Exploring fully heavy scalar tetraquarks QQQ‾Q‾QQ\overline{Q}\overline{Q}

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

Decays of fully beauty scalar tetraquarks to BqB‾qB_{q}\overline{B}_{q} and Bq∗B‾q∗B_{q}^{\ast}\overline{B}_{q}^{\ast} mesons

Decays of the fully beauty four-quark structures $X_{\mathrm{4b}}$ and $T_{ \mathrm{4b}}$ to $B$ meson pairs are investigated in the framework of QCD three-point sum rule method. We model the scalar exotic mesons $X_{\mathrm{4b }}$ and $T_{\mathrm{4b}}$ as diquark-antidiquark systems composed of the axial-vector and pseudoscalar diquarks, respectively. The masses $m=(18540 \pm 50)~\mathrm{MeV}$ and $\widetilde{m}=(18858 \pm 50)~\mathrm{MeV}$ of these compounds calculated in our previous articles, fix possible decay channels of these particles. In the present work, we consider their decays to $B_{q}\overline{B}_{q}$ and $B_{q}^{\ast }\overline{B}_{q}^{\ast } (q=u,d,s,c)$ mesons. In the case of $X_{\mathrm{4b}}$ the mass of which is below the $2\eta_{b}$ threshold, these channels determine essential part of its full width $\Gamma_{\mathrm{4b}}$. The tetraquark $T_{\mathrm{4b}}$ can decay to the pair $\eta_{b}\eta_{b}$, therefore partial widths of processes with $B (B^{\ast})$ mesons in the final state permit us to refine our estimate for the full width of this particle. The predictions $\Gamma_{ \mathrm{4b}}=(9.6\pm 1.1)~\mathrm{MeV}$ and $\widetilde{\Gamma }_{\mathrm{4b} }^{\mathrm{Full}}=(144 \pm 29)~\mathrm{MeV}$ obtained in this article can be used in future experimental investigations of four $b$-quark mesons.Comment: 9 Pages, 3 Figures and 1 Tabl

Scalar exotic mesons bbc‾c‾bb\overline{c}\overline{c}

Properties of doubly charged scalar tetraquarks $bb\overline{c}\overline{c}$ are investigated in the framework of the QCD sum rule method. We model them as diquark-antidiquark states $X_{\mathrm{1}}$ and $X_{\mathrm{2}}$ built of axial-vector and pseudoscalar diquarks, respectively. The masses and current couplings of these particles are computed using the QCD two-point sum rule method. Results $m_{1}=(12715 \pm 80)~\mathrm{MeV}$ and $m_{2}=(13370 \pm 95)~\mathrm{MeV}$ obtained for the masses of these particles are used to determine their kinematically allowed decay modes. The full width $\Gamma_{ \mathrm{1}}$ of the state $X_{\mathrm{1}}$ is evaluated by taking into account its strong decays to mesons $2B_{c}^{-}$, and $2B_{c}^{\ast -}$. The processes $X_{\mathrm{2}} \to 2B_{c}^{-}$, $2B_{c}^{\ast -}$ and $B_{c}^{-}B_{c}^{-}(2S)$ are employed to estimate $\Gamma_{\mathrm{2}}$. Predictions obtained for the full widths $\Gamma_{\mathrm{1}}=(63 \pm 12)~ \mathrm{MeV}$ and $\Gamma_{\mathrm{2}}=(79 \pm 14)~\mathrm{MeV}$ of these structures and their masses may be utilized in experimental studies of fully heavy resonances.Comment: 12 Pages and 4 Figure

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

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

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

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

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

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

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

e-Beam and γ-rays Induced Synthesis and Catalytic Properties of Copper Nanoclusters-Deposited Composite Track-Etched Membranes

Effective removal of toxic inorganic and organic pollutants is one of the current leading challenges of wastewater treatment. In this study, the decomposition of methylene blue (MB) under UV light irradiation was investigated in the presence of copper nanoclusters (NCs)-deposited polyethylene terephthalate (PET) track-etched hybrid membranes. PET track-etched membranes (TeMs) with an average pore size of ~400 nm were grafted by functional acrylic acid (AA) monomer under electron beam irradiation after oxidation with H2O2/UV system. The radiation dose varied between 46 and 200 kGy. For the deposition of copper NCs, poly(acrylic acid) (PAA)-grafted membranes saturated with Cu(II) ions were irradiated either by electron beam or γ-rays to obtain copper-based NCs for the catalytic degradation of MB. Irradiation to 100 kGy with accelerated electrons resulted in the formation of small and uniform copper hydroxide (Cu(OH)2) nanoparticles homogeneously distributed over the entire volume of the template. On the other hand, irradiation under γ-rays yielded composites with copper NCs with a high degree of crystallinity. However, the size of the deposited NCs obtained by γ-irradiation was not uniform. Nanoparticles with the highest uniformity were obtained at 150 kGy dose. Detailed analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the loading of copper nanoparticles with an average size of 100 nm on the inner walls of nanochannels and on the surface of PET TeMs. Under UV light irradiation, composite membranes loaded with NCs exhibited high photocatalytic activity. It was determined that the highest catalytic activity was observed in the presence of Cu(OH)2@PET-g-PAA membrane obtained at 250 kGy. More than 91.9% of the initial dye was degraded when this hybrid membrane was employed for 180 min, while only 83.9% of MB was degraded under UV light using Cu@PET-g-PAA membrane. Cu(OH)2@PET-g-PAA membranes obtained under electron beam irradiation demonstrated a higher photocatalytic activity compared to Cu@PET-g-PAA membranes attained by γ-rays. © 2023 by the authors.International Atomic Energy Agency, IAEA: F22070The research project titled “Radiation induced and template synthesis of the photocatalytically active ion-track membrane composites” (contract #23152) was funded the International Atomic Energy Agency (IAEA) under coordinated research project F22070 (IAEA Research Contract No: 23152)