Antimicrobial activity of new carboxymethyl chitosan–carbon nanotube biocomposites and their swell ability in different pH media

New carboxymethyl chitosan–carbon nanotube (CMCS-CNT) biocomposites were prepared and characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and normal photography. The recorded images of the CMCS-CNT biocomposites showed homogeneous distribution of carbon nanotubes into the carboxymethyl chitosan (CMCS) matrix. Their antimicrobial activity and swell ability in different pH media have been investigated. They showed a higher antimicrobial activity against tested gram-positive and gram-negative bacteria. The inhibition zone diameters are closer to that recorded for the commonly used antibiotics. They showed an increase in the swell ability in different pH media relative to the parent CMCS. It would be expected that these nanobiocomposites are promising candidates for medical applications.     

Nano emulsion binders for paper coating synthesis and application

The key objectives of coating papers and paperboards are to improve their aesthetic appearance and printability. Coatings offer smoothness, gloss, brightness, and opacity to the base papers and provide them with enhanced printability, which requires resistance to ink splitting forces, smoothness, ink holdout and gloss, etc. Styrene acrylate latexes were synthesized, via emulsion polymerization, and were formulated as coats for white and brown recycled papers. Both processes were characterized specifically for offset printing. The prepared latexes showed enhanced solid content, viscosity, zeta potential and appropriate glass transition temperature for paper coating formulation. The porosity, gloss and Cobb60 values of coated papers increased with the increased addition of nano-emulsion modified latexes. The formulations afforded high printability (print gloss and print density) with local ground calcium carbonate compared with that of the imported pigment (kaolin). Furthermore, the synthesized binder had higher water resistance than the commercial one; which can tightly be correlated with print quality, printability and productivity and most significantly, permits usage of low viscous ink. Coated recycled brown base gave promising results with respect to print quality although offset printing was utilized. The novelty of this work was not only in employing the local alternative binder and local pigment but also in achieving compatibility with environmental regulations since oil-based inks and recycled papers were also used.     

On Multiobjective Oligopoly

Multiobjective oligopoly models are constructed. The objectives of the first two models are to maximize profits and to maximize sales. In the third model the objectives are to maximize profits and to minimize risk. Giving more weight to risk minimization decreased the profits. In all three models, we found that the weight of profit maximization has to be higher than a given threshold. Again they require that the weight of profit maximization has to be higher than a certain value.     

Temperature dependent viscosity and thermal conductivity effects on combined heat and mass transfer in MHD three-dimensional flow over a stretching surface with Ohmic heating

An analysis has been carried out to obtain the flow, heat and mass transfer characteristics of a viscous electrically conducting fluid having temperature dependent viscosity and thermal conductivity past a continuously stretching surface, taking into account the effect of Ohmic heating. The flow is subjected to a uniform transverse magnetic field normal to the plate. The resulting governing three-dimensional equations are transformed using suitable three-dimensional transformations and then solved numerically by using fifth order Runge–Kutta–Fehlberg scheme with a modified version of the Newton–Raphson shooting method. Favorable comparisons with previously published work are obtained. The effects of the various parameters such as magnetic parameter M, the viscosity/temperature parameter θ _r , the thermal conductivity parameter S and the Eckert number Ec on the velocity, temperature, and concentration profiles, as well as the local skin-friction coefficient, local Nusselt number, and the local Sherwood number are presented graphically and in tabulated form.     

Investigating effects of sample pretreatment on protein stability using size‐exclusion chromatography and high‐resolution continuum source atomic absorption spectrometry

In this study, size‐exclusion chromatography and high‐resolution atomic absorption spectrometry methods have been developed and evaluated to test the stability of proteins during sample pretreatment. This especially includes different storage conditions but also adsorption before or even during the chromatographic process. For the development of the size exclusion method, a Biosep S3000 5 μm column was used for investigating a series of representative model proteins, namely bovine serum albumin, ovalbumin, monoclonal immunoglobulin G antibody, and myoglobin. Ambient temperature storage was found to be harmful to all model proteins, whereas short‐term storage up to 14 days could be done in an ordinary refrigerator. Freezing the protein solutions was always complicated and had to be evaluated for each protein in the corresponding solvent. To keep the proteins in their native state a gentle freezing temperature should be chosen, hence liquid nitrogen should be avoided. Furthermore, a high‐resolution continuum source atomic absorption spectrometry method was developed to observe the adsorption of proteins on container material and chromatographic columns. Adsorption to any container led to a sample loss and lowered the recovery rates. During the pretreatment and high‐performance size‐exclusion chromatography, adsorption caused sample losses of up to 33%.     

Adsorptive and affinity linear sweep voltammetry for the determination of singulair in tablets and its interaction with human serum albumin

A new simple, sensitive and reliable adsorptive and affinity linear sweep voltammetric method at in situ mercury film electrode for the determination of singulair in tablets and its interaction with human serum albumin (HSA) was investigated. The solubility of singulair in aqueous media was enhanced by inclusion with hydroxypropyl-β-cyclodextrin (HPβCD). The nature of the electrochemical process of singulair was studied by affinity cyclic voltammetry (ACV). Reproducibility of the proposed method was checked giving interday precision of 0.073 standard deviation. The limit of detection and limit of quantification were 0.05 and 0.16 fg/L, respectively. In the present work, singulair was interacted with HSA by 1: 1 stoichiometry to form electroinactive supramolecular complex. The binding constant was precisely estimated by coupling affinity linear sweep voltammetry (ALSV) and ACV with non-linear regression analysis based on the shifting of analyte peak potentials. The proposed experiments and data analysis could be used to investigate the binding constant of drug with protein within one hour.     

Preparation and electrochemical performance of graphene–Pt black nanocomposite for electrochemical methanol oxidation

This work reports the preparation, characterization, and electrocatalytic characteristics of a new metallic nanocatalyst. The catalyst, Pt black–graphene oxide (Pt-GO), was prepared by deposition of Pt black on the surface of graphene oxide nanosheet and characterized by transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and voltammetry. The Pt-graphene (Pt-GR) composite modified glassy carbon electrode (Pt-GR/GCE) was prepared with cyclic voltammetric scanning of Pt-GO/GCE in the potential range from ?1.5 to 0.2 in 0.1 M phosphate buffer solution at 50 mV·s^?1 for 5 cycles. The electrocatalytic properties of the Pt-GR/GCE for methanol (CH₃OH) oxidation have been investigated by cyclic voltammetry (CV); high electrocatalytic activity of the Pt-GR/GCE can be observed. This may be attributed to the high dispersion of Pt catalyst and the particular properties of GR support. The long-term stability of Pt-GR composite was investigated in 0.05 M CH₃OH in 0.1 M H₂SO₄ solution. It can be observed that the peak current decreases gradually with the successive scans. The loss may result from the consumption of methanol during the CV scan. It also may be due to the poisoning organic compounds. The results imply that the Pt-GR composite has good potential applications in fuel cells.     

Application of High-Performance Thin-Layer Chromatography for Screening and Simultaneous Determination of Some Angiotensin II Receptor Antagonists in Dosage Forms and Plasma

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatographic (HPTLC) method was performed for simultaneous quantification of four angiotensin II...     

Cu(Ⅱ),Ni(Ⅱ),Co(Ⅱ),Mn(Ⅱ),Zn(Ⅱ)和Cd(Ⅱ)的乙基3-(2-氨硫化亚肼基)-2-(羟胺基)丁烯酸酯配合物:合成、表征和细胞毒性(英文)

合成了Cu(Ⅱ),Ni(Ⅱ),Co(Ⅱ),Mn(Ⅱ),Zn(Ⅱ)和Cd(Ⅱ)的乙基3-(2-氨硫化亚肼基)-2-(羟胺基)丁烯酸酯配合物(H2L)并用元素分析,DTA热分析,IR,UV-Vis,1H-NMR,质谱,顺磁共振以及磁矩,电导率测量等对合成的配合物进行表征。摩尔电导率测量结果证明合成的配合物为非电解质。光谱数据表明配体分别表现为一元的三齿配体,一元的二齿配体,中性的二齿配体,中性的三齿配体,一元的四齿配体或二元的四齿配体通过席夫碱的氮原子,氨基硫脲中的氮原子,肟中的氮原子和硫酮中的硫原子与金属离子键合生成围绕金属离子的四面体或平面正方形构型。固态Cu(Ⅱ)(2),(3),(4)和(5)的配合物顺磁共振谱表明其为轴向对称,但(10~15)的配合物却为各向异性。配体和配合物(2),(3),(10),(13),(16)和(19)由于它们对乳腺癌(MCF-7细胞系)和肝癌(HePG-2细胞系)的抑制作用而表现出潜在的抗癌活性。