高光谱成像快速检测壳聚糖涂膜草莓可溶性固形物

为了对壳聚糖涂膜草莓可溶性固形物含量(soluble solids content, SSC)进行快速检测,该文采用高光谱成像仪(400～1 000 nm)对0,0.5%,1%浓度的壳聚糖(chitosan, CTS)涂膜草莓分别储藏1,2,4 d后进行成像,并测量样本SSC。通过分析SSC发现,0.5%和1%壳聚糖涂膜草莓,其SSC随着储藏天数的增加均高于0浓度壳聚糖涂膜草莓,说明了0.5%和1%壳聚糖涂层抑制了草莓中SSC的降低,能够延长草莓的新鲜口味。随后采用蒙特卡罗-偏最小二乘法(monte carlo-partial least squares, MCPLS)对异常样本进行剔除。对剔除异常样本后的光谱数据进行不同预处理,以确定最优的预处理方法。为提高运行速度和降低数据维数,采用竞争性自适应权重取样法(competitive adaptive reweighted sampling, CARS)和连续投影算法(successive projections algorithm, SPA)进行特征波段选择。最后,采用偏最小二乘回归(partial least square regression, PLSR)和支持向量回归(support vector regression, SVR)法建立回归模型。最终结果表明:SPA-SVR模型效果最佳,0浓度的壳聚糖涂膜的草莓,建模集精度Rc2为0.865,预测集精度Rv2为0.835;0.5%浓度的壳聚糖涂膜的草莓,建模集精度Rc2为0.808,预测集精度Rv2为0.799;1%浓度的壳聚糖涂膜的草莓,建模集精度Rc2为0.834,预测集精度Rv2为0.875。对储藏第4天的部分样本图像进行主成分分析(principal component analysis, PCA),结果显示除第二主成分图像(PC2)中有部分噪声影响外,PC1和PC3均能完整反映草莓信息,且PC3图像明显呈现出不同浓度壳聚糖涂膜草莓的褐变程度,说明不同浓度的壳聚糖涂膜也会对草莓货架期产生不同影响。综上说明利用高光谱成像技术可以实现壳聚糖涂膜草莓SSC快速检测,有效指导草莓保鲜处理。     

杜马斯燃烧法和凯氏定氮法在土壤全氮检测中的比较研究

选用 6组不同全氮含量的土壤样品(梯度为 0%～0.06%、0.06%～0.1%、0.1%～0.2%、0.2%～0.3%、0.3%～ 0.4%和 0.4%～ 0.5%)和 4份土壤有效态成分分析标准物质为试验材料，分别采用杜马斯燃烧法和凯氏定氮法测定其全氮含量，并对两种方法测定结果的精密度、准确度和相关性及检测成本进行了比较分析。对土壤有效态成分分析标准物质全氮含量的检测，两种方法测定结果都接近于真实值，比较两种方法的相对标准偏差(RSD)和相对误差(RE)值，可确定杜马斯燃烧法精密度更高，且准确度更好；对于含氮量范围为 0%～ 0.06%的样品，两种方法的测定值之比(D/K)为 0.692～ 0.965，杜马斯燃烧法测定结果的变异系数为 0.00%～ 9.96%，测定结果不稳定，两种方法的测定值间存在显著的线性相关，但 R2仅为 0.9049；而含氮量大于 0.06%的样品，两种方法的测定值之比(D/K)为 0.940～ 1.104，变异系数均小于 5%，测定结果间存在显著的线性相关(R2=0.9979)。在检测成本方面，完成相同数量样品检测，杜马斯燃烧法所需时间和人力都约是凯氏定氮法的1/2。因而，杜马斯燃烧法是一种环保、高效的土壤全氮检测方法，对于含氮量范围为 0%～ 0.06%的土壤样品，凯氏定氮法的测定结果更接近于真实值，而对于含氮量大于 0.06%的土壤样品，杜马斯燃烧法更加适用。     

Barriers to Open Government Data (OGD) initiative in Tanzania: Stakeholders’ perspectives

Open Government Data (OGD) initiatives are picking up across the globe with their emphasis upon the tenets of transparency, collaboration, and participation. While much of the research has remained confined at unraveling the theoretical and conceptual dimensions of OGD, empirical investigations are visibly lacking, especially in the African context. Using a qualitative research methodology, we analyze the responses received from relevant stakeholders—representatives from public and private sector—regarding their views about the OGD initiative in Tanzania. Our findings show that the OGD initiative in Tanzania is in an emerging stage and there are barriers (organizational, social, legal, and technical) toward instituting a robust OGD initiative in the country. Further, we find that there is inertia among the government departments in terms of publishing data sets. Our findings provide a sounding board for further research on the sustainability of OGD initiatives in Tanzania and the other African countries, by and large.     

播期对直播水稻产量、花后各器官干物质和氮素积累及转运的影响

为探究播期对直播水稻产量、花后干物质和氮素积累与转运的影响,以水稻品种白粳1号、长白9号和龙粳31号为供试材料,设置3个播期（SD1、SD2和SD3）,比较不同播期条件下3个品种的产量、抽穗期和成熟期各器官干物质及氮素积累与转运特点。3个品种抽穗期和成熟期各器官干物质及氮素积累量、抽穗至成熟期各器官干物质及氮素转运量和产量均表现为SD2>SD3>SD1。相关分析表明,产量与成熟期穗干物质及氮素积累量呈显著正相关,与叶片干物质和氮素转运量呈显著正相关。在本试验条件下,播期的推迟提高了3个品种有效穗数及结实率,进而提高了产量,同时促进了各器官物质转运量与转运率的提高。各品种SD2处理的产量及花后干物质、氮素积累量最高,SD2为适宜播期。     

Analyzing the spatial allocation of Japan’s aid to China: A perspective from the relations between aid allocation stakeholders

While the spatial distribution of foreign aid has aroused a widespread academic interest, the existing research is limited mainly to the transnational level and lacks an analysis of aid allocation within a single recipient country. Moreover, more attention is paid to the factors influencing the aid allocation than to the interactions among different aid allocation stakeholders. To fill the research blank, this paper proposes a “three-party relationship model” to analyze the spatial allocation of aid within a recipient county, and uses the case of Japan's aid to China to validate the model. We find most of the aid has been allocated to the economic infrastructure, over time, and the key aid sector has shifted from economic infrastructure to social infrastructure and general environmental protection; The allocation characteristics of total aid and key aid sectors are various; The spatial allocation pattern of aid reflects an interaction between the donor (Japan) and the recipient country (China). The degree of importance of each aid allocation stakeholder is different at different stages of the total life cycle of aid, and the aid allocation stakeholder relationship in the three-party relationship model may be constantly reshaped during the allocation processes of aid in space.     

2018—2020年四川省兽医系统实验室检测能力比对

为评估四川省兽医系统实验室检测能力和水平，2018—2020年四川省动物疫病预防控制中心组织全省21个地市（州）级兽医实验室开展了检测能力比对。结果显示：2018—2020年全省整体平均正确率分别为95.59%、97.09%和97.88%，说明四川省地市（州）级兽医实验室检测能力处于较高水平，能满足非洲猪瘟、禽流感等重大动物疫病检测需要。同时，部分实验室也反映出一些问题，如设备差、检测水平不高、检测报告不规范等。建议加大兽医实验室建设力度，更新完善检测设施设备；加强实验室技术人员培训，提升其检测能力和水平；同时继续推进兽医系统实验室考核工作，加强比对考核。     

Effects of biochar on microbial community in bioflocs and gut of Oreochromis niloticus reared in a biofloc system

Aquaculture International - This study investigated the effects of biochar application on the bacterial community structure in bioflocs and intestines of Oreochromis niloticus cultured in a biofloc...     

<Emphasis Type="Italic">In situ</Emphasis> Cross-linked Chitosan Composite Superfine Fiber via Electrospinning and Thermal Treatment for Supporting Palladium Catalyst

Uniform chitosan fibers (CS/PEO) with diameter of 398±76 nm were prepared by electrospinning with merely 5 wt.% of poly(ethylene oxide) (PEO) loading, and then annealed at elevated temperature without the use of additional crosslinker to improve the thermostability and solvent resistance. Swelling test shows that the CS/PEO composite fibers annealed at 200 oC were stable in 50 wt.% acetic acid aqueous solution. The mechanical strength test shows that the annealing temperature can affect the tensile strength of CS/PEO composite fiber mat. The cross-linked CS/PEO composite fibers provide a useful platform for the immobilization of palladium catalyst to catalyze the Mizoroki-Heck reactions of aromatic halides with olefins. Moreover, these CS/PEO composite fibers could be post modified with special ligands to chelate palladium species efficiently to further improve the catalytic activity and stability.     

Nonstructural carbohydrates in leaves subtending cotton bolls,fibers and embryos in response to nitrogen stress

A field study was conducted in 2013 and 2014 where cotton was exposed to three N regimes: (1) the control without N application (low N); (2) 260 kg N ha^?1 (medium N); (3) 520 kg N ha^?1 (high N). Boll size, lint mass per boll, seed mass per boll, fiber length and strength were significantly decreased under N deprivation in the two years. The increased carbohydrate levels of LSCB (leaf subtending the cotton boll) led to decreased carbohydrate levels of fibers in the low N relative to the other N treatments. The low N embryos exhibited lower starch concentrations at 17 and 31 DPA (days post anthesis), and TNC (total nonstructural carbohydrate) concentrations at 17, 31, 45 and 52 DPA compared to medium N embryos. Starch levels in LSCB had negative associations with those in fibers at 17, 31 and 45 DPA, but positive associations with those in embryos at 24 and 45 DPA. Fibers expressed negative associations with embryos in glucose level at 24 and 38 DPA, and in TNC levels at 17 and 45 DPA. The study suggests that carbon assimilate levels in fibers and embryos could explain the difference in boll yield components and fiber quality.     

Effects of IBA on the rooting of branch cuttings of Chinese jujube (<Emphasis Type="Italic">Zizyphus jujuba</Emphasis> Mill.) and changes to nutrients and endogenous hormones

‘Zhongqiusucui’ jujube secondary shoots were treated with 3-indolebutyric acid (IBA) at three concentrations, 500, 1000 and 1500 mg/L. Results show that IBA could significantly enhance rooting and root characteristics of cuttings and were best with IBA at 1500 mg/L. In the rooting process, the formation of adventitious roots was related to the consumption and accumulation of nutrients (soluble sugars and proteins) and the changes in endogenous hormones in phloem, leaf tips and leaf bases. The rooting of cuttings had a positive correlation with the consumption of soluble sugars during the period of callus formation and with the accumulation of soluble sugars during adventitious root formation and growth. Rooting was positively related to the breakdown of soluble proteins in the phloem when the callus formed, and had a positive correlation with its accumulation during adventitious root formation and growth. Leaf tips and leaf bases showed a reverse trend in changes of soluble protein. However, together with the phloem, leaf tips and leaf bases regulated and controlled the formation and development of adventitious roots. The main activities of soluble proteins exist in the leaf tips as this was the main source of soluble proteins. The relation between rooting and IAA (indole-3-acetic acid) content in phloem was positive and thus a high concentration of IAA could benefit the induction and formation of adventitious roots. However, rooting was negatively related with ABA (abscisic acid) and GA (gibberellic acid) and a high concentration of both could inhibit the induction and formation of adventitious roots. Rooting had a positive correlation with phloem IAA/ABA ratios, and higher ratios could improve rooting. Low concentrations of ZR (zeatin riboside) triggered the induction of adventitious roots, while higher concentrations promoted root growth. Endogenous hormones in leaf tips and bases had an impact on rooting. The activities of endogenous hormones mainly existed in leaf tips because they play a major role in the production and consumption of IAA and its ABA content increased during rooting. The ZR in leaf tips influenced the rooting of cuttings, especially in the callus formation and rooting stage. Leaf tips were the main source of GA.