Contemporary review of techniques for the solution of nonlinear Burgers equation

In the present paper, a comprehensive review of the different techniques used for solving the Burgers equation has been presented along with the recent progress going in finding its solution. The main objective of this paper is not only to present a proper assessment of the previous work but also to provide readers with all fruitful existing information that can help in numerical solution of the Burgers equation, which is otherwise difficult to solve under certain assumptions. Comments are supplied with each reference cited, in order to briefly summarize the objectives of the specific analysis and the important results therein. In addition, a brief discussion of a contribution by the authors in this field has also been presented at the end.     

An Expeditious Study of the Nature of Halogen(S) at γ-Positions in Carbonyl Compounds

The detailed study, of the behaviour of di/tri halo carbonyls to act as the synthetic equivalents of corresponding mono γ-halo carbonyls, is carried out.     

Mild and Efficient PtO2-Catalyzed One-Pot Reductive Mono-N-alkylation of Nitroarenes

A mild and efficient one-pot reductive monoalkylation of nitroarenes has been described using aldehydes as alkylating agents, molecular hydrogen as a reducing agent, and PtO₂ as a catalyst in methanol. This methodology is found to be applicable for both aliphatic and aromatic aldehydes and for a wide variety of nitroarenes.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Commuications® to view the free supplemental file.     

Chemical Constituents from Fruits and Stem Bark of Celtis australis L.

Four triterpenoids named (9β,31R)‐9,25‐cyclo‐30‐propylhopan‐31‐ol ( 1 ), (3β)‐3‐hydroxy‐30‐propylhopan‐31‐one ( 2 ), (3β)‐oleanan‐3‐ol ( 3 ), and (3β,9β)‐9,25‐cycloolean‐12‐en‐3‐yl β‐D ‐glucofuranoside ( 4 ), a steroid named (3β,9β,14β)‐14‐hydroxy‐9,19‐cyclocholan‐3‐yl β‐D ‐glucopyranoside ( 5 ), and an anthraquinone named 6‐hydroxy‐5,7,8‐trimethoxy‐9,10‐dioxo‐9,10‐dihydroanthracen‐2‐yl acetate ( 6 ) have been isolated from the fruits and bark of Celtis australis (Ulmaceae), along with apigenin, quercetin, and its glucoside. Their structures were elucidated by means of chemical and spectral analysis including COSY, NOESY, and HMBC experiments.     

Thermodynamics of U(VI) complexation by succinate at variable temperatures

Complexation of U(VI) by succinate has been studied at various temperatures in the range of (298 to 338) K by potentiometry and isothermal titration calorimetry at constant ionic strength (1.0 M). The potentiometric titrations revealed the formation of 1:1 uranyl succinate complex in the pH range of 1.5 to 4.5. The stability constant of uranyl succinate complex was found to increase with temperature. Similar trend was observed in the case of enthalpy of complex formation. However, the increase in entropy with temperature over-compensated the increase in enthalpy, thereby favouring the complexation reaction at higher temperatures. The linear increase of enthalpy of complexation with temperature indicates constancy of the change in heat capacity during complexation. The temperature dependence of stability constant data was well explained with the help of Born equation for electrostatic interaction between the metal ion and the ligand. The data have been compared with those for uranyl complexes with malonate and oxalate to study the effect of ligand size and hydrophobicity on the temperature dependence of thermodynamic quantities.     

Shape, flexibility and packing of proteins and nucleic acids in complexes

Determining the change in topological properties like shape, flexibility and packing of proteins and nucleic acids on complexation is important in characterizing the role of induced structural changes and various interactions which control the functional specificity of proteins and nucleic acids. To this end, we have analyzed and compared the three dimensional structures of several protein-protein, protein-DNA and protein-RNA complexes available in the Protein Data Bank (PDB) and the Nucleic Acid Data Bank (NDB). The size of complexed proteins and nucleic acids, as measured by the radius of gyration, follows Flory's scaling law. The change in the scaling exponents for proteins, RNA and DNA reflects the changes in their respective sizes due to complexation. The anisotropy in the shape of proteins, DNA and RNA in complexes is measured by considering the asphericity and shape parameter, which are calculated from the eigenvalues of the moment of inertia tensor. The distribution of asphericity and shape shows that complexed proteins are mostly spherically symmetrical, while DNA and RNA in complexed states are largely prolate and considerably more aspherical compared to the proteins. Persistence length characterizes the intrinsic flexibility/rigidity of proteins and nucleic acids. The flexibility of all biomolecules decreases with the chain length. For small DNA molecules (6-147 base pairs), persistence length is larger compared to RNA and proteins in protein-protein and protein-RNA complexes. The flexibility of DNA increases, while RNA decreases, in their respective complexed states as compared to that of proteins which remain almost unchanged. The two body contact analysis confirms that the side-chain-backbone contacts are predominant compared to sidechain-sidechain and backbone-backbone contacts in the complexed proteins. The average packing density of proteins decreases in their complexed states, which is measured by the mean value of the contact density of their alpha carbon atoms. The average number of hydrogen bonds are found to be less in the interface region of protein-protein complexes compared to that in protein-DNA and protein-RNA complexes.     

Isolation and characterization of a new flavone diglucoside from <Emphasis Type="Italic">Salix denticulata</Emphasis>

A new flavone diglucoside named 7,3′-dihydroxy-4′-methoxyflavone-5-O-β-D-glucopyranosyl (6″ → 1‴)-β-D-glucopyranoside (1), along with four known flavonoids, luteolin (2), isoquercetin (3), catechin (4), and diosmetin (5), has been isolated and characterized from Salix denticulata. The structure of the new flavone diglucoside was characterized by means of high field 1D and 2D NMR and MS spectral analysis.     

A fuzzy inventory model without shortages using triangular fuzzy number

In business and industry it becomes very difficult for a manager to take concrete decision regarding inventory, as the data available to him are not always certain. Because uncertainty arises in demand, set-up resources & capacity constraints of an inventory planning system, it could be more justified to consider these factors in an elastic form. Therefore, with these uncertain data, fuzziness can be applied and the problem of inventory can be controlled. In the present paper, an inventory model without shortage has been considered in a fuzzy environment, by considering real-life data from the LPG store of Banasthali University. Triangular fuzzy numbers have been used to consider the ordering and holding costs. For defuzzification, signed-distance method has been used to compute the optimum order quantity.