地埋滴灌点源入渗土壤水分运动规律实验研究

通过室内砂土中进行地埋滴灌的实验,对地埋滴灌在砂土中的适应性进行初步研究,为田间试验布置提供依据。通过分析湿润锋的推移速率、特征点的土壤含水率变化规律,发现湿润锋推移速率先是径向大于垂向,随着灌水时间和灌水量增加,水平方向和垂向的湿润锋和含水率趋于平衡。根据对比滴灌带埋深15和20 cm特征点的含水率变化情况,得出埋深15 cm节水效果更好,更利于作物生长。实验还得出湿润比能作为滴灌灌水参数的指标,由于作物种植的间距和作物根系深度之比基本小于1.0,因此在田间实际灌溉中湿润比应控制在1.0左右。     

感应式高压静电喷头雾滴荷电效果影响因素分析

为研究如何在有限的充电电压下获得良好的雾滴荷电效果,首先建立了雾滴荷电过程的等效模型,对影响雾滴荷电效果的关键性参数进行理论推导;然后采取圆环形和仿形两种电极形式,取3个高压电极的关键性技术参数,设计4种不同的高压电极方案;最后配合2、2.5mm两种不同的绝缘层厚度,为雾锥角为80°的空心圆锥雾喷头TR 80-04设计了8种不同的高压静电罩,用网状目标法与法拉第筒法结合的荷质比测量系统对其荷电比进行测量,以荷质比评价其荷电效果的优劣。结果证明:理论分析与试验研究达到了良好的一致性,仿形电极的荷电效果明显优于圆环形电极,且电极宽度、电极中心到喷口的轴向距离与雾滴荷质比正相关,为高压静电罩的合理设计提供了可靠的理论和试验依据。     

施氮深度对‘黄金梨’树氮素吸收、分配及利用效率的影响

以7年生‘黄金梨’树为试材,采用~(15)N示踪技术研究了3个施氮深度[0(表面施氮)、20和40 cm]处理下不同器官对氮素的吸收、分配及利用效率,并探讨了氮素在土壤中的残留及损失。结果表明,梨果实成熟期,果实的Ndff值最高,其他器官的Ndff值均表现为20 cm施氮深度处理显著高于其他处理。各施氮深度处理,~(15)N的分配率均为贮藏器官最高,生殖器官最低。20 cm施氮深度处理的梨树N利用率最高(26.23%),40 cm施氮深度处理最低(15.65%)。N损失率以表面施氮处理最高(54.21%),20 cm施氮深度最低;0~80 cm土层的N残留率以40 cm施氮深度处理最高(31.73%),表面施氮处理最低。因此,本研究中,20 cm深度施氮处理能提高梨树各器官对N肥的吸收征调能力,氮素损失少。     

低溶胀壳聚糖/丝素蛋白复合膜的制备及性能测试

为改善单纯壳聚糖膜用作医用创面敷料在湿环境下的力学性能,将壳聚糖(CS)和家蚕丝素蛋白(SF)混合,采用延流法制备壳聚糖/丝素蛋白(CS/SF)复合膜。物理与机械性能测试表明:CS/SF复合膜的溶胀率较单纯CS膜显著降低,且其溶胀能力具有pH依赖性;CS/SF复合膜的水蒸气透过率较单纯CS膜略有下降,但仍保持在2 043～3 363 g/(m2.d);CS/SF复合膜在湿环境下的力学强度较单纯CS膜显著提高,当加入SF的质量分数为15%时,复合膜的力学性能最好,其拉伸强度为34.5 MPa±1.8 MPa,比单纯CS膜提高近18%,而其断裂伸长率也由初始的83.1%±6.7%提高到119.3%±8.2%。CS/SF复合膜具有较好的药物释放性能,对抗感染药物盐酸万古霉素表现出在初始1 h内的突释行为和随后较长时期的缓释行为,十分有利于降低感染和加速伤口愈合。此外,CS/SF复合膜对STO小鼠胚成纤维细胞具有良好的生物相容性。各项性能测试显示CS/SF复合膜作为医用敷料具有潜在的应用前景。     

Comparison of dietary essential amino acid requirements determined from group‐housed versus individually‐housed juvenile bluegill,Lepomis macrochirus

Two 60‐day experiments were conducted sequentially to determine (i) lysine requirement of juvenile bluegill, Lepomis macrochirus based on the dose–response method, (ii) requirements for other essential amino acids (EAAs) using whole‐body amino acid profile and (iii) whether differences in growth rates of group‐housed versus individually‐housed bluegills lead to different lysine requirement levels because of the presence and absence, respectively, of social hierarchies. Seven, semi‐purified, experimental diets (isonitrogenous, isocaloric) were prepared to contain graded levels of digestible lysine (10–31 g kg⁻¹). Experiment‐1 involved group‐housed bluegills (approximately 27 g, n = 10 fish/chamber, 4 chambers/diet) whereas experiment‐2 involved individually‐housed bluegills (approximately 30 g, n = 1 fish/chamber, 14 chambers/diet). Fish were fed twice daily to apparent satiation. Bluegill growth responses in both experiments generally improved (P < 0.05, anova ) with increasing dietary lysine levels from 10 to 16 g kg⁻¹, and then levelled off with further increase in lysine level (P > 0.05). Optimal dietary lysine level (digestible basis) was estimated to be 15 g kg⁻¹ based on broken‐line regression analyses of relative growth rate and feed conversion ratio with no differences being observed between the two rearing methods. Determined dietary requirement levels for other EAAs ranged from 2.4 g kg⁻¹ (tryptophan) to 15.3 g kg⁻¹ (leucine).     

井渠灌区地下地表水耦合模拟及用水配置研究

针对宁夏惠农区渠井用水比例失调,导致地下水越过适宜埋深造成次生盐渍化的问题。选择惠农区李岗村为试验区,在概化试验区水文地质条件,建立了水文地质概念模型,采用双重节点方式对地表水地下水模型进行耦合,在每个时间段对两者进行联立同时求解,通过HydroGeoSphere进行模型的计算求解,率定和验证模型中的水文地质参数。并通过建立的模拟模型,适时调整用水比例,得到在生态安全埋深下,渠井用水最优比例。     

基于最小二乘法的落叶松木粉粒径数学建模与分析

【目的】建立落叶松木粉粒径与长宽比的数学模型，通过分析数学模型和其二阶导数，揭示木粉长宽比随粒径减小的变化趋势及变化的根本原因，获得最大长宽比对应的粒径，为建立长宽比与力学性能之间的定量关系提供参考。【方法】利用光学显微镜拍摄获得木粉的显微图像，测算获得目标木粉成熟管胞的平均长度、平均宽度以及木粉粒径的大小。通过数字图像处理技术提取单木粉颗粒的矩形度、长宽比：将原始木粉显微图像由 RGB颜色空间转到Lab颜色空间，提取其b分量；对b分量图像用3×3模板进行中值滤波；用K-means算法将去噪后图像聚类为2类，得木粉的二值图像；对二值图像用5×5的结构元素进行先开启后闭合的数学形态学运算；用八连通区域法标记图像中的单木粉颗粒；对标记后图像用目标区域像素点个数统计法计算获得单木粉颗粒的几何面积，用主轴法获得单木粉颗粒的最小外接矩形的长、宽、面积；计算获得单木粉颗粒的长宽比、矩形度数据。采用最小二乘法对木粉粒径与长宽比进行数据拟合，通过分析评判多项式、高斯和傅里叶3种拟合函数后选用高斯方程表达得木粉粒径与木粉长宽比的数学模型，再根据其拟合曲线方程计算得其二阶导数，结合模型的二阶导数和测算得的木粉管胞数据对高斯模型进行分析与讨论。【结果】矩形度不随木粉粒径的减小而变化，均值在0.6～0.8之间。长宽比随粒径减小出现先增大后减小的趋势：木粉粒径在1100～576μm 时，长宽比数值从接近于1开始逐渐增大；木粉粒径为576μm时(与本文目标木粉成熟管胞的平均长度563.82μm接近)，长宽比达到最大数值4.6；木粉粒径在576～30μm时，长宽比逐渐减小；而粒径小于50μm 时(与目标木粉成熟管胞的平均宽度46.498μm接近)，长宽比数值再次趋近于1。【结论】长宽比的变化与管胞破裂密切相关：木粉粒径大于管胞长度时，木粉主要通过纵向断裂使粒径减小；粒径与管胞长度接近时，长宽比较大；粒径小于等于管胞宽度范围内，木粉主要是横向断裂，而长宽比基本不再发生变化且趋近于1。长宽比和冲击强度随粒径减小的变化趋势是一致的，长宽比是影响材料力学性能本质因素之一。     

Regulated deficit irrigation effects on growth, yield, grape quality and individual anthocyanin composition in Vitis vinifera L. cv. ‘Tempranillo’

Regulated Deficit Irrigation (RDI) is an irrigation scheduling technique, originally developed for fruit orchards, that has been successfully adapted for winegrape production. The aim of this work is to evaluate the effect of RDI in vegetative growth, yield and harvest quality in ‘Tempranillo’ vineyards grown under semiarid conditions typical in Mediterranean areas. Two RDI strategies were compared with conventional irrigation practices (CI). CI that consisted in a progressive increase in water deficit as summer progressed, whereas RDI strategies (RDI1 and RDI2) had in common a deficit period just after fruit set and, in RDI2, vines were subjected to an additional stress period shortly after veraison. The experiment was carried out in four consecutive seasons in a commercial vineyard.Water stress at the beginning of berry development resulted in an important reduction of both vegetative growth and berry weight in RDI strategies. No differences in sugar concentration were found between treatments, and RDI berries tended to have lower acidity. The most relevant effect of RDI strategies on grape quality was an increase in anthocyanin and phenolics concentration. In RDI1 berries, this increase was mainly an indirect consequence of smaller berry size. However, in the RDI2 treatment the higher berry anthocyanin concentration reported was not exclusively due to a reduction in berry size. Since harvest quality has been clearly improved by any of the RDI strategies in both years, it can be concluded that RDI constitutes an interesting technique to be applied in ‘Tempranillo’ vineyards grown in semiarid areas aiming to obtain high quality grape.