A new algorithm for automatic photopeak searches

A new, "quantum mechanical" algorithm is proposed for automatic photopeak location in gamma-ray spectra from semiconductor and scintillator detectors.Comment: 9 pages, LaTex, without figures. Sample program and figures (by FAX) can be sent on reques

Stability and aromaticity of nH2@B12N12 (n=1–12) clusters

Standard ab initio and density functional calculations are carried out to determine the structure, stability, and reactivity of B12N12 clusters with hydrogen doping. To lend additional support, conceptual DFT-based reactivity descriptors and the associated electronic structure principles are also used. Related cage aromaticity of this B12N12 and nH2@B12N12 are analyzed through the nucleus independent chemical shift values

Intimacy development in late adolescence: Longitudinal associations with perceived parental autonomy support and adolescents' self-worth

The present longitudinal study tested for the role of perceived parental autonomy-support and late adolescents' self-worth in their intimacy development. A sample of 497 Belgian late adolescents (Mage = 17.9, 43.5% girls) participated in this two-wave study. Results indicated that perceived autonomy-supportive parenting did not relate significantly to change in adolescents' experienced intimacy (in terms of closeness and mutuality), but was associated with a decrease in unmitigated agency (an excessive focus on the self) and unmitigated communion (an excessive focus on the other) across time. Adolescents' self-worth predicted an increase in experienced intimacy and a decrease in unmitigated agency and communion, and the initial level of experienced intimacy predicted an increase in self-worth. Finally, results suggested that adolescents' self-worth may mediate some of the longitudinal relations between perceived parental autonomy-support and adolescents' intimate functioning. No evidence was found for moderation by romantic involvement, gender or age

Field Programmable Gate Array Reliability Analysis Using the Dynamic Flowgraph Methodology

Field programmable gate array (FPGA)-based systems are thought to be a practical option to replace certain obsolete instrumentation and control systems in nuclear power plants. An FPGA is a type of integrated circuit, which is programmed after being manufactured. FPGAs have some advantages over other electronic technologies, such as analog circuits, microprocessors, and Programmable Logic Controllers (PLCs), for nuclear instrumentation and control, and safety system applications. However, safety-related issues for FPGA-based systems remain to be verified. Owing to this, modeling FPGA-based systems for safety assessment has now become an important point of research. One potential methodology is the dynamic flowgraph methodology (DFM). It has been used for modeling software/hardware interactions in modern control systems. In this paper, FPGA logic was analyzed using DFM. Four aspects of FPGAs are investigated: the “IEEE 1164 standard,” registers (D flip-flops), configurable logic blocks, and an FPGA-based signal compensator. The ModelSim simulations confirmed that DFM was able to accurately model those four FPGA properties, proving that DFM has the potential to be used in the modeling of FPGA-based systems. Furthermore, advantages of DFM over traditional reliability analysis methods and FPGA simulators are presented, along with a discussion of potential issues with using DFM for FPGA-based system modeling

Rapid Synthesis of Functionalized High-Generation Polyester Dendrimers via Strain-Promoted Alkyne–Azide Cycloaddition

Preparation of structurally perfect high-generation dendrimer libraries with different peripheral groups is challenging as divergent synthesis introduces peripheral defects and convergent synthesis leads to low yields. Here, we prepare a third-generation polyester dendron based on the bisMPA monomer structure, having eight peripheral azide functionalities, as an “inner” dendron. We also prepare a series of low-generation “outer” dendrons (G2 and G3) with various peripheral groups, including aromatic, aliphatic, and polar structures, each having a single dibenzoaza­cyclooctyne (DIBAC) at the core. Efficient strain-promoted azide–alkyne cycloaddition (SPAAC) enables quantitative coupling between the outer and inner dendrons, producing high-generation (G5 and G6) dendrimers in a single coupling step. Characterization by NMR and mass spectrometry shows that the coupling products are structurally perfect. Using this strategy, we prepared a small dendrimer library that includes the first high-generation monodisperse peripherally PEGylated dendrimers as well as a structure bearing bulky protected amino acids at its periphery. This general strategy allows for rapid, efficient, and quantitative preparation of high-generation dendrimers with a variety of peripheral and core functional groups, starting from small, easily prepared fragments

Direct Measure of the Local Concentration of Pyrenyl Groups in Pyrene-Labeled Dendrons Derived from the Rate of Fluorescence Collisional Quenching

The model-free analysis (MFA) was applied to measure the average rate constant (<k>) for pyrene excimer formation (PEF) in a series of pyrene-labeled dendrons referred to as Pyx-G(N), where x (= 2N) is the number of pyrenyl labels born by a dendron of generation N ranging from 1 to 6. <k> was measured in four different solvents, namely tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF), and dimethylsulfoxide (DMSO). <k> was found to increase linearly with increasing local pyrene concentration ([Py]loc), where [Py]loc had been determined mathematically for the Pyx-G(N) dendrons. The slope of each straight line changed with the nature of the solvent and represented kdiff, the bimolecular rate constant for PEF. kdiff depended on the solvent viscosity (η) and the probability (p) for PEF upon encounter between an excited and a ground-state pyrene. In a same solvent, kdiff for the Pyx-G(N) dendrons was about 360 ± 30 times smaller than kdiff obtained for ethyl 4-(1-pyrene)butyrate (PyBE), a pyrene model compound similar to the pyrene derivative used to label the dendrons. The massive decrease in kdiff observed for the Pyx-G(N) samples reflected the massive loss in mobility experienced by the pyrenyl labels after being covalently attached onto a macromolecule compared to freely diffusing PyBE. Interestingly, the kdiff values obtained for the Pyx-G(N) dendrons and the PyBE model compound followed similar trends as a function of solvent, indicating that the difference in behavior between the kdiff values obtained in different solvents were merely due to the changes in the η and p values between the solvents. Normalizing the <k> values obtained with the Pyx-G(N) dendrons by the kdiff values obtained for PyBE in the same solvents accounted for changes in η and p, resulting in a master curve upon plotting <k>/(fdiff × kdiff) as a function of [Py]loc, where fdiff was introduced to account for some pyrene aggregation in the higher generation dendron (Py64-G(6)). This result demonstrates that <k> represents a direct measure of [Py]loc in pyrene-labeled macromolecules