Optimization of a supercritical fluid extraction/reaction methodology for the analysis of castor oil using experimental design

The aim of this work was to optimize a supercritical fluid extraction (SFE)/enzymatic reaction process for the determination of the fatty acid composition of castor seeds. A lipase from Candida antarctica (Novozyme 435) was used to catalyze the methanolysis reaction in supercritical carbon dioxide (SC-CO(2)). A Box-Behnken statistical design was used to evaluate effects of various values of pressure (200-400 bar), temperature (40-80 degrees C), methanol concentration (1-5 vol %), and water concentration (0.02-0.18 vol %) on the yield of methylated castor oil. Response surfaces were plotted, and these together with results from some additional experiments produced optimal extraction/reaction conditions for SC-CO(2) at 300 bar and 80 degrees C, with 7 vol % methanol and 0.02 vol % water. These conditions were used for the determination of the castor oil content expressed as fatty acid methyl esters (FAMEs) in castor seeds. The results obtained were similar to those obtained using conventional methodology based on solvent extraction followed by chemical transmethylation. It was concluded that the methodology developed could be used for the determination of castor oil content as well as composition of individual FAMEs in castor seeds.     

夹持自锁式棉花精量穴播轮的研究

针对夹持自锁式棉花精量穴播轮在使用中存在的问题及其产生的原因,设计了挡种圈和投种器,改进了取种机构。介绍了其工作原理,计算得出其结构尺寸,并从理论上分析了充种、清种和落种过程,建立了充种、清种、落种模型。田间试验表明,改进后穴播轮的充种可靠性能明显增强,有效地解决了由于振动脱落种子和落种卡滞而造成的空穴问题。     

Optimizing ultraperformance liquid chromatographic analysis of 10 diterpenoid compounds in Salvia miltiorrhiza using central composite design

A rapid, sensitive, reproducible, and accurate ultraperformance liquid chromatographic (UPLC) method was developed for the simultaneous determination of 10 diterpenoid compounds (tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone I, 1,2-dihydrotanshinquinone, methylenetanshinquinone, miltirone, 5,6-dehydrosugiol, sugiol, and przewalskin) in Salvia miltiorrhiza for the first time. Central composite design was applied as a powerful tool to optimize the most dominant parameters that influence the resolution of UPLC, that is, gradient, flow rate, and column temperature. Under optimum conditions, all peaks except 1,2-dihydrotanshinquinone and methylenetanshinquinone could be baseline separated within 8 min. Furthermore, the contents of these compounds in S. miltiorrhiza samples collected from different provinces of China have also been compared. The results showed that UPLC is one of the most efficient methods for the analysis of diterpenoid compounds in S. miltiorrhiza and that it is a potential method for quality control of this valuable traditional Chinese medicine.     

Optimization of arsenic and pentachlorophenol removal from soil using an experimental design methodology

Purpose

In this study, a soil-washing process was investigated for arsenic (As) and pentachlorophenol (PCP) removal from polluted soils. This research first evaluates the use of chemical reagents (HCl, HNO₃, H₂SO₄, lactic acid, NaOH, KOH, Ca(OH)₂, and ethanol) for the leaching of As and PCP from polluted soils.

Materials and methods

A Box–Behnken experimental design was used to optimize the main operating parameters for soil washing. A laboratory-scale leaching process was applied to treat four soils polluted with both organic ([PCP] _i ?=?2.5–30 mg kg^?1) and inorganic ([As] _i ?=?50–250 mg kg^?1, [Cr] _i ?=?35–220 mg kg^?1, and [Cu] _i ?=?80–350 mg kg^?1) compounds.

Results and discussion

Removals of 72–89, 43–62, 52–68, and 64–98 % were obtained for As, Cr, Cu, and PCP, respectively, using the optimized operating conditions ([NaOH]?=?1 N, [cocamidopropylbetaine] _i ?=?2 % w w^?1, t?=?2 h, T?=?80 °C, and PD?=?10 %).

Conclusions

The use of NaOH, in combination with the surfactant, is efficient in reducing both organic and inorganic pollutants from soils with different levels of contamination.     

优化实验内容,改进教学方法,提高微生物学实验教学效果

微生物学实验是一门非常重要的基础课实验,在微生物学的教学中占有举足轻重的地位。通过合理地设置实验内容,采用科学的教学方法,提高了教学效果,培养了学生观察、思考、分析和解决问题的综合能力,为学生进一步学习有关专业课程打下良好基础。     

A new two-stage sampling design for estimating the maximum average time to flower

A horticulturist was considering the number of days (X) each variety took from planting seeds to reach the stage when the first bud appeared for three local marigold varieties. The data X could be recorded with accuracy of one-half day. The primary interest was to estimate the maximum waiting time between “seeding” and “first budding” among three varieties under consideration. It was thought that a 99% confidence interval with width one day would suffice. The horticulturist felt comfortable to assume a normal distribution for the response variable. He provided positive lower bounds for the variances which forced pilot sample sizes to become unequal. We are not aware of any existing methodology with unequal pilot sample sizes that would readily apply here. Accordingly, a new two-stage sampling design was developed and implemented. The gathered data validated all assumptions made during the course of this investigation. Important exact as well as large-sample properties of the proposed methodology are highlighted (Theorem 1). This methodology is proven to be theoretically superior (Theorem 2) to the existing methodology for large sample sizes provided that the pilot sizes could be “chosen” equal. For the experimental data on hand, the superiority of the new methodology has also been indicated (Section 4.3). The solution to the primary estimation problem ultimately led to a natural and yet nontraditional selection problem involving identification of the “worst” marigold variety. For this selection problem, a practical approach is developed (Section 4.4) for evaluating the associated probability of correctly selecting the worst marigold variety.     

Habitat loss and the habitat fragmentation threshold: an experimental evaluation of impacts on richness and total abundances using grassland invertebrates

Based on empirical analyses and computer-based modelling, it has been suggested that the impact of habitat loss is essentially independent of habitat fragmentation when >10-30% of the original habitat is left and that habitat fragmentation is influential only when less that this amount remains. This is the threshold effect of habitat fragmentation. In many systems, effects of habitat loss cannot be distinguished from those of habitat fragmentation in a way needed to critically evaluate the existence of the threshold effect. Therefore, we used an experimental model system (EMS) that was constructed to produce multiple micro-landscapes in which the habitat-loss and habitat-fragmentation impacts were potentially distinguishable. We used responses of terrestrial invertebrates to measure the impacts. We did not find an interaction between habitat-loss and habitat-fragmentation effects in the predicted fashion, although it is possible the threshold of habitat loss we used for the experiments (90%) may have still been above a critical level for the invertebrates. The only significant components were a strong ‘edge-centre’ difference in both richness and abundance, and a temporal change in both variables. Thus, in this EMS, there was little support for the threshold phenomenon or for general effects of habitat loss and fragmentation although this conclusion needs to be tempered by the limited duration of the experiment.     

Electrochemical estimation of the polyphenol index in wines using a laccase biosensor

The use of a laccase biosensor, under both batch and flow injection (FI) conditions, for a rapid and reliable amperometric estimation of the total content of polyphenolic compounds in wines is reported. The enzyme was immobilized by cross-linking with glutaraldehyde onto a glassy carbon electrode. Caffeic acid and gallic acid were selected as standard compounds to carry out such estimation. Experimental variables such as the enzyme loading, the applied potential, and the pH value were optimized, and different aspects regarding the operational stability of the laccase biosensor were evaluated. Using batch amperometry at -200 mV, the detection limits obtained were 2.6 x 10(-3) and 7.2 x 10(-4) mg L(-1) gallic acid and caffeic acid, respectively, which compares advantageously with previous biosensor designs. An extremely simple sample treatment consisting only of an appropriate dilution of wine sample with the supporting electrolyte solution (0.1 mol L(-1) citrate buffer of pH 5.0) was needed for the amperometric analysis of red, rosé, and white wines. Good correlations were found when the polyphenol indices obtained with the biosensor (in both the batch and FI modes) for different wine samples were plotted versus the results achieved with the classic Folin-Ciocalteu method. Application of the calibration transfer chemometric model (multiplicative fitting) allowed that the confidence intervals (for a significance level of 0.05) for the slope and intercept values of the amperometric index versus Folin-Ciocalteu index plots (r = 0.997) included the unit and zero values, respectively. This indicates that the laccase biosensor can be successfully used for the estimation of the polyphenol index in wines when compared with the Folin-Ciocalteu reference method.     

基于多目标算法集热/蒸发器微通道结构优化

为提升微通道集热/蒸发器流动与传热性能,该研究通过多目标算法对集热/蒸发器微通道孔结构进行优化。首先,建立集热/蒸发器流动传热耦合模型,通过试验验证模型准确性;其次,采用响应曲面法拟合集热效率和压降的目标函数,建立以微通道集热/蒸发器结构参数为变量的双目标优化模型,并通过多目标粒子群优化算法得到集热效率和压降的Pareto优化解集,用K-means聚类算法对优化解集进行分类;最后,采用不同季节典型工况试验数据确定最佳微通道孔结构尺寸。研究结果表明：集热效率和压降目标函数的决定系数R2分别为0.995和0.999,拟合精度高;孔长、孔宽及孔间距对集热效率和压降影响显著;最终确定孔长1.27 mm、孔宽1.53 mm、孔间距0.39 mm为最佳微通道孔结构尺寸,与原结构相比,集热效率平均提高了8.29%,压降平均降低了11.05%。此方法提供了一定工况范围的优化解集,提升了微通道集热/蒸发器流动与传热性能。     

盐渍化灌区玉米施氮量阈值DNDC模型模拟

为了寻求保障农业生产和环境友好的适宜施氮量,该研究利用内蒙古河套灌区2 a田间试验数据对脱氮-分解作用模型(Denitrification-Decomposition Model,DNDC)进行了率定与验证,模拟并研究了影响硝态氮淋失量和植株吸氮量的关键因素,以及玉米施氮量阈值.结果表明:1)DNDC模型可以较好地模拟...     

Analysis of Kjeldahl digests by the salicylate method: Optimizing pH and buffering improves both sensitivity and precision

Abstract

Digest acidity can interfere strongly with ammonium analysis using salicylate‐indophenol colorimetry, but many methods over‐neutralize acids so that buffering capacity and sensitivity are reduced. To optimize analysis of acidic digests, we replaced the phosphate buffer with salicylate. Base was added stoichiometrically to neutralize acids and dissociate one‐half the salicylate to reach the phenolic pKa (approx. 13). Sample flow was 20% of total flow and a 60°C water bath was used. This gave optimal sensitivity and minimized interferences due to acidity fluctuations. The limit of detection was 1 μM in digest solution.     

Evaluation of experimental plot design for a sloping and eroding site

Abstract

Sloping and eroding soils are often avoided by many agronomists when selecting a site for long term crop or soils research due to concerns about the impact of soil variability on experimental results. The extent of soil loss and erosion phase was determined by comparisons of soil properties at the cultivated site with a forest site having similar soil, slope and landscape characteristics. The cultivated site was dominated by the moderately eroded phase of the Grantsburg soil with approximately 7.5 cm of soil (38% of upper 20 cm of original soil) eroded during the previous 80 years. Prior to the establishment of the tillage treatments of no‐tillage (NT); chisel‐plow (CP); and moldboard plow (MP), a number of selected soil property parameters were examined to measure the inherent soil conditions that existed within the experimental area, and to test the precision of the experimental design. An experimental design was selected which fit within the field boundaries, landscape position, soil and slope constraints. The experimental design was a Youden Type III, and Incomplete Latin Square, that allowed for randomization of treatments to the plots by both row (block) and column (replication) to control random variability in the two directions. Overall, the experimental design selected to control random variability that existed within the experimental area was effective. This was evidenced by the lack of significant differences among most of the tillage treatment locations with respect to the background data collected.     

Optimizing water,nitrogen and crop density in canola cultivation using response surface methodology and central composite design

Abstract

Optimisation of water and nitrogen use is an effective management tool to conserve resources and reduce environmental pollutions. Response surface methodology (RSM) is defined as a collection of mathematical and statistical methods that are used to develop, to improve or to optimize a product or process. In order to determine optimum levels of water, nitrogen and planting density of canola (Brassica napus L.), a 2-year experiment (2010–2011) was carried out by central composite design as RSM at the research station of Ferdowsi University of Mashhad. The treatments were designed based on low and high levels of irrigation (1500 and 4000 m³ ha^?1), nitrogen (0 and 400 kg N ha^?1) and density (50 and 150 plant m^?2) as independent variables. Furthermore, seed yield, nitrogen losses, nitrogen use efficiency (NUE) and water use efficiency (WUE) were measured as response variables in a full quadratic polynomial model. Optimum levels of irrigation, nitrogen and planting density were suggested to achieve the target range of dependent variables based on three scenarios: economic, environmental and eco-environmental. The results showed that increasing irrigation and fertilizer led to an increase in seed yield and nitrogen losses, whereas increasing canola density resulted in an increase in seed yield but a decrease in nitrogen losses. The optimum levels of water, fertilizer and density based on environmental scenario were 1802 m³ ha^?1, 11 kg N ha^?1 and 122 plant m^?2, respectively. To achieve optimum conditions under the economic scenario, it is necessary to use 3411 m³ water ha^?1, 178 kg N ha^?1 and 119 plant m^?2. Amounts of 2347 m³ water ha^?1, 92 kg N ha^?1 and 114 plant m^?2 were found to be the optimum conditions for the eco-environmental scenario. In general, it seems that resource use based on the eco-environmental scenario may be the most favorable cropping strategy for canola production.     

基于自纠正NMS-ByteTrack的套袋葡萄估产方法

针对套袋后的葡萄体积增加和葡萄叶片表面积大容易出现重叠遮挡,及人工拍摄视频的速度不稳定可能导致套袋葡萄目标丢失的问题,该研究提出一种基于自纠正NMS(non-maximum suppression)-ByteTrack的套袋葡萄估产方法。该方法首先通过目标检测方法YOLOv5s检测视频中的套袋葡萄,将检测阶段的NMS操作后置到追踪阶段,保留因遮挡而被过滤的果实检测框;其次在ByteTrack的基础上加入相机运动补偿和改进的卡尔曼滤波算法,以自动纠正果实预测框的位置并进行追踪;最后提出一种划线计数策略对套袋葡萄自动计数。试验结果表明,该方法的多目标追踪准确率、多目标追踪精度和ID调和平均数分别为64.6%、82.4%和80.8%,相比ByteTrack分别提高了1.7个百分点、1.0个百分点和4.1个百分点,平均计数精度达到82.8%。因此,基于自纠正NMS-ByteTrack的估产方法能有效解决套袋葡萄的追踪计数问题,实现对套袋葡萄更精确地估产。     

Testing the precision of a weighable gravitation lysimeter

Tests were carried out to determine the weighing precision of a 2 m deep lysimeter with a 1 m² cross‐sectional area and a total mass of 3500 to 3850 kg, depending on the soil water content. The weighing mechanism consists on three shear‐stress cells laid out for a load capacity of 1320 kg each. Mass changes as small as 20 g, which is equivalent here to a water gain or loss of 0.02 mm, can be measured with good accuracy and stability under favorable environmental conditions (low wind speed, relatively constant temperature). This precision does not depend on the position on the lysimeter where the mass change occurs and is as good as the best values reported in the literature for other lysimeters. To prevent water and debris from entering the cleavage between lysimeter vessel and pit casing, a rubber collar can be placed across the cleavage. It is attached to the casing and extends about 1–2 cm into the vessel. Although the collar is not supposed to touch the vessel, it does at a few points. This seriously lowers weighing precision, because this contact exerts forces on the vessel, which distort the true weight. Hence, one should refrain from using this type of collar and develop another one. Weighing precision decreases with increasing wind speed, because wind exerts forces on the lysimeter vessel and can thus alter its apparent weight. It is temperature‐dependent, too.     

基于遥感的区域蒸散研究进展

以基于遥感的区域蒸散研究发展为主线,根据国内外最新研究进展介绍了剩余法、遥感反演的指数和P-M公式结合计算的方法。重点对剩余法中的3种模型：单层模型、双层模型和多层模型进行了阐述,为区域蒸散的研究提供了借鉴。通过对不同模型优缺点和适用范围的比较以及一些问题解决方法的描述得出：基于遥感的区域蒸散研究理论发展已经比较成熟,今后应加强模型在实际应用中的完善和发展。     

多因素耦合的光伏水泵提水系统配置优化方法

为探究提水效率影响因素及系统配置对光伏水泵提水系统性能影响,该研究利用光伏水泵循环提水系统,探究不同辐照强度、阀门开度、提水高度下光伏组件利用效率、水泵运行效率、管路效率变化规律,并构建系统流量计算模型,根据该模型计算各个区间的提水量占比及不同提水高度下提水系统的参数,根据该系统整体效率和太阳能利用率确定最优提水高度;在此基础上,通过增加光伏组件面积及蓄水池数量降低提水系统提水成本及提高太阳能利用率,并确定提水成本最低时光伏组件面积和蓄水池数量。研究结果表明：确定光伏组件利用效率随辐照强度变化关系及水泵高效率运行区间,并确定光伏水泵最优提水高度为20 m,太阳能利用率为64.05%,整体利用效率为4.521%,提水成本为0.151元/m³;在最优提水高度的基础上,讨论了增加光伏板面积及蓄水池数量对太阳能利用率与提水成本的影响,当提水成本最低时,光伏板面积为3.71 m²,成本为0.143元/m3,太阳能利用率为90.83%;蓄水池数量为4个,成本为0.145元/m³,太阳能利用率为94.62%,表明增加光伏板面积和蓄水池...     

基于改进最小化SNAP的植保无人机作业轨迹优化算法

轨迹优化是实现植保无人机自主作业路径规划的重要环节，合理高效的轨迹优化算法能使植保无人机安全快速地跟踪轨迹作业，提升作业稳定性与精准性。针对传统最小化SNAP算法偏移误差较大、时间分配不合理的问题，该研究提出一种针对植保作业场景的改进最小化SNAP轨迹优化算法。首先，运用机载载波相位差分(real-time kinematic,RTK)模块采集作业地块地形数据并搭建三维空间地图，基于空间地图采用牛耕法规划初始作业路径；其次，通过改进最小化SNAP算法优化作业路径，结合初始轨迹状态参量构建时间分配函数，解算得到当前最优时间分配；然后，重构最小化SNAP轨迹约束函数，添加位置偏移量梯度惩罚因子，采用最优化方法求解轨迹多项式系数；最后，联合无人机位置控制周期与轨迹多项式实例化航迹点，作为无人机运动的位置期望。试验结果表明，相较于传统最小化SNAP算法，本文算法在同等作业时间前提下，平均加速度减小7.82%，平均偏移误差减小45.56%，对轨迹偏移的抑制效果明显，并降低了加速度在地头转向处的超调，作业轨迹更加精准，作业速度更加平稳，可为植保无人机的轨迹优化策略提供参考。     

Integrated toxicity evaluation of a pulp deposit using organisms of different trophic levels

Purpose

In order to assess possible adverse effects originating from pulp deposits in a Swiss lake, a sediment quality triad approach was applied with chemical, ecotoxicological and ecological assessment methods.

Materials and methods

To obtain an integrative picture of the potential ecotoxicological effects on organisms of different trophic levels, four test procedures were applied. The acute effects of pulp deposit pore water on a decomposer, the amphipod Gammarus fossarum, were monitored. Chronic toxicity of the pore water was evaluated on primary producers via a growth inhibition test with unicellular green algae (Pseudokirchneriella subcapitata) and on secondary consumers in a reproduction test with the water flea Ceriodaphnia dubia. To evaluate the effects of the pulp deposit on sediment inhabitants, a whole-life-cycle test with the non-biting midge Chironomus riparius was undertaken. Chemical assessment included dissolved organic carbon, extractable organic halogenic compounds, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals. The composition of the macrozoobenthos community was analysed in order to assess the ecological effects.

Results and discussion

G. fossarum displayed increased locomotor activity at 12.5% but not at 25% sample concentration during a short-time exposure of 20 h. Chronic effects compromised the reproduction and growth of C. dubia (lowest observed effect concentration, 12.5% sample concentration) with zero population growth in 100% pulp deposit pore water. In 100% pulp deposit, C. riparius exhibited increased mortality at 10 and 17 days after oviposition. Pulp deposits of 50% and 100% concentration caused a significantly lower emergence compared with the reference treatments (lake sediment and quartz sand). Additionally, the locomotor activity of chironomids decreased significantly in 25–100% pulp deposit. No chronic effects of pulp deposit pore water on algae photosynthesis and growth could be detected. The bioassay results were in accordance with an elevated content of PAHs, PCBs and metals in the pulp deposit. Significantly more organisms known to be tolerant to organic pollution were present within the macrozoobenthos community.

Conclusions

In general, for sediment inhabitants such as chironomids, the pulp deposit has to be classified toxic. In the present test setup, the toxicity of the pulp deposit was reflected better by the chronic test systems applied than by the acute ones. The applied testing framework could be a suitable tool to assess the risk of contaminated sites, and this information will help decide whether risk mitigation measures should be taken. In addition, with a similar approach, the success of any mitigation measures taken can be assessed.     

基于TRIZ-AD的集成式油菜气力精量排种装置设计

针对现有气力式播种机排种装置的传动和供气系统复杂、机械结构无法适配智能变量作业、气力供给风压消耗大且稳定性差等问题，该研究应用发明问题解决理论（theory of inventive problem solving, TRIZ）与公理化设计（axiomatic design theory, AD）方法，开展油菜气力精量排种装置设计。首先使用TRIZ技术成熟度预测和进化定律分析，阐明了排种技术发展阶段和进化路径及潜力；其次建立基于TRIZ和AD集成的设计过程模型，求解时在功能域到结构域映射过程中引入TRIZ工具，采用“冲突解决原理”解决现有排种装置中涉及的传动方案、供气系统矛盾冲突，分析对改善结构参数有用的发明原理和对应的方案，最终确定电机直接驱动排种盘和风机内置气室的解决方案，构造并求解其原始设计矩阵，并通过独立公理和信息公理判断该解决方案的合理性及最优化。最后进行电机风机集成式油菜气力精量排种装置设计，确定电机风机同侧排布技术方案，集成电机驱动简化传动，集成风机取消输气管道降低风压损失。台架试验结果表明，设计的集成式排种器排种性能满足油菜单粒排种要求，吸种负压绝对值取1.0～2.0 kPa、作业速度小于7 km/h时，排种合格指数均大于90%，且合格指数达到90%需要的风压低于现有排种装置风机和输气管道布局所需风压。本研究可为气力式排种器设计提供思路和参考。