MgB2 Superconducting Tips for Scanning Tunneling Microscopy Study

We report a simple method for the fabrication of reproducible, clean, and stable MgB₂ superconducting tips. The quality of these tips has been verified by imaging the surface of a thin Au(111) film sample, using a low temperature scanning tunneling microscopy (STM). Using the MgB₂ superconducting tip, high-quality semiatomically resolved STM surface images of the thin Au(111) film sample have been observed, which unambiguously indicates that the fabrication of relatively superconducting MgB₂, suitable for use as STM tips, is feasible.     

Engineering quantum confinement and orbital couplings in laterally coupled vertical quantum dots for spintronic applications

We use three-dimensional self-consistent Kohn-Sham's equations coupled with Poisson's equation to investigate the electrical behavior of laterally coupled vertical quantum dots (LCVQD) for spin-qubit operation. The shape and the depth of the central gate are changed in different ways to correlate gate geometry with the coupling between the two quantum dots. Upon comparing LCVQD single-gate and the split-gate structures, we found that the two inherently different designs result in different energy barrier profiles leading to dissimilar wavefunction coupling between the two dots. Finally, we show that the doping concentrations in the layered structure could be optimized for practical two-qubit operation.     

Gas-driven hydrogen permeation in the surface-limited regime

Gas-driven permeation of hydrogen through metal membranes in the surface-limited regime (SLR) is analyzed. An analytical solution for the concentration and permeation flux as a function of time is given for permeation through the asymmetric membrane having different conditions on the inlet and outlet sides. The features of the steady state and transient permeation are discussed. Comparison of calculations with an experiment on deuterium permeation through vanadium, which is available from literature, is performed. It has been demonstrated that the parameters, extracted from the measurements of the permeation rate in SLR are very uncertain. Even the calculations with opposite asymmetries can be equally well adjusted to the experiment. Non-zero initial conditions in SLR experiments are additional source of uncertainty. Measurements of the accumulation in a closed volume instead of the permeation rate can seriously mislead in the interpretation of the experiment. Complementary experiments on permeation in two opposite directions and measurements of permeation decay could increase the reliability of the data obtained.     

Apoptosis in cultured human colon cancer cells induced by combined treatments with 5-fluorouracil, tumor necrosis factor-alpha and interferon-alpha

An experimental study of Allergan's Oxysept Comfort system was performed by measuring the slight reddish hue that appears in the disinfecting solution, indicating to the users that their lenses are again ready to be worn. The temporal evolution of the color of the solution has been measured under standardized conditions and analyzed in the CIELAB system, from the perspective of the typical threshold discrimination of the human eye. Color differences between neutralized and non-neutralized solutions occurred in an appropriate direction of the color space to enhance discrimination and were clearly perceptible by normal observers (greater than 9.7 +/- 1.2 CIELAB units). Colorimetric analyses have been used to draw conclusions regarding observers with defective color vision. The color of the solution changes abruptly, approximately 25 min after the neutralization process begins, and remains nearly constant after about 60 min, this agreeing well with the temporal evolution of the hydrogen peroxide concentration.     

0.1-μm gate-length superconducting FET

A superconducting field-effect transistors (FET) with a 0.1-μm-length gate electrode was fabricated and tested at liquid-helium temperature. Two superconducting electrodes (source and drain) were formed on the same Si substrate surface with an oxide-insulated gate electrode by a self-aligned fabrication process. Superconducting current flowing through the semiconductor (Si) between the two superconducting electrodes (Nb) was controlled by a gate-bias voltage     

Acute ingestion of yerba mate infusion (Ilex paraguariensis) inhibits plasma and lipoprotein oxidation

Yerba mate extract (Ilex paraguariensis) is a source of phenolic compounds that possesses in vitro antioxidant activities and may contribute to a reduction in the risk of cardiovascular disease. In this study we examined the acute effects of the consumption of mate infusion on ex vivo plasma and low-density lipoprotein (LDL) oxidation, plasma antioxidant capacity, and platelet aggregation. Twelve healthy fasted subjects ingested 500 mL of mate infusion and blood samples were collected before and 1 h after mate intake. Lipid peroxidation of plasma and LDL was monitored by the measurement of cholesteryl-ester hydroperoxides (CE-OOH) and cholesterol oxides. The plasma antioxidant capacity was measured as ferric-reducing antioxidant potential (FRAP). Platelet aggregation was evaluated in platelet-rich plasma stimulated with adenosine diphosphate and coagulation was tested in platelet-poor plasma. Ingestion of mate infusion diminished the ex vivo oxidizability of both plasma and LDL particles. After mate intake, the CE-OOH levels were around 50% lower in plasma oxidized with copper or 2,2′-azobis[2-amidine-propane-hydrochloride] (AAPH) and the lag time to plasma oxidation increased 2-fold (P < 0.05). Copper- and AAPH-induced LDL peroxidation were also inhibited by around 50% and 20%, respectively, after mate consumption (P < 0.05). The levels of various oxysterols were significantly reduced in oxidized-plasma and LDL (P < 0.05) and FRAP increased by 7.7% after mate intake (P < 0.01). However, mate consumption did not inhibit platelet aggregation or blood coagulation. In summary, intake of yerba mate infusion improved the antioxidant capacity and the resistance of plasma and LDL particles to ex vivo lipid peroxidation.     

Improvement in high temperature stability of Pd coating on Nb by Nb2C intermediate layer

Niobium subcarbide (Nb₂C) was chosen as a material for non-porous intermediate layer to improve the high temperature durability of Pd–Nb composite membranes for hydrogen separation. A layer of Nb₂C was prepared between Nb substrate and thin Pd films (100 nm), and the stability of Pd coating at elevated temperatures (573–773 K) was examined by hydrogen absorption experiments. Hydrogen permeability through the Nb₂C layer appeared to be sufficiently high, and no noticeable deterioration was observed in hydrogen absorption rate under as-prepared conditions. The degradation in coating effect of Pd at elevated temperatures was substantially mitigated by Nb₂C layer. Such improved durability was ascribed to retardation of open porosity development by Nb₂C caused as a consequence of impeded interdiffusion between Pd and Nb.     

Quantum Oscillations of Thermoelectric Effects in a Pseudo-one-dimensional Electron Gas With a Spin–Orbit Interaction

We consider thermoelectric effects in a pseudo-one-dimensional electron gas (P1DEG) with a spin–orbit interaction (SOI). The SOI splits the dispersion relation of the P1DEG into subbands with an energy gap. We find quantum oscillations in transport coefficients, which coincide with the locations of the subband edges, as a function of the electrochemical potential.     

Isolation and characterization of hardening-induced proteins in Chlorella vulgaris C-27: identification of late embryogenesis abundant proteins

Hardening-induced soluble proteins of Chlorella vulgaris Beijerink IAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27) were isolated and purified by two-dimensional high-performance liquid chromatography (2D-HPLC) on an anion-exchange column, with subsequent reversed-phase chromatography. Some of the proteins were resolved by SDS-PAGE, characterized by amino-terminal sequencing and identified by searching for homologies in databases. Separation of the soluble proteins during the hardening of Chlorella by a combination of 2D-HPLC and SDS-PAGE revealed that at least 31 proteins were induced or increased in abundance. Of particular interest was the induction after 12 h of a 10-kDa protein with the amino-terminal amino acid sequence AGNKPITEQISDAVGAAGQKVG and the induction after 6 h of a 14-kDa protein with the amino-terminal sequence ALGEESLGDKAKNAFEDAKDAVKDAAGNVKEAV. The amino-terminal sequences of these proteins indicated that they were homologous to late embryogenesis abundant (LEA) proteins. Furthermore, the level of a 22-kDa protein also increased after 12 h. The amino-terminal sequence of this protein, AAPLVGGPAPDFTAAAVFD, indicated that it was homologous to thioredoxin peroxidase.