Non-invasive glucose sensing with near-infrared spectroscopy enhanced by optical measurement conditions reproduction technique

Non-invasive glucose sensing utilizing near-infrared spectroscopy (NIRS) has been a focusing topic in biomedical optics applications. However, different probing locations and contact pressures between the probe and skin cause variations in the light propagation paths within tissue, making it very hard to obtain stable near-infrared spectra concerning body content. This paper proposes one possible solution to the reproduction of light propagation within tissue for near-infrared non-invasive glucose sensing systems by introducing the optical measurement conditions reproduction technique. Results of experiments on glucose concentrations within human body through application of our proposed system show a RMSEP value of 15–20 mg/dL and a correlation coefficient greater than 0.8.     

基于可调谐半导体激光吸收光谱的瓦斯监测方法研究

瓦斯爆炸是煤矿安全的主要威胁,对瓦斯气体浓度进行准确、快速、实时监测和预警是治理瓦斯灾害的有效手段。实验研究了近红外半导体激光吸收光谱技术在煤矿瓦斯气体安全检测中的应用。系统光源采用的是1.65μm波长的近红外可调谐DFB激光器,使用了波长调制和二次谐波检测技术,通过光纤进行信号传输。系统检测限低于0.09%,气体浓度的检测速度最高可达到0.02s。研究表明:该技术具有实时、连续、快速、非接触检测的特点;现场无带电部件,具有多点分布式遥测的能力,能够满足煤矿瓦斯安全检测的要求。     

偏稳健M回归在人体血糖浓度近红外无创检测中的应用

采用偏稳健M回归方法有效地解决了人体血糖浓度近红外无创检测研究过程中由于样本奇异值影响模型稳健性的问题。该方法源于现有的迭代变权偏最小二乘法,计算快、易于实现,具有M估计的所有性质,且当权函数选择合适时,能降低奇异值的影响,建立具有稳健性的校正模型。采用该方法对近红外光谱实验数据进行了处理,并与传统的偏最小二乘(partialleast squares,PLS)建模方法进行了比较。结果表明,与PLS相比,该方法可建立稳健的校正模型提高预测精度,更适合复杂样品建模,对于人体血糖浓度近红外无创检测的进一步研究具有应用价值。     

血糖检测中建模方法和温度引入的偶然相关研究

近红外光谱分析技术应用在血糖检测中,需要借助化学计量学方法建立模型来实现对未知样品的定量分析。在模型建立和验证的过程中通常会引入一定程度的偶然相关,从而影响模型的稳健性。采用随机数模拟光谱数据及参考浓度的研究方式,从建模波长数的选择和交互验证方法两方面考察了不同建模方法在建模的过程中存在偶然相关的概率水平,并给出了最佳的建模波长数以及最优的交互验证方法,以降低引入的偶然相关。此外通过离体实验,研究温度对葡萄糖浓度检测的影响并指导如何在实际血糖检测中降低温度引入的偶然相关。     

血浆中葡萄糖浓度的近红外光谱测量和分析

糖尿病是目前较为普遍的一种内分泌疾病。血糖的无创监测是世界各国研究和开发的一个热点。用近红外光谱技术对血浆进行了浓度分析。利用近红外光谱透射测量血糖浓度的吸光度变化,选择包含有葡萄糖特征峰的谱段建立校正模型,所建立的模型应使误差最小和相关系数最大。采用基线校正和曲线平滑的方法对光谱曲线作预处理,滤除噪声,突出有用信息。用偏最小二乘法(PLS)建立回归模型。对血浆中血糖浓度的实际值和计算值做了比较。     

毒死蜱乳油中敌敌畏违禁添加的红外快速测定

分别采用中红外衰减全反射技术和近红外光谱分析透射技术对毒死蜱乳油中违禁添加的敌敌畏乳油含量进行了快速定量测定。利用偏最小二乘法(partial least squares,PLS)建立敌敌畏的定量模型并进行优化,再分别用独立检验集和不同批次考核样本对模型适应性进行评价。结果表明,中红外和近红外光谱分析技术均可以准确测定毒死蜱乳油中敌敌畏的含量。中红外校正集标准差(RMSEC)为0.013,近红外为0.020,模型测定系数(R2)二者均为1.000。对于考核样品,近红外模型适用性更好,不需要进行模型修正,预测标准差(RMSEP)为0.09;中红外模型需要进行修正,修正后预测标准差(RMSEP)为0.03。红外光谱分析技术因前处理方法简单,测量迅速、方便,对于监督部门进行农药质量控制具有重要意义。     

Low-field nuclear magnetic resonance spectrometer for non-invasive monitoring of fluctuations in blood glucose in the human finger

A low-field nuclear magnetic resonance spectrometer for non-invasive monitoring of human finger blood glucose fluctuations was developed. Saline solution and blood serum samples with different glucose concentrations were first detected by the spectrometer and it has been found that there was a high-linear correlation between the glucose concentration and the transverse relaxation time. Then, the spectrometer was employed to noninvasively measure a finger from each of the several volunteers. The experiment results showed that the transverse relaxation time of the human finger increases with human blood glucose concentration. In conclusion, the human finger nuclear magnetic resonance spectrometer could be a potential tool to noninvasive monitoring of human body’s blood glucose fluctuations in the future.     

中红外无创血糖测量中光程变化对PLSR模型的影响研究

在测量人体皮肤中红外光谱的过程中,皮肤与ATR晶体之间的接触面积很难保持一致,导致倏逝波与人体皮肤的作用光程会产生差异。以光程变化信息与葡萄糖浓度信息之间的相关性为基础,建立了两个分析葡萄糖含量的偏最小二乘回归(PLSR)模型,RMSECV分别为31.3和4.52mg.dL-1;RMSEP分别为30.3和98.7mg.dL-1。结果表明,当光程变化信息与葡萄糖浓度信息之间偶然相关时,所建PLSR模型的预测精度与稳健性会受到不同程度的影响,随着二者之间相关性的增强,最优模型对葡萄糖信息的识别能力越来越弱。为提高中红外无创血糖测量分析结果的可靠性,避免获得伪优定标模型提供了实验依据。     

Application of transcutaneous diffuse reflectance spectroscopy in the measurement of blood glucose concentration

In this paper, the propagation characteristics of near-infrared (NIR) light in the palm tissue are analyzed,and the principle and feasibility of using transcutaneous diffuse reflectance spectroscopy for non-invasive blood glucose detection are presented. An optical probe suitable for measuring the diffuse reflectance spectrum of human palm and a non-invasive blood glucose detection system using NIR spectroscopy are designed. Based on this system, oral glucose tolerance tests are performed to measure the blood glucose concentrations of two young healthy volunteers. The partial least square calibration model is then constructed by all individual experimental data. The final result shows that correlation coefficients of the two experiments between the predicted blood glucose concentrations and the reference blood glucose concentrations are 0.9870 and 0.9854, respectively. The root mean square errors of prediction of full cross validation are 0.54 and 0.52 mmol/1, respectively.     

Rapid quantitative detection of mineral oil contamination in vegetable oil by near-infrared spectroscopy

This study provides a rapid method for quantification of mineral oil in rapeseed oil using near-infrared spectroscopy.The data were processed by direct orthogonal signal correction(DOSC),successive projections algorithm(SPA),partial least squares,and principal component regression(PCR).Good correlation coefficients(R) of 0.998 and root-mean-squared error(RMSE) of 0.005 were obtained,and the DOSC-SPA-PCR model was identified as the optimal method.A satisfactory accuracy with R and RMSE of prediction by DOSC-SPA-PCR of 0.990 and 0.006,was obtained.The results demonstrate that the proposed methodology is a promising method for the rapid quantitative detection of mineral oil in vegetable oil.     

血清中胆固醇的近红外光谱测量及模型适用性研究

使用近红外光谱分析方法进行了血清中胆固醇含量的快速、无试剂测最研究,并考察、分析了模型的适用性.利用傅里叶光谱仪测量1,2和6.5mm 厚血清的近红外光谱,在合频与第一、第二倍频波段内,结合偏最小二乘方法(PLS)对胆固醇建立了模型.1,2,6.5mm 厚血清模型的预测标准差(RMSEP)分别是0.15,0.16,0....     

近红外反射光谱快速测定玉米DDGS营养成分的研究

试验探讨了近红外反射光谱测定玉米DDGS的8项重要营养成分,包括水分、蛋白、粗脂肪、粗灰分、总磷、中性洗涤纤维、酸性洗涤纤维、粗纤维的可行性.从国内18个工厂采集93个玉米DDGS样品,使用偏最小二乘法,采取15种不同的导数和去散射光谱预处理方法建立近红外模型.在光谱预处理中,二阶导数产生了较好的预测效果.使用70个与...     

Dynamic Jahn-Teller effects in isolated C60- studied by near-infrared spectroscopy in a storage ring

We have measured the near-infrared absorption spectrum for isolated C60- ions at room temperature. Two bands, at 9145 cm(-1) and 10460 cm(-1), have been identified in addition to the main absorption band at 9382 cm(-1), seen also at low temperature in a matrix. An interpretation based on the theory of dynamic Jahn-Teller effects is proposed.     

Rapid determination of ethyl pentanoate in liquor using Fourier transform near-infrared spectroscopy coupled with chemometrics

ABSTRACT

The feasibility of Fourier transform near-infrared spectroscopy for rapid determination of ethyl pentanoate in Chinese liquor was investigated. A total of 108 liquor samples from production line were analyzed with Fourier transform near-infrared transmission spectroscopy. The calibration model for ethyl pentanoate content prediction was established with partial least square, and validated using internal cross validation. In a calibration set (80 samples), the coefficient of determination was 0.958, with the corresponding root mean square error of cross validation 0.020 g L^?1. In a validation set (28 samples), the coefficient of determination was 0.964, with the root mean square errors of prediction 0.023 g L^?1, and the bias value (0.005 g L^?1) for the validation set was less than the bias confidence limits value (0.009 g L^?1), indicating that the resulting near-infrared spectroscopy prediction model has good performance for online rapid determination of ethyl pentanoate in Chinese liquor. The determination of ethyl pentanoate in liquor can be completed in less than 2 min per sample using the near-infrared spectroscopy prediction model. The near-infrared spectroscopy combining chemometrics as a rapid analytical method has a promising application prospect of application in the liquor production field.     

Intensities and shapes of H2O lines in the near-infrared by tunable diode laser spectroscopy

The integrated intensities, self- and air-broadening coefficients of thirteen transitions of H₂¹⁶O in the 11980–12260 cm^?1 region, belonging to the 2ν₁+ν₂+ν₃ band, were measured. Using a tunable diode laser system, spectra were recorded at room temperature for a wide range of pressure (2–15 Torr for pure H₂O and 50–760 Torr for H₂O in air). Line parameters were adjusted from experiments using three line-shape models: the Voigt profile (VP), the (hard collision) Rautian profile (RP) and the speed dependent Voigt profile (SDVP). The results show that the RP and SDVP are in better agreement with measurements than the VP and that they lead to larger values of the line parameters (about 5% for the line broadening, and 0.8% for the line intensity). Comparisons of the present results with HITRAN 2008 [Rothman et al., JQSRT 2009, 110:533-72] show that the HITRAN intensities of the studied lines are overestimated by about 9.4%, suggesting a more complete study of the H₂O line parameters in the considered region. The Dicke narrowing and speed dependence parameters deduced from this work are also presented and discussed, demonstrating the need for a more refined line-shape model.     

Effect of decreasing glucose concentration in blood plasma after blood saturation with oxygen

It was experimentally detected that the glucose concentration in blood plasma decreases after venous blood saturation with oxygen (oxygenation process). This effect was recorded for several tens of donor blood samples using IME-DC (Germany) and Optium Omega (USA) portable glucometers, as well as an optical method using holographic sensors based on hydrogel polymer films, independent of the presence of oxygen in plasma. During blood oxygenation in the organism, glucose is redistributed between blood plasma and erythrocyte cytoplasm in favor of cytoplasm. The observed effect is explained by an increase in the electric field during blood oxygenation in lipids of the erythrocyte cytoplasmic membrane, which orients dipoles of asymmetric glucose molecules along the normal to the membrane surface. This results in erythrocytemembrane permeability asymmetry.     

Einstein's theory of the gravitational field in a representation by orthogonal reference systems

Some difficulties in the theory of the gravitational field are discussed; these are associated with the nonlocalized field energy. Orthogonal reference systems are used to formulate the energy and momentum distribution in terms of generally covariant tensors.The authors are indebted to Professor D. D. Ivanenko for an interesting discussion of these problems.     

铝合金中铬元素的时间分辨激光诱导击穿光谱高灵敏检测

为了消除在激光诱导击穿光谱(LIBS)信号检测时等离子体中强的轫致电子辐射对光电倍增管和前置信号放大器造成的不良影响,提高信号检测灵敏度,设计了一种基于CR110的门控端窗光电倍增管并用于LIBS中的微弱信号检测。该门控光电倍增管与前置信号放大器组合运用既可以成功抑制激光等离子体中强的轫致电子辐射的背景干扰,又可以进一步放大微弱的原子辐射信号,提高光谱分析的灵敏度。用LIBS分析铝合金标样中的微量铬元素,采用该门控光电倍增管时其检出限可以达到5.55 ppm,与采用普通光电倍增管的相比改善了近6倍,显示出该门控光电倍增管在时间分辨信号检测领域良好的应用效果。