Science and Technology Research Institute

Tehrān, Iran

Science and Technology Research Institute

Tehrān, Iran
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Keivani M.,Shahrekord University of Medical Sciences | Khorsandi J.,Science and Technology Research Institute | Mokhtari J.,Islamic Azad University at Khorasgan | Kanani A.,Shiraz University of Medical Sciences | And 2 more authors.
Acta Astronautica | Year: 2016

Paddle-type and double-sided nanostructures are potential for use as accelerometers in flying vehicles and aerospace applications. Herein the pull-in instability of the cantilever paddle-type and double-sided sensors in the Casimir regime are investigated under the acceleration. The D'Alembert principle is employed to transform the accelerating system into an equivalent static system by incorporating the accelerating force. Based on the couple stress theory (CST), the size-dependent constitutive equations of the sensors are derived. The governing nonlinear equations are solved by two approaches, i.e. modified variational iteration method and finite difference method. The influences of the Casimir force, geometrical parameters, acceleration and the size phenomenon on the instability performance have been demonstrated. The obtained results are beneficial to design and fabricate paddle-type and double-sided accelerometers. © 2015 IAA. Published by Elsevier Ltd. All rights reserved.

Saidi P.,Islamic Azad University at Tehran | Sadeghi M.,Science and Technology Research Institute | Shirazi A.,Tehran University of Medical Sciences | Mahdavi S.R.,Tehran University of Medical Sciences | Mirzaii M.,Science and Technology Research Institute
International Journal of Low Radiation | Year: 2011

With increased demand for low 103Pd (palladium) seed sources, to treat prostate and eye cancers, new sources have been designed and introduced. This paper presents the two new palladium brachytherapy sources, IR03- 103Pd and IR04- 103Pd that have been developed at Agricultural, Medical & Industrial Research School. The dosimetric parameters, such as the dose rate constant Λ, the radial dose function g(r) and the anisotropy function F(r, θ), around the sources have been characterised using Version 5 Monte Carlo radiation transport code in accordance with the update AAPM Task Group No. 43 Report (TG-43U1). The results indicated the dose rate constant of 0.689 ± 0.02 and 0.667 ± 0.02 cGy h -1 U -1 for the IR03- 103Pd and IR04- 103Pd sources, respectively, which are in acceptable agreement with other commercial seeds. The calculated results were compared with published results for those of other source manufacturers. However, they show an acceptable dose distribution, using for clinical applications is pending experimental dosimetry. Copyright © 2011 Inderscience Enterprises Ltd.

Wongwilai W.,Center for Innovation in Chemistry | Wongwilai W.,Science and Technology Research Institute | Lapanantnoppakhun S.,Center for Innovation in Chemistry | Lapanantnoppakhun S.,Science and Technology Research Institute | And 3 more authors.
Talanta | Year: 2010

A modification of a webcam camera for use as a small and low cost detector was demonstrated with a simple lab-on-chip reactor. Real time continuous monitoring of the reaction zone could be done. Acid-base neutralization with phenolphthalein indicator was used as a model reaction. The fading of pink color of the indicator when the acidic solution diffused into the basic solution zone was recorded as the change of red, blue and green colors (%RBG.) The change was related to acid concentration. A low cost portable semi-automation analysis system was achieved. © 2010 Elsevier B.V. All rights reserved.

Jiang B.,Harbin Institute of Technology | Mostofizadeh A.,Harbin Institute of Technology | Mostofizadeh A.,Science and Technology Research Institute | Bai Y.P.,Harbin Institute of Technology | Huang Y.D.,Harbin Institute of Technology
Journal of Physical Chemistry B | Year: 2011

Preparation of the recording coating on the ink jet printing (RC-IJP) is proposed. The microstructure of RC-IJP was analyzed by scanning electron microscopy and atomic force microscope. The surface infiltration process of RC-IJP was studied. Fourier transform near-infrared (FT-NIR) spectra showed the combination and overtone vibrations information of the hydrogen-containing groups in RC-IJP structure. NIR spectra combined with partial least-squares methods were proposed for the noncontact analysis of the surface infiltration time and weight per unit area in RC-IJP. Forty-five samples were selected for the calibration sets of the surface infiltration time and weight per unit area, respectively. Spectral pretreatment method was used to develop robust calibration models. After the spectral pretreatment was optimized, the determination coefficient (R2) of the surface infiltration time and weight per unit area were 0.90 and 0.97, respectively. The analytical results showed that NIR spectra had significant potential for the analysis of the surface infiltration time and weight per unit area of RC-IJP. © 2011 American Chemical Society.

Heidari S.,University of Tehran | Mohammadizadeh M.R.,University of Tehran | Mahjour-Shafiei M.,University of Tehran | Larijani M.M.,Science and Technology Research Institute | Malek M.,Science and Technology Research Institute
Applied Physics A: Materials Science and Processing | Year: 2015

Titanium dioxide thin films were coated on soda-lime glass substrates using spray pyrolysis method with a thickness of 152 ± 10 nm. The films were irradiated with hydrogen ions at room temperature at various beam energies and fluences. Optimized incident beam energy and beam fluence were obtained to improve photocatalytic and hydrophilicity properties of TiO2 thin films by narrowing the band gap. Samples were characterized by scanning electron microscopy to study the surface morphology and by UV–Vis absorption spectroscopy to measure the band gap. The optical band gap of H-doped anatase TiO2 thin films irradiated with hydrogen beam with energies of 2 and 4 keV and a fluence of 1015 ions/cm2 was narrowed from 3.34 eV (before irradiation) to 3.04 and 2.92 eV (after irradiation), respectively. The irradiated sample with energy of 4 keV with a fluence of 1015 ions/cm2 has the best improvement. This is attributed to the contraction of the band gap and to the increase in surface active site. Furthermore, it was observed that photocatalytic and hydrophilicity properties of this sample were improved, as well. © 2015, Springer-Verlag Berlin Heidelberg.

Mohaddespour A.,University of Tehran | Abolghasemi H.,University of Tehran | Mostaedi M.T.,Science and Technology Research Institute | Habibzadeh S.,University of Tehran
Journal of Applied Polymer Science | Year: 2010

High density polyethylene- and polypropylene- clay nanocomposites are synthesized by melt blending, in which polyethylene glycol and polypropylene glycol are used as compatibilizers to increase the space of galleries. The morphology properties of nanocomposites are explored by X-ray diffraction and transition electron microscopy. The thermal conductivity coefficient (K) of nanocomposites is also measured along with the thermal stability. A conventional model based on developed Maxwell- Garnett formula is also established to predict the thermal conductivity of polymer/clay nanocomposites with clay loading. Morphology results indicate that two intercalated and exfoliated structures are formed. The established model satisfactorily predicts the K values of nanocomposites for low range of clay content. Thermogravimetric analysis shows remarkable thermal stability of anocomposites with 10 wt % of clay content. The deviation of our model from experimental result for 10 wt % of clay can be attributed to the intercalated structure of layered silicates into the matrices. Although the K values do not considerably increase in 5 wt % with respect to the increase occurs for 10 wt % of clay, but it increases about 28 and 37% at 50°C for high density polyethylene- and polypropylene-clay nanocomposites, respectively. © 2010 Wiley Periodicals, Inc.

Kheradmand F.,Tehran University of Medical Sciences | Kheradmand F.,Urmia University of Medical Sciences | Nourmohammadi I.,Tehran University of Medical Sciences | Modarressi M.H.,Tehran University of Medical Sciences | And 3 more authors.
Iranian Biomedical Journal | Year: 2010

Background: Zinc (Zn) as an important trace element is essential for testicular development and spermatogenesis. Molecular mechanism of Zn action in the reproductive system may be related to metal binding low-molecular weight proteins, metallothioneins (MT). Our objective was to determine the effect of Zn on two important isoforms of MT, MT1M and MT1G genes expression on testicular sertoli cells. Methods: Cultured sertoli TM4 cells were exposed to different concentrations of Zn at different time points. Cellular uptake of Zn was tested using flame atomic absorption spectrometry. The cellular viability and gene expression were assessed by MTT and real-time PCR methods, respectively. Results: The treated cells resulted in higher Zn concentration and cellular viability. The expression of MT1M and MT1G genes in the treated cells were greater than those of the untreated cells (P<0.05). In the high dosage treated group (100 and 500 μM), Zn concentration and expression of MT1M and MT1G genes increased three h after treatment; MT1G gene expression increased more at sixth h. At 18th h of treatment, the expression of both genes especially MT1G, increased dramatically while Zn concentration decreased. Conclusion: Since the increase of MT1G mRNA was coincident with cellular Zn level, it seems that MT1G has a more prominent role than MT1M in the homeostasis of Zn. In addition, Zn at dosage of 50 μM (pharmacologic concentration) may protect cells by increasing the expression of MT genes at longer periods.

Hafizi M.,University of Tehran | Abolghasemi H.,University of Tehran | Moradi M.,University of Tehran | Milani S.A.,Science and Technology Research Institute
Chinese Journal of Chemical Engineering | Year: 2011

In this study, strontium adsorption from sulfuric acid solution by different Dowex 50W-X ion exchange resins was investigated. Among these resins, Dowex 50W-X8 resin showed the maximum sorption of strontium from the aqueous solutions. The effect of pH, contact time, mass of resin, temperature, and concentration of interfering ions on strontium adsorption were evaluated to determine the optimum conditions of strontium sorption process. The kinetic models of sorption were analyzed using pseudo-first and pseudo-second order models. The results indicated that the pseudo-second order kinetic model was more appropriate than the other one. Moreover, the data obtained in this study were fitted into several sorption isotherm models and it was found that the Langmuir sorption isotherm shows the best fitting to the experimental data. © 2011 Chemical Industry and Engineering Society of China (CIESC) and Chemical Industry Press (CIP).

Akhavan O.,Sharif University of Technology | Azimirad R.,Malek-Ashtar University of Technology | Safa S.,Science and Technology Research Institute | Larijani M.M.,Science and Technology Research Institute
Journal of Materials Chemistry | Year: 2010

Carbon nanotube (CNT)-doped TiO2 thin films with various CNT contents were synthesized by sol-gel method for visible light photoinactivation of Escherichia coli bacteria. Post annealing of the CNT-doped TiO2 thin films at 450 °C resulted in anatase TiO2 and formation of Ti-C and Ti-O-C carbonaceous bonds in the film. By increasing the CNT content, the thin films could further inactivate the bacteria in the dark. Meanwhile, as the CNT content increased from zero to 40 wt% the effective optical band gap energy of the CNT-doped TiO2 thin films annealed at 450 °C decreased from 3.2-3.3 to less than ∼2.8 eV providing light absorption in the visible region. Concerning this, visible light photoinactivation of the bacteria on the surface of the films was found to be optimum for 20 wt% CNT content. The CNT-doped TiO2 thin films annealed at 450 °C showed a further improved photoinactivation of bacteria than the films annealed at 100 °C. The improvement in the visible light photocatalytic performance was assigned to the charge transfer through the carbonaceous bonds formed between the TiO2 and the CNT content of the films annealed at 450 °C, in contrast to the thin films annealed at 100 °C which contained no such effective bonds. © 2010 The Royal Society of Chemistry.

Sommano S.,Science and Technology Research Institute
Acta Horticulturae | Year: 2015

Cut Backhousia myrtifolia, an Australian native ornament suffers from a severe postharvest browning syndrome. Leaf and floral tissues of this plant contain high amounts of phenolics. This together with the latent stage of the oxidative enzymes polyphenol oxidase (PPO) and peroxidase (POD) makes the study of enzymatic properties difficult. Therefore, extraction and/or purification of these enzymes are important to overcome this problem. Samples were extracted with different phenol removing agents in sodium phosphate buffer (pH 6.8). PPO was activated by the addition of detergents (e.g., TritonX-100) and POD was extracted with mild treatments (e.g., sucrose solution). For partial enzyme purification, high temperature induced phase separation was used. Results showed that the inclusion of 5% polyvinylpolypyrrolidone (PVPP) in the extraction buffer was effective in removing polyphenols. Latent PPO in crude extract from B. myrtifolia leaves was activated using 2% v/v TTX-100, resulting in an almost 30-fold increase in activity. The same optimised extraction protocol also improved POD activity. While the phase separation step improved enzyme activity, it failed to maintain total protein content. Fresh extract of B. myrtifolia leaf tissue was, therefore, initially concentrated by filtering with an Amicon® PL-10 unit. However, concentrated endogenous phenolics interfered with enzyme activity. The results indicated that in studying PPO and POD in phenolic rich B. myrtifolia tissues, PVPP and high temperature-induced phase separation effectively improved enzymatic activity.

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