The preparation of calcium carbonate whiskers by gas‐liquid contact method using low‐grade dolomite refining solution and CO2 as raw materials has attracted widespread attention. The effects of ...reaction temperature, Mg2+ concentration and pH value on the morphology, particle size, aspect ratio and crystal form of CaCO3（Calcium carbonate） whiskers are investigated in detail. SEM (Scanning Electron Microscope) and XRD (X‐ray powder diffraction) are combined to analyze the calcium carbonate whiskers. The results demonstrated that under the conditions such as 100 °C, Mg2+ concentration of 0.05 mol L−1 and pH value of 9.5, calcium carbonate whiskers with uniform distribution, aspect ratio of 15–20, and purity of 99.38% can be prepared. Through Material Studios simulation software and critical nucleation energy analysis, it is confirmed that the morphology of calcium carbonate whiskers emerged to be a long hexagonal prism. Mg2+ in the refined solution would adhere to the surface of calcium carbonate during carbonization, inhibit the formation of calcite phase, and promote the growth of face clusters connected by vertex angles between CaCO3 crystals. The initial pH condition determines the solubility of CO32− and the supersaturation of the solution, which in turn affected the formed calcium carbonate crystal form.
The SEM image in the above figure shows that the calcium carbonate whisker is a long hexagonal prism octahedron structure, and the Morphology module of Materials Studio simulation software predicts that the growth of (111) (221) (112) crystal plane tends to be hexagonal prisms, and the growth morphology of (021), (012), (041) and (130) crystal plane is long rhombohedral columnar whiskers. This shows that the morphology of calcium carbonate whiskers is consistent with the predicted structure of Materials Studio simulation software, which makes it more reliable to judge the morphology of calcium carbonate whiskers by the diffraction peak intensity of each crystal plane of XRD pattern.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Densities and viscosities of four ternary mixtures made from heptane, octane, nonane, and hexyl benzene were measured. The temperature ranged from 293.15 K to 313.15 K. The experimental viscosities ...of the four pure hydrocarbons and their ternary mixtures vs temperature were fitted to the Andrade equation with an average absolute deviation of 0.13 %. On the basis of these data, the excess molar volumes and viscosity deviations were calculated. The prediction results based on the Przezdiecki−Sridhar method and the Sastri−Rao method for low-temperature liquid viscosity estimation, the Dymond−Assael hard sphere model, and an equation of state based viscosity model proposed by Fan and Wang were compared with the experimental data.
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IJS, KILJ, NUK, PNG, UL, UM
The reaction that synthesis of dichlorophenylp-hosphine over the catalyst HZSM-5 zeolite catalyst in the gas phase was studied as the target. The deactivation and regeneration characteristics of ...HZSM-5 catalyst were studied by N2 adsorption-desorption, scanning electron microscopy (SEM), X-Ray diffraction, FT-IR, TG-DTG tests. The results revealed that the structure of HZSM-5 zeolite scarcely damaged in the catalyst deactivation and regeneration process. It was found that both coke deposition and local dealumination of tetrahedral framework aluminum were the crucial factors in the deactivation of HZSM-5. Due to the coke forming on the catalyst surface and dealumination , the pore mouth of zeolite channels were blocked. The coke consisted mainly of aromatic compounds which from product depth oxidation. Regeneration of HZSM-5 catalyst had high activity and stability for the target reaction.
The effect of vanadium carbide（VC） on the grain size of commercial pure aluminum was experimentally investigated by varying the content of VC, the holding time, and casting temperature. The refining ...efficiencies of VC and Al5Ti1 B were also compared. The refined samples of commercial pure aluminum were examined using optical microscopy, scanning electron microscopy（SEM） and energy-dispersive spectroscopy（EDS）. The results suggest that VC is a good refiner of commercial pure aluminum. The addition of only 0.3wt% VC can decrease the grain size of aluminum to 102 μm, whereas the casting temperature and holding time have little effect on the grain size. The refining efficiency of VC is better than that of Al5Ti1 B. The VC particles in molten aluminum act as nuclei and the grain refinement of aluminum alloys by VC particles is achieved via heterogeneous nucleation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effect of vanadium carbide(VC) on the grain size of commercial pure aluminum was experimentally investigated by varying the content of VC, the holding time, and casting temperature. The refining ...efficiencies of VC and Al5Ti1 B were also compared. The refined samples of commercial pure aluminum were examined using optical microscopy, scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS). The results suggest that VC is a good refiner of commercial pure aluminum. The addition of only 0.3wt% VC can decrease the grain size of aluminum to 102 μm, whereas the casting temperature and holding time have little effect on the grain size. The refining efficiency of VC is better than that of Al5Ti1 B. The VC particles in molten aluminum act as nuclei and the grain refinement of aluminum alloys by VC particles is achieved via heterogeneous nucleation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
AIM： To investigate contrast-enhanced ultrasound （CEUS） for early diagnosis of postoperative vascular complications after right-lobe living donor liver transplantation （RLDLT）. METHODS： The ...ultrasonography results of 172 patients who underwent RLDLT in West China Hospital, Sichuan University from January 2005 to June 2008 were analyzed retrospectively. Among these 172 patients, 16 patients＇ hepatic artery flow and two patients＇ portal vein flow was not observed by Doppler ultrasound, and 10 patients＇ bridging vein flow was not shown by Doppler ultrasound and there was a regional inhomogeneous echo in the liver parenchyma upon 2D ultrasound. Thus, CEUS examination was performed in these 28 patients. RESULTS： Among the 16 patients without hepatic artery flow at Doppler ultrasound, CEUS showed nine cases of slender hepatic artery, six of hepatic arterial thrombosis that was confirmed by digital subtraction angiography and/or surgery, and one of hepatic arterial occlusion with formation of lateral branches. Among the two patients without portal vein flow at Doppler ultrasound, CEUS showed one case of hematoma compression and one of portal vein thrombosis,and both were confirmed by surgery. Among the 10 patients without bridging vein flow and with liver parenchyma inhomogeneous echo, CEUS showed regionally poor perfusion in the inhomogeneous area, two of which were confirmed by enhanced computed tomography （CT）, but no more additional information about bridging vein flow was provided by enhanced CT. CONCLUSION： CEUS may be a new approach for early diagnosis of postoperative vascular complications after RLDLT, and it can be performed at the bedside.
Summary： Human sperm DNA is an important genetic and epigenetic material, whose chromatin structure differs from that of somatic cells. As such, conventional methods for DNA extraction of somatic ...cells may not be suitable for obtaining sperm DNA. In this study, we evaluated and compared three sperm DNA extraction techniques, namely, modified guanidinium thiocyanate method （method A）, traditional phenol-chloroform method （method B）, and TianGen kit method （method C）. Spectrophotometry and agarose gel electrophoresis analyses showed that method A produced DNA with higher quantity and purity than those of methods B and C （P〈0.01）. PCR results revealed that method A was more reliable in amplifying DEAD-box polypeptide 4 （DDX4） and copy number variations （CNVs） than methods B and C, which generated false-positive errors. The results of sperm DNA methylation assay further indicated that methods A and B were effective, and the former yielded higher quantitative accuracy. In conclusion, the modified guanidinium thiocyanate method provided high quality and reli- able results and could be an optimal technique for extracting sperm DNA for methylation assay.
•Remote sensing based water occurrence methods can accurately delineate DCNs.•Time-series Landsat images analysis can efficiently track DCNs morphodynamics.•The quantitative framework integrating ...remote sensing and GIS can facilitate river delta mangement.
Delta channel networks (DCNs) are highly complex and dynamic systems that are governed by natural and anthropogenic perturbations. Challenges remain in quickly quantifying the length, width, migration, and pattern changes of deltaic channels accurately and with a high frequency. Here, we develop a quantitative framework, which introduces a water occurrence algorithm based on Landsat time-series data and spatial morphological delineation methods, in order to measure DCN structures and associated changes. In examining the Pearl River Delta (PRD) and Irrawaddy River Delta (IRD) as case studies, we analyze their conditions and trends between 1986 and 2018 at ten-year intervals. Both study areas have undergone various human interventions, including dam construction, sand mining, and land use change driven by urbanization. Our results show the following: (1) the use of a 0.5 water occurrence extraction based on Landsat time-series data, morphological delineation, and spatial change analysis methods can quantify the morphodynamics of DCNs effectively with a root-mean-square error of 15.1 m; (2) there was no evident channel migration in either PRD or IRD with average channel widths of 387.6 and 300.9 m, respectively. Most channels in the PRD underwent remarkable shrinkage, with average rates of 0.4–6.4 m/year, while there were only slight changes in the IRD, which is consistent with observed trends in sediment load variation. The results of this research have the potential to contribute to sustainable river management in terms of flood prevention, riparian tideland reclamation, and water and sediment regulation. Moreover, the proposed framework can be used to develop a new global delta channel network dataset and can be generalized to remotely sensed water discharge and river depth estimation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Identified ecological change capture based on dense Landsat data.•Analysed mutation and long-term and recent changes in the ecological status of Ramsar sites in time series data.•Ecological status ...deteriorated from 1986 to 2021 in more than half of China's Ramsar sites.
Wetlands are globally critical for human survival and Earth's sustainable development. However, wetlands are experiencing rapid degradation and loss due to pollution, reclamation, climate change, invasions, etc. Ramsar sites are globally recognized as wetland hotspots that have been designated Wetlands of International Importance under the Ramsar Convention. However, the long-term trends of change that affect these sites remain unclear. This study explored the ecological changes and characteristics of Ramsar sites using 7 ecological indicators from three aspects: vegetation status, hydrological dynamics and anthropogenic disturbance, with the support of 36-year dense Landsat imagery and the trend and mutation analysis algorithms of Theil-Sen and BreakoutDetection. The results showed that (1) for the long-term trend, the ecological status of 55% of China's Ramsar sites experienced a trend of degradation, and the remaining Ramsar sites showed a trend of restoration in the past 36 years. (2) After the mutation was analysed, 47% of the Ramsar sites showed an environmental and ecological improvement trend in the recent period. (3) More than 50% of Ramsar sites were found to have ecological reversals in vegetation status and hydrological dynamics in the past 36 years.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Mixed cellulose ester (MCE) separator is applied to tailor the zinc deposition in AZBs based on physical and chemical effect.•The physical shunting effect by the uniform and dense ...pore structure can control and homogenize the ion movement.•The mechanism of physical pore effect is illuminated by comparing MCE membranes with similar component but different pore size.•The chemical guiding effect for ion diffusion is realized by the coordination between polar functional groups in MCE and Zn2+.
Aqueous zinc-ion batteries (AZBs) with high energy density, low cost and environmental characteristics, have become the promising device for energy storage. However, uncontrolled zinc dendrite growth remains an impediment to the popularization of AZBs. The unrestricted two-dimensional (2D) ions diffusion is the main cause of the above defect. In this work, mixed cellulose ester (MCE) membrane is proposed as the separator. A dense homogeneous pore structure can achieve a physical shunting effect on ion diffusion, which can control and homogenize the ion motion. Further, the mechanism of this physical pore effect is confirmed by comparing the behavior of Zn deposition in MCE systems with different pore sizes but the same composition. As conjectured, a membrane with a smaller pore size is more favorable. In addition, the MCE contains many polar oxygen-containing functional groups that can facilitate and modulate ion diffusion through coordination. This chemical ion guiding effect, together with the above physical pore effect, gives the separator the ability to suppress dendrite formation. Zn/Zn symmetric cells with this membrane exhibit ultralong cycle life exceeding 1250 h at 0.5 mA cm−2 and 1000 h at 5 mA cm−2. And the Zn//MnO2 battery presents excellent cycle stability for more than 500 cycles with a capacity retention of 90.67%. This work proposes MCE separators and reveals their coordinated regulation of physical and chemical effects on metal-based anodes. This will shed light on the development of high-performance separators and AZBs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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