233 research outputs found

    High pressure infrared studies of HMX

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    We are studying the effects of pressure on HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) using infrared spectroscopy. The sample is put under pressure using a diamond anvil cell at ambient temperature, data is collected at the National Synchrotron Light Source in Brookhaven National Laboratory. In analyzing this data, we hope to learn more about the molecular vibrations as the molecule bends and deforms under pressure. Such understanding could aid in determining new safety standards or more efficient ways of using HMX. In future studies, we intend to include the aspect of temperature variation in addition to pressure, with the goal of describing the molecule in a phase diagram

    Potassium chlorate decomposition under high pressure

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    High pressure physics involves placing various substances under high pressure and observing changes in that substance. In this experiment this high amount of pressure is induced using a diamond anvil cell. A diamond anvil cell uses a metal gasket to hold the sample between two diamonds, which will press on the sample to reach high pressures. High pressures are reached with a moderate amount of force by exerting that force over a small area. Diamonds are used for the compression because of their hardness and ability to resist compression. The pressure being exerted on the sample using a diamond anvil cell is often measured using ruby fluorescence. The behavior of ruby under high pressure is well known so the pressure inside the diamond anvil cell can be determined by observing the ruby fluorescence. Ruby is placed inside the gasket along with the sample so that it is always at the same pressure as the sample. Potassium Chlorate is a chemical that is often used as an oxygen producer and as an explosive when mixed with other chemicals. It decomposes under heat to release oxygen gas, which is the reaction we are trying to induce by placing the chemical under pressure. When molecules heat up they begin to vibrate more rapidly and are more likely to collide with each other. When molecules undergo higher pressures they are also more likely to collide as atoms get closer together. The purpose of this experiment is to determine if pressure can induce the same reaction in Potassium Chlorate as heat

    Spectroscopic studies of melamine at high pressure

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    We have performed mid- and far- Infra Red (IR) absorption, Raman spectroscopy, and angular dispersive x-ray diffraction (XRD) studies on melamine under high pressure and room temperature. We have verified the presence of two prior reported phase transitions, the first between 1-2 GPa, and the second between 7-9 GPa. We have also found evidence of a third unreported phase transition between 14-16 GPa, during which, there was a sudden disappearance of all low energy peaks (-1 ) in both the Raman and IR spectra. The far-IR peak movement experiences a discontinuity as the rate of peak movement suddenly changes. The XRD pattern shows a dramatic change in crystal structure between 11 and 16 GPa. We observed softening of the N-H symmetric and anti-symmetric vibrations with pressure, suggesting that intermolecular hydrogen bonding increases as the intermolecular distance decreases similarly to what was observed in TATB [20]. The molecular decompression data from core intra-molecular peaks of mid IR and Raman show complete reversibility, giving evidence that the melamine did not chemically decompose at high pressures. Melamine merits this investigation into its high pressure behavior as it has many similarities with some high explosives. The closest cousin to melamine is the secondary explosive TATB, which is in the same symmetry group D 3h [16]. Understanding the exact science of explosives is an extremely difficult process, therefore approaching the problem from the examination of a similar inert compound may help yield a better understanding of explosives and the novel routes to the synthesis of ultra-hard materials such as C 3 N4

    Review of state of knowledge regarding the safety, access and usability needs of children with disabilities

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    Within European countries and the European Union, there is wide recognition that special consideration must be given to the needs of both people with disabilities and to young people. In terms of ergonomics design, consideration needs to be given to access to public buildings, safety in the home, school buildings and educational services, ability to make use of public transport, etc. This research focused on children who also have disabilities, an area that is less well understood and where it is uncertain whether standards or legislation exist. Interviews and discussions with experts were conducted to locate knowledge about design for disabled children in different contexts. This document reports the results of the research sponsored by ANEC (www.anec.org). The study identified relevant standards, legislation or guidelines within Europe and outside which could potentially be employed by the standards bodies within the European Union and promulgated more widely. The report also showed that there are gaps in knowledge indicating a requirement for further research to be carried out to generate suitable guidelines for standards bodies to consider

    High pressure study of 1,1-diamino-2,2-dinitroethene with Raman spectroscopy

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    The goal of this experiment is to better understand the reasons for Fox-7s insensitivity and high performance. It is very similar to other explosives in composition but different in structure. This different structure is believed to be the reason for Fox-7s unique characteristics. Using Raman spectroscopy along with high pressure techniques we hope to better understand this molecule and how it handles extreme conditions

    Raman studies of 1,3,5,7 Cyclooctatetraene at high pressure

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    We performed Raman spectroscopic studies of 1,3,5,7-cyclooctatetraene at elevated pressures up to 10 GPa with the aim of examining possible planarization of the molecule and further studying two prior-discovered phases of the solid with pressure. The Raman excitation source was a Krypton-ion laser operating at 674.1 nm (give wavelength). 1,3,5,7 Cyclooctatetraene has an octagonal formation however it is not aromatic or anti-aromatic (not a subject to the 4n+2 Huckel’s rule) [1]. As a result, its adopts a somewhat reactive tub shape. Upon the addition or removal of one to two electrons under ambient conditions, the molecule planarizes and becomes aromatic [3-5]. Our goal was to determine if we can aromatize the COT molecule mechanically or via electron transfer at elevated pressure

    Experiences of ergonomics practitioners on vacation

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    A group of practitioners collaborated in reporting ergonomic issues experienced during their holidays. While poor ergonomics made a big impression on the vacationers, good well-designed aspects of their holidays demonstrate the benefits that ergonomics can bring

    Can the Experience of Participatory Development Help Think Critically about ‘Patient and Public Involvement’ in UK Healthcare?

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    The expansion of spaces for ‘patient and public involvement’ (PPI) in health systems in the UK is a relatively recent phenomenon, and yet ‘participation’ as a principle for planned interventions in international development is well established as a field of practice and controversy. Development workers and scholars have passed through moments of enchantment and disenchantment with the idea that the true source of innovation, expertise and workable (and sustainable) solutions is to be found not in the professionals but in communities of experience. Making ‘local knowledge’ the basis of interventions has proved unexpectedly problematic. How could incommensurable forms of knowing, across steep gradients of power be bridged? This article describes a decade-long experiment in participatory development in a remote Adivasi (tribal) region of western India in order to suggest the relevance of this experience for the very different context of PPI in healthcare settings. In particular, it highlights some general points about knowledge practices at the interface, and the human tendency to adjust, mirror, mimic, loop and in other ways make the ‘patient-professional’ interface itself hard to navigate. The article suggests that self-reflective insight into these social processes is necessary for effective ‘engagement’ by professional and lay actors alike

    Effects of Propofol on Endotoxin-Induced Acute Lung Injury in Rabbit

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    This study was undertaken to clarify the effects of propofol on endotoxin-induced acute lung injury. Rabbits were randomly assigned to one of four groups. Each group received intravenous infusion of saline only, saline and Escherichia coli endotoxin, propofol (1 mg/kg bolus, then 5 mg/kg/hr) and endotoxin, or propofol (4 mg/kg bolus, then 20 mg/kg/hr) and endotoxin respectively. Infusion of saline or propofol was started 0.5 hr before the infusion of saline or endotoxin, and continued for 6 hr thereafter. The lungs of rabbits were ventilated with 40% oxygen. Mean blood pressure, heart rate, arterial oxygen tension (PaO2), and peripheral blood leukocyte and platelet count were recorded. The wet/dry (W/D) weight ratio of lung and lung injury score were measured, and analysis of bronchoalveolar lavage fluid (BALF) was done. Endotoxin decreased PaO2, and peripheral blood leukocyte and platelet count. And it increased W/D ratio of lung, lung injury score and leukocyte count, percentage of PMN cells, concentration of albumin, thromboxane B2 and IL-8 in BALF. Propofol attenuated all these changes except the leukocyte count in peripheral blood. In conclusion, propofol attenuated endotoxin-induced acute lung injury in rabbits mainly by inhibiting neutrophil and IL-8 responses, which may play a central role in sepsis-related lung injury
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