Design of Bionic Saw Blade for Corn Stalk Cutting

The serrated incisors of grasshopper [Chondracris rosea rosea （De Geer）] possess an advantageous capacity for cutting plant fiber. Inspired by this special geometrical structure of incisors, bionic saw blade was designed and manufactured. MATLAB software digital image processing technology was used to obtain outer margin profile from stereomicroscope pho- tograph of the serrated incisors. The outer margin profile of incisors was fitted and expressed by six-order polynomial function. To compare the cutting capacity of bionic and traditional saw blades, the internodes of dry corn stalks were cut perpendicularly. Cutting force-deformation characteristics were obtained by universal testing machine. The results of cutting experiments show that the maximum cutting force of bionic saw blade was 128.26 N, which is 15.87% lower than 152.45 N of traditional saw blade; the average cutting force of bionic saw blade was 51.56 N, which is 28.17% less than 71.78 N of traditional saw blade. Meanwhile, the cutting energy consumption of bionic saw blade was 8.95 J, which is 12.85% less than 10.27 J of traditional saw blade. Overall, the bionic saw blade can lead to noticeable reduction of the cutting force and energy. These results will be helpful for designing cutting elements of corn stalk harvesting, biomass size reduction and other processing machinery.     

心室辅助径流泵的设计方法

我们正在研制一种心室辅助径流泵,可在体外循环中代替血泵使用,也可作为心衰病人短期心脏辅助泵使用。此种无密封件的径流的泵的轴尖支承结构由一根据氧化铝陶瓷制成的叶轮轴和两只氧化锆陶瓷制成的轴尖轴承组成。叶轮的外径为７２毫米,进流处直径为２４毫米。位于叶轮上表面的六个叶片的进流侧高度为５．５毫米。出流侧高度为３毫米。     

福建省耕地土壤潜性酸动态变化及其驱动因素

土壤潜性酸是植物生长的潜在限制因子,是土壤酸性调控的重要依据.按比例抽取并测定福建省耕地表层土壤代表性样点的潜性酸量和pH值,拟合潜性酸(PA)与活性酸(pH)的最优关系模型,利用全省1982年36777个、2008年236445个和2016年21269个耕地表层土壤调查样点pH等属性数据,建立3期1∶5万耕地土壤潜性酸量数据库,借助GIS技术和灰色关联分析模型探讨福建省耕地土壤潜性酸动态变化规律及其驱动因素.结果表明: 1982—2016年,全省耕地土壤潜性酸量整体呈上升趋势,2008和2016年潜性酸量分别比1982年上升1.30和1.49 cmol·kg^-1,1982—2008年的潜性酸上升速率比2008—2016年高0.03 cmol·kg^-1·a^-1.1982—2016年,全省耕地土壤潜性酸变化量空间差异明显,龙岩市耕地土壤潜性酸变化量最大,比最小的三明市高4倍以上;不同利用类型耕地土壤潜性酸变化量大小依次为水田>水浇地>旱地;咸酸水稻土、潜育水稻土和淹育水稻土亚类的潜性酸变化量最大,是全省潜性酸变化量均值的1倍以上;赤红壤和盐渍水稻土亚类变化量最小,分别为全省均值的25.7%和28.4%.福建省耕地土壤潜性酸动态变化的主要驱动因素包括氮、磷肥施用量、阳离子交换量(CEC)、黏粒含量、pH和粉粒含量,灰色关联系数绝对值＞0.92.科学优化施肥结构、合理施用碱性调理剂改酸是减缓福建省耕地土壤潜性酸增加的重要途径.     

稻田土壤关键元素的生物地球化学耦合过程及其微生物调控机制

水稻土是在长期植稻下人为培育的特殊耕作土壤,是我国土壤学的特色,其研究也反映我国土壤学的国际地位。水稻土是研究土壤生物地球化学过程的理想模型。稻田土壤关键元素(碳氮磷硫铁等)的生物地球化学循环过程、耦合机理及其驱动机制研究是土壤生物学研究的核心之一。因此,以国际土壤年为契机,结合中国科学院院士工作局资助的"土壤生物学发展战略研究"项目的部分成果,以稻田关键元素(碳氮磷硫铁等)生物地球化学循环过程及其耦合的微生物驱动机制为核心,重点讨论了稻田土壤基本生物化学特征、稻田土壤碳-氮、碳-氮-磷、碳-氮-铁等多元素耦合过程及其与微生物之间的反馈机制,并由此提出了稻田土壤关键元素生物地球化学循环微生物驱动机制研究的未来重点发展方向为:1)土壤关键元素生物地球化学过程的异质性及其微生物过程的互作机制研究;2)微生物参与机制对土壤关键元素循环过程的响应、反馈机制与调控机制研究;3)土壤关键生物地球化学过程的计量学研究。     

水溶性有机质对土壤中镉吸附行为的影响

水溶性有机质 (DOM)是陆地生态系统和水生生态系统中的一种很活跃的组分 .本文以赤红壤、水稻土和褐土作为供试土壤 ,研究了来源于稻秆和底泥的DOM对土壤中Cd吸附行为的影响 .DOM对土壤中Cd的吸附行为具有明显的抑制作用 .这种抑制作用与土壤类型和DOM种类有关 .在 3种供试土壤中 ,无论添加稻秆DOM还是底泥DOM ,都会使Cd的最大吸附容量和吸附率明显降低 ,其下降幅度为17 3%～ 93 9%.在添加同一种DOM的前提下 ,DOM对Cd吸附的抑制作用均为 :赤红壤 >水稻土 >褐土 .如果不添加DOM ,则土壤对Cd的最大吸附容量主要取决于土壤固相的吸附特性 ,添加DOM后土壤对Cd的最大吸附容量则主要取决于液相中的DOM .由此推断 ,传统的看法 ,通过施用有机肥来固定土壤中的Cd并达到治理重金属污染土壤的观点值得商榷 .     

施肥措施对不同母质发育的稻田生态系统土壤微生物量碳、氮的影响

以湖南省稻田土壤肥力监测点为基础,研究了稻田生态系统土壤微生物量碳、氮的特性.结果表明,不同施肥措施对不同地域和母质发育的稻田生态系统土壤微生物量碳、氮的影响程度不同.经过18年的不同施肥处理,不同母质发育的稻田生态系统土壤微生物量碳、氮的变化趋势基本一致,变化顺序为湖积物发育的水稻土>河流冲积物和第四纪红土发育的水稻土>石灰岩发育的水稻土>板页岩发育的水稻土.土壤微生物量碳为259.5～864.4 mg·kg^-1,土壤微生物量氮为8.7～70.7 mg·kg^-1.施肥可以明显提高稻田生态系统土壤微生物量碳、氮含量;有机肥是改善土壤微生物量碳、氮的主要基础物质,但以有机无机配合施用效果最好.与对照相比,施化肥和有机无机配施处理土壤微生物量碳、氮最大增量分别为407.6和59.2 mg·kg^-1,最大增长率分别为102.8%和514.8%.     

Combined effect of hydrodynamic and interfacial flow parameters on lysozyme deactivation in a stirred tank bioreactor

The dynamic environment within a bioreactor and in the purification equipment is known to affect the activity and yield of enzyme production. The present research focuses on the effect of hydrodynamic flow parameters (average energy dissipation rate, maximum energy dissipation rate, average shear rate, and average normal stress) and the interfacial flow parameters (specific interfacial area and mass transfer coefficient) on the activity of lysozyme. Flow parameters were estimated using CFD simulation based on the k-epsilon approach. Enzyme deactivation was investigated in 0.1, 0.3, 0.57, and 1 m i.d. vessels. Enzyme solution was subjected to hydrodynamic stress using various types of impellers and impeller combinations over a wide range of power consumption (0.03 < P(G)/V < 7, kW/m3). The effects of tank diameter, impeller diameter, blade width, blade angle, and the number of blades on the extent of deactivation were investigated. At equal value of P(G)/V, epsilon(max), and gamma(avg), the extent of deactivation was dramatically different for different impeller types. The extent of deactivation was found to correlate well with the average turbulent normal stress and the mass transfer coefficient.     

Triarylmethane Dye Decolorization by Pellets of Pycnoporus sanguineus: Statistical Optimization and Effects of Novel Impeller Geometry

A study was carried out to optimize selected parameters for decolorization of a triarylmethane dye, such as crystal violet by white rot fungus, Pycnoporus sanguineus, pellets. The parameters studied were initial dye concentration (ppm), agitation speed (rpm), and process time (days) and were optimized using response surface methodology (RSM). It is shown that process time, agitation speed, and their interactions have significant effects on the decolorization process. Following the optimization, the decolorization study was extended to a stirred tank reactor (STR) process. Effects of different geometry of impellers on the decolorization process and power consumption were studied. Novel impeller geometries, such as 180° curved blade and 60° angled blade impellers, were used in the STR. The application of 180° curved blade impeller resulted in higher percentage of decolorization at a relatively less power consumption as compared with 60° angled blade impeller.     

Fermentation pattern of methanogenic degradation of rice straw in anoxic paddy soil

The anaerobic degradation of different fractions of rice straw in anoxic paddy soil was investigated. Rice straw was divided up into stem, leaf sheath and leaf blade. The different straw fractions were mixed with paddy soil and incubated under anoxic conditions. Fermentation of straw components started immediately and resulted in transient accumulation of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate and caproate with much higher concentrations in the presence than in the absence of straw. Also some unidentified compounds with UV absorption could be detected. The maximum concentrations of these compounds were different when using different straw fractions, suggesting differences in the degradation pathway of these straw fractions during the early phase of incubation, i.e. with Fe(III) and sulfate serving as oxidants. When concentrations of the intermediates decreased to background values, CH(4) production started. Rates of CH(4)unamended soil. During the methanogenic phase, the percentage contribution of fermentation products to CH(4) production was determined by inhibition with 2-bromoethanesulfonate (BES). Acetate (48-83%) and propionate (18-28%) were found to be the main intermediates of the carbon flow to CH(4), irrespective of the fraction of the rice straw or its absence. Mass balance calculations showed that 84-89% of CH(4) was formed via acetate in the various incubations. Radiotracer experiments showed that 11-27% of CH(4) was formed from H(2)/CO(2), thus confirming that acetate contributed 73-89% to methanogenesis. Our results show that the addition of rice straw and the fraction of the straw affected the fermentation pattern only in the early phase of degradation, but had no effect on the degradation pathway during the later methanogenic phase.     

Structural Bionic Design and Experimental Verification of a Machine Tool Column

Based on the configuration principles of biological skeletons and sandwich stems, a machine tool column with stiffening ribs inside was designed using structural bionic method. After the lightening effect was verified by finite element simulation, scale-down models of a conventional column and a bionic column were fabricated and tested. Results indicate that the bionic column can reduce the maximum static displacement by 45.9% with 6.13% mass reduction and its dynamic performances is also better with increases in the first two natural frequencies. The structural bionic design is effective in improving the static and dynamic structural performances of high speed machine tools.     

Study on Mechanics of Driving Drum with Superelastic Convexity Surface Covering-Layer Structure

Belt conveyor is one of the main transport equipment in coal mine and the driving drum is its key part. With the method of bionic design, the mushroom morphological structure is applied to the design of covering-layer structure of driving drum surface of belt conveyor. Superelastic rubber with large deformation is adopted as the covering-layer material. Nonlinear constitutive model of rubber, which is of superelasticity and large deformation, is established. The stress states and deformation principles of driving drums including both bionic covering-layer and common covering-layer are obtained by static intensity analysis with Finite Element Analysis (FEA) software ANSYS. The values of the stress and strain on the driving drum surface are gotten and the dangerous area is determined. FEA results show that the superelastic convexity surface structure can enlarge the contact area between the driving drum and viscoelastic belt. The results also show that in comparison with common driving drum, the bionic surface driving drum can not only increase the friction coefficient between drum and belt but also prolong its service life.     

Enhancing aspergiolide A production from a shear-sensitive and easy-foaming marine-derived filamentous fungus Aspergillus glaucus by oxygen carrier addition and impeller combination in a bioreactor

Production enhancement of a novel antitumor compound aspergiolide A from shear-sensitive and easy-foaming marine-derived fungus Aspergillus glaucus HB1-19 in a 5-l stirred bioreactor was investigated. Two types of impellers, i.e., six-flat-blade disc turbine impeller (DT) and three-sector-blade pitched blade turbine impeller (PB) were used in this work. In cultures with fermentation medium, the combination of upper PB and lower DT led to the maximum dry biomass (13.8 g/l) and aspergiolide A production (19.3 mg/l). However, two PBs brought the highest aspergiolide A yield coefficient (1.9 mg/g dry biomass) despite it produced the lowest dry biomass (5.3 g/l). By contrast, two DTs and the upper DT and lower PB showed insignificant results. Feeding 0.35% (v/v) n-dodecane in cultures with upper PB and lower DT further improved aspergiolide A production by 31.0%, i.e., 25.3 mg/l, which is also 322% higher than that in the ordinary cultures with two DTs.     

Hydraulic redistribution in a Douglas-fir forest: lessons from system manipulations

Hydraulic redistribution (HR) occurs in many ecosystems; however, key questions remain about its consequences at the ecosystem level. The objectives of the present study were to quantify seasonal variation in HR and its driving force, and to manipulate the soil-root system to elucidate physiological components controlling HR and utilization of redistributed water. In the upper soil layer of a young Douglas-fir forest, HR was negligible in early summer, but increased to 0.17 mm day(-1) (20-60 cm layer) by late August when soil water potential was approximately -1 MPa. When maximum HR rates were observed, redistributed water replenished approximately 40% of the water depleted from the upper soil on a daily basis. Manipulations to the soil or to the soil/plant water potential driving force altered the rate of observed HR indicating that the rate of HR is controlled by a complex interplay between competing soil and plant water potential gradients and pathway resistances. Separating roots from the transpiring tree resulted in increased HR, and sap flow measurements on connected and disconnected roots showed reversal of water flow, a prerequisite for HR. Irrigating a small plot with deuterated water demonstrated that redistributed water was taken up by small understorey plants as far as 5 m from the watering source, and potentially further, but the utilization pattern was patchy. HR in the upper soil layers near the watering plot was twice that of the control HR. This increase in HR also increased the amount of water utilized by plants from the upper soil. These results indicate that the seasonal timing and magnitude of HR was strongly governed by the development of water potential differences within the soil, and the competing demand for water by the above ground portion of the tree.     

机械搅拌式动物细胞反应器不同桨型组合的CFD数值模拟与优化

生物反应器已成为哺乳动物细胞生产治疗性抗体药物和疫苗的核心。文中采用CFD数值模拟方法对目前常用的机械搅拌式生物反应器在不同的搅拌形式下的流场进行了分析,获得了5种搅拌桨型组合条件下的速率矢量、持气率、含气率和剪切力分布的特征。通过构建的重组CHO细胞在不同搅拌形式条件下的流加分批培养发现,细胞密度和抗体表达水平与反应器内的最大剪切率直接相关,在FBMI3搅拌形式下细胞密度和抗体表达水平均最高。结果表明该CHO细胞在悬浮培养时对剪切环境比较敏感,且最大剪切力是工业规模放大的关键因素。     

平衡施肥对缺磷红壤性水稻土的生态效应

为了研究平衡施肥对缺磷水稻土的生态效应,对长期缺施磷肥水稻土进行了3.5年平衡施肥试验。试验采取盆栽水稻的方式,在长期缺施磷肥的红壤性水稻土上比较不施磷肥（NK）、平衡施用氮磷钾无机肥（NPK）、无机氮磷钾肥配施硅肥（NPKSi）、无机氮磷钾肥配施有机肥（无机肥占3/5）、NPK基础上增施磷肥（NKhP）、NPKM基础上增施磷肥（NKhPM）处理的土壤肥力、土壤微生物特性、土壤磷的渗漏量以及地上部水稻产量、养分利用率、磷肥利用率的变化。试验表明,平衡施肥处理NPK、NPKSi、NPKM、NKhPM显著提高水稻产量,比不施磷肥（NK）平均增产147%,其中NPKM提高152%;能提高土壤肥力,比不施磷肥土壤有机质含量平均提高18.5%,其中NPKM提高30.1%;显著提高土壤微生物生物量,比不施磷肥土壤微生物生物量碳（MBC）平均提高57.2%,其中NPKM提高87.1%;提高氮素、钾素养分利用率,比不施磷肥平均分别提高120.3%、33.6%,其中NPKM分别提高152%、43%。而长期重施无机磷肥处理（NKhP）虽然水稻产量比不施磷肥处理提高125.1%,但因土壤中磷酸根离子含量过高影响土壤微生物正常生长,土壤微生物活度比不施磷处理降低9.4%,土壤微生物量碳（MBC）降低2.4%,稻田土壤微生物生态系统质量劣化。此外,重施磷肥处理（包括NKhP、NKhPM）易导致稻田水体的磷污染。各处理比较,NPKM综合生态效应最佳,以下依次是NKhPM、NPKSi、NPK,NKhP,NKhP对稻田土壤微生物生态系统产生负效应。根据试验结果,平衡施肥是恢复缺磷水稻土的有效措施,其中在平衡施用氮磷钾化肥的基础上增施有机肥或硅肥效果较好。     

太湖地区水稻土的健康质量问题及调控对策

从可持续生产安全、营养农产品角度 ,比较系统地阐述了土壤健康质量的概念和内涵 .同时根据土壤健康质量的概念 ,对太湖地区 13个省市级水稻丰产示范方及其灌溉河流淤泥进行了调查 .结果表明 ,太湖地区水稻土N、P含量相对较高 ,但引起面源污染的可能性较小 ,同样水稻土中的重金属含量基本上在环境背景值范围内 ,但点源污染不可忽视 .DDT和六六六的残留也在标准允许范围内 ,生命有益元素Se处于相对缺乏程度 .然而 ,由于乡镇企业的发展 ,三废的肆意排放 ,灌溉河流的富营养化及重金属污染极为严重 .部分河流淤泥中重金属Cu和Zn的含量分别高达 5 4和 7 2mg·kg-1.针对上述情况及发展趋势 ,提出了一些相应的主要控制措施 .     

Comparison of crop productivity and soil microbial activity among different fertilization patterns in red upland and paddy soils

Soil enzyme activity and microorganism community can be changed through different long-term fertilization patterns. However, the effect of different fertilization practices on soil microorganisms might differ among crop systems. The objective of the study was to reveal the change of soil enzyme activity and soil microorganism community in different fertilizations both in upland and paddy soils. Therefore, based on long-term fertilization experiments in upland soil started in 1986 and adjacent paddy soil experiment commenced in 1981, with both consisting of 4 treatments: Control (no fertilization), N (only nitrogen fertilizer), NPK (nitrogen, phosphate and potassium fertilizers) and NPKM (nitrogen, phosphate and potassium fertilizers plus organic manure), grain yield, soil fertility, activities of soil urease, catalase, acid phosphatase, microorganism community (the number of bacteria, fungus and actinomycete) were analyzed. The result showed that: the highest grain yield was attained under the application of chemical fertilizers plus manure, as compared with Control, NPKM significantly increased the grain yield by 908.63% in corn and 118.80% in rice (p < 0.05). Meanwhile, NPKM treatment increased significantly soil organic matter and nutrient contents in upland and paddy soils. Interestingly, there was no significant difference in soil pH among all the treatments of paddy soil, but in upland, NPKM increased pH in comparison to Control by 23.06% (1.15 units of pH). Compared with Control, soil urease, catalase activities, bacteria and actinomycete numbers of NPKM were increased by 321.39%, 129.64%, 229.79%, 85.81% in upland soil, and 25.11%, 251.12%, 292.83%, 196.34% in paddy soil. However, in paddy soil, the soil acid phosphatase activity of Control, NPK and NPKM treatments were higher than upland soil by 34.87%, 44.81%, 52.73% and 30.11%. Then, the soil fungus and actinomycete numbers of paddy soil were lower than upland soil by 20.20% and 88.29%. Therefore, it indicated that long-term application of chemical and organic fertilizers delivered highest productivity in both experiment but the effect of fertilizer practices differed between land uses.     

连续免耕对不同质地稻田土壤理化性质的影响

以我国南方地区典型的单季水稻生产大田为研究对象,按土壤质地分为壤质和粘质两个系列,探讨不同质地稻田土壤理化性质变化对连续免耕的响应规律。结果表明,在无秸秆覆盖条件下,随着免耕年限的增加,壤质和粘质稻田土壤的耕层均有紧实度提高的趋势,特别是粘质土壤,导致耕层变浅。与常年翻耕土壤相比,免耕6a后壤质水稻土0—20 cm土层的紧实度值平均增加了32%,而粘质的平均增加了90%。在相同免耕年限条件下粘质稻田土壤容重的增加也比壤质土壤的明显。壤质土壤0—10 cm土层有机质和碱解氮含量随免耕年限延长而提高,而在粘质土壤则显著降低。无论是壤质还是粘质土壤,连续免耕多年后土壤速效磷均在耕层(0—20 cm)富集,而速效钾则相反。总体而言,壤质水稻土对免耕的适宜性要优于粘质土壤;应根据土壤质地的不同选择性地实施免耕技术,并结合秸秆覆盖,以实现免耕稻田土壤的可持续利用。     

Bionic Research on Fish Scales for Drag Reduction

To reduce friction drag with bionic method in a more feasible way,the surface microstructure of fish scales was analyzed attempting to reveal the biologic features responding to skin friction drag reduction.Then comparable bionic surface mimicking fish scales was fabricated through coating technology for drag reduction.The paint mixture was coated on a substrate through a self-developed spray-painting apparatus.The bionic surface with micron-scale caves formed spontaneously due to the interfacial convection and deformation driven by interfacial tension gradient in the presence of solvent evaporation.Comparative experiments between bionic surface and smooth surface were performed in a water tunnel to evaluate the effect of bionic surface on drag reduction,and visible drag reduction efficiency was obtained.Numerical simulation results show that gas phase develops in solid-liquid interface of bionic surface with the effect of surface topography and partially replaces the solid-liquid shear force with gas-liquid shear force,hence reducing the skin friction drag effectively.Therefore,with remarkable drag reduction performance and simple fabrication technology,the proposed drag reduction technique shows the promise for practical applications.     

西双版纳地区稻田CO2排放通量

采用静态暗箱-气相色谱法对云南西双版纳地区单季稻田CO2排放及氮肥、水热因子对CO2排放的影响进行田间原位观测研究.试验设3个氮肥水平处理:N0(0 kg N hm-2)、N150(150 kg N hm-2)和N300(300 kg N hm-2).结果表明,受一天温度变化的影响,西双版纳地区稻田生态系统呼吸日变化为单峰型,其最大值出现在11:00～13:00之间,最小值出现在凌晨.稻田土壤呼吸呈明显的季节变化趋势,土壤呼吸平均速率为水稻收获后休闲季节>种植前休闲季节>水稻生长季节,差异达到1%显著水平.不同季节影响土壤呼吸的环境因子不同.土壤水分含量低于34%时,土壤呼吸速率与土壤含水量呈正相关,达5%显著水平;地面淹水时,土壤呼吸速率与淹水深度呈1%极显著负相关;水分含量高于38%时,土壤呼吸速率与温度呈极显著指数相关.长期考虑(整个生长季节),氮肥的施用对稻田土壤呼吸和生态系统呼吸无影响;N300处理抑制植株呼吸作用,单位生物量呼吸速率下降.氮肥的施用对土壤呼吸有短期影响,氮肥用量增加,土壤呼吸速率增加.计算得出N0、N150和N300处理年土壤呼吸量分别为6.27、6.31 t C hm-2 a-1和5.89 t C hm-2 a-1;年净固定大气中CO2-C分别为1.41、2.22 t C hm-2 a-1和1 11 t C hm-2 a-1,表明西双版纳稻田生态系统是碳汇.