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Formation of rovibrational excited molecular hydrogen from atomic recombination has been computationally studied using three body dynamics and orbiting resonance theory. Each of the two methods in the frame of classical mechanics,...
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Formation of rovibrational excited molecular hydrogen from atomic recombination has been computationally studied using three body dynamics and orbiting resonance theory. Each of the two methods in the frame of classical mechanics, that has been used for all of the calculations, appear complementary rather than complete,with similar values in the low temperature region, and predominance of three body dynamics for temperatures higher than about 1000 K. The sum of the two contributions appears in fairly good agreement with available data from the literature. Dependence of total recombination on the temperature over pressure ratio is stressed.Detailed recombination toward rovibrational states is presented, with large evidence of importance of rotation in final products. Comparison with gas-surface recombination implying only physiadsorbed molecules shows approximate similarities at T=5000 K, being on the contrary different at lower temperature.
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The recombination dynamics of defect states in zinc oxide nanowires has been studied by developing a general expression for time-resolved photoluminescence intensity based on a second-order approximation for the radiative and non-...
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The recombination dynamics of defect states in zinc oxide nanowires has been studied by developing a general expression for time-resolved photoluminescence intensity based on a second-order approximation for the radiative and non-radiative recombination rates. The model allows us to determine the parameters that characterize the recombination from deep defect states (defect concentration, unimolecular lifetime and bimolecular coefficient) through multi-fitting analysis of time-resolved photoluminescence measurements. Analyses conducted on zinc oxide nanowires gave deep state concentrations of the order of 10~(18) cm~(-3) and unimolecular lifetimes and bimolecular recombination coefficient comparable to those typical of interband recombination in direct gap semiconductors. The consistency of a `two-channel decay' model (double exponential decay) has been tested by means of a similar analysis procedure. The results suggest that double exponential fitting of time-resolved photoluminescence data of zinc oxide nanowires may be just a mere phenomenological tool which does not reflect the real recombination dynamics of the visible emission band.
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Hepatitis C virus (HCV) is an RNA virus, which belongs to the genus Hepacivirus within the Flaviviridae family. Recombinant viruses have been described in the three genera of this family. HCV is a highly variable virus, whose stra...
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Hepatitis C virus (HCV) is an RNA virus, which belongs to the genus Hepacivirus within the Flaviviridae family. Recombinant viruses have been described in the three genera of this family. HCV is a highly variable virus, whose strains are classified among six genotypes. The first intergenotypic recombinant HCV 2k/1b was identified in 2002 in Saint Petersburg. To date a limited number of intragenotypic or intergenotypic recombinant strains were characterized in vivo. The crossover point of the recombinant strains was mainly found at the NS2-NS3 junction. Regarding the small number of recombinant strains described in the literature, the phenomenon of recombination might be rare. However, its prevalence may be underestimated since these viruses are not routinely searched. The impact of recombination on HCV epidemiology or physiopathology remains to be elucidated.
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Epstein Barr virus (EBV) has a large DNA genome assumed to be stable, but also subject to mutational processes such as nucleotide substitution and recombination, the latter explored to a lesser extent. Moreover, differences in the...
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Epstein Barr virus (EBV) has a large DNA genome assumed to be stable, but also subject to mutational processes such as nucleotide substitution and recombination, the latter explored to a lesser extent. Moreover, differences in the extent of recombination events across herpes sub-families were recently reported. Given the relevance of recombination in viral evolution and its possible impact in pathogenesis, we aimed to fully characterize and quantify its extension in all available EBV complete genome by assessing global and local recombination rate values (rho/bp).
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Dissociative electron-ion recombination (DR) is an important ionization loss process and source of neutral reactive radicals in the interstellar medium (ISM) and many other molecular plasmas. Unfortunately, neutral products are di...
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Dissociative electron-ion recombination (DR) is an important ionization loss process and source of neutral reactive radicals in the interstellar medium (ISM) and many other molecular plasmas. Unfortunately, neutral products are difficult to identify with only about 40 distributions being reported in the literature. These have been obtained by spectroscopic techniques integrated with flowing afterglows (FA) and using storage rings (SR). The data obtained by SR measurements are more extensive than those determined in the FA. Some data are available where the two techniques overlap, however here there are very significant differences. To resolve these contradictions, a new technique to quantitatively detect product neutrals has been developed. This technique is based on the FA and uses an electron impact (EI) ionizer to ionize the neutral products prior to detection by a quadrupole mass filter/electron multiplier. Two, experimental methodologies, both using pulsed gas techniques, isolate and quantify the DR products. In one approach, an electron attaching gas is pulsed into the flow to transiently destroy electrons and thus quench DR. N2H+ recombination has been used as a test case and results from this approach give an upper limit of 5% for the NH + N product channel, the remainder being N-2 + H. In the second approach, the reagent gas N-2 is pulsed. Here the absolute percentages of products are monitored versus initial N-2 concentration. Results from this approach also give an upper limit of 5% for NH + N production. This establishes that N-2 + H is the dominant channel, being at least 95%, and that there is no significant NH production. This was contrary to a recent storage ring measurement which yielded 64% NH + N and 36% N-2 + H. Note, that these values have changed due to a recent re-measurement of the DR revealing that the NH channel is not nearly as significant as originally thought. Additionally, the DR product distribution for CH5+ is reported and discussed.
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The goal of the present work was to develop reagents with potential for tuberculosis diagnosis. Genetic sequences of Mycobacterium tuberculosis secretion antigens were amplified by PCR, cloned into the Gateway (R) system, and expr...
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The goal of the present work was to develop reagents with potential for tuberculosis diagnosis. Genetic sequences of Mycobacterium tuberculosis secretion antigens were amplified by PCR, cloned into the Gateway (R) system, and expressed in Escherichia coli. The recombinant M. tuberculosis proteins were purified by metal affinity chromatography and preparative gel SDS-PAGE electrophoresis followed by electroelution and removal of endotoxins using Triton X-114. In total, seven recombinant proteins were obtained (ESAT-6, CFP10, TB10.3, TB10.4, MTSP11, MPT70, and MPT83). Delayed hypersensitivity reactions (DHR) was evaluated in Cavia porcellus and compared to the response using a standard purified protein derivative (PPD). All seven recombinant proteins produced a positive induration reaction in an intradermal test in guinea pigs previously sensitized with M. tuberculosis. When applied together, at a concentration of each recombinant protein 0.04 mg/mL, the intradermoreaction in C. porcellus was significantly higher than that obtained by standard PPD (p-value = 0.00386)
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The radio recombination line intensities of heavy elements of helium, carbon and oxygen are calculated with accounting for dielectronic recombination. Dielectronic recombination rates are determined accurate to the second order of...
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The radio recombination line intensities of heavy elements of helium, carbon and oxygen are calculated with accounting for dielectronic recombination. Dielectronic recombination rates are determined accurate to the second order of a perturbation theory and the rates are described as function of principal quantum number for helium-like atom or ion. Balance equations are solved for the departure coefficients from LTE b(n). The collision and spontaneous transition rates are accounted for the balance equations, in which non-equilibrium distribution source is dielectronic recombination. Non-equilibrium amplification coefficients are found as functions of a medium temperature, density and ion charge z = 1-3 for radio recombination lines.
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The radio recombination line intensities of heavy elements of helium, carbon and oxygen are calculated with accounting for dielectronic recombination. Dielectronic recombination rates are determined accurate to the second order of...
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The radio recombination line intensities of heavy elements of helium, carbon and oxygen are calculated with accounting for dielectronic recombination. Dielectronic recombination rates are determined accurate to the second order of a perturbation theory and the rates are described as function of principal quantum number for helium-like atom or ion. Balance equations are solved for the departure coefficients from LTE b n . The collision and spontaneous transition rates are accounted for the balance equations, in which non-equilibrium distribution source is dielectronic recombination. Non-equilibrium amplification coefficients are found as functions of a medium temperature, density and ion charge z = 1–3 for radio recombination lines.
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The ion recombination is examined in parallel-plate ionization chambers in scanning proton beams at the Danish Centre for Particle Therapy and the Skandion Clinic. The recombination correction factor ks is investigated for clinica...
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The ion recombination is examined in parallel-plate ionization chambers in scanning proton beams at the Danish Centre for Particle Therapy and the Skandion Clinic. The recombination correction factor ks is investigated for clinically relevant energies between 70 MeV and 244 MeV for dose rates below 400 Gy min-1 in air. The Boutillon formalism is used to separate the initial and general recombination. The general recombination is compared to predictions from the numerical recombination code lonTracks and the initial recombination to the Jaffe theory. ks is furthermore calculated with the two-voltage method (TVM) and extrapolation approaches, in particular the recently proposed three-voltage (3VL) method. The TVM is in agreement with the Boutillon method and lonTracks for dose rates above 100 Gy min-1. However, the TVM calculated ks is closer related to the Jaffee theory for initial recombination for lower dose rate, indicating a limited application in scanning light ion beams. The 3VL is in turn found to generally be in agreement with Boutillon’s method. The recombination is mapped as a function of the dose rate and proton energy at the two centres using the Boutillon formalism: the initial recombination parameter was found to be A = (0.10 ± 0.01) V at DCPT and A = (0.22 ± 0.13) V at Skandion, which is in better agreement with the Jaffee theory for initial recombination than previously reported values. The general recombination parameter was estimated to m2 = (4.7 ± 0.1) ? 103V2nA-1cm-1 and m2 = (7.2 ± 0.1) ? 103V2nA-1cm-1. Furthermore, the numerical algorithm lonTracks is demonstrated to correctly predict the initial recombination at low dose rates and the general recombination at high dose rates.
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Homologous recombination (HR) is a universally conserved mechanism used to maintain genomic integrity. In eukaryotes, HR is used to repair the spontaneous double strand breaks (DSBs) that arise during mitotic growth, and the progr...
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Homologous recombination (HR) is a universally conserved mechanism used to maintain genomic integrity. In eukaryotes, HR is used to repair the spontaneous double strand breaks (DSBs) that arise during mitotic growth, and the programmed DSBs that form during meiosis. The mechanisms that govern mitotic and meiotic HR share many similarities, however, there are also several key differences, which reflect the unique attributes of each process. For instance, even though many of the proteins involved in mitotic and meiotic HR are the same, DNA target specificity is not: mitotic DSBs are repaired primarily using the sister chromatid as a template, whereas meiotic DBSs are repaired primarily through targeting of the homologous chromosome. These changes in template specificity are induced by expression of meiosis-specific HR proteins, down-regulation of mitotic HR proteins, and the formation of meiosis-specific chromosomal structures. Here, we compare and contrast the biochemical properties of key recombination intermediates formed during the pre-synapsis phase of mitotic and meiotic HR. Throughout, we try to highlight unanswered questions that will shape our understanding of how homologous recombination contributes to human cancer biology and sexual reproduction.
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