Synthesis and characterization of CdS doped TiO2 nanocrystalline powder: A spectroscopic study

This report aimed to study the effect of CdS doping in TiO₂ on the phase transformation of TiO₂ from anatase to rutile using X-ray diffraction (XRD) and Raman spectroscopy. CdS-doped TiO₂ nanocomposites have been prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). We have observed that contrary to bare TiO₂, phase transformation of TiO₂ from anatase to rutile is hindered when doped with CdS at high temperature. Raman spectroscopy is found to be more sensitive for detection of the surface of TiO₂ as compared to XRD.     

Gefitinib–cyclodextrin inclusion complexes: physico-chemical characterization and dissolution studies

Background: Gefitinib, an anticancer drug, has an extremely low aqueous solubility, and its oral absorption is limited by its dissolution rate. The solubility and dissolution of gefitinib can be improved by complexation with cyclodextrins (CDs). Methods: Phase solubility studies of gefitinib with hydroxypropyl βCD (HPβCD) and randomly methylated βCD (RMβCD) in n various aqueous systems was conducted to characterize the complexes in the liquid state. The inclusion complexes in the solid state were prepared by freeze-drying method and characterized by X-ray diffractometry (X-RD) and differential scanning calorimetry (DSC). Results: Gefitinib formed stable complexes with HPβCD and RMβCD in distilled water as indicated by the association rate constants (Ks) of 458.9 and 1096.2 M^?1 for HPβCD and RMβCD, respectively. The complexation of gefitinib with CDs in pH 4.5 acetate buffer indicated an A_N type of phase-solubility diagrams, whereas gefitinib and HPβCD in distilled water in the presence of polymers such as polyvinyl pyrrolidone K-30 (PVP) or hydroxypropyl methylcellulose E3 (HPMC) resulted in A_P-type phase-solubility diagrams. The solid-state amorphous complexes (as described by DSC and X-RD) showed substantial increases in the solubility and dissolution rate of gefitinib with both CDs. Further increases in the solubility and dissolution rate of the gefitinib-HPβCD freeze-dried complex were obtained by physically mixing the complex with PVP and HPMC. Conclusion: Gefitinib formed stable inclusion complexes with HPβCD and RMβCD, and the solubility and dissolution rate of the drug was significantly increased.     

Experimental validation of multiple gain combiner in single-relay cooperative FSO communication systems

In this paper, we have proposed a new combining technique named as multiple gain combiner (MGC) for single-relay cooperative FSO communication systems. The first objective of this paper is to test the experimental feasibility of single-relay cooperative FSO communication system. The next objective is to ascertain the performance of a cooperative FSO link in the presence of simulated fading effect generated by means of modified optical chopper. The last objective is to determine the performance improvement of our proposed MGC combining method over conventional equal gain combining method. Bit error rate performance of the relay system is tested for single-relay cooperative FSO link under weak and strong fading conditions simulated with the modified optical chopper, which shows that the significant performance improvement can be obtained with the use of cooperative diversity. Rsoft-Optsim with MATLAB^® co-simulation results show the same trend of performance for the same level of fading present in the system, thereby validating the fading mechanism as obtained by means of modified optical chopper.

     

The effect of using the turbulence enhancement unit before the catalytic converter in diesel engine emissions

This research focuses on reducing the toxic emissions from the exhaust by installing a turbulence enhancement unit just before the three-way catalytic converter. This unit creates turbulence in the gases flowing through the combustion chamber when fitted with the Tata Indica V2 diesel engine (1405cc). Turbulence leads to the rising in the contact area of the exhaust gases going to the catalytic converter for the reactions to take place. Experimentally, it was found that swirl venturi gives the best results in the overall emission test. Although the overall best device is swirl venturi, swirl blades also give better results on higher rpm of the engine. This paper shows the detailed research on the emission test performed.     

Asthma in the elderly: underperceived, underdiagnosed and undertreated; a community survey

Bronchial asthma is now increasingly recognized in the elderly and is associated with significant morbidity and mortality. The aims of this study were two-fold: first, to assess the prevalence and, second, to evaluate diagnostic awareness, therapeutic management and patient perception of bronchial asthma among elderly patients in the community. From the age-sex register of an urban general practice in NE England, 2004 patients aged > 65 years were eligible for inclusion. Response to an initial screening questionnaire on respiratory symptomatology was 68% (n = 1362). Of these, 869 patients had respiratory symptoms: 390 voluntarily agreed to be evaluated further including assessment of airway physiology. In this group 369/390 had obstructive spirometry and, of these, 95 patients fulfilled clinical and physiological criteria of bronchial asthma. Prevalence of asthma within this age cohort was minimally and rather crudely assigned at 4.5% (95/2004). Among the 95 patients so-defined patients with asthma [age 70 +/- 8 years (mean +/- SD), FEV1 = 0.96 +/- 0.41, 33 male, 75 life-long non-smokers], subjective awareness, perception and attribution of pulmonary symptoms were poor. Further, despite tangible evidence of reversible and significant airflow limitation, only 21 were receiving inhaled glucocorticoid therapy (median daily dose 400 micrograms). Asthma in the elderly remains poorly perceived, poorly recognized and suboptimally treated. These findings are particularly apposite in the light of current epidemiological trends in asthma mortality and morbidity in elderly age cohorts.     

High trans,trans Conjugated Linoleic Acid-Rich Triacylglyceride Production by Photo-Irradiation

Recent studies have shown that a 20 % trans,trans conjugated linoleic acid (CLA)‐rich soy oil significantly reduces heart disease and diabetes risk factors in obese rats. Furthermore, trans,trans‐CLA has been reported to have superior anti‐carcinogenic activity than other CLA isomers. Therefore, a more concentrated source of trans,trans‐CLA oil would be highly desirable. The objectives of this study were to (1) determine the yield of trans,trans‐CLA isomers resulting from photo‐irradiation of Tonalin^® (BASF Global, Florham Park, NJ, USA) and identify trans,trans‐CLA positional isomers; and (2) derive a mathematical model of kinetics of trans,trans‐CLA TAG formation from Tonalin^®. Fifty‐five percent trans,trans‐CLA rich oil was obtained in about 140 min when Tonalin^® was photo‐isomerized with 0.35 % iodine, which is almost three times more than is possible with photo‐isomerized soy oil. Photo‐isomerization of Tonalin^® requires about 2 h, compared to 12 h for photo‐isomerization of soy oil. This reaction is a first‐order reversible reaction with the forward rate constant (k_f) = 13.17 × 10^?3min^?1 and backward rate constant (k_b) = 5.334 × 10^?3min^?1. The major isomers identified were trans‐9,trans‐11‐ and trans‐10,trans‐12‐CLA.     

The optical properties of CuGa0.5In0.5Se2 thin films

CuGa_0.5In_0.5Se₂ thin films with thickness in the range 50 to 280 nm were deposited by thermal evaporation of prereacted material on glass substrates. The films were found to be polycrystalline with single phase having chalcopyrite structure as that of bulk material. The optical constants of these films were determined by transmittance and reflectance measurements at normal incidence for light in the wavelength range 400 to 1200 nm. Three characteristic energy gaps of 1.30, 1.55 and 2.46 eV were obtained from an analysis of the optical absorption spectrum. The optical constants of the films appear to be independent of the substrate temperature.     

Investigations on Romashkino asphaltic bitumen. 3. Fractionation of asphaltenes using ion-exchange chromatography

The fractionation of asphaltenes originally separated¹ from Romashkino asphaltic bitumen has been achieved by means of stepwise anion- and cation-exchange chromatography through macroreticular resins. The fractionation procedure and yields of the fractions are given. A detailed structural analysis has been made of original asphaltenes and their acid- and base-free fraction using elemental and densimetric analyses, gel-permeation chromatography and proton magnetic resonance spectroscopy. Inverse gas-liquid chromatography has also been used to detect the chemical functionality of the asphaltene fractions. Results are presented to show the effect of ion-exchange resins treatment upon the composition of asphaltenes, noting that molecular weight as well as chemical structure changes appreciably.