Measurement of mechanical and thermophysical properties of dimensionally stable materials for space applications

Mechanical, thermal, and physical property test data was generated for as-fabricated advanced composite materials at room temperature (RT), -150 and 250 F. The results are documented of mechanical and thermophysical property tests of IM7/PEEK and discontinuous SiC/Al (particulate (p) and whisker (w) reinforced) composites which were tested at three different temperatures to determine the effect of temperature on material properties. The specific material systems tested were IM7/PEEK (0)8, (0, + or - 45, 90)s, (+ or - 30, 04)s, 25 vol. pct. (v/o) SiCp/Al, and 25 v/o SiCw/Al. RT material property results of IM7/PEEK were in good agreement with the predicted values, providing a measure of consolidation integrity attained during fabrication. Results of mechanical property tests indicated that modulus values at each test temperature were identical, whereas the strength (e.g., tensile, compressive, flexural, and shear) values were the same at -150 F, and RT, and gradually decreased as the test temperature was increased to 250 F. Similar trends in the strength values was also observed in discontinuous SiC/Al composites. These results indicate that the effect of temperature was more pronounced on the strength values than modulus values

Composite materials for space applications

The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values

Aid conditionalities, international Good Manufacturing Practice standards and local production rights: a case study of local production in Nepal

© 2015 Brhlikova et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.This work was supported by the Economic and Social Research Council and the Department for International Development [RES-167-25-0110] through the collaborative research project Tracing Pharmaceuticals in South Asia (2006 – 2009). In addition to the authors of this paper, the project team included: Soumita Basu, Gitanjali Priti Bhatia, Erin Court, Abhijit Das, Stefan Ecks, Patricia Jeffery, Roger Jeffery, Rachel Manners, and Liz Richardson. Martin Chautari (Kathmandu) and the Centre for Health and Social Justice (New Delhi) provided resources drawn upon in writing this paper but are not responsible for the views expressed, nor are ESRC or DFID. Ethical review was provided by the School of Social and Political Science at the University of Edinburgh, and ethical approval in Nepal for the study granted by the Nepal Health Research Council (NHRC)

Evaluation of etoricoxib in patients undergoing total knee replacement surgery in a double-blind, randomized controlled trial.

BACKGROUND: Optimal postoperative pain management is important to ensure patient comfort and early mobilization. METHODS: In this double-blind, placebo- and active-controlled, randomized clinical trial, we evaluated postoperative pain following knee replacement in patients receiving placebo, etoricoxib (90 or 120 mg), or ibuprofen 1800 mg daily for 7 days. Patients \u3e=18 years of age who had pain at rest \u3e=5 (0--10 Numerical Rating Scale [NRS]) after unilateral total knee replacement were randomly assigned to placebo (N = 98), etoricoxib 90 mg (N = 224), etoricoxib 120 mg (N = 230), or ibuprofen 1800 mg (N = 224) postoperatively. Co-primary endpoints included Average Pain Intensity Difference at Rest over Days 1--3 (0- to 10-point NRS) and Average Total Daily Dose of Morphine over Days 1--3. Pain upon movement was evaluated using Average Pain Intensity Difference upon Knee Flexion (0- to 10-point NRS). The primary objective was to demonstrate analgesic superiority for the etoricoxib doses vs. placebo; the secondary objective was to demonstrate that the analgesic effect of the etoricoxib doses was non-inferior to ibuprofen. Adverse experiences (AEs) including opioid-related AEs were evaluated. RESULTS: The least squares (LS) mean (95% CI) differences from placebo for Pain Intensity Difference at Rest over Days 1--3 were -0.54 (-0.95, -0.14); -0.49 (-0.89, -0.08); and -0.45 (-0.85, -0.04) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively (p \u3c 0.05 for etoricoxib vs. placebo). Differences in LS Geometric Mean Ratio morphine use over Days 1--3 from placebo were 0.66 (0.54, 0.82); 0.69 (0.56, 0.85); and 0.66 (0.53, 0.81) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively (p \u3c 0.001 for etoricoxib vs. placebo). Differences in LS Mean Pain Intensity upon Knee Flexion were -0.37 (-0.85, 0.11); -0.46 (-0.94, 0.01); and -0.42 (-0.90, 0.06) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively. Opioid-related AEs occurred in 41.8%, 34.7%, 36.5%, and 36.3% of patients on placebo, etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively. CONCLUSIONS: Postoperative use of etoricoxib 90 and 120 mg in patients undergoing total knee replacement is both superior to placebo and non-inferior to ibuprofen in reducing pain at rest and also reduces opioid (morphine) consumption.Clinical trial registration: NCT00820027

Preferences and skills of Indian public sector teachers

With a sample of 700 future public sector primary teachers in India, a Discrete Choice Experiment is used to measure job preferences, particularly regarding location. General skills are also tested. Urban origin teachers and women are more averse to remote locations than rural origin teachers and men respectively. Women would require a 26-73 percent increase in salary for moving to a remote location. The results suggest that existing caste and gender quotas can be detrimental for hiring skilled teachers willing to work in remote locations. The most preferred location is home, which supports decentralised hiring, although this could compromise skills

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation

We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis

Development of a Thin-Film Solar Cell Interconnect for the Powersphere Concept

Dual junction amorphous silicon (a-Si) solar cells produced on polyimide substrate have been selected as the best candidate to produce a lightweight solar array for the PowerSphere program. The PowerSphere concept features a space-inflatable, geodetic solar array approximately 0.6 meters in diameter and capable of generating about 20W of electrical power. Trade studies of various wiring concepts and connection methods led to an interconnect design with a copper contact that wraps around the edge, to the back of the solar cell. Applying Plasma Vapor Deposited (PVD) copper film to both sides and the edge of the solar cell produces the wrap around contact. This procedure results in a contact pad on the back of the solar cell, which is then laser welded to a flex circuit material. The flex circuit is constructed of copper in a custom designed routing pattern, and then sandwiched in a Kapton insulation layer. The flex circuit then serves as the primary power distribution system between the solar cells and the spacecraft. Flex circuit material is the best candidate for the wiring harness because it allows for low force deployment of the solar cells by the inflatable hinges on the PowerSphere. An additional frame structure, fabricated and assembled by ILC Dover, will reinforce the wrap around contact-flex blanket connection, thus providing a mechanically robust solar cell interconnect for the PowerSphere multifunctional program. The PowerSphere team will use the wraparound contact design approach as the primary solution for solar cell integration and the flex blanket for power distribution

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: Environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 ??C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.ope