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.

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>

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.

Effect of medium viscosity on rheological characteristics of magnetite-based magnetorheological fluids

Ehsan Esmaeilnezhad,Seyed Hasan Hajiabadi,최형진 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

This study examined the magnetorheological (MR) behavior of magnetite-based MRfluids according tothe magnetite concentration, magneticfield strength, and different viscosity of silicone oil as the carrierfluid. To this end, an experimental design was chosen to decrease the experimental error and provide abetter rheological interpretation. Theflow behavior parameters increased remarkably with increasingmedium viscosity and nanoparticles (NPs) concentration, whereas the magneticfield strength had amilder effect, exhibiting a saturation value above which its effect became almost negligible. Moreover,both the Bingham plastic and power law models were found tofit theirflow behaviors well. Almost all thecritical rheological parameters of the aforementioned models experienced remarkable improvementafter increasing the magneticfield strength, NPs concentration and carriedfluid viscosity. In addition,mathematical correlations were derived to model each of the rheological parameters such as plasticviscosity and yield stress (for Binghamfluid model) and the consistency and power-law indices (forpower-law model).

Modelling Mass Flux Within a Frost Layer on a Cold Flat Plate

Ehsan Gholamalizadeh,Jae Dong Chung 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.11

Novel combinatorial extensions to breakthrough curve modeling of an adsorption column — Depth filtration hybrid process

Ehsan Salehi,Mahdi Askari,Yaser Darvishi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.86 No.-

This work introduces novel scenarios for the breakthrough curve modeling of an adsorption column/depthfiltration hybrid system. Four well-known theoretical breakthrough models including Thomas,Adams–Bohart, Yoon–Nelson, and BDST were employed to describe the normalized concentrationprofiles. In thefirst approach, the theoretical models were combined for better estimation of thebreakthrough curves and the Thomas/Yoon–Nelson and Thomas/BDST combinations were obtained asthe best extensions. In the second approach, an adsorption-transport model was developed for the depthfilter to obtain the transient concentration gradient across thefilter medium thickness. The model wasthen combined with the theoretical breakthrough models to predict the adsorption columnbreakthrough curves. Results revealed that a decrease in the feedflowrate andfilter pore size couldintensify the concentration polarization on thefilter surface. Both model extensions could successfullyapproximate the breakthrough curves of the hybrid system with more than 99% agreement withthe experimental data, while the prediction accuracy of the original breakthrough models seldomexceeds 93%.

The effect of the Iranian family approach-specific course (IrFASC) on obtaining consent from deceased organ donors’ families

Ehsan Radi,Matin Ghanavati,Batoul Khoundabi,Jamal Rahmani,Katayoun Nahafizadeh,Mahdi Shadnoush,Behrooz Broumand,Omid Ghobadi 대한이식학회 2022 Korean Journal of Transplantation Vol.36 No.4

Background: A family approach and obtaining consent from the families of potential brain-dead donors is the most important step of organ procurement in countries where an opt-in policy applies to organ donation. Health care staff’s communication skills and ability to have conversations about donation under circumstances of grief and emotion play a crucial role in families’ decision-making process and, consequently, the consent rate. Methods: A new training course, called the Iranian family approach-specific course (IrFASC), was designed with the aim of improving interviewers’ skills and knowledge, sharing experiences, and increasing coordinators’ confidence. The IrFASC was administered to three groups of coordinators. The family consent rate of participants in the same intervals (12 months for group 1, 6 months for group 2, and 3 months for group 3) was measured before and after the training course. The Wilcoxon signed-rank test was used to make comparisons. Results: The family consent rate was significantly different for all participants before and after the training, increasing from 50.0% to 62.5% (P=0.037). Furthermore, sex (P=0.005), previous training (P=0.090), education (P=0.068), and duration of work as a coordinator (P=0.008) had significant effects on the difference in families’ consent rates before and after IrFASC. Conclusions: This study showed that the IrFASC training method could improve the success of coordinators in obtaining family consent.

CO2/N2 Separation Using Polyvinyl Chloride Iso-Phthalic Acid/ Aluminium Nitrate Nanocomposite Membrane

Ehsan Kianfar,Mahmoud Salimi,Farshid Kianfar,Mehran Kianfar,Seyyed Ali Hasan Razavikia 한국고분자학회 2019 Macromolecular Research Vol.27 No.1

In this paper, composite membranes based on polyvinyl chloride (PVC) has been prepared and then filled with 0.125-0.250 wt% of iso-phthalic acid/aluminium nitrate nanoparticles. All of the polymeric and nanocomposite membranes were fabricated by solution casting using tetrahydrofuran (THF) solvent. The performance of the prepared membranes was studied for CO2/N2 at the feed pressure of 2.5, 3, and 3.5 bar at 35 °C. Results showed that in most cases, increasing the percentage of PVC increased the permeability of CO2/N2. Also, with the addition of iso-phthalic acid/aluminium nitrate nanoparticles in the membrane, gas permeability in all cases increased. The highest gas pair selectivity for CO2/N2 could be obtained from PVC (30wt%) loaded with 0.250wt% of iso-phthalic acid/aluminium nitrate nanoparticles. For characterization of samples, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used. These results also suggest that PVC membranes with the higher loading percentage of nanoparticles are good candidates for the CO2/N2 separation, offering better selectivity for CO2/ N2 in the range of 63.78 to 230.42, depending on the loading percentage.

Knowledge of and attitudes toward HIV/AIDS among Iranian women

Ehsan Zarei,Roghayeh Khabiri 한국역학회 2018 Epidemiology and Health Vol.40 No.-

OBJECTIVES: This study investigated the knowledge of Iranian women about HIV/AIDS and whether they had accepting attitudes towards people living with human immunodeficiency virus (HIV), and sought to identify factors correlated with their knowledge and attitudes. METHODS: The data analyzed in the present study were taken from Iran’s Multiple Indicator Demographic and Health Survey, a national survey conducted in 2015. In total, 42,630 women aged 15-49 years were identified through multi-stage stratified cluster random sampling and interviewed. Associations of the socio-demographic characteristics of participants with their knowledge and attitudes were examined using multiple logistic regression analysis. RESULTS: The majority (79.0%) of Iranian women had heard about HIV/AIDS, but only 19.1% had a comprehensive knowledge. In addition, only 15.4% of women had accepting attitudes toward people with HIV. Being older, married, more highly educated, and wealthier were factors associated with having more comprehensive knowledge of HIV/AIDS, and living in urban areas was associated with having more positive attitudes toward people with HIV. CONCLUSIONS: The relatively poor knowledge of Iranian women and the low prevalence of accepting attitudes toward people living with HIV highlight the need to develop policies and interventions to overcome this issue, which would be a basis for further prevention of HIV/AIDS in Iran.