Reaction kinetics of stover liquefaction in recycled stover polyol

The purpose of this research was to study the kinetics of liquefaction of crop residues. The liquefaction of corn stover in the presence of ethylene glycol and ethylene carbonate using sulfuric acid as a catalyst was studied. It was found that the liquefaction yield was a function of ratio of solvent to corn stover, temperature, residence time, and amount of catalyst. Liquefaction of corn stover was conducted over a range of conditions encompassing residence times of 0–2.5 h, temperatures of 150–170°C, sulfuric acid concentrations of 2–4% (w/w), and liquefaction reagent/corn stover ratio of 1–3. The liquefaction rate constants for individual sets of conditions were examined using a first-order reaction model. Rate constant increased with the increasing of liquefaction temperature, catalyst content, and liquefaction reagent/corn stover ratio. Reuse of liquefied biomass as liquefying agent was also evaluated. When using recycled liquefied biomass instead of fresh liquefaction reagent, the conversion is reduced. It appeared that 82% of liquefaction yield was achieved after two times of reuse.     

高效液相色谱串联质谱法测定玉米及植株中胺唑草酮及其代谢物

建立了同时测定玉米及玉米植株中胺唑草酮及其两个代谢物残留量的液相色谱串联质谱分析方法.样品采用乙腈提取,石墨化炭黑(GCB)和C18分散固相萃取净化,以甲醇-5 mmol/L乙酸铵溶液为流动相,液相色谱串联质谱分析测定.在1 ～ 1000 μg/L的浓度范围内,3种目标化合物的响应值与浓度呈良好的线性关系,在3个添加水平下,玉米籽粒及植株中胺唑草酮及其代谢物的平均添加回收率为85％～111％,相对标准偏差(RSD)为2.3％～11.0％.方法定量限(LOQ)为5μg/kg.采用本方法监测15例市售玉米样品,样品中目标物均低于方法检出限.本方法简单,快速,灵敏度高,可完全满足国外胺唑草酮相关现行法规的限量要求.     

Determination of betaines in vegetable oils by capillary electrophoresis tandem mass spectrometry--application to the detection of olive oil adulteration with seed oils

A CE–tandem mass spectrometry (MS²) methodology enabling the simultaneous determination of betaines (glycine betaine, trigonelline, proline betaine and total content of carnitines) in vegetable oils was developed. Betaines were derivatized with butanol previous to their baseline separation in 10 min using a 0.1 M formic acid buffer at pH 2.0. Ion trap conditions were optimized in order to maximize the selectivity and sensitivity. Analytical characteristics of the proposed method were established by evaluating its selectivity, linearity, precision (RSDs ranged from 4.8 to 10.7% for corrected peak areas) and accuracy by means of recovery studies (from 80 to 99%) and LODs and LOQs at 0.1 ppb level. The method was applied for the determination of the selected betaines in seed oils and extra virgin olive oils. MS² experiments provided the fingerprint fragmentation for the betaines identified in vegetable oils. In extra virgin olive oils, carnitines were not detected, making it possible to propose them as a feasible novel marker for the detection of adulterations of olive oils. Application of the developed method for the analysis of different mixtures of extra virgin olive oil with seed oil (between 2 and 10%) enabled the detection and quantitation of the total content of carnitines. The results obtained show the high potential of the developed method for the authentication and quality control of olive oils.     

Application of lag-k autocorrelation coefficient and the TGA signals approach to detecting and quantifying adulterations of extra virgin olive oil with inferior edible oils

The combination of lag-k autocorrelation coefficients (LCCs) and thermogravimetric analyzer (TGA) equipment is defined here as a tool to detect and quantify adulterations of extra virgin olive oil (EVOO) with refined olive (ROO), refined olive pomace (ROPO), sunflower (SO) or corn (CO) oils, when the adulterating agents concentration are less than 14%. The LCC is calculated from TGA scans of adulterated EVOO samples. Then, the standardized skewness of this coefficient has been applied to classify pure and adulterated samples of EVOO. In addition, this chaotic parameter has also been used to quantify the concentration of adulterant agents, by using successful linear correlation of LCCs and ROO, ROPO, SO or CO in 462 EVOO adulterated samples. In the case of detection, more than 82% of adulterated samples have been correctly classified. In the case of quantification of adulterant concentration, by an external validation process, the LCC/TGA approach estimates the adulterant agents concentration with a mean correlation coefficient (estimated versus real adulterant agent concentration) greater than 0.90 and a mean square error less than 4.9%.     

玉米叶片重金属铅含量的SVD-ANFIS高光谱预测模型

重金属污染农作物后可通过食物链进入人体从而严重危害身体健康。如何快速准确地监测农作物中重金属含量已成为当今生态与粮食安全等领域的重要研究内容。常规的生化监测方法存在操作繁琐、过程长、具有破坏性等缺点,而高光谱遥感具有光谱分辨率高、信息量大、生化反演能力强、方便快捷、对监测对象无损伤等优势,因此利用高光谱遥感技术监测农作物中重金属含量已成为遥感领域的热点研究之一。以不同浓度Pb(NO₃)₂溶液胁迫下盆栽玉米植株为研究对象,基于不同铅离子(Pb2+)胁迫梯度下玉米叶片的反射光谱及其中Pb2+含量的测定数据,结合奇异值分解(SVD)理论和自适应模糊神经网络推理系统(ANFIS)结构,建立了一种Pb2+含量预测的SVD-ANFIS模型。首先对各胁迫梯度下玉米的老叶(O)、中叶(M)、新叶(N)三种叶片的反射光谱数据进行SVD处理,获取原始光谱信息的奇异值;然后选择O,M和N叶片对应的奇异值来寻求ANFIS结构的最佳输入组合,最终选定O-M（双输入）组合作为ANFIS结构的输入量,通过训练和学习获得最优模糊规则库后,ANFIS结构的输出量即为叶片中Pb2+含量,从而实现了SVD-ANFIS模型的预测性能。研究结果表明,该模型的输出误差值较小,精度较高,在模糊训练过程中隶属函数选为钟型函数时预测效果最佳。利用多参数的反向传播(BP)神经网络预测模型对SVD-ANFIS模型的预测优越性进行验证时,得到BP模型和SVD-ANFIS模型的决定系数(R2)分别为0.977 6和0.988 7,均方根误差(RMSE)分别为2.455 9和0.601 3,可见SVD-ANFIS模型的拟合度更高,预测效果更好。同时选取不同年份的Pb污染玉米叶片等光谱数据对SVD-ANFIS模型进行可行性检验,其R2和RMSE分别为0.986 4和0.887 4,说明SVD-ANFIS模型能较好的用于玉米叶片中Pb2+含量预测且具有较高的鲁棒性,可作为预测玉米叶片中重金属含量的一种方法。     

极低频高压脉冲电场对萌发玉米种子超弱发光的影响

生物超弱发光是来自细胞的电磁信号,在揭示电磁生物学效应的机理研究中具有重要作用.为了研究极低频脉冲电场生物学效应及其机理,采用基于玉米细胞电位波动频率的1 Hz极低频高压脉冲电场处理萌发玉米种子,结果发现玉米种子的萌发过程明显加快,根长和芽长均有显著增长.对萌发种子的自发发光和延迟发光的测量结果显示,1 Hz极低频高压脉冲电场对萌发过程中玉米种子的自发发光和延迟发光积分强度都有明显的促进作用,表明1 Hz极低频高压脉冲电场加速了玉米种子萌发过程中的DNA合成和细胞代谢.     

复合酶耦合酶解酸处理后玉米秸秆的研究

以玉米秸秆为研究对象,经过2%硫酸预处理后,利用果胶酶、β-葡萄糖苷酶、纤维素酶三种酶协同酶解,以提高玉米秸秆的酶解产糖量。结果表明:当酶解时间为48h,果胶酶、β-葡萄糖苷酶、纤维素酶分别为45U/mL、30U/mL、60U/mL时,葡萄糖、木糖和酶水解得率分别为67.83%、3.25%、73.65%,相比纤维素酶单一酶解的葡萄糖、木糖和酶水解得率分别提高了65.04%、20.82%、65.06%。分步糖化发酵5天后,相比单一酶解发酵乙醇含量提高了72.5%。说明利用三种酶复合处理,能明显提高酶解产糖量。研究结果为玉米秸秆转化为可发酵糖技术的研究提供重要参考。     

The effect of ultrasound on the structure and properties of the water-soluble corn hull heteroxylan

Ultrasonic irradiation of a water-soluble corn hull xylan fraction in neutral and alkaline aqueous medium has been found to produce significant changes in its molecular properties. Degradation is first manifested by a decrease in the large molar mass component under generation of polymer chains with about the same size as those of the main molar mass component. The latter is slightly shifted to the lower molar mass region only at stronger irradiation conditions. Ultrasonication of the xylan in neutral aqueous medium at high ultrasound power and/or long irradiation caused no significant changes in its sugar composition, primary structure and viscoelastic properties.     

Statistical Optimization for Succinic Acid Production from E. Coli in a Cost-Effective Medium

Response surface methodology (RSM) was employed for optimization of medium components and cultural parameters in cost effective cane molasses based medium for attaining high yield of succinic acid. The important factors obtained by “one-variable-at-a-time-approach” (cane molasses, corn steep liquor, sodium carbonate, and inoculum density) were further optimized by RSM. The optimum values of the parameters obtained through RSM (cane molasses 12.5%, corn steep liquor 7.5%, and sodium carbonate 25 mM) led to almost double yield of succinic acid (15.2 g/l in 36 h) as against “one-variable-at-a-time-approach” (7.1 g/l in 36 h) in 500-ml anaerobic bottles containing 300-ml cane molasses based medium. Subsequently, in 10-l bioreactor succinic acid production from Escherichia coli was further improved to 26.2 g/l in 30 h under conditions optimized through RSM. This fermentation-derived succinic acid will definitely help in replacing existing environmentally hazardous and cost-intensive chemical methods for the production of succinic acid.     

基于优化面积光谱指数的玉米叶片叶绿素值估测

综合使用光谱技术对作物养分进行实时、有效诊断,有助于作物的精准管理、保障产量和减少环境污染,提高肥料利用率,并且为定量估测作物生化组分状况提供了一种新的途径.光谱指数是进行作物叶片叶绿素实时估测的重要指标,然而由于受到环境条件及内在生化成分的影响,估测结果不尽满意.为了进一步提高光谱指数在估测作物叶片叶绿素含量时的抗干...