Synthesis,characterization, and properties of intercalated poly(2‐ethyl hexylacrylate)/silicate nanocomposites: XRD,TEM, IR,TGA, superabsorbency,pressure‐sensitive adhesion,and biodegradation

Poly(2‐ethyl hexylacrylate) (PEHA)/silicate composites were synthesized by the emulsion polymerization of ethyl hexylacrylate (EHA) in the presence of sorbitol and the composites were analyzed to be of nano order. The nanocomposites so prepared were shown to be intercalated by X‐ray diffraction, transmission electron microscopy, and infrared spectroscopy. The thermal stability of the nanocomposites was found to be appreciably increased. These nanocomposites are potentially suitable for novel uses such as pressure‐sensitive adhesives and superabsorbents. The biodegradability and superabsorbency of these nanocomposites were evaluated for their commercial potential. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1007–1011, 2004     

Deformation and fracture of CeO2-stabilized zirconia ceramics. I. Strength and deformability

Investigations of the strength and deformability of four types of zirconia-base ceramics stabilized by 9% CeO₂ (9Ce — TZP) and having different grain sizes (from 1.4 to 3.0 µm) are described. Under mechanical loads these materials exhibit avalanche formation of wide transformation zones. A correlation is established between the special features of the formation of such zones, the deformability of specimens, the the acoustic emission in them, and the grain composition of the material.Translated from Ogneupory, No. 1, pp. 8 – 12, January, 1995.     

Fly ash—a potential source of soil amendment and a component of integrated plant nutrient supply system

In sub-tropical climate the high rainfall and high temperature is responsible for low soil productivity due to losses of bases and low organic matter content in soil. In acid lateritic soil low availability of P and high content of Al and Fe posses nutritional imbalance which is generally corrected by lime materials. Alkaline fly ash can be used in such problematic soil as an amended material and also it acts as source of plant nutrition for crop production. An attempt was made to develop an integrated plant nutrient supply system utilizing the fly ash along with other organic wastes like paper factory sludge, farm yard manure, crop residue and chemical fertilizers for rice-peanut cropping system. Direct and residual effects of fly ash were assessed based on crop yield, nutrient uptake and changes in soil characteristics. The application 10 t ha⁻¹ of fly ash in combination with organic sources and chemical fertilizer increased the grain yield and nutrient uptake of rice, and pod yield of peanut compared to chemical fertilizers alone. The heavy metal contents in plant and soil system was analyzed and found to remain below the permissible level. The results indicated that fly ash could be applied safely to tropical agro eco-systems for retaining productivity of acid lateritic soil.     

CZTS synthesis in aqueous media by microwave irradiation

Copper zinc tin sulfide (Cu₂ZnSnS₄, CZTS), a p-type semiconductor composed of non-toxic earth abundant elements, is a promising material for absorber layer application in thin film solar photovoltaics. The present work describes a relatively faster and reliable microwave irradiation technique to prepare CZTS powder in aqueous media. The CZTS phase of the as-synthesized powder was confirmed by X-ray diffraction and Raman spectroscopy. Optical properties i.e. band gap determined from Tauc plot of the optical absorption spectrum measured by UV–Vis spectroscopy was 1.27 eV, which is suitable for absorbing the solar radiation. The particle morphology studied under SEM and TEM analysis was found to be a 3D flower-like nanostructure formed from 2D layers of CZTS crystals. Further, the most probable mechanism for the formation of CZTS phase is explained.     

A higher-order polynomial shear deformation theory for geometrically nonlinear free vibration response of laminated composite plate

In this paper, a nonlinear analysis for large amplitude free vibration of laminated composite plates is developed using higher-order shear deformation theory. The effect of all higher-order terms arising from nonlinear strain-displacement relations are included in the formulation and present plate theory exhibits traction-free surface of the laminated plate in von-Karman sense. A finite element procedure considering a C° continuous isoparametric nine-node rectangular element is implemented for nonlinear model. The accuracy of the theory is validated with some available theory for different aspect ratio, modular ratio, number of layers, ply orientations, etc. through some numerical examples.     

Effect of semicrystalline polymers on self-emulsifying solid dispersions of nateglinide: in vitro and in vivo evaluation

This study was undertaken to improve solubility and bioavailability of nateglinide by preparation of stable self-emulsifying solid dispersions (SESDs). The influence of semicrystalline polymers (poloxamer 407, gelucire 50/13) and method of preparation on dissolution behavior, in vivo performance and stability of nateglinide SESDs were investigated. After optimization, SESDs were prepared at 1:5 weight ratio of nateglinide and polymer individually. All the SESDs were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. Aqueous solubility of nateglinide was enhanced by 91.82-fold. The SESDs (poloxamer 407-based solid dispersions) achieved rapid and complete drug release (～100% within 45?min) at pH 2. The improved dissolution appeared to be well correlated with the enhanced bioavailability of nateglinide in rabbits. After oral administration of SESDs (poloxamer 407-based solid dispersions), C_max and AUC of nateglinide were increased by ～2.92 and 1.77-folds, respectively, signifying the effectiveness of solid dispersions to improve the bioavailability of nateglinide. Stability during storage was established to show prevention of recrystallization. In conclusion, SESDs with poloxamer 407 in solvent method appeared to be an economic and promising technique to improve the dissolution, bioavailability, and stability of nateglinide.     

New horizons in spectroelectrochemical measurements: optically transparent carbon electrodes

Given the useful electroanalytical properties of carbon electrodes, having an optically transparent material could lead to new measurement paradigms that combine electrochemical and spectroscopic measurements.     

Optically transparent diamond electrode for use in ir transmission spectroelectrochemical measurements

A new analytical spectroelectrochemical methodology is reported on that utilizes an optically transparent boron-doped diamond thin film. The film was deposited on undoped Si by microwave-assisted chemical vapor deposition using a 4-h growth with a 0.5% CH4/H2 source gas mixture and 2 ppm B2H6 added for boron doping. The thin-film electrode possessed a transparency of 40-60% in the mid- and far-IR regions of the electromagnetic spectrum. The physical, electrical, optical, and electrochemical properties of the electrode were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, four-point probe electrical resistance measurements, IR spectroscopy, and cyclic voltammetry. The film's electrochemical behavior was evaluated using both aqueous (Fe(CN)(6)3-/4-, methyl viologen, Ru(NH3)(6)3+/2+, and IrCl(6)2-/3-) and nonaqueous (ferrocene) redox systems. The film exhibited a low and stable background current and a nearly reversible voltammetric response for all these redox systems. The diamond/Si optically transparent electrode (OTE) and a thin-layer transmission cell were used to record the spectroelectrochemical response for 10 mM Fe(CN)(6)3-/4- in 1 M KCl. Difference IR spectra (oxidized minus reduced), recorded at various applied potentials, showed that the CN vibrational mode at 2039 cm-1 for Fe(CN)(6)4- reversibly shifted to 2116 cm-1 upon oxidation to Fe(CN)(6)3-, as expected. Difference IR spectra (oxidized minus reduced) were also recorded for 20 mM ferrocene in 0.1 M TBABF4/CH3CN. A shift of the C-H bending mode of the cyclopentadienyl ring from 823 to 857 cm-1 occurred upon oxidation of ferrocene to ferricenium. The key finding from the work is that the diamond OTE provides sensitive, reproducible, and stable spectroelectrochemical responses for aqueous and nonaqueous redox systems in the mid- and far-IR.     

Clinical assessment of CYP2D6-mediated herb-drug interactions in humans: effects of milk thistle, black cohosh, goldenseal, kava kava, St. John's wort, and Echinacea

Cytochrome P450 2D6 (CYP2D6), an important CYP isoform with regard to drug-drug interactions, accounts for the metabolism of approximately 30% of all medications. To date, few studies have assessed the effects of botanical supplementation on human CYP2D6 activity in vivo. Six botanical extracts were evaluated in three separate studies (two extracts per study), each incorporating 16 healthy volunteers (eight females). Subjects were randomized to receive a standardized botanical extract for 14 days on separate occasions. A 30-day washout period was interposed between each supplementation phase. In study 1, subjects received milk thistle (Silybum marianum) and black cohosh (Cimicifuga racemosa). In study 2, kava kava (Piper methysticum) and goldenseal (Hydrastis canadensis) extracts were administered, and in study 3 subjects received St. John's wort (Hypericum perforatum) and Echinacea (Echinacea purpurea). The CYP2D6 substrate, debrisoquine (5 mg), was administered before and at the end of supplementation. Pre- and post-supplementation phenotypic trait measurements were determined for CYP2D6 using 8-h debrisoquine urinary recovery ratios (DURR). Comparisons of pre- and post-supplementation DURR revealed significant inhibition (approximately 50%) of CYP2D6 activity for goldenseal, but not for the other extracts. Accordingly, adverse herb-drug interactions may result with concomitant ingestion of goldenseal supplements and drugs that are CYP2D6 substrates.     

CFD analysis of heat transfer in hexagonal subchannels of super fast reactor in upward flow

A super fast reactor is a fast spectrum, supercritical, water‐cooled reactor. This paper represents CFD analysis of heat transfer in hexagonal subchannels of super fast reactor using FLUENT in ANSYS. The numerical simulation of grid stability was done by considering different mesh sizes and the turbulence model for heat transfer of supercritical water was also carried out and compared with the experimental data. RNG k‐? turbulence model with enhanced wall treatment was considered for simulations. Heat transfer and heat generation rate analysis of the outer surface rod wall is carried out with different subchannels by changing various parameters like boundary conditions and pitch‐to‐diameter ratio. The analyses reveal that the outer surface of the rod wall temperature decreases with increase in pitch‐to‐diameter ratio. Maximum coolant temperature rises in edge subchannels more than corner subchannels. Further analysis is carried out with different mass fluxes. Increases in mass flux has minimal effect on the maximum rod wall surface temperature. Maximum cladding surface temperature for the corner subchannel is less compared to the edge subchannel. Heat generation rate also decreases with increase in pitch‐to‐diameter ratio. This paper also investigates the buoyancy effect on subchannels with varying heat flux as boundary conditions considering constant mass flux.