פרסומים

Hybrid nanostructures are attractive for future use in a variety of optoelectronic devices. Self-assembled hybrid organic/quantum dots can couple quantum properties to semiconductor devices and modify their functionality. These devices are simple to fabricate and control; however, they usually demonstrate low quantum efficiency. In this work we present experimental results of large extinction enhancement from a monolayer of colloidal quantum dots using a thin gold film evaporation forming random gold nanoparticles that act as plasmonic antennas. The random structures guarantee no sensitivity to polarization changes. The fabrication process of the plasmonic gold nanoparticles is simple and cheap and can be easily integrated with existing semiconductor devices. By matching the plasmonic resonance and the colloidal quantum dots bandgap we achieve up to 16% light extinction, which is 13-fold enhancement, compared to the reference. These results may pave the way toward realizing more efficient and sensitive photon detectors. Hybrid nanostructures are attractive for future use in a variety of optoelectronic devices. Self-assembled hybrid organic/quantum dots can couple quantum properties to semiconductor devices and modify their functionality. These devices are simple to fabricate and control; however, they usually demonstrate low quantum efficiency. In this work we present experimental results of large extinction enhancement from a monolayer of colloidal quantum dots using a thin gold film evaporation forming random gold nanoparticles that act as plasmonic antennas. The random structures guarantee no sensitivity to polarization changes. The fabrication process of the plasmonic gold nanoparticles is simple and cheap and can be easily integrated with existing semiconductor devices. By matching the plasmonic resonance and the colloidal quantum dots bandgap we achieve up to 16% light extinction, which is 13-fold enhancement, compared to the reference. These results may pave the way toward realizing more efficient and sensitive photon detectors.

We report the fabrication of a new selective "inverse tandem" absorbing coating based on carbon nanotube (CNT)/indium-tin oxide (ITO) on aluminum (Al) for mid-temp. solar-thermal application. The CNT layer is formed by spraying and functions as an excellent solar absorber whereas the ITO layer produced on top of the CNTs by sputtering serves as an IR reflector. The effect of the thickness of the ITO on the spectral selectivity of the absorbing coating was investigated. Controlling the thickness of ITO allowed the spectral selectivity of the coating to be tuned. The CNT/ITO solar coatings with optimized thickness of ITO showed excellent spectral selectivity values of absorptance (α) of 0.927 and emittance (ε) of 0.2. The performance of the coatings at high temp. after heating in air in the range of 25-300°C for different durations was also investigated. The performance and structure of the CNT/ITO coating was also compared with the wet deposition method in which the ITO coating was formed by spraying. [on SciFinder(R)]

Transparent conductive films composed of CuS were formed by wet deposition on PET at room temp. followed by annealing at 100° for 1 h. The resistance of the films was tuned by doping with In3+. A decrease of over an order of magnitude of the sheet resistance was obtained, from 1721 Ω sq-1 for undoped CuS film to 109 Ω sq-1 for In3+ doped. Transparency of the conducting films could be tuned by an appropriate selection of reaction time and In3+ concn. Films contg. 10 mol% of In3+ ions after a reaction duration of 24 h have a sheet resistance of \~270 Ω sq-1 and a transparency of \~80%. The fabricated films are characterized by excellent adhesion to the PET substrate and are suitable for use as transparent conducting electrodes (TCE) in flexible electroluminescent (EL) devices. [on SciFinder(R)]

Questionnaires were given to 392 elementary school teachers to examine help-seeking or help-avoidance in dealing with classroom behavioral problems. Scale validity was examined through a series of exploratory and confirmatory factor analyses. Using a series of multivariate regression analyses and structural equation modeling, we identified predictors of motivational goals, predictors of attitudes toward help-seeking or help-avoidance, and a model of teachers’ attitudes toward help-seeking or help-avoidance. Results revealed four types of attitudes. Two reflected a positive approach to seeking help, but for different reasons: the first is intended to end the confrontation rapidly, and the second strives to develop new coping abilities. Also, two avoidant behaviors intended to avoid seeking help were revealed: one from fear of failure, and the other from a desire to deal with the problems independently. These four positions support a model of teacher help-seeking, where seeking or avoiding help arises from a combination of implicit theories, efficacy beliefs, and motivational goals. Suggestions for further research into motivational factors of teachers when seeking help in coping with behavioral problems are suggested, as well as a call for a renewed consideration of the effectiveness of teacher support mechanisms.

The role of human capital and physical capital in determining regional productivity and innovation is examined. Two specific mechanisms through which knowledge becomes an inherently regional asset are investigated: the generation of local externalities (a stock mechanism) and human capital accumulation and mobility (a flow mechanism). Empirically, this connection is investigated using recent advances in spatial panel data analysis applied to regions in Israel. Panel co-integration is used to entangle issues of spurious relationships. Results show that human capital stock has large and relatively consistent effects on both regional earnings and regional innovation levels. Human capital mobility is inversely related to innovation. This is interpreted as reflecting the ‘conduit’ role of the region in the innovation process. Regional capital-to-labour ratios are also inversely related to innovation, implying that physical capital substitutes rather than complements human capital.

Feasible elimination procedures (Peleg, 1978) play a central role in constructing social choice functions which have the following property: in the associated game form, for any preference profile there exists a strong Nash equilibrium resulting in the sincere outcome. In this paper we provide an axiomatic characterization of the social choice correspondence resulting from applying feasible elimination procedures. The axioms are anonymity, Maskin monotonicity, and independent blocking.

Acylsugars are insecticidal specialized metabolites produced in the glandular trichomes of plants in the Solanaceae family. In the tomato clade of the Solanum genus, acylsugars consist of aliphatic acids of different chain lengths esterified to sucrose, or less frequently to glucose. Through liquid chromatography-mass spectrometry screening of introgression lines, we previously identified a region of chromosome 8 in the Solanum pennellii LA0716 genome (IL8-1/8-1-1) that causes the cultivated tomato Solanum lycopersicum to shift from producing acylsucroses with abundant 3-methylbutanoic acid acyl chains derived from leucine metabolism to 2-methylpropanoic acid acyl chains derived from valine metabolism. We describe multiple lines of evidence implicating a trichome-expressed gene from this region as playing a role in this shift. S. lycopersicum M82 SlIPMS3 (Solyc08g014230) encodes a functional end product inhibition-insensitive version of the committing enzyme of leucine biosynthesis, isopropylmalate synthase, missing the carboxyl-terminal 160 amino acids. In contrast, the S. pennellii LA0716 IPMS3 allele found in IL8-1/8-1-1 encodes a nonfunctional truncated IPMS protein. M82 transformed with an SlIPMS3 RNA interference construct exhibited an acylsugar profile similar to that of IL8-1-1, whereas the expression of SlIPMS3 in IL8-1-1 partially restored the M82 acylsugar phenotype. These IPMS3 alleles are polymorphic in 14 S. pennellii accessions spread throughout the geographical range of occurrence for this species and are associated with acylsugars containing varying amounts of 2-methylpropanoic acid and 3-methylbutanoic acid acyl chains.