检索结果-南通市图书馆

Experimental Study on molecular arrangement of Nanoscale Lubricant Films——A Review

Chinese Journal of Mechanical Engineering 2015年第5期28卷 896-903页

作者： ZHANG Shaohua LIU Yuhong State Key Laboratory of Tribology Tsinghua University

In order to understand lubrication mechanism at the nanoscale, researchers have used many physical experimental approaches, such as surface force apparatus, atomic force microscopy and ball-on-disk tribometer. The results show that the variation rules of the friction force, film thicknessand viscosity of the lubricant at the nanoscale are different from elastohydrodynamic lubrication （EHL）. It is speculated that these differences are attributed to the special arrangement of the molecules at the nanoscale. However, it is difficult to obtain the molecular orientation and distribution directly from the lubricant molecules in these experiments. In recent years, more and more attention has been paid to use new techniques to overcome the shortcomings of traditional experiments, including various spectral methods. The most representative achievements in the experimental research of molecular arrangement are reviewed in this paper： The change of film structure of a liquid crystal under confinement has been obtained using X-ray method. The molecular orientation change of lubricant films has been observed using absorption spectroscopy. Infrared spectroscopy has been used to measure the anisotropy of molecular orientation in the contact region when the lubricant film thickness is reduced to a few tens of nanometers. In situ Raman spectroscopy has been performed to measure the molecular orientation of the lubricant film semi-quantitatively. These results prove that confinement and shear in the contact region can change the arrangement of lubricant molecules. As a result, the lubrication characteristics are affected. The shortages of these works are also discussed based on practicable results. Further work is needed to separate the information of the solid-liquid interface from the bulk liquid film.

关键词： nano-scale lubricating film in situ measurement molecular arrangement

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Liquid crystal-based optical aptasensor for the sensitive and selective detection of Gram-negative bacteria

引用

Science China Chemistry 2022年第10期65卷 2023-2030页

作者： Mengjun Liu Minmin Zhang Jiamei Chen Ruizhi Yang Zhaofan Huang Zhenping Liu Na Li Lingling Shui Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices School of Information and Optoelectronic Science and EngineeringSouth China Normal UniversityGuangzhou 510006China Joint Laboratory of Optofluidic Technology and Systems National Center for International Research on Green OptoelectronicsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou 510006China

The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.

关键词： liquid crystal molecular arrangement optical sensor aptamer Gram-negative bacteria

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Interfacial properties and micellization of triblock poly(ethylene glycol)-poly(ε-caprolactone)-polyethyleneimine copolymers

引用

Acta Pharmaceutica Sinica B 2020年第6期10卷 1122-1133页

作者： Ji Li Yitian Du Haitao Su Shixuan Cheng Yanxia Zhou Yiguang Jin Xian-Rong Qi Key Laboratory of molecular Pharmaceutics and New Drug Delivery System School of Pharmaceutical SciencesPeking UniversityBeijing 100191China Department of Pharmaceutical Sciences Beijing Institute of Radiation MedicineBeijing 100850China

This study aimed to explore the link between block copolymers’interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system.A library of diblock copolymers of PEG-PCL and triblock copolymers with additional PEI(PEG-PCL-PEI)were synthesized.Subsequently,a systematic isothermal investigation was performed to explore molecular arrangements of copolymers at air/water interface.Then,structural properties and drug encapsulation in self-assembly were investigated with DLS,SLS and TEM.We found the additional hydrogen bond in the PEG-PCL-PEI contributes to film stability upon the hydrophobic interaction compared with PEG-PCL.PEG-PCL-PEI assemble into smaller micelle-like(such as PEGPCL4006-PEI)or particle-like structure(such as PEG-PCL8636-PEI)determined by their hydrophilic and hydrophobic block ratio.The distinct structural architectures of copolymer are consistent between interface and self-assembly.Despite the disparity of constituent ratio,we discovered the arrangement of both chains guarantees balanced hydrophilic-hydrophobic ratio in self-assembly to form stable construction.Meanwhile,the structural differences were found to have significant influence on model drugs incorporation including docetaxel and siRNA.Taken together,these findings indicate the correlation between molecular arrangement and self-assembly and inspire us to tune block compositions to achieve desired nanostructure and drug loading.

关键词： Block copolymers Langmuir films molecular arrangement Self-assembly Nanostructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：