西施舌形态性状与体质量性状的相关性分析

为研究西施舌(Coelomactra antiquata)野生群体壳体性状对体质量性状的影响,文章以广西北海铁山港海区采集的178只西施舌为研究对象,测量壳高(SH)、壳长(SL)、壳宽(SW)、前缘长(AL)、后缘长(GL)、壳质量(SM)、软体部质量(VM)、活体质量(BM),以壳体性状(SH、SL、SW、AL、GL、SM)为自变量,体质量性状(BM、VM)为因变量进行相关性分析、通径分析、多元回归分析。结果表明西施舌8个数量性状中,软体部质量变异系数最高,性状间的相关性均达到极显著水平(P<0.01),活体质量和软体部质量分别与壳高和壳质量的相关系数最大(0.831和0.646);壳宽和壳质量分别对活体质量和软体部质量的直接影响最大,通径系数分别为0.362和0.487,决定程度分析与通径分析结果变化趋势一致;建立了关于体质量性状的回归方程(R2<0.85)。     

Poorly crystalline iron and aluminium oxides contribute to the carbon saturation and sorption of dissolved organic carbon in the soil

Soil carbon (C) saturation implies an upper limit to a soil's capacity to store C depending on the contents of silt + clay and poorly crystalline Fe and Al oxides. We hypothesized that the poorly crystalline Fe and Al oxides in silt + clay fraction increased the C saturation and thus reduced the capacity of the soil to sorb additional C input. To test the hypothesis, we studied the sorption of dissolved organic carbon (DOC) on silt + clay fractions (<53 µm) of highly weathered oxic soils, collected from three different land uses (i.e., improved pasture, cropping and forest). Soils with high carbon saturation desorbed 38% more C than soils with low C saturation upon addition of DOC, whereas adsorption of DOC was only observed at higher concentration (>15 g kg^?1). While high Al oxide concentration significantly increased both the saturation and desorption of DOC, the high Fe oxide concentration significantly increased the desorption of DOC, supporting the proposition that both oxides have influence on the DOC sorption in soil. Our findings provide a new insight into the chemical control of stabilization and destabilization of DOC in soil.     

Glacier mass balance in High Mountain Asia inferred from a GRACE release-6 gravity solution for the period 2002–2016

We provide estimates of glacier mass changes in the High Mountain Asia (HMA) area from April2002 to August 2016 by employing a new version of gravity solutions of the Gravity Recovery and ClimateExperiment (GRACE) twin-satellite mission. We find a total mass loss trend of the HMA glaciers at a rateof –22.17 (±1.96) Gt/a. The largest mass loss rates of –7.02 (±0.94) and –6.73 (±0.78) Gt/a are found forthe glaciers in Nyainqentanglha Mountains and Eastern Himalayas, respectively. Although most glaciers inthe HMA area show a mass loss, we find a small glacier mass gain of 1.19 (±0.55) and 0.77 (±0.37) Gt/a inKarakoram Mountains and Western Kunlun Mountains, respectively. There is also a nearly zero massbalance in Pamirs. Our estimates of glacier mass change trends confirm previous results from the analysisof altimetry data of the ICESat (ICE, Cloud and Land Elevation Satellite) and ASTER (AdvancedSpaceborne Thermal Emission and Reflection Radiometer) DEM (Digital Elevation Model) satellites inmost of the selected glacier areas. However, they largely differ to previous GRACE-based studies which weattribute to our different post-processing techniques of the newer GRACE data. In addition, we explicitlyshow regional mass change features for both the interannual glacier mass changes and the 14-a averagedseasonal glacier mass changes. These changes can be explained in parts by total net precipitation (netsnowfall and net rainfall) and net snowfall, but mostly by total net radiation energy when compared to datafrom the ERA5-Land meteorological reanalysis. Moreover, nearly all the non-trend interannual masschanges and most seasonal mass changes can be explained by the total net radiation energy data. The massloss trends could be partly related to a heat effect due to increased net rainfall in Tianshan Mountains, QilianMountains, Nyainqentanglha Mountains and Eastern Himalayas. Our new results for the glacier mass changein this study could help improve the understanding of glacier variation in the HMA area and contribute tothe study of global change. They could also serve the utilization of water resources there and in neighboringareas.     

基于DEM仿真与试验验证的双轴螺旋输送机结构优化分析

针对螺旋输送机的输送效率问题,对双轴螺旋输送机输送颗粒物料的过程进行离散元法数值计算,并与单轴螺旋输送机输送物料的试验和模拟结果进行对比。在试验验证了仿真模型和参数正确的基础上,对双轴螺旋输送机的轴距和螺距2个参数与质量流速率(■)间的定量关系进行二元二次多项式拟合,得到拟合优度R~2=0.964 6的回归方程。研究结果表明:1)双轴的相对转动方向对■没有影响;2)螺距和轴距对■均有明显影响。■随着轴距的增大显著增大,大螺距时会在达到极值后趋于稳定或略有下降;■随着螺距的增大先增大至峰值后下降;3)双轴的螺距和轴距对颗粒运动影响显著。两轴中间位置颗粒的最小轴向平动速度与轴距呈现近似线性的递减关系,且螺距越大,其减小趋势越明显。     

沙棘果实中主要活性成分质量分布

沙棘作为一种抗逆性、适应性、萌蘖性较强的植物资源，被广泛应用于黄土丘陵地区荒山绿化、土壤改良、水土保持和砒砂岩治理。沙棘不仅具有良好的生态价值，其果实中富含多种生物活性物质。本文凝练了沙棘果实中活性化合物的构成、分布及活性特征，并对沙棘果实活性物质的研究进行展望。基于相关文献，针对黄酮、花青素、酚酸、有机酸、肌醇、维生素、类胡萝卜素、不饱和脂肪酸、甾醇等广泛存在于沙棘果实中的化学成分进行总结分析，提供沙棘果实中上述活性物质分布情况的综合信息。研究表明，针对沙棘果实中活性物质的构成、分布和活性特征的研究较为丰富，但在部分领域仍缺乏研究，如栽培技术条件对活性物质的影响，活性物质与沙棘果实加工中异味的关联性等。本文为沙棘果实在食品、药品及保健品行业中的综合利用提供了理论支撑，为促进沙棘资源在经济中的全面发展提供参考。      

超高效液相色谱-串联质谱法测定饲料中的二氢吡啶

【目的】二氢吡啶是一种新型的饲料添加剂,具有促进动物生长、提高饲料利用率、改善肉质等功效,目前已在畜牧生产中得到广泛应用。然而,二氢吡啶并不是允许使用的药物饲料添加剂,其在饲料中高水平添加所带来的畜产品中二氢吡啶残留可引起敏感人群严重的低血压反应。央视3.15晚会曝光了部分饲料企业违规使用二氢吡啶、硫酸黏杆菌素、喹乙醇等兽药,引起社会的广泛关注和政府的高度重视,因而亟需建立饲料中二氢吡啶的检测方法,为饲料企业合理用药和政府监管提供必要的技术支撑。【方法】采用UPLC上常用的BEH C18色谱柱,分别使用甲醇-水、乙腈-水、甲醇-0.1%甲酸、乙腈-0.1%甲酸作为流动相,优化了不同组成和比例流动相对色谱分离和质谱电离的影响。在正离子模式下进行母离子扫描,确定准分子离子,优化仪器毛细管电压、锥孔电压、雾化气流速等参数;然后进行子离子扫描,优化碰撞能量、驻留时间等参数,以确定丰度较高的两个子离子作为定性离子,并选择其中丰度最高的作为定量离子。比较甲醇、乙腈等不同溶剂对提取效率的影响,以及C18、HLB、MCX和碱性氧化铝等固相萃取柱(SPE)对净化效果的影响,确定较优的样品前处理方法。【结果】优化确定了较佳的前处理方法:采用乙腈超声提取,提取液在60℃下氮气吹干,残余物用乙腈﹕水(1﹕9,v/v)复溶,过HLB固相萃取柱净化,用乙腈﹕水(9﹕1,v/v)洗脱,洗脱液过0.22μm有机滤膜后上超高效液相色谱-串联质谱仪(UPLC-MS/MS)测定。采用电喷雾离子源,在多反应监测(MRM)模式下,二氢吡啶的[M+H]+为m/z 254,失去乙氧基(CH3-CH2-O+,46 Da)后产生主要的碎片离子m/z 208,m/z 208脱掉羰基(C=O,28 Da)产生碎片离子m/z 180,m/z 180进一步脱去乙酯基(CO-O-CH2-CH3,73 Da)后得到碎片离子m/z 108,因此本研究以离子对m/z 254208为定量离子,m/z 254180为定性离子。以0.1%的甲酸水-乙腈为流动相进行梯度洗脱,在10 min内完成了二氢吡啶的分离,且峰形尖锐,灵敏度高。二氢吡啶在0—500μg·L~(-1)浓度范围内呈现良好的线性关系(R2≥0.9992),根据20个空白样品的基线噪音,取其平均值,以信噪比(S/N)=3为检出限(LOD),S/N=10为定量限(LOQ),二氢吡啶的LOD、LOQ分别为10和50μg·kg-1。在10、50和100μg·kg-1三个添加水平下,二氢吡啶的平均回收率为82.6%—101.0%,日内变异系数为0.8%—6.7%,日间变异系数为4.7%—9.2%。【结论】该方法操作简便、快速、稳定,适用于饲料中二氢吡啶的日常监测。     

Relationship Between Allelopathic Effects and Functional Traits of Different Allelopathic Potential Rice Accessions at Different Growth Stages

In this study,effects of temperature,light and their interactions on allelopathic effects and the functional traits specific leaf area(SLA)and stem mass fraction(SMF)of different allelopathic potential rice accessions at different growth stages were analyzed.The main results were as follows:Allelopathic responses to temperature and light varied with different allelopathic potential rice accessions at different growth stages.With the rise of temperature and the extension of photoperiod,allelopathic effect increased firstly and then decreased at 2–3 leaf stage,but increased constantly at the 4–5 and 7–8 leaf stages in strong allelopathic rice accessions[O.longistaminata,F1(O.longistaminata×RD23),F2(RL159 and RL169)].Temperature had significant impact on allelopathic effect without considering light factors,but light showed little effect on rice allelopathy at the same temperature conditions.The greatest allelopathic effect was attained with moderate temperature and long photoperiod at 2–3 leaf stage in strong allelopathic rice accessions,but all the rice accessions showed weak allelopathic effects at the low temperature condition(15oC/10oC),and the influence of different factors on allelopathy followed a general trend as temperatureleaf stagelight,indicating that among the multiple factors impacting rice allelopathy,temperature was the main factor.Allelopathic characteristics of F1 and F2 to various temperature and light were similar to O.longistaminata,showing that allelopathic genes from wild rice can be expressed in its descendants.Temperature and light also had significant effects on SLA and SMF,and rice allelopathy was closely correlative to SLA in strong allelopathic rice accessions at the 4–5 and 7–8 leaf stages,but there was no correlation between rice allelopathy and SMF at different growth stages.These results suggested that rice adjust the relationship between allelopathy and SLA and adapt to the varied environments,and that high temperature and long photoperiod can enhance rice allelopathic activity.     

电感耦合等离子体发射光谱法测量土壤中有效锌含量的不确定度评估

对电感耦合等离子体发射光谱法(ICP-OES)测定土壤有效锌含量的不确定度进行评定,分析了整个检测过程产生不确定度的来源,对称样量、浸提液体积、标准系列溶液配制、线性标准曲线拟合、测量重复性等产生的不确定度分量进行计算,量化给出扩展不确定度。待测土壤中有效锌含量最终结果表示:w(Zn)=(1.12±0.10)mg/kg,包含因子k=2,置信概率为95%。测量过程中,标准溶液制备所产生的不确定度最大。因此,在ICP-OES法测定土壤样品有效锌时应足够重视标准溶液制备与曲线拟合过程,以减小测量不确定度。本文研究结果为控制ICP-OES法测定土壤有效锌数据质量提供了理论依据。     

Divergent effects of defoliation intensity and frequency on tiller growth and production dynamics of Pascopyrum smithii and Hesperostipa comata

Rotational stocking theoretically enables regrazing of regrowth, but regrowth may be limited in xerophytic vegetation. We tested the hypothesis that regrowth would be slow and fixed in Hesperostipa comata (a caespitose, drought‐tolerant grass), while growth would be flexible in Pascopyrum smithii (a rhizomatous, less drought‐tolerant grass) under increasing defoliation and moisture, by assessing tiller growth rates, population dynamics and plant yield on marked plants in a Dry Mixed Grass prairie. Plots were clipped in late summer to simulate a deferred control, or intermittently during the growing season (May–August) at high intensity–low frequency (HILF), low intensity–high frequency (LIHF) or high intensity–high frequency and crossed with two water treatments (ambient and addition) in both a xeric upland and a mesic lowland. Growing season defoliation increased tiller growth rates of P. smithii in the upland, whereas HILF and LIHF reduced growth in the lowland. All defoliation regimes increased tiller growth for H. comata. Tiller populations of H. comata increased with frequent defoliation, while tiller populations of P. smithii decreased regardless of defoliation regime. Frequent defoliation, regardless of intensity, reduced yield relative to the deferred control for both grasses. While water addition consistently increased growth rates and reduced differences in tiller number among defoliation treatments, the regrowth of both grasses remained similar under varied defoliation with ambient moisture. High moisture conditions also promoted regrowth more in P. smithii compared to H. comata. In summary, neither grass species displayed an inherently fixed or flexible tiller or plant yield response in response to defoliation or moisture.     

QuEChERS-超高效液相色谱-串联质谱技术同时测定大蒜中10种农药残留

建立了快速、准确测定大蒜中10种农药多残留的QuEChERS-超高效液相色谱-串联质谱检测技术。样品经酸化乙腈提取,无水硫酸镁(500 mg)除水后,用N-丙基乙二胺(PSA,500 mg)和十八烷基键合硅胶(C₁₈,500 mg)净化,以乙腈和0.1%甲酸水溶液为流动相进行梯度洗脱,Waters C₁₈色谱柱分离,采用正离子多反应监测(MRM)模式检测,基质匹配标准溶液外标法定量。10种农药的检出限在0.020~0.800 μg·kg^-1,定量限在0.067~2.670 μg·kg^-1。线性范围内相关系数均大于0.99。加标回收率在73.4%~109.0%,相对标准偏差在1.2%~9.8%。结果表明,该方法简便、快速、灵敏度高、重现性好,可同时测定大蒜中10种农药。