Thermal And Mechanical Response Of PBX 9501 Under Contact Excitation

The thermal and mechanical responses of a cyclotetramethylene-tetranitramine-based explosive (PBX 9501) and two non-energetic mock materials (900-21 and PBS 9501) under high-frequency mechanical excitation are presented. Direct contact ultrasound transducers were used to excite samples through a frequency range of 50 kHz to 40 MHz. The mechanical response of each sample was approximated from a contact receiving transducer and trends were confirmed via laser Doppler vibrometry. The steady-state thermal response of the samples was measured at discrete excitation frequencies via infrared thermography. A maximum temperature rise of approximately 15 K was observed in PBX 9501, and the mock materials exhibited similar thermal characteristics. Temperature gradients were calculated to estimate the total heat generated within the samples due to the mechanical excitation. The active heating mechanisms were found to be highly dependent on the frequency of excitation. Possible mechanisms of heating at frequencies below 1 MHz are likely related to bulk motion. Above this frequency, the active heating mechanisms are likely related to particle-scale processes. The observed phenomena may prove useful in the aid of current trace vapor detection methods for explosives

The ambivalence of losing weight after bariatric surgery

This study is grounded in a phenomenological lifeworld perspective. It aims at providing rich descriptions of lived experience of the process of losing weight after obesity surgery. Two women participated in in-depth interviews four times each during the first postoperative year. Based on the women's experiences, a meaning structure—the ambivalence of losing weight after obesity surgery—was identified across the women's processes of change. This consisted of five core themes: movement and activity—freedom but new demands and old restraints; eating habits and digestion—the complexity of change; appearance—smaller, but looser; social relations—stability and change; and being oneself—vulnerability and self-assurance. These core themes changed over time in terms of dominance. The experience of ambivalence is discussed according to a phenomenological perspective of the body as lived experience

Dilemmas in the process of weight reduction: Exploring how women experience training as a means of losing weight

Patients diagnosed with obesity are usually offered group-based behavior interventions which include dietary advice and exercise programs. In particular, high-intensity training—combining weight lifting with aerobic exercising—has been proven effective for losing weight. Moreover, recent studies have shown that persons participating in high-intensity training are more likely to maintain their weight loss compared to persons with lower levels of physical activity. However, most of the research in the field has made use of quantitative methods focusing on the measurable effect of such interventions. Therefore, the aim of this study was to show how the training is experienced from a first-person perspective, namely the patients themselves. Our hope was to shed some new light on the process of weight loss that concerns more than the measurable “impacts” of the training. A qualitative approach was used based on interviews with five women selected from a primary healthcare clinic in Norway. Our results show that experiences of training are connected to the participants' general experience of being overweight. Both relationships to other people and earlier experiences are important for how the training is carried out and perceived. Five themes were identified supporting this line of argument: (1) the gaze of others; (2) a common ground; (3) dependence of close-follow up; (4) bodily discomfort as painful; and (5) aiming for results—an ambivalent experience. The results highlight the importance of finding the proper context and support for each patient's needs

Rasch analysis of the Psychiatric Out-Patient Experiences Questionnaire (POPEQ)

<p>Abstract</p> <p>Background</p> <p>The Psychiatric Out-Patient Experiences Questionnaire (POPEQ) is an 11-item core measure of psychiatric out-patients experiences of the perceived outcome of the treatment, the quality of interaction with the clinician, and the quality of information provision. The POPEQ was found to have evidence for reliability and validity following the application of classical test theory but has not previously been assessed by Rasch analysis.</p> <p>Methods</p> <p>Two national postal surveys of psychiatric outpatients took place in Norway in 2004 and 2007. The performance of the POPEQ, including item functioning and differential item functioning, was assessed by Rasch analysis. Principal component analysis of item residuals was used to assess the presence of subdimensions.</p> <p>Results</p> <p>6,677 (43.3%) and 11,085 (35.2%) psychiatric out patients responded to the questionnaire in 2004 and 2007, respectively. All items in the scale were retained after the Rasch analysis. The resulting scale had reasonably good fit to the Rasch model. The items performed the same for the two survey years and there was no differential item functioning relating to patient characteristics. Principal component analysis of the residuals confirmed that the measure to a high degree is unidimensional. However, the data also reflects three potential subscales, each relating to one of the three included aspects of health care.</p> <p>Conclusions</p> <p>The POPEQ had excellent psychometric properties and Rasch analysis further supported the construct validity of the scale by also identifying the three subdimensions originally included as components in the instrument development. The 11-item instrument is recommended in future research on psychiatric out-patient experiences. Future development may lead to the construction of more precise measures of the three subdomains that the POPEQ is based on.</p

Atomic Layer Deposition of 2D Metal Dichalcogenides for Electronics, Catalysis, Energy Storage, and Beyond

2D transition metal dichalcogenides (TMDCs) are among the most exciting materials of today. Their layered crystal structures result in unique and useful electronic, optical, catalytic, and quantum properties. To realize the technological potential of TMDCs, methods depositing uniform films of controlled thickness at low temperatures in a highly controllable, scalable, and repeatable manner are needed. Atomic layer deposition (ALD) is a chemical gas-phase thin film deposition method capable of meeting these challenges. In this review, the applications evaluated for ALD TMDCs are systematically examined, including electronics and optoelectonics, electrocatalysis and photocatalysis, energy storage, lubrication, plasmonics, solar cells, and photonics. This review focuses on understanding the interplay between ALD precursors and deposition conditions, the resulting film characteristics such as thickness, crystallinity, and morphology, and ultimately device performance. Through rational choice of precursors and conditions, ALD is observed to exhibit potential to meet the varying requirements of widely different applications. Beyond the current state of ALD TMDCs, the future prospects, opportunities, and challenges in different applications are discussed. The authors hope that the review aids in bringing together experts in the fields of ALD, TMDCs, and various applications to eventually realize industrial applications of ALD TMDCs.Peer reviewe

Translating weight loss into agency: Men’s experiences 5 years after bariatric surgery

Fewer men than women with severe obesity undergo bariatric surgery for weight loss, and knowledge about men's situation after surgery, beyond medical status, is lacking. Our aim was to explore men's experiences with life after bariatric surgery from a long-term perspective. We conducted in-depth interviews with 13 men, aged 28–60 years, between 5 and 7 years after surgery. The analysis was inspired by Giorgi's phenomenological method. We found that agency was pivotal for how the men understood themselves and their lives after surgery. Weight loss meant regaining opportunities for living and acting in unrestricted and independent daily lives, yet surgery remained a radical treatment with complex consequences. Turning to surgery had involved conceptualizing their own body size as illness, which the men had resisted doing for years. After surgery, the rapid and major weight loss and the feelings of being exhausted, weak, and helpless were intertwined. The profound intensity of the weight loss process took the men by surprise. Embodying weight loss and change involved an inevitable renegotiating of experiences connected to the large body. Having bariatric surgery was a long-term process that seemed unfinished 5 years after surgery. Restrictions and insecurity connected to health and illness persist, despite successful weight loss and embodied change. Bariatric surgery initiated a complex and long-lasting life-changing process, involving both increased capacity for agency and illness-like experiences

Micro-RVE modeling of mechanistic response in porous intermetallics subject to weak and moderate impact loading

In this article we propose macroscopic (continuum) simulation schemes to predict response of porous heterogeneous material systems subjected to weak and moderate impact velocities. The proposed simulation model includes (1) an equation of state for porous solids that describes the evolution of porosity in the material as a function of shock pressure and, (2) a macroscopic rate dependent plasticity model for the porous composite that accounts for the deviatoric strength of the material at weak to moderate shock strengths. In addition, the numerical scheme employs cold-mixture theory to predict shock response of porous intermetallics. The material model is validated using gas-gun impact experiments on Ni/Al Intermolecular Reactive Composite (IRC) at 70% TMD. The proposed model is also used to understand the effect of microstructure on the material response predictions. (C) 2013 Elsevier Ltd. All rights reserved