分子蒸馏工艺参数对高碳脂肪醇提取物精制效果的研究

采用分子蒸馏技术进行高碳脂肪醇提取物的精制，试验结果表明，蒸馏压力66.7 Pa，蒸馏温度在160～230℃范围内，随着蒸馏温度升高，馏出物中的二十八烷醇和三十烷醇含量逐渐增加，并在190℃时出现峰值，之后下降；蒸馏温度190℃，蒸馏压力在26.7～266.7 Pa范围内，随着压力的下降，馏出物中的二十八烷醇和三十烷醇含量增加，到133.3 Pa处分别达到最大值。蒸馏温度和压力作为分子蒸馏的关键工艺参数对高碳脂肪醇的精制效果具有显著影响。     

基于振动机理的藜蒿扦插机分苗机构设计与试验

目前,藜蒿栽植主要依靠人工扦插。分苗装置是实现藜蒿机械化扦插的关键部件,为实现藜蒿苗杆的有序进给,该文设计了一种基于振动机理的藜蒿扦插机分苗装置。在分析振动式分苗装置振动机构-曲柄滑块机构运动分析基础上,利用Matlab优化了振动式分苗装置的结构参数,即当该曲柄摇杆机构的连杆、摇杆分别取499 mm、273 mm时,机构达到最好传力效果。利用Ansys对分苗装置的振动特性进行了模态分析,为防止弹簧钢板变形,振动频率应小于98.66 Hz。而后,以曲柄长度、振动频率、轨道倾角为试验因素,开展了藜蒿分苗装置的试验研究。极差分析结果表明,试验台倾角对分苗合格率影响较大,振动频率次之,偏心距影响最小,优化组合为：振动频率36 Hz、轨道倾角6°、曲柄长度14 mm,此优化组合参数下藜蒿苗杆分苗合格率可达86.3%。该研究工作实现了藜蒿苗杆的机械化分苗,为藜蒿扦插机械的进一步研究提供了参考。     

高速公路边坡生态恢复的问题与对策

通过分析当前高速公路边坡生态恢复中存在的问题,认为边坡立地条件差、植被组合简单、生态适应性差、景观效果不佳、岩质陡坡恢复困难、缺乏基础理论研究、恢复成本高和养护管理困难等是当前存在的主要问题.针对这些问题提出了相应对策,如提高生物多样性、培育边坡植物种子市场、建立恢复评价体系、新技术新材料研究、制定科学养护方案和培养恢复专业人才等措施.     

香蕉产地初加工技术分类及集成

香蕉是全球贸易量第一、产量第二的大宗水果,也是中国产量位居前五的水果之一,但它却是中国唯一存在贸易逆差的大宗水果。在国内香蕉不断增产的情况下,香蕉进口数量仍然保持上涨,表明国内市场需求巨大,但同时存在巨大产后损失,其损失量相当于中国香蕉进口量的2倍以上。该文对中国香蕉产地初加工技术进行了分类整理,在遵循层次性、稳定性、开放性、现实性等系统原则的基础上,采用线性分类法对香蕉产地初加工技术进行了纵向层次划分,按所选定的若干个属性或特征逐次地分成相应的类目,形成了以大类、中类、小类、子类划分的层次分明、逐渐展开的分类体系,简洁、清晰地揭示出香蕉产地初加工技术系统的结构与功能。基于上述分类,对目前使用较为广泛的技术进行集成,形成了4种技术集成方案。并对其适用性进行了评价。     

广西大麦生态区划初探

本文根据大麦生育期长短和灾害年份受害程度的不同,将广西大麦划分为四个生态区。分析了影响大麦发展的主要因素,桂南,桂中是大麦光温敏感期遇长期阴雨寡照天气;桂西是秋、冬、春三季干旱;桂北虽抽穗前后光温较宜,但收晒期雨水过多。同时提出各生态区发展大麦的关键技术措施。     

Purification and characterization of acetylcholinesterase from oriental fruit fly [Bactrocera dorsalis (Hendel)] (Diptera: Tephritidae)

An acetylcholinesterase (AChE, EC 3.1.1.7) was purified from the head of the insecticide susceptible oriental fruit fly, Bactrocera dorsalis (Hendel), by affinity chromatography of Triton X-100 extract. The degree of purification was about 8183-fold with recoveries of 52%. The molecular mass of purified AChE was 116 kDa for its native protein (nonreduced form) and 61 kDa for its subunits (reduced form) as revealed on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), suggesting that the homodimer of AChE linked with disulfide bonds. Nondenaturing PAGE of the purified AChE revealed only one molecular form. The maximum velocities (V(max)) for hydrolyzing acetylthiocholine (ATC), propionylthiocholine, and S-butyrylthiocholine were 833.3, 222.2, and 57.5 micromol/min/mg, and the Michaelis constants (K(m)) were 87.9, 26.9, and 195.3 microM, respectively. More than 97% of AChE activity was inhibited by 10 microM eserine or BW284C51, but only 53% of the activity was inhibited by ethopropazine at the same concentration. On the basis of the substrate and inhibitor specificities, the purified enzyme appeared to be a true AChE. Nevertheless, the purified AChE exhibited some distinctive characteristics including (i) a lack of the substrate inhibition phenomenon when using ATC as the hydrolyzing substrate and (ii) a higher V(m) value for ATC than AChE from other insect species. These biochemical properties may show that AChE purified from the oriental fruit fly may have structural differences from those of other insect species.     

Uncertainty analysis in near-surface soil moisture estimation on two typical land-use hillslopes

Purpose

Spatial prediction of near-surface soil moisture content (NSSMC) is necessary for both hydrologic modeling and land use planning. However, uncertainties associated with the prediction are always neglected and lack of quantitative analysis. The objective of this study was to investigate the influences of different sources of uncertainty on NSSMC estimation at two typical hillslopes (i.e., tea garden and forest).

Materials and methods

In this study, stepwise multiple regression models with terrain indices and soil texture were built to spatially estimate NSSMC on two typical land use hillslopes (tea garden and forest) at different dates. The uncertainties due to limited sample sizes used for developing regression models (uncertainty of model parameter), digital elevation model resolutions of 1, 2, 3, 4, and 5 m (uncertainty of terrain indices) and spatial interpolations of soil texture by kriging or cokriging with electromagnetic induction (uncertainty of soil texture), were investigated using bootstrap, resampling, and Latin hypercube sampling techniques, respectively.

Results and discussion

The accuracies of NSSMC predictions were acceptable for both tea garden (the Nash-Sutcliffe efficiency or NSE?=?0.34) and forest hillslopes (NSE?=?0.57). The model parameter uncertainty was more important on tea garden hillslope than on forest hillslope. A significant negative correlation (P?<?0.05) was observed between the model parameter uncertainty and the mean NSSMC of the hillslopes, indicating that the model parameter uncertainty was small when the hillslope was wet. The resolution uncertainty from digital elevation model had a minor effect on NSSMC predictions on both hillslopes. The texture uncertainty was weak on NSSMC estimations on tea garden hillslope. However, it was more important than the model parameter uncertainty on the forest hillslope.

Conclusions

Improving the regression model structure and the hillslope soil texture mapping are critical in the accurate spatial prediction of NSSMC on tea garden and forest hillslopes, respectively. This study presents techniques for analyzing three different uncertainties that can be used to identify the main sources of uncertainties in soil mapping.

     

砖红壤施硼肥对花生产量和食用品质的影响研究

花生是我国主要油料作物之一,是油脂加工业和副食品工业以及医疗等行业的重要原料,在国民经济中占有重要地位[1~3]。近年来,我国花生的种植面积一般在400万hm2左右,居世界第一位[1~3]。研究如何提高我国花生的产量和品质成为世界花生生产重要内容。日本20世纪90年代就有21%的花生直接用于食用,目前欧洲国家食用花生占80%,印度尼西亚食用花生达84%,我国也有食用花生的传统[2,3,5]。花生成为国内外重要的保健食品[2,4],食用花生的品质的研究越来越受到重视[2,3]。花生是硼中度敏感作物,缺硼可导致花生空荚率高,特别是糖分含量降低[5~7,9],从而…     

Inhibitory effect of hot-water extract from dried fruit of Crataegus pinnatifida on low-density lipoprotein (LDL) oxidation in cell and cell-free systems

The dried fruit of Crataegus pinnatifida, a local soft drink material and medical herb, was found to possess potential against oxidative stress. In the preliminary study, the antioxidant potential of a hot-water extract obtained from the dried fruit of C. pinnatifida (CF-H) was evaluated in terms of its capacity of quenching 1,1-diphenyl-2-picrylhydrazyl free radicals (EC(50) = 0.118 mg/mL). After content analysis, it was found that CF-H is mainly composed of polyphenols including flavonoids (6.9%), procyanidins (2.2%), (+)-catechin (0.5%), and (-)-epicatechin (0.2%). The antioxidative bioactivity of CF-H had been assess previously using the models of CuSO(4) as cell-free system and sodium nitroprusside (SNP) plus macrophage RAW 264.7 cells as cell system to induce human low-density lipoprotein oxidation. CF-H was found to inhibit relative electrophoretic mobility and thiobarbituric acid reactive substances at the concentration of 0.5-1.0 mg/mL in the cell-free system and at 0.01-0.10 mg/mL in the cell system. Furthermore, it was found that CF-H decreased the SNP-induced cell lipid peroxidation and reduced glutathione depletion.     

基于产量、氮效率和经济效益的春玉米控释氮肥掺混比例

设置多年多点大田试验,研究多环境条件下控释氮肥与普通尿素不同掺混比例对春玉米拔节期生长发育、成熟期产量及产量构成因素、氮素利用效率和经济效益的影响,并建立产量、氮肥偏生产力和施肥利润与控释氮肥掺混比例之间的关系以确定最佳掺混比例。结果表明,增加控释氮肥掺混比例可促进春玉米拔节期生长发育,其中显著增加叶片数并改善叶片氮营养状况。9个试验综合显示,春玉米产量和施肥利润随控释氮肥掺混比例的增加而显著提高并均在30%时达到最高,分别为10.12 t hm-2和5 071元hm-2,较普通尿素全施处理分别增加了0.98 t hm-2(10.8%)和1 639元hm-2(47.8%)。提高控释氮肥掺混比例获得增产的主要原因是显著增加了春玉米成熟期的穗粒数,同时对收获穗数也表现出积极影响。控释氮肥掺混比例增加显著提高春玉米的氮肥偏生产力,同时土壤氮素依存率则显著下降,两指标均在掺混比例超过30%后不再明显变化。各试验点春玉米的产量、氮肥偏生产力和施肥利润在整体上与控释氮肥掺混比例均存在极显著的一元二次关系,基于此三项指标推算得出适宜掺混比例平均分别为35.1%、35.2%和33.7%。可见,控释氮肥掺混施用有利于促进春玉米生长发育,获得增产增收并提高氮素效率,综合各方面表现确定控释氮肥的最佳掺混比例为30%~35%。