473 research outputs found
Evidence for particle-hole excitations in the triaxial strongly-deformed well of ^{163}Tm
Two interacting, strongly-deformed triaxial (TSD) bands have been identified
in the Z = 69 nucleus ^{163}Tm. This is the first time that interacting TSD
bands have been observed in an element other than the Z = 71 Lu nuclei, where
wobbling bands have been previously identified. The observed TSD bands in
^{163}Tm appear to be associated with particle-hole excitations, rather than
wobbling. Tilted-Axis Cranking (TAC) calculations reproduce all experimental
observables of these bands reasonably well and also provide an explanation for
the presence of wobbling bands in the Lu nuclei, and their absence in the Tm
isotopes.Comment: 13 pages, 7 figure
Carbon materials as electrocatalysts for oxygen reduction in phosphoric acid medium
The behaviour of acstylene black (Indian grade) as catalyst support material is reported. The acetylene black is heat treated
(activated) at variour temperatures in nitrogen atmosphere. The surface area of the various heat treated samples is obtained.
Platinum is deporited into the carbon bye reported technique. The of platinum agglomeration on the carbon in identified
through scanning electron microscope.
The above catalyst is applied to glassy carbon disc. The electrochemical surface area of the catalyst ie determined by the hydrogen absorption and oxidation in alkaline medium. Similar electrodes (disc, dia 6 mm) are used in H3PO4 medium. Cyclic
vottammograms are obtained in the oxygen evolution region and oxygen reduction region. The exchange current density of
the catalyst for oxygen evolution and reduction ir reported for different catalyst loadings
High-spin structure and Band Termination in Cd
Excited states of the neutron deficient Cd nucleus have been
investigated via the Ge(Cl, p3n) reaction at beam energy of 135
MeV by use of in-beam spectroscopic methods. Gamma rays depopulating the
excited states were detected using the Gammasphere spectrometer with high-fold
-ray coincidences. A quadrupole -ray coincidence analysis
() has been used to extend the known level scheme. The positive
parity levels have been established up to and
MeV. In addition to the observation of highly-fragmented level scheme belonging
to the positive-parity sequences at E 5 MeV, the termination of a
negative-parity sequence connected by transitions has been established at
and MeV. The experimental results
corresponding to both the positive- and negative-parity sequences have been
theoretically interpreted in the framework of the core particle coupling model.
Evidence is presented for a shape change from collective prolate to
non-collective oblate above the (8011 keV) level and for a
smooth termination of the negative-parity band.Comment: 19 pages, 8 figures. Submitted to Phys. Rev.
High-spin structure and Band Termination in Cd
Excited states of the neutron deficient Cd nucleus have been
investigated via the Ge(Cl, p3n) reaction at beam energy of 135
MeV by use of in-beam spectroscopic methods. Gamma rays depopulating the
excited states were detected using the Gammasphere spectrometer with high-fold
-ray coincidences. A quadrupole -ray coincidence analysis
() has been used to extend the known level scheme. The positive
parity levels have been established up to and
MeV. In addition to the observation of highly-fragmented level scheme belonging
to the positive-parity sequences at E 5 MeV, the termination of a
negative-parity sequence connected by transitions has been established at
and MeV. The experimental results
corresponding to both the positive- and negative-parity sequences have been
theoretically interpreted in the framework of the core particle coupling model.
Evidence is presented for a shape change from collective prolate to
non-collective oblate above the (8011 keV) level and for a
smooth termination of the negative-parity band.Comment: 19 pages, 8 figures. Submitted to Phys. Rev.
A Composite Chiral Pair of Rotational Bands in the odd-A Nucleus 135Nd
High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd
reaction at a 30Si bombarding energy of 133 MeV. Two Delta(I)=1 bands with
close excitation energies and the same parity were observed. These bands are
directly linked by Delta(I)=1 and Delta(I)=2 transitions. The chiral nature of
these two bands is confirmed by comparison with three-dimensional tilted axis
cranking calculations. This is the first observation of a three-quasiparticle
chiral structure and established the primarily geometric nature of this
phenomenon.Comment: 10 pages, 5 figures (1 in color), 1 table, submitted to Physics
Review Letters, written in REVTEX4 forma
Lifetime measurements of Triaxial Strongly Deformed bands in Tm
With the Doppler Shift Attenuation Method, quadrupole transition moments,
, were determined for the two recently proposed Triaxial Strongly Deformed
(TSD) bands in Tm. The measured moments indicate that the
deformation of these bands is larger than that of the yrast, signature
partners. However, the measured values are smaller than those predicted by
theory. This observation appears to be valid for TSD bands in several nuclei of
the regionComment: 8 pages, 5 figures. Submitted to Physical Review
Level Structure of 103Ag at high spins
High spin states in Ag were investigated with the Gammasphere array,
using the Ge(Cl,)Ag reaction at an incident beam
energy of 135 MeV. A =1 sequence with predominantly magnetic
transitions and two nearly-degenerate doublet bands have been
observed. The dipole band shows a decreasing trend in the strength as
function of spin, a well established feature of magnetic bands. The
nearly-degenerate band structures satisfy the three experimental signatures of
chirality in the nuclei; however microscopic calculations are indicative of a
magnetic phenomeno
Uteroglobin Represses Allergen-induced Inflammatory Response by Blocking PGD2 Receptorâmediated Functions
Uteroglobin (UG) is an antiinflammatory protein secreted by the epithelial lining of all organs communicating with the external environment. We reported previously that UG-knockout mice manifest exaggerated inflammatory response to allergen, characterized by increased eotaxin and Th2 cytokine gene expression, and eosinophil infiltration in the lungs. In this study, we uncovered that the airway epithelia of these mice also express high levels of cyclooxygenase (COX)-2, a key enzyme for the production of proinflammatory lipid mediators, and the bronchoalveolar lavage fluid (BALF) contain elevated levels of prostaglandin D2. These effects are abrogated by recombinant UG treatment. Although it has been reported that prostaglandin D2 mediates allergic inflammation via its receptor, DP, neither the molecular mechanism(s) of DP signaling nor the mechanism by which UG suppresses DP-mediated inflammatory response are clearly understood. Here we report that DP signaling is mediated via p38 mitogenâactivated protein kinase, p44/42 mitogenâactivated protein kinase, and protein kinase C pathways in a cell typeâspecific manner leading to nuclear factorâÎșB activation stimulating COX-2 gene expression. Further, we found that recombinant UG blocks DP-mediated nuclear factorâÎșB activation and suppresses COX-2 gene expression. We propose that UG is an essential component of a novel innate homeostatic mechanism in the mammalian airways to repress allergen-induced inflammatory responses
Complex ferromagnetic state and magnetocaloric effect in single crystalline Nd_{0.7}Sr_{0.3}MnO_{3}
The magnetocaloric effect in single crystalline Nd_{0.7}Sr_{0.3}MnO_{3} is
investigated by measuring the field-induced adiabatic change in temperature
which reveals a single negative peak around 130 K well below the Curie
temperature (T_C=203 K). In order to understand this unusual magnetocaloric
effect, we invoke the reported {55}^Mn spin-echo nuclear magnetic resonance,
electron magnetic resonance and polarized Raman scattering measurements on
Nd_{0.7}Sr_{0.3}MnO_{3}. We show that this effect is a manifestation of a
competition between the double exchange mechanism and correlations arising from
coupled spin and lattice degrees of freedom which results in a complex
ferromagnetic state. The critical behavior of Nd_{0.7}Sr_{0.3}MnO_{3} near
Curie temperature is investigated to study the influence of the coupled degrees
of freedom. We find a complicated behavior at low fields in which the order of
the transition could not be fixed and a second-order-like behavior at high
fields.Comment: Accepted for publication in Phys. Rev.
Analog E1 transitions and isospin mixing
We investigate whether isospin mixing can be determined in a model-independent way from the relative strength of E1 transitions in mirror nuclei. The specific examples considered are the A=31 and A=35 mirror pairs, where a serious discrepancy between the strengths of 7/2--->5/2+ transitions in the respective mirror nuclei has been observed. A theoretical analysis of the problem suggests that it ought to be possible to disentangle the isospin mixing in the initial and final states given sufficient information on experimental matrix elements. With this in mind, we obtain a lifetime for the relevant 7/2- state in 31S using the Doppler-shift attenuation method. We then collate the available information on matrix elements to examine the level of isospin mixing for both A=31 and A=35 mirror pairs
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