A time-of-flight detector of low-energy ions for an accelerating mass-spectrometer

The results of experiments with a time-of-flight detector for detecting rare ions at the output of the accelerating mass spectrometer of the Institute of Nuclear Physics (Siberian Branch, Russian Academy of Sciences) are described. The operation of this detector is based on detection of electron emission from thin films by means of microchannel plates. Owing to the small thickness of films, ions can sequentially pass through several films—this is the basis of the time-of-flight system for identifying isotopes. The high time resolution of detectors allows a significant decrease in the external-radiation background compared to one semiconductor complete-absorption detector that measures the ion energy.     

Measurements of the profile of an intense electron beam

Methods for measuring the profiles of high-power electron beams by using a thin tungsten wire moved transversely to the beam have been developed. In one method, the electron current intercepted by the wire is measured and the beam profile is determined from a solution to the Abel equation under the assumption of axial beam symmetry. The second method is based on the detection of the local radiation emitted by the wire being heated by the beam to 1700–2200 K. The wire is additionally heated by an electric current in order to improve the sensitivity and spatial resolution. The measured beam current density is ～5–50 A/cm², and the resolution is ～0.1 cm.     

Search for the most stable folds of protein chains: I. Application of a self-consistent molecular field theory to a problem of protein three-dimensional structure prediction

We present a general approach to the prediction of 3-D foldsof protein chains from their amino acid sequences. The approachis based on the use of the self-consistent molecular field theoryfor long-range interactions, the use of 1-D statistical mechanicsfor short-range interactions and on the discovery that thereis and should only be a relatively small discrete set of foldingpatterns. This makes it possible to examine the full varietyof ‘potentially stable’ folds and to determine thethermodynamically stable structure. In this paper, we give thegeneral theoretical background of the approach. The encouragingresults of the application of this approach to ß-domainsare described in another paper.     

Understanding the Visible Absorption of Electron Accepting and Donating CNDs

Carbon nanodots (CNDs) synthesized from citric acid and formyl derivatives, that is, formamide, urea, or N-methylformamide, stand out through their broad-range visible-light absorbance and extraordinary photostability. Despite their potential, their use has thus far been limited to imaging research. This work has now investigated the link between CNDs’ photochemical properties and their chemical structure. Electron-rich, yellow carbon nanodots (yCNDs) are obtained with in situ addition of NaOH during the synthesis, whereas otherwise electron-poor, red carbon nanodots (rCNDs) are obtained. These properties originate from the reduced and oxidized dimer of citrazinic acid within the matrix of yCNDs and rCNDs, respectively. Remarkably, yCNDs deposited on TiO₂ give a 30% higher photocurrent density of 0.7 mA cm⁻² at +0.3 V versus Ag/AgCl under Xe-lamp irradiation (450 nm long-pass filter, 100 mW cm⁻²) than rCNDs. The difference in overall photoelectric performance is due to fundamentally different charge-transfer mechanisms. These depend on either the electron-accepting or the electron-donating nature of the CNDs, as is evident from photoelectrochemical tests with TiO₂ and NiO and time-resolved spectroscopic measurements.     

Culturally competent interventions for abused and suicidal African American women.

This article focuses on interventions with low-income, African American women who are survivors of domestic abuse and who have made one or more suicide attempts. The authors review the literature on domestic abuse and suicidal behavior in African American women, and discuss the association between abuse and suicide in this population. Next, they propose an integrated theoretical model for understanding suicidal behavior as one possible coping response to the stress of a domestic abuse situation. The model utilizes concepts from the literature on stress and coping as well as stages of change. A culturally sensitive group treatment intervention that is based on the theoretical model is presented. The intervention focuses on ensuring women's safety, increasing coping skills and resource mobilization, and promoting supportive relationships in a manner that is consistent with each woman's sociocultural context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)