Room-Temperature Solid-Matrix Luminescence Spectroscopy of Pyrene and 1-Hydroxypyrene from Optically Clear Sugar Glasses

Room-temperature solid-matrix luminescence was investigated for two model compounds pyrene and 1-hydroxypyrene from optically clear sugar glasses. Several glasses were investigated. Novel glasses were prepared for the first time from binary mixtures of sugars for spectroscopy. Glasses were prepared from glucose/xylose and glucose/maltose. The glucose/maltose gave a superior glass compared to glucose/xylose. The glucose/maltose glass gave the best room temperature phosphorescence (RTP) for pyrene compared to glasses of glucose and maltose without a heavy atom. The RTP was weak for both pyrene and 1-hydroxypyrene without a heavy atom in the glucose glass. The addition of a heavy atom (12% NaI) gave a 44-fold increase in RTP of pyrene and a 10-fold increase in the RTP of 1-hydroxypyrene. Room temperature fluorescence (RTF) of pyrene and 1-hydroxypyrene were easily observed from all the glass systems studied. However, the pyrene RTF intensity varied with the different sugar glass systems studied. Furthermore, a polymer, polyacrylic acid (PAA), was added to the sugar matrix at the level of 1% and 2% to improve the rigidity of the glass matrix. The observed phosphorescence was weak for pyrene at both the 1% and 2% PAA concentrations. A glass prepared with 2% PAA gave the strongest RTP for pyrene. Addition of 12% NaI with 1% polyacrylic acid did improve the RTP of pyrene but it was less than the RTP of pyrene from a glucose glass with 12% NaI by a factor of 2.7. A glucose glass with 12% NaI was the best system for RTP of pyrene.     

The effects of creatine ethyl ester supplementation combined with heavy resistance training on body composition, muscle performance, and serum and muscle creatine levels

Numerous creatine formulations have been developed primarily to maximize creatine absorption. Creatine ethyl ester is alleged to increase creatine bio-availability. This study examined how a seven-week supplementation regimen combined with resistance training affected body composition, muscle mass, muscle strength and power, serum and muscle creatine levels, and serum creatinine levels in 30 non-resistance-trained males. In a double-blind manner, participants were randomly assigned to a maltodextrose placebo (PLA), creatine monohydrate (CRT), or creatine ethyl ester (CEE) group. The supplements were orally ingested at a dose of 0.30 g/kg fat-free body mass (approximately 20 g/day) for five days followed by ingestion at 0.075 g/kg fat free mass (approximately 5 g/day) for 42 days. Results showed significantly higher serum creatine concentrations in PLA (p = 0.007) and CRT (p = 0.005) compared to CEE. Serum creatinine was greater in CEE compared to the PLA (p = 0.001) and CRT (p = 0.001) and increased at days 6, 27, and 48. Total muscle creatine content was significantly higher in CRT (p = 0.026) and CEE (p = 0.041) compared to PLA, with no differences between CRT and CEE. Significant changes over time were observed for body composition, body water, muscle strength and power variables, but no significant differences were observed between groups. In conclusion, when compared to creatine monohydrate, creatine ethyl ester was not as effective at increasing serum and muscle creatine levels or in improving body composition, muscle mass, strength, and power. Therefore, the improvements in these variables can most likely be attributed to the training protocol itself, rather than the supplementation regimen.     

Role of Bose enhancement in photoassociation

Abstract

We discuss the role of Bose enhancement of the dipole matrix element in photoassociation, using stimulated Raman adiabatic passage as an example. In a non-degenerate gas the time scale for coherent optical transients tends to infinity in the thermodynamic limit, whereas Bose enhancement keeps this time scale finite in a condensate. Coherent transients are therefore absent in photoassociation of a thermal non-degenerate gas, but are feasible if the gas is a condensate.     

Review of Life-Cycle Assessment Applications in Building Construction

Life-cycle assessment (LCA) has been used to assess product development processes “from cradle to grave” for many years. With the current push toward sustainable construction, LCA has gained importance as an objective method to evaluate the environmental impact of construction practices. A substantial amount of construction-related LCA work has been published recently; however, most of this work has been fragmented and a systematic compilation of this literature has not been undertaken. This article presents a structured review of building construction-related LCA literature, classified under four categories: LCA applications for construction products selection; LCA applications for construction systems/process evaluation; LCA tools and databases related to the construction industry; and LCA methodological developments related to the construction industry. Current challenges for using LCA in construction are discussed and potential areas for future research are highlighted. This review and similar efforts may provide the construction industry and associated researchers the necessary background to make better-informed construction decisions and assist the development of an agenda for further research.     

Identifying Shared Environmental Contributions to Early Substance Use: The Respective Roles of Peers and Parents.

Although behavior genetic studies have suggested that early substance use is primarily environmentally mediated, no study has sought to identify the specific sources of environmental variance. Using data obtained from multiple informants, this study assessed the contributions of peer deviance and parent-child relationship problems to substance use in 14-year-old male and female twins (N = 1,403) drawn from the Minnesota Twin Family Study (MTFS). All three phenotypes were influenced primarily by shared environmental variance (average c2 = .51), as was the overlap among them. Moreover, peer deviance and parent-child relationship problems accounted for approximately 77% of the variance in early substance use. Findings also indicated that peer deviance, but not parent-child relationship problems, accounted uniquely for variance in early substance use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of practice tests in the accuracy of test predictions on text material.

Investigated the role of practice tests in predictions about test performance on texts. Generally, Ss predicted their relative performance on tests accurately. However, answering practice-test questions that were drawn from the same pool as criterion-test questions did not improve prediction accuracy. The main reason for this was that practice-test scores for specific texts did not correlate with criterion-test scores. In addition, neither practice tests that were identical to the criterion tests nor practice tests consisting of the question stems improved the accuracy of test predictions relative to no-practice tests. With identical practice and criterion tests, accuracy of self-generated feedback correlated positively with the accuracy of test predictions. For similar practice and criterion tests, however, accurate experimenter-provided feedback reduced test-prediction accuracy, presumably because of the lack of reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

便携式电子产品的散热管理

减小封装尺寸和提高性能的双重要求向便携式系统设计工程师提出了解决散热管理问题的严峻挑战.提高性能通常通过提高时钟频率和提高集成度来实现,但是这两种做法都会引起功耗增加.另外封装尺寸减小势必增加了器件的散热困难.因此,便携式设备的散热问题因受重量、通风配置、防风雨和其它因素的限制而进一步加重.     

Profiling under UNIX by patching

Profiling under UNIX is done by inserting counters into programs either before compiling, during compiling or during assembly. A fourth type of profiling involves monitoring the execution of a program, and gathering relevant statistics during the run. This paper looks at this method and an implementation of it, and discusses its advantages and disadvantages.     

透视Virtex-4超高效且低功耗的奥秘

随着工艺技术越来越小型化、越来越快速,通常会增加功耗,这时在功耗和效能上往往必须有所取舍,因而器件功耗一直是半导体业的首要课题。来自Xilinx的新型Virtex-4FPGA采用创新的架构特性和先进的IC设计技术,可以在显著降低功耗的同时,依然不损害其性能,且和90nm工艺技术特征尺寸减小的趋势不谋而合。本文将探讨XilinxIC设计者如何在高性能Virtex-4FPGA中实现很高的功率效率。