Using ion implantation to adjust the transition temperature of superconducting films

We summarize a continuing investigation into using ion implantation to alter the transition temperature of superconducting thin films. The primary motivation for the work presented here was to study the feasibility of using magnetic ion doping to replace the bi-layer T_c control process currently used for certain cryogenic detector applications at National Institute for Standards and Technology. The results from work with various ion species implanted into aluminum, molybdenum, titanium and tungsten host films are presented.     

Resonant Quantum Phenomena for an rf-SQUID: Moderate Underdamped and Extreme Underdamped Limit

We study the resonant quantum behaviour of a macroscopic superconducting system interacting with an external field. First we consider the resonant tunneling assisted by microwave frequency in the moderate underdamped quantum regime. Then we consider the resonant process in the extreme underdamped limit. In both regimes we have investigated a small frequency range, where resonant phenomena take place. The transition probability W from the left to the right potential well has been numerically calculated for an rf-SQUID as function of the external flux φ _x for both regimes. Results indicate that, in a proper frequency and φ _x range, the transition probability W can present two or three resonant peaks, depending on the damping regime.     

High growth rate process in a SiC horizontal CVD reactor using HCl

The results of a new epitaxial process using an industrial 6 × 2″ wafer reactor with the introduction of HCl during the growth have been reported. A complete reduction of silicon nucleation in the gas phase has been observed even for high silicon dilution parameters (Si/H₂ > 0.05%) and an increase of the growth rate until about 20 μm/h has been measured. Photoluminescence at room temperature and at 50 K was used for defects quantification and distribution. On these wafers grown using HCl high voltage Schottky diodes have been realized. The diodes were analyzed by current-voltage (I-V) characteristics.     

Exchange of free cholesterol between plasma and erythrocytes from hyperthyroid and hypothyroid ratsin Vitro

In our previous studies, we found that circulating thyroid hormone levels alter cholesterol partition between plasma and erythrocytes by changing the phospholipid content of erythrocytes (Ruggiero, F.M.,et al. (1984)Horm. Metabol. Res. 16, 37–40; Ruggiero, F.M.,et al. (1987)Lipids 22, 148–151). As an extension of this work, we now followed the exchange of free cholesterol between plasma and erythrocytes in control, hyperthyroid and hypothyroid rats under various experimental conditionsin vitro. In control rats, erythrocytes incubated with plasma at 37°C for 4 hr lose 10% of cholesterol which was esterified by lecithin: cholesterol acyltransferase (LCAT) present in the plasma. In hyperthyroid rats, erythrocytes incubated with plasma lose 30% of cholesterol within the same time. By contrast, in the case of hypothyroid rats incubation for 4 hr was necessary to transfer 24% of free cholesterol from plasma to erythrocytes. Inhibition of cholesterol esterification did not affect the loss of erythrocyte cholesterol in control and in hyperthyroid rats. Ca²⁺ increased the LCAT activity in the plasma of these rats. The findings shed light on the role of thyroid hormones in regulating cholesterol levels in plama through active cholesterol transfer between plasma and erythrocytes.     

Influence of inorganic soil components and humic substances on the mechanochemical removal of pentachlorophenol

The influence of the presence of humic acids of different origin on the catalytic transformation of pentachlorophenol (PCP) by two metal oxides, ferrihydrite and birnessite, using mechanochemical contact was studied. The mechanochemical dry contact with light grinding of PCP and birnessite was more effective than that observed in the presence of ferrihydrite (approximately 70 and 40% of PCP removal after 20 days, respectively). The removal of PCP by birnessite and ferrihydrite was significantly enhanced in the presence of humic acid (HA). The different origin of humic acids (agricultural, forest and commercial) showed a slight influence on the overall reaction. The commercial HA, when mixed with birnessite, was more effective in reducing PCP concentration compared to the others two HAs investigated. The transformation process in the presence of birnessite with and without HA was accompanied by the release of four chlorides per molecule of PCP transformed.     

Structural Plasticity Is a Feature of Rheostat Positions in the Human Na+/Taurocholate Cotransporting Polypeptide (NTCP)

In the Na⁺/taurocholate cotransporting polypeptide (NTCP), the clinically relevant S267F polymorphism occurs at a “rheostat position”. That is, amino acid substitutions at this position (“S267X”) lead to a wide range of functional outcomes. This result was particularly striking because molecular models predicted the S267X side chains are buried, and thus, usually expected to be less tolerant of substitutions. To assess whether structural tolerance to buried substitutions is widespread in NTCP, here we used Rosetta to model all 19 potential substitutions at another 13 buried positions. Again, only subtle changes in the calculated stabilities and structures were predicted. Calculations were experimentally validated for 19 variants at codon 271 (“N271X”). Results showed near wildtype expression and rheostatic modulation of substrate transport, implicating N271 as a rheostat position. Notably, each N271X substitution showed a similar effect on the transport of three different substrates and thus did not alter substrate specificity. This differs from S267X, which altered both transport kinetics and specificity. As both transport and specificity may change during protein evolution, the recognition of such rheostat positions may be important for evolutionary studies. We further propose that the presence of rheostat positions is facilitated by local plasticity within the protein structure. Finally, we note that identifying rheostat positions may advance efforts to predict new biomedically relevant missense variants in NTCP and other membrane transport proteins.     

3D Active Edge Silicon Detector Tests With 120 GeV Muons

3D detectors with electrodes penetrating through the silicon wafer and covering the edges were tested in the SPS beam line X5 at CERN in autumn 2003. Detector parameters including efficiency, signal-to-noise ratio, and edge sensitivity were measured using a silicon telescope as a reference system. The measured sensitive width and the known silicon width were equal within less than 10 mum.     

Terrorism Communication: Characteristics and Emerging Perspectives in the Scientific Literature 2002–2011

This paper aims to clarify current knowledge on the contribution of communication to crisis management in the case of terrorism incidents. This is done by means of a systematic review of the scientific literature on terrorism communication over the last 10 years to identify the many challenges facing communication in such crises, and represents the first attempt of its kind. To date, within the literature on terrorism communication, much attention has been paid to chemical, biological, radiological or nuclear hazards. Terrorism crises are complex and challenging. Preparedness for such diverse low‐probability high‐impact crises can best be included in a wider educative approach. Terrorism crises call for fast information updates that, using a multi‐channel approach, can be tailored to fit different needs and (social) media habits.