Internal layers for a quasi--linear singularly perturbed delay differential equation

The current paper is mainly concerned with the internal layers for a quasi--linear singularly perturbed differential equation with time delays. By using the method of boundary layer functions and the theory of contrast structures, the existence of a uniformly valid smooth solution is proved, and the asymptotic expansion is constructed. As an application, a concrete example is presented to demonstrate the effectiveness of our result.     

An inequality model for solving interval dynamic response of structures with uncertain-but-bounded parameters

In this paper, we look into the dynamic response of structures with uncertain-but-bounded parameters. A new inequality model for determining the interval dynamic response is presented. First we propose an interval dynamic response solution theorem. An inequality model which is a mathematics programming problem is suggested by the presented theorem. Using the central difference method, we substitute the differential items of the inequality model by difference items. By solving them, the interval dynamic response can be obtained. Two examples are used to illustrate the feasibility and the efficiency of the model.     

Synthesis and preliminary evaluation of a novel 125I-labeled T140 analog for quantitation of CXCR4 expression

The aim of this study was to develop a radiopharmaceutical for the imaging of CXCR4-expressing tumors in vivo. For ¹²⁵I-labeling, ¹²⁵I-SIB was synthesized and conjugated with the ε-NH₂ group of Ac-TZ14011, a specific CXCR4 antagonist. The specific radioactivity of the product was 5 GBq/μmol and the radiochemical purity (RCP) was 96% (n = 3). After 6 h, the RCP of the product in PBS was 93%. The MCF-7 cell uptake of Ac-TZ14011 was rapid and high. Primary biodistribution studies indicated that ¹²⁵I-IB-Ac-TZ14011 was mainly excreted via the kidney, and further evaluation in mice with induced tumors was necessary.     

Addition of porous cuprous oxide to a Nafion film strongly improves the performance of a nonenzymatic glucose sensor

The direct electrocatalytic oxidation of glucose in alkaline medium at an electrode modified with microcubes of porous cuprous oxide is reported. Compared to the glassy carbon electrode, a substantial increase in the efficiency of the electrocatalytic oxidation of glucose is observed starting at around +0.20 V (vs. Ag/AgCl). The pH dependence of the response was examined by cyclic voltammetry. This non-enzymatic amperometric sensor may be used for non-enzymatic detection of glucose with a high and reproducible sensitivity of 10.95 μA per mM at a potential of +0.40 V, with response times of <3 s, a linear range from 2.0 to 350 μM, and a detection limit of 1.3 μM. The porous microcubes are conveniently prepared, and display high sensitivity and repeatability.     

A fluorescent hydrogen peroxide probe based on a ‘click’ modified coumarin fluorophore

Herein a water-soluble ‘click’ modified coumarin-based fluorescent probe for hydrogen peroxide is reported. This probe shows significant intensity increases (up to fivefold) in near-green fluorescence upon reaction with hydrogen peroxide, and good selectivity over other reactive oxygen species.     

Discrimination of Chinese traditional soy sauces based on their physico-chemical properties

This work aimed to classify the categories (produced by different processes) and brands (obtained from different geographical origins) of Chinese soy sauces. Nine variables of physico-chemical properties (density, pH, dry matter, ashes, electric conductivity, amino nitrogen, salt, viscosity and total acidity) of 53 soy sauce samples were measured. The measured data was submitted to such pattern recognition as cluster analysis (CA), principal component analysis (PCA), discrimination partial least squares (DPLS), linear discrimination analysis (LDA) and K-nearest neighbor (KNN) to evaluate the data patterns and the possibility of differentiating Chinese soy sauces between different categories and brands. Two clusters corresponding to the two categories were obtained, and each cluster was divided into three subsets corresponding to three brands by the CA method. The variables for LDA and KNN were selected by the Fisher F-ratio approach. The prediction ability of all classifiers was evaluated by cross-validation. For the three supervised discrimination analyses, LDA and KNN gave 100% predications according to the sample category and brand.     

Theoretical studies on the electronic structures and spectra of single silicon-doped SWCNTs

The equilibrium geometries and electronic structures of a series of SWCNTs doped with a silicon atom were studied by using density function theory (DFT). The most stable doping site of silicon predicted at B3LYP/6-31G(d,p) level was located near the boundary of the SWCNTs. The energy gaps of (3,3) C₄₈, (3,3) C₆₀ and (3,3) C₇₂ were respectively decreased by 0.43, 0.25 and 0.14 eV after doping. Based on the B3LYP/6-31G(d) optimized geometries, the electronic spectra of the doped SWCNTs were computed using the INDO/CIS method. The first UV absorption at 973.9 nm of (5,5)-Si(L) (C₅₉Si) compared with that at 937.5 nm of (5,5) (C₆₀) was red-shifted. The ¹³C NMR spectra and nuclear independent chemical shifts (NICS) of the doped SWCNTs were investigated at B3LYP/6-31G(d) level. The chemical shift at 119.4 of the carbon atom bonded with the silicon atom in (3,3)-Si(L) (C₅₉Si) in comparison with that at 144.1 of the same carbon atom in (3,3) (C₆₀) moved upfield. The tendency of the aromaticity (NICS = −0.1) for (3,3)-Si(H) (C₄₇Si) with respect to that of the anti-aromaticity (NICS = 6.0) for (3,3) (C₄₈) was predicted.      

Authentication of cassia seeds on the basis of two-wavelength HPLC fingerprinting with the use of chemometrics

<正>High performance liquid chromatographic(HPLC) fingerprints of Cassia seed,a traditional Chinese medicine(TCM),were developed by means of the chromatograms at two wavelengths of 238 and 282 nm.Then,the two data sets were combined into one matrix.The application of principal component analysis(PCA) for this data matrix showed that the samples were clustered into four groups in accordance with the plant sources and preparation procedures.Furthermore,partial least squares(PLS),back propagation artificial neural network(BP-ANN),and radial basis function artificial neural network(RBF-ANN) were effectively applied to predict the category of the four different samples in the test set.     

Penetration of beta-lactoglobulin into monoglyceride monolayers. dynamics, interactions, and topography of mixed films

In this work we have analyzed the penetration of betalactoglobulin into a monoglyceride monolayer (monopalmitin or monoolein) spread at the air-water interface and its effects on the structural, dilatational, and topographical characteristics of mixed films. Dynamic tensiometry, surface film balance, Brewster angle microscopy (BAM), and surface dilatational rheology have been used, maintaining the temperature constant at 20 degrees C and the pH and ionic strength at 7 and 0.05 M, respectively. The initial surface pressure (mN/m) of the spread monoglyceride monolayer (pii(MONOGLYCERIDE)) at 10, 20, and the collapse point is the variable studied. Beta-lactoglobulin can penetrate into a spread monoglyceride monolayer at every surface pressure. The penetration of beta-lactoglobulin into the monoglyceride monolayer with a more condensed structure, at the collapse point of the monoglyceride, requires monoglyceride molecular loss by collapse and/or desorption. However, the structural, topographical, and dilatational characteristics of monoglyceride penetrated by beta-lactoglobulin mixed monolayers are essentially dominated by the presence of monoglyceride (either monopalmitin or monoolein) in the mixed film. In fact, monoglyceride molecules have the capacity to re-enter the monolayer after expansion and recompression of the mixed monolayer. Thus, monoglyceride molecular loss by collapse and/or desorption is reversible. The topography of the monolayer under dynamic conditions corroborates these conclusions.     

A Monte Carlo study of spherical electrical double layer of macroions-polyelectrolytes systems in salt free solutions

A canonical Monte Carlo simulation is performed to investigate the microstructure and the electrical double layer (EDL) of polyelectrolytes around macroions in the bulk systems based on the primitive model. We explore the influences of particles size, chain length, and charge density of polyelectrolytes on the microscopic behavior of the macroions-polyelectrolytes systems. The simulation results show that the surface charge density and the chain length of the polyelectrolytes are two key factors that affect the microstructure of polyelectrolytes around the macroions and potential of mean force between the macroions as well as the zeta potential of the spherical EDL constructed by polyelectrolytes. The high surface charge density of a polyelectrolyte leads to the polyelectrolyte acting as a bridge for the aggregation of macroions, causing the presence of the attraction between macroions. The polyelectrolytes with a long chain length present a cooperativity effect for the adsorption of the polyelectrolytes on the surface of the macroions. Furthermore, the two key factors both induce the overcharge of the macroions. The longer the chain length and the higher surface charge density of the polyelectrolytes, the stronger is the overcharge.