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1.
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   
2.
基于水声超材料吸声机理和多层平行介质平面波理论,建立局域共振型水声超材料结构,通过COMSOL进行建模计算,研究该结构的吸声性能机理,此外为了验证钢背衬的隔声性能,在该水声超材料结构基础上添加一层0.005m厚的钢背衬进行仿真对比。研究结果表明,在频段为200Hz-4000Hz时,水声超材料声学性能较好,吸声性能整体较优,且添加钢背衬的水声超材料隔声性能较优,甚至在某频率点达到15dB的隔声差值;此外通过位移场图进一步揭示水声超材料的吸声机理,发现水声超材料结构的位移场和钢背衬都对吸声性能会产生影响,钢背衬通过影响共振吸收来影响吸声性能,而位移场则通过位移幅度大小影响吸声性能。  相似文献   
3.
Aimed at the internal short circuit problem due to large deformation of the prismatic lithium-ion battery cell under impact loadings, a simplified battery model was first established. Then the motion equations of velocity and displacement based on the membrane factor method were proposed. With the effects of the face-sheet thickness and the densification region on the normalized final deflection, impact response characteristics of prismatic battery cells were investigated in detail. The results show that, the improved motion equations involving the membrane factor can reflect the dynamic response mechanisms of the prismatic battery cell under impact loadings, and the large deflection under high-speed impact can be predicted. With the increase of the face-sheet thickness, the deflection of the battery cell’s lower part decreases obviously. However, the densification region expands with the face-sheet thickness. The deflection and the densification region of the cell’s lower part both increase with the inner core density of the battery. This proposed impact model provides a theoretical guidance for the multi-functional integrated dynamic design of prismatic battery cells. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.  相似文献   
4.
在隔声板结构中,分布式内嵌大量小型消声单元,在入射声波被消声单元有效衰减的同时,气流可均匀通过整个板结构,形成一种分布式消声板结构。利用平面波理论和修正传递矩阵法,建立消声板简化模型,并预测模型传递损失。加工消声板样件,实验室内测试并验证其声学及通风性能。对比隔声测试结果与预测结果,验证修正传递矩阵法针对该结构的准确性,同时验证消声板结构的实际效果。结果显示,该分布式消声板结构具有良好的声学效果,修正传递矩阵法可应用于该结构的声学性能预测以及结构设计。  相似文献   
5.
梁青 《应用数学和力学》2022,43(9):1034-1044
该文讨论了一类带扰动的随机脉冲泛函微分方程解的渐近性.通过比较扰动方程的解和原方程的解,得到了两者逼近的充分条件.首先,两者在有限的时间区间上相互逼近;其次,当扰动趋于零时,区间长度趋于无穷大,在这个区间上两个解仍然是相互逼近的.最后,举例说明了结果的有效性.  相似文献   
6.
本文提出了一种新的带有时间幂次项的灰色GM(1,1,k,k2)模型,给出了其灰微分方程和白化微分方程基本形式。基于最小二乘法获得了该模型参数估计值,并推导了该模型时间响应函数。鉴于GM(1,1,k,k2)模型灰微分方程与白化微分方程之间存在跳跃关系,首先对灰微分方程的背景值进行了优化,并推导了优化后的背景值计算公式。为了克服初始值的影响,根据误差平方和最小,进一步优化了GM(1,1,k,k2)模型时间响应函数。最后,该优化后的GM(1,1,k,k2)模型被应用于软土地基沉降预测,获得了较好的模拟预测效果,说明模型是可行的。  相似文献   
7.
Kai-Feng Yin 《中国物理 B》2022,31(11):110703-110703
Zero-field single-beam atomic magnetometers with transverse parametric modulation for ultra-weak magnetic field detection have attracted widespread attention recently. In this study, we present a comprehensive response model and propose a modification method of conventional first harmonic response by introducing the second harmonic correction. The proposed modification method gives improvement in dynamic range and reduction of linearity error. Additionally, our modification method shows suppression of response instability caused by optical intensity and frequency fluctuations. An atomic magnetometer with single-beam configuration is built to compare the performance between our proposed method and the conventional method. The results indicate that our method's magnetic field response signal achieves a 5-fold expansion of dynamic range from 2 nT to 10 nT, with the linearity error decreased from 5% to 1%. Under the fluctuations of 5% for optical intensity and ±15 GHz detuning of frequency, the proposed modification method maintains intensity-related instability less than 1% and frequency-related instability less than 8% while the conventional method suffers 15% and 38%, respectively. Our method is promising for future high-sensitive and long-term stable optically pumped atomic sensors.  相似文献   
8.
基于不完备频响函数数据,结合概率统计方法,提出了一种能同时考虑模型参数不确定性和测试噪声影响的结构损伤统计识别方法。首先,基于频响函数某一行向量在不同频率下的幅值数据,利用矩阵拉直运算建立了关于损伤系数的确定性识别方程。其次,假设模型参数误差和测试噪声为零均值的高斯随机变量,根据摄动理论,推导了损伤后结构刚度参数的前二阶矩。随后,利用结构损伤前后的概率分布得到了结构损伤存在概率。最后,通过一个平面桁架结构模型验证了本文方法的有效性。数值算例的研究结果表明,损伤单元的损伤存在概率远大于非损伤单元;测试噪声对识别结果的影响比模型参数不确定性的影响更为显著。  相似文献   
9.
Ulcerative colitis, an inflammatory bowel disease, is a chronic inflammatory disorder that results in ulcers of the colon and rectum without known etiology.Ulcerative colitis causes a huge public health care burden particularly in developed countries.Many studies suggest that ulcerative colitis results from an abnormal immune response against components of commensal microbiota in genetically susceptible individuals.However, understanding of the disease mechanisms at cellular and molecular levels remains largely elusive.In this paper, a network model is developed based on our previous study and computer simulations are performed using an agent-based network modeling to elucidate the dynamics of immune response in ulcerative colitis progression.Our modeling study identifies several important positive feedback loops as a driving force for ulcerative colitis initiation and progression.The results demonstrate that although immune response in ulcerative colitis patients is dominated by anti-inflammatory/regulatory cells such as alternatively activated macrophages and type Ⅱ natural killer T cells, proinflammatory cells including classically activated macrophages, T helper 1 and T helper 17 cells, and their secreted cytokines tumor necrosis factor-α, interleukin-12, interleukin-23, interleukin-17 and interferon-γ remain at certain levels (lower than those in Crohn's disease, another inflammatory bowel disease).Long-term exposure to these proinflammatory components, causes mucosal tissue damage persistently, leading to ulcerative colitis.Our simulation results are qualitatively in agreement with clinical and laboratory measurements, offering novel insight into the disease mechanisms.  相似文献   
10.
《Mathematische Nachrichten》2018,291(2-3):443-491
In this paper, we propose the concepts of Caputo fractional derivatives and Caputo type Hadamard fractional derivatives for piecewise continuous functions. We obtain general solutions of four classes of impulsive fractional differential equations (Theorem 3.1–Theorem 3.4) respectively. These results are applied to converting boundary value problems for impulsive fractional differential equations to integral equations. Some comments are made on recently published papers (see Section 4).  相似文献   
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