脑电图机电极与头皮接触阻抗的检测

脑电图机中电极与头皮接触的好坏对脑电波形质量有很大影响，本文利用AT89C51单片机实现电极与头皮接触阻抗的检测。还通过发光二极管给予医务人员对电极接触好坏直观的指示。     

益生菌通过肠-皮肤轴改善皮肤疾病

肠道微生物区系是肠-皮肤轴的主要调节因子,可以将肠道与炎症性皮肤病联系起来.调节肠道微生物区系可改善肠道微环境,进而影响皮肤健康.虽然越来越多的证据证明了肠-皮肤轴的存在,但他们之间的作用机制还有待阐明.本文总结了肠道微生物与三种常见皮肤病——痤疮、特异性皮炎、银屑病相互作用的最新进展,与此同时提出了补充益生菌和改善饮...     

心阻抗图的弹性腔-边值问题理论模型

分析了造成Ｎｙｂｏｅｒ－Ｋｕｂｉｃｅｋ公式与用其它较可靠的方法测得的每搏心排量相差较大的五个主要原因,并针对其中前三个原因,修改了原有的物理模型,用弹性腔模型及解边值问题的方法得出了一种心阻抗图的新理论模型;最后对此新理论模型作了初步的讨论     

尿酸在聚6-甲基香豆素修饰的玻碳电极上的电化学行为

制备了聚6-甲基香豆素修饰玻碳电极,研究了尿酸(UA)在该修饰电极上的电化学行为。实验结果表明:在pH=5.0的磷酸盐缓冲溶液中,扫描速率为50mV/s时,尿酸在修饰电极上于0.352V处产生一个灵敏的氧化峰,在0.278V处有一弱的还原峰。经线性扫描伏安法测定,氧化峰电流与尿酸浓度在2.5×10-6～1.0×10-5mol/L范围内表现出良好的线性关系,检出限为1.0×10-6mol/L。将修饰电极在常温下放置50d及将体系温度升高到75℃时,修饰电极对尿酸的响应电流大体不变,结果满意。     

多导联在线阻抗检测的实现与分析

目的：提出了一种基于多导联生理信号采集装置平台的快速、稳定、低功耗的在线阻抗测量方法。方法：在线阻抗测量的实现主要有两个关键技术：正弦信号恒流源和数字带通滤波器,都主要是采用软件的方式实现的。结果：单极性和双极性两种模式四组测量阻值的变异系数均不超过10%,测量值的稳定性较高,可以通过多次测量求平均值的办法来修正测量误差,修正后的误差明显优于修正之前的误差。结论：由单极性和双极性两种模式实际阻抗测量值可知,测量值能够准确反映电极与人体表皮的接触情况,此种方法稳定可靠。     

皮肤肿瘤早期筛查的快速无创电阻抗检测方法

目的 随着环境问题和臭氧层空洞化的加剧,皮肤肿瘤的患病率也大幅增加,但是皮肤肿瘤前期隐蔽性高、症状不明显,导致大部分病例都是在中晚期发现的。因此,本文基于生物阻抗谱(bioimpedance spectroscopy,BIS)技术,提出一种皮肤肿瘤早期筛查的快速无创电阻抗检测方法。方法 首先,建立四层皮肤模型,采用数值分析方法研究角质层对BIS测量的阻碍作用。其次,使用去除角质层的皮肤模型研究混有不同半径和浸润深度的皮肤肿瘤组织电学特性。最后,使用凝胶处理后的猪皮组织实验验证肿瘤浸润深度(h)的影响。结果 角质层仿真结果表明,去除角质层的皮肤对激励信号的响应更明显。皮肤肿瘤模型仿真表明,当肿瘤半径(R_tumor)及h>1.5 mm时能够区分肿瘤组织与正常组织。同时根据实验结果中正常组织与肿瘤组织虚部弛豫阻抗(Z_imag-relax)定义了组织病变度(ε_worse,为肿瘤组织虚部阻抗相对于正常组织虚部阻抗变化的百分比),并绘制了肿瘤组织浸润深度(Depth)与Z_imag-relax的拟合曲线。当...     

局部5-氨基酮戊酸光动力学疗法在皮肤真菌感染中的应用

局部5-氨基酮戊酸光动力疗法是利用光敏剂和光辐射治疗疾病的方法,目前多用于皮肤肿瘤、某些癌前病变和病毒疣等的治疗.皮肤真菌感染是一种常见病,由皮肤癣菌或念珠菌引起,使用标准抗真菌药物疗法治疗皮肤真菌感染,周期长,费用高,易出现耐药性;目前急需新的治疗方法.本文回顾了局部5-氨基酮戊酸光动力学疗法在体内、体外条件下对皮肤真菌感染的作用.     

老化皮肤的纹理分析

本文利用多光子显微镜从亚微米尺度下研究皮肤老化过程的纹理特征。通过多光子显微镜在体获得年轻皮肤及自然老化皮肤的表皮纹理及形态特征。对表皮纹理和形态的图片分别进行纹理网格分析及分形分析,结果显示两种分析法具有高度的相似性及相关性。本文研究显示以皮肤纹理网格数和皮肤分形维数为特征参量可有效评价皮肤老化的纹理特征。     

小鼠皮肤损伤修复过程中白细胞介素-6对某些炎症因子基因表达的影响

为了解在皮肤损伤修复过程中白细胞介素-6(Interlukin-6,IL-6)对其他炎症因子基因表达的影响,以及对皮肤损伤修复过程的影响,用免疫组织化学染色法和RT—PCR法,检查了IL-6基因敲除鼠(IL-6^-/-鼠)和正常野生型鼠(IL-6^ / 鼠)皮肤损伤后损伤区组织内不同时间的白细胞介素-1α(Interlukin-1α,IL-1α)、白细胞介素-1β(Interlukin-1β,IL-1β)、角质细胞诱导因子(Keratinocyte chemoattractant,KC)、单核细胞诱导蛋白-1α(Macrophage inflammatory protein-1α,MIP-1α)以及单核细胞诱导蛋白-2(Macrophage inflammatory protein-2,MIP-2)这5种炎症因子的基因表达的变化。结果发现：不论是IL-6^-/-鼠还是IL-6^ / 鼠,其被检因子的基因表达都以第3d为高峰,第6d则明显下降;同时,在损伤后的第3d和第6d,IL-6^-/-鼠的5种因子的基因表达水平显著低于IL-6^ / 鼠,而在损伤后的第1d,只有MIP-1α和KC的水平低于IL-6^ / 鼠,而且,IL-6^-/-鼠的皮肤损伤修复过程也稍迟于IL-6^ / 鼠,但皮肤的损伤仍可完全修复。上述结果显示,IL-6在小鼠皮肤损伤过程中诱导其他5种被检因子的产生,从而促进皮肤损伤的修复,但IL-6基因缺失也不会严重影响皮肤损伤的修复。     

大面积皮肤坏死患者的临床分析

目的探讨大面积皮肤坏死的诱因、治疗和危害。方法对1998年1月至2008年1月收治的36例患者大面积皮肤坏死的情况进行调查分析。结果大面积皮肤坏死引起肢体功能障碍15例,部分功能障碍19例,无功能障碍2例。结论大面积皮肤坏死与皮肤撕脱,厌氧菌和需氧菌混合感染,其他继发疾患引起有关,应采取积极治疗措施,提高患者生存质量。     

Myocardial Infarction Detection and Localization Using Optimal Features Based Lead Specific Approach

ObjectivesObjective of this paper is to present a reliable and accurate technique for Myocardial Infarction (MI) detection and localization.Material and methodsStationary wavelet transform has been used to decompose the ECG signal. Energy, entropy and slope based features were extracted at specific wavelet bands from selected lead of ECG. k-Nearest Neighbors (kNN) with Mahalanobis distance function has been used for classification. Sensitivity (Se), specificity (Sp), positive predictivity (+P), accuracy (Acc), and area under the receiver operating characteristics curve (AUC) analyzed over 200 subjects (52 health control, 148 with MI) from Physikalisch-Technische Bundesanstalt (PTB) database has been used for performance analysis. To handle the imbalanced data adaptive synthetic (ADASYN) sampling approach has been adopted.ResultsFor detection of MI, the proposed technique has shown an AUC = 0.99, Se = 98.62%, Sp = 99.40%, PPR = 99.41% and Acc = 99.00% using 12 top ranked features, extracted from multiple leads of ECG and AUC = 0.99, Se = 98.34%, Sp = 99.77%, PPR = 99.77% and Acc = 99.05% using 12 features extracted from a single ECG lead (i.e. lead V5). For localization of MI, the proposed technique has an AUC = 0.99, Se = 98.78%, Sp = 99.86%, PPR = 98.80%, and Acc = 99.76% using 5 top ranked features from multiple leads of ECG and AUC = 0.98, Se = 96.47%, Sp = 99.60%, PPR = 96.49% and Acc = 99.28% using 8 features extracted from a single ECG lead (i.e. lead V3).ConclusionThus for MI detection and localization, the proposed technique is independent of time-domain ECG fiducial markers and can work using specific leads of ECG.     

Wavelet threshold based ECG compression using USZZQ and Huffman coding of DSM

In this paper, a new Wavelet threshold based ECG signal compression technique using uniform scalar zero zone quantizer (USZZQ) and Huffman coding on differencing significance map (DSM) is proposed. Wavelet coefficients are selected based on the energy packing efficiency of each sub-band. Significant Wavelet coefficients are quantized with uniform scalar zero zone quantizer. Significance map is created to store the indices of the significant coefficients. This map is encoded efficiently with less number of bits by applying Huffman coding on the differences between indices in the significance map. ECG records from the MIT-BIH arrhythmia database are selected as test data. For the record 117, the proposed technique achieves a compression ratio of 18.7:1 with lower percentage root mean square difference (PRD) compared to other threshold based methods. The proposed technique is tested for MIT-BIH arrhythmia record 119 and a compression ratio of 21.81:1 is achieved with a PRD value of 3.716% which is much lower compared to the reported PRD value of 5.0 and 5.5% of set partitioning in hierarchical tress (SPIHT) and analysis by synthesis ECG compressor (ASEC), respectively. The noise eliminating capability of the proposed technique is also demonstrated in this work. The proposed technique achieves the required compression ratio with less reconstruction error for GSM-based cellular telemedicine system.     

个体化快速心律失常虚拟介入手术体系的建立与临床应用价值研究

目的:建立个体化快速心律失常虚拟介入手术体系定位手术靶点并分析其临床应用价值。方法:收集2011年1月-2013年1月在我院进行射频消融手术治疗的室性早搏和房室折返性心动过速患者共120例,(其中室性早搏40例,房室折返性心动过速80例),平均年龄40.6±9.7岁,获取数字新电机记录18导体表心电图(ECG)、数字食道调搏图、心脏CT成像原始数据,并记录手术靶点。所有采集心电图和CT数据进行多模式序列识别系统的计算机辅助诊断(CAD)处理,然后再对处理后的数据进行分析。两名心内科医生人工对心电图进行分析定位,并不告知患者的临床资料及射频消融手术最终靶点定位结果,按照室性早搏和房室旁路的诊断定位标准进行诊断,随后两名医师对处理后的心电图进行诊断,再次得出诊断结果,以术中成功消融靶点定位诊断为金标准,分析,个体化快速心律失常虚拟介入手术体系定位手术靶点的特异性、敏感性、阳性预测值,阴性预测值等指标。结果:ECG+CAD组诊断准确度高于单独ECG组,ECG组ROC曲线下面积(Az)=0.742,95%可信区间[0.652-0.832];ECG+CAD组:Az=0.934,95%可信区间[0.882-0.985];ECG+CAD组:精确度0.908;敏感性:0.905;特异性:0.923;阳性预测值:0.818;阴性预测值:0.934,较单独ECG组明显提高。结论:与单独体表心电图定位诊断相比,虚拟介入手术体系显著提高快速心律失常诊靶点定位的准确度,临床应用价值更高。     

Nanowire‐Based Three‐Dimensional Transparent Conducting Oxide Electrodes for Extremely Fast Charge Collection

A 3D transparent conducting oxide (3D‐TCO) has been fabricated by growing Sn‐doped indium oxide (ITO) nanowire arrays on glass substrates via a vapor transport method. The 3D TCO charge‐collection properties have been compared to those of conventional two‐dimensional TCO (2D‐TCO) thin films. For use as a photoelectrode in dye‐sensitized solar cells, ITO‐TiO₂ core‐shell nanowire arrays were prepared by depositing a 45 nm‐thick mesoporous TiO₂ shell layer consisting of ～6 nm anatase nanoparticles using TiCl₄ treatments. Dye‐sensitized solar cells fabricated using these ITO‐TiO₂ core‐shell nanowire arrays show extremely fast charge collection owing to the shorter electron paths across the 45 nm‐thick TiO₂ shell compared to the 2D TCO. Interestingly, the charge‐collection time does not increase with the overall electrode thickness, which is counterintuitive to conventional diffusion models. This result implies that, in principle, maximum light harvesting can be achieved without hindering the charge collection. The proposed new 3D TCO should also be attractive for other photovoltaic applications where the active layer thickness is limited by poor charge collection.     

光学技术在早期龋齿检测中的应用

介绍了光学技术在口腔医学早期龋齿无损检测领域的应用,包括基于牙齿自体荧光效应的定量光导荧光技术和激光龋齿检测技术;基于光散射效应的数字化显影光纤透照术,以及基于牙釉质双折射效应的偏振敏感光学相干断层术和偏振拉曼光谱技术.详细介绍了各种光学方法应用于龋齿检测的基本原理、实验方案和研究现状,并对不同的光学方法进行比较.最后,提出基于频域荧光寿命成像的早期龋齿检测方法,并对该方案的技术路线进行了介绍.     

高温胁迫对菊花电阻抗图谱参数的影响

以菊花(Chrysanthemum morifolium)‘神马’扦插苗茎段和叶片为材料,测定其高温胁迫(25~50℃)下电阻抗图谱参数的变化,通过膜透性(相对电导率)与电阻抗图谱参数间的相关性,来证明电阻抗图谱法研究菊花耐热性的有效性。结果表明:随着温度升高,茎叶的胞外电阻、胞内电阻、弛豫时间呈现先增加,后急剧下降的趋势,而弛豫时间分布系数变化趋势为不规则下降。茎叶相对电导率是随着温度的升高先增加后降低再急剧增加。经过菊花茎叶电阻抗图谱参数拟合菊花的耐热性与相对电导率表示的耐热性温度极为接近。相关分析表明,高温胁迫下菊花茎叶相对电导率与胞外电阻(茎p<0.01,叶p<0.05)、弛豫时间(p<0.05)之间有显著的相关。由此可见,胞外电阻和弛豫时间是测定菊花耐热性的适合参数。     

Time Domain Analysis of Heart Rate Variability Signals in Valence Recognition for Children with Autism Spectrum Disorder (ASD)

BackgroundAutism Spectrum Disorder (ASD) is a neurodevelopmental condition that is characterized by various social impairments. Children with ASD have major difficulties in expressing themselves, resulting in stress and meltdowns. Understanding their hidden feelings and needs may help in tackling and avoiding such strenuous behaviors.ObjectiveThis research aims to aid the parents and caretakers of children with ASD to understand the hidden and unexpressed emotional state by using physiological signals obtained from wearable devices.MethodsHere, electrocardiogram (ECG) signals pertaining to two valence states (‘like’ and ‘dislike’) were recorded from twenty children (10 Control and 10 children with ASD). The heart rate variability (HRV) signals were then obtained from the ECG signals using the Pan-Tompkins's algorithm. The statistical, higher order statistics (HOS) and geometrical features which were statistically significant were trained using the K Nearest Neighbor (KNN) and Ensemble Classifier algorithms.ResultsThe findings of our analysis indicate that the integration of major statistical features resulted in an overall average accuracy of 84.8% and 75.3% using HRV data for the control and test population, respectively. Similarly, geometrical features resulted in a maximum average accuracy of 84.8% and 74.2% for control and test population respectively. The decreased HRV in the test population indicates the presence of autonomic dysregulation in children with ASD when compared to their control peers.     

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures¹. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.