Search Results
You are looking at 1 - 10 of 34 items for
- Author or Editor: Dong Zhang x
- Refine by Access: All Content x
Abstract
Differential elastic scattering cross sections for backscattering of 0.96–2.74 MeV protons incident on an aluminum layer covered by a gold layer deposited on a graphite crystal have been measured. The lowest proton energy in the experiment is in the Rutherford backscattering energy region. The measured cross sections are compared with the previous data and presented in graphical and tabular forms.
Abstract
The concentrations of up to 11 elements in subcellular fractions of human brain (normal and malignant tumor) have been determined by a combination of gradient centrifugation and INAA methods. Samples of human brain were homogenized in a glass homogenizer tube, the homogenate was separated into nuclei, mitochondrial, myelin, synaptosome fractions, and these fractions were then analyzed using the INAA method. The discussions of elemental subcellular distributions in human brain malignant tumor are presented in this paper.
Eight malting barley cultivars were used to investigate the cultivar and environmental effects on grain protein components and the relationships between protein fractions and β -amylase or β -glucanase activity. The results showed there was a great variation for three protein fraction (albumin, hordein and glutelin) contents over cultivars and locations, and a distinct difference in each protein fraction content between the locations for a given cultivars. Correlation analysis indicated that β -amylase activity was significantly correlated with three protein fraction contents and there was a negative correlation between glutelin content and β -amylase activity, but β -amylase activity positively correlated with albumin or hordein content. Furthermore, there was a significant positive correlation between total protein content and β -glucanase activity, and we found the hordein and glutelin content did not show correlated with β -glucanase activity but the albumin content was a significantly negative correlation with β -glucanase activity.
Abstract
The sorption of Co(II) from aqueous solution on Na-rectorite was investigated under ambient conditions. Experiments were carried out as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic acid and temperature. The results indicated that the sorption of Co(II) was strongly dependent on pH. At low pH the sorption was dominated by outer-sphere surface complexation or ion exchange, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were used to simulate the sorption isotherms at three different temperatures. The thermodynamic data (∆G 0, ∆S 0, ∆H 0) were calculated from the temperature dependent sorption isotherms and the results suggested that the sorption process of Co(II) on Na-rectorite was spontaneous and endothermic. Experimental results indicate that Na-rectorite is a suitable adsorbent for preconcentration and solidification of Co(II) from large volumes of aqueous solutions.
Abstract
The sorption of 60Co(II) on γ-Al2O3 was conducted under various conditions, i.e., contact time, adsorbent content, pH, ionic strength, foreign ions, humic acid (HA), and temperature. Results of sorption data analysis indicated that the sorption of 60Co(II) on γ-Al2O3 was strongly dependent on pH and ionic strength. At low pH the sorption was dominated by outer-sphere surface complexation or ion exchange, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The presence of different cation ions influenced 60Co(II) sorption, while the presence of different anion ions had no obvious influences on 60Co(II) sorption. The presence of HA decreased the sorption of 60Co(II) on γ-Al2O3. The sorption isotherms were simulated well with the Langmuir model. The thermodynamic parameters (ΔH 0 , ΔS 0 and ΔG 0 ) calculated from the temperature-dependent sorption isotherms indicated that the sorption of 60Co(II) on γ-Al2O3 was an endothermic and spontaneous process. Experimental results indicated that the low cost material was a suitable material in the preconcentration of 60Co(II) from large volumes of aqueous solutions.
Abstract
Biomass pyrolysis can be divided into three stages: moisture evaporation, main devolatilization, and continuous slight devolatilization. This present study focuses on the heat and mass transfer characteristics of biomass in the first pyrolysis stage, which takes place in the range of room temperature to 150 °C. Thermalgravimetric experiments of rice husk and cotton stalk were performed by a synchronic thermal analyzer (TG/DSC). Four nonisothermal drying models were obtained from common isothermal drying models in order to describe the drying behavior of agricultural products. The moisture content of biomass decreased rapidly as the temperature increased and an apparent water loss peak was observed in the temperature range of 65–75 °C. DSC could be regarded as the superposition of three parts: heat flow from moisture evaporation, heat flow from the heat capacity of unevaporated moisture, and heat flow from the heat capacity of dry base biomass. The heat requirements for the dehydration of 1 kg rice husk and cotton stalk were 251 and 269 kJ, respectively. Nonisothermal drying models were evaluated based on the coefficient of determination (R 2) and reduced chi-square (χ2). Page model was found to be the best for describing the nonisothermal drying kinetics. The values of activation energy were determined to be 9.2 and 15.1 kJ/mol for rice husk and cotton stalk, respectively.
Abstract
Venetoclax is the first oral Bcl-2 inhibitor with high affinity targeting tumor cell apoptosis mechanism. In this study we developed a simple, sensitive and reliable LC–MS/MS method to determine venetoclax in children's hemolytic or lipemic samples. The method utilized an electrospray ion source and operated in multiple reaction monitoring mode. Venetoclax-d8 was used as an internal standard. Plasma samples were precipitated by acetonitrile containing 10% dimethyl sulfoxide and were separated by a Hypersil GOLD column (2.1 mm × 150 mm, 5 μm). The mobile phase consisted of acetonitrile-2 mM ammonium acetate (30:70, v/v) containing 0.4% formic acid. The quantification for venetoclax and venetoclax-d8 were m/z 868.1 → 636.1, m/z 876.1 → 644.1, respectively. The linear range was 10–2,000 ng mL−1 for venetoclax. The matrix in normal plasma, hemolytic or lipemic plasma had no significant effect on the detection results. The specificity, recovery and stability also met the acceptance criteria of guiding principles for the validation of biological sample quantitative analysis presented in the Chinese Pharmacopoeia (2015). As a result, this method is particularly suitable for determining venetoclax in hemolytic or lipemic samples from children with acute myeloid leukemia. The method, with the application of monitoring drug concentrations in pediatric patients, was successful.
Abstract
This study characterized the removal of strontium from an aqueous solution via co-precipitation followed by microfiltration (CPMF) on a lab-scale. Sodium carbonate was used as the precipitating agent. Ferric chloride was added to a settler at a dosage of 20 mg/L to improve strontium removal, and it was added to a membrane separator at a dosage of 10 mg/L to reduce membrane fouling. The concentration of strontium in the raw water used in this study was about 5 mg/L. In two intermittent tests, where dosages of sodium carbonate were 2000 mg/L and 1000 mg/L, the mean decontamination factors (DFs) were 237 and 158 and the mean concentration factors (CFs) were 288 and 462, respectively. Although the mean DF value was lower when the sodium carbonate dosage was 1000 mg/L instead of 2000 mg/L, the rate at which the specific flux (SF) of the membrane declined decreased as the amount of the effluent treated increased. The problem of strontium release at the beginning of the operation was controlled by a continuous test in which the dosage of sodium carbonate still was 1000 mg/L and the other parameters were the same as in the other tests. The results showed that the mean DF and CF were 157 and 480, respectively.
Abstract
Atmospheric aerosols are generally collected on filters according to the International Monitoring System (IMS) designed in the Comprehensive Nuclear-Test-Ban Treaty (CTBT). More information could be revealed when the filter sample is pretreated rather than measured directly by g-ray spectrometer. Microwave-assisted extraction (MAE) is a suitable method that gives higher recoveries of elements from glass fibrous filters under different conditions. The results indicate that the MAE is a highly efficient and robust method for the treatment of glass fibrous filter samples. The recoveries of potential fission products from glass fibrous filter samples by microwave-assisted extraction meet the efficiency of the extraction by both aqua regia and 2% HCl.
Abstract
Objectives
Understanding the neural mechanisms underlying Internet gaming disorder (IGD) is essential for the condition's diagnosis and treatment. Nevertheless, the pathological mechanisms of IGD remain elusive at present. Hence, we employed multi-voxel pattern analysis (MVPA) and spectral dynamic causal modeling (spDCM) to explore this issue.
Methods
Resting-state fMRI data were collected from 103 IGD subjects (male = 57) and 99 well-matched recreational game users (RGUs, male = 51). Regional homogeneity was calculated as the feature for MVPA based on the support vector machine (SVM) with leave-one- out cross-validation. Mean time series data extracted from the brain regions in accordance with the MVPA results were used for further spDCM analysis.
Results
Results display a high accuracy of 82.67% (sensitivity of 83.50% and specificity of 81.82%) in the classification of the two groups. The most discriminative brain regions that contributed to the classification were the bilateral parahippocampal gyrus (PG), right anterior cingulate cortex (ACC), and middle frontal gyrus (MFG). Significant correlations were found between addiction severity (IAT and DSM scores) and the ReHo values of the brain regions that contributed to the classification. Moreover, the results of spDCM showed that compared with RGU, IGD showed decreased effective connectivity from the left PG to the right MFG and from the right PG to the ACC and decreased self-connection in the right PG.
Conclusions
These results show that the weakening of the PG and its connection with the prefrontal cortex, including the ACC and MFG, may be an underlying mechanism of IGD.
