166 research outputs found

    High Yield Production of Heterologous Proteins with Escherichia coli

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    The demand for therapeutic recombinant proteins is set to see a significant increase over the next few years. As a consequence, the processes used to produce these proteins must be able to meet market requirements. Recombinant proteins have gained enormous importance for clinical applications. The present paper reviews the fermentation process for high yield scalable production of heterologous recombinant proteins in Escherichia coli. Influence of process parameters for the standard  fermentation processes are discussed, and alternative methods that solve the limitations are reviewed together with the methods that yielded in higher productivity of E. coli process. The common problems are scale-up issues, plasmid instability, acetate accumulation and substrate inhibition in the high cell density bioreactor production system. Methods to overcome these issues are described. Solving the problems makes ideal condition for high yield production with E. coli expression system as compared to other systems.Defence Science Journal, 2009, 59(2), pp.137-146, DOI:http://dx.doi.org/10.14429/dsj.59.150

    SPM limited long haul optical transmission in RZ-DPSK for varying input launch power with SMF, Monte Carlo Simulation

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    In this paper 10Gbps and 20Gb/s optical systems have been studied for return to zero differential phase shift keying. Observations are based on numerical simulations of dispersion compensated transmission link, for the range of optical signal power -2.5 to +2.5,-5 to +5,-10 to +10,-20 to +20dBm.Transmission over distances of four thousands of kilometers has been shown with amplified spontaneous emission (ASE) noise of the inline erbium doped fiber amplifier. Key words: DWDM, OSNR, ASE, RZ, DPS

    Study in variable duty cycle return to zero pulse with multiplexed channels for SMFs

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    In this paper analysis has been done with varying return-to-zero (RZ) pulsed duty cycle, differential phase shift keying 640Gbps (16x40Gb/s) multiplexed channel optical transmission system using different SMFs viz standard Single mode fiber (SSMF), Non Zero Dispersion shifted fibers (normal NZDSF and anomalous NZDSF fiber), Corning SMF.Optical transmission used for sixteen users operates at 40Gbps per channel, 0.20nm spaced sixteen channels and fiber span analysis is done for test length of 200km. We tested system for detailed performance study for its behavior with different duty cycles for optical RZ pulse, results showing lowest bit error rate for 0.80 duty cycles among selection of 0.5, 0.8.0.99 for four types of SMFs tested for optical communication. Single repeater less mode fiber length is increased from 60km at duty cycle 0.5 to NZDSF fiber length of 140km at duty cycle 0.99.Results are also compared through 10dB Q improvement and corresponding improvement in average eye opening pattern. NZDSF fiber shows much improvement in average eye opening diagram for 0.99 duty cycle compared to other fibers tested and other duty cycles tested. Key words: DWDM, ASE, RZ, DPSK, OSNR

    Comparative performance study in multiplexed RZDPSK for SMF's with FBG

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    The Fiber Bragg gratings have emerged as important components in several of light wave applications in the FBG becoming a ubiquitous and necessary element in equipment located throughout the network from the central office to the home. This paper explores comparative performance study with and without using FBG as an external dispersion compensator for sixteen channel return to zero differential phase shift keying modulation operating at 45Gbps per channel with channel spacing of 0.15nm. Simulations are done with various single mode fibers with and without external FBG.Better performance (Q, BER) for dispersion values used in simulation are -58ps/nm, 23ps/nm, and 100ps/nm for FBG's used at receiver channels. It is observed that FBG used with receiver channels support larger communication fiber length, also G655 (NZDSF) fiber shows much better performance as compared with other SMF's tested. Key Words: FBG, WDM, DCG, DCF, FOM, RZ

    Assessment of Influence and Inter-Relationships of Soil Properties in Irrigated Rice Fields of Bangladesh by GIS and Factor Analysis

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    Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): Assessment of Influence and Inter-Relationships of Soil Properties in Irrigated Rice Fields of Bangladesh by GIS and Factor Analysis. Manuscript LW 07 022. Vol. IX. November, 2007

    The Comparative Study of Electrical Resistivity of bcc Liquid Transition Metals

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    In the present paper, we have used Ziman’s approach and transition matrix (t-matrix) approach to study the electrical resistivities of bcc liquid metals. By carrying out this study, we have verified the validity of our proposed pseudopotential extracted from generalized pseudopotential theory (GPT). Our theoretical results agree well with experimental results. Also, it has been verified that for transition metals tmatrix approach is more realistic and physically sound than Ziman approach

    A CRISPR/Cas9-based genome-editing system for yam (Dioscorea spp.)

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    Open Access Journal; Published online: 22 Nov 202

    Nuclear Flow Excitation Function

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    We consider the dependence of collective flow on the nuclear surface thickness in a Boltzmann--Uehling--Uhlenbeck transport model of heavy ion collisions. Well defined surfaces are introduced by giving test particles a Gaussian density profile of constant width. Zeros of the flow excitation function are as much influenced by the surface thickness as the nuclear equation of state, and the dependence of this effect is understood in terms of a simple potential scattering model. Realistic calculations must also take into account medium effects for the nucleon--nucleon cross section, and impact parameter averaging. We find that balance energy scales with the mass number as AyA^{-y}, where yy has a numerical value between 0.35 and 0.5, depending on the assumptions about the in-medium nucleon-nucleon cross section.Comment: 11 pages (LaTeX), 7 figures (not included), MSUCL-884, WSU-NP-93-

    Density Dependent Hadron Field Theory

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    A fully covariant approach to a density dependent hadron field theory is presented. The relation between in--medium NN interactions and field--theoretical meson--nucleon vertices is discussed. The medium dependence of nuclear interactions is described by a functional dependence of the meson--nucleon vertices on the baryon field operators. As a consequence, the Euler--Lagrange equations lead to baryon rearrangement self--energies which are not obtained when only a parametric dependence of the vertices on the density is assumed. It is shown that the approach is energy--momentum conserving and thermodynamically consistent. Solutions of the field equations are studied in the mean--field approximation. Descriptions of the medium dependence in terms of the baryon scalar and vector density are investigated. Applications to infinite nuclear matter and finite nuclei are discussed. Density dependent coupling constants obtained from Dirac--Brueckner calculations with the Bonn NN-potentials are used. Results from Hartree calculations for energy spectra, binding energies and charge density distributions of 16O^{16}O, 40,48Ca^{40,48}Ca and 208Pb^{208}Pb are presented. Comparisons to data strongly support the importance of rearrangement in a relativistic density dependent field theory. Most striking is the simultanuous improvement of charge radii, charge densities and binding energies. The results indicate the appearance of a new "Coester line" in the nuclear matter equation of state.Comment: 48 LateX pages, 12 Figures, figures and full paper are available as postscript files by anonymous ftp at ftp://theorie.physik.uni-giessen.de/dd

    Search for Rare and Forbidden Dilepton Decays of the D+, Ds, and D0 Charmed Mesons

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    We report the results of a search for flavor-changing neutral current, lepton-flavor violating, and lepton-number violating decays of D+, Ds, and D0 mesons (and their antiparticles) into modes containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, we examine the pi,l,l and K,l,l decay modes of D+ and Ds and the l+l- decay modes of D0. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 24 decay modes examined. Eight of these modes have no previously reported limits, and fourteen are reported with significant improvements over previously published results.Comment: 12 pages, 3 figures, LaTeX, elsart.cls, epsf.sty, amsmath.sty Submitted to Physics Letters
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