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991.
Self-healing property of epoxy/nanoclay nanocomposite using poly(ethylene-co-methacrylic acid) agent
This paper investigates the self-healing repair of cracks in an epoxy/nanoclay nanocomposite using mendable poly[ethylene-co-methacrylic acid] (EMAA) particles. The effects of two different concentrations of EMAA agent on the self-healing efficiency were measured using single edge notch bar (SENB) testing. Inclusion of EMAA particles into the nanocomposite results an increase in the fracture strength and strain of the SENB specimens. Damaged SENBs were healed at 150 °C for 30 min to achieve up to 63% recovery in critical stress intensity and over 85% recovery in sustainable peak load. Also, X-ray diffraction (XRD) analysis and tensile test used in order to examine the nanocomposite structure and investigate the effects of EMAA inclusion on the nanocomposite mechanical properties. The pressure delivery mechanism of the healing agent is shown by scanning electron microscopy (SEM) images. It seems EMAA can be used as an effective self-healing agent for epoxy/nanoclay nanocomposites. 相似文献
992.
Aisha Khatoon Muhammad Zargham Khan Zain ul Abidin Sheraz Ahmed Bhatti 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(3):538-545
A presence of mycotoxins in feed is one of the most alarming issues in the poultry feed industry. Ochratoxins, produced by several Aspergillus and Penicillium species, are important mycotoxin regarding the health status of poultry birds. Ochratoxins are further classified into to several subtypes (A, B, C, etc) depending on their chemical structures, but ochratoxin A (OTA) is considered the most important and toxic. Bentonite clay, belonging to phyllosilicates and formed from weathering of volcanic ashes, has adsorbent ability for several mycotoxins. The present study was designed to study the effects of bentonite clay upon OTA-induced immunosuppression in broiler chicks. For this, 480 day-old broiler chicks were procured from a local hatchery and then different combinations of OTA (0.15, 0.3, or 1.0 mg/kg) and bentonite clay (5, 10, and 20 g/kg) were incorporated into their feed. At 13, 30, and 42 days of age, parameters such as antibody responses to sheep red blood cells, in situ lymphoproliferative responses to mitogen (PHA-P), and in situ phagocytic activity (i.e., via carbon clearance) were determined respectively. The results indicated there was a significant reduction of total antibody and immunoglobulin titres, lymphoproliferative responses, and phagocytic potential in OTA-treated birds, suggesting clear immunosuppression by OTA in birds in a dose-dependent manner. These results were also significantly lower in all combination groups (OTA with bentonite clay), suggesting few to no effects of feeding bentonite clay upon OTA- induced alterations in different immune parameters. 相似文献
993.
Rajiv K. Bedi Dr. Danzhi Huang Stefanie A. Eberle Dr. Lars Wiedmer Dr. Pawel Śledź Prof. Amedeo Caflisch 《ChemMedChem》2020,15(9):744-748
The RNA methylase METTL3 catalyzes the transfer of a methyl group from the cofactor S-adenosyl-L-methionine (SAM) to the N6 atom of adenine. We have screened a library of 4000 analogues and derivatives of the adenosine moiety of SAM by high-throughput docking into METTL3. Two series of adenine derivatives were identified in silico, and the binding mode of six of the predicted inhibitors was validated by protein crystallography. Two compounds, one for each series, show good ligand efficiency. We propose a route for their further development into potent and selective inhibitors of METTL3. 相似文献
994.
本文以630 ℃汽轮机紧固件备选合金GH4080A合金为研究对象,对美国Special Metals和抚顺特钢冶炼的材料经过标准热处理后分别在不同载荷下进行高温缺口持久实验,并结合光学显微镜(OM)和扫描电镜(SEM)及背散射电子衍射(EBSD)分析,研究合金持久寿命的分散性与持久样品断口附近组织的关联性。结果表明:GH4080A抚钢边缘和芯部持久寿命不同的主要原因是两者晶粒大小不同;抚钢边缘与SMC边缘持久寿命不同的主要原因是两者变形机制不同,前者为晶界滑移,后者为晶内变形与晶界变形协调作用。 相似文献
995.
The dispersion stabilities of three titania (TiO2) nanopowders with different particle sizes and surface chemistries in aqueous suspensions containing a common water-based dispersant, ammonium polyacrylate (PAA-NH4), have been investigated and compared. According to adsorption isotherm and Fourier transform infrared spectroscopy analyses, the adsorption conformations of PAA-NH4 are distinct for the different TiO2 nanopowders. In addition, PAA-NH4 exhibited the greatest adsorption affinity to the larger, hydrophilic TiO2 nanopowder and the least affinity to smaller, hydrophobic nanopowder. From sedimentation and rheological results, the dispersion stability of the larger, hydrophilic TiO2 nanopowder was demonstrated to be the greatest. Based on thermodynamic and kinetic calculations for the stabilization energies, the larger, hydrophilic TiO2 nanopowder was also shown to be the best-stabilized powder, although it settles faster than the smaller, hydrophilic TiO2 nanopowder; this is due to the greater affection of sedimentation flux on the larger nanopowder. In contrast, the hydrophobic TiO2 nanopowder formed a gel-like structure in the aqueous suspension when the solid content was greater than 10 wt%, which is attributed to polymer bridging between PAA-NH4-adsorbed TiO2 nanoparticles. 相似文献
996.
Polash Chandra Karmakar Jin Seop Ahn Yong-Hee Kim Sang-Eun Jung Bang-Jin Kim Hee-Seok Lee Buom-Yong Ryu 《International journal of molecular sciences》2020,21(22)
Exposure to bisphenol A (BPA) in the gestational period damages the reproductive health of offspring; detailed evidence regarding BPA-induced damage in testicular germ cells of offspring is still limited. In this study, pregnant mice (F0) were gavaged with three BPA doses (50 μg, 5 mg, and 50 mg/kg body weight (bw)/day; tolerable daily intake (TDI), no-observed-adverse-effect-level (NOAEL), and lowest-observed-adverse-effect level (LOAEL), respectively) on embryonic days 7 to 14, followed by investigation of the transgenerational effects of such exposure in male offspring. We observed that the NOAEL- and LOAEL-exposed F1 offspring had abnormalities in anogenital distance, nipple retention, and pubertal onset (days), together with differences in seminiferous epithelial stages and testis morphology. These effects were eradicated in the next F2 and F3 generations. Moreover, there was an alteration in the ratio of germ cell population and the apoptosis rate in germ cells increased in F1 offspring at the LOAEL dose. However, the total number of spermatogonia remained unchanged. Finally, a reduction in the stemness properties of spermatogonial stem cells in F1 offspring was observed upon LOAEL exposure. Therefore, we provide evidence of BPA-induced disruption of physiology and functions in male germ cells during the gestational period. This may lead to several reproductive health issues and infertility in offspring. 相似文献
997.
This paper addresses the effective use of carbon fiber reinforced polymeric (CFRP) materials in the cable system. As the span length of cable-stayed bridges increases, several technical challenges become more dominant with traditional material. This paper mainly focuses on improving the aerodynamic performance through implementing CFRP composites in the cable system in combination with steel. In order to maximize the improvement, a genetic algorithm (GA)-based optimization procedure is developed to optimize the distribution of CFRP and steel. A numerical example is presented and the results suggest the typical composition of an optimized CFRP-steel cable system for long-span cable-stayed bridges. 相似文献
998.
Based on nonlocal theory, this article discusses vibration of CDVGS1 systems. The properties of each single layer graphene sheet (SLGS) are assumed to be orthotropic and viscoelastic. The two SLGSs are simply supported and coupled by an enclosing viscoelastic medium which is simulated as a Visco-Pasternak layer. This model is aimed at representing dynamic interactions in nanocomposite materials with dissipation effect. By considering the Kirchhoff plate theory and Kelvin–Voigt model, the governing equation is derived using Hamilton's principle. The equation is solved analytically to obtain the complex natural frequency. The parametric study is thoroughly performed, concentrating on the series effects of viscoelastic damping structure, aspect ratio, visco-Pasternak medium, and mode number. In this system, in-phase (IPV) and out-of-phase (OPV) vibrations are investigated. The numerical results of this article show a perfect correspondence with those of the previous researches. 相似文献
999.
A study on the temperature-dependent viscoelastic behavior of (1–3 active composites) 1–3 piezocomposites and bulk piezoceramic subjected to electromechanical loading is carried out. The temperature-dependent effective properties are obtained experimentally using resonance based measurement technique. Experiments are also preformed for various fiber volume fractions of 1–3 piezocomposites subjected to constant compressive prestress and cyclic electric field at elevated temperature to understand the time-dependent behavior. Based on the measurements it is observed that the viscoelastic behavior has a significant influence on the electromechanical responses of 1–3 piezocomposites. Hence a viscoelastic based numerical model (unit cell approach) is proposed to predict the time-dependent effective properties of 1–3 piezocomposites. The evaluated effective properties are incorporated in a finite element based 3-D micromechanical model to predict the time-dependent thermo-electro-mechanical behavior of 1–3 piezocomposites and compared with the experimental observations. 相似文献
1000.
Nguyen T. H. Hanh Bui T. Nhung Le T. Hop Le T. Tuyet Duong T. A. Dao Nguyen T. T. Thu Tran Quang Binh 《Lipids》2020,55(6):683-691
Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case–control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits. 相似文献