Science China-Chemistry
·
2016
·Vol. 59
·期 7
·824-829
·
IF 2.429
Zhao Jianwei,Sun Yinlu,Gao Yajun
The diffusion behavior of particles in the chromatography is a fundamental issue of chromatographic dynamics. The understanding of the diffusion behaviors is particularly critical to optimize the operation conditions, improve the chromatographic performance and design a new separation device. Many of the present simulations focus on chromatographic thermodynamics, and very few aim at the overall diffusion and separation process. In order to dynamically trace the trajectory of the diffusing particles and to perform simulations of the whole chromatographic process, we have developed a model based on the framework of random walk in the restricted space and performed the simulation of a single particle diffusion in the gas chromatography. The simulation parameters were determined by comparing with the experimental data. The elution profiles of n-alkanes under different flow rates were accurately simulated with the method. The results show that the relative difference between the measures and the simulations are less than 2% and 10% for the retention time and the peak width, respectively. The simulation method shows great significance for the optimization of separation conditions and the development of novel technologies of chromatographic separation.
研究领域:
分析化学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2021
·
IF 6.986
Yuling Wang,Rongrong Pan,Depeng Jiang,Dechen Jiang,Hong-Yuan Chen
The chemical reaction in a confined space is known to be accelerated due to a high collision probability; however, the study of this confinement effect in a supersmall space down to femtoliter (fL) is seldom reported. Here, an adjustable volume [from picoliter (pL) to fL] of the aqueous phase is retrained at the tip of a nanopipette by an organic solvent so that the confinement effect on the specific activity of glucose oxidase is investigated. The activity is determined by the amount of hydrogen peroxide generated from the reaction between the oxidase and glucose using a nanoelectrode inside the nanopipette. As compared with the activity in bulk solution (82 U/mg), the activity increases up to 7500 U/mg in a 105 fL space. The 2 orders of magnitude increase in the enzymatic activity is the highest amplification in the volume-confined enzyme reaction as reported. A near-exponential drop in the activity is observed with the increase in the space volume, revealing the dominant enhancement in the confined space at the fL level for the first time. The established electrochemical nanopipettes should not only provide a strategy for the study of the enzymatic activity in supersmall confined space but also help understand the confinement effect of enzyme-catalyzed reactions.
研究领域:
生物化学
·
电化学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Shuo Tao,Xiaolei Li,Huimin Gong,Qike Jiang,Wenguang Yu,Huaijun Ma,Renshun Xu,Zhijian Tian
Hierarchical MgAPO-11 molecular sieves with large BET surface areas and high pore volumes have been synthesized via dry-gel conversion of the magnesioaluminophosphate-carbon (MAP-C) composites. The carbon film coated on the mesopores of amorphous magnesioaluminophosphate (MAP) provides a confined-space to restrict the overgrowth of the crystals. The products were well characterized using XRD , SEM, TEM , N 2 adsorption-desorption, infrared spectroscopy of pyridine adsorption (Py-IR) and solid-state NMR techniques. The results show that highly mesoporous MgAPO-11 with good crystallinity can be obtained at an appropriate carbon loading amount. The time-dependent study indicates that the formation process of hierarchical MgAPO-11 obeys a reversed crystal growth route: crystallization started on the outer surface of the amorphous precursor, then extended to inward, and finally hierarchical molecular sieves assembled by nanosized crystals with a size of about 50 nm were obtained. The catalyst based on hierarchical MgAPO-11 exhibits a significant higher activity and selectivity than the conventional Pt/MgAPO-11 catalyst in the hydroisomerization of n -dodecane, attributing to its higher acidity and excellent diffusion properties resulting from the hierarchical pore architecture.
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2016
·Vol. 51
·期 11
·5113-5121
·
IF 2.302
Chen Mingsen,Sun Fameng,Xu Wangfa,Zhou Li,Zhang Faai
A series of polymerized high internal phase emulsion (polyHIPE) monoliths with internal phase contents varying from 82.5 to 94.0 % were synthesized. The limited spaces of the polyHIPE were used as reactors to polymerize methyl methacrylate (MMA) by reverse atom transfer radical polymerization (RATRP). The main purpose of this research was to investigate the effect of limited spaces of polyHIPE on RATRP polymerization. The monoliths before and after MMA polymerization and PMMA obtained in the polyHIPE were characterized by scanning electron microscopy, gel permeation chromatography, Fourier transform infrared spectroscopy, thermogravimetry analysis, hydrogen nuclear magnetic resonance, and differential scanning calorimetry. The results suggested that the monomer MMA had polymerized in the polyHIPE. Compared with PMMA by RATRP without confined space, the molecular weight, initial thermal decomposition temperature, glass transition temperature ( T
g ), and the isotacticity of the PMMA obtained from polyHIPE were increased significantly and the molecular weight distribution broadened. The increase in the internal phase contents increased the numbers of the cavities and windows, whereas the molecular weight, molecular weight distribution, and T
g of the PMMA obtained from different polyHIPEs did not change much.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2023
·
IF 10.9
Chun-Yan Wu,Yu-Xuan Le,Li-Yan Liang,Jing-Yue Li,Feng-Xia Liang,Shi-Rong Chen,Xiao-Ping Yang,Yu-Xue Zhou,Lin-Bao Luo
In this study, we report the fabrication of a sensitive deep ultraviolet (DUV) photodetector by using CsPbBr 3 nanosheets synthesized through confined-space growth at room temperature. The peak photoresponse of the device upon illumination blueshifts with decreasing thickness and a 68 nm CsPbBr 3 nanosheet based device displays a peak response to 265 nm illumination, showing responsivity and specific detectivity of 85 mA/W and 4.05 × 10 11 Jones at 3 V bias, respectively. Theoretical simulation reveals that the blueshift is associated with the wavelength-dependent absorption coefficient of CsPbBr 3 nanosheet: incident light with shorter wavelengths can be absorbed on the superficial surface, while long-wavelength light has a larger penetration depth, leading to dominant DUV absorption in thinner CsPbBr 3 nanosheet. This work will shed light on the facile and cost-effective fabrication of DUV photodetectors from non-ultrawide bandgap (UWBG) all-inorganic perovskite materials.
研究领域:
材料科学
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光子学
·
纳米技术
·
半导体物理
✓ 已验证
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2015
·
IF 5.636
Nannan Liu,Zekun Yang,Xiaoding Lou,Benmei Wei,Juntao Zhang,Pengcheng Gao,Ruizuo Hou,Fan Xia
Almost all of the important functions of DNA are realized by proteins which interact with specific DNA, which actually happens in a limited space. However, most of the studies about the protein–DNA binding are in an unconfined space. Here, we propose a new method, nanopore-based DNA-probe sequence-evolution (NDPSE), which includes up to 6 different DNA-probe systems successively designed in a nanoscale confined space which unveil the more realistic characteristics of protein–DNA binding phenomena. There are several features; for example, first, the edge-hindrance and core-hindrance contribute differently for the binding events, and second, there is an equilibrium between protein–DNA binding and DNA–DNA hybridization.
研究领域:
分子生物学
·
生物信息学
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生物物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TALANTA
·
2024
·
IF 5.6
Xin Geng,Yanqiu Wang,Hongli Li,David Da Yong Chen
Characterization of chemical composition in cigarette smoke is essential for establishing smoke-related exposure estimates. Currently used methods require complex sample preparation with limited capability for obtaining accurate chemical information. We have developed an in situ solid-phase microextraction (SPME) method for online processing of smoke aerosols and directly coupling the SPME probes with confined-space direct analysis in real time (cDART) ion source for high-resolution mass spectrometry (MS) analysis. In a confined space, the substances from SPME probes can be efficiently desorbed and ionized using the DART ion source, and the diffusion and evaporation of volatile species into the open air can be largely avoided. Using SPME-cDART-MS, mainstream smoke (MSS) and side-stream smoke (SSS) can be investigated and the whole analytical protocol can be accomplished in a few min. More than five hundred substances and several classes of compounds were detected and identified. The relative contents of 13 tobacco alkaloids were compared between MSS and SSS. Multivariate data analysis unveiled differences between different types of cigarette smoke and also discovered the characteristic ions. The method is reliable with good reproducibility and repeatability, and has the potential to be quantitative. This study provides a simple and high-efficiency method for smokeomics profiling of complex aerosol samples with in situ online extraction of volatile samples, and direct integration of extracted probes with a modified ambient ionization technique.
研究领域:
分析化学
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烟草科学
·
质谱分析
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nature Communications
·
2021
·Vol. 12
·期 1
·1-10
·
IF 14.919
Ma Qun,Li Yu,Wang Rongsheng,Xu Hongquan,Du Qiujiao,Gao Pengcheng,Xia Fan
Function elements (FE) are vital components of nanochannel-systems for artificially regulating ion transport. Conventionally, the FE at inner wall (FE IW ) of nanochannel − systems are of concern owing to their recognized effect on the compression of ionic passageways. However, their properties are inexplicit or generally presumed from the properties of the FE at outer surface (FE OS ), which will bring potential errors. Here, we show that the FE OS independently regulate ion transport in a nanochannel − system without FE IW . The numerical simulations, assigned the measured parameters of FE OS to the Poisson and Nernst-Planck (PNP) equations, are well fitted with the experiments, indicating the generally explicit regulating-ion-transport accomplished by FE OS without FE IW . Meanwhile, the FE OS fulfill the key features of the pervious nanochannel systems on regulating-ion-transport in osmotic energy conversion devices and biosensors, and show advantages to (1) promote power density through concentrating FE at outer surface, bringing increase of ionic selectivity but no obvious change in internal resistance; (2) accommodate probes or targets with size beyond the diameter of nanochannels. Nanochannel-systems with only FE OS of explicit properties provide a quantitative platform for studying substrate transport phenomena through nanoconfined space, including nanopores, nanochannels, nanopipettes, porous membranes and two-dimensional channels.
研究领域:
纳米技术
·
材料科学
·
生物物理学
·
电化学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）