对直接标准化算法的改进及其应用

由于各种仪器之间存在差异,主机上建立的定量模型用于从机会导致预测结果出现较大偏差。目前主要通过有标样方法和无标样方法来减小预测偏差。该文对现有标样方法中的直接标准化算法进行改进,在转移矩阵的建立过程中,对从仪器数据矩阵进行主成分分解,以预测均方差为判定标准,确定最终的转移矩阵。并以玉米和烟草数据为对象,测试了该法的有效性。玉米样品含有2种成分:水分和蛋白质;烟草样品含有4种成分:还原糖、总糖、总氮和总碱。结果表明,对于玉米样品中的2种成分,采用改进的方法可显著提高预测的准确度;对于烟草中的4种成分而言,采用改进的方法可获得稳健的预测结果。     

超疏水超亲油玉米秸秆粉油污吸附剂的制备及其在油水分离中的应用

超疏水超亲油材料因其在油水分离等领域有广泛的应用前景而引起人们极大关注。 目前,有很多方法可以用来制备超疏水超亲油材料,但因其过程复杂、成本高、环境适应性差限制了其在实际生产、生活中应用。 本文以玉米秸秆为原料,经TiO₂ 溶胶浸涂并经辛基三甲氧基硅烷修饰后显示出超疏水和超亲油,水滴、油滴在其表面的接触角分别为160°和0°。 研究结果显示,玉米秸秆粉表面的超疏水性源于其表面微纳米复合阶层结构及低表面能化学组成的协同作用。 利用玉米秸秆粉表面的憎水性和亲油性,能将其用于水面油污的吸附和分离,具有分离效率高、稳定性好、可循环利用的优点。 相比于其它材料,以玉米秸秆为原料制备超疏水超亲油的油污吸附剂,原料丰富、成本低、过程简单、易降解、可循环利用,有望在生产、生活中得到应用。     

超高效液相色谱-串联质谱快速检测精米、玉米与土豆样品中噻呋酰胺残留

采用分散固相萃取(QuEChERS)为样品前处理方法,建立了超高效液相色谱-串联质谱(UPLCMS/MS)快速检测精米、玉米和土豆中噻呋酰胺残留的分析方法。样品经乙腈提取,PSA净化,超高效液相色谱分离,电喷雾电离、负离子扫描,三重四极杆串联质谱以多反应监测扫描方式进行检测,基质匹配标准品外标法进行定量分析。结果显示,噻呋酰胺在1.0~1 000μg·L-1范围内呈良好线性(r2=0.999 0)。在0.01~1.0 mg·kg-1加标水平范围内,噻呋酰胺在精米、玉米和土豆中的平均回收率为89.1%~109.3%,相对标准偏差为3.5%~8.7%,检出限(LOD)为0.009~0.015μg·kg-1,定量下限(LOQ)为0.032~0.049μg·kg-1。该方法简便、快速、准确,可用于精米、玉米和土豆中噻呋酰胺农药残留的确证检测。     

玉米须提取液对尿液中草酸钙晶体形成的影响

本文采用X射线衍射(XRD)、红外光谱(FTIR)、扫描电子显微镜(SEM)等方法分析了玉米须提取液对正常人尿液中草酸钙晶体形成的影响,通过电导率法研究了草酸钙晶体生长的动力学过程,以及从生物矿化的角度对玉米须提取液影响尿液中草酸钙晶体的可能机理进行了探讨。由于玉米须提取液中有机酸或多糖的羟基、羰基等通过配位作用与Ca²⁺结合形成可溶性配位化合物,减少了Ca²⁺与Oxa^2-的结合能力,从而抑制了CaOxa的成核和生长。同时,可能由于玉米须提取液中有效成分与二水草酸钙(COD)的吸附点键合,增强了COD晶体在溶液中的热力学稳定性,进而抑制了COD晶体向热力学更稳定态的一水草酸钙(COM)晶体转变。结果显示,这种抑制作用随玉米须浓度增大而增大,且COD晶体尺寸随着玉米须浓度的增大而减小。玉米须抑制COD晶体向COM晶体转变的作用为开发预防和治疗尿结石的药物提供了启示。     

玉米秆粉粒体塑性压缩成型过程的有限元分析

保护环境,节约资源是人类的共识,本以我国丰富的农作物副产物-玉米秸秆为原料,采用弹塑性增量有限元法对玉米秆粉粒体的成型过程进行了研究,有限元计算结果与实验结果比较一致,此研究为玉米秸秆等农林副产物转化为高附加值产品提供了理论依据。     

Ethanol production in a membrane bioreactor

Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5–10 h with ethanol outputs of 10–11.5% (v/v) were obtained when the cell concentration was 60–100 g/L drywt of yeast, equivalent to about 10⁹−10¹⁰ cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady flux of 70 L/(m²·h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity; a clear productstream containing no particulates or yeast cells, which should improve subsequent stripping and distillation operations; and substantially reduced stillage handling. The capital cost of the MRB is $21–$34/(m³·yr) ($0.08–$0.13/[gal·yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance, labor, and cleaning, is $4.5–9/m³ ($0.017–$0.034/gal) of ethanol.     

用逐步二级分辨数学模型预测农业害虫种群动态

文章应用基本Ｆｉｓｈｅｒ准则下逐步二级分辨原理，对山东省临沂市１９６５～１９８６年（１９８０年除外）共２１年的第二代玉米螟虫株率的历史观测数据进行了数量分析，建立了３个逐步二级分辨数学模型。经对历史资料的回报验证，其历史符合率分别为９５．２４％、９２．３１％、１００％。将１９８７年、１９８８年观测数据作为独立样本进行试报，其预报结果与实际一致。     

Sorption of aliphatic ketones from aqueous solutions by starch cryotextures

Capillary gas chromatography was applied to study the sorption of aliphatic ketones (C₆—C₁₁), including metamers, from aqueous solutions by corn starch cryotextures. The amount of ketones sorbed by cryotextures depends linearly on their concentrations in the initial sol. Equations describing the concentration dependence of sorption were proposed. The shape of sorption isotherms reflects the strength of sorption. The binding constants and the number of binding sites were determined for weakly sorbed ketones. The length of alkyl substituent and the position of the functional group are the crucial factors governing the sorption of ketones under conditions of excess binding sites. It was found that the degree of sorption increases with an increase in the carbon chain length from 6 to 9 carbon atoms. The presence of cooperation of binding sites for ketone sorption by cryotextures was demonstrated. The major part of ketones is sorbed irreversibly. This fact points to the formation of supramolecular complexes. Ketones with lower molecular masses are better sorbed by cryotextures than by native starch grains.     

Cellulase retention and sugar removal by membrane ultrafiltration during lignocellulosic biomass hydrolysis

Technologies suitable for the separation and reuse of cellulase enzymes during the enzymatic saccharification of pretreated corn stover are investigated to examine the economic and technical viability of processes that promote cellulase reuse while removing inhibitory reaction products such as glucose and cellobiose. The simplest and most suitable separation is a filter with relatively large pores on the order of 20–25 mm that retains residual corn stover solids while passing reaction products such as glucose and cellobiose to form a sugar stream for a variety of end uses. Such a simple separation is effective because cellulase remains bound to the residual solids. Ultrafiltration using 50-kDa polyethersulfone membranes to recover cellulase enzymes in solution was shown not to enhance further the saccharification rate or overall conversion. Instead, it appears that the necessary cellulase enzymes, including β-glucosidase, are tightly bound to the substrate; when fresh corn stover is contacted with highly washed residual solids, without the addition of fresh enzymes, glucose is generated at a high rate. When filtration was applied multiple times, the concentration of inhibitory reaction products such as glucose and cellobiose was reduced from 70 to 10 g/L. However, an enhanced saccharification performance was not observed, most likely because the concentration of the inhibitory products remained too high. Further reduction in the product concentration was not investigated, because it would make the reaction unnecessarily complex and result in a product stream that is much too dilute to be useful. Finally, an economic analysis shows that reuse of cellulase can reduce glucose production costs, especially when the enzyme price is high. The most economic performance is shown to occur when the cellulase enzyme is reused and a small amount of fresh enzyme is added after each separation step to replace lost or deactivated enzyme.     

我国燃料乙醇生产技术的现状与展望

概述了目前国内外燃料乙醇产业现状.结合我国中粮生化能源(肇东)有限公司燃料乙醇装置,重点介绍了我国目前的燃料乙醇生产工艺技术水平、特点以及与国外的差距.本文从提高燃料乙醇生产技术水平、降低生产成本、寻找廉价非粮原料和开发新生产工艺等几个方面,对燃料乙醇生产技术的发展作了展望.