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  • Author or Editor: Li Lu x
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A two-dimensional thin-layer chromatographic fingerprint has been developed on a polyamide plate for the quality control of Helleborus thibetanus Franch. The investigated sample was separated by chloroform-ethyl acetate-methanol (3.0:8.0:4.4, v/v) in the first dimension and isooctane-n-propyl alcohol-water (10:2.5:1.0, v/v) adding 0.28 mol L−1 sodium dodecyl sulfate, a reversed micelle, in the second dimension. The plate was dried in the air at room temperature and examined in ultraviolet (UV) light at λ = 365 nm after development. The two developments were carried out over a distance of 70 mm. The two-dimensional thin-layer chromatographic method was validated in terms of repeatability, stability, and robustness. For fingerprint analysis, nine spots were identified as common spots. Statistical method (canonical correlation analysis) was first used to calculate the degree of similarity between the two-dimensional chromatograms. The proposed method was novel and accurate for the identification and quality evaluation of H. thibetanus Franch.

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Abstract

The calcination characteristics, sulfation conversion, and sulfation kinetics of a white mud from paper manufacture at fluidized bed combustion temperatures were investigated in a thermogravimetric analyzer. Also, the comparison between the white mud and the limestone in sulfation behavior and microstructure was made. Although the white mud and the limestone both contain lots of CaCO3, they are different in the alkali metal ions content and microstructure. It results in a marked difference in sulfation behavior between the white mud and the limestone. The CaO derived from white mud achieves the maximum sulfation conversion of 83% at about 940 °C which is 1.7 times higher than that derived from limestone at about 880 °C. The shrinking unreacted core model is appropriate to analyze the sulfation kinetics of the white mud. The chemical reaction activation energy E a and the activation energy for product layer diffusion E p for the sulfation of the white mud are 44.94 and 55.61 kJ mol−1, respectively. E p for the limestone is 2.8 times greater than that for the white mud. The calcined white mud possesses higher surface area than the calcined limestone. Moreover, the calcined white mud has more abundant pores in 4–24 nm range which is almost optimum pore size for sulfation. It indicates that the microstructure of the white mud is beneficial for SO2 removal.

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Abstract

In this study, the solid-state shear pan-milling was employed to prepare a series of polymer/layered silicate (PLS) nanocomposites. During the process of pan-milling at ambient temperature, poly(vinyl alcohol)/organic montmorillonite (PVA/OMMT) can be effectively pulverized, resulting in coexistence of intercalated and exfoliated OMMT layers. The obtained PLS nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM analysis indicated that OMMT dispersed homogeneously in PVA matrix and XRD results illustrated that pan-milling had an obvious effect on increase in the interlayer spacing of OMMT, and resulted in coexistence of intercalated and exfoliated OMMT layers formed. Thermal gravimetric analysis showed that thermal stability of PVA was improved owing to the incorporation of OMMT. Thermal decomposition kinetics of PVA/OMMT nanocomposites with different milling cycles of OMMT was also studied. Two types of OMMT are chosen to compare the effect of hydrophilicity of OMMT on PVA/OMMT nanocomposites.

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Abstract  

The thermal decomposition studies for two palladium(II) complexes Pd(apyr)2Cl2 and Pd(pmpa)Cl2 (apyr=1–aminopyrene and pmpa=N–(2–pyridylmethylene)–1–pyrenylamine) were carried out in pure nitrogen using TG-DTG techniques. The non-isothermal kinetic parameters for the two complexes were evaluated employing the method suggested by Málek, esták, Koga et al. Based on the above results, thermal behaviour of the complexes were carefully discussed, which showed that not only the parameters value, but also the decomposition pattern and mechanism for complex 1 are different from complex 2.

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Summary  

Cyanocobalamin (CNCbl), a kind of vitamin B12 (cobalamin, Cbl), which has a special binding capability to rapid dividing cells and proliferating tissue, especially tumors, has been modified and labeled by 99mTc. The optimal labeling condition was determined, and the biodistribution of 99mTc-DTPA-b-CNCbl both in normal mice and TA2 mice bearing MA891 mammary tumors were studied. 99mTc-DTPA-b-CNCbl showed low uptake and rapid clearance in nontarget tissues, and renal excretion. About 40% of uptake at 1 hour remained in the tumor at 12 hours p.i. The satisfying ratio of T/NT was acquired at 6 hours p.i.

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A micellar high-performance liquid chromatography (HPLC) method has been described for simultaneous determination of ephedrine, pseudoephedrine, and methylephedrine in Ephedra Herb and two traditional Chinese preparations. The separation and determination of ephedrine, pseudoephedrine, and methylephedrine were performed using a mobile phase containing 1.75 × 10−1 mol·L−1 sodium dodecyl sulphate and 0.02 mol·L−1 potassium hydrogen phosphate with 10% (v/v) methanol at pH 3.0, running at 1.5 mL·min−1 by a Venusil XBP C18 (250 × 4.6 mm, 5 μm) column at 40 °C. The detected wavelength was set at 210 nm. The method was validated according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines. The main analytical parameters were linearity (r > 0.9990), intra- and inter-day precisions (relative standard deviation [RSD %], 0.33–1.63, and RSD %, 1.26–2.20, respectively), limit of quantifications [LOQs], and limit of detections [LODs] (2.6 × 10−4 and 7.8 × 10−5 mg·mL−1 for ephedrine, 6.8 × 10−4 and 2.0 × 10−4 mg·mL−1 for pseudoephedrine, and 5.0 × 10−4 and 1.5 × 10−4 mg·mL−1 for methylephedrine). RSDs of recoveries were <5.5% in the three samples. Based on the optimized chromatographic conditions and the eluted orders, a model of separation mechanism for the analytes was established. The results indicated that the proposed method was an accurate, “green” and cheap method.

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Abstract

In this work, CaO derived from the carbide slag (CaO–carbide slag) as a kind of typical industrial waste was used to capture CO2 during the calcination/carbonation cycles. The carbonation kinetics and cyclic carbonation behavior of CaO–carbide slag were investigated in a thermogravimetric analyzer. The chemical reaction activation energy and the product layer diffusion activation energy for carbonation of CaO–carbide slag are 12.46 and 36.83 kJ mol−1, respectively, which are significantly less than those for carbonation of CaO derived from the limestone (CaO–limestone). CaO–carbide slag shows higher carbonation conversion than CaO–limestone after enough reaction time and at the same number of cycles. Moreover, the calcination temperature and CO2 concentration in the carbonation atmosphere have important effect on the carbonation behavior of CaO–carbide slag. The BET surface area of CaO–carbide slag is 1.6 times as large as that of CaO–limestone after 1 cycle and the average pore size of CaO–carbide slag is much smaller. In addition, the carbide slag contains much more Al2O3 than most of the limestones. These are reasons why carbide slag as a precursor can retain greater carbonation conversion than limestone in calcination/carbonation cycles.

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Authors: Lu Li, Dan-Dan Xu, Jing-Xin Chai, Di Wang, Lin Li, Ling Zhang, Li Lu, Chee H. Ng, Gabor S. Ungvari, Song-Li Mei and Yu-Tao Xiang

Background and aims

Internet addiction disorder (IAD) is common in university students. A number of studies have examined the prevalence of IAD in Chinese university students, but the results have been inconsistent. This is a meta-analysis of the prevalence of IAD and its associated factors in Chinese university students.

Methods

Both English (PubMed, PsycINFO, and Embase) and Chinese (Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from their inception until January 16, 2017.

Results

Altogether 70 studies covering 122,454 university students were included in the meta-analysis. Using the random-effects model, the pooled overall prevalence of IAD was 11.3% (95% CI: 10.1%–12.5%). When using the 8-item Young Diagnostic Questionnaire, the 10-item modified Young Diagnostic Questionnaire, the 20-item Internet Addiction Test, and the 26-item Chen Internet Addiction Scale, the pooled prevalence of IAD was 8.4% (95% CI: 6.7%–10.4%), 9.3% (95% CI: 7.6%–11.4%), 11.2% (95% CI: 8.8%–14.3%), and 14.0% (95% CI: 10.6%–18.4%), respectively. Subgroup analyses revealed that the pooled prevalence of IAD was significantly associated with the measurement instrument (Q = 9.41, p = .024). Male gender, higher grade, and urban abode were also significantly associated with IAD. The prevalence of IAD was also higher in eastern and central of China than in its northern and western regions (10.7% vs. 8.1%, Q = 4.90, p = .027).

Conclusions

IAD is common among Chinese university students. Appropriate strategies for the prevention and treatment of IAD in this population need greater attention.

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Abstract  

Nuclear microprobe was used to measure single aerosol particles (SAPs) indoors from Shanghai. Every particle is characterized with its micro-PIXE spectrum, which can be considered as the fingerprint of the SAPs. The pattern recognition technique (PR) was applied to trace the SAPs back to their source. Results of five monitor homes at different locations in Shanghai show that most of the measured indoor aerosol particles are derived from soil dust, cement dust, vehicle exhaust, coal boilers and steel mill dust.

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Analysis of the binding interaction of (−)-epigallocatechin-3-gallate (EGCG) and pepsin is important for understanding the inhibition of digestive enzymes by tea polyphenols. We studied the binding of EGCG to pepsin using fluorescence spectroscopy, Fourier transform infrared spectroscopy, isothermal titration calorimetry, and protein-ligand docking. We found that EGCG could inhibit pepsin activity. According to thermodynamic parameters, a negative ΔG indicated that the interaction between EGCG and pepsin was spontaneous, and the electrostatic force accompanied by hydrophobic binding forces may play major role in the binding. Data from multi-spectroscopy and docking studies suggest that EGCG could bind pepsin with a change in the native conformation of pepsin. Our results provide further understanding of the nature of the binding interactions between catechins and digestive enzymes.

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