Computational Chemistry Modelling of the Oxidation of Highly Oriented Pyrolitic Graphite (HOPG)

Under high heat flux, carbon based Thermal Protection Systems (TPS) are observed to rapidly ablate and an accurate characterization is essential to their design. Dissociated oxygen atoms (from the gas phase) striking the surface of TPS could lead to several possibilites. The O atom could adsorb on the surface, recombine with another O atom to form O2 and oxidize the surface to produce CO or CO2 resulting in recession of the surface (ablation). The goal is to predict finite rate models for these reactions which could be incorporated into CFD and DSMC solvers. Our efforts are to predict the rates through large scale Molecular Dynamics (MD) simulations using the ReaxFF potential which enables accurate simulation of large chemically reacting systems of molecules. In this work, we simulate the collision of hyperthermal (5eV) O atoms on Highly Oriented Pyrolitic Graphite (HOPG) at 525K. The simulations are compared to molecular beam experiments performed by Minton and co-workers

Is Fecal Leukocyte Test a good predictor of Clostridium difficile associated diarrhea?

BACKGROUND: Fecal leukocyte test (FLT) is widely used to screen for invasive diarrheas including C. difficile associated diarrhea (CDAD), which account for more than 25 % of all antibiotic associated diarrhea. METHOD: 263 stool samples from patients with suspected CDAD were studied simultaneously for fecal leukocyte test (FLT) and Clostridium difficile toxin assay (CDTA). FLT was performed by the Giemsa technique and CDTA was performed by enzyme immuno assay (EIA). RESULTS: Sensitivity, specificity, positive predictive value and negative predictive value of FLT as compared to CDTA were 30%, 74.9%, 13.2% and 89.3% respectively. CONCLUSION: Considering the poor sensitivity of FLT, and the comparable cost and time of obtaining a CDTA at our institution, we conclude that FLT is not a good screening test for CDAD. Possible reasons for FLT being a poor predictor of CDTA are discussed

Influence of heat-treatment on torsional resistance to fracture of Nickel-Titanium endodontic instruments

AbstractOver the past 3 decades, Nickel-Titanium (NiTi) instruments have become an important part of the armamentarium for shaping phase of root canal treatment. NiTi endodontic files have increased flexibility and strength compared with stainless steel instruments, but they seem to be vulnerable to fracture in clinical situations. Many variables might contribute to file separation, but the 2 main causes are cyclic fatigue and torsional stress. Heat treatment (thermal processing) is one of the most fundamental approaches toward adjusting the transition temperatures of NiTi alloys and affecting the fatigue and torsional resistance of NiTi endodontic files. In recent years, novel thermo-mechanical processing and manufacturing technologies such as controlled memory wire (CM-wire), M-Wire and electrical discharge machining (EDM) have been developed to optimize the microstructure of NiTi alloys and their mechanical properties. Aim of this work was to investigate the torsional resistance (maximum torque load, and angular rotation) of NiTi instruments made by different thermo-mechanical and manufacturing processes.One-hundred new Hyflex EDM One- File (#25/0.08, CM-wire and EDM process), WaveOne Primary (#25/0.08, M-wire), ProTaper Next X2 (#25/0.06, M-wire), Hyflex CM (#25/0.06, CM-wire) and F6 SkyTaper(#25/0.06, conventional NiTi) files were used. Torque and angle of rotation at failure of new instruments (n = 20) were measured using a torsiometer according to ISO 3630-1 for each brand. Data were analyzed using the analysis of variance test and the Student- Newman-Keuls test for multiple comparisons. The fracture surface of each fragment was examined with a scanning electron microscope.Files made by CM wire size #25, 0.06 taper (Hyflex CM) showed same torque load and angular rotation to fracture than conventional NiTi (F6 SkyTaper) (P > .05); instead CM files (manufacturing by grinding or EDM process) recorded lower maximum torque load (P .05) but significantly higher angular rotation (P < .05) to fracture than M-wire instruments size #25, 0.06 taper (ProTaper Next).Hyflex EDM One-File and Hyflex CM have same torque load and angular rotation to fracture than F6 SkyTaper due to the higher flexibility and cross-sectional area of CM files tested than conventional NiTi one.Moreover CM files showed lower torque load and higher angular rotation to fracture than M-wire instruments due to the flexibility of CM alloy. M-wire instruments showed same torque load but significantly lower angular rotation than conventional NiTi files due to the same flexibility and higher cross-sectional area of the files tested

La Lectura reflexiva de textos técnicos y científicos en la Universidad.

En la enseñanza universitaria se transmiten contenidos disciplinarios específicos, considerando que los alumnos tienen que comprender y entender el contenido de lo que leen. En la carrera de Ingeniería (FTyCA) los estudiantes constantemente acceden a textos técnicos que han sido por ellos seleccionados o impuestos por el profesor como material de estudio. Esta tarea no siempre tiene resultados positivos; con la finalidad de comprender las razones de las dificultades que se presentan, se analizan en este trabajo aspectos relacionados con este proceso. Nuestro objetivo es lograr que el alumno enfrente y resuelva las dificultades con la presencia y colaboración permanente de sus profesores, apoyado en capacidades de tipo cognitivo y metacognitivo. Los resultados demuestran que si se trabaja en conjunto guiando a los alumnos a través de proceso organizados, el desarrollo de la lectura es efectivo y surgen en consecuencia lectores autónomos y reflexivos

Studi sosioliguistik bahasa Fataluku di Lautém

This book describes the end result of a research in Laut_m between 2010 and 2014, as part of a research project on Adult Literacy Education in Timor-Leste. This book focuses on the Fataluku language that is spoken in Laut_m District, specifically in the sub districts of Lospalos and Tutuala. Fataluku is a non-Austronesian language that can be considered endangered, because most speakers of younger generations prefer Tetum of Fataluku. By means of a study on the national language policy, Laut_m__s linguistic landscape, Fataluku language attitudes and uses, and through a case study on adult literacy classes, this book discusses the change of an endangered unwritten language into a language that is written. This book shows that the planned education language policy does not yet apply correctly in Laut_m. Although the national language policy anticipates Portuguese and Tetum to become the languages of teaching, it turns out that Fataluku is till being used with that particular function in education.NWO‐WOTRO Science for Global DevelopmentAsian Studie

Influence of growing conditions on the reactivity of Ni supported graphene towards CO

Free standing graphene is chemically inert but, as recently demonstrated, CO chemisorption occurs at low crystal temperature on the single layer grown by ethene dehydrogenation on Ni(111). Such layer is inhomogeneous since different phases coexist, the relative abundance of which depends on the growth conditions. Here we show by X ray photoemission and high resolution electron energy loss spectroscopies that the attained CO coverage depends strongly on the relative weight of the different phases as well as on the concentration of carbon in the Ni subsurface region. Our data show that the chemical reactivity is hampered by the carbon content in the substrate. The correlation between the amount of adsorbed CO and the weight of the different graphene phases indicates that the top-fcc configuration is the most reactive

Economic Effects of a Tax Policy to Reduce Greenhouse-Gas Emissions in Brazil

Brazil has proposed to reduce emissions by 37% below 2005 levels in 2025, and for indicative purposes, to further reduce it by 43% in 2030, following the agreement of COP-21 in Paris. This study seeks to investigate the macroeconomic effects if Brazil adopts a GHG emissions tax to meet the carbon reduction commitment and to simulate the thesis of "double dividend". A neoclassical growth model with the introduction of environment and fiscal policy was used. A tax rate on CO2 emissions of US$ 100.00/tCO2e would be enough to meet Brazil´s target of emission reduction. The double dividend hypothesis was observed in Brazil’s case and the best results occur when capital income tax is reduced

Nanofabrication strategies for influencing biomolecule behavior

In recent years, nanofabrication techniques have shown themselves to have the most promising potential for innovative research on crucial biomolecules for life sciences, such as DNA and RNA. Two main examples are: Firstly, large-scale nanostructuring, effective for engineering innovative biosensors; and secondly, nanopores, intensively exploited for developing fast and inexpensive technologies for DNA sequencing, a major research challenge in the field of biomedicine. In addition to nanopores, nanoslits and nanochannels allow interesting functionalities for the study, processing and sorting of DNA. For example, when a long DNA chain is forced to enter a nanochannel, it stretches, thus acquiring a conformation which allows its genetic information to be optically read. Herein, we have focused on various geometry-based strategies, involving short and long channels, as well as funnels and a series of pit nanostructures, integrated into polymeric lab-on-a-chip models. We have implemented these miniaturized systems in order to study, at single molecule level, the typical conformations of DNA chains in various nano-confinement conditions whilst also observing the dynamic behavior of the long strands in crossing structures with different cross sections. In fact, by taking advantage of polydimethylsiloxane's elasticity, we have developed a strategy for modulating the translocation dynamics of single molecules crossing a nanochannel. Lastly, we have investigated on important applications for life and material sciences of the recent innovative tool which counts and recognizes nanoparticles through a new simultaneous optical and electrical sensing method

Antioxidant Supplementation Impairs Changes in Body Composition Induced by Strength Training in Young Women

International Journal of Exercise Science 12(2): 287-296, 2019. Strength training (ST) is known to promote muscle hypertrophy and body composition adaptations. However, only a few studies investigated the effects of ST combined with antioxidant supplementation (AS) on these adaptations. The aim of this study was to investigate chronic effects of ST combined with AS on fat mass (FM) and fat-free mass (FFM) of young women. In a double-blinded design, thirty-three subjects (22.9 ± 2.5 years, 57.7 ± 8.4 kg, 1.6 ± 0.6 m) were allocated into three groups: 1) vitamins (n=12), 2) placebo (n=11) and 3) control (n=10). Vitamins and placebo underwent a ST program for 10 weeks. Vitamins supplemented with vitamin C (1g/day) and E (400IU/day) during the training period. FM and FFM were assessed by DEXA. Multiple 3 x 2 (group x time) mixed- factor ANOVA with Tukey adjustment was performed to examine differences in the dependent variables. The significance level was set at P ≤ .05. Only placebo increased total FFM (34.9 ± 4.9 vs 36.3 ± 4.8 kg, P\u3c0.05) and decreased total FM (21.8 ± 7.8 vs 21.0 ± 8.3 kg, P\u3c0.05) after training for 10 weeks. Moreover, only placebo presented a significantly greater FFM percent change from pre to post-intervention compared to control (4.0 ± 3.4 vs -0.7 ± 3.1%, respectively, P \u3c 0.05). These results suggest that chronic AS can mitigate ST related improvements of body composition in young women

Assessing the genetic diversity of rice originating from Bangladesh, Assam and West Bengal

Acknowledgements This work was funded by BBSRC research project BB/J00336/1. FS and a part of the proportion of the cost of the Illumina genotyping was funded by a Beachell-Borlag International Fellowship. The authors would like to acknowledge the help of Dr MK Sarmah in collecting seed samples of the landraces and improved cultivars from Assam used in this study and Dr. Ma. Elizabeth B. Naredo and Ms. Sheila Mae Q. Mercado for handling of IRGC accessions and preparation of DNAs for genotyping. All rice seeds used here were obtained with MTA agreements and seed and dry leaves imported into the UK under import licence IMP⁄SOIL⁄18⁄2009 issued by Science and Advice for Scottish Agriculture.Peer reviewedPublisher PD