黄磷燃烧特性实验研究与理论分析

基于黄磷燃烧特性实验,对黄磷燃烧的动力学现象进行了实验研究和理论分析。通过观察不同燃烧表面积的黄磷燃烧动力学现象,获得了黄磷的燃烧特性参数,并利用池火模型对黄磷燃烧实验进行了理论分析。研究结果表明：固定表面积的黄磷燃烧时,黄磷的质量损失速率可近似视为某一恒定值,黄磷的质量损失速率与燃烧表面积有关。黄磷燃烧实验火焰最高温度约为1000℃,火焰高度与燃烧表面积有关。池火模型可以对黄磷的燃烧特性参数进行预测和分析,池火模型所预测的火焰高度与实验数据基本相吻合,相对误差小于7％。     

室外风作用下竖井结构内火灾烟气运动规律研究

室外风是影响高层（超高层）建筑火灾蔓延的主要因素。通过数值模拟六个不同火灾场景温度场、能见度及CO浓度场变化过程,定量总结了不同风向、风速条件下侧向全开竖井结构内烟气运动规律。模拟结果发现,迎面风作用下,竖井内会产生较高滞止压力,中性面位置上升,上部烟气加速向竖井下部蔓延,下部烟气通过开口排出;背面风作用下,中性面位置...     

巢湖流域SRTM高程误差的空间分异研究

数字高程模型是进行地学研究的重要基础数据,SRTM、DEM是公众可以免费获取的精度达90m的DEM数据.以我国1:5万DEM为参考数据,以巢湖流域为研究区,利用高程中误差模型和单位面积土地填挖方对SRTM、DEM进行高程精度研究,并分析了高程误差的空间分异规律.结果表明,SRTM、DEM的高程中误差和单位面积土地填挖方随着地貌类型的变化呈现明显的空间分异性,这主要由于SRTM像元精度不高所致.在研究区内的33块样区中,绝大部分都是在二级精度评价标准之内,可见SRTM、DEM整体精度较高.     

荷木树干CO2释放通量的个体间差异及树干液流的效应

为研究荷木(Schima superba)个体间树干CO2释放通量(Es)的差异以及树干液流对Es的影响,提高森林生态系统呼吸计算准确性,利用红外气体分析仪及自制式气室于2009年湿季和干季监测了华南荷木人工林5棵样树的Es,并同步监测了树干温度(θs)、气温及液流密度.结果显示:θs与气温之间呈显著线形正相关;Es与树干温度之间存在显著指数函数关系;Es干湿季的差异显著,并呈现明显的季节变化;5株样树之间Es存在显著差异,平均Es分别为3.12、3.60、5.52、6.98、8.09μmol m-2 s-1;同时,样树之间树干CO2释放通量的温度系数(Q10)差异显著(1.97～4.24之间).Tree1、Tree2和Tree4白天的Es与液流速度(v)显著正相关,白天的标准化树干CO2释放通量(R25,温度为25℃时的Es)高于晚上.荷木Es个体之间及时间上的差异主要受树干温度、生长状况和液流速度的影响.图3表6参35     

GRAZED STUBBLE HEIGHT AS A CRITERION FOR CONTROLLING SEDIMENT PRODUCTION FROM GRAZING LANDS1

ABSTRACT: Efforts by state and federal agencies to develop standards and guidelines for protecting and enhancing water quality on grazing lands have led to suggestions that grazed stubble height criteria could be used to determine when cattle should be removed from a specific pasture or grazing area. Until recently only indirect scientific evidence from agronomy and laboratory studies gave support to the stubble height concept. Consequently, a grazing study was initiated on a Montana ranch in 1997 to determine the reduction in overland sediment achieved by grazing a pasture to a predetermined stubble height. Treatments consisted of 7 cm (3 in) grazed, 7 cm (3 in) clipped or mowed, 15 cm (6 in) grazed; 15 cm (6 in) clipped and untreated or natural forage plant height. The five treatments were used in a two‐year trial spanning 1997 to 1999. At the conclusion of this study the magnitude of sediment production was related to the number of intense rain events during the March through June period rather than total precipitation. There was a significant year effect in terms of sediment accumulation (P < 0.01) but no year by treatment effect (P = 0.11). Even though a significant difference in sediment accumulation was detected between the shorter and taller stubble heights (P = 0.04) in both 1998 and 1999, the difference could not be explained by grazed stubble height alone. Close grazing (7 cm stubble) consistently ranked lowest in sediment production (P < 0.01) among all treatments, including the ungrazed control. These results suggest that changes in plant community structure and microtopographic caused by grazing influence sediment entrapment (retention) on hillslopes more than those caused by plant height.     

苹果茎沟病毒对梨树幼苗生长及过氧化物酶活性的影响

Based on growth level and peroxidase activity, a comparative study and paried-samples t test were made between vires-free Zaosu pear seedlings and the seedlings inoculated with apple stem grooving virus(ASGV). The results showed : ( 1 )virus-free Zaosu pear seedlings grew better than inoculated ones. Of the seedlings the height, diameter, branches and autumn braches differed statistically significantly; (2)the peroxidase activity of inoculated seedlings was higher than that of virus-free ones, and the peak of peroxidase activity occurred on about d 7 and d 24 after inoculation. Fig 1, Tab 1, Ref 9     

Fetal and maternal progenitor cells in co-culture respond equally to erythropoietin

To explore potentially selective growth conditions for fetal cells in cultures from the blood of pregnant women, we investigated if fetal and adult erythroid progenitors with different hemoglobin expression programs are differentially responsive to erythropoietin (EPO). Co-cultures of clonogenic cells from 12-week fetal and adult peripheral blood were established, and the development of erythropoietic cells was monitored using flow cytometric profiles of correlated cellular contents of fetal and adult hemoglobin (HbF and HbA, respectively). Adult nucleated red cells were classified as F+A−, F+A+ or F−A+. All fetal cells were F+A−. The population of F+A− cells was flow-sorted and fetal cells were identified by fluorescence in situ hybridization (FISH) using chromosome-specific probes. Delayed EPO addition revealed that all types of erythroid cells entered the EPO-dependent phase with similar kinetics, beginning at about Day 4. The data suggest that fetal and adult erythroid stem/progenitor cells have the same initial maturation kinetics in culture independent of their hemoglobin chain expression program. Fetal and adult cells with different hemoglobin profiles also showed similar EPO dose–response curves, determined for different intervals during the first 2 weeks of culture. Thus, the kinetics of entry into the phase of EPO dependence, as well as the sensitivity to EPO at various stages of development, are essentially the same for erythropoietic progenitor cells derived from adult and early fetal blood, which rules out the possibility of using the timing or concentration of EPO for the selective growth of fetal cells from the blood of pregnant women. Copyright © 2001 John Wiley & Sons, Ltd.     

苏北海域表层沉积物中PH_3的分布

为研究海洋生态系统中PH3的迁移转化规律及其产生机制,2006年12月对苏北海域表层沉积物中磷化氢(PH3)、总磷(TP)、无机磷(IP)、有机磷(OP)及有机质(OM)的分布进行了系统分析和讨论。结果表明,PH3在苏北海域表层沉积物中普遍存在,含量在[(2.63±0.38)~(39.35±5.49)]×10-12之间,最大值出现在长江口,最小值出现在辐射沙洲海域。辐射沙洲海域TP和IP的含量较低,长江口及吕四一带含量相对较高,且沿着长江入海方向逐渐减少。OP和OM分布的总体趋势是由南至北,由西到东含量逐渐减小,长江口及吕四港一带含量较高。区与区间PH3与TP、IP及OP的相关性分析表明,IP作为PH3的生成前体物可能性比OP高。     

外加可溶性碳、氮对不同热量带土壤氨挥发的影响

在室内条件下采用静态吸收法,研究了外加可溶性碳、氮对不同热量带经长期施肥的3种农田土壤:黑土、潮褐土和红壤氨挥发的影响.结果表明,施用氮肥显著促进了土壤氨挥发,在单施氮肥和可溶性碳配施氮条件下,不同热量带土壤氨挥发量从高到低分别为潮褐土(14.3、 7.37 mg·kg~(-1)),黑土(1.52、 1.11 mg·kg~(-1)),红壤(0.998、 0.402 mg·kg~(-1)).添加可溶性碳显著减少土壤因施氮肥产生的氨挥发量,其中黑土减少27.0%,潮褐土减少48.5%,红壤减少60.0%.在黑土、潮褐土长期不同施肥土壤中,单施氮肥后氨挥发量均表现为无肥土壤 > 化肥土壤 > 化肥+有机肥土壤,与可溶性碳配施氮后氨挥发量变化规律相反;在红壤长期不同施肥土壤中,单施氮肥和可溶性碳配施氮后氨挥发量均表现为无肥土壤 > 化肥土壤 > 化肥+有机肥土壤.研究结果还表明,外加可溶性碳、氮后,潮褐土铵态氮含量的减少幅度和硝态氮含量的增加幅度均显著高于黑土和红壤,说明潮褐土中氮素损失潜能大.     

Enhanced adaptability of Sesbania rostrata to Pb/Zn tailings via stem nodulation

Sesbania rostrata is wellknown for its stem nodulation, but the roles of stem nodulation in root nodulation and adaptation of S. rostrata to Pb/Zn-enriched tailings environment has been poorly understood. We investigated the e ects of inoculating (with stem nodule treatment) and non-inoculating (without stem nodule treatment) Azorhizobium caulinodans on the growth, root nodulation, and N fixation of S. rostrata grown on three di erent types of soil substrata: Pb/Zn tailings, garden soil amended tailings, and garden soil. The results showed that plant height, stem basal diameter, biomass, chlorophyll content, nitrogen content and N-accumulation per plant were 2.3%–4.9%, 2.2%–7.7%, 27.8%–72.2%, 17.1%–23.5%, 12.3%–34.2%, and 43.1%–131.2%, respectively, higher in treatments with stem nodule than those without stem nodule for the same soil substrate. With respect to soil substrata, all measurements had consistently higher values in tailings than in amended tailings and garden soil, indicating that the poorer the soil condition, the greater the contribution of stem nodule. In contrast, the number and fresh weight of root nodules on plants without stem nodule were 6.9–11.6 times and 5.8–29.0 times higher than those with stem nodule, respectively, especially with respect to the plants grew on Pb/Zn tailings. In general, stem nodulation favored plant growth and nitrogen fixation of S. rostrata, but suppressed root nodulation. With the ability of stem and root nodulation, S. rostrata can be used as a pioneer plant species for remediation of Pb/Zn tailings.