1,149 research outputs found
Hydraulic forces caused by annular pressure seals in centrifugal pumps
The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity
Nuclear basket protein ZC3HC1 and its yeast homolog Pml39p feature an evolutionary conserved bimodular construction essential for initial binding to NPC-anchored homologs of scaffold protein TPR
Proteins ZC3HC1 and TPR are construction elements of the nuclear pore complex (NPC)-attached nuclear basket (NB). NB-location of ZC3HC1 depends on TPR already occurring NPC-anchored, whereas additional TPR polypeptides are appended to the NB by ZC3HC1. The current study examined the molecular properties of ZC3HC1 that enable it to bind to the NB and TPR. We report the identification and definition of a nuclear basket-interaction domain (NuBaID) of HsZC3HC1 comprising two similarly built modules, both essential for the binding to the NB’s NPC-anchored HsTPR. Furthermore, we describe such a bimodular construction as evolutionarily conserved and exemplify the kinship of HsZC3HC1 by the NB- and DdTPR-interacting homolog of Dictyostelium discoideum and by characterizing protein Pml39 as the ZC3HC1 homolog in Saccharomyces cerevisiae. Among several properties shared by the different species’ homologs, we unveil the integrity of the bimodular NuBaID of ScPml39p as being essential for binding to the yeast’s NBs and its TPR homologs ScMlp1p and ScMlp2p, and we further present Pml39p as enabling interlinkage of Mlp1p subpopulations. In addition to phyla-specific features, we delineate the three species’ common NuBaID as the characterizing structural entity of a one-of-a-kind protein found not in all but likely most taxa of the eukaryotic realm
Chondroprotective effects of Salubrinal in a mouse model of osteoarthritis
OBJECTIVES:
Salubrinal is a synthetic agent that elevates phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) and alleviates stress to the endoplasmic reticulum. Previously, we reported that in chondrocytes, Salubrinal attenuates expression and activity of matrix metalloproteinase 13 (MMP13) through downregulating nuclear factor kappa B (NFκB) signalling. We herein examine whether Salubrinal prevents the degradation of articular cartilage in a mouse model of osteoarthritis (OA).
METHODS:
OA was surgically induced in the left knee of female mice. Animal groups included age-matched sham control, OA placebo, and OA treated with Salubrinal or Guanabenz. Three weeks after the induction of OA, immunoblotting was performed for NFκB p65 and p-NFκB p65. At three and six weeks, the femora and tibiae were isolated and the sagittal sections were stained with Safranin O.
RESULTS:
Salubrinal suppressed the progression of OA by downregulating p-NFκB p65 and MMP13. Although Guanabenz elevates the phosphorylation level of eIF2α, it did not suppress the progression of OA.
CONCLUSIONS:
Administration of Salubrinal has chondroprotective effects in arthritic joints. Salubrinal can be considered as a potential therapeutic agent for alleviating symptoms of OA. Cite this article: Bone Joint Res 2015;4:84-92
Bipolar Charge Transport in Poly(3-hexyl thiophene)/Methanofullerene Blends: A Ratio Dependent Study
We investigated the charge carrier mobility in pristine poly(3-hexyl
thiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM)
blend devices by applying the time resolved photoconductivity experiment in
dependence on the donor:acceptor ratio. We observe a bipolar transport in all
studied samples ranging from pure polymer to polymer:fullerene with 90% PCBM
content. For the ratios P3HT:PCBM 1:4 and 1:1 we observe two transit times in
the electron current transients, as well as hole double transients for
P3HT:PCBM 1:2. We find high hole and electron mobilities in the order of
10^(-3) - 10^(-2) cm^2/Vs for a concentration of 90% PCBM in the blend.Comment: 3 pages, 1 table, 2 figures, minor corrections include
Gauge Theory Description of Spin Ladders
A s=1/2 antiferromagnetic spin chain is equivalent to the two-flavor massless
Schwinger model in an uniform background charge density in the strong coupling.
The gapless mode of the spin chain is represented by a massless boson of the
Schwinger model. In a two-leg spin ladder system the massless boson aquires a
finite mass due to inter-chain interactions. The gap energy is found to be
about .25 k |J'| when the inter-chain Heisenberg coupling J' is small compared
with the intra-chain Heisenberg coupling. k is a constant of O(1). It is also
shown that a cyclically symmetric N-leg ladder system is gapless or gapful for
an odd or even N, respectively.Comment: 8 pages. CORRIGENDUM has been incorporated. (A factor 2 error has
been corrected.
Mixed-Spin Ladders and Plaquette Spin Chains
We investigate low-energy properties of a generalized spin ladder model with
both of the spin alternation and the bond alternation, which allows us to
systematically study not only ladder systems but also alternating spin chains.
By exploiting non-linear model techniques we study the model with
particular emphasis on the competition between gapful and gapless states. Our
approach turns out to provide a more consistent semi-classical description of
alternating spin chains than that in the previous work. We also study a closely
related model, i.e., a spin chain with plaquette structure, and show that
frustration causes little effect on its low-energy properties so far as the
strength of frustration is weaker than a certain critical value.Comment: 7 pages, REVTeX, 3 figures, submitted to JPS
Scaling Properties of Antiferromagnetic Transition in Coupled Spin Ladder Systems Doped with Nonmagnetic Impurities
We study effects of interladder coupling on critical magnetic properties of
spin ladder systems doped with small concentrations of nonmagnetic impurities,
using the scaling theory together with quantum Monte Carlo (QMC) calculations.
Scaling properties in a wide region in the parameter space of the impurity
concentration x and the interladder coupling are governed by the quantum
critical point (QCP) of the undoped system for the transition between
antiferromagnetically ordered and spin-gapped phases. This multi-dimensional
and strong-coupling region has characteristic power-law dependences on x for
magnetic properties such as the N\'eel temperature. The relevance of this
criticality for understanding experimental results of ladder compounds is
stressed.Comment: 4 pages LaTeX including 3 PS figure
The free surface of superfluid 4He at zero temperature
The structure and energetics of the free surface of superfluid He are
studied using the diffusion Monte Carlo method. Extending a previous
calculation by Vall\'es and Schmidt, which used the Green's function Monte
Carlo method, we study the surface of liquid He within a slab geometry
using a larger number of particles in the slab and an updated interatomic
potential. The surface tension is accurately estimated from the energy of slabs
of increasing surface density and its value is close to one of the two existing
experimental values. Results for the density profiles allow for the calculation
of the surface width which shows an overall agreement with recent experimental
data. The dependence on the transverse direction to the surface of other
properties such as the two-body radial distribution function, structure factor,
and one-body density matrix is also studied. The condensate fraction, extracted
from the asymptotic behavior of the one-body density matrix, shows an
unambiguous enhancement when approaching the surface.Comment: RevTex, 11 pages, accepted in Phys. Rev.
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