A comparative study on the diagnosis of maedi-visna infection in serum and colostrum samples using agar gel immunodiffusion (AGID) technique

Serum/colostrum pairs were collected from 245 ewes in 6 sheep herds which had been determined previously to be infected with MV virus and were tested against maedi-visna infection using AGID test. Positive rates were detected as 3.8-41.2% in tested flocks. Serum and colostrum samples obtained from 53 sheep were positive for MV virus specific antibodies by AGID test. 16 colostrum samples were negative although serum samples obtained from the same animals were found to be positive for MV antibodies. Of the 245 sera and colostrum pairs tested, there was total agreement of results (+ or -) in 229 and disagreement in the results with the other 16 serum/colostrum pairs. Of the latter, all serum samples were positive and all colostrum samples were negative for MV antibodies. This study compared colostrum and serum samples for the determination of MV antibodies using AGID test under field conditions on naturally infected animals and on healthy animals. The results show that colostrum antibodies can be detected using AGID test and that colostrum is a reliable material to determine anti-MV virus antibodies. The procedure can be used for herd diagnosis.     

Dissolution kinetics of an oxidized copper ore in water saturated by chlorine

Dissolution kinetics of an oxidized copper ore (mainly malachite) in water saturated by Cl₂ has been studied. The effect of particle size, flow rate of the gas, temperature and solid-liquid ratio has been determined. The dissolution rate increased with decrease in particle size and solid-liquid ratio and with increase in the gas flow rate and temperature. It has been found that the dissolution proceeds in two stages and is controlled by diffusion through the ash layer in each stage. The activation energies for the first and second stage are 27.15 and 20.21 kJ mol^?1, respectively.     

Bond strength of repaired composite resins: surface treatments,adhesive systems,and composite type

The aim of the present study was to investigate the effects of three different surface treatments and two different adhesives on the microtensile bond strength (μTBS) of repaired composites using the same or different type of resin. Twenty-four nano-hybrid (Ceram X mono-C) and 24 nanofilled (Filtek Ultimate-F) composite discs were prepared. The specimens were aged with 5000 thermocycles and randomly divided into groups according to the surface treatment methods: (a) phosphoric acid (b) Er:YAG laser and (c) aluminum trioxide particle (air abrasion). Fresh composite resins (C and F) were added to the treated surfaces with two different adhesives (two-step and one-step self-etch adhesives). Then, the specimens were aged again. The stick-shaped specimens were prepared from the discs (n = 25) and the sticks were subjected to the μTBS test. Results indicated that significant differences were found in μTBS values among the surface treatment methods. In the C groups, the highest μTBS value (41.3 ± 8.3 MPa) was recorded in the air abrasion and one-step self-etch adhesive group, which were repaired with the same kind of composite. In the F groups, the highest μTBS value was observed in the air abrasion and one-step self-etch adhesive (37.6 ± 12.3 MPa) group. The treatment with air abrasion is more effective than the others, and it may be suggested for composite repair.     

Preparation and Characterisation of Novel Composites Based on a Radiation Grafted Membrane for Fuel Cells

Novel composites for fuel cells were prepared via two different methods using a radiation grafted membrane, prepared from poly(ethylene‐alt‐tetrafluoroethylene) (ETFE) and styrene, and commercial Nafion®112 as the substrates. The first method was based on chemical polymerisation of pyrrole (Py) on the membrane followed by platinum (Pt) deposition by chemical reduction. The second method was based on direct deposition of Pt on the membrane by several steps of initial composite formation and surface electrodeposition. Polypyrrole (PPy) was coated as a layer only on the surface of the membrane. The thickness of PPy layer, proton conductivity of the composites and Pt loading could be controlled with Py polymerisation time. Moreover, the deposition of Pt on the surface as the granular particles was achieved by the first method while Pt deposition occurred as the aggregates of particles on the surface of the membrane by the second method which yielded wavy and rough surfaces. The first method offered a simple, quick, reproducible and effective procedure, yet some of the Pt particles peeled off from the surface of the composites. The second method required complex, multistep and tedious procedure with a high amount of Pt precursor, while Pt particles were more stable in this case.     

Deposition and Characterization of Tungsten Carbide Thin Films by DC Magnetron Sputtering for Wear-Resistant Applications

In this study, WC (tungsten carbide) thin films were deposited on high-speed steel (AISI M2) and Si (100) substrates by direct current magnetron sputtering of a tungsten carbide target having 7% cobalt as binding material. The properties of the coatings have been modified by the change in the bias voltages from grounded to 200 V. All the coatings were deposited at 250°C constant temperature. The microstructure and the thickness of the films were determined from cross-sectional field-emission gun scanning electron microscope micrographs. The chemical composition of the film was determined by electron probe micro analyzer. The x-ray diffractometer has been used for the phase analyses. Nanoindentation and wear tests were used to determine the mechanical and tribological properties of the films, respectively. It is found that the increase in the bias voltages increased drastically the hardness and elastic modulus, decreased the friction coefficient values and increased the wear resistance of tungsten carbide thin films by a phase transformation from metallic W (tungsten) to a nonstoichiometric WC_1?x (tungsten carbide) phase.     

Poly(ethylene glycol)/poly(methyl methacrylate) blends as novel form‐stable phase‐change materials for thermal energy storage

In this study, we focused on the preparation and characterization of poly(ethylene glycol) (PEG)/poly(methyl methacrylate) (PMMA) blends as novel form‐stable phase‐change materials (PCMs) for latent‐heat thermal energy storage (LHTES) applications. In the blends, PEG acted as a PCM when PMMA was operated as supporting material. We subjected the prepared blends at different mass fractions of PEG (50, 60, 70, 80, and 90% w/w) to leakage tests by heating the blends over the melting temperature of the PCM to determine the maximum encapsulation ratio without leakage. The prepared 70/30 w/w % PEG/PMMA blend as a form‐stable PCM was characterized with optical microscopy and Fourier transform infrared spectroscopy. The thermal properties of the form‐stable PCM were measured with differential scanning calorimetry (DSC). DSC analysis indicated that the form‐stable PEG/PMMA blend melted at 58.07°C and crystallized at 39.28°C and that it had latent heats of 121.24 and 108.36 J/g for melting and crystallization, respectively. These thermal properties give the PCMs potential LHTES purposes, such as for solar space heating and ventilating applications in buildings. Accelerated thermal cycling tests also showed that the form‐stable PEG/PMMA blend as PCMs had good thermal reliability and chemical stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of log storage conditions and steaming process on the formaldehyde emissions of particleboard manufactured from eucalyptus (E. camaldulensis) wood

The aim of this study was to determine the changes in formaldehyde emissions of eucalyptus particleboards produced from logs stored under different conditions (indoor, outdoor, and under water) or steamed. The pH and Stiasny values of particles changed significantly according to the storage condition and log steaming process. The pH values of particles obtained from steamed logs and stored outdoors for 4 months were found to be lower than those of the particles obtained from logs stored in the other aforementioned two conditions. The peaks of acetyl groups in the IR-spectra of the four group particles were similar. There was a strong relationship among the formaldehyde emission values of the panels pressed at 150 °C and the Stiasny values of the particles from which the panels were produced. The formaldehyde emission values of the panels pressed at 190 °C were lower than those of the panels pressed at 150 °C.     

Thermal issues in machine tools

This paper presents a review of the latest research activities and gives an overview of the state of the art in understanding changes in machine tool performance due to changes in thermal conditions (thermal errors of machine tools). The topics are focused on metal cutting machine tools, especially on turning and milling machines as well as machining centres. The topics of the paper thermal issues in machine tools include measurement of temperatures and displacements, especially displacements at the tool centre point, computations of thermal errors of machine tools, and reduction of thermal errors. Computing the thermal errors of machine tools include both, temperature distribution and displacements. Shortly addressed is also to avoid thermal errors with temperature control, the influence of fluids and a short link to energy efficiency of machine tools. The paper presents the summary of research work in the past and current. Research challenges in order to achieve a thermal stable machine tool are discussed. The paper apprehend itself as an update and not a substitution of two published keynote papers of Bryan et al. [28] in 1990 and Weck et al. [199] in 1995.     

Thermal energy storage properties of polyethylene glycol grafted styrenic copolymer as novel solid-solid phase change materials

Polymeric solid-solid phase change materials (S-SPCMs) are functional materials with phase transition-heat storing/releasing ability. With this respect, a series of polyethylene glycol (PEG) grafted styrenic copolymer were produced as novel S-SPCMs. PEGs with three different molecular weights were used for synthesis of isocyanate-terminated polymers (ITPs). To achieve cross-linking S-SPCMs, the ITPs were grafted with styrene-co-ally alcohol) (PSAA) at three different PSAA:PEG mole ratios. The produced polymers were characterized using Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (¹H NMR), and X-ray diffraction (XRD) technique. The crystalline-amorphous phase transitions of the polymers were examined using polarized optical microscopy (POM). The FT-IR, NMR, and XRD results confirmed the expected chemical structures and crystallization performances of the polymers. Thermal energy storage (TES) properties of the S-SPCMs were determined by differential scanning calorimetry (DSC). The DSC results revealed that the polymers with grafting ratio of PSAA:PEG(1:1) had phase transition enthalpies between about 74 and 142 J/g and phase transition temperatures between about 26°C and 57°C. Thermogravimetric analysis (TGA) measurements demonstrated that the S-SPCMs were resistant to thermal decomposition until about 300°C. Thermal conductivities of the produced S-SPCMs were measured in a range of about 0.18 to 0.19 W/mK. Furthermore, TES properties of the S-SPCMs were slightly changed as their chemical structures were remained after 5000 thermal cycles. By overall evaluation of the findings, it can be foreseen that particularly PSAA-g-PEG(1:1) polymers can be considered as promising S-SPCMs for some TES practices such as air conditioning of buildings, thermoregulation of food packages, automobile components, electronic devices, and solar photovoltaic panels.