Determination potentiometrique des constantes de stabilite des complexes entre l'argent(I) et quelques heterocycles azotes en milieu neutre et acide dans le carbonate de propylene

The formation of AgL⁺_n (n = 1–4) (L = pyridine), AgL′⁺ and AgL′₂⁺ [L′ = 2,2′ bipyridine, 2,2′ biquinoline, 2-(2-pyridyl)benzimidazole] complexes has been studied using potentiometry with a silver electrode. The acidity constants of the ligands have been measured potentiometrically with the hydrogen electrode. The silver distribution between the Ag⁺ and AgL_n⁺ species has been computed by means of the so obtained β_n. In acidic medium, the metallic complexes are destroyed by the ligand protonation.     

Determining the Liquid-Crystal Polar Anchoring at High Electric Fields by Heterodyne Interferometer

A common-path heterodyne interferometer is proposed to determine the surface anchoring energy of a homogeneously aligned nematic liquid crystal (LC). This technique measures, with high sensitivity, the phase retardation of a nematic LC cell as a function of the applied voltage. According to the measured voltage-dependent phase retardation of the LC cells, a simple linear fitting over a well-specified voltage window can be achieved, leading to a precise determination of the polar anchoring energy. The anchoring energy , cell gap, and pretilt angle can be simultaneously obtained in the course of the same experiment.     

Characterization of DOM as a function of MW by fluorescence EEM and HPLC-SEC using UVA,DOC, and fluorescence detection

To investigate the composition of dissolved organic matter (DOM) as a function of apparent molecular weight (MW) by rapid analytical methods, high performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) was conducted with sequential on-line detectors consisting of UV, fluorescence, and quantitative DOC measurement. Fluorescence excitation-emission matrix (EEM) spectrophotometry was used to select wavelengths for the HPSEC on-line fluorescence system. The chosen peak maxima locations of excitation-emission wavelengths were 278-353 nm for protein-like substances and 337-423 nm for fulvic-like substances based on an analysis of EEM spectra for various samples and reference materials. This system provides quantitative and qualitative information on the specific MW components of DOM, including proportion of DOC (by DOC measurement), aromaticity (by comparison of UV and DOC measurements), and chemical properties (by fluorescence measurement). It further allows determination of organic matter characteristics (e.g., fulvic-like, protein-like, and polysaccharide-like substances) as a function of MW. Three types of samples (Irvine Ranch ground water (IRWD-GW), Barr Lake surface water (BL-SW), and Hawaii wastewater secondary effluent) were analyzed by the HPSEC-UVA-fluorescence-DOC system. These results were compared with fluorescence EEM for samples fractionated by HPLC-SEC. The DOM fraction in the high apparent MW range (over 10,000g/mol) consisted of polysaccharide-like substances for IRWD-GW and a mixture of polysaccharide-like/protein-like substances for BL-SW and wastewater secondary effluent. Minimal amounts of fulvic-like substances were found in the wastewater secondary effluent sample. The DOM fractions in a medium apparent MW range (5000-1000 g/M) showed higher aromaticity (fulvic in character) than any other fractions for all samples. For the DOM fraction in the low apparent MW range (below 680 g/M), additional aliphatic organic matter was found in IRWD-GW, while BL-SW contained protein-like processes. DOM plays an important role in drinking water and wastewater treatment processes. An enhanced HPSEC technique with multiple on-line detectors enables a better understanding of quantitative and qualitative DOM properties and can help to design and optimize water/wastewater treatment facilities.     

Fatigue crack initiation and multiplication of unnotched titanium matrix composites

Fatigue crack initiation and multiplication of the unnotched SCS-6 silicon carbide fiber-reinforced titanium matrix composites with different matrix and interfacial properties have been investigated experimentally and analytically. Ti–15V–3Al, Ti–6Al–4V, and Ti–22Al–23Nb were chosen as matrix materials. The initiation and propagation of each individual matrix crack as a function of fatigue cycles and applied stress levels were carefully monitored. The statistical distribution of crack growth rates in each composite has been constructed and analyzed. The evolution of normalized matrix crack density and stiffness reduction of these composites under fatigue loading also has been characterized. A modified shear-lag model, coupled with the strain-life equation and a fiber bridging model were used to predict the fatigue crack initiation life, matrix crack growth rate, normalized matrix crack density, and residual stiffness of the composites. The predicted fatigue properties correlated well with experimental results.     

Dopamine-Modified Zero-Valent Iron Nanoparticles for Dual-Modality Photothermal and Photodynamic Breast Cancer Therapy

Phototherapy has the advantages of minimal invasion, few side effects, and improved accuracy for cancer therapy. The application of a polydopamine (PDA)-modified nano zero-valent iron (nZVI@PDA) as a new synergistic agent in combination with photodynamic/photothermal (PD/PT) therapy to kill cancer cells is discussed here. The nZVI@PDA offered high light-to-heat conversion and ROS generation efficiency under near-infrared (NIR) irradiation (808 nm), thus leading to irreversible damage to nZVI@PDA-treated MCF-7 cells at low concentration, without inducing apoptosis in normal cells. Irradiation of nZVI@PDA using an NIR laser converted the energy of the photons to heat and ROS. Our results showed that modification of the PDA on the surface of nZVI can improve the biocompatibility of the nZVI@PDA. This work integrated the PD and PT effects into a single nanodevice to afford a highly efficient cancer treatment. Meanwhile, nZVI@PDA, which combines the advantages of PDA and nZVI, displayed excellent biocompatibility and tumoricidal ability, thus suggesting its huge potential for future clinical research in cancer therapy.     

Development of a multiplexed interface for capillary electrophoresis-electrospray ion trap mass spectrometry

A four-channel multiplexed electrospray capillary electrophoresis interface has been developed. This new interface permits up to four capillary electrophoresis columns to be sampled sequentially by means of a stepper motor and a notched rotating plate assembly, which at any instant occludes all but a single sprayer. In this design, four sheath liquid electrospray probes are oriented in a circular array situated 90 degrees relative to one another. The rotating metal disk, which contains a one-quarter notch, is mounted to the stepper motor assembly and is located between the sprayers and the entrance aperture of an ion trap mass spectrometer. By using the data acquisition signal from the ion trap mass spectrometer, the scan event is synchronized with the rotation of the metal disk. With this device, four discrete sample streams can be simultaneously analyzed, resulting in a 4-fold increase in analytical throughput.     

Analytical and experimental study on the spiral marks of the rolled product during three-roll planetary rolling processes

In this study, the effects of various rolling conditions, such as inclined angle, offset angle, roll shapes, etc., upon the depth of the spiral marks on the surface of the rolled product and the rolling forces are discussed numerically by the finite element method. Experiments using a self-designed testing machine with work-rolls of three different kinds of roll shapes were conducted. The depth of the spiral marks was measured. From the comparisons between the analytical and experimental results, it is known that a smoother surface on the rolled product can always be obtained with convex-shaped rolls. Whereas, prominent spiral marks probably appear for two-stage conical rolls and spherical-headed rolls under an ill-set rolling condition. These analytical and experimental results can offer useful knowledge for the design of the roll shapes and the pass schedule during three-roll planetary rolling processes.     

Crystalline quality and photovoltaic performance of InGaAs solar cells grown on GaAs substrate with large-misoriented angle

This article reports the quality of In_xGa_1−xAs (0 < x < 0.2) layers grown on 15°-off GaAs substrate by metalorganic chemical vapor deposition. The crystalline quality of the In_xGa_1−xAs epilayers is determined by x-ray reciprocal space mapping (RSM). From the RSM results, the crystalline quality of In_xGa_1−xAs epilayers grown with small indium composition (x < 0.11) is better than that of large indium composition (x > 0.11) due to the small strain relaxation. The crystalline quality of In_xGa_1−xAs epilayer is found to strongly depend on indium content. The photovoltaic performance of p-n structure In_0.16Ga_0.84As solar cell shows the lower device performance, because the In_xGa_1−xAs films grown on 15°-off GaAs substrate show a large strain relaxation in the active layer of solar cell. It results in dislocation defects created at the initial active layer/In_xGa_1−xAs graded layer interface. The performance of In_0.16Ga_0.84As solar cell with p-n structure can be significantly improved by the p-i-n structure.     

A Rapid Colorimetric Sensor for Soluble Interleukin-2 Receptor α, Based on Aptamer-Adsorbed AuNP

The soluble interleukin-2 receptor α (sIL-2Rα) is a broad indicator of clinical disease activity in various inflammatory diseases. Here we have developed, for the first time, a rapid, washing-free colorimetric aptasensor based on a sIL-2Rα aptamer (K_d=1.33 nm ). The aptasensor was fabricated with Au nanoparticles (AuNPs) adsorbing sIL-2Rα aptamers. On addition of sIL-2Rα, the aptamers become desorbed from the AuNPs, and this in turn weakens the absorption corresponding to AuNP-catalyzed oxidation of ortho-phenylenediamine (oPD) with H₂O₂. The aptasensor was characterized by TEM imaging, ζ potential measurements, dynamic light scattering (DLS) analysis, and UV/Vis spectrometry, followed by further optimization. The fabricated sensor exhibited great analytical performance, with a linear range of 1 to 100 nm and a detection limit of 1 nm both in buffer and in spiked human serum within 25 min. Other proteins, such as bovine serum albumin (BSA), IL-17Rα, IL-5Rα, IL-13Rα₂, and CD166, showed negligible effects on the aptasensor. Thanks to the great advantages of the aptamers and AuNPs, this aptasensor provides a rapid, simple, and inexpensive process that might offer insights into various diagnostic applications of sIL-2Rα.     

An anonymous buyer‐reseller watermarking protocol

Abstract

In (Memon and Wong, 2001), Memon and Wong first proposed a buyer‐seller watermarking protocol. Inspired by (Memon and Wong, 2001), Cheung and Curreem recently proposed a buyer‐reseller watermarking protocol to address the digital contents redistribution in the second‐hand markets over the Internet (Cheung and Curreem, 2002). In this paper, we show that their watermarking protocol is vulnerable to malicious attacks and propose a simple improvement. The main contribution is that we extend their schemes to enable anonymous transactions among a buyer, a reseller, and a seller in order to further protect the privacy of the buyers.