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Abstract  

A continuous fixed-bed study was carried out by using zeolite as a low-cost adsorbent for the removal of uranium(VI) ions from aqueous solution under the effect of various process parameters such as the pH the bed depth, the flow rate, the presence of salt and the initial U(VI) ion concentration. The U(VI) ion uptake by zeolite increased with initial U(VI) ion concentration and bed height, but decreased as the flow rate increased. The adsorption capacity reached a maximum at pH of 6.0. A shorter breakthrough time was observed in the presence of salt. The experimental data obtained from the breakthrough curves were analyzed using the Thomas model. The BDST model was also applied to predict the service times for other flow rates and initial concentrations. The results showed that the Thomas model was suitable for the description of the whole breakthrough curve, while the data were in good agreement with the BDST model. The columns were regenerated by eluting the bound U(VI) ions with 0.1 mol L−1 NaHCO3 solution after the adsorption studies. After desorption and regeneration with deionized water, zeolite could be reused to adsorb uranium(VI) at a comparable capacity.

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Abstract  

A rapid separation system based on SISAK technique was established to isolate 142La successfully from fission products. SISAK technique is often applied in the separation of nuclides with the half-life of seconds or minutes. Here it was used to separate the parent nuclide of 142La, which the half-life is in the magnitude of several seconds. According to the separation procedure designed in the paper, the activity of 142La acquired is more than 104 Bq and the decontamination factors for most γ-emitters are higher than 103.

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Barium(II) tetraphenylborate, Ba(Bph4))2·4H2O was prepared, and its decomposition mechanism was studied by means of TG and DTA. The products of thermal decomposition were examined by means of gas chromatography and chemical methods. A kinetic analysis of the first stage of thermal decomposition was made on the basis of TG and DTG curves and kinetic parameters were obtained from an analysis of the TG and DTG curves using integral and differential methods. The most probable kinetic function was suggested by comparison of kinetic parameters. A mathematical expression was derived for the kinetic compensation effect.

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Abstract

Background and aims

Internet gaming disorder (IGD) in adolescents is a concerning issue. Positive parenting has been found to protect against adolescent IGD, but the underlying mechanisms await further investigation. As such, this study examined the longitudinal association between parental involvement (PI) – a specific type of positive parenting understudied in the literature of adolescent gaming disorder – and IGD. Moreover, this study also tested consideration of future consequences (CFC) as a mediator and peer victimization (PV) as a moderator.

Methods

A two-wave longitudinal research spanning 6 months apart was conducted. Participants were Chinese adolescents (final N = 434; 222 females; M age = 14.44 years, SD = 1.56). They provided ratings on PI, PV, and IGD at Wave 1, and CFC-immediate, CFC-future, and IGD at Wave 2.

Results

Descriptive statistics showed that the prevalence rate of IGD was 10.81% and 9.45% at Waves 1 and 2, respectively. Moreover, results of moderated mediation model found that after controlling for Wave 1 IGD and covariates, Wave 1 PI was associated with Wave 2 IGD via preventing adolescents who had higher levels of PV from developing a tendence of CFC-immediate and via promoting adolescents who had lower levels of PV to develop a tendence of CFC-future.

Discussion and Conclusions

Altogether, these results suggest that facilitative ecological systems (e.g., positive parenting and good relationships with peers) and personal strengths (e.g., positive future orientation) jointly contribute to the mitigation of adolescent IGD.

Open access

Three wheat varieties of Atlas66 (Al-tolerant genotype), EM12 (a major elite cultivar in China) and Scout66 (Al-sensitive genotype) were used to investigate their potential mechanisms of Al toxicity. Al concentrations of 50, 75, 100 μmol l −1 were used and the inhibition on root elongation between Scout66 and EM12 is significantly higher than that of Al-tolerant Atlas66, which is negative correlated to the Al absorption in root apices. Organic acids secretion was checked 24 h after Al stress and only malate was detected in Atlas66, but none of the organic acids were detected in the others, suggesting that secretion of malate in root is a major mechanism of Al resistance in Al-tolerant wheat genotype. The root cell ultrastructure showed less damage in Atlas66 than that in Scout66 and EM12 under Al stress by transmission electron microscopy (TEM) technique. Tissue culture was carried out and the callus induction frequencies were all decreased on the media containing Al. The decrease of callus induction frequencies was less in Atlas66 than that in the others. It is concluded that Al damages the cell ultrastructure, resulting in the inhibition of acids secretion and cell division, which implies that the damage of cell ultrastructure is probably the key factor in Al inhibition of root growth.

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Exploring antibiotic resistant mechanism by microcalorimetry

Determination of thermokinetic parameters of metallo-β-lactamase L1 catalyzing penicillin G hydrolysis

Journal of Thermal Analysis and Calorimetry
Authors:
Hui-Zhou Gao
,
Qi Yang
,
Xiao-Yan Yan
,
Zhu-Jun Wang
,
Ji-Li Feng
,
Xia Yang
,
Sheng-Li Gao
,
Lei Feng
,
Xu Cheng
,
Chao Jia
, and
Ke-Wu Yang

Abstract

In an effort to probe the reaction of antibiotic hydrolysis catalyzed by B3 metallo-β-lactamase (MβL), the thermodynamic parameters of penicillin G hydrolysis catalyzed by MβL L1 from Stenotrophomonas maltophilia were determined by microcalorimetric method. The values of activation free energy ΔG θ are 88.26, 89.44, 90.49, and 91.57 kJ mol−1 at 293.15, 298.15, 303.15, and 308.15 K, respectively, activation enthalpy ΔH θ is 24.02 kJ mol−1, activation entropy ΔS θ is −219.2511 J mol−1 K−1, apparent activation energy E is 26.5183 kJ mol−1, and the reaction order is 1.0. The thermodynamic parameters reveal that the penicillin G hydrolysis catalyzed by MβL L1 is an exothermic and spontaneous reaction.

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Exploring antibiotic resistant mechanism by microcalorimetry II

Determination of thermokinetic parameters of imipenem hydrolysis with metallo-β-lactamase ImiS

Journal of Thermal Analysis and Calorimetry
Authors:
Xia Yang
,
Lei Feng
,
Kang-Zhen Xu
,
Hui-Zhou Gao
,
Chao Jia
,
Cheng-Cheng Liu
,
Jian-Min Xiao
,
Le Zhai
,
Li-Sheng Zhou
, and
Ke-Wu Yang

Abstract

In an effort to understand the reaction of antibiotic hydrolysis with B2 metallo-β-lactamases (MβLs), the thermodynamic parameters of imipenem hydrolysis catalyzed by metallo-β-lactamase ImiS from Aeromonas veronii bv. sobria were determined by microcalorimetric method. The values of activation free energy are 86.400 ± 0.043, 87.543 ± 0.034, 88.772 ± 0.024, and 89.845 ± 0.035 kJ mol−1 at 293.15, 298.15, 303.15, and 308.15 K, respectively, activation enthalpy is 18.586 ± 0.009 kJ mol−1, activation entropy is −231.34 ± 0.12 J mol−1 K−1, apparent activation energy E is 21.084 kJ mol−1, and the reaction order is 1.5. The thermodynamic parameters reveal that the imipenem hydrolysis catalyzed by metallo-β-lactammase ImiS is an exothermic and spontaneous reaction.

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Journal of Behavioral Addictions
Authors:
Lijuan Shi
,
Yuanyuan Wang
,
Hui Yu
,
Amanda Wilson
,
Stephanie Cook
,
Zhizhou Duan
,
Ke Peng
,
Zhishan Hu
,
Jianjun Ou
,
Suqian Duan
,
Yuan Yang
,
Jiayu Ge
,
Hongyan Wang
,
Li Chen
,
Kaihong Zhao
, and
Runsen Chen

Abstract

Background

The aim of this study was to investigate the mechanisms of Internet gaming disorder (IGD) and the associated interaction effects of childhood trauma, depression and anxiety in college students.

Methods

Participants were enrolled full-time as freshmen at a University in the Hunan province, China. All participants reported their socio-demographic characteristics and undertook a standardized assessment on childhood trauma, anxiety, depression and IGD. The effect of childhood trauma on university students' internet gaming behaviour mediated by anxiety and depression was analysed using structural equation modelling (SEM) using R 3.6.1.

Results

In total, 922 freshmen participated in the study, with an approximately even male-to-female ratio. A mediation model with anxiety and depression as the mediators between childhood trauma and internet gaming behaviour allowing anxiety and depression to be correlated was tested using SEM. The SEM analysis revealed that a standardised total effect of childhood trauma on Internet gaming was 0.18, (Z = 5.60, 95% CI [0.02, 0.05], P < 0.001), with the direct effects of childhood trauma on Internet gaming being 0.11 (Z = 3.41, 95% CI [0.01, 0.03], P = 0.001), and the indirect effects being 0.02 (Z = 2.32, 95% CI [0.00, 0.01], P = 0.020) in the pathway of childhood trauma-depression-internet gaming; and 0.05 (Z = 3.67, 95% CI [0.00, 0.02], P < 0.001) in the pathway of childhood trauma-anxiety-Internet gaming. In addition, the two mediators anxiety and depression were significantly correlated (r = 0.50, Z = 13.54, 95% CI [3.50, 5.05], P < 0.001).

Conclusions

The study revealed that childhood trauma had a significant impact on adolescents' Internet gaming behaviours among college students. Anxiety and depression both significantly mediated the relationship between childhood trauma and internet gaming and augmented its negative influence. Discussion of the need to understand the subtypes of childhood traumatic experience in relationship to addictive behaviours is included.

Open access