Engineering topics

Mukherjee, G

Publications and source records attributed to Mukherjee, G.

5 records

DOE OSTI2011

Structural and Functional Characterization of a Single-chain Peptide-MHC Molecule that Modulates both Naive and Activated CD8plus T Cells

Peptide-MHC (pMHC) multimers, in addition to being tools for tracking and quantifying antigen-specific T cells, can mediate downstream signaling after T-cell receptor engagement. In the absence of costimulation, this can lead to anergy or apoptosis of cognate T cells, a property that could be exploited in the setting of autoimmune disease. Most studies with class I pMHC multimers used noncovalently linked peptides, which can allow unwanted CD8{sup +} T-cell activation as a result of peptide transfer to cellular MHC molecules. To circumvent this problem, and given the role of self-reactive CD8{sup +} T cells in the development of type 1 diabetes, we designed a single-chain pMHC complex (scK{sup d}.IGRP) by using the class I MHC molecule H-2K{sup d} and a covalently linked peptide derived from islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP{sub 206-214}), a well established autoantigen in NOD mice. X-ray diffraction studies revealed that the peptide is presented in the groove of the MHC molecule in canonical fashion, and it was also demonstrated that scK{sup d}.IGRP tetramers bound specifically to cognate CD8{sup +} T cells. Tetramer binding induced death of naive T cells and in vitro- and in vivo-differentiated cytotoxic T lymphocytes, and tetramer-treated cytotoxic T lymphocytes showed a diminished IFN-{gamma} response to antigen stimulation. Tetramer accessibility to disease-relevant T cells in vivo was also demonstrated. Our study suggests the potential of single-chain pMHC tetramers as possible therapeutic agents in autoimmune disease. Their ability to affect the fate of naive and activated CD8{sup +} T cells makes them a potential intervention strategy in early and late stages of disease.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2011

Evidence of quasifission in the {sup 16}O + {sup 238}U reaction at sub-barrier energies

Mass distribution of fission fragments and neutron multiplicity in the {sup 16}O+{sup 238}U reaction were measured at near- and below-barrier energies. A sudden change in the fragment mass width, observed in the present measurement, confirmed the transition to quasifission at below-barrier energies; the same was indicated earlier from the study of fission fragment angular anisotropy. However, the present measurement of prescission neutron multiplicity as well as the earlier measurement of evaporation residue yield did not indicate any significant departure from the respective statistical model predictions throughout the energy range. It is argued that the first two probes are more sensitive for highly asymmetric systems, whereas all probes would be useful and complimentary to each other for study of quasifission in more symmetric systems, where quasifission is more dominant.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2010

Evidence of nontermination of collective rotation near the maximum angular momentum in {sup 75}Rb

Two of the four known rotational bands in {sup 75}Rb were studied via the {sup 40}Ca({sup 40}Ca,{alpha}p){sup 75}Rb reaction at a beam energy of 165 MeV. Transitions were observed up to the maximum spin I{sub max} of the assigned configuration in one case and one-transition short of I{sub max} in the other. Lifetimes were determined using the residual Doppler shift attenuation method. The deduced transition quadrupole moments show a small decrease with increasing spin, but remain large at the highest spins. The results obtained are in good agreement with cranked Nilsson-Strutinsky calculations, which indicate that these rotational bands do not terminate, but remain collective at I{sub max}.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2010

K-hindered decay of a six-quasiparticle isomer in {sup 176}Hf.

The structure and decay properties of high-K isomers in {sup 176}Hf have been studied using beam sweeping techniques and the Gammasphere multidetector array. A new {Delta}K = 8 decay branch, from a K{sup {pi}} = 22{sup -}, six-quasiparticle, isomeric (t{sub 1/2} = 43 {micro}s) state at 4864 keV to the 20{sup -} state of a K{sup {pi}} = 14{sup -} band, has been identified. The reduced hindrance factor per degree of K forbiddenness for this decay is measured to be unusually low (f{sub ?} = 3.2), which suggests K mixing in the states involved. The deduced interaction matrix elements are discussed within the context of relevant K-mixing scenarios. The 3266-keV state, previously interpreted as a K{sup {pi}} = 16{sup +} intrinsic state, is reassigned as the J{sup {pi}} = 16{sup +} member of the band based on the K{sup {pi}} = 15{sup +} state at 3080 keV. The systematics of f{sub ?} values as a function of the degree of forbiddenness is discussed in light of this change.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2010

Nuclear Data Sheets for A = 95

Experimental data on ground and excited state properties for all known nuclei with mass number A=95 have been compiled and evaluated. States populated in radioactive decay, as well as in nuclear reactions, have been considered. For these nuclei, level and decay schemes, as well as tables of nuclear properties, are presented. This work supersedes the 1993 evaluation by T. W. Burrows (1993Bu08). In summary, three isomers were identified in {sup 95}Ag and their respective decay schemes were presented (2003Do09) though only limits on their half lives could be obtained. Besides, high resolution prompt gamma-spectroscopy of {sup 95}Ag has been reported for the first time (2003Ma24). A comprehensive level scheme {sup 95}Pd is now available through the ? decay of {sup 95}Ag (2005Ha45) and the energy of the 21/2+ spin-gap isomer have been established for the first time by observing the gamma-rays from the yrast levels (2003Ma24). The level scheme of {sup 95}Rh has been extended up to 39/2 h by in-beam spectroscopy (1994Ro08) and the {gamma}-delayed proton decays from 96Ag isomers to low-lying levels in {sup 95}Pd have been observed (2003Ba39). The high spin level scheme of {sup 95}Ru has been extended up 43/2 h (1994Gh06) and the lifetime or lifetime limits of several high spin states have been reported (2004Ga08). In {sup 95}Tc, the level scheme has been extended by in-beam spectroscopy (2000Gh01). New data on high spin states in {sup 95}Mo have been available through in-beam spectroscopy using heavy ion reactions [(1998Kh04),(2004Ch18),(2009Zh11)]. The data on {sup 95}Nb has been considerably extended by (t,p) reaction (2005Ra30) and by ({sup 82}Se,p2n{gamma}) reaction (2005Bu08). In {sup 95}Zr, new measurements on {mu} (2005St24) and Q (1998Se01) have become available. Controversy on the existence of a 23 keV state in {sup 95}Zr has been resolved by a high-resolution measurement using magnetic spectrometer (2003So23). New data on high spin states have been published through heavy-ion induced fission [(2002Fo03), (2005Pa48)]. Very recently, new high spin data on {sup 95}Y by n-induced and spontaneous fission decay have been available (2009Ur02). High spin data on {sup 95}Sr have been reported by {gamma}-spectroscopy of spontaneous fission decay (2004Hw04). In {sup 95}Rb, revised estimate of {gamma}-n decay intensity (2002Pf04) and mass excess (2007Ra23) have been reported. New data on {sup 85}Kr it decay have been reported [(2006Ge05),(2007Si17)] and incorporated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗