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Investigating the seeding mechanism of precision seeders is of great significance for improving the quality of cotton sowing operations. This paper designs a rotary type-hole cotton precision mulching dibbler. The main factors influencing the entry of cotton seeds into the seed wheel holes during the seeding process are then theoretically analyzed. Following this, an accurate discrete element model of coated cotton seeds is established and combined with a discrete element method (DEM) and multi-body dynamics (MBD)-coupled simulation model of the seed drill for seed picking and planting. Simulation experiments on the seeding performance of the precision dibbler were performed to study the influence of the seed wheel structure and motion parameters on the picking and planting performance under different speeds. The optimal parameter combination for the seed wheel is obtained through optimization experiments, and a precision dibbler is manufactured for bench testing. The bench test results are consistent with the simulation test results. At the precision dibbler rotation speed of 16 r/min, the qualified index reaches a maximum value of 93.28%, the skip sowing index increases with the precision dibbler rotation speed, and the re-sowing index decreases as the speed increases. These optimization results significantly improved seeding precision and efficiency and are of great significance for the reliability and effectiveness of cotton sowing operations. [ABSTRACT FROM AUTHOR]

Secreted phospholipase A2s (sPLA2s) are a group of enzymes with 6–8 disulfide bonds that participate in numerous physiological processes by catalyzing the hydrolysis of phospholipids at the sn-2 position. Due to their high content of disulfide bonds and hydrolytic activity toward cell membranes, obtaining the protein of sPLA2s in the soluble and active form is challenging, which hampers their functional study. In this study, one member of recombinant human sPLA2s, tag-free group IIE (GIIE), was expressed in Pichia pastoris. The protein GIIE was purified from the crude culture supernatant by a two-step chromatography procedure, a combination of cation exchange and size-exclusion chromatography. In the shake flask fermentation, Protein of GIIE with higher purity was successfully obtained, using basal salts medium (BSM) instead of YPD medium. In the large-scale fermentation, each liter of BSM produced a final yield of 1.2 mg pure protein GIIE. This protocol will facilitate further research of GIIE and provide references for the production of other sPLA2 members. [ABSTRACT FROM AUTHOR]

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Existing research on agricultural auto water pumps mainly concentrate on structure optimization; nonetheless, a few works examine the characteristics of the inner flow field. The current study conducted an unsteady numerical simulation calculation of agricultural auto water pumps using an impeller model with a 0.5 mm blade tip clearance (s) and ANSYS CFX software. The unsteady flow results were analyzed, and results indicated that the unsteady characteristics of the lift undergo significant periodic changes due to the dynamic and static interference of the cut water and the impeller. This change in frequency is in accordance with the passing frequency of the blade. The pressure fluctuation varies at different monitoring points on the same volute section. The pressure fluctuation decreases first and then increases from the bottom volute to the back volute. Additional dither components were also detected at the monitoring points on the bottom volute. The pressure fluctuation is maximized at the circumferential monitoring points proximal to the water cut. The distance between the circumferential monitoring points and the water cut increases with the circumference angle, whereas the fluctuation amplitude decreases. The results of fluid dynamics provide useful references to determine the reduction in the vibration and noise of agricultural auto water pumps. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis is an energy converting technology, but during the pyrolysis process, the outlet temperature of biochar is high due to high final pyrolysis temperature. As such biochar continue burning when exposed in air. So only after cooling, biochar can be transported and used. Currently, common practice is that biochar are natural cooled in a sealed container or by sprinkling water directly to biochar after pyrolysis. Both of the methods need a long time, besides, a great deal of residual heat of biochar is wasted during cooling. This leads to the long production cycle, lowly utilization rate of biochar heat in pyrolysis process. So a sealed cooling device is needed to solve the problem. Through this device, the outlet temperature of biochar should be <40-50°C. Because biomass heat transfer coefficient is low, the cooling process needs more time than other materials, and the new device should be long enough to allow sufficient cooling. As such, a two-stage heat exchange device is needed, using the principle of solid-liquid indirect heat exchange. Such design can ensure that the cooled biochar can be used directly for package, transportation or experiment. In this study, we first examined the details about device structure and size design. Based on analysis and comparison of different structure and biochar sizes, we selected water cooled screw type as the main structure. Biochar was delivered by screw blade in the inner tube with circulating water in out surface of the tube. For such device, the most important part was baffles, it was added between the inner tube and external tube, making circulating water flow in the form of spiral-flow around the inner tube, thus increasing heat transfer time between circulating water and wall surface of inner tube. Based on this, a second-stage biochar cooling system was designed with temperature acquisition terminal and control device, the temperature acquisition terminal was used to monitor the temperature of circulating water and biochar, including two temperature sensors and temperature patrol instrument. The control device regulated water flow and rotation speed of screw axis. We then conducted different cold water flow test,different rotation speeds of screw axis test and different biochar test by use of the system. The application results showed that, the average outlet temperature of biochar was 30°C, it reached the design requirement. Besides, the application results showed that the temperature difference increased with the rise of cold water flow. The temperature difference of peanut biochar was 272, 242, 222°C when rotation speeds of screw axis was 5 r/min, cold water flow was 8, 6.5, 4 m³/h. Meanwhile the outlet temperature of peanut biochar was 40°C, while rotation speed of screw axis was 25 r/min, and cold water flow was 6.5 me³/h. In contrast, when rotation speed of screw axis was 5 r/min, the outlet temperature of peanut biochar was 25°C. In all heat transfer coefficient was different with different biochar. The experiments showed that corn stalk biochar, peanut biochar, corncob biochar overall heat transfer coefficient was 100.6, 85.3, 57.6 W/(m²∙K), respectively. The cooling process completed smoothly with the cooperation of cooling system and pyrolysis equipment, this system could meet the need of continuous cooling process for various kinds of biochar. [ABSTRACT FROM AUTHOR]

In order to select appropriate mode of crop straw's collection-storage-transportation, and promote the large-scale use of straw resources, the mathematical model about straw's collection, storage and transportation was established, which was based on the equipment, manpower, and cost on the North China Plain. By analyzing different modes about straw's collection-storage-transportation (which was divided into centralized model, decentralized mode; collected by manpower, collected by machinery), the effect of cost and energy consumption were different. Because of the different amounts of straw collection, manpower and equipments were demanded in mathematical models. The results showed that the cost of straw's collection-storage-transportation was 120- 260 Yuan/t, the fuel consumption of straw's collection-storage-transportation was 1.2×105 - 5.5×105 kJ/t. While using machinery to collected straw in filed, the cost was lower than that by manpower; but the required equipment number was significantly more than thatneeded by manpower. Meanwhile, the energy consumption of equipment was significantly increased. On the contrary, collecting straw in filed by manpower needs a lot of manpower. The calculated results showed that the cost and energy consumption of centralized mode about equipment-manpowercost was lower than decentralized mode when collecting by the same manner. Compared to the manpower collection, collection by machinery can reduce the total cost, but the initial investment was higher and the capacity in solving employment problem was lower. When the amount of crop straw collection increased from 5×104 to 50×104 t, the unit cost of mode A and B was monotonically increasing. As to mode C and D, it declined quickly from 5×104 to 25×104 t, then rose gradually from 25×104 to 50×104 t. Therefore, it can be concluded that the collection methods affected cost extremely. Collecting straw by manpower, the mode of A and C curved intersect at 250 000 t; Or else, the mode of B and D curved intersect at 500 000 t. When the collected amount of crop straw increased from 5×104 to 50×104 t, the unit energy consumptions of mode A and B increased, with slow upward trend rate; On the contrary, from 5×104 to 25×104 t straw collection, the unit energy consumption of mode C and D was decreasing, when the collected amount of crop straw was 18×104 and 12×104 t, the unit energy consumption curves of mode B and C2 could intersect; Similarly, the unit energy consumption curves of mode A2 and C1 also could intersect. In this circumstance, when the collected amount was less than the intersection, the energy consumption of mode B and A2 was lower than mode C2 and C1. Therefore, the energy consumption of centralized mode is lower when the crop straw amount collected is less, it is recommended to choose centralized mode; Otherwise, decentralized mode is the better choice. [ABSTRACT FROM AUTHOR]

Based on the CFD imitation of the three- dimensional flow field of the agricultural automobile engine cooling water pump, the thesis analyzes the energy characteristics and cavitation performance of the farm vehicle using two variable curvature blade type cooling water pump without cavitation, forecasts the cavitation distribution in the impeller and the stream line load distribution under different cavitation conditions and compares with the test results. The results showed that: in the design flow of 25 ºC, the simulated head was 13.49m and the error between numerical simulation and the test results was within 2%. The head of the pump engine cooling model of agricultural vehicles of the design operating point under 85 ºC is 9.6m, much lower than the head value of the design flow under 25 ºC. This shows that there is serious cavitation in the actual operation of pump, the cavitation performance curve and the numerical change trend converge, numerical value is less than the full cavitation range measured values and as the flow increases, the critical cavitation allowance also increases accordingly. The research provides a theoretical basis for the improvement of the cavitation performance of agricultural machinery engine cooling water pumps and the prevention and mitigation of cavitation. [ABSTRACT FROM AUTHOR]

Because there exists much diversity in raw materials, biomass fuel pellet properties, and corresponding combustion equipment, research to develop the fuel adaptability of biomass burners is necessary. The research was accomplished on a self-build biomass combustion equipment-monitoring platform. The monitoring platform has multiple sensors to collect and process data of the burner's control parameters and combustion state parameters. Based on the platform, the author used a PB-20-type biomass pellet burner, which is designed by the Chinese Academy of Agricultural Engineering. The author investigated five kinds of biomass pellets with ash values from 0 to 25 percent, And tested nine kinds of working conditions for each pellet with 3, 4, and 5 kg/h fuel feed rates and 2 600, 2 700, and 2 800 r/min fan speed. The thermal performance of the burner was tested according to the GB/T10180-2003 Thermal performance test code for industrial boilers and the GB13271-2001 Emission standard of air pollutants for coal-burning oil-burning gas-fired boilers. During each test, the water circulation amount, inlet and outlet temperature of water, cold air and exhaust gas temperature, slag temperature, O2\CO\NO\NO2 content in flue gas, and the slag ash content were processed. The excess air ratio, anti-balance efficiency, gas incomplete combustion heat loss, heat loss due to combustion in refuse, heat loss due to sensible heat in slag, soot emissions and blackness of each condition with the thermal performance data of the burner were then calculated. Combined with physical and chemical characteristics of the pellet fuels, the pellet fuel combustion efficiency change and its causes were analyzed, and fuel feed rate and the best match into the air flow of 15-25 kW biomass pellet fuel burner were obtained. The results showed that the pellets with ash content ≥20 percent were not applicable to this type of biomass pellet burner; the recommended parameters for pellets with ash rate 12.40 percent were 4 kg/h (feed rate), 2 600-2 800 r/min (fan speed), 3 r/min, turn on 5 sec/turn off 35 sec (slag-off speed); for pellets with ash rate 7.21percent, the recommended parameters were 3-4 kg/h (feed rate), 2 600-2 800 r/min (fan speed), 3 r/min, turn on 5 sec/turn off 60-55 sec (slag-off speed); and for pellets withash rate =1.0 percent, the recommended parameters were 3-4 kg/h (feed rate), 2600-2800 r/min (fan speed), without slagging. This study summarizes the burner's control parameters for the biomass pellet fuel, and provides data support for the promotion and application of the pellet burner. [ABSTRACT FROM AUTHOR]

The global energy crisis arouses growing interest in the field of renewable energy all over the world. Biomass is a world-recognized environmentally friendly renewable energy because of its lower contents of N and S element and the approximate zero net emissions of CO2. How to make full use of biomass energy has been an important direction of studies in the field of renewable energy. Biomass combustion is one of the most important technologies for large-scale efficient and clean utilization of biomass energy. The existing study on biomass combustion characteristics in China mostly focus on a kind of biomass, and little on different kinds of biomass. Thermal analysis curves (TGA- DTG- DTA) are commonly used in combustion characteristic analysis and dynamic analysis, but not in biomass combustion analysis. Therefore, this study investigated the combustion characteristics of biomass--agricultural residues (wheat straw, cotton straw, and cornstalk), forestry residues (sawdust), and industrial waste residues (sweet sorghum slag) at different heating rates (5, 10, 20, and 30℃/min) in air by thermo gravimetric analysis technology. Results showed that all the biomass combustion included four main phases: water evaporation stage, devolatilization and combustion stage, fixed carbon combustion stage, and burnout stage. The comprehensive combustion characteristic index S was ordered in wheat straw (XMJ)> cotton stalk (MHJ)> sweet sorghum slag (GLZ)> cornstalk(YMJ)> sawdust (MX). The rise of heating rate could improve the combustion performance of biomass samples. Based on these results, a TGA-DTG-DTA method was proposed to determine the values of industrial analysis of samples. The weightlessness rate of A-B, B-C, and C-D was equal to moisture content, volatile content, fixed carbon content, respectively. The weightlessness rate of point D was the ash content of the sample. Thermal analysis curves under 20℃/min heating rate were recommended for industrial analysis. Meanwhile, a differential thermal analysis method was also proposed to determine calorific value of samples, which was the heat difference of peak area between RS (the heat discharged) and OP (the heat absorbed). The other heat-related curves could be obtained from TA-60WS data processing software built in the instrument. Overall, the best combustion performance could be obtained at the heating rate of 20℃/min for agricultural residues, 5℃/min for sawdust and 10℃/min for sorghum slag. The differential thermal analysis and thermal analysis curve expanded the application of thermogravimetric analysis technology in studies on biomass combustion characteristic. However, their effectiveness and applicability required further verification of more experiments and data. It hoped that this study would provide valuable information for maturing biomass combustion technology in China. [ABSTRACT FROM AUTHOR]

Human secreted phospholipase A2 GIIE (hGIIE) is involved in inflammation and lipid metabolism due to its ability of hydrolyzing phospholipids. To reveal the mechanism of substrate head-group selectivity, we analyzed the effect of mutation of hGIIE on its activity and selectivity. hGIIE structural analysis showed that E54 might be related to its substrate head-group selectivity. According to the sequence alignment, E54 was mutated to alanine, phenylalanine, and lysine. Mutated genes were cloned and expressed in Pichia pastoris X33, and the enzymes with mutations were purified with 90% purity by ion exchange and molecular size exclusion chromatography. The enzymatic activities were determined by isothermal microthermal titration method. The Km of mutant E54K towards 1,2-dihexyl phosphate glycerol decreased by 0.39-fold compared with that of wild type hGIIE (WT), and the Km of E54F towards 1,2-dihexanoyl-sn-glycero-3-phosphocholine increased by 1.93-fold than that of WT. The affinity of mutant proteins with phospholipid substrate was significantly changed, indicating that E54 plays an important role in the substrate head-group selectivity of hGIIE.

Secreted phospholipases A 2 s (sPLA 2 s) are involved in various pathological conditions such as rheumatoid arthritis and cardiovascular disease. Many inhibitors were developed and studied in clinical trials, but none have reached the market yet. This failure may be attributed to the lack of subtype selectivity for these inhibitors. Therefore, more structural information for subtype sPLA 2 is needed to guide the selective inhibitor development. In this study, the crystal structure of human sPLA 2 Group IIE (hGIIE), coupled with mutagenesis experiments, proved that the flexible second calcium binding site and residue Asn21 in hGIIE are essential to its enzymatic activity. Five inhibitor bound hGIIE complex structures revealed the key residues (Asn21 and Gly6) of hGIIE that are responsible for interacting with inhibitors, and illustrated the difference in the inhibitor binding pocket with other sPLA 2 s. This will facilitate the structure-based design of sPLA 2 's selective inhibitors.