Inherent emf relaxation of electrochemical cells with nanocrystalline Ag electrodes

The open circuit voltage of the electrochemical cell Ag (nano)|solid silver electrolyte|Ag (macro) is found to be inherently unstable. Even under conditions which support the morphological stability of the arrangement of nanocrystalline silver, the particles grow significantly as soon as they function as electrodes; i.e. when they are in contact with a silver electrolyte and connected electronically at the same time. The process is shown to be due to electrochemical Ostwald ripening with the interfacial transfer of Ag⁺ through the Ag/electrolyte interface being the rate limiting step. Its activation energy is 0.01 eV. The decay is in good agreement with modelling results.     

A note on the internal consistency of the Manifest Needs Questionnaire.

Reviews certain psychometric properties of the Manifest Needs Questionnaire as reported in 8 published studies. In addition, data from 2 new samples are summarized. It is concluded that estimates of internal consistency associated with the needs for achievement, affiliation, and autonomy are not generally satisfactory for use in organizational research. Only the Need for Dominance scale demonstrates a minimally useful degree of internal consistency across all reported studies. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in visual perception and in visual-motor functioning between psychotic and nonpsychotic children.

The study explored the applicable scope of Bender's theory of a "maturational lag" in functional childhood psychosis. Tests of visual perception, visual-motor performance, and a clinical evaluation of presence of CNS deviations consistent with Bender's criteria for childhood schizophrenia were performed on 39 psychotic and 57 nonpsychotic 8-12-year-old boys. Results revealed no differences in accuracy or variability of perceptual and visual-motor behavior when appropriate controls for large group differences in MA functioning were instituted. No difference in test performance was found between psychotic Ss with and without CNS deviations. With MA level constant, the difference in incidence of CNS deviations between psychotics and nonpsychotics was nonsignificant. The results were interpreted as not supporting Bender's organic theory. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Occurrence, distribution and fluxes of benzotriazoles along the German large river basins into the North Sea

Benzotriazole (BT) and tolyltriazole (TT) are high production volume chemicals which are used in various industrial and household applications. In this study, the distribution of benzotriazoles in the estuaries of different rivers of central Europe and in the North Sea was analyzed by solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (HPLC-MS/MS). BT as well as TT was detected in all water samples. The concentrations for total benzotriazoles (BTs) ranged from 1.7 to 40 ng/L in the North Sea in costal areas. Concentrations in rivers are from 200 to 1250 ng/L, respectively. The mass flux of total benzotriazoles from the major rivers of central Europe into the North Sea was calculated to 78 t/a, dominated by the Rhine with an individual flux of 57 t/a of BTs. The analysis of the distribution profile in the North Sea showed that the decrease of the concentration was mostly caused by dilution and that the benzotriazoles are poorly degradable in the North Sea. This paper presents the first report of benzotriazoles in the marine environment.     

Addressing the numbers problem in directed evolution

Our previous contribution to increasing the efficiency of directed evolution is iterative saturation mutagenesis (ISM) as a systematic means of generating focused libraries for the control of substrate acceptance, enantioselectivity, or thermostability of enzymes. We have now introduced a crucial element to knowledge-guided targeted mutagenesis in general that helps to solve the numbers problem in directed evolution. We show that the choice of the amino acid (aa) alphabet, as specified by the utilized codon degeneracy, provides the experimenter with a powerful tool in designing "smarter" randomized libraries that require considerably less screening effort. A systematic comparison of two different codon degeneracies was made by examining the relative quality of the identically sized enzyme libraries in relation to the degree of oversampling required in the screening process. The specific example in our case study concerns the conventional NNK codon degeneracy (32 codons/20 aa) versus NDT (12 codons/12 aa). The model reaction is the hydrolytic kinetic resolution of a chiral trans-disubstituted epoxide, catalyzed by the epoxide hydrolase from Aspergillus niger. The NDT library proves to be of much higher quality, as measured by the dramatically higher frequency of positive variants and by the magnitude of catalyst improvement (enhanced rate and enantioselectivity). We provide a statistical analysis that constitutes a useful guide for the optimal design and generation of "smarter" focused libraries. This type of approach accelerates the process of laboratory evolution considerably and can be expected to be broadly applicable when engineering functional proteins in general.     

Multi-Agent Dynamic Logics with Informational Test

This paper investigates a family of logics for reasoning about the dynamic activities and informational attitudes of agents, namely the agents' beliefs and knowledge. The logics are based on a new formalisation and semantics of the test operator of propositional dynamic logic and a representation of actions which distinguishes abstract actions from concrete actions. The new test operator, called informational test, can be used to formalise the beliefs and knowledge of particular agents as dynamic modalities. This approach is consistent with the formalisation of the agents' beliefs and knowledge as K(D)45 and S5 modalities. Properties concerning informativeness, truthfulness and preservation of beliefs are proved for a derivative of the informational test operator. It is shown that common belief and common knowledge can be expressed in the considered logics. This means, the logics are more expressive than propositional dynamic logic with an extra modality for belief or knowledge. The logics remain decidable and belong to 2EXPTIME. Versions of the considered logics express natural additional properties of beliefs or knowledge and interaction of beliefs or knowledge with actions. It is shown that a simulation of PDL can be constructed in one of these extensions.