Design of liquid-liquid extraction system

The unit operation of liquid-liquid extraction has developed enormously in the last 20 years and is now recognized as one of the most important techniques for the physical separation and refining of industrial liquids. For years the conventional apparatus used for liquid-liquid extraction has been towers employing countercurrent flow of the liquids and equipped with various means to increase the interfacial area. The countercurrent column consists of a tower through which flows a continuous phase while countercurrent to this flow is a stream of droplets (the dispersed phase). Provision is made for dispersing one phase with a settling region at each end of the tower. This arrangement corresponds to the single spray tower in absorption but in practice such a simple apparatus has a very low efficiency due to incomplete mixing and coalescing of the original droplets. A recent design for the improvement of liquid-liquid extraction equipment involves a column utilizing countercurrent flow, mechanical agitation, and baffled settling zones. In one case, the column is fitted with sieve plates that may be moved up and down relative to the liquid producing the agitation, while the liquids flow countercurrently through the plates. Settling takes place during the pauses between the strokes. The operation and construction or this column can be simplified by using stationary plates and agitating by imparting a reciprocating motion to the liquids relative to the plates. Another possible design is a column which consists of a number of compartments formed by a series of stator rings, with a rotating disc centered in each compartment and supported by a rotating shaft. This apparatus has been proved to be highly efficient, simple, and cheap to operate, and easy to maintain. The purpose of this thesis was to design a liquid-liquid extraction system containing (1) a pulse extraction column and (2) a rotating-disc contactor column for non-hazardous, simulated, nuclear fuel processing. The system was designed such that the two columns may be operated (1) separately, (2) as a countercurrent system, and (3) as a multiple contact system --Introduction, pages 1-2

Recommender System Based on Semantic Similarity

In electronic commerce, in order to help users to find their favourite products, we essentially need a system to classify the products based on the user's interests and needs to recommend them to the users. For the same reason the recommendation systems are designed to help finding information in large websites. They are basically developed to offer products to the customers in an automated fashion to help them to do conveniently their shopping. The developing of such systems is important since there are often a large number of factors involved in purchasing a product that would make it difficult for the customer to make the best decision. Finding relationship among users and relationships among products are important issue in these systems. One of relations is similarity. Measure similarity among users and products is used in the pure methods for calculating similarity degree. In this paper, semantic similarity is used to find a set of k nearest neighbours to the target user, or target item. Thus, because of incorporating semantic similarity in the proposed recommendation system, from the experimental results, the high accuracy was obtained on private building company dataset in comparison with state-of-the-art recommender systems.DOI:http://dx.doi.org/10.11591/ijece.v3i6.393

Effects of Lavandula angustifolia essential oil on Interleukin 23 and Brain-Derived neurotrophic factor gene expression in peripheral blood mononuclear cells of multiple sclerosis patients

Introduction: We aimed to determine the effect of lavandula angustifolia essential oil (LEO) on IL-23 and brain-derived neurotrophic factor (BDNF) gene expressions in peripheral blood mononuclear cells (PBMCs) of relapse-remitting MS (RRMS) patients.Methods: LEO was prepared using the hydrodistilation method on the plants aerial parts.    8 female RRMS patients and 8 healthy sex and age matched controls were entered into this study. PBMC cells were separated using Ficoll method and were treated with a concentration of 225 µg/ml LEO which and then the mRNAs were used for determining the effects of LEO on IL-23 and BDNF gene expressions using Quantitative Real Time PCR technique. Moreover in order to determine the anti-inflammatory effects of LEO, we measured the gene expression of IL-6 and IL-23 in stimulated healthy PBMC cells treated with LEO.Results: Results showed that there is no significant difference between PBMC of patients compared to healthy controls in case of IL-23 gene expression. Moreover, LEO has no significant effect on gene expression of IL-23 in PBMC of neither patients nor control. Also the results showed that BDNF gene expression is reduced to 41% compared to healthy controls and LEO can increase the BDNF gene expression by 81% in patients PBMCs. Moreover we observed that LEO can significantly reduce the LPS stimulated IL-6 gene expression in healthy PBMCs but had no significant effect on IL-23 gene expression.Conclusion: The present study demonstrated that L.angustifolia essential oil may have a protective effect against neuron damage via increasing the gene expression of BDNF in PBMCs from RRMS patients. However, further studies are necessary to confirm our results

Stabilization of arbitrary switched nonlinear fractional order dynamical systems : application to Francis Hydro-Turbine Governing System

This paper is a theoretical and practical study on the stabilization of fractional order Lipschitz nonlinear systems under arbitrary switching. The investigated system is a generalization of both switched and fractional order dynamical systems. Firstly, a switched frequency distributed model is introduced as an equivalent for the system. Subsequently, a sufficient condition is obtained for the stabilizability of the system based on the Lyapunov approach. Finally, the results are extended to synthesis mode-dependent state feedback controller for the system. All the results are expressed in terms of coupled linear matrix inequalities, which are solvable by optimization tools and directly reducible to the conditions of the integer order nonlinear switching systems as well as the conventional non-switched nonlinear fractional order systems. The proposed method has various practical implications. As an example, it is utilized to control Francis hydro-turbine governing system. This system is represented as a switching structure and supposed to supply a load suffering abrupt changes driven by an arbitrary switching mechanism. The simulation results support the usefulness of the method

Post-COVID-19 chest imaging evaluation: which patients should be prioritized for follow-up pulmonary assessment?

Objectives: The current study evaluated the long‑term lung abnormalities based on initial and follow‑up chest computed tomography (CT) images of COVID‑19 patients and investigates the possible factors associated with them. Methods: One hundred and twenty‑four hospitalized COVID‑19 patients who received a follow‑up chest CT scan in three hospitals in Tehran between February 20, 2021 and September, 2021, were included. Based on the presence of persistent lesions in the follow‑up images, patients were divided into residual and nonresidual groups, and logistic regression analysis was performed to investigate the association between different disease characteristics and long‑term lung abnormalities. Results: The most frequent abnormality in the initial imaging was ground‑glass opacities which was observed in 95.3% of patients, and residual lesions were observed in 39.8% of patients at the follow‑up date. Patients in the residual group were generally older, more frequently suffered from hypertension and dyspnea, and had lower oxygen saturation and lymphocyte count, and lymphopenia was more prevalent among them. Moreover, patients in the residual group had higher initial lung involvement score, and the presence of lymphadenopathy and consolidation was more frequent among them. After adjustment for age, gender, and intervals between the two imagings, logistic regression results showed that hospitalization period, dyspnea, decreased oxygen saturation, decreased lymphocyte count, lymphopenia, consolidation, lymphadenopathy, and high initial lung involvement were strongly associated with the presence of long‑term abnormalities. Conclusion: The current study revealed multiple discrepancies between residual and nonresidual groups, which can be used to better identify the patients at risk of long‑term COVID‑19 lung complications

Relationship between Body Mass Index, Risk of Venous thromboembolism and Pulmonary Embolism: a systematic review and dose-response meta-analysis of cohort studies among four million participants

Background: The relationship between body mass index (BMI) and risk of venous thromboembolism (VTE) and pulmonary embolism (PE) is a controversial issue. This dose-response meta-analysis was performed to investigate the association between BMI and risk of VTE and PE incidence based on cohort studies. Method: A comprehensive systematic search was conducted up to August 2019 in MEDLINE/PubMed, SCOPUS, and Cochrane. DerSimonian and Laird random-effects models were run to estimate combined hazard ratios (HRs) with 95% confidence intervals (CIs). Dose-response analysis was also carried out based on BMI values. Results: Eleven articles with 16 arms and 3,910,747 participants were eligible for inclusion in this systematic review and meta-analysis. Pooled results showed a positive association between BMI and risk of VTE in the obese participants compared to participants classified in the normal BMI category (HR: 1.62, 95% CI: 1.29-2.04, I2 = 95%). Furthermore, results showed a significant association between lower BMI (underweight versus normal BMI category) and reduced risk of PE (HR: 0.80, 95% CI: 0.70-0.92, I2 = 9%) and higher risk of PE in obese versus normal BMI participants (HR: 2.24, 95% CI: 1.93-2.60, I2 = 0%). There was a significant linear relationship between BMI and risk of VTE (p < 0.001) and PE (p < 0.001). Conclusions: This systematic review and dose-response meta-analysis with 3,910,747 participants highlights obesity as a significant risk factor related to the incidence of VTE and PE. 2020 Elsevier LtdThe student research committee at Shahid Beheshti University of Medical Sciences was the financial supporter of this study (19163).Scopu

X-ray tomography studies on porosity and particle size distribution in cast in-situ Al-Cu-TiB2 semi-solid forged composites

X-ray computed tomography (XCT) was used to characterise the internal microstructure and clustering behaviour of TiB2 particles in in-situ processed Al-Cu metal matrix composites prepared by casting method. Forging was used in semi-solid state to reduce the porosity and to uniformly disperse TiB2 particles in the composite. Quantification of porosity and clustering of TiB2 particles was evaluated for different forging reductions (30% and 50% reductions) and compared with an as- cast sample using XCT. Results show that the porosity content was decreased by about 40% due to semi-solid forging as compared to the as-cast condition. Further, XCT results show that the 30% forging reduction resulted in greater uniformity in distribution of TiB2 particles within the composite compared to as-cast and the 50% forge reduction in semi-solid state. These results show that the application of forging in semi-solid state enhances particle distribution and reduces porosity formation in cast in-situ Al-Cu-TiB2 metal matrix composites

High-order modeling of circular cylindrical composite sandwich shells with a transversely compliant core subjected to low velocity impact

In this study, a high-order model for the analysis of circular cylindrical composite sandwich shells subjected to low-velocity impact loads is presented. The sandwich shell is composed of two composite face sheets and a transversely compliant core. The impact behavior of the cylindrical composite sandwich shells is described by a high-order sandwich shell theory. The interaction between the impactor body and the sandwich shell is approximated using a spring mass model. The present analysis is based on an iteration procedure, and yields analytic functions describing the contact force history. The contact force is considered to be distributed uniformly over a contact patch, the size of which depends on the magnitude of the impact load as well as the elastic properties and geometry of the impactor. Finally, the obtained results have been compared with the available experimental results, and a good correlation has been found