Performance of G-Oil Well cement exposed to elevated hydrothermal curing conditions

G-Oil Well cement was modified by blending it with blast furnace slag and silica fume at various ratios. The hydration was carried out under the hydrothermal conditions (200 °C and 1.2 MPa) up to 7 days. TG and DTG were performed on cured pastes to identify the hydrated products, their quantity and their stability under given hydrothermal curing conditions. The microstructure of samples was observed by a scanning electron microscope. The mechanical compressive strength was determined and the pore structure was analyzed using mercury intrusion porosimeter. It was found out that the compressive strength values of blend G-Oil Well cements markedly increased with increasing blast furnace/silica ratio. The pore structure was consolidated, as demonstrated by the displacement of pore size distribution to the region of micro and nano pores.     

Nanoscale membrane electrode assemblies based on porous anodic alumina for hydrogen–oxygen fuel cell

In this paper, we demonstrate that nanoscale membrane electrode assemblies, functioning in a H₂/O₂ fuel cell, can be fabricated by impregnation of anodic alumina porous membranes with Nafion® and phosphotungstic acid. Porous anodic alumina is potentially a promising material for thin-film micro power sources because of its ability to be manipulated in micro-machining operations. Alumina membranes (Whatman, 50 μm thick, and pore diameters of 200 nm) impregnated with the proton conductor were characterized by means of scanning electron microscopy, X-ray diffraction, and thermal analysis. The electrochemical characterization of the membrane electrode assemblies was carried out by recording the polarization curves of a hydrogen–oxygen 5 cm² fuel cell working at low temperatures (25?÷?80 °C) in humid atmosphere. Our assemblies realized with alumina membranes filled with phosphotungstic acid and Nafion® reach respectively the peak powers of 20 and 4 mW/cm² at room temperature using hydrogen and oxygen as fuel and oxidizer.     

Properties of electrospun PVDF/PMMA/CA membrane as lithium based battery separator

Poly vinylidene fluoride:poly methyl methacrylate:cellulose acetate (CA) at ratios of 100:0:0, 90:10:0, 90:5:5 and 90:0:10 respectively, were successfully electrospun. These membranes were mixed to form a 12 wt% solution prepared with volume ratio 7:3 of DMAc:acetone solvents. These membranes were then analyzed using differential scanning calorimetry, scanning electron microscopy, FTIR, WAXD, pore size, porosity% and electrolyte uptake (EU)%. It was observed that the best absorption results were obtained in the presence of CA. The electrospun membrane at ratio of 90:0:10 was observed with the highest porosity of 99.1 % and EU at 323 %. It also had a 43.6 % crystallinity and a 162 °C melting temperature. It was then concluded that addition of CA improved the separator properties.     

10Be measurements at IUAC-AMS facility

An accelerator mass spectrometry (AMS) facility for measurements of ¹⁰Be has been developed by upgrading the 15UD Pelletron accelerator at Inter-University Accelerator Centre (IUAC), New Delhi. Details of the up gradation of the facilities and the measurement procedure are described briefly. Chemical processing for the separation of ¹⁰Be from manganese nodules and results of recent experiments on ¹⁰Be are presented.     

Use of ultra-filtration in organic-rich groundwater for the physical separation of thorium

During this work, size fractionation technique “ultra filtration” is used in physical speciation of thorium in organic rich groundwater. Laboratory simulated experiments were carried out to study the physical speciation of thorium in aquatic environment having elevated level of dissolved humus material classified as dissolved organic carbon (DOC). Samples were collected from organic rich environment having DOC in the range of 50–60 µg mL^?1. Th(IV) ions are extremely particle reactive having K _d value of the order of 10^5–6, hence to avoid adsorption on suspended particulate matter, spiking of the solution with Th(NO₃)₄ was carried out in ground water samples after filtering through 450 nm pore size using suction filtration. Particles in dissolved state (colloids) ranging between <450 and >220 nm were separated using suction filtration assembly having a membrane with a pore diameter of 220 nm. Thereafter, solution was sequentially passed through the ultra-filtration membranes having pore diameters of 14 nm [300 k NMWL (nominal molecular weight limit)], 3.1 nm (50 k NMWL), 2.2 nm (30 k NMWL), 1.6 nm (10 k NMWL) and 1.1 nm (0.5 k NMWL) by using “Stirred Ultra-filtration Cells”, operating in concentration mode. Thorium has only one stable oxidation state i.e. IV, under all redox conditions in natural waters and therefore, its speciation is dominated by its interaction with various fractions of DOC. Experimental results show 50–60 % of the spiked Th is in association with fraction enriched with particles of 10 k NMWL (1.6 nm) followed by fraction enriched with particle of 0.5 k NMWL and <220 nm.     

Synthesis of hexagonal zeolite Y from Kankara kaolin using a split technique

Synthesis of hexagonal zeolite Y from Kankara kaolin using a split technique is presented. The technique entails splitting kaolin to alumina and silica components. These components were further recombined to synthesize zeolite Y. The as-synthesized NaY zeolite was transformed to REY zeolite. Characterizations of the as-synthesized zeolite Y were carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) texture analysis, scanning electron microscope (SEM), transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy. Catalytic desulfurization of the as-synthesized REY zeolite was studied using microwave assisted desulfurization of model diesel. The Si/Al molar ratio of the as-synthesized NaY zeolite was 4.27. The crystallinity of the as-synthesized NaY and REY zeolites were 79.1 and 56.5% respectively. The as-synthesized NaY and REY zeolites possessed hexagonal morphology with average crystal sizes of 200 and 100 nm respectively. The specific surface area, pore volume and pore diameter of the as-synthesized NaY zeolite were 732 m² g^?1, 0.2611 cm³ g^?1 and 1.426 nm respectively. The specific surface area, pore volume and pore diameter of the as-synthesized REY zeolite were 456 m² g^?1, 0.1591 cm³ g^?1 and 1.395 nm respectively. Zeolite Y synthesized using the split technique possessed physiochemical properties comparable to the commercial zeolite Y, it was also free of quartz and competing phase impurities reported in previous works. The as-synthesized REY zeolite resulted to 79% sulfur reduction when used as a catalyst in a microwave desulfurization of model diesel at 100?°C for 15 min.     

Temperature-sensitive membranes prepared from blends of poly(vinylidene fluoride) and poly(N-isopropylacrylamides) microgels

In this study, temperature-sensitive membranes were prepared by phase transition of the mixture of the temperature-sensitive poly(N-isopropylacrylamides) (PNIPAAM) microgels and poly(vinylidene fluoride). The results of Fourier transformed infrared spectrometer, X-ray photoelectron spectroscopy, elemental analysis, and scanning electron microscope photographs indicate that the PNIPAAM microgels are distributed more in the inner membrane than on the surface. The scanning electron microscope photographs reveal the blend membranes having porous surfaces with nanometer sizes and porous cross-sections with micrometer sizes. The addition of the PNIPAAM microgels is found to improve the porosity, the pore size, water flux, as well as to enhance the hydrophilicity and anti-fouling property of the blend membranes. The blend membrane shows temperature-sensitive permeability and protein rejection with the most dramatic change at around 32 °C which is the lower critical solution temperature of PNIPAAM, when water or bovine serum albumin solution flow through. Specifically, below 32 °C, the blend membrane shows a high protein rejection ratio which decreases with increasing temperature and a low water flux which increases with increasing temperature; above 32 °C, the blend membrane shows a low protein rejection ratio which decreases with increasing temperature and a high water flux which increases with increasing temperature.     

Effect of Polyvinylpyrrolidone on Separation Performance of Cellulose Acetate-Polysulfone Blend Membranes

Blend membranes comprising cellulose acetate and polysulfone (CA/PSf) were prepared through a solution casting method using a different concentration of polyvinylpyrrolidone (PVP) as the pore former. Fourier transform infrared spectroscopy (ATR-FTIR) was used to investigate structural properties of membranes. Membranes morphology and its thermal properties were characterized by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The strength of membranes was studied by mechanical stability. The effect of PVP concentration on separation performance of the prepared membranes was studied. The separation performance of prepared membranes was tested by using an aqueous solution of cadmium metal complexed with humic acid. The results showed that an increase in the PVP concentration in the cast film from 0 to 3 wt% increased the thermal stability, water content (%), pure water flux, and solute rejection. SEM results showed that the pore size decreased but the number of pores increased on an increase in the PVP concentration.     

Enhancement of the Schottky Effect in a Si(100)—Water System Using Porous Polymeric Track-Etched Membranes

The kinetics of variation in the electronic work function (EWF) of single-crystal silicon Si(100) exposed to liquid water is studied. It is shown that immersing porous film track-etched membranes (TEMs) with pore sizes of 3.0–0.1 μm in water containing Si(100) considerably reduces the EWF of single-crystal silicon. It is found that a similar effect is observed when TEMs in the form of caps are held over the surface of water containing Si(100) at a distances of around 1.5–2.0 cm. It is speculated that the occurrence of a developed surface of TEMs in an open system changes the supramolecular structure of the water and leads to the formation of associates (H₂O)_n with increased dipole moments (compared to molecular moments), enhancing the Schottky effect during sorption on Si(100) surfaces.     

pH‐induced on–off switching of polycarbonate track‐etched membranes by plasma‐induced surface grafting

Surface functionalization of the plasma‐pretreated polycarbonate (PC) track‐etched membranes via plasma‐induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore‐filling ratio, the pore diameters of PAAc‐grafted membranes became smaller. The PC‐g‐PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH‐valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermoanalytical Studies of Polymeric Membranes for Immunoisolation

Preliminary studies concerning characterization of the structure of polymeric membranes for immunoisolation are reported. Laboratory-made cellulosic and polyurethane membranes for immunoisolation were investigated. Differential scanning calorimetry (DSC) was applied to determine the membrane structure, e.g. the pore diameter. The thermoanalytical measurements were carried out with a Perkin Elmer DSC 7 equipped with a CCA 7 cooling accessory. Diffusive transport across the hollow fiber membrane was evaluated in vitro by using albumin, creatinine and vitamin B₁₂. It was concluded that the DSC method is a useful tool for characterization of polymeric membranes for immunoisolation. Methodology, including experimental conditions, is proposed for capillary membranes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Membrane characterization and solute diffusion in porous composite nanocellulose membranes for hemodialysis

The membrane and solute diffusion properties of Cladophora cellulose and polypyrrole (PPy) functionalized Cladophora cellulose were analyzed to investigate the feasibility of using electroactive membranes in hemodialysis. The membranes were characterized with scanning electron microscopy, ζ-potentiometry, He-pycnometry, N₂ gas adsorption, and Hg porosimetry. The diffusion properties across the studied membranes for three model uremic toxins, i.e. creatinine, vitamin B12 and bovine serum albumin, were also analyzed. The characterization work revealed that the studied membranes present an open structure of weakly negatively charged nanofibers with an average pore size of 21 and 53 nm for pristine cellulose and PPy-Cladophora cellulose, respectively. The results showed that the diffusion of uremic toxins across the PPy-Cladophora cellulose membrane was faster than through pure cellulose membrane, which was related to the higher porosity and larger average pore size of the former. Since it was found that the average pore size of the membranes was larger than the hydrodynamic radius of the studied model solutes, it was concluded that these types of membranes are favorable to expand the Mw spectrum of uremic toxins to also include conditions associated with accumulation of large pathologic proteins during hemodialysis. The large average pore size of the composite membrane could also be exploited to ensure high-fluxes of solutes through the membrane while simultaneously extracting ions by an externally applied electric current.     

Electrospun cellulose acetate/poly(vinylidene fluoride) nanofibrous membrane for polymer lithium-ion batteries

The membranes for gel polymer electrolyte (GPE) for lithium-ion batteries were prepared by electrospinning a blend of poly(vinylidene fluoride) (PVdF) with cellulose acetate (CA). The performances of the prepared membranes and the resulted GPEs were investigated, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), porosity, hydrophilicity, electrolyte uptake, mechanical property, thermal stability, AC impedance measurements, linear sweep voltammetry, and charge–discharge cycle tests. The effect of the ratio of CA to PVdF on the performance of the prepared membranes was considered. It is found that the GPE based on the blended polymer with CA:PVdF =2:8 (in weight) has an outstanding combination property-strength (11.1 MPa), electrolyte uptake (768.2 %), thermal stability (no shrinkage under 80 °C without tension), and ionic conductivity (2.61 × 10^?3 S cm^?1). The Li/GPE/LiCoO₂ battery using this GPE exhibits superior cyclic stability and storage performance at room temperature. Its specific capacity reaches up to 204.15 mAh g^?1, with embedded lithium capacity utilization rate of 74.94 %, which is higher than the other lithium-ion batteries with the same cathode material LiCoO₂ (about 50 %).     

Anodic alumina membranes with defined pore diameters and thicknesses obtained by adjusting the anodizing duration and pore opening/widening time

The through-hole porous anodic aluminum oxide (AAO) membranes were fabricated by a simple two-step anodization of aluminum in 0.3 M oxalic acid, 0.3 M sulfuric acid, and 2 wt.% phosphoric acid solutions under different operating conditions followed by the removal of the remaining Al substrate and the pore opening/widening process. The effect of duration of the second anodizing step on the thickness of the porous oxide layer and the influence of other anodizing conditions such as applied voltage, type of electrolyte, and purity of the substrate on the rate of porous oxide growth were discussed in detail. The pore opening procedure for all synthesized membranes was optimized, and the influence of the duration of chemical etching on structural features of AAO membranes, especially pore diameter, was studied. The rate of pore widening was established for AAO membranes formed in various anodizing electrolytes and for different temperatures of 5 wt.% H₃PO₄ used for alumina dissolution.

     

Structural and performance studies of poly(vinyl chloride) hollow fiber membranes prepared at different air gap lengths

Poly(vinyl chloride) hollow fiber membranes were prepared by the dry/wet and wet/wet spinning technique at different air gap lengths keeping all other spinning parameters constants. Mean pore size, pore size distribution and mean roughness of both the internal and external surfaces of the hollow fibers were determined by atomic force microscopy. Cross-sectional structure was studied by scanning electron microscopy. Ultrafiltration experiments of pure water and aqueous solutions of different solutes having different molecular weights (bovine serum albumin, polyethylene glycol and polyvinyl pyrrolidone) were carried out. It was found that the inner and outer diameters of the PVC fiber membranes decreased with the increase of the air gap distance due to the gravitational force effect. The hollow fiber membranes prepared without and with air gap distances up to 7 cm exhibited a quite symmetric cross-structure consisting of four layers, two small finger-like structure layers at both edges of the hollow fibers and two larger finger-like voids mixed with macrovoids layers in the middle of the cross-section. The outer-middle layer thickness decreased when the air gap distance was increased to 10 cm and disappeared from the cross-section of the hollow membranes prepared with higher air gap lengths than 15 cm. For all dry/wet spun PVC hollow fibers, the outer pore size and the pure water permeation flux both increased with the increase of the air gap distance. In contrast, the solute separation factor decreased with the air gap distance. This was related to the pore size of the external surface of the PVC hollow fibers.     

Measurement of neutron-capture cross section and capture γ-ray spectrum of 105Pd(n,γ)106Pd reaction

We measured the neutron-capture cross section and the capture γ-ray spectrum of the ¹⁰⁵Pd(n,γ)¹⁰⁶Pd reaction with about 550 keV neutrons produced from the ⁷Li(p,n)⁷Be reaction at a 3-MV Pelletron accelerator. The capture yields of the palladium or gold sample were obtained by applying a pulse-height weighting technique to the corresponding net capture γ-ray pulse-height spectra. The neutron-capture cross section of the ¹⁰⁵Pd(n,γ)¹⁰⁶Pd reaction was determined with errors less than 5 % by using the standard capture cross sections of ¹⁹⁷Au. The neutron-capture γ-ray spectrum was obtained by unfolding the observed capture γ-ray pulse-height spectra. Theoretical calculations of cross sections and γ-ray spectra with the Empire code have been performed by utilizing the Hauser-Feshbach statistical model. The calculated results have a good agreement with present measurements.     

The Preparation and Applications of One Biodegradable Liquid Film Mulching by Oxidized Corn Starch-Gelatin Composite

Degraded gelatin (Gel) and oxidized corn starch (OCS) as abundant, recyclable, and biodegradable materials can be applied to agricultural production, which has been investigated in this research. Firstly, the prepared oxidized corn starch-gelatin (OCS-Gel) composite material was characterized through a Fourier transform infrared spectrometer (FT-IR), a scanning electron microscope (SEM) picture, and a thermogravimetric analysis (TGA). The OCS-Gel was then used as a liquid film mulching for agricultural production, and the application performances (hygroscopicity, permeability, water retention, etc.) of the OCS-Gel were measured. Finally, the planting rapeseed experiments were carried out, and the germination and growing state of the rapeseed seeds were observed. The results from the structural analysis indicated that OCS-Gel enriches pore structure and exhibits high thermal stability up to 324.8 °C. In the application experiments, the OCS-Gel showed excellent properties of water-absorbing and water-retention and low permeability. In addition, the germination rate of the rapeseed seed reached 80 %, and the height of rapeseeds obviously increased in pot experiments after adding the liquid film mulching.     

Analysis of blood serum of lung cancer patients using particle induced X-ray emission

Trace elemental imbalance in human beings is postulated to exert action, directly or indirectly, on the carcinogenic process. The objective of this study was to evaluate the levels of trace elements in blood serum samples of lung cancer patients and analyze their alteration with respect to healthy controls. Particle induced X-ray emission (PIXE), a well established method for elemental analysis, was used to identify and quantify trace elements in the blood serum samples of the studied groups. The PIXE measurements were carried out using 2.5 MeV collimated proton beam from the 3 MV Tandem Pelletron Accelerator at Ion Beam Laboratory, Institute of Physics, Bhubaneswar, India. The serum of the cancerous group displayed increased concentrations of Ti, Ni, and Cu but lowered concentrations of V, Cr, Mn, Fe, Co, Zn, and Se. Statistically significant differences were found for serum Cr (p < 0.01), Fe (p < 0.0005), Ni (p < 0.05), Cu (p < 0.00005), and Zn (p < 0.0005) between the two studied groups. The copper to zinc ratio for the lung cancer group was 2.24 ± 0.39, which was almost three times the value for normal subjects (0.77 ± 0.14). The observed alterations are discussed with respect to the possible mechanisms by which these elements might influence the carcinogenic process. Significant reduction in mortality from lung cancer can be achieved by advances in early diagnosis and implementation of multidisciplinary treatment programmes leading to improvement of survivorship and better quality of life. It is expected that similar studies from all corners of the world would ultimately lead to the development of novel therapeutic agents to treat lung cancer.     

Hydraulic and osmotic permeabilities of water and water/sucrose solutions through cellophane membranes

Measurements were made of different transport phenomena in cellophane membranes, using a specially designed device. The aqueous, hydraulic permeability was studied over a range of temperatures between 30 and 50°C. The hydraulic permeability/temperature relationship was found to be linear. The use of sucrose solutions of equal concentration in the two phases on either side of the membrane produced a considerable variation in the hydraulic permeability when the solution concentrations were greater than 0.1 M. Osmotic flow experiments were carried out for sucrose/water solutions, and the coefficient of osmotic permeability was found to be independent of the solution concentrations separated by the membrane within the range of concentrations studied (up to 0.2 M). The equivalent pore radius was calculated for the membranes used; these values are higher than that of the molecular diameter of water. The reflection coefficient was calculated for one of the membranes used and a value of 0.077 was obtained.     

Structural studies of nanosized porous membrane catalytic systems highly active in dry reforming of biomass conversion products

The structures of porous ceramic membrane catalytic systems exhibiting high activity in dry reforming of biomass conversion products (methane, hydrocarbons C₂?CC₄, and alcohols) to a hydrogen-containing gas were studied. The membrane catalytic systems represent porous inorganic membranes (supports) prepared by self-propagating high-temperature synthesis and modified by nanosized metallocompex components, which are uniformly distributed in the internal pore volume. Structural studies were carried out using scanning electron microscopy with energy dispersive analysis, transmission electron microscopy, temperature-programmed reduction with hydrogen, and X-ray diffraction analysis.