Influence of residual chirality on the conformation and enzymatic degradation of glycopolypeptide based biomaterials

Science China Technological Sciences - Glycopolypeptides as analogs of glycoproteins or glycosaminoglycans represent attractive building blocks for the construction of biomimetic biomaterials....     

ARGET ATRP合成大分子偶联剂PMMA-b-PTMSPMA及其对玻璃表面的接枝

以电子转移再生催化剂的原子转移自由基聚合(ARGET ATRP)成功合成了大分子硅烷偶联剂即聚甲基丙烯酸甲酯-b-3-甲基丙烯酰氧基丙基三甲氧基硅烷(PMMA-b-PTMSPMA)。利用所制得的大分子偶联剂对玻璃表面进行了接枝改性,对改性后的玻璃表面形态及疏水性能进行了研究。结果表明,以CuBr2/PMDETA络合物为催化体系,溴化铜(CuBr2)用量为n(CuBr2)/n(单体)=5×10-4时,PMMA段以辛酸亚锡(Sn(EH)2)为还原剂,PTMSPMA段以铜(Cu)为还原剂,用ARGET ATRP两步法成功制备了嵌段共聚物PMMA-b-PTMSPMA。采用"接枝到(graft onto)"方法,在温和的条件下,在玻璃表面接枝上了大分子偶联剂。玻璃表面的接触角可从30°提高到65°,提高了玻璃表面的疏水性。     

水稻基因组MSAP指纹图谱构建及DNA甲基化修饰位点分离与鉴定

采用EcoR I和Hpa II/Msp I双酶切建立了适合于水稻基因组的甲基化敏感扩增多态性(MSAP)分析体系,在全基因组水平检测了水稻DNA甲基化修饰位点.以12对MSAP引物进行选择性扩增,共检测到甲基化修饰位点120个,"CCGG/GGCC"位点甲基化修饰比例为20.17%.对部分水稻基因组甲基化修饰位点进行回收,最终分离了55条存在甲基化位点变异的DNA序列,通过BLAST比对分析将其联配到水稻基因组序列上.分析表明,这些甲基化修饰位点主要集中于基因启动子区(47%)和第一外显子区(22%),在其侧翼序列中存在类似"CpG island" 典型序列特征的"CpG"二核苷酸成簇富集区.在此基础上,对应用MSAP技术分离水稻基因组DNA甲基化修饰位点的有效性以及水稻基因组序列中"CpG island"类似序列分布特征和生物意义进行了讨论.     

高速高精度ADC系统研究

由于单个ADC模拟输入带宽的限制,混合滤波器组ADC系统不能够直接对高达数GHz的模拟信号进行采样.本文提出了基于混频器和低通滤波器的抽取器数学模型,并且从时域和频域进行详细的分析和证明.最后在混合滤波器组ADC系统的基础上,提出了基于混频器和低通滤波器的高速高精度混合滤波器组ADC系统,它完全满足软件无线电和雷达等多个领城的高速高精度要求.     

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.     

The E3 Ligase GmPUB21 Negatively Regulates Drought and Salinity Stress Response in Soybean

E3-ubiquitin ligases are known to confer abiotic stress responses in plants. In the present study, GmPUB21, a novel U-box E3-ubiquitin ligase-encoding gene, was isolated from soybean and functionally characterized. The expression of GmPUB21, which possesses E3-ubiquitin ligase activity, was found to be significantly up-regulated by drought, salinity, and ABA treatments. The fusion protein GmPUB21-GFP was localized in the cytoplasm, nucleus, and plasma membrane. Transgenic lines of the Nicotiana benthamiana over-expressing GmPUB21 showed more sensitive to osmotic, salinity stress and ABA in seed germination and inhibited mannitol/NaCl-mediated stomatal closure. Moreover, higher reactive oxygen species accumulation was observed in GmPUB21 overexpressing plants after drought and salinity treatment than in wild-type (WT) plants. Contrarily, silencing of GmPUB21 in soybean plants significantly enhanced the tolerance to drought and salinity stresses. Collectively, our results revealed that GmPUB21 negatively regulates the drought and salinity tolerance by increasing the stomatal density and aperture via the ABA signaling pathway. These findings improved our understanding of the role of GmPUB21 under drought and salinity stresses in soybean.     

Velocity and turbulence characteristics in an open channel with multi-row staggered vegetation patches

A staggered distribution of vegetation is very common in nature,which might significantly affect the flow structure.To investigate its impact,three rows of stag...     

浅析建立企业标准体系必须结合企业自身实际情况

目前，很多企业已经建立了GB／T19001、GB／T28001、GB／T24001管理体系，为了在更大的范围和更深的层次上提高企业的管理水平，一些企业还在寻求更多管理体系的认证或确认，还有些企业在寻求不同管理体系的整合和提高，按照GB／T15496、GB／T15497、GB／T15498和GB／T19273的2003版标准建立的企业标准体系也是规范企业所有的管理工作的有效手段。对于有管理经验积累的企业而言，管理体系的运行在一定时期后，企业标准化水平会得到一定提高。但是，如何不断提高运行的有效性与更好地协调各管理体系的兼容性，是摆在我们面前的一个新课题。笔者结合本公司建立企业标准体系的实践经验，阐述了建立企业标准体系，实现企业管理水平持续改进必须要结合企业自身实际情况。