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81.
ABSTRACTCrude extracts were extracted from blossoms of Citrus aurantium L. var. amara Engl. with 50% ethanol (CAVAP-E), 50% methanol (CAVAP-M), and hot water (CAVAP-W). CAVAP-W had the highest polyphenol yield of 3.7%. The optimum values of liquid/solid ratio, ultrasonic time, and ultrasonic power were 34.06 mL/g, 1 h, and 81.04 W, respectively. The adsorption characteristics of polyphenols were investigated using different macroporous resins. AB-8 and HP-20 resins offered higher adsorption and desorption capacities. Langmuir equation was more suitable to predict the adsorption of polyphenols. The pseudo second-order model was satisfactory to describe the kinetic data of polyphenols onto AB-8 and HP-20. 相似文献
82.
Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen frequently associated with acute diarrhea in children and travelers to endemic regions. EAEC was found the most prevalent bacterial diarrheal pathogen from hospitalized Bolivian children less than five years of age with acute diarrhea from 2007 to 2010. Here, we further characterized the epidemiology of EAEC infection, virulence genes, and antimicrobial susceptibility of EAEC isolated from 414 diarrheal and 74 non-diarrheal cases. EAEC isolates were collected and subjected to a PCR-based virulence gene screening of seven virulence genes and a phenotypic resistance test to nine different antimicrobials. Our results showed that atypical EAEC (a-EAEC, AggR-negative) was significantly associated with diarrhea (OR, 1.62, 95% CI, 1.25 to 2.09, p < 0.001) in contrast to typical EAEC (t-EAEC, AggR-positive). EAEC infection was most prevalent among children between 7–12 months of age. The number of cases exhibited a biannual cycle with a major peak during the transition from warm to cold (April–June). Both typical and a-EAEC infections were graded as equally severe; however, t-EAEC harbored more virulence genes. aap, irp2 and pic were the most prevalent genes. Surprisingly, we detected 60% and 52.6% of multidrug resistance (MDR) EAEC among diarrheal and non-diarrheal cases. Resistance to ampicillin, sulfonamides, and tetracyclines was most common, being the corresponding antibiotics, the ones that are frequently used in Bolivia. Our work is the first study that provides comprehensive information on the high heterogenicity of virulence genes in t-EAEC and a- EAEC and the large prevalence of MDR EAEC in Bolivia. 相似文献
83.
84.
This paper deals with modeling of the phenomenon of fretting fatigue in
heterogeneous materials using the multi-scale computational homogenization technique
and finite element analysis (FEA). The heterogeneous material for the specimens consists
of a single hole model (25% void/cell, 16% void/cell and 10% void/cell) and a four-hole
model (25% void/cell). Using a representative volume element (RVE), we try to produce
the equivalent homogenized properties and work on a homogeneous specimen for the
study of fretting fatigue. Next, the fretting fatigue contact problem is performed for 3 new
cases of models that consist of a homogeneous and a heterogeneous part (single hole cell)
in the contact area. The aim is to analyze the normal and shear stresses of these models
and compare them with the results of the corresponding heterogeneous models based on
the Direct Numerical Simulation (DNS) method. Finally, by comparing the
computational time and % deviations, we draw conclusions about the reliability and
effectiveness of the proposed method. 相似文献
85.
To minimize the mass and increase the bearing failure load of composite doublelap bolted joints, a three-step optimization strategy including feasible region reduction,
optimization model decoupling and optimization was presented. In feasible region
reduction, the dimensions of the feasible design region were reduced by selecting dominant
design variables from numerous multilevel parameters by sensitivity analyses, and the
feasible regions of variables were reduced by influence mechanism analyses. In model
decoupling, the optimization model with a large number of variables was divided into
various sub-models with fewer variables by variance analysis. In the third step, the
optimization sub-models were solved one by one using a genetic algorithm, and the
modified characteristic curve method was adopted as the failure prediction method. Based
on the proposed optimization method, optimization of a double-lap single-bolt joint was
performed using the ANSYS® code. The results show that the bearing failure load increased
by 13.5% and that the mass decreased by 8.7% compared with those of the initial design of
the joint, which validated the effectiveness of the three-step optimization strategy. 相似文献
86.
Based on multiphase field conception and integrated with the idea of vectorvalued phase field, a phase field model for typical allotropic transformation of solid
solution is proposed. The model takes the non-uniform distribution of grain boundaries of
parent phase and crystal orientation into account in proper way, as being illustrated by the
simulation of austenite to ferrite transformation in low carbon steel. It is found that the
misorientation dependent grain boundary mobility shows strong influence on the
formation of ferrite morphology comparing with the weak effect exerted by
misorientation dependent grain boundary energy. The evolution of various types of grain
boundaries are quantitatively characterized in terms of its respective grain boundary
energy dissipation. The simulated ferrite fraction agrees well with the expectation from
phase diagram, which verifies this model. 相似文献
87.
Yihe Liu Aaqif Afzaal Abbasi Atefeh Aghaei Almas Abbasi Amir Mosavi Shahaboddin Shamshirband Mohammed A. A. Al-qaness 《计算机、材料和连续体(英文)》2020,63(1):31-61
Mobile cloud computing is an emerging field that is gaining popularity across borders at a rapid pace. Similarly, the field of health informatics is also considered as an extremely important field. This work observes the collaboration between these two fields to solve the traditional problem of extracting Electrocardiogram signals from trace reports and then performing analysis. The developed system has two front ends, the first dedicated for the user to perform the photographing of the trace report. Once the photographing is complete, mobile computing is used to extract the signal. Once the signal is extracted, it is uploaded into the server and further analysis is performed on the signal in the cloud. Once this is done, the second interface, intended for the use of the physician, can download and view the trace from the cloud. The data is securely held using a password-based authentication method. The system presented here is one of the first attempts at delivering the total solution, and after further upgrades, it will be possible to deploy the system in a commercial setting. 相似文献
88.
With the popularity of sensor-rich mobile devices, mobile crowdsensing (MCS) has emerged as an effective method for data collection and processing. However, MCS platform usually need workers’ precise locations for optimal task execution and collect sensing data from workers, which raises severe concerns of privacy leakage. Trying to preserve workers’ location and sensing data from the untrusted MCS platform, a differentially private data aggregation method based on worker partition and location obfuscation (DP-DAWL method) is proposed in the paper. DP-DAWL method firstly use an improved K-means algorithm to divide workers into groups and assign different privacy budget to the group according to group size (the number of workers). Then each worker’s location is obfuscated and his/her sensing data is perturbed by adding Laplace noise before uploading to the platform. In the stage of data aggregation, DP-DAWL method adopts an improved Kalman filter algorithm to filter out the added noise (including both added noise of sensing data and the system noise in the sensing process). Through using optimal estimation of noisy aggregated sensing data, the platform can finally gain better utility of aggregated data while preserving workers’ privacy. Extensive experiments on the synthetic datasets demonstrate the effectiveness of the proposed method. 相似文献
89.
This paper examines the causal relationship between oil prices and the Gross
Domestic Product (GDP) in the Kingdom of Saudi Arabia. The study is carried out by a
data set collected quarterly, by Saudi Arabian Monetary Authority, over a period from
1974 to 2016. We seek how a change in real crude oil price affects the GDP of KSA.
Based on a new technique, we treat this data in its continuous path. Precisely, we analyze
the causality between these two variables, i.e., oil prices and GDP, by using their yearly
curves observed in the four quarters of each year. We discuss the causality in the sense of
Granger, which requires the stationarity of the data. Thus, in the first Step, we test the
stationarity by using the Monte Carlo test of a functional time series stationarity. Our
main goal is treated in the second step, where we use the functional causality idea to
model the co-variability between these variables. We show that the two series are not
integrated; there is one causality between these two variables. All the statistical analyzes
were performed using R software. 相似文献
90.
As an unsupervised learning method, stochastic competitive learning is
commonly used for community detection in social network analysis. Compared with the
traditional community detection algorithms, it has the advantage of realizing the timeseries community detection by simulating the community formation process. In order to
improve the accuracy and solve the problem that several parameters in stochastic
competitive learning need to be pre-set, the author improves the algorithms and realizes
improved stochastic competitive learning by particle position initialization, parameter
optimization and particle domination ability self-adaptive. The experiment result shows
that each improved method improves the accuracy of the algorithm, and the F1 score of
the improved algorithm is 9.07% higher than that of original algorithm. 相似文献