Novel graphene‐based optical MEMS accelerometer dependent on intensity modulation

Mehdi Ahmadian,Kian Jafari,Mohammad Javad Sharifi 한국전자통신연구원 2018 ETRI Journal Vol.40 No.6

This paper proposes a novel graphene‐based optical microelectromechanical systems MEMS accelerometer that is dependent on the intensity modulation and optical properties of graphene. The designed sensing system includes a multilayer graphene finger, a laser diode (LD) light source, a photodiode, and integrated optical waveguides. The proposed accelerometer provides several advantages, such as negligible cross‐axis sensitivity, appropriate linearity behavior in the operation range, a relatively broad measurement range, and a significantly wider bandwidth when compared with other important contributions in the literature. Furthermore, the functional characteristics of the proposed device are designed analytically, and are then confirmed using numerical methods. Based on the simulation results, the functional characteristics are as follows: a mechanical sensitivity of 1,019 nm/g, an optical sensitivity of 145.7 %/g, a resonance frequency of 15,553 Hz, a bandwidth of 7 kHz, and a measurement range of ±10 g. Owing to the obtained functional characteristics, the proposed device is suitable for several applications in which high sensitivity and wide bandwidth are required simultaneously.

Biosorptive removal of organic dyes using natural gums-based materials: A comprehensive review

Moslem Ahmadian,Hossein Derakhshankhah,Mehdi Jaymand 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.124 No.-

Treatment of industrial wastewater containing synthetic dyes is inevitable owing to negative effects ofdyes on the environment and human health. Consequently, numerous strategies, including filtration,photochemical, coagulation, oxidation process, biological, ion exchange, and adsorption have beenapplied for dyes removal. Amongst, the adsorption process is a promising method with superior features,such as cost-effectiveness, high selectivity and removal efficiency, easy operation, and recyclability of theadsorbents. Natural gums are naturally-occuring polysaccharides that possessing excellent properties,including their renewability, surface functionality, low cost, biocompatibility, abundancy, biodegradability,and non-toxic nature that can be used as bioadsorbent in dye remediation of industrial wastewater. Nevertheless, limitations such as low surface area, poor mechanical properties, low thermal stability,high hydrophilicity and water solubility, and low adsorption capability should be circumvented to affordideal adsorbents. In this context, various techniques, including derivatization, polymer grafting, crosslinking,nanomaterials incorporation, blending with other polymers, and combination of theseapproaches have been employed for improving their properties. Considering these facts, this assayfocused on presenting a comprehensive summary, recent progresses and future direction regarding theapplication of natural gums-based adsorbents for removal of synthetic dyes.

Fabrication and Characterization of Polyphosphazene/ Calcium Phosphate Scaff olds Containing Chitosan Microspheres for Sustained Release of Bone Morphogenetic Protein 2 in Bone Tissue Engineering

Adnan Sobhani,Mohammad Rafienia,Mehdi Ahmadian,Mohammad-Reza Naimi-Jamal 한국조직공학과 재생의학회 2017 조직공학과 재생의학 Vol.14 No.5

Bone morphogenetic protein 2 has a major role in promoting bone regeneration in tissue engineering scaffolds. Growth factor release rate is a remaining crucial problem in these systems. The aim of this study was to fabricate and characterize a novel calcium phosphate/polyphosphazenes porous scaffold for the sustained release of bone morphogenetic protein 2 in bone tissue engineering. Polyphosphazenes were substituted with 2-dimethylaminoethanol and evaluated by GPC, NMR, and in vitro degradation. Calcium phosphate porous samples were prepared from hydroxyapatite nanoparticles and naphthalene using the sintering method at 1250 C before being composited with poly(dimethylaminoethanol)phosphazenes containing chitosan microspheres loaded with bone morphogenetic protein 2. The characteristics and biodegradability of the product were evaluated by SEM, XRD, and in vitro degradation. Moreover, the release rate and mechanical properties of the scaffolds were investigated. The release behavior was found to be sustained since the scaffolds had been fabricated from polyphosphazenes with a low degradation rate. The release rates of the scaffolds were observed to increase with increasing chitosan microspheres content from 10 to 30%. The bioactivity of the scaffolds depended on the release rate of growth factor while bone morphogenetic protein 2 was able to induce an osteoblast proliferation. The results of cell adhesion and cell viability tests showed that scaffolds displayed a non-toxic behavior and western blot analyses confirmed that the scaffolds loaded with growth factor increased the osteogenic differentiation potential of cells when compared with scaffolds alone. These results demonstrate that these scaffolds can be successfully utilized in bone tissue engineering.

Magneto-Rheological 유체를 이용한 엔진마운트의 준능동제어

Young Kong Ahn,Mehdi Ahmadian,양보석(Bo-Suk Yang),Shin Morishita 한국소음진동공학회 1999 한국소음진동공학회 학술대회논문집 Vol.1999 No.6

INTEGRATED VEHICLE DYNAMICS SYSTEM THROUGH COORDINATING ACTIVE AERODYNAMICS CONTROL, ACTIVE REAR STEERING, TORQUE VECTORING AND HYDRAULICALLY INTERCONNECTED SUSPENSION

Arash Hosseinian Ahangarnejad,Stefano Melzi,Mehdi Ahmadian 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5

This paper investigates integrated vehicle dynamics control through coordinating active aerodynamics control, active rear steering, torque vectoring and hydraulically interconnected suspension for improving the overall vehicle performance including handling, stability, and comfort. After developing each chassis control system, it is tested by various manoeuvres in order to assess each subsystem. Then, a rule-based coordinate system is proposed for integrated control of the four chassis control systems. Simulation investigation is performed to display the effectiveness of the proposed integrated vehicle dynamics system. Results demonstrate that the proposed control scheme is able to enhance the multiple performance indices of the vehicle including both the ride comfort, and the lateral stability, compared to the non-integrated control system.

Preparation and characterization of carbon felt/carbon composites by chemical vapor infiltration process

Elahi Davaji Hossein,Shamoradi Fatemeh,Panjepour Masoud,Ahmadian Mehdi 한국탄소학회 2022 Carbon Letters Vol.32 No.1

The current study was intended to synthesize and characterize the physical, chemical, and mechanical properties of carbon/carbon (C/C) composites using the chemical vapor infiltration (CVI) process. To that end, carbon fiber felt (CF) was used as a preform, and methane and hydrogen were employed as reactive and carrier gases, respectively. After deciding on the optimum temperature (1050 °C), the composite samples were produced at different times (0–195 h). Then the samples were studied for their phase and microstructure characteristics using XRD, SEM, FESEM, FTIR, and Raman spectroscope. The results showed that by increasing the CVI process time up to 195 h, the density of the produced samples increased from 0.20 to 1.62 g/cm3, and the specific surface area decreased from 58.78 to 0.23 m2/g. Also, by increasing the process duration, the deposition rate decreased due to the reduction of the available surface for carbon deposition. In other words, due to the increase in density, and decrease in both porosity and specific surface area, the thermal conductivity coefficient and the bending strength of the samples increased. The composite specimens' SEM images of the fracture surface indicated a weak interface between the carbon fibers and the carbon layer developed by the CVI process. The structural analyses showed that the morphology of carbon growth during the CVI process was initially laminar, but changed to rough-laminar (RL) with the higher duration of the CVI process.

The combination of exercise training and Zataria multiflora supplementation increase serum irisin levels in postmenopausal women

Abbass Ghanbari-Niaki,Ayoub Saeidi,Mehdi Ahmadian,Leila Gharahcholo,Nooshin Naghavi,Mohammad Fazelzadeh,Soleiman Mahjoub,Stephen Myers,Andrew Williams 한국한의학연구원 2018 Integrative Medicine Research Vol.7 No.1

Background: We examined the effect of antioxidant supplementation and exercise on irisin within postmenopausal women. Methods: Forty-eight participants (age: 55.7 ± 4.9 years; weight: 68.0 ± 6.3 kg; BMI 27.0 ± 2.7; mean ± SD) were randomized into four groups for the eight week intervention: control group (CG; n = 12), resistance training group (RTG; n = 12), supplementation with Zataria multiflora group (ZG; n = 12), or supplementation with Z. multiflora and resistance training group (ZRTG; n = 12). RTG and ZRTG performed circuit resistance training, and both ZG and ZRTG consumed 500 mg of Z. multiflora every day during the intervention. Blood samples were taken 48 hours before and after the intervention. Results: There was a significant difference in irisin at post-training, with greater levels in ZRTG compared to CG. A significant increase was noted for irisin at post-training compared to pre-training for ZG, RTG, and ZRTG. Moreover, we identified a significant decrease in malondialdehyde in the RTG and ZRTG groups and increase in glutathione in the ZG, RTG, and ZRTG groups when compared to CG. Conclusion: These findings showed that exercise, Z. multiflora supplementation or their combination led to an increase in irisin.

Improving the Chitinolytic Activity of Bacillus pumilus SG2 by Random Mutagenesis

( Majid Vahed ),( Ebrahim Motalebi ),( Garshasb Rigi ),( Kambiz Akbari Noghabi ),( Mohammad Reza Soudi ),( Mehdi Sadeghi ),( Gholamreza Ahmadian ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.11

Bacillus pumilus SG2, a halotolerant strain, expresses two major chitinases designated ChiS and ChiL that were induced by chitin and secreted into the supernatant. The present work aimed to obtain a mutant with higher chitinolytic activity through mutagenesis of Bacillus pumilus SG2 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on chitin agar and subsequent formation of halos, the mutated strains were examined for degradation of chitin under different conditions. A mutant designated AV2-9 was selected owing to its higher chitinase activity. To search for possible mutations in the whole operon including ChiS and ChiL, the entire chitinase operon, including the intergenic region, promoter, and two areas corresponding to the ChiS and ChiL ORF, was suquenced. Nucleotide sequence analysis of the complete chitinase operon from the SG2 and AV2-9 strains showed the presence of a mutation in the catalytic domain (GH18) of chitinase (ChiL). The results demonstrated that a single base change had occurred in the ChiL sequence in AV2- 9. The wild-type chitinase, ChiL, and the mutant (designated ChiLm) were cloned, expressed, and purified in E. coli. Both enzymes showed similar profiles of activity at different ranges of pH, NaCl concentration, and temperature, but the mutant enzyme showed approximately 30% higher catalytic activity under all the conditions tested. The results obtained in this study showed that the thermal stability of chitinase increased in the mutant strain. Bioinformatics analysis was performed to predict changes in the stability of proteins caused by mutation.