Combustion characteristics of boron nanoparticles

An experimental investigation of the combustion characteristics of boron nanoparticles in the post flame region of a flat flame burner has been conducted. Boron is attractive as a fuel or a fuel supplement in propellants and explosives due to its high heats of combustion on both a gravimetric and volumetric basis. A relatively large database exists for combustion characteristics of large (greater than 1 μm) boron particles, but very little exists for nano-sized boron. Ignition and combustion characteristics have been studied in the post flame region of a fuel lean CH₄/Air/O₂ flame, with burner temperatures ranging from about 1600 K to 1900 K, and oxygen mole fractions ranging between 0.1 and 0.3. As in earlier investigations on boron combustion, a two-stage combustion phenomenon was observed. Ensemble-averaged burning times of boron nanoparticles were obtained, while the ignition time measurements for boron nanoparticles were extended into a lower temperature range previously unavailable in the literature. The measured burning times were between 1.5 ms and 3.0 ms depending on both the temperature and oxygen mole fraction. The ignition times were relatively insensitive to oxygen concentration in the range studied, and were affected only by temperature. The measured ignition times were inversely related to the temperature, ranging from 1.5 ms at 1810 K to 6.0 ms at 1580 K. The burning time results were compared to both diffusion and kinetic limited theories of particle combustion. It was found that the size dependence on particle burning times did not follow either theory.     

Reasons for abstaining or limiting drinking: A developmental perspective.

The cross-sectional and longitudinal relations between reasons for abstaining or limiting drinking (RALD) and abstention were examined in a 16-year longitudinal study (N = 489) of college students with and without a family history of alcohol problems. Results indicated that RALD based upon upbringing or religiosity were associated with increased rates of abstention, whereas RALD based upon perceived or experienced negative consequences of drinking were associated with lower rates of abstention and increased alcohol consumption among drinkers. In addition, changes in RALD over time coincided with alcohol consumption transitions. Abstainers who began drinking after turning 21 reported a decrease in the importance of RALD associated with loss of control and upbringing or religiosity compared to abstainers who continued to abstain after turning 21. Conversely, drinkers who began abstaining after leaving college reported an increase in the importance of RALD associated with loss of control and upbringing or religiosity compared to drinkers who continued to drink after leaving college. Examining the reciprocal influences of RALD on drinking outcomes extends previous research and may inform prevention and intervention programs among college drinkers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Force Transmission Error Analysis for a High-Pressure Single-Sinker Magnetic Suspension Densimeter

The magnetic suspension densimeter (MSD) is a sophisticated, state-of-the-art device that provides extremely accurate results for density measurements. The MSD uses a magnetic technique to couple a mass inside a measurement cell with an external mass balance for mass measurement. This article presents a force transmission error (FTE) analysis for a high-pressure, single-sinker MSD. Due to the magnetic working principle of the apparatus, magnetic properties of the high-pressure cell and external magnetic fields affect the measurements slightly. For the analysis, McLinden et al. suggest making measurements using two different sinkers, a titanium sinker and a copper sinker, having the same mass. The measurements cover densities for methane, ethane, carbon dioxide and nitrogen over the temperature range from 265 K to 450 K (±5 mK stability) up to 180 MPa (uncertainty of 0.01 % full scale: 200 MPa). Comparing and manipulating the measurements permit determination of apparatus and fluid specific effects that contribute to the FTE. For this MSD, the apparatus effect is about 200 ppm, which effectively masks any fluid specific effect. A comprehensive analysis of the FTE produces a uniform deviation for density values of about 0.05 % at 2σ across the full range of pressure.     

Relaxation and sleep compression for late-life insomnia: A placebo-controlled trial.

Older adults with insomnia were recruited from the community and randomized to treatments: relaxation, sleep compression, and placebo desensitization. Questionnaire data collected at baseline, posttreatment, and 1-year follow-up and polysomnography data collected at baseline and follow-up yielded the following conclusions: All treatments improved self-reported sleep, but objective sleep was unchanged. Clinical significance analyses yielded the strongest findings supporting the active treatments and suggested that sleep compression was most effective. Results partially supported the conclusion that individuals with high daytime impairment (i.e., fatigue) respond best to treatments that extend sleep, as in relaxation, and individuals with low daytime impairment respond best to treatments that consolidate sleep, as in sleep compression. Strong methodological features including a placebo condition and a treatment implementation scheme elevate the confidence due these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do others judge us as harshly as we think? Overestimating the impact of our failures, shortcomings, and mishaps.

When people suffer an embarrassing blunder, social mishap, or public failure, they often feel that their image has been severely tarnished in the eyes of others. Four studies demonstrate that these fears are commonly exaggerated. Actors who imagined committing one of several social blunders (Study 1), who experienced a public intellectual failure (Studies 2 and 3), or who were described in an embarrassing way (Study 4) anticipated being judged more harshly by others than they actually were. These exaggerated fears were produced, in part, by the actors' tendency to be inordinately focused on their misfortunes and their resulting failure to consider the wider range of situational factors that tend to moderate onlookers' impressions. Discussion focuses on additional mechanisms that may contribute to overly pessimistic expectations as well as the role of such expectations in producing unnecessary social anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical relevance of heavy drinking during the college years: Cross-sectional and prospective perspectives.

This study investigated the clinical relevance of heavy drinking during the college years and beyond on concurrent and prospective alcohol-related problems in a high-risk sample (N?=?377). Measures of heavy drinking and alcohol-related problems were significantly correlated cross-sectionally over the study frame, regardless of how these constructs were operationalized. However, the magnitude of the association between heavy drinking and alcohol-related problems declined substantially over time, with the most pronounced decrease following the college years. Despite this cross-sectional decrease in the association between heavy drinking and alcohol-related problems over time, heavy drinking during the college years significantly and substantially predicted alcohol-use disorders up to 10 years later. Implications for assessment of heavy drinking as well as prevention of problematic alcohol use in college students are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Out-of-Plane Strengthening of Masonry Walls with Reinforced Composites

This paper presents an investigation into the effectiveness of using fiber-reinforced composite overlays to strengthen existing unreinforced masonry walls to resist out-of-plane static loads. A total of fifteen wall panels [1,200 × 1,800 × 200 mm (4 ft × 6 ft × 8 in.)] were tested. Twelve panels were assembled with fiber-reinforcing systems attached to the tension side, and the remaining three control walls were left without any external reinforcement. Two configurations of external reinforcement were evaluated. The first reinforcement configuration consisted of two layers of fiber-reinforced plastic webbing and the second consisted of vertical and horizontal bands of undirectional fiber composites. The three wall specimens without external reinforcement were tested to evaluate the change in the system strength and behavior with application of the external reinforcing systems. In addition to the two fiber configurations, the testing program also evaluated two methods of surface preparation of the walls, sand blasting, and wire brush. All specimens were thoroughly washed by water jet, 48 hours prior to application of the fiber-reinforcing systems. Three specimens were tested for each variable. A uniformly distributed lateral load was applied to each panel using the procedures described in the ASTM Standard E-72 Test Method (airbag). Failure loads, strains in the external reinforcement (FRP), out-of-plane deformations, and failure modes were recorded. Recommendations on the usefulness of the proposed technique as a means of strengthening masonry walls for out-of-plane loads are presented. In general, flexural strength of masonry walls can be increased if the shear failure is controlled.     

Religion in the home in the 1980s and 1990s: A meta-analytic review and conceptual analysis of links between religion, marriage, and parenting.

The authors reviewed 94 studies published in journals since 1980 on religion and marital or parental functioning. Meta-analytic techniques were used to quantify religion-family associations examined in at least 3 studies. Greater religiousness appeared to decrease the risk of divorce and facilitate marital functioning, but the effects were small. Greater Christian conservatism was modestly associated with greater endorsement and use of corporal punishment with preadolescents. Isolated findings suggested that greater parental religiousness relates to more positive parenting and better child adjustment. The scope, meaningfulness, and potential strength of findings were restricted because of reliance on global or single-item measures of religious and family domains. To facilitate more conceptually and methodologically sophisticated research, the authors delineated mechanisms by which the substantive and psychosocial elements of religion could benefit or harm family adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic effects of self-efficacy on smoking lapse and relapse.

Self-efficacy (SE) is thought to be critical to success in smoking cessation both as an individual difference and as a dynamic process after a quit attempt. In this study, 214 smokers used palm-top computers to record day-to-day variations in SE during 4 weeks after quitting. SE remained at high and stable levels prior to a 1st lapse but decreased and became more variable thereafter. The authors used event history models with time-varying covariates to assess the effect of daily SE on lapse and relapse risk. Daily SE measures predicted an initial lapse on the subsequent day. However, this relationship was accounted for by stable baseline differences in SE (assessed by questionnaire), rather than by day-to-day dynamics in SE. Progression from 1st lapse to relapse was also examined. In this instance, daily SE predicted subsequent relapse risk, even when baseline SE and concurrent smoking were accounted for, suggesting the importance of SE dynamics for this stage of the relapse process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tobacco withdrawal in women and menstrual cycle phase.

Because negative mood is a characteristic of both tobacco withdrawal and menstrual discomfort, withdrawal may vary by menstrual cycle phase. Tobacco withdrawal, mood, and menstrual discomfort were assessed in premenopausal women who quit smoking during either the follicular (Days 1–14 postmenstrual onset; n?=?41) or luteal (Day 15 or longer postmenstrual onset; n?=?37) phase of the menstrual cycle and maintained biochemically verified smoking abstinence during the postquit week. Women quitting during the luteal phase reported significantly greater increases in tobacco withdrawal and self-reported depressive symptoms than women quitting during the follicular phase. These results indicate that selecting a quit-smoking day early in the follicular phase may attenuate withdrawal and negative affect in premenopausal female smokers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)