基于数字岩心技术的气体解析/扩散格子Boltzmann模拟

在页岩气和煤层气等非常规储层中普遍存在着气体解析/扩散现象,为了描述微观尺度下的流动模拟,通过在格子Boltzmann方法的演化方程中添加源汇项,模拟了多孔介质中的解析/扩散现象。并以Langmuir等温吸附定律为例进行模拟,模型计算结果与宏观扩散方程的有限差分结果基本一致,但有限差分方法对时间步长要求较高,计算量比格子Boltzmann方法大,格子Boltzmann方法在迭代次数上具有明显的优势。最后基于CT扫描的二维数字岩心,模拟了气体在复杂结构多孔介质中气体解析/扩散过程。这种处理方式避免了复杂的边界条件,计算量不会明显增加,并可以用来模拟具有复杂孔隙结构的真实岩心中的解析/扩散现象,同时可以根据不同储层中气体满足的解析/吸附规律来配置源汇项。

A review of defect engineering in two‐dimensional materials for electrocatalytic hydrogen evolution reaction

The exploration of efficient and earth‐rich electrocatalysts for electrochemical reactions is critical to the implementation of large‐scale green energy conversion and storage techniques.Two‐dimensional(2D)materials with distinctive structural and electrochemical properties provide fertile soil for researchers to harvest basic science and emerging applications,which can be divided into metal‐free materials(such as graphene,carbon nitride and black phosphorus)and transition metal‐based materials(such as halogenides,phosphates,oxides,hydroxides,and MXenes).For faultless 2D materials,they usually exhibit poor electrochemical hydrogen evolution reaction(HER)activity because only edge sites can be available while the base surface is chemically inactive.Defect engineering is an effective strategy to generate active sites in 2D materials for improving electrocatalytic activity.This review presents feasible design strategies for constructing defect sites(including edge defects,vacancy defects and dopant derived defects)in 2D materials to improve their HER performance.The essential relationships between defect structures and electrocatalytic HER performance are discussed in detail,providing valuable guidance for rationally fabricating efficient HER electrocatalysts.The hydrogen adsorption/desorption energy can be optimized by constructing defect sites at different locations and by adjusting the local electronic structure to form unsaturated coordination states for efficient HER.

THE N-NITROSAMINES IN TOBACCO SMOKE AND ITS ADSORPTION AND DEGRADATION

N-nitrosamines are strong carcinogens for humans. This paper gives an overview of the nitrosmaines in cigarette smoke including the formation, the harmfulness, the analytical methods of the nitrosmaines and the adsorptions and degradations of N –nitrosamines.

Dissolved Silica Adsorbed onto MnO_2 in Catalyzing the Decomposition of H_2O_2: Molecular Structural Rearrangement Revealed by FTIR,SEM-EDX and XRD

It has been generally unclear over the mechanism of inhibitory influence of silicate on structural rearrangement or solely physical adsorption onto manganese dioxide （MnO2） about the decomposition of hydrogen peroxide （H2O2）. Consequently, several experiments were carried out by using MnO2 as a catalyst for the decomposition of H2O2 in a concentration series under certain concentrations of silicates. The silicates were analyzed by using a molybdenum blue colorimetric method. The results showed that the determination of silicates was inhibited by H2O2, whose inhibitory effect was greatly increased by increasing its concentration, but not limited by pH. SEM-EDX （scanning electron microscopy-energy dispersive x-ray spectrometry） results showed that the adsorption of silicates onto the surface of MnO2 was not purely via a structural rearrangement, with increasing Mn atoms protruding on the outer surface by covering oxygen and silicon atoms. XRD （X-ray diffraction） and FTIR （Fourier transform infrared） spectra results further revealed no significant total crystal structural changes in MnO2 after the adsorption of silicates, but only a small shift of 0.21° at 2e from 56.36° to 56.15° , and a FTIR vibration showed at around 1 050 cm-1. The results, therefore, showed that silicate adsorption onto MnO2 took place via both surface adsorption and structural rearrangement by interfacial reaction.

Silicene nanoribbons as carbon monoxide nanosensors with molecular resolution

Applications based on silicene as grown on substrates are of high interest toward actual utilization of this unique material. Here we explore, from first principles, the nature of carbon monoxide adsorption on semiconducting silicene nanoribbons and the resulting quantum conduction modulation with and without silver contacts for sensing applications. We find that quantum conduction is detectably modified by weak chemisorption of a single CO molecule on a pristine silicene nanoribbon. This modification can be attributed to the charge transfer from CO to the silicene nanoribbon and the deformation induced by the CO chemisorption. Moderate binding energies provide an optimal mix of high detectability and recoverability. With Ag contacts attached to a -1 nm silicene nanoribbon, the interface states mask the conductance modulations caused by CO adsorption, emphasizing length effects for sensor applications. The effects of atmospheric gases--nitrogen, oxygen, carbon dioxide, and water--as well as CO adsorption density and edge-dangling bond defects, on sensor functionality are also investigated. Our results reveal pristine silicene nanoribbons as a promising new sensing material with single molecule resolution.

Using MALDI-TOF MS coupled with a high-mass detector to directly analyze intact proteins in thyroid tissues

Protein analysis is vital for biological and clinical research, but the measurement of unseparated, intact and high-mass proteins is also a challenging task by mass spectrometry-based methods. Here, we present a protocol for rapid and high-throughput analysis of intact proteins in tissue samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDITOF MS） combined with a high-mass detector platform. The method involves tissue specimens that undergo a simple protein extraction before MALDI-MS analysis. Using this method, the high abundance proteins in human thyroid carcinoma and paracarcinoma tissues were successfully investigated, and the mass spectra of the tissues of the 30 illustrated thyroid cancers showed remarkable differences. The peak intensity revealed a significant increase in human albumin in thyroid carcinoma tissues（p＆lt;0.05）. To validate the feasibility and credibility of this method, label-free proteomics quantitative analysis and Western blotting were used to relatively quantify the proteins in these tissues. Those results demonstrated a nearly 3-fold difference in human albumin levels between thyroid carcinoma and para-carcinoma tissues, which were consistent with the results of our method. The advantages of our method are easy sample handling, remarkable reproducibility and the ability to analyze high-mass proteins without digestion, which make them have the potential to be used in biological research and in clinical practice.