Artículos de revistas: "Testis Effect of heat on"

1

Hamilton, Thais Rose dos Santos, Adriano Felipe Perez Siqueira, Letícia Signori de Castro, Camilla Mota Mendes, Juliana de Carvalho Delgado, Patrícia Monken de Assis, Leonardo Pereira Mesquita et al. "Effect of Heat Stress on Sperm DNA: Protamine Assessment in Ram Spermatozoa and Testicle". Oxidative Medicine and Cellular Longevity 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/5413056.

Texto completo

Resumen

Sperm DNA fragmentation is considered one of the main causes of male infertility. The most accepted causes of sperm DNA damage are deleterious actions of reactive oxygen species (ROS), defects in protamination, and apoptosis. Ram sperm are highly prone to those damages due to the high susceptibility to ROS and to oxidative stress caused by heat stress. We aimed to evaluate the effects of heat stress on the chromatin of ejaculated and epididymal sperm and the activation of apoptotic pathways in different cell types in ram testis. We observed higher percentages of ejaculated sperm with increased chromatin fragmentation in the heat stress group; a fact that was unexpectedly not observed in epididymal sperm. Heat stress group presented a higher percentage of spermatozoa with DNA fragmentation and increased number of mRNA copies of transitional protein 1. Epididymal sperm presented greater gene expression of protamine 1 on the 30th day of the spermatic cycle; however, no differences in protamine protein levels were observed in ejaculated sperm and testis. Localization of proapoptotic protein BAX or BCL2 in testis was not different. In conclusion, testicular heat stress increases ram sperm DNA fragmentation without changes in protamination and apoptotic patterns.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Hu, Suqin, Dianlong Liu, Sijia Liu, Chunrui Li y Jian Guo. "Lycium barbarum Polysaccharide Ameliorates Heat-Stress-Induced Impairment of Primary Sertoli Cells and the Blood-Testis Barrier in Rat via Androgen Receptor and Akt Phosphorylation". Evidence-Based Complementary and Alternative Medicine 2021 (3 de mayo de 2021): 1–10. http://dx.doi.org/10.1155/2021/5574202.

Texto completo

Resumen

Male infertility induced by heat stress has been attracting more and more attention. Heat stress not only causes apoptosis of spermatocytes but also has adverse effects on Sertoli cells, further damaging spermatogenesis. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum, which has a protective effect on male reproduction, but its mechanism is still unclear. In this study, our results proved that LBP blocked the inhibitory effect on the proliferation activity of Sertoli cells after heat stress, reversed the dedifferentiation of Sertoli cells induced by heat stress, and ameliorated the structural integrity of the blood-testis barrier. In addition, it increased the expression of the androgen receptor and activated Akt signaling pathway to resist heat-stress-induced injury of Sertoli cells.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Setchell, B. P., A. Locatelli, C. Perreau, C. Pisselet, I. Fontaine, C. Kuntz, J. Saumande, J. Fontaine y M. T. Hochereau-de Reviers. "The form and function of the Leydig cells in hypophysectomized rams treated with pituitary extract when spermatogenesis is disrupted by heating the testes". Journal of Endocrinology 131, n.º 1 (octubre de 1991): 101–12. http://dx.doi.org/10.1677/joe.0.1310101.

Texto completo

Resumen

ABSTRACT The morphology and in-vivo function of the Leydig cells were studied in rams when spermatogenesis had been disrupted by a single exposure of the testes 20 days earlier to a temperature of about 42 °C for 45 min. To avoid complications due to changed negative feedback from the testes to the pituitary with consequent changes in the degree of gonadotrophic stimulation, ten of the animals (five heated and five unheated) were surgically hypophysectomized when the testes were heated and then treated twice daily with pituitary extract. Six intact rams (three heated and three unheated) were also studied. The heat-affected testes were about half the size of the unheated testes, and blood plasma flow was closely related to testis weight. There were no differences in the testosterone concentrations in spermatic venous blood, testicular lymph or rete testis fluid, or in oestradiol in spermatic venous plasma from heated or unheated testes. Consequently, testosterone secretion by the heat-affected testes was markedly reduced, and the concentrations in jugular blood were also lower in the heat-affected rams than in controls. The volume of the interstitial tissue was less in absolute terms in the heat-affected rams, but it made up a greater fraction of the testes. The absolute volume of the blood plus lymph vessels, and their fraction of the interstitial tissue were lower in the heat-affected testes, although there was no effect on their volume as a fraction of the whole testis. The heat-affected testes of the hormone-treated rams had fewer Leydig cells, but each cell was larger; no equivalent difference was found in the intact rams. However, the dose of pituitary extract chosen was somewhat excessive, as there were higher than normal concentrations of FSH, LH and testosterone in jugular blood plasma, of testosterone and oestradiol in testicular venous blood plasma and of testosterone in rete testis fluid in the hormone-treated hypophysectomized rams. The testes of the unheated hypophysectomized rams increased in size by about 20% during treatment with pituitary extract, although testicular blood plasma flow was lower per unit weight of testis. The absolute volume of each Leydig cell and the total volume in absolute terms and as a fraction of the interstitial tissue was greater in the hormone-treated than in the untreated rams, but not the volume as a fraction of the whole testis. The total number of Leydig cells was higher in the hormone-treated unheated rams than in all the other rams taken together. It would therefore appear that when spermatogenesis was disrupted following heating of the testes and the gonadotrophic stimulation was kept constant, the Leydig cells underwent hypertrophy, presumably because of a change in the secretion of paracrine factor(s) by the tubules. However, there was also a decrease in testosterone secretion, which was closely related to decreases in blood plasma flow through the testes, and bore little or no relation to the number, total volume or size of the Leydig cells, or the concentration of testosterone in the testicular venous blood. Journal of Endocrinology (1991) 131, 101–112

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Kheradmand, Arash, Omid Dezfoulian y Mohammad Javad Tarrahi. "Ghrelin attenuates heat-induced degenerative effects in the rat testis". Regulatory Peptides 167, n.º 1 (febrero de 2011): 97–104. http://dx.doi.org/10.1016/j.regpep.2010.12.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Guo, Jian, Shi-Xin Tao, Min Chen, Yu-Qiang Shi, Zhu-Qiang Zhang, Yin-Chuan Li, Xue-Sen Zhang, Zhao-Yuan Hu y Yi-Xun Liu. "Heat Treatment Induces Liver Receptor Homolog-1 Expression in Monkey and Rat Sertoli Cells". Endocrinology 148, n.º 3 (1 de marzo de 2007): 1255–65. http://dx.doi.org/10.1210/en.2006-1004.

Texto completo

Resumen

We demonstrated in this study that liver receptor homolog-1 (LRH-1) was expressed in the round spermatids in normal monkey testis, and no LRH-1 signal was observed in the Sertoli cells. After local warming (43 C) the monkey testis, however, LRH-1 expression was induced in the Sertoli cells in coincidence with activation of cytokeratin 18 (CK-18), a Sertoli cell dedifferentiated marker. Furthermore, we isolated rat primary Sertoli cells from testes at various stages of development and treated with 43 C water in vitro. The changes in LRH-1 as well as CK-18 expression were analyzed by confocal immunohistochemistry and Western blot. The results showed that LRH-1 was stage-dependently expressed in the Sertoli cells; no LRH-1-positive signal was detected in the cells obtained from the testes of adult rat on d 60 after birth when mature spermatozoa in the testis was completed. However, the mature Sertoli cells were warmed at the 43 C water bath for 15 min, and the LRH-1 signal was remarkably induced in a time-dependent manner, just like the changes of CK-18 expression in the Sertoli cells, suggesting that the heat-induced dedifferentiation of the mature Sertoli cells might be related to LRH-1 regulation. LRH-1 expression induced by the heat treatment was completely inhibited by the addition of ERK inhibitor U0126 in the culture, indicating that the heat-induced LRH-1 expression in the Sertoli cells may be regulated via ERK1/2 activation pathway. Testosterone was found to have no such effect on LRH-1 expression in the monkey and rat Sertoli cells.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Hou, Ying, Peipei Yuan, Yang Fu, Qi Zhang, Yaxin Wei, Liyuan Gao, Li Liu, Xiaolan Wang, Xiaoke Zheng y Weisheng Feng. "Duzhong Butiansu Prescription Improves Heat Stress-Induced Spermatogenic Dysfunction by Regulating Sperm Formation and Heat Stress Pathway". Evidence-Based Complementary and Alternative Medicine 2020 (27 de febrero de 2020): 1–11. http://dx.doi.org/10.1155/2020/6723204.

Texto completo

Resumen

Background. Duzhong Butiansu (DZBTS) prescription contains many traditional Chinese medicines and has been shown to have a curative effect on male fertility. However, the efficacy and mechanism of DZBTS in the treatment of male infertility induced by heat stress have not been reported. The aim of the present study is to elucidate the effect and mechanism of DZBTS on spermatogenic function of a heat stress model in rats. Methods. Male Wistar rats (280–320 g) were given different doses of DZBTS (0.4853 g/kg/d or 0.9707 g/kg/d), Shengjing capsule (0.56 g/kg/d), or double distilled water for 15 days. A 43°C hot water bath for 30 minutes was used to stimulate the testis of rats. Sperm count, sperm motility, the organ index of kidney and gonadal organs, serum sex hormone levels, and serum oxidising reaction index were measured. Haematoxylin and eosin (HE) staining was used to observe the morphology of the testis and kidney. The expression of Hsp70 in testes was observed by immunofluorescence. The changes in heat stress, reproductive-related protein, and mRNA were measured by western blot assay and RT-qPCR. Results. Heat stress downregulated the levels of sex hormone (P<0.05 or P<0.01) and its receptor androgen receptor (AR) protein expression and mRNA (P<0.01) in rats. Meanwhile, heat stress downregulated the levels of CAMP-responsive element-binding (CREB1) protein and mRNA (P<0.01), which are involved with spermatogenesis. Heat stress also decreased the oxidative damage index. Furthermore, Hsp70 and the heat shock transcription factor 1 (HSF1) protein pathway and mRNA level were overactivated (P<0.05 or P<0.01). Finally, the organ coefficients of the kidney and gonadal organs of rats were decreased. The sperm concentration and motility also decreased significantly (P<0.01). DZBTS could recover these changes induced by heat stress. Conclusions. Our results for the first time have found that DZBTS can improve spermatogenesis disorder in a heat stress model in rats, which may be mainly by regulating AR, sperm regulatory protein CREB1, and the HSF/Hsp70 signaling pathway to decrease oxidative stress.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Mohajeri, D. y R. Kaffashi Elahi. "Effects of Nigella sativa on heat-induced testis damage in mouse". Bratislava Medical Journal 116, n.º 04 (2015): 264–69. http://dx.doi.org/10.4149/bll_2015_051.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Rahman, A., MM Hossain, M. Khan, MT Kamal y MA Hashem. "Effect of Heat Stress on Bucks Adaptability and Semen Characteristics". Journal of Environmental Science and Natural Resources 9, n.º 1 (8 de noviembre de 2016): 151–56. http://dx.doi.org/10.3329/jesnr.v9i1.30309.

Texto completo

Resumen

The experiment was conducted to investigate the effect of heat stress on adaptability and semen quality of buck. Almost similar 10 Black Bengal bucks were selected for the study at Artificial Insemination Centre, Bangladesh Agricultural University, Bangladesh. Prerequisite biological data were collected from each animal before keeping them sun heat and after 1 hour sun exposure. Different semen characteristics of each animal were measured. Temperature humidity index (THI) was 19.95 in the morning which indicate all the animals were in absence of heat stress and THI was 25.54 in the noon which indicate all the animals were in severe heat stress at noon. Buck 1 and buck 5 were more heat resistant (p<0.01), because their thermolysis capacity (TC) values were less than the others. There were no differences in tunica dartos index and semen characteristics among different bucks (p>0.05). Positive correlation between sperm motility and testis length (p<0.05), and negative correlation between sperm concentration and scrotal skin temperature (p<0.05) were found. From the study it can be concluded that all the bucks were in severe heat stress at noon time and TC can be used as an indicator for selection of buck for heat tolerance.J. Environ. Sci. & Natural Resources, 9(1): 151-156 2016

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Yaeram, J., B. P. Setchell y S. Maddocks. "Effect of heat stress on the fertility of male mice in vivo and in vitro". Reproduction, Fertility and Development 18, n.º 6 (2006): 647. http://dx.doi.org/10.1071/rd05022.

Texto completo

Resumen

A study was conducted to determine whether following exposure of male mice to high temperatures, the ability of their spermatozoa to fertilise ova was reduced, especially during the period before the males became completely infertile. Male mice placed in a microclimate chamber at 36°C for two periods, each of 12 h on successive days, were less able to fertilise control females in vivo when mated and, even in those females that became pregnant, litter size was reduced. However, these effects were associated with falls in testis weight and numbers of spermatozoa in the testis and epididymis. To determine whether the effect on fertility was a result of the decreased spermatozoa numbers, spermatozoa were collected from the epididymides of heated and control males. Equal numbers of motile spermatozoa from an unselected sample or those subjected to a swim-up procedure to separate those that were motile from the immotile ones in the sample were then mixed in vitro with oocytes from superovulated normal females. Similar numbers of spermatozoa from both control and heated males bound to the zona pellucida but smaller percentages of the oocytes were fertilised by spermatozoa from the heated males and fewer of these spermatozoa penetrated the ova. The effects were first seen 7 days after the heat exposure and became more obvious after 10 or 14 days.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Koide, Y., T. Ono, C. Ishinami y K. Yamashita. "Alterations in activities of calmodulin and heat-stable calmodulin-binding protein in rat testis". American Journal of Physiology-Cell Physiology 250, n.º 2 (1 de febrero de 1986): C299—C305. http://dx.doi.org/10.1152/ajpcell.1986.250.2.c299.

Texto completo

Resumen

Effects of postnatal development, surgical cryptorchidism, and hypophysectomy on the activity of calmodulin and of a 32,000-molecular weight (32) calmodulin-binding protein (Ono et al., J. Biol. Chem. 259: 9011-9016, 1984) were examined in rat testis. In adult rats, approximately 95% of their activities distributed in seminiferous tubule preparation, and most of them were in the 105,000-g supernatant. Both activities were low early in the development, but the calmodulin activity increased between 25 and 45 days of age, and the 32 K calmodulin-binding protein activity increased between 35 and 45 days of age. In contrast, surgical cryptorchidism caused a rapid decline in their activities in the abdominal testis, whereas their activities in a scrotal testis did not decline. Hypophysectomy similarly resulted in a gradual decline in their activities. Replacement of follicle-stimulating hormone or testosterone for 7 days from 30 days after hypophysectomy did not quantitatively restore either the testes weight or the activities of the proteins. The results indicate a primary distribution of both proteins in mature germ cells.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Chen, Z., J. R. Zhang, Y. W. Zhou, C. Liang y Y. Y. Jiang. "Effect of heat stress on the pituitary and testicular development of Wenchang chicks". Archives Animal Breeding 58, n.º 2 (13 de octubre de 2015): 373–78. http://dx.doi.org/10.5194/aab-58-373-2015.

Texto completo

Resumen

Abstract. To study the effects of heat stress (HS) on the growth and reproductive performance of chicks, 1-day-old male Wenchang chicks were randomly selected and divided into control (CK) and HS groups. The two groups of birds were fed according to a routine. The chicks in the HS group were placed under HS for 2 h day−1 (temperature, 40 ± 0.5°; humidity, 63.0–80.0 %) until the sixth week. At the end of each week, six chicks were randomly selected from each group and dissected for pituitary and testicular tissues, which were then weighed and sectioned onto slides to observe the histological changes in pituitary and testis under a microscope. Our results indicated that compared with the CK group, with the increase in age, HS significantly reduced the feed conversion rate (FCR) and weight gain per week, and these changes were positively correlated. The pituitary and testicular weights and volumes of chicks in the HS group were significantly lower than those in the CK group (P < 0.05). For 3-week old chicks, the cross-sectional area of seminiferous tubule in chicks of the HS group was extremely significantly lower than that of the CK group (P < 0.01). Compared with the CK group, the seminiferous epithelium was thinner in the HS group, the arrangement of spermatogenic cells became loose and irregular, and the integrity of the histological structure of testicular tissues was also damaged. Therefore, the above results indicated that HS significantly impeded the growth and development of pituitary and testis in chicks.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Kumazawa, T., K. Mizumura, M. Minagawa y Y. Tsujii. "Sensitizing effects of bradykinin on the heat responses of the visceral nociceptor". Journal of Neurophysiology 66, n.º 6 (1 de diciembre de 1991): 1819–24. http://dx.doi.org/10.1152/jn.1991.66.6.1819.

Texto completo

Resumen

1. Whether bradykinin (BK), which is known as an endogenous pain-producing substance, induces augmentation of the discharges of polymodal receptors evoked by heat stimulation was investigated in in vitro canine testis-superior spermatic nerve preparations. 2. The heat response was significantly augmented by pretreatments with BK at concentrations greater than 0.094 nM, whereas BK induced significant increases in the mean discharge rates at concentrations above 9.4 nM. Both effects increased in a concentration-dependent manner. The augmenting effect of BK on the heat response diminished within 10 min after application of BK, regardless of concentration. 3. When 9.4 nM BK was applied in a mixture with 940 nM NPC349, a B2 receptor antagonist, the averaged mean discharge rate evoked by BK and the averaged augmenting effect were both significantly suppressed compared with those induced by BK given alone. 4. The augmenting effect of BK on the heat response of polymodal receptors could be observed even in the absence of BK-evoked discharges per se in several cases in which low concentrations of BK or BK plus B2 antagonists were given. 5. These findings suggest that the augmenting effects of BK on the heat response depend on B2 receptor-mediated intracellular processes acting in parallel to, but not directly on, the impulse-generation mechanism of the heat response of the polymodal receptor.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Al-Bagdadi, F., R. Stout, S. Farouqi, P. Crawford, M. Kearny, J. O’Donnell y S. Husein. "Apoptosis In Experimental Unilateral Abdominal Cryptorchid Testis In Rat". Microscopy and Microanalysis 5, S2 (agosto de 1999): 1182–83. http://dx.doi.org/10.1017/s1431927600019231.

Texto completo

Resumen

It has been reported that cryptorchidism caused disruption of spermatogenesis that become extensive with time (1). The process of spermatogenesis undergoes spontaneous degeneration in rats, the spermatids degenerate, the primary spermatocytes have been reported to degenerate more commonly (2). Apoptosis has been considered the route for removing sensitive germ cells after short-term experimental cryptorchidism (3). The abdominal heat stress causes cell loss by apoptotic pathway (4). The cellular damage of the experimentally induced cryptorchid adult rat is regulated by local testicular factors in pachytene spermatocyte (5). In this preliminary diagnostic study, we examined the role of the effect of the body temperature on the seminiferous tubule cells in surgically induced unilateral cryptorchid testis at various time periods in rats. This study is to document the extent of the cellular damage at various specified time periods of abdominal retention of the testis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Forte, L. R., W. J. Krause y R. H. Freeman. "Escherichia coli enterotoxin receptors: localization in opossum kidney, intestine, and testis". American Journal of Physiology-Renal Physiology 257, n.º 5 (1 de noviembre de 1989): F874—F881. http://dx.doi.org/10.1152/ajprenal.1989.257.5.f874.

Texto completo

Resumen

The distribution of receptors for Escherichia coli enterotoxin were examined in opossum kidney, intestine, and testis. E. coli enterotoxin stimulated guanosine 3',5'-cyclic monophosphate (cGMP) production in renal cortex, testis, and small intestinal mucosa but had only a small effect in the colon. Atrial natriuretic factor enhanced the cGMP content of renal cortex and small intestine but had no effect on testis or colon. The enterotoxin receptors were observed to be localized in proximal tubules, to epithelial cells of crypts and villi of small intestine, to crypts of colon, and in seminiferous tubules. Both convoluted and straight portions of proximal tubules exhibited specific binding sites for 125I-labeled enterotoxin. Glomeruli and distal tubules did not have receptors. Binding of 125I-enterotoxin to brush-border membranes of kidney cortex or intestinal mucosa and to testis membranes was markedly temperature dependent. The binding affinities of these receptors for E. coli enterotoxin were similar (i.e., IC50 approximately equal to 0.4-0.5 nM). Daily administration of 20 micrograms of enterotoxin intramuscularly to opossums increased urine cGMP excretion with no apparent changes in urine volume, Na+, or K+ excretion. Thus receptors for heat-stable enterotoxins are localized to proximal tubules of kidney and to enterocytes and seminiferous tubules of intestine and testis, respectively. Apical membranes may be the site of enterotoxin receptors in these epithelia.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Jahanbani G, Ashkan y Tom A. Jelmert. "Effect of Heat Loss on Pressure Falloff Tests". International Journal of Engineering Trends and Technology 39, n.º 1 (25 de septiembre de 2016): 28–36. http://dx.doi.org/10.14445/22315381/ijett-v39p205.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Nicholson, H. D., H. M. Greenfield y J. Frayne. "The effect of germ cell complement on the presence of oxytocin in the interstitial and seminiferous tubule fluid of the rat testis". Journal of Endocrinology 143, n.º 3 (diciembre de 1994): 471–78. http://dx.doi.org/10.1677/joe.0.1430471.

Texto completo

Resumen

Abstract In the rat testis oxytocin has been localized to the Leydig cells, and these cells have been shown to produce oxytocin in vitro. The present study was performed to determine whether oxytocin is present in the interstitial fluid (IF) and seminiferous tubule fluid (TF) of the rat and whether concentrations of the peptide vary within the two compartments following germ cell destruction. In order to destroy germ cells adult male rats were anaesthetized and their scrotal regions placed in a water bath at 43 °C for 20 min. Control animals were subjected to anaesthesia alone. Groups of 6 animals were killed 3, 7 and 21 days after heat treatment and their testes removed for histological examination or fluid extraction. IF and TF were separated and the oxytocin content of the fluids measured by radioimmunoassay. Immunoreactive oxytocin was detected in both the IF (100 ±11 pg/ml) and TF (27± 4 pg/ml) of control rats and this immunoreactivity co-eluted with the authentic peptide following HPLC. Three days after heat treatment IF levels of oxytocin were significantly reduced but TF levels of the peptide were significantly increased. These changes were associated with a lack of pachytene spermatocytes in the histological sections. Seven and 21 days after heat treatment the levels of oxytocin in the IF and TF were not significantly different from control levels. Similar changes in IF and TF oxytocin levels were seen in a second experiment when pachytene spermatocytes were removed using the testicular toxicant methoxyacetic acid. To investigate whether oxytocin passes from the IF into the TF, 3H-oxytocin was infused into the testicular arteries of both control and heat-treated rats and the rats killed at regular intervals over the next 24 h. In both groups of animals <5% of the 3H-oxytocin passed from the IF into the TF. These data suggest that the seminiferous tubule as well as the Leydig cells may secrete oxytocin and that this secretion may be influenced by the presence of germ cells, particularly pachytene spermatocytes. Journal of Endocrinology (1994) 143, 471–478

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Holets, Lesya, Sudhakar Jakkaraj, Ramappa Chakrasali, Gunda I. Georg y Joseph S. Tash. "Effect of Gamendazole on Expression of Heat Shock Proteins HSP70 and HSP90 in Rat Testis and Primary Sertoli Cells." Biology of Reproduction 81, Suppl_1 (1 de julio de 2009): 129. http://dx.doi.org/10.1093/biolreprod/81.s1.129.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

James, L. A. y W. J. Mills. "Effect of Heat-Treatment Upon the Fatigue-Crack Growth Behavior of Alloy 718 Weldments—Part I: Macroscopic Behavior". Journal of Engineering Materials and Technology 107, n.º 1 (1 de enero de 1985): 34–40. http://dx.doi.org/10.1115/1.3225768.

Texto completo

Resumen

Gas-tungsten-arc weldments in Alloy 718 were studied in fatigue-crack growth tests conducted at five temperatures over the range 24–649°C. In general, crack growth rates increased with increasing temperature, and weldments given the “conventional” post-weld heat-treatment generally exhibited crack growth rates that were higher than for weldments given the “modified” (INEL) heat-treatment. Limited testing in the as-welded condition revealed crack growth rates significantly lower than observed for the heat-treated cases, and this was attributed to residual stresses. Three different heats of filler wire were utilized, and no heat-to-heat variations were noted.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Liao, Zebin, Zhe Liu, Zhenyu Gong, Xuguang Hu, Yuanyuan Chen, Kun Cao, Hong Zhang et al. "Heat-killed Salmonella Typhimurium protects mice against carbon ion radiation". Journal of International Medical Research 48, n.º 10 (octubre de 2020): 030006052092425. http://dx.doi.org/10.1177/0300060520924256.

Texto completo

Resumen

Objective Patients receiving carbon-ion radiation therapy and astronauts exploring outer space are inevitably exposed to heavy ion radiation. The aim of this study was to develop radioprotectors to minimize the injuries induced by carbon ion radiation. Methods Heat-killed Salmonella Typhimurium (HKST) was administered to mice by gavage prior to irradiation with a 12C6+ heavy ion accelerator. Hematoxylin and eosin staining and immunofluorescence TdT-mediated dUTP Nick-End Labeling staining were used to assess the radioprotective effect of HKST on organ damage and levels of apoptosis, respectively, in mice. To investigate the mechanism underlying the radioprotective effect of HKST, levels of the pro-apoptotic proteins BAX and caspase 3 as well as interferon-regulatory factor (IRF) 3/7 in the femur, testis and intestine were assessed using immunofluorescence. Results Injuries induced by carbon ion radiation were significantly eased by pretreatment with HKST. Both apoptosis and high expression levels of pro-apoptotic proteins induced by heavy ion radiation were inhibited by HKST pretreatment. The radioprotective effect of HKST was associated with stimulation of Toll-like receptor signaling mediated by enhanced IRF3 and IRF7 signaling. Conclusion HKST was an effective radioprotector alleviating damage to multiple organs caused by heavy ion radiation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Breitenbach, Anthony T., Amanda W. Carter, Ryan T. Paitz y Rachel M. Bowden. "Using naturalistic incubation temperatures to demonstrate how variation in the timing and continuity of heat wave exposure influences phenotype". Proceedings of the Royal Society B: Biological Sciences 287, n.º 1932 (5 de agosto de 2020): 20200992. http://dx.doi.org/10.1098/rspb.2020.0992.

Texto completo

Resumen

Most organisms are exposed to bouts of warm temperatures during development, yet we know little about how variation in the timing and continuity of heat exposure influences biological processes. If heat waves increase in frequency and duration as predicted, it is necessary to understand how these bouts could affect thermally sensitive species, including reptiles with temperature-dependent sex determination (TSD). In a multi-year study using fluctuating temperatures, we exposed Trachemys scripta embryos to cooler, male-producing temperatures interspersed with warmer, female-producing temperatures (heat waves) that varied in either timing during development or continuity and then analysed resulting sex ratios. We also quantified the expression of genes involved in testis differentiation ( Dmrt1 ) and ovary differentiation ( Cyp19A1 ) to determine how heat wave continuity affects the expression of genes involved in sexual differentiation. Heat waves applied during the middle of development produced significantly more females compared to heat waves that occurred just 7 days before or after this window, and even short gaps in the continuity of a heat wave decreased the production of females. Continuous heat exposure resulted in increased Cyp19A1 expression while discontinuous heat exposure failed to increase expression in either gene over a similar time course. We report that even small differences in the timing and continuity of heat waves can result in drastically different phenotypic outcomes. This strong effect of temperature occurred despite the fact that embryos were exposed to the same number of warm days during a short period of time, which highlights the need to study temperature effects under more ecologically relevant conditions where temperatures may be elevated for only a few days at a time. In the face of a changing climate, the finding that subtle shifts in temperature exposure result in substantial effects on embryonic development becomes even more critical.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Nasir, Gulboy A. "Effect of magnetized water on morphologically abnormal sperms and histopathological status of testis in mice". Journal of Biotechnology Research Center 6, n.º 2 (17 de junio de 2012): 28–35. http://dx.doi.org/10.24126/jobrc.2012.6.2.217.

Texto completo

Resumen

ifty white Swiss male mice (6-7) weeks of age were randomly divided into two groups, and each group included 25 mice. Group 1 (treatment group) were get magnetic water, group 2 (control group) were get tap water. After whole experimental period (16 weeks), Animals sacrificed and sperms were collected from epididimyes, then histopathology for testis tissue was done and morphologically abnormal sperm of head sperm percentage were calculated. Results revealed that abnormalities of head sperm percentage in treatment group 0.99% were reduced compared with control group 1.03%, but the differences were not significant. Means of narrow head, loss hook head, hammer head and bacillary head in control group were insignificantly (P>0.05) more than treatment group, but mean of spherical head in treatment group 1.63 was mathematically higher than its similar in control group 1.44, simple correlation coefficient between all kinds of abnormalities was insignificant except that between loss hook head and hammer head (-0.27) which exhibited significant differences (p<0.05). No significant reduction was observed in motality percentage of sperms, dead and abnormalities of sperms in the treatment group compared to control group. Significant increase (P<0.01) was observed in seminiferous tubules diameters in the treatment group, whereas primary spermatocytes, spermatids and interstitial spaces exhibited insignificant increase in treatment group compared with control group.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Aydilek, N., O. Varisli, M. S. Kaya, A. Kocyigit y A. Taskin. "272 EFFECT OF DIETARY RESTRICTION ON SPERM CHARACTERISTICS AND OXIDATIVE STATUS ON TESTICULAR TISSUE IN YOUNG RATS EXPOSED TO LONG-TERM HEAT STRESS". Reproduction, Fertility and Development 27, n.º 1 (2015): 225. http://dx.doi.org/10.1071/rdv27n1ab272.

Texto completo

Resumen

The objective was to evaluate effects of dietary restriction on oxidative status and sperm parameters in rats exposed to long-term heat stress. Forty healthy Sprague-Dawley rats (2.5 months old) were equally allocated into 4 groups (with respect to diet and temperature): room temperature (22°C)-ad libitum; room temperature-dietary restriction (40%); high temperature (38°C)-ad libitum; and high temperature-dietary restriction. At the end of the 9th week, some oxidants (lipid hydroperoxide, total oxidant status, oxidative stress index) and some antioxidants (total antioxidant status, sulfhydryl groups, ceruloplasmin, paraoxonase and arylesterase activities) were measured in testicular tissues. In addition, concentration, motility, volume, abnormal sperm count, acrosome and membrane integrity of epididymal sperm were also evaluated. All data were analysed by 2-way ANOVA (P < 0.05). High temperature did not significantly affect most oxidative and antioxidative parameters (except for sulfhydryl groups and ceruloplasmin), yet it impaired all sperm values. Neither sperm values nor oxidative status, with the exception of sulfhydryl groups, ceruloplasmin and arylesterase in the testis tissue, were significantly affected by dietary restriction. We concluded that long-term heat stress did not significantly affect testicular oxidative status in young rats, although sperm were sensitive to heat stress. Furthermore, dietary restriction failed to improve sperm quality and oxidative status, except some individual antioxidant parameters in young rats exposed to long-term heat stress.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Pei, Yangli, Yingjie Wu y Yinghe Qin. "Effects of chronic heat stress on the expressions of heat shock proteins 60, 70, 90, A2, and HSC70 in the rabbit testis". Cell Stress and Chaperones 17, n.º 1 (10 de agosto de 2011): 81–87. http://dx.doi.org/10.1007/s12192-011-0287-1.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Tabassum, Rahila, Karim Gabol ., Masarrat Yousuf . y M. Z. Khan . "Induced Effect of Pesticides on Pigeon (Liver, Kidney, Testis, Heart uscles and Fat)". Journal of Biological Sciences 3, n.º 5 (15 de abril de 2003): 496–501. http://dx.doi.org/10.3923/jbs.2003.496.501.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Anoh, K. U. "Effect of baobab fruit pulp meal on testosterone concentration and gonadal and epididymal morphometry of rabbit bucks in a hot environment". Nigerian Journal of Animal Production 44, n.º 3 (2 de enero de 2021): 98–103. http://dx.doi.org/10.51791/njap.v44i3.613.

Texto completo

Resumen

The aim of the study was to evaluate the effect of baobab fruit pulp meal on testosterone concentration and gonadal and epididymal morphometry of rabbit bucks during hot season in Nigeria. A total of 25 bucks of 10-12 months old were used. There were five (5) rabbits per group grouped as follows; T1 (control) and T2-T5 (Diets with graded levels of BFPM at 2.5%,3.5%, 4.5% and 5.5% inclusion levels, respectively). The experiment lasted for nine weeks. All management practices were duly observed. Three bucks were selected from each treatment group and slaughtered. The two testes of each of the rabbits were carefully removed and evaluated for their morphometric. The weight, length and volume of each testis were determined. It was found that the treatments with 3.5 – 5.5% BFPM significantly (P<0.05) increased testosterone concentration, weight and size of the gonad and the epididymis. It was concluded that BFPM is more effective in ameliorating heat stress in rabbit production and reproduction and can be used up to 5.5% inclusion level.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Andersson, K., S. Kivivuori y A. S. Korhonen. "Effect of the heat-transfer coefficient in ring-compression tests". Journal of Materials Processing Technology 62, n.º 1-3 (noviembre de 1996): 10–13. http://dx.doi.org/10.1016/0924-0136(95)02141-8.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Mobaraki, Fahimeh, Masoumeh Seghatoleslam, Alireza Fazel y Alireza Ebrahimzadeh-Bideskan. "Effects of MDMA (ecstasy) on apoptosis and heat shock protein (HSP70) expression in adult rat testis". Toxicology Mechanisms and Methods 28, n.º 3 (5 de noviembre de 2017): 219–29. http://dx.doi.org/10.1080/15376516.2017.1388461.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Sahyoun, C., S. W. Kingman y N. A. Rowson. "The Effect of Heat Treatment on Chalcopyrite". Physical Separation in Science and Engineering 12, n.º 1 (1 de enero de 2003): 23–30. http://dx.doi.org/10.1080/1478647031000101296.

Texto completo

Resumen

The influence of conventional heat treatment and microwave radiation on chalcopyrite was investigated. There was a significant increase in the proportion of material recovered to magnetic fraction and magnetic susceptibility with conventional heating time. XRD analysis detected phase changes in conventional heat-treated chalcopyrite, which increases the magnetic susceptibility of the ore and enables its effective magnetic separation, which is impossible to achieve in its original state.With microwave treatment, the magnetic susceptibility increases and the proportion of material recovered to magnetic fraction on the induced rolls is also increased. However, XRD analysis failed to detect any phase changes. A possible explanation for this observed behaviour is that the more magnetic component that has been formed by microwave treatment is below the threshold of detection of the XRD analyser. Taking into account that results from the froth flotation tests indicated that % weight fraction in the concentrate decreases with microwave exposure time, the change might be due to a surface effect.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Zheng, Mulian, Yanjuan Tian y Litao He. "Analysis on Environmental Thermal Effect of Functionally Graded Nanocomposite Heat Reflective Coatings for Asphalt Pavement". Coatings 9, n.º 3 (7 de marzo de 2019): 178. http://dx.doi.org/10.3390/coatings9030178.

Texto completo

Resumen

The heat-reflective coating for asphalt pavement is a functional layer applied on pavement surfaces to reduce heat storage in the pavement via reflecting sunlight, thus inhibiting pavement temperature rise. The objective of this study was to analyze the environmental thermal effect of the self-developed reflective coating, namely, functionally graded nanocomposite reflective coatings, for asphalt pavement. The thermal effects of heat-reflective coatings were compared and analyzed based on field tests. A heating model of the atmosphere layer near the road surface was established. Moreover, the influence of urban road temperature on the thermal comfort of the human body was analyzed. Results showed that the radiation heat of all heat-reflective coatings decreased around two-thirds, and the convective heat decreased nearly 50% when compared with the control asphalt pavement, and the temperatures of the pavement itself and the atmosphere layer were lowered. Additionally, the heat-reflective coating improved the thermal comfort of the human body. This indicated that the heat-reflective coating reduced ambient temperate and relieved the urban heat island effect (UHI) as well as improved the environmental thermal effect.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Obiukwu, Osita, Henry Udeani y Progress Ubani. "The Effect of Heat Treatment on the Mechanical Properties of SAE 1035 Steel". International Journal of Engineering and Technologies 8 (agosto de 2016): 32–43. http://dx.doi.org/10.18052/www.scipress.com/ijet.8.32.

Texto completo

Resumen

The effect of various heat treatment operations (annealing, normalizing, tempering) on mechanical properties of 0.35% carbon steel was investigated. The change in the value of endurance limit of the material as a result of the various heat-treatment operations were studied thoroughly. It was found that the specimens tempered at low temperature (200°C) exhibited the best fatigue strength. Microscope was used to characterize the structural properties resulting from different heat treatment processes. The results from the tensile tests impact tests and hardness tests showed that the mechanical properties variate at every heat-treatment conditions. The microstructure of differently heat-treated steels was also studied.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Obiukwu, Osita, Henry Udeani y Progress Ubani. "The Effect of Heat Treatment on the Mechanical Properties of SAE 1035 Steel". International Journal of Engineering and Technologies 8 (9 de agosto de 2016): 32–43. http://dx.doi.org/10.56431/p-t11557.

Texto completo

Resumen

The effect of various heat treatment operations (annealing, normalizing, tempering) on mechanical properties of 0.35% carbon steel was investigated. The change in the value of endurance limit of the material as a result of the various heat-treatment operations were studied thoroughly. It was found that the specimens tempered at low temperature (200°C) exhibited the best fatigue strength. Microscope was used to characterize the structural properties resulting from different heat treatment processes. The results from the tensile tests impact tests and hardness tests showed that the mechanical properties variate at every heat-treatment conditions. The microstructure of differently heat-treated steels was also studied.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Cheung, Stephen S. y Tom M. McLellan. "Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress". Journal of Applied Physiology 84, n.º 5 (1 de mayo de 1998): 1731–39. http://dx.doi.org/10.1152/jappl.1998.84.5.1731.

Texto completo

Resumen

—The purpose of the present study was to determine the separate and combined effects of aerobic fitness, short-term heat acclimation, and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40°C, 30% relative humidity). Men who were moderately fit [(MF); <50 ml ⋅ kg−1 ⋅ min−1maximal O2 consumption; n = 7] and highly fit [(HF); >55 ml ⋅ kg−1 ⋅ min−1maximal O2 consumption; n = 8] were tested while they were euhydrated or hypohydrated by ∼2.5% of body mass through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after 2 wk of daily heat acclimation (1-h treadmill exercise at 40°C, 30% relative humidity, while wearing the nuclear, biological, and chemical protective clothing). Heat acclimation increased sweat rate and decreased skin temperature and rectal temperature (Tre) in HF subjects but had no effect on tolerance time (TT). MF subjects increased sweat rate but did not alter heart rate, Tre, or TT. In both MF and HF groups, hypohydration significantly increased Tre and heart rate and decreased the respiratory exchange ratio and the TT regardless of acclimation state. Overall, the rate of rise of skin temperature was less, while ΔTre, the rate of rise of Tre, and the TT were greater in HF than in MF subjects. It was concluded that exercise-heat tolerance in this uncompensable heat-stress environment is not influenced by short-term heat acclimation but is significantly improved by long-term aerobic fitness.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Forn, Antonio, Maite T. Baile, Enric Martín, Javier Goñi y I. Sarriés. "Heat Treatments Effect on A357 Components Produced by SSM". Solid State Phenomena 116-117 (octubre de 2006): 181–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.181.

Texto completo

Resumen

The present work studies the effect the solution heat treatment, during artificial ageing and re-aging, has on the mechanical properties of an A357 aluminium alloy component formed by New Rheocasting. The effect that the evolution of silicon, during the solution treatment at various times, has on the mechanical properties was also examined. The mechanical properties were evaluated performing tensile tests, fractographical analysis and hardness tests. The microstructural characterization was made using optical and electronic microscopy.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Yu, Kai, Yao Wang, Yanxin Li, Jakov Baleta, Jin Wang y Bengt Sundén. "Effect of phase change materials on heat dissipation of a multiple heat source system". Open Physics 17, n.º 1 (31 de diciembre de 2019): 797–807. http://dx.doi.org/10.1515/phys-2019-0083.

Texto completo

Resumen

AbstractThis paper experimentally investigates heat dissipation of a heat pipe with phase change materials (PCMs) cooling in a multiple heat source system. Two heat sources are fixed at one end of the heat pipe. Considering that a heat sink cannot dissipate all the heat generated by two heat sources, various PCMs are used due to a large latent heat. Different materials in a container are wrapped outside of the middle heat pipe to take away the heat from the evaporation section. The experimental tests obtain temperature data of heat source, evaporation section, and energy storage characteristics of PCMs are also determined under constant and dynamic values of the heat source powers. It is found that under this multiple heat source system structure, the phase change material RT35 maintains temperature variations of the evaporation section at a lower temperature and shortens the required time to reach the equilibrium temperature under a heating power of 20 W.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Filipczak, Piotr Teodor, Wojciech Piglowski, Magdalena Glowala-Kosinska, Zdzislaw Krawczyk y Dorota Scieglinska. "HSPA2 overexpression protects V79 fibroblasts against bortezomib-induced apoptosis". Biochemistry and Cell Biology 90, n.º 2 (abril de 2012): 224–31. http://dx.doi.org/10.1139/o11-083.

Texto completo

Resumen

Human HSPA2 is a member of the HSPA (HSP70) family of heat-shock proteins, encoded by the gene originally described as testis-specific. Recently, it has been reported that HSPA2 can be also expressed in human somatic tissues in a cell-type specific manner. The aim of the present study was to find out whether HSPA2 can increase the resistance of somatic cells to the toxic effect of heat shock, proteasome inhibitors, and several anticancer cytostatics. We used a Chinese hamster fibroblast V79 cell line because these cells do not express the HSPA2 and cytoprotective HSPA1 proteins under normal culture conditions and show limited ability to express HSPA1 in response to heat shock and proteasome inhibitors. We established, by retroviral gene transfer, a stable V79/HSPA2 cell line, which constitutively overexpressed HSPA2 protein. The major observation of our study was that HSPA2 increased long-term survival of cells subjected to heat shock and proteasome inhibitors. We found, that HSPA2 confers resistance to bortezomib-induced apoptosis. Thus, we showed for the first time that in somatic cells HSPA2 can be a part of a system protecting cells against cytotoxic stimuli inducing proteotoxic stress.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

KOSTUGANOV, Arman B. "RESEARCH OF HEAT DISPOSAL EFFICIENCY IN RECUPERATIVE HEAT EXCHANGERS OF AUTONOMOUS VENTILATION UNITS". Urban construction and architecture 10, n.º 1 (15 de marzo de 2020): 36–46. http://dx.doi.org/10.17673/vestnik.2020.01.6.

Texto completo

Resumen

Full-scale tests of recuperative heat exchangers of autonomous ventilation units of a new design were carried out in order to determine the efficiency of heat recovery in them. As a result of the tests, it was found that the efficiency of heat recovery in such recuperative heat exchangers varies from 40 to 70 %, depending on the initial parameters of the supply and exhaust air. It was also found that in order to achieve the same heat recovery effect, it is advisable to use the construction of heat exchangers with corrugated mesh than the construction with corrugated plates because the first construction with a comparable heat recovery effect provides up to one and a half times lower aerodynamic drag. During the tests was also made an approbation of a new protection scheme for recuperative heat exchangers against freezing.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Chaturapanich, G., S. Chaiyakul, V. Verawatnapakul y C. Pholpramool. "Effects of Kaempferia parviflora extracts on reproductive parameters and spermatic blood flow in male rats". REPRODUCTION 136, n.º 4 (octubre de 2008): 515–22. http://dx.doi.org/10.1530/rep-08-0069.

Texto completo

Resumen

Krachaidum (KD, Kaempferia parviflora Wall. Ex. Baker), a native plant of Southeast Asia, is traditionally used to enhance male sexual function. However, only few scientific data in support of this anecdote have been reported. The present study investigated the effects of feeding three different extracts of KD (alcohol, hexane, and water extracts) for 3–5 weeks on the reproductive organs, the aphrodisiac activity, fertility, sperm motility, and blood flow to the testis of male rats. Sexual performances (mount latency, mount frequency, ejaculatory latency, post-ejaculatory latency) and sperm motility were assessed by a video camera and computer-assisted sperm analysis respectively, while blood flow to the testis was measured by a directional pulsed Doppler flowmeter. The results showed that all extracts of KD had virtually no effect on the reproductive organ weights even after 5 weeks. However, administration of the alcohol extract at a dose of 70 mg/kg body weight (BW)/day for 4 weeks significantly decreased mount and ejaculatory latencies when compared with the control. By contrast, hexane and water extracts had no influence on any sexual behavior parameters. All types of extracts of KD had no effect on fertility or sperm motility. On the other hand, alcohol extract produced a significant increase in blood flow to the testis without affecting the heart rate and mean arterial blood pressure. In a separate study, an acute effect of alcohol extract of KD on blood flow to the testis was investigated. Intravenous injection of KD at doses of 10, 20, and 40 mg/kg BW caused dose-dependent increases in blood flow to the testis. The results indicate that alcohol extract of KD had an aphrodisiac activity probably via a marked increase in blood flow to the testis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Gareh, Salim y Zakaria Boumerzoug. "HEAT TREATMENT EFFECT ON THE CREEP OF INDUSTRIAL COPPER WIRE". Acta Metallurgica Slovaca 22, n.º 3 (27 de septiembre de 2016): 181. http://dx.doi.org/10.12776/ams.v22i3.725.

Texto completo

Resumen

<p class="Default">Creep behavior of copper wire, produced by wiredrawing process in ENICAB Biskra, has been investigated by creep tests at 340°C under the stress 98,108 and 118 MPa. In this investigation, three samples have been tested: copper drawn wire non heat treated, and heat treated at 600°C and 700°C. Microstructure after the creep test was observed by optical microscopy to understand the rupture mechanism. We have found that the sample heat treated at 600 °C had a longer creep life. We have also deduced that the dislocation creep was the creep deformation mechanism of the drawn copper. SEM observations of fractured surfaces after creep tests of drawn copper wire non heat treated and treated 10 min at 600 ° C under stress of 118 MPa.</p>

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Abe, Fujio. "Behavior of Boron in 9Cr Heat Resistant Steel during Heat Treatment and Creep Deformation". Key Engineering Materials 345-346 (agosto de 2007): 569–72. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.569.

Texto completo

Resumen

The effect of boron on microstructure evolution and creep deformation behavior has been investigated for a tempered martensitic 9Cr-3W-3Co-0.2V-0.05Nb steel at 650oC. Creep tests were carried out at 650oC for up to about 6 x 104 h. The addition of boron retards the onset of acceleration creep at low stress and long time conditions, which results in lower minimum creep rate and longer time to rupture. The addition of boron also retards the Ostwald ripening of M23C6 carbides near prior austenite grain boundaries (PAGBs) during creep. The retardation of the onset of acceleration creep results from the retardation of the recovery of martensitic microstructure near PAGBs by pinning effects due to fine M23C6 carbides. The main effect due to boron is considered to occupy vacancies near growing M23C6 carbides, which makes it difficult to accommodate local volume change around the growing carbides. This reduces the rate of Ostwald ripening of M23C6 carbides.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Zheng, Yi, Yao Hui Liu, Yu Lai Song, Jia’an Liu, Ling Nan Kong y Yan Liang. "Effect of Welding Heat Input on Microstructure and Softening Behavior of 5CrMoV Steel". Key Engineering Materials 735 (mayo de 2017): 42–48. http://dx.doi.org/10.4028/www.scientific.net/kem.735.42.

Texto completo

Resumen

Three different heat input combinations for the medium carbon alloy steels 5CrMoV are compared in terms of the heat affected zone of microstructures, hardness, and tensile properties. The microstructures in the heat affected zone are predominately ferrite and bainite, with grain size variation in different sub-zones and different heat input. Analyses of the micro-hardness profiles indicated that softening phenomenon occurs in the entire heat affected zone, and high heat input resulted in the greatest decrease in hardness. The results of the tensile tests reveal tensile properties of the heat affected zone deteriorate with the increase of heat input, and the region at temperatures near Ac1 is the weakest part of heat affected zone.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Naheed, Kishwar, Humaira Ali, Fareeha Mushtaq, Muhammad Saad Abdullah, Maria Yousaf, Noreen Anwar y Talha Laique. "Effects of Microwave Oven Exposed Diet on Animal Weight and Testicular Tissue and Relative Role of Mentha Piperita". Pakistan Journal of Medical and Health Sciences 15, n.º 9 (30 de septiembre de 2021): 2352–54. http://dx.doi.org/10.53350/pjmhs211592352.

Texto completo

Resumen

Background: Usage of electronic gadgets like microwave oven is increasing day by day that heats the food by exposing it to electromagnetic radiations which has many hazardous effects on human health including fertility. Aim: To find the effects of microwave oven exposed diet on weight and testis of mice along with protective effects of Mentha Piperita and Melatonin Study Design: Randomized control trial. Methodology: Adult male mice (n=32) were divided into four groups. Control group (G1) received standard pellets prepared for mice. Second group (G2) was given mice pellets exposed to microwave oven. Third group (G3) received Mentha Piperita leaf extract along with mice pellets exposed to microwave oven and the fourth group (G4) received oral melatonin along with pellets exposed to microwave oven. After experimental period, wt of each mice was again recorded and then mice were sacrificed. Data analyzed by SPSS 21.0v. Results: There was no statistically significant difference of weight gain of animals but there was significant reduction in weight of testis in group G2 but in G3 and G4 wt of the testis was close to control. Conclusion: It was concluded that microwave oven exposed diet had no significant effect on overall weight gain of the animal but it significantly reduced weight of the testis in group G2. However, Mentha Piperita and Melatonin both had ameliorative effects on the wt of the testicular tissue. Keywords: Mice, Testis, Weight, Mentha piperita and Melatonin

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Paul, Catriona, Alison A. Murray, Norah Spears y Philippa T. K. Saunders. "A single, mild, transient scrotal heat stress causes DNA damage, subfertility and impairs formation of blastocysts in mice". REPRODUCTION 136, n.º 1 (julio de 2008): 73–84. http://dx.doi.org/10.1530/rep-08-0036.

Texto completo

Resumen

Infertility represents a major clinical problem and 50% of cases are attributable to the male partner. Testicular function is temperature dependent, and in both man and mouse the position of the testes in the scrotum ensures that they are kept at between 2 and 8 °C below core body temperature. We used a mouse model to investigate the impact of a single, transient, mild, scrotal heat stress (38, 40 or 42 °C for 30 min) on testicular function, sperm DNA integrity and embryo survival. We detected temperature-dependent changes in testicular architecture, number of apoptotic cells and a significant reduction in testis weight 7 and 14 days after heat stress at 42 °C. We report for the first time that DNA strand breaks (γ-H2AX-positive foci) were present in spermatocytes recovered from testes subjected to 40 or 42 °C. Fertility of heat-stressed males was tested 23–28 d after treatment (sperm at this time would have been spermatocytes at time of heating). Paternal heat stress at 42 °C resulted in reduced pregnancy rate, placental weight and litter size; pregnancies from the 40 °C group had increased resorptions at e14.5. Abnormalities in embryonic development were detected at e3.5 and in vitro fertilisation with sperm recovered 16 h or 23 d after scrotal stress at 42 °C revealed a block in development between the 4-cell and blastocyst stages. This study has provided evidence of temperature-dependent effects on germ cell DNA integrity and highlighted the importance of an intact paternal genome for normal embryo development.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Boumerzoug, Zakaria, Zakaria Boumerzoug y Vincent Ji. "Heat Treatments Effect on the Mechanical Properties of Industrial Drawn Copper Wires". Advanced Materials Research 811 (septiembre de 2013): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amr.811.9.

Texto completo

Resumen

In this present investigation, the mechanical properties of industrial drawn copper wires have been studied by creep tests, tensile tests and hardness Vickers. The effect of prior heat treatments at 500°C for different time on the drawn wires behavior was the main goal of this investigation. We have found that these heat treatments influenced the creep behavior of drawn wires and recorded shape curves. The creep tests were applied under ambient atmosphere at 240 °C. The creep duration before rupture decreased with the prior heat treatment time. The creep tests results were confirmed by tensile tests. A relationship between the hardness and the ultimate tensile strength of this industrial material has been established. Optical and scanning electron microscopy observations have been also used. Cross section observations of the wire after tensile or creep-rupture tests have shown that the mechanism of rupture was mainly controlled by the void formation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Djurumana, Yohana, Reny I’tishom y Bambang Purwanto. "Pemberian Ekstrak Rumput Kebar (Biophytum petersianum Klotzsh) Dapat Meningkatkan Berat Testis Mencit Model Diabetes Mellitus". Jurnal Penelitian Kesehatan "SUARA FORIKES" (Journal of Health Research "Forikes Voice") 11, n.º 3 (18 de mayo de 2020): 324. http://dx.doi.org/10.33846/sf11320.

Texto completo

Resumen

Background: In addition to the influence of diabetes on male reproduction lowers testosterone levels of FSH and LH, the second number of hormones is reduced will interfere with the process of spermatogenesis. If the spermatogenesis process is interrupted then the number of germ cells decreases, this will cause a decrease in the weight of the testes. Objective: To analyze the effect of extract grass administration to the weight of the testicles diabetes Mellitus mice between the treatment group and the control. Methods: The research used DM male mice which is divided into 5 groups each consisting of 6 mice. Day 1 till day 5 all STZ-induced groups. On the 11th day to the 45th day, the control group (K +) was given metformin 2mg/head/day. The control group (K-) was given CMC-Na 1%. Group P1, P2 and P3 was given Kebar grass with dose of 67, 5mg/day, 135mg/kg/day, and 270mg/kg/day and metformin 2mg/head/day. The 46th was done with the release and sampling of the right and left testicles. Testicular weighing used analytic scales 0.001gram. Results: Statistical tests showed that there was a discrepancy in the p-value = 0.000 (0.05) on testicular weight. Conclusion: Increased testicular weight model of diabetes mellitus that gets the grass extractions of Kebar. Keywords: Kebar grass extract; testicular weight; diabetes mellitus ABSTRAK Latar belakang: Pengaruh diabetes mellitus terhadap reproduksi pria menurunkan kadar testosterone yaitu FSH dan LH, jumlah ke dua hormone tersebut berkurang maka akan mengganggu roses spermatogenesis. Proses spermatogenesis terganggu maka jumlah sel germinal mengalami penurunan, hal ini akan menyababkan berat testis menurun. Tujuan: menganalisisi pengaruh pemberian ekstrak rumput kebar terhadap berat testis mencit model diabetes mellitus antara kelompok perlakuan dan kontrol. Metode: penelitian menggunakan mencit DM yang dibagi menjadi lima kelompok setiap kelompok terdiri dari 6 ekor mencit. Hari ke 1 sampai hari ke 5 semua kelompok diinduksi STZ. Hari ke 11 sampai hari ke 45 kelompok kontrol (K+) disonde metformin 2mg/ekor/hari. Kelompok kontrol (K-) disonde CMC Na 1%. Kelompok P1,P2 dan P3 disonde ekstrak rumput kebar dengan dosis, 67,5mg/kgBB/hari, 135mg/kgBB/hari, 270mg/kgBB/hari dan metformin 2mg/ekor/hari. Hari ke 46 dilakukan pembedahan dan pengambilan sampel testis kanan dan kiri dan Penimbangan berat testis mencit menggunakan timbangan analitik dengan skala 0,001 gram. Hasil: uji statistik menunjukkan terdapat perbedaan bermakna dengan nilai p= 0,000 (p<0,05) pada berat testis mencit. Kesimpulan: berat testis meningkat dibandingkan kelompok kontrol Kata kunci: ekstrak rumput kebar; berat testis; diabetes mellitus

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Holets, Lesya M., Anne Grissell, Sudhakar Jakkaray, Ramappa Chakrasali, Gunda Georg, Mary Zelinski y Joseph S. Tash. "Effect of H2-Gamendazole on Rapid HSF1 Expression and Interaction with Heat Shock Proteins in Rat Testis In Vivo and Primary Sertoli Cells." Biology of Reproduction 83, Suppl_1 (1 de noviembre de 2010): 531. http://dx.doi.org/10.1093/biolreprod/83.s1.531.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

MAGALHÃES, APARECIDA SILVA, CHARLES HENRIQUE XAVIER MORAIS MAGALHÃES, LEONARDO BARBOSA GODEFROID, GERALDO LÚCIO DE FARIA, MILTON SERGIO FERNANDES DE LIMA, JULIANE CRUZ y RODNEI BERTAZZOLI. "Effect of PWHT on Laser-Welded Duplex Stainless Steel". Welding Journal 99, n.º 7 (1 de julio de 2020): 185s—202s. http://dx.doi.org/10.29391/2020.99.018.

Texto completo

Resumen

The welded joints of duplex stainless steels (DSSs) have been widely used in petrochemical, nuclear, pulp, and paper industries. Welds require a good, superficial finishing and a combination of mechanical and corrosion properties in these types of high-quality, demanding applications. Even though laser welding promotes narrow weld beads and a small heat-affected zone, when it is applied to DSSs, it can produce dangerous microstructural discontinuities. In this context, the effects of subsequent heat treatments on the microstructure, corrosion resistance, microhardness, and tensile proper-ties of DSS laser-welded joints are investigated. In this study, samples of UNS S32304 DSS were submitted to two different conditions of laser welding. Subsequently, the plates submitted to the best welding condition were subjected to isothermal heat treatments at different temperatures (850°, 950°, 1050°, and 1150°C) for 10 min. Then they were microstructurally characterized. Phase fraction measurements and microhardness tests were performed. Based on the obtained results, postweld heat-treated samples at 1150°C, which is the best condition, were subjected to corrosion and tensile tests. It was possible to conclude the corrosion prop-erties of the welded joint were significantly improved after the heat treatment. However, the mechanical behavior was strongly influenced by the presence of volumetric discontinuities and intermetallic compounds, which considerably deteriorated the mechanical strength of the material.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Xavier, Guadalupe Carvalho, Pierre Castro Soares, Valdemiro Amaro da Silva Junior, Sandra Maria de Torres, Ana Cristina Marinho Maymone, Rosana Nogueira de Morais, Cristiane Scavuzzi Moura y Maria Madalena Pessoa Guerra. "Effect of Dietary Selenium and Vitamin E Supplementation on Testicular Morphology and Serum Testosterone Concentration in Goats Following Scrotal Insulation". Acta Scientiae Veterinariae 44, n.º 1 (19 de marzo de 2018): 8. http://dx.doi.org/10.22456/1679-9216.81171.

Texto completo

Resumen

Background: Heat directly applied to the testis has been providing information regarding the damage triggering mechanisms on spermatogenesis and possible treatments to prevent testicular changes. Testis submitted to heat-shock have inhibition of the local antioxidant defense mechanisms against lipid peroxidation and free radicals. Vitamin E and Selenium protect biological membranes against free radicals to prevent membrane lipid peroxidation. The current assay evaluated the effect of dietary supplementation with Selenium and Vitamin E on testicular parenchyma and testosterone levels of goats submitted to heat shock by scrotal insulation.Materials, Methods & Results: The effect of dietary selenium and vitamin E supplementation on testicular parameters and serum testosterone concentration was evaluated in goats subjected to scrotal insulation. The animals were randomly allocated into two groups (n = 6) to receive either a control diet (CO) or a diet supplemented with selenium and vitamin E (SE). The animals received supplementation for 120 days: 60 days prior to scrotal insulation, 18 days during scrotal insulation and 42 days after scrotal insulation. Orchiectomy was performed on three animals from each group, immediately after the end of scrotal insulation. The remaining animals were neutered at the end of the experimental period (120 days). Testicles were routinely processed and embedded in glycol methacrylate, stained with toluidine blue/1% sodium borate and evaluated qualitative and quantitatively. Serum testosterone concentrations were determined by enzyme immunoassay at the time of the orchiectomy. Scrotal circumference was greater (P < 0.05) in goats of the SE group (23.0 ± 1.00 cm) than those of the control group (20.0 ± 1.00 cm) at the end of the scrotal insulation period (Day 18). At the end of the experimental period (Day 42 post-scrotal insulation (PSI)), the seminiferous tubule diameter and seminiferous epithelium height were greater (P < 0.05) in the SE group than in control. Histological changes associated with testicular degeneration were detected after 18 days of scrotal insulation in the goats of the control group. The animals of SE group had some histological changes of seminiferous tubules but the majority of them had normal association of germ cells. Selenium and vitamin E supplementation did not seem to avoid testicular damage caused by scrotal insulation but accelerated testicular recovery after the removal of insulation. Testosterone serum levels were not changed in the animals submitted to scrotal insulation, with or without dietary supplementation with selenium and vitamin E.Discussion: In the current study, scrotal insulation for 18 days caused testicular degeneration in both groups. However, selenium and vitamin E supplementation were capable of maintaining the scrotal circumference on the 18th day of insulation in the SE group. Previous reports suggested that selenium and vitamin E could protect cell membranes against the harmful effects of reactive oxygen species. However, the histopathological changes and morphometric data observed in the both groups after 18 days of insulation demonstrated that supplementation with these antioxidants did not prevent the damage caused by heat stress. In turn, at 42 days after the removal of insulation, the tubular diameter and seminiferous epithelium height was greater in animals supplemented with selenium and vitamin E. In addition, the animals that received supplementation had most of seminiferous tubules with cell associations of the seminiferous epithelium cycle. Vitamin E and selenium may reduce testicle sensitivity to heat and thereby shorten the spermatogenesis recovery time by 10 to 20 days. Selenium plus vitamin E added to feed was unable to prevent the degeneration of the testicular parenchyma in these animals. Nonetheless, the supplementation with both antioxidants hastened the recovery of spermatogenesis after the thermal injury.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Atalay, Ozgur, Senem Kursun Bahadir y Fatma Kalaoglu. "An Analysis on the Moisture and Thermal Protective Performance of Firefighter Clothing Based on Different Layer Combinations and Effect of Washing on Heat Protection and Vapour Transfer Performance". Advances in Materials Science and Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/540394.

Texto completo

Resumen

Fabric assemblies for firefighting clothing have been tested for heat protection and comfort. The constituent materials and fabric structures have been specifically selected and tailored for firefighters’ clothing. In order to do this, four types of outer shell fabrics, four types of moisture barrier fabrics, and four types of heat barriers with different weights and material compositions were used to make a multilayered fabric assembly. Heat transfer (flame), heat transfer (radiant), and water vapour resistance tests were conducted according to the latest EN469 test standard which also recommends washing tests. These tests reveal that material content and material brand have considerable effect on the required performance levels of heat protection. In addition, while washing tests have improved water vapor transfer properties, they have a deteriorating effect on heat protection performance. Considering heat protection and moisture comfort properties, the optimal assemblies are thereby identified.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Fiorini, Celine, Xavier Decrouy, Norah Defamie, Dominique Segretain y Georges Pointis. "Opposite regulation of connexin33 and connexin43 by LPS and IL-1α in spermatogenesis". American Journal of Physiology-Cell Physiology 290, n.º 3 (marzo de 2006): C733—C740. http://dx.doi.org/10.1152/ajpcell.00106.2005.

Texto completo

Resumen

The gap junction proteins, connexins (Cxs), are present in the testis, and among them, Cx43 play an essential role in spermatogenesis. In the present study, we investigated the testicular expression and regulation of another Cx, Cx33, previously described as a negative regulator of gap junction communication. Cx33 mRNA was present in testis and undetectable in heart, liver, ovary, and uterus. In the mature testis, Cx33 was specifically immunolocalized in the basal compartment of the seminiferous tubules, whereas Cx43 was present in both seminiferous tubule and interstitial compartments. During stages IX and X of spermatogenesis, characterized by Sertoli cell phagocytosis of residual bodies, Cx43 was poorly expressed within seminiferous tubules, while Cx33 signal was strong. To evaluate the role of phagocytosis in the control of Cx33 and Cx43 expression, the effect of LPS was analyzed in the Sertoli cell line 42GPA9. We show herein that phagocytosis activation by LPS concomitantly stimulated Cx33 and inhibited Cx43 mRNA levels. These effects appear to have been mediated through IL-1α, because the exposure of Sertoli cells to the IL-1 receptor antagonist partly reversed these effects. IL-1α enhanced and reduced, respectively, the levels of Cx33 and Cx43 mRNA in a time- and dose-dependent manner. These data reveal that Cx33 and Cx43 genes are controlled differently within the testis and suggest that these two Cxs may exert opposite and complementary effects on spermatogenesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

van, Zelst SJ, JL Zupp, DL Hayman y BP Setchell. "X-Y chromosome dissociation in mice and rats exposed to increased testicular or environmental temperatures". Reproduction, Fertility and Development 7, n.º 5 (1995): 1117. http://dx.doi.org/10.1071/rd9951117.

Texto completo

Resumen

Heating the testes, scrota and tails of mice and rats by immersion in a water bath at 42 degrees C for 20 min caused an increased percentage of X-Y univalents in meiotic preparations made after 6 and 12 days respectively. It was also confirmed that exposing mice of a cool-adapted strain to an environment at 33 degrees C for 5 days resulted in an increase in the percentage of X-Y and autosomal univalents in meiotic preparations made after a recovery period of 2 days. Mice of a strain adapted to living at 33 degrees C also showed a higher rate of X-Y dissociation than control cool-adapted mice, but a lower frequency of autosomal univalents than cool-adapted mice exposed to the hot environment. The testes of the heat-adapted mice were even more sensitive than the testes of cool-adapted mice to the effects of local heating, as judged by the fall in testis weight 21 days afterwards.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Testis Effect of heat on"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros