We investigate the structure and mechanical properties of proposed graphene-like hexagonal thallium nitride monolayer (g-TlN) using first-principles calculations based on density-functional theory. Compared to graphen...We investigate the structure and mechanical properties of proposed graphene-like hexagonal thallium nitride monolayer (g-TlN) using first-principles calculations based on density-functional theory. Compared to graphene-like hexagonal boron nitride monolayer (g-BN), g-TlN is much softer, with 12% in-plane stiffness, 25%, 22%, and 20% ultimate strengths in armchair, zigzag, and biaxial strains respectively. However, g-TlN has a larger Poisson’s ratio, 0.69, about 3.1 times that of g-BN. It was found that the g-TlN also sustains much smaller strains before rupture. We obtained the second, third, fourth, and fifth order elastic constants for a rigorous continuum description of the elastic response of g-TlN. The second order elastic constants, including in-plane stiffness, are predicted to monotonically increase with pressure while the Poisson’s ratio monotonically decreases with increasing pressure.展开更多
文摘We investigate the structure and mechanical properties of proposed graphene-like hexagonal thallium nitride monolayer (g-TlN) using first-principles calculations based on density-functional theory. Compared to graphene-like hexagonal boron nitride monolayer (g-BN), g-TlN is much softer, with 12% in-plane stiffness, 25%, 22%, and 20% ultimate strengths in armchair, zigzag, and biaxial strains respectively. However, g-TlN has a larger Poisson’s ratio, 0.69, about 3.1 times that of g-BN. It was found that the g-TlN also sustains much smaller strains before rupture. We obtained the second, third, fourth, and fifth order elastic constants for a rigorous continuum description of the elastic response of g-TlN. The second order elastic constants, including in-plane stiffness, are predicted to monotonically increase with pressure while the Poisson’s ratio monotonically decreases with increasing pressure.
文摘目的观察糖络宁对糖尿病周围神经病变(diabetic peripheral neuropathy,DPN)大鼠坐骨神经内质网应激相关PERK-CHOP-Caspase-12通路的调节作用。方法选用8周龄雄性SD大鼠,除空白对照组外,采用高脂饲料致高血脂联合链脲佐菌素腹腔注射诱导高血糖致DPN大鼠模型。将高脂高糖大鼠随机分为模型对照组、阳性药(氧化三甲胺)对照组、糖络宁低剂量组和糖络宁高剂量组,连续给药12周。给药过程中,动态监测大鼠血糖、血脂,确保糖尿病造模成功。12周后采用免疫荧光法检测坐骨神经中葡萄糖调节蛋白(glucose regulatory protein 78k D,GRP78)、C/EBP同源蛋白(C/EBP-homologous protein,CHOP)、蛋白激酶样内质网激酶(PKR-like ER kinase,PERK)、caspase-12和caspase-3的表达。结果与空白对照组比较,模型对照组坐骨神经中GRP78、CHOP、PERK、Caspase-12和Caspase-3的表达均显著升高(P<0.01或P<0.05);与模型对照组比较,糖络宁低剂量组和高剂量组GRP78表达显著升高(P<0.01),CHOP、PERK、Caspase-12和Caspase-3表达明显降低(P<0.01或P<0.05)。结论糖络宁防治DPN的作用机制与调节坐骨神经中内质网应激相关的PERK-CHOP-Caspase-12通路相关蛋白表达而抑制细胞凋亡有关。
基金This research was supported by the National High Technology Research and Development Program of China(863 Program)(No.2002AA207002 and No.2001AA241024),and the Natural Science Foundation of Jiangsu Province(No.BK2003076).
