Synthesis,structure and thermal protective behavior of silica aerogel/PET nonwoven fiber composite     

Zahra Talebi Mazraeh-shahi  Ahmad Mousavi Shoushtari  Ahmad Reza Bahramian  Majid Abdouss 《Fibers and Polymers》2014,15(10):2154-2159

In recent years, flexible, mechanically strong and environmental friendly thermal insulation materials have attracted considerable attention. In this work, silica aerogel/polyethylene terephthalate (PET) nonwoven fiber composite with desirable characteristics was prepared via a two-step sol-gel process followed by an ambient drying method through immersing the PET nonwoven fiber into silica sol. The silica aerogel particles were characterized by FTIR, FE-SEM, TGA and nitrogen adsorption analysis. The morphology and hydrophobic properties of neat PET nonwoven fiber and its silica aerogel composite were also investigated. For studying thermal protective properties, the thermal diffusivity was calculated from temperature distribution curves. The mean pore size of 11 nm, the surface area of 606 m²/g and the total pore volume of 1.77 cm³/g for the silica aerogel particles in the composite are obtained from nitrogen adsorption analysis, indicating the aerogel can maintain its high porosity in the nonwoven composite structure. Silica aerogel particles were efficiently covered the surface of the PET fibers and completely filled the micron size pores of the nonwoven fiber leading to a stronger hydrophobicity and higher thermal insulation performance in the aerogel composite samples compared to the neat PET nonwoven. In this regard, an almost 64 % decrease in the thermal diffusivity was achieved with 66 wt% silica aerogel.  相似文献   

Histology and ultrastructure of the developing superficial digital flexor tendon in rabbits     

Oryan A  Shoushtari AH 《Anatomia, histologia, embryologia》2008,37(2):134-140

This study was designed to investigate the developmental changes in the superficial digital flexor tendon (SDFT) of the white New Zealand rabbit, from 5 to 7 days pre-natal to 112 days post-natal (PN), at histological and ultrastructural levels. The tendons changed from being highly cellular with 13079 ± 2538 cell/mm² and little directional organization to a longitudinally oriented, predominantly connective tissue structure with relatively few, mature tenocytes (2384 ± 365 cell/mm²). Fibrillogenesis was seen in isolated vacuoles of fibroblast cytoplasm during fetal life as well as after birth, but less frequently with increasing age. At the ultrastructural level, there was a progressive increase in the mean diameter of collagen fibrils with age throughout the population , until PN day 28. A bimodal distribution of collagen fibril size was first observed on PN day 56 while at day 112, the fibrils were fully differentiated and showed a multimodal size distribution. The development of elastic fibres preceded that of collagen fibres and accompanied progressively more marked sinusoidal crimping in collagen fibres on PN days 7 and 14. The tendons of older animals became less tightly crimped. The cells of the epi- and endotenon were less mature and relatively undifferentiated compared with the cells in the body of the tendon of the same age, which might explain their ability to initiate healing of tendon injuries in older animals. In conclusion, extensive changes were observed in tendons during growth and maturation, with diameters of collagen fibrils, tissue orientation and cellularity being the parameters affected, probably due largely to increased physical activity.  相似文献   

Comparison between artificial neural network and response surface methodology in the prediction of the production rate of polyacrylonitrile electrospun nanofibers     

Komeil Nasouri  Ahmad Mousavi Shoushtari  Mehrdad Khamforoush 《Fibers and Polymers》2013,14(11):1849-1856

This paper focused on using response surface methodology (RSM) and artificial neural network (ANN) to analyze production rate of electrospun nanofibers. The three important electrospinning factors were studied including polymer concentration (wt %), applied voltage (kV) and the nozzle-collector distance (cm). The predicted production rates were in agreement with the experimental results in both ANN and RSM techniques. High regression coefficient between the variables and the response (R ²=0.975) indicates excellent evaluation of experimental data by second-order polynomial regression model. The regression coefficient was 0.988, which indicates that the ANN model was shows good fitting with experimental data. The obtained results indicate that the performance of ANN was better than RSM. It was concluded that applied voltage plays an important role (relative importance of 42.8 %) against production rate of electrospun nanofibers. The RSM model predicted the 2802.3 m/min value of the highest production rate at conditions of 15 wt % polymer concentration, 16 kV of the applied voltage, and 15 cm of nozzle-collector distance. The predicted value showed only 4.4 % difference with experimental results in which 2931.0 m/min at the same setting was observed.  相似文献   

Molecular characterization of the surface glycoprotein genes of highly pathogenic H5N1 avian influenza viruses detected in Iran in 2011     

Ebrahim Kord  Amir Kaffashi  Hadi Ghadakchi  Fatemeh Eshratabadi  Zakaria Bameri  Abdelhamed Shoushtari 《Tropical animal health and production》2014,46(3):549-554

Highly pathogenic avian influenza (HPAI) H5N1 virus is causing the death of a large number of wild birds and poultry. HPAI H5N1 was reported in the north of Iran in 2011. In this study, two A/Chicken/Iran/271/2011 and A/Duck/Iran/178/2011 viruses were genetically characterized by sequence analysis of Hemagglutinin (HA) and Neuraminidase (NA) genes. Phylogenetic analysis revealed that these viruses were different from previous Iranian isolates (Clade 2.2) and belonged to the subclade 2.3.2.1. The results showed that the detected viruses are almost identical to each other and closely related to HPAI H5N1 strains isolated in Mongolia in 2010. Based on the amino acid sequence analysis, these viruses at their HA cleavage sites contained the multibasic amino acid motif PQRERRRK-R/GLF lacking a lysine residue compared with the previous reports of the same motif. There is also a 20-amino acid deletion (resides 49–69) in the NA stalk similar to other viruses isolated after 2000. It seems that introduction of HPAI H5N1 to Iran might have happened by wild birds from Mongolian origin virus.  相似文献   

Mesquite rhizobia isolated from the Sonoran Desert: Physiology and effectiveness     

Nastaran H. Shoushtari  Ian L. Pepper 《Soil biology & biochemistry》1985,17(6):797-802

A mesquite Rhizobium isolated from the Sonoran Desert (strain AZ-M1) and a commercial mesquite Rhizobium obtained from the Nitragin Company (strain 31A5) were chosen as superior strains from among many evaluated in a screening study of the efficiency of mesquite rhizobia. Both strains were fast-growing and acid-producing in denned media. The desert strain AZ-M1 had the shortest mean generation time of 3.5 h. Strain 31A5 grew better in broth amended with various sugars and amino acids, but generally produced less acid. The desert strain showed greater resistance to various antibiotics than did 31A5. In a greenhouse study N applied at high rates inhibited N₂ fixation when either strain was used as inoculant for mesquite seed. At low N rates, AZ-M1 fixed more N than 31A5. Total N, nodule weight, C₂H₂ reduction, mesquite shoot weight and root weight were all significantly increased when AZ-M1 was the applied inoculant. This study shows that the mesquite Rhizobium AZ-M 1 isolated from the Sonoran Desert is infective and effective on mesquite seedlings. Fast growth rate, acid production and high resistance to antibiotics in laboratory media may indicate the adaptation of this organism to its microbial niche in the Sonoran Desert.  相似文献   

Quantum dot/polyvinyl alcohol composite nanofibers membrane as highly sensitive fluorescence quenching-based sensors     

Matin Mahmoudifard  Ahmad Mousavi Shoushtari  Maryam Shanehsaz 《Fibers and Polymers》2014,15(9):1797-1803

Nanofibrous membranes are intensively applied to fabricate advanced intelligent devices like highly sensitive sensors due to their flexibility, high porosity, high surface area and good mechanical and chemical stability. In this work, fluorescent cadmium telluride (CdTe) quantum dots (Q.Ds) were synthesized and then uniformly embedded in poly vinyl alcohol (PVA) nanofibers by electrospinning technique to serve as reversible quenching fluorescence-based sensor to detect the traces of benzene, toluene and xylene vapors selectively at room temperature. Fluorescence analysis suggested that Q.Ds preserve their original fluorescent property in solid nanofiber as if they were in solution. Scanning electron microscopy images showed the uniform diameter of nanofibers. In addition, Fluorescence and transmission electron microscopy (TEM) measurements confirmed the uniform distribution of the Q.Ds into nanofibers structures. The main mechanism of quenching based sensor was designated as electron transfer from thiogalycolic acid (TGA) — capped Q.D surface to target volatile organic compounds (VOC’s) vapors. Fabricated sensor showed selectively sensing upon trace of different target vapors due to the difference in the electronegativity of various VOC’s molecules. For example exposure to more electron withdrawing toluene molecules induces severe quenching effect on fluorescence intensity of Q.D (about 25 %) over xylene exposure. Moreover, it was observed that reducing the diameter of nanofibers enhanced the sensitivity of sensor.  相似文献   

Sequence and phylogenetic analysis of the haemagglutinin genes of H9N2 avian influenza viruses isolated from commercial chickens in Iran     

Ali Reza Homayounimehr  Habibollah Dadras  Abdolhamid Shoushtari  Seyyed Ali Pourbakhsh 《Tropical animal health and production》2010,42(6):1291-1297

To determine the genetic relationship of Iranian viruses, the haemagglutinin (HA) genes from ten isolates of H9N2 viruses isolated from commercial chickens in Iran during 1998–2002 were amplified and sequenced. Sequence analysis and phylogenetic studies were conducted by comparing each isolate with those of the available H9N2 strains at GenBank. All these ten isolates had the same sequence –R-S-S-R/G-L– of proteolytic cleavage site of the HA. Nucleotide sequence comparisons of HA gene from Iranian isolates showed 95.2–99.1% identity within the group. Five isolates had leucine (L) at position 226 instead of glutamine (Q). Phylogenetic analysis showed that all our isolates belonged to the G1-like sublineage. Also these isolates showed some degree of homology with other H9N2 isolates e.g., 94.3–96.9% with qu/HK/G1/97, 96.1–98.6% with pa/Chiba/1/97, 95.6–98.2% with pa/Narita/92A/98, and 94.0–96.3% with HK/1073/99. On the basis of phylogenetic and molecular characterization evidence, we concluded that the H9N2 subtype influenza viruses circulating in chicken flocks in Iran since 1998–2002 had a common origin. The results of this study indicated that all Iranian viruses have the potential to emerge as highly pathogenic influenza virus, and considering the homology of these isolates with human H9N2 strains, it seems that the potential of these avian influenza isolates to infect human should not be overlooked.  相似文献   

RSM and ANN approaches for modeling and optimizing of electrospun polyurethane nanofibers morphology     

Amir Rabbi  Komeil Nasouri  Hossein Bahrambeygi  Ahmad Mousavi Shoushtari  Mohammad Reza Babaei 《Fibers and Polymers》2012,13(8):1007-1014

This paper focused on using response surface methodology (RSM) and artificial neural network (ANN) to analyze polyurethane (PU) nanofibers morphology synthesized by electrospinning. The process was characterized in detail by using experimental design to determine the parameters that may affect the nanofibers morphology such as polymer concentration, a tip to collector distance and applied voltage. It was concluded that solution concentration plays an important role (relative importance of 79.85 %) against nanofibers diameter and its standard deviation. Based on the results, applied voltage has a different effect on the nanofiber diameter at low and high solution concentrations. Moreover, the tip to collector distance parameter has no significant impact on the average nanofiber diameter. The finest PU nanofiber (201 nm) was obtained from experimental under conditions of: 9 w/v% polymer concentrations, 12 cm tip to collector distance and 16 kV applied voltage. The results show a very good agreement between the experimental and modeled data. It was demonstrated that both models (specially, in case of neural network) are excellent for predicting diameter of PU nanofibers. Furthermore, numerical optimization has been performed by considering desirability function to access the region in design space that introduces minimum average diameter.  相似文献   

Fabrication and characterization study of electrospun quantum dot — poly vinyl alcohol composite nanofiber for novel engineering applications     

Matin Mahmoudifard  Ahmad Mousavi Shoushtari  Afshin Mohsenifar 《Fibers and Polymers》2012,13(8):1031-1036

CdTe quantum dot/PVA (poly vinyl alcohol) composite nanofiber was successfully fabricated by eletrospinning process. CdTe quantum dots were uniformly dispersed and stabilized into solid nanofiber structure. Spectrofluorometer analysis revealed whenever Q.D??s enter to the PVA solution, due to the aggregation of Q.D??s red shift happens; however, when blend Q.D-PVA solution changes to nanofiber form via electrospining, this shift phenomenon offsets and original fluorescence properties of Q.D??s does not degraded due to excellent individual dispersion of Q.D in the nanofibers structure. It is also turned out that the proportion of Q.D??s incorporated in the composite solution of electrospining has strong influence on the nanofiber morphology. Addition of Q.D??s to PVA solution causes remarkable changes in the conductivity and solution viscosity, therefore different nanofiber morphologies can be obtained as evidenced by scanning electron microscopy. Furthermore, differential scanning calorimetric (DSC) revealed addition of small amount of Q.D??s to the electrospining solution causes strenuous improvement in crystalinity and heat of nanofiber fusion. Fluorescence and transmission electron microscopy (TEM) measurements confirmed the evenly dispersion of the Q.D??s into nanofibers structures.  相似文献   

Full sequence analysis of hemagglutinin and neuraminidase genes and proteins of highly pathogenic avian influenza H5N1 virus detected in Iran, 2015     

Yegani  Sima  Shoushtari  Abdel-Hamid  Eshratabadi  Fatemeh  Molouki  Aidin 《Tropical animal health and production》2019,51(3):605-612

Over the last two decades, the highly pathogenic avian influenza H5N1 virus has gained a lot of attention due to its zoonotic and mutative nature. Iran is among the countries significantly affected by the virus as it hosts migratory birds during seasonal migration. In this study, the molecular characterizations of hemagglutinin (HA) and neuraminidase (NA) genes and proteins of H5N1 strain A/chicken/Iran/8/2015 detected in backyard poultry, Mazandaran province, were investigated. Phylogenetic analysis classified this virus as a member of subclade 2.3.2.1c, with the cleavage site motif of “PQRERRRK-R/GLF”. HA carried a few mutations altering affinity to mammalian cells; however, the virus was categorized as avian. NA protein had the 20-amino acid deletion at aa position 49–69 similar to those isolated since 2000. Mutations of H253Y and H274Y contributing to antiviral resistance were present in NA. From this analysis, it can be concluded that the wild migratory birds flying from Western Asia to Eastern Africa are probably the main carriers of seasonal H5N1 in the country.

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