Controllable 1D Patterned Assembly of Colloidal Quantum Dots on PbSO4 Nanoribbons

Control of the 1D self‐assembly pattern of colloidal quantum dots (QDs) on PbSO₄ nanoribbon (NRb) templates is achieved. The internal structure of the NRbs is investigated by X‐ray diffraction, revealing the isotropic packing of the PbSO₄ nanoclusters in the NRbs. Colloidal QDs in a chloroform/hexane mixture are adsorbed onto the region close to the edges of the NRbs and form a 1D assembly of straight single line or double lines by controlling the amount of OAm. This is the first demonstration of a densely packed 1D self‐assembly of colloidal QDs with a straight line pattern without the use of any molecular bridge or adhesive. Atomic force microscopy measurements of the NRbs show depressions in the phase profile along the width of the NRbs, corresponding to the position of the 1D QD chain. The amount of adsorbed QDs on the NRbs in solution decreases as the addition of OAm increases, suggesting that additional OAm prevents interaction between the QDs and NRbs but facilitates the uniform adsorption of the 1D assembly. The low‐dimensional self‐assembly of colloidal QDs in this study opens up the possibility for the creation of anisotropically assembled QD superstructures.     

Oxidation behavior of ytterbium silicide

Si-rich ytterbium silicide was fabricated by through an arc-melting technique for applying use as a bond coat material in an environmental barrier coating system. Evaluation of its potential was accomplished through oxidation tests in dry air and an inert atmosphere. The experimental results showed that the changes in weight and morphologies of ytterbium silicide observed after the tests depended on the oxygen partial pressure. Extensive oxidation and weight gain occurred after oxidation in air. In order to apply this material for hot structures, improvement of the oxidation resistance is needed.     

Automated formal analysis of temporal properties of Ladder programs

International Journal on Software Tools for Technology Transfer - Programmable Logic Controllers are industrial digital computers used as automation controllers in manufacturing processes. The...     

Logic programming in tensor spaces

Annals of Mathematics and Artificial Intelligence - This paper introduces a novel approach to computing logic programming semantics. First, a propositional Herbrand base is represented in a vector...     

Blood lead levels of the general populations of three Chinese cities

Blood samples were obtained from 537 adults (age greater than or equal to 16 years) living in three cities in China; in Hefei in 1985, and in Shenyang and Jinxi in 1987. The samples were subjected to blood lead (Pb-B) analyses. The subjects were factory workers either in solvent-synthesizing or solvent application plants with no known exposure to metals (including lead). Their smoking and drinking habits were confirmed in medical interviews. Blood lead was significantly higher in smokers than in non-smokers, although no dose-dependency was observed. The Pb-B values in non-smokers were log-normally distributed. The Pb-B among non-smokers was significantly higher in men [104.0 micrograms l-1 (1.428) 87] [geometric mean (geometric standard deviation) number of determinations] than in women [75.5 micrograms l-1 (1.358) 225] when the data from the three cities were combined. There was a significant difference in the Pb-B levels of non-smoking men in the three cities studied, suggesting that regional food habits should be considered as a possible contributory factor of a non-occupational nature. The present findings are compared with observations from Korea and Japan from the viewpoint of environmental health.     

Monitoring behaviour of catabolic genes and change of microbial community structures in seawater microcosms during aromatic compound degradation

The behaviour of microbial populations responsible for degradation of the aromatic compounds, phenol, benzoate, and salicylate, and changes of microbial community structures in seawater microcosms were analysed quantitatively and qualitatively using MPN–PCR and PCR–DGGE. The purpose of the study was to investigate the ecology of the entire microbial community during bioremediation. Bacterial populations possessing catechol 1,2-dioxygenase (C12O) DNA were evidently the primary degraders of phenol and benzoate, but others possessing catechol 2,3-dioxygenase (C23O) DNA increased to enhance substrate degradation under high-load conditions when the substrates were present for long periods. However, salicylate degradation was evidently facilitated by specific bacterial populations possessing C23O DNA. PCR–DGGE analyses suggested that bacterial populations already relatively dominant in the original microcosm contributed to phenol degradation. Bacteria composing a minor fraction of the original population apparently increased and contributed to benzoate degradation. Bacterial populations possessing C23O DNA were responsible for salicylate degradation, however, and different degrading bacteria were evidently selected for, depending on the initial salicylate concentration. Microbial community structure tended to be simplified by aromatic compound degradation. Thus, microbial monitoring can elucidate the behaviour of bacterial populations responsible for aromatic compound degradation and be used to assess the effects of bioremediation on intact microbial ecosystems.     

Adiabatic photo-steering theory in topological insulators

Feasible external control of material properties is a crucial issue in condensed matter physics. A new approach to achieving this aim, named adiabatic photo-steering, is reviewed. The core principle of this scheme is that several material constants are effectively turned into externally tunable variables by irradiation of monochromatic laser light. Two-dimensional topological insulators are selected as the optimal systems that exhibit a prominent change in their properties following the application of this method. Two specific examples of photo-steered quantum phenomena, which reflect topological aspects of the electronic systems at hand, are presented. One is the integer quantum Hall effect described by the Haldane model, and the other is the quantum spin Hall effect described by the Kane–Mele model. The topological quantities associated with these phenomena are the conventional Chern number and spin Chern number, respectively. A recent interesting idea, time-reversal symmetry breaking via a temporary periodic external stimulation, is also discussed.     

Sustained photobiological hydrogen production in the presence of N2 by nitrogenase mutants of the heterocyst-forming cyanobacterium Anabaena

Heterocyst-forming cells of the cyanobacterium Anabaena sp. strain PCC 7120 ΔHup, lacking an uptake hydrogenase, photobiologically produce H₂ by nitrogenase. Under N₂-rich atmosphere, the nitrogenase activity declines in a rather short time due to the sufficiency of combined nitrogen. From the parental ΔHup strain, site-directed double-crossover variants, dc-Q193S and dc-R284H, were created with amino acid substitutions presumed to be located in the vicinity of the FeMo-cofactor of nitrogenase. Unlike the case for the ΔHup strain, H₂ production activities of the variants were not decreased by the presence of high concentrations of N₂ and they continuously produced H₂ over 21 days with occasional headspace gas replacement. This property of N₂ insensitivity is a potentially useful strategy for reducing the cost of the culture gas in future practical applications of sustainable biofuel production. This Anabaena strain has only the Mo-containing nitrogenase which reduces acetylene to ethylene, but the dc-Q193S variant also produced ethane at low but measurable rates along with greater rates of ethylene production.     

Synthesis and optical properties of azobenzene side chain polymers derived from the bifunctional fumaric acid and itaconic acid

Three type polymers containing the same azobenzene side chain group with different backbone structures, poly(DMAz6Fm), poly(DMAz6It) and poly(MAz6Ac) derived respectively from fumaric acid, itaconic acid and acrylic acid, were synthesized. The dependence of photo-response properties on the polymeric architecture was investigated for the solutions and films. By irradiation of the linearly polarized light (436 nm), uniaxial orientations of the thin films were induced and anisotropic properties were investigated by measurements of the order parameters and birefringence values.