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1.
According to the Food and Agriculture Organization of the United Nations, approximately 1.3 billion tons of food is wasted each year, equivalent to approximately one-third of world production. Agri-food wastes are the source of proteins, carbohydrates, lipids, and other essential minerals that have been exploited for value-added products by the development of biorefineries and sustainable business as important elements of circular economies. The innovation and materialization of these types of processes, including the use of disruptive technologies on microbial bioconversion and enzyme technology, such as nanotechnology, metabolic engineering, and multi-omics platforms, increase the perspectives on the waste valorization process. Lignocellulolytic enzymes, pectinases, and proteases are mainly used as catalyzers on agri-food waste treatment, and their production in house might be the trend in near future for agro-industrial countries. Another way to transform the agri-food wastes is via aerobic or anaerobic microbial process from fungal or bacterial cultures; these processes are the key to produce waste enzymes.  相似文献   
2.
锡二硫族化合物可以通过改变硫和硒的含量来连续调控三元合金材料的带隙、载流子浓度等物理化学性质,在电子和光电子器件应用上具有巨大的潜力。本文采用化学气相沉积(CVD)技术可控地制备了不同元素组分的SnSxSe2-x(x=0,0.2,0.5,0.8,1.0,1.2,1.5,1.8,2.0)单晶纳米片。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、能量色散X射线光谱(EDS)、透射电子显微镜(TEM)以及拉曼光谱等手段对SnSxSe2-x纳米片进行了综合表征。结果表明本方法成功实现了元素百分比可调的SnSxSe2-x单晶纳米片的可控制备。重点研究了依赖于元素百分比的SnSxSe2-x的拉曼特征谱,实验结果与基于密度泛函理论(DFT)的第一性原理计算得到的SnSxSe2-x的拉曼仿真谱高度吻合,理论计算结果较好地诠释了实验拉曼光谱发生变化的原因。本研究提供了一种元素百分比可调的三元SnSxSe2-x单晶纳米片的可控制备方法,同时对锡二硫族化合物的明确、无损识别提供了方案。  相似文献   
3.
Pesticide residue in vegetables has been considered as a serious food safety problem across the whole world. This study investigates a novel advanced oxidation process (AOP), namely the coupled free chlorine/ultrasound (FC/US) process for the removal of three typical pesticides from lettuce. The removal efficiencies of dimethoate (DMT), trichlorfon (TCF) and carbofuran (CBF) from lettuce reached 86.7%, 79.8% and 71.3%, respectively by the FC/US process. There existed a synergistic effect in the coupled FC/US process for pesticide removal and the synergistic factors reached 22.3%, 19.0% and 36.4% for DMT, TCF and CBF, respectively. Based on the analysis of mass balance of pesticides, the synergistic effect was probably attributed to the efficient oxidation of pesticides both in vegetables and in water by the generated free radicals and FC. The surface area and surface structure of vegetables strongly affected the removal of pesticides by FC/US. The removal efficiency of DMT increased from 80.9% to 88.1% as solution pH increased from 5.0 to 8.0, and then decreased to 84.1% when solution pH further increased to 9.0. When the ultrasonic frequency changed from 20 to 40 kHz, a remarkable improvement in pesticide removal by FC/US was observed. As the FC concentration increased from 0 to 15 mg L–l, the removal efficiencies of pesticides increased firstly, and then became stagnant when the FC concentration further increased to 25 mg L–l. The pesticide degradation pathways based on the identified intermediates were proposed. The total chlorophyll content was reduced by less than 5% after the FC/US process, indicating a negligible damage to the quality of vegetables. It suggests that the FC/US process is a promising AOP for pesticides removal from vegetables.  相似文献   
4.
Ultrasound can accelerate and change the reaction process and is widely used in the field of hydrogen production and storage. In this study, ultrasound (US) and AlOOH suspension (AH) are used to promote hydrogen production from Al hydrolysis. The results indicate that both US and AH greatly shorten the induction time and enhance the hydrogen production rate and yield. The promoting effect of US and AH on Al hydrolysis originates from the acoustic cavitation effect and catalytic effect, respectively. When AH is used in combination with US, Al hydrolysis has the best hydrogen production performance and the hydrogen yield can reach 96.6 % within 1.2 h, because there is a synergistic effect on Al hydrolysis between AH and US. Mechanism analyses reveal that the micro-jets and local high temperature environment arising from acoustic cavitation improve the catalytic activity of AlOOH, while the suspended AlOOH particles enhance the cavitation effect of US. This work provides a novel and feasible method to promote hydrogen production from Al hydrolysis.  相似文献   
5.
信息技术的快速发展,使得闲置产能的分享逐渐成为生产领域重要的产能利用模式。为研究闲置产能分享时平台的最优定价问题,在平台向供给者收取交易费而对需求者不收费的条件下,首先,建立商业平台和公益平台的基础模型,并对两类平台进行分析和对比;然后,在基础模型之上构建以一定权重考虑其他参与者利益的平台X的定价模型,探讨权重对最优交易费、供需双方的数量以及平台最优利润的影响;最后,用数值例子验证文中重要定理以及权重对供需双方效用产生的影响。研究结果表明:(1)商业平台收取的最优交易费和获得的最优利润均高于公益平台;(2)考虑其他参与者利益的平台X收取的最优交易费和获得的最优利润、需求者(免费方)的数量和效用均随着权重的增加而增加,而供给者(被收费方)的数量及其效用则随着权重的增加而减少。研究结果为平台运营商和企业的行为决策提供理论参考依据。  相似文献   
6.
Carotenoids are an essential component of cashew and can be used in pharmaceuticals, cosmetics, natural pigment, food additives, among other applications. The present work focuses on optimizing and comparing conventional and ultrasound-assisted extraction methods. Every optimization step took place with a 1:1 (w:w) mixture of yellow and red cashew apples lyophilized and ground in a cryogenic mill. A Simplex-centroid design was applied for both methods, and the solvents acetone, methanol, ethanol, and petroleum ether were evaluated. After choosing the extractor solvent, a central composite design was applied to optimize the sample mass (59–201 mg) and extraction time (6–34 min). The optimum conditions for the extractor solvent were 38% acetone, 30% ethanol, and 32% petroleum ether for CE and a mixture of 44% acetone and 56% methanol for UAE. The best experimental conditions for UAE were a sonication time of 19 min and a sample mass of 153 mg, while the CE was 23 min and 136 mg. Comparing red and yellow cashews, red cashews showed a higher carotenoid content in both methodologies. The UAE methodology was ca. 21% faster, presented a more straightforward composition of extracting solution, showed an average yield of superior carotenoid content in all samples compared to CE. Therefore, UAE has demonstrated a simple, efficient, fast, low-cost adjustment methodology and a reliable alternative for other applications involving these bioactive compounds in the studied or similar matrix.  相似文献   
7.
自新冠肺炎(COVID-19)疫情爆发以来,国内外多家研究机构和企业都在加快推进新冠病毒(SARS-CoV-2)抗体药物的研发。药物多晶型限制了有效药物的研发进度。药物生产、存储和使用环境影响了药物的稳定性。红外光谱作为一种快速无损检测手段,可从振动光谱反映出药物结构、晶型甚至生产工艺上的差异大大提高了研发效率。首次以三种临床试验被认为治疗新冠肺炎有效药物:磷酸氯喹,利巴韦林和盐酸阿比多尔为例,利用傅里叶红外光谱仪测试得到它们在远红外(1~10 THz)和中红外(400~4 000 cm-1)波段的振动光谱。远红外光谱中,利巴韦林的特征峰位于:2.01,2.68,3.37,4.05,4.83,5.45,5.92,6.42和7.14 THz附近;磷酸氯喹的特征峰位于:1.26,1.87,2.37,3.06,3.78,5.09和6.06 THz附近;盐酸阿比多尔的特征峰位于:2.24,3.14,3.72,4.25和5.38 THz附近。结合密度函理论,选择B3LYP杂化泛函和6-311++G(d,p)基组,利用Crystal14和Gaussian16软件分析了光谱中所有特征峰对应的振动模式,实现了对振动光谱的精确指认。远红外波段,振动模式源自分子的集体振动。中红外波段,2 800 cm-1以下,振动模式主要源自基团的面内外弯曲和摇摆;2 800 cm-1以上,振动模式过渡为C—H,O—H和N—H键的面内伸缩。以考虑了周期性边界条件的晶体结构作为理论计算的初始构型,会让理论光谱与实验光谱更加吻合,尤其是在远红外波段和中红外400~1 000 cm-1的低频段。该研究对深入理解磷酸氯喹,利巴韦林和盐酸阿比多尔等抗病毒药物的药学特性,药物间相互作用,控制药物生产过程,指导药物存储和使用有重大意义。  相似文献   
8.
Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge.  相似文献   
9.
任虎虎 《物理通报》2022,(1):61-63+67
学科大概念向下统领学科内核心知识,向上构成学科核心素养的基本框架,指向学科结构的中心,因此它不只是一个聚合概念,也是连接学科知识与学科核心素养的工具和媒介[1,2].以"机械能守恒定律"教学为例探讨基于大情境,促进还原与下沉,激活学科大概念;基于大问题,促进探究与整合,建构学科大概念;基于大反思,促进反思与上浮,迁移学科大概念.  相似文献   
10.
延安是中国共产党领导革命的中心和战略总后方,是革命的红色摇篮。延安时期出版了大量具有历史、文化以及教育意义的红色文献,这些红色文献记载了中国共产党波澜壮阔的发展历程,也反映了延安时期不断发展的科技生产水平与独特的制浆造纸工艺,具有重要的研究价值。然而,延安时期出版的红色文献虽距今不到百年时间,但其保存现状不容乐观,普遍存在纸张老化、焦脆易碎等问题,大量文献急需科学检测与修复保护,以延长其保存寿命。目前,针对延安时期红色文献的检测研究仍存在较大空白。考虑到红色文献的珍贵性与特殊性,应当尽可能选择无损检测方法对其分析检测。基于衰减全反射-傅里叶变换红外光谱法(ATR-FTIR),以木素1 510 cm-1处特征峰与纤维素1 030 cm-1处特征峰的强度作为定量依据,建立了造纸原料与红色文献纸张中木素相对含量的无损检测方法。通过检测不同碱强度与碱浓度处理后的构皮、苦竹与杨木的木素含量,考察了制浆过程中碱处理条件对造纸原料脱木素程度的影响,同时体现了红外光谱法测定木素相对含量的普适性。以复旦大学图书馆藏的76册延安时期红色文献为研究对象,分析了红色文献的纸张木素含量与纸张pH值以及纸张氧化度的相互关系。结果表明,木素相对含量高于25%的红色文献,其纸张pH集中在3~4之间且纸张氧化度较高,文献整体保存状况堪忧;而木素相对含量低于25%的红色文献,其纸张氧化度与酸度较低,文献整体保存情况较好。以上结果验证了红外光谱无损检测法用于延安时期红色文献木素含量分析的可行性,并结合纸张氧化度与酸度数据提出了纸张木素含量的合适范围,为制浆造纸中植物原料的脱木素过程提供参考。拓展了红外光谱法在红色文献无损检测中的应用范围,以期为延安时期红色文献的修复与保护研究提供科学依据。  相似文献   
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