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排序方式: 共有470条查询结果,搜索用时 9 毫秒
71.
Sara Khademi Ali ShakeriZadeh Razieh Solgi Hosein Azimian Hossein Ghadiri 《IET nanobiotechnology / IET》2021,15(7):594
This study was performed to specify the efficiency of imaging nanoparticle concentration as contrast media in dual‐energy computed tomography (DECT). Gold nanoparticles (AuNPs) and gold nanoparticles‐conjugated folic acid through cysteamine (FA‐Cya‐AuNPs) were both considered as contrast agents. Characterization of NPs was performed using Dynamic Light Scattering (DLS) and zeta potential. The hemocompatibility of NPs was confirmed by different blood parameters such as white blood cell, red cell distribution width, hemoglobin, lymphocytes counts and haemolysis assay. DECT algorithm was confirmed using calibration phantom at different concentrations of NPs and tube potentials (80 and 140 kVp). Then, DECT was used to quantify the concentration of both AuNPs and FA‐Cys‐AuNPs in human nasopharyngeal cancer cells. Mice were injected with non‐targeted AuNPs and targeted AuNps at a concentration of 3 × 103 μg/ml. Then, they were scanned with different tube potentials. The concentration of nanoparticles in the various organs of nude mice was measured through DECT imaging and inductively coupled plasma mass spectrometry (ICP‐MS) analysis. The results of DECT images were compared with ICP‐MS analysis and indicated that they were approximately similar. In sum, FA‐Cys‐AuNPs can be a proper candidate for targeted contrast media in DECT molecular scanning of human nasopharyngeal tumours. 相似文献
72.
Surface engineering technology is a suitable method for coatings on the metal surfaces or performing surface modification treatment,which can improve corrosion resistance and biocompatibility of metals.In this research,corrosion behavior of Nb coating on H 2 SO 4 and HNO 3 treated AISI stainless steel 316L (SS) was evaluated.Nb coating was carried out using physical vapor deposition process on the SS.Characterization techniques including scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) technique were used to investigate the microstructure and morphology of the coated and treated SS.Electrochemical potentiodynamic tests were performed in two types of physiological solutions and compared with the pristine SS specimens.Cyclic polarization tests were performed to evaluate resistivity against pitting.Experimental results indicate that Nb coating and surface treatment of the SS had a positive effect on improvement of corrosion behavior.The decrease in corrosion current densities was significant for coated and treated specimens.The corrosion current density was much lower than the values obtained for pristine specimens. 相似文献
73.
74.
New formulation for compressive strength of CFRP confined concrete cylinders using linear genetic programming 总被引:5,自引:0,他引:5
Amir Hossein Gandomi Amir Hossein Alavi Mohammad Ghasem Sahab 《Materials and Structures》2010,43(7):963-983
This paper proposes a new approach for the formulation of compressive strength of carbon fiber reinforced plastic (CFRP) confined
concrete cylinders using a promising variant of genetic programming (GP) namely, linear genetic programming (LGP). The LGP-based
models are constructed using two different sets of input data. The first set of inputs comprises diameter of concrete cylinder,
unconfined concrete strength, tensile strength of CFRP laminate and total thickness of utilized CFRP layers. The second set
includes unconfined concrete strength and ultimate confinement pressure which are the most widely used parameters in the CFRP
confinement existing models. The models are developed based on experimental results collected from the available literature.
The results demonstrate that the LGP-based formulas are able to predict the ultimate compressive strength of concrete cylinders
with an acceptable level of accuracy. The LGP results are also compared with several CFRP confinement models presented in
the literature and found to be more accurate in nearly all of the cases. Moreover, the formulas evolved by LGP are quite short
and simple and seem to be practical for use. A subsequent parametric study is also carried out and the trends of the results
have been confirmed via some previous laboratory studies. 相似文献
75.
Paola Fabbri Francesco Pilati Roya Aghababazadeh Ghasem Kavei 《Materials Letters》2010,64(20):2265-2268
In this work a new approach has been developed for the synthesis of SiO2@Y2O3 particles with core-shell structure. The method is based on the synthesis of a covalently bonded sacrificial polymer shell grown onto silica particles. It is suitable to promote and stabilize the adsorption of different ions, namely Yttrium from its nitrate solution. After calcination and consequent elimination of the sacrificial polymer shell, the SiO2@Y2O3 core-shell particles are obtained. Results reveal that the shell thickness of these core-shell particles is higher and more uniform than that of particles prepared without sacrificial polymer shell. 相似文献
76.
Saeid Shahraki Sami Khorasani Reza Abdi Behnagh Yassin Fotouhi Hosein Bisadi 《Metallurgical and Materials Transactions B》2013,44(6):1546-1553
In this study, friction stir processing (FSP) was used to produce AA5083/ZrO2 nanocomposite layer. Optical microscopy and SEM were used to probe the microstructures formed in the composite layer. In addition, the mechanical properties of each sample are characterized using both tensile and hardness tests. Results showed that FSP is an effective process to fabricate AA5083/ZrO2 nanocomposite layer with uniform distribution of ZrO2 particles, good interfacial integrity, and significant grain refinement. On processing, in the proper combination of process parameters, the metal matrix composite layer was observed to have increased tensile and hardness properties. 相似文献
77.
In this work, the anticorrosion properties of phenyl trimethoxysilane (PTMS) films coated on aluminium 5000 series alloys were studied. PTMS films were deposited at various cathodic potentials. The optimum electrodeposition potential was found to be ?0.8?V vs. SCE. The coatings were also modified by different amounts of nano-TiO2. In order to introduce corrosion inhibition and a self-repair property of the PTMS film, the addition of chromium (III) corrosion inhibitor in the presence of nano-TiO2 was studied. The anticorrosion performance of coatings was investigated in a 3.5 wt.% NaCl solution. At optimum deposition potential, the ‘critical’ nano-TiO2 and Cr(III) contents were both observed, under which the obtained PTMS coatings show the highest anticorrosion performance. The surface morphologies of PTMS coatings were examined by scanning electron microscopy. The results showed that the coatings deposited at ?0.8?V vs. SCE, from 20?ppm of nano-TiO2 and 0.003 M Cr(III) inhibitor present uniform and compact morphologies. 相似文献
78.
Leila Gorgani Maedeh Mohammadi Ghasem D. Najafpour Maryam Nikzad 《Food and Bioprocess Technology》2017,10(12):2199-2207
Piperine is the natural bioactive component of black pepper (Piper nigrum L.) with several astounding therapeutic properties. In this study, sequential microwave-ultrasound-assisted extraction approach was used for isolation of piperine from black pepper. The effect of various factors such as extraction solvent, particle size of pepper, solvent to solid ratio, microwave power and time and ultrasound temperature and time on the extraction yield of piperine was considered. The maximum extraction yield was 46.6 mg piperine/g pepper which was obtained using ethanol as solvent at the particle size of 0.15 mm, solvent to solid ratio of 20:1, microwave power of 100 W for 1 min, and ultrasound temperature of 50 ° C for 30 min. This extraction yield was higher than those obtained by Soxhlet (39.1 mg/g), microwave-assisted (38.8 mg/g) and ultrasound-assisted (37.0 mg/g) extractions. The purity of the extracted piperine was 81.4% as determined by HPLC analysis. The FTIR and UV-vis analyses confirmed that the structure of piperine remained intact after extraction and purification which is very important for medicinal applications. 相似文献
79.
Mehdi Javani Amir Abdolmaleki Amin Nouri Khorasani 《Journal of Adhesion Science and Technology》2013,27(10):975-985
Crosslinking reaction of polymer by ultraviolet (UV) irradiation has been important in industries. In this work, photocrosslinking of styrene–isoprene–styrene (SIS) triblock copolymer in the presence of benzoin photoinitiator and a dimethacrylate monomer as crosslinking agent was investigated. Curing of samples was initiated under UV irradiation. Benzoin was used as photoinitiator because it contains chromophore group that could absorb UV irradiation. Ethylene glycol dimethacrylate (EGDMA) was used as crosslinking agent, since it has alkene functional groups that could react with the alkene group of SIS. ATR-FTIR spectra of samples show that absorption band of double bond at 1500–1600?cm?1 decreases after UV exposure. Increasing the concentration of benzoin (0.1–1?phr) and EGDMA (1–10?phr) leads to an increase in gel content and hardness, while swelling ratio decreases. After 5?min heating at 150?°C, about 20%wt of the unirradiated compound became insoluble, because heating of compound at 150?°C causes crosslinking reaction without any irradiation. 相似文献
80.
Marjan Mohammad Ali Zadeh Mansoor Keyanpour-Rad Touradj Ebadzadeh 《Ceramics International》2013,39(8):9079-9084
In this paper, the synthesis of continuous mullite (3Al2O3·2SiO2) nanofibres by combination of the sol–gel and electrospinning technique is reported. To find out the optimum viscosity of the electrospinning solution for obtaining the high quality mullite nanofibers, solutions containing different amounts of polyvinyl butyral (PVB, 0–8 wt%) and the precursor sol were prepared for the electrospinning process. The precursor sol was made by using proper amounts of aluminium isopropoxide (AIP), hydrated aluminium nitrate (AN) and tetraethylorthosilicate (TEOS). Crystal phase, microstructure and thermal decomposition behaviour of the electrospun mullite nanofibres were investigated by conventional methods of analysis. The optimal amount of PVB in the electrospinning polymeric solutions was found to be between 4 and 6 wt% and the mullite nanofibres obtained as such were pure, smooth and uniform with diameter sizes of 85–130 nm after calcination at 1200 °C. 相似文献