186 research outputs found

    Exploring fully heavy scalar tetraquarks QQQQQQ\overline{Q}\overline{Q}

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    The masses, current couplings and widths of the fully heavy scalar tetraquarks X4Q=QQQQX_{\mathrm{4Q}}=QQ\overline{Q}\overline{Q}, Q=c,bQ=c, b are calculated by modeling them as four-quark systems composed of axial-vector diquark and antidiquark. The masses m()m^{(\prime)} and couplings f() f^{(\prime)} of these tetraquarks are computed in the context of QCD sum rule method by taking into account a nonperturbative term proportional to a gluon condensate αsG2/π\langle \alpha _{s}G^{2}/ \pi \rangle. Results obtained for m=(6570±55) MeVm=(6570 \pm 55)~\mathrm{MeV} and m=(18540±50) MeVm^{\prime}=(18540 \pm 50)~\mathrm{MeV } are used to fix kinematically allowed decay channels of these states. It turns out that, processes X4cJ/ψJ/ψX_{\mathrm{4c}}\rightarrow J/\psi J/\psi , X4cηcηcX_{ \mathrm{4c}}\rightarrow \eta _{c}\eta _{c}, and X4cηcχc1(1P)X_{\mathrm{4c}}\rightarrow \eta _{c}\chi _{c1}(1P) are possible decay modes of X4cX_{\mathrm{4c}}. Partial widths of these channels are evaluated by means of couplings gi,i=1,2,3g_{i}, i=1,2,3 which describe strong interactions of tetraquark X4cX_{\mathrm{4c}} and mesons at relevant vertices. The couplings gig_{i} are extracted from QCD three-point sum rules by extrapolating corresponding form factors gi(Q2) g_{i}(Q^2) to the mass-shell of the final meson. The mass of the scalar tetraquark X4bX_{\mathrm{4b}} is below the ηbηb\eta_b \eta_b and Υ(1S)Υ(1S) \Upsilon(1S)\Upsilon(1S) thresholds, therefore X4bX_{\mathrm{4b}} is strong-interaction stable particle. Comparing m=(6570±55) MeVm=(6570 \pm 55)~\mathrm{MeV} and Γ4c=(110±21) MeV\Gamma _{\mathrm{4c}}=(110 \pm 21)~\mathrm{MeV} with parameters of structures observed by LHCb, ATLAS and CMS collaborations, we interpret X4c X_{4c} as a resonance X(6600)X(6600) reported by CMS. Comparisons are made with other theoretical predictions.Comment: 12 Pages, 4 Figures and 2 Table

    Cu/cuo composite track-etched membranes for catalytic decomposition of nitrophenols and removal of as(III)

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    One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP05130797Funding: A.M. gratefully acknowledges the funding of the Ministry of Education and Science of the Republic of Kazakhstan (Project AP05130797)

    Application of silver-loaded composite track-etched membranes for photocatalytic decomposition of methylene blue under visible light

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    In this study, the use of composite track-etched membranes (TeMs) based on polyethylene terephthalate (PET) and electrolessly deposited silver microtubes (MTs) for the decomposition of toxic phenothiazine cationic dye, methylene blue (MB), under visible light was investigated. The structure and composition of the composite membranes were elucidated by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction technique. Under visible light irradiation, composite membrane with embedded silver MTs (Ag/PET) displayed high photocatalytic efficiency. The effects of various parameters such as initial dye concentration, temperature, and sample exposure time on the photocatalytic degradation process were studied. The decomposition reaction of MB was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The degradation kinetics of MB accelerated with increasing temperature and activation energy, Ea, was calculated to be 20.6 kJ/mol. The reusability of the catalyst was also investigated for 11 consecutive runs without any activation and regeneration procedures. The Ag/PET composite performed at high degradation efficiency of over 68% after 11 consecutive uses. © 2021 by the authors.The research titled ?Development of functionalized composite track-etched membranes for environmental applications? (grant No AP08855527) was funded by the Ministry of Education and Science of the Republic of Kazakhstan. M.V.Z. acknowledges the International Atomic Energy Agency (IAEA) for support under coordinated research project F22070 (IAEA Research Contract No: 23152)

    CRISPR Systems for COVID-19 Diagnosis

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    The emergence of the new coronavirus 2019 (COVID-19) was first seen in December 2019, which has spread rapidly and become a global pandemic. The number of cases of COVID-19 and its associated mortality have raised serious concerns worldwide. Early diagnosis of viral infection undoubtedly allows rapid intervention, disease management, and substantial control of the rapid spread of the disease. Currently, the standard approach for COVID-19 diagnosis globally is the RTqPCR test; however, the limited access to kits and associated reagents, the need for specialized lab equipment, and the need for highly skilled personnel has led to a detection slowdown. Recently, the development of clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostic systems has reshaped molecular diagnosis. The benefits of the CRISPR system such as speed, precision, specificity, strength, efficiency, and versatility have inspired researchers to develop CRISPRbased diagnostic and therapeutic methods. With the global COVID-19 outbreak, different groups have begun to design and develop diagnostic and therapeutic programs based on the efficient CRISPR system. CRISPR-based COVID-19 diagnostic systems have advantages such as a high detection speed (i.e., 30 min from raw sample to reach a result), high sensitivity and precision, portability, and no need for specialized laboratory equipment. Here, we review contemporary studies on the detection of COVID-19 based on the CRISPR system

    Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration

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    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol-1 in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux

    Kinetic and isotherm study of as(Iii) removal from aqueous solution by pet track-etched membranes loaded with copper microtubes

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    This paper reports on the synthesis and structure elucidation of track-etched membranes (TeMs) with electrolessly deposited copper microtubes (prepared in etched-only and oxidized polyethylene terephthalate (PET) TeMs), as well as on the comparative testing of arsenic (III) ion removal capacities through bath adsorption experiments. The structure and composition of composites were investigated by X-ray diffraction technique and scanning electron and atomic force microscopies. It was determined that adsorption followed pseudo-second-order kinetics, and the adsorption rate constants were calculated. A comparative study of the applicability of the adsorption models of Langmuir, Freundlich, and Dubinin–Radushkevich was carried out in order to describe the experimental isotherms of the prepared composite TeMs. The constants and parameters of all of the above equations were determined. By comparing the regression coefficients R2, it was shown that the Freundlich model describes the experimental data on the adsorption of arsenic through the studied samples better than others. Free energy of As(III) adsorption on the samples was determined using the Dubinin–Radushkevich isotherm model and was found to be 17.2 and 31.6 kJ/mol for Cu/PET and Cu/Ox_PET samples, respectively. The high EDr value observed for the Cu/Ox_PET composite indicates that the interaction between the adsorbate and the composite is based on chemisorption. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The research project titled “Development of functionalized composite track-etched membranes for environmental applications” (grant No. AP08855527) was funded by the Ministry of Education and Science of the Republic of Kazakhstan

    A Novel Cu2O/ZnO@PET Composite Membrane for the Photocatalytic Degradation of Carbendazim

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    The extremely high levels of water pollution caused by various industrial activities represent one of the most important environmental problems. Efficient techniques and advanced materials have been extensively developed for the removal of highly toxic organic pollutants, including pesticides. This study investigated the photocatalytic degradation of the fungicide carbendazim (Czm) using composite track-etched membranes (TeMs) in an aqueous solution. Copper(I) oxide (Cu2O) and zinc oxide (ZnO) microtubes (MTs) were prepared using an electroless template deposition technique in porous poly(ethylene terephthalate) (PET) TeMs with nanochannels with a density of 4 × 107 pores/cm-2 and diameter of 385 _ 9 nm to yield Cu2O@PET and ZnO@PET composite membranes, respectively. A mixed Cu2O/ZnO@PET composite was prepared via a two-step deposition process, containing ZnO (87%) and CuZ (13%) as crystalline phases. The structure and composition of all composite membranes were elucidated using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. Under UV-visible light irradiation, the Cu2O/ZnO@PET composite displayed enhanced photocatalytic activity, reaching 98% Czm degradation, higher than Cu2O@PET and ZnO@PET composites. The maximum Czm degradation efficiency from aqueous solution was obtained at an optimal pH of 6 and contact time of 140 min. The effects of various parameters such as temperature, catalyst dosage and sample exposure time on the photocatalytic degradation process were studied. The degradation reaction of Czm was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first order kinetic model. The degradation kinetics of Czm accelerated with increasing temperature, and the activation energy (Ea) levels were calculated as 11.9 kJ/mol, 14.22 kJ/mol and 15.82 kJ/mol for Cu2O/ZnO@PET, ZnO@PET and Cu2O@PET composite membranes, respectively. The reusability of the Cu2O/ZnO@PET catalyst was also investigated at different temperatures for 10 consecutive runs, without any activation or regeneration processes. The Cu2O/ZnO@PET composite exhibited degradation efficiency levels of over 50% at 14 °C and over 30% at 52 °C after 5 consecutive uses. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of KazakhstanFunding: The research titled “Development of Functionalized Composite Track-Etched Membranes for Environmental Applications” (grant No AP08855527) was funded by the Ministry of Education and Science of the Republic of Kazakhstan

    The Burden of Disease due to COVID-19 (BoCO-19): A study protocol for a secondary analysis of surveillance data in Southern and Eastern Europe, and Central Asia

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    Introduction The COVID-19 pandemic has had an extensive impact on public health worldwide. However, in many countries burden of disease indicators for COVID-19 have not yet been calculated or used for monitoring. The present study protocol describes an approach developed in the project “The Burden of Disease due to COVID-19. Towards a harmonization of population health metrics for the surveillance of dynamic outbreaks” (BoCO-19). The process of data collection and aggregation across 14 different countries and sub-national regions in Southern and Eastern Europe and Central Asia is described, as well as the methodological approaches used. Materials and methods The study implemented in BoCO-19 is a secondary data analysis, using information from national surveillance systems as part of mandatory reporting on notifiable diseases. A customized data collection template is used to gather aggregated data on population size as well as COVID-19 cases and deaths. Years of life lost (YLL), as one component of the number of Disability Adjusted Life Years (DALY), are calculated as described in a recently proposed COVID-19 disease model (the ‘Burden-EU’ model) for the calculation of DALY. All-cause mortality data are collected for excess mortality sensitivity analyses. For the calculation of Years lived with disability (YLD), the Burden-EU model is adapted based on recent evidence. Because Covid-19 cases vary in terms of disease severity, the possibility and suitability of applying a uniform severity distribution of cases across all countries and sub-national regions will be explored. An approach recently developed for the Global Burden of Disease Study, that considers post-acute consequences of COVID-19, is likely to be adopted. Findings will be compared to explore the quality and usability of the existing data, to identify trends across age-groups and sexes and to formulate recommendations concerning potential improvements in data availability and quality. Discussion BoCO-19 serves as a collaborative platform in order to build international capacity for the calculation of burden of disease indicators, and to support national experts in the analysis and interpretation of country-specific data, including their strengths and weaknesses. Challenges include inherent differences in data collection and reporting systems between countries, as well as assumptions that have to be made during the calculation process.Peer Reviewe

    Living Radical Polymerization by the RAFT Process - A Second Update

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    Patient safety attitudes of health care proffessionals: Aclinical study

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    Sağlık hizmeti sunan örgütler, hizmet sunumunda sürekli iyileştirmeyi hedeflediklerinden hasta güvenliği, sağlık hizmetleri kalitesinin önemli bir bileşeni haline gelmiştir. Bu nedenle hasta güvenliği kültürünün oluşturulması, son yıllarda hizmet sunan örgütlerin gündeminde bulunmaktadır. Sağlık hizmetlerinde ISO belgelendirmesi, sürekli kalite iyileştirme ile toplam kalite yönetimi uygulamalarında ve sağlık sistemlerinde entegrasyonun sağlanmasında önemli bir faktör olarak tanımlanmaktadır. Belgelendirme ve akreditasyon, hataların azaltılmasında önemli role sahiptir. Sağlık hizmeti sunumu sırasında oluşan istenmeyen olumsuz olayların sıklığının azaltılması, sağlık hizmetlerinin güvenirliğini artıracaktır. Hasta güvenliği kültürü, sağlık bakım sisteminin güvenirliğinin bütüncül bir göstergesi olarak ele alındığından bu çalışma, ISO 9001:2000 kalite belgesine sahip bir devlet hastanesinde acil ve yatan hasta servislerinde görev yapan hekim ve hemşireler araştırma kapsamına alınmıştır. Araştırma sonuçları, kliniklerde benimsenen kültürün, hasta güvenliğini desteklediğini göstermektedir.As health care organizations continually aim to improve the public service, patient safety has become critical component of health care quality. Also, there is a growing recognition of the importance of establishing a culture of safety. In health care, ISO certification is identified as an important factor in implementing continuous quality improvement and total quality management and in promoting integration in health care systems. Certification and accreditation has an important role in reducing errors. Minimizing the frequency of adverse events during providing health care services will increase the reliability of health care systems. Because of the fact that patient safety culture enhances the reliability of the health care system as a whole, this research focus on the physicians and nurses at emergency and inpatient departments in a state hospital certified by ISO. The results of the research point out that the culture adopted by clinics support the patient safety
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