Novel synthons from mucochloric acid: the first use of alpha,beta-dichloro-gamma-butenolides and gamma-butyrolactams for direct vinylogous aldol addition

Novel 5-(1'-hydroxy)-gamma-butyrolactone and gamma-butyrolactam subunits were synthesized by direct vinylogous aldol addition of alpha,beta-dichloro gamma-butyrolactones and gamma-butyrolactams with aldehydes under basic conditions. Different bases and solvents were screened in the context of generating gamma-butyrolactones. Diastereoselectivity was observed and gamma-butenolides and gamma-butyrolactams showed opposite diastereoselectivity under the same reaction condition.     

Retention of enzymatic activity of alpha-amylase in the reductive synthesis of gold nanoparticles

In this paper, we report the generation of Au nanoparticles (NPs), using a pure enzyme for the reduction of AuCl4(-), with the retention of enzymatic activity in the complex. As a model system, alpha-amylase was used to readily synthesize and stabilize Au NPs in aqueous solution. Although several other enzymes were also pursued for the synthesis, it was interesting to observe that only alpha-amylase and EcoRI could produce Au NPs. Following NP synthesis, the activity of the enzyme was retained in the Au NP-alpha-amylase complex. The presence of Au NPs and alpha-amylase in the complex was established by UV-visible and FT-IR spectroscopy, X-ray diffraction (XRD) and transmission electron microscopic (TEM) measurements. Our observations suggest that the presence of free and exposed S-H groups is essential in the reduction of AuCl4(-) to Au NPs. Structural analysis of the enzymes showed that both alpha-amylase and EcoRI enzymes have free and exposed S-H groups in their native form and thus are suitable for the generation of NPs, whereas the other ones used here do not have such groups. Fortuitously, the enzymatic functional group of alpha-amylase is positioned opposite to that of the free and exposed S-H group, which makes it ideal for the production of Au NPs; binding of the enzyme to Au NPs via Au-S bond and also retention of the biological activity of the enzyme.     

Michael adducts‐synthons for pyrazolidinediones,isoxazolidinediones, pyrimidinetriones,and thioxopyrimidinediones

4‐Substituted pyrazolidinediones, isoxazolidinediones, and 5‐substituted pyrimidinetriones, thioxopyrimidinediones were obtained by exploiting gem‐diester functionality in mono‐ and di‐substituted dimethyl malonates. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:477–481, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20053     

A labeling scheme for young tableaux spanning representations of permutation group S(N)

A structure‐dependent labeling scheme for the Standard Young Tableaux spanning the representations of the permutation group is outlined in the present work. This scheme is used to generate the representations of a select class of permutations such as dense cycles and general transpositions of the group using minimal storage requirements. Two distinct approaches are outlined for generating the tableaux in the present labeling scheme. Detailed application has been made to two‐column Young diagram representations that are extremely useful in electron correlation studies in molecules. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 185–190, 2000     

Graphical approach to correlations in high‐spin systems

We present a graphical technique for generating and indexing spin monomials of high‐spin systems. The procedure consists of developing a graph with at most n line segments from each node in a given row to the one immediately lower, where n is the multiplicity of single‐particle spin function. The paths lead to monomials with definite M values at each node. This technique has been used to generate and diagonalize the model spin Hamiltonian. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 389–393, 1999     

Magnetic studies of Li-Zn ferrites prepared by citrate precursor method

Ferrites having the general formula Li_0.5−0.5xZn_xFe_2.5−0.5xO₄ where 0≤x≤0.6 in steps of 0.2 were prepared by the citrate precursor method. The Curie temperature measured shows a decrease with increasing Zn concentration. Experimental results show that the room temperature initial permeability increases with the increase in the concentration of zinc. The initial permeability has also been studied as a function of frequency in the range of 100 Hz-1 MHz. The real part of initial permeability referred as initial permeability and the imaginary part of initial permeability better known as permeability loss show dispersion with frequency. Possible mechanism contributing to the above processes is discussed.     

Semi numerical solution of non-singlet Dokshitzer–Gribov–Lipatov–Altarelli–Parisi evolution equation up to next-to-next-to-leading order at small x

The non-singlet structure functions have been obtained by solving Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equations in next-next-to-leading order (NNLO) in the small-x limit. Here a Taylor series expansion has been used to solve the evolution equations and we obtain the semi numerical solution. Results are compared with the Fermi Lab experiment E665 data and New Muon Collaboration (NMC) data.     

Damping and modal structure of patterned magnetic nanoarrays

A number of studies have shown that ferromagnetic resonance linewidths in magnetic thin films contain a significant contribution due to processes, such as inhomogeneous broadening and two-magnon scattering followed by decay to the phonon thermal bath. We present a classical theoretical approach that permits the calculation of such processes for arrays of arbitrarily shaped magnetic nanoparticles and, by comparison with experimental results, demonstrates that the linewidth broadening and damping are dominated by inhomogenities that strongly depend on the equilibrium state of magnetization and can be used to identify the latter.     

A comparative study of soliton switching in a two- and three-core coupler with TOD and IMD

A numerical study of soliton switching in a two- and three-core coupler is carried out taking into account the effect of intermodal dispersion and third-order dispersion. A two and three-core coupler with linear and triangular configuration is considered. It is found that the three-core coupler with linear configuration shows the best switching characteristics.