Synthesis of Au microwires by selective oxidation of Au–W thin-film composition spreads

Abstract

We report on the stress-induced growth of Au microwires out of a surrounding Au–W matrix by selective oxidation, in view of a possible application as ‘micro-Velcro’. The Au wires are extruded due to the high compressive stress in the tungsten oxide formed by oxidation of elemental W. The samples were fabricated as a thin-film materials library using combinatorial sputter deposition followed by thermal oxidation. Sizes and shapes of the Au microwires were investigated as a function of the W to Au ratio. The coherence length and stress state of the Au microwires were related to their shape and plastic deformation. Depending on the composition of the Au–W precursor, the oxidized samples showed regions with differently shaped Au microwires. The Au₄₈W₅₂ composition yielded wires with the maximum length to diameter ratio due to the high compressive stress in the tungsten oxide matrix. The values of wire length (35 μm) and diameter (2 μm) achieved at the Au₄₈W₅₂ composition are suitable for micro-Velcro applications.     

Surgical education via the Internet: the Cardiothoracic Surgery Network

The Cardiothoracic Surgery Network is an international collaborative effort among cardiothoracic surgeons that provides a common platform for the exchange of information. The Cardiothoracic Surgery Network website provides peer-reviewed journals, multimedia applications, and a database repository.     

The computer as a zone of proximal development: Internalizing reading-related metacognitions from a Reading Partner.

We hypothesized that computer tools that provide models, opportunity for higher level thinking, and metacognitivelike guidance (e.g., "Can I conjure up an image of the story?") can serve in a learner's zone of proximal development (L. S. Vygotsky, 1978); they can develop competencies through internalization. A computerized Reading Partner presented four reading principles and metacognitivelike questions during the reading of 11 texts over three reading sessions. It was compared with one version that presented the texts with factual and inferential questions and a control version that presented only the texts. Seventh graders using the Reading Partner (n?=?25) reported the expenditure of more mental effort in the process, showed far better metacognitive reconstruction, and improved significantly more in their later reading comprehension and in the quality of their written essays than did the subjects in the other groups. Improvements in reading and writing were statistically accounted for by subjects' ability for metacognitive reconstruction. The study reinforces previous findings pertaining to the role of metacognitions in reading and shows that well-designed computer tools can cultivate competence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cardiovascular reactivity during social and nonsocial stressors: Do children's personal goals and expressive skills matter?

The relationships between social competence and cardiovascular reactivity were evaluated in 180 children (ages 8-17; 52% female; 53% Caucasian). Participants performed a social task (Social Competence Interview [SCI]) and 2 nonsocial tasks while reactivity measures were obtained. Social competence was coded from SCI audiotapes. Among adolescents, higher scores on the Acceptance-Affiliation subscale were associated with increased heart rate (HR) and blood pressures and with decreased HR variability during the SCI. Among boys, greater Acceptance-Affiliation scores were associated with increased vascular reactivity during the SCI. During the nonsocial tasks, higher Self-Defensiveness and Expressiveness scores were associated with increased cardiac output and stroke volume among African American children. Personal strivings and expressive skills do matter for understanding cardiovascular responses in children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of high-T c oxide films via flaming solvent spray

Thick films of the high-temperature superconductors YBa₂Cu₃O_7?x and Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀ have been prepared by spraying an ignited ethanol, ethylene glycol, or liquid ammonia solution of stoichiometric amounts of the metal nitrates (or acetates) onto polycrystalline MgO. The flaming spray is mechanically forced to traverse a region directly in front of the substrates. This new method is simple and inexpensive, and eliminates the problem of substrate cooling encountered in normal spray pyrolysis methods. Since decomposition of the solvent and metal salts occurs before deposition, the resulting films are relatively free of craters and nonuniformities common with spray methods. The method can be adapted to coat large areas and irregular or nonplanar shapes (i.e., cylinders), which could have useful magnetic shielding properties. The films were characterized by XRD and show single-phase material with preferredc-axis orientation. For YBa₂Cu₃O_7?x , resistance vs. temperature measurements show aT _c onset at 90 K and aT _c 0 at 76 K. Silver nitrate has been added to some of the solutions in an attempt to improve contact among individual grains.     

"After Me,The Deluge": Uncertainty and Water Policy in Israel

Israel's water system is characterized by a very high degree of uncertainty, emanating from the semi-arid climatic position, and the dynamic population growth.The agricultural sector dominates water policy making, thereby giving preference to the sector that consumes roughly 70% of the available resources. Water for agriculture is priced too low, resulting in its inefficient use. This paper seeks to explain water policy making in Israel, as an attempt to cope with uncertainty. We show that the pattern has been to shift the burden of uncertainty from present consumers to future consumers. This pattern is explained by the following factors: the high vulnerability of Israel's water system, due to uncertainty in both supply and demand; the inclination of elected policy makers to give preference to short-term objectives over long-term objectives; the acceptance of uncertainty as a constraint rather than a policy variable; and the acceptance of a given level of agricultural activity as a permanent constraint.     

Levuglandin E2-protein adducts in human plasma and vasculature

The prostaglandin endoperoxide PGH2 rearranges nonenzymatically to generate prostaglandins and secoprostanoic acid levulinaldehyde derivatives such as PGE2 and levuglandin (LG) E2, respectively. Direct detection of LGE2 in biological samples is complicated because it is rapidly sequestered by covalent adduction to endogenous nucleophiles including proteins, which produces LGE2-derived protein-bound pyrroles. Therefore, to detect LGE2-protein adducts in vivo, antibodies were raised against a covalent adduct of LGE2 with keyhole limpet hemocyanin (KLH). This antigen enabled the production of high-titer antibodies that exhibit minimal cross-specificity and are sensitive for detecting LGE2-derived pyrroles. Although pyrrole yields are low at LG/protein ratios found in vivo, an enzyme-linked immunosorbent assay with the LGE2-KLH antibodies detects LGE2-derived protein-bound pyrrole immunoreactivity in human plasma from specific patient populations. Furthermore, prominent immunocytochemical staining of human brain thin sections revealed the presence of LGE2-derived pyrrole immunoreactivity, especially in the meningeal vessels of some patients. This demonstration of LG-protein adducts in human plasma and vasculature provides the first evidence for the biological occurrence of levuglandins in vivo and further suggests that these antibodies might prove useful in diagnostic and mechanistic studies of various disease conditions.