Regional homogeneity of resting-state fMRI contributes to both neurovascular and task activation variations

The task induced blood oxygenation level dependent signal changes observed using functional magnetic resonance imaging (fMRI) are critically dependent on the relationship between neuronal activity and hemodynamic response. Therefore, understanding the nature of neurovascular coupling is important when interpreting fMRI signal changes evoked via task. In this study, we used regional homogeneity (ReHo), a measure of local synchronization of the BOLD time series, to investigate whether the similarities of one voxel with the surrounding voxels are a property of neurovascular coupling. FMRI scans were obtained from fourteen subjects during bilateral finger tapping (FTAP), digit–symbol substitution (DSST) and periodic breath holding (BH) paradigm. A resting-state scan was also obtained for each of the subjects for 4 min using identical imaging parameters. Inter-voxel correlation analyses were conducted between the resting-state ReHo, resting-state amplitude of low frequency fluctuations (ALFF), BH responses and task activations within the masks related to task activations. There was a reliable mean voxel-wise spatial correlation between ReHo and other neurovascular variables (BH responses and ALFF). We observed a moderate correlation between ReHo and task activations (FTAP: r = 0.32; DSST: r = 0.22) within the task positive network and a small yet reliable correlation within the default mode network (DSST: r = − 0.08). Subsequently, a linear regression was used to estimate the contribution of ReHo, ALFF and BH responses to the task activated voxels. The unique contribution of ReHo was minimal. The results suggest that regional synchrony of the BOLD activity is a property that can explain the variance of neurovascular coupling and task activations; but its contribution to task activations can be accounted for by other neurovascular factors such as the ALFF.     

Electrostatic potential of several small molecules from density functional theory

A number of density functional theory (DFT) methods were used to calculate the electrostatic potential for the series of molecules N2, F2, NH3, H2O, CHF3, CHCl3, C6H6, TiF4, CO(NH2)2 and C4H5N3O compared with QCISD (quadratic configuration interaction method including single and double substitutions) results. Comparisons were made between the DFT computed results and the QCISD ab initio ones and MP2 ab initio ones, compared with the root-mean-square deviation and electrostatic potential difference contours figures. It was found that the hybrid DFT method B3LYP, yields electrostatic potential in good agreement with the QCISD results. It is suggest this is a useful approach, especially for large molecules that are difficult to study by ab initio methods.     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica Sinica.     

Can an IR Diode Laser Spectrometer be Used for the Determination of Natural Isotope Ratios in Biological Samples?

Abstract

An IR diode laser spectrometer can detect the enrichment of stable isotopes (¹³C [1] and ¹⁵N[2]) in tracer studies. However our system cannot detect differences of the natural abundances of these isotopes. This problem is not a principal limitation of the IR diode laser spectroscopy, but is inherent to our standard system. A new isotope ratio IR diode laser spectrometer has an accuracy high enough for most biological applications. Some advantages like flexibility in measuring different isotopes, insensitivity against other gases in the sample and price are correlated to this system.     

Instructions for Authors

Chinese Physics B （Chin. Phys. B）, formerly titled Chinese Physics, is an international comprehensive academic journal, aiming to publish original papers and rapid communications reflecting creative and innovative achievements in physics, as well as review papers about important accomplishments in frontier of physics. The journal is published monthly in English by the Chinese Phvsical Society （CPS） and the IOP Publishing. Chin.     

基于气息图案法有序多孔薄膜的制备改性及应用进展

有序多孔薄膜在过滤分离、催化、生物医学等领域有重要的应用前景。在众多制膜方法中,气息图案法以其简便易行、制膜效果好、环保等特点得到了广泛关注。科学家们一直致力于采用不同的材料和手段来进一步提高气息图案法多孔薄膜的性能。本文结合了最新的研究状况,探讨了基于气息图案法有序多孔薄膜的制备、改性及应用进展,并对未来的发展方向作...     

Analysis of biogenic volatile organic compounds in human health and disease

The analysis of volatile biomarkers of disease in breath is attractive because breath analysis is non-invasive and quick, and allows for repeated sampling. Challenges faced in the development of breath analysis include developing techniques that can measure analytes at very low concentrations, gaining an understanding of the exhalation physiology of individual volatiles, and determining the relationship between the proposed biomarker and the underlying condition. A small number of breath tests are used in clinical practice, but there is great potential for the development and wider application of clinical breath analysis in infection, inflammation, cancer and metabolic disease.     

Nanostructure formation in polymer thin films influenced by humidity

The influence of relative humidity (RH) during the film preparation on the surface morphology and on the material distribution of the resulting technical polymer blend films consisting of poly (methyl methacrylate) (PMMA) and poly (vinyl butyral) (PVB) is investigated by atomic force microscopy. Both pure polymers and polymer blends with different compositions of PVB/PMMA dissolved in tetrahydrofuran (THF) were used. Polymer films prepared under dry conditions (RH < 20%) are compared with those that have the same polymer composition but were prepared under increased humidity conditions (RH > 80%). The films consisting of the pure polymers showed a nonporous surface morphology for low‐humidity preparation conditions, whereas high‐humidity preparation conditions lead to porous PVB and PMMA films, respectively. These pores are explained as the result of a breath figure formation. In the case of the polymer blend films containing both polymers, porous or phase‐separated surface structures were observed even at low‐humidity conditions. A superposition of the effects of phase separation and breath figure formation is observed in the case of polymer blend films prepared under high‐humidity conditions. Atomic force microscopy (AFM) images taken before and after the treatment with ethanol as a selective solvent for PVB indicate that PMMA is deposited on top of a PVB layer in the case of the low‐humidity preparation process whereas for high‐humidity conditions the silicon substrate is covered with a PMMA film. Copyright © 2006 John Wiley & Sons, Ltd.     

呼气中痕量挥发性有机物的质子转移反应质谱在线检测研究

通过对自主研制的大气成分在线检测质子转移反应质谱的进样管路系统进行改造,建立了可在线检测呼气中痕量挥发性有机物的质子转移反应质谱装置。通过对呼气进样系统的旁路流量控制,实现对进样速度的调控,既可提高进样速度,以满足实时监测呼气中指定成分浓度变化;也可适时关闭旁路,以降低进样速度,从而对呼气成分进行全谱分析,避免采样袋采样和浓缩的复杂程序和潜在干扰。以作者呼出气体作为研究对象,对装置性能进行测试,结果表明:装置最快响应时间可达1s,对呼气中丙酮的探测灵敏度高达每10-9(V/V)浓度的信号强度为14.6counts/s,多次呼气测量重复性好,有望广泛应用于呼气疾病诊断研究。