饲料搅拌机的研制

本文从提高中、小型养殖场的效益，节省人工出发，改良其混合工序，利用工程设计原理研制了饲料搅拌机，在确定总计设计思路和工作原理后，进行了总装设计和关键部件的设计，最后通过试验验证了研发出的饲料搅拌机的适用性：在搅拌时间为100秒时，混合料均匀度变异系数CV（经专业鉴定机构检测）为7%。本次饲料搅拌机的成功研制可提高中、小型养殖场经济效益，对促进农业现代化发展有显著功效。     

Zn~(2+)胁迫对4种紫花苜蓿光合色素的影响

以紫花苜蓿品种敖汉苜蓿、金皇后、隆西和三得利为材料,采用土培方法,研究Zn2+胁迫对4种紫花苜蓿叶片绝对生长率和相对生长量及光合色素的影响。结果表明,当900μmol/L Zn2+胁迫23d时,4种紫花苜蓿相比较,敖汉苜蓿叶片叶绿素a、叶绿素b、叶绿素总量、类胡卜素含量、绝对生长率和相对生长量均比对照增加,而其他3个紫花苜蓿品种分别比对照有不同程度的下降。综合表明,敖汉苜蓿具有较强的抗Zn2+能力。     

暗排技术对设施连作土壤改良及切花菊品质的影响

针对温室、大棚等设施栽培条件下的土壤随着连作年限的增加,土壤理化性状变劣、养分比例失调、土壤次生盐渍化加重、生产性能降低这一现象,采用暗管排水排盐技术,在稻草还田(800 kg/hm²)配套措施条件下,研究了暗管不同埋管间距(2、4、6m)对设施连作表层土(0～15 cm)有机质、速效养分(碱解氮、有效磷和速效钾)、盐分含量以及切花菊‘神马’品质的影响。结果表明:暗排技术能明显增强切花菊的根系活力,对切花菊主要品质(株高、茎粗、花径、舌状花数及生物量)的提高具有积极作用,其中4 m的埋管间距处理效果最佳;对土壤有机质和速效养分含量的提高效果埋管间距4 m处理显著高于埋管间距2 m和6 m处理;暗排技术对于土壤的降渍排盐作用明显,可显著降低表层土壤的含水量、电导率、全盐量以及主要盐分离子含量(Ca²⁺和SO₄^2–),并且随着埋管间距的减小,降渍排盐的效果越明显。综合比较分析各相关试验结果,结合暗管埋设初期成本投入的考虑,4 m的埋管间距处理能最有效地改良设施连作土壤及提高切花菊的品质。     

杭州城市边缘区暴露度评价

暴露度理论是分析人地相互作用过程的桥梁。本文以快速城市化带来的影响作为主要干扰因素,选取杭州城市边缘区所辖街道为基本单位,以距市中心距离、斑块密度、香农多样性指数、景观分割度指数、建设用地比重、最大斑块指数6方面指标构建暴露度评价指标体系,并结合熵值法对杭州市城市边缘区暴露程度的空间分异特征及其影响因素进行了研究。结果表明：（1）杭州市城市边缘区暴露度总体分布规律并非是从城东向城西逐渐递减,而是呈现出高、中、低3个等级相间排列的现象;（2）结合当前杭州市社会经济数据,发现空间分异状况、城市系统体制转换阶段差异对杭州市边缘区的暴露程度均有一定的影响。     

Associations between green space,air pollution and birthweight in Sydney Metropolitan Area,Australia

Growing number of evidence have reported that exposure to air pollution was associated with unfavourable birth outcomes while increased exposure to green spaces was associated with better birth outcomes. However, the effect of interactions between air pollution and green spaces on pregnancy outcomes remain unclear. Using the data on all the live births recorded in Sydney between 2016 January and 2017 December, we built up multilevel linear and logistic regression models with random intercepts for statistical area level 2 (SA2) to examine the association between residential levels of air pollution (NO2, PM2.5, SO2 and O3) and pregnancy outcomes including birthweight, low birthweight, and preterm birth. This was followed by assessment of potential effect modification by green space quantity by fitting 2-way interaction term between each air pollutants and green space quantity separately. Furthermore, building on the 2-way interaction term, we explored 3-way interactions by adding area level socio-economic status and population density. Higher levels of PM2.5, NO2 and SO2 were statistically significantly associated with decrease in birthweights (p < 0.05) in the adjusted models. We observed statistically significantly association between the lower risks of preterm birth and higher levels of NO2 in the adjusted models (p < 0.05). However, none of the other air pollutants were statistically significantly associated with the odds of low birthweight and preterm birth. In the adjusted models, green space quantity was statistically significantly associated with reduced odds of preterm birth (p < 0.05). The results for birthweights were in the same direction (p < 0.05) however, some of these associations did not remain statistically significant after adjusting the models for air pollution. In general, no associations were found for low birthweight. Statistically significant 2-way interactions between green space quantity and NO2, PM2.5 and SO2 levels indicated that association between moderate levels of NO2, PM2.5 and birthweight weakened in the greener areas (>20 %) especially in the affluent and densely populated areas while the effect of SO2 did not differ consistently across green space levels with benefit of exposure to the greenest areas (>40 %) was evident, yet not statistically significant. Our findings suggest that increasing green spaces in cities may help supporting a healthy start in life by decreasing harms of moderate levels of air pollution. Replication in different contexts and consideration of potentially contrasting results with different types of green space is warranted.