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The aroma compounds of ayran were isolated using solvent-assisted flavor evaporation (SAFE) resulting in a more representative extract of ayran odor compared to liquid–liquid extraction (LLE), solid-phase extraction (SPE), and simultaneous distillation–extraction (SDE). The aromatic extract was subjected to sensory analysis and identified and quantified by gas chromatography–mass spectrometry (GC–MS). A total of 19 volatile compounds were detected that included alcohols, aldehyde, acids, esters, ketones, and terpenes. However, the compounds present at the highest concentrations were ethyl lactate, ethanol, 2,3-butanediol, acetoin, and acetic acid. The key odorants for the ayran drinks were detected using aroma extract dilution analysis (AEDA) and GC–MS–olfactometry (GC–MS–O). A total of 14 aroma-active compounds were determined for the first time. The flavor dilution (FD) factors ranged between 4 and 512 while their odor activity values (OAVs) were from 1.35 to 1126.99. Ethyl lactate (FD of 512 whey/creamy), 2-methylbutanal (FD of 512, fruity), acetoin (FD of 256, buttery creamy), and butanoic acid (FD of 256, cheesy-sweet) were the strongest aroma-active components of the Ayran drink. 相似文献
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Carbon nanotube (CNT), a well-known carbon-based nanomaterial has drawn much attention in many application fields including chemistry in the last few decades. Many researchers and scientists have shown huge interest to improve the extraction methodologies and adopt their applications in combination with chromatography technique. With respect to this, the exceptional applications of CNTs have been introduced as extraction sorbent due to their excellent inborn physical and chemical properties. In particular, CNTs have consistently been used as adsorbents in various techniques including solid-phase micro-extraction, solid-phase extraction, micro dispersive slid phase extraction, magnetic dispersive solid phase extraction, analytes enrichment, sample fractionation and clean-up as well as support for many derivatization reactions. Many research papers have discussed the successful use of CNTs to overcome the limitations of the extraction techniques due to their excellent sorbent capacity. In addition, considering the clear need to make chromatographic technique more successful, the applications of CNTs have been reported in the literatures in details as stationary and pseudo-stationary phases for the separation and extraction of challenging compounds. Because of the higher thermal and chemical stability, CNTs have been anticipated as stationary phase modifier for chromatographic applications to avoid bleeding of the columns and enable the analysis even at very high temperature (1200 °C). In liquid chromatography CNTs have primarily been used in combination with other packing materials (silica) and sometimes incorporated in a porous polymeric monolith. Therefore, the recent utilizations of CNTs as extraction materials and stationary phases have been illustrated in the current review and a table listing the details applications of CNTs in aforementioned field is provided as well. We believe that the review will help researcher to gain vast knowledge about application of carbon nanotubes in the field of separation chemistry. 相似文献
105.
最佳线性多用户信号检测器及其近似求解 总被引:1,自引:0,他引:1
本文提出了平均误比特率最小意义下的最佳线性多用户信号检测器,并给出了求解这种最佳线性多用户信号检测器的近似方法-训练单层感知器不。 相似文献
106.
不规则地形散射场的MEI方法分析 总被引:4,自引:1,他引:3
本文将非均匀、不规则的地形处理成阻抗表面,沿地形表面作共形网格剖分,并利用不变性测试方程法(MEI方法),使截断边界进一步靠近地表,从而减少计算机内存的占用量,使对实际工程中遇到的电大尺寸地形的分析及研究成为可能,文中计算的电大尺寸达180个波长。本文对比了不同电尺寸和地形结构的散射和传播特性计算,并给出几个实用模型的计算结果。 相似文献
107.
多载波频率分集扩展频谱码分多址系统(FD/SSMA)是一种基于多载波传输,与直接序列扩展频谱码分多址系统(DS/SSMA)存在时间-频率对偶关系的扩频多址通信方案。在多径传输信道下,基于FD/SSMA信号的锐自相关和低互相关特性,本文提出FD/SSMA系统可以采用路径分集接收的方案。分析和模拟计算表明,在多径衰落信道下,采用路径分集方案时FD/SSMA系统的性能将得到明显的改善。 相似文献
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Although several molecular markers for human breast cancer exist, their versatility is limited. Here we demonstrate, through a differential proteome analysis utilizing the fluorogenic derivatization-liquid chromatography/tandem mass spectrometry (FD-LC-MS/MS) method between seven cancer cells and one normal cell, that the presence of cooperatively expressed annexin-2 and galectin-1 without tropomyosin-1 in a tissue could be used to diagnose metastatic breast cancer. Interestingly, in a metastatic cancer cell, the expression of the former two together with highly expressed cofilin-1 activates the Rho signal pathway to aggressively form disorganized actin filaments. Despite the excess expression of annexin-2 and galectin-1 in the normal cell, the highly expressed tropomyosin-1 counteracted the activity of cofilin-1 and stabilized the filaments, resulting in the restoration of the disorganization. This phenomenon suggests that enhancement of tropomyosin-1 should be used as therapy for metastatic breast cancer. 相似文献
110.
Ichibangase T Saimaru H Takamura N Kuwahara T Koyama A Iwatsubo T Imai K 《Biomedical chromatography : BMC》2008,22(3):232-234
It has been known that the over-expression of alpha-synuclein, the main protein of Lewy bodies in Parkinson's disease (PD), leads to neurodegeneration in PD models. In this study, the changes in protein expression between the transgenic over-expressing human alpha-synuclein wild type (alpha-synWT) and the control Caenorhabditis elegans were elucidated by fluorogenic derivatization-liquid chromatography/tandem mass spectrometry (FD-LC-MS/MS) proteome analysis, which is a highly selective, sensitive, repeatable and quantitative method for protein identification. Because the alpha-synuclein wild-type worms showed moderate levels of dopamine loss without overt behavioral abnormalities, it was suggested that the changes in proteins in the alpha-synWT are related in the sequence of the formation of Lewy bodies. Among more than 400 protein peaks detected, actin and several ribosomal proteins were identified for the first time as negative markers at early PD stages. Actin was suggested to be one of the important targets in the elucidation of the etiology of neuronal diseases such as PD or other synucleinopathies. 相似文献