Perturbation theory for multiconfiguration reference states

Vector method procedures are adapted to evaluate Rayleigh-Schrödinger perturbation corrections to a multiconfiguration zeroth order function. If this function is sufficiently flexible, this perturbation theory can be applied to low lying excited states. The effectiveness of our theory is demonstrated on the ground state of F₂ and the low lying excited states of Mg₂. Energies calculated through fourth order are compared with appropriate CI results.     

Molecular mechanics (MM2) calculations on peptides and on the protein Crambin using the CYBER 205

The MM2 potential functions for amides and peptides have been further extended by examining the experimental crystal structures for cyclo-(-Ala-Ala-Gly-Gly-Ala-Gly-), I, and cyclo-(-Ala-Ala-Gly-Ala-Gly-Gly-), II. The force field obtained was then applied to a study of the structure of the hydrophobic protein Crambin, for which a high resolution crystal structure is available. The energy minimization was carried out using a version of MM2 adapted to the CYBER 205.     

A comparative study of double beta decay by shell model and quasiparticle RPA

Nuclear matrix elements of the two-neutrino and neutrinolessββ decays of⁴⁸Ca(0 _g.s. ⁺ )→⁴⁸Ti(0 _g.s. ⁺ ) are calculated by shell model and QRPA. The two-neutrino matrix elementM _GT ^2v is rather reliably evaluated in the QRPA approach by a careful fit of the particle-particle interaction strength in the 1⁺ channel, which governs the spinisospin ground-state correlations. The shell-model value ofM _GT ^2v depends not only on the 1⁺ interaction but largely on the pairing and quadrupole interactions. Concerning the neutrinoless-mode nuclear matrix elements, the shell model gives generally smaller values than the QRPA. A detailed analysis indicates that the discrepancies originate mainly from the truncation of shell-model configurations (fp-space). The QRPA calculation in a larger model space well takes into account transitions from/to single-particle orbits far from the Fermi surface, and those transitions give rise to sizable contributions because of large momentum transfers due to the exchange of a virtual neutrino.     

Synthetic quinine,analogs. V. Quinolinemethanols related to desvinylquinine

Aldol condensation of quinolinecarboxaldehydes with 3-quinuelidinone followed by acid-catalyzed hydration of the resulting α,β-unsalurated ketones provides a short and versatile synthesis of desvinylquinine derivatives. A novel rearrangement of 2-(9-phenanthrylmethylene)-3-quinuclidinyl earbinols leading to dibenzoindole derivatives is described.     

Kinetics of enzyme-catalyzed alcoholysis of soybean oil in n-hexane

This work investigated the production of fatty acid ethyl esters (FAEEs) from soybean oil using n-hexane as solvent and two commercial lipases as catalysts, Novozym 435 and Lipozyme IM. A Taguchi experimental design was adopted considering the variables temperature (35–65°C), addition of water (0–10 wt/wt%), enzyme (5–20 wt/wt%) concentration, and oil-to-ethanol molar ratio (1:3–1:10). It is shown that complete conversion in FAEE is achieved for some experimental conditions. The effects of process variables on reaction conversion and kinetics of the enzymatic reactions are presented for all experimental conditions investigated in the factorial design.     

Optimization of alkaline transesterification of soybean oil and castor oil for biodiesel production

This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.     

Distributed chemical computing using ChemStar: an open source java remote method invocation architecture applied to large scale molecular data from PubChem

We present the application of a Java remote method invocation (RMI) based open source architecture to distributed chemical computing. This architecture was previously employed for distributed data harvesting of chemical information from the Internet via the Google application programming interface (API; ChemXtreme). Due to its open source character and its flexibility, the underlying server/client framework can be quickly adopted to virtually every computational task that can be parallelized. Here, we present the server/client communication framework as well as an application to distributed computing of chemical properties on a large scale (currently the size of PubChem; about 18 million compounds), using both the Marvin toolkit as well as the open source JOELib package. As an application, for this set of compounds, the agreement of log P and TPSA between the packages was compared. Outliers were found to be mostly non-druglike compounds and differences could usually be explained by differences in the underlying algorithms. ChemStar is the first open source distributed chemical computing environment built on Java RMI, which is also easily adaptable to user demands due to its "plug-in architecture". The complete source codes as well as calculated properties along with links to PubChem resources are available on the Internet via a graphical user interface at http://moltable.ncl.res.in/chemstar/.