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排序方式: 共有209条查询结果,搜索用时 31 毫秒
61.
Cover Picture: Viologen‐Templated Arrays of Cucurbit[7]uril‐Modified Iron‐Oxide Nanoparticles (Chem. Eur. J. 12/2015)
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62.
Effect of particle size distribution on magnetic behavior of nanoparticles with uniaxial anisotropy
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S Rizwan Ali Farah Naz Humaira Akber M Naeem S Imran Ali S Abdul Basit M Sarim Sadaf Qaseem 《中国物理 B》2018,(9)
The effect of particle size distribution on the field and temperature dependence of the hysteresis loop features like coercivity(H_C), remanence(M_R), and blocking temperature(T_B) is simulated for an ensemble of single domain ferromagnetic nanoparticles with uniaxial anisotropy. Our simulations are based on the two-state model for T T_B and the metropolis Monte-Carlo method for T T_B. It is found that the increase in the grain size significantly enhances H_C and T_B. The presence of interparticle exchange interaction in the system suppresses H_C but causes MRto significantly increase.Our results show that the parameters associated with the particle size distribution(D_(d,δ)) such as the mean particle size d and standard-deviation δ play key roles in the magnetic behavior of the system. 相似文献
63.
Farah Abdallah Serge Nicaise Julie Valein Ali Wehbe 《Comptes Rendus Mathematique》2012,350(1-2):29-34
In this Note, we consider the approximation of two coupled wave equations with internal damping. Our goal is to damp the spurious high frequency modes by introducing numerical viscosity terms in the approximation scheme. With these viscosity terms, we show the exponential or polynomial decay of the discrete scheme when the continuous problem has such a decay (since the spectrum of the spatial operator associated with the undamped system satisfies the generalized gap condition). 相似文献
64.
Stress relaxation tests have been carried out on a blue, pipe grade PE 80 medium density polyethylene (BP Chemicals), to provide thermo-viscoelastic rheology for use in calculating thermal stresses in pipe production. Stresses up to 4 MPa were used, with strains up to about 2%, in tests at temperatures from 23° to 90°C. Within this range a linear viscoelastic model was applicable, provided the initial ramp strain rate was less than 7×10–5 s–1. The stress relaxation data was fitted directly by a model incorporating an elastic response to volumetric strains, and a generalised linear solid model, consisting of two Maxwell elements and a purely elastic element in parallel, for deviatoric strains. Arrhenius type temperature dependence of relaxation times and shear moduli is found, and within experimental accuracy the temperature dependence of all these model parameters is the same. As a consequence, and provided that the duration of the strain ramp is sufficiently short relative to relaxation times, the model leads to time-temperature superposition of the relaxation moduli, using the same shift factor on both the response magnitude and time axes. 相似文献
65.
Kevin Carlson Enoch Cheung Ilijas Farah Alexander Gerhardt-Bourke Bradd Hart Leanne Mezuman Nigel Sequeira Alexander Sherman 《Archive for Mathematical Logic》2014,53(1-2):157-169
We prove that the classes of UHF algebras and AF algebras, while not axiomatizable, can be characterized as those C*-algebras that omit certain types in the logic of metric structures. 相似文献
66.
Zhanyou Chi Farah Elloy Yuxiao Xie Yucai Hu Shulin Chen 《Applied biochemistry and biotechnology》2014,172(1):447-457
Using microalgae to capture CO2 from flue gas is an ideal way to reduce CO2 emission, but this is challenged by the high cost of carbon capture and transportation. To address this problem, a bicarbonate-based integrated carbon capture and algae production system (BICCAPS) has been proposed, in which bicarbonate is used for algae culture, and the regenerated carbonate from this process can be used to capture more CO2. High-concentration bicarbonate is obligate for the BICCAPS. Thus, different strains of microalgae and cyanobacteria were tested in this study for their capability to grow in high-concentration NaHCO3. The highest NaHCO3 concentrations they are tolerant to were determined as 0.30 M for Synechocystis sp. PCC6803, 0.60 M for Cyanothece sp., 0.10 M for Chlorella sorokiniana, 0.60 M for Dunaliella salina, and 0.30 M for Dunaliella viridis and Dunaliella primolecta. In further study, biomass production from culture of D. primolecta in an Erlenmeyer flask with either 0.30 M NaHCO3 or 2 % CO2 bubbling was compared, and no significant difference was detected. This indicates BICCAPS can reach the same biomass productivity as regular CO2 bubbling culture, and it is promising for future application. 相似文献
67.
68.
Farah Alvi Rakesh K. Joshi Qiang Huang Ashok Kumar 《Journal of nanoparticle research》2011,13(6):2451-2459
Kinetic Monte Carlo (KMC)-based stochastic model is used to understand the growth of zinc oxide nanowires from aqueous solution
containing chemical precursors and capping agent. Through a hydrothermal growth mechanism, the average diameter of zinc oxide
wires obtained is around 300 nm, whereas the length is order of several micrometers. Our Monte Carlo algorithm is based on
the continuous-time Monte Carlo algorithm of Bortz, Kalos and Lebowitz (BKL) methodology. Both reactions and diffusion mechanisms
assigning stochastic probabilities have been simulated. In algorithm, the ZnO atoms were treated as individual particles which
diffuse in solution substrate and interact with other type of atoms. Once attached with growing nanowires, the diffusion rate
of ZnO atom is considerably reduced. Since in a KMC algorithm each atom can be represented individually therefore, internal
noise is automatically incorporated. 相似文献
69.
Dr. Farah Kawtharani Dr. Svetlana Mintova Dr. Richard Retoux Prof. Mehran Mostafavi Dr. Guy Buntinx Dr. Vincent De Waele 《Chemphyschem》2020,21(24):2634-2643
Silver cations were introduced in nanosized BEA-type zeolite containing organic template by ion-exchange followed by chemical reduction towards preparation of photoactive materials (Ag0-BEA). The stabilization of highly dispersed Ag0 nanoparticles with a size of 1–2 nm in the BEA zeolite was revealed. The transient optical response of the Ag-BEA samples upon photoexcitation at 400 nm was studied by femtosecond absorption. The photodynamic of the hot electrons was found to depend on the sample preparation. The lifetime of the hot electrons in the Ag−BEA samples containing small Ag nanoparticles (1–2 nm) is significantly shortened in comparison to bear Ag nanoparticles with a size of 10 nm. While for the larger Ag nanoparticles, the energy absorbed in the conduction band is decaying by electron-phonon coupling into the metal lattice, the high surface-to-volume ratio of the small Ag nanoparticles favors the dissipation of the energy of the hot electrons from the metal nanoparticles (Ag0) towards the zeolitic micro-environment. This finding is encouraging for further applications of Ag-containing zeolites in photocatalysis and plasmonic chemistry. 相似文献
70.
RUB MalikAbdul ASIRIAbdullah M KUMAR Dileep AZUM Naved KHAN Farah 《物理化学学报》2014,30(4):699-707
The mixed micellization behavior of an amphiphilic antidepressant drug amitriptyline hydrochloride(AMT)in the presence of the conventional anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate(AOT)was studied at five different temperatures and compositions by the conductometric technique.The critical micelle concentration(cmc)and critical micelle concentration at the ideal state(cmcid)values show mixed micelle formation between the components(i.e.,drug and AOT).The micellar mole fractions of the AOT(X1)values calculated using the Rubingh,Motomura,and Rodenas models show a higher contribution of AOT in the mixed micelles.The interaction parameter(β)is negative at all temperatures and the compositions show attractive interactions between the components.The activity coefficients(f1and f2)calculated using the different proposed models are always less than unity indicating non-ideality in the systems.TheΔGmΘ values were found to be negative for all the binary mixed systems.However,ΔHmΘ values for the pure drug as well as the drug-AOT mixed systems are negative at lower temperatures(293.15-303.15 K)and positive at higher temperatures(308.15 K and above).TheΔSmΘ values are positive at all temperatures but their magnitude was higher at T=308.15 K and above.The excess free energy of mixing(ΔGex)determined using the different proposed models also explains the stability of the mixed micelles compared to the pure drug(AMT)and surfactant micelles. 相似文献