Synthesis,Structure and Near-infrared Luminescence of a Dinuclear Ytterbium（Ⅲ） Complex with a Bis（2,2＇-bipyridyl） Ligand

The title complex {Yb（hfac）3}2（bpyC≡CC6H4C≡Cbpy） （hfac = hexafluoroacetyl- acetonate,bpyC≡CC6H4C≡Cbpy=2-（pyridin-2-yl）-5-（2-（4-（2-（6-（pyridin-2-yl）pyridin-3-yl）ethynyl）- phenyl）ethynyl）pyridine） has been prepared and characterized by X-ray crystallography. It crystallizes in the monoclinic space group P21/c with a = 17.240（16）, b = 25.64（2）, c = 16.481（15）A, β = 93.469（9）°, V = 7271（12）A^3, Z = 4, Mr = 2022.91, F（000） = 3888, Dc = 1.848 g/cm^3 and μ（MoKα） = 2.708 mm^-1. The structure was refined to R = 0.0714 and wR = 0.1762 for 9771 observed reflections （I 〉 2σ（I））. Sensitized near-infrared （NIR） luminescence from YbIII centers was achieved through efficient antenna effect or energy transfer from the bridging ligand chromophore.     

Partitioned partial least squares regression with application to a batch fermentation process

The performance of Partial Least Squares regression (PLS) in predicting the output with multivariate cross‐ and autocorrelated data is studied. With many correlated predictors of varying importance PLS does not always predict well and we propose a modified algorithm, Partitioned Partial Least Squares (PPLS). In PPLS the predictors are partitioned into smaller subgroups and the important subgroups with high prediction power are identified. Finally, regular PLS analysis using only those subgroups is performed. The proposed Partitioned PLS (PPLS) algorithm is used in the analysis of data from a real pharmaceutical batch fermentation process for which the process variables follow certain profiles during a specific fermentation period. We observed that PPLS leads to a more accurate prediction of the yield of the fermentation process and an easier interpretation, since fewer predictors are used in the final PLS prediction. In the application important issues such as alignment of the profiles from one batch to another and standardization of the predictors are also addressed. For instance, in PPLS noise magnification due to standardization does not seem to create problems as it might in regular PLS. Finally, PPLS is compared to several recently proposed functional PLS and PCR methods and a genetic algorithm for variable selection. More specifically for a couple of publicly available data sets with near infrared spectra it is shown that overall PPLS has lower cross‐validated error than PLS, PCR and the functional modifications hereof, and is similar in performance to a more complex genetic algorithm. Copyright © 2011 John Wiley & Sons, Ltd.     

Long-lasting near-infrared persistent luminescence from β-Ga2O3:Cr nanowire assemblies

Near-infrared (NIR) persistent luminescent β-Ga₂O₃:Cr³⁺ nanowire assemblies were synthesized by a hydrothermal process followed by calcination. The phosphor exhibits more than 4 h afterglow in the wavelength range of 650-850 nm after ceasing the ultraviolet light (280-360 nm) irradiation. The trap structure and persistent luminescence mechanism were revealed by thermoluminescence measurement. The β-Ga₂O₃:Cr³⁺ nanowire assemblies may find applications as identification taggants in security and optical probes in bio-imaging.     

近红外光谱法预测粗皮桉木材气干密度的影响因素分析

采用近红外光谱分析技术,对粗皮桉木材气干密度校正模型的影响因素进行比较研究.使用直接测量法测量了粗皮桉木材的气干密度,并用近红外光谱仪采集试样的近红外漫反射光谱,对不同切面、厚度、含水率和粗糙度的粗皮桉木材试样的原始光谱进行二阶导数预处理并选择一定光谱段建立回归模型.以50～140个试样作为校正集建立木材气干密度的偏最...     

NIR and UV-vis spectroscopy, artificial nose and tongue: Comparison of four fingerprinting techniques for the characterisation of Italian red wines

Four rapid and low-cost vanguard analytical systems (NIR and UV-vis spectroscopy, a headspace-mass based artificial nose and a voltammetric artificial tongue), together with chemometric pattern recognition techniques, were applied and compared in addressing a food authentication problem: the distinction between wine samples from the same Italian oenological region, according to the grape variety.Specifically, 59 certified samples belonging to the Barbera d’Alba and Dolcetto d’Alba appellations and collected from the same vintage (2007) were analysed.The instrumental responses, after proper data pre-processing, were used as fingerprints of the characteristics of the samples: the results from principal component analysis and linear discriminant analysis were discussed, comparing the capability of the four analytical strategies in addressing the problem studied.     

Optical characterization of polycarbonate: Influence of additives on optical properties

In laser transmission welding of thermoplastics the optical properties of the joining parts determine the quality of the welding result. Especially, the scattering of laser radiation in the transparent welding part has an impact on weld seam properties. This scattering is caused by additives. For polycarbonate (PC) with different additives the transmittance, the reflectance and the collimated transmittance are measured with a UV‐VIS‐NIR spectrometer. From this data, the optical properties, such as scattering coefficient, absorption coefficient, and anisotropy factor are calculated. The calculations are made with the aid of the four‐flux model of radiation transport in the diffusive approximation. The results show that the additives have a significant influence on the scattering coefficient. For most additives under consideration the scattering is forward directed, which means that most of the radiation is transmitted into the absorbing welding part. However, the power density distribution of the transmitted radiation may differ significantly from PC without additives. So, the weld seam may also differ due to different additives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 451–455, 2010     

Instrumental Requirements for Non-Invasive Blood Glucose Measurement Using NIR Spectroscopy

The magnitude of spectral change in blood glucose measurements with diffuse reflectance spectroscopy is investigated. Spectral change is estimated by simulation of light propagation in skin tissue and measurements of absorbance spectra of aqueous glucose solution. Required sensitivity of spectrophotometers for monitoring change in the blood glucose concentration as small as 10 mg/dL has been obtained using the estimated change in the absorbance spectrum and mean pathlength of light in tissue.     

An empirical study of PLAD regression using the bootstrap

Partial LAD regression uses the L ₁ norm associated with least absolute deviations (LAD) regression while retaining the same algorithmic structure of univariate partial least squares (PLS) regression. We use the bootstrap in order to assess the partial LAD regression model performance and to make comparisons to PLS regression. We use a variety of examples coming from NIR experiments as well as two sets of experimental data.     

NIR FT－Raman研究铝酸钠溶液的碳酸化过程

本文用ＮＩＲＦＴ－Ｒａｍａｎ光谱仪原位跟踪了铅酸钠溶液的碳酸化过程，观察到此过程的Ｒａｍａｎ光谱呈现振荡现象和非重线性，认为在碳酸化过程中，可能产生Ａｌ２（ＯＨ）离子和进一步缩聚形成的离子。