Scanning tunnelling miscroscopy/spectroscopy and X-ray absorption spectroscopy studies of Co adatoms and anoislands on highly oriented pyrolytic graphite

In this paper, the scanning tunneling microscopy, scanning tunneling spectroscopy and X-ray absorption spectroscopy of cobalt adatoms and nanoislands were studied on a highly oriented pyrolytic graphite. Local electronic structure were observed by STS.\ud \u

Time-dependent linear response of an inhomogeneous Bose superfluid: Microscopic theory and connection to current-density functional theory

The dynamics of a confined fluid of Bose atoms is treated within the linear response regime, with a view to establishing a current-density functional formalism for an inhomogeneous superfluid state. After evaluating in full detail a simplified case of an external coupling to the density and phase of the condensate, the theory is extended to include the coupling to the total current density. The Kohn-Sham response functions of the condensate and all the exchange-correlation kernels for the superfluid are introduced from the microscopic equations of motion and are expressed in a physically transparent way through functional derivatives of correlation functions. A microscopic formula for the superfluid density is derived and used to introduce a generalized hydrodynamic approach for a weakly inhomogeneous two-fluid model in isothermal conditions. Local-density expressions are thereby derived for the velocities of first and second sound in the weakly inhomogeneous superfluid and for visco-elastic functions describing the transition from the hydrodynamic to the collisionless regime. Landau's hydrodynamic theory and known results in Green's functions language are recovered in the limiting case of a homogeneous superfluid.Comment: 25 pages, no figures, Postscript fil

Local mean-field study of capillary condensation in silica aerogels

We apply local mean-field (i.e. density functional) theory to a lattice model of a fluid in contact with a dilute, disordered gel network. The gel structure is described by a diffusion-limited cluster aggregation model. We focus on the influence of porosity on both the hysteretic and the equilibrium behavior of the fluid as one varies the chemical potential at low temperature. We show that the shape of the hysteresis loop changes from smooth to rectangular as the porosity increases and that this change is associated to disorder-induced out-of-equilibrium phase transitions that differ on adsorption and on desorption. Our results provide insight in the behavior of $^4$He in silica aerogels.Comment: 19 figure

Electron transport in nanotube--molecular wire hybrids

We study contact effects on electron transport across a molecular wire sandwiched between two semi-infinite (carbon) nanotube leads as a model for nanoelectrodes. Employing the Landauer scattering matrix approach we find that the conductance is very sensitive to parameters such as the coupling strength and geometry of the contact. The conductance exhibits markedly different behavior in the two limiting scenarios of single contact and multiple contacts between the molecular wire and the nanotube interfacial atoms. In contrast to a single contact the multiple-contact configuration acts as a filter selecting single transport channels. It exhibits a scaling law for the conductance as a function of coupling strength and tube diameter. We also observe an unusual narrow-to-broad-to-narrow behavior of conductance resonances upon decreasing the coupling.Comment: 4 pages, figures include

A Study Of Human T-Cell Lines Generated From Multiple Sclerosis Patients And Controls By Stimulation With Peptides Of Myelin Basic Protein

We generated T-cell lines from the peripheral blood of controls and of patients with multiple sclerosis (MS) by stimulation with overlapping synthetic peptides representing the entire sequences of all four isoforms of human myelin basic protein (MBP). The T-cell lines reacted to a wide range of epitopes in the major isoforms of MBP and to epitopes that were present only in the minor isoforms. Many MS patients and controls had T-cells responding to one or more cryptic MBP epitopes, as indicated by the generation of a peptide-specific T-cell line(s) by stimulation with synthetic peptides but not by stimulation with whole MBP. About one-third of the peptide-generated lines were cytotoxic. Although we have shown that this technique of peptide stimulation is effective in generating human antiviral cytotoxic CD8+ T-cell lines, all the cytotoxic MBP-specific lines generated by this method were predominantly CD4+. Our study did not reveal any significant differences, between MS patients and controls, in reactivity to epitopes within any of the isoforms of MBP

Intracellular changes in Ca2+, K+ and pH after sperm motility activation in the European eel (Anguilla anguilla): Preliminary results

[EN] Although it is widely accepted that osmolality and ion fluxes are the main factors triggering sperm motility in fish, a complex universal mechanism for sperm motility activation does not exist in fish, and studies of marine fish species are even more scarce. Therefore, the main goal of this study was to estimate the intracellular variations in the main ions involved in sperm activation for the first time in European eel, in order to provide additional new data about this little-known process. It was observed that levels of intracellular Ca2+ and K+ sperm ions increased significantly 30 s after the hyperosmotic shock compared to baseline levels, and remained at this level until 120 s post-activation. In contrast, the intracellular pH remained constant during the first 30 s, and decreased gradually at 60 and 120 s post-activation. Our data agree with the current main theory for explaining motility activation in marine fish, in which internal fluctuations of Ca2+ and K+ seem to participate in sperm activation. In addition, fluorescent images showed that both Ca2+ and K+ were concentrated in the apical area of the sperm head, which corresponds to the location of the eel sperm mitochondria, suggesting this organelle plays an important role in sperm motility activation. (C) 2013 Elsevier B.V. All rights reserved.Funded from the European Community's 7th Framework Programme under the Theme 2 "Food, Agriculture and Fisheries, and Biotechnology", grant agreement no 245257 (Pro-Eel) and the Spanish Ministry of Science and Innovation (MICINN; AGL2010-16009). Victor Gallego has a predoctoral grant (MICINN; BES-2009-020310) and has been granted a fellowship (EEBB-I-12-05858) of the Spanish Personnel Research Training Programme to carry out this study in the Universidad de Leon (Leon, Spain). Ilaria Mazzeo had a predoctoral grant from GVA. David S. Penaranda has a contract co-financed by MICINN and UPV (PTA2011-4948-I). F. Martinez-Pastor was supported by the Ramon y Cajal program (RYC-2008-02560, MICINN).Gallego Albiach, V.; Martínez Pastor, F.; Mazzeo, I.; Peñaranda, D.; Herraez, P.; Asturiano Nemesio, JF.; Pérez Igualada, LM. (2014). Intracellular changes in Ca2+, K+ and pH after sperm motility activation in the European eel (Anguilla anguilla): Preliminary results. Aquaculture. 418:155-158. https://doi.org/10.1016/j.aquaculture.2013.10.022S15515841

Draft genome sequence of antarctic psychrotroph Streptomyces fildesensis strain INACH3013, isolated from King George Island soil

The draft genome sequence of Streptomyces fildesensis strain INACH3013, a psychrotrophic bacterium isolated from Northwest Antarctic soil, was reported. The genome sequence totaling 9,306,785 bp resulted from 122 contigs characterized by a GC content of 70.55%

Pre-diagnostic serum concentrations of organochlorines and risk of acute myeloid leukemia: A nested case-control study in the Norwegian Janus Serum Bank Cohort

Background: Epidemiologic studies suggest an increased risk of leukemia among individuals occupationally exposed to some organochlorine (OC) compounds. Associations between serum OC pesticide and polychlorinated biphenyl (PCB) levels and risk of acute myeloid leukemia (AML), the most common subtype of acute leukemia in adult populations, have not been evaluated prospectively in the general population. Objective: We evaluated the risk of AML in relation to pre-diagnostic serum levels of OC pesticides and PCBs in a case-control study nested within the Janus Serum Bank Cohort. Methods: Janus is a large population-based cohort containing biologic samples collected beginning in the early 1970s from ~318,000 individuals in Norway. Serum levels of 11 OC pesticides or their metabolites and 34 PCB congeners were measured in 56 AML cases and 288 controls. Conditional logistic regression was conducted to evaluate associations between lipid-adjusted serum OC levels and risk of AML. Results: Higher serum levels of total chlordane/heptachlor metabolites were associated with AML risk (3rd vs. 1st tertile odds ratio (OR) = 2.26, 95% confidence interval (CI) = 0.91–5.63; ptrend = 0.11). Significant exposure-response associations were observed for levels of heptachlor epoxide (3rd vs. 1st tertile OR = 2.85, 95% CI = 1.05–7.73; ptrend = 0.02) and dieldrin (3rd vs. 1st tertile OR = 2.71, 95% CI = 1.07–6.83; ptrend = 0.03). No significant exposure-response associations with AML risk were observed for total DDT or individual isomers and derivatives. Higher serum levels of p,p′-DDT showed a non-significant increase in risk, but the exposure-response became attenuated when co-adjusting for heptachlor epoxide or dieldrin levels. Serum PCB levels were not significantly associated with AML risk. Conclusions: Our data suggest that higher serum levels of dieldrin and metabolites derived from chlordane/heptachlor are associated with risk of AML in the general Norwegian population, based on samples collected on average ~17 years before diagnosis. Further research in populations with historically high or recent exposure to DDT is warranted to assess the association with AML risk with body burden of specific DDT isomers and derivatives