Synthesis,Characterization, and Catalytic Behavior of Bamboo Rice Husk Ash

In this paper, we report the use of bamboo rice husk ash as an efficient, greener, reusable, and biodegradable heterogeneous catalyst for the synthesis of tetrahydro‐4H ‐chromene‐3‐carbonitriles via the one‐pot three‐component reaction of malononitrile with aromatic aldehydes and dimedone or 1,3‐cyclohexanedione. The formation of bamboo rice husk ash‐silica has been confirmed by several analytical techniques.     

A Dilute and Shoot Strategy for Determining Alternaria Toxins in Tomato-Based Samples and in Different Flours Using LC-IDMS Separation

Alternaria toxins are emerging mycotoxins whose regulation and standardization are in progress by the European Commission and the European Committee for Standardization. This paper describes a dilute and shoot approach to determine five Alternaria toxins in selected food samples using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The strategy involves sample extraction with acidified aqueous methanol, followed by a solvent change accomplished via sample evaporation and reconstitution. The quantification is based on isotope dilution, applying all corresponding isotopically labeled internal standards to compensate possible matrix effects of the analysis. The main advantages of the present method over other existing methods includes simple and effective sample preparation, as well as detection with high sensitivity. The five-fold sample dilution can decrease matrix effects, which were evaluated with both external and internal standard methods. The results demonstrated a limit of quantification lower than 1.0 µg/kg for all five analytes for the first time. The newly presented method showed acceptable accuracy (52.7–111%) when analyzing naturally contaminated and spiked standard samples at the described levels. The method was validated for tomato-based and flour samples (wheat, rye, and maize). The absolute recovery ranged from 66.7% to 91.6% (RSD < 10%). The developed method could be an alternative approach for those laboratories that exclude sample cleanup and pre-concentration of state-of-the-art instruments with enhanced sensitivity.     

A 12/7-approximation algorithm for the discrete Bamboo Garden Trimming problem

We study the discrete Bamboo Garden Trimming problem (BGT), where we are given n bamboos with different growth rates. At the end of each day, one can cut down one bamboo to height zero. The goal in BGT is to make a perpetual schedule of cuts such that the height of the tallest bamboo ever is minimized. Here, we improve the current best approximation guarantee by designing a 12/7-approximation algorithm.     

A universal kinetic equation for characterising the fractal nature of delignification of lignocellulosic materials

A kinetic model was developed, based on the power law of growth and Avrami’s nuclei growth concepts, to describe the heterogeneous nature of pulping kinetics, taking into account the effects of chemical concentration and temperature. The general form of the kinetic equation is first order with a time-dependent rate coefficient. The model was statistically tested using published data obtained from delignification of lignocellulosic materials (hemp woody core, giant reed, wheat straw, cottonwood, bamboo and flax fibres). The activation energies of the delignification range from 71 to 136 kJ/mol. The p-values obtained from the regression analysis are significantly small indicating that all the estimates of the model parameters were significant with very high levels of confidence. The correlation coefficients R ² for these models range from 0.76 to 0.98.     

微波消解ICP-MS测定鲜竹笋中7种微量元素

建立同时检测鲜竹笋中铬、铜、锌、砷、镉、汞、铅等7种元素的分析方法。竹笋样品在硝酸介质中经微波消解,用电感耦合等离子体质谱(ICP-MS)检测,全定量法采集数据。校准曲线线性良好,相关系数在0.9937—1.0000之间;检出限为0.005—0.202μg/L;加标回收率在88.96%—110.5%;精密度RSD小于6.09%;国家标准样品西红柿叶(GSBZ51001-94)中几种元素的测定值都在标准范围内。该方法具有灵敏、可靠、快速、准确等优点,适用于竹笋中微量元素的分析测定。     

Quantitative determination of BMS-378806 in human plasma and urine by high-performance liquid chromatography/tandem mass spectrometry

BMS-378806 is a human immunodeficiency virus (HIV) entry inhibitor that is being developed for the oral treatment of HIV infection. Human plasma and urine LC/MS/ MS methods have been developed and validated for the quantitation of BMS-378806. For human plasma method, methyl t-butyl ether was used to extract BMS-378806 from plasma in a 96-well format, and the organic layers were dried down and then reconstituted for the injection, while a dilute-and-shoot approach was used for human urine method in a 96-well format. Chromatographic separation was achieved isocratically on a Phenomenex C18 (2) Luna column (2 x 50 mm2, 5 microm). The mobile phase contained 60:40 v/v of 0.1% formic acid in water and ACN. Detection was by positive ion electrospray MS/MS. The standard curves ranged from 1.25 to 1000 ng/mL for the plasma assay and from 10 to 5000 ng/mL for the urine assay. The curves were fitted to a 1/x2 weighted quadratic regression model for both methods. The validation results demonstrated that both methods had satisfactory precision and accuracy across the calibration ranges. The methods were applied to the analysis of human plasma and urine samples from a single ascending dose clinical study to assess the pharmacokinetics of the drug. The pharmacokinetic analysis results indicated the absorption and disposition of the drug was rapid. The systemic exposure of BMS-378806 was generally dose proportional among the doses from 100 to 1200 mg, but not dose proportional to 1600 mg. There were modest increases in the systemic exposure when the drug was given with food or given as a solution formulation. Renal excretion was not a substantial elimination pathway of the drug. BMS378806 was safe and well tolerated over a dose range of 100-1600 mg administered as a single oral dose.     

竹炭为高效吸附剂的固相萃取分析环境水样中的痕量三氯生

建立了一种由竹炭作为固相萃取高效吸附剂富集环境水样中痕量三氯生的新方法. 研究并优化了几个影响富集效率的参数. 在优化条件下, 三氯生的检测限为0.08 μg/L, 在1～100 μg/L 范围内有良好的线性关系, 相对标准偏差为2.9% (n=7). 方法可应用于实际废水样品的分析.     

Sensitive determination of phenols in environmental water samples with SPE packed with bamboo carbon prior to HPLC

Bamboo carbon, an inexpensive, readily available material, has attracted great attention in recent years because of adsorptive properties. In this paper, the potential of bamboo carbon as a SPE adsorbent for the determination of phenols, was investigated. Phenols are important environmental contaminants that may adversely affect human health. Parameters influencing extraction efficiency, including type of eluent, eluent volume, amount of adsorbent, as well as sample pH, volume, and flow rate were investigated and optimized. The optimized results exhibited excellent linear relationships between peak area and phenol concentrations over the range of 2.0–100 ng/mL, with precision between 2.2–7.2%. The LODs were 0.06–0.4 ng/mL for the eight phenols tested. The proposed method has been successfully applied to the analysis of several real‐world environmental water samples. These results indicate that bamboo carbon may be used as a novel SPE adsorbent for the concentration and determination of phenols in real environmental water samples.     

基于自编码网络流形学习的毛竹笋不溶性膳食纤维含量红外光谱建模

提出了一种结合自编码网络(AN)流形学习和偏最小二乘(PLS)法的红外光谱建模方法AN-PLS。AN-PLS方法首先用AN算法对红外光谱数据进行非线性降维,再结合PLS建立回归模型。利用该方法建立了毛竹笋中不溶性膳食纤维含量的近红外光谱和中红外光谱回归模型。结果表明,用AN-PLS方法建立的回归模型,比用其他常用光谱数据预处理方法结合PLS及用单独PLS算法建立的模型具有更小的预测均方根误差RMSEP和更高的决定系数R2,因此,AN-PLS具有较优的建模与预测能力,利用近红外光谱和中红外光谱技术结合AN-PLS建模,可实现毛竹笋中不溶性膳食纤维含量的准确测量。     

热处理竹材的化学成分傅里叶变换红外光谱分析

化学热处理是实现可再生木质生物能源中纤维素高效利用及半纤维素糖化转换的关键步骤。通过预处理过程可以快速去除难溶木质素,实现细胞壁中半纤维素的物理化分离,使得植物细胞壁中化学成分发生变化,从而增加木质纤维素的产出量。以硫酸(H₂SO₄)、稀碱(NaOH)及甘油(glycerol)为预处理介质,采用不同的热处理温度(硫酸(H₂SO₄)、稀碱(NaOH)热处理温度为117和135 ℃;甘油(glycerol)热处理温度为117 ℃)),对竹材处理前后的主要化学组分进行对比分析,并通过傅里叶变换红外光谱进一步证实化学热处理前后竹材化学组分的变化,以获得不同的化学热处理介入下竹材化学成分转换的主要变化规律和机理。结果表明：热化学处理后竹材的纤维素产出量明显增加。纤维素得率及木质素的去除率在不同的处理介质条件下的变化规律为,稀碱(NaOH)处理效果优于稀酸(H₂SO₄)和甘油(glycerol);此外,在相同介质条件下135 ℃热处理效果比117 ℃热处理效果显著。对于不同处理条件的半纤维素的降解程度大小变化结果与此相同。通过红外光谱分析可知,热处理后纤维素环状C-O-C不对称伸缩振动峰出现峰值分解,半纤维素的红外吸收特征峰出现明显陡降变化,木质素苯环特征吸收峰明显减弱,证明纤维素产出量明显增加,半纤维素降解趋势明显,木质素去除效果良好。傅里叶红外变换光谱分析结果与标准测定结果一致。