Synthesis and antimicrobial activity of metronidazole containing polymer and copolymers

Homopolymer and copolymers containing metronidazole (MTZ) drug were synthesized. Acryloyl chloride was reacted with MTZ (drug) to produce monomer containing MTZ, and then the monomer was copolymerized with various amounts of methyl methacrylate. The produced monomer, homopolymer, and copolymers were characterized by elemental analysis, IR, and ¹H‐NMR. The antimicrobial activities of the synthesized polymers were tested against Kelpsilic as fungal organisms, and Escherichia coli, Bacillus subitilus, and Pesudomonus areuginosa as bacteria organisms. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Forensic investigation of the cause(s) of slippery ultra-thin bonded wearing course of an asphalt pavement: influence of binder content

This paper documents the second part of a forensic investigation performed to determine the causes of loss of skid resistance and bleeding in two pavement sections rehabilitated with an ultra-thin bonded wearing course. The first part of the study explored the influence of the aggregate fraction on the loss of skid resistance. This second part focuses on binder-related issues to understand the cause of the bleeding. A detailed investigation was performed on cores removed from both sections to quantify the binder content profile with depth. The chemical characteristics of all the recovered binders were determined using Fourier transform infrared spectroscopy and X-ray fluorescence spectroscopy. The results suggested that bleeding due to excess binder in the tack coat contributed to this deleterious performance. Chemical analysis identified an upward migration of a part of the binder from the interface and confirmed this hypothesis.     

Simulation and multi‐objective optimization of a fixed bed catalytic reactor to produce hydrogen using ethanol steam reforming

A mathematical model is developed for a fixed bed catalytic reactor to produce hydrogen using ethanol steam reforming in the presence of a Ni (II)‐Al (III)‐LDH catalyst. The simulation of the reactor has been carried out using the ode23s module of MATLAB (version 2010a) based on a mechanistic kinetic model (Langmuir‐Hinshelwood approach) with proven reaction kinetics. There is a confusion regarding the values of the kinetic parameters even though earlier workers have used the same experimental data and the same model equations. The values of the model parameters obtained using two different curve‐fitting techniques, the generalized reduced gradient (GRG) algorithm and a derivative‐free approach based on the simplex method, were different. This leads to differences in the agreement of model predictions vs experimental results. A more powerful and recent technique, genetic algorithm (GA), has been used to resolve this problem by minimizing a sum‐of‐square errors (SSE). Our tuned model parameters gave good agreement with experimental data. An SSE value of the order of 10^?4 is obtained in the present study over the SSE values of the order of 10^?2 obtained from earlier studies. Using this tuned model, multi‐objective optimization (MOO) of an isothermal fixed bed ESR reactor has been carried out using NSGA‐II to achieve the maximum hydrogen mole fraction in the product gas while simultaneously minimizing the mole fractions of the greenhouse gases, CO + CO₂. The maximum theoretical mole fraction of hydrogen obtained is 0.088 at 911.86 K vs 0.080 at 923 K, as observed experimentally. The more recent jumping gene adaptation of NSGA‐II, namely, NSGA‐II‐JG, was also tried to check if it can give more rapid convergence to the Pareto set. It is found that the present problem is far too simple, and the advantage of the JG adaptation is small.     

Liquid fuel resources and prospects for ligno-cellulosic ethanol: An Egyptian case study

Fossil fuels (oil, natural gas and coal) presently represent about 90% of the world’s total commercial primary energy demand. Yet, they are depletable sources of energy. Growth in the production of easily accessible oil, the main source of high energy liquid transportation fuels, will not match the projected rate of demand growth, especially in developing countries. In the transport sector, today, the only alternative to non-sustainable fossil fuels is biofuels that are produced from biomass, a stored environmentally neutral solar energy. These fuels are compatible with current vehicles and blendable with conventional fuels. Moreover, they share the long-established distribution infrastructure with little, if any, modification of equipment. The main biofuels presently in commercial production are bioethanol and biodiesel. Industrial countries started production of the 1st generation bioethanol and biodiesel from food products (grains and edible oil) since a few decades and these fuels are currently available at petrol stations. Second generation bioethanol from ligno-cellulosic materials is on the research, pilot and/or demonstration stage. This paper discusses the current situation regarding liquid fuels in Egypt which are experiencing imbalance between total production and demand for gasoline and diesel fuels. The quantified need for nonconventional sources is presented. Based on a thorough assessment of current and prospective generated agriculture residues as distributed over the political areas, mapping of the number and capacity of plants to be installed for production of bioethanol from available residues namely rice straw, sugar cane residues and cotton stalks has been developed. Annual capacities of 3000, 10,000 and 20,000 tons ethanol/year until year 2021 have been proposed. Capital and operating requirements and economic indicators have been estimated. It has been concluded that at current price of ethanol of about $0.6/kg, the simple rate of return on investments is about 2.8%, 11% and 16% for the 3000, 10,000 and 20,000 tons annual capacity ethanol respectively.     

Effect of Tungsten (W) Substitution on the Physical Properties of Bi-(2223) Superconductors

The superconducting Bi_1.6Pb_0.4Sr₂Ca₂Cu_3?x W _x O_10+y (x=0.00, 0.05, 0.10, 0.15) bulk samples were prepared by the solid-state reaction method. The effects of W substitution on the BSCCO system have been investigated by the electrical resistivity (ρ-T), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), magnetic hysteresis and critical current density measurements. It has been found that the Bi-(2212) low-T _C phase is formed for all the substitution levels, together with the Bi-(2223) high-T _C phase. The results obtained from the XRD data show that the Bi-(2223) phase gradually transforms into the Bi-(2212) phase with increasing W substituting for Cu. In addition, from the magnetization measurements at the temperatures below the zero resistance temperatures of the samples, we have observed that a decreasing in magnitude of |M| with the increasing measurement temperature and W concentration. Therefore, the decreasing of |M| related to superconducting volume seems to imply an existence of flux-pinning centers in our samples.     

Antibiotic resistance and incidence of Enterococcus species in Turkish white cheese

Thirty samples of Turkish white cheese were analysed for the presence of Enterococcus spp., and presumptive isolates were identified by morphological, cultural and biochemical tests and confirmed by the API 20 Strep System. Among the 101 isolates of Enterococcus spp., 62 were E. faecalis , 25 were E. faecium , seven were E. durans , five were E. mundtii and two were E. hirae/dispar . The resistance of the isolates to 13 different antibiotics was determined by the Kirby–Bauer disc diffusion test. Resistance to streptomycin, erythromycin, oxacillin and vancomycin was frequently found in these enterococci, and resistance to vancomycin was found in 96.8% of E. faecalis isolates and 76% E. faecium . The most effective antimicrobials were ampicillin (69.3% of isolates inhibited) and imipenem (76.3% of isolates inhibited). This examination confirmed the presence of enterococci, especially vancomycin-resistant strains, in Turkish white cheese, indicating poor sanitary conditions during production and processing and a significant health risk for consumers.     

Biochemical changes and in-vitro protein digestibility of the endosperm of germinating dolichos lablab

A gradual decrease was noted in total protein, soluble protein and protein fractions such as albumin, globulin, prolamine andglutelin in the endosperm of Dolichos lablab L germinated for 8 days. Prolamine showed a maximum decrease of 85% whereas only a 25% decrease was noted in the globulin fraction. Both acid and alkaline protease activities increased during germination, and the acid protease activity was consistently higher than the alkaline protease activity throughout. Electrophoretic studies showed that high molecular weight polypeptide bands disappeared with the appearance of new low molecular weight polypeptide bands in the endosperm proteins of the germinating seeds. Total phenolics and tannin contents and trypsin inhibitory activity also increased during the progressive germination. Germination increased the in-vitro protein digestibility of the endosperm of Dolichos lablab in the presence of proteolytic enzymes like pepsin, trypsin and pancreatin. It showed a negative but non-significant correlation with trypsin inhibitory activity, phenolics and tannin contents. Amylase activity also increased gradually up to the sixth day of germination which coincided with the increase in the reducing sugars.     

λ-Statistical limit points of the sequences of fuzzy numbers

Aytar has introduced the concepts of statistical limit and cluster points of a sequence of fuzzy numbers based on the definitions given in Fridy’s study for sequences of real numbers. In this paper, we define λ-statistical limit and λ-statistical cluster points of sequences of fuzzy numbers and discuss the relations among the sets of ordinary limit points, λ-statistical limit points and λ-statistical cluster points of sequences of fuzzy numbers.     

Comments on "AC impedance of an isolated flat conductor"

For original paper see Z. Zhihua and M. Weiming, IEEE Trans. Electromagn. Compat., vol.44, pp.482-486, (2002). Employing the moments method, and a triangular patch modeling technique, this paper gives an analysis of the AC impedance of an isolated flat conductor, taking into consideration capacitive effects. It is observed that, for the flat conductor under consideration, the capacitance has a significant effect on the impedance beyond a frequency of about 20 MHz. Thus, it can be concluded that the capacitive effects should also be considered in evaluating the AC impedance of an isolated conducting strip.