Search Results
You are looking at 41 - 50 of 75 items for
- Author or Editor: D. Wang x
- Refine by Access: All Content x
Abstract
A complex of N,N'-ethylenebis(salicylideneiminato)diaquochromium(III) nitrate, [Cr(salen)(H2O)2]NO3 was characterized and its decomposition mechanism was studied by TG. The IR spectrum and X-ray analysis were examined for the complex. The non-isothermal kinetic data were analyzed by means of the Achar method and the Coats—Redfern method. The most probable kinetic model function was suggested by comparison of the kinetic parameters.
Abstract
Polyimide BTDA-ODA sample was prepared by polycondensation or step-growth polymerization method. Its low temperature heat capacities were measured by an adiabatic calorimeter in the temperature range between 80 and 400 K. No thermal anomaly was found in this temperature range. A DSC experiment was conducted in the temperature region from 373 to 673 K. There was not phase change or decomposition phenomena in this temperature range. However two glass transitions were found at 420.16 and 564.38 K. Corresponding heat capacity increments were 0.068 and 0.824 J g–1 K–1, respectively. To study the decomposition characteristics of BTDA-ODA, a TG experiment was carried out and it was found that this polyimide started to decompose at ca 673 K.
Summary
Calorimetric determination of the total enthalpy changes (ΔH i) of guanidine-denatured lysozyme (Lys) during the adsorption with simultaneously refolding on the surface of hydrophobic interaction chromatography packings was carried out at 250.001C. The measured ΔH iin the circumstances should include the changes in the three fractions: adsorption, dehydration and molecular conformation. It was found that when the unfolded Lys molecules are adsorbed and refold on the surface, entropy-driving caused by the dehydration of Lys mainly dominates the foregoing process. The refolding enthalpies of Lys, ΔΔH iwere found to be 10~100 folds higher than that measured in usual solutions.</o:p>
Summary
In 1951, 6.7 liters of an aqueous acidic solution of irradiated uranium (360 GBq) leaked from a buried storage tank into unsaturated prairie soil, where it has remained, undisturbed. In October 2001, sonic drilling was conducted to recover core samples around and below the tank location. This paper describes the measurements and investigative approaches being pursued to determine the transport properties of the various fission and daughter products and actinides. Separate effects laboratory experiments are also being conducted involving both inert and radioactive samples in similar soil, to examine the effects on transport properties (diffusion and sorption) of temperature, recharge and discharge rates, concentration and soil porosity. Finally, transport modeling approaches are discussed.
Abstract
The 
—T and d/dT—T curves of the FeCuNbSiB amorphous alloy, which are the relationship between the total saturated magnetic moment per unit mass and temperature, are investigated by magnetic thermogravimetry analysis (TG(M)) technique. It is found that the crystallization process of the samples can be divided into five stages. The studies of samples annealed in temperature range of 480–610°C for 1h show that when the annealing temperature (T
a) is less than 540°C, the quantity of nanocrystalline 
-Fe(Si) phase increases evidently with T
a, and the Curie temperature (T
C) of residual amorphous phase also increases linearly with T
a, i.e. T
C=0.52T
a+91.7°C, with correlation coefficient 
=0.98. The variation of volume fraction of -Fe(Si) nanocrystalline phase or residual amorphous phase with T
a is measured by TG(M) technique.
Abstract
Background and aims
We aimed to systematically identify, evaluate and summarize the research on adolescent emotion dysregulation and problematic technology use. We critically appraise strengths and limitations and provide recommendations for future research.
Methods
We followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and conducted a systematic review of published original reports on adolescent emotion dysregulation and problematic technology use published until March 1, 2022. A thorough search preceded the selection of studies matching prespecified criteria. Strengths and limitations of selected studies, regarding design and reporting, were identified based on current best practices.
Results
39 studies met inclusion criteria. All of these studies provided on the relationship between adolescent emotion dysregulation and problematic technology use severity based on self-report data.
Discussion
There was a positive correlation between adolescent emotion dysregulation and the severity of problematic technology use. Beyond this, other variables (such as anxiety, depression, self-esteem, etc.) were also closely related to emotion dysregulation and problematic technology use. Such studies are of importance to better understand cause-effect relations regarding both variables.
Abstract
Hair samples from junior high school students in metropolitan areas of Taichung, Taiwan were tested for a total of 13 elements, Al, Ag, Br, Cl, Cr, Fe, K, La, Mn, Na, Sc, Se, and Zn by instrumental neutron activation analysis (INAA) to establish seasonal variations, gender and environmental exposures. The seasonal variations of hairs in 39 healthy students (18 males and 21 females; age 13.3 ± 0.4 years; height, 158.0 ± 4.1 cm; weight, 53.4 ± 5.7 kg) were collected at 1.5-month intervals for 1 year starting from late August, 2008. The concentrations of the above elements varied from 103 to 10−2 μg g−1 at different sampling times. A quantified index of agreement (AT) was introduced to help classify the elements. A smaller AT indicated highly consistent quantities of specific metals in the hair while a larger AT indicated increased fluctuation, i.e., less agreement. The different ATs in various hair samples were discussed. The concentrations of these elements are compared with the data in the literature.
Abstract
The effects of two Chinese prescriptions, Zhugu and Shengu capsules were studied on calcium absorption. The absorption ratios of Zhugu and Shengu was 30.4% and 21.5%, respectively.
Abstract
Yaozhou Kiln at Lidipo and Shangdian are two independent porcelain kiln groups of Yaozhou kiln series in Shanxi Province. Both of them were consisted of some individual porcelain kilns. The samples of 20 pieces of porcelain sherds produced in Shangdian and 43 pieces of porcelain sherds made in Lidipo sites which produced in Kin Dynasty (1115–1234 A.D.) have been collected. The main chemical compositions in body were determined by X-ray fluorescence (XRF). The contents of trace elements were measured using neutron activation analysis (NAA). Principal component analysis (PCA) and stepwise discriminant analysis were used to study the provenance characteristic of these samples. The results indicated that the main components and trace elements in the specimen can be used to reveal the provenance characteristic.
Summary
The removal of heavy metal ion Co(II) from aqueous solution was studied usingg-Al2O3 by batch technique. The experiments were performed at T=20±2 °C, in 0.01M NaNO3 solutions and under aerobic conditions. The effect of pH, ionic strength, fulvic acid (FA) and alumina amount on the sorption of Co(II) on alumina were also investigated. The pH affected the sorption of Co(II) significantly as compared with the effect of FA and ionic strength. The results indicated that strong chemical bonds are formed between Co(II) and functional groups of the bare or FA coated alumina, and a precipitation of Co(II) takes place on the alumina surface, induced by a transition from the adsorption to surface. The addition sequences of Co/FA on Co(II) sorption were also studied: the sorption of Co(II) in the ternary system was found independent of addition sequences.
