Fluidization of granular media wetted by liquid 4^4He

We explore experimentally the fluidization of vertically agitated PMMA spheres wetted by liquid $^4$He. By controlling the temperature around the $\lambda$ point we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization ($\Gamma_c$) shows a steep increase close to the saturation of the vapor pressure in the sample cell. For helium II wetting, $\Gamma_c$ starts to increase at about 75% saturation, indicating that capillary bridges are enhanced by the superflow of unsaturated helium film. Above saturation, $\Gamma_c$ enters a plateau regime where the capillary force between particles is independent of the bridge volume. The plateau value is found to vary with temperature and shows a peak at 2.1 K, which we attribute to the influence of the specific heat of liquid helium.Comment: 4 pages, 3 figures, Accepted by Phys. Rev. E as a rapid communicatio

Innovative Service-Based Business Concepts for the Machine Tool Building Industry

Organised by: Cranfield UniversityDuring the last decade, machine tool building companies have been forced to put innovative offers on the market. Due to the technical features of their products and the prevailing organizational structures in this sector, especially product-service systems are a promising way of creating a unique selling point. In this paper, potential new business concepts for machine tool builders will be presented which aim at fulfilling basic customer needs like the increase in quality, flexibility, productivity and the reduction of lead times, costs and risks. For the implementation of these product-service systems, practical examples are given.Mori Seiki – The Machine Tool Compan

99mTc-DTPA and 131I-hippuran findings in liver transplant recipients treated with cyclosporin A.

The effects of cyclosporin A (CyA), an immunosuppressive agent that is potentially nephrotoxic, on the kidneys of 9 liver transplant recipients were studied with serial 99mTc-DTPA and 131I-hippuran scans. In addition, renal function was determined by measuring serum creatinine levels during the second postoperative week in the 9 unselected CyA-treated patients and, retrospectively, in a control group of 29 liver transplant recipients who had not been treated with CyA and who were selected because they had survived for at least 3 months postoperatively. The early postoperative creatinine level was significantly greater in the CyA group. Eight of the 9 CyA patients showed imaging abnormalities in all preoperative and postoperative studies. Five of the 8 patients showed a pattern similar to that of acute tubular necrosis (relatively preserved perfusion) in at least one study. Lowering the dosage of CyA permitted the continuation of therapy, and all 9 patients are alive after 8 to 14 months

Coat/tether interactions-exception or rule?

Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers

Stationary state volume fluctuations in a granular medium

A statistical description of static granular material requires ergodic sampling of the phase space spanned by the different configurations of the particles. We periodically fluidize a column of glass beads and find that the sequence of volume fractions phi of post-fluidized states is history independent and Gaussian distributed about a stationary state. The standard deviation of phi exhibits, as a function of phi, a minimum corresponding to a maximum in the number of statistically independent regions. Measurements of the fluctuations enable us to determine the compactivity X, a temperature-like state variable introduced in the statistical theory of Edwards and Oakeshott [Physica A {\bf 157}, 1080 (1989)].Comment: published with minor change

Liver Allograft: Its Use in Chronic Active Hepatitis with Macronodular Cirrhosis, Hepatitis B Surface Antigen

A patient suffering from chronic active hepatitis with macronodular cirrhosis, positive for hepatitis B surface antigen (HBsAg), was treated with an orthotopic liver allograft. The HBs antigenemia, as measured with several precipitation tests and by complement fixation, became negative after transplantation and remained so for about 2½ months. During the interval, very low titers of the antigen were detectable by radioimmunoassay. At about three months after transplantation, she had an attack of acute hepatitis, at which time HBsAg became detectable by all tests. She recovered, but progressive liver disease developed during the remaining 1½ years of her life. She died of disseminated nocardiosis and candidiasis with deteriorating hepatic function. The homograft at autopsy showed no evidence of rejection, but was the site of chronic active liver disease, although of a different pathologic pattern than that affecting her native liver. The differences in histology may reflect the influence of chronic immunosuppression on the features of chronic active hepatitis. © 1979, American Medical Association. All rights reserved

Potential Energy Surface for H_2 Dissociation over Pd(100)

The potential energy surface (PES) of dissociative adsorption of H_2 on Pd(100) is investigated using density functional theory and the full-potential linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are identified which have a vanishing energy barrier. A pronounced dependence of the potential energy on ``cartwheel'' rotations of the molecular axis is found. The calculated PES shows no indication of the presence of a precursor state in front of the surface. Both results indicate that steering effects determine the observed decrease of the sticking coefficient at low energies of the H_2 molecules. We show that the topology of the PES is related to the dependence of the covalent H(s)-Pd(d) interactions on the orientation of the H_2 molecule.Comment: RevTeX, 8 pages, 5 figures in uufiles forma

Onset of mechanical stability in random packings of frictional spheres

Using sedimentation to obtain precisely controlled packings of noncohesive spheres, we find that the volume fraction $\phi_{\rm RLP}$ of the loosest mechanically stable packing is in an operational sense well defined by a limit process. This random loose packing volume fraction decreases with decreasing pressure $p$ and increasing interparticle friction coefficient $\mu$. Using X-ray tomography to correct for a container boundary effect that depends on particle size, we find for rough particles in the limit $p \to 0$ a new lower bound, $\phi_{\rm RLP} = 0.550 \pm 0.001$.Comment: significantly revised, published versio