The Effect of Biomass Densification on Structural Sugar Release and Yield in Biofuel Feedstock and Feedstock Blends

In this work, we examined the behavior of feedstock blends and the effect of a specific feedstock densification strategy (pelleting) on the release and yield of structural carbohydrates in a laboratory-scale dilute acid pretreatment (PT) and enzymatic hydrolysis (EH) assay. We report overall carbohydrate release and yield from the two-stage PT-EH assay for five single feedstocks (two corn stovers, miscanthus, switchgrass, and hybrid poplar) and three feedstock blends (corn stover-switchgrass, corn stover-switchgrass-miscanthus, and corn stover-switchgrass-hybrid poplar). We first examined the experimental results over time to establish the robustness of the PT-EH assay, which limits the precision of the experimental results. The use of two different control samples in the assay enabled us to identify (and correct for) a small bias in the EH portion of the combined assay for some runs. We then examined the effect of variable pretreatment reaction conditions (residence time, acid loading, and reactor temperature) on the conversion of a single feedstock (single-pass corn stover, CS-SP) in order to establish the range of pretreatment reaction conditions likely to provide optimal conversion data. Finally, we applied the assay to the 16 materials (8 feedstocks in 2 formats, loose and pelleted) over a more limited range of pretreatment experimental conditions. The four herbaceous feedstocks behaved similarly, while the hybrid poplar feedstock required higher pretreatment temperatures for optimal results. As expected, the yield data for three blended feedstocks were the average of the yield data for the individual feedstocks. The pelleting process appears to provide a slightly positive effect on overall total sugar yield.     

On Polydispersity of Plant Biomass Recalcitrance and Its Effects on Pretreatment Optimization for Sugar Production

This paper discusses a property associated with plant biomass recalcitrance to enzyme and microbial deconstructions in sugar production from cellulose and hemicelluloses. The hemicelluloses are more readily hydrolyzed to sugars than is cellulose. As a result, optimization to maximize individual glucose and hemicellulose sugar recovery is not possible. This property is an inherent feature of plant biomass and is named polydispersity of plant biomass recalcitrance (PPBR) in this study. A set of pretreatment experiments using eucalyptus and sulfite pretreatment to overcome recalcitrance of lignocelluloses was conducted. The results were used to predict the conditions for individually maximizing enzymatic glucose and xylose yields. The predicted maximal yields were used to quantitatively illustrate the PPBR concept. The effect of PPBR on pretreatment optimization and strategies for maximal sugar recovery using two-stage pretreatment are discussed.     

肉苁蓉和寄主梭梭体内可溶性糖分积累与蔗糖代谢相关酶活性研究

通过测定不同发育时期肉苁蓉和寄主梭梭体内主要糖类物质含量和蔗糖代谢相关酶活性,以研究寄生植物与寄主植物的糖代谢及其关系。结果表明:未寄生肉苁蓉的梭梭以积累葡萄糖为主,而寄生肉苁蓉的梭梭在夏季休眠期以积累葡萄糖为主,进入秋季旺盛生长期时以积累蔗糖为主。肉苁蓉的糖分积累与梭梭不同,己糖含量约占可溶性总糖的62.45%,而蔗糖仅为可溶性总糖的4.98%,故肉苁蓉为己糖积累型。寄主梭梭同化枝内蔗糖磷酸合成酶活性较转化酶活性和蔗糖合成酶活性低,其中寄生肉苁蓉的梭梭的分解酶类活性高于未寄生肉苁蓉的梭梭。肉苁蓉体内转化酶活性较低,而蔗糖合成酶和蔗糖磷酸合成酶活性较高,且蔗糖合成酶活性高于蔗糖磷酸合成酶活性,表现为肉苁蓉中的分解酶类活性高于合成酶类活性,较高的分解酶类活性促进了蔗糖的分解,从而促进了糖分由寄主梭梭向肉苁蓉的不断转移。总体来看,肉苁蓉和寄主梭梭体内糖分的代谢主要以蔗糖合成酶为主,其它2种酶为辅协同参与调控。     

喜树叶、枝水溶性糖提取的研究

用正交实验结果作方差分析表明：溶剂用量对试验结果有较显著的影响（a=0.10),提取温度对试验结果也有较大的影响,而提取时间对试验结果的影响不显著。喜树叶中水溶性糖的提取最优方案是A3C2B3,即溶剂用量为60ml,提取温度80℃,提取时间60min;喜树叶水溶性糖的提取最优方案是A2C2B1,即溶剂用量为40ml,提取温度80℃,提取时间20min。通过对喜树叶与枝的成对比较分析,叶与枝的水溶性糖含量无显著差异。     

Dispersion Estimation and Its Effect on Test Performance in RNA-seq Data Analysis: A Simulation-Based Comparison of Methods

A central goal of RNA sequencing (RNA-seq) experiments is to detect differentially expressed genes. In the ubiquitous negative binomial model for RNA-seq data, each gene is given a dispersion parameter, and correctly estimating these dispersion parameters is vital to detecting differential expression. Since the dispersions control the variances of the gene counts, underestimation may lead to false discovery, while overestimation may lower the rate of true detection. After briefly reviewing several popular dispersion estimation methods, this article describes a simulation study that compares them in terms of point estimation and the effect on the performance of tests for differential expression. The methods that maximize the test performance are the ones that use a moderate degree of dispersion shrinkage: the DSS, Tagwise wqCML, and Tagwise APL. In practical RNA-seq data analysis, we recommend using one of these moderate-shrinkage methods with the QLShrink test in QuasiSeq R package.     

补充蓝光对设施栽培油桃光合性能及糖酸积累的影响

以设施曙光油桃(Prunus persica cv. ‘Shuguang’)为试材, 设置补充蓝光处理, 测定了生育期内5个关键时期叶片的光合性能相关参数及果实的糖酸组分, 并观察了叶片气孔的变化情况。结果表明: 补充蓝光后油桃叶片的净光合速率提高, 叶绿素a和b含量增加, 叶绿素a/b显著降低, 叶面积增大; 气孔开放提前并较早达到最大开度, 且关闭延迟。叶片中检测到的主要同化物为果糖、葡萄糖和山梨醇, 以山梨醇为主; 果实中则为果糖、葡萄糖、山梨醇和蔗糖, 成熟期以蔗糖为主。补充蓝光处理的叶片中3种同化物积累较少, 而果实中总糖和蔗糖含量较高, 表明蓝光处理提高了光合同化物从叶片到果实的转运转化能力。草酸是叶片和果实中主要的有机酸, 补充蓝光处理的果实中有机酸含量显著降低, 糖酸与对照相比提高了30.5%。硬核期后是蓝光处理提高果实糖酸比的关键时期, 此时补充蓝光可改善设施油桃光合性能及果实品质, 这一技术措施有望应用到设施果树的栽培中。     

The Relative Age Effect and Its Influence on Academic Performance

Introduction and Purpose

The policy of school organisation for grouping students in the same academic year is based on date of birth. The differences in the experiences and maturation of older students involve a relatively better performance in academic settings, which is known as the relative age effect (RAE). This effect is more important the younger the student is. The goal of this study is to identify the connections of influence that RAE, socioeconomic status (SES), and type of institution have on academic performance in a school population of eighth graders.

Methods

The study is based on a population-based, representative sample of 15,234 8th graders (50.4% female; average age = 13.61 years) in the 2011 National System of Quality Assessment in Education Survey (SIMCE) from Chile. The SIMCE for global academic performance consists of 4 tests: reading, mathematics, social studies, and science. All tests consist of multiple-choice and closed questions. In addition, in order to have the information of general academic performance, an extra variable expressing the average score of each student was created. Also, the SIMCE includes additional variables for the evaluation process such as SES or type of school. Students were assigned to one of five age groups in terms of date of birth (G1, G2, G3, G4, and G5), in which students belonging to G1 are the oldest and students belonging to G5 are the youngest.

Results

The results achieved in the structural equation modelling indicate a good global fit. Individual relationships show significant effects of the three variables observed on academic performance, although SES received the highest values. The influence of RAE took place both in the full sample and sub-samples composed according to the SES and academic performance, showing higher values for students with lower scores. Although the influence of RAE decreases when SES is controlled, its effect is still significant and contributes to additionally explain the performance.

Conclusions

The RAE remains, even with residual values, an explanatory factor in academic performance even in eighth graders. Since the RAE decreases as the influence of schooling increases, the potential adverse effects for some students would be placed in previous and initial moments of formal schooling. These findings may be useful into taking steps towards flexibilisation on age of entry in compulsory schooling. Moreover, the need to implement early, comprehensive evaluation systems which include aspects related to neurodevelopment in order to provide maximum information to parents and educators is also drawn.     

七氟醚预处理对缺血再灌注损伤大鼠的神经保护作用及机制研究

目的:探讨七氟醚对大鼠缺血再灌注损伤的保护作用。方法:选取48只体重260 g±10 g的健康雄性SD大鼠,随机分为假手术组、损伤组及七氟醚组。假手术组大鼠分离右侧颈总动脉及颈外动脉结扎,不进入颅内置入线栓。损伤组吸入100%纯氧60min之后对右颈内动脉采用尼龙线线栓法制备大脑中动脉阻闭模型(MCAO),七氟醚组吸入2.5%七氟醚(2.5%七氟醚及97.5%氧气)60 min后再行MCAO模型制备。3组大鼠缺血2 h后,进行再灌注24 h。观察三组大鼠的神经功能评分及脑组织TNF-α和IL-1β蛋白水平。结果:假手术组大鼠神经功能评分中位数为18分;损伤组评分中位数为7分;七氟醚组大鼠评分中位数为13分,三组大鼠的评分分布差异具有统计学意义(x2=35.784,P=0.000)。各组大鼠脑组织TNF-α和IL-1β蛋白总体水平差异具有统计学意义(F=15.201,P=0.00;F=26.879,P=0.000)。进一步两两比较后,损伤组TNF-α和IL-1β蛋白水平高于七氟醚组及假手术组,七氟醚组高于假手术组,但远低于损伤组水平,P=0.000。结论:七氟醚对大鼠神经功能有一定保护作用,其机制可能与其影响大鼠脑组织TNF-α及IL-1β蛋白水平,减轻脑缺血再灌注后组织炎症反应有关。     

生长调节物质和可溶性糖含量对丹参中丹酚酸类物质积累的影响

采用盆栽实验研究了生长调节物质水杨酸（SA）、茉莉酸甲酯（MeJA）、赤霉素（GA3）对不同生长时期丹参植株中非结构糖含量、碳/氮比及根中丹酚酸类物质积累的影响;并进一步测定培养基中不同浓度蔗糖、葡萄糖、果糖对丹参毛状根中丹酚酸类物质积累的影响,对盆栽实验的结论进行了验证。结果显示,SA处理的丹参幼苗及花后期植株中蔗糖含量有增加趋势,而MeJA处理的丹参幼苗及花后期植株及GA3处理的丹参花后期植株中蔗糖积累均有降低趋势;且SA、MeJA和GA3处理对花后期植株地上和地下部分碳/氮比的影响不同。然而,SA和MeJA处理的丹参幼苗及花后期植株地上部分和根中还原糖含量、GA3处理的花后期植株根中还原糖含量均显著增加;同时,SA和MeJA处理的丹参幼苗根中迷迭香酸含量,以及SA、MeJA、GA3处理的花后期植株根中迷迭香酸含量和丹酚酸类总量显著增加。毛状根培养结果进一步证明,葡萄糖促进毛状根中迷迭香酸的产生,增加丹酚酸类总量,毛状根中迷迭香酸、丹酚酸B的积累及丹酚酸类总量与培养基中蔗糖浓度不相关。可见,丹参（植株）根中丹酚酸类物质的产生和积累受SA、MeJA和GA3的诱导,其与碳/氮比及植株中蔗糖含量没有相关性,推测植株中葡萄糖含量的增加促进根中丹酚酸类物质的积累。     

Fractionation of Forest Residues of Douglas-fir for Fermentable Sugar Production by SPORL Pretreatment

Douglas-fir (Pseudotsuga menziesii) forest residues were physically fractionated through sieving. The bark and wood were separated for large-sized fractions (>12.7?mm), and their contents were determined. The chemical compositions of the large fractions were calculated based on the contents and chemical compositions of the bark and wood. The chemical compositions of the fine fractions were analyzed. The bark and wood content in the fine fractions was calculated based on the measured glucan and lignin contents in each fraction. It was found that fractionation by particle/chip size can effectively fractionate bark and wood and therefore lignin from carbohydrates. The large-sized fractions (>12.7?mm) represent approximately 60?% of the collected forest residues but only contain approximately 37?% of the total bark and 35?% of the total ash, or a selectivity over bark and ash of 1.6 and 1.7, respectively. Pretreatment of forest residues by sulfite pretreatment to overcome recalcitrance of lignocelluloses and subsequent enzymatic hydrolysis revealed the presence of 14.3?% bark can reduce substrate enzymatic digestibilities (SED) 16?% compared with that from a bark-free sample. The SED of a bark is 41?% compared with 73?% for wood when pretreated under the same conditions. Separating pretreatment of bark from wood is beneficial for producing a more enzymatically digestible substrate. The results from the present study could have significant implications for harvesting forest residues.     

黄皮种子脱水敏感性与胚轴中可溶性糖含量的关系

以典型的顽拗性种子黄皮为试材,研究了花后不同时间的种子、收获后萌发的种子及15℃湿藏种子的脱水敏感性变化及其与种子胚轴中可溶性糖含量的关系.15℃湿藏150d及600d使种子脱水敏感性增强,与寡糖含量下降以至消失及寡糖/蔗糖(O/D)之比下降极为一致,虽然花后67d的种子耐脱水能力最强,但此时蔗糖、寡糖含量及寡糖/蔗糖之比却并非最高.虽然15℃湿藏150d的种子萌发4d最耐脱水,但寡糖含量及寡糖/蔗糖之比在萌发3d时均已降至0.结果表明,发育及萌发种子的脱水敏感性与蔗糖、寡糖含量及O/D比无直接关系.     

番木瓜感染环斑花叶病毒后蛋白质和还原糖的变化

本文对番木瓜不同抗性的品种感染环斑花叶病毒后,可溶性蛋白含量和电泳谱带以及还原糖含量的变化规律进行了研究,并分析其与抗性的关系。结果表明,接种处理后,感病品种(岭南种)的可溶性蛋白含量变化率的峰值较抗病品种(穗中红48号)出现早且高;前者出现在接种后24h,高达54.6%,而后者出现在接种后48h,为38.2%。在未接种处理时,感病品种叶片可溶性蛋白谱带较抗病品种多1条;但在接种初期(接种后24h),抗病品种的蛋白谱带比感病品种多1条(Rf值为0.602)。不同抗性品种在接种后的还原糖含量变化也有差异,抗病品种的还原糖含量变化率在接种后48h达到高峰,峰值为12.3%;而感病品种的还原糖含量变化率在接种后都为负值。     

Effect of Photoperiod on Growth of Sugar Beet

Sugar beet grown in controlled environments were given similardaily amounts of visible radiation during three different photoperiodtreatments. Plants were given (a) 115 W m^–2 visible irradiancefrom fluorescent and tungsten lamps for 12 h; (b) 88 W m^–2of the same light for 16 h or (c) 115 W m^–2 from fluorescentand tungsten lamps for 12 h extended to 16 h with low intensity(3 W m^–2) incandescent light from the tungsten lamps only.Plant growth was increased similarly in both long day treatments[(b) and (c)] and dry weights were 25 per cent greater thanin the 12 h photoperiod (a) after 6 weeks. Leaf area was increasedby 18 per cent and net assimilation rate by 10 per cent in the16 h photoperiod at 88 W ^m–2 (b). By contrast, extendingthe photoperiod with 4 h of incandescent light (c) triggereda photomorphogenic increase in leaf expansion which increasedleaf area per plant by 47 per cent and leaf-area ratio by 12per cent.     

On the Numerical Availability of Multiple Comparison Procedures

In the past many multiple comparison procedure were difficult to perform. Usually, such procedures can be traced back to studentized multiple contrast tests. Numerical difficulties restricted the use of the exact procedures to simple, commonly balanced, designs. Conservative approximations or simulation based approaches have been used in the general cases. However, new efforts and results in the past few years have led to fast and efficient computations of the underlying multidimensional integrals. Inferences for any finite set of linear functions of normal means are now numerically feasible. These include all‐pairwise comparisons, comparisons with a control (including dose‐response contrasts), multiple comparison with the best, etc. The article applies the numerical progress on multiple comparisons procedures for common balanced and unbalanced designs within the general linear model.     

Effect of Lime Pretreatment on Granulation of Switchgrass

Densification of switchgrass into consistent and high-density solid feedstock will reduce the cost of transport, handling, and storage to produce fuels and chemicals. Development a novel, low-cost densification technology is critical for reducing the delivered cost of feedstock while improving the bulk flow properties of densified products. In this paper, a novel wet granulation technology was proposed to investigate the effect of lime pretreatment on the production of switchgrass granules. Granulation is a process of agglomerating fine powders by wetting powder surfaces with liquid binders and mild application of shear/vibrating forces. Switchgrass was size reduced into fine powders using a knife mill and pretreated with three lime loading rates (0.05, 0.1, 0.2 g/g of biomass) at 121 °C for 30 min and at room temperature (25 °C) for 72 h. The structural modification of pretreated samples was analyzed by scanning electron microscopy and autofluorescence microscopy. Pretreated samples were granulated using a pan granulator with pre-formulated starch binder. Granules made from 20 % (0.2 g/g of biomass) lime loading rate had significantly higher single granule density and angle of repose with lower binder requirement than that of untreated granules. Lime treatment did not significantly increase the bulk density and hardness of granules. Lime-treated granules had significantly higher ash content and lower gross calorific value than that of untreated granules. In overall, lime treatment was not attractive to produce granules for thermochemical conversion platform, but lime-treated granules could be used to produce liquid biofuels and platform chemicals in biochemical conversion platform.     

糖类在植物组织培养中的效应

糖类是影响植物组织培养成功与否的关键之一。迄今为止,已用于植物组织培养的糖类有50多种。在植物体细胞组织培养中,蔗糖一直作为标准碳源,然而其他糖类物质如：葡萄糖、麦芽糖和山梨醇对植物体细胞培养也产生了一定的影响。在植物花药培养中,蔗糖较好,但应注意麦芽糖对花药培养的促进作用。     

Comparison of Schistosoma mansoni Soluble Cercarial Antigens and Soluble Egg Antigens for Serodiagnosing Schistosome Infections

A Schistosoma mansoni cercarial antigen preparation (cercarial transformation fluid – SmCTF) was evaluated for detection of anti-schistosome antibodies in human sera in 4 collaborating laboratories. The performance of SmCTF was compared with that of S. mansoni egg antigens (SmSEA) in an indirect enzyme-immunoassay (ELISA) antigen assay, the latter being used routinely in 3 of the 4 participating laboratories to diagnose S. mansoni and S. haematobium infections. In the fourth laboratory the performance of SmCTF was compared with that of S. japonicum egg antigens (SjSEA) in ELISA for detection of anti-S. japonicum antibodies. In all 4 laboratories the results given by SmCTF in ELISA were very similar to those given by the antigen preparation routinely used in the respective laboratory to detect anti-schistosome antibodies in human infection sera. In so far as the ELISA results from SmCTF are thus so little different from those given by schistosome egg antigens and also cheaper to produce, the former is a potentially useful new diagnostic aid for schistosomiasis.     

不同刈割程度对紫花苜蓿生长、净光合速率和可溶性糖含量的影响

研究不同刈割程度对紫花苜蓿生长和相关生理指标影响的结果表明：适度刈割可以提高苜蓿的再生能力和生物量;刈割后苜蓿的叶绿素a含量和叶绿素a／b比值及净光合速率均增加;其叶中的可溶性糖含量也增加,轻度刈割的最高,重度刈割的次之,不刈割的最低。     

花生种子耐脱水力的形成与可溶性糖累积的关系

花生胚轴的耐脱水力在40－65DAP的发育后期逐渐增加,同时胚轴还原性糖／非还原性糖比值下降。缓慢干燥可同时诱导35DAP胚轴累积蔗糖与寡糖（水苏糖与棉籽糖）;外源ABA及高渗处理可诱导35DAP离体胚轴累积蔗糖,但不能累积寡糖（水苏糖）。耐脱水胚轴可溶性糖成分的模拟混合物可在水活度0．32及零上温度进入玻璃态;而不耐脱水胚轴的可溶性糖模拟混合物仅在零下温度进入玻璃态。模拟实验证明在干燥状态下可溶性糖与花生2S蛋白结合,并消除了2S蛋白的干燥结晶。