Mesoporous silica/polyphosphoric acid (SBA-15/PPA) nanocomposites for acylation of naphthalene

Silica-polyphosphoric acid nanocomposites (SBA/PPA) were synthesized via direct and post-functionalization of ordered mesoporous SBA-15 materials with PPA. The catalytic studies for acylation of naphthalene in the liquid phase showed very high selectivity of 2-acylated product (A) over direct functionalized SBA/PPA nanocomposites.     

Shielded rectangular dielectric wave guides for millimeter wave integrated circuits

The dispersion characteristics of Insulated non-radiative dielectric guides are computed using mode matching technique. From the dispersion characteristics the dielectric loss conductor loss and wave impedances are derived. Effect of metallic walls on trapped insulated image guide are also discussed. The dimensions of Insulated non radiative dielectric guide are same as that of rectangular metallic wave guide at ka band.     

Faradaic rectification study of cadmium(II)-cadmium in different supporting electrolytes

The Faradaic rectification theory has been extended to the reaction accompanied with multiple electron charge transfer for metal ion—metal solid reactions. The theoretical formulations have been applied for determining the rate constants for each of the two steps ie Cd²⁺ +e Cd⁺ and Cd⁺ +e Cd in the Cd²⁺/Cd(s) reaction. The second step reaction is found to be thousand times slower as compared to the first step reaction and it is in control of the overall rate of reaction. On the basis that the second step of the reaction is overall in control of the reaction, the values of the rate constant determined by applying Delahay's formulations, are found to vary appreciably from those obtained from the present theoretical treatment. The values of rate constant for both the steps in different supporting electrolytes have been obtained and the results have been discussed.     

Improvement in high stress abrasive wear property of steel by hardfacing

High stress abrasive wear behavior of mild steel, medium carbon steel, and hardfacing alloy has been studied to ascertain the extent of improvement in the wear properties after hardfacing of steel. High stress abrasive wear tests were carried out by sliding the specimen against the abrasive media consisting of silicon carbide particles, rigidly bonded on paper base and mounted on disk. Maximum wear was found in the case of mild steel followed by a medium carbon alloy steel and a hardfacing alloy. Different compositions of steels and constituent phases present led to different wear rates of the specimen. The extent of improvement in wear performance of steel due to hardfacing is quite appreciable (twice compared to mild steel). Microstructural examination of the wear surface has been carried out to understand the wear mechanism.     

In-situ atomic force microscopic study of reverse pulse plated Cu/Co-Ni-Cu films

Cu/Co-Ni-Cu films have been electrochemically synthesized in a single bath using a pulse deposition technique. The results of cyclic voltammetry investigation of the electrodeposition process have been used to optimise bath composition and pulse deposition parameters. The results of in-situ examination of the surface morphology using Atomic Force Microscopy (AFM) have been presented to show reduction in surface roughness following pulse deposition. Pulse plated multilayers of Cu/Co-Ni-Cu have also been characterised using Glancing Angle X-ray Diffraction (GAXRD) studies.     

Separation of ceramic particles from aluminium metal-ceramic composites

An improved method for separation and quantitative analysis of ceramic particles in aluminiumceramic mixture and cast materials is given. The mixture containing H₂SO₄, HNO₃ and HCI has been found to be most efficient in the separation process. Mixtures containing other acids have been shown to be unsuitable. Optical and scanning electron micrographs of acid-treated aluminium-graphite and talc samples are presented.     

SPECIFIC HEAT OF SOYBEAN

The specific heat of soybean, determined by the method of mixtures, exhibited linear positive correlation with moisture content in the moisture range from 8.1 to 25% d.b. for the mean temperature of 315 K and can be expressed in the form as Cp=1.444 (1 + 4.06 × 10⁻²M). The specific heat values increased from 1.926 to 2.912 kj/kg-K in the given moisture range. Further, the specific heat values obtained in the present study when compared with the values predicted by the other empirical methods indicated the close approximation of observed and estimated values.     

Role of Cenosphere Addition on Dielectric Properties of Sisal Fiber-Polypropylene Composites

This research investigates the influence of addition of porous additives on dielectric constant of polypropylene. Composite composed of PP matrix with sisal fiber having cylindrical pores and cenospheres having spherical pore, presents low dielectric constant. A new relation concerning porosity is proposed by modifying the usual mixing rule to predict the dielectric constant of PP composite. This research presents the dielectric properties of sisal fiber-reinforced PP composites with and with out cenospheres. Treated and untreated cenospheres with different concentration were loaded in chopped sisal fiber-reinforced polypropylene. The loading of the polypropylene with the sisal fiber, increases the dielectric constant ε′ and improves the ac conductivity σ_ac. The effect of temperature on the dielectric spectrum of polypropylene composites was investigated in the frequency range ranging from 1–10 kHz. Sisal fiber-reinforced polypropylene composites having 20% sisal fiber with and without cenospheres were developed and electrical properties such as dielectric constant (?′), dissipation factor (tanδ) and ac conductivity (σ_ac) of these composites were determined. Dielectric constant, tan δ, and a.c. conductivity increases with increase in temperature at different frequencies.     

CRYOGENIC GRINDING of CLOVES

Studies on cryogenic grinding of clove were conducted to observe influence of parameters, viz., grinding temperature, rotor speed, sieve size and feed rate on sieve choking characteristics, particle size distribution, volume mean diameter, specific energy consumption and volatile oil content. It was observed that the clove could be successfully ground at temperatures below −50C without any deposition over the sieve surface. an increase in temperature in the cryogenic range (-110 to −50C) had no significant effect on volatile oil content, whereas temperatures in the range of 55 to 85C significantly reduced the volatile oil content from 11.0 to 9.3 mL/100g. Thus, cryogenic grinding resulted in 29.5% more volatile oil in comparison to that of ambient grinding. When grinding temperature was increased from −110 to −50C, there were increases in particle size for the same cumulative volume fraction. the volume mean diameter of clove powder increased quadratically from 119 to 153 μm with increases in temperature from −110 to −50C at constant feed rate of 1.5kg/h, rotor speed of 69 m/s and sieve opening size of 0.5 mm. It increased quadratically from 119 to 140 μm with increase in feed rate from 1.5 to 6 kg/h with the grinding temperature constant at −110C. the specific energy consumption during grinding increased quadratically from 62 to 81 kJ/kg with increases in grinding temperature from −110 to −50C at a typical feed rate of 1.5 kg/h, rotor speed of 69 m/s and sieve size of 0.5 mm. The specific energy consumption increased quadratically from 62 to 85 kJlkg with the increase in feed rate from 1.5 to 6 kg/h with constant grinding temperature of -IlOC, rotor speed of 69 m/s and sieve opening size of 0.5 mm.