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71.
H. Uršič M. Hrovat J. Holc J. Tellier S. Drnovšek N. Guiblin B. Dkhil M. Kosec 《Journal of the European Ceramic Society》2010,30(10):2081-2092
Thick films with the nominal composition 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (0.65PMN–0.35PT) were produced by screen-printing and firing paste prepared from an organic vehicle and pre-reacted powder. The films were fired for 2 h at 950 °C on alumina (Al2O3), platinum (Pt), aluminium nitride (AlN) and 0.65PMN–0.35PT substrates. The films were then characterized using scanning electron microscopy, X-ray diffraction and dielectric constant measurements. The X-ray analysis did not detect the presence of any undesirable pyrochlore phase, and the differences in the phase compositions were determined with a Rietveld refinement. The variations of the cell parameters vs. the temperature for the monoclinic and tetragonal phases were calculated. It was demonstrated that under similar processing conditions the microstructures, phase compositions and dielectric properties strongly depended on the stress in the thick films due to the different temperature expansion coefficients of the thick films and the substrates. The 0.65PMN–0.35PT thick films under compressive stresses (for the case of the Al2O3 and Pt substrates) exhibited a tetragonal phase in addition to the monoclinic one. The films were sintered to a high density and with a coarse microstructure. These microstructures favour a high dielectric constant. In contrast, for the films under a tensile stress, like the films on AlN substrates, the films were sintered to a lower density and the microstructure consisted of smaller grains. The X-ray analysis showed mainly a monoclinic phase, while the tetragonal phase was not detected. These results indicate the importance of the stresses in 0.65PMN–0.35PT thick films and their influence on the structural and electrical characteristics of the films. 相似文献
72.
Riaz ur Rehman Bakhtawar Khan Tehmina Aziz Faiza Zareen Gul Syeda Nasreen Muhammad Zia 《IET nanobiotechnology / IET》2020,14(5):423
Due to unique physiochemical properties, nanoparticles (NPs) have acquired substantial attention in the field of research. However, threats of ecotoxicity and phytotoxicity have limited their biological applications. In this study in vivo experiments were performed to determine the effect of CuO (12.5, 25 and 50 mg/kg) and ZnO (200, 400 and 600 mg/kg) NPs on growth, and antioxidant activities of Brassica nigra. The results showed that CuO NPs did not affect the seed germination while presence of ZnO NPs in the soil generated an inhibitory effect. Both CuO and ZnO NPs positively influenced the growth of stem and other physiological parameters i.e. stem height increased (23%) at 50 mg/kg CuO while root length decreased (up to 44%) with an increase in the concentration of NPs. Phytochemical screening of apical, middle and basal leaves showed elevated phenolic and flavonoid contents in the range of 15.3–59 μg Gallic Acid Equivalent (GAE)/mg Dry Weight (DW) and 10–35 μg Querceitin Equivalent (QE)/mg DW, respectively, in NPs‐treated plants. Antioxidant activity was higher in CuO NPs‐treated plants as compared to ZnO and control plants. Results conclude that CuO and ZnO NPs at low concentrations can be exploited as nanofertilisers in agriculture fields.Inspec keywords: biochemistry, enzymes, renewable materials, crops, nanoparticles, soil, nanofabrication, zinc compounds, organic compounds, agricultural products, toxicology, nanobiotechnologyOther keywords: antioxidative response, ZnO nanoparticles exposure, soil conditions, unique physiochemical properties, germination, antioxidant activities, brassica nigra plant, antioxidant activity, CuO NP‐treated plants, control plants, ZnO NPs effect, mass 15.3 mug to 59.0 mug, mass 10.0 mug to 35.0 mug, CuO, ZnO 相似文献
73.
Saima Rehman Haq Nawaz Bhatti Zafar Iqbal & Umer Rashid 《International Journal of Food Science & Technology》2008,43(2):346-350
The essential oil components of different tea brands were investigated by gas chromatography. The oil yields of dried tea samples were ranged from 0.09% to 0.63%. Twenty-five compounds from Supreme and Lipton Yellow Label tea brands representing 98.0% and 88.0% of the Camellia sinensis oil were identified, respectively. The main ones were β-pinene (51.2%) and α-pinene (30.2%). Nineteen components from Tapal tea brand representing 76.7% of the C. sinensis oil were determined with high contents of muurol-5-en-4-a-ol (10.5%) and muurol-5-en-4-b-ol (31.3%). Fifteen components from Deer and Diana tea brands were identified, accounting for 83.3% and 78.2% of the oil containing α-cadinol and β-pinene. Seventeen components from non-branded teas were determined with high contents of muurol-5-en-4-a-ol and muurol-5-en-4-b-ol. Twenty-one compounds from non-branded Bangladeshi Shezan and Indian teas were also identified. All oils consisted of monoterpenic hydrocarbons, oxygenated monoterpenes and sesquiterpenes. 相似文献
74.
This paper introduces a neural network technique for the estimation of global solar radiation. There are 41 radiation data collection stations spread all over the kingdom of Saudi Arabia where the radiation data and sunshine duration information are being collected since 1971. The available data from 31 locations is used for training the neural networks and the data from the other 10 locations is used for testing. The testing data was not used in the modeling to give an indication of the performance of the system in unknown locations. Results indicate the viability of this approach for spatial modeling of solar radiation. 相似文献
75.
Sardar Muhammad Bilal Atta ur Rehman Khan Samee Ullah Khan Sajjad A. Madani Babar Nazir Mazliza Othman 《Wireless Personal Communications》2014,77(4):2497-2515
Over the last few years, vehicular ad hoc networks (VANETs) have gained popularity for their interesting applications. To make efficient routing decisions, VANET routing protocols require road traffic density information for which they use density estimation schemes. This paper presents a distributed mechanism for road vehicular density estimation that considers multiple road factors, such as road length and junctions. Extensive simulations are carried out to analyze the effectiveness of the proposed technique. Simulation results suggested that, the proposed technique is more accurate compared to the existing technique. Moreover, it facilitate VANET routing protocols to increase packet delivery ratio and reduce end-to-end delay. 相似文献
76.
Graphene: Large‐Area Si‐Doped Graphene: Controllable Synthesis and Enhanced Molecular Sensing (Adv. Mater. 45/2014) 下载免费PDF全文
77.
78.
The shape and scale parameters of a Weibull density distribution function are calculated for 10 locations in Saudi Arabia. The daily mean wind speed data from 1970 to mid-1990 are used for this purpose. It is found that the numerical values of the shape parameter vary between 1.7 and 2.7, whereas the value of the scale parameter is found to vary between 3 and 6. It is also concluded from this study that wind data are very well represented by the Weibull distribution function. 相似文献
79.
Textile composite double dome stamping simulation using a non-orthogonal constitutive model 总被引:1,自引:0,他引:1
Stamping is one of the most effective ways to form textile composites in industry for providing high-strength, low-weight and cost-effective products. This paper presents a fully continuum mechanics-based approach for stamping simulation of textile fiber reinforced composites by using finite element (FE) method. A previously developed non-orthogonal constitutive model is used to represent the anisotropic mechanical behavior of textile composites under large deformation during stamping. Simulation are performed on a balanced plain weave composite with 0°/90° and ±45° as initial yarn orientation over a benchmark double dome device. Simulation results show good agreement with experimental output in terms of a number of parameters selected for comparison. The effects of meshing and shear moduli obtained from bias extension test and picture frame test on forming simulation results are also investigated. 相似文献
80.
In this paper, several simple and efficient sign based normalized adaptive filters, which are computationally superior having multiplier free weight update loops are used for cancelation of noise in electrocardiographic (ECG) signals. The proposed implementation is suitable for applications such as biotelemetry, where large signal to noise ratios with less computational complexity are required. These schemes mostly employ simple addition, shift operations and achieve considerable speed up over the other least mean square (LMS) based realizations. Simulation studies shows that the proposed realization gives better performance compared to existing realizations in terms of signal to noise ratio and computational complexity. 相似文献