凹角区域双曲外问题的精确人工边界条件

研究一类凹角区域双曲型外问题的数值方法.先用Newmark方法对时间进行离散化,在每个时间步求解一个椭圆外问题.然后引入人工边界,并获得精确的人工边界条件.给出半离散化问题的变分问题,证明了变分问题的适定性,并给出了误差估计.最后给出数值例子,以示该方法的可行性与有效性.     

Molecular functions and therapeutic applications of exosomal noncoding RNAs in cancer

Cancer is one of the most difficult diseases in human society. Therefore, it is urgent for us to understand its pathogenesis and improve the cure rate. Exosomes are nanoscale membrane vesicles formed by a variety of cells through endocytosis. As a new means of intercellular information exchange, exosomes have attracted much attention. Noncoding RNAs exist in various cell compartments and participate in a variety of cellular reactions; in particular, they can be detected in exosomes bound to lipoproteins and free circulating molecules. Increasing evidence has suggested the potential roles of exosomal noncoding RNAs in the progression of tumors. Herein, we present a comprehensive update on the biological functions of exosomal noncoding RNAs in the development of cancer. Specifically, we mainly focus on the effects of exosomal noncoding RNAs, including microRNAs, circular RNAs, long noncoding RNAs, small nuclear RNAs, and small nucleolar RNAs, on tumor growth, metastasis, angiogenesis, and chemoresistance. Moreover, we outline the current clinical implications concerning exosomal noncoding RNAs in cancer treatment.Subject terms: Cancer, Non-coding RNAs     

Tl系超导薄膜金属涂层的生长与特性研究

我们研究了Tl-2212超导薄膜在带有YSZ/CeO2缓冲层和带有CeO2/YSZ/CeO2缓冲层的Ni金属RABiTS基带上的生长情况.基带上的缓冲层是采用PLD方法制备的,Tl-2212薄膜的制备采用了磁控溅射和后热处理两步方法.XRD 实验结果表明,Tl-2212薄膜都具有很好的C轴垂直于膜面的织构,并具有双向外延生长特性.在CeO2/YSZ/CeO2/Ni基带上制作的Tl-2212薄膜的Tc达到102.8 K,Jc(77 K,0 T)达到2.6 MA/cm2;在YSZ/CeO2/Ni基带上薄膜Tc可达97.7 K,Jc(77 K,0 T)也可以达到0.45 MA/cm2.     

单级G-M 150制冷机性能实验研究

为满足高温超导和低温气体处理系统等工程应用项目的大冷量需求,单级大冷量G-M制冷机成为目前国内外的研究热点。文章中描述了以G-M150为基础的制冷机综合性能测试方法及实验平台,并对其制冷温度和制冷量两个主要性能的影响因素进行实验研究,为探讨20K单级大冷量G-M制冷机的研究提供参考。     

二维导电金属有机骨架材料

金属有机骨架(MOFs)是由金属离子或簇与有机配体以配位键组装而成的晶态多孔材料,其高的孔隙率及功能可设计性使其广泛应用于各种领域.然而,传统MOFs多数电导率非常低,这严重制约了其在电学相关领域的发展.近年来,导电金属有机骨架尤其是二维导电金属有机骨架(2D ECMOFs)材料因其结构中独特的π-π堆积及π-d共轭作...     

两共轴带电圆环的相互作用能和作用力

计算了两共轴均匀带电圆环的相互作用能,并求出它们之间的相互作用力,绘制出电场力的空间分布图,进而讨论了作用力和两圆环半径和中心距离等参量的关系.     

板栗内皮对水溶液中镉离子和铅离子的吸附

研究了板栗内皮对水溶液中金属离子(Cd2+,Pb2+)的吸附过程,以及吸附过程中不同条件对其吸附能力的影响.通过对反应时间、温度、pH、初始金属离子浓度等因素的控制,设计不同单一变量确定在不同条件下的吸附能力,利用红外光谱确定板栗内皮上参与反应的主要基团.结果表明,板栗内皮吸附Cd2+,Pb2+理论最佳吸附条件分别为p...     

中华黄萤荧光素酶的性质

近年来,萤火虫荧光素酶催化的生物发光反应被广泛的应用到ATP检测、细菌数目检测、环境监测和其他生物学研究之中。通过对中华黄萤荧光素酶的性质研究,发现其分子量为6 400左右,是一种非典型的Michaelis-Menten氏酶,对底物之一的ATP动力学曲线为S型。最适反应温度为20～25℃,对温度极其敏感,当反应温度高于30℃时,该酶的活性快速失活。该荧光素酶的最适pH=6.5。随着pH值的下降该荧光素酶生物发光的最大发射光波长没有明显的红移现象。Mg²⁺和Mn²⁺对该酶活性的激活效果比较接近,最佳的激活浓度均在1mmol/L附近,而Ca²⁺最佳的激活浓度则小于1 mmol/L,且激活的效果只有Mg²⁺作用效果的50%左右。和Hg²⁺、Cd²⁺等离子一样,Cu²⁺会在一定程度上抑制该荧光素酶的活性。该酶的稳定性较差,对盐浓度和光照比较敏感,高浓度的盐类和长时间的日光照射能够使酶失活。谷胱甘肽(GSH)和二硫苏糖醇(DTT)是该酶较好的保护剂,可以提高该酶在一定时间内的稳定性,其中前者的作用效果要好于后者。     

量子点中磁激子的极化子效应

采用推广的LLP方法研究了自组织量子点中磁激子的极化子效应。考虑带电粒子和声子的相互作用,得到了激子能量随磁场的变化关系。结果表明,激子-声子的相互作用降低了激子的能量,但影响很小;极化子效应在没有外磁场时较明显,随着外磁场的增加,这种效应变得越来越弱。     

Interactions between Human Serum Albumin and Sulfadimethoxine Determined Using Spectroscopy and Molecular Docking

Sulfonamides are widely used antibiotics in agricultural production. However, the potential threat of these drugs to human health has increased global concern. Human serum albumin (HSA) is the main reservoir and transporter of exogenous small molecules in humans. In this study, the interaction between sulfadimethoxine (SMT) and human serum albumin (HSA) was studied using spectroscopy and computer simulation. Our results showed that the hydrogen bonding and van der Waals forces drove SMT to enter the binding site I of HSA spontaneously and resulted in the fluorescence quenching of HSA. The stability of the HSA–SMT complex decreased with an increase in temperature. The binding of SMT to HSA induced alterations in the secondary structure of HSA, where the content of α-helix decreased from 61.0% of the free state to 59.0% of the compound state. The π–π, π–σ, and π–alkyl interactions between HSA and SMT were found to play important roles in maintaining the stability of the complex.