Feasibility study for the use of near infrared spectroscopy in the qualitative and quantitative analysis of green tea, Camellia sinensis (L.)

This paper indicates the possibility to use near infrared spectroscopy (NIR) combined with PLS as a rapid method to estimate the quality of green tea. NIR is used to build calibration models to predict the content of caffeine, epigallocatechin gallate (EGCG) and epicatechin (EC) and for the prediction of the total antioxidant capacity of green tea. For the determination of the total antioxidant capacity, the trolox equivalent antioxidant capacity (TEAC) method is used. Until now, the prediction of the antioxidant capacity as such by use of NIR has not been reported. For caffeine and TEAC, models are build for the whole green tea leaves and also for the ground leaves. For the polyphenols (EGCG and EC), only models for the whole leaves are investigated. A partial least squares (PLS) algorithm is used to perform the calibration. To decide upon the number of PLS factors included in the PLS model, the model with the lowest root mean square error of cross-validation (RMSECV) for the training set is chosen. The correlation coefficient (r) between the predicted and the reference results for the test set is used as an evaluation parameter for the models: for the TEAC results r=0.90 for the model with the whole leaves, r=0.86 for the model with the powdered leaves are obtained. The caffeine prediction model has a correlation coefficient r=0.96 for the whole leaves and r=0.93 for the ground leaves. The correlation coefficient for the EGCG and the EC content models are, respectively 0.83 and 0.44.     

Oxidation products of the niobium tungsten oxide Nb4W13O47: A high-resolution scanning transmission electron microscopy study

Nb₄W₁₃O₄₇, a member of the solid solution series Nb_8−nW_9+nO₄₇ (0?n?5), crystallizes in a threefold superstructure of the tetragonal tungsten bronze structure. While the oxidation of this reduced phase at T_OX=1200 °C leads to a separation into the thermodynamically stable phases, lower oxidation temperatures result in products that comprise new structural elements and ordering variants. The characterization of the oxidation products obtained at T_OX=1000 °C was performed by scanning transmission electron microscopy applying a high-angle annular dark field detector. At the selected imaging conditions (Z contrast), not only the metal positions are revealed by this technique but valuable additional information about the elemental distribution can be obtained simultaneously.     

纳米分辨率的三维形貌检测仪

从光干涉方式，瞳窗关系和光源带宽等基本关系出发，利用空间不变系统理论解析了相移显微干涉检测系统中衍射效应的影响。为了减小横向分辨率对纵向分辨率的影响，利用相关信息提取或数字滤波的方法，获得了纳米分辨率的三维形貌。     

Fourier transform spectroscopy using image sensors

Multichannel Fourier transform spectrometers utilizing image sensing devices are reviewed along with the instrumental design concepts. Although the idea itself is fairly simple, a photographic plate in holographic spectroscopy is replaced by an image sensor, there are stringent requirements to be satisfied in order to realize the system for field use. Mainly two types of the instrument, which are characterized by the Sagnac common-path interferometer and the polarization interferometer optics, respectively, are described with regard to their system performances. Examples of the system operation introduced show that Fourier transform spectrometers without mechanical moving parts play an important role in a variety of spectroscopic applications under severe surroundings. In a summary, methods for the resolution enhancement and comments on the signal-to-noise ratio are also included.     

Molecular structure and spectral properties of thionaphthalimides

The molecular structure and absorption spectra of monothio- and dithio-naphthalimides were compared to their naphthalimide analogues using AM1, PM3 and ZINDO/S semiempirical quantum chemical methods. The substitution of the 4R-naphthalimide oxygen atoms by sulphur atoms resulted in a red-shift of the absorption spectra by Δλ_max60-65 and 100-140 nm, respectively. The thionated naphthalimide derivatives do not show observable fluorescence due to intersystem crossing to the triplet -states localised at the CS groups. The -absorption bands of monothioimides are located at 525-580 nm (ε=60-80) and those for dithioimides at 535-560 nm (ε=140-390) and 628-686 nm (ε=34-68). None of these transitions are solvent sensitive. The -transitions of N-phenylthioimides have also a small contribution from -states due to a partial conjugation between CS group and π-electronic system of the N-phenyl ring. As a result, the bands of aromatic substituted N-phenylthioimides are red-shifted as compared to those of the aliphatic N-methyl-thioimides.     

LapRLSR for NIR spectral modeling and its application to online monitoring of the column separation of Salvianolate

A novel near infrared (NIR) modeling method—Laplacian regularized least squares regression (LapRLSR) was presented, which can take the advantage of many unlabeled spectra to promote the prediction performance of the model even if there are only few calibration samples. Using LapRLSR modeling, NIR spectral analysis was applied to the online monitoring of the concentration of salvia acid B in the column separation of Salvianolate. The results demonstrated that LapRLSR outperformed partial least squares (PLS) significantly, and NIR online analysis was applicable.     

FTO客体3m闪光照相的Monte Carlo研究

 研究了客体模型FTO的闪光照相系统X光输运过程，给出了直穿照射量、散射照射量、直散比、直穿照射量能谱、散射照射量能谱、直穿X光通量能谱和散射X光通量能谱在记录平面的空间分布。结果表明：后锥是照射量散射成分的主要来源，后锥照射量占总散射量97%；后锥也是造成散射的空间分布不均匀的主要器件，这一不均匀性高达58%。照相系统的最小直散比非常小，表明锥造成的散射已经严重地淹没了直穿（轫致辐射）信号。计算中使用高空间分辨率记录法进行分点，合成图像对吸收系数的复原结果与国外报道的结果相符。     

Digital Interferometric Measurement of Forced Convection Heat Transfer in a Miniature Rectangular Channel

Investigations have been performed on convective heat transfer in water flowing through mini-channels using the non intrusive technique of laser interferometry coupled with digital image processing. Optical glass channels, fabricated with metallic heating surfaces, were studied using a Mach-Zehnder interferometer configuration. Fringe patterns captured using a high-sensitivity CCD camera were analyzed digitally based on a calculation method developed for the liquid medium. Results of parametric studies were compared and contrasted with relevant theoretical solutions from the literature. Indication of the onset of turbulence at Reynolds numbers smaller than the conventional transition Reynolds number for large channels has also been noticed in the experimental investigation.     

一种不同地面分辨率图像的拼接算法

航空遥感监测中变焦镜头的广泛应用以及飞行高度的变化会获得不同地面分辨率的航空影像,因此为了实时监控到飞行区域的整体情况,需要对不同地面分辨率的图像进行拼接。提出了针对不同地面分辨率图像进行拼接的方法。首先用四分法对图像进行分割,检测变化倍率,选择配准策略;然后用基于加速鲁棒性特征(Speeded-Up Robust Features,SURF)的算法对相邻图像进行拼接。获得了焦距变化从高倍过渡到低倍,或从低倍过渡到高倍的拼接图像。通过航空变焦模拟影像的拼接实验和地面变焦影像的拼接实验表明,该方法能够对不同地面分辨率的图像进行拼接,且拼接结果均以高分辨率为基准。     

Comment on “On the Neumann function and the method of images in spherical and ellipsoidal geometry”

In this note, we point out two errors in the article “On the Neumann function and the method of images in spherical and ellipsoidal geometry” by Dassios and Sten. Two corrections are then proposed.