海洋生物质的热解特性与动力学研究

以定生浒苔、漂浮浒苔、石莼、大叶藻、海带、龙须菜和裙带菜7种海洋生物质为研究对象,以1种草类生物质玉米秸秆、1种木质类生物质锯末为对照,用热重分析法对其热解过程及其动力学规律进行了研究。利用TG-DTG-DTA曲线分析了它们的基本热解特性。结果表明,整个热解过程主要为干燥失水、剧烈失重和缓慢失重3个阶段,海洋生物质的Tmax明显低于2类陆生生物质,而且大叶藻的热解稳定性相对较高,而漂浮浒苔的热解稳定性较低,燃烧特性较好。同时,用Coats-Redfern法求得相应的活化能E和频率因子A,发现3类生物质的热解反应机理函数不同。     

Al_2O_3催化剂对海洋生物质热解特性的影响

以海洋生物质浒苔为研究对象,并以玉米秸秆(草类生物质)和锯末(木质类生物质)为对照,采用热重分析方法研究了3种生物质的热解特性,并比较了3种生物质之间的热解差异。结果表明,与玉米秸秆和锯末等典型陆生生物质相比,浒苔的热稳定性最低。此外,以不同浓度氧化铝作为催化剂,用热重分析法对其热解过程进行了研究,利用TG-DTG曲线分析了不同催化剂在不同浓度下对其基本热解特性的影响。结果表明,Al2O3对于3种生物质转化率和最大失重速率有显著的影响,其中Al2O3对锯末和浒苔的转化率降低程度比玉米秸秆较明显。考虑到Al2O3具有可调变的表面酸碱性以及多种不同的晶相结构等优点,Al2O3具有较大的的应用价值。     

棉花秸秆催化热解特性及动力学的研究

通过热重分析实验观察K2CO3、KOH、KCl、NaCl、MgCl2和ZnCl26种无机催化剂对棉花秸秆热解催化效果的影响。K2CO,、KOH处理过的棉花秆与纯棉花秆相比热解发生在较低的温度范围,而KCl、NaCl、MgCl,和ZnCl2处理过的棉花秆热解发生在较高的温度范围。碱性催化剂K2C03、KOH降低了棉花秸秆的最大质量损失率,而KCl、NaCl、MgCl2和ZnCl2却增大了棉花秸秆的最大质量损失率。应用Ozawa动力学模型得到动力学参数,棉花秸秆在热解主要阶段可由一段一级反应过程描述,升温速率10K／min时活化能值EA的范围是35～66kJ／mol,频率因子自然对数的范围是4～12。     

农田生态条件下玉米秸秆腐解过程腐解物的热解变化特征

用热分析法研究了农田生态条件下玉米秸杆腐解过程腐解物的热解变化特征,并探讨了腐解物中不同组分对腐解物热解特征的影响。结果表明,腐解物ＤＴＡ曲线的２８０℃、３３０℃、４５０℃放热峰,ＤＴＧ曲线的第二失重峰和ｈ３３０℃／ｈ４５０℃值可作为表征腐解进程的特征峰和特征值。由腐解特ＤＴＡ、ＤＴＧ所得能量各参数（△Ｈ,Ｅ）与文献「３」所述腐解物能态（Ｑｖ）呈现波动起伏,趋于稳定２个阶段相符,二者相互印证,显示     

农田生态条件下玉米秸杆腐解过程腐解物的热解变化特征

用热分析法研究了农田生态条件下玉米秸杆腐解过程腐解物的热解变化特征 ,并探讨了腐解物中不同组分对腐解物热解特征的影响。结果表明 ,腐解物 DTA曲线的 2 80℃、3 3 0℃、4 50℃放热峰 ,DTG曲线的第二失重峰和 h330℃ /h4 50℃ 值可作为表征腐解进程的特征峰和特征值。由腐解物 DTA、DTG所得能量各参数 ( ΔH,E)与文献 [3 ]所述腐解物能态 ( Qv)呈现波动起伏 ,趋于稳定 2个阶段相符 ,二者相互印证 ,显示热分析方法用于植物残体腐解进程研究的可行性。 DTA的2 80℃放热峰主要由苯 -醇溶性物、水溶性物引起。苯 -醇溶性物、水溶性物和纤维素、半纤维素是影响腐解物热解及其能态变化特征的主要物质组分。木质素组分对腐解后期腐解物的热解及其能态特征趋于稳定具有重要作用     

两种钙藻热解产出的气态和液态烃类

在２００℃至４００℃高温和还原条件下分别对仙掌藻和乳节藻两种钙质藻类进行热模拟降解实验,分离获得气态和液态烃类化合物。随着热解温度升高,两种钙藻产烃气量明显上升,其中甲烷与乙烷气的增加最多,同时两种钙藻产出的乙烷与乙烯比值都有规律地增加,但仙掌藻产烃气量高于乳节藻。这表明钙质藻类可能是天然气的一种重要母质来源。虽然这两种钙藻随温度增加热解产出的可溶有机质及族组分的变化规律不明显,但它们的正烷烃分布特征具有相类似的变化。未经热解时它们都以Ｃ１７为主峰的低碳数正烷烃占优势;当热解温度从２００℃增加到４００℃时,它们都又表现出以Ｃ２５或Ｃ２３为主峰的较高碳数正烷烃占优势的分布特征。这与富含钙藻化石的沉积岩样品中正烷烃的分布特征相一致,说明Ｃ２５或Ｃ２３为主峰的较高碳数正烷烃占优势的分布特征可能是钙藻热解有机质的一种判识标志．     

玉米秸秆生物炭制备及结构特性分析

为了高效、经济、环保地解决华北平原地区玉米秸秆处置问题并寻求有效途径,该研究以玉米秸秆为原料,采用限氧裂解法在不同温度(200℃、300℃、400℃、500℃)下制备生物炭,并对生物炭的热解动力学、结构形貌、元素组成、比表面积、孔径分布、官能团等理化特征进行了分析表征。结果表明:不同裂解温度制备的生物炭具有不同的差热曲线,其官能团的组成也存在差异,这表明了样品中不同生物质的热解反应过程。随着热解温度的升高,生物炭产率、氢和氧含量下降,同时H/C和(O+N)/C比值也降低,而碳和氮含量却升高,说明生物炭芳香性增强,亲水性和极性减弱,性质趋于稳定。生物炭热重曲线和差热曲线分为三个过程,热解温度高时失重比例低,曲线趋向平缓。生物炭的比表面积、微孔比表面积、中孔体积和微孔体积随着热解温度的升高而增大,但最可几孔径却减小,吸附能力增强。综上所述,400℃的温度制备生物炭,其产率相对较高、结构最稳定、吸附性能最佳,有助于最大程序的利用农业废弃物资源、降低耗能,提高农产品附加值。     

紫薯干燥的动力学模型及工艺优化

为了探究紫薯在干燥过程中水分变化规律,建立动力学模型,进一步为紫薯干中天然色素的高效提取给予理论依据。以新鲜紫薯为原材料,分别研究了切片厚度、热风温度和热风风速对紫薯干燥特性的影响,通过用线性回归法处理,根据较常用的薄层干燥模型进行拟合,建立紫薯热风薄层干燥的动力学模型;在以上单因素试验的基础上,采用正交实验优化提取红色素的干燥工艺参数。研究得出对紫薯薄层干燥速率的影响因素由大到小是切片厚度、热风温度、热风风速;紫薯热风薄层干燥的动力学模型满足Page方程;紫薯红色素提取的最优工艺为热风温度60℃、热风风速0.6 m/s、切片厚度6 mm,此条件下提取得率为15.90 mg/g。     

薏苡仁油回流提取工艺参数优化及其动力学研究

探索加热回流法提取薏苡仁油的最佳工艺条件,并对提取过程进行深入探讨。采用单因素法考察溶剂、料液比、药材粒径、提取时间等对薏苡仁油提取率的影响,在此基础上研究其提取动力学。结果表明薏苡仁油较佳的提取条件为采用丙酮作为溶剂,液固比7倍,药材平均粒径0.25 mm,提取3 h。动力学研究表明,粒径较小时(0.25~0.83 mm),薏苡仁油的提取动力学符合二阶溶出动力学模型,即减小药材粒径,可明显增加有效成分的提取率。     

样品保存条件对土壤与植物全碳全氮含量的影响

土壤与植物的保存样品对生态学研究有重要意义,但目前未得到广泛应用。该研究的目的是比较样品保存前后全碳、全氮含量的变化,探讨保存样品应用于长时间序列的生态学研究的可行性。研究选取2011年生长季采集的土壤与植物样品,保存4年之后测试碳、氮质量分数,与保存前的测试数据通过成对t检验与线性回归进行比较。氮质量分数在不同保存条件下,保存前后的测试数据之间均为1:1的线性关系,除低温保存、粒径2 mm的土壤样品相关系数为0.91外,其余保存条件下相关系数均大于0.98。碳质量分数保存后的变化与保存条件有关,粒径0.15 mm的土壤与植物样品,两次测试数据之间为1:1的线性关系,相关系数均大于0.98;粒径2 mm的土壤与植物样品两次测试数据的线性关系斜率分别为1.26与1.04,即2016年测试数据显著高于2012年。结果表明不同保存温度与样品粒径下,样品保存后的氮含量没有变化;而碳含量的稳定与样品粒径有关,常温保存与20℃低温下保存则无明显区别。建议用于碳氮元素分析的样品应充分干燥、研磨成0.15 mm粒径后在常温环境下密封保存。     

影响水稻光合日变化的酶和相关因素的分析

水稻叶片的最大光合速率出现在上午１０：００时,Ｒｕｂｉｓｃｏ初始活力也在此时达到最大,然后逐渐降低,下午１４：００时略上升后又下降．Ｒｕｂｉｓｃｏ初始活力与光合速率之间极显著相关,相关系数为 ０．９４７４．运用相关性分析、回归分析、通径分析,对晴（有时有云）天气水稻叶片的光合速度、光合关键酶及有关因素的日变化进行综合评估,结果发现中午光合下降主要来自气孔限制,同时Ｒｕｂｉｓｃｏ活性也下降;Ｒｕｂｉｓｃｏ活性是影响光合日变化的又一重要生化因子．体内Ｒｕｂｉｓｃｏ活性受Ｒｕｂｉｓｃｏ活化酶的调节．     

Numerical approaches towards life cycle interpretation five examples

The ISO-standard for LCA distinguishes four phases, of which the last one, the interpretation, is the least elaborated. It can be regarded as containing procedural steps (like a completeness check) as well as numerical steps (like a sensitivity check). This paper provides five examples of techniques that can be used for the numerical steps. These are the contribution analysis, the perturbation analysis, the uncertainty analysis, the comparative analysis, and the discernibility analysis. All five techniques are described at a non-technical level with respect to basic concept, possibilities, tabular and graphical representation, restriction and warnings, and all are illustrated with a simple example.     

Discrimination of higher plant calluses based on embryogenic capacity and taxonomic classification by pyrolysis mass spectrometry

Pyrolysis mass spectrometry (PyMS) is a rapid, simple, high-resolution analytical method based on thermal degradation of complex material in a vacuum, and has been widely applied to the discrimination of closely related microbial strains. Minimally prepared samples of embryogenic and non-embryogenic calluses derived from various higher plants (sweet potato, morning glory, Korean ginseng, Siberian ginseng, and balloon flower) were subjected to PyMS for spectral fingerprinting. A dendrogram based on the unweighted pair group method, with arithmetic mean of pyrolysis mass spectra, divided the calluses into Siberian ginseng embryogenic callus and the others, which were subsequently divided into embryogenic and non-embryogenic callus groups, regardless of plant species from which the calluses were derived. In the non-embryogenic callus group, the dendrogram was in agreement with the known taxonomy of the plants. These results indicate that PyMS analysis could be applied for discriminating plant calluses based on embryogenic capacity and taxonomic classification.     

Intraspecific variation in Licuala glabra Griff. (Palmae) in Peninsular Malaysia– a morphometric analysis

We studied vegetative and reproductive characters of 74 herbarium specimens of Licuala glabra Griff. (Palmae) collected from 22 localities throughout Peninsular Malaysia. To test the null hypothesis that there are no distinct groups within the species, cluster analysis (nearest neighbour), principal coordinates and principal components analyses were performed on the set of 43 qualitative and quantitative characters. The results obtained suggested that: (1) there are three infraspeciflc groups within the species, viz., the two published varieties glabra and selangorensis as well as a possible third novel taxon; (2) there is clustering of individuals corresponding to their geographic localities; (3) clusters generated using only reproductive characters indicate a biogeographic distribution of populations correlated with the mountain ranges in the peninsula.     

Some remarks about the analysis of active control studies

In an active-controlled trial, the experimental treatment can be declared to be non-inferior to the control if the confidence interval for the difference excludes a fixed pre-specified margin. Recently, some articles have discussed an alternative method where the data from the current study and placebo-controlled studies for the active control are combined together into a single test statistic to test whether a fixed fraction of the effect of the active control is preserved. It has been shown that, conditional on nuisance parameters from the active-controlled study, a fixed margin can be defined that will be operationally equivalent to this latter method. In this article, we will discuss statistical properties associated with these approaches. Specifically, the interim monitoring boundaries and level of evidence will be considered.     

Normal Approximations of Exact Tests in Configural Frequency Analysis

The most common tests for types and antitypes in configural frequency analysis are normal approximations of exact tests. In the paper such statistics under the complete independence model and under the fixed margins model are discussed. It turns out that these test statistics are not acceptable when the number of simultaneously performed tests is large or when the expected frequencies are small. In these cases, the use of exact tests is advocated and some existing computer programs for such tests are indicated. A normal approximation based on the strong version of the De Moivre-Laplace limit theorem is also discussed. Empirical examples are given from longitudinal data describing psychological development of boys.     

甲醇对酵母过氧化氢酶活性的影响机理研究

将酵母过氧化氢酶加入一定比例的甲醇,测定其活性变化。结果表明:在含2%甲醇时酶活比对照提高4026%。将粗酶液用70%饱和度的硫酸铵盐析后离心所得的上清液再加入硫酸铵至80%饱和度,离心的沉淀溶解在缓冲液中,上SephadexG75柱,分离出的有酶活性的蛋白峰经电泳得一条蛋白带,说明过氧化氢酶已经被提纯到电泳纯。光谱分析发现,甲醇处理后过氧化氢酶纯酶的吸收光谱和荧光发射光谱与未经处理的比较基本不变,而差示光谱出现明显的正峰和负峰。由动力学分析可知,在甲醇中,过氧化氢酶的Vmax和Km值均有不同程度提高 。     

Fish ecoregions of Kansas: stream fish assemblage patterns and associated environmental correlates

Synopsis Principal components analysis was performed on fish presence/absence data for 39 common fish species from 410 stream sites in Kansas. The analysis confirmed ten ecologically meaningful fish assemblages, based on species associations. Factor scores based on these assemblages were then clustered into six geographic areas or fish ecoregions. Canonical discriminant analysis identified environmental variables that distinguished the derived fish ecoregions. Mean annual runoff, mean annual growing season, and discharge appear most important. Mean width, mean depth, chloride concentration, water temperature, substrate type, gradient, and percent of pool habitat were less important. Correspondence exists between these fish ecoregions and the patterns of physiographic regions, river basins, geology, soil, and potential natural vegetation in Kansas. The multivariate statistical approach used to classify fish ecoregions should have considerable potential value for fish assessment and management purposes in areas other than the state of Kansas.     

Phenotypic evaluation of genetic variability and selection of yield contributing traits in chickpea recombinant inbred line population under high temperature stress

Heat is a major abiotic stress that drastically reduces chickpea yield. This study aimed to identify heat-responsive traits to sustain crop productivity by screening a recombinant inbred line (RILs) population at two locations in India (Ludhiana and Faridkot). The RIL population was derived from an inter-specific cross between heat-tolerant genotype GPF 2 (C. arietinum L.) and heat sensitive accession ILWC 292 (C. reticulatum). The pooled analysis of variance showed highly significant differences for all the traits in RILs and most of the traits were significantly affected by heat stress at both locations. High values of genotypic coefficient of variation (19.52–38.53%), phenotypic coefficient of variation (20.29–39.85%), heritability (92.50–93.90%), and genetic advance as a percentage of mean (38.68–76.74%) have been observed for plant height, number of pods per plant, biomass, yield, and hundred seed weight across the heat stress environments. Association studies and principal component analysis showed a significant positive correlation of plant height, number of pods per plant, biomass, hundred seed weight, harvest index, relative leaf water content, and pollen viability with yield under both timely-sown and late-sown conditions. Path analysis revealed that biomass followed by harvest index was the major contributor to yield among the environments. Both step-wise and multiple regression analyses concluded that number of pods per plant, biomass and harvest index consistently showed high level of contribution to the total variation in yield under both timely-sown and late-sown conditions. Thus, the holistic approach of these analyses illustrated that the promising traits provide a framework for developing heat-tolerant cultivars in chickpea.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-00977-5.     

分子水平的遗传多样性及其测量方法

遗传多样性水平是一项很重要的数据。目前从分子水平量化遗传多样性的方法以等位酶分析、ＲＦＬＰ分析和ＲＡＰＤ分析为代表。遗传变异在基因组中并非随机分布,所以取样方式对分析结果的影响不容忽视。本文叙述了遗传变异的产生和分布,并以此为基础比较了上述３种分析方法的理论与实践。