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111.
112.
González-Sáiz JM Esteban-Díez I Sánchez-Gallardo C Pizarro C 《Analytical and bioanalytical chemistry》2008,391(8):2937-2947
Wastes and by-products of the onion-processing industry pose an increasing disposal and environmental problem and represent
a loss of valuable sources of nutrients. The present study focused on the production of vinegar from worthless onions as a
potential valorisation route which could provide a viable solution to multiple disposal and environmental problems, simultaneously
offering the possibility of converting waste materials into a useful food-grade product and of exploiting the unique properties
and health benefits of onions. This study deals specifically with the second and definitive step of the onion vinegar production
process: the efficient production of vinegar from onion waste by transforming onion ethanol, previously produced by alcoholic
fermentation, into acetic acid via acetic fermentation. Near-infrared spectroscopy (NIRS), coupled with multivariate calibration
methods, has been used to monitor the concentrations of both substrates and products in acetic fermentation. Separate partial
least squares (PLS) regression models, correlating NIR spectral data of fermentation samples with each kinetic parameter studied,
were developed. Wavelength selection was also performed applying the iterative predictor weighting–PLS (IPW-PLS) method in
order to only consider significant spectral features in each model development to improve the quality of the final models
constructed. Biomass, substrate (ethanol) and product (acetic acid) concentration were predicted in the acetic fermentation
of onion alcohol with high accuracy using IPW-PLS models with a root-mean-square error of the residuals in external prediction
(RMSEP) lower than 2.5% for both ethanol and acetic acid, and an RMSEP of 6.1% for total biomass concentration (a very satisfactory
result considering the relatively low precision and accuracy associated with the reference method used for determining the
latter). Thus, the simple and reliable calibration models proposed in this study suggest that they could be implemented in
routine applications to monitor and predict the key species involved in the acetic fermentation of onion alcohol, allowing
the onion vinegar production process to be controlled in real time. 相似文献
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亚甲基蓝与鲱鱼精DNA相互作用的光谱法研究 总被引:1,自引:0,他引:1
以吖啶橙(AO)作为光谱探针, 采用UV和荧光光谱等方法研究了亚甲基蓝(MB)与鲱鱼精DNA的作用机制. 确定了在低浓度MB时, MB与DNA以嵌插方式作用; 而在高浓度MB时, MB与DNA之间为混合作用方式. 结合比n(MB)∶n(DNA)=10∶1, 结合常数 =2.46×105 L•mol-1, MB-DNA复合物的表观摩尔吸光系数ε=5.70×106
L•mol-1•cm-1. 同时研究了酸度和温度等对MB与DNA相互作用的影响, 热力学研究推导了MB结合DNA为焓驱动反应. 相似文献
115.
Gene expression profiles, which represent the state of a cell at a molecular level, have great potential as a medical diagnosis tool. Compared to the number of genes involved, available training data sets generally have a fairly small sample size in cancer type classification. These training data limitations constitute a challenge to certain classification methodologies. A reliable selection method for genes relevant for sample classification is needed in order to speed up the processing rate, decrease the predictive error rate, and to avoid incomprehensibility due to the large number of genes investigated. Improved binary particle swarm optimization (IBPSO) is used in this study to implement feature selection, and the K-nearest neighbor (K-NN) method serves as an evaluator of the IBPSO for gene expression data classification problems. Experimental results show that this method effectively simplifies feature selection and reduces the total number of features needed. The classification accuracy obtained by the proposed method has the highest classification accuracy in nine of the 11 gene expression data test problems, and is comparative to the classification accuracy of the two other test problems, as compared to the best results previously published. 相似文献
116.
Improved ion optics for introduction of ions into a 9.4‐T Fourier transform ion cyclotron resonance mass spectrometer 下载免费PDF全文
Yu Chen Nathan K. Kaiser Xibei Dang Yehia M. Ibrahim Randolph V. Norheim Gordon A. Anderson Richard D. Smith Alan G. Marshall 《Journal of mass spectrometry : JMS》2015,50(1):280-284
Enhancements to the ion source and transfer optics of our 9.4 T Fourier transform ion cyclotron resonance (ICR) mass spectrometer have resulted in improved ion transmission efficiency for more sensitive mass measurement of complex mixtures at the MS and MS/MS levels. The tube lens/skimmer has been replaced by a dual ion funnel and the following octopole by a quadrupole for reduced ion cloud radial expansion before transmission into a mass‐selective quadrupole. The number of ions that reach the ICR cell is increased by an order of magnitude for the funnel/quadrupole relative to the tube lens/skimmer/octopole. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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118.
A novel approach of head-space single-drop micro-extraction applied to the determination of ethanol in wine is presented. For the first time, the syringe of an automated syringe pump was used as an extraction chamber of adaptable size for a volatile analyte. This approach enabled to apply negative pressure during the enrichment step, which favored the evaporation of the analyte. Placing a slowly spinning magnetic stirring bar inside the syringe, effective syringe cleaning as well as mixing of the sample with buffer solution to suppress the interference of acetic acid was achieved. 相似文献
119.
120.
《Analytical letters》2012,45(2):257-280
Abstract A procedure for selection of wavelength range and number of factors to be used in partial least square calibration that involves the calculation of prediction residual sum of squares (PRESS) in different conditions is proposed. The best model takes into account the minimum PRESS value that does not show significant differences with respect to the corresponding model with fewer factors. The ability of the proposed method to minimize errors in partial least squares (PLS) prediction is demonstrated by applying it to the resolution of phenytoine (DPH) and phenobarbital (PB) binary mixtures with errors less than 2.8%; the results are compared with those obtained using another wavelength selection procedure. The ensuing method, which was validated by high performance liquid chromatography (HPLC), also gives good results with real samples (pharmaceutical preparations). 相似文献