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To investigate the effect of molecular weight of chitosan and the type of plasticizer used in the composition of edible coating on internal quality parameters and morphology of eggshell, an experiment with 125 eggs in a completely randomized design with 5 treatments included uncoated eggs (control), coated based on chitosan with high molecular weight (450 kDa) or low molecular weight (65 kDa) and the use of glycerol or sorbitol and 3 replicates was conducted. Coating was done by immersion method and the eggs were stored at ambient temperature for 4 weeks. The internal quality parameters of eggs including weight loss (WL), Haugh unit (HU), yolk index (YI) and albumen pH were evaluated weekly. At the end of the storage period, scanning electron microscope (SEM)micrograph were prepared for eggshell morphology. The results showed that the edible coating based on chitosan improved significantly (P<0.05) all the evaluated parameters. At the end of the week 4, among these, the lowest values of WL (7.01 ± 0.90) and pH of albumen (8.90 ± 0.15) and the highest values of HU (± 3.23) 63.80) and YI (0.34 ± 0.06) were seen in eggs containing high molecular weight chitosan -sorbitol coating (P<0.05). In the SEM micrograph, more integrated and less porous and fractured in the mentioned group. Therefore, in order to improve the quality of edible coating based on chitosan as a biocompatible packaging to increase the storage time of eggs, chitosan with higher molecular weight and sorbitol as plasticizer are recommended. [ABSTRACT FROM AUTHOR]

The increase in the need for starch in the food processing industry has led to the recognition of the effect of other food compounds on the processing of starch-based foods. Xanthan and sugar are commonly used as hydrocolloids and sweeteners, respectively, in starch-based foods. These constituents can affect the structural, thermal, adhesive (dough) and rheological properties of these types of foods. The purpose of this study is to analyze the effect of sucrose and xanthan on the physicochemical, rheological and morphological characteristics of starch pastes. In addition, the comparison of the effect of the combination of xanthan and sucrose on corn and wheat starch pastes has been done in this study. In this research, the concentration of xanthan was 1% by weight and sucrose was 5% by weight, and the mixtures were prepared based on starch (corn or wheat starch). The results showed that in the presence and absence of xanthan 1% by weight and sucrose 5% by weight, the starch dough had a significant difference in terms of solubility, swelling power, water absorption, and dough transparency (p < 0.05). Rheological tests revealed that all pastes exhibited shear thinning behavior. By adding xanthan and sucrose, the apparent viscosity, storage modulus and loss modulus of starch pastes increased. Fourier transform infrared spectra showed the change in the intensity and wavelength of absorption peaks due to the addition of xanthan and sucrose. The measurements of scanning electron microscope and X-ray diffraction proved that as a result of adding xanthan and sucrose during gelatinization, changes were made in the network structure. The results of this study can improve processing and find optimal processing conditions to produce food based on Starch like baby food, bread, sweets, etc. help. [ABSTRACT FROM AUTHOR]

The use of quinoa seeds and its derivatives in the bakery products formulation, in addition to improving the nutritional value of the final product, reduces dependence on plant sources with high water requirements such as wheat and rice, so in this study the effect of rice flour replacement by whole quinoa enzymatic malt at levels of 0, 2.5, 5, 7.5 and 10% on physicochemical and textural properties and internal structure of gluten-free bread was investigated. The results showed that by increasing the amount of quinoa malt (up to 10%) in the product formulation no significant effect on moisture content and water activity was observed. However, the firmness of the texture in 2 and 72h after baking increased by 10% of quinoa malt. Also, the specific volume and porosity of the product was reduced only at level of 10% of quinoa malt flour. On the other hand, by increasing the amount of quinoa malt flour, the enthalpy of the samples decreased (2 and 72h after baking), while the enthalpy increased with increasing product storage time. The results of crust color evaluation showed a decrease in the amount of L* value and an increase in the amount of a* and b* values by increasing the amount of malt flour in the formulation, which indicates more turbidity of the product. The results of images obtained by Scanning Electron Microscope showed the average values of diameter and pore area of the product decreased by addition quinoa malt. Finally, the panellists gave the highest overall acceptance score to three samples containing 0, 2.5 and 5% of quinoa malt, which indicates the improvement of quantitative and qualitative properties of the final product using enzymatic derivatives and gluten-free quinoa. [ABSTRACT FROM AUTHOR]

chitosan (Cs) was extracted from shrimp shell and its derivative forms including N-alkyl (AlkCs) and nanoparticles (CsNPs) were prepared. Then, their antibacterial effects on the growth of Staphylococcus aureus strain sensitive to methicillin were investigated. Morphology was investigated by scanning electron microscope (SEM), chemical structure by X-ray diffraction pattern and size of CsNPs by zetasizer. Then, their antibacterial activity was evaluated by testing the minimum concentration of inhibition and lethality, diffusion in agar with the help of a disk, the permeability of the cell membrane by measuring the diffusion of cytoplasmic beta-galactosidase. The type of cell death induced was also examined by DAPI staining and changes in cell surface integrity by atomic force microscopy (AFM). The results showed that the CsNPs are spherical with an average hydrodynamic diameter of 240 nm. AlkCs had a rough surface structure compared to chitosan. The best results regarding MIC (78/125 μg/ml) and MBC (100 μg/ml) points were observed for CsNPs (P < 0.05). CsNPs and AlkCs showed the highest diameter of growth inhibition zone at 1250 concentration compared to other disks (P <0.05). The permeability of the cytoplasmic membrane of Staphylococcus aureus treated with CsNPs and AlkCs showed a significant difference compared to the treatment with chitosan and control (untreated) (P < 0.05). (P < 0.05). DAPI staining test showed higher cell death of Staphylococcus aureus treated with CsNPs and AlkCs. The images obtained from AFM showed a change in the integrity of the membrane and the arrangement of the treated bacteria compared to the spherical surface and the cluster arrangement of the untreated bacteria. [ABSTRACT FROM AUTHOR]

The present research has aimed to investigate the effect of Ti3AlC2 reinforcing MAX phase on the electromagnetic behavior of TiC matrix composites. In this case, the milling process and secondary heat treatment were used for the synthesis of the composite. The resulting structures were examined by scanning electron microscope, differential thermal analysis, and X-ray diffractometer. Electromagnetic behavior was investigated by vector network analyzer. The investigations showed that it is possible to create a TiC/Ti3AlC2 composite structure in situ after milling. Electromagnetic investigations revealed that the electromagnetic absorption behavior of TiC/Ti3AlC2 ceramic matrix composite was improved compared to the original TiC. So that the lowest reflection loss of the milled composite was equal to -19.46 dB in the frequency range of 1 to 18 GHz band. After annealing at 1400 °C, it was found that the Ti3AlC2 phase resulting from the milling process was not stable and turned into the single phase solid solution of TiCx. Electromagnetic investigations of the annealed sample showed that after removing the MAX phase, the electromagnetic absorption behavior was weakened. Thus, the lowest reflection loss of the annealed sample was equal to -9.82 dB. [ABSTRACT FROM AUTHOR]

One of the problems of papers and cardboards in the packaging industry is the poor resistance to water, gas, and oil penetration. Nowadays, many researches have been done on the use of biodegradable films and coatings based on polysaccharides to solve this problem. Chitosan is one of these polysaccharides that can be used as a biodegradable coating in packaging papers. In this study, the effect of chitosan on the strength and barrier properties of coated liner paper was investigated. Chitosan was used in three levels of 10, 15, and 20 g/L acetic acid (1%) and with two softener ratios (glycerol) of 0.5 and 1 (based on dry weight of chitosan) for papers coating. Strength properties including tensile, burst and tear index and barrier properties including water absorption, air resistance, and oil absorption in the coated samples were investigated. The statistical analysis of results showed that the barrier properties increased significantly. Also, the effect of increasing the concentration of softener in the coating solution on the properties of air resistance and oil absorption was positive but negative for water absorption. The basis weight, burst and tear index of the coated samples increased with increasing coating weight. On the other hand, the tensile strength decreased. Moreover, increasing the concentration of softener in the coating solution showed a negative effect on the properties of the samples. The scanning electron microscope images showed the formation of chitosan film and increase in the uniformity of the liner paper surfaces, especially in higher consumption volume. [ABSTRACT FROM AUTHOR]

Collagen is the most abundant protein of animal origin and the most important compound in the connective tissue which is widely used in the food and beverage industry. In addition, recent research has demonstrated the functional, beneficial, and potential properties of collagen extracted from aquatic wastes as nutraceuticals and for delivery systems of sensitive bioactive compounds. Therefore, the aim of this research was considered to study the structural charachters, antioxidant and functional properties of collagen and collagen hydrolysate extracted from the skin of common grouper (Epinephelus coicoides). In the present experimental study, the collagen sample was extracted by acid and enzymatic method and structural characters were studied by Fourier -transform infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM) and polyacrylamide gel electrophoresis (SDS -PAGE). DPPH radical scavenging, reducing Power and foam producing capacity also assessed.The results of Scanning Electron Microscope confirmed schistose structure, filamentus network, secondary and third structure, and the good interconnection and uniform porus matrix was noticed. The typical characters for type I collagen, including five peaks (amide A, amide B, amide I, amide II and amide III are observed in the spectrogram of collagen and collagen hydrolysate, also the preserved triple -helical structure were comfirmed. The results of the functional properties and antioxidant activity of collagen from orange -spotted grouper skin also showed that with increasing the concentration, reducing power and DPPH radical scavenging ability increased. Comparing collagen and hydrolyzed sample, the foam producing capacity was proved just for collagen. Finally, it can be said that collagen and hydrolyzed collagen extracted from the skin of orange -spotted grouper with suitable antioxidant properties, and appropriate functional properties can be mass -produced as a bioactive compound and as emulsifier may be used in the food industry and in the production of Functional foods. [ABSTRACT FROM AUTHOR]

The musk willow essential oil is volatile and encapsulation can protect them from environmental factors such as, light, oxygen and temperature. In the present research, preparation of sodium alginate -whey protein microcapsule containing essential oil of musk willow was carried out by internal gelation -emulsification method with encapsulation efficiency of 87.31%. The obtained microcapsules were characterized by particle size analyzer, zeta potential analyzer and scanning electron microscope. Encapsulation efficiency, swelling ratio and in vitro release of the essential oil was also investigated in fatty and acidic food simulationconditions. At acidic and fatty food simulation conditions, the complex presented negatively charged, with potential zeta values being 42.25 and 38.11 mV, respectively. The greatest electrostatic interaction occurred near pH 3.0 where the charge approached neutrality, which represents a balance between the biopolymer charges. Microcapsules shrinking in the acidic food simulation (pH=3.0) and expanding in the fatty food simulation (pH=7.0). The release results indicated that the release of musk willow essential oil from the microcapsule in both conditions occurred with a controlled manner and exhibited a slow rate. The essential oil release was found to be best fitted by Hixson–Crowell model (R 2 =0.993 for the acidic food simulation condition and R 2 =0.995 for fatty food simulation condition) which implies that a change in diameter of the microcapsule as a function of time. Mathematical modeling of release kinetics shows that musk willow essential oil loaded microsphere release follows by classical Fickian diffusion and erosion/degradation mechanisms. [ABSTRACT FROM AUTHOR]

Background and Objective: Microplastics can have harmful effects on living things, including humans. These particles have been identified in all water, soil, and food sources. Among these, freshwater resources are more important, because they are considered a water source for humans through drinking water treatment plants (DWTPs). Therefore, this study investigates the performance of Tehran DWTPs in removing these particles. Materials and Methods: In this study, the performance of three DWTPs in Tehran in removing these particles was investigated. In most studies worldwide, particles larger than 1 µm were examined, but in this study, nanoplastic particles smaller than 1 µm, as well as the effect of the warm and cold seasons of the year on the concentration of these particles were also examined. Results: According to the results of the study, the amount of micro and nanoplastic particles at the inlet of treatment plants in the warm season of the year was 2569 ± 309 to 3918 ± 425 MP/L, and the output was 1492 ± 32 to 2279 ± 146 MP/L, which indicates an increase in these particles in the warm season. As a result, the studied treatment plants were only able to remove 32.1 to 59.9% of these particles. In addition, using electron microscopy, MPs were classified into three categories in terms of appearance: fiber, fragment, and film. This study completes the knowledge of MPs in this area. Conclusion: Based on the results of this study, Tehran DWTPs have poor performance in removing these particles. [ABSTRACT FROM AUTHOR]

With increasing public awareness, the demand for healthy foods has increased. Low resistance of probiotic bacteria against adverse environmental conditions is one of the most important factors limiting the production and development of probiotic products. Encapsulation by enclosing probiotic cells can increase stability against limiting factors such as gastric acidity.In this study, the efficiency of double layer encapsulation with sodium alginate and chitosan by spray drying and emulsion methods on the stability of Lactobacillus acidophilus under simulated gastric conditions (pH=2) during 0, 30, 60, 90 and 120 minutes were examined. The size of the microcapsules was determined by the particle size analyzer and their morphology using a scanning electron microscope (SEM).The obtained growth curve showed that the bacteria enter a stationary growth phase 40 to 42 hours after inoculation. The size of the microcapsules obtained from the emulsion method were significantly (p≤ 0.05) smaller than the spray drying method. The morphology of the microcapsules was spherical to oval, and the samples obtained from the spray drying method had a shrinked surface. The highest survival was shown by emulsion encapsulated samples with a decrease of 1.9 logarithmic cycles, followed by spray dried encapsulated bacteria with a reduction of 2.4 logarithmic cycles. The lowest survival rate was related to the control sample (free bacteria) with a decrease of 3.83 logarithmic cycles.Encapsulation of Lactobacillus acidophilus probiotic bacteria by the emulsion technique by creating appropriate stability under simulated gastric conditions is a suitable method to obtain probiotic products enriched with this bacterium. [ABSTRACT FROM AUTHOR]

The present study was conducted with the aim of protein isolation from the muscle of grass carp (Ctenopharyngodon idella) and investigation of the effect of extraction pH on different properties of isolated protein. Proteins were produced by pH -shift method in two treatments including dissolution in alkaline pH (11.5), and acidic pH (3), and then evaluated in terms of nutritional value, functional properties, and structural changes. According to the results, the yield of protein production was significantly higher in alkaline conditions than in acidic conditions. The evaluation of emulsifying and foaming capacity and water absorption capacity showed that the protein obtained from alkaline pH was better than acidic treatment. Also, the extracted proteins contained all essential amino acids within the recommended limit for daily consumption of adults. The evaluation of color indices showed that the protein obtained from acidic pH had a brighter and whiter color than alkaline pH. The images obtained from the scanning electron microscope and the FTIR spectra of samples showed that the pH -shift method did not lead to extensive destruction of the protein structure and both protein isolates had all the absorption peaks related to the main bonds of the proteins structure. In general, it can be concluded that the pH -shift method is an efficient method for extracting high quality protein from grass carp tissue, and different alkaline and acidic conditions lead to the production of proteins with different characteristics that can be used based on the application that is intended for the final product. [ABSTRACT FROM AUTHOR]

Cast AZ91 alloy is one of the most used magnesium alloys, which is sensitive to liquation in the fusion weld method's and friction stir spot welding due to low eutectic temperature and the presence of the intermetallic compound in eutectic temperature. In this research, the liquation behavior of AZ91 alloy during friction stir spot welding was investigated. The process was carried out at two rotation speeds of 1000 and 2500 rpm and a dwell time of 1 second on the plate of AZ91 with a 10 mm thickness. Microstructural characterization was carried out using optical and scanning electron microscopes. The results showed that at low rotation speed (1000 rpm), mechanical grinding redistribution and dissolution of precipitates occurred. While at high rotation speed (2500 rpm), the predominant phenomenon was liquation. In this condition, the liquation initiated around the stirred zone. Also, the presence of liquid film along grain boundaries resulted in decreased grain boundary strength and liquation cracking. [ABSTRACT FROM AUTHOR]

Application of ionizing rays like gamma-ray in polymers to modify their properties has attracted much attention. Therefore, in this study, polypropylene as the composite matrix, maleic anhydride (MAPP) as the compatibilizer material, and poplar wood as the filler were used to make composite and then the composite was placed under the radiation of gamma-ray with different doses from 0 to 75 kGy. The white rot fungi (Trametes versicolor) and, brown rot fungi (Gloeophyllum Trabeum) were used in fungal decay test. The main purpose of this study is to investigate the probable benefits of gamma-ray radiation for improvement of some of the composites physical and mechanical properties, and also, to investigate the biodegradation in fungal decay and thermal properties. The results indicates that radiation of gamma-ray improves the physical and mechanical properties of some structures, and the decay resistance of the WPCs against brown and white rot fungus according to their weight losses. The uniformity of the micrographs obtained from the scanning electron microscope (SEM) indicated that the interaction between the polymer and wood fibers. [ABSTRACT FROM AUTHOR]

Introduction: Nowadays, the heavy metals pollution is one of the most important environmental problems. Due to the high cost of common refining methods, the use of microbial biomass is recommended to clean up heavy metals. The aim of this study was to evaluate the interactions of Rhodoterula toruloides strain IR-1395 with mercury. Materials and methods: In this study, the growth rate and types of interactions of the strain IR1395 with mercury in the Sucrose Broth medium were investigated and the amount of mercury accumulated was measured using the Spectrophotometry method. Then, in order to determine the best biosorption conditions, the effect of parameters such as pH, mercury concentration, biomass concentration, contact time, and the temperature was measured. Also, the biosorption was investigated by treated cells with 2,4 dinitrophenol and autoclave. Finally, the biosorbent was characterized by Scanning Electron Microscope equipped with Energy Dispersive X-Ray Analysis. Results: Studies have shown that the maximum growth rate of the strain IR-1395 was after 36 hours and then it entered the stationary phase. Also, this strain was able to the biosorption and bioaccumulation (61.86%) and 10.17% biovolatilization of mercury from the medium at the concentration of 10 mg/l of chloride mercury for seven days. In examining the factors affecting the mercury biosorption, it was indicated that the optimal pH was 4. The highest biosorption was observed at 300 mg/l of mercury in 10 minutes at 15 ˚C. In the study of the effect of 2,4- dinitrophenol treatment and autoclave, it was found that mercury adsorption has reduced by the treated yeast. Finally, the results of the EDX confirmed the biosorption of mercury by this yeast. Discussion and conclusion: By examining the types of interactions of the strain IR-1395 with mercury and its potential in biosorption, it was found that this strain is a valuable microorganism in mercury bioremediation processes from contaminated aquatic environments. [ABSTRACT FROM AUTHOR]

Metastable beta titanium alloys have the ability to achieve different microstructures as a result of various heat treatment cycles. The aim of the present study was to create a combination of fine spherical and needle-shaped alpha phase in a metastable beta Titanium alloy (Ti-3Al-8Mo-7V-3Cr) using two-phase solution annealing and aging to improve tensile properties. In this regard, one strip of the alloy was solution annealed in the two-phase region (α+β) at 750°C. Then, some of the solution treated specimens were aged in one step and the others in two steps. The microstructural observation and phase analysis were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively followed by investigating tensile properties using tensile test. The results exhibited that the microstructure of the alloy after annealing in the two-phase region (α+β) consisted of a spherical primary alpha phase of 1 μm in the beta matrix. One-step aging at 600°C resulted in a microstructure without secondary alpha layers. This heat treatment cycle resulted a yield strength of 980 MPa and fracture strain of 13.9%. Two-step aging at 300°C and 600°C led to formation of the secondary alpha layers with 0.1 μm thickness and increased the yield strength and fracture strain to 1007 MPa and 15.8%, respectively. [ABSTRACT FROM AUTHOR]

Kaymak or Sarshir, a traditional dairy product, is served in Iranian breakfast. The aim of this study was to investigate the fatty acids profile, physicochemical properties (texture, color, pH, acidity, the content of dry matter, fat and protein) and organoleptic aspects of Gilanvand and Dalirankaymaks in comparison to the heavy cream. To study more closely the texture and appearance differences of these products, scanning electron microscope (SEM) images were also prepared. The obtained results showed that the contents of fat and dry matter in heavy cream were higher than the kaymaks; however, Gilanvandkaymak had the highest protein content, acidity, and b*-value. Based on the study of the fatty acids profile, palmitic acid and cis-oleic acid were recognized as the most dominated saturated and unsaturated fatty acids, respectively. Microstructural analysis of SEM revealed that the structure of the protein in the fat field was compact, irregular and abundant in Gilanvandkaymak which influenced the product properties. The hardness, gumminess, and adhesiveness of the heavy cream were highest in comparison to the kaymaks. The Gilamvandkaymak obtained higher scores in evaluating the taste and total acceptance. In conclusion, it can be mentioned that the Gilamvandkaymak will have high potential in marketability by considering its higher protein content as well as total acceptance. [ABSTRACT FROM AUTHOR]

Application of composites according to their properties such as high strength to weight ratio, high corrosion resistance, and their ability to build complex shapes in different industries are increased. But due to composite's vulnerability against unwanted impact loads, their usage has been limited. Relatively higher costs of carrying out low-velocity impact (LVI) test, data sampling limit due to short experiment time, and adaptation of quasi-static impact (QSI) test results with LVI, convinced researchers to use QSI instead of LVI. This research investigated the effect of different percentages of nanoclay (1%, 3%, 5%, and 7%) on impact properties of glass-epoxy composite and for this purpose, the QSI test was used. To disperse and distribute nanoclay homogeneously inside the resin, mechanical and ultrasonic mixers have been used; EDAX photograph token from nano-resin section confirmed the success of this process. QSI test results showed that adding 3% nanoclay to glass-epoxy composite, increases absorbed energy and stiffness up to 16% and 12% respectively. It was also determined by perusing SEM photographs that the mechanical properties of specimens containing 7% nanoclay had decreased due to the agglomeration of nanoparticles. [ABSTRACT FROM AUTHOR]

One of the reasons for soil salinization is the accumulation of salts in it by transmission through water and wind. In order to investigate the phenomenon of transfer of salts with dust in the arid regions of the north of Yazd- Ardakan plain, field samples were taken using 32 MDCO sediments traps with uniform dispersion in an area of 20,000 hectares at some stage in 4 seasons of 2017. After washing the sediment collector with a liter of distilled water in the field and transferring the samples to the laboratory, for the quantitative analysis of saline dust, similar to measuring the Water Electrical Conductivity (ECw), the Total Soluble Solids (TDS) were additionally measured through evaporation technique. The form and distribution of the dust particle size were additionally investigated using a Scanning Electron Microscope (SEM) tool. Within the qualitative examine of salts, effective cations and anions in salinity including Na+, K+, Ca++, Mg++, Cl, HCO3and SO4were measured The results confirmed that, in general, the fallout was 11.1 g.m2 of soluble material with dust particles (13.28%) in the course of only 12 months. Particles with a diameter of 5 to 10 microns were the most frequent. Considering the high correlation between Cland Na+ in the spring, autumn and winter, due to the high correlation between Ca++ and SO4in summer dust, sodium chloride (NaCl) and gypsum (CaSO4) 2H2O)), the most abundant composition of dust- containing salts could be expected in these seasons. By determining the percentage of solutes in the fallout dust, it was observed that the impact of the amount of the deposited salt from dust was slight and insignificant in the short time period; with the assumption of no change in the rate of subsidence, it was anticipated that it would explain the poor salinity in non- saline mass soils for up to 10 cm in 72 years. In general, the capability of airborne salt in increasing the soil salinity in the study area can be in long- term periods. Therefore, it is recommended to investigate other environmental effects of this phenomenon in order to identify its hazards. [ABSTRACT FROM AUTHOR]

In this study, the hot-working behavior of Mn-25Ni-5Cr alloy was studied using hot compression tests at the temperatures of 850 ˚C, 900 ˚C, 950 ˚C and 1000 ˚C and the strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1 and 1 s-1 to a true strain level of 0.7. The results of flow curves showed that the flow stress decreases with increasing temperature and decreasing strain rate. Regarding the shape of flow curves, peak appearance represents the dynamic recrystallization. The peak stress and strain of flow curves appeared in fewer strains at high temperatures and strain rates. The microstructural evolution is mainly controlled by dynamic recrystallization. The presence of evolving boundaries around the recrystallized grains also indicates the occurrence of continuous dynamic recrystallization during hot working . In closer scrutiny of microstructure and fasciology, using by SEM microscope equipped with EDS detector, in addition to the background phase, second phase consisting of manganese, nickel and chromium was identified. The constants of n, α and β were determined using constitutive, power and exponential equations at 0.3 strain. According to the constitutive equation of the hyperbolic sinus, the amount of activation energy in the strain of 0.3 is 394.6258 kJ/mol. [ABSTRACT FROM AUTHOR]

Spot welding process due to its ability to create a qualitative connection between metal plates and the absence of restrictions on old welding methods such as the impossibility of welding metals by many differences in their melting point is considered as one of the fastest and most economical methods. In this method, an atomic bonding is created on the surface of plates due to high-velocity impact and metal plates are welded together. In the present study, a gas mixture detonation set up was used to perform the impact spot welding tests. Also, the steel plate with a thickness of 4mm was considered as a base plate and steel plates with 1, 2, and 3mm thickness were used as front layers. They were under direct contact with flat- and spherical-nosed metallic projectiles with a mass of 650 and 1300g, respectively. The diameter of the projectiles was 25mm and the average velocity was 600 meters per second. To study the morphology of the weld interface in impact spot welding, the interface of the welds was studied using scanning electron microscope (SEM). Also, the effect of flyer plate thickness and stand-off distance on the spot welding of plates due to projectile impact was studied. The results showed that by increasing the thickness of the flyer plate, the formation of a damaged central area will be decreased. The results also confirmed that when higher stand-off distance was utilized, the velocity of impact was not sufficient to create continuous weld. [ABSTRACT FROM AUTHOR]

Spot welding process due to its ability to create a qualitative connection between metal plates and the absence of restrictions on old welding methods such as the impossibility of welding metals by many differences in their melting point is considered as one of the fastest and most economical methods. In this method, an atomic bonding is created on the surface of plates due to highvelocity impact and metal plates are welded together. In the present study, a gas mixture detonation set up was used to perform the impact spot welding tests. Also, the steel plate with a thickness of 4mm was considered as a base plate and steel plates with 1, 2, and 3mm thickness were used as front layers. They were under direct contact with flat- and spherical-nosed metallic projectiles with a mass of 650 and 1300g, respectively. The diameter of the projectiles was 25mm and the average velocity was 600 meters per second. To study the morphology of the weld interface in impact spot welding, the interface of the welds was studied using scanning electron microscope (SEM). Also, the effect of flyer plate thickness and stand-off distance on the spot welding of plates due to projectile impact was studied. The results showed that by increasing the thickness of the flyer plate, the formation of a damaged central area will be decreased. The results also confirmed that when higher stand-off distance was utilized, the velocity of impact was not sufficient to create continuous weld. [ABSTRACT FROM AUTHOR]

In this research, the effect of temperature and time on the properties of AISI420/SAF2507 dissimilar joint produced by transient litpd phase bonding process was investigated. A BNi-2 interlayer witb 25 pm thickness was inserted between two dissimilar steel samples. The bonding process was performed at 1050 oC and 1100 oC for different bonding times. The microstructures of the joints were studied using optical microscope, scanning electron microscope and energy dispersive X-ray spectroscopy. Microhardness and tensile shear strength of bonded samples were investigated. Isothermal solidification was completed for the joints bonded at 1050 oC and 1100 oC for 45 min and 30 min, respectively. ASZ and ISZ areas of the bonding zone at the bonding temperature of 1050 oC indicated the highest (520 HV) and the lowest (300 HV) microhardness values, respectively. Sample bonded at 1050 oC for 1 min indicated the lowest tensile strength (196 MPa) and sample bonded at 1100 oC for 60 min indicated the highest tensile strength (517 MPa). [ABSTRACT FROM AUTHOR]

Commercial pure (CP) titanium has many applications in biomaterials especially in implants due to its excellent biocompatibility. Despite the importance of surface properties in bioapplications, limited research has been conducted to improve surface properties of CP titanium by improving the structure. Therefore, the purpose of this research is to improve the corrosion and wear properties of CP titanium by reducing grain size by multi-directional forging (MDF) process. For this purpose, annealed CP titanium samples were forged by MDF up to six passes at ambient temperature and 220°C. To investigate the corrosion properties of specimens, the tafel polarization test was performed in a simulated body fluid (SBF) solution. The tribological properties were also investigated by pins-on-disk test at sliding speed and applied stress of 0.2 (m/s) and 1MPa, respectively. The results of microstructure analysis of the samples using a scanning electron microscope (SEM) equipped with EBSD showed that the ultrafine grain structure was formed in titanium CP, after 6 passes of the MDF. The results of the investigation of the tafel polarization test showed that the corrosion resistance of the samples increased with applying MDF and increasing the pass number, regardless of the processing temperature. Also, the corrosion resistance of MDFed samples at 220°C temperature was higher than the MDFed samples at ambient temperature. Wear resistance of CP titanium was also increased, by decreasing the grain size. The results of the investigation of surface morphology of samples using a field-emission scanning electron microscope showed mainly the abrasive and delamination wear mechanisms. [ABSTRACT FROM AUTHOR]

In this study, the effect of platinum-aluminide coating parameters on surface roughness of nickel-based superalloy Rene®80 was evaluated. For this purpose, different thicknesses of Pt-layer (2, 4, 6 and 8µm) were plated on the Samples. Then diffusion aluminide coating in two types, high tempeature-low activity and low temperature-high activity was performed. The results of structural investigations by scanning electron microscope and X-Ray diffraction indicated a three-zone structure of coating in all thicknesses of platinum layer, as well as in the two methods of aluminizing. Surface roughness of coatings was measured in three steps: 1-after Pt plating, 2-after Pt diffusion, and 3-after aluminizing and final aging. The results showed that the thickness of Pt and the final thickness of the coating directly affected the surface roughness. The minimum surface roughness was created by high temperature low activity with 2µ of Pt-layer (2.6µm) and the maximum of surface roughness was obtained in low-temperature high activity with 8µ of the Pt-layer (8.8 µm). [ABSTRACT FROM AUTHOR]

Background and Objective: Currently, photocatalysts have become a major focus of research in physics, chemistry, and surface engineering. It is hoped that this science help to solve various environmental problems. This study investigated the effect of ultraviolet lamp type on the removal efficiency of xylene utilizing the fixation of TiO2 nanoparticles on the activated carbon absorber and passing different concentrations of polluted air through xylene. Materials and Methods: In this experimental study, after the fixation of nanoparticles on activated carbon, the produced catalyst characteristics with the specific surface area were determined using Brunauer-Emmett-Teller (BET) analysis and scanning electron microscope (SEM). A dynamic concentrator system was used in order to produce xylene vapor. Moreover, the photocatalytic removal efficiency of xylene with three inlet concentrations of the pollutant was studied under ultraviolet rays in the wavelengths of A and C regions. Results: The results of BET analysis and SEM images showed that nanoparticles were well fixed on the surface of activated carbon. Moreover, the photocatalytic removal efficiency in the concentrations of 50, 100 and 300 ppm was equal to 87.8%, 98.9%, and 90.8%, respectively. In addition, no significant difference was observed between ultraviolet A and C regarding photocatalytic removal efficiency of xylene. Conclusion: According to the results of this study, the inlet concentration of the pollutant had an effect on its photocatalytic removal efficiency. However, there was no significant difference between ultraviolet A and C regarding photocatalytic removal efficiency of xylene. [ABSTRACT FROM AUTHOR]

In this research, pollen grains of some species of Grumorsae group of Ranunculus were studied. In doing so, pollen grains of 13 species were studied by light microscope and the surface of nine pollen grains has studied by Scanning Electron Microscope. Among these species, in addition to previous pollen types in the genus Ranunculus, a new type (Thalictrum flavum L.) was reported. Finally, we could distinguish the species based on pollen grains characters and prepare an identification key. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of constructional elements on the biomechanical behavior of desert locust hind wing. First, the microstructure of the insect wing is investigated using scanning electron microscope. The results of the scanning electron microscopy are used to develop finite element models of the wing with different constructional elements. The presented models are studied under the inertial and aerodynamic loads applied during flight and the obtained stresses and displacements are assessed. The results show that longitudinal veins, longitudinal and cross veins, corrugations, corrugations and longitudinal veins and finally a combination of corrugations and longitudinal and cross veins cause, on average, a 4, 25.75, 4.34, 184.54, 768.5 times decrease of the achieved principal stresses in comparison with a wing without the mentioned constructional elements. Constructional elements of the locust wing play an important role to stablize the pattern of stress distribution in the wing during flight. Further, the existence of the mentioned constructional elements causes a decrease in the variation of the stress within a stroke-cycle. In addition, it is shown that the inertia and aerodynamic forces have less effect on the wing deformation than the elastic ones. The results of this research may be helpful in the development of lightweight structures with high strength. [ABSTRACT FROM AUTHOR]

The main aim of this experiment is to investigate the effects of Nano-size Al2O3 on the mechanical properties and microstructure of multi-passes friction stir welding of Al 2024 lap joint. Nano particles were added into the joint line. A combination of rotational speed and travelling speeds were performed. Optical microscopy and scanning electron microscope were used to investigate the microstructure and fracture surface of samples respectively. Optimum condition (sample) was selected due to highest ultimate tensile strength (UTS). It was seen that sample which included Nano particles and fabricated by 1400 rev/min rotational speed and 16 mm/min travelling speed in second pass of continues welding had improvement in UTS in comparison to one pass welded sample of particle free and after that increasing the number of passes reduce the UTS. The average micro hardness of the sample which was particle rich were increased in comparison to particle free sample in nugget zone. Increasing the number of passes was not effect average micro hardness in nugget zone significantly. Grain sizes were reduced by 2 passes welding and after that no significant reduction has been seen. [ABSTRACT FROM AUTHOR]