Benefits to poorly studied taxa of conservation of bird and mammal diversity on islands

Protected area delineation and conservation action are urgently needed on marine islands, but the potential biodiversity benefits of these activities can be difficult to assess due to lack of species diversity information for lesser known taxa. We used linear mixed effects modeling and simple spatial analyses to investigate whether conservation activities based on the diversity of well‐known insular taxa (birds and mammals) are likely to also capture the diversity of lesser known taxa (reptiles, amphibians, vascular land plants, ants, land snails, butterflies, and tenebrionid beetles). We assembled total, threatened, and endemic diversity data for both well‐known and lesser known taxa and combined these with physical island biogeography characteristics for 1190 islands from 109 archipelagos. Among physical island biogeography factors, island area was the best indicator of diversity of both well‐known and little‐known taxa. Among taxonomic factors, total mammal species richness was the best indicator of total diversity of lesser known taxa, and the combination of threatened mammal and threatened bird diversity was the best indicator of lesser known endemic richness. The results of other intertaxon diversity comparisons were highly variable, however. Based on our results, we suggest that protecting islands above a certain minimum threshold area may be the most efficient use of conservation resources. For example, using our island database, if the threshold were set at 10 km² and the smallest 10% of islands greater than this threshold were protected, 119 islands would be protected. The islands would range in size from 10 to 29 km² and would include 268 lesser known species endemic to a single island, along with 11 bird and mammal species endemic to a single island. Our results suggest that for islands of equivalent size, prioritization based on total or threatened bird and mammal diversity may also capture opportunities to protect lesser known species endemic to islands. Beneficios de los Taxa Poco Estudiados para la Conservación de la Diversidad de Aves y Mamíferos en Islas     

Emissions of particulate matter and associated polycyclic aromatic hydrocarbons from agricultural diesel engine fueled with degummed, deacidified mixed crude palm oil blends

Mixed crude palm oil(MCPO),the mixture of palm fiber oil and palm kernel oil,has become of great interest as a renewable energy source.It can be easily extracted from whole dried palm fruits.In the present work,the degummed,deacidified MCPO was blended in petroleum diesel at portions of 30% and 40% by volume and then tested in agricultural diesel engines for long term usage.The particulates from the exhaust of the engines were collected every 500 hr using a four-stage cascade air sampler.The 50% cut-off aerodynamic diameters for the first three stages were 10,2.5 and 1μm,while the last stage collected all particles smaller than 1μm.Sixteen particle bounded polycyclic aromatic hydrocarbons(PAHs) were analyzed using a high performance liquid chromatography.The results indicated that the size distribution of particulate matter was in the accumulation mode and the pattern of total PAHs associated with fine-particles(< 1μm) showed a dominance of larger molecular weight PAHs(4-6 aromatic rings),especially pyrene.The mass median diameter,PM and total PAH concentrations decreased when increasing the palm oil content,but increased when the running hours of the engine were increased.In addition,Commercial petroleum diesel(PB0) gave the highest value of carcinogenic potency equivalent(BaP eq) for all particle size ranges.As the palm oil was increased,the BaP eq decreased gradually.Therefore the degummed-deacidified MCPO blends are recommended for diesel substitute.     

Modeling the current-voltage characteristics of thin-film silicon solar cells based on photo-induced electron transfer processes

Power conversion efficiency of p-i-n type microcrystalline silicon (c-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type c-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 m) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively.     

Modeling the current-voltage characteristics of thin-film silicon solar cells based on photo-induced electron transfer processes

Power conversion efficiency of p-i-n type macrocrystalline silicon (µc-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type μc-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 μm) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively.     

锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响因素研究

本试验采用室内试验装置,研究了 pH、温度、硝酸盐浓度对锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响结果表明,pH值在5～10内变化时对锯末+乙醇混合碳源体系的硝酸盐去除率影响较大,pH ＞7时的硝酸盐去除率明显高于pH ＜7时的去除率;并且随着pH值的增加,亚硝酸盐的积累量越多,锯末+乙醇混合碳源体系最佳的pH值范围是7～8.锯末+乙醇混合碳源体系受温度的影响较大,温度为8.5、15℃时的反硝化速率显著低于25℃时的速率,25℃时的反硝化速率分别是8.5、15℃时的3倍和1.5倍,锯末+乙醇混合碳源体系适宜的温度范围为25 ～35℃进水硝酸盐浓度也会影响锯末+乙醇混合碳源体系的反硝化效果,硝酸盐氮浓度在67.8 ～113 mg·L-1范围内变化时,反应体系的硝酸盐去除效果较好反应初期,硝酸盐浓度越大混合碳源体系的反硝化速率就越低,可能较大的硝酸盐负荷对反硝化细菌产生毒害作用而不利于硝酸盐的去除.     

Machining efficiency of powder mixed near dry electrical discharge machining based on different material combinations of tool electrode and workpiece electrode

Powder mixed near dry electrical discharge machining (PMND-EDM) is a novel electrical discharge machining (EDM) process. It is proposed to further improve the machining efficiency of dry EDM. The principle of material removal in PMND-EDM is illustrated and its deionization principle is proposed. The influence of residual heat on MRR is analyzed. The concept of superfluous residual heat is proposed. The material removal rate (MRR), the main index of machining efficiency for PMND-EDM process, is researched. Single factor experiments are performed to get effect of peak current, pulse on time, pulse off time, flow rate, tool rotational speed, air pressure and powder concentration on MRR under different material combinations of tool electrode and workpiece electrode. Thermal phenomena in PMND-EDM are illustrated. Effect of each process parameter on MRR of PMND-EDM is gotten and analyzed based on the deionization principle of PMND-EDM. Differences in MRR under different material combinations are found out. Brass tool electrode and W18Cr4V workpiece gain higher MRR under most of discharge conditions, while the superiority of copper tool electrode and 45 carbon steel workpiece in MRR arise when there is improper heat dissipation. The difference is analyzed based on the deionization principle of PMND-EDM.     

混酸消解玻璃纤维滤筒滤膜法测定大气颗粒物中的铅

用高氯酸、硝酸和氢氟酸组成的混酸在加热的条件下消解玻璃纤维滤筒滤膜采集的铅尘样品,可基本除去滤膜中的硅。大部分除去滤筒中的硅,残留的硅酸对铅的溶出和准确测定不干扰。因此是取代索氏提取法和酸煮法的理想方法。     

1961~2019年黄河流域大气自净能力指数变化特征分析

利用2015~2019年环境空气质量监测数据和黄河流域73个站点1961~2019年的气象观测资料,对11个站点的大气自净能力指数的适用性及其与环境空气质量之间的关联性进行了验证,并分析了黄河流域大气自净能力指数的时空变化特征及影响因子.结果表明,1961~2019年黄河流域大气自净能力指数整体呈下降趋势,下降速率为每10a下降0.18t/（d×km²）,平均值为4.44t/（d×km²）,且在1969年达到最大值,为5.32t/（d×km²）,2011年达到最小值,为3.81t/（d×km²）;黄河流域73个站点中有64个站点大气自净能力指数呈下降趋势,50个站点呈显著和极显著下降趋势.从年内变化看出,黄河流域大气自净能力指数最高值出现在4月,为5.30t/（d×km²）,最低值出现在1月,为3.48t/（d×km²）.在年空间分布上,黄河流域大气自净能力指数分布以青海西南部,山东、四川大部分地区,内蒙古、宁夏以及甘肃少部分地区,陕西西安,山西的五寨和右玉等大气自净能力较好,大气自净能力指数在4.69~7.18t/（d×km²）,其余地区大气自净能力相对较差.影响因子中,混合层高度与大气自净能力指数呈极显著正相关,相关系数为0.63（n=4307）;小风日数与大气自净能力指数呈极显著负相关,相关系数为-0.78（n=4307）,日平均风速³2.5m/s的日数及日平均风速³5.5m/s的日数与大气自净能力指数均呈极显著正相关,相关系数分别为0.78和0.55（n=4307）;降水日数与大气自净能力指数呈极显著正相关,相关系数为0.18（n=4307）,中雨及以上日数与大气自净能力指数呈显著正相关,相关系数为0.03（n=4307）,黄河流域小雨对大气自净能力的影响明显高于中雨.逐步回归分析显示,大气自净能力指数主要受日平均风速³2.5m/s的日数、降水日数和混合层高度的综合影响,其中,日平均风速³2.5m/s的日数对大气自净能力指数的贡献率最大,其贡献为正.     

高比表面硫脲改性花生壳炭的制备及对四环素和铜的吸附

以硫脲和磷酸为改性剂,通过一步碳化制备了高活性氮硫共掺杂高比表面改性花生壳炭PBC-NS.探讨了改性花生壳炭PBC-NS吸附单一与混合体系中TC/Cu(Ⅱ)吸附特性,并研究了改性对TC/Cu(Ⅱ)吸附的增强作用及机制.结果表明,改性花生壳炭PBC-NS成功引入了砒啶氮、石墨氮、 C—S—C和—SH等氮硫官能团,且改性后比表面积高达1 437 m²·g^-1,比改性前提升了2.6倍.改性花生壳炭PBC-NS对单一体系TC和Cu(Ⅱ)的最大吸附量分别为585mg·g^-1和21.2mg·g^-1,较改性前提升2.6倍和2.7倍;且PBC-NS对混合体系中的TC和Cu(Ⅱ)的饱和吸附量较单一体系提升13mg·g^-1和6.8mg·g^-1.PBC-NS在4次重复使用后对TC和Cu(Ⅱ)的吸附容量仍能达到初始吸附量的66%和70%.等温拟合与现代光谱分析表明,改性使PBC-NS对TC/Cu(Ⅱ)吸附量的大幅提高主要归因于氮硫活性官能位的化学络合和高比表面引起的孔填充共同作用...     

不同取样尺度和数量下针阔混交林土壤呼吸的空间异质性

区域土壤呼吸通量估算大多用样地尺度的测定结果进行外推,因此对样地尺度土壤呼吸(Rs)及其影响因子的空间关系和取样尺度、取样数量对测定结果的准确性进行评价非常重要.以山西省庞泉沟自然保护区针阔混交林作为研究样地,运用传统统计分析与地统计分析相结合的方法,分析了4、2、1 m取样尺度下土壤水分(Ws)、土壤温度(T10)、凋落物量(Lw)、凋落物含水量(Lm)、土壤全碳(C)、全氮(N)和全碳/全氮(C/N)对土壤呼吸速率(Rs)空间变异的影响.结果表明3个取样间隔下,Rs的均值没有显著差异,但其变异程度随着取样尺度的增大而增加,变异系数在16%~22%之间.在4 m取样间隔下,Rs与Ws、Lw、C、C/N呈极显著正相关(P0.01),与N呈显著正相关(P0.05);在2 m取样间隔下,Rs与T10呈极显著负相关(P0.01),与其他因子相关不显著;在1 m取样间隔下,Rs与其他影响因子的相关性都不显著.随着取样尺度的减小,Rs的空间自相关性逐渐减弱,由高度自相关变为弱相关,表明随着采样距离的减小,结构因素对Rs的作用减弱,随机因素的作用逐渐增大.同一置信水平下相同取样数量随着取样尺度的减小,估计误差降低.95%置信水平下,2 m和1 m取样尺度时9个样本产生的Rs误差在±12%左右,而4 m尺度的误差为±16%;90%置信水平下,2 m和1 m取样尺度时9个样本产生的误差在±10%以内,4 m尺度则为±13%.研究结果可以为样地尺度进行Rs季节测定样点的科学布设提供依据.