Atmospheric deposition of inorganic nitrogen in a semi-arid grassland of Inner Mongolia,China

Due to increasing global demand for crop production and energy use, more and more reactive nitrogen(Nr) has been generated and emitted to the environment. As a result, global atmospheric nitrogen(N) deposition has tripled since the industrial revolution and the ecological environment and human health have been harmed. In this study, we measured dry and wet/bulk N deposition from July 2013 to December 2015 in a semi-arid grassland of Duolun County, Inner Mongolia, China. The samples of dry and wet/bulk N deposition were collected monthly with a DELTA(DEnuder for Long Term Atmospheric sampling) system and with Gradko passive samplers and a precipitation gauge. The measured results show that the annual mean concentrations of NH_3, NO_2, HNO_3, particulate NH_4~+(pNH_4~+) and particulate NO_3~-(pNO_3~-) in atmosphere were 2.33, 1.90, 0.18, 1.42 and 0.42 μg N/m3, respectively, and that the annual mean volume-weighted concentrations of NH_4~+-N and NO_3~--N in precipitation were 2.71 and 1.99 mg N/L, respectively. The concentrations of Nr components(including NH_3, NO_2, HNO_3, p NH_4~+, pNO_3~-, NH_4~+-N and NO_3~--N) exhibited different seasonal variations. Specifically, NO_2 and HNO_3 exhibited higher concentrations in autumn than in summer, while the other Nr components(NH_3, pNH_4~+, pNO_3~-, NH_4~+-N and NO_3~--N) showed the highest values in summer. Based on measured concentrations of Nr components and their deposition velocities estimated using the GEOS-Chem global atmospheric chemical transport model, the calculated annual mean dry deposition fluxes were 3.17, 1.13, 0.63, 0.91 and 0.36 kg N/(hm~2·a) for NH_3, NO_2, HNO_3, p NH_4~+ and pNO_3~-, respectively, and the calculated annual mean wet/bulk deposition fluxes were 5.37 and 3.15 kg N/(hm~2·a) for NH_4~+-N and NO_3~--N, respectively. The estimated annual N deposition(including dry N deposition and wet/bulk N deposition) reached 14.7 kg N/(hm~2·a) in grassland of Duolun County, approaching to the upper limit of the N critical load(10–15 kg N/(hm~2·a)). Dry and wet/bulk deposition fluxes of all Nr components(with an exception of HNO_3) showed similar seasonal variations with the maximum deposition flux in summer and the minimum in winter. Reduced Nr components(e.g., gaseous NH_3 and p NH_4~+ in atmosphere and NH_4~+-N in precipitation) dominated the total N deposition at the sampling site(accounted for 64% of the total N deposition), suggesting that the deposited atmospheric Nr mainly originated from agricultural activities. Considering the projected future increases in crop and livestock production in Inner Mongolia, the ecological and human risks to the negative effects of increased N deposition could be increased if no mitigation measures are taken.     

车用空调直流无刷风机的减振研究

对车用空调直流无刷风机样机进行整机的振动测试和频谱分析,确定了影响风机振动的2个主要因素,即风机转子质量不平衡和无刷直流电机的换相脉动、齿槽脉动;分析了其影响规律,提出了相应的减振措施,并给出改进后的测试结果.     

Influence of Water and Glycerol Contents on the aw of Fish Pastes

Abstract

The influence of fish water content on the characteristics of water activity (a_w) of reduced paste was studied. Two fish species were used: a fat species, mackerel (Scomber japonicus marplatensis), and a lean species, Brazilian sandperch (Pseudopercis semifasciata). Glycerol (from 15 to 50%) was used to decrease a_w of the cooked fish paste.(54.12% and 77.89%) in mackerel, two relationships of a_w versus percent added glycerol were obtained, and for Brazilian sandperch one relationship was obtained.     

四倍体小麦矮杆基因对胚芽鞘生长的影响

胚芽鞘长度决定了籽粒的最大播种深度,是影响小麦产量的一重要因素.本研究测定了矮杆番麦,硬粒小麦Langdon,以及以矮杆番麦为母本,Langdon为父本通过一粒传法得到的重组自交系群体(RILs)的胚芽鞘长度和胚芽鞘表皮细胞的长度,并对矮杆番麦胚芽鞘的组织结构进行了观察.结果表明,矮杆植株具有短的胚芽鞘,高杆植株具有长胚芽鞘,且胚芽鞘的长度是由于表皮细胞的长度所决定.因此推断矮杆番麦的短胚芽鞘是矮化基因的多效性.     

云南普洱茶特征成分的功能与毒理学评价

研究了普洱茶特征成分茶褐素、茶多糖与蛋白质等的复合体对昆明种小白鼠的抗疲劳、降胆固醇以及毒理学效应。实验结果显示：普洱茶特征成分提取物能显著提高小白鼠的抗疲劳作用和降低小鼠血液中的胆固醇含量,且优于普洱茶水提物。普洱茶特征成分提取物经口LD₅₀>10βg/kg,属实际无毒级物质。Ames实验中加S₉混合液和不加S₉混合液的各剂量组回变菌落数与阴性对照差别无统计学意义,且无剂量反应关系。小鼠骨髓嗜多染红细胞微核试验与阴性对照组比较差别无统计学意义。普洱茶特征成分提取物在500~5β000βμg/ml浓度范围内未见诱发CHL细胞染色体畸变率增高。这说明,在实验条件下,普洱茶特征成分提取物属实际无毒级,也未见有致突变作用。     

水肥耦合对紫色土中小麦肥料减施效应的影响

为了认识水肥耦合对紫色土中小麦的影响特征及肥料减施效应,在四川盐亭县青峰村和四川盐亭农田生态系统国家野外科学观测研究站的石灰性紫色土上,于2018年10月至2020年5月,用小区和盆栽试验等方法,观测不同水肥耦合处理对小麦和土壤主要属性的影响。结果表明,水肥耦合对小麦生长和籽粒产量有明显的促进效应,浇水到田间持水量的80%左右时,其促进效应最大;肥料用量减少10%~20%,不会造成小麦的明显减产;水肥耦合主要提高了土壤养分有效性和土壤酶的活性,因而有明显的促进效应。水肥耦合是紫色土区减肥增效的一种有效措施,从而能有效防治区域的面源污染。     

基于单形重心设计优化柑橘皮渣馅料配方

为开发利用柑橘皮渣，提高柑橘整果资源的利用，以柑橘皮渣为主要原料，利用麦芽糖醇、椰子蜜、罗汉果甜苷作为蔗糖替代品，以中链甘油三酯、聚葡萄糖为脂肪替代品制作柑橘皮渣馅料，以质构参数及感官评价为综合指标，通过单因素试验对蔗糖及油脂替代物进行筛选，并在此基础上利用单形重心设计试验进行配方优化，最终获得柑橘皮渣馅料的最优配方为：以馅料总质量为100%计，柑橘皮浆79.20%、麦芽糖醇7.50%、椰子蜜8.70%、罗汉果甜苷0.10%、花生油0.13%、中链甘油三酯2.26%、聚葡萄糖0.81%、玉米淀粉1.30%。在此条件下，制得的柑橘皮渣馅料色泽澄黄，细腻软糯，清新爽甜，总糖含量降低了57.63%、油脂含量降低了52.54%，总膳食纤维含量增加了20.79%，属于减糖、低脂、高膳食纤维的新型健康馅料。     

太阳辐射减弱对浮游与底栖藻类竞争的影响

为了解辐射减弱对浮游藻类和底栖藻类竞争的影响，构建了浅水生态系统，设置遮光组和不遮光的对照组两种处理，通过测定水中氮、磷营养盐、浮游藻类生物量及底栖藻类生物量等指标，分析遮光时浮游藻类和底栖藻类生长变化，研究辐射减弱对浮游与底栖藻类竞争的影响。结果表明，遮光条件下，水体浮游藻类Chl a降低15%，DO浓度平均增加9%，TN、TP浓度分别增加30%和24%时，底栖藻类Chl a增加48%。说明辐射减弱虽可显著降低水体光照强度和浮游藻类生物量，但可提高水体中氮、磷营养盐浓度，促进底栖藻类生物量增加。因此，在辐射减弱背景下，不利于浮游藻类生长，而有利于底栖藻类竞争。     

减量施肥条件下甜玉米产量效应与农田氮、磷流失特征

从农田面源污染产生的源头入手,研究减量施肥条件下甜玉米的产量效应和氮、磷流失特征,寻求防控甜玉米农田氮、磷流失的减肥增效措施。通过田间试验,设置（1）不施肥(CK);（2）常规施肥(CF);（3）配方肥(FF);（4）配方肥+有机肥(OFFF);（5）配方肥+生物炭(BFF);（6）配方肥+控释尿素(CRUFF);（7）尿素+控释BB肥(UCRF)。结果表明：在氮肥用量减少20%条件下,处理CF与FF、BFF、CRUFF之间并无显著差异,而与处理OFFF、UCRF间达到显著差异(P<0.05),OFFF、UCRF分别较CF增产达17.8%、16.8%。甜玉米生育期地表径流总氮浓度和流失量呈逐步下降趋势,CF氮素流失总量最大,达到3.54 kg/hm²;减量施肥条件下农田氮素流失总量显著降低,降幅为18.4%~45.5%,其中以CRUFF最为显著,其次为UCRF、OFFF和BFF;减量施肥条件下,OFFF、FF、UCRF处理总磷流失量显著降低(P<0.05),降幅为46.7%~60.0%,其中以OFFF最为显著。浅层地下水氮磷浓度能一定程度反映农田氮磷渗漏情况。甜玉米生育期CF处理浅层地下水氮磷浓度最高,分别达到45.85 mg/L和4.10 mg/L,而CRUFF生育期总氮浓度最高为22.79 mg/L,较CF降低50.3%,CRUFF生育期总磷浓度最高为2.73 mg/L,较CF降低33.4%。浅层地下水中氮素是以铵态氮为主要存在形态。与传统施肥比较,以减氮20%为目标的配方肥(21.2-6.36-18.42)及其分别与控释尿素、控释BB肥、有机肥配施不仅可以获得高产,而且能有效防控农田氮磷流失,减少面源污染风险。     

Extending Finlay–Wilkinson regression with environmental covariates

Finlay–Wilkinson regression is a popular method for analysing genotype–environment interaction in series of plant breeding and variety trials. It involves a regression on the environmental mean, indexing the productivity of an environment, which is driven by a wide array of environmental factors. Increasingly, it is becoming feasible to characterize environments explicitly using observable environmental covariates. Hence, there is mounting interest to replace the environmental index with an explicit regression on such observable environmental covariates. This paper reviews the development of such methods. The focus is on parsimonious models that allow replacing the environmental index by regression on synthetic environmental covariates formed as linear combinations of a larger number of observable environmental covariates. Two new methods are proposed for obtaining such synthetic covariates, which may be integrated into genotype-specific regression models, that is, criss-cross regression and a factor-analytic approach. The main advantage of such explicit modelling is that predictions can be made also for new environments where trials have not been conducted. A published dataset is employed to illustrate the proposed methods.