stress damage
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Author(s):  
Xinyue Wang ◽  
Zejun Zeng ◽  
Guoqi Q. Zhang ◽  
Jing Zhang ◽  
Pan Liu

Abstract Recent years, the sintered silver paste was introduced and further developed for power electronics packaging due to low processing temperature and high working temperature. The pressure-less sintering technology reduces the stress damage caused by the pressure to the chip, improves reliability, and is widely applied in manufacturing. Currently, most existed studies are focused on alcohol-based sintered silver pastes while resins have been demonstrated to improve the bonding properties of solder joints. Hence, the performance and sintering mechanisms with epoxy-based silver paste need to be further explored. In this work, a methodology for multi-factor investigation is settled on the epoxy-based silver paste to reveal the relationship between the strength and the different influence factors. We firstly analyzed the characteristics of commercialized epoxy-based silver paste samples, including silver content, silver particle size, organic paste composition, sample viscosity, and thermal conductivity. Samples were then prepared for shear tests and microstructure analysis under different pressure-less sintering temperatures, holding time, substrate surface, and chip size. Full factor analysis results were further discussed in detail for correlation. The influence factors were ranked from strong to weak as follows: sintering temperature, substrate surface, chip size, and holding time. Finally, a thermal cycling test was carried out for reliability analysis. Epoxy residues are one of the possible reasons which result in shear strength decreasing exponentially.


Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 151
Author(s):  
Jin Wang ◽  
Jia-Qiang Hu ◽  
Yu-Jie Song ◽  
Jia Yin ◽  
Yuan-Yi-Fei Wang ◽  
...  

The imbalance of reactive oxygen species is the main cause in aging, accompanied by oxidative stress. As the most abundant in human milk oligosaccharides (HMOs), 2′-Fucosyllactose (2′-FL) has been confirmed to have great properties in immunity regulation and anti-inflammatory. The research on 2′-FL is focused on infants currently, while there is no related report of 2′-FL for the elderly. A d-galactose-induced accelerated aging model was established to explore the protective effect of 2′-FL on the intestines and brain in mice. In this study, 2′-FL significantly reduced oxidative stress damage and inflammation in the intestines of aging mice, potentially by regulating the sirtuin1 (SIRT1)-related and nuclear factor E2-related factor 2 (Nrf2) pathways. In addition, 2′-FL significantly improved the gut mucosal barrier function and increased the content of short-chain fatty acids (SCFAs) in the intestine. The gut microbiota analysis indicated that 2′-FL mainly increased the abundance of probiotics like Akkermansia in aging mice. Moreover, 2′-FL significantly inhibited apoptosis in the brains of aging mice, also increasing the expression of SIRT1. These findings provided a basis for learning the benefits of 2′-FL in the aging process.


2022 ◽  
Author(s):  
Tao Wang ◽  
Fei Zhang ◽  
Wuxun Peng ◽  
Lei Wang ◽  
Jian Zhang ◽  
...  

Oxidative stress damage is a common problem in bone marrow mesenchymal stem cell (BMSC) transplantation. Under stress conditions, the mitochondrial function of BMSCs is disrupted, which accelerates senescence and apoptosis of BMSCs, ultimately leading to poor efficacy. Therefore, improving mitochondrial function and enhancing the anti-oxidative stress capacity of BMSCs may be an effective way of improving the survival rate and curative effect of BMSCs. In this study, we have confirmed that overexpression of nicotinamide mononucleotide adenylyl transferase 3 (NMNAT3) improves mitochondrial function and resistance to stress-induced apoptosis in BMSCs. We further revealed the mechanism of NMNAT3-mediated resistance to stress-induced apoptosis in BMSCs. We increased the level of nicotinamide adenine dinucleotide (NAD+) by overexpressing NMNAT3 in BMSCs and found that it could significantly increase the activity of silent mating type information regulation 2 homolog 3 (Sirt3) and significantly decrease the acetylation levels of Sirt3-dependent deacetylation-related proteins isocitrate dehydrogenase 2 (Idh2) and Forkhead-box protein O3a (FOXO3a). These findings show that NMNAT3 may increase the activity of Sirt3 by increasing NAD+ levels. Our results confirm that the NMNAT3-NAD+-Sirt3 axis is a potential mechanism for improving mitochondrial function and enhancing anti-oxidative stress of BMSCs. In this study, we take advantage of the role of NMNAT3 in inhibiting stress-induced apoptosis of BMSCs and provide new methods and ideas for breaking through the bottleneck of transplantation efficacy of BMSCs in the clinic.


Author(s):  
Ata Rafiee ◽  
Juana Maria Delgado-Saborit ◽  
Peter D. Sly ◽  
Hoda Amiri ◽  
Shamim Mosalaei ◽  
...  

Antioxidants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 65
Author(s):  
Zhi-Yuan Chen ◽  
Hui-Wen Xiao ◽  
Jia-Li Dong ◽  
Yuan Li ◽  
Bin Wang ◽  
...  

Radiation pneumonia is a common and intractable side effect associated with radiotherapy for chest cancer and involves oxidative stress damage and inflammation, prematurely halting the remedy and reducing the life quality of patients. However, the therapeutic options for the complication have yielded disappointing results in clinical application. Here, we report an effective avenue for fighting against radiation pneumonia. Faecal microbiota transplantation (FMT) reduced radiation pneumonia, scavenged oxidative stress and improved lung function in mouse models. Local chest irradiation shifted the gut bacterial taxonomic proportions, which were preserved by FMT. The level of gut microbiota-derived PGF2α decreased following irradiation but increased after FMT. Experimental mice with PGF2α replenishment, via an oral route, exhibited accumulated PGF2α in faecal pellets, peripheral blood and lung tissues, resulting in the attenuation of inflammatory status of the lung and amelioration of lung respiratory function following local chest irradiation. PGF2α activated the FP/MAPK/NF-κB axis to promote cell proliferation and inhibit apoptosis with radiation challenge; silencing MAPK attenuated the protective effect of PGF2α on radiation-challenged lung cells. Together, our findings pave the way for the clinical treatment of radiotherapy-associated complications and underpin PGF2α as a gut microbiota-produced metabolite.


2021 ◽  
Vol 14 (4) ◽  
pp. 1486-1492
Author(s):  
Anthony T. Eduviere

Although the implication of calcium signalling in the aetiology of anxiety remains elusive, drugs modulating calcium (like calcium channel blockers) have been discovered to be some worth beneficial as treatment option for anxiety related disorders. This study was therefore undertaken to assess probable ameliorative potential of verapamil against manic-like (stereotype behaviour) and anxiety-like symptoms in mice exposed to sleep deprivation. Mice were allotted into five treatment groups (n=5): group 1 and 2 received 10 mL/kg distilled water, groups 3 and 4 verapamil (25 and 50 mg/kg) while group 5 received astaxanthin (50 mg/kg) which served as the reference drug. Treatment was for 7 days and animals were sleep-deprived on the final 72 hours. Various behavioural tests to determine degree of stereotypical behaviour and locomotor activity were carried out. Anxiety test was done via the aid of a light/dark box and plus maze while stereotype behaviour was assess utilizing an open field box. Oxidative stress parameters; malondialdehyde and glutathione were assessed. Histopathological perturbations in the caudate putamen were also recorded. Data were subjected to ANOVA at α0.05. The results obtained suggest that verapamil significantly suppressed stereotyped behaviour and reduced the incidence of manic-like behaviour which was induced by paradoxical sleep deprivation. Verapamil also significantly restored antioxidant levels and protected against loss of caudate neurons. In conclusion, verapamil ameliorates manic-like symptoms and anxiety in mice derived of sleep, while protecting brain neurons against oxidative stress damage induced by sleep deprivation.


Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1996
Author(s):  
Kun Yang ◽  
Qiaowei Li ◽  
Guocai Zhang ◽  
Chao Ma ◽  
Xianjun Dai

Carrageenan oligosaccharides (COS) have been reported to possess excellent antioxidant activities, but the underlying mechanism remains poorly understood. In this study, H2O2 was applied to trigger oxidative stress. The results showed that the addition of COS could effectively extend the lifespan of female Drosophila, which was associated with improvements by COS on the antioxidant defense system, including a decrease in MDA, the enhanced activities of SOD and CAT, the reduction of ROS in intestinal epithelial cells, and the up-regulation of antioxidant-relevant genes (GCL, GSTs, Nrf2, SOD). Meanwhile, the axenic female Drosophila fed with COS showed almost no improvement in the above measurements after H2O2 treatment, which highlighted the antioxidant mechanism of COS was closely related to intestinal microorganisms. Then, 16S rDNA high-throughput sequencing was applied and the result showed that the addition of COS in diets contributed to the diversity and abundance of intestinal flora in H2O2 induced female Drosophila. Moreover, COS significantly inhibited the expression of gene mTOR, elevated its downstream gene 4E-BP, and further inhibited autophagy-relevant genes (AMPKα, Atg1, Atg5, Atg8a) in H2O2 induced female Drosophila. The inhibition of the mTOR pathway and the activation of autophagy was probably mediated by the antioxidant effects of COS. These results provide potential evidence for further understanding of COS as an intestinal antioxidant.


2021 ◽  
Vol 11 (23) ◽  
pp. 11413
Author(s):  
Xinyong Xu ◽  
Wenjie Xu ◽  
Chenlong Xie ◽  
Mohd Yawar Ali Khan

The South-to-North Water Diversion Project has been in operation since 2014, directly benefiting more than 79 million people in China. Thus, its service life and long-term performance have gained much attention from scholars. To predict its life and performance, this study used the seepage/stress-damage coupling method. In addition, a seepage/stress-damage coupling theory was proposed and a finite element model of a deep excavated canal in the Xichuan Section of the South-to-North Water Diversion Project was established. The results showed that this canal subsided greatly in the first two years of operation, which can be confirmed by the monitoring data. It is predicted that, after 50 years of normal operation, the canal damage may start and spread from the water level, and reach 37.6%, but such damage will not affect its normal water delivery function. The purpose of this study is to provide guidance for the safe operation of the project.


2021 ◽  
Vol 144 ◽  
pp. 112351
Author(s):  
Mohamad Allaw ◽  
Maria Manconi ◽  
Pierluigi Caboni ◽  
Gianluigi Bacchetta ◽  
Elvira Escribano-Ferrer ◽  
...  

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