响应面法优化农产品中抗性淀粉的体外检测

目的 采用响应面法优化农产品中抗性淀粉(Resistant Starch, RS)的体外检测方法。方法 选择谷类、薯类、豆类3类抗性淀粉主要来源的农产品，设计单因素试验和Box-Behnken试验。单因素试验考察了水浴时间、淀粉葡萄糖苷酶（AMYLOGLUCOSIDASE, AMG）作用温度、AMG作用时间、AMG添加量和离心力与离心时间5个条件，并选择AMG作用温度、AMG作用时间、AMG添加量来设计Box-Behnken试验。结果 根据单因素试验，确定了水浴时间为14 h，离心条件选择4500 g离心5 min；根据响应面实验确定对RS含量检测结果影响程度排序为AMG添加量＞AMG作用时间＞AMG作用温度。结合单因素响应面试验，确定最佳检测方法为水浴14 h，4500 g离心5 min，AMG作用温度49℃、AMG添加量0.2 mL、AMG作用时间38 min。结论 优化后的方法重复性良好，适用于玉米、马铃薯和红豆3类样品，且有望适用于其他主要农产品。     

Study of Brinkman–Bènard nanofluid convection with idealistic and realistic boundary conditions and by considering the effects of shape of nanoparticles

This study deals with linear and weakly non-linear stability analyses of Brinkman–Bènard convection in nanoliquid-saturated porous enclosures. Water with a dilute concentration of molybdenum disulfide nanoparticles with 0.06 volume fraction and 30% glass fiber-reinforced polycarbonate as a porous medium with porosity 0.88 are considered to be a working medium. The analytical solution is obtained in the present study for idealistic and realistic boundary conditions, and their results are compared. An analytically intractable Lorenz model with quadratic nonlinearities is reduced to a tractable Ginzburg–Landau amplitude equation with cubic nonlinearity using the multiscale method. Nanoparticles with different shapes are considered in the study, and their effects on the onset and heat transfer are discussed in great detail graphically in the presence of other parameters arising in the problem.     

Eugenol,citral, and hexanal,alone or in combination with heat,affect viability,biofilm formation,and swarming on Shiga-toxin-producing Escherichia coli

Shiga-toxin-producing Escherichia coli strains are pathogenic for humans and cause mild to severe illnesses. In this study, the antimicrobial effect of citral, eugenol, and hexanal in combination with heat shock (HS) was evaluated in terms of the growth, biofilm formation, swarming, and expression of virulence genes of STEC serotypes (O157:H7, O103, O111, and O26). Eugenol was the most effective compound against the growth of E. coli strains (MBC = 0.58 to 0.73 mg/mL), followed by citral (MBC = 0.86 to 1.26 mg/mL) and hexanal (MBC = 2.24 to 2.52 mg/mL). Biofilm formation and swarming motility have great variability between STEC strains. Natural compounds—alone or combined with HS—inhibited biofilm formation; however, swarming motility was induced by most treatments. The expression of the studied genes during biofilm formation and swarming under natural antimicrobials was affected but not in a uniform pattern. These treatments could be used to control contamination of STEC and inhibit biofilm formation.     

Comprehensive numerical study of molecular diffusion effects and Eddy Dissipation Concept model in MILD combustion

Moderate or Intense Low-oxygen Dilution (MILD) combustion is a clean combustion technology with high thermal efficiency and low levels of emissions. In this paper, by employing Adelaide Jet-in-Hot-Co-flow (AJHC), several approaches are examined to increase the numerical solution accuracy. First, molecular diffusion effects are investigated in MILD combustion. Second, adjusting the Eddy Dissipation Concept (EDC) coefficients is comprehensively discussed, and finally, the reaction fraction coefficient and EDC formulation are investigated. The results show that the effect of enthalpy transport caused by molecular diffusion on the energy equation must be considered in the low oxygen concentration regions. Also, the maximum temperature in the MILD region can be kept constant by adjusting EDC coefficients. Furthermore, it is shown that applying the reaction fraction factor increases the accuracy of the numerical solution in the MILD region.     

融合时间隐语义填充和子群划分的推荐算法

随着个性化推荐技术的发展，推荐系统面临着越来越多的挑战。传统的推荐算法通常存在数据稀疏性和推荐精度低等问题。针对以上问题，提出了一种融合时间隐语义填充和子群划分的推荐算法[K]-TLFM（Time Based Latent Factor Model Integrated with [k]-means）。该算法利用融合时间因素的隐语义模型对原始用户物品评分矩阵缺失项进行填充，避免了用全局平均值或者用户/物品平均值补全矩阵带来的误差，有效缓解了数据稀疏性问题，同时融合时间因素有效地刻画了用户偏好随时间的变化；完成评分矩阵缺失项填充后，基于二分[k]-means聚类算法将偏好、兴趣特征相似的对象划分到同一个子群中，在目标用户所属的子群中基于选定的协同过滤算法为用户产生推荐列表，提高了推荐效率和准确性。在MovieLens和Netflix数据集上对该算法的推荐性能进行了对比实验，结果表明该算法具有更高的推荐精度。     

A tripartite approach to operator-error evaluation in ballast water management system operation

This paper presents a new methodology developed to quantitatively analyze and prioritize the contributions of Human Factors (HFs) in the human-machine-interaction (HMI) within a complex sociotechnical system such as a Ballast Water Management (BWM) System. The methodology is a combination of the Human Factor Analysis Classification System (HFACS), Analytic Hierarchy Process (AHP), and a modified version of the Theory of Inventive Problem Solving (TRIZ) known as the Radial Dynamics Model (RDM). The methodology (HFACS-AHP-RDM) is based on a five-step algorithm, with which data from experts’ judgment was analyzed. A human-error and system risk minimization hierarchy was subsequently proposed to improve human performance and minimize the likelihood of an unwanted event such as the discharge of harmful aquatic organisms and pathogens (HAOPs). The result from the study in order of hierarchy showed fatigue, training and complex automation to be the HFs with the greatest impacts on BWM operations. Minimizing their impact, therefore, will have the greatest positive contribution on the performance of the system.Relevance to industryThe study's outcome shall help decision makers in prioritizing limited resources (e.g. time and money) allocation to resolving only issues related to HFs with the greatest impact on BWM System's performance. The new methodology could also be applicable in assessing the relative impacts of subjective criteria like HFs in complex sociotechnical systems other than BWM Systems.     

How do normalization schemes affect net spillovers? A replication of the Diebold and Yilmaz (2012) study

This paper replicates the Diebold and Yilmaz (2012) study on the connectedness of the commodity market and three other financial markets: the stock market, the bond market, and the FX market, based on the Generalized Forecast Error Variance Decomposition, GEFVD. We show that the net spillover indices (of directional connectedness), used to assess the net contribution of one market to overall risk in the system, are sensitive to the normalization scheme applied to the GEFVD. We show that, considering data generating processes characterized by different degrees of persistence and covariance, a scalar-based normalization of the Generalized Forecast Error Variance Decomposition is preferable to the row normalization suggested by Diebold and Yilmaz since it yields net spillovers free of sign and ranking errors.     

血小板源性生长因子/蛋白激酶B通路在压力超负荷诱导的心室重构中的作用及机制研究

目的:分析血小板源性生长因子（PDGF）/蛋白激酶B（AKT）通路在压力超负荷诱导的心室重构中的作用及机制。方法:选取C57BL/6雌性小鼠55只，建立主动脉弓缩窄模型，成功建模45只，小鼠随机数字表法分为假手术组、DMSO组和实验组，假手术组小鼠开胸后逐层缝合，不进行主动脉缩窄术（TAC），开胸24 h后给予PBS溶液200 μL加DMSO 50 μL，DMSO组TAC术后24 h给予PBS溶液200 μL加DMSO 50 μL，实验组TAC术后24 h给予PBS溶液200 μL加抑制剂AG1296 50 μL，观察小鼠心功能及心肌组织病理形态。慢病毒感染建立PDGF基因不同表达人脐静脉内皮细胞（HUVEC）细胞鉴定和培养，依据细胞不同处理方式分为对照组、PDGF组、shRNA组和PDGF+IMA组，检测p-AKT及t-AKT蛋白在HUVEC细胞内表达情况。结果:DMSO组小鼠左室收缩末期容积（LVESV）、左室舒张末期容积（LVEDV）、左室收缩末期内径（LVESD）及左室舒张末期内径（LVEDD）较假手术组升高，左室射血分数（EF）、左室短轴缩短率（FS）较假手术组降低。实验组LVESV、LVEDV、LVESD及LVEDD较DMSO组降低，EF、FS较DMSO组升高，差异有统计学意义（P＜0.05）。假手术组小鼠心肌组织整齐排列，间隙正常；DMSO组小鼠形态不规整，炎性细胞浸润，细胞间隙变大，胞核深染。实验组小鼠膨大或坏死细胞减少，间隙变小，炎性浸润降低。DMSO组小鼠心肌细胞横截面积较假手术组升高，实验组小鼠心肌细胞横截面积较DMSO组降低，差异有统计学意义（P＜0.05）。PDGF+IMA组细胞内p-AKT及t-AKT蛋白表达较PDGF组及shRNA组显著降低，差异有统计学意义（P＜0.05）。结论:PDGF可加速压力超负荷诱导心室重构，促进形成心肌组织纤维化，而抑制PDGF/AKT通路可改善心肌细胞肥大。