Cultivar differences in gaseous 1-methylcyclopropene accumulation in whole and fresh-cut apple fruit

A number of studies have shown that responses of apple fruit to 1-methylcyclopropene (1-MCP) vary considerably among cultivars. This study was designed to determine if cultivars show differences in accumulation of gaseous 1-MCP. Apple fruit were placed in 1.76 L jars that were sealed and injected with 20 μL L⁻¹ 1-MCP. After 12 h, samples of intercellular atmosphere were removed and analyzed for 1-MCP concentration. Accumulation of internal gaseous 1-MCP varied markedly among cultivars, ranging from 0.14 ± 0.06, 0.22 ± 0.03, and 0.77 ± 0.30 in ‘Redcort’, ‘McIntosh’, and ‘Empire’, respectively, to 2.10 ± 0.28, 3.33 ± 0.13, and 6.93 ± 0.35 μL L⁻¹ in ‘Gala’, ‘Cameo’, and ‘Honeycrisp’, respectively. Accumulation of gaseous 1-MCP was reduced an average of 51% in fruit treated with Sta-Fresh 8711 fruit wax. The role of the epidermis in modulating 1-MCP ingress was determined by measuring gaseous 1-MCP accumulation in fresh-cut tissue. Fresh-cut cortical tissue rapidly depleted headspace 1-MCP (>95%) over a 1-h exposure yet accumulated negligible quantities of internal gaseous 1-MCP. By contrast, cortical tissue treated with ascorbic acid or hypotaurine, or aged for several hours prior to exposure to 1-MCP, showed reduced consumption of headspace 1-MCP and high accumulation of internal gaseous 1-MCP. Levels of internal 1-MCP in cortical tissue from the cultivars generally paralleled those for intact fruit, ranging from 0.23 ± 0.07, 0.37 ± 0.18 and 1.09 ± 0.14 μL L⁻¹ in ‘Empire’, ‘McIntosh’ and ‘Redcort’, respectively, to 2.40 ± 0.71, 4.55 ± 0.15, and 6.24 ± 0.85 in Gala’, ‘Cameo’, and ‘Honeycrisp’, respectively. Although commercial fruit wax influences gaseous 1-MCP accumulation, the comparable accumulation patterns in unwaxed whole and fresh-cut apple fruit suggest that epidermal tissue/native waxes alone do not account for cultivar differences.     

《大学图书馆学报》期刊引用认同实证研究

引用认同是Howard D.White在2001年提出的,它同时对引用和施引期刊进行研究,获得了有关引用的全景,有助于了解期刊之间在研究领域、学术思想上的联系。以CSSCI《大学图书馆学报》2000-2009年的数据为研究对象,采用文献计量学的方法,从自引率、自被引率和同被引等方面来研究期刊的引用认同,分析比较了《大学图书馆学报》与图书情报领域其它期刊的关系密切程度,同时还引进了新期刊扩散因子的概念作为期刊影响因子的补充指标,对《大学图书馆学报》进行分析和评价,揭示该刊的学术水平和办刊质量,为该刊今后的发展及研究提供参考数据。     

Influence of processing temperature on the water vapour transport properties of wheat gluten based agromaterials

The influence of processing conditions (thermoforming temperature) on water vapour transport properties (permeability, sorption and diffusion) of wheat gluten-based films was studied in relation to structural properties (cross-linking degree of the wheat gluten matrix). Increasing temperature from 80 °C to 120 °C led to a significant decrease in material swelling in high moisture environment and a WVP reduction mainly due to a decrease in diffusivity but without important effect on the moisture sorption isotherms. This was attributed to a higher cross-linking degree of protein network for film thermoformed at 120 °C, with a limited mobility and less possibilities of rearrangement in high moisture conditions.     

区域逼近与动态图形法求解大行程液压支撑机构参数及优化

为实现一种作业与运输兼用型地轮机构的状态转换,针对其结构特点研究一种非端部支撑的新型液压支撑方案,以满足在有限的安装空间内实现大工作行程的要求。在建立该机构力学及运动学模型的基础上,通过几何关系及动力约束条件进行参数的区域逼近;确定液压缸安装位置和参数的可行域后,运用动态图形模拟摆梁步进旋转时机构的运动情况,观测参数取值域曲线的运动状态,得出与可行边界线的交点,从而确定在液压系统压力16 MPa条件下,安装臂长度175 mm,安装臂距旋转点357 mm,液压缸缸体长度为916 mm,缸体内径为71 mm。研究及样机试用表明,非端部支撑对置双缸体液压支撑机构能够满足地轮状态转换的需要,且具有结构紧凑、工作行程大的特点。同时,该研究探索并证实了区域逼近与动态图形求解法在解决此类机构的优化与参数求解方面的可行性与有效性。     

恩施市松材线虫病扩散规律研究

利用恩施市历年的松材线虫病除治资料,对该疫区松材线虫病的扩散趋势和发生规律进行了初步分析。结果表明：恩施市松材线虫病的发生范围随着时间的推进,发生地块逐年增多,发生程度逐年加重,发生范围逐年向外围推移。发生面积由最初的2．54km^2扩展到900．00km^2之多,疫木数量呈逐年上升趋势。由于受到山脊阻拦,南北方向的扩散速度与范围远大于东西方向。公路沿线、河流沿岸远重于地势较高的山脊等地。在该病害除治时采用皆伐的方式极易导致环境条件较差的森林群落生境片段化。该研究为恩施市松材线虫病的除治和抑制马尾松群落片段化提供了重要的理论依据。     

Assessing the Role of Competing Anions Silicate and Bicarbonate on Diffusion of P vis-à-vis Its Bioavailability in Different Soils Measured by Resin Disc Technique

The bioavailability of phosphorus (P) depends on its diffusion process. An attempt has been made to study the effects of bicarbonate and silicate on phosphate diffusion through the analysis of its bioavailability. Resin discs were used to determine P diffusion rate (PDR), which was observed to increase in the presence of competing anions in the following sequence: silicate > bicarbonate > control. Phosphorus diffusion rate also increased with added P levels, temperature, and moisture. Added P level in soil is the most important factor, which contributed about 56% of the variation in PDR. The presence of competing anions such as bicarbonate and silicate accounted for 12.5% of the variations of PDR in soil system. Embedded resin discs in fields treated with different treatments showed significant variation of PDR in the following sequence of treatments: mixture of biogas slurry and paddy straw > sodium silicate > only paddy straw > biogas slurry > control.     

The NURBS human body modeling using local knot removal

These days consumers’ various demands are accelerating research on apparel manufacturing system including automatic measurement, pattern generation, and clothing simulation. Accordingly, methods of reconstructing human body from point-clouds measured using a three dimensional scanning device are required for apparel CAD system to support these functions. In particular, we present in this study a human body reconstruction method focused on two issues, which are the decision of the number of control point for each sectional curve with error bound and the local knot removal for reducing the unusual concentration of control points. The approximation of sectional curves with error bounds as an approximation criterion leads all sectional curves to their own particular shapes apart from the number of control points. In addition, the application of the local knot removal to construction of human body sectional curves reduces the unusual concentration of control points effectively. The results may be used to produce an apparel CAD system as an automatic pattern generation system and a clothing simulation system through the low level control of NUBS or NURBS.     

基于Voronoi cell的RNN_k近似查询与计算

在空间数据索引与查询研究领域中,反向k最近邻(RNNk)问题作为反向最近邻问题的泛化扩展近来受到更多关注.所谓RNNk查询就是找到所有以给定查询点为k个最近邻之一的对象点.为了有效地进行RNNk查询,利用分级的Voronoi cell和空间区域划分方法对查询结果进行有效过滤,避免了过多次最近邻查找计算.在初步得到的RNNk结果中,有针对性地分别利用平行于分割线的扫描线和局部扩展的查询区域Q进一步限定了RNN候选点.近似最小平均距离(AMAD)计算则可由近似的RNNk查询结果得到且不受k取值限制.实验结果表明了在3种不同数据分布情况下,本文算法与近似方法的效率和有效性.因此,通过充分利用对数据的过滤与查询空间修剪的近似方法,得到了具有较高查全率和准确率的近似查询和计算.     

Migration of methylene bis thiocyanate in wood and its effect on a wood degrading fungus

The mobility and concentrations of methylene bis thiocyanate (MBT) at different depths of wood billets (200 mm long, 40 mm in diameter) of Pinus radiata were determined using NMR spectroscopy and ICP-ASE. Results were then correlated with the effect of wood MBT concentrations on growth of O. floccosum in a bioassay using stereomicroscopy and confocal laser scanning microscopy (CLSM). The ¹³C NMR spectra showed the presence or the absence of MBT in wood but it was unable to detect small concentrations. ICP-ASE, however produced quantitative data across the depth (40 mm) of the wood billets tested. Within 7 days of storage, MBT penetrated from surface to pith but showed significantly higher concentrations of MBT in surface wood compared to pith wood. Present study highlighted the benefit of using CLSM for fungal detection in wood. The information obtained from ICP-ASE and CLSM analysis suggested to inhibit growth of O. floccosum, the MBT concentration needs to be >55 μg/g of dry wood. Due to its high detection capacity, ICP-ASE is identified as an excellent tool for MBT detection and quantification in wood.     

基于DLA模型模拟植物生长系统的设计与实现

概述了分形理论的产生和DLA扩散有限凝聚模型,提出了基于DLA模型在计算机上进行植物生长模拟的实现方法。并在此基础上,设计了一个基于Visual Basic平台的分形生长模拟系统,并对模拟的结果进行了讨论,同时给出了模拟效果图。