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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.
Hydrothermal synthesis using graphene oxide (GO) as a precursor has been used to produce luminescent graphene quantum dots (GQDs). However, such a method usually requires many reagents and multistep pretreatments, while can give rise to GQDs with low quantum yield (QY). Here, we investigated the concentration, the temperature of synthesis, and the pH of the GO solution used in the hydrothermal method through factorial design experiments aiming to optimize the QY of GQDs to reach a better control of their luminescent properties. The best synthesis condition (2 mg/mL, 175 °C, and pH = 8.0) yielded GQDs with a relatively high QY (8.9%) without the need of using laborious steps or dopants. GQDs synthesized under different conditions were characterized to understand the role of each synthesis parameter in the materials' structure and luminescence properties. It was found that the control of the synthesis parameters enables the tailoring of the amount of specific oxygen functionalities onto the surface of the GQDs. By changing the synthesis' conditions, it was possible to prioritize the production of GQDs with more hydroxyl or carboxyl groups, which influence their luminescent properties. The as-developed GQDs with tailored composition were used as luminescent probes to detect Fe3+. The lowest limit of detection (0.136 μM) was achieved using GQDs with higher amounts of carboxylic groups, while wider linear range was obtained by GQDs with superior QY. Thus, our findings contribute to rationally produce GQDs with tailored properties for varied applications by simply adjusting the synthesis conditions and suggest a pathway to understand the mechanism of detection of GQDs-based optical sensors.  相似文献   
3.
针对考虑几何和材料非线性的石英晶体板厚度剪切振动和弯曲振动的方程组,利用扩展伽辽金法对该方程组进行转化和求解,分别获得了强烈耦合的厚度剪切振动模态和弯曲振动模态的频率响应关系,绘制了不同振幅比和不同驱动电压影响下的频率响应曲线图。数值计算结果表明可以选取石英晶片的最佳长厚比尺寸来避免两种模态的强烈耦合。驱动电压的变化将引起石英晶体谐振器厚度剪切振动频率的明显改变,必须将振动频率的漂移值控制在常用压电声波器件的允许值之内。扩展伽辽金法对石英晶体板非线性振动方程组的求解为非线性有限元分析和偏场效应分析奠定了基础。  相似文献   
4.
In the present paper,we study the restricted inexact Newton-type method for solving the generalized equation 0∈f(x)+F(x),where X and Y are Banach spaces,f:X→Y is a Frechet differentiable function and F:X■Y is a set-valued mapping with closed graph.We establish the convergence criteria of the restricted inexact Newton-type method,which guarantees the existence of any sequence generated by this method and show this generated sequence is convergent linearly and quadratically according to the particular assumptions on the Frechet derivative of f.Indeed,we obtain semilocal and local convergence results of restricted inexact Newton-type method for solving the above generalized equation when the Frechet derivative of f is continuous and Lipschitz continuous as well as f+F is metrically regular.An application of this method to variational inequality is given.In addition,a numerical experiment is given which illustrates the theoretical result.  相似文献   
5.
采用水热-煅烧法制备Cd2SnO4,之后通过超声混合法得到一系列MoS2/Cd2SnO4复合材料。采用X射线衍射、扫描电子显微镜、X射线光电子能谱对Cd2SnO4和一系列MoS2/Cd2SnO4复合材料进行结构和形貌的表征。研究了MoS2掺杂量对于MoS2/Cd2SnO4复合材料的气敏性能影响。实验结果表明,当MoS2与Cd2SnO4的质量比为2.5%,MoS2/Cd2SnO4复合材料制备的气敏元件在170 ℃时对浓度为100 μL·L-1的甲醛气体的灵敏度为40.0,最低检测限为0.1 μL·L-1。  相似文献   
6.
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   
7.
0.5 mol% Nd-doped (Ba0.85Ca0.15)(Ti0.9Hf0.1)O3 (BCTH-Nd) lead-free ceramics were prepared by a solid-phase twin crystal method, where the effects of sintering condition on structure, electrical and optical properties were studied. All the sintered BCTH-Nd ceramics exhibit pure perovskite structure, dense microstructure with several micron grain size, which tends to increase with elevating sintering temperature. All synthesized ceramics have complex dielectric behavior, which presents normal ferroelectrics characteristic with slight dispersion phenomenon. The BCTH-Nd ceramics exhibit excellent piezoelectric and ferroelectric properties and acceptable dielectric performance when sintered at 1480 °C for 2 h. Under 269 nm light excitation, several fluorescent emission peaks are excited with a whole indigo fluorescence, where the strongest emission peak is emitted at 473 nm, corresponding to the 4G3/2 → 4I9/2 energy level transition of Nd3+. Multifunctional performance is fulfilled in the lead-free BCTH ceramics via rare earth doping, which can broaden the application fields of piezoelectric-based materials.  相似文献   
8.
结合无网格局部彼得洛夫-伽辽金(MLPG)方法和径向基函数有限差分(RBF-FD)无网格方法求解非线性热传导问题。MLPG方法属于弱式无网格方法,具有处理边界条件方便的优点,然而因其要做大量的插值、积分运算而计算效率偏低;RBF-FD无网格方法属于强式无网格方法,直接对微分算子进行数值离散,计算效率高,然而其边界条件的处理较复杂。将二者相结合,在求解域边界附近采用MLPG方法,其它区域采用RBF-FD无网格方法,则能扬长避短。介绍了MLPG方法和RBF-FD无网格方法的基本原理,将该混合方法用来求解非线性热传导方程,数值算例显示了方法的正确性和高效性。  相似文献   
9.
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   
10.
暴露于硫酸盐环境中的混凝土输水管易遭受硫酸盐化学侵蚀,导致其耐久性退化、提前失效;而环境中硫酸根离子传输进入混凝土是其化学侵蚀的前提.为获得混凝土内硫酸根离子的扩散进程,首先基于Fick定律及质量守恒定律,建立饱和混凝土管内硫酸根离子的扩散-反应模型.其次,将扩散-反应模型的边界条件齐次化,建立其有限元控制方程.然后,开展硫酸钠溶液中水泥砂浆圆柱试件的腐蚀试验,测定试件不同深度处的硫酸根离子浓度,与模型计算结果对比,以验证模型.最后,开展数值模拟研究,分析混凝土输水管外表面、内外表面暴露于浓度恒定或振荡的硫酸盐溶液情况下管内硫酸根离子浓度的时空分布.  相似文献   
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