仿蚯蚓运动多功能开沟器设计及参数优化

针对中国东北地区春播时耕种层土壤温度和含水率较低,严重阻碍大豆根系生长,进而影响大豆发育的难题,该文通过仿生结构设计和理论分析的方法,设计了一种集松土、沟底镇压和开沟功能为一体的仿蚯蚓运动多功能开沟器,其设有的仿蚯蚓动态松土开沟机构可模拟蚯蚓的运动方式对种沟上层土壤进行疏松作业,设有的镇压力调节机构可对种沟下方土壤进行镇压作业。通过参数优化试验和回归分析的方法,研究仿蚯蚓运动多功能开沟器关键结构参数和作业速度对平均土壤温度(0~100 mm)、平均土壤含水率(0~100 mm)和大豆出苗时间的影响规律,并运用Design-Expert和Matlab软件对试验结果进行分析,得出最优参数组合为:作业速度8 km/h、松土机构凸起高度6 mm和波纹圆盘波峰数量15。通过对比验证试验,发现仿蚯蚓运动多功能开沟器相较于传统单元盘和双圆盘开沟器,可提升土壤含水率(0~100 mm)5.92%和4.86%,提高土壤温度(0~100 mm)0.5和0.4℃,提前大豆出苗时间0.5和0.92 d。仿蚯蚓运动多功能开沟器可有效改善土壤耕种层结构,使耕种层土壤达到表层松软和下层坚实的状态,有效提高土壤温度和含水率,进而促进大豆发育,可为提高中国大豆产量提供技术装备支撑。     

基于“三生”视角的煤粮复合区土地利用功能评价

[目的]以河南省新乡市赵固二矿煤粮复合区为典型案例区,对该区土地利用多功能性进行研究,为其区域功能发展提供支撑。[方法]基于研究时序统计年鉴等基础数据,从"三生"功能(生产功能、生活功能、生态功能)角度择选出符合不同子功能的15个指标因子,构建出适用于煤粮复合区的评价指标体系。运用全排列多边形综合图示法对研究区2009—2015年间土地利用功能演变进行量化评价。[结果](1)全排列多边形综合图示法评价结果直观、准确、涉及面广且主观随意性低,适用于区域土地利用功能评价;(2)单项指标显示,2009—2015年间,各子功能的指标偏向侧重度均有所改变,但其主导障碍因子稳定不变;(3)7a间,研究区均以生产功能作为区域主导功能,受区域煤炭开采影响土地集约利用综合指数以2012年为分界点总体先增加后减少,变化速率为快—缓—快。[结论]煤炭开采活动对煤粮复合区土地功能利用有重要影响,区域土地"三生"功能变化及区域土地集约利用程度与区域煤炭事业的发展变化联系紧密。     

獾牙与狗牙的微观结构及摩擦学特性

以獾牙和狗牙为研究对象,采用摩擦磨损试验机进行摩擦磨损试验,考察了獾牙和狗牙的摩擦学性能,利用纳米压痕仪进行力学性能试验,测试了獾牙和狗牙的纳米硬度和弹性模量。试验表明:牙齿的摩擦磨损行为同其微观结构密切相关,獾牙釉质磨斑表面划痕和擦伤痕迹相对轻微,磨损深度为(13.521±1.034)μm,狗牙釉质磨斑表面有较多的裂纹,犁削和擦伤较为严重,磨损深度为(15.429±1.337)μm;牙齿的摩擦磨损性能与其硬度以及显微组织和结构密切相关;獾牙釉质的耐磨性和纳米硬度、弹性模量高于狗牙釉质。该研究为以獾的牙齿为原型将仿生耦合原理应用于刀具的开发提供了理论依据。     

元谋干热河谷水保林营造技术研究

由于城郊水土保持目的多样性,其水土保持效益分析也存在着复杂性,该文以北京郊区十三陵蓄能电站建设造成的人为水土流失治理为例,从安全效益,保健效益,景观视觉环境质量和经济效益角度出发,分析探讨了以旅游为特点的城郊水土保持效益。     

A rapid and simple electrochemical method for evaluating the electron transfer capacities of dissolved organic matter

Purpose  

The evaluation of the electron transfer capacities (ETC) of DOM is important to understand their roles in microbial activity, pollution degradation, and metal mobility. Those currently used methods to quantify ETC, such as Zn and Fe³⁺ assays, are normally time consuming and usually require experience and skills to achieve reproducible results. The aim of this paper is to develop a rapid and simple approach to accurately and directly quantify the ETC of DOM.     

元谋干热河谷水保林营造技术研究

通过对元谋干热河谷现有水土保持植物的试验观测及水土保持林营造技术的试验研究,初步选出适宜于当地气候特点的水土保持林草种１１个,总结出９０￣１００ｄ为袋苗移栽的最佳洁龄,０．６ｍ×０．６ｍ水平沟整地,６月下旬－７月上旬定植为最佳时节的水土保持林营造技术。     

气提式砂滤器在水产养殖系统中的水质净化效果

为解决传统压力式砂滤罐长时间工作后截留大量固体颗粒物而导致的难以反冲洗的问题,该研究在原有设备基础上进行技术改进;研制出了1种可以边工作边反冲洗的气提式砂滤器;气提式砂滤器集过滤、分离、气浮、自动清洗等功能于一体,可以替代传统用于养殖车间的砂滤罐、无阀滤池、微滤机、机械式气浮等物理过滤装置;试验用1~2 mm石英砂作为过滤介质,过滤水以向上流方向从气提式砂滤器底部慢慢上升,污物被石英砂截留,同时,从底部流入定流量气体,使得污物和砂粒同时被提起,最终在顶端的洗砂装置中石英砂被清洗干净并由于重力作用而落回系统,污物和废水从排污口流出;试验表明,气提式砂滤器设备简单、操作简便,不需停机反冲洗,系统运行连续平稳,能耗小并且易于日常维护和检修;数据表明,这种气提式砂滤器对海水循环水养殖系统中的颗粒悬浮物(suspended solids,SS)和化学需氧量(chemical oxygen demand,COD)平均去除率分别为(41.31%±7.72%)、34.04%,同时也降低了氨氮、亚硝酸盐含量,过滤后养殖水颗粒悬浮物质量浓度≤67.33 mg/L。气提式砂滤器在海水循环水养殖系统中进行物理过滤,是1种行之有效的方法,满足了养殖车间的水处理要求。     

Similarities in chemical composition of soil organic matter across a millennia-old paddy soil chronosequence as revealed by advanced solid-state NMR spectroscopy

This study examined the chemical composition of soil organic matter (SOM) along a 2,000-year paddy soil chronosequence in eastern China by use of advanced solid-state nuclear magnetic resonance (NMR) spectroscopy as well as Fourier transform infrared spectroscopy (FTIR), aiming to identify changes in the chemical composition of SOM over a millennium timescale. The results showed that soil organic carbon concentration in the surface soil reached a steady state after 100 years of rice (Oryza sativa L.)–wheat (Triticum sp.) cropping on coastal tidal flats. The ¹³C NMR spectra and fractions of structural groups or components of the whole SOM samples differed little along the chronosequence, suggesting a similar chemical composition in SOM samples regardless of the duration of rice cultivation. The FTIR spectral pattern and relative intensities of some resolved functional groups or components of whole SOM were also similar along the soil chronosequence. The similarities in chemical composition of SOM can be attributed to the rice–wheat cropping system, in which SOM has undergone ongoing turnover under periodical fresh plant material input and wet–dry cropping alternation, leading to a similar chemical composition of bulk SOM.     

The elevational patterns and key drivers of soil microbial communities strongly depend on soil layer and season

Knowledge about the elevational patterns of soil microbial biomass and communities can facilitate accurate prediction of the responses of soil biogeochemical processes to climate change. However, previous studies that have considered intra- and inter-annual variations have reported inconsistent results on the one hand, and they have paid little attention to the effect of soil layer on the other hand. We, therefore, conducted a 4-year in situ soil core incubation experiment along a 2431-m elevational gradient across the dry valley shrubland, valley-montane ecotone forest, subalpine coniferous forest, alpine coniferous forest, and alpine meadow in an ecologically fragile alpine-gorge region on the eastern edge of the Qinghai-Tibetan Plateau. Soil microbial biomass and community composition in the organic and mineral layers were measured using the phospholipid fatty acids (PLFA) method at five critical periods each year. Our results indicated that soil microbial biomass in the organic layer was the highest in the subalpine coniferous forest, followed by the alpine meadow, alpine coniferous forest, and valley-montane ecotone forest. In contrast, soil microbial biomass in the mineral layer was significantly higher in the alpine meadow than in the other sites. Soil microbial biomass exhibited differential seasonal fluctuations at different elevations, resulting in their elevational patterns being strongly intra-annual and inter-annual dependent. Our results revealed that elevation and seasonality significantly affected soil microbial communities. Seasonality had a more substantial effect than elevation on soil microbial communities during the first 3 years of incubation, whereas the relative importance of seasonal and elevational effects on microbial communities was reversed in the organic layer with incubation time. These results are mainly attributed to the magnitude and direction of effect of environmental variables on soil microbial biomass and communities vary with elevation, soil layer, and sampling time. Briefly, the elevational patterns and dominant factors of soil microbial biomass and communities have intense soil layer and temporal specificity, implying that differential responses of soil biochemical processes to climate change might be observed at different elevations.     

牛鲨牙齿微观结构组成和摩擦磨损特性

为研究牛鲨咬合力大的原因,并以牛鲨牙齿为原型设计仿生刀具,以牛鲨上颌齿和下颌齿为研究对象,利用扫描电子显微镜观察牛鲨牙齿的微观结构,利用能谱仪测试牙齿的元素组成。采用微观摩擦磨损试验机进行摩擦磨损试验,考察了牛鲨上颌齿、下颌齿的摩擦学性能,通过激光共聚焦扫描显微镜测量磨损深度,利用扫描电子显微镜观察牛鲨牙齿的磨损形貌。试验表明:釉质层由条状纤维束形成致密的结构,本质层为多孔结构,孔径范围在3~20μm,这些孔洞呈不规则的排布;能谱仪测试结果中,牛鲨牙釉质比牙本质中Ca、F含量高,氟和钙的组合效应可以帮助其在生存环境下有更好的耐酸性和硬度。牛鲨上下颌齿牙釉质磨斑表面有片状磨屑剥落,且有大量的细小磨粒,上颌齿磨损体积约为1.72×10~7μm~3,主要是磨粒磨损;下颌齿出现明显裂纹,磨损体积约为2.11×10~7μm~3,比上颌齿的磨损体积大。上述结果为新型刀具的仿生设计提供理论依据。