6,229 research outputs found
Transport and the Order Parameter of Superconducting UPt3
We calculate the ultrasonic absorption and the thermal conductivity in the
superconducting state of UPt as functions of temperature and direction of
propagation and polarization. Two leading candidates for the superconducting
order parameter are considered: the and representations. Both
can fit the data except for the ultrasonic absorption in the phase. To do
that, it is necessary to suppose that the system has only a single domain, and
that must be chosen as the most favorable one. However, the theory
requires fine-tuning of parameters to fit the low temperature thermal
conductivity. Thus, transport data favor the theory. Measurements of
the thermal conductivity as a function of pressure at low temperature could
help to further distinguish the two theories.Comment: 7 pages, 4 figure
Thermal conductivity in B- and C- phase of UPt_3
Although the superconductivity in UPt_3 is one of the most well studied,
there are still lingering questions about the nodal directions in the B and C
phase in the presence of a magnetic field. Limiting ourselves to the low
temperature regime (T<<Delta(0)), we study the magnetothermal conductivity with
in semiclassical approximation using Volovik's approach. The angular dependence
of the magnetothermal conductivity for an arbitrary field direction should
clarify the nodal structure in UPt_3.Comment: 4 pages, 5 figure
Bromelain protease F9 reduces the CD44 mediated adhesion of human peripheral blood lymphocytes to human umbilical vein endothelial cells
AbstractThe thiol protease bromelain has been shown to remove T-cell CD44 molecules from lymphocytes and to affect T-cell activation. We investigated the effect of a highly purified bromelain protease F9 (F9) on the adhesion of peripheral blood lymphocytes (PBL) to human umbilical vein endothelial cells (HUVEC). Preincubation of the lymphocytes with F9 reduced the adherence to about 20% of unstimulated and to about 30% of phorboldibutyrate (P(Bu)2) stimulated lymphocytes. Using flow cytometry, both crude bromelain and protease F9 reduced the expression of CD44, but not of LFA-1, on PBL. F9 was about 10 times more active than crude bromelain; at 2.5 μg/ml of F9 about 97% inhibition of CD44 expression was found. A mAb against CD44 was tested and found to block the F9-induced decrease in PBL-binding to HUVEC. The results indicate that F9 selectively decreases the CD44 mediated binding of PBL to HUVEC
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