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271.
Zhiliang Xu Nan Chen Malgorzata M Kamocka Elliot D Rosen Mark Alber 《Journal of the Royal Society Interface》2008,5(24):705-722
A two-dimensional multiscale model is introduced for studying formation of a thrombus (clot) in a blood vessel. It involves components for modelling viscous, incompressible blood plasma; non-activated and activated platelets; blood cells; activating chemicals; fibrinogen; and vessel walls and their interactions. The macroscale dynamics of the blood flow is described by the continuum Navier-Stokes equations. The microscale interactions between the activated platelets, the platelets and fibrinogen and the platelets and vessel wall are described through an extended stochastic discrete cellular Potts model. The model is tested for robustness with respect to fluctuations of basic parameters. Simulation results demonstrate the development of an inhomogeneous internal structure of the thrombus, which is confirmed by the preliminary experimental data. We also make predictions about different stages in thrombus development, which can be tested experimentally and suggest specific experiments. Lastly, we demonstrate that the dependence of the thrombus size on the blood flow rate in simulations is close to the one observed experimentally. 相似文献
272.
The process of selective non-catalytic reduction of NO, SNCR, is important for limiting emissions of nitrogen oxides from coal-fired power plants. Such a process has been studied for many years, both in the laboratory and under practical conditions. This work was an attempt at elucidating some of the problems associated with the method when used under circulating fluidized bed (CFB) conditions and in particular, the formation of the N2O by-product. The NO + NH3 reaction has been studied in the laboratory, over quartz sand in a heated fixed bed flow reactor. In comparison with a combustion environment, the composition of the gas phase was drastically simplified and limited to NO and NH3, in nitrogen as the carrier gas, with O2 added in some experiments. The product gases were analyzed for NO, N2O and NH3. The effects the following parameters were studied: temperature inside the reactor between 850 and 1250 K, height of the sand bed, NH3/NO molar ratio over the range 0.54–2.0 and the addition of 1 or 2% of O2 in volume. Baseline tests with an empty reactor were also made. With no sand in the reactor, the results were both qualitatively and quantitatively different. The sand helped to increase the efficiency of NO reduction, particularly at lower temperatures, but N2O formation also appeared to be strongly enhanced, except at the highest temperatures. Higher molar NH3/NO ratios favored NO reduction and N2O production, both with and without sand. The reduction of NO did not appear to require the presence of O2, but the introduction of 1% or 2% of O2 gave some benefit. The results confirmed that under practical conditions more attention should be paid to the role of the bed solids in the SNCR process. 相似文献
273.
Isabelle Fabre-Francke Malgorzata Zagorska Philippe Hapiot Saïd Sadki 《Electrochimica acta》2008,53(22):6469-6476
A conjugated oligomer containing central bi-ethylenedioxythiophene (BEDOT) unit and two terminal anil-substituted carbazole units has been characterized by cyclic voltammetry and spectroelectrochemical methods (UV-vis-NIR and Raman). It shows two oxidation waves at −0.01 V and +0.24 V (versus Fc/Fc+), which can be ascribed to two successive oxidative dopings of the molecule. The molecule is transmissive sharp yellow when fully reduced, transmissive green upon oxidation up to the end of the first oxidative process, and dark blue upon full oxidation. UV-vis-NIR and Raman spectroelectrochemical investigations show that the colour changes within the potential of the first oxidation wave are associated with the oxidation of both carbazole and ethylenedioxythiophene subunits whereas the electrochromic effect in the potential range of the second oxidation wave involves predominantly the oxidation of the ethylenedioxythiophene subunits. 相似文献
274.
FT-Raman spectroscopy was used for the first time for in situ identification of aspalathin and quantification of the dihyrochalcones in dried, green rooibos (Aspalathus linearis). With the support of two-dimensional correlation spectroscopy, characteristic key bands of aspalathin, the main flavonoid and antioxidant occurring in rooibos, were localized and identified in the spectra obtained from various plant samples. Application of Raman mapping revealed the spatial distribution of this valuable dihydrochalcone within the intact dried leaves. Based on the spectral data and reference HPLC values, reliable multivariate calibration models were developed for quantification of aspalathin, nothofagin, and the combined dihydrochalcone contents of dried, green rooibos. 相似文献
275.
The Microstructure Degradation of the IN 713C Nickel-Based Superalloy After the Stress Rupture Tests
Hubert Matysiak Malgorzata Zagorska Alicja Balkowiec Boguslawa Adamczyk-Cieslak Rafal Cygan Jan Cwajna Jacek Nawrocki Krzysztof J. Kurzydłowski 《Journal of Materials Engineering and Performance》2014,23(9):3305-3313
The aim of the work was to examine the degradation phenomena taking place in the microstructure of the as-cast IN 713C superalloy after stress rupture tests, performed at T = 980 °C under a tensile stress of 150 MPa. A directional growth of γ′ phase (rafting) and decomposition of the NbC primary carbides accompanied by the precipitation of M23C6 secondary carbides rich in chromium and of γ′ phase were observed. It was also indicated that the decomposition of the NbC primary carbides may be accompanied by the precipitation of M3B2 borides rich in Mo. 相似文献
276.
The stability of plant oils is related to the level of polyunsaturated fatty acids and the presence of native antioxidants--especially tocopherols. During storage, lipids or the fat products undergo oxidation and tocopherol dimers and trimers are formed. These compounds possess reducing and antioxidant properties and participate in oxidation clearly inhibiting this process. In the present study, the correlation between levels of peroxides formed during autoxidation of methyl linoleate and simultaneous decomposition of tocopherols was examined. The peroxide value was investigated. Quantities of decomposed tocopherols and formation of their dimers were determined by high-performance liquid chromatography (HPLC). Mass spectrum analysis confirmed thatthe analysed compounds were dimes. Dimerisation of gamma-T begins at the smaller quantity of the methyl linoleate peroxides than dimerisation of delta-T. At the beginning of methyl linoleate autoxidation dimerisation of gamma-T in relation to its loss was smaller. The quantity of gamma-T dimers with ether bonds in total dimers pointed to faster binding of phenoxy radicals than transformation into the phenyl ones. delta-T dimers with phenyl bonds constitute about 65% of the total. The quantity of peroxides in methyl linoleate, necessary for quantitative and qualitative changes of homologous tocopherols, decreased from delta-T to alpha-T. 相似文献
277.
278.
279.
Kowalska MA Kasprzak HT Iskander DR Danielewska M Mas D 《IEEE transactions on bio-medical engineering》2011,58(3):674-680
Our aim was to ascertain whether the ultrasonic measurement of longitudinal corneal apex displacements carried out in a proper headrest is a credible method of ocular pulse (OP) detection. To distinguish between longitudinal movements of the eye globe treated as a rigid body and ocular surface expansion caused by the variations of the eye-globe volume, two ultrasound distance sensors were applied to noninvasively measure displacements of cornea and sclera. The same sensors were used to examine the influence of the anterio-posterior movements of a fixed head on the registration of corneal apex pulsation. In both experiments, ECG signals were synchronically recorded. Time, spectral, and coherence analyses obtained for four healthy subjects showed that the ocular surface expansion due to pulsatile ocular blood flow (POBF) is the main component of longitudinal corneal displacement. Ocular surface pulsation is always affected by the head movement. However, there exist some unique properties of signals, which help to distinguish between head and eye movements. A rigid headrest and a bite bar are required to stabilize the head during OP measurement. Ultrasonic technique enables noninvasive and accurate in vivo measurement of corneal pulsation, which could be of interest for indirectly estimating intraocular pressure propagation and POBF component. 相似文献
280.
This paper characterizes the behaviour of multi-terminal nets in a circuit to provide an accurate estimation of interconnect net-degree distribution. Based on Rent's rule, we derived a new net-degree distribution model, called the weighted exponential model. Numerical evaluations show that weighted exponential model is more accurate than any other currently available net-degree distribution models. It generates from 18% to 87% smaller average absolute errors in the prediction of the total number of nets and average net degree. Moreover, it was observed that the internal fraction factor f, that represents the ratio of the number of new internal nets to the total number of new nets, similarly to Rent's rule, exhibits Regions II and III. With a refined value of f, our model can provide even more accurate estimation of net-degree distribution.
A method to generate floorplanning benchmarks using weighted exponential model is presented. Thanks to the accuracy of new model and the introduction of a block-degree distribution, the significantly improved benchmark generator, BGen, outperforms a prototype tool we have previously developed using Zarkesh-Ha et al's model. 相似文献