Dynamic load concentration caused by a break in a Lamina with viscoelastic matrix

Arash Reza,Hamid M. Sedighi,Mahdi Soleimani 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.6

The effect of cutting off fibers on transient load in a polymeric matrix composite lamina was studied in this paper. The behavior of fibers was considered to be linear elastic and the matrix behavior was considered to be linear viscoelastic. To model the viscoelastic behavior of matrix, a three parameter solid model was employed. To conduct this research, finite difference method was used. The governing equations were obtained using Shear-lag theory and were solved using boundary and initial conditions before and after the development of break. Using finite difference method, the governing integro-differential equations were developed and normal stress in the fibers is obtained. Particular attention is paid the dynamic overshoot resulting when the fibers are suddenly broken. Results show that considering viscoelastic properties of matrix causes a decrease in dynamic load concentration factor and an increase in static load concentration factor. Also with increases the number of broken fibers, trend of increasing load concentration factor decreases gradually. Furthermore, the overshoot of load in fibers adjacent to the break in a polymeric matrix with high transient time is lower than a matrix with lower transient time, but the load concentration factor in the matrix with high transient time is lower.

Comparison of the effect of hand instruments, an ultrasonic scaler, and an erbium-doped yttrium aluminium garnet laser on root surface roughness of teeth with periodontitis: a profilometer study

Reza Amid,Mahdi Kadkhodazadeh,Reza Fekrazad,Farzin Hajizadeh,Arash Ghafoori 대한치주과학회 2013 Journal of Periodontal & Implant Science Vol.43 No.2

Purpose: The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation. Methods: Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acrylic resin block such that a plain root surface was accessible. After primary evaluation and setting a baseline, the samples were divided into 4 groups. In group 1, the samples were root planned using a manual curette. The group 2 samples were prepared with an ultrasonic scaler. In group 3, after scaling with hand instrumentation, the roots were treated with a Smart 1240D plus Er:YAG laser and in group 4, the roots were prepared with ultrasonic scaler and subsequently treated with an Er:YAG laser. Root surface roughness was then measured by a profilometer (MahrSurf M300+RD18C system) under controlled laboratory conditions at a temperature of 25°C and 41% humidity. The data were analyzed statistically using analysis of variance and a t-test (P<0.05). Results: Significant differences were detected in terms of surface roughness and surface distortion before and after treatment. The average reduction of the surface roughness after treatment in groups 1, 2, 3, and 4 was 1.89, 1.88, 1.40, and 1.52, respectively. These findings revealed no significant differences among the four groups. Conclusions: An Er:YAG laser as an adjunct to traditional scaling and root planning reduces root surface roughness. However,the surface ultrastructure is more irregular than when using conventional methods.

Temperature and Ca2+ ion as modulators in cellular immunity of the Sunn pest Eurygaster integriceps Puton (Heteroptera: Scutelleridae)

Arash ZIBAEE,Ali Reza BANDANI,Reza TALAEI-HASSANLOUEI,Davide MALAGOLI 한국곤충학회 2009 Entomological Research Vol.39 No.6

Environmental conditions in addition to divalent cations may affect the interactions between pathogens and insects. Elucidation of factors which modulate insect immune responses could be a significant part of investigations in this area. In this study, adults of Eurygaster integriceps, as the destructive pest of wheat, were kept at different temperatures in addition to injection with different concentrations of Ca2+ to find the effect on cellular immune reactions against Beauveria bassiana. Results showed that total and differentiate hemocyte numbers, nodule formation and phenoloxidase activity increased with elevation of temperature so that the higher values were obtained at 30 and 40°C at various intervals. Higher concentrations of Ca2+ ion (5 mM) caused an increase in plasmatocyte length and width especially after 60 min. Similar results were observed for nodule formation and phenoloxidase activity of E. integriceps adults after injection by B. bassiana spores and phenoloxidase activity. It is clear from the current study that thermoregulation and Ca2+ ion can positively affect the hemocyte numbers especially plasmatocytes and granulocytes, nodule formation and phenoloxidase activity in E. integriceps. The understanding of modulators of the insect immune response may directly influence novel approaches to obtain safe and effective biological control agents.

A fast damage detecting technique for indeterminate trusses

Arash Naderi,Mohammad Reza Sohrabi,Mohammad Reza Ghasemi,Babak Dizangian 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.5

Detecting the damage of indeterminate trusses is of major importance in the literature. This paper proposes a quick approach in this regard, utilizing a precise mathematical approach based on Finite Element Method. Different to a general two-step method defined in the literature essentially based on optimization approach, this method consists of three steps including Damage-Suspected Element Identification step, Imminent Damaged Element Identification step, and finally, Damage Severity Detection step and does not need any optimizing algorithm. The first step focuses on the identification of damage-suspected elements using an index based on modal residual force vector. In the second step, imminent damage elements are identified among the damage-suspected elements detected in the previous step using a specific technique. Ultimately, in the third step, a novel relation is derived to calculate the damage severity of each imminent damaged element. To show the efficiency and quick function of the proposed method, three examples including a 25-bar planar truss, a 31-bar planar truss, and a 52-bar space truss are studied; results of which indicate that the method is innovatively capable of suitably detecting, for indeterminate trusses, not only damaged elements but also their individual damage severity by carrying out solely one analysis.

Total and Partial Updating Technique: A Swift Approach for Cross-Section and Geometry Optimization of Truss Structures

Arash Naderi,Mohammad Reza Sohrabi,Mohammad Reza Ghasemi,Babak Dizangian 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

In this paper, a novel two-phase method called Total and Partial Updating Technique, is employed for the cross section and geometry optimization of truss structures. The goal of optimizing such structures is to minimize their weights under natural frequency constraints. In Total and Partial Updating Technique, in order to find the global optimum point, only the best two existed solution points at each repetition move together in the search space defined in each phase. Each time, the first phase is destined to find a solution near the global optimum point although searching in the unfeasible region. In the second phase, it is forced jumping into the feasible region to reach the global optimum point. The comparison of the results with those in the literature on two numerical examples demonstrates that due to its relatively significant low computational costs and its assured non-violated constrained optimum solutions at the end of the process, the method may be considered as more reliable and efficient technique on such problems.

Comparison of the effect of hand instruments, an ultrasonic scaler, and an erbium-doped yttrium aluminium garnet laser on root surface roughness of teeth with periodontitis: a profilometer study

Amid, Reza,Kadkhodazadeh, Mahdi,Fekrazad, Reza,Hajizadeh, Farzin,Ghafoori, Arash Korean Academy of Periodontology 2013 Journal of Periodontal & Implant Science Vol.43 No.2

Purpose: The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation. Methods: Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acrylic resin block such that a plain root surface was accessible. After primary evaluation and setting a baseline, the samples were divided into 4 groups. In group 1, the samples were root planned using a manual curette. The group 2 samples were prepared with an ultrasonic scaler. In group 3, after scaling with hand instrumentation, the roots were treated with a Smart 1240D plus Er:YAG laser and in group 4, the roots were prepared with ultrasonic scaler and subsequently treated with an Er:YAG laser. Root surface roughness was then measured by a profilometer (MahrSurf M300+RD18C system) under controlled laboratory conditions at a temperature of $25^{\circ}C$ and 41% humidity. The data were analyzed statistically using analysis of variance and a t-test (P<0.05). Results: Significant differences were detected in terms of surface roughness and surface distortion before and after treatment. The average reduction of the surface roughness after treatment in groups 1, 2, 3, and 4 was 1.89, 1.88, 1.40, and 1.52, respectively. These findings revealed no significant differences among the four groups. Conclusions: An Er:YAG laser as an adjunct to traditional scaling and root planning reduces root surface roughness. However, the surface ultrastructure is more irregular than when using conventional methods.

Novel Thallium(I)-Selective Membrane Electrode Based on a Podal Ligand

Ganjali, Mohammad Reza,Pourjavid, Mohammad Reza,Mouradzadegun, Arash,Hosseini, Morteza,Mizani, Farhang Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.11

A PVC-based membrane electrode for thallium(I) ions based on 1,21,23,25-tetramethyl-2,20: 3,19-dimetheno-[H, 2] H, 23H, 25H-bis-[1,3] dioxocino[5,4-i:5',4'-i] benzo [1,2-d: 5.4-d'] bis [1,3] benzodioxocin(II) has been prepared. The electrode displays a linear dynamic range of $1.0{\times}10^{-1}-1.0{\times}10^{-5}$ M, with a Nernstian slope of $59.8{\pm}0.2\;mV\;{decad^-1}$, and a detection limit $5.0{\times}10^{-6}$ M. It has a very fast response time of<10 s and can be used for at least ten weeks without a considerable divergence in potentials. This electrode revealed comparatively good selectivity with respect to alkali, alkaline earth, and some transition and heavy metal ions and was effective in a pH range of 2.0-10.0. It was used as an indicator electrode in potentiometric titration of thallium ion with sulfide ion.

Application of photoelectro-fenton process modified with porous cathode electrode in removing resistant organic compounds from aquatic solutions: modeling, toxicity and kinetics

Reza Ali Fallahzadeh,Mohammad Hassan Ehrampoush,Mohsen Nabi Meybodi,Mohammad Taghi Ghaneian,Arash Dalvand,Fariborz Omidi,Mohammad Hossein Salmani,Hossien Fallahzadeh,Amir Hossein Mahvi 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.6

The presence of antibiotics in the environment as persistent micropollutants, due to their widespread consumption, has increased the concerns about the harmful effects of these compounds on human and animal health. Advanced oxidation processes are one of the most effective methods to remove these types of organic pollutants. In this study, amoxicillin (AMX) removal in a modified photoelectro-Fenton (PEF) reactor in which porous stainless steel was used as a cathode electrode, and the ability of air injection into its center to produce H2O2 was investigated. A graphite anode electrode equipped with iron rings was used to increase the electrochemical reaction surface and produce iron ions. The effect of current density, time, and electrolyte concentration on AMX removal efficiency was evaluated by Box-Behnken design method. Subsequently, the effect of AMX concentration variable and pH on removal efficiency was investigated. Finally, the chemical oxygen demand (COD) removal efficiency, toxicity, and effluent activity from the PEF reactor were investigated. The results showed that the modified photoelectro-Fenton process could have efficiency of 99% to remove AMX, in 20min using current density of 36 mA/cm2 and 16mM/L electrolyte concentration. Reducing pH and AMX concentration increased the removal efficiency. The PEF process can completely remove the COD in 58 min. Also, toxicity studies indicated an effective reduction in the effluent. This modified reactor improves the efficiency of the PEF process, which, in addition to the 99% removal of AMX, provides a proper function for COD removal, reducing the toxicity properties of the effluent.

Molecular characterization of a pigeon paramyxovirus type 1 virus isolated from Eurasian collared doves in Iran, 2017

Reza Esmaeelzadeh-Dizaji,Aidin Molouki,Hossein Hosseini,Mohammad Hossein Fallah-Mehrabadi,Zahra Ziafati-Kafi,Azin Takalou,Nava Eram,Niloufar Kumar,Alireza Ashuri,Naser Sadri,Arash Ghalyanchi-Langeroud 대한수의학회 2022 JOURNAL OF VETERINARY SCIENCE Vol.23 No.3

In September 2017, an outbreak with high mortality, which showed the typical signs of ND, occurred among a flock of more than 2000 Eurasian collared doves in Konarak, southeast of Iran. A confirmed pigeon paramyxovirus type 1 strain was isolated from the brain tissues of the dead doves. The isolate, which was called Pigeon/Iran/Konarak/Barin/2017, was classified as a highly velogenic NDV. Complete genome sequencing and phylogenetic analysis showed that the isolate belonged to subgenotype XXI.2, which has never been reported from Iran before. The isolate had the highest homology (96.15%) with early 2010s Italian isolates. Further studies will be required to understand the diversity better.

Characterization of α-amylase in the midgut and the salivary glands of rice striped stem borer, Chilo suppressalis Walker (Lepidoptera: Pyralidae)

Arash Zibaee,Ali Reza Bandani,Maryam Kafil,Samar Ramzi 한국응용곤충학회 2008 Journal of Asia-Pacific Entomology Vol.11 No.4

The rice striped stem borer, Chilo supprressalis, is a destructive pest of rice that was introduced to Iran in 1973 and has since become widely distributed. Amylases are hydrolytic enzymes that catalyze the hydrolysis of the α-D-(1,4)-glucan linkage in glycogen and other related carbohydrates. Laboratory-reared 4th stadium larvae were randomly selected; the midgut and the salivary glands were removed by dissection under a dissecting microscope and α-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of α-amylase in the midgut and salivary gland were 0.06 and 0.036 μmol/min/mg protein, respectively. The optimal pH and temperature for α-amylase were 9 and 35–40 °C, which is consistent with reports of other lepidopteran insects. The enzyme activity was inhibited by addition of NaCl, KCl, MgCl2, Urea, EDTA, and SDS. CaCl2 enhanced enzyme activity. Ca2+ ions also had inhibitory effects on glucosidase activity. Plant amylase inhibitors play important role against insect pests. Hence, the characterization of digestive enzymes and the examination of inhibitors on enzyme activity could be useful in tackling of insect pests. The rice striped stem borer, Chilo supprressalis, is a destructive pest of rice that was introduced to Iran in 1973 and has since become widely distributed. Amylases are hydrolytic enzymes that catalyze the hydrolysis of the α-D-(1,4)-glucan linkage in glycogen and other related carbohydrates. Laboratory-reared 4th stadium larvae were randomly selected; the midgut and the salivary glands were removed by dissection under a dissecting microscope and α-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of α-amylase in the midgut and salivary gland were 0.06 and 0.036 μmol/min/mg protein, respectively. The optimal pH and temperature for α-amylase were 9 and 35–40 °C, which is consistent with reports of other lepidopteran insects. The enzyme activity was inhibited by addition of NaCl, KCl, MgCl2, Urea, EDTA, and SDS. CaCl2 enhanced enzyme activity. Ca2+ ions also had inhibitory effects on glucosidase activity. Plant amylase inhibitors play important role against insect pests. Hence, the characterization of digestive enzymes and the examination of inhibitors on enzyme activity could be useful in tackling of insect pests.