Threshold and compactification effects in GUTS

We review general results on threshold effects and their implications on GUTs in the context of LEP data. Among the blooming grand-desert models, threshold effects are computed in the presence of a single real scalar ζ (3, 0, 8) with M_ζ≃10¹⁰ GeV leading to experimentally testable predictions on the proton lifetimeτ _p in SU (5) and, in addition, small neutrino masses in SO (10) needed for the solar neutrino flux and the dark matter of the universe. The fine structure constant matching at M_Z is ensured by including threshold effects on the unification coupling. In the minimal SUSY SU (5) such effects at the GUT scale modify the prediction of the supersymmetric mass threshold near the TeV scale and the precision measurments of the Standard Model couplings at M_Z probe into the superheavy mass spectrum. Consequences of theorems proved very useful for threshold, compactification and multiloop effects are discussed. It is noted that in a class of GUTs the highest intermediate scale M_I above which G_224P becomes a good symmetry is not affected by the GUT threshold or compactification effects or multiloop contributions in the range M_I-M_U. But spontaneous compatification effects can decrease the intermediate scale drastically in models where parity and SU(2)_R breakings are decoupled. Low mass W_R-bsosns are permitted in models with decoupled parity and SU (2)_R breakings.     

Asymptotic bounds on pion form factor

A technique recently developed for inelastic electron proton scattering is applied for inelastic electron pion scattering. It is found that all the derivatives of off-shell form factor of pion nears=m _π ² and for largeQ ² are bounded from above, provided that the dispersion relation for the form factor requires no more than one subtraction. The elastic pion form factor is bounded by [lnQ ²] ^c /Q ², wherec is any positive constant.     

Dielectric and impedance spectroscopy of rare earth-based tungsten bronze ceramic

The ceramic oxide Na₂Pb₂Gd₂W₂Ti₄Ta₄O₃₀ (NPGWT) was synthesized by the solid solution route. The formation of compound was checked by using X-ray diffraction and scanning electron microscope study. It is observed from both the studies that the material is a single phase and highly dense. The preliminary temperature variation of the dielectric study reveals ferroelectric to paraelectric phase transition much above the room temperature. The polarization study of the material further confirms the presence of ferroelectricity in the studied compound. The transport property of the material was carried out by using the impedance spectroscopy technique. From both impedance and modulus analysis, it is confirmed that conduction mechanism in the material is due to the hopping motion of charge carrier. To strengthen the hopping motion of charge carrier in the material frequency dependence, ac conductivity is carried out.     

Solar Light Induced Photocatalytic Degradation of Pollutants over Titania Pillared Zirconium Phosphate and Titanium Phosphate

Titania pillared zirconium phosphate (ZrP) and titanium phosphate (TiP) were prepared by intercalating Ti (IV) isopropoxide sol in the interlayers of the mono sodium form of the corresponding metal phosphate. The sol-intercalated samples were activated at various temperatures and characterized by XRD, UV–vis DRS, FTIR, BET-surface area, BJH-pore size distribution and acid sites measurement. Basal spacing and surface area analyses revealed that highest amount of pillaring has taken place with 2 and 4 wt.% titania loading for ZrP and TiP, respectively. The photocatalytic degradation of 4-nitrophenol (4-NP), phenol, methylene blue (MB) and hexavalent chromium (Cr (VI)) was studied in aqueous solution over the neat as well as pillared materials under solar irradiation. Catalytic activity tests revealed that hexavalent chromium (Cr (VI)) and 4-nitrophenol (4-NP) were completely degraded under acidic conditions, whereas, the same was observed in almost neutral conditions for phenol and methylene blue (MB) over 0.6 g/L of catalyst.

Total synthesis of hyacinthacine A1, a glycosidase inhibitor

A practical and enantioselective total synthesis of hyacinthacine A1 is achieved involving syn allylic epoxide opening with retention using Pd catalysis and "domino" hydrogenation (five steps in one pot) sequences.     

Studies on selenite adsorption using manganese nodule leached residues

Selenite adsorption on water-washed manganese nodule leached residues (WMNLR) was studied with the aim of detoxifying industrial effluents before their safe disposal into the environment. WMNLR, a solid waste material, was characterized with the help of XRD, FTIR, TG-DTA, pH(pzc), BET surface area, surface oxygen, surface hydroxyl group, and chemical analyses. The adsorption behavior of WMNLR toward selenite was studied as a function of time, pH, temperature, and concentration of adsorbate and adsorbent. Increased adsorption capacity with rise in temperature indicates that the adsorption process was endothermic in nature. Based on the thermodynamic parameters such as the Gibbs free energy change, standard enthalpy change, and standard entropy change, the adsorption process was found to be spontaneous and endothermic in nature. Adsorption followed second-order kinetics. The adsorption capacity of the material was found to be 54.6 mg g(-1) at 60 mg L(-1) of selenite concentration at pH 5 in 3 h contact time.     

Integrated Condition Monitoring of Large Captive Power Plants and Aluminum Smelters

Condition monitoring is implementation of the advanced diagnostic techniques to reduce downtime and to increase the efficiency and reliability. The research is for determining the usage of advanced techniques like Vibration analysis, Oil analysis and Thermography to diagnose ensuing problems of the Plant and Machinery at an early stage and plan to take corrective and preventive actions to eliminate the forthcoming breakdown and enhancing the reliability of the system. Nowadays, the most of the industries have adopted the condition monitoring techniques as a part of support system to the basic maintenance strategies. Major condition monitoring technique they follow is Vibration Spectrum Analysis, which can detect faults at a very early stage. However implementation of other techniques like Oil analysis or Ferrography, Thermography etc. can further enhance the data interpretation as they would detect the source of abnormality at much early stage thus providing us with a longer lead time to plan and take the corrective actions. In Large Captive Power Plants and Aluminium Smelters, Integrated Condition Monitoring techniques play an important role as stoppage of primary system and its auxiliaries (boiler, steam turbine, generator, coal and ash handling plants etc.) results into the stoppage of the entire plant, which in turn leads to loss of productivity. From economical and operational point of view, it is desirable to ensure optimum level of system availability.     

Surface characterization and catalytic evaluation of copper-promoted Al-MCM-41 toward hydroxylation of phenol

The Mobil Composition of Matter No. 41 (MCM-41) containing Cu and Al with Si/Al ratios varying from 100 to 10 and 1 to 6 wt.% of Cu was synthesized under hydrothermal and impregnation conditions, respectively. The samples were characterized by nitrogen adsorption–desorption measurements, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and ²⁹Si and ²⁷Al magic-angle spinning–nuclear magnetic resonance (MAS–NMR) spectra. X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. TPR patterns show the two-step reduction of Cu species. TPD study shows that Cu-impregnated Al-MCM-41 samples are more acidic than Al-MCM-41. From the MAS–NMR it was confirmed that most of the Al atoms are present tetrahedrally within the framework and some are present octahedrally in extraframework position. Impregnation of Cu shifted Al to the extraframework position. The catalytic activity of the samples toward hydroxylation of phenol in aqueous medium was evaluated using H₂O₂ as the oxidant at 80 °C. The effects of reaction parameters such as temperature, catalyst amount, amount of H₂O₂, and solvent were also investigated. Sample containing 4 wt.% copper-loaded Al-MCM-41-100 showed high phenol conversion (78%) with 68% catechol and 32% hydroquinone selectivity.     

Effect of sulfate on the surface and catalytic properties of iron-chromium mixed oxide pillared clay

Sulfate-supported iron-chromium mixed oxide pillared clay was prepared varying the sulfate loading from 1 to 5 wt% by the incipient wetness method and characterized by low-angle XRD, BET surface area, and ammonia TPD. All the samples were found to be stable up to 500 degrees C having the basal spacing 17.7 A even after sulfate impregnation. Formation of strong Lewis acid sites and decrease in the number of Br?nsted acid sites due to the sulfate loading were observed from the ammonia TPD curve. Catalytic properties of the sulfated materials were evaluated with the help of methanol conversion and aromatic alkylation reactions and correlated with the surface area and TPD results. For methanol conversion, decomposition product selectivity increases due to the sulfate addition. A negligible decrease in the surface area and a substantial increase in the catalytic activity were observed due to the sulfate loading of 1-2 wt%. However, a significant decrease in the surface area as well as catalytic activity was observed for the 3 wt% and above sulfate loaded samples which may be due to the partial blockage of pores by excess sulfate. Results shows the importance of acidity of the material due to sulfate loading (up to 2 wt%) and thus can be used as a better acid catalyst.     

Preparation and characterization of Mg-Al hydrotalcite-like compounds containing cerium

Hydrotalcite-like compounds (HTlcs) containing Mg(2+), Al(3+), and Ce(3+) in the hydroxide layer and with carbonate as charge-balancing anion have been prepared by a co-precipitation (at constant pH) method. The Al/Ce ratio in the final product depends on the concentration in the initial solution. The crystallinity of the layered materials decreases with the increase in cerium content, probably, due to the distortions introduced by the large difference in the ionic radii of the cations. All the synthesized materials were characterized by XRD, FT-IR spectroscopy and TG/DTA. The textural properties were determined from low-temperature nitrogen adsorption-desorption measurements.