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991.
We extend the well-known Artstein-Sontag theorem by introducing the concept of control Lyapunov function for the notion of
nonuniform in time global asymptotic stability in probability of stochastic differential system, when both the drift and diffusion
terms are affine in the control. The main results of our work enable us to derive the necessary and sufficient conditions
for feedback stabilization for affine in the control systems. 相似文献
992.
Fatemeh Rostami Mahdi Shahrokhi Md Azlin Md Said Rozi Abdullah Syafalni 《Applied Mathematical Modelling》2011
Inlets should be designed to dissipate the kinetic energy or velocity head of the mixed liquor and to prevent short-circuiting, mitigate the effects of density currents, and minimize blanket disturbances. Flow in primary settling tank is simulated by means of computational fluid dynamics. The fluid is assumed incompressible and non-buoyant. A two-dimensional computational and one phase fluid dynamics model was built to simulate the flow properties in the settling tank including the velocity profiles, the flow separation area and kinetic energy. In this study, the RNG turbulent model was solved with the Navier–Stokes equations. In order to evaluate hydraulic influences on the velocity profile, separation length and kinetic energy, three different of opening positions and two and three aperture in inlets were simulated. The flow model uses to apply a fixed-grid of cells that are all rectangular faces; the fluid moves through the grid and free surfaces are tracked with the volume-of-fluid (VOF) technique. Effects of numbers and locations of inlet apertures on the flow field are presented and the results show the positions of inlet apertures are affected on the flow pattern in the settling basin and increasing the numbers of slots can reduce kinetic energy in the inlet zone and produce uniform flow. 相似文献
993.
994.
Arlinghaus LR Li X Rahman AR Welch EB Xu L Gore JC Yankeelov TE 《Magnetic resonance imaging》2011,29(5):630-638
MRI techniques have been developed that can noninvasively probe the apparent diffusion coefficient (ADC) of water via diffusion-weighted MRI (DW-MRI). These methods have found much application in cancer where it is often found that the ADC within tumors is inversely correlated with tumor cell density, so that an increase in ADC in response to therapy can be interpreted as an imaging biomarker of positive treatment response. Dynamic contrast enhanced MRI (DCE-MRI) methods have also been developed and can noninvasively report on the extravascular extracellular volume fraction of tissues (denoted by ve). By conventional reasoning, the ADC should therefore also be directly proportional to ve. Here we report measurements of both ADC and ve obtained from breast cancer patients at both 1.5 and 3.0 T. The 1.5-T data were acquired as part of normal standard of care, while the 3.0-T data were obtained from a dedicated research protocol. We found no statistically significant correlation between ADC and ve for the 1.5- or 3.0-T patient sets on either a voxel-by-voxel or a region-of-interest (ROI) basis. These data, combined with similar results from other disease sites in the literature, may indicate that the conventional interpretation of either ADC, ve or their relationship is not sufficient to explain experimental findings. 相似文献
995.
Arshad Khan Khalid Rahman Myung-Taek Hyun Dong-Soo Kim Kyung-Hyun Choi 《Applied Physics A: Materials Science & Processing》2011,104(4):1113-1120
In this paper, multi-nozzle electrohydrodynamic (EHD) inkjet printing of a colloidal solution containing silver nanoparticles
in a fully controlled fashion is reported. For minimizing interaction, i.e. cross-talk, between neighboring jets, the distance
between the nozzles was optimized numerically by investigating the magnitude of the electric field strength around the tip
of each nozzle. A multi-nozzle EHD inkjet printing head consisting of three nozzles was fabricated and successfully tested
by simultaneously printing electrically conductive lines of a colloidal solution containing silver nanoparticles onto a glass
substrate. The printed results show electrical resistivity of 5.05×10−8 Ω m, which is almost three times larger than that of bulk silver. These conductive microtracks demonstrate the feasibility
of the multi-nozzle EHD inkjet printing process for industrial fabrication of microelectronic devices. 相似文献
996.
The diffusion of two-dimensional adatom-islands (up to 100 atoms) on Cu(111) has been studied, using the self-learning kinetic Monte Carlo method (Trushin et?al 2005 Phys. Rev. B 72 115401). A variety of multiple-?and single-atom processes are revealed in the simulations, and the size dependences of the diffusion coefficients and effective diffusion barriers are calculated for each. From the tabulated frequencies of events found in the simulation, we show a crossover from diffusion due to the collective motion of the island to a regime in which the island diffuses through periphery-dominated mass transport. This crossover occurs for island sizes between 13 and 19 atoms. For islands containing 19-100 atoms the scaling exponent is 1.5, which is in good agreement with previous work. The diffusion of islands containing 2-13 atoms can be explained primarily on the basis of a linear increase of the barrier for the collective motion with the size of the island. 相似文献
997.
Density functional theory (DFT) calculations have been carried out on the possible degradation/demethylation mechanism of methyl mercury (CH(3)Hg(+)) complexes with free cysteine and seleonocysteine. The binding of CH(3)Hg(+) ions with one (seleno)amino acid is thermodynamically favorable. However, the binding with another acid molecule is a highly unfavorable process. The CH(3)Hg-(seleno)cysteinate then degrades to bis(methylmercuric)sulphide (selenide for the Se-containing complex) which in turn forms dimethyl mercury and HgS/HgSe, the latter being precipitated out as nanoparticles. The dimethyl mercury interacts with water molecules and regenerates the CH(3)HgOH precursor. The calculated free energies of formation confirm the thermodynamic feasibility of every intermediate step of the degradation cycle and fully support earlier experimental results. In completing the cycle, one unit of mercury precipitates out from two units of sources, and thereby Se antagonizes the Hg toxicity. The degradation of CH(3)Hg-L-cysteinate is thermodynamically more favorable than the formation of CH(3)Hg-L-cysteinate. The preferred degradation of the CH(3)Hg-L-cysteinate suggests that another mechanism for CH(3)Hg to cross the blood-brain barrier should exist. 相似文献
998.
Kim JS Cho KJ Tran TH Nurunnabi M Moon TH Hong SM Lee YK 《Journal of colloid and interface science》2011,353(2):363-371
Luminescent near-infrared (NIR) CdTe/CdSe QDs were synthesized and encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanospheres to prepare stable and biocompatible QDs-loaded nanospheres for in vivo imaging. QDs were encapsulated with PLGA nanospheres by a solid dispersion method and optimized to have high fluorescence intensity for in vivo imaging detection. The resultant QDs-loaded PLGA nanospheres were characterized by various analytical techniques such as UV-Vis measurement, dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM). Finally, we evaluated toxicity and body distribution of QDs loaded in PLGA nanospheres in vitro and in vivo, respectively. From the results, the QDs loaded in PLGA nanospheres were spherical and showed a diameter range of 135.0-162.3 nm in size. The QD nanospheres increased their stability against photooxidation and photobleaching, which have the high potential for applications in biomedical imaging. We have also attained non-invasive in vivo imaging with light photons, representing an intriguing avenue for obtaining biological information by the use of NIR light. 相似文献
999.
Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties 总被引:1,自引:0,他引:1
Rahman MM Chehimi MM Fessi H Elaissari A 《Journal of colloid and interface science》2011,361(2):556-564
Three new dimeric cholesterol-based compounds of A(LS)(2) type, where A stands for aromatic component, S steroid moiety, and L a linker connecting the two units, have been designed and prepared. Gelation test in 30 solvents demonstrated that the compounds can gel some of the solvents and form 37 gels, of which 16 form spontaneously at room temperature (~25 °C). These gels possess smart thixotropic properties as revealed by rheological studies. FTIR and (1)H NMR measurements revealed that hydrogen bonding is an important driving force for the formation of the gel networks. XRD analysis demonstrated that unlike commonly found layered structures adopted by dimeric cholesterol-based low-molecular mass gelators (LMMGs), one of the gelators created in this study adopts a hexagonal packing structure in its benzene gel. 相似文献
1000.
Ramachandran H Iqbal NM Sipaut CS Abdullah AA 《Applied biochemistry and biotechnology》2011,164(6):867-877
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) [P(3HB-co-3HV-co-4HB)] terpolymer was produced using Cupriavidus sp. USMAA2-4 via one-step cultivation process through combination of various carbon sources such as 1,4-butanediol or γ-butyrolactone
with either 1-pentanol, valeric acid, or 1-propanol. Oleic acid was added to increase the biomass production. The composition
of 3HV and 4HB monomers were greatly affected by the concentration of 1,4-butanediol and 1-pentanol. Terpolymers with 3HV
and 4HB molar fractions ranging from 2 to 41 mol.% and 5 to 31 mol.%, respectively, were produced by varying the concentration
of carbon precursors. The thermal and mechanical properties of the terpolymers containing different proportions of the constituent
monomers were characterized using gel permeation chromatography (GPC), DSC, and tensile machine. GPC analysis showed that
the molecular weights (M
w) of the terpolymer produced were within the range of 346 to 1,710 kDa. The monomer compositions of 3HV and 4HB were also
found to have great influences on the thermal and mechanical properties of the terpolymer P(3HB-co-3HV-co-4HB) produced. 相似文献