Citation status of Turkish physics publications in foreign journals: A global analysis

We have studied the citation rates and characteristics of 572 Turkish physics publications that appeared in the source journals listed in theScience Citation Index (SCI) for the period 1982–1990 to drive the following results: The papers appeared in a set of 94 journals, and 68% of the total output went to 21 of these; half of which are journals of high impact. On the average, papers from Turkey that appeared in the American and European journals are cited at rates higher than the corresponding average papers. There has been a substantial shift of Turkish papers from European journals to American journals over the last few years. These changes are an example of the process by which science in a less developed country becomes integrated into the word scientific community.     

Adaptive mesh refinement for chevron nozzle jet flows

In this paper an adaptive mesh generation procedure is presented for improving the resolution of the numerical simulation of a turbulent jet exhausting from a chevron nozzle. This procedure is based on the minimization of a variational integral whose integrand depends on the metric (also called the monitor function) induced by a curvilinear grid generated in the physical domain. Specifically, it leads to solving parabolic equations involving the monitor function, which is carefully designed to resolve the flow gradients, and which, in the present instance, is determined by the time-averaged axial velocity profile within the jet. This mesh redistribution strategy is incorporated into a flow computation code (that solves the compressible three-dimensional Navier-Stokes equations using a prefactored optimized fourth-order compact difference scheme for spatial derivatives and the Beam-Warming method for the time derivative on a multi-block overset grid) and is demonstrated to be efficient and effective.     

A real time traffic simulator utilizing an adaptive fuzzy inference mechanism by tuning fuzzy parameters

Traffic lights are installed at intersections mostly for traffic management. Traffic signals turn on during the amount of time determined. Intelligent traffic management systems emerge as a need to handle the dynamicity of traffic. These systems are first implemented on simulators in order to mimic the real life situations before realization.     

The effect of cryogenic treatment on tapping

This study was realized with two different types (flat and thread rolled) of coated (TiAlN), uncoated, and cryogenically treated taps (uncoated). The tapping processes were carried at four different cutting speeds (2, 3, 4, and 5 m/min) and 1.25 mm/rev feed rate under dry and wet cutting conditions on the Ti-6Al-4 V alloy. The measured cutting forces (cutting torque) were evaluated according to the cutting tool and cutting parameters. The best results in terms of cutting torque were obtained with straight flutes with spiral point taps. For the coated cutting tools, it was seen that the cutting torque was higher with respect to the other tools. The cutting fluid caused decreases in cutting forces for both of the cutters. Under dry cutting conditions, in the cryogenically treated tool, cutting torques came out to be lower with respect to the coated and uncoated tool.     

Sulfur removal from original and acid treated lignites by pyrolysis

Six original, three hydrochloric acid treated and three demineralized lignite samples were pyrolysed at seven different temperatures between 350 and 950 °C for 7 min under evolved gas atmosphere. All samples and their chars were analysed quantitatively for their total sulfur content and pyritic, sulfate and organic sulfur forms. The alkaline oxide contents of original lignites and their hydrochloric acid treated counterparts were determined. The results clearly indicate that calcium and sulfurous compounds in the parent lignites undergo various chemical changes during pyrolysis. The pyrolysis temperature, types of sulfur and calcium compounds, all affect the behaviour of sulfur during pyrolysis. Higher pyrolysis temperatures favour total sulfur removal for all lignites, reaching 30-54% around 850 and 950 °C. HCl treatment and demineralization decreases calcium contents, hence, increases quantitative sulfur removal from the lignites by pyrolysis. The maximum total sulfur removal from acid treated lignites is observed as 77%. The ratios of the total sulfur to heating value decreases with increases of pyrolysis temperature up to around 600 °C for acid treated lignites and no major changes are observed at higher pyrolysis temperatures; no common behaviour is observed for original lignites.     

Pseudospecific magnetic affinity beads for immunoglobulin‐G depletion from human serum

Magnetic poly(ethylene glycol dimethacrylate‐N‐methacryloyl‐(L )‐histidine methyl ester) [m‐poly(EGDMA‐MAH)] beads were prepared by suspension polymerization for the affinity depletion of immunoglobulin‐G (IgG) from human serum in a batch system. Elemental analysis of the magnetic beads for nitrogen was estimated as 70 μmol MAH/g polymer. IgG adsorption onto the m‐poly(EGDMA) was negligible. Higher adsorption value (up to 46.8 mg/g) was obtained in which the m‐poly(EGDMA‐MAH) beads were used. IgG adsorption capacity of the magnetic beads increased with an increase in the concentration of IgG. The maximum IgG adsorption was observed at pH 6.5 for MOPS buffer. IgG molecules could be repeatedly adsorbed and eluted with these adsorbents, without noticeable loss in their IgG adsorption capacity. Adsorption capacity decreased for both increasing salt concentration and temperature. In this study, we show that m‐poly(EGDMA‐MAH) beads (wherein IgG molecules bind directly with the matrix) can be used directly for affinity depletion without further modification. Higher adsorption value was obtained from human serum (up to 85.7 mg/g). The elution results demonstrated that the adsorption of IgG to the adsorbent was reversible. The depletion efficiencies for IgG were above 85% for all studied concentrations. Eluted portion was analyzed for testing the IgG removal efficiency by two dimensional gel electrophoresis. Eluted proteins include mainly IgG, and a small number of nonalbumin proteins such as apolipoprotein A1, serotransferrin, haptoglobulin, and α1‐antitrypsin. IgA was not identified in eluted fraction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Hydrophobic microbeads as an alternative pseudo-affinity adsorbent for recombinant human interferon-α via hydrophobic interactions

Hydrophobic interaction chromatography (HIC) is increasingly used for protein purification, separation and other biochemical applications. The aim of this study was to prepare hydrophobic microbeads and to investigate their recombinant human interferon-α (rHuIFN-α) adsorption capability. For this purpose, we had synthesized functional monomer, N-methacryloyl-l-phenylalanine (MAPA), to provide a hydrophobic functionality to the adsorbent. The poly(2-hydroxyethyl methacrylate-N-methacryloyl-l-phenylalanine) [poly(HEMA–MAPA)] microbeads were prepared by suspension copolymerization. microbeads were characterized using FTIR, swelling behavior, and SEM micrographs. Equilibrium swelling ratio of poly(HEMA–MAPA) and poly(HEMA) microbeads were 53.3% and 69.3%, respectively. The specific surface area and average pore diameters determined by BET apparatus were 17.4 m²/g and 47.3 Å for poly(HEMA) microbeads and 18.7 m²/g and 49.8 Å for poly(HEMA–MAPA) microbeads. Adsorption experiments were performed under different conditions. Maximum rHuIFN-α adsorption capacity was found to be 137.6 ± 6.7 mg/g by using poly(HEMA–MAPA) microbeads with a size range of 150–250 μm and containing 327 μmol MAPA/g microbeads. Compared with poly(HEMA–MAPA) microbeads, nonspecific rHuIFN-α adsorption onto plain poly(HEMA) microbeads was very low, about 4.2 ± 2.3 mg/g. To determine the effects of adsorption conditions on possible conformational changes of rHuIFN-α structure, fluorescence spectrophotometry was employed. Repeated adsorption–elution processes showed that these microbeads are suitable for repeatable rHuIFN-α adsorption.     

Mechanical Properties of BSCCO Superconductor by Oliver–Pharr Method and Work of Indentation Approach

Polycrystalline superconducting Bi–Pb–Gd–Sr–Ca–Cu–O bulk samples with nominal composition Bi_1.7Pb_0.3?x Gd _x Sr₂Ca₃Cu₄O_12+y (x=0.00,0.01,0.05) were produced by the melt quenching method. The mechanical properties of the samples were characterized by depth sensing indentation technique under different peak loads ranging from 200 to 1800 mN. The experimental data were comparatively analyzed by the Oliver–Pharr method and a work of indentation approach. It was found that the work of indentation approach gave more reliable results because of the reducing pile-up effect. The results implied that both microhardness and reduced elastic modulus increased with increasing Gd substitution.