On the behavior of a slightly rarefied gas mixture over plane boundaries

Summary The behavior of a slightly rarefied gas mixture bounded by plane boundaries is investigated on the basis of the linearized Boltzmann equation ofB-G-K type for gas mixtures under the diffusive boundary condition. A useful result of the present analysis is that the macroscopic equations and the appropriate boundary conditions in terms of slip and jump are obtained together with the Knudsen-layer corrections near the boundaries. This system of equations makes possible the treatment at fluid dynamic level for various problems of gas mixtures with plane geometry which require kinetic theory consideration. As an application of this system, some basic flow problems of a slightly rarefied gas mixture, namely, Couette flow, thermal slip flow and diffusion slip flow between two plates are taken up. The total velocity distributions of these concrete problems are explicitly obtained for the first time, and their dependence on the properties and concentration of the component gases in the mixture are clarified in some detail.

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Zusammenfassung Das Verhalten einer verdünnten Gasmischung, bei kleiner aber nicht vernachlässigbarer Knudsen Zahl, zwischen zwei parallelen Platten wird analytisch untersucht. Die linearisierten Boltzmann Gleichungen desB-G-K Typs für Gasmischungen mit diffusiven Randbedingungen werden angewendet. Aus der vorliegenden Untersuchung resultieren brauchbare makroskopische Gleichungen mit den zugehörigen Randbedingungen, — mit Gleitgeschwindigkeit und Temperatursprung formuliert, — sowie die Korrekturen für die wandnahe Knudsen-Schicht. Verschiedene Strömungen von Gasmischungen, bei denen gas-kinetische Effekte eine Rolle spielen, entlang ebener Begrenzungen können mit den Gleichungssystemen auf strömungsmechanischem Niveau behandelt werden. Das System wird auf die Couette Strömung und die thermal-slip und diffusion-slip Strömungen angewendet. Zum ersten Mal werden die Geschwindigkeitsprofile dieser elementaren Strömungen explizit berechnet. Der Einfluß der Gaseigenschaften und Konzentrationen auf diese Profile werden weitgehend erklärt.

     

Synthesis and characterization of polyester dendrimers from acetoacetate and acrylate

New aliphatic polyester-type dendrimers were synthesized using a new AB2-type building block 3, prepared from benzyl acetoacetate and 2 equiv of tert-butyl acrylate by acetoacetic acid ester synthesis. The reiterative [deprotection by HCO2H, then EDCI/DMAP coupling] sequence using divergent growth method gave [G1]-4tBu-[G5]-64tBu dendrimers. 13C NMR relaxation time (T1) measurements on the carboxy carbons show that the extended chain conformations are predominant in CDCl3. [structure: see text]     

Self-assembled coordination cage derived from small-sized pyridinophane

The dithia[3.3]pyridinophane consisting of two pyridine rings has been found out to assume the syn-structure by the X-ray crystallography, meaning the two nitrogen atoms point in the same direction. From this cyclophane and cis-protected palladium(II), the self-assembled coordination molecular cage has been constructed.     

Temperature‐dependent location of a weakly segregated block copolymer in binary blends of block copolymers

The phase behaviors of binary blends of poly(styrene‐b‐butadiene) block copolymers were investigated by a small‐angle X‐ray scattering technique. The blends were composed of weakly segregated one in a random micellar phase and the other in a cylindrical phase with similar molecular weights and complementary volume fractions. Morphologies, domain spacings, and order–disorder transition temperatures of the blends indicated that the junctions of the constituent block copolymers share the interface at low temperatures. The domain spacing decreased as temperature increased in a blend with a small amount of the weakly segregated block copolymer. In the cases of the blends with a large amount of the weakly segregated constituent, domain spacing increased with increasing temperature. These results implied that some of the weakly segregated block copolymer moved from the interface to one microdomain at higher temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 470–476     

Heat/Mass transfer in a two-pass rotating rectangular duct with and without 70°-angled ribs

The present study investigates convective heat/mass transfer and flow characteristics inside a cooling passage of rotating gas-turbine blades. The rotating duct with and without rib turbulators are used. The ribs of 70° attack angle are attached on leading and trailing surfaces in a staggered arrangement. A naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. Additional numerical calculations are conducted to analyze the flow patterns in the cooling. The local heat/mass transfer and the flow pattern in the passage are changed significantly according to rib configurations, duct turning geometry and duct rotation speed. The results show that the duct rotation generates the heat transfer discrepancy between the leading and trailing walls due to the secondary flows induced by the Coriolis force. The heat/mass transfer on the ribbed duct shows 80% higher than the smooth duct because the ribs attached on the walls disturb the mainflow resulting in recirculation and secondary flows near the rib with the secondary flow generated by rotation. The overall heat transfer pattern on the leading and trailing walls for the first and second passes depend on the rotating speed and the turning geometry, but the local heat transfer trend is affected mainly by the rib arrangeements.     

Multicompartmental Microcylinders

Colorful columns : A simple yet scalable method that yields multicompartmental microcylinders with controllable internal architectures, aspect ratios, and controlled surface modification uses electrohydrodynamic co‐spinning followed by microsectioning. Compartments are discriminated by different colored dyes (see CLSM images; scale bars=10.0 μm).

     

Evaluation of energy transfer in perylene-cored anthracene dendrimers

Quantitative evaluation of F?rster-type fluorescence resonance energy transfer (FRET) was undertaken by statistical investigations on perylene-cored anthracene dendrimers.     

Medicinal carbon tablets for treatment of acetaminophen intoxication: adsorption characteristics of medicinal carbon powder and its tablets

Adsorption characteristics of medicinal carbon powder (JP 14) for acetaminophen were examined at 37 degrees C using conventional incubation in an attempt to obtain an effective oral dosage form. Hydroxypropyl cellulose (HPC) and maltitol (MT), being able to act as a binding agent, were tested as additives. Tablets of medicinal carbon were produced by the wet granulation method. The rate and extent of adsorption of the medicinal carbon powder were roughly similar in water, JP 14 1st fluid (pH 1.2) and JP 14 2nd fluid (pH 6.8). The relationship between concentrations of free and adsorbed acetaminophen indicated that the adsorption followed the Langmuir mode. The maximal adsorption of acetaminophen in water was 0.219 g per gram medicinal carbon powder, little influenced by the addition of MT, but slightly reduced by the addition of HPC. The tablet prepared using MT as a binding agent displayed a favorable hardness and adequate disintegration time. The tablet showed good adsorption potential for acetaminophen, though the adsorption rate and extent of the tablet were reduced to some extent as compared with powder.     

Characterization of the critical Sobolev space on the optimal singularity at the origin

In the present paper, we investigate the optimal singularity at the origin for the functions belonging to the critical Sobolev space , 1<p<∞. With this purpose, we shall show the weighted Gagliardo-Nirenberg type inequality:

(GN)