[en] Results are reported for tritium production rate (TPR) and tritium breeding ratio (TBR) in a 20-cm-thick bare lithium slab, at temperatures 100, 150, 200 and 300 K. The multigroup diffusion equation is solved as an eigenvalue problem for a completely thermalized source. The spatial variation of TPR has been estimated in the above-mentioned temperature range. It is observed that as the temperature is lowered the values of TPR show a considerable increase at distances very close to the source plane, whereas it falls rapidly at later distances for low temperatures. Variation of TBR with thickness of the breeding region at the a foresaid temperatures, shows saturation regions at various thicknesses. This thickness is seen to decrease as the temperature is lowered or the concentration of ⁶Li nuclei is enhanced. The effects of enrichments of ⁶Li nuclei on the value of TBR has also been assessed. The calculation shows that with increase in concentration of ⁶Li nuclei, the TBR value after an initial rise attains a constant value. It is also seen that TBR saturates at lower concentration of ⁶Li nuclei as the temperature is lowered. For the above-mentioned temperature range, TBR values show an exponential decay with increase in temperature. It is interesting to observe here, that even in a simple bare lithium slab the optimal value of TBR (1.05) is attainable at a temperature below about 180 K

[en] We have studied a Hubbard ring with alternating site potentials for half-filling in presence of a magnetic flux. Using a mean-field approach we have calculated the conductivity of such a ring at low and high temperatures. The interplay of the correlation, the polarizing field and the chemical modulation in site potentials tune the conductivity in an interesting fashion. In presence of the modulation in the site energy an appreciable variation in the conductance is observed with the change in flux. This scenario gets substantially modified in presence of the Hubbard correlation. Finite-size effects are also identified and they are found to be quickly disappearing with increasing system size. Sharp changes in the magnetoconductance is found to disappear at higher temperatures

[en] In this paper we have reported our results of a detailed time dependent study of neutron spectra, tritium production rate, tritium breeding ratio, slowing down time and average energy following a pulse of 14 MeV neutrons in Li + C assemblies of different sizes. We have solved the time dependent diffusion equation with energy dependent buckling as an eigenvalue problem. Our results show that an initial 14 MeV pulse slows down to the keV region within about 200 ns after its injection. At later times, its energy decreases rather slowly because elastic scattering is the sole mechanism of energy loss. Since most of the tritium producing reactions take place with neutrons having energies in this region, the tritium production rate is higher in a Li + C system than a corresponding natural lithium assembly. Moreover, in Li + C the calculated value of TBR is almost twice the value obtained for a natural lithium assembly of the same size. Also, by varying the concentration of ⁶Li we find that the value of TBR tends to saturate beyond about 40%

[en] It is proved analytically that the complex growth rate ω=ω_r+iω_i (ω_randω_i are respectively the real and imaginary parts of ω) of an arbitrary oscillatory motion of growing amplitude in ferromagnetic convection, with magnetic field dependent viscosity, in a rotating ferrofluid layer for the case of free boundaries, must lie inside a semicircle in the right half of the ω_rω_i- plane whose center is at the origin and (radius)²=max{(RM₁/P_r),T_a}, where R is the Rayleigh number, M₁ is the magnetic number, P_r is the Prandtl number and T_a is the Taylor number. Further, bounds for the case of rigid boundaries are also derived separately. - Highlights: • The linear stability analysis for a rotating ferrofluid layer with magnetic field dependent viscosity heated from below is made. • Upper bounds for the complex growth rates are obtained for free and rigid boundaries. • Bounds are important mainly when atleast one boundary is rigid so that exact solutions in closed form are not obtainable. • Results derived involve only nondimensional quantities and are independent of the wave number; are, thus, of uniform validity and applicability

[en] The technique of small angle neutron scattering was first used in Germany less than two decades ago. Since then it has developed very rapidly, and today it is regarded as one of the most powerful techniques in materials, chemical and biological research. During the last decade the combination of high flux reactors and sophisticated instrumentation has revolutionized the technique. This paper endeavours to present a brief but comprehensive review of small angle scattering of neutrons and its applications in solid state research. The domain in which small angle neutron scattering is particularly useful is delineated and some of the methods used in the analysis of data are discussed with special emphasis on recent developments. Typical small angle neutron scattering cameras are described. Finally some experimental results on heterogeneities in metallic systems (both static and dynamic studies), radiation damage in materials, superconductivity, magnetic materials and the technologically very important area of non-destructive testing are reviewed in order to illustrate the wide range of applicability of this technique to problems in solid state research. (author)

[en] Residual life assessment of components of nuclear power plants is essential for their operational safety, reliability and financial viability. The high risks involved in the event of failures in nuclear power plants have led to the development of design philosophies that incorporate extreme conservatism in design. The implications of such conservatism in design leads to more frequent maintenance operations than necessary

[en] Highlights: • Loss of H3S10P in response to DNA damage is a universal phenomenon from G1 cells. • The loss happens predominantly from histone H3.3, a transcription activation mark. • Compaction of chromatin occurs during repair stage of DDR. • The alteration of H3S10P shows an inverse correlation with γH2AX. - Abstract: Chromatin acts as a natural barrier in DNA-damage recognition and repair. Histones undergo differential post-translational modification(s) to facilitate DNA damage response (DDR). Importance of modifications like phosphorylation of histone variant H2A.X in DNA repair is very well understood, however, ambiguous results exist in literature regarding the levels of certain histone modifications and their possible role in repair. In the present study, we have investigated in depth the alteration in the level of the highly dynamic histone mark H3S10P as it plays a dual role in different phases of the cell cycle. We show here that H3S10P decreases specifically from irradiated G1-enriched cells irrespective of the damaging agent or the cell line used in the study. Interestingly, the loss occurs predominantly from H3.3 variant which is a transcription activation mark like H3S10P itself, suggesting that the alteration might be implicated in transcription repression. The decrease in other transcription marks like H3K9Ac, H3K14Ac, H3K56Ac and H3S28P along with the occurrence of chromatin condensation in response to DNA damage in G1 phase strengthens the hypothesis. In addition, the alteration in the level of H3S10P shows an inverse correlation with that of γH2AX in a dose-dependent manner and probably occurs from the same mononucleosome. We propose that the drop in the levels of histone H3S10 phosphorylation is a universal phenomenon in response to DNA damage and is a trigger to induce transcription repressive state to facilitate repair

[en] A cooling system was designed, installed and is in the process of commissioning for cooling subsystems of Indus-2 accelerator

[en] Highlights: • Reversible reduction of H3S10 phosphorylation after DNA damage is G1 phase specific. • Dynamic balance between MAP kinases, MKP1 and MSK1 regulate H3S10P during DDR. • MKP1 associates with chromatin bearing γH2AX in response to DNA damage. • Inhibition of MKP1 activity with specific inhibitor promotes radiation-induced cell death. - Abstract: Histone mark, H3S10 phosphorylation plays a dual role in a cell by maintaining relaxed chromatin for active transcription in interphase and condensed chromatin state in mitosis. The level of H3S10P has also been shown to alter on DNA damage; however, its cell cycle specific behavior and regulation during DNA damage response is largely unexplored. In the present study, we demonstrate G1 cell cycle phase specific reversible loss of H3S10P in response to IR-induced DNA damage is mediated by opposing activities of phosphatase, MKP1 and kinase, MSK1 of the MAP kinase pathway. We also show that the MKP1 recruits to the chromatin in response to DNA damage and correlates with the decrease of H3S10P, whereas MKP1 is released from chromatin during recovery phase of DDR. Furthermore, blocking of H3S10 dephosphorylation by MKP1 inhibition impairs DNA repair process and results in poor survival of WRL68 cells. Collectively, our data proposes a pathway regulating G1 cell cycle phase specific reversible reduction of H3S10P on IR induced DNA damage and also raises the possibility of combinatorial modulation of H3S10P with specific inhibitors to target the cancer cells in G1-phase of cell cycle

[en] Image-guided percutaneous biopsy is a well-established and safe technique for obtaining tissue specimens from various regions of the body and plays a crucial role in patient management. Improvements in needle designs, development of new biopsy techniques, and continual advances in image-guidance technology have improved the safety and efficacy of the procedure. Lesions previously considered relatively inaccessible can now be safely biopsied. This review looks at the recent technologic developments in image guidance for percutaneous biopsy procedures. Improvements in needle design and other innovations intended to enhance the diagnostic yield of biopsy specimens are briefly discussed. Also described are some new techniques and unconventional approaches that help provide safe access to difficult-to-reach lesions