Low-pass filtering effects of viscous sublayer on high Schmidt number mass transfer close to a solid wall

Numerical simulation of high Schmidt number turbulent mass transfer at a solid wall is carried out. Particular attention is paid to the response of the concentration field to the wall-normal velocity fluctuation inside the viscous sublayer. Spatio-temporal correlation shows that the high Schmidt number concentration field becomes insensitive to the wall-normal velocity fluctuation. In addition, there exists a significant time lag in the response of the concentration field to the wall-normal velocity fluctuation. As a result, the instantaneous distribution of the local mass transfer rate is drastically changed. These facts explain why the analogy between the momentum and mass transfer does not hold close to the wall. Based on a one-dimensional advection–diffusion equation, we derive a transfer function connecting the wall-normal velocity and the concentration fluctuations. It is shown that the present model can reproduce the fundamental dynamical features of high Schmidt number concentration field.     

Optical characteristic variations in gamma ray irradiated polarization-maintaining optical fibers

Optical Review - Polarization-maintaining (PM) optical fibers are introduced in fiber optic communication systems and optical fiber sensors to improve their performances. It is known that...     

Bipancyclic properties of Cayley graphs generated by transpositions

Cycle is one of the most fundamental graph classes. For a given graph, it is interesting to find cycles of various lengths as subgraphs in the graph. The Cayley graph on the symmetric group has an important role for the study of Cayley graphs as interconnection networks. In this paper, we show that the Cayley graph generated by a transposition set is vertex-bipancyclic if and only if it is not the star graph. We also provide a necessary and sufficient condition for to be edge-bipancyclic.     

Vibrationally-assisted dissociative adsorption of oxygen on Ru(0 0 0 1)-p(2 × 1)-O

Supersonic molecular beam technique combined with high resolution X-ray photoelectron spectroscopy using synchrotron radiation was applied to the study of the dynamics of dissociative adsorption of oxygen on Ru(0 0 0 1) surface in high coverage region. The Ru(0 0 0 1) surface pre-covered with oxygen atoms of 0.5 monolayer, which corresponds to the p(2 × 1)-O structure, was dosed to oxygen molecules with translational energy of 0.5 eV. Oxygen uptake was compared between the cases with and without the beam source heated in order to verify the effects of internal energy of oxygen. We found drastic enhancement in initial sticking probability of oxygen when the beam source was heated to 1400 K. We concluded that the enhancement of sticking probability is mainly caused by molecular vibrational excitation, indicating that dissociation barrier is located in the exit channel on potential energy surface.     

Photoinduced transannular reaction of 1,3-dimethylcyclooctapyrimidine-2,4-diones

This article reports further elaboration of the authors' investigations on the acid-catalyzed photorearrangements undergone by derivatives of 1,3-dimethylcyclooctapyrimidine-2,4-dione. In this case the results are represented for compounds containing a simple methyl or fluorine substituent at different positions in the eight-membered ring. Upon photolysis in frozen benzene containing trifluoroacetic acid, the monomethylated compounds give varying yields of pentalenopyrimidinedione products that are not generated from the fluorinated compounds, which are either inert or undergo hydration accompanied by dehyrofluorination. Plausible mechanisms are advanced to account for the formation of the observed photoproduct species. The work represents an interesting extension and uncovered new aspects of the photorearrangement process.     

Chemiluminescence assay of N-acetyl-beta-D-glucosaminidase in urine using o-aminophthalylhydrazido-N-acetyl-beta-D-glucosaminide

The chemiluminescence assay of urinary N-acetyl-beta-D-glucosaminidase using o-aminophthalylhydrazido-N-acetyl-beta-D-glucosaminide as the substrate was examined. Under optimized conditions, a linear chemiluminescence response to the standard N-acetyl-beta-D-glucosaminidase (NAGase) of different concentrations was observed with a correlation coefficient of 0.999 over the range of 0.3 to 20 I.U./l. The present method was compared with the prevalent method using p-nitrophenyl-N-acetyl-beta-D-glucosaminide in the assay of 20 urine samples from healthy subjects, and the correlation coefficient of 0.891 was obtained.     

Specific-heat anomaly caused by ferroelectric nanoregions in Pb(Mg(1/3)Nb(2/3))O3 and Pb(Mg(1/3)Ta(2/3))O3 relaxors

The specific heat of typical relaxors, Pb(Mg(1/3)Nb(2/3))O3 (PMN) and Pb(Mg(1/3)Ta(2/3))O3 (PMT), was measured by adiabatic and relaxation methods between 2 and 420 K. A broad anomaly was found in the specific heat curve over the wide temperature range between 150 and 500 K for PMN, and between 50 and 400 K for PMT, which provides evidence for the formation of ferroelectric nanoregions (FNR) in the paraelectric matrix. The entropy of the anomaly was estimated as 3.3 J K(-1) mol(-1) and 2.9 J K(-1) mol(-1) for PMN and PMT, respectively, which implies an order-disorder-type mechanism for the formation of FNR.     

Photo-injected electron current in cryogenic liquids: a comparison of liquid Ar, Ne, He, N2, and H2 near their boiling points

The steady-state photoelectron currents J_L arising from a cathode irradiated by a deuterium lamp in liquid Ar, Ne, He, H₂ and N₂ near their boiling points were measured for external field strengths of up to 10⁵ V/cm. The current attenuation in the liquids compared to that available from the same light intensity into vacuum J_v, J (J_L/J_v), is in reverse order to the dielectric strength of the liquids. This may suggest that the facility of electron injection from the cathode plays an important role in determining the dielectric strength.