PHYSICAL MUTAGENESIS BASED STRAIN IMPROVEMENT OF ASPERGILLUS SP. FOR ENHANCED PRODUCTION OF LOVASTATIN

Objective: The present investigation aimed towards the strain improvement of lovastatin maximum yielding wild-type fungal strains (Aspergillus terreus-MTCC 11045, Aspergillus terreus-MTCC 11395 and Aspergillus flavus-MTCC 11396) through physical mutagenesis by applying UV random mutations.Methods: Revival of fungal cultures on PDA plates followed by a screening of their morphological and microscopic properties. Strain improvement of screened fungi by UV (255 nm) random mutagenesis, selection of mutants based on morphological variations further submerged fermentation of selected (SmF) mutants, subsequently extraction of lovastatin from the spent broth and the extracts were analyzed for the presence of lovastatin by TLC and UV spectrophotometer scans (200-300 nm).Results: Out of eighteen screened mutant samples seven showed positive results for the lovastatin production. Among these seven positive cultures, Aspergillus terreus 11045-90 found to yield the maximum amount of lovastatin (3912 mg/l).Conclusion: The present study concludes by reporting the evidence of raised in the lovastatin titre by three-fold compared to the yield of the wild-type strain (996 mg/l) and confirms the achievement of strain improvement by UV random mutagenesis.Keywords: Aspergillus terreus, Lovastatin, UV Random mutations, Strain improvement, Submerged fermentatio

Interference effects in the counting statistics of electron transfers through a double quantum dot

We investigate the effect of quantum interferences and Coulomb interaction on the counting statistics of electrons crossing a double quantum dot in a parallel geometry using a generating function technique based on a quantum master equation approach. The skewness and the average residence time of electrons in the dots are shown to be the quantities most sensitive to interferences and Coulomb coupling. The joint probabilities of consecutive electron transfer processes show characteristic temporal oscillations due to interference. The steady-state fluctuation theorem which predicts a universal connection between the number of forward and backward transfer events is shown to hold even in the presence of Coulomb coupling and interference.Comment: 11 pages, 12 figure

Persistent time intervals between features in solar flare hard X-ray emission

Several solar hard X-ray events (greater than 100 keV) were observed simultaneously with identical instruments on the Venera 11, 12, 13, 14, and Prognoz spacecraft. High time resolution (= 2 ms) data were stored in memory when a trigger occurred. The observations of modulation are presented with a period of 1.6 s for the event on December 3, 1978. Evidence is also presented for fast time fluctuations from an event on November 6, 1979, observed from Venera 12 and another on September 6, 1981, observed from the Solar Maximum Mission. Power spectrum analysis, epoch folding, and Monte Carlo simulation were used to evaluate the statistical significance of persistent time delays between features. The results are discussed in light of the MHD model proposed by Zaitsev and Stepanov

Memory-induced anomalous dynamics: emergence of diffusion, subdiffusion, and superdiffusion from a single random walk model

We present a random walk model that exhibits asymptotic subdiffusive, diffusive, and superdiffusive behavior in different parameter regimes. This appears to be the first instance of a single random walk model leading to all three forms of behavior by simply changing parameter values. Furthermore, the model offers the great advantage of analytic tractability. Our model is non-Markovian in that the next jump of the walker is (probabilistically) determined by the history of past jumps. It also has elements of intermittency in that one possibility at each step is that the walker does not move at all. This rich encompassing scenario arising from a single model provides useful insights into the source of different types of asymptotic behavior

Many-body Green's function approach to attosecond nonlinear X-ray spectroscopy

Closed expressions are derived for resonant multidimensional X-ray spectroscopy using the quasiparticle nonlinear exciton representation of optical response. This formalism is applied to predict coherent four wave mixing signals which probe single and two core-hole states. Nonlinear X-ray signals are compactly expressed in terms of one- and two- particle Green's functions which can be obtained from the solution of Hedin-like equations at the $GW$ level.Comment: 10 pages and 3 figures (To appear in Physical Review B

Anaesthetic management for cleft palate in a child with digeorge syndrome: Look before you leap!

DiGeorge syndrome is a multisystem disorder associated with various cardiac anomalies, aplasia or hypoplasia of thymus and parathyroid glands, palatal defects, immune deficiency, and characteristic facial features. Here, we are reporting the case of a known DiGeorge syndrome posted for the repair of cleft palate in a 3-year-old female child. Anaesthetic management for any surgery in a child with DiGeorge syndrome is challenging for anaesthesiologist in terms of the associated complications. Hence, sound knowledge about DiGeorge syndrome is required for safe anaesthetic management

Structural Relaxation and Frequency Dependent Specific Heat in a Supercooled Liquid

We have studied the relation between the structural relaxation and the frequency dependent thermal response or the specific heat, $c_p(\omega)$, in a supercooled liquid. The Mode Coupling Theory (MCT) results are used to obtain $c_p(\omega)$ corresponding to different wavevectors. Due to the two-step relaxation process present in the MCT, an extra peak, in addition to the low frequency peak, is predicted in specific heat at high frequency.Comment: 14 pages, 13 Figure

The Fourier Imaging X-ray Spectrometer (FIXS) for the Argentinian, Scout-launched satelite de Aplicaciones Cienficas-1 (SAC-1)

The Fourier Imaging X-ray Spectrometer (FIXS) is one of four instruments on SAC-1, the Argentinian satellite being proposed for launch by NASA on a Scout rocket in 1992/3. The FIXS is designed to provide solar flare images at X-ray energies between 5 and 35 keV. Observations will be made on arcsecond size scales and subsecond time scales of the processes that modify the electron spectrum and the thermal distribution in flaring magnetic structures

Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime