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  • Author or Editor: Yan Huang x
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Abstract

The use of heat to inactivate foodborne pathogens is a critical control point and the most common means for assuring the microbiological safety of processed foods. A key to optimization of the heating step is defining the target pathogens’ heat resistance. Sufficient evidence exists to document that insufficient cooking, reheating, and/or subsequent cooling are often contributing factors in food-poisoning outbreaks. Accordingly, the objective of thermal processing is to design sufficient heating regiments to achieve a specific lethality for foodborne pathogens in foods. The effects and interactions of temperature, pH, sodium chloride content, sodium pyrophosphate, and sodium lactate concentration are among the variables that were considered when attempting to assess the heat inactivation kinetics of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and spores of non-proteolytic Clostridium botulinum. Incorporation of these multiple barriers usually increases the sensitivity of pathogens to heat, thereby reducing heat requirements and ensuring the safety of ready-to-eat food products. Complex multifactorial experiments and analysis to quantify the effects and interactions of additional intrinsic and extrinsic factors and development of “enhanced” predictive models are underway to ensure the microbiological safety of thermally processed foods. Predictive inactivation kinetics (thermal death) models for foodborne pathogens have been converted into an easy-to-use computer program that is available on the USDA–Eastern Regional Research Center website. These models should aid in evaluating the safety of cooked products and are being used as building blocks for microbial risk assessment.

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Abstract  

Herein, hydroxyapatite (HAP) was prepared by aqueous precipitation technique and was characterized by using FT-IR and XRD to determine its chemical functional groups and micro-structure. The removal of cobalt from aqueous solution to HAP was studied by batch technique as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, fulvic acid (FA), and temperature under ambient conditions. The results indicated that the sorption of Co(II) on HAP was strongly dependent on pH and ionic strength. The presence of FA enhanced the sorption of Co(II) on HAP at low pH, whereas reduced Co(II) sorption on HAP at high pH. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms at three different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Co(II) on HAP was spontaneous and endothermic. The sorption of Co(II) was dominated by outer-sphere surface complexation and ion exchange at low pH, whereas inner-sphere surface complexation or surface precipitation was the main sorption mechanism at high pH values. The results suggest that the HAP is a suitable material in the preconcentration and solidification of Co(II) from large volumes of aqueous solutions.

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Abstract  

In this work, hydroxyapatite (HAP) was prepared by aqueous precipitation technique and was characterized by using FT-IR to determine its chemical functional groups. A series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time, pH, ionic strength, foreign ions, fulvic acid (FA) and temperature on the sorption behavior of HAP towards radionuclide 109Cd(II). The results indicated that the sorption of 109Cd(II) on HAP was strongly dependent on pH and ionic strength. A positive effect of FA on 109Cd(II) sorption was found at pH <7.0, whereas a negative effect was observed at pH >7.0. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms at three different temperatures of 298.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH0, ΔS0 and ΔG0) calculated from the temperature dependent sorption isotherms indicated that the sorption process of 109Cd(II) on HAP was spontaneous and endothermic. At low pH, the sorption of 109Cd(II) was dominated by outer-sphere surface complexation and ion exchange on HAP surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that HAP has good potentialities for cost-effective treatments of 109Cd(II)-contaminated wastewaters.

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Abstract  

The bentonite/iron oxide magnetic composites were prepared by co-precipitation method, and characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction and scanning electron microscope. The prepared bentonite/iron oxide magnetic composites were used as a sorbent for the removal of Co(II) ions from radioactive wastewater. The results demonstrated that the sorption of Co(II) was strongly dependent on pH and ionic strength at low pH values. The sorption of Co(II) was dominated by outer-sphere surface complexation or ion exchange at low pH whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The presence of iron oxide in the composites also contributes to the sorption of Co(II) ions on the magnetic composites. The experimental data were well described by Langmuir model. The thermodynamic parameters (∆G °, ∆S °, ∆H °) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on bentonite/iron oxide magnetic composites was an endothermic and spontaneous processes.

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The most abundant seed storage proteins of wheat are gliadins and glutenins. Gliadins, including α/β, γ and ω types, are normally monomeric proteins and account for about 50% of the gluten proteins. In this study, 55 sequences of γ -gliadin genes were obtained from species of Sitopsis section, the deduced B genome donors of wheat. Despite the high sequence similarities to the known γ -gliadin genes, extensive variations were also found. Using the extensive sequence information deposited in database and obtained in this study, a comprehensive classification of the γ -gliadin multigene families were performed based on the primary structures and phylogenic analysis. All the γ -gliadin genes analyzed could be divided into 2 types, which contain 8 and 9 cysteines, respectively. Type I (with 8 cysteines) and type II (with 9 cysteines) are further classified to 7 and 4 groups, respectively, and several subgroups are also identified. The genes derived from A, B and D genomes of common wheat were clustered distinctly, indicating that there was apparent genomic specificity in γ -gliadins genes. Besides the high homology between γ -gliadin genes from Sitopsis species and B genome of wheat, some unique groups or subgroups were also identified in Sitopsis section, suggesting that it could be considered as a valuable source of γ -gliadin genes. The comparison of deduced primary structures of each group and/or subgroup was conducted, from which their evolution and quality properties were also speculated.

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The principal component analysis is a practical method for multivariate statistical analyses. It can eliminate the correlation between sample indexes, and on the premise of keeping the main information of samples, extract a few representative principal components. This article adopts the input—output method and principal component analysis. It carries on the transverse comparison research on the effective utilization situation of human resources in China in 2008 and reveals the actual situation of efficient use of human resources in the provinces in China. The degree of effective use of human resources in Beijing is the highest, while in Ningxia is the lowest. It is closely related to the economic development. Finally, it puts forward the thoughts and suggestions of improving the effective use of human resources in China.

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Abstract

A new homologous series of curing agents (LCECAn) containing 4,4′-biphenyl and n-methylene units (n = 2, 4, 6) were successfully synthesized. The curing behaviors of a commercial diglycidyl ether of bisphenol-A epoxy (E-51) and 4,4′-bis(2,3-epoxypropoxy)biphenyl (LCE) by using LCECAn as the curing agent have been investigated by differential scanning calorimetry (DSC), respectively. The Ozawa equation was applied to the curing kinetics based upon the dynamic DSC data, and the isothermal DSC data were fitted using an autocatalytic curing model. The glass transition temperatures (T g) of the cured epoxy systems were determined by DSC upon the second heating, and the thermal decomposition temperatures (T d) were obtained by thermogravimetric (TG) analyses. The results show that the number of methylene units in LCECAn has little influence on the curing temperatures of E-51/LCECAn and LCE/LCECAn systems. In addition, the activation energies obtained by the dynamic method proved to be larger than those by the isothermal method. Furthermore, both the T g and T d of the cured E-51/LCECAn systems and LCE/LCECAn systems decreased with the increase in the number of methylene units in LCECAn.

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Authors: Chuanfu Chen, Yuan Yu, Qiong Tang, Kuei Chiu, Yan Rao, Xuan Huang and Kai Sun

Abstract

Authority generally relates to expertise, recognition of official status of a source, and the reputation of the author and publisher. As the Internet has become a ubiquitous tool in modern science and scholarly research, evaluating the authority of free online scholarly information is becoming crucial. However, few empirical studies have focused on this issue. Using a modified version of Jim Kapoun's “Five criteria for evaluating web pages” as framework, this research selected 32 keywords from eight disciplines, inputted them into three search engines (Google, Yahoo and AltaVista) and used Analytic Hierarchy Process to determine the weights. The first batches of results (web pages) from keyword searching were selected as evaluation samples (in the two search phases, the first 50 and 10 results were chosen, respectively), and a total of 3,134 samples were evaluated for authority based on the evaluation framework. The results show that the average authority value for free online scholarly information is about 3.63 (out of five), which is in the “fair” level (3 ≤ Z < 4) (Z is the value assigned to each sample). About 41% of all samples collected provide more authoritative scholarly information. Different domain names, resource types, and disciplines of free online scholarly information perform differently when scored in terms of authority. In conclusion, the authority of free online scholarly information has been unsatisfactory, and needs to be improved. Furthermore, the evaluation framework and its application developed herein could be a useful instrument for librarians, researchers, students, and the public to select Internet resources.

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Authors: Lan Guo, Min Luo, Wan-Xin Wang, Guo-Liang Huang, Yan Xu, Xue Gao, Ci-Yong Lu and Wei-Hong Zhang

Background and aims

This large-scale study aimed to test (a) associations of problematic Internet use (PIU) and sleep disturbance with suicidal ideation and suicide attempts among Chinese adolescents and (b) whether sleep disturbance mediates the association between PIU and suicidal behavior.

Methods

Data were drawn from the 2017 National School-based Chinese Adolescents Health Survey. A total of 20,895 students’ questionnaires were qualified for analysis. The Young’s Internet Addiction Test was used to assess PIU, and level of sleep disturbance was measured by the Pittsburgh Sleep Quality Index. Multilevel logistic regression models and path models were utilized in analyses.

Results

Of the total sample, 2,864 (13.7%) reported having suicidal ideation, and 537 (2.6%) reported having suicide attempts. After adjusting for control variables and sleep disturbance, PIU was associated with an increased risk of suicidal ideation (AOR = 1.04, 95% CI = 1.03−1.04) and suicide attempts (AOR = 1.03, 95% CI = 1.02−1.04). Findings of the path models showed that the standardized indirect effects of PIU on suicidal ideation (standardized β estimate = 0.092, 95% CI = 0.082−0.102) and on suicide attempts (standardized β estimate = 0.082, 95% CI = 0.068−0.096) through sleep disturbance were significant. Conversely, sleep disturbance significantly mediated the association of suicidal behavior on PIU.

Discussion and conclusions

There may be a complex transactional association between PIU, sleep disturbance, and suicidal behavior. The estimates of the mediator role of sleep disturbance provide evidence for the current understanding of the mechanism of the association between PIU and suicidal behavior. Possible concomitant treatment services for PIU, sleep disturbance, and suicidal behavior were recommended.

Open access
Authors: Yang Ya-xin, Liu Qing-cheng, Wu Xin-min, Huang Yan-jun, Lin Jun, Wu Ya-mei, Li Shu-zhen and Hsia Yuan-fu

Summary  

A new air radon monitor is proposed based on the combination of an aluminum disk and an electric multilevel clearance system (EMCS). The positively charged, small aluminum disk has a high collection ability to radon with a collection efficiency of about 60%. The old radon progenies were eliminated by the EMCS in the air entrance of the monitor with an efficiency of about 99%. The monitor was calibrated in the national standard radon chamber in Hengyang, China. Compared to the radon double-filter equipment, the results, gained by both apparatus, coincide with each other.

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