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12,438 result(s) for "Ma, W. H."
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Soil organic carbon in the Sanjiang Plain of China: storage, distribution and controlling factors
The accurate estimation of soil organic carbon (SOC) storage and determination of its pattern-controlling factors is critical to understanding the ecosystem carbon cycle and ensuring ecological security. The Sanjiang Plain, an important grain production base in China, is typical of ecosystems, yet its SOC storage and pattern has not been fully investigated because of insufficient soil investigation. In this study, 419 soil samples obtained in 2012 for each of the three soil depth ranges 0–30, 30–60, and 60–100 cm and a geostatistical method are used to estimate the total SOC storage and density (SOCD) of this region. The results give rise to 2.32 Pg C for the SOC storage and 21.20 kg m−2 for SOCD, which is higher than the mean value for the whole country. The SOCD shows notable changes in lateral and vertical distribution. In addition, vegetation, climate, and soil texture, as well as agricultural activities, are demonstrated to have remarkable impacts on the variation in SOCD of this region. Soil texture has stronger impacts on the distribution of SOCD than climate in the Sanjiang Plain. Specifically, clay content can explain the largest proportion of the SOC variations (21.2% in the top 30 cm) and is the most dominant environmental controlling factor. Additionally, the effects of both climate and soil texture on SOCD show a weakening with increasing soil layer depth. This study indicates that reducing the loss of SOC requires effective conservation and restoration efforts of wetlands and forestlands, as well as sensible fertilization. The results from this study provide the most up-to-date knowledge on the storage and pattern of SOC in the Sanjiang Plain and have important implications for the determination of ecosystem carbon budgets and understanding ecosystem services.
Recovery of Li, Mn, and Fe from LiFePO4/LiMn2O4 mixed waste lithium-ion battery cathode materials
The recovery of metals from the cathode material or used lithium-ion batteries is of both environmental and economic importance. In this study, stepwise precipitation by acid leaching was used to separate and recover lithium, iron, and manganese from the mixed LiFePO4/LiMn2O4 cathode material. The thermodynamic properties of the lithium, iron, and manganese metal phases, especially the stability range, were analyzed using Eh-pH diagrams. The leaching system with sulfuric acid and hydrogen peroxide released Fe3+, Mn2+, and Li+ ions from the cathode material. Fe3+ in the leaching solution was precipitated as Fe(OH)3 and finally recovered as Fe2O3 after calcination. Mn2+ in the leaching solution was recovered as MnCO3. The remaining Li+-rich solution was evaporated and crystallized into Li2CO3. The purity of the recycled MnCO3 and Li2CO3 met the standard of cathode materials for lithium-ion batteries. XRD and XPS analysis showed that the main phase in the leaching residue was FePO4. This process can be used to separate and recover metals from mixed waste lithium-ion battery cathode materials, and it also provides raw materials for the preparation of lithium-ion battery cathode materials.
Study on the behavior of impurity removal from lithium-iron-phosphate slag using the ultrasonic-assisted sulphuric acid leaching
The recovery of iron phosphate from the leaching slag of used lithium iron phosphate cathode materials is a crucial step to achieve closed-loop recovery of lithium iron phosphate, which has not yet been effectively accomplished. In the study, ultrasonic-assisted sulfuric acid leaching was used to remove impurities in the iron phosphate, to meet the stringent impurity content requirements for battery-grade iron phosphate regarding impurity content. Optimization of leaching conditions involved a sulfuric acid concentration of 0.2 mol?L-1, acid-leaching time of 30 min, power of 50 W, and reaction temperature of 80?. Under these conditions, the removal efficiencies of Cr, Cu, Ni, and Zn in iron phosphate were 26.09%, 83.0%, 75.9%, and 96.3%, respectively. Simultaneously, the content of impurity elements Cr and Zn concurred with the standard for battery-grade iron phosphate (HG/T 4701-2021), with both 50 ppm and 10 ppm contents. The leaching results indicated the effectiveness of ultrasound in enhancing the removal of impurity elements in iron phosphate within a sulfuric acid solution. Further analyses, including XRD, particle size, TEM, and XPS indicated that the surface of the iron phosphate particles cavitated after ultrasonic acid leaching, resulting in the formation of numerous pores. Additionally, particle collisions led to a reduction in particle size, with no generation of by-products during the process. This innovative approach not only contributed to the removal of impurity elements but also provided insights into the reuse of leaching slag (iron phosphate) and offered guidance for the recovery of metals from waste lithium iron phosphate cathode materials.
Experimental determination of activity interaction coefficients of components in Si-B-Fe and Si-B-Al ternary systems at 1723 K
The interactions among impurity components in Si-based solution are the important thermodynamic parameters for the purification of silicon materials. A ?same concentration? method was used to determine the activity interaction coefficients of Fe to B and Al to B in the silicon solution. Fe and Al were respectively dissolved into the binary Si-B solution at 1723 K with the holding time of 5 h, 7 h, 9 h, and 11 h. The equilibrium concentrations of Fe, B in the Si-B-Fe system and Al, B in the Si-B-Al system were determined. The interaction coefficients of Fe to B and Al to B were obtained by fitting the solubility data of B, Fe, and Al. The solubility relationships between B and [%Fe], and between B and [%Al] were obtained, respectively. It was found by the SEM and EPMA pictures of the samples that the third component Fe or Al added to the binary Si-B solution was alloyed, which verifies the accuracy of the experimental determination results. The significance of the activity interaction coefficient of B on boron removal from industrial silicon was analyzed. nema
Down-regulation of BTG3 promotes cell proliferation, migration and invasion and predicts survival in gastric cancer
Background Gastric cancer (GC) is one of the most common malignancies in China. B-cell translocation gene 3 (BTG3) has been identified as a tumor suppressor in several tumors, but its role in GC remains unknown. This study aimed to detect the expression of BTG3 and its prognostic value in GC tissues and determine its function in the progression of GC. Methodology The expression of BTG3 was detected in GC cell lines and tissues by real-time RT-PCR, Western blot or immunohistochemistry. A series of in vitro and in vivo assays were performed to evaluate the effect of BTG3 on proliferation, migration and invasion of GC cells. Results B-cell translocation gene 3 was obviously down-regulated in GC tissues. Its expression was positively correlated with distant metastasis ( P  < 0.05). Patients with lower BTG3 expression had shorter overall survival time ( P  = 0.015). BTG3 suppressed the proliferation of GC cells in vitro and in vivo. It also inhibited migration and invasion of GC cells in vitro. Conclusion Down-regulation of BTG3 is closely associated with proliferation, migration and invasion in GC. It may be a novel prognostic biomarker for GC patients.
18FFluorodeoxyglucose Positron Emission Tomography/Computed Tomography Findings in Anti–Gamma-Aminobutyric Acid B Receptor Encephalitis: A Case Report
Magnetic resonance imaging of the brain 4 days afteradmission. (a) T1-weighted image with contrast demonstratingan enhancing left frontal lobe lesion likely representing a tumour(arrow). (b) Coronal fluid-attenuated inversion recovery imagedemonstrating slightly increased signal at the right hippocampus(arrowhead) suspected to be related to convulsion. [...]the clinical outcome for patients with anti-GABAB receptor encephalitis and underlying small-cell lung carcinoma is dictated by successful treatment of the tumour. Brain 18F-FDG PET for the diagnosis of autoimmune encephalitis: a systematic review and a meta-analysis.
Thymosin beta-4 upregulates anti-oxidative enzymes and protects human cornea epithelial cells against oxidative damage
Background:The ability to scavenge reactive oxygen species (ROS) is crucial for cornea epithelial cells to resist oxidative damage. The authors previously demonstrated that exogenous thymosin beta-4 (Tβ4) was able to protect human cornea epithelial (HCE-T) cells against H2O2-induced oxidative damage, and its cellular internalisation was essential. The aim of this study is to further elucidate its protective mechanism.Methods:HCE-T cells with or without Tβ4 pretreatment were exposed to H2O2, and the differences in caspase activity, intracellular ROS levels, cell viability, and the expression of anti-oxidative enzymes, were measured and compared.Results:Besides reducing caspase-9 activation and intracellular ROS levels induced by H2O2, treatment of Tβ4 could also increase cell viability and stimulate the expression of manganese superoxide dismutase (SOD) and copper/zinc SOD. Moreover, both transcription and translation levels of catalase were also upregulated by Tβ4 in the presence of exogenous H2O2. Furthermore, it was demonstrated that the addition of catalase inhibitor abrogated the protective effect of Tβ4 against H2O2-induced oxidative damage.Conclusion:To the best of the authors' knowledge, this is the first report to show that Tβ4 was capable of upregulating anti-oxidative enzymes in human corneal epithelial cells, and these findings further support its role in cornea protection.
Thermodynamic properties of iron, aluminum, boron and phosphorus in dilute silicon solutions by molecular interaction volume model
The thermodynamic properties of impurity components in silicon solutions play an important role in the chemical removal process to the metallurgical route. In this paper, the component activity coefficients and interaction parameters of dilute silicon solutions were estimated by the molecular interaction volume model (MIVM). The activity coefficients (?i) of component i in dilute binary Si-i and ternary Si-i-j solutions at 1687-1873 K were firstly calculated. The concentration dependences of the interaction parameter and activity coefficient were also obtained. The self-interaction parameters (?i,i) for Si-i system were obtained as ?B,B= -2.728-362.031/T, ?Al,Al = 2.157-1876.776/T, ?Fe,Fe= -4.842+14445.926/T and ?P,P = -2.543+13767.036/T. At the same time, the interaction parameters among components B, Al, and Fe in dilute ternary Sii- j solutions were also derived as ?Fe,B=-1.2758-2946.306/T, ?Al,B = 0.7467-9765.9298/T and ?Fe,Al= -1.39677+3319.6803/T. Most important of all, the temperature dependences of the interaction parameters and activity coefficients in dilute Si-i and Si-i-j solutions with a certain i or j concentration were deduced. The results show that the predicted self-interaction parameters of B, Al, Fe, and P in binary silicon solutions reasonably agree with the experimental data. This further shows that MIVM is of reliability and can be expanded to a multi-component dilute silicon solution. nema
A comparative study of the five-repetition sit-to-stand test and the 30-second sit-to-stand test to assess exercise tolerance in COPD patients
The sit-to-stand test (STST) has been used to evaluate the exercise tolerance of patients with COPD. However, mutual comparisons to predict poor exercise tolerance have been hindered by the variety of STST modes used in previous studies, which also did not consider patients' subjective perceptions of different STST modes. Our aim was to compare the five-repetition sit-to-stand test (5STS) with the 30-second sit-to-stand test (30STS) for predicting poor performance in the six-minute walking test and to evaluate patients' subjective perceptions to determine the optimal mode for clinical practice. Patients with stable COPD performed 5STS, 30STS and the 6MWT and then evaluated their feelings about the two STST modes by Borg dyspnea score and a questionnaire. Moreover, we collected data through the pulmonary function test, mMRC dyspnea score, COPD assessment test and quadriceps muscle strength (QMS). A receiver operating characteristic curve analysis of the 5STS and 30STS results was used to predict 6-minute walk distance (6MWD) <350 m. The final analysis included 128 patients. Similar moderate correlations were observed between 6MWT and 5STS ( =-0.508, <0.001) and between 6MWT and 30STS ( =0.528, <0.001), and there were similar correlations between QMS and 5STS ( =-0.401, <0.001) and between QMS and 30STS ( =0.398, <0.001). The 5STS and 30STS score cutoffs produced sensitivity, specificity and positive and negative predictive values of 76.0%, 62.8%, 56.7% and 80.3% (5STS) and 62.0%, 75.0%, 62.0% and 75.0% (30STS), respectively, for predicting poor 6MWT performance. The 5STS exhibited obvious superiority in terms of the completion rate and the subjective feelings of the participants. As a primary screening test for predicting poor 6MWD, the 5STS is similar to the 30STS in terms of sensitivity and specificity, but the 5STS has a better patient experience.
On the Equivalent Position Workspace for a Coal Gangue Picking Robot
Coal gangue separation is of key important for green mining. Robotic separation of coal and gangue based on the machine vision system, which is called a coal gangue picking robot with a gangue grab driven by four cables, is developed in this study. Here, this paper focuses on the equivalent position workspace, within which a coal gangue picking robot possesses the identical stability, to find out any more information about the structural stability for a coal gangue picking robot. First, the kinematic and kinetostatic models of the coal gangue picking robot are presented for analyzing the effects of it on the structural stability for the coal gangue picking robot. And moreover, a non-iterative polynomial-based optimization algorithm with the proper optimal objective function is presented based on the convex optimization theory, in which the cable with the minimum cable tension at any pose is determined. Then, three position performance indices are proposed to show the important effects on the structural stability for the coal gangue picking robot in a specified region of the workspace. Besides, a new workspace, the Equivalent Position Workspace (EPW), is introduced. Finally, the theoretical relationship between the two performance indices and the stability is corrected based on simulation results. The research has important guiding significance and practical value for coal gangue robotic separation.