Transport and structural studies of the thermoelectric material, bismuth telluride

Thermoelectric materials have long been investigated for the possible use as a power source. This application was recently put to use in the Voyager space program to power the deep space probes on their journey. However, the research done in this area has yet to completely study the properties of these special materials. As a result, this research aims to investigate the high pressure structure and transport properties of these materials in a effort to better understand why they behave as they do. To this end, various techniques have been performed revealing the high pressure properties of these materials

Measurement system for high pressure characterizations of materials

Thermoelectric materials have long been investigated for possible use as power sources. This application was recently put to use in the Voyager space program, powering the deep space probes. Despite the usefulness of these materials, the use of pressure to investigate the material properties has only recently become interesting. As such, the work in this document was to developing a system for concurrently measuring the necessary properties. This system is capable of measuring the electrical resistivity, thermal conductivity, and Seebeck coefficient in the pressure range from 0 - 10 GPa. The results for zinc, almandine garnet, and nickel are presented and demonstrate the capabilities of the system. In addition, results are presented for selected established (Bi2Te3, Sb2Te3, BiSbTe3) and potential (GaTe, InTe, and InGaTe2) thermoelectric materials. The measurements have been made with pressure up to 10 GPa (transport properties, except heat capacity) or 20 GPa (structure). From these measured properties, it is possible to evaluate how pressure effects the interactions

High pressure – Variable temperature studies on pressure transmitting media

The pressure transmitting medium is an important element in high pressure physics. A variety of pressure transmitting media exist including Silicone fluid, Daphne Oil, 4:1 Methanol:Ethanol mixture, etc. In this experiment, the hydrostatic limits of pressure transmitting media have been observed at low temperatures and high pressures. In this case, 4:1 Methanol: Ethanol has been used. The hydrostaticity of 4:1 Methanol:Ethanol has been well studied at room temperatures using the fluorescence of ruby by fitting the R1 and R2 lines to Pseudo-Voigt functions. The hydrostacity of the pressure medium was determined by analyzing the full width at half max (FWHM) of theR2 line

Physical Activity Across the Curriculum (PAAC): a randomized controlled trial to promote physical activity and diminish overweight and obesity in elementary school children

Objective Physical Activity Across the Curriculum (PAAC) was a three-year cluster randomized controlled trial to promote physical activity and diminish increases in overweight and obesity in elementary school children. Methods Twenty-four elementary schools were cluster randomized to the PAAC intervention or served as control. All children in grades two and three were followed to grades four and five. PAAC promoted 90 minutes/wk of moderate to vigorous intensity physically active academic lessons delivered by classroom teachers. BMI was the primary outcome, daily PA and academic achievement were secondary outcomes. Results The three-year change in BMI for PAAC was 2.0 ± 1.9 and control 1.9 ± 1.9, respectively (NS). However, change in BMI from baseline to three years was significantly influenced by exposure to PAAC. Schools with ≥75 minutes of PAAC/wk showed significantly less increase in BMI at three years compared to schools that had <75 minutes of PAAC (1.8 ± 1.8 vs. 2.4 ± 2.0, p=0.02). PAAC schools had significantly greater changes in daily PA and academic achievement scores. Conclusions The PAAC approach may promote daily PA and academic achievement in elementary school children. Additionally, 75 minutes of PAAC activities may attenuate increases in BMI

Multicenter, Prospective, Longitudinal Study of the Recurrence, Surgical Site Infection, and Quality of Life After Contaminated Ventral Hernia Repair Using Biosynthetic Absorbable Mesh: The COBRA Study

OBJECTIVE: The aim of the study was to evaluate biosynthetic absorbable mesh in single-staged contaminated (Centers for Disease Control class II and III) ventral hernia (CVH) repair over 24 months. BACKGROUND: CVH has an increased risk of postoperative infection. CVH repair with synthetic or biologic meshes has reported chronic biomaterial infections and high hernia recurrence rates. METHODS: Patients with a contaminated or clean-contaminated operative field and a hernia defect at least 9 cm had a biosynthetic mesh (open, sublay, retrorectus, or intraperitoneal) repair with fascial closure (n = 104). Endpoints included overall Kaplan-Meier estimates for hernia recurrence and postoperative wound infection rates at 24 months, and the EQ-5D and Short Form 12 Health Survey (SF-12). Analyses were conducted on the intent-to-treat population, and health outcome measures evaluated using paired t tests. RESULTS: Patients had a mean age of 58 years, body mass index of 28 kg/m, 77% had contaminated wounds, and 84% completed 24-months follow-up. Concomitant procedures included fistula takedown (n = 24) or removal of infected previously placed mesh (n = 29). Hernia recurrence rate was 17% (n = 16). At the time of CVH repair, intraperitoneal placement of the biosynthetic mesh significantly increased the risk of recurrences (P ≤ 0.04). Surgical site infections (19/104) led to higher risk of recurrence (P < 0.01). Mean 24-month EQ-5D (index and visual analogue) and SF-12 physical component and mental scores improved from baseline (P < 0.05). CONCLUSIONS: In this prospective longitudinal study, biosynthetic absorbable mesh showed efficacy in terms of long-term recurrence and quality of life for CVH repair patients and offers an alternative to biologic and permanent synthetic meshes in these complex situations

Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rhombus tilings

The degree of randomness, or partial order, present in two-dimensional supramolecular arrays of isophthalate tetracarboxylic acids is shown to vary due to subtle chemical changes such as the choice of solvent or small differences in molecular dimensions. This variation may be quantified using an order parameter and reveals a novel phase behaviour including random tiling with varying critical properties as well as ordered phases dominated by either parallel or non-parallel alignment of neighbouring molecules, consistent with long-standing theoretical studies. The balance between order and randomness is driven by small differences in the intermolecular interaction energies, which we show, using numerical simulations, can be related to the measured order parameter. Significant variations occur even when the energy difference is much less than the thermal energy highlighting the delicate balance between entropic and energetic effects in complex self-assembly processes

The Effects of Mothers' Depression on the Behavioral Assessment of Disruptive Child Behavior

This study uses a group design to compare depressed and non-depressed mothers and their disruptive children. It controls for broad environmental stress factors to examine whether specific differences between groups can be linked with mothers’ depression. It aims to build a more comprehensive picture of depressed mothers’ interactions with their disruptive children by comparing these interactions with those of similar, but non-maternally depressed mother-child dyads, and a non-clinic control group