Eudragit S (methyl methacrylate methacrylic acid copolymer)/fatty acid blends as form‐stable phase change material for latent heat thermal energy storage

By composing (Eudragit S) with fatty acids (stearic acid (SA), palmitic acid (PA), and myristic acid (MA)), form‐stable phase change materials (PCMs), which can retain the same shape in a solid state even when the temperature of the PCMs is over the melting points of the fatty acids, are prepared. The compatibility of fatty acids with the Eudragit S is proved by microscopic investigation and infrared (FTIR) spectroscopy. The melting and crystallization temperatures and the latent heats of melting and crystallization of the form‐stable PCMs are measured by Differential Scanning Calorimetry (DSC) method. The maximum mass percentage of all fatty acids in the form‐stable PCMs is found as 70%, and no leakage of fatty acid is observed at the temperature range of 50–70°C for several heating cycles. Thermal properties obtained from the DSC analysis indicate that the Eudragit S/fatty acid blends as form‐stable PCM have great potential for passive solar latent heat thermal energy storage (LHTES) applications in terms of their satisfactory thermal properties and utility advantage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1402–1406, 2006     

Synthesis and characterization of poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) copolymer beads for heavy‐metal removal

We prepared poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [poly(EGDMA–VTAZ)] beads (average diameter = 150–200 μm) by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1‐vinyl‐1,2,4‐triazole (VTAZ). The copolymer composition was characterized by elemental analysis and found to contain five EGDMA monomer units for each VTAZ monomer unit. The poly(EGDMA–VTAZ) beads had a specific surface area of 65.8 m²/g. Poly(EGDMA–VTAZ) beads were characterized by Fourier transform infrared spectroscopy, elemental analysis, surface area measurements, swelling studies, and scanning electron microscopy. Poly(EGDMA–VTAZ) beads with a swelling ratio of 84% were used for the heavy‐metal removal studies. The adsorption capacities of the beads for Cd(II), Hg(II), and Pb(II) were investigated in aqueous media containing different amounts of these ions (5–750 mg/L) and at different pH values (3.0–7.0). The maximum adsorption capacities of the poly(EGDMA–VTAZ) beads were 85.7 mg/g (0.76 mmol/g) for Cd(II), 134.9 mg/g (0.65 mmol/g) for Pb(II), and 186.5 mg/g (0.93 mmol/g) for Hg(II). The affinity order toward triazole groups on a molar basis was observed as follows: Hg(II) > Cd(II) > Pb(II). pH significantly affected the adsorption capacity of the VTAZ‐incorporated beads. The equilibrium data were well fitted to the Redlich–Peterson isotherm. Consideration of the kinetic data suggested that chemisorption processes could have been the rate‐limiting step in the adsorption process. Regeneration of the chelating‐beads was easily performed with 0.1M HNO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4276–4283, 2006     

Asphalt concrete stability estimation from non-destructive test methods with artificial neural networks

The core drilling method has often been used to determine the current status of asphalt concretes. However, this method is destructive so causes damage to the asphalt concretes. In addition, this method causes localized points of weakness in the asphalt concretes and is time consuming. In recent years, non-destructive testing methods have been used for pavement thickness estimation, determination of elasticity modulus, and density and moisture measurements. In this study, the above-mentioned non-destructive and destructive tests with data obtained by applying the Marshall stability to the same asphalt concretes were estimated using the artificial neural networks approach.     

Natural frequency analysis of lattice boom crane theoretically and experimentally

International Journal of Steel Structures - Having knowledge of dynamic properties named as natural frequency and mode shapes during the design process is important to determine proper design...     

Immunoglobulin G recognition with Fab fragments imprinted monolithic cryogels: Evaluation of the effects of metal-ion assisted-coordination of template molecule

In this study, we applied the epitope imprinting approach to prepare molecularly imprinted monolithic cryogels for immunoglobulin G (IgG) recognition. In this respect, we imprinted F_ab fragments of IgG molecules instead of intact protein molecules via two different non-covalent interactions. In the first approach, we directly coordinated F_ab fragments with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine, but for the second, we used cupric ions [Cu(II)] as mediator between MAH and F_ab fragments. The monolithic cryogels were characterized by Fourier transform infrared (FTIR) spectroscopy, swelling test, and scanning electron microscopy. Then, the monolithic cryogels were used for F_ab fragment adsorption from aqueous solution while evaluating the factors such as pH and F_ab fragment concentration affecting on adsorption process in continuous set-up. After that, monolithic cryogels were used for IgG adsorption by varying pH, IgG concentration, flowrate, and temperature in appropriate ranges. Maximum IgG adsorption capacities were determined as 32.4 mg/g and 49.0 mg/g for directly coordinated cryogel (MIP_Direct) and Cu(II) assisted cryogel (MIP_{Cu(II) assisted}), respectively. Non-imprinted monolithic cryogels were also prepared for control purposes. In addition to F_ab fragments and IgG molecules, albumin and F_c fragment of IgG molecules were used as competitor biomolecules in order to investigate the selectivity gained by imprinting process. Relative selectivity constants were calculated as 1.47, 2.64 and 3.89 for MIP_Direct and 2.90, 8.98, and 11.51 for MIP_{Cu(II) assisted} for F_ab/IgG, F_ab/F_c, and F_ab/albumin as biomolecule pairs, respectively. The desorption efficiency and reusability of MIP_{Cu(II) assisted} cryogel were better than that of MIP_Direct. The results reported here showed that the metal ion assistance improved the selectivity features of the imprinted cryogels and allowed to study under milder conditions with enhanced adsorptive properties.     

The effect of phosphine in syngas on Ni-YSZ anode-supported solid oxide fuel cells

Ni-YSZ cermet is commonly used as the anode of a solid oxide fuel cell (SOFC) because it has excellent electrochemical performance, not only in hydrogen fuel, but also in a clean blended synthetic coal syngas mixture (30% H₂, 26% H₂O, 23% CO, and 21% CO₂). However, trace impurities, such as phosphine (PH₃), in coal-derived syngas can cause degradation in cell performance [J.P. Trembly, R.S. Gemmen, D.J. Bayless, J. Power Sources 163 (2007) 986-996]. A commercial solid oxide fuel cell was exposed to a syngas with 10 ppm PH₃ under a constant current load at 800 °C and its performance was evaluated periodically using electrochemical methods. The central part of the anode was exposed directly to the syngas without an intervening current collector. Post-mortem analyses of the SOFC anode were performed using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that the impurity PH₃ caused a significant loss of the Ni-YSZ anode electrochemical performance and an irreversible Ni-YSZ structural modification. Ni₅P₂ was confirmed to be produced on the cell surface as the dominant nickel phosphorus phase.     

Failure of Welded Radiator Nipples Caused by Nonmetallic Inclusions

A splitting phenomenon in the weld zone of the radiator nipples was encountered after a threading operation. During the failure analysis, some oxide traces were macroscopically observed on the surfaces of unthreaded nipples. Subsequent scanning electron microscopy–x-ray spectrometer (SEM–EDS) examination through the surfaces of the unthreaded nipples and as-pickled steel sheet coupons that were used for nipple manufacturing revealed that the oxide traces were hot-rolling scale residuals. However, none of the traces of scale residuals were encountered on the cross sections of weld zone of unthreaded nipple samples. Contrarily, some cracks and inclusion residuals were observed through the interface between the protrusion and weld zone. EDS analysis and optical microscopy affirmed the presence of MnS-type inclusions. The same kind of inclusions was also observed when one of the unthreaded nipples was intentionally separated through the weld zone. In conclusion, the main cause for the failure was determined to be the adverse effect that the MnS inclusions in the steel had on the material ductility.     

Characterization of 17-4 PH stainless steel foam for biomedical applications in simulated body fluid and artificial saliva environments

Highly porous 17-4 PH stainless steel foam for biomedical applications was produced by space holder technique. Metal release and weight loss from 17–4 PH stainless steel foams was investigated in simulated body fluid and artificial saliva environments by static immersion tests. Inductively coupled plasma-mass spectrometer was employed to measure the concentrations of various metal ions released from the 17-4 PH stainless steel foams into simulated body fluids and artificial saliva. Effect of immersion time and pH value on metal release and weight loss in simulated body fluid and artificial saliva were determined. Pore morphology, pore size and mechanical properties of the 17-4 PH stainless steel foams were close to human cancellous bone.     

Hydrolysis of kenaf (Hibiscus cannabinus L.) stems by catalytical thermal treatment in subcritical water

The present study was designed to solubilize/hydrolyze lignocellulosic biomass of kenaf stems in subcritical water, in an environmentally friendly manner. The hydrolysis efficiency was examined with respect to several parameters such as sonication of biomass-water mixture before thermal treatment, changing temperature and pressure of the hydrolysis process, adding carbon dioxide or nitrogen as pressurizing gas.The molar mass of polysaccharide fractions in the sonication pretreated solutions notably decreased because of effective degradation. The extent of hydrolysis was more effective at higher temperatures and under carbon dioxide atmosphere rather than nitrogen as the pressurizing gas. In comparison to untreated sample, 200 °C-subcritical water-treated kenaf stems had significant morphological and structural changes on plant cell wall surface that was further distorted at 250 °C.