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101.
Carbon-black–epoxy composite films were prepared by cathodic electro-deposition of a dispersion containing carbon black and epoxy resins. The films, after baking at elevated temperature, show a semi-conducting behavior. Using DC conductivity measurements it was possible to determine the glass transition temperature of the samples, the conductivities of which lie in the sensitivity range of the instrument. Conductive samples show a positive temperature coefficient both below and above Tg. Based on the electrical impedance data extracted from the electrochemical impedance spectra, the exponents x and y were determined for the frequency dependence of the complex conductivity and complex dielectric constant as 0.8 and 0.2, respectively. These values are in good agreement with the classical values of x = 0.72 and y = 0.28. It was also found that these exponents are the same for all the CCB contents studied. 相似文献
102.
Qualitative and quantitative evaluation of heart sound reduction from lung sound recordings 总被引:1,自引:0,他引:1
Gnitecki J Hossain I Pasterkamp H Moussavi Z 《IEEE transactions on bio-medical engineering》2005,52(10):1788-1792
Recursive least squares (RLS) adaptive noise cancellation (ANC) and wavelet transform (WT) ANC have been applied and compared for heart sound (HS) reduction from lung sounds (LS) recordings. Novel processes for quantitative and qualitative evaluation of any method for HS reduction from LS have also been proposed. 相似文献
103.
The creep-rupture behaviour of a Type DIN 1.4970 austenitic stainless steel has been investigated at 973 K (700°C) in a high vacuum for three conditions of thermomechanical treatment and a wide range of applied stresses using foil specimens of 105 μm thickness. After solution-annealing at 1373 K (1100°C) for all specimens, the three treatments were: — condition 1: 13% cold-worked — condition2: aged for 24 h at 1073 K (800°C) and 13% cold-worked — condition 3: (“Standard condition”): 13% cold-worked and aged for 24 h at 1073 K (800°C).The rupture lives and the minimum creep rates were found to be highly dependent on the applied stresses. The treatment of condition 1 material yielded a product as strong as the “standard” condition 3, while the condition 2 material was less creep resistant.Structural changes as well as fractography were followed using metallographic, transmission and scanning electron microscope techniques. Transgranular ductile fracture was clearly observed in all three conditions. TEM investigations showed that dispersive TiC precipitates were present in the matrix of condition 3 material before creep testing, contrary to condition 1 and 2 material. In condition 1, the TiC dispersion was already found after short creep times, while no dispersive TiC precipitates were found in condition 2 material in any test condition. 相似文献
104.
Masoud Hashempour Zahra Mashreghian Arani Fabrizio Lombardi 《Journal of Electronic Testing》2009,25(1):25-37
In self-assembly, individual components (commonly referred to as tiles) have sufficient infor mation to build templates for
structures such as lat tices for two-dimensional scaffolds. Tile sets that can heal (fully or partially) an erroneous DNA
assembly have been proposed. Healing requires growth to be restarted such that erroneous tiles can be removed and the correct
tiles can bind to the aggregate. Punctures have been proposed for this purpose; in this paper, a puncture is intentionally
induced in the self-assembly to restart the growth process. The goal of this paper is to characterize an intentionally induced
puncture (and its relevant properties) on an erroneous tile site in the grown crystal as part of a healing process. This allows
to propagate any newly generated error away from the source of growth (i.e. the seed tile), such that self-assembly can continue
along specific directions. Different types of puncture are considered with respect to healing and related features, such as
growth direction, error and aggregate types. Punctures are analyzed using a new characterization and metric; different tile
sets are investigated in detail for healing of a DNA self-assembly.
相似文献
Fabrizio LombardiEmail: |
105.
Amorphous silica gel modified carbon paste electrode (CPE) offers substantial improvements in voltammetric sensitivity and selectivity towards determination of dopamine (DA). Cyclic voltammetry of Fe(CN)63−/4− as a negatively charged probe revealed that the surface of the silica gel modified carbon paste electrode had a high density of negative charge at pH 8.0. Therefore, the modified electrode adsorbed DA (pKa = 8.9) and enhanced its voltammetric response while repulsed ascorbic acid (AA) (pKa = 4.2) and uric acid (UA) (pKa = 5.4) and inhibited their interfering effects. The influence of various experimental parameters including percent of silica gel in the CPE, pH of solution, and accumulation time and potentials, on the voltammetric response of DA was investigated. At the optimum conditions, the analytical curve was linear for dopamine concentrations from 2.0 × 10−7 to 1.0 × 10−6 mol L−1 and 2.0 × 10−6 to 1.5 × 10−4 mol L−1 with a detection limit (3σ) of 4.8 × 10−8 mol L−1. The prepared electrode was used for determination of DA spiked into DA injection and human serum samples, and very good recovery results were obtained over a wide concentration range of DA. 相似文献
106.
Yousef Kazemzadeh Behnam Dehdari Zahra Etemadan Masoud Riazi Mohammad Sharifi 《石油科学(英文版)》2019,(3):578-590
Nanofluids because of their surface characteristics improve the oil production from reservoirs by enabling different enhanced recovery mechanisms such as wettability alteration, interfacial tension (IFT) reduction, oil viscosity reduction, formation and stabilization of colloidal systems and the decrease in the asphaltene precipitation. To the best of the authors’ knowledge, the synthesis of a new nanocomposite has been studied in this paper for the first time. It consists of nanoparticles of both SiO2 and Fe3O4. Each nanoparticle has its individual surface property and has its distinct effect on the oil production of reservoirs. According to the previous studies, Fe3O4 has been used in the prevention or reduction of asphaltene precipitation and SiO2 has been considered for wettability alteration and/or reducing IFTs in enhanced oil recovery. According to the experimental results, the novel synthesized nanoparticles have increased the oil recovery by the synergistic effects of the formed particles markedly by activating the various mechanisms relative to the use of each of the nanoparticles in the micromodel individually. According to the results obtained for the use of this nanocomposite, understanding reservoir conditions plays an important role in the ultimate goal of enhancing oil recovery and the formation of stable emulsions plays an important role in oil recovery using this method. 相似文献
107.
The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties compared to polyacrylamide, was confirmed by several analyses including HNMR, elemental analysis, FTIR, SEM, TGA, and DSC. Simulating HTHS oil reservoir condition under high salinity, temperature, and shear rate, the rheological studies suggested unlike traditional EOR agents such as polyacrylamide, the viscosity of the copolymer, and terpolymer aqueous solutions showed a considerable increase after a critical polymer concentration and less reduction with the salt increment at both ambient and elevated temperatures. Furthermore, the swelling ratio of the insoluble terpolymers measured versus the time and temperature in salt water increased with the maleic anhydride mole fraction, decreased with the salt concentration, and showed a maximum value at around 57 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47753. 相似文献
108.
109.
Merikhi Behnaz Mirjalili Seyed Mohammad Zoghi Milad Mirjalili Seyedeh Zahra Mirjalili Seyedali 《Photonic Network Communications》2019,38(1):167-176
Photonic Network Communications - This paper proposes an effective method for shaping the radiation pattern intensity of photonic crystal (PhC) light-emitting diode (LED). In this method, the... 相似文献
110.
Mahsa Varmazyari Yasin Khani Farzad Bahadoran Zahra Shariatinia Saeed Soltanali 《International Journal of Hydrogen Energy》2021,46(1):565-580
Cu(BDC) metal–organic framework (MOF) was used as a support for the copper (Cu) catalyst applied in the methanol steam reforming (MSR) process at low temperatures (130–250 °C) with a feed WHSV = 9.2 h?1 within the monolithic reactor. Also, the effects of diverse promoters were examined on the catalytic activities of the Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts. Results showed that the Ce/Sm–Cu(BDC) supports exhibited highest activities, lowest reduction temperatures and largest specific surface areas, which caused highest distributions of the active copper metal nanoparticles on the supports. The reactor tests displayed that the activities of Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts followed the order X = Ce > Sm > Y > La > Pr > Cu(BDC) > Zn > Gd. The highest activities of Ce and Sm containing catalysts were attributed to the presence of CeO2 and Sm2O3 caused the oxygen vacancies on the catalyst surface which had positive effects on the methanol reforming process. The time-on-stream stability tests showed the highest resistance of the Cu/Ce–Cu(BDC) catalyst to the carbon formation during 32 h. Consequently, the Cu/Ce–Cu(BDC) with the highest stability, methanol conversion and carbon monoxide selectivity could be used in practical industrial applications. 相似文献