Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 426 journals)
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 Iranian Journal of Science and Technology, Transactions A : ScienceNumber of Followers: 0      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1028-6276 - ISSN (Online) 2364-1819 Published by Springer-Verlag  [2469 journals]
• U-Model-Based Dynamic Inversion Control for a Class of Nonlinear Dynamical
Systems

Abstract: Different types of techniques such as state-space linearization method and state-dependent parameter method are available for designing a control system of nonlinear plant although a little bit disadvantages generally occur. This paper deals with the adaptive controller which is based on recently developed U-Model-based control that has contributed a generic approach for modeling and controlling of various complicated systems. U-Model works with less number of parameters and variables, resulting a simple model configuration and applied to both linear and nonlinear dynamical systems. The single inverted pendulum on a cart being an unstable, nonlinear system is popularly applied as a benchmark for designing different control methodologies. Here, the control objective of this proposed work is to control the system in such a way that when the cart reaches the desired position, this inverted pendulum is balanced in an upright position with a particular angle, for achieving the aforementioned goal this paper has proposed U-Model dynamic inversion control, U-Model-based Model Reference Adaptive Control technique with Massachusetts Institute of Technology rule, Feedback linearization-based dynamic inversion technique and different Model Reference Adaptive Control methodologies. The novel contribution of the proposed work is to implement U-Model-based dynamic inversion technique where the inversion of the closed loop is performed for the development of the invariant controller, and ultimately, the necessity of solving complex diophantine equation is avoided. The MATLAB Simulink environment is applied for simulation of the proposed technique for determining the system performance.
PubDate: 2022-01-25

• Thermal, Structural Properties and Potential Dynamic Corrosion Study of
Ti-27Ni-21Nb-2Ta SMA

Abstract: In this study, Ti-27Ni-21Nb-2Ta (at. %) alloy was produced by arc-melting method. The physical and chemical properties of the alloys such as phase transformation temperatures, thermal activation energies, microstructure, electrochemical resistance, microhardness were investigated. Phase transformation temperatures were determined by DSC. The thermal activation energies of the alloy were calculated according to the Ozawa, Kissenger, and Takhor methods. The average thermal activation energy obtained according to these calculations was 56.35 kJ/mol. The optical microscope (OM) and SEM images showed that the alloy consisted of a dendritic structure. $$\beta$$ -Nb, B2, and B19/ peaks were found in the XRD pattern. Additionally, the crystallite size calculated by the Scherrer equation was estimated to be approximately 29.86 nm. Electrochemical investigation performed in SBF (artificial body fluid) at room temperature (RT) yielded a corrosion resistance rate of 9.38 × 10–6 mmpy analysis. The microhardness measurement of the alloys was taken from five distinct regions with an average of 376 HV0.3.
PubDate: 2022-01-21

• Platinum Coatings on SS304: Photocatalytic Dye Degradation Application

Abstract: This article successfully explains the coating of platinum on stainless steel sample (SS304) by simple direct current electrodeposition (DC) and pulse current electrodeposition (PC) method. All parameters of operation like current density temperature, duty cycle and pH were optimized. Various analysis techniques were used to categorize the platinum deposited sample, including electron dispersive spectroscopy, scanning electron microscopy and atomic force microscopy. Platinum-coated samples show excellent photocatalytic activity towards methylene blue. PC-coated sample shows better dye degradation performance than DC-coated sample which was monitored by using UV–Vis spectrophotometer.
PubDate: 2022-01-21

• Kinetic and Equilibrium Studies of Cr(VI) Adsorption Using

PubDate: 2022-01-21

• Estimation and Optimization for Step-Stress Accelerated Degradation Tests
Under an Inverse Gaussian Process with Tampered Degradation Model

Abstract: This paper addresses the estimation and optimization problems for a step-stress accelerated degradation test (SSADT) when a product’s degradation follows an inverse Gaussian (IG) process. Developing a link model to connect the deterioration measurements at different stress levels is a primary concern for this design issue. In this paper, we propose a tampered degradation model and construct a new framework to model the effect of changing stress from a level to another on the degradation path. Parameter estimates are obtained by both maximum likelihood and Bayesian methods. Under the constraint that the total experimental cost does not exceed a pre-specified budget, the optimal settings such as sample size, measurement frequency, and the number of measurements at each stress level are obtained. Finally, a real-world example is analyzed to illustrate the application of the proposed method. A notable finding was that enlarging the difference between the two stress levels makes the test more efficient.
PubDate: 2022-01-21

• Generalized Diffusion Characteristics of Calcium Model with Concentration
and Memory of Cells: A Spatiotemporal Approach

Abstract: The anomalous diffusion gives a more concise description of the biophysical process. One of the indispensable processes in the nervous system is the diffusion of free calcium ( $$\hbox {Ca}^{2+}$$ ) in nerve cells. An alteration/dysfunction of $$\hbox {Ca}^{2+}$$ leads to cell death and consequently manifests the early symptoms of many neurological disorders. In the context of this, we have presented a two-dimensional fractional-order reaction–diffusion model to develop a control mechanism of $$\hbox {Ca}^{2+}$$ dynamics. We have used the integral transform technique of arbitrary order to find the solution of the proposed $$\hbox {Ca}^{2+}$$ diffusion model. Due to the lack of smoothness of the solution, we have presented different schemes to obtain the closed-form solution. Finally, we have simulated the results in MATLAB software to show the diffusion characteristics on the $$\hbox {Ca}^{2+}$$ model and exhibit the control strategy to optimize calcium concentration. Furthermore, the obtained results are interpreted with the physiology of Parkinson’s. We observed that when space derivative moved from integer to fractional-order and the time derivative moved from fractional to integer-order we get an optimum control on $$\hbox {Ca}^{2+}$$ diffusion due to the intermediate memory and generalized diffusion characteristics of cells. Thus, we conclude that the generalized diffusion characteristics and memory of cells are enhanced the control strategy on the $$\hbox {Ca}^{2+}$$ diffusion model.
PubDate: 2022-01-21

• Steady-State and Transient Raman Gain Coefficients of Semiconductor
Magneto-plasmas (Calculated for n-InSb-CO2 Laser System)

Abstract: Assuming that the origin of stimulated Raman scattering (SRS) lies in third-order effective (Raman) susceptibility arising due to nonlinear induced polarization, we obtained expressions for steady-state and transient Raman gain coefficients of weakly polar semiconductors magneto-plasmas under various geometrical configurations. The threshold pump intensity and optimum pulse duration for the onset of transient SRS have been estimated. For numerical calculations, we consider n-InSb crystal at 77 K temperature as a Raman active medium irradiated by a pulsed CO2 laser. The dependence of Raman gain coefficients on doping concentration, external magnetostatic field and its inclination, scattering angle and pump pulse duration have been explored in detail with aim to determine suitable values of these controllable parameters to enhance Raman gain coefficients at lower threshold intensities, and to search the feasibility of efficient semiconductor nonlinear devices based on Raman nonlinearities. Most expectedly, the technological potentiality of weakly polar semiconductor magneto-plasmas as hosts for compression of scattered pulses and fabrication of efficient nonlinear devices such as frequency converters, Raman amplifiers and oscillators based on Raman nonlinearities have been established.
PubDate: 2022-01-13

• Blind Signature Protocol Based on Hidden Discrete Logarithm Problem Set in
a Commutative Algebra

Abstract: A new blind signature scheme is proposed which is characterized in that it is based on a hidden discrete logarithm problem defined in a finite commutative associative algebra. The used algebraic support represents a 4-dimensional commutative associative algebra defined over the ground finite field GF(p), commutative group of which possesses 4-dimensional cyclicity. The public key represents a triple of vectors contained in different cyclic subgroup of the multiplicative group. Correspondingly, three different blinding factors are used to insure the anonymity property of the introduced blind signature protocol.
PubDate: 2022-01-04

• Modify RF Cavity of 10 MeV Cyclotron to Improve the Beam Gain by Beam
Dynamic Analysis

Abstract: In this study, the central region and beam dynamic of a 10 MeV H− AVF cyclotron called IranCYC10 have been considered. The aim of this cyclotron is to accelerate H− ions up to 10 MeV energy and extract H+ ions to produce PET radioisotopes for medical applications. The cyclotron that is currently in fabrication consists of four sector magnets and two RF cavity parts which operate in 71 MHz frequency. The internal cold-cathode Penning Ion Gauge ion source that was used in this cyclotron, caused the central region design to become very sensitive and complex. In the first step, in order to obtain the optimized beam efficiency at the central region, the beam injection conditions, design of magnet center poles and adjustment of the pullers position have been determined. In contrast to conventional methods which design desired structure of central region based on trial and error, this design is carried out due to consideration of equilibrium orbit. In addition to the beam dynamic analysis in the early turns such as usual works, it is calculated until the extraction of the beam, as the second step. Our new developed code named BDIC (Beam Dynamic of Iran Cyclotron) has been developed for the calculation of the central region and beam dynamics of the cyclotron based on proposed algorithm. This code has been written in C++ program that uses the conventional Runge–Kutta method. The input data of this code including the electric and magnetic field distribution have been designed by OPERA-3D/TOSCA. In order to verify the BDIC code, optimized results of the code have been compared with the results of well-known beam dynamic programs, CYCLONE.
PubDate: 2021-12-23

• Response of Lettuce to Silver Nanoparticles Under Drought Conditions

Abstract: Nano-fertilization is an emerging technology to improve agricultural productivity under diverse ecosystems. Our study was conducted to investigate the effects of foliar fertilization of silver nanoparticles (AgNPs) on the growth, enzyme activities and water use efficiency (WUE) of lettuce (Lactuca sativa, L.) under drought conditions. A pot culture study with 4 AgNPs rates × 2 stress levels in a factorial combination of randomized complete block (RCB) design was conducted. The AgNPs levels were 0 (control), 25, 50, 75 and 100 mg/L) were imposed on lettuce seedlings under ambient and simulated drought (~50% field moisture capacity of soil) conditions. Lettuce plant height, total yields, leaf relative water content (RWC), chlorophyll content, membrane injury (MII), glutathione S-transferase (GST), glutathione reductase (GR), carboxylesterase (CaE), total phenolics and flavonoids and WUE were determined and/or calculated. The results showed that GST activity reduced in treatments of AgNPs + stress compared to stressed plants. In treatment of 100 mg L−1 AgNPs + stress, GR activity increased in treatments of 25, 50 and 75 mg L−1 AgNPs, but showed a significant decrease in 100 mg L−1 AgNPs + stress. CaE activity enhanced in 100 mg L−1 AgNPs + stress (about 1.55-fold) compared to stressed plants. Total flavonoid and phenolic contents were the highest in 50 mg L−1 AgNPs + stress. It was not obtained significant effects in the WUE rates. In 100 mg L−1 AgNPs, MII rates were the highest, and RWC rates were the lowest. Leaf width, plant height and total yield decreased at doses of AgNPs.
PubDate: 2021-12-02

• Correction to: On the Signed Complete Graphs with Maximum Index

PubDate: 2021-12-01

• Oil Sorbent Based on Luffa Fiber-Graft-Poly(Butyl Acrylate) Copolymer

Abstract: Luffa cylindrica is primarily used as a vegetable, but its dry fiber can be also used as a sponge. L. cylindrica has a ligneous fibrous netting system, in which the fibrous cords are disposed in a multidirectional array, forming a natural mat. In this work, we aim to synthesize a potential material for oil spill cleanup by the graft polymerization of butyl acrylate (BA) onto Luffa fiber (LF) using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The grafting process has been controlled by monomer and AIBN concentrations, reaction time and temperature, in which the optimal condition for the highest graft yield of 40.60% is [AIBN] = 0.035 mol/L, [BA] = 1.50 mol/L, 180 min at 75 °C. The graft copolymer LF-g-BA is structurally characterized by the Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. In the presence of crosslinking agent divinyl benzene, the oil sorption capacity of the synthetic LF-g-BA reaches 20.60 g oil/g sorbent for 48-h treatment. The LF-g-BA material can be seen as a potential sorbent due to its swelling property in non/weak polar mediums and reusable feature.
PubDate: 2021-12-01

• Extraction of Oleic Acid from Animals Oil and Its Anti-inflammatory Effect
on Network Pharmacology

Abstract: The purpose of this paper is to explore the possible mechanisms of anti-inflammatory and scar repair by Mongolian horse oil. We used TCM database and literature mining to collect active compounds of horse oil and used Swiss TargetPrediction and SuperPred server to find targets of compounds. Anti-inflammatory drug targets were collected through the CTD database. Go annotation of targets and KEGG pathway were enriched and analyzed through Metascape database platform. Molecular docking between active ingredients and targets was verified by AutoDock software. Metascape analysis revealed that the key candidate targets were significantly enriched in a number of pathways associated with inflammatory pathology. The results of molecular docking showed that oleic acid, a major component of animals oil, could influence the regulatory functions of TNF, NGF, IL6, IL1B, Jun, and CDK1. This suggests that animals oil can regulate the development of inflammation through its active ingredient, oleic acid, and can influence the expression of multiple signaling pathways, with theoretical endogenous interactions with TNF, NGF, IL6, IL1B, JUN, and CDK1 proteins.
PubDate: 2021-12-01

• Dopamine D2 Receptor Antagonist Alters the Testosterone Release and
Kisspeptin/GPR54 Signaling in Food-Restricted Rats

Abstract: It is well established that acute food restriction (FR) has a suppressive effect on the reproductive system that may be mediated through attenuating the kisspeptin/GPR54 signaling in the hypothalamus. Kisspeptin neurons have been shown to express the dopamine D2 receptor (D2R). The aim of the present study was to investigate the effect of chronic food restriction and/or antagonism of D2R by sulpiride on testosterone release and kisspeptin/GPR54 signaling in male rats. Sixty-six male Wistar rats, weighing-200 ± 20 g, were divided into seven groups including control, sham, 25%FR, 50%FR, 75%FR, sulpiride (50 µg/rat i.c.v., once at the end of treatment), 75%FR + sulpiride. FR was applied for 21 days. At the end, the mean serum testosterone level and the hypothalamic mRNAs expression of KiSS1, GPR54, D2R, and dopamine concentration were evaluated. The results demonstrated that the testosterone level significantly decreased in 50% and 75% food-restricted animals, and in sulpiride group, compared to control rats (P < 0.05). Injection of sulpiride to 75% food-restricted animals reduced the testosterone levels compared to all other groups (P < 0.05). Also, chronic 75%-FR significantly increased kisspeptin mRNA, dopamine concentration, but decreased D2R-mRNA (P < 0.05), and non-significantly decreased the GPR54mRNA (P > 0.05) compared to the control. Sulpiride injection to 75% food-restricted animals significantly decreased kisspeptin mRNA and increased dopamine concentration (P < 0.05), but had no significant effect on GPR54 or D2R-mRNAs expression, compared to 75% food-restricted group. In conclusion, we suggest that chronic food restriction decreases the testosterone release and then increases the kisspeptin/GPR54 signaling, and that the involvement of dopamine D2 receptor in these effects.
PubDate: 2021-12-01

• Poisson Noise Removal Using Non-convex Total Generalized Variation

Abstract: As is well-known that the total generalized variation model performs well in reducing the staircasing effect while removing noise, but it tends to cause the undesirable edge details blurring. To overcome this drawback, the current paper introduces the non-convex restriction into the total generalized variation regularizer and constructs an improved edge-preserving optimization model for Poissonian images restoration. For solving the minimization problem, we propose an efficient alternating minimization method by skillfully combining the classical iteratively reweighted $$\ell _1$$ algorithm and primal-dual framework. Some visual experiments presented in the illustration section, which are compared with some related denoising methods, demonstrate the better performance of the developed scheme in staircase artifacts reduction and image features protection. Besides, the measurable comparisons also indicate that our outcomes enjoy the best restoration accuracy against other popular competitors.
PubDate: 2021-12-01

• Assessment of Phenolic Contents and Antibacterial, Cytotoxic, and
Antioxidant Activities of Five Brown Algae from the Persian Gulf

Abstract: Marine sources have attracted worldwide attention due to their various biological activities. This study reports the cytotoxic, antioxidant, and antibacterial activities and phenolic contents of solvent extracts sequentially prepared by 80% methanol (MeOH), MeOH, and dichloromethane (DCM), of five brown algae from the Persian Gulf: Colpomenia sinuosa (C. sinuosa), Sargassum acinaciforme (S. acinaciforme), Iyengaria stellata (I. stellata), Sirophysalis trinodis (S. trinodis), and Padina gymnospora (P. gymnospora). The cytotoxicity of the extracts was determined against human acute lymphoblastic leukemia (MOLT-4) cells. We have determined the DCM extracts of C. sinuosa and S. acinaciforme and I. stellata as the most potent cytotoxic agents with IC50 values of 23.95 ± 1.9, 31.6 ± 8.5, and 36.0 ± 6.0 µg/mL, respectively. Additionally, the extracts were subjected to 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and Folin-Ciocalteu total phenolic assays. The MeOH extract of P. gymnospora showed the highest antioxidant activity with the highest radical scavenging potential (IC50 = 746.76 ± 94.15 µg/ml DPPH), which was consistent with its highest phenolic content (70.24 ± 5.40 mg equivalent to gallic acid in 1 g algal extract: mg EG/g AE). Finally, the antibacterial activity of the extracts was assessed against three Gram-positive and four Gram-negative bacteria using the broth dilution method by determination of the minimum inhibitory concentrations (MICs). The MeOH and 80% MeOH extracts of P. gymnospora and C. sinuosa exhibited the strongest antibacterial activity against all tested microorganisms, with the MIC values ranging from 0.62 to 5.00 mg/mL. In conclusion, the DCM extracts of the algae are suggested as the best sources of cytotoxic metabolites, while the MeOH and 80% algal extracts were week antioxidants (IC50s 746.76–5000 µg/ml DPPH) and contained lower amounts of phenolics (1.61–70.24 mg EG/g AE), but they are better source (0.62 to 5.00 mg/mL) of antibacterial metabolites.
PubDate: 2021-12-01

• Interactions Between Ecological Factors in the Development and Survival of
Bufotes variabilis: Resilience to Change

Abstract: Invasive species and climate change are important factors in amphibian declines. Climate change mediates impacts on water level fluctuations and amphibian densities. In this study, the interaction effects of invasive species (Gambusia holbrooki), desiccation, and high density were investigated on growth, size, time and percentage of metamorphosis, and survival Bufotes variabilis larvae within 60 d. We designed a 2 × 2 × 3 factorial experiment, crossing two levels of predatory cues (presence/absence), two levels of tadpole density (low/ high) and three levels of water (low/high/ decreasing). Results of the experiment showed mean larval growth rate was highest for both of presence of predator × high water level × high density and presence of predator × decreasing water level × low density treatments (0.30 mm/day). The slowest development time, the lowest percentage of metamorphosis and survival rate were observed at the presence of predator × high water level × high density treatment. Except for the significant impact of the presence of predator and density of tadpoles on survival, independent and interactive effects of three factors showed not significant effects on growth and survival. According to the results of the experiments, although each of the factors of predatory cues, density and water level influence the larval period, size and percentage of metamorphosis separately, however, their interactive effect is not significant. For effective conservation management, this study suggests that more research is needed on different species of amphibians.
PubDate: 2021-12-01

• Effects of Aging on Magnetic and Thermal Characteristics of NiMnCoSn
Magnetic Shape Memory Alloys

Abstract: Heusler shape memory alloys are important for many applications due to their typical magnetic and shape memory behaviors. In this study, a Ni50Mn36Sn12Co2 (at.%) alloy was manufactured by arc-melting technique, then the ingot cooled to ambient temperature in the natural atmosphere. Three different temperatures, including 500 °C (773 K), 700 °C (973 K), and 900 °C (1173 K), was selected for aging the samples cut from the main ingot. The impact of aging on the crystalline; microstructure; caloric; and magnetic properties of the alloys were investigated through x-ray diffraction (XRD); scanning electron microscope; differential scanning calorimetric (DSC), differential thermal analysis, and thermal gravimetric (TG); and physical property measuring system was investigated, respectively. The aging in different temperatures led to the shift DSC curve, such that the martensitic phase transformation temperatures of the sample aged at 773 K increased, however, the transformation at 973 and 1173 K decreased compared to the as-casted alloy. The different phase transformation behavior showed that the alloy aged at 773 K has the maximum elastic energy, enthalpy and entropy change compared to the reset of samples, on the other hand, its crystallite sized obtained from XRD analysis comparably diminished. Besides, the TG analysis revealed that the mass gain almost occurs at a temperature above 773 K, therefore the magnetization of the alloys aged at 973 and 1173 K decreased due to a thin oxide layer formed on the surface of the alloys.
PubDate: 2021-12-01

• Magnetic Dispersive Solid Phase Extraction of Cu (II) as 1-

Abstract: Fe3O4@XAD-16 has been used as adsorbent for magnetic dispersive solid phase extraction of Cu(II) as with 1- (2-pyridylazo) -2-naphthol (PAN) complex prior to flame atomic absorption spectrometric detection of copper. The effects of important parameters affecting extraction efficiency such as pH, adsorbent amount, eluent concentration and volume, model solution volume and ultrasonic bath time on magnetic solid phase extraction were studied in detail. The optimum pH for the extraction of Cu (II) was 6.0. The enrichment factor was 25. The accuracy of the extraction method was determined by the analysis of HR-1 (river sediment) and TMDA-53.3 (lake water) certified reference materials. The method was applied to determination of copper contents of food and water samples.
PubDate: 2021-12-01

• Evaluation of the Natural Radioactivity of Samples of Some Types of Field
Crops in Different Areas of Tikrit, Iraq

Abstract: This study aims to assess the concentrations of natural radionuclides activity (226Ra,232Th and 40 K) and calculate a number of radiation risk indicators in some types of field crops in different areas of Tikrit City-Salah Al-Din Governorate-Iraq. The measurement was carried out using a gamma-ray spectroscopy connected with a scintillation detector crystallized with thallium-activated sodium iodide NaI(TI). The results were that the mean concentrations of elements (226Ra, 232Th and 40 K) were (6.79 $$\pm 0.331\, Bq/kg,10.79 \pm 0.640\, Bq/kg, 133.34 \pm 5.895\, Bq/kg$$ ), respectively. And, the radiation risk indicators were less than the international permissible and the recommended average, so that the samples under study are safe and suitable for human and animal consumption.
PubDate: 2021-10-03
DOI: 10.1007/s40995-021-01222-0

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