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To study the antioxidant activity of polysaccharides from Dendrobium officinale, the polysaccharide was extracted and purified from Dendrobium officinale, and its preliminary structure was characterized. Free radical scavenging activity and inhibition of low density lipoprotein (LDL) in vitro oxidation of Dendrobium officinale polysaccharides were evaluated. The results showed that the total sugar content of the obtained Dendrobium officinale polysaccharide was 90.17%±3.90%, the protein content was 0.14%±0.05%, the ash content was 4.47%±1.42% and the glucuronic acid content was 2.53%±1.02%, the relative molecular weight was 23970 Da and the monosaccharides were mainly mannose and glucose in this test. Dendrobium officinale polysaccharide had certain free radical scavenging capacity. It could inhibit the production of conjugated diene in the oxidative modification system of LDL. The inhibition rate of thiobarbituric acid reactive substances (TBARS) by copper ion reached 57.46%±0.56% when the polysaccharide concentration was 3.00 mg·mL−1. This study could provide theoretical support for the development of drugs for diseases such as arteriosclerosis due to LDL oxidation.

【Objective】The research aims to investigate the effects of nitrogen application rates on growth, yield, output value and quality of cigar in order to provide a basis for rational application of nitrogen fertilizer in cigar filler planting in Shifang, Sichuan Province.【Method】With Dexue 3 (cigar filler) as material, the variation characteristics of agronomic characters, yield, output value, physical quality and chemical composition of tobacco plants under different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg/hm2, which were recorded as N0, N60, N120, N150, N180 and N240, respectively) were analyzed by field experiment.【Result】Nitrogen application rate had little effect on agronomic character indexes of cigar at topping stage (44 days after transplanting). With the increase of nitrogen application rate, the yield and output value of tobacco leaves increased rapidly at first, then the yield increased slowly, and the output value decreased instead of increasing. Compared with N0 treatment, the yield and output value of nitrogen treatment obviously increased by 11.62%-57.62% and 10.11%-45.83%, respectively. Among them, the highest yield of tobacco leaves under N240 treatment was 2 737.18 kg/hm2, while the highest output value of tobacco leaves under N180 treatment was 99 834.63 yuan/hm2, both higher than those under N150 treatment, but there was no significant difference between treatments. With the increase of nitrogen application rate, the proportion of high-quality grade 1 and grade 2 tobacco leaves increased first and then decreased, while the proportion of lowquality grade 3 and lowest grade tobacco leaves presented an opposite trend, among which grade 1 and grade 2 tobacco leaves under N120 and N150 treatments accounted for the largest proportion, both reaching more than 80%. The comprehensive scores of physical quality and chemical composition of cigar leaves increased first and then decreased with the increase of nitrogen application rate. Among them, the coordination of physical quality and chemical composition of tobacco leaves treated with N120 was relatively better, and the comprehensive scores of physical quality and chemical composition of tobacco leaves were the highest, which were 8.58 and 7.58, respectively,【Conclusion】Suitable nitrogen application rate can increase the yield and output value of cigar tobacco, increase the proportion of high-quality tobacco, improve the physical quality of tobacco, and coordinate the chemical composition. Considering the yield, output value and quality of tobacco leaves, the reasonable nitrogen application rate of cigar filler in Shifang of Sichuan Province is 120-150 kg/hm2.

To construct the near infrared spectrum model of acid ester content in Baijiu (Chinese Liquor) and detect rapidly the acid ester content in Baijiu. The chemical value of acid ester content in Baijiu was determined by reflux and acid-base titration, which was combined with the near-infrared spectra of 1 mm and 8 mm optical path colorimetric cell of Baijiu, and the near-infrared spectrum model of acid ester content in Baijiu was established by internal cross test and external independent verification test. The results showed that acid ester content in Baijiu had special absorption to near infrared spectroscopy (NIR). The processing method and the best band of 1 mm optical path colorimetric cell were first derivative and 9400~5448 cm−1, and the processing method and the best band of 8 mm optical path cell were first derivative and 9400~7500 cm−1 and 6100~5448 cm−1. The coefficient of determination (R2) between the NIR predicted values and the chemical true values of acid ester content in 1 mm and 8 mm optical path colorimetric cells were 99.18% and 96.62%, and the correction standard deviation (RMSECV) were 0.989 mmol/L and 1.980 mmol/L. The coefficient of determination (R2) of external independent verification model between the predicted values and the chemical true values was 99.45%, and the prediction standard deviation (RMSEP) was 0.819 mmol/L. The results showed that the NIR model built by 1 mm optical path colorimeter cell had good prediction ability and could meet the requirements of rapid detection of acid ester content in Baijiu.

In order to improve the surface properties of hot work mold steel, the influence and mechanism of laser quenching, plasma nitriding and laser quenching/plasma nitriding composite treatment process on the friction, wear and corrosion resistance of the modified layer of H13 steel were studied. The surface morphology, surface chemical composition and microstructure of samples with different heat-treated were characterized by optical microscope, scanning electron microscope and energy dispersive spectrometer. Results showed that the composite treatment process could significantly improve the friction and wear resistance of the modified layer, and improve the corrosion resistance of the material surface. Compared with the single laser quenching and single nitriding treatment, the average friction coefficient of the modified layer after composite treatment declined significantly, the self-corrosion potential was remarkably increased, which indicated that the wear resistance and corrosion resistance of the modified layer after composite treatment were improved dramatically.

Objective: To investigate the mastery status of standard diagnosis and treatment of Helicobacter pylori (Hp) infection among general practitioners in Pudong New Area of Shanghai and its influencing factors. Methods: From January to May in 2021, 348 general practitioners from 24 community health service centers in Pudong New Area were selected by using stratified random sampling method. A self-made questionnaire (full score of 30) was used to investigate the general practitioners′ mastery of Hp infection diagnosis, treatment and prevention. According to the scores, they were divided into poor mastery group (0-10 points), moderate mastery group (11-20 points) and good mastery group (21-30 points), and the differences among the groups were compared. Results: A total of 320 valid questionnaires were collected in this survey, and the general practitioners′ mastery of standard diagnosis and treatment of Hp infection was at a high level, with an average score of 21.69. There were 116 people in the moderate mastery group, accounting for 36.25%, with an average score of 17.53 points. There were 204 people in the good mastery group, accounting for 63.75%, with an average score of 24.05 points, and 0 people in the poor mastery group. For diagnosis of current Hp infection, only 50.0% of general practitioners knew that fecal Hp antigen positive was one of diagnostic criteria, while 66.6% of general practi-tioners mistakenly believed that serum Hp antibody positive could be used for diagnosing Hp infection. In terms of indications for eradication treatment of Hp infection, only 41.9% of general practitioners believed that "confirmation of Hp infection" was the indication of eradication treatment. There were significant differences in educational background and working years between the moderate mastery group and the good mastery group. In terms of standardized treatment, fol-lowup and prevention of Hp infection, there were significant differences in other options between the two groups except for the choice of antibiotics (P

Objective: The petition letters of the National Exhibition and Convention Center (NECC) Fangcang Hospital, Jiahe Xinyuan Hotel (Jiahe) Fangcang Hospital and designated Ruijin Hospital of North Branch (designated Hospital) were analyzed, and the discussion was focused on how to optimize the operation process, improve the quality of medical service, optimize the doctor-patient relationship and other measures through the feedback of petition data after the hospitals were built in a very short time. Methods: The petition letters from two Fangcang hospitals and one designated hospital were retrospectively analyzed, and the source channels, types and trends of petition letters were analyzed at multiple levels, as well as the specific problems involved. The results and suggestions were summarized by combining qualitative and quantitative methods. Results: Ouring March 14 adn May 4, the two makeshift hospitals and one designated hospital had received a total of 1 155 letters, mainly from the "12345" hotline (88.86%). 759 (65.72%), 25 (2.16%) and 371 (32.12%) were respectively received from the NECC Fangcang Hospital, Jiahe Fangcang Hospital and designated Hospital. The number of requests for help accounted for 67.85%, 68.00% and 70.08% respectively in the three hospitals, and the other types of petition letters were consultation, complaint and suggestion. Requests for help and advice were frequently asked such as isolation policies, virus RNA PCR testing, critical care and emergency transport, and logistics. Conclusions: During the epidemic, the problems of letters and visits in the shelter focuse on the various actual needs and difficulties faced by patients in the shelter hospital, suggesting that the managers and operators of the shelter hospital should prepare for such needs and problems. Analyzing the contents of letters and visits can feed back and optimize the operation process and medical services of the shelter hospitals.