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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Progress in Color, Colorants and Coatings
- نوع مقاله: Journal Article
- کلمات کلیدی: Surface functionalization,Graphene Oxide,Natural Polymer,Epoxy Coatings,Cure kinetics
- چکیده:
- چکیده انگلیسی: Epoxy is a versatile resin used in different fields such as coatings, colors, colorants, and composites. Adding nano-scale fillers/additives to the epoxy has valued epoxy coatings for engineering applications, and opened the time of advanced epoxy-based nanocomposite coatings. In the present work, graphene oxide GO was chemically functionalized with starch, as a natural polymer, and added to the epoxy/amine system. Differential scanning calorimetry was utilized to assess the cure kinetics of neat epoxy and its composites containing pristine and starch-functionalized GO GO-St. Cryofractured surfaces of epoxy/GO and epoxy/GO-St nanocomposites are detected by scanning electron microscopy. Overall, the results are indicative of appropriateness of surface functionalization of GO by starch for high-performance coating applications. Hindered cure observed in the case of epoxy/GO was conquered by the attachment of starch to GO; moreover, tree-like fracture was responsible for higher fracture resistance due to starch.
- انتشار مقاله: 11-10-1348
- نویسندگان: E. Yarahmadi,Kh. Didehban,M. Shabanian,M.R. Saeb
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Science and Technology A:Science
- نوع مقاله: Journal Article
- کلمات کلیدی: Water stress,Osmotic adjustment,Colza (Brassica napus L.),24-epibrassinolide
- چکیده:
- چکیده انگلیسی: Brassinosteroids are phytohormones possessing a wide spectrum of antistress activity. To see
whether this hormone is able to ameliorate the effects of water stress, the effects of 24-epibrassinolise on
plant growth, accumulation of osmolytes (proline, sugars and ions), lipid peroxidation and electrolyte leakage
were investigated in Colza (Brassica napus L. cv. Fusia) plants which were under water stress. The seeds
were sown in plastic pots containing sand, clay and peat (in a proportion of 1:1:1). Solution of 24-epibrassinolid
at 10-7 M concentration containing 0.01% Tween-20 (polyoxyethylene sorbitan) was sprayed on
leaves at intervals of 1, 2 and 3 weeks after sowing. Control plants were sprayed with 0.01% Tween-20, and
water treatment was applied 26 days after germination, withholding water for 3 or 4 days. One month after
sowing, plants were harvested. Lipid peroxidation and electrolyte leakage significantly increased under water
stress, but when plants were pretreated with 24-epibrassinolid and put under water stress these parameters
decreased, revealing that less oxidative damage occurred in this group. Proline and reduced sugars content
was increased when 24-epibrassinolide were applied. FW and DW were significantly decreased under water
stress. Water stress also increased the uptake of K and Ca, but the uptake of Na significantly decreased. 24- epibrassinolide considerably increased ions uptake by plants. Taken together, these results showed that 24- epibrassinolide alleviated the effects of water stress and increased the tolerance of plants to stress by
increasing osmolytes accumulation and therefore could be used to improve crops in harsh conditions.- انتشار مقاله: 30-02-1386
- نویسندگان: E. AHMADI MOUSAVI,K. MANOCHEHRI KALANTARI,S. R. JAFARI
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Iron and Steel Society of Iran
- نوع مقاله: Journal Article
- کلمات کلیدی: Stainless steel,A-TIG welding,delta-ferrite,oxide flux
- چکیده:
- چکیده انگلیسی: Gas tungsten arc welding is a popular process in those applications requiring a high degree of quality and accuracy. However, this process has a big disadvantage against the substantially high productivity welding procedures. Hence, many efforts have been made to improve its productivity. One of these efforts is the use of activating flux (A-TIG welding). In this study, the performance of A-TIG welding on 304L austenitic stainless steel plates has been presented. Two oxide fluxes, TiO2 and SiO2 were used to investigate the effect of A-TIG welding process on weld morphology, microstructure and mechanical properties of weldments. The experimental results indicated that A-TIG welding could increase the weld penetration and depth-to-wide ratio. It was also found that A-TIG welding could increase the delta-ferrite content of weld metals and improve the mechanical properties. Moreover, a 2D axial symmetric model was developed to simulate the flow behavior in the melting pool. These results were compared to those experiments carried out on a stainless steel (304L) melted by a stationary heat source.
- انتشار مقاله: 15-04-1393
- نویسندگان: E. Ahmadi,A. R. Ebrahimi,R. Azari Khosroshahi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Nanoscience and Nanotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Drug Delivery,nano silica,Surface modification,Ibuprofen,SBA-15
- چکیده:
- چکیده انگلیسی: Mesoporous silica nanoparticles with unique structure (SBA-15) were synthesized and modified by [3-(2-Aminoethylamino) propyl] trimethoxysilane (AEAPTMS). The synthesized nanoparticles were characterized by TGA, N2 adsorption, SEM, FTIR, CHN elemental analysis. The total weight loss for the modified SBA-15 is 15.2% and thermal analysis revealed that 1.5 mmol AEAPTMS/1g SBA-15 had been grafted. The modified particles were used as a drug delivery system. Ibuprofen as common nonsteroidal anti-inflammatory drugs was used to evaluate the controlled drug release properties of modified SBA-15.The results show that the modification of SBA-15 with organic groups such as [3-(2-Aminoethylamino) propyl] trimethoxysilane and (3-aminopropyl) triethoxysilane (APTES) improve the organophilicity of the SBA-15 and the drug loading efficiency. The results of drug delivery experiments reveal that the surface modification of SBA-15 with amino groups significantly decreases the drug delivery rate. The data obtained from the in vitro release studies was used to evaluate the kinetic mechanism of release; the initial 60% release of drug at pH 7.4 fits with the Korsmeyer – Peppas model, when diffusion is the main drug release mechanism.
- انتشار مقاله: 24-01-1394
- نویسندگان: Z. Mohamadnia,E. Ahmadi,M. Ghasemnejad,S. Hashemikia,A. Doustgani
- مشاهده
- جایگاه : پژوهشی
- مجله: Archives of Razi Institute
- نوع مقاله: Journal Article
- کلمات کلیدی: Drug resistance,bovine,mastitis,Shige toxin-producing Escherichia coli (STEC),virulence
- چکیده:
- چکیده انگلیسی: Bovine subclinical mastitis is regarded as a devastating disease due to the economic costs imposed on dairy husbandry. Moreover, it is a hazard in the public sector in the cases of zoonotic bacteria because of the potential role of unpasteurized milk and dairy products to propagate the infectious agent to the human food chain. The present study aimed to evaluate the frequency, virulence content, and antimicrobial resistance profile of Shiga toxin-producing Escherichia coli (STEC) strains isolated from bovine subclinical mastitis in Kurdistan Province, West of Iran. A total of 400 bovine subclinical mastitis milk samples recognized in the California Mastitis Test were collected aseptically and analyzed for the presence of E. coli phenotypically and molecularly. The isolates were genotypically screened for stx1, stx2, and eae genes. Furthermore, O157:H7 STEC strain was searched among the isolates in a duplex polymerase chain reaction. The antimicrobial resistance scheme of the isolates was determined using the agar disk diffusion method. In general, 173 (43.25%) E. coli isolates were detected among which 39 (22.54%) isolates were STEC. The frequency of STEC virulence genotypes was stx2 (25 isolates, 64.10%), stx2+eae (6 isolates, 15.38%), stx1+stx2 (6 isolates, 15.38%), and stx1+stx2+eae (2 isolates, 5.12%). In addition, three O157: H7 strains were identified with the genetic content of stx1+stx2+eae (2 isolates) and stx1+stx2 (1 isolate). The most prevalent antimicrobial resistance was observed against streptomycin, tetracycline, and ampicillin. Gentamycin, amoxicillin-clavulanic acid, and trimethoprim-sulfadiazine were the most effective antibiotics against O157 strains, whereas gentamycin, ciprofloxacin, and nitrofurantoin were effective against non-O157 strains. The results revealed the significant role of STEC in bovine subclinical mastitis in the studied region. In addition, the distribution of O157:H7 strain and high prevalence of multidrug resistance among the isolates is a matter of concern. Therefore, there is a potential threat of human infection following the consumption of contaminated milk with STEC in Kurdistan Province, Iran.
- انتشار مقاله: 14-09-1397
- نویسندگان: E. Ahmadi,K. Mardani,A. Amiri
- مشاهده