Intra-ply, inter-ply and FG hybrid composites based on basalt and poly-ester fibers: Flexural and impact properties

Ehsan Fadayee Fard,Hassan Sharifi,Majid Tehrani,Ehsan Akbari Techno-Press 2023 Advances in materials research Vol.12 No.1

Basalt and poly-ester fibers along with epoxy resin were used to produce inter-ply, intra-ply and functionally gradient hybrid composites. In all of the composites, the relative content of basalt fiber to poly-ester fiber was equal to 50 percent. The flexural and charpy impact properties of the hybrid composites are presented with particular regard to the effects of the hybrid types, stacking sequence of the plies, loading direction and loading speed. The results show that with properly choosing the composition and the stacking sequence of the plies; the inter-ply hybrid composites can achieve better flexural strength and impact absorption energy compared to the intra-ply and functionally gradient composites. The flexural strength and impact absorption energy of the functionally gradient hybrid composites is comparable to, or higher than the intra-ply sample. Also, by increasing the loading speed, the flexural strength increases while the flexural modulus does not have any special trend.

Fluid-structure coupling of concentric double FGM shells with different lengths

Ehsan Moshkelgosha,Ehsan Askari,정경훈,Ali Akbar Shafiee 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.2

The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged inside the stored fluid. The container shell is made of functionally graded materials with mechanical properties changing through its thickness continuously. The baffle made of steel is fixed along its top edge and submerged inside fluid such that its lower edge freely moves. The developed approach is verified using a commercial finite element computer code. Although the model is presented for a specific case in the present work, it can be generalized to investigate coupling of shellplate structures via fluid. It is shown that the coupling between concentric shells occurs only when they vibrate in a same circumferential mode number, n. It is also revealed that the normalized vibration amplitude of the inner shell is about the same as that of the outer shell, for narrower radial gaps. Moreover, the natural frequencies of the fluid-coupled system gradually decrease and converge to the certain values as the gradient index increases.

The tissue expression of MCT3, MCT8, and MCT9 genes in women with breast cancer

Sohrabi Ehsan,Moslemi Masoumeh,Rezaie Ehsan,Nafissi Nahid,Khaledi Mansoor,Afkhami Hamed,Fathi Javad,Zekri Ali 한국유전학회 2021 Genes & Genomics Vol.43 No.9

Background Breast cancer (BC) is a common malignancy with a high mortality rate. Malignant cell transformation is associated with metabolic changes. One group of proteins that are afected is the monocarboxylate transporters (MCTs-SLC16A). The MCTs comprise 14 members, and they play an important role in the growth, proliferation, and metabolism of cancer cells by transporting monocarboxylates such as lactate, pyruvate and thyroid hormones. Objective We aimed to evaluate the expression of MCT3 (SLC16A8), MCT8 (SLC16A2) and MCT9 (SLC16A9) genes in breast cancer samples, comparing to normal adjacent tissues. Methods Forty paired breast cancer tumor samples, the adjacent non-tumor and fve healthy tissues were collected. Three cancer cell lines (MCF-7, MDA-MB-231, and SKBR3) were also analyzed. The expression of SLC16A8, SLC16A2 and SLC16A9 were assessed using quantitative real-time PCR. The relationship between gene expression with the pathological features of the tumors, and the hormone receptors status of the patient’s tumors were also analyzed. Results There was a signifcantly lower expression of the MCT3 gene in tumor samples compared to adjacent normal tissue and healthy samples (p value<0.05). There was a signifcant diference in the expression of all three candidate genes between the BC tissues and normal tissues, and for the, tissues with diferent hormone receptor status and the molecular subtypes. Altered MCT8 and MCT9 gene expression was associated with a reduced survival Conclusion MCT3 expression is signifcantly downregulated in breast cancer tissue. MCT3 may represent a novel therapeutic target in breast cancer patients, or in some hormone receptor subgroups.

Power-aware performance analysis of self-adaptive resource management in IaaS clouds

Ataie, Ehsan,Entezari-Maleki, Reza,Etesami, Sayed Ehsan,Egger, Bernhard,Ardagna, Danilo,Movaghar, Ali North-Holland 2018 Future generations computer systems Vol.86 No.-

<P><B>Abstract</B></P> <P>In this paper, Stochastic Activity Networks (SANs) are used to model and evaluate the performance and power consumption of an Infrastructure-as-a-Service (IaaS) cloud. The proposed SAN model is scalable and flexible, yet encompasses some details of an IaaS cloud, such as Virtual Machine (VM) provisioning, VM multiplexing, and failure/repair behavior of VMs. Using the proposed SAN, a power-aware self-adaptive resource management scheme is presented for IaaS clouds that automatically adjusts the number of powered-on Physical Machines (PMs) regarding variable workloads in different time intervals. The proposed scheme respects user-oriented metrics by avoiding Service Level Agreement (SLA) violations while taking provider-oriented metrics into consideration. The behavior of the proposed scheme is analyzed when the arriving workload changes, and then its performance is compared with two non-adaptive baselines based on diverse performance and power consumption measures defined on the system. A validation of the proposed SAN model and the resource management scheme against an adapted version of the CloudSim framework is also presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An analytical model is proposed for Infrastructure-as-a-Service (IaaS) clouds taking several details of such systems into consideration. </LI> <LI> A self-adaptive power-aware and Service Level Agreement (SLA)-aware resource management scheme is presented for cloud systems. </LI> <LI> The presented scheme adjusts the number of powered-on Physical Machines (PMs) according to the input workload. </LI> <LI> A validation of the proposed model and scheme against the CloudSim framework is presented. </LI> </UL> </P>

Numerical analysis of sheet cavitation on marine propellers,considering the effect of cross flow

Ehsan Yari,Hassan Ghassemi 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.4

The research performed in this paper was carried out to investigate the numerical analysis of the sheet cavitation on marine propeller. The method is boundary element method (BEM). Using the Green’s theorem, the velocity potential is expressed as an integral equation on the surface of the propeller by hyperboloid-shaped elements. Employing the boundary conditions, the potential is determined via solving the resulting system of equations. For the case study,a DTMB4119 propeller is analyzed with and without cavitating conditions. The pressure distribution and hydrodynamic performance curves of the propellers as well as cavity thickness obtained by numerical method are calculated and compared by the experimental results. Specifically in this article cavitation changes are investigate in both the radial and chord direction. Thus, cross flow variation has been studied in the formation and growth of sheet cavitation. According to the data obtained it can be seen that there is a better agreement and less error between the numerical results gained from the present method and Fluent results than Hong Sun method. This confirms the accurate estimation of the detachment point and the cavity change in radial direction.

Inhibition of quorum sensing in Pseudomonas aeruginosa by two herbal essential oils from Apiaceae family

Ehsan Sepahi,Saeed Tarighi,Farajollah Shahriari Ahmadi,Abdolreza Bagheri 한국미생물학회 2015 The journal of microbiology Vol.53 No.2

Ferula (Ferula asafoetida L.) and Dorema (Dorema aucheri Bioss.) both from Apiaceae family were tested for their antiquorum sensing (QS) activity against Pseudomonas aeruginosa. Both essential oils exhibited anti-QS activity at 25 μg/ml of concenteration. At this concenteration Ferula fully abolished and Dorema reduced the violacein production by C. violaceum. Pyocyanin, pyoverdine, elastase and biofilm production were decreased in Ferula oil treatments. Dorema oil reduced pyoverdine and elastase production, while pyocyanin and biofilm production were not affacted. Expresion analysis of QS-dependent genes confirmed our phenotypic data. Our data introduced native Dorema and Ferula plants as novel QS and virulence inhibitors.

Coalescence of two at-rest equal-sized drops in static vapor of the same material: A lattice Boltzmann approach

Ehsan Amiri Rad 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.9

We studied the coalescence of two stationary equal-sized droplets in static vapor using a lattice Boltzmann approach. The non-idealbehavior of one-component, two-phase flow is coupled with BGK lattice Boltzmann by defining a suitable free energy function, whichproduces the correct equilibrium conditions of the flow. The accuracy of developed model is confirmed by calculating droplet surfacetension for different conditions and comparing that with theoretical results. Finally, the coalescence process of two equal-sized drops ismodeled and effective parameters on critical gap of coalescence are investigated. The results show that for two at-rest and equal-sizeddrops in a static flow, the critical gap of coalescence only depends on thickness of the interface, and other parameters such as dropletradius, density ratio and surface tension do not have influences on that directly.

Energy Trade and Economic Integration between the Commonwealth Independent States and China

Ehsan Rasoulinezhad 세종대학교 경제통합연구소 2020 Journal of Economic Integration Vol.35 No.1

The main purpose of this study is to conduct the traditional economic, political, and geopolitical factors to uncover the relationship between different factors and the volume of China's energy importing from the Commonwealth of Independent States. We conducted a panel data framework for our sample during the period between 2001 and 2017. My paper's main findings reveal that the economic sizes of Commonwealth of Independent States members have a positive effect on China's energy import flow from the Commonwealth of Independent States. Furthermore, the amount of the Commonwealth of Independent States 's annual energy exports to countries other than China has a significant negative effect on the level of China's energy imports from the Commonwealth of Independent States. In regard to geographic distance, findings showed a negative sign of its coefficient meaning that geographical distance might decelerate energy trade flows running from the Commonwealth of Independent States to China. I also discovered that China's foreign direct investment in Commonwealth of Independent States states might determine and accelerate energy export flows running from the Commonwealth of Independent States to China. Finally, our major findings proved the evidence of a positive relationship between political risk in the Commonwealth of Independent States and the energy importing flows of China.

Prediction of Proton Exchange and Bacterial Growth on Various Substrates Using Constraint-based Modeling Approach

Ehsan Motamedian,Fereshteh Naeimpoor 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.5

Proton exchange between cells and medium is one of the most important factors affecting culture pH, and hence its prediction is advantageous. In this research,proton exchange flux across the cell membrane was predicted using a genome-scale model. Calculated proton exchange flux was then exploited as a criterion to predict the trends and intensities of pH changes in cultures of Bacillus subtilis containing various C-sources, i.e. glucose,sucrose, glycerol, lactate, and citrate, as well as N-sources,i.e. ammonium chloride, sodium nitrate, urea, and histidine. The results showed that glucose, sucrose, and glycerol lowered culture pH as compared to citrate and lactate,which raised it. With regard to N-sources, the model predicted that ammonium chloride lowered culture pH while other sources raised pH. Furthermore, maximum theoretical biomass yield using the various C&N-sources was calculated, and sensitivity of microbial growth to proton exchange flux was investigated using robustness analysis to identify the effect of pH on growth of B. subtilis using different substrates. Finally, the effect of ammonium nitrate, a widely used nitrogen source, on growth of B. subtilis was studied. Experimental data obtained by cultivation of B. subtilis DSM 3256 on mineral salt media containing various C&N-sources were used to confirm model predictions. Model predictions were in good agreement with the experimental results for all of the examined C-sources as well as ammonium chloride and sodium nitrate as N-sources. However, the predictions for the N-sources urea and histidine showed deviations,possibly because these two compounds serve as both C&N-sources.

A Giant Sacrococcygeal Chordoma: A Case Report

Ehsan Keykhosravi,Amin Tavallaii,Mona Maftouh,Behzad Aminzadeh 대한뇌종양학회 2022 Brain Tumor Research and Treatment Vol.10 No.1

Sacrococcygeal chordoma is a rare malignant bone tumor. Although there are tough membranes such as the periosteum and presacral fascia (which resist transgression by the tumors), chordoma usually invades the rectal wall. The serious problem with these tumors is the late diagnosis and its high likeli- hood to become enlarged. The main treatment options for this tumor is surgical resection, radiothera- py, and chemotherapy. Due to the tumor vicinity to important organs such as bladder and its neurovas- cular structures, it makes surgical excision extremely challenging. The aim of this study is to describe a 50-year-old man with a giant sacrococcygeal mass. The novelty of this case report is the huge and unique size of the tumor which has not reported previously as well the special surgical approaches performed to remove the tumor.