A many-objective evolutionary algorithm based on three states for solving many-objective optimization problem.

In recent years, researchers have taken the many-objective optimization algorithm, which can optimize 5, 8, 10, 15, 20 objective functions simultaneously, as a new research topic. However, the current research on many-objective optimization technology also encounters some challenges. For example: Pareto resistance phenomenon, difficult diversity maintenance. Based on the above problems, this paper proposes a many-objective evolutionary algorithm based on three states (MOEA/TS). Firstly, a feature extraction operator is proposed. It can extract the features of the high-quality solution set, and then assist the evolution of the current individual. Secondly, based on Pareto front layer, the concept of "individual importance degree" is proposed. The importance degree of an individual can reflect the importance of the individual in the same Pareto front layer, so as to further distinguish the advantages and disadvantages of different individuals in the same front layer. Then, a repulsion field method is proposed. The diversity of the population in the objective space is maintained by the repulsion field, so that the population can be evenly distributed on the real Pareto front. Finally, a new concurrent algorithm framework is designed. In the algorithm framework, the algorithm is divided into three states, and each state focuses on a specific task. The population can switch freely among these three states according to its own evolution. The MOEA/TS algorithm is compared with 7 advanced many-objective optimization algorithms. The experimental results show that the MOEA/TS algorithm is more competitive in many-objective optimization problems.

Effect of dietary supplementation Ampelopsis grossedentata extract on growth performance and muscle nutrition of Megalobrama hoffmanni by gut bacterial mediation.

Nowadays, Megalobrama hoffmanni is a typical cultured fish in south China due to its resource decline in the Pearl River. Meanwhile, since antibiotics had been banned internationally, Chinese medical herbal plant serving as alternative to antibiotics has been adopted in aquaculture. In the present study, to ensure the health growth of M. hoffmanni, extract of traditional medical herbal plant Ampelopsis grossedentata was dietary supplemented and a series experiments were performed, including growth performance determination, physiological/biochemical detection, nutrition analysis, histology analysis, and 16S rRNA amplicon sequencing. Growth performance enhancement was determined since the weight gain rate (WGR), specific growth rate (SGR), and condition factor (CF) of M. hoffmanni increased as feeding inclusion A. grossedentata extract. Interestingly, the total content of muscle fatty acids ascended via supplementing A. grossedentata extract at middle level, in which group the activities of superoxide dismutase (SOD) and catalase (CAT) significantly increased and thus retarded the lipid peroxidation process (manifesting as malondialdehyde (MDA) content rising). Additionally, immune response and inflammatory reaction was stimulated in low and high level A. grossedentata extract added groups, indicating a suitable dosage of A. grossedentata extract benefited in safety production. Moreover, gut microbiota community varied hugely as daily supplementation A. grossedentata extract and the keystone species were tightly related to lipid transformation, which ultimately led to fatty acids composition variation. Our results confirmed that dietary supplementation A. grossedentata extract at the middle level (0.5‰, w/w) is suitable for serving as feed additive in healthful aquaculture of M. hoffmanni.

Dietary supplementation Eucommia ulmoides extract at high content served as a feed additive in the hens industry.

Since numerous natural components in Eucommia ulmoides belong to phytoestrogen, its effect on hens production deserve more attention. To investigate the potential of E. ulmoides extract used as a feed additive, laying performance, egg quality, yolk cholesterol, yolk fatty acids, yolk fatty, yolk volatile components, albumen amino acids, plasma biochemical parameters, intestinal histology, and gut microbiota of hens (n = 120) were determined between basal diet (A) and dietary supplementation low (B), middle (C), and high (D) level E. ulmoides extract for 11 wk. When compared to A group, 2 percentage points elevation in laying rate was observed of D group. Significant up-regulation of immunoglobulin indexes and down-regulation of lipid related indexes in D group were also found if comparison with A group, suggesting that supplementation E. ulmoides extract at a relative high content benefited in immunity enhancing and blood-fat depressing. Meanwhile, obvious variation in albumen amino acids and yolk volatile compounds were inspected as dietary supplementation E. ulmoides extract, especially in D group, implied that the flavor of egg would change under high-level E. ulmoides extract treatment. Besides, villus height and villus height to crypt depth ratio of duodenum, jejunum, and ileum in D group were also significantly higher than that of in A group, indicating high-level E. ulmoides extract contributed to nutrient adsorption via intestinal histology changing. Moreover, the richness, diversity, and composition of gut microbiota in D group also significantly altered with a comparison of A group. These variation caused gut microbiota in D group major enriched in the KEGG pathway of insulin signing pathway, systemic lupus erythematosus, and bacterial invasion of epithelial cells, which were conducive to egg production elevation via facilitating nutrient adsorption, inflammation relieving, blood lipid amelioration, and insulin resistance alleviation. These results indicated that dietary supplementation E. ulmoides extract at high content could serve as a feed additive in the hens industry.

Effects of dietary supplementation with Ampelopsis grossedentata extract on production performance and body health of hens.

To investigate the potential of Ampelopsis grossedentata extract used as a feed additive, laying performance, egg quality, yolk cholesterol, plasma biochemical parameters, intestinal histology, and gut microbiota of hens (n = 60) were determined between basal diet (CK) and dietary supplementation with A. grossedentata extract (RT) for 11 weeks. The laying rate in RT group was 6.3 percentage points higher than in CK group together with feed conversion rate decreasing. Significant upregulation of immunoglobulin indexes and downregulation of lipid-related indexes in RT group were also found in comparison with CK group, suggesting that dietary supplementation with A. grossedentata extract benefited in immunity enhancing and blood-fat depressing. Meanwhile, the villus height in duodenum and villus height to crypt depth ratio in duodenum and jejunum of RT group were significantly higher than that of CK group, indicating that dietary supplementation with A. grossedentata extract facilitated nutrient adsorption via intestinal histology changing. Moreover, the richness, diversity, and composition of gut microbiota in RT group significantly altered with a comparison of CK group, including beneficial bacterium and pathogenic bacterium, revealing that dietary supplementation with A. grossedentata extract could modify gut microbiota communities to affect intestinal adsorption and pathogen invasion. In addition, the lipid metabolism-related insulin signing pathway was significantly enriched by gut microbiota in RT group, which were conducive to egg production elevation via facilitating blood lipid amelioration and insulin resistance alleviation. These results provided a basis for A. grossedentata extract served as a feed additive in the hen industry.

Output Consensus for Heterogeneous Linear Multiagent Systems With a Predictive Event-Triggered Mechanism.

In this paper, an output consensus problem for a heterogeneous linear multiagent system with a predictive event-triggered mechanism on directed graphs is investigated. An event-triggered consensus protocol is proposed by introducing an internal reference model for each agent to handle the heterogeneity existing in the system. With the proposed mechanism, each agent predicts its internal reference model's input by employing the estimate of the internal reference model's state differences between itself and its neighbor agents. As it considers the internal reference model's inputs of agents, the system requires far fewer event-triggered times to achieve consensus, leading to a significant reduction in communication cost among agents. A necessary and sufficient condition of the output consensus for the heterogeneous linear multiagent system is put forth. Furthermore, Zeno behavior can be ruled out for each agent. Some numerical examples are given to demonstrate the effectiveness of the proposed control mechanism.

Adsorption and desorption characteristics of polyphenols from Eucommia ulmoides Oliv. leaves with macroporous resin and its inhibitory effect on α-amylase and α-glucosidase.

BACKGROUND: Eucommia ulmoides Oliv. (EUO) was a traditional Chinese herb, its leaves were abundant in China, and polyphenol compounds were considered to be an important active ingredient in Eucommia ulmoides Oliv. leaves (EUOL). However, previous research mainly focused on compound identification and extraction process, there were few reported on the efficient enrichment process and biological activity evaluation of polyphenols in EUOL. METHODS: The adsorption and desorption characteristics of twelve different resins (HPD-100, HPD-300, HPD-600, D-3250, X-5, D-140, NKA-9, NKA-II, D-101, AB-8, S-8 and Polyamide) were investigated to develop an efficient method for the enrichment of polyphenol from EUOL, and the static adsorption, kinetics, isotherm and thermodynamics of the polyphenol from EUOL were analyzed. The eluted component was obtained through dynamic elution, and its main polyphenol compounds were detected by high-phase liquid chromatography (HPLC) and the inhibitory effects on the enzyme activity of α-amylase and α-glucosidase was also evaluated for different elution components. Meanwhile, the binding of main polyphenol compounds to enzyme was also evaluated. RESULTS: The selected resins (HPD-300, HPD-600, D-3250, X-5, D-140, NKA-9, D-101 and AB-8) showed adsorption patterns that fitted well to the pseudo second-order kinetics. The intra-particle diffusion model demonstrated that the diffusion of polyphenol compounds on these resins were divided into three processes. For HPD-300, HPD-600 and NKA-9, the Freundlich model better described the adsorption isotherm behavior than the Langmuir model, and the adsorption of polyphenol was a physical, exothermic, and spontaneous process. Subsequently, dynamic elution was performed yielding a higher polyphenol content in a 60% ethanol-water elution component, and it also exhibited a higher inhibitory effect on α-amylase and α-glucosidase activity. Furthermore, as the main polyphenol compounds, chlorogenic acid, rutin, quercetin and kaempferol were used to simulate the binding to the enzyme protein through molecular docking technology. The results showed that quercetin had a higher docking score for α-amylase, while rutin displayed superior binding to α-glucosidase. CONCLUSIONS: Therefore, polyphenols of EUOL could be enriched through macroporous resins and have the potential to be effective enzyme inhibitor.

DCN-MAC: A Dynamic Channel Negotiation MAC Mechanism for Underwater Acoustic Sensor Networks.

In the design of media access control (MAC) mechanism in underwater acoustic sensor networks (UASNs), due to the propagation characteristic of low-speed underwater acoustic signals, it is necessary to solve the spatial-temporal uncertainty problem. In order to avoid the multi-user access conflict in underwater networks, reduce the energy cost and improve the throughput and fairness across the network, a dynamic channel negotiation MAC mechanism based on spatial-temporal mapping of receiving queue (DCN-MAC) was proposed. DCN-MAC uses a duty cycle mechanism and implements a network management based on dynamic single node wake-up. The awakening node collects the request to send (RTS) and network status information in the network to solve the problem of space-temporal uncertainty and the highly dynamic needs of network access nodes and access services. The simulation results show that in different network scenarios, especially in those featuring high density and heavy network load, compared with the traditional underwater acoustic network MAC protocols, this protocol can effectively improve the network throughput and reduce the packet loss probability caused by multi-node conflict.

Data Uploading Strategy for Underwater Wireless Sensor Networks.

Underwater wireless sensor networks (UWSNs) have become a popular research topic due to the challenges of underwater communication. The existing mechanisms for collecting data from UWSNs focus on reducing the data redundancy and communication energy consumption, while ignoring the problem of energy-saving transmission after compression. In order to improve the efficiency of data collection, we propose a data uploading decision-making strategy based on the high similarity of the collected data and the energy consumption of the high similarity data compression. This decision-making strategy efficiently optimizes the energy consumption of the networks. By analyzing the data similarity, the quality of network communication, and uploading energy consumption, the decision-making strategy provides an energy-efficient data upload strategy for underwater nodes, which reduces the energy consumption in various network settings. The simulation results show that compared with several existing data compression and uploading methods, the proposed data upload methods has better energy saving effect in different network scenarios.

Dietary supplementation with the extract from Eucommia ulmoides leaves changed epithelial restitution and gut microbial community and composition of weanling piglets.

This study was conducted to compare the effects of Eucommia ulmoides leaves (EL) in different forms (EL extract, fermented EL, and EL powder) with antibiotics on growth performance, intestinal morphology, and the microbiota composition and diversity of weanling piglets. Compared to the control group, the antibiotics and EL extract significantly increased the average daily gain and decreased the feed: gain ratio as well as the diarrhea rate (P < 0.05). The EL extract significantly decreased the crypt depth and increased the ratio of villus height to crypt depth (P < 0.05), while the fermented EL group did the opposite (P < 0.05). The crypt depth in the antibiotics group was of similar value to the EL extract group, and was lower than the fermented EL and EL powder groups (P < 0.05). Compared to the control and antibiotics groups, the jejunul claudin-3 mRNA expression and the concentrations of total VFA, Chao 1, and ACE were significantly augmented in the EL extract group of piglets (P < 0.05). The EL extract groups also showed elevated Shannon (P < 0.05) and Simpson (P = 0.07) values relative to the control and antibiotics groups. At the phylum level, the EL extract group exhibited a reduced abundance of Bacteroidetes and an enhanced abundance of Firmicutes. At the genus level, the abundance of Prevotella was augmented in the EL extract group. Moreover, compared with the antibiotic group, the acetate concentration was enhanced in the EL extract and fermented EL groups. Overall, dietary supplementation with the EL extract, but not the fermented EL or EL powder, improved growth performance, jejunul morphology and function, as well as changed colonic microbial composition and diversity, which might be an alternative to confer protection against weanling stress in weanling piglets.

A Glider-Assisted Link Disruption Restoration Mechanism in Underwater Acoustic Sensor Networks.

Underwater acoustic sensor networks (UASNs) have become a hot research topic. In UASNs, nodes can be affected by ocean currents and external forces, which could result in sudden link disruption. Therefore, designing a flexible and efficient link disruption restoration mechanism to ensure the network connectivity is a challenge. In the paper, we propose a glider-assisted restoration mechanism which includes link disruption recognition and related link restoring mechanism. In the link disruption recognition mechanism, the cluster heads collect the link disruption information and then schedule gliders acting as relay nodes to restore the disrupted link. Considering the glider's sawtooth motion, we design a relay location optimization algorithm with a consideration of both the glider's trajectory and acoustic channel attenuation model. The utility function is established by minimizing the channel attenuation and the optimal location of glider is solved by a multiplier method. The glider-assisted restoration mechanism can greatly improve the packet delivery rate and reduce the communication energy consumption and it is more general for the restoration of different link disruption scenarios. The simulation results show that glider-assisted restoration mechanism can improve the delivery rate of data packets by 15-33% compared with cooperative opportunistic routing (OVAR), the hop-by-hop vector-based forwarding (HH-VBF) and the vector based forward (VBF) methods, and reduce communication energy consumption by 20-58% for a typical network's setting.

Asymmetric Hearing Loss in Chinese Workers Exposed to Complex Noise.

OBJECTIVES: Evaluate the audiometric asymmetry in Chinese industrial workers and investigate the effects of noise exposure, sex, and binaural average thresholds on audiometric asymmetry. DESIGN: Data collected from Chinese industrial workers during a cross-sectional study were reanalyzed. Of the 1388 workers, 266 met the inclusion criteria for this study. Each subject underwent a physical examination and an otologic examination and completed a health-related questionnaire. χ and t tests were used to examine the differences between the asymmetric and symmetric hearing loss groups. RESULTS: One hundred thirty-one subjects (49.2%) had a binaural hearing threshold difference of 15 dB or more for at least one frequency, and there was no statistically significant difference between the left and right ears. The asymmetric hearing loss group was not exposed to higher cumulative noise levels (t = 0.522, p = 0.602), and there was no dose-response relation between asymmetry and cumulative noise levels (χ = 6.502, p = 0.165). Men were 1.849 times more likely to have asymmetry than women were (95% confidence interval, 1.051 to 3.253). Among the workers with higher high-frequency hearing thresholds, audiometric asymmetry was 1.024 times more prevalent than that among those with lower high-frequency hearing thresholds (95% confidence interval, 1.004 to 1.044). CONCLUSIONS: The results indicated that occupational noise exposure contributed minimally to asymmetry, whereas sex and binaural average thresholds significantly affected audiometric asymmetry. There was no evidence that the left ears were worse than the right ears.

EFPC: An Environmentally Friendly Power Control Scheme for Underwater Sensor Networks.

In oceans, the limited acoustic spectrum resource is heavily shared by marine mammals and manmade systems including underwater sensor networks. In order to limit the negative impact of acoustic signal on marine mammals, we propose an environmentally friendly power control (EFPC) scheme for underwater sensor networks. EFPC allocates transmission power of sensor nodes with a consideration of the existence of marine mammals. By applying a Nash Equilibrium based utility function with a set of limitations to optimize transmission power, the proposed power control algorithm can conduct parallel transmissions to improve the network's goodput, while avoiding interference with marine mammals. Additionally, to localize marine mammals, which is a prerequisite of EFPC, we propose a novel passive hyperboloid localization algorithm (PHLA). PHLA passively localize marine mammals with the help of the acoustic characteristic of these targets. Simulation results show that PHLA can localize most of the target with a relatively small localization error and EFPC can achieve a close goodput performance compared with an existing power control algorithm while avoiding interfering with marine mammals.

An energy-efficient underground localization system based on heterogeneous wireless networks.

A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners' should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on high speed Industrial Ethernet is deployed. Since the mobile wireless nodes are working in an irregular tunnel, a specific wireless propagation model cannot fit all situations. In this paper, an underground localization system is designed to enable the adaptation to kinds of harsh tunnel environments, but also to reduce the energy consumption and thus prolong the lifetime of the network. Three key techniques are developed and implemented to improve the system performance, including a step counting algorithm with accelerometers, a power control algorithm and an adaptive packets scheduling scheme. The simulation study and experimental results show the effectiveness of the proposed algorithms and the implementation.

Comparison of two dose-response relationship of noise exposure evaluation results with high frequency hearing loss.

BACKGROUND: Complex noise and its relation to hearing loss are difficult to measure and evaluate. In complex noise measurement, individual exposure results may not accurately represent lifetime noise exposure. Thus, the mean L Aeq,8 h values of individuals in the same workgroup were also used to represent L Aeq,8 h in our study. Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did. METHODS: A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China. We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times, respectively. A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance. RESULTS: We observed that 88.3% of workers were exposed to more than 85 dB(A) of occupational noise (mean: 89.3 ± 4.2 dB(A)). The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A), respectively. In the binary logistic regression analysis, we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable. The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable. Furthermore, we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was. The CNEg model was better than the CNEp model. In this circumstance, we can measure some subjects instead of the whole workgroup and save manpower. CONCLUSIONS: In a complex noise environment, the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.

Effect of cigarette smoking on noise-induced hearing loss in workers exposed to occupational noise in China.

Excessive exposure to high noise level environments has the potential to cause noise-induced hearing loss (NIHL), and cigarette smoking has also been shown to have a potential adverse effect on hearing. The aim of this study was to determine whether smoking interacts with noise in the development of hearing loss, and if so, the extent of the contribution from smoking on NIHL. A cross-sectional study was designed to assess the effect of smoking on NIHL in 517 male workers (non-smokers: N = 199; smokers: N = 318) exposed to a high-level industrial noise environment in China. Shift-long temporal waveforms of the noise that workers were exposed to for evaluation of noise exposures, and audiometric threshold measures were obtained on all selected subjects. The subjects used hearing protection devices only within the last 1-2 years. The results suggest that smoking has an adverse effect on NIHL in workers exposed to high level industrial noise, i.e., the median high frequency hearing thresholds were significantly greater in smokers than non-smokers exposed to noise for more than 10 years. This effect was observed at 4.0 and 6.0 kHz. Smoking did not have an adverse effect on NIHL in workers exposed to noise less than 10 years. Multivariate regression analysis revealed that the odds ratio (OR) for high frequency hearing loss (i.e., hearing threshold greater than 40 dB at 4.0 kHz) were 1.94 for smokers in comparison to non-smokers. The results suggest that: (1) smokers have a higher risk of developing high frequency hearing loss than non-smokers with a similar occupational noise exposure, and (2) the interaction between cigarette smoking and high-level noise exposure may be additive. There is a need to develop and analyze a larger database of workers with well-documented exposures and smoking histories for better understanding of the effect of smoking on NIHL incurred from high-level industrial noise exposures. A better understanding of the role of smoking may lead to its incorporation into hearing risk assessment for noise exposure.

Noise exposure assessment with task-based measurement in complex noise environment.

BACKGROUND: Task-based measurement (TBM) is a method to assess the eight-hour A-weighted equivalent noise exposure level (L(Aeq.8h)) besides dosimeter. TBM can be better used in factories by non-professional workers and staffs. However, it is still not clear if TBM is equal or similar with dosimeter for L(Aeq.8h) measurement in general. This study considered the measurement with dosimeter as real personal noise exposure level (PNEL) and assessed the accuracy of TBM by comparing the consistencies of TBM and dosimeter in L(Aeq.8h) measurement. METHODS: The study was conducted in one automobile firm among 387 workers who are exposed to unstable noise. Dosimeters and TBM were used to compare the two strategies and assess the degree of agreement and causes of disagreement. Worker's PNEL was measured via TBM for noise; the real PNEL was also recorded. The TBM for noise was computed with task/position noise levels measured via sound level meter and workers' exposure information collected via working diary forms (WDF) filled by participants themselves. Full-shift noise exposure measurement via personal noise dosimeters were taken as the real PNEL. General linear model (GLM) was built to analyze the accuracy of TBM for noise and the source of difference between TBM for noise and real PNEL. RESULTS: The L(Aeq.8h) with TBM were slightly higher than the real PNELs, except the electricians. Differences of the two values had statistical significance in stamping workers (P < 0.001), assembly workers (P = 0.015) and welding workers (P = 0.001). The correlation coefficient of L(Aeq.8h) with TBM and real PNELs was 0.841. Differences of the two results were mainly affected by real PNEL (F = 11.27, P = 0.001); and work groups (F = 3.11, P < 0.001) divided by jobs and workshops were also independent factors. PNEL of workers with fixed task/position ((86.53 ± 8.82) dB(A)) was higher than those without ((75.76 ± 9.92) dB(A)) (t = 8.84, P < 0.01). Whether workers had fixed task/position was another factor on the accuracy of TBM for noise (F = 4.36, P = 0.038). CONCLUSION: TBM for noise has acceptable accuracy on workers' PNEL measurement. The accuracy is affected by job categories, workshops and variability of task/position. TBM for noise can yield a relatively conservative result of worker's PNEL in most cases, so it can be used to measure and assess workers' real PNEL.

Microwave-accelerated derivatization prior to GC-MS determination of sex hormones.

A new microwave-accelerated derivatization method was developed for rapid determination of 13 natural sex hormones in feeds. Sex hormones were isolated from the sample matrix by ultrasonic extraction, followed by solid-phase extraction, derivatized under microwave irradiation, and then analyzed directly by gas chromatography-mass spectrometry (GC-MS) in selective ion monitoring (SIM) mode. The key parameters affecting derivatization efficiency, including microwave irradiation time, microwave power, and reaction solvent were studied. Under microwave power of 360 W and microwave irradiation for 3 min, 13 natural sex hormones were simultaneously derivatized using heptafluorobutyric acid anhydride (HFBA) as derivatization reagent. This method was applied to the determination of 13 natural sex hormones in different feed samples, and the obtained results were compared with those obtained by the traditional thermal derivatization. The recoveries from 58.1 to 111% were obtained at sex hormone concentrations of 10-300 µg/kg with RSDs ≤12.0%. The results showed that the proposed method was fast, simple, efficient and can be applied to the determination of 13 natural sex hormones in different feed samples.

[Risk factors analysis of low back pain among workers in a foundry factory of the automobile company].

OBJECTIVE: To study the main risk factors of low back pain of workers ina foundry factory of the automobile company using cross sectional epidemiological investigation, and to provide scientific base for preventing the disorder. METHODS: The low back pain and work loads of 1340 workers in a foundry factory of the automobile company were investigated using questionnaire, and logistic regression analysis was used to analyze the risk factors. RESULTS: The one-year morbidity of low back pain in workers was 58.9% the morbidities of low back pain in workers engaged in foundry, transportation and modeling were 64.6%, 64.6% and 62.5%, respectively. The lifting with squat postures, bending trunk heavily, bending trunk with twisting and moving the heavy objects were found to be the most dominant risk factors for low-back pain, the OR values were 2.085, 1.961, 1.967 and 1.956, respectively. The distributions of risk factors were different among the different jobs. The logistic regression analysis showed that moving the heavy objects, lifting with squat postures, bending trunk heavily, bending trunk with twisting existed simultaneously, also the work years and gender were the risk factors. CONCLUSION: The manual moving heavy objects, awkward working posture or both were the most important risk factors for low-back pain. The intervene ergonomic study should be performed in future to reduce the morbidity of low-back pain.

Determination of fluoroquinolones in blood by matrix solid-phase dispersion extraction and CE.

A simple and rapid method for the determination of residues of four fluoroquinolones in blood samples was developed. The method was based on matrix solid-phase dispersion extraction followed by CE with ultraviolet detection. 1-Butyl-3-methylimidazolium tetrafluoroborate aqueous solution was used as the background electrolyte for the separation of fluoroquinolones. The average recoveries of the four fluoroquinolones at two spiked levels ranged from 54.0 to 86.4% for pig blood, and 45.4 to 79.9% for deer blood, with the relative standard deviations <9.45%. Detection limits for the four fluoroquinolones in blood sample ranged from 0.15 to 0.31 µg/mL.