Reconsideration On The Role Of The Specific Heat Ratio In Arrhenius Law Applications

Arrhenius law implicates that only those molecules which possess the internal energy greater than the activation energy E-a can react. However, the internal energy will not be proportional to the gas temperature if the specific heat ratio gamma and the gas constant R vary during chemical reaction processes. The varying gamma may affect significantly the chemical reaction rate calculated with the Arrhenius law under the constant gamma assumption, which has been widely accepted in detonation and combustion simulations for many years. In this paper, the roles of variable gamma and R in Arrhenius law applications are reconsidered, and their effects on the chemical reaction rate are demonstrated by simulating one-dimensional C-J and two-dimensional cellular detonations. A new overall one-step detonation model with variable gamma and R is proposed to improve the Arrhenius law. Numerical experiments demonstrate that this improved Arrhenius law works well in predicting detonation phenomena with the numerical results being in good agreement with experimental data.

Sample-specific behavior in failure models of disordered medial

The concept ''sample-specific'' is suggested to describe the behavior of disordered media close to macroscopic failure. it is pointed out that the transition from universal scaling to sample-specific behavior may be a common phenomenon in failure models of disordered media. The dynamical evolution plays an important role in the transition.

Detection of constitutive homomeric associations of the integrins Mac-1 subunits by fluorescence resonance energy transfer in living cells

Integrins alpha(M)beta(2) plays important role on leukocytes, such as adhesion, migration, phagocytosis, and apoptosis. It was hypothesized that homomeric associations of integrin subunits provide a driving force for integrins activation, and simultaneously inducing the formation of integrins clusters. However, experimental reports on homomeric associations between integrin subunits are still controversial. Here, we proved the homomeric associations of the isolated Mac-1 subunits in living cells using three-channel fluorescence resonance energy transfer (FRET) microscopy and FRET spectra methods. We found that the extent of homomeric associations between beta(2) subunits is higher than alpha(M) subunits. Furthermore, FRET imaging indicated that the extent of homomeric associations of the Mac-1 subunits is higher along the plasma membrane than in the cytoplasm. Finally, we suggested that homomeric associations of the transmernbrane domains or/and cytoplasmic domains may provide the driving force for the formation of constitutive homomeric associations between alpha(M) or beta(2) subunits. (c) 2006 Elsevier Inc. All rights reserved.

Coma measurement by use of an alternating phase-shifting mask mark with a specific phase width

The correlation between the coma sensitivity of the alternating phase-shifting mask (Alt-PSM) mark and the mark's structure is studied based on the Hopkins theory of partially coherent imaging and positive resist optical lithography (PROLITH) simulation. It is found that an optimized Alt-PSM mark with its phase width being two-thirds its pitch has a higher sensitivity to coma than Alt-PSM marks with the same pitch and the different phase widths. The pitch of the Alt-PSM mark is also optimized by PROLITH simulation, and the structure of p - 1.92 lambda/NA and pw = 2p/3 proves to be with the highest sensitivity. The optimized Alt-PSM mark is used as a measurement mark to retrieve coma aberration from the projection optics in lithographic tools. In comparison with an ordinary Alt-PSM mark with its phase width being a half its pitch, the measurement accuracies of Z(7) and Z(14) apparently increase. (C) 2009 Optical Society of America