Common path interferometer based on the modified Michelson configuration using a reflective grating

A common-path interferometer using the modified Michelson system with a reflective grating is proposed for quantitative phase imaging. The frequency spectrum of the object beam is split into two beams using a beam splitter. One beam is diffracted into +1, 0, and −1 orders by the reflective grating to act as an object beam, and the other beam is low-filtered and diffracted by a pinhole mirror to act as a reference beam. Three phase-shifted interferograms can be simultaneously captured using the proposed interferometer, and the specimen phase can then be reconstructed from the three interferograms. Experiments are carried out to prove the precision, real-time ability, and stability of the proposed method.     

Novel image encryption algorithm based on cycle shift and chaotic system

In this paper, a novel image encryption algorithm is proposed. The cycle shift in bits of pixels and the chaotic system are employed for the encryption of the proposed scheme. For cycle shift operations, random integers with the same size of the original image are produced to scramble the plaintext image. Moreover, the scrambled image effects the initial values of the chaotic system for the further encryption process, which increases the sensitivity of plaintext images of the scheme. The scrambled image is encrypted into the ciphered image by the keys which are produced by the chaotic system. The simulation experiments and theoretical analyses indicate that the proposed scheme is superior and able to resist exhaustive attack and statistical attack.     

掺杂和结构对光纤中去极化型声波导布里渊散射频移与散射效率的影响

利用全矢量有限元法研究了单模光纤及光子晶体光纤中掺杂材料及浓度、光纤结构对去极化型声波导布里渊散射频移和散射效率的影响.结果表明增大包层掺氟浓度或纤芯掺锗浓度均会减小光纤布里渊频移,也会增大单模光纤散射效率.光子晶体光纤中整体掺氟浓度不变时,空气孔层数的增加会减小布里渊频移;而纤芯掺锗浓度不变时,随空气孔层数的增加TR2,3模式的布里渊频移增大,而TR2,7模式的布里渊频移减小.     

远红外Ge-Te-I高卤硫系玻璃的制备及其光学性能的研究

为获得高质量的远红外硫系玻璃,采用传统的真空熔融淬冷法配合真空低温固化技术制备了高卤素含量的Te硫系玻璃(卤素Imax =40 at.％),并分析了该系列Ge20Te80-xIx(x-10、15、20、25、30、35、40)硫卤玻璃样品.采用分光光度计和傅里叶红外光谱仪等光学仪器分析该玻璃的可见/近红外吸收光谱和红外透射光谱等频谱性质,利用Raman光谱仪和X射线衍射仪分析了玻璃的内部微观结构.研究表明,随着卤素Ⅰ元素的增加,可见/近红外吸收光谱的短波截止边持续发生蓝移,光学带隙持续增大,从近红外的1 μm一直到远红外波长25μm都保持透光性;Ge20Te65I15玻璃的转变温度最大,在138℃附近,其红外透过率最高,达到50％.     

Study of a Mn–Cr/TiO2 mixed oxide nanocatalyst prepared via an inorganic precursor complex for high-temperature water–gas shift reaction

The influence of three preparation methods on the properties and reaction performances of a titania-supported Mn–Cr bimetallic nanocatalyst for high-temperature water–gas shift reaction has been studied. Impregnation, co-precipitation and thermal decomposition of the [Mn(H₂O)₆]₃[Cr(NCS)₆]₂·H₂O/TiO₂ precursor as an inorganic precursor complex were utilized for the preparation of the Mn–Cr/TiO₂ catalysts. The calcined catalyst and the precursor that were used for its preparation were characterized by powder X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller specific surface area measurements, thermal gravimetric analysis, differential scanning calorimetry and Fourier transform–infrared spectroscopy. The high-temperature water–gas shift activity was appraised in the temperature range from 280 to 420 °C. The results showed that thermal decomposition of inorganic precursor complexes is more advantageous than impregnation and co-precipitation methods for the preparation of Mn–Cr/TiO₂ catalysts for high-temperature water–gas shift reaction.     

Model‐based pre‐processing in Raman spectroscopy of biological samples

Model‐based pre‐processing has become wide spread in spectroscopy and is the standard procedure in Fourier‐transform infrared spectroscopy. It has also been shown to give valuable contributions in Raman spectroscopy. Extended multiplicative signal correction is flexible enough to handle varying fluorescence background and take into account individual variations in baselines while still keeping enough rigidity through reference spectra and model fitting to avoid degenerate solutions and overfitting, when used correctly. We demonstrate the basic extended multiplicative signal correction method and some extensions, including a novel shift correction, on real Raman data to demonstrate effects on visual appearance, replicate variation and prediction. Comparisons with other standard correction methods are also shown and discussed. © 2016 The Authors. Journal of Raman Spectroscopy Published by John Wiley & Sons, Ltd.     

Fractional Gamma and Gamma-Subordinated Processes

We introduce and study fractional generalizations of the well-known Gamma process, in the following sense: the corresponding densities are proved to satisfy the same differential equation as the usual Gamma process, but with the shift operator replaced by its fractional version of order ν > 0. In the case ν > 1, the solution corresponds to the density of a Gamma process time-changed by an independent stable subordinator of index 1/ν. For ν less than one an analogous result holds, with the subordinator replaced by the inverse. In this case the fractional Gamma process is proved to be a non-stationary version of the standard one, with power law behavior of the expected value. Hence it can be considered a useful tool in modelling stochastic deterioration in the non-linear cases, a situation which often occurs in real data (see i.e., [42 Van Noortwijk, J.M., 2009. A survey of the application of Gamma processes in maintenance. Reliability Engineering System Safety 94: 2–21.[Crossref], [Web of Science ®] , [Google Scholar]] and the references therein).

As a consequence of the previous results, the fractional generalizations of some Gamma subordinated processes (i.e. the Variance Gamma, the Geometric Stable and the Negative Binomial) are introduced and the corresponding fractional differential equations are obtained. These processes are particularly relevant for a wide range of financial and technological applications.     

NMR Spectroscopy for Protein Higher Order Structure Similarity Assessment in Formulated Drug Products

Peptide and protein drug molecules fold into higher order structures (HOS) in formulation and these folded structures are often critical for drug efficacy and safety. Generic or biosimilar drug products (DPs) need to show similar HOS to the reference product. The solution NMR spectroscopy is a non-invasive, chemically and structurally specific analytical method that is ideal for characterizing protein therapeutics in formulation. However, only limited NMR studies have been performed directly on marketed DPs and questions remain on how to quantitively define similarity. Here, NMR spectra were collected on marketed peptide and protein DPs, including calcitonin-salmon, liraglutide, teriparatide, exenatide, insulin glargine and rituximab. The 1D ¹H spectral pattern readily revealed protein HOS heterogeneity, exchange and oligomerization in the different formulations. Principal component analysis (PCA) applied to two rituximab DPs showed consistent results with the previously demonstrated similarity metrics of Mahalanobis distance (D_M) of 3.3. The 2D ¹H-¹³C HSQC spectral comparison of insulin glargine DPs provided similarity metrics for chemical shift difference (Δδ) and methyl peak profile, i.e., 4 ppb for ¹H, 15 ppb for ¹³C and 98% peaks with equivalent peak height. Finally, 2D ¹H-¹⁵N sofast HMQC was demonstrated as a sensitive method for comparison of small protein HOS. The application of NMR procedures and chemometric analysis on therapeutic proteins offer quantitative similarity assessments of DPs with practically achievable similarity metrics.     

A general method to obtain Sturmian functions for continuum and bound state problems with Coulomb interactions

In this article, we investigate discretization schemes to represent Sturmian functions for both positive and negative energies in the presence of a long range Coulomb potential. We explore two methods to obtain Sturmian functions for positive energy. The first one involves the expansion of the radial wave function in a L² finite basis set, whereas the second one introduces the discretization of the radial coordinate domain of the Hamiltonian or, alternatively, the Green function. We apply them to find the bound states and scattering phase shift for ‐electron atoms close to the critical charge. Both methods are able to describe bound states near threshold, as well as continuum states with very good convergence properties. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Oriented tin on the metal surface obtained by crystallization in magnetic field

¹¹⁹Sn NMR showed that β-tin areas that formed upon freezing at magnetic field 9.4 T on the surface of tin polycrystalline samples have their symmetry axes strongly aligned along a particular direction. The fraction of the oriented frozen tin was found to approach the total amount of the Sn melt on the sample surface.