Table of Content

28 April 2021, Volume 49 Issue 2

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Clinical Characteristics and Severe Risk Factors of COVID- 19 Patients：A 474-Case Study

YIN Ziwei，ZHU Hong，TU Qian

2021, 49(2):  5-11.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.001

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Objective To explore the risk factors that may be related to severe/critical COVID-19 patients，so as to early identify patients with severe/critical high-risk indicators and make appropriate interventions and adjustments in a timely manner. Methods A total of 474 patients were included in the study. The differences in general characteristics，underlying diseases，clinical symptoms，laboratory findings and outcomes between mild/normal and severe/critical patients were observed retrospectively. The binary logistics model was used for multi-factor analysis to explore the risk factors that may be related to the development of severe/critical type. Results Severe/critically patients had higher mortality，older age and longer hospital stays. There were 305 patients complicated with pre-existing comorbidities，and single factor study found that neutrophil count， the levels of blood urea nitrogen（BUN），fibrinogen，D-dimer，CRP，procalcitonin，creatine kinase isoenzyme and lactate dehydrogenase were higher in severe/critical patients. However，lymphocyte count，platelet count，macrophage count，albumin，globulin ratio and total protein were lower，and there was a significant difference between the two groups（P < 0. 01）. Multivariate binary logistic analysis showed that the patients complicated with pre-existing comorbidities OR = 1. 706，95%CI（1. 074，2. 709），P = 0. 024. Lymphocyte count OR = 0. 521，95%CI（0. 342，0. 792），P = 0. 002；BUN OR = 1. 054，95%CI（1. 001，1. 110），P = 0. 044；CRP OR = 1. 107，95%CI（1. 024，1. 197），P = 0. 011；LDH OR = 1. 004，95% CI（1. 001，1. 007），P = 0. 007. Conclusion There is a higher risk of developing into severe/critical cases for the COVID-19 patients complicated with pre-existing comorbidities and laboratory examination results suggest that the higher levels of BUN，CRP，LDH，and lower lymphocyte count. Therefore，monitoring and treatment regimens of patients in the hospital could be strengthened and timely adjusted.

Advances in Digestive System Performance Induced by SARS-CoV- 2

YUE Jingru，LI Zhongxia，ZHANG Heng，QIAO Jialu

2021, 49(2):  12-19.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.002

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As a new acute respiratory infectious disease in 2019，coronavirus disease 2019（COVID-19） shows a global epidemic trend，which leads to large casualties and serious economic losses，and poses a serious threat to public health worldwide. COVID-19 has been confirmed to be caused by the severe acute respiratory syndrome coronavirus 2（SARS-CoV-2）. Although COVID-19 is principally defined by its respiratory symptoms，it is clear that the virus can also affect the digestive system，which mainly causes gastrointestinal symptoms such as diarrhea， vomiting and abnormal liver function. Moreover，some patients have gastrointestinal symptoms as the first manifestation，and some studies have shown that the RNA of SARS-CoV-2 could be detected in the stool of infected patients. In this paper，we reviewed the clinical symptoms，pathogenesis，treatment，and faecal-oral transmission of COVID-19 associated with the digestive system based on the existing diagnosis and treatment guidelines and literature，in order to provide a reference for clinical medical staff to prevent and treat COVID-19.

Research Progress on the Possibility of Faecal-Oral Transmission of COVID-19

LI Zhongxia，YUE Jingru，ZHANG Heng

2021, 49(2):  20-28.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.003

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Coronavirus disease 2019（COVID-19），which was caused by the severe acute respiratory syndrome coronavirus 2 （SARS-CoV-2），broke out in December 2019. It spread rapidly throughout the world in a short time and caused a serious threat to global public health. SARS-CoV-2 presents a high infection rate，which is mainly transmitted through droplet and close contact. After the virus enters the human body，it is mainly replicated in the alveoli，which aggravates the inflammatory reaction in the lung and damages the lung tissue. It is found that SARS-CoV-2 can cause acute respiratory distress syndrome （ARDS） and severe pneumonia with multiple organ failure （MOF） in some severe patients. It has been reported that the RNA of SARS-CoV-2，even the live virus can be detected in the stool of some COVID-19 patients with gastrointestinal symptoms，which indicates that faecal-oral transmission is also a potential route of transmission. By searching the literature published in China and abroad from December 2019 to April 2020，we discussed the possibility of faecal-oral transmission of COVID-19 and put forward the methods to prevent infectious cases and environmental pollution caused by faecal-oral transmission，combined with reports about the faecal-oral transmission of Middle East Respiratory Syndrome（MERS）and Severe Acute Respiratory Syndrome（SARS）.

The Deduction of the Expressions of Laplacian Operator in Two Special Coordinate Systems

TIAN Daping，WANG Min

2021, 49(2):  29-34.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.004

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According to the definition of the Laplacian operator on Riemannian manifolds，it is a second-order elliptic differential operator obtained by applying the divergence operator to the gradient field of the smooth function on Riemannian manifolds. In this paper，we first specialize Riemannian manifolds into Euclidean spaces， and derive the expression of Laplacian operator in the rectangular coordinate system in the three-dimensional Euclidean space through calculation. And then， by applying transformation formulas between the rectangular coordinate system and the cylindrical coordinate system or the spherical coordinate system，we derive respectively the specific expressions of Laplacian operator in cylindrical and spherical coordinate systems in Euclidean space.

Study on Optimal Consumption-Portfolio Problem Considering Labor Income Based on Stochastic Volatility Model

JIANG Kui

2021, 49(2):  35-42.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.005

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This paper studies the optimal consumption and portfolio of investors with labor income under the framework of the stochastic volatility model. After the model is established，the HJB （Hamilton-Jacobi-Bellman） equation is obtained by applying the stochastic optimal control theory；secondly，the power utility function is considered and the explicit solution of optimal consumption-portfolio is obtained by separating variables，that is，the functional expressions of optimal consumption c^*（t）and investment strategy π^*（t）. Finally，the effect of different market parameters on the optimal consumption-portfolio strategy is analyzed through numerical simulation. The result shows that when the instantaneous volatility increases，the optimal investment proportion decreases，but the consumption level increases；when the risk aversion factor increases，investors bear less investment risk，which will increase the investment proportion of risk assets and reduce consumption expenditure；when the investor has a labor income，it affects the investor's consumption-portfolio decision.

Application Analysis on Breakthrough Model of Desulfurization by Activated Carbon Adsorption

SHI Ling，SUN Shaofeng，ZHU Zhongkui，CHANG Yufeng，LIU Xiaoye，YUE Lin，AN Liang

2021, 49(2):  43-50.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.006

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The experimental breakthrough data of activated carbon fixed-bed adsorption of SO2 was analyzed by the Slogistic function and Bohart-Adams model. For several types of activated carbon at different particle diameters，the saturation of adsorption layer，median concentration adsorption time，and the key parameters and mathematical properties of the Bohart-Adams model were obtained. At the same time，the linear relationship between the adsorption time and the bed thickness was also obtained based on the median concentration adsorption time. This study has certain reference significance for the design of adsorption fixed-bed.

Electrochemical Behavior of POP on Cu-MOF/MWCNTs Composite Modified Electrode

LIN Qian，HUANG Xiaozhou，HUANG Dihui

2021, 49(2):  51-58.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.007

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Cu-MOF and MWCNTs were synthesized by solvothermal method，and then Cu-MOF/MWCNTs composites were prepared，which was dropped onto the electrode surface，and the electrochemical behavior of POP on the Cu-MOF/MWCNTs modified electrode was studied by cyclic voltammetry （CV）. Experimental results showed that the electrode modified with Cu-MOF/MWCNTs had obvious electrocatalytic activity for p- （Tert-octyl） phenol （POP）. The reaction of POP on the electrode was controlled by adsorption. The oxidation peak current had a good linear relationship with the concentration of POP in the range of 1-50 μmol/L with a detection limit of 9. 51×10^-7 mol/L（S/N = 3），ΔI = -7. 965 82 - 0. 898 21C （R² = 0. 997 1）. Using this analytical method to detect samples of disposable polystyrene plastic lunch boxes，the average recovery of POP was 98. 9%-100. 4%，and the relative standard deviation of the measured values（n = 6） was 3. 02%-4. 00%.

Construction and Use of Disinfection By-Products Database Network Platform

XIE Jidao，LI Ziyi，MA Yanfei，FAN Rong，ZHOU Lei，YANG Zebiao，YANG Xiaoqiu，ZHENG Qi

2021, 49(2):  59-65.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.008

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In view of the information of disinfection by-products（DBPs）is scattered and difficult to query，a DBPs database network platform is constructed. Using the network resources，the information of more than 900 kinds of DBPs was collected and uploaded to the system platform made by the dynamic website technology of MyEclipse + MySQL + Tomcat. Through the network platform， accurately or fuzzy query for DBPs could be conducted to get the molecular formula，determination method，disinfection method and other contents of the target substances. This platform provides a reference for understanding DBPs deeply to control and remove them effectively.

Effects of Tillage Management and Rhizobia Inoculation on Soil Fertility，Pea Yield and Quality

ZENG Changli，LIU Li，TIAN Xueting，DAI Xigang，NING Tingting，DING Jianjun

2021, 49(2):  66-75.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.009

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In the paper，using the variety of 'Zhongwan No. 4' as material，in the situation of no-tillage and tillage in winter-fallow paddy fields，considering rhizobia inoculated and non-inoculated pea， the effects of tillage management and rhizobia inoculation on soil fertility of winter-fallowed paddy fields，pea yield and quality were discussed by double factor randomized block design. The results showed that the organic matter content of peas planted with or without rhizobia could be significantly increased under no-tillage conditions. Although the treatments of no-tillage and tillage inoculation could significantly improve the content of soil total nitrogen，there was no significant effect of tillage management and rhizobia inoculation on soil alkaline nitrogen content. The treatment of no-tillage could significantly increase the available phosphorus content in the soil. Moreover，the treatment of no-tillage could significantly increase the content of available potassium， while the treatment of rhizobia inoculation did not have the effect. The treatments of no-tillage inoculation and no-tillage no-inoculation could markedly increase the number of bacteria，but only no-tillage inoculation could significantly increase the number of actinomycetes and fungi. No-tillage inoculation treatment could remarkably improve the number of pods per plant， the yield of tender pods， and the yield of seeds， but there was no significant difference in the number of seeds per plant and the weight of 100 seeds. In addition，the content of crude protein and crude fiber in pea could be markedly improved by inoculating rhizobia under no-tillage or tillage conditions. Further analysis of the main effects showed that the tillage managements played a leading role in the content of available phosphorus and available potassium，the number of actinomycetes and fungi. However，the effect of rhizobia inoculation played a leading role in the content of organic matter and soil total nitrogen，the number of bacteria，the number of pods per plant，the yield of tender pods and seeds，the content of crude protein and crude fiber. In the impact on the yield of tender pods and seeds，there was an obvious interaction effect between the tillage managements and rhizobia inoculation.

Study on Influencing Factors of Seed Germination and Aseptic Seedling Transplanting Survival of Bletilla striata

ZOU Huanhuan，CHENG Mingsheng，ZOU Na

2021, 49(2):  76-81.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.010

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The effects of different media and culture methods on aseptic germination of Bletilla striata seeds，the effects of different size seedling bags on the survival of Bletilla striata aseptic seedlings，and the influence of shade intensity on the growth of Bletilla striata container seedlings were studied. The results showed that there was no significant difference in germination rate of Bletilla striata seeds in different media and culture methods，but the corm in solid BJ4 medium was larger than that other treatments；the average survival rate and growth of the aseptic seedlings treated with larger size（16 cm × 20 cm）seedling bags were better. In terms of shading strength，the four-needle shading net was more conducive to the survival and growth of Bletilla striata. The survival rate of Bletilla striata was 60% and the average seedling height was 5. 65 cm after transplanting for 2 months. However，the unshaded state was not suitable for the growth of Bletilla striata container seedlings.

Reliability Design of FAT32 File System Based on SD Card

LU Junhui，LIU Qi，SHI Lijuan

2021, 49(2):  82-88.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.011

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This paper analyzes the problems existing in the application of the FAT32 file system in the embedded system，reserves FDT space to make FDT and DATA store sequentially，and prevents FDT and DATA from interpenetrating with each other. The redundant storage of incremental idle cluster numbers is realized by increasing the number of DBR sectors，and the necessary format error detection and error correction for DBR，FAT，and FDT is conducted. The real-time performance and reliability of the FAT32 file system applied to the embedded system are improved effectively.

Realization of Communication Between STM32 MCU and Siemens Smart 700 Touch Screen

LI Peng，WANG Li

2021, 49(2):  89-96.  doi:10.16389/j.cnki.cn42-1737/n.2021.02.012

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The paper establishes the communication between STM32 MCU and Smart 700 touch screen， and analyzes the composition and format of Modbus RTU， the basic communication mode of Smart 700 touch screen and the communication characteristics of STM32 MCU. Then，the communication program of STM32 MCU is proposed. Finally，the experimental platform is designed to test the communication reliability between STM32 MCU and Smart 700 touch screen. The experimental results achieve the expected results.