Some characterizations of weakly compact operator on Banach lattices

We establish necessary and sufficient conditions under which each operator between Banach lattices is weakly compact and we give some consequences.     

Diastereodivergence and appendage diversity in the multicomponent synthesis of aryl-pyrrolo-tetrahydrocarbazoles

A one-pot approach using a subsequent Cu(II)/Cu(I) catalysis and a highly diastereodivergent three-component reaction allow an easy access to various aryl-pyrrolo-tetrahydrocarbazoles with the control of up to four variable fragments and two different diastereoselectivities.     

Selective Spectrofluorimetric Protocol for Determination of Commonly Used Gram-negative Bactericidal Drug in Combined Pharmaceutical Dosage Forms and Human Plasma

Gram-negative bacteria cause infections such as skin infection, meningitis, and pneumonia in human being. Gram-negative bacteria are highly resistant to most availaible bactericidal drugs. One of the most commonly used Gram-negative bactericidal drug is Polymyxin B sulfate (PMS). In addition, it is used in cases of highly resistant Gram-negative bacterial infections. The widespread of PMS necessitate the development of an exceedingly sensitive and selective fluorimetric assay for its determination in pure form, different pharmaceutical dosage forms, and human plasma. The presented method is used to determine PMS in their dosage form (vials) and combined pharmaceutical formulations (skin and eye ointments) with a high degree of accuracy and selectivity. The described procedure relies on the structure of a derivative of a high degree of fluorescence called dihydropyridine, via the condensation of the amino moiety of PMS with two equivalents of acetylacetone in the presence of formaldehyde and Teorell buffer (pH?=?3). The fluorescent product was measured at 471 nm (λ_ex?=?402 nm). The linearity ranged from 100-3000 ng mL^?1 of PMS with an excellent r² of 0.9998. LOD and LOQ were 27.16 ng mL^?1 and 82.30 ng mL^?1, respectively. Owing to the developed method's high selectivity, it was successfully utilized for assay of PMS, in the ointment, in the presence of oxytetracycline as an active ingredient. Furthermore, the procedure applied for the estimation of parenteral PMS in human plasma with very good mean recovery 97.42?±?1.46.

     

Evaluation of a tube equipped with different inserts: competition between improvements in heat transfer versus increase in pressure drop

Journal of Thermal Analysis and Calorimetry - This study evaluated the efficacy of different inserts incorporation into the simple tube on the rate of improvement in heat transfer as well as the...     

Date Fruits-Assisted Synthesis and Biocompatibility Assessment of Nickel Oxide Nanoparticles Anchored onto Graphene Sheets for Biomedical Applications

Nanographene- and graphene-based nanohybrids have garnered attention in the biomedical community owing to their biocompatibility, excellent aqueous processability, ease of cellular uptake, facile surface functionalization, and thermal and electrical conductivities. NiO nanoparticle-graphene nanohybrid (G-NiO) was synthesized by first depositing Ni(OH)₂ onto the surface of graphene oxide (GO) sheets. The Ni(OH)₂-GO hybrids were then reduced to G-NiO using date palm syrup at 85 °C. The prepared G-NiO nanohybrids were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The NiO nanoparticles, with a diameter of approximately 20–30 nm, were uniformly dispersed over the surface of the graphene sheets. The G-NiO hybrids exhibit biocompatibility in human mesenchymal stem cells (hMSCs) up to 100 μg/mL. The nanohybrids do not cause any significant changes in cellular and nuclear morphologies in hMSCs. The as-synthesized nanohybrids show excellent biocompatibility and could be a promising material for biomedical applications.     

Carbon nanotube-cuprous oxide composite based pressure sensors

In this paper,we present the design,the fabrication,and the experimental results of carbon nanotube (CNT) and Cu 2 O composite based pressure sensors.The pressed tablets of the CNT-Cu 2 O composite are fabricated at a pressure of 353 MPa.The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm.The sizes of the Cu 2 O micro particles are in the range of 3-4 μm.The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm,respectively.In order to make low resistance electric contacts,the two sides of the pressed tablet are covered by silver pastes.The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m 2.The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.     

Interdiffusion/reaction at the polymer/polymer interface in multilayer systems probed by linear viscoelasticity coupled to FTIR and NMR measurements

This paper describes the experimental investigation of the interdiffusion/reaction mechanisms of asymmetric polymer-polymer interfaces. The study deals with the assessment of the chemical reactions occurring at the interface between two reactive polymers. A focal point of the investigation was to study these interfacial reactions by an array of techniques at very different space scales: from macroscopic viscoelastic investigations to IR and NMR spectroscopies at the molecular scale. The studied material pairs include PE-GMA/PA6 as the reactive system (RS) and PE/PA6 as the non-reactive one (NRS) - of coextruded multilayer polymers, i.e., after processing. The linear viscoelastic properties of the reactive multilayer systems were determined and the mechanisms were analyzed by NMR and FTIR measurements. Substantial reactions occurred during the rheological measurements and the results indicated the preferential formation of a copolymer at the interface, triggered by the neighboring layers. Moreover, the contribution of an interface/interphase effect was investigated along with the increase in the number of layers. The results showed that the variation in dynamic modulus of the multilayer system was a result of both diffusion and chemical reaction. Specific experiments were carried out to follow-up on the physicochemical phenomena, and the results were rationalized by comparing the obtained data with theoretical models. The effect of this interphase was quantified at a specific welding time and oscillation frequency thanks to rheological modeling. Because of the coupling between rheology and spectroscopical tools, potential reactions between the GMA functions and the amine/carboxylic polyamide chain ends were explored. The results highlighted that the main reaction mechanism was constituted by the crosslinking reaction between the GMA and carboxylic acid units, and not by that between GMA and amine end functions.     

Optimal adaptive replacement in a renewal process

In this paper we present an exact method for computing the Weibull renewal function and its derivative for application in maintenance optimization. The computational method provides a solid extension to previous work by which an approximation to the renewal function was used in a Bayesian approach to determine optimal replacement times. In the maintenance scenario, under the assumption an item is replaced by a new one upon failure, the underlying process between planned replacement times is a renewal process. The Bayesian approach takes into account failure and survival information at each planned replacement stage to update the optimal time until the next planned replacement. To provide a simple approach to carry out in practice, we limit the decision process to a one‐step optimization problem in the sequential decision problem. We make the Weibull assumption for the lifetime distribution of an item and calculate accurately the renewal function and its derivative. A method for finding zeros of a function is adapted to the maintenance optimization problem, making use of the availability of the derivative of the renewal function. Furthermore, we develop the maximum likelihood estimate version of the Bayesian approach and illustrate it with simulated examples. The maintenance algorithm retains the adaptive concept of the Bayesian methodology but reduces the computational need. Copyright © 2014 John Wiley & Sons, Ltd.