Efficient one-pot synthesis of n-butyl levulinate from carbohydrates catalyzed by Fe_2(SO_4)_3

Butyl levulinate（BL） is a promising new candidate as diesel fuel and fuel additive. In this study, an efficient process for a one-pot synthesis of BL from biomass-derived carbohydrates in butanol medium with the catalysis of metal sulfates was developed. The catalytic activity of a series of metal sulfates for the synthesis of BL from fructose was investigated. Among various metal sulfates, ferric sulfate Fe（SO）was found to be the most efficient catalyst, which gave a remarkably high BL yield of 62.8 mol% under the conditions of 463 K, 3 h, a catalyst dosage of 5.0 g/L, and fructose concentration of 25 g/L. Different carbohydrates including glucose, cellulose, inulin and sucrose were also used for one-pot synthesis of BL with the catalysis of Fe（SO）, showing the yields of 39.6, 30.5, 56.6 and 50.1 mol%, respectively. In addition,the recycling and reuse of Fe（SO）was studied by characterizing them using powder X-ray diffraction（XRD）, scanning electron microscope（SEM）, X-ray photoelectron spectroscopy（XPS）. A plausible reaction pathway for the one-pot synthesis of BL from fructose was proposed. This study provides a facile and feasible way for the synthesis of BL from biomass.

HIV/AIDS related perception and behavior: A comparative study among college students of different majors in China

Objective:In order to carry out proper education and intervention of AIDS based on different features and demands of different majors,this study aimed to compare the difference of college students from six majors in China in the aspects of AIDS-related knowledge,attitudes and behaviors.Methods:A questionnaire survey was carried out among 18,644 students in 30 colleges/universities from 9 provinces of China,who were recruited through stratified cluster sampling.AIDS-related knowledge,attitude,condom-use intention,self-efficacy and sexual behavior of these students were investigated.Results:AIDS-related knowledge level of students majoring in education was the lowest while that of medical students was the highest as well as highest self-efficacy of condom use.Students of music or fine arts had the strongest intention to use condoms,while the students majoring in education had the weakest.The sexually active percentages of male students from different majors ranked as follows:music or fine arts(29.5%),minority nationality(12.2%),science&tech(10.9%),medicine(10.6%),educationmajor(10.0%),and liberal arts(8.2%).Among female students,the rank was music or fine arts(11.0%),science&tech(6.2%),education-major school(4.5%),minority nationality(4.5%),liberal arts(4.1%),and medicine(2.8%).Conclusion:It is urgent to enhance proper AIDS-related education and intervention based on the features and demands of students from different majors or universities,for example,to enhance comprehensive AIDS prevention education among students major in education and to increase behavioral skills to prevent sexually transmitted diseases among students from colleges or faculty of music or fine arts.

A novel surface molecularly imprinted polymer as the solid-phase extraction adsorbent for the selective determination of ampicillin sodium in milk and blood samples

Surface molecularly imprinted polymers （SMIPs） for selective adsorption of ampicillin sodium were synthesized using surface molecular imprinting technique with silica gel as a support. The physical and morphological characteristics of the polymers were investigated by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravimetric analysis （TGA）, elemental analysis and nitrogen adsorption-desorption test. The obtained results showed that the SMIPs displayed great adsorption capacity （13.5 lag/mg）, high recognition ability （the imprinted factor is 3.2） and good binding kinetics for ampicillin sodium. Finally, as solid phase extraction adsorbents, the SMIPs coupled with HPLC method were validated and applied for the enrichment, purification and determination of anapicillin sodium in real milk and blood samples. The averages of spiked accuracy ranged from 92.1% to 107.6%. The relative standard deviations of intra- and inter-day precisions were less than 4.6%. This study provides a new and promising method for enriching, extracting and determining ampicillin sodium in complex biological samples.

Separation and enrichment of trace ractopamine in biological samples by uniformly-sized molecularly imprinted polymers

In order to prepare a high capacity packing material for solid-phase extraction with specific recognition ability of trace ractopamine in biological samples, uniformly-sized, molecularly imprinted polymers （MIPs） were prepared by a multi-step swelling and polymerization method using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and toluene as a porogen respectively. Scanning electron microscope and specific surface area were employed to identify the characteristics of MIPs. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, Scatchard analysis and kinetic study were performed to interpret the specific recognition ability and the binding process of MIPs. The results showed that, compared with other reports, MIPs synthetized in this study showed high adsorption capacity besides specific recognition ability. The adsorption capacity of MIPs was 0.063 mmol/g at 1 mmol/L ractopamine concentra- tion with the distribution coefficient 1.70. The resulting MIPs could be used as solid-phase extraction materials for separation and enrichment of trace ractopamine in biological samples.

Evaluation on the natural gas hydrate formation process

Gas hydrates have endowed with great potential in gas storage,and rapid formation of gas hydrates is critical to use this novel technology.This work evaluated the natural gas hydrate formation process,which was compared from six parameters,including conversion of water to hydrate,storage capacity,the rate of hydrate formation,space velocity(SV)of hydrate reaction,energy consumption and hydrate removal.The literature was selected by analyzing and comparing these six parameters mentioned above,meanwhile placing emphasis on the three parameters of storage capacity,the rate of hydrate formation and space velocity of hydrate reaction.Through analysis and comparison,four conclusions could be obtained as follows.Firstly,the overall performance of the stirring process and the spraying process were better than other processes after analyzing the six parameters.Secondly,the additive types,the reactor structure and the reactor size had influence on the natural gas hydrate formation process.Thirdly,the energy consumption via reciprocating impact in the hydrate formation process was higher than that via stirring,spraying and static higee.Finally,it was one key for hydrate removal to realize the hydrate industrial production.

Preparation and evaluation of monolithic molecularly imprinted stationary phase for S-naproxen

An S-naproxen（S-NAP）molecularly imprinted monolithic stationary phase（MIMSP）with specific recognition for S-NAP and naproxen（NAP）was prepared by in situ technique,utilizing 4-vinylpridine（4-VP）as a function monomer,ethylene glycol dimethacrylate（EDMA）as a cross-linking agent,and low-polar solvents（toluene and dodecanol）as porogenic solvents.The selectivity of the polymers for S-NAP and NAP was evaluated by high performance liquid chromatography（HPLC）.The binding characteristics were tested by Scatchard analysis.Racemic NAP could be specifically separated to some extent.At the same time,NAP could be separated from ibuprofen under optimized conditions.Scatchard analysis showed that two classes of binding sites existed in the S-NAP-imprinted polymers,with their dissociation constants estimated to be 1.045 and 5.496 μM,respectively.The results demonstrate that S-NAP and NAP can be recognized specifically on the obtained MIMSP.

Effectiveness of a workplace-based multicomponent intervention to improve hypertension control among Chinese working population:a cluster-controlled trial

Objective To determine whether a workplace-based multicomponent intervention strategy could improve BP control among Chinese working population.Methods A cluster-controlled trail,with workplaces assigned to either the intervention or control group.60 workplaces across 20 urban regions of China were selected.4,548 hypertensive employees aged 18-60 years were assigned intervention(n=3,470)or control(n=1,078),of whom 4,205(92.5%;intervention,n=3,209;control,n=996)were included in this analysis.

Research on the Origin of Mongolian Medicine Veratrum nigrum L.and Its Recent Research Progress

On the basis of research on the origin of Mongolian medicine Veratrum nigrum L.,this paper summarizes the research situation of Mongolian medicine Veratrum nigrum L.from the aspects of clinical application,chemical composition,pharmacological action and toxicological action,so as to provide a reference basis for further research and further development and utilization of Mongolian medicine.

Teaching Strategy on Diagnosing and Removing Automobile’s Failure

:This article first analyzes the problems existing in the teaching about diagnosing and removing automobile’s failure,and then discusses some specific teaching strategies on diagnosing and removing automobile’s failure to provide some effective reference for the related staff.

Urban-Rural Disparity in Mortality Patterns of Respiratory Diseases Among Older Adults—China,1987-2021

What is already known about this topic?Respiratory diseases(RDs)are the primary cause of death in older adults in China.However,there is limited evidence regarding the disparity in mortality rates of RDs between urban and rural areas among the elderly population.What is added by this report?The age-standardized mortality rate(ASMR)due to RDs in the elderly population in both urban and rural areas of China has shown a consistent decrease.This trend is observed in both males and females.However,there was no significant change in the average annual percentage of ASMR for pneumonia among the urban elderly population and rural elderly men throughout the study period.What are the implications for public health practice?Efforts should be made in China to reduce mortality from chronic lower respiratory disease and pneumonia among the elderly,particularly in urban populations.

Limited Social Support,but Comparable Health Literacy and Service Utilization,Among Elderly People Living Alone—Six PLADs,China,May-September 2020

What is already known about this topic?The proportion of elderly living alone in China is approximately 10%.Living away from family poses enormous challenges for older adults.What is added by this report?Compared to those living with family,elderly individuals living alone exhibit a lower registration rate with general practitioners and have less social support.What are the implications for public health practice?While the current health service system for elderly people living alone is working relatively well,there is a need for additional programs to enhance social support and improve their social well-being.

Recognition and localization system of the robot for harvesting Hangzhou White Chrysanthemums

To realize the robotic harvesting of Hangzhou White Chrysanthemums,the quick recognition and 3D vision localization system for target Chrysanthemums was investigated in this study.The system was comprised of three main stages.Firstly,an end-effector and a simple freedom manipulator with three degrees were designed to meet the quality requirements of harvesting Hangzhou White Chrysanthemums.Secondly,a segmentation based on HSV color space was performed.A fast Fuzzy C-means(FCM)algorithm based on S component was proposed to extract the target image from irrelevant background.Thirdly,binocular stereo vision was used to acquire the target spatial information.According to the shape of Hangzhou White Chrysanthemums,the centroids of stamens were selected as feature points to match in the right and left images.The experimental results showed that the proposed method was able to recognize Hangzhou White Chrysanthemums with the accuracy of 85%.When the distance between target and baseline was 150-450 mm,the errors between the calculated and measured distance were less than 14 mm,which could meet the requirements of the localization accuracy of the harvesting robot.

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents:A comparative study of waste-polymer-based,coal-based activated carbon,and carbon nanotubes

Adsorption of the hydrophobic organic compounds （HOCs） trichloroethylene （TCE）, 1,3-dichlorobenzene （DCB）, 1,3-dirdtrobenzene （DNB） and y-hexachlorocyclohexane （HCH） on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon （F400） and multiwalled carbon nanotubes （MWNT）. The polymer- based activated carbons were prepared using KOH activation from waste polymers： polyvinyl chloride （PVC）, polyethyleneterephthalate （PET） and tire rubber （TR）. Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area （2700 m2/g） and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.

太阳能CO_2煤气化反应器玻璃窗清洁度的数值模拟

太阳能二氧化碳煤气化拥有减少CO_2排放,清洁、节能地制取高品质高纯度气体燃料的优点.作为太阳能热化学制备清洁燃料的核心部件,旋风流反应器便于输运、液态排渣、效率高、易实现,然而直接式反应器的一个主要问题是煤颗粒会沾染反应器玻璃窗口,影响反应器效率和安全性.针对三维直接辐照旋流太阳热化学反应器,并考虑能流椭球型分布及聚光边界条件,本文采用欧拉-拉格朗日方法建立了气固两相流数学模型并耦合煤颗粒、气体的参与性介质辐射和化学反应动力学模型.与苏黎世联邦理工学院的实验结果对比验证之后,研究了CO_2进气质量流量配比和煤颗粒质量流量对石英玻璃窗表面沉积煤颗粒的影响规律.计算结果表明,保持玻璃窗口清洁主要取决于进气质量流量配比,当CO_2与煤颗粒的摩尔比在1.3～1.8的范围内,腔体、清扫玻璃和输送煤颗粒气体质量流量分别占总CO_2进气质量流量的范围为71.9%～78.2%,15.7%～20.7%和5%～10%,玻璃窗口清洁度最优.煤颗粒质量流量对石英玻璃窗表面沉积煤颗粒的影响不大,但会显著影响煤颗粒运动轨迹.

Segmentation algorithm for Hangzhou white chrysanthemums based on least squares support vector machine

In order to realize the visual positioning for Hangzhou white chrysanthemums harvesting robot in natural environment,a color image segmentation method for Hangzhou white chrysanthemum based on least squares support vector machine(LS-SVM)was proposed.Firstly,bilateral filter was used to filter the RGB channels image respectively to eliminate noise.Then the pixel-level color feature and texture feature of the image,which was used as input of LS-SVM model(classifier)and SVM model(classifier),were extracted via RGB value of image and gray level co-occurrence matrix.Finally,the color image was segmented with the trained LS-SVM model(classifier)and SVM model(classifier)separately.The experimental results showed that the trained LS-SVM model and SVM model could effectively segment the images of the Hangzhou white chrysanthemums from complicated background taken under three illumination conditions such as front-lighting,back-lighting and overshadow,with the accuracy of above 90%.When segmenting an image,the SVM algorithm required 1.3 s,while the LS-SVM algorithm proposed in this paper just needed 0.7 s,which was better than the SVM algorithm obviously.The picking experiment was carried out and the results showed that the implementation of the proposed segmentation algorithm on the picking robot could achieve 81%picking success rate.

Coal fly ash reinforcement for the property enhancement of crude glycerol-based polyurethane foam composites

Coal fly ash(CFA)is the main combustion residue of fine ground coal in the process of coal-fired thermal power generation,and crude glycerol(CG)is the byproduct of biodiesel production.The novel polyurethane/CFA(PU/CFA)foam composites were prepared from CFA and CG.Two kinds of CFA,CFAI and CFAII were used as fillers for the property enhancement of PU/CFA composites,and the effects on foaming behavior and the reinforcement for the PU/CFA composites were investigated.It was found that the addition of CFA can prolong the rising time and tack-free time,and the maximum rising time and tack-free time increased to 40 s and 42 s.Meanwhile,the maximum compressive strength of PU/CFAI and PU/CFAII increased to 0.2186 MPa and 0.2284 MPa with the addition of CFA.The thermogravimetric analysis showed that the PU/CFA composites underwent three stages of thermal decomposition,and the amount of carbon residue increased from 23.11%to 67.91%with increasing CFA dosage.Moreover,the values of the limit oxygen index increased from 21.5%to 23.7%with the incorporation of CFA into the PU foam matrix,indicating that CFA improved the thermal stability and flame retardant performance of the composites.This study provided a new method for the recycling and high-value utilization of CG and CFA.

Quantitative computed tomography measurement of cross-sectional area of small pulmonary vessels in asthmatic patients

Background: Cross-sectional area (CSA) for small pulmonary vessels is considered a parameter of pulmonary vessel alterations in patients with chronic obstructive pulmonary disease. This study was to evaluate the correlation of CSA with airflow obstruction parameters in asthma. Furthermore, we aimed to measure the difference in vascular alteration between asthma phenotypes and evaluate its relation with cytokine levels. Methods: We consecutively enrolled 20 adult asthmatic patients (13 women: age range, 26–80 years) and 20 healthy controls (8 women: age range, 23–61 years) from Peking University Third Hospital. Total CSA <5 mm2 (CSA<5) was measured with 64-slice spiral computed tomography, and the percentage CSA <5 for the lung area (%CSA<5) was calculated. Data were corrected for body surface area to obtain sixth-generation airway luminal diameter (LDcor), luminal area (Aicor), and airway wall thickness, and airway wall area percentage (WA%) was calculated. Enzyme-linked immunosorbent assay was used to detect the expression of leptin, total immunoglobulin E, periostin, and transforming growth factor β1 in serum and matrix metalloproteinase 9 in induced sputum supernatant of asthmatic patients. The differences in %CSA<5 between subgroups were assessed by independent samples Student's t test, and Spearman correlation analysis was used to analyze the correlation of %CSA<5 with clinical indexes and inflammatory cytokine levels. Results: Patients with asthma and controls did not differ in %CSA<5. In asthma patients,%CSA<5 was lower with initial onset age ≤12 years old, airflow restriction and uncontrolled Global Initiative for Asthma classification (all P < 0.05). Moreover, it was positively correlated with forced vital capacity ratio in 1 s (FEV1)/forced expiratory volume ratio, FEV1%, LDcor, Aicor, and serum leptin level (all P < 0.05) and negatively with total lung WA%(P = 0.007). Conclusions:%CSA<5 of pulmonary small vessels was well correlated with airflow limitation indexes and sixth-generation airway parameters. It has certain significance in predicting the clinical control of asthma.

Effective degradation of tetracycline by mesoporous Bi2WO6 under visible light irradiation

Bi2WO6 was synthesized with a hydrothermal method at different pHs and used for the degradation of tetracycline （TC） in water. The mesoporous BiEWO6 prepared at pH 1 （BWO-1） displayed the highest adsorption and degradation capacity to TC due to its large surface area and more efficient capacity to separate photogenerated electrons and holes. 97% of TC at 20 mg · L-1 was removed by BWO-1 at 0.5 g-L-1 after 120min irradiation under simulated solar light. Only 31% of the total organic carbon （TOC） was removed after 360 min irradiation although the TC removal reached 100%, suggesting that TC was mainly transformed to intermediate products rather than completely mineralized. The inter- mediates were identified by high-performance liquid chromatography-time of flight-mass spectrometry （HPLC-TOF-MS） and possible photodegradation path- ways were proposed.

Sphingolipid profiles and their relationship with inflammatory factors in asthmatic patients of different sexes

Background:Asthma is a heterogeneous disease with distinct prevalence and manifestation between sexes.This study was to identify sex-specific features of asthma via metabolomic analysis of sphingolipids.Methods:Forty-two asthma patients(27 women and 15 men)admitted to the Peking University Third Hospital from January 2015 to December 2015 were enrolled.Peripheral venous blood was collected for metabolomic analysis by targeted liquid chromatography-mass spectrometry.Sex hormones(estradiol,progesterone,testosterone,and androstenedione)and multiple inflammatory factors(periostin,leptin,IgE,IL-4,IL-5,IL-10,IL-13,IL-17A,and IFN-γ)were also assessed.The eosinophil percentage in induced sputum was also detected.All these data were applied to comparative analysis between sexes.Results:Testosterone was negatively related to periostin(ρ=-0.420,P=0.009)and IL-5(ρ=-0.540,P=0.012),while estradiol was positively related to the blood eosinophil percentage(ρ=0.384,P=0.025).Among the eighteen species of sphingolipids detected in the 42 patients,five ceramide(Cer)species(Cer16:0,Cer:20:0,Cer22:0,Cer24:0,and Cer26:0)and one sphingomyelin(SM)species(SM38:0)were significantly higher in male than in female patients.Further investigation found that the correlation between Cer20:0 and IL-5 was positive in males(ρ=0.943,P=0.005)but negative in females(ρ=-0.561,P=0.030).Conclusions:Testosterone was negatively correlated with eosinophil inflammatory factors,but estradiol was positively correlated.Male asthma patients had higher ceramide and sphingomyelin levels than female patients.Different sexes had opposite correlations with ceramide and IL-5,respectively,suggesting that therapeutic strategies targeting ceramide should be different between sexes.