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101.
Bart De Spiegeleer Bram Baert Elien Vangheluwe Ilse Becue Jan De Smet Pieter Spanoghe Christophe Wille Paul Van der Meeren Guido Slegers 《Journal of solution chemistry》2007,36(7):835-843
Simulated intestinal fluids (SIFs) are described in the United States Pharmacopoeia (USP) and the International Pharmacopoeia
(IntPh) as recommended dissolution media for the characterization of solid drugs. This study was carried out to compare their
wettability properties. Six different model substrates were used as surrogates for solid drugs. These surrogate solid substrates
were characterized by the Lifshitz-van der Waals, electron donor and electron acceptor terms, which are the three components
of the total surface energy obtained by the van Oss model, which is based upon Young’s equation. Contact angles of the SIFs
on the surrogate solid-substrates were determined dynamically by image analysis up to five minutes after applying a drop of
the fluid on the solid surface. Observed time-dependent spreading behavior was accounted for by a linear extrapolation of
the experimental data to zero contact time to obtain the apparent equilibrium contact angle at zero time. Additionally, the
pH, osmolality and buffer capacity of the SIFs were experimentally determined. Although some differences in osmolality and
buffer capacity were observed, no statistically significant differences in the wetting properties of the three SIFs were detected.
This confirms recent findings that there are no observed differences in dissolution behavior among these simulated intestinal
fluids. Harmonization of these SIFs is thus recommended. 相似文献
102.
103.
In this paper we present some topics from the field of discrete mathematics which might be suitable for the high school curriculum.
These topics yield both easy to understand challenging problems and important applications of discrete mathematics. We choose
elements from number theory and various aspects of coding theory. Many examples and problems are included. 相似文献
104.
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107.
Bovee TF Helsdingen RJ Hamers AR Brouwer BA Nielen MW 《Analytical and bioanalytical chemistry》2011,401(3):873-882
Sensitive and robust bioassays for glucocorticoids are very useful for the pharmaceutical industry, environmental scientists
and veterinary control. Here, a recombinant yeast cell was constructed that expresses the human glucocorticoid receptor alpha
and a green fluorescent reporter protein in response to glucocorticoids. Both the receptor construct and the reporter construct
were stably integrated into the yeast genome. The correct and specific functioning of this yeast glucocorticoid bioassay was
studied by exposures to cortisol and other related compounds and critically compared to a GR-CALUX bioassay based on a human
bone cell. Although less sensitive, the new yeast glucocorticoid bioassay showed sensitivity towards all (gluco)corticoids
tested, with the following order in relative potencies: budesonide >> corticosterone > dexamethasone > cortisol = betamethasone
> prednisolone > aldosterone. Hormone representatives for other hormone nuclear receptors, like 17β-estradiol for the oestrogen
receptor, 5α-dihydrotestosterone for the androgen receptor and progesterone for the progesterone receptor, showed no clear
agonistic responses, whilst some polychlorinated biphenyls were clearly able to interfere with the GR activity. 相似文献
108.
We propose and analyze a new candidate Lyapunov function for relaxation towards general nonequilibrium steady states. The proposed functional is obtained from the large time asymptotics of time-symmetric fluctuations. For driven Markov jump or diffusion processes it measures an excess in dynamical activity rates. We present numerical evidence and we report on a rigorous argument for its monotonic time dependence close to the steady nonequilibrium or in general after a long enough time. This is in contrast with the behavior of approximate Lyapunov functions based on entropy production that when driven far from equilibrium often keep exhibiting temporal oscillations even close to stationarity. 相似文献
109.
Bram van Leer 《Journal of computational physics》2011,230(7):2378-2383
The Russian landmark paper “Application of the principle of minimizing the derivative to the construction of finite-difference schemes for computing discontinuous solutions of gas dynamics” by Vladimir P. Kolgan is discussed in a historical–technical perspective. The 1972 paper already featured a Godunov-type scheme for the Euler equations with second-order spatial accuracy, and a limiter to make it monotonicity-preserving. The work remained little known within and completely unknown outside the USSR, largely because of Kolgan’s untimely death in 1978. To honor Kolgan’s contribution to CFD, an English translation of his paper is included in this issue of the Journal of Computational Physics. Facts about Kolgan’s life are presented here, and an appraisal is given of the originality of his ideas. 相似文献
110.
To explain the signal behavior in 2D-TrueFISP imaging, a slice excitation profile should be considered that describes a variation of effective flip angles and magnetization phases after excitation. These parameters can be incorporated into steady-state equations to predict the final signal within a pixel. The use of steady-state equations assumes that excitation occurs instantaneously, although in reality this is a nonlinear process. In addition, often the flip angle variation within the slice excitation profile is solely considered when using steady-state equations, while TrueFISP is especially known for its sensitivity to phase variations. The purpose of this study was therefore to evaluate the precision of steady-state equations in calculating signal intensities in 2D TrueFISP imaging. To that end, steady-state slice profiles and corresponding signal intensities were calculated as function of flip angle, RF phase advance and pulse shape. More complex Bloch simulations were considered as a gold standard, which described every excitation within the sequence until steady state was reached. They were used to analyze two different methods based on steady-state equations. In addition, measurements on phantoms were done with corresponding imaging parameters. Although the Bloch simulations described the steady-state slice profile formation better than methods based on steady-state equations, the latter performed well in predicting the steady-state signal resulting from it. In certain cases the phase variation within the slice excitation profile did not even have to be taken into account. 相似文献