Dielectrophoretically controlled fabrication of single-crystal nickel silicide nanowire interconnects

We report here on applying electric fields and dielectric media to achieve controlled alignment of single-crystal nickel silicide nanowires between two electrodes. Depending on the concentration of nanowire suspension and the distribution of electrical field, various configurations of nanowire interconnects, such as single, chained, and branched nanowires were aligned between the electrodes. Several alignment mechanisms, including the induced charge layer on the electrode surface, nanowire dipole-dipole interactions, and an enhanced local electrical field surrounding the aligned nanowires are proposed to explain these novel dielectrophoretic phenomena of one-dimensional nanostructures. This study demonstrates the promising potential of dielectrophoresis for constructing nanoscale interconnects using metallic nanowires as building blocks.     

Effective Modulation of CNS Inhibitory Microenvironment using Bioinspired Hybrid-Nanoscaffold-Based Therapeutic Interventions

Central nervous system (CNS) injuries are often debilitating, and most currently have no cure. This is due to the formation of a neuroinhibitory microenvironment at injury sites, which includes neuroinflammatory signaling and non-permissive extracellular matrix (ECM) components. To address this challenge, a viscous interfacial self-assembly approach, to generate a bioinspired hybrid 3D porous nanoscaffold platform for delivering anti-inflammatory molecules and establish a favorable 3D-ECM environment for the effective suppression of the neuroinhibitory microenvironment, is developed. By tailoring the structural and biochemical properties of the 3D porous nanoscaffold, enhanced axonal growth from the dual-targeting therapeutic strategy in a human induced pluripotent stem cell (hiPSC)-based in vitro model of neuroinflammation is demonstrated. Moreover, nanoscaffold-based approaches promote significant axonal growth and functional recovery in vivo in a spinal cord injury model through a unique mechanism of anti-inflammation-based fibrotic scar reduction. Given the critical role of neuroinflammation and ECM microenvironments in neuroinhibitory signaling, the developed nanobiomaterial-based therapeutic intervention may pave a new road for treating CNS injuries.     

Longitudinal stability of personality traits: A multitrait–multimethod–multioccasion analysis.

The longitudinal stability of personality was investigated in a group of several hundred adults who were rated by themselves, their marriage partners, and their acquaintances in 1935-1938 and by themselves and their marriage partners in 1954-1955. For both men and women, there were very similar factorial structures in all five sources of ratings. Individual differences in neuroticism, social extraversion, and impulse control had reasonably high levels of longitudinal stability over a 19-year period. Both the synchronic and diachronic correlations converged across methods and discriminated among traits. Self-report personality inventory data available in 1935-1938 and 1954-1955 provided corroborating evidence of the longitudinal and methodological robustness of personality traits. In data gathered on the same panel in 1980-1981, the questionnaire and the life history correlates of neuroticism and social extraversion displayed patterns indicative of temporal stability, methodological convergence, and discrimination among constructs. The data of this longitudinal study carried out over five decades strongly indicate that there is a set of personality traits that are generalizable across methods of assessment and are stable throughout adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Teaching Teachers to Teach Engineering—T4E

The essence of a teacher‐training program that has proven to be successful with faculty from around the nation, and the world, is presented. T⁴ E is a week‐long short course run at the United States Military Academy at West Point, NY. The goal of this short course is to provide participants with a solid foundation of effective teaching skills that they can subsequently build upon as they continue to teach. The focus of T⁴ E is on well organized classes presented in a clear and logical fashion that promotes the active participation of students.     

Oxyanion-mediated inhibition of serine proteases

Novel aryl derivatives of benzamidine were synthesized and tested for their inhibitory potency against bovine trypsin, rat skin tryptase, human recombinant granzyme A, human thrombin, and human plasma kallikrein. All compounds show competitive inhibition against these proteases with Ki values in the micromolar range. X-ray structures were determined to 1.8 A resolution for trypsin complexed with two of the para-substituted benzamidine derivatives, 1-(4-amidinophenyl)-3-(4-chlorophenyl)urea (ACPU) and 1-(4-amidinophenyl)-3-(4-phenoxyphenyl)urea (APPU). Although the inhibitors do not engage in direct and specific interactions outside the S1 pocket, they do form intimate indirect contacts with the active site of trypsin. The inhibitors are linked to the enzyme by a sulfate ion that forms an intricate network of three-centered hydrogen bonds. Comparison of these structures with other serine protease structures with noncovalently bound oxyanions reveals a pair of highly conserved oxyanion-binding sites in the active site. The positions of noncovalently bound oxyanions, such as the oxygen atoms of sulfate, are distinct from the positions of covalent oxyanions of tetrahedral intermediates. Noncovalent oxyanion positions are outside the "oxyanion hole." Kinetics data suggest that protonation stabilizes the ternary inhibitor/oxyanion/protease complex. In sum, both cations and anions can mediate Ki. Cation mediation of potency of competitive inhibitors of serine proteases was previously reported by Stroud and co-workers [Katz, B. A., Clark, J. M., Finer-Moore, J. S., Jenkins, T. E., Johnson, C. R., Ross, M. J., Luong, C., Moore, W. R., and Stroud, R. M. (1998) Nature 391, 608-612].     

Material Characterization of Ge1−x Sn x Alloys Grown by a Commercial CVD System for Optoelectronic Device Applications

High-quality compressive-strained Ge_1?x Sn _x /Ge films have been deposited on Si(001) substrate using a mainstream commercial chemical vapor deposition reactor. The growth temperature was kept below 450°C to be compatible with Si complementary metal–oxide–semiconductor processes. Germanium tin (Ge_1?x Sn _x ) layers were grown with different Sn composition ranging from 0.9% to 7%. Material characterizations, such as secondary-ion mass spectrometry, Rutherford backscattering spectrometry, and x-ray diffraction analysis, show stable Sn incorporation in the Ge lattice. Comparison of the Sn mole fractions obtained using these methods shows that the bowing factor of 0.166 nm (in Vegard’s law) is in close agreement with other experimental data. High-resolution transmission electron microscopy and atomic force microscopy results show that the films have started to relax through the formation of misfit and threading dislocations. Raman spectroscopy, ellipsometry, and photoluminescence (PL) techniques are used to study the structural and optical properties of the films. Room-temperature PL of the films shows that 7% Sn incorporation in the Ge lattice results in a decrease in the direct bandgap of Ge from 0.8 eV to 0.56 eV.     

Nonlinear and nonplanar dynamics of suspended nanotube and nanowire resonators

Previous works on suspended carbon nanotube and nanowire resonators assume a priori that they oscillate in a single plane. We explore the nonlinear dynamics of such resonators and demonstrate that they can suddenly transition from a planar motion to a whirling, "jump rope" like motion. We identify nondimensional gate voltage, resonator geometry, quality factor, and flexural and axial elastic stiffnesses for which such motions can arise. The deliberate use of nonlinear and nonplanar motions opens up a variety of new modalities for this class of nanoelectromechanical systems that are not accessible in the linear operating regime.     

Predictions of displacements and stresses in cracked reinforced concrete containment vessels subjected to seismic loads

A three dimensional, nonlinear finite element analysis capability for analysis of cracked reinforced concrete nuclear containment vessels is described. A bilinear shear stress-shear strain model, based on experiments, is used to study the distribution of radial and tangential shear produced by horizontal seismic loading. Results show substantial redistribution of tangential shear, and significant increases in radial shear, peak bending stress, and vessel displacement, as compared to conventional linear analysis results.     

Experience curves as a planning tool

Observers have found that the ``learning-curve' phenomenon occurs in many complex situations and is not confined to the human learning of repetitive manual skills. If experience improves performance, it should follow that the company that has produced the most widgets will be the most efficient widget producer. This implies that market share is vital in determining potential profitability and that new products, whether developed internally or acquired outside, are doomed to lackluster financial performance unless they capture a dominant market position. The learning-curve effect and its more generalized experience-curve companions are reviewed in this article. Some typical cost and price experience curves are discussed along with the technical details of their derivation. The possible inferences that can be drawn from the observed facts are examined and tested for their qualitative agreement with certain known trends and tendencies.