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1.
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices.  相似文献   
2.
Scope : The proliferation and differentiation of intestinal stem cells (ISCs) are the basis of intestinal renewal and regeneration, and gut microbiota plays an important role in it. Dietary nutrition has the effect of regulating the activity of ISCs; however, the regulation effect of α-linolenic acid (ALA) has seldom been reported. Methods and Results : After intervening mice with different doses of ALA for 30 days, it is found that ALA (0.5 g kg?1) promotes small intestinal and villus growth by activating the Wnt/β-catenin signaling pathway to stimulate the proliferation of ISCs. Furthermore, ALA administration increases the abundance of the Ruminococcaceae and Prevotellaceae, and promotes the production of short-chain fatty acids (SCFAs). Subsequent fecal transplantation and antibiotic experiments demonstrate that ALA on the proliferation of ISCs are gut microbiota dependent, among them, the functional microorganism may be derived from Ruminococcaceae. Administration of isobutyrate shows a similar effect to ALA in terms of promoting ISCs proliferation. Furthermore, ALA mitigates 5-fluorouracil-induced intestinal mucosal damage by promoting ISCs proliferation. Conclusion : These results indicate that SCFAs produced by Ruminococcaceae mediate ALA promote ISCs proliferation by activating the Wnt/β-catenin signaling pathway, and suggest the possibility of ALA as a prebiotic agent for the prevention and treatment of intestinal mucositis.  相似文献   
3.
艾俊哲  谢郢  周可心  池伸 《广东化工》2022,49(3):186-188
胶体电泳速度测定实验是大学物理化学实验中一个重要的综合性教学实验.本文针对该实验中存在半透膜制作不稳定、渗析时间过长、电泳现象不明显、胶体/辅助液界面不清晰等问题.从胶体浓度、电极电压、半透膜、稳定剂四个方面进行了改进.结果表明,胶体界面移动距离,胶体/辅助液界面的清晰程度都有很大的改善,大大提高了实验的体验感.  相似文献   
4.
Oil, accounting for 45% of almonds, is easily oxidised and can further induce the protein oxidation to reduce their quality. Structure and physicochemical properties of amandin, the main water-soluble protein in almonds, inducing oxidation by malondialdehyde (MDA) were investigated. The results showed that the content of carbonyl group increased from 5.23 to 33.25 nmol mg−1 of protein with the increase in MDA concentration (P < 0.05). However, the sulphydryl content, surface hydrophobicity, particle size and the absolute value of ζ-potential first increased and then decreased. Fourier-transformed infrared spectroscopy (FT-IR) confirmed that the structure of amandin changed from order to disorder. Fluorescence spectroscopic analysis revealed that mild oxidation (0–0.1 mmol L−1 MDA) exposed hydrophobic groups of the protein. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) suggested that protein oxidation promoted crosslinking between protein molecules. Furthermore, protein oxidation markedly declined the total amino acid content of amandin (P < 0.05). In conclusion, MDA oxidation changed the structure and amino acid content of amandin, and caused the protein aggregate and crosslink through hydrophobic interaction and electrostatic interaction.  相似文献   
5.
A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen. The physical-chemical properties of Cu-MgAlO catalysts were studied, and the results indicated that the copper component had been successfully introduced into the hydrotalcite unit layer structure. The catalytic reaction results showed that copper as the active species could activate C-H bond and effectively promote the decomposition of cyclohexyl hydroperoxide (CHHP) to the mixture of cyclohexanol and cyclohexanone (KA oil). 8.3% of cyclohexane conversion and 82.9% of selectivity for KA oil were obtained over 9%Cu-MgAlO catalyst at 150℃ with 0.6 MPa of oxygen pressure for 2 h. Especially, its catalytic performance was still stable after five runs.  相似文献   
6.
7.
Electrochemical CO2 reduction reaction (CO2RR) is an efficient way in the utilization of CO2. In this work, single transition-metal (TM) atom (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) anchored on two-dimensional (2D) Ti2CN2 are designed for CO2RR using density-functional-theory (DFT) calculation. We show that Ti2CN2 serves as an excellent substrate to support single atom catalysts (SACs), compared to Ti2CO2 and Ti2CF2. We find that the Sc, Ti and V supported on Ti2CN2 show high catalytic activities to produce CO with a low overpotential of 0.37, 0.27, and 0.23 eV, respectively. Differently, the Mn and Fe on Ti2CN2 are catalytically active for the production of HCOOH with a low overpotential of 0.32 and 0.43 eV, respectively. We further show that the negatively charged TM-Ti2CN2 can capture and activate CO2 more effectively, and the catalytic activity and selectivity can be significantly tuned by injecting extra electrons.  相似文献   
8.
随着风电在电力系统中渗透率的提高,调度时段内的风电出力波动越发剧烈,可能导致时段内爬坡不足,威胁电力系统在时段内的运行安全.针对这一问题,提出计及超分辨率风电出力不确定性的连续时间鲁棒机组组合模型和求解算法,该方法充分考虑时段内风电出力变化,给出对超分辨率风电出力不确定性鲁棒的调度方案.首先,基于连续时间建模方法,建立连续时间鲁棒经济调度模型,并对其中的超分辨率不确定性模型进行分析;然后,通过解空间变换,将代数空间的优化问题转换为易求解的函数空间优化问题,并通过列和约束生成算法进行求解,计算结果还原到代数空间;最后,通过算例结果验证了所提方法能够充分计及超分辨率风电出力的不确定性,提高调度方案的鲁棒性.  相似文献   
9.
本文归纳了遥感技术在重金属污染土壤监测中的应用研究现状,分析了适合遥感监测的土壤重金属污染修复技术,并论述了结合修复技术对土壤重金属污染修复效果进行监测的研究,进而提出了当前土壤重金属污染修复遥感监测研究的不足与解决方法,最后展望了遥感技术在土壤重金属污染修复方面的应用前景.分析表明:土壤中重金属含量反演研究集中在可见光-红外遥感与微波监测,其中可见光-红外遥感反演已较为成熟,微波监测的研究有待加强,两者结合反演的研究还处于起步阶段;在土壤重金属污染修复方法方面,生物修复及其联合修复(生物间联合修复)的过程适合遥感监测;在遥感监测土壤修复效果的过程中,对植物性状的监测多于动物、微生物监测研究;同时,对于修复效果基本体现在土壤与植物表现出的特性.目前,土壤重金属污染修复遥感监测研究涉及多源数据的使用以及多学科交叉研究,且平台较为单一,致使整体研究还处于相对松散的状态.未来,解决遥感技术在土壤修复中的应用不足问题,依赖于精度不断提高的遥感数据、土壤修复体系完善等方面的进步.  相似文献   
10.
金属矿石资源特别是贫、细、复杂矿物资源的综合回收技术日渐发展,具备来源广泛、无毒(或低毒)、低耗等特点的微生物药剂在选矿中的应用引起许多人的重视。微生物在选矿中的细菌浸出已经早有应用,而微生物作为浮选药剂的研究有望将其工业化以替代或部分替代化学药剂。本文结合国内外相关研究结果,概述了微生物作为絮凝剂、捕收剂及抑制剂等浮选药剂的应用研究进展,并对微生物浮选药剂的作用机理以及发展趋向进行了总结。  相似文献   
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