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近红外光谱方法在颌面外科皮瓣移植术后监测中的应用 总被引:10,自引:4,他引:6
近红外光谱技术作为一种无创组织氧监测手段,近年来在整形外科手术术后监测方面得到了越来越多的重视。文章利用一套近红外无损组织氧检测系统对6例手术成功病例的移植皮瓣侧和对照侧正常组织内的氧饱和度进行了长时间对比监测,发现两侧的组织氧饱和度之间存在显著性差异。还对一例血管吻合失败的病例下颌部的多个位置进行了检测,发现坏死部位的氧饱和度和正常组织相比处于很低的水平。实验结果表明,近红外光谱检测技术对于皮瓣内的血氧浓度动态变化具有很好的灵敏度,在移植皮瓣的术后监测方面具有良好的应用前景。 相似文献
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基于组织光学原理研发了组织氧饱和度无损检测仪。利用该仪器检测了101名受试者(其中健康锻炼者42人,健康不锻炼者34人,脾虚证患者25人)在进行递增负荷功率自行车运动实验时,股四头肌外侧头的肌氧变化过程。测得的血红蛋白浓度(ctHb)受脂肪等外层组织影响较大,而肌氧饱和度(rSO2)受影响较小。实验结果显示, 在运动过程中,随着运动负荷的逐渐增加,骨骼肌中的总血红蛋白浓度逐渐上升,肌氧饱和度逐渐降低;当运动停止后,总血红蛋白浓度和肌氧饱和度都出现快速上升。运动中肌氧饱和度的变化幅度与受试者运动能力有密切关系。利用局部组织氧饱和度这一指标来评价肌肉组织中氧的输送与消耗的平衡点,进而实现了对肌肉组织有氧代谢能力的定量评估。 相似文献
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公共网络的开放性和自组织特性导致网络容易受到病毒干扰和入侵攻击,对攻击数据的准确高效挖掘能确保网络安全。传统方法采用时频指向性波束特征聚类方法实现攻击数据挖掘,在信噪比较低时攻击数据准确挖掘概率较低。提出一种基于自适应滤波检测和时频特征提取的公共网络攻击数据挖掘智能算法。首先进行公共网络攻击数据的信号拟合和时间序列分析,对含噪的攻击数据拟合信号进行自适应滤波检测,提高信号纯度,对滤波输出数据进行时频特征提取,实现攻击数据的准确挖掘。仿真结果表明,采用该算法进行网络攻击数据挖掘,对攻击数据特征的准确检测性能较高,对干扰的抑制性能较强,能有效实现网络安全防御。 相似文献
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氧化锆氧传感器及其应用 总被引:1,自引:0,他引:1
氧化锆氧传感器是采用氧化锆固体电解质组成的氧浓差电池来测氧的传感器。它是本世纪60年代才兴起的,属于固体离子学中一个重要应用方面。这类氧传感器已在国内外广泛用于工业炉窑优化燃烧,产生了显著的节能效果;广泛用于汽车尾气测量,明显地改善了城市环境污染;广泛用于钢液测氧,大大提高了优质钢的质量和产量;广泛用于惰性气体中测氧,其灵敏度和测氧范围非其它氧量计可比。本文从理论分析和实际应用两个方面阐述了上述问题。 相似文献
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Molecular Diversity - In the absence of efficient anti-viral medications, the coronavirus disease 2019 (COVID-19), stemming from severe acute respiratory syndrome coronavirus-2 (SARS CoV-2), has... 相似文献
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Small world network models have been effective in capturing the variable behaviour of reported case data of the SARS coronavirus outbreak in Hong Kong during 2003. Simulations of these models have previously been realized using informed “guesses” of the proposed model parameters and tested for consistency with the reported data by surrogate analysis. In this paper we attempt to provide statistically rigorous parameter distributions using Approximate Bayesian Computation sampling methods. We find that such sampling schemes are a useful framework for fitting parameters of stochastic small world network models where simulation of the system is straightforward but expressing a likelihood is cumbersome. 相似文献
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Studying the effect of oxygen in coal oxidation is very important for understanding and controlling coal spontaneous combustion. However, the oxygen effect is not very easy to determine clearly due to the large effect of heat source on coal oxidation in temperature rising experiments. Here, focused on sub-bituminous coal, the oxygen effect was separated from coal oxidation by continuously measuring FTIR spectra of coal with respect to varying temperatures and under oxygen and nitrogen. The active groups’ real-time changes of coal oxidation, thermal treatment and oxygen effect were measured. The carboxylic ester and carboxyl units are the main functional groups that increase with temperatures increasing under oxygen and nitrogen, while the other functional groups decrease in quantity. The oxygen effect promoted the consumption of aliphatic hydrocarbons and hydroxyl groups and also promoted the formation of oxygen-containing groups (except hydroxyl). Four characteristic temperature stages involved in the oxygen effect and their key functional groups were identified. Simultaneously, the relationship of oxygen consumption and chemisorption in oxygen effect was analyzed. The starting temperature of oxygen chemisorption is between 50 and 60°C. The maximum contribution of oxygen effect was observed in methyl and methylene groups. These results are important for chemical control of coal spontaneous combustion. The oxidation of aliphatic hydrocarbon should be controlled before oxygen chemisorption. The value of oxygen consumption between 70 and 80°C can be measured accurately due to the constant chemisorption rate, which help to identify the tendency for spontaneous combustion. These results will help in better understanding of the reaction mechanism of coal oxidation, especially the oxygen effect. 相似文献
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McGrath DM Naish JH O'Connor JP Hutchinson CE Waterton JC Taylor CJ Parker GJ 《Magnetic resonance imaging》2008,26(2):221-227
The objective was to measure the effect of 100% oxygen inhalation on T1 relaxation times in skeletal muscle. Healthy volunteers were scanned using three different MRI protocols while breathing medical air and 100% oxygen. Measurements of T1 were made from regions of interest (ROIs) within various skeletal muscle groups. Dynamic data of subjects breathing a sequence of air-oxygen-air allowed the calculation of characteristic wash-in and -out times for dissolved oxygen in muscle. Contrary to previous findings, a statistically significant decrease in T1 in skeletal muscle was observed due to oxygen inhalation. We report approximate baseline characteristic values for the response of skeletal muscle to oxygen inhalation. This measurement may provide new biomarkers for evaluation of oxygen delivery and consumption in normal and diseased skeletal muscle. 相似文献
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A global event such as the COVID-19 crisis presents new, often unexpected responses that are fascinating to investigate from both scientific and social standpoints. Despite several documented similarities, the coronavirus pandemic is clearly distinct from the 1918 flu pandemic in terms of our exponentially increased, almost instantaneous ability to access/share information, offering an unprecedented opportunity to visualise rippling effects of global events across space and time. Personal devices provide “big data” on people’s movement, the environment and economic trends, while access to the unprecedented flurry in scientific publications and media posts provides a measure of the response of the educated world to the crisis. Most bibliometric (co-authorship, co-citation, or bibliographic coupling) analyses ignore the time dimension, but COVID-19 has made it possible to perform a detailed temporal investigation into the pandemic. Here, we report a comprehensive network analysis based on more than 20,000 published documents on viral epidemics, authored by over 75,000 individuals from 140 nations in the past one year of the crisis. Unlike the 1918 flu pandemic, access to published data over the past two decades enabled a comparison of publishing trends between the ongoing COVID-19 pandemic and those of the 2003 SARS epidemic to study changes in thematic foci and societal pressures dictating research over the course of a crisis. 相似文献
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In this article, we have proposed an epidemic model based on the
probability cellular automata theory. The essential mathematical
features are analysed with the help of stability theory. We have
given an alternative modelling approach for the spatiotemporal system
which is more realistic from the practical point of view. A discrete
and spatiotemporal approach is shown by using cellular automata
theory. It is interesting to note that both the size of the endemic
equilibrium and the density of the individuals increase with the
increase of the neighbourhood size and infection rate, but the
infections decrease with the increase of the recovery rate. The
stability of the system around the positive interior equilibrium has
been shown by using a suitable Lyapunov function. Finally,
experimental data simulation for SARS disease in China in 2003 and a
brief discussion are given. 相似文献
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Long RC Papas KK Sambanis A Constantinidis I 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,146(1):49-57
This investigation implements specifically designed solvent-suppressed adiabatic pulses whose properties make possible the long-term monitoring of (1)H NMR detectable metabolites from alginate/poly-l-lysine/alginate (APA)-encapsulated betaTC3 cells. Our encapsulated preparations were maintained in a perfusion bioreactor for periods exceeding 30 days. During this prolonged cultivation period, the cells were exposed to repetitive hypoxic episodes of 4 and 24 h. The ratio of the total choline signal (3.20 ppm) to the reference signal (observed at 0.94 ppm assigned to isoleucine, leucine, and valine) decreased by 8-10% for the 4-h and by 20-32% for the 24-h episodes and returned to its prehypoxic level upon reoxygenation. The decrease in the mean value of total choline to reference signal ratio for three 4-h and two 24-h episodes in two different cultures was highly significant (P<0.01). The rate of recovery by this ratio was slower than the rates of recovery by oxygen consumption, lactate production, or glucose consumption. A step-up in oxygen level led to a new, higher value for the total choline to reference ratio. From spectra of extracts at 400 MHz, it was determined that 63.6% of the total choline signal is due to intracellular phosphorylcholine. Therefore, it is inferred that the observed changes in total choline signal are linked to an oxygen level dependence of the intracellular phosphorylcholine. Several possible mechanisms in which oxygen may influence phosphorylcholine metabolism are suggested. In addition, the implications of these findings to the development of a noninvasive monitoring method for tissue-engineered constructs composed of encapsulated cells are discussed. 相似文献
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气相过氧化氢为强氧化剂,其消毒、灭菌的最终产物为水和氧气,具有无残留、安全、快速消毒以及广泛的材料兼容性等优点。广泛应用于制药、医疗、卫生、生物安全等领域,特别是新冠肺炎、MERS、SARS以及甲流等呼吸类传染性疾病的消毒防治。为保证灭菌效果,防止无菌检查的假阴性或者假阳性,需要对过氧化氢的浓度进行监测。基于1 255 cm-1量子级联激光器可调谐激光吸收光谱技术研制了一套气相过氧化氢浓度测量装置,浓度测量范围为0~1 800 ppm。采用V型光路结构、窗口片将检测仪主要部件与过氧化氢进行隔离,避免过氧化氢腐蚀。针对高浓度、高吸光度时一阶泰勒级数近似透射率函数误差较大这一情况,采用二阶泰勒级数近似透射率函数,导出了二次谐波信号关于气体浓度的二次函数。二次谐波信号测得是电压值,采用高锰酸钾滴定法对其进行标定、溯源。最终得到气相过氧化氢浓度的测量公式,对高低浓度过氧化氢都拟合较好,拟合误差最大为3%。当湿度变化时,二次谐波信号没有发生变化,排除水分对过氧化氢测量的影响,适用于灭菌过程中常压下高浓度VHP的浓度测量。 相似文献
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气体混合是微流动系统的重要应用之一.本文使用DSMC方法,数值模拟了不同进出口压力下简单和复杂微通道内H2和O2的混合过程,并从满足完全燃烧的氢氧摩尔流量比的角度,讨论了进出口压力以及两种气体入口压力比和宽度比(截面面积比)对摩尔流量比的影响. 相似文献
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The inhibition effect of methylene chloride CH2Cl2, chloroform CHCl3 and carbon tetrachloride CCl4 on the ozone generation process from oxygen by negative corona discharge was experimentally investigated. The experiments were performed in a system of coaxial cylindrical electrodes at total gas pressure of 900 mbar and ambient temperature of gaseous mixtures. The rate of ozone generation as well as ozone concentration apparently decreases with a rising number of substituted chlorine atoms in the methane molecule at constant specific energy consumption dissipated in the discharge and at constant concentration of gaseous impurities in oxygen. In addition to experimental results, the paper presents theoretical considerations aimed at identifying the main process responsible for inhibition of ozone generation. The consumption of considerable fraction of oxygen atoms by CH
x
Cl
y–1 radicals formed in discharge, is likely the most important mechanism responsible for the deleterious effect of such compounds on the efficiency of ozone production. 相似文献