Building‐Block Diversity in Polydopamine Underpins a Multifunctional Eumelanin‐Type Platform Tunable Through a Quinone Control Point

Rational approaches to engineering polydopamine films with tailored properties for surface coating and functionalization are currently challenged by the lack of detailed information about the polymer structure and the mechanism of buildup. Using an integrated chemical and spectroscopic approach enables the demonstration of: a) a three‐component structure of polydopamine, comprising uncyclized (catecholamine) and cyclized (indole) units, as well as novel pyrrolecarboxylic acid moieties; b) remarkable variations in the relative proportions of the cyclized and uncyclized units with starting dopamine concentration; c) the occurrence of oligomer components up to the tetramer level; d) the covalent incorporation of Tris buffer; and e) the role of dopamine quinone as a crucial control point for directing the buildup pathways and tuning the properties. The importance of the uncyclized amine‐containing units in polydopamine adhesion is also highlighted. The proper selection of substrate concentration and buffer is thus proposed as a practical means of tailoring polydopamine functionality via control of competing pathways downstream of dopamine quinone.     

Controlled Synthesis of CdSe Nanowires by Solution–Liquid–Solid Method

Semiconductor nanowires prepared by wet chemical methods are a relatively new field of 1D electronic systems, where the dimensions can be controlled by changing the reaction parameters using solution chemistry. Here, the solution–liquid–solid approach where the nanowire growth is governed by low‐melting‐point catalyst particles, such as Bi nanocrystals, is presented. In particular, the focus is on the preparation and characterization of CdSe nanowires, a material which serves a prototype structure for many kinds of low dimensional semiconductor systems. To investigate the influence of different reaction parameters on the structural and optical properties of the nanowires, a comprehensive synthetic study is presented, and the results are compared with those reported in literature. How the interplay between different reaction parameters affects the diameter, length, crystal structure, and the optical properties of the resultant nanowires are demonstrated. The structural properties are mainly determined by competing reaction pathways, such as the growth of Bi nanocatalysts, the formation and catalytic growth of nanowires, and the formation and uncatalytic growth of quantum dots. Systematic variation of the reaction parameters (e.g., molecular precursors, concentration and concentration ratios, organic ligands, or reaction time, and temperature) enables control of the nanowire diameter from 6 to 33 nm, while their length can be adjusted between several tens of nanometers and tens of micrometers. The obtained CdSe nanowires exhibit an admixture of wurtzite (W) and zinc blende (ZB) structure, which is investigated by X‐ray diffraction. The diameter‐dependent band gaps of these nanowires can be varied between 650 and 700 nm while their fluorescence intensities are mainly governed by the Cd/Se precursor ratio and the ligands used.     

InGaAs/GaAs structures with quantum dots in vertical optical cavities for wavelengths near 1.3 µm

Semiconductor heterostructures with vertical optical cavities with active regions, based on arrays of InAs quantum dots inserted in an external InGaAs quantum well, have been obtained by molecular-beam epitaxy on GaAs substrates. The dependences of the reflection and photoluminescence spectra on the structural characteristics of the active region and optical cavities have been investigated. The proposed heterostructures are potentially suitable for optoelectronic devices at wavelengths near 1.3 μm. Fiz. Tekh. Poluprovodn. 33, 629–633 (May 1999)     

Exciton waveguide and lasing in structures with superfine GaAs quantum wells and InAs submonolayer inclusions in an AlGaAs host

The optical properties of structures with InAs islands and narrow GaAs quantum wells in an AlGaAs host have been investigated. The InAs islands were formed by depositing a layer of InAs with an effective thickness less than one monolayer. The effect of an exciton waveguide and the onset of lasing due to optical pumping in the red spectral range are demonstrated in structures without external optical confinement by layers with a lower refractive index. Fiz. Tekh. Poluprovodn. 33, 488–491 (April 1999)     

Investigation of MOVPE-grown GaN layers doped with As atoms

Conditions are investigated for the injection of arsenic into gallium nitride layers grown by metal-organic vapor-phase epitaxy. It is shown that the deposition of GaAs on a GaN surface relieves stresses in the GaN layer. The high-temperature overgrowth of a thin GaAs layer by a GaN layer causes As atoms to diffuse into the GaN, produces a thick, homogeneously doped GaN:As region, and creates a bright band in the photoluminescence spectrum with a maximum at ∼2.5 eV. Fiz. Tekh. Poluprovodn. 33, 791–794 (July 1999)     

用无线技术降低医疗费用

蓝牙低耗能规范保证会达到卫生机构关于在家中对病患者进行无线监控的严格要求,但是做到这点要战胜一些挑战,本文就是详细介绍如何利用无线技术提升医疗服务的范围和效率.     

Let's give the devil his due: A response to Birnbaum.

Argues that although M. H. Birnbaum's (see record 1973-20037-001) criticism regarding the potential inadequacies of the correlation coefficient in model assessment is correct, the examples he provides actually reveal inadequacies in the models rather than in the correlation coefficient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comment on component-randomization tests.

Examination of the discrete randomization t and F tests reveals that in general they should not be regarded as the appropriate exact tests, which are only approximated by their parametric counterparts. In very small samples, the randomization tests will fail to reveal differences easily detected by the appropriate parametric test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accident management strategy in Sweden — implementation and verification

A comprehensive program for severe accident mitigation was completed in Sweden by the end of 1988. As described in this paper, this program included plant modifications such as the introduction of filtered containment venting, and an accident management system comprising emergency operating strategies and procedures, training and emergency drills. The accident management system at Vattenfall has been further developed since 1988 and some results and experience from this development are reported in this paper. The main aspects covered concern the emergency organization and the supporting tools developed for use by the emergency response teams, the radiological implications such as accessibility to various locations and the long-term aspects of accident management.