Kinetic Analysis and Modeling of Thermal Decomposition of Ammonia Borane

Ammonia borane (AB; NH₃BH₃) is one of the most promising materials for hydrogen storage applications, mainly due to its high gravimetric hydrogen storage capacity of 19.6 wt%. In this paper, we present an exclusive kinetic analysis of AB thermolysis. Three methods are used for kinetic analysis of the thermal decomposition of AB, namely the Kissinger method, isoconversional model‐free fitting method, and solid‐state kinetics model–based method. Finally, a need to device a new model for thermal kinetics of AB was observed and hence a new kinetic model for AB thermolysis is proposed.     

Functionalized Gold Nanoparticles – Octadecylamine Hybrid Langmuir‐Blodgett Film for Enzyme Sensor

Mediator free enzyme sensor has been fabricated by covalently immobilizing cholesterol oxidase (ChOx) onto 11‐mercaptoundecanoic acid functionalized gold nanoparticles (MUDA‐AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA‐AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM^?1 and response time of 20 s at pH 7.0.     

Bianchi Type III Cosmological Models for Barotropic Perfect Fluid Distribution with Variable <Emphasis Type="Italic">G</Emphasis> and <Emphasis Type="BoldItalic">Λ</Emphasis>

Bianchi type III cosmological model for perfect fluid distribution with variable G and Λ are investigated. To get the determinate models, we have assumed the barotropic condition p=γ ρ and shear (σ) is proportional to expansion (θ) where p is isotropic pressure, ρ the matter density and 0≤γ≤1. The physical and geometrical aspects related with the observations and singularities in the models are discussed.     

Use of microwave technology for the synthesis of organotitanium(IV) and organozirconium(IV) complexes with HPOH,HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>OH and HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>SH type of ligands

Synthesis and characterization of titanium(IV) and zirconium(IV) complexes of the types Cp₂M(Cl)(HPO), Cp₂M(HPO)₂, Cp₂M(O^∩N^∩O) and Cp₂M(O^∩N^∩S) (where M represents titanium or zirconium and HPO, O^∩N^∩O and O^∩N^∩S represent the donor sets of the ligands) have been reported. These new derivatives have been prepared by the reactions of titanocene dichloride or zirconocene dichloride with 2-hydroxy-N-phenyl benzamide(HPOH), 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazine-carboxamide (HO^∩N^∩OH) and 2-hydroxy-N-phenyl benzamide benzothiazoline (HO^∩N^∩SH) in different molar ratios. The ligands and their complexes have been characterized by the elemental analyses, conductance measurement, molecular weight determinations and spectral studies. On the basis of electronic, I.r., ¹H.-n.m.r. and ¹³C.-n.m.r. spectral studies, trigonal bipyramidal and octahedral geometries have been proposed for the resulting complexes. All the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found positive in this respect.     

A rapid field detection method for arsenic in drinking water.

In this study, a rapid colorimetric method for arsenic detection was developed. Different reagents containing magnesium turnings in combination with a series of acids were tested for arsine generation. The arsine was then allowed to react with auric chloride on Whatman filter paper No. 3, which in turn changed color. The detection time and detection limit were measured for each acid. Oxalic acid was found to be the most appropriate acid among all the acids used for detection in this study. It took 10 min to detect 10 ppb arsenic concentration and only 1 min to detect concentrations higher than 50 ppb. This method thus reduced the detection time for arsenic and has the potential to develop better field kit.     

On some liquid crystalline phases exhibited by compounds made of bent-core molecules and their mixtures with rod-like molecules

In most homologous series of compounds made of bent-core (BC) molecules, the B₂ B₁ and B₆ phases occur as the chain length decreases. We have studied binary mixtures of the compound 1,3-phenylene bis[4-(3-methylbenzoyloxy)]4-n-dodecylbiphenyl 4’-carboxylate (BC12) which exhibits the B₂ phase with the compound 4-biphenylyl 4’-n-undecyloxybenzoate (BO11) made of rod-like (R) molecules. We find the above sequence of occurrence of the B phases with increasing concentration of BOH. In this paper we describe the physical origin for the formation of these phases in both pure compounds and in the mixtures. We have also found the occurrence of the biaxial smectic A phase when the BO11 concentration is increased to 87–95.5 mol%. We also report on another binary system composed of BC12 and 4-n-octyloxy 4’- cyanobiphenyl (8OCB) made of R molecules. This system exhibits the biaxial smectic A phase down to 30°C. Using polarized infrared spectroscopy we find that the mutual orientation of the R and BC molecules in the SmA_db liquid crystal is such that the arrow axes of the BC molecules are along the layer normal of the partial bilayer smectic structure formed by the rods. We also describe unusual growth patterns obtained when the nematic phase transforms to the SmA_db phase in a mixture with 24 mol% of BC12.     

Structural Study of Lanthanide Complexes Formed with o-Vanillin Salicyloylhydrazone and o-Vanillin Paraanisidine

Abstract

Ten lanthanide complexes (Ln=La, Ce, Pr, Nd, Sm, Gd, Eu and Dy) with the title ligands have been synthesised and characterised. The structure of these complexes are assigned on the basis of IR spectra, magnetic and thermal analysis data. The IR spectra indicate that o-vanillin paraanisidine (oVPA) is a bidentate ligand coordinating through azomethine N and phenolic O whereas o-vanillin salicyloylhydrazone (oVSH) is tridentate possessing ketonic O as an additional donor site. Involvement of anions (Cl^?, Ac^?) in coordination is explored. Electronic spectra indicate weak covalent nature of metal ligand bond and various parameters β, b½, η and δ have been evaluated.     

An Exact Solution of Perfect Fluid in Isotropic Coordinates, Compatible with Relativistic Modeling of Star

We present a spherically symmetric solution of the general relativistic field equations in isotropic coordinates for perfect fluid, compatible with a super dense star modeling. The solution is well behaved for all the values of u lying in the range 0<u≤0.12. Further, we have constructed a super-dense star model with all degree of suitability and by assuming the surface density ρ _b =2×10¹⁴ g/cm³. Corresponding to u=0.12, the resulting well behaved model has maximum mass M=0.912M _Θ with radius R _b ≈11.27 km and Moment of inertia 0.97×10⁴⁵ gm?cm². The good matching of our results for Vela pulsars show the stoutness of our model.     

Exploration of polystyrene-supported 2-isobutoxy-1-isobutoxycarbonyl-1,2-dihydroquinoline (PS-IIDQ) as new coupling agent for the synthesis of 8-substituted xanthine derivatives

Polystyrene-supported 2-isobutoxy-1-isobutoxycarbonyl-1,2-dihydroquinoline (PS-IIDQ), a polymer supported covalent coupling reagent, was successfully employed for the first time in the synthesis of 8-substituted xanthine derivatives. PS-IIDQ was observed to be more efficient than IIDQ and polymer-supported carbodiimide (PS-EDC).