Cell membrane-covered nanoparticles as biomaterials

Surface engineering of synthetic carriers is an essential and important strategy for drug delivery in vivo. However, exogenous properties make synthetic nanosystems invaders that easily trigger the passive immune clearance mechanism, increasing the retention effect caused by the reticuloendothelial systems and bioadhesion, finally leading to low therapeutic efficacy and toxic effects. Recently, a cell membrane cloaking technique has been reported as a novel interfacing approach from the biological/immunological perspective, and has proved useful for improving the performance of synthetic nanocarriers in vivo. After cell membrane cloaking, nanoparticles not only acquire the physiochemical properties of natural cell membranes but also inherit unique biological functions due to the presence of membrane-anchored proteins, antigens, and immunological moieties. The derived biological properties and functions, such as immunosuppressive capability, long circulation time, and targeted recognition integrated in synthetic nanosystems, have enhanced their potential in biomedicine in the future. Here, we review the cell membrane-covered nanosystems, highlight their novelty, introduce relevant biomedical applications, and describe the future prospects for the use of this novel biomimetic system constructed from a combination of cell membranes and synthetic nanomaterials.     

Surface superconductivity in the type II Weyl semimetal TaIrTe4

The search for unconventional superconductivity in Weyl semimetal materials is currently an exciting pursuit, since such superconducting phases could potentially be topologically non-trivial and host exotic Majorana modes. The layered material TaIrTe₄ is a newly predicted time-reversal invariant type II Weyl semimetal with the minimum number of Weyl points. Here, we report the discovery of surface superconductivity in Weyl semimetal TaIrTe₄. Our scanning tunneling microscopy/spectroscopy (STM/STS) visualizes Fermi arc surface states of TaIrTe₄ that are consistent with the previous angle-resolved photoemission spectroscopy results. By a systematic study based on STS at ultralow temperature, we observe uniform superconducting gaps on the sample surface. The superconductivity is further confirmed by electrical transport measurements at ultralow temperature, with an onset transition temperature (T_c) up to 1.54 K being observed. The normalized upper critical field h*(T/T_c) behavior and the stability of the superconductivity against the ferromagnet indicate that the discovered superconductivity is unconventional with the p-wave pairing. The systematic STS, and thickness- and angular-dependent transport measurements reveal that the detected superconductivity is quasi-1D and occurs in the surface states. The discovery of the surface superconductivity in TaIrTe₄ provides a new novel platform to explore topological superconductivity and Majorana modes.     

基于GOCI影像的杭州PM2.5遥感建模及时空变异分析

地球静止卫星上的GOCI(geostationary ocean color imager)传感器具有较高的时间分辨率,在研究短时间尺度内大气PM2.5浓度时空变化方面具有一定的应用潜力.本文根据GOCI影像的波段特征,利用2011-2013年实测PM2.5浓度、大气气溶胶光学厚度(aerosol optical depth,AOD)与气象因子数据,分别进行了GOCI PM2.5浓度单变量和多变量反演建模研究,并结合2013年12月6日的GOCI AOD数据,实现了单日杭州市PM25浓度遥感反演与时空变异分析.结果表明:在单变量模型中,分季节模型的平均相对误差最高值28.11％比年度模型的平均相对误差34.04％低,分季节模型精度优于年度模型;单变量模型的平均相对误差34.04％比多变量模型的平均相对误差48.96％低,单变量模型精度优于多变量模型;把单变量冬季模型应用于杭州GOCI AOD数据,得出逐时大气PM2.5的空间分布,并计算了PM2.5浓度的变异系数,发现杭州各区县变异系数大都在0.5以下,东部和北部的数值较高,中西部地区的值较低.     

Transgenic barley with overexpressed PTrx increases aluminum resistance in roots during germination

A transgenic barley line (LSY-11-1-1) with overexpressed Phalaris coerulescens thioredoxin gene (PTrx) was employed to measure the growth, protein oxidation, cell viability, and antioxidase activity in barley roots during germination on the presence of 2 mmol/L AlCl₃ on filter paper. The results show that (1) compared with the non-transgenic barley, LSY-11-1-1 had enhanced root growth, although both were seriously inhibited after AlCl₃ treatment; (2) the degree of protein oxidation and loss of cell viability in roots of LSY-11-1-1 were much less than those in roots of non-transgenic barley, as reflected by lower contents of protein carbonyl and Evans blue uptakes in LSY-11-1-1; (3) activities of catalase (CAT), glutathione peroxidase (GPX), ascorbate peroxidase (APX), and glutathione reductase (GR) in LSY-11-1-1 root tips were generally higher than those in non-transgenic barley root tips, although these antioxidase activities gave a rise to different degrees in both LSY-11-1-1 and non-transgenic barley under aluminum stress. These results indicate that overexpressing PTrx could efficiently protect barley roots from oxidative injury by increasing antioxidase activity, thereby quenching ROS caused by AlCl₃ during germination. These properties raise the possibility that transgenic barley with overexpressed PTrx may be used to reduce the aluminum toxicity in acid soils.     

Electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter system

This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10–10⁷ Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system.     

大学英语写作教学中的若干问题及对策分析

随着我国经济的发展,对外交流越来越多,社会经济的发展对于英语人才的需求越来越急迫。大学是英语人才培养的重要基地,大学英语专业的教育教学活动质量对于当代英语人才的英语语言能力有着重要影响。英语写作是英语教学的重要组成内容,利用英语写作教学,可以对大学生的英语语言理解能力与英语表达能力进行有效促进与提高。但是,目前的大学英语写作教学并没有达到学生与社会的期望,还存在一些问题影响着其教学成效的提高。加强大学英语写作教学问题的发现与解决已经成为当代大学英语教师的重要研究课题。因此,本文以大学英语写作教学中的若干问题及对策分析为题,对大学英语写作教学中的问题进行分析,提出切实可行的加强对策。     

学术期刊编辑思维定式的误区

当代一些学术期刊编辑受传统思维模式的影响和制约,形成了重整体、重综合、崇尚圣贤经典的价值取向,使办刊过程中产生了许多误区,刊物平庸无奇,缺少个性与生机.认为期刊要发展、要同世界接轨,必须调整和革新编辑的思维模式与价值取向.     

书目著作的历史沿革与当前应变——喜见2006年《中国图书年鉴》出版有感

本文在回溯我国书目著作历史沿革的基础上,对2006年卷《中国图书年鉴》主体部分的"年度重点书简介"栏目进行了分析,认为该栏目是适应时代需求的新型书目,在全面集中展示各年度图书出版精华,深度报道反映科学技术研究和文化艺术创作成果,为科研、教学和历史提供系统资料方面,发挥着重要作用.     

�������еġ���ͼ������˼��

分析《中国科学院图书馆图书分类法》（简称《科图法》）处于窘境的原因,呼吁加强对《科图法》的研究,并建议在文献工作中实行《科图法》和《中国图书馆图书分类法》（简称《中图法》）两法并用。     

对中学语文审美教学的几点思考

在中学语文教学中进行审美教育,不但有利于提高语文教学的质量和效率,深化语文教育的效果,促进学生学习语文的主动性和积极性,同时还有利于培养学生的审美想像力。于是,探索语文审美教学便成为中学语文教学改革的一个重要课题。一、语文教学与审美教育的关系在语文教学中实现美育,是语文教学应有之义。一方面,语文教学内容所具有的审美属性,决定了语文教学与美育有着必然的联系。即二者相互依存、互为条件,语文教学的过程必须贯穿美育,美育通过语文教学得以实现。现行的中学语文教材,80%的课文是中外文学名作佳篇。文学作品中优美的语言,不…