Hexavalent chromium is one of the major heavy metals. As the environmental legislation becomes increasingly strict, looking for new technology to treat hexavalent chromium is becoming more and more ...important. In this research, 2-mercaptobenzothiazole was used to blend polyvinylidene fluoride to prepare a modified membrane that could be applied to adsorb and purify water containing hexavalent chromium. The membrane performance was characterized by infrared spectroscopy (Fourier transform infrared spectroscopy) and water contact angle measurements. The experimental results showed that the pure water flux of the membrane was 255.57 l/m2 h, the contact angle was 80.1°, and the adsorption capacity of chromium ion was 241 µg/cm2. The polyvinylidene fluoride-modified membrane presented better adsorption abilities for chromium ion than that of the traditional polyvinylidene fluoride membrane.
Double perovskites Re2CoMnO6 (Re=Sm, Dy) have been synthesized by a solid-state reaction method. Magnetic field-induced metamagnetic behavior is observed in the samples below the ferromagnetic Curie ...temperature (TC), which are respectively 123 K and 88 K in Sm2CoMnO6 and Dy2CoMnO6. The origin of this effect is attributed to the competition between the nearest-neighbor ferromagnetic super-exchange interaction (Co2+-Mn4+) and the next nearest-neighbor antiferromagnetic exchange interaction (Co2+-Co2+, Mn4+-Mn4+). Arrott plots combined with the thermal hysteresis confirm that the transition from ferromagnetic to antiferromagnetic state with negative slope is the first-order magnetic phase transition. Moreover, the positive slope closely to TC indicates that the transition from paramagnetic to ferromagnetic state is the second-order transition. Magnetocaloric effect associated with Maxwell's relation is studied and the maximal value of |ΔSM| is 1.4 and 3.5 J kg−1 K−1 at 6 T near TC for Sm2CoMnO6 and Dy2CoMnO6. The large value of |ΔSM| for Dy2CoMnO6 is obtained which is 9.1 J kg−1 K−1 at 20 K. The relatively smaller magneto entropy change for Sm2CoMnO6 may be attributed to the higher coercive field and the weaker magnetism.
•External filed-induced metamagnetism is observed in Re2CoMnO6 (Re=Sm, Dy) ceramics.•Two types of magnetic transition are observed.•The metamagnetism is closely related to the rare-earth ions.
•The thermal hysteresis existed in Mn0.98CoGe compound recedes even disappears for ball milling different time.•For Mn0.98CoGe compound, the increasing of ball milling time leads to the reduction of ...its crystal sizes.•The magnetic entropy change (ΔSM) decreases and the temperature interval of ΔSM broadens with increasing ball milling time.•The relative cooling powers (RCP) of BM-12 h sample are improved relative to no-milled sample.
The Mn0.98CoGe compound can be as alternative refrigerants due to its low cost and large magentocaloric effect near room temperature. However, the narrow work temperature range and the large thermal hysteresis restrict its application. In this work, we investigate the influence of ball milling (BM) time on the thermal hysteresis and magnetocaloric properties of Mn0.98CoGe compound. Results show that the thermal hysteresis of Mn0.98CoGe reduced markedly after BM 5 h, and disappeared completely after BM 12 h. Furthermore, the magnetic entropy change (ΔSM) over a wider temperature span are observed, which leads to the relative cooling power (RCP) of BM-12 h sample as high as those typical refrigerants.
Since the beginning of the SARS-CoV-2 pandemic, the treatments and management of the deadly COVID-19 disease have made great progress. The strategies for developing novel treatments against COVID-19 ...include antiviral small molecule drugs, cell and gene therapies, immunomodulators, neutralizing antibodies, and combination therapies. Among them, immunomodulators are the most studied treatments. The small molecule antiviral drugs and immunoregulators are expected to be effective against viral variants of SARS-CoV-2 as these drugs target either conservative parts of the virus or common pathways of inflammation. Although the immunoregulators have shown benefits in reducing mortality of cytokine release syndrome (CRS) triggered by SARS-CoV-2 infections, extensive investigations on this class of treatment to launch novel therapies that substantially improve efficacy and reduce side effects are still warranted. Moreover, great challenges have emerged as the SARS-CoV-2 virus quickly, frequently, and continuously evolved. This review provides an update and summarizes the recent advances in the treatment of COVID-19 and in particular emphasized the strategies in managing CRS triggered by SARS-CoV-2. A brief perspective in the battle against the deadly disease was also provided.
NiCr2O4 nanoparticles have been successfully prepared by chemical co-precipitation method. Desired crystallographic phase of NiCr2O4 is confirmed by analyzing x-ray diffractrograms. With increasing ...annealing temperature, crystal transition from cubic to tetragonal phase is observed. The increasing average particle size from ∼80 to ∼280 nm is studied by SEM and TEM micrographs as annealing temperature increases. Exchange bias behavior is detected at 10 K accompanied by the shift of magnetic hysteresis loops along field axis. This effect is gradually weakening as annealing temperature increases. The magnetization depending on temperature under zero-field-cooled and field-cooled conditions suggests the ferrimagnetic transition at ∼72 K and the spiral magnetic order at ∼25 K. Furthermore, the ferrimagnetic transition point shifts slightly to low temperature with increasing annealing temperature. Based on the measurement results, the appearance and evolution of exchange bias effect in NiCr2O4 nanoparticles with improving annealing temperature should be simultaneously derived from the lattice transition and the surface spin effects.
•Annealing temperature evidently affects the microstructure and magnetism of NiCr2O4 nanoparticles.•Increasing annealing temperature results in crystal transition from cubic to tetragonal phase.•Increasing average particle size from ∼80 to ∼280 nm is observed as annealing temperature increases.•Magnetic behavior is regulated by crystal transition and particle size due to annealing temperature.
The lead-free (1-x)Bi4Ti3O12/xBi4.5K0.5Ti4O15 composites (x = 0–0.4) have been synthesized by solid state reaction method. Evolution of microstructure and electric properties has been investigated ...with varying composition ratio. X-ray diffraction, Raman and IR absorption confirm the crystal transition tendency from orthorhombic to tetragonal phase. Evident texture along c-axis crystallographic orientation is observed in structure and morphology characteristics with x = 0.05 and 0.1. Through modulating the mole ratio of Bi4.5K0.5Ti4O15, coexistence of ferroelectric order and relaxor state is verified by the variation of ferroelectric hysteresis loops and polarization current density. This behavior can be attributed to the uncertain stability of discernable ferroelectric order induced by electric field among polar nanoregions during symmetry distoration. Temperature dependence of dielectric properties suggests an excellent thermal stability during a wide temperature range. Moreover, the detailed dielectric mechanism has been analyzed via various methods. Electrical conduction in grains and grain boundaries respectively plays the different role during the varying temperature process.
•(1-x)Bi4Ti3O12/xBi4.5K0.5Ti4O15 (x = 0–0.4) are synthesized by solid state reaction.•Crystal transition from orthorhombic to tetragonal phase can be observed.•Electric properties show a coexistence of ferroelectric order and relaxor state.•Electric response exhibits mixed conductivity mechanisms for varying temperature.
•Large dielectric constant is obtained in single phase NiCr2O4 at room temperature.•Dielectric relaxation behavior is confirmed at wide temperature range in NiCr2O4.•Evident magnetodielectric ...coupling is observed at the temperature range of 80–300 K.
Single phase NiCr2O4 has been successfully prepared by sol–gel technique. Characterization of crystal and morphology exhibits the tetragonal structure and homogeneous growth with regular crystalline shape. Large dielectric constant of ~2447 is observed at room temperature. The relaxation behavior below room temperature is confirmed through measurements of dielectric constant, dielectric loss, electric modulus and impedance depended on frequency or temperature. The analysis through equivalent circuit simulation demonstrates the influence of grains at low temperature and the common contribution of grains and grain boundaries at high temperature. Moreover, the change in dielectric response indicates the presence of magnetodielectric coupling effect. Two different mechanisms are considered to control the magnetodielectric coupling, yielding the positive and negative coupling coefficient at different temperature ranges. The intrinsic magnetoelectric coupling gives rise to the frequency independent magnetodielectric behavior at low temperature. As temperature increases above 150 K, the large magnetodielectric coupling coefficient depended on frequency is contributed by the Maxwell-Wagner effect. The negative value of magnetodielectric coupling coefficient is attributed to the leakage current. Therefore, both mechanisms of Maxwell-Wagner and leakage are competing as a function of frequency, which results in the coefficient crossover at room temperature. Such features bring NiCr2O4 a step closer to potential applications in areas such as magnetic field sensors, actuators and others.
By using nanoindentation techniques combined with transmission electron microscope, wide-/small-angle X-ray scattering, and three-dimensional atom probe tomography, the sub-nanometer- to ...nanometer-length-scale structural heterogeneity due to the precipitation of Co(Fe)-rich clusters was observed in (Co0.7Fe0.3)0.68B0.219Si0.051Nb0.05100-xCux (x = 0.5) metallic glasses. Such short-range ordered structure promotes energy dissipation during deformation via regulating intrinsic elastic constants and hardness at the mesoscale, which contributes to the improved compressive plasticity of Cu-doped (Fe, Co)-based metallic glasses. Our work provides new evidence on atomic-scale heterogeneity in Cu-doped metallic glasses from the aspects of topological orders and microscopic mechanical responses.
•A significant hierarchical structural heterogeneity in the range from several angstroms to dozens of nanometers was observed in the Cu-doped Co(Fe)-based metallic glasses for the first time.•These atomic-scale topological orders are introduced by the positive mixing enthalpy between Cu and Co(Fe), which lead to the mechanical inhomogeneity with characteristic lengths of tens of microns.•This mechanical heterogeneity together with a hierarchical heterogeneity at the multi-scale, contributes to the improved compressive plasticity of the Cu-doped ferromagnetic glassy alloys via dissipating more energy during deformation.
•Increased dielectric constant with low loss is observed in studied samples.•Ferromagnetic properties are dependent on the annealing temperature.•Magnetoelectric coupling effect are strongly ...dependent on annealing temperature.
Multiferroic 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 ceramics were prepared by sol-gel method with various temperatures ranging from 950 to 1100 °C. The influence of annealing temperature on structure, morphology, dielectric, magnetic and magnetoelectric coupling effect was investigated. The refinement of x-ray diffraction data and the thermogravimetric-differential thermal analysis indicated the coexistence of perovskite and spinel phases with annealing temperature above 950 °C. Increasing grain size in surface morphology measurement was closely related to the increasing annealing temperature. Enhancement in dielectric properties was observed with increasing annealing temperature. The room-temperature ferromagnetic properties were also detected with saturated magnetic hysteresis loops under different annealing temperatures. Finally, magnetoelectric coupling effect was confirmed in the samples. The possible factors for room-temperature multiferroic properties were discussed with increasing annealing temperature. This study showed that annealing temperature could evidently affect the multiferroic properties in 0.7Bi0.5Na0.5TiO3-0.3NiFe2O4 solid solution.
The impact of dietary alpha-tocopherol on juvenile Chinese mitten crab Eriocheir sinensis was experimentally evaluated in a 10-week study. Crab were fed with nine diets including three levels of ...alpha-tocopherol (0, 100 and 300 mg kg-1 diet) and three levels of fish oil oxidation (fresh, moderate and high) in triplicates. Fresh and moderate oil oxidization enhanced weight gain, but moderate and high oil oxidization lowered survival and feed efficiency. The 100-mg alpha-tocopherol kg-1 diet resulted in higher hepatopancreas MDA than other alpha-tocopherol diets. High oil oxidization led to the lowest serum superoxide dismutase (SOD) and glutathione peroxidase (GPH-PX). The serum SOD and GPH-PX activities in crab fed 100 mg alpha-tocopherol were higher than in those fed other alpha-tocopherol diets. The diet without alpha-tocopherol addition lowered lysozyme and phenoloxidase (PO) activities compared to other alpha-tocopherol diets. Fresh fish oil diet increased PO activity compared to oxidized oils. High oil oxidization caused significantly more mortality than fresh or moderate oxidization after 7-d postchallenge with Aeromonas hydrophila. Supplementation with alpha-tocopherol significantly enhanced resistance to bacterial infection. This study indicates that alpha-tocopherol can protect lipid from peroxidation and enhance disease resistance.
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