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排序方式: 共有113条查询结果,搜索用时 31 毫秒
1.
Sevda Dehghani Ahad Hanifpour Mehdi Nekoomanesh-Haghighi Samahe Sadjadi Seyed Amin Mirmohammadi Ali Farhadi Naeimeh Bahri-Laleh 《应用聚合物科学杂志》2020,137(22):49018
The main aim of this research is to decrease the amount of AlCl3 content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl3 on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl3 and TiCl4 onto Al2O3, SiO2, and mixed supports, that is, Al2O3/FeCl3 and SiO2/FeCl3. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl3; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al2O3 and SiO2, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV40 and KV100). The viscosity index (VI) values, derived from KV40 and KV100, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by 1H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures. 相似文献
2.
Mahmoud Ghazavi Ahad Ehsani Yamchi Javad Nazari Afshar 《Geotextiles and Geomembranes》2018,46(3):312-318
In very soft soils, the bearing capacity of stone columns may not improve significantly due to very low confinement of the surrounding soil. Therefore, they may be reinforced with geosynthetics by using vertical encasement or horizontal layers. Very limited studies exist on horizontally reinforced stone columns (HRSCs). In this research, some large body laboratory tests have been performed on horizontally reinforced stone columns with diameters of 60, 80, and 100?mm and groups of stone columns with 60?mm diameter. Results show that the bearing capacity of stone columns increases by using horizontally reinforcing layers. Also, they reduce lateral bulging of stone columns by their frictional and interlocking effects with stone column aggregates. Finally, numerical analyses were carried out to study main affecting parameters on the bearing capacity of HRSCs. Numerical analysis results show that the bearing capacity increases considerably with increasing the number of horizontal layers and decreasing space between layers. 相似文献
3.
Ahad Hanifpour Naeimeh Bahri-Laleh Mehdi Nekoomanesh-Haghighi 《Polymer Engineering and Science》2020,60(12):2991-3000
This study aims to investigate the effects of methacrylate-functionalized polyhedral oligomeric silsesquioxane (MA-POSS) on polyolefin-based adhesives. The so called adhesive was synthesized by the cooligomerization of 1-decene/9-decene-1-ol monomers using a Ti amine bis-phenolate catalyst, [Ti{2,2′-(OC6H2-4,6-tBu2)2NHC2H4NH(OiPr)2], which was subsequentlyacrylated via a simple reaction with methacryloyl chloride. Different weight fractions of MA-POSS nanoparticles were solution blended with synthesized adhesive and undergone curing reaction with blue light. Observation of a unique tan δ peak in dynamic mechanical thermal analysis (DMTA) curve was clear evidence that two employed moieties were miscible and only one hybrid polymeric phase was created. Most noticeably, significant increase in mechanical parameters was detected in the lower inclusion compositions, 0.2-1 wt% of MA-POSS, where flexural strength and flexural modulus were increased up to 99 and 110%, respectively. Furthermore, thermal stability of the synthesized nanocomposite enhanced dramatically by increasing MA-POSS weight fraction. Influence of employed nanoparticles on adhesion properties of synthesized nanocomposites was evaluated with tensile shear bond strength and pull off analysis. According to the adhesion results, the MA-POSS causes an adhesion promotion on the fabricated adhesive/POSS nanocomposites. 相似文献
4.
Gholipoor Ahad Baseri Hamid Shabgard Mohammad Reza 《Journal of Mechanical Science and Technology》2015,29(5):2213-2218
Journal of Mechanical Science and Technology - Material removal rate (MRR), tool wear ratio (TWR) and surface roughness (SR) obtained by near-dry EDM process were compared with wet and dry EDM at... 相似文献
5.
6.
Li Jingqi Yue Weisheng Guo Zaibing Yang Yang Wang Xianbin Syed Ahad A. Zhang Yafei 《纳微快报(英文)》2014,6(3):287-292
Nano-Micro Letters - A vertical carbon nanotube field-effect transistor (CNTFET) based on silicon (Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled... 相似文献
7.
Maryam Mehrnezhad Abbas Ghaemi Bafghi Ahad Harati Ehsan Toreini 《International Journal of Information Security》2017,16(2):133-149
This paper introduces pictorial intelligent system for human identification (PiSHi), an image-based captcha which uses three human cognitive abilities to distinguish humans from machines. The first is the human ability to easily recognise the image’s upright orientation. The second is the human brain’s ability in recognising a picture’s content when it is only partially visible. And the third is the human ability in unconscious decision making when encountering pictorial challenges. This work models such complicated human patterns in problem solving for the first time. In order to extract these behavioural patterns and save them in a pattern database, we have implemented our own captcha and performed a series of experiments. PiSHi’s interface presents the user with a set of distorted pictures and asks her to click on the upright orientation of all the pictures in any preferred order. Next, it captures the user’s interaction patterns, compares them with the ones saved in the pattern database, and grants her a corresponding credit. Based on this credit, the user either passes or fails the test, and participates in updating the picture database. Our experiments indicate that human users can solve our proposed captcha effectively—with an accuracy of 99.44 %. Besides, our proposed system is secure against several types of attacks including random guessing and reverse image search engines. The results offer the possibility of utilising the identified human behavioural models in practical captchas. 相似文献
8.
Md. Wasim Khan Natarajan A. Arivarasu Shubha Priyamvada Sara Anees Khan Sheeba Khan Ahad Noor Khan Yusufi 《Journal of Functional Foods》2013,5(2):956-967
Sodium nitrite (SNT) widely used as a curative agent in meat processing industry possesses cell-transforming mutagenic and cytogenic properties. Dietary omega-3 polyunsaturated fatty acids (ω-3 PUFA) has been shown to reduce the severity of certain types of cancers, cardiovascular and renal diseases. The present study examined whether feeding of fish oil (FO)/flaxseed oil (FXO) has protective effect against SNT-induced toxicity. SNT significantly altered the activities of serum creatinine (Crt), blood urea nitrogen (BUN), metabolic and brush border membrane (BBM) enzymes. SNT caused significant imbalances in the antioxidant system associated with increased lipid peroxidation (LPO). Feeding of FO and FXO with SNT ameliorated the changes in various parameters caused by SNT. Nephrotoxicity parameters lowered and enzyme activities of carbohydrate metabolism, BBM and radioactively labeled inorganic phosphate (32Pi) transport were improved to near control values. The results of the present study suggest that ω-3 PUFA-enriched FO and FXO from sea-foods and plant sources respectively are similarly effective in reducing SNT-induced nephrotoxicity and oxidative damage. 相似文献
9.
In order to monitor articles/patents in nanotechnology, there is little agreement on a universal lexical query or even an explicit definition of nanotechnology. Here in the light of a proposed definition, a set of case studies has been conducted to remove keywords which are not exclusive to nanotechnology. This resulted in a collective and abridged lexical query (CALQ) for nanotechnology delineation. Through bibliometric quantification of already-proposed as well as the novel keywords, it was shown that all keywords included in CALQ have considerable exclusive retrieval and precision, while the removed keywords do not satisfy either of these numerical thresholds. This approach may also be applied for the future updating of CALQ. 相似文献
10.
Mohammad A. Altamimi Mohsin Kazi Mshaan Hadi Albgomi Abdul Ahad Mohammad Raish 《Drug development and industrial pharmacy》2013,39(7):1073-1078
The purpose of this work is to develop novel lipid-based self-nanoemulsifying drug delivery systems (SNEDDS) as carriers for transdermal delivery of curcumin. SNEDDS containing black seed oil, medium chain mono- and diglycerides and surfactants, were prepared as curcumin delivery vehicles. Their formation spontaneity, morphology, droplet size, and drug loading were evaluated. Gel preparation containing two of the SNEDDS formulations were used in the carrageenan induced paw edema to evaluate the anti-inflammatory effect. Results showed droplet size as low as 71?nm. The highest drug loading was observed with SNEDDS-F6 of ~45?mg/g. In in-vivo investigation, SNEDDS-F6 exhibited significant anti-inflammatory activities in terms of 80% reduction in paw edema when compared with positive control. The prepared SNEDDS with the elevated entrapment efficiency, good transdermal penetration ability could be a suitable candidate for effective transdermal curcumin skin delivery. 相似文献