156 research outputs found

    Evidence for magnetic clusters in Ni1x_{1-x}Vx_{x} close to the quantum critical concentration

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    The d-metal alloy Ni1x_{1-x}Vx_{x} undergoes a quantum phase transition from a ferromagnetic ground state to a paramagnetic ground state as the vanadium concentration xx is increased. We present magnetization, ac-susceptibility and muon-spin relaxation data at several vanadium concentrations near the critical concentration xc11.6x_c \approx11.6% at which the onset of ferromagnetic order is suppressed to zero temperature. Below xcx_c, the muon data reveal a broad magnetic field distribution indicative of long-range ordered ferromagnetic state with spatial disorder. We show evidence of magnetic clusters in the ferromagnetic phase and close to the phase boundary in this disordered itinerant system as an important generic ingredient of a disordered quantum phase transition. In contrast, the temperature dependence of the magnetic susceptibility above xcx_c is best described in terms of a magnetic quantum Griffiths phase with a power-law distribution of fluctuation rates of dynamic magnetic clusters. At the lowest temperatures, the onset of a short-range ordered cluster-glass phase is recognized by an increase in the muon depolarization in transverse fields and maxima in ac-susceptibility.Comment: 6 pages, 5 figures, submitted to Proceedings of SCES 201

    Transformation Mechanisms & Metaphors in Architectural Design of Post Modernism Era Between Type & Model: Analytical Study on Comparison Between the Universities of Baghdad And Al Mustansiriyah

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    The design output is a representation of several important attitudes and perceptions, which have contributed, and contributes to the generation of the form through special design methods. The architect’s role is to transform the intellectual or physical reference to architectural product using design and architectural composition act or vice versa. The main issue of the search is the lack of a clear perception in determiningthe relationship between two important terms in design (type and model) and their role as tools for producing architectural form. The search is based on a hypothesis that it’s a constant shift cycle from type to model or vice versa or can reached an edge and stopped. The aims is to identify concrete inputs in order to determine aspecific vocabulary frame to shift cycle, and applied this frame to analysis architectural projects in the city of Baghdad. The research contains definitions of model, types, transformation and their mechanisms. In addition, it has a practical part which assists on the election of two examples of architectural works resulting from transformation strategies as full cycle (not equivalent) for architectural product. The last part contains research findings, conclusions and recommendations. Accordingly, the search main conclusion is that the design basis for Baghdad University project as approved formal grounds derived from the old fabric of the city of Baghdad, where the design basis of Al Mustansiriyah University buildings is a model based on inherited Mustansiriya

    Examining the effectiveness of consuming flour made from agronomically biofortified wheat (Zincol-2016/NR-421) for improving Zn status in women in a low resource setting Pakistan: Study protocol for a randomised, double blind, controlled cross over trial (BiZiFED)

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    Introduction: Dietary zinc (Zn) deficiency is a global problem, particularly in low and middle-income countries where access to rich, animal-source foods of Zn is limited due to poverty. In Pakistan, Zn deficiency affects over 40% of the adult female population, resulting in sub-optimal immune status and increased likelihood of complications during pregnancy. Methods and analysis: We are conducting a double blind, randomised controlled feeding study with crossover design, in a low resource setting in Pakistan. Households were provided with flour milled from genetically and agronomically biofortified grain (Zincol-2016/NR-421) or control grain (Galaxy-2013. Fifty households were recruited. Each household included a female aged 16-49 years who is neither pregnant nor breastfeeding, and not currently consuming nutritional supplements. These women were the primary study participants. All households were provided with control flour for an initial 2-week baseline period, followed by an 8-week intervention period where 25 households receive biofortified flour (Group A) and 25 households receive control flour (Group B). After this eight-week period, Group A and B crossed over, receiving control and biofortified flour respectively for eight weeks. Tissue (blood, hair and nails) have been collected from the women at five time points: baseline, mid and end of period 1, mid and end of period 2. Ethics and dissemination: Ethical approval was granted from the lead University (reference number: STEMH 697 FR) and the collaborating institution in Pakistan. The final study methods (including any modifications) will be published in peer reviewed journals, alongside the study outcomes on completion of the data analysis. In addition, findings will be disseminated to the scientific community via conference presentations and abstracts and communicated to the study participants through the village elders at an appropriate community forum

    Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment

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    In this paper, we review theoretical and experimental research on rare region effects at quantum phase transitions in disordered itinerant electron systems. After summarizing a few basic concepts about phase transitions in the presence of quenched randomness, we introduce the idea of rare regions and discuss their importance. We then analyze in detail the different phenomena that can arise at magnetic quantum phase transitions in disordered metals, including quantum Griffiths singularities, smeared phase transitions, and cluster-glass formation. For each scenario, we discuss the resulting phase diagram and summarize the behavior of various observables. We then review several recent experiments that provide examples of these rare region phenomena. We conclude by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative Ising chain fixed, references added, v3: final version as publishe

    Intestinal perforation due to adult tapeworm of Taenia: a case report and review of the literature

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    Taeniasis is an intestinal helminth infection due to adult tapeworms belonging to the genus Taenia. Taeniasis remains a major burden in low-income countries in Asia. We present a case of intestinal perforation caused by adult tapeworm of Taenia in a 50-year-old Nepali male. The patients presented to the hospital with severe abdominal pain and intermittent vomiting. Following clinical presentations and imaging features, gastrointestinal perforation was suspected. Surgical removal of adult tapeworm of Taenia, suspected to be T. saginata or T. asiatica, was carried out during exploratory laparotomy, which was followed by an uneventful postoperative period. In addition to case presentation, we systematically review published case reports on taeniasis-related intestinal perforation. A learning point from this case is clinician should maintain a clinical suspicion of taeniasis as a possible cause of intestinal perforation in endemic areas

    Development and properties of polymeric nanocomposite coatings

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    Polymeric-based nanocomposite coatings were synthesized by reinforcing epoxy matrix with titanium nanotubes (TNTs) loaded with dodecylamine (DOC). The performance of the developed nanocomposite coatings was investigated in corrosive environments to evaluate their anti-corrosion properties. The SEM/TEM, TGA, and FTIR analysis confirm the loading of the DOC into the TNTs. The UV-Vis spectroscopic analysis confirms the self-release of the inhibitor (DOC) in response to the pH change. The electrochemical impedance spectroscopic (EIS) analysis indicates that the synthesized nanocomposite coatings demonstrate superior anticorrosion properties at pH 2 as compared to pH 5. The improved anticorrosion properties of nanocomposite coatings at pH 2 can be attributed to the more effective release of the DOC from the nanocontainers. The superior performance makes polymeric nanocomposite coatings suitable for many industrial applications.Qatar University, University of Auckland, Qatar FoundationScopu

    Synthesis and properties of polyelectrolyte multilayered microcapsules reinforced smart coatings

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    The present research work focuses on the synthesis, characterization and properties of novel polyelectrolyte multilayered microcapsules used as smart additives in organic coatings for corrosion protection of steel parts. Urea formaldehyde microcapsules encapsulated with linalyl acetate (UFMCs), sensitive to mechanical stimulus, were synthesized by in situ emulsion polymerization technique. In the next step, dodecylamine, working as a pH stimulus corrosion inhibitor, was loaded into layers of polyelectrolyte molecules, polyethylenimine (PEI) and sulfonated polyether ether ketone (SPEEK). These were applied layer-by-layer over the microcapsules to form inhibitor containing multilayered urea formaldehyde microcapsules (MLUFMCs). In the next step, MLUFMCs (5.0 wt%) and UFMCs (5.0 wt%) were thoroughly dispersed into the epoxy resin and coated on cleaned steel. A comparison of the structural, thermal and anticorrosive properties indicates that coatings modified with multilayered capsules (PMLSCs) demonstrate good thermal stability, improved self-healing characteristics and higher corrosion resistance compared to the coating modified with urea formaldehyde microcapsules. The improved properties of PMLSCs can be attributed to efficient release of the encapsulated self-healing agent and corrosion inhibitor from the MLUFMCs. Therefore, epoxy coatings modified with the novel multilayered capsules may be attractive for corrosion protection of steel parts used in oil and gas and related industries. - 2019, The Author(s).Open Access funding provided by the Qatar National Library. This publication was made possible by NPRP Grant 9–080-2-039 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. R. A. Shakoor would like to acknowledge the financial support of QU internal grant-QUCG-CAM-2018/2019-3 and the Core Labs, QEERI for their SEM and TEM imaging. M.F. Mon-temor thanks Fundac¸ão para a Ciência e a Tecnologia (FCT, Portugal) for financial support under the projects PEst-OE/QUI/UI0100/2013.Scopu

    Evidence for Magnetic Clusters in Ni₁₋ₓVₓ Close to the Quantum Critical Concentration

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    The d-metal alloy Ni1-xVx undergoes a quantum phase transition from a ferromagnetic ground state to a paramagnetic ground state as the vanadium concentration x is increased. We present magnetization, ac-susceptibility and muon-spin relaxation data at several vanadium concentrations near the critical concentration xc ~ 11.6 % at which the onset of ferromagnetic order is suppressed to zero temperature. Below xc, the muon data reveal a broad magnetic field distribution indicative of a long-range ordered ferromagnetic state with spatial disorder. We show evidence of magnetic clusters in the ferromagnetic phase and close to the phase boundary in this disordered itinerant system as an important generic ingredient of a disordered quantum phase transition. In contrast, the temperature dependence of the magnetic susceptibility above xc is best described in terms of a magnetic quantum Griffiths phase with a power-law distribution of fluctuation rates of dynamic magnetic clusters. At the lowest temperatures, the onset of a short-range ordered cluster-glass phase is recognized by an increase in the muon depolarization in transverse fields and maxima in ac-susceptibility

    Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

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    Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

    Effect of Furnace Parameters on Optical Emission Spectra of Hematite Reduction by Hydrogen Plasma

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    Abstract Hydrogen plasma smelting reduction (HPSR) has been envisaged as a potential CO2-lean process for ore-based steelmaking, combining the reduction, melting and refining steps into a single unit process. However, scaling the process to industrial use still requires some work. In previous studies, optical emission spectroscopy (OES) has been suggested as a potential process monitoring method for HPSR. The present study investigates the effect of furnace parameters, such as the arc length and current, on the optical emissions of the hematite reduction by HPSR. To understand the effect of slag components, a few experiments were also conducted with fluxed hematite. It was found that the optical emissions of non-ionized elements are more intense at lower currents than at higher currents due to a lower level of ionization. The electron density calculated from the optical emissions could be used to estimate the arc length if the arc cannot be directly observed. It was also noted that the optical emissions of the slag components are very distinct in fluxed hematite experiments, which is of interest for potential industrial applications. Finally, the positioning of the optical fiber in relation to the plasma was found to be crucial for the successful monitoring of the experiments.Abstract Hydrogen plasma smelting reduction (HPSR) has been envisaged as a potential CO2-lean process for ore-based steelmaking, combining the reduction, melting and refining steps into a single unit process. However, scaling the process to industrial use still requires some work. In previous studies, optical emission spectroscopy (OES) has been suggested as a potential process monitoring method for HPSR. The present study investigates the effect of furnace parameters, such as the arc length and current, on the optical emissions of the hematite reduction by HPSR. To understand the effect of slag components, a few experiments were also conducted with fluxed hematite. It was found that the optical emissions of non-ionized elements are more intense at lower currents than at higher currents due to a lower level of ionization. The electron density calculated from the optical emissions could be used to estimate the arc length if the arc cannot be directly observed. It was also noted that the optical emissions of the slag components are very distinct in fluxed hematite experiments, which is of interest for potential industrial applications. Finally, the positioning of the optical fiber in relation to the plasma was found to be crucial for the successful monitoring of the experiments
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