Eigenvalue approach to study the effect of rotation and relaxation time in generalized magneto-thermo-viscoelastic medium in one dimension

The fundamental equations of the problems of generalized thermoelasticity with one relaxation parameter including heat sources in infinite rotating magneto-thermo-viscoelastic media have been derived in the form of a vector matrix differential equation in the Laplace transform domain for a one dimensional problem. These equations have been solved by the eigenvalue approach to determine deformations, stress, and temperature. The results have been compared to those available in the existing literature. The graphs have been drawn to show the effect of rotation in the medium.     

Some generating functions of Jacobi polynomials

In this paper, Weisner’s group-theoretic method of obtaining generating functions is utilized in the study of Jacobi polynomialsP> _n ^(a,ß)(x) by giving suitable interpretations to the index (n) and the parameter (β) to find out the elements for constructing a six-dimensional Lie algebra.     

The first, discrete Zn4 tetrahedron with a selenium atom in the center: x-ray structure and solution study of [Zn4(mu4-Se)[Se2P(OPr)2]6

The first discrete, selenium-centered tetranuclear zinc cluster [Zn4(mu4-Se)[Se2P(OPr)2]6] was isolated and characterized. The cluster consists of six edge-bridged dsep ligands with four zinc atoms in a slightly distorted tetrahedron and a mu4-Se atom in the center. In addition, 12 mu2-bridging selenium atoms form a Se12 icosahedron. From variable-temperature 31P NMR studies, it was observed that the cluster [Zn4(Se)[Se2P(OPr)2]6] is partly decomposed to [Zn[Se2P(OPr)2]2] and the monomeric species [Zn[Se2P(OPr)2]2] is further in equilibrium with its dimer [Zn[Se2P(OPr)2]2]2.     

Paramagnetic ruthenium(III) cyclometallated complex. Synthesis, spectroscopic studies and electron-transfer properties

The reaction of Ru^II(PPh₃)₃X₂ (X = Cl, Br) with o-(OH)C₆H₄C(H)=N-CH₂C₆H₅ (HL) under aerobic conditions affords Ru^II(L)₂(PPh₃)₂, 1, in which both the ligands (L) are bound to the metal center at the phenolic oxygen (deprotonated) and azomethine nitrogen and Ru^III(L¹)(L²)(PPh₃), 2, in which one L is in bidentate N,O form like in complex 1 and the other ligand is in tridentate C,N,O mode where cyclometallation takes place from the ortho carbon atom (deprotonated) of the benzyl amine fragment. The complex 1 is unstable in solution, and undergoes spontaneous oxidative internal transformation to complex 2. In solid state upon heating, 1 initially converts to 2 quantitatively and further heating causes the rearrangement of complex 2 to the stable RuL₃ complex. The presence of symmetry in the diamagnetic, electrically neutral complex 1 is confirmed by ¹H and ³¹P NMR spectroscopy. It exhibits an Ru^II → L, MLCT transition at 460 nm and a ligand based transition at 340 nm. The complex 1 undergoes quasi-reversible ruthenium(II)—ruthenium(III) oxidation at 1.27V vs. SCE. The one-electron paramagnetic cyclometallated ruthenium(III) complex 2 displays an L → Ru^III, LMCT transition at 658 nm. The ligand based transition is observed to take place at 343 nm. The complex 2 shows reversible ruthenium(III)—ruthenium(IV) oxidation at 0.875V and irreversible ruthenium(III)—ruthenium(II) reduction at −0.68V vs. SCE. It exhibits a rhombic EPR spectrum, that has been analysed to furnish values of axial (6560 cm⁻¹) and rhombic (5630 cm⁻¹) distortion parameters as well as the energies of the two expected ligand field transitions (3877 cm⁻¹ and 9540 cm⁻¹) within the t₂ shell. One of the transitions has been experimentally observed in the predicted region (9090 cm⁻¹). The first order rate constants at different temperatures and the activation parameter ΔH^#/ΔS^# values of the conversion process of 1 → 2 have been determined spectrophotometrically in chloroform solution.     

Identification of Amino Acids with Modified Ninhydrin Reagents on Thin-Layer Chromatography Plates

JPC – Journal of Planar Chromatography – Modern TLC - The four new spray reagents (Benzoic acid and some of its parahaloderivatives) have been introduced. These reagents enable...     

Kinetics of catalyzed esterification of acetic acid with n-butanol using carbonized agro-waste

The objective of this research work was to investigate the kinetics of esterification of acetic acid with n-butanol through the variation of experimental parameters. The reaction mixture was catalyzed heterogeneously by a sulfonated catalyst in batch mode of operation. The catalyst was prepared from abundantly available agro-waste, Cajanus cajan husk by chemical activation process, which produces a carbon-based solid catalyst with high surface area. The catalyst was characterized by a Brunauer-Emmet-Teller surface analyzer and Fourier transform infrared spectroscopy to know the surface morphology. Process parameters such as contact time, reaction temperature, and catalyst loading, which can influence the extent of conversion of reactants, were studied. Furthermore, the kinetic investigation was also carried out to estimate the kinetic parameters for uncatalyzed and catalyzed reaction using the second-order pseudo-homogeneous (P-H), Eley-Rideal (E-R), and Langmuir-Hinshelwood (LH) kinetic models for this research work. The kinetic parameters such as activation energy, preexponential factor, and the thermodynamic parameters such as enthalpy and entropy were estimated for uncatalyzed and catalyzed reactions using these three models. The process conditions were optimized for catalyzed and uncatalyzed reactions to obtain the maximum product yield by minimizing root mean square error of each experimental data using the MS-excel solver tool. Thus, this study reveals the high potential of an agro-waste, Cajanus cajan husk as raw material for the synthesis of catalyst. The results show that the E-R model is more appropriate for predicting the dynamic data of an esterification reaction, as the forward rate of reaction estimated using the E-R model are more modified than P-H and L-H models.     

Surfactant-promoted enhancement in bioremediation of hexavalent chromium to trivalent chromium by naturally occurring wall algae

Research on Chemical Intermediates - The discharge of hexavalent chromium [Cr(VI)] has resulted in significant pollution because of the presence of Cr(VI) oxyanions. They are highly water-soluble,...     

Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9′-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (¹H), and fluorine 19 (¹⁹F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (M_ns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λ_em peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), and their λ_em peaks were blue shifted.     

A review on sources,toxicity and remediation technologies for removing arsenic from drinking water

Arsenic is a natural element found in the environment in organic and inorganic forms. The inorganic form is much more toxic and is found in ground water, surface water and many foods. This form is responsible for many adverse health effects like cancer (skin, lung, liver, kidney and bladder mainly), and cardiovascular and neurological effects. The estimated number of people in Bangladesh in 1998 exposed to arsenic concentrations above 0.05 mg/l is 28–35 million, and the number of those exposed to more than 0.01 mg/l is 46–57 million. The estimated number of people in West Bengal, India (the border province to Bangladesh), in 1997 actually using arsenic-rich water is more than 1 million for concentrations above 0.05 mg/l and is 1.3 million for concentrations above 0.01 mg/l. The United States Environmental Protection Agency (USEPA) has estimated that 13 million of the US population are exposed to arsenic in drinking water at 0.01 mg/l. The situation has prevailed for more than 10 years and is more severe now. The USEPA lowered the maximum contaminant level (MCL) for drinking water arsenic from 50 to 10 μg/l in 2001 based on international data analysis and research. This recommendation is now on hold. The level of 10 ppb become standard in the European Union (EU) in 2001. Arsenic may be found in water flowing through arsenic-rich rocks. The source is diverse. These include the earth's crust, introduced into water through the dissociation of minerals and ores, industrial effluents to water, combustion of fossil fuels and seafoods. Arsenic-removal methods are coagulation (ferric sulfate, ferrous sulfate, ferric chloride, aluminum sulfate, copper sulfate, and calcium hydroxide as coagulants), adsorption (activated carbon, activated alumina, activated bauxite) ion exchange, bio-sorption, etc.