薄膜承载力及其对日光温室结构稳定性能的影响

为研究薄膜对日光温室结构抗灾害垮塌性能的影响,采用 ANSYS 有限元分析软件,模拟了单片薄膜受风雪、冰雹荷载作用情景,分析了薄膜厚度、尺寸（长度×宽度）、预张力和外荷载对单膜承载力的影响,建立了日光温室结构单榀拱架、无膜空间整体骨架、覆膜空间整体骨架3种计算模型,得到了风雪灾害下日光温室结构破坏全过程以及覆膜日光温室结构空间系数,探讨了薄膜厚度、弹性模量、预张力等参数改变时,薄膜张拉刚化效应对日光温室结构稳定性能的影响。结果表明：薄膜尺寸（长度×宽度）和厚度是影响其承载性能的主要因素,同时应适当考虑薄膜长宽比影响;0.2 mm厚的薄膜可满足特强冰雹的防灾要求;薄膜张拉刚化效应有助于提高日光温室结构抗风承载力,对抗雪承载力影响不大;各分析参数中,薄膜弹性模量对日光温室结构空间系数的影响不明显。研究结果为覆膜日光温室结构抗风雪、抗冰雹灾害设计提供参考。     

Wood ash effects on chemical and microbiological properties of digestate- and manure-amended soils

A field study was carried out to evaluate the potential of wood ash as a fertilizer in grassland systems in combination with enriched N organic wastes. Six treatments including manure or digestate, each combined with wood ash at 0, 1, and 3 t?ha^?1 were spread onto the soil to an amount equivalent to 120 kg?N ha^?1. Three soil samplings and one cutting was carried out within one growing season (3 months). A higher pH value was found in manure-treated plots, the pH rise being proportional to the amount of wood ash added. Those plots amended with digestate were characterized by a larger content of total C, NH₄ ⁺, and total P (TP) regardless of the amount of ashes. Microbial activity, assessed by basal respiration and microbial biomass carbon of the differently treated soils, was not affected neither by the nature of the organic waste nor by the amount of wood ash added. However, amending soil with digestate resulted in a more efficient soil microbial community, as shown by the lower values of the metabolic quotient. Such effects were accompanied by a higher percentage of plant cover, particularly of leguminous plants in digestate-treated plots. The time of sampling (seasonal effects) was found to influence the soil pH and electrical conductivity (EC), as well as the nutrient content (total N, NH₄ ⁺, and NO₃ ^?). Overall, the combined use of wood ash and biogas digestate can constitute an efficient way for the disposal and recycling of both products and additionally, it may constitute an environmentally friendly alternative to mineral fertilizers for acid soils.     

Nodule numbers,colonization rates,and carbon accumulations of white clover response of nitrogen and phosphorus starvation in the dual symbionts of rhizobial and arbuscular mycorrhizal fungi

Leguminous plants can be dual colonized by rhizobia (Rh) and arbuscular mycorrhizal fungi (AMF). To test the affections of nodulation, colonization of AMF (AMF%) and the growth responses of white clover under crossed low nitrogen (N) and phosphorus (P) fertilization levels. The results showed that the nodule numbers were much more dense, significantly increased by AMF symbiosis, negatively controlled by the N levels but had no effect due to P levels. The influence of nodule numbers via AMF % was beyond P availability. The AMF% was related and favored with the better N and P nutrition, which may have better photosynthetic carbon (C) availability. The plant growth and C accumulation were significantly increased via rhizobium inoculation but were negatively affected by the AMF. The AMF colonization beyond P fertilization had strong effects on nodulation. Compared with rhizobium symbiosis, the AMF colonization requires a more C-composition between these two tertiary symbioses.     

Molecular cloning and expression of salmon pituitary hormones

A cDNA library was prepared from chinook salmon pituitaries. Growth hormone (GH), prolactin (PRL) and the β subunit of gonadotropin (GTH) genes were screened using synthetic oligonucleotides as probes. Full size cDNA clones coding for these polypeptide hormones were isolated and characterized. The cDNA sequences for PRL and βGTH have been reported earlier from our laboratories. The cDNA clone for GH contains 1148 bp and codes for a preGH of 210 amino acids. The chinook salmon GH, reported in the present investigation, differs from chum salmon GH in only 1 amino acid, and from coho salmon GH in 5 amino acids. Plasmids containing modified nucleotide sequences coding for GH, PRL and βGTH were constructed individually into an expression vector using the heat-inducible λ pL promotor. Mature PRL, GH and unglycosylated βGTH were expressed in the bacteria at elevated temperature.     

Cloning and characterization of two types of growth hormone receptors in tomato clownfish (Amphiprion frenatus), and their expression under different light spectra and photoperiods

Light is regarded as an important environmental factor which is involved in the regulation of the various physiological processes of fish. Thereinto, the light spectra and photoperiods have been shown the noticeable influences on the growth performance of fish species. In the present study, two types of growth hormone receptors (Afghr1 and Afghr2) were cloned from tomato clownfish (Amphiprion frenatus) using RACE PCR, and the effects of different photoperiods and light spectra on the growth performance as well as the growth-related gene expression of A. frenatus were investigated. The full-length cDNA sequences of Afghr1 and Afghr2 were 2609 and 2673 bp in length, encoding the proteins of 630 and 571 amino acids, respectively. Both receptors were widely expressed in all the tested tissues, and the highest expression was observed in the liver and pituitary, respectively. Furthermore, the experimental clownfish under constant-light photoperiod (24L:0D) exhibited the significantly higher related somatic growth rate and expression levels of Afghr1, Afghr2, gh, and igf-I as well as the lower feed conversion ratio and plasma melatonin level, compared with other photoperiods (16L:8D, 8L:16D, and 2L:22D). Additionally, red light appeared to markedly improve the growth parameters and the expression of growth-related genes comparing with blue, green, and white lights. In summary, the result of the current study highlights the regulatory effects of light spectra and photoperiods on the growth performance of a coral-reef fish, A. frenatus. The constant-light photoperiod (24L:0D) and red light have been shown the best promotion for the growth of A. frenatus and should be considered as the optimal light conditions for its culture.

     

鳌山湾水动力状况研究

通过对鳌山湾海域的潮流数值模拟，较为详细地阐述了鳌山湾的潮汐、潮流征及海水交换率与交换期。结果表明，与其他海湾相比，鳌山湾水交换能力一般。     

光合细菌在池塘蚌鱼混养中的应用

蚌鱼混养是将河蚌育珠和池塘养鱼有机结合起来的一种生态淡水养殖模式。我们于2000年～2001年在诸暨市王家井水产珍珠养殖场进行了光合细菌(PSB)在池塘蚌鱼混养中的应用试验,取得了较大的经济效益,生态效益和社会效益。 一、养殖条件 蚌鱼混养池塘为标准长方形土池,池塘9个,共计面积200亩。池塘水深2.0m左     

广西西江流域水源涵养服务空间格局及其影响因素

  目的  水源涵养在众多生态系统服务中占据着重要的地位。揭示水源涵养服务空间格局及其影响因素,识别水源涵养服务重要区,对流域水资源利用、分区管理与综合保护具有重要意义。  方法  以广西西江流域为研究对象,基于InVEST模型、GeoDa与ArcGIS等工具,使用全域和局域空间自相关检验研究区水源涵养服务空间分布模式,构建空间误差模型辨识水源涵养服务关键影响因素,采用分位数分类法进行水源涵养服务重要性分级。  结果  广西西江流域多年平均水源涵养量为185.36 mm,2015年总量为376.10亿 m3。全域莫兰指数为0.769,表明研究区水源涵养服务在空间分布上具有空间依赖性。考虑到多重共线性的影响,最终从13项影响因素中筛选出7项进入空间误差模型,得出土壤饱和导水率、多年平均降水量、坡度、植被净初级生产力、经济密度对水源涵养服务产生显著正面影响,而人口密度和不透水率对水源涵养服务产生显著负面影响。识别出黔浔江流域及左郁江流域南部区域是水源涵养服务重要区,在相关政策制定与管理决策中需重点和优先考虑。  结论  广西西江流域水源涵养服务在空间分布上呈现集聚分布,并以低-低聚集和高-高聚集类型为主。土壤饱和导水率、多年平均降水量、坡度以及不透水率是水源涵养服务最主要的影响因素。图5表2参28     

不同施肥条件下模拟酸雨对 小白菜生长品质的影响

通过大棚试验,研究在不同酸度模拟酸雨胁迫下,施加无机肥和有机肥对小白菜生长周期叶绿素含量、全氮、全磷、全钾积累量的影响。结果表明,酸雨对小白菜的生长有抑制作用,强酸性酸雨(p H≤3.5)抑制效果更显著,各指标含量在处理后21~28 d积累速率最大,且在成熟期无机肥组大于有机肥组。与CK相比,p H2.5、3.5、4.5、5.6处理的小白菜各指标在收获期损失率表现为,叶绿素含量:无机肥组分别损失27.99%、15.29%、7.94%、1.09%;有机肥组分别损失25.39%、7.43%、0.18%、-2.45%;全氮积累量:无机肥组分别损失47.28%、37.04%、23.58%、8.65%;有机肥组分别损失37.89%、34.93%、23.58%、8.65%;全磷积累量:无机肥组分别损失49.15%、25.84%、-3.54%、-1.69%;有机肥组分别损失46.69%、45.11%、22.15%、14.53%;全钾积累量:无机肥组分别损失55.42%、35.39%、8.26%、6.52%;有机肥组分别损失36.43%、22.62%、9.57%、6.85%。有机肥能减缓酸雨作用下小白菜叶绿素含量的损失;减缓强酸性酸雨作用下氮磷钾积累量的损失,而无机肥能减缓弱酸性酸雨作用下氮磷钾积累量损失。因此,可根据蔬菜种植地区的酸雨酸度情况,选择合适的施肥条件。     

石灰性土壤大蒜田硫酸钙肥的应用效果

为了研究在石灰性土壤大蒜田中施用钙肥的效果,以硫酸钙为试材,设置5个处理:0(CK)、75、150、225、300 kg/hm2,测定大蒜生育时期、蒜头产量、单个蒜头质量。结果表明:不同用量的硫酸钙肥可使大蒜的幼苗期、鳞芽分化期、花茎伸长期、鳞茎肥大期提前0~2 d,成熟期延迟0~3 d;随施肥量增加抗病虫害性能呈感染→较轻→较抗的变化趋势;单蒜头质量增加,4个处理分别比对照增加8.74%、13.29%、18.91%、25.30%,差异均达极显著水平;产量提高,4个处理分别比对照提高8.73%、13.27%、18.90%、25.29%,差异均达极显著水平。