Enantiomeric synthesis of the key synthon of the oviposition-deterring pheromone of Rhagoletis cerasi L

A convenient and enantioselective synthesis of ethyl (8RS, 15R)-8-acetoxy-15-hydroxyhexadecanoate15 via a chemoenzymatic approach has been described. The salient features of the synthesis were operational simplicity, use of easily accessible materials, and excellent enantiocontrol via lipase catalyzed acetylation of 2-alkanol.     

Polyadic codes of prime power length

Polyadic codes constitute a special class of cyclic codes and are generalizations of quadratic residue codes, duadic codes, triadic codes, m-adic residue codes and split group codes, which have good error-correcting properties. In this paper, we give necessary and sufficient conditions for the existence of polyadic codes of prime power length. Examples of some good codes arising from the family of polyadic codes of prime power length are also given.     

Optimization of lantadenes isolation and preparation of 22 β-hydroxyoleanonic acid

The lantadenes fraction from Lantana camara was isolated and transformed to the medicinally important intermediate 22β-hydroxyoleanonic acid. The compound was studied for hepatotoxicity using lantadene A as standard and found to be nontoxic. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 357–358, July–August, 2006.     

On solving energy-dependent partitioned eigenvalue problem by genetic algorithm: The case of real symmetric Hamiltonian matrices

An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed     

Approximate and Exact Small Signal Analysis for Single-Mode Fiber Near Zero Dispersion Wavelength with Higher Order Dispersion

This article presents the comparison of approximate and exact small-signal theories for analyzing the influence of the higher-order dispersion terms on dispersive optical communication systems operating near zero dispersion wavelength for linear single-mode fiber. For the approximate theory, the generalized conversion matrix has been reported and gives the transfer function of intensity and phase from the fiber input to fiber output for a laser source including the influence of any higher-order dispersion term. In addition, expressions for the small-signal frequency response and the relative intensity noise (RIN) response of an ultrafast laser diode including noises are derived. However, it is observed that the approximation assumed for the second-order dispersion term for the approximate analysis is not valid. From the approximate theory, the exact generalized conversion matrix and exact expressions for small-signal frequency response and relative intensity noise (RIN) are obtained. We show that for the exact theory, the second-order dispersion term has no effect on intensity and frequency response even at large modulating frequencies and large propagation distances contrary to the approximate theory as reported by other authors. But we show that third-order dispersion term certainly has some minute impact on the frequency and RIN response for long distance links at high modulating frequencies.     

Engel type identities with derivations for right ideals in prime rings

Let R be a prime ring of char R≠2, d a non-zero derivation of R and ρ a non-zero right ideal of R such that [[d(x),d(y)]_n [y,x]_m] = 0 for all x,y ∈ ρ or [[d(x),d(y)]_n d[y,x]_m] = 0 for all x,y ∈ ρ, n, m ≥ 0 are fixed integers. If [ρ,ρ]ρ ≠ 0, then d(ρ)ρ = 0.     

Study of photon-induced L3 vacancy alignment for elements La to U

Alignment of photon-induced L₃ vacancies is studied in rare earth and highZ elements at energies of experimental interest, near thresholds to 60 keV, under nonrelativistic dipole approximation. Numerical calculations of the matrix element are undertaken to produce theoretical data for comparison with the experimental findings. The A₂ values being s>0.1 at photoelectron energies <20 keV are certainly higher than 5–8% uncertainties quoted in experimental results. Present findings are from a very basic model, hydrogen-like and can further be treated as reference to observe the impact of screening, relativistic, multipole and retardation corrections to the model     

Temperature studies of Fe−Mn nodules

Sea nodules were extensively studied over a wide range of temperature ranging from 77K to 1175K using Mossbauer effect and ESR. The Mossbauer studies of the nodules at 77K and room temperature show a quadrupole doublet whereas at higher temperatures magnetic spectra were obtained starting at around 875K which ultimately gives a hyperfine field of around 390 KOe at 1175 K. The Mossbauer spectra recorded at 30K did not show any significant change in the room temperature spectra. The analysis of the spectra upto 775K showed two positions of Fe^R+, vie., octahedral and tetrahedral which were varified by ESR of the diluted samples.