance to which an organism is exposed, but also on the species and size of the organism, its nutritional status, the method of exposure, and several related factors. Alcohol is a good example. Taken in small quantities, alcohol may be harmless and sometimes even medically recommended. However, an overdose causes intoxication and, in extreme cases, death. Similarly, vitamin A is required for the normal functioning of most higher organisms, yet an overdose of it is highly toxic. If the biological effect of a chemical is related to its dose, there must be a measurable range between concentrations that produce no effect and those that produce the maximum effect. The observation of an effect, whether beneficial or harmful, is complicated by the fact that apparently homogeneous systems are, in fact, heterogeneous. Even an inbred species will exhibit marked differences among individuals in response to chemicals. An effect produced in one individual will not necessarily be repeated in another one. Therefore, any meaningful estimation of the toxic potency of a compound will involve statistical methods of evaluation. To determine the toxicity of a compound for a biological system, an observable and well-defined end effect must be identified. Turbidity or acid production, reflecting the growth or growth inhibition of a culture, may be used as an end point in bacterial systems. In some cases, such as in the study of mutagenesis, colony count may be used. Similarly, measures of viable cells, cell protein, or colony count are useful end points in cell cultures.

Hormones, produced by glands or cells, are messengers which act locally or at a distance to coordinate the function of cells and organs. Types of hormone include: peptides (e.g. hypothalamic releasing factors) and proteins (e.g. insulin, growth hormone)—these generally interact with membrane receptors located on the cell surface, causing activation of downstream signalling pathways leading to alteration in gene transcription or modulation of biochemical pathways to effect a physiological response; steroids (e.g. cortisol, progesterone, testosterone, oestradiol) and other lipophilic substances (e.g. vitamin D, retinoic acid, thyroid hormone)—these act by crossing the plasma membrane to interact with intracellular receptors, with hormone action via nuclear receptors altering cellular gene expression directly.

Hormones, produced by glands or cells, are messengers which act locally or at a distance to coordinate the function of cells and organs. Types of hormone include (1) peptides (e.g hypothalamic releasing factors) and proteins (e.g. insulin, growth hormone)—these generally interact with membrane receptors located on the cell surface, causing activation of downstream signalling pathways leading to alteration in gene transcription or modulation of biochemical pathways to effect a physiological response; (2) steroids (e.g. cortisol, progesterone, testosterone, oestradiol) and other lipophilic substances (e.g. vitamin D, retinoic acid, thyroid hormone)—these act by crossing the plasma membrane to interact with intracellular receptors, with hormone action via nuclear receptors altering cellular gene expression directly....

Mobile phone use has exponentially grown worldwide from a few subscribers in the 1970s to more than 6 billion in 2013. As mobile phones are frequently replaced and upgraded, enormous volumes of mobile phones are retired each year. Mobile phones and accessories typically contain a variety of valuable elements as well as many toxic chemicals. The toxic substances may cause serious human health problems if they are not properly managed. Thus, environmentally sound management of used and end-of-life mobile phones is an issue of growing concern around the world. Although a large quantity of mobile phones are disposed each year, only a small fraction of these phones are collected and managed, and collection programs occur primarily in developed countries. Considering the potential environmental impacts of used and end-of-life mobile phones, understanding the current knowledge of the management of mobile phone waste is critical. This chapter reviews the generation rates, collection systems and recycling, and the impacts of obsolete mobile phones, based on review of available literature and research conducted by a number of leading and pioneering scholars in the field.

In the previous two chapters, we listened to the daughters, in their own voices, describe the myriad experiences that helped to promote their academic success, in general, and in math and science, in particular. As the daughters told their stories, and described their respective journeys to Black womanhood, they touched on several critical areas in their lives, beyond academics. In this chapter, we narrow our focus and take a closer look at their personal, cultural, and emotional challenges. (For the purposes of this discussion, “cultural” challenges refer to those pertaining to race, ethnicity, and gender.) As we listen to the daughters’ voices, we learn that these young women share many experiences—some because they are women, some because they are Black, some because they are Black women, and some because they are human. Specifically, we focus on the daughters’ experiences in the following areas: (1) dating and sexual intimacy, (2) depression and substance abuse, (3) self-esteem and body-image, (4) racial and ethnic identity, and (5) race, gender, and their intersection. The challenges we discuss occurred both within and outside of school contexts, and from preschool through post-college years. We often hear that every challenge presents an opportunity for growth. As we listen to the daughters describe their personal battles, we gain a better understanding of the nature of such challenges. In some instances, we also see how these obstacles became motivating forces in the young women’s lives, and how they overcame the challenges. In addition, we learn about the many resources the daughters used to respond to personal, cultural, and emotional difficulties. For instance, parents often served as an important resource either by preparing their daughters for future challenges, having taught them values and given them advice, or by playing an active role at the time of the challenge. We also learn that religion and spirituality proved important to the majority of the daughters in terms of preparing them for and overcoming obstacles. We discuss the critical role of religion and spirituality at the end of this chapter.

I recall a true story about an Ozark farmer who telephoned his neighbors one fine June day asking for help in getting in his hay. Arriving at the hayfield, people found the farmer baling his hay, but without twine in the baler. Unbound piles of hay, which would have to be entirely reraked and rebaled, lay all over the field. The farmer, with a bottle of whiskey in his lap, was feeling no pain, as they say, and did not seem to notice the problem, nor did the dozen or so men, similarly anesthetized, standing around the pickup trucks at the edge of the field. Believing the lack of twine to be a serious problem, one of the volunteers, a newcomer to such haying operations, suggested putting a roll of twine in the baler. To which an old-timer replied: “Naw, no need for that. Ol’ Billy-Hugh [the farmer in question] is having too much fun to stop now.” This story says something important about intention. Those of us who arrived on the scene ready to work failed to understand that the purpose of the event had nothing to do with getting in hay. This was a party, haying the pretext. Once we understood that, all of us could get in the flow, so to speak. A good many things, including politics, work similarly. One of the best books ever written about politics, The Symbolic Uses of Politics (Edelman 1962), develops the thesis that the purpose of political activity is often not to solve problems but only to appear as if doing so. The politics of sustainability, unfortunately, provide no obvious exception to this tendency to exalt symbolism over substance. And of symbols and words there is no end. The subject of sustainability has become a growth industry. Government- and business-sponsored councils, conferences, and public meetings on sustainability proliferate, most of which seem to be symbolic gestures to allay public anxieties, not to get down to root causes.

Antibiotics include an extensive range of agents able to kill or prevent reproduction of bacteria in the body, without being overly toxic to the patient. Traditionally derived from living organisms, most are now chemically synthesized and act to disrupt the integrity of the bacterial cell wall, or penetrate the cell and disrupt protein synthesis or nucleic acid replication. Typically, bacteria are identified according to their ap­pearance under the microscope depending on shape and response to the Gram stain test. Further identification is obtained by growth characteristics on various types of culture media, based on broth or agar, biochemical and immunological profiles. Further testing on broth or agar determines antibiotic sensitivity to guide on anti­biotic therapy in individual patients. This process can take 24– 48 hours to culture and a further 24– 48 hours to measure sensitivities. Increasingly, new technology, e.g. Matrix Assisted Laser Desorption Ionization— Time of Flight (MALDI- TOF) and nucleic acid amplification as­says, are being used to provide more rapid identification. The Gram classification, however, is still widely referred to as it differentiates bacteria by the presence or absence of the outer lipid membrane (see Figure 11.1), a fundamental characteristic that influences antibiotic management. Antimicrobial agents rely on selective action exploiting genetic differences between bacterial and eukaryotic cells. They target bacterial cell wall synthesis, bacterial protein synthesis, microbial DNA or RNA synthesis, by acting on bacterial cell metabolic pathways or by inhibiting the ac­tion of a bacterial toxin (see Table 11.1). Both Gram- positive and Gram- negative bacteria possess a rigid cell wall able to protect the bacteria from varying osmotic pressures (Figure 11.1). Peptidoglycan gives the cell wall its rigidity and is composed of a glycan chain of complex alternating carbohydrates, N- acetylglucosamide (N- ATG), and N- acetylmurcarinic acid (N- ATM), that are cross- linked by peptide (or glycine) chains. In Gram-positive bacteria, the cell wall contains multiple peptido­glycan layers, interspersed with teichoic acids, whereas Gram- negative bacteria contain only one or two peptido­glycan layers that are surrounded by an outer membrane attached by lipoproteins. The outer membrane contains porins (which regulate transport of substances into and out of the cell), lipopolysaccharides, and outer proteins in a phospholipid bilayer. For both Gram- negative and Gram-positive bacteria, peptidoglycan synthesis involves about 30 bacterial enzymes acting over three stages. Since the cell wall is unique to bacteria, it makes a suitable target for antibiotic therapy.

The research we have discussed suggests that schizophrenia occurs when ab­normal genes and environmental risk factors combine to cause brain dys­function. In the past two decades, several researchers— notably Drs Daniel Weinberger, Larry Seidman, and Patricia Goldman- Rakic— have concluded that schizophrenia is a neurodevelopmental brain disorder. This suggests that schizophrenia emerges because of the way the brain is built early in life. To understand this concept, consider brain disorders that do not have a neurodevelopmental origin but instead, come about because of the way the brain breaks down after it is developed. We call these disorders neurodegenerative be­cause the causes of the disease attack and degrade a normal brain. The senility of old age, which doctors call dementia, is a common example. When some people age, their brain is degraded by events such as many strokes or the rav­ages of Alzheimer’s disease. After a few years, a person who once functioned normally can no longer do simple tasks. Other examples are acquired brain syndromes, which occur after an injury to the head, and disorders due to the in­gestion of toxic substances (e.g., drugs, lead paint). In each of these cases, some external agent has acted on a normal brain to make it abnormal. In neurodevelopmental disorders, the brain does not develop (i.e., grow) prop­erly. In other words, it was never really normal to begin with. We know that genes contain the ‘blueprint’ for building the brain. For schizophrenia, this blueprint contains errors so that the brain is not ‘built’ correctly. Dr Patricia Goldman- Rakic suggested that certain brain cells in individuals with schizophrenia do not ‘migrate’ correctly during development. That is, normal brain development re­quires that cells locate themselves in the right spot and connect to one another in specific patterns. In schizophrenia, it may be that some cells are in the wrong place, some do not make necessary connections, and others make connections that should not be made. It is as if the blueprint for a home told the electrician to put the light switch for the kitchen in the living room.

Overview The adhesion-aggregation of platelets to a site of vessel wall injury is a quintessential blood flow phenomenon. Firstly, platelets are driven to the vicinity of the vessel wall by a form of convective diffusion in which red cells both mechanically augment the effective platelet diffusivity (Turitto et al., Ind. Eng. Chem. Fund. 11:216-223, 1972; Grabowski et al., Ind. Eng. Chem. Fund. 11:224-232, 1972) and enhance the near-wall piatelet concentration (Ti11es and Eckstein, Microvasc Res., In press, 1987). Secondly, red cells subjected to physiologic shear forces are capable of secreting sufficient adenine nucleotides to induce primary platelet aggregation without themselves undergoing frank lysis (Reimers et al, Blood 64:1200-1206, 1984). This "humoral" effect of erythrocytes is likely to contribute to primary hemostasis in a shear stress-dependent manner. Thirdly, endothelial cells are able to modulate platelet aggregation at a site of vessel injury by producing prostacyclin (and perhaps other antithrombotic substances) in a manner which increases with vessel shear rate (Grabowski et al, Blood 62:301a, 1983); production for a large range of arterial shear rates appears to be limited by plasma-borne substrate (arachidonate). This manner of production ensures a concentration of prostacyclin in the near-wall region which remains relatively independent of shear rate.Imaging primary hemostasis. In our work, epi-fluorescence videomicroscopy has allowed real time imaging of platelet adhesion-aggregation to a simulated vessel wall injury. The injury model is an endothelial cell monolayer (ECM) across which, prior to ECM exposure to flowing blood, a 6-0 sterile suture is drawn in a direction transverse to flow. Microinjuries result which measure 70 ± 15μm (Mean ± SD) in width. The fluorescent label is the TAB murine monoclonal antibody (courtesy of Dr. R.P. McEver) directed against human platelet GPIIB, together with a fluorescein-conjugated goat F(ab')2 against murine inmunoglobulin. The injured ECM's, grown to confluence on rectangular cover glasses precoated with microfibrillar collagen, comprise one wall of a flow chamber mounted on a vertical microscope stage. On microinjury sites and at shear rates of 100 to 700 sec-1, computer-enhanced video images show adherence, remodelling and growth of chains of platelet aggregates. Aligned with the flow direction, these chains have a spacing of approximately 30)im, a length similar to the average endothelial cell diameter. One may speculate that such chains provide a scaffold for wound healing insofar as they are likely rich in agents chemotactic for leukocytes and in platelet-derived growth factor.Modulatory role of endothelium. When the ECM's are pre treated with 1.0 mM FC lysine acetyl sal icy late (LA), aggregate length increases (P<0.001) up totwo-fold, outflow levels by RIA of serum thromboxane B2 increase (8 of 8 paired runs), and outflow levels of prostacyclin by RIA for 6-Keto PGFiot decrease (5 of 7 paired runs). The Table gives data for one of four similar experiments at 270 sec-1 and following five minutes of flow. These data imply that products of ECM which are inhibitable by aspirin modulate local adhesion-aggregation; their inhibition, as by vasculitis or drugs, may give rise to thrombotic states.Bleeding disorders. Aggregate length is reduced in von Willebrand's disease (4 patients), Hermansky-Pudlak syndrome (2 patients), and after 300 mg oral aspirin (Tablet 4 donors). The reduction in the first two, however, is greater (P<0.01) than that for oral aspirin. With oral aspirin, further, there is a paradoxic increase in the percent platelet coverage of the injury area. Summary. Rheology has profound effects on the rate, structure, and modulation of primary hemostasis. Many of these effects can be studied via real-time, epi-fluorescence videomicroscopy of platelet adhesion-aggregation to a site of injury to an endothelial cell monolayer exposed to flowing blood. The model described has application to the study of thrombotic and hemostatic disorders and unstable angina.

Analysis of special features of the reproductive system of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1845) females from the Azov and Black Sea Basin at the end of the winter season, 2019, has been conducted using the size of oocytes as its basis. Individual differences in distribution of oocyte sizes during the period of trophoplazmatic growth have been identified. Following the estimation of ordered series of oocyte sizes during the period of trophoplazmatic growth, the median and percentile values have been calculated; they can be used as reference values for qualitative characterization of ordered series for oocyte diameter in an individual specimen, using the empirical median, calculated for the respective specimen, as a basis. It has been found out that the sizes of trophoplazmatic growth oocytes, which are utilized during the spawning period of the current year, and, therefore, the degree of gonad maturity have individual characteristics independent of the age of an individual, of its length and weight, and of the content of reserve and bioactive substances in its tissues and blood.

This paper identifies and explores possible safety implications of RoHS (Restriction of Hazardous Substances) compliance on railway equipment, with the purpose of presenting this topic for further consideration in North American industry standards, e.g. AREMA (American Railway Engineering and Maintenance-of-Way Association) guidelines. Of specific interest is the topic of tin whiskers, which are known to grow in electric circuits that are Lead free. Tin whiskers have the ability to bridge the gap between two vital signals in a circuit, creating the possibility for a potentially hazardous scenario to occur in a safety-critical system. As rail transportation technologies become progressively more dependent on safety critical electronics that are RoHS compliant, the subject of tin whiskers merits its due consideration in the industry. There are verified incidents of tin whiskers having adverse impact in the automotive and aerospace industries; examples are provided in the paper. If precautionary measures are not respected, it is possible that a short circuit resulting from tin whiskers may lead to an undesirable incident in the rail industry also. Research has shown that there are proven techniques which can inhibit tin whisker growth to an acceptable level. Mitigating measures and their effectiveness in deterring whisker growth are discussed in this paper. Awareness is essential in prevention of a hazard. Railroads and Transit agencies that recognize hazards posed by metal whisker growth will be in a better position to evaluate the safety of RoHS compliant products provided by system integrators, who, in turn, must account for the issues presented in this paper in their internal quality processes. In due course, the safety implications of RoHS transitioning should be considered in an industry-wide guideline such as AREMA, laying the foundation for future RoHS compliant railway equipment that is safeguarded against safety concerns from tin whisker growth.

The termination finish of Small Output Integrated Circuit (SOIC) and Small Output Transistor (SOT) chip components were converted from Pb-free to Sn-Pb (backward conversion) and vice versa (forward conversion). The motivation for these conversions is due to a combination of factors such as the supply chain constraints on component availability, European Union’s (EU) legislation on “Restriction of Hazardous Substances” (or RoHS), and the growth of tin whiskers on matte tin finish components. The conversions were performed using a “Robotic Stripping and Solder Dipping Process”, and the mechanical reliability of the converted components was evaluated through lead pull testing. In this experiment, a 100% (all finishes are given in weight percentage unless otherwise specified) matte tin finish was first stripped and re-plated with an eutectic Sn-Pb finish. Then, components with 100% matte tin and eutectic Sn-Pb termination finish were replaced with a Pb-free Sn-3.5%Ag-0.5%Cu (SAC305) finish. Three Printed Circuit Board (PCB) surface finishes namely Immersion Silver (ImAg), Organic Solderable Preservative (OSP), and Electroless Nickel/Immersion Gold (ENIG), were evaluated with Sn-Pb and Pb-free processes. All the assembled boards were subjected to an initial analysis, which includes visual inspection with an optical microscope and X-Ray analysis. Subsequently, a time zero analysis was performed which includes cross sectioning, Scanning Electron Microscope (SEM) analysis and lead pull testing. The pull testing was performed on a Chatillon TCM 201-SS equipment. All the leads were pulled orthogonal to the surface of the PCB. After isothermal aging at 150°C for a time period of 10 days (240 hours), cross sectioning and pull testing were performed to study its effect on Intermetallic Compound (or IMC) growth and reliability.