Towards an effective potential for the monomer, dimer, hexamer, solid and liquid forms of hydrogen fluoride

We present an attempt to build up a new two-body effective potential for hydrogen fluoride, fitted to theoretical and experimental data relevant not only to the gas and liquid phases, but also to the crystal. The model is simple enough to be used in Molecular Dynamics and Monte Carlo simulations. The potential consists of: a) an intra-molecular contribution, allowing for variations of the molecular length, plus b) an inter-molecular part, with three charged sites on each monomer and a Buckingham "exp-6" interaction between fluorines. The model is able to reproduce a significant number of observables on the monomer, dimer, hexamer, solid and liquid forms of HF. The shortcomings of the model are pointed out and possible improvements are finally discussed.Comment: LaTeX, 24 pages, 2 figures. For related papers see also http://www.chim.unifi.it:8080/~valle

Innovative Capability of Building Information Modeling in Construction Design

The construction industry has long been urged to innovate, but innovation has been elusive because of the inherent social and organizational complexity of construction. Therefore, developing insight into the practice of innovating is needed to better understand and perform innovation in construction. Focusing on the practice of innovating requires exploring the enabling capability of solutions for practitioners to establish novel ways of doing things for improvement, referred to as ‘innovative capability.’ Building information modeling (BIM) has been promoted as an enabler of innovation in construction design because of its data management capabilities and the opportunities for interdisciplinary work based on them. Nevertheless, previous work presents divergent results exploring what BIM technologies can do for people and what people can actually do in BIM-enabled design practices, which presents confusion about the innovative capability of BIM. This paper aims to establish the basis of this confusion as a necessary step in developing more realistic ways of assessing and exploiting this capability. A conceptual continuum is proposed based on the functionalist/technology-centered and nonfunctionalist/human-centered perspectives on BIM to consider divergent arguments about its innovative capability; this continuum is used to analyze empirical findings from BIM-enabled design practices. The analyses suggest that individuals use BIM but are confused about its innovative capability because they adopt different views of BIM depending on their job and perspective. Given this, innovation is held back by the unexpressed differences between the views of BIM adopted by various practitioners who have to work together. It is argued that recognizing these differences, and working toward their reconciliation, is the way forward in establishing and exploiting the innovative capability of BIM

Effects of tranexamic acid on death, disability, vascular occlusive events and other morbidities in patients with acute traumatic brain injury (CRASH-3): a randomised, placebo-controlled trial

Background Tranexamic acid reduces surgical bleeding and decreases mortality in patients with traumatic extracranial bleeding. Intracranial bleeding is common after traumatic brain injury (TBI) and can cause brain herniation and death. We aimed to assess the effects of tranexamic acid in patients with TBI. Methods This randomised, placebo-controlled trial was done in 175 hospitals in 29 countries. Adults with TBI who were within 3 h of injury, had a Glasgow Coma Scale (GCS) score of 12 or lower or any intracranial bleeding on CT scan, and no major extracranial bleeding were eligible. The time window for eligibility was originally 8 h but in 2016 the protocol was changed to limit recruitment to patients within 3 h of injury. This change was made blind to the trial data, in response to external evidence suggesting that delayed treatment is unlikely to be effective. We randomly assigned (1:1) patients to receive tranexamic acid (loading dose 1 g over 10 min then infusion of 1 g over 8 h) or matching placebo. Patients were assigned by selecting a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was head injury-related death in hospital within 28 days of injury in patients treated within 3 h of injury. We prespecified a sensitivity analysis that excluded patients with a GCS score of 3 and those with bilateral unreactive pupils at baseline. All analyses were done by intention to treat. This trial was registered with ISRCTN (ISRCTN15088122), ClinicalTrials.gov (NCT01402882), EudraCT (2011-003669-14), and the Pan African Clinical Trial Registry (PACTR20121000441277). Results Between July 20, 2012, and Jan 31, 2019, we randomly allocated 12 737 patients with TBI to receive tranexamic acid (6406 [50·3%] or placebo [6331 [49·7%], of whom 9202 (72·2%) patients were treated within 3 h of injury. Among patients treated within 3 h of injury, the risk of head injury-related death was 18·5% in the tranexamic acid group versus 19·8% in the placebo group (855 vs 892 events; risk ratio [RR] 0·94 [95% CI 0·86-1·02]). In the prespecified sensitivity analysis that excluded patients with a GCS score of 3 or bilateral unreactive pupils at baseline, the risk of head injury-related death was 12·5% in the tranexamic acid group versus 14·0% in the placebo group (485 vs 525 events; RR 0·89 [95% CI 0·80-1·00]). The risk of head injury-related death reduced with tranexamic acid in patients with mild-to-moderate head injury (RR 0·78 [95% CI 0·64-0·95]) but not in patients with severe head injury (0·99 [95% CI 0·91-1·07]; p value for heterogeneity 0·030). Early treatment was more effective than was later treatment in patients with mild and moderate head injury (p=0·005) but time to treatment had no obvious effect in patients with severe head injury (p=0·73). The risk of vascular occlusive events was similar in the tranexamic acid and placebo groups (RR 0·98 (0·74-1·28). The risk of seizures was also similar between groups (1·09 [95% CI 0·90-1·33]). Interpretation Our results show that tranexamic acid is safe in patients with TBI and that treatment within 3 h of injury reduces head injury-related death. Patients should be treated as soon as possible after injury. Funding National Institute for Health Research Health Technology Assessment, JP Moulton Charitable Trust, Department of Health and Social Care, Department for International Development, Global Challenges Research Fund, Medical Research Council, and Wellcome Trust (Joint Global Health Trials scheme)

Sifat optik dan struktur saput tipis timah sulfida

Saput tipis timah sulfida telah disediakan dengan menggunakan teknik penyejatan vakum pada tekanan sekitar 1 x 10-4 tor dan pada suhu di antara 100 dan 300 oC. Ketebalannya adalah di antara 52 dan 570 nm. Pengukuran penyerapan di dalam julat cahaya nampak telah dilakukan dan didapati jurang jalurnya adalah sekitar 1.47 eV (bagi suhu sampel 100 oC) manakala cerapan belauan sinar-X pula menunjukkan bahawa komposisi saput berubah daripada SnS2 (suhu rendah) kepada SnS (suhu yang lebih tinggi)

Electrical conductivity measurements in evaporated tin sulphide thin films

Tin sulphide (SnS) has been evaporated on to substrates maintained at fixed temperature in the range 50-300 oC. X-ray diffraction measurements have shown that the films deposited at the lower substrate temperatures are non-stoichiometric, containing higher sulphides of tin, but that those deposited at 300 oC consist essentially only of SnS. Film conductivity increased in the range 0.5-2.0 S m-1 as the substrate temperature during deposition increased from 50 oC to 250 oC, this effect being attributed to the changing film composition. Films deposited at 50 oC and 150 oC showed thermally activated conductivity at temperatures above 220-250K, with activation energies Ea of 0.12 eV and 0.14 eV, respectively. At lower temperatures both conductivity and activation energy were considerably lower, consistent with hoping via localized states. The conductivity is modified after prolonged cooling to 160 K, although the mechanism of this process is not understood

Optical absorption in annealed tin sulphide thin films

Evaporated thin sulphide thin films have been prepared onto glass substrate at room temperature. The films were subjected to long period annealing in running argon gas up to 36 hours. Optical absorption measurements were made on the as prepared and annealed films near the fundamental absorption edge over the visible light vision light regions. Absorption coefficient, ï¡ were found to be of the order 10-5 cm-1 which suggest the occurance of indirect optical transition. A further investigation on the (ï¡hï®)1/2 and (ï¡hï®)1/3 plots revealed the existence of indirect allowed and indirect forbidden transition near the absorbtion edge respectively. The resulting optical band gap of the former were found to be 1.33 eV (as prepared) and between 1.59- 2.01 eV (annealed films) and this values were associated with compositional changes during annealing; the mainly SnS stoichiometric composition of the as prepared films was gradually disproportionated to SnS2 and completion of the course took place at the end 20 hours annealing. The optical band gap of 2.01 eV was in good agreement with those measured earlier on SnS2 in both thin film and bulk forms

Students' Satisfaction on the Quality of Service University Parcel Centre (Upc): a Focus on Uum

The purpose of this paper is to measure the level of students' satisfaction on University Parcel Centre (UPC) among University Utara Malaysia (UUM) students. The University Parcel Centre (UPC) play pivotal role in providing fundamental services to classify, arrange and store the students' parcel which arrive from the third-party couriers. It also recognizes as a one stop parcel hub center, so that students can collect their respective parcel by themselves at UPC. This study has adopted SERVQUAL model as the research framework. The five dimensions of this model which are tangibility, assurance, reliability, responsiveness and empathy were used to determine its effect on students' satisfaction on using the UPC services. This study adopted quantitative research design. A total of 370 respondents participated in the survey from which all of them were taken from around 20,000 UUM students living in campus. The Cronbach's Alpha score was 0.813. The findings showed that all the factors tested (tangible, reliability, responsiveness and empathy) were significant with positive relationship. Only one factor (assurance) is not significant. Strategies and dynamic initiatives should be driven by these factors to improve UPC service quality

Microstructure and dielectric properties of CaCu3Ti4O12 ceramic

CaCu3Ti4O12 (CCTO) was prepared by the solid state technique. The sample was calcined at 900 °C/12 h and sintered at 1050 °C/24 h, then subjected to XRD to ensure CCTO formation. The microstructure was observed by SEM. XRD results identified both samples as single phase CCTO, whereas the microstructure shows abnormal grain growth and large pores. Sintering was studied in the temperature range of 950–1050 °C for 3–12 h. Increasing sintering temperature enhances the density and secondary formation of Cu2O. A clear grain boundary and dense microstructure were observed. The results show that the sample sintered at 1040 °C/10 h yields a clearly uniform grain size with the highest εr (33,210