Anisotropic Thermal Expansion of β-Ca2SiO4 Monoclinic Crystal

Crystals of β-Ca₂SiO₄ (space group P 12₁/ n 1) were examined by high-temperature powder X-ray diffractometry to determine the change in unit-cell dimensions with temperature up to 645°C. The temperature dependence of the principal expansion coefficients (α_i) found from the matrix algebra analysis was as follows: α₁= 20.492 × 10⁻⁶+ 16.490 × 10⁻⁹ ( T - 25)°C⁻¹, α₂= 7.494 × 10⁻⁶+ 5.168 × 10⁻⁹( T - 25)°C⁻¹, α₃=−0.842 × 10⁻⁶− 1.497 × 10⁻⁹( T - 25)°C⁻¹. The expansion coefficient α₁, nearly along [302] was approximately 3 times α₂ along the b -axis. Very small contraction (α₃) occurred nearly along [     01]. The volume changes upon martensitic transformations of β↔α_L' were very small, and the strain accommodation would be almost complete. This is consistent with the thermoelasticity.     

Evaluation of mixing profiles for a new micromixer design strategy

The relationship between mixing history and reaction performance in microreactors using computational fluid dynamics (CFD) simulations is identified. In the idealized, simplified mixing model, mixing proceeds linearly and only the mixing time determined the reaction performance. However, in the case of realistic models where mixing proceeds unequally, the partial rapid progression of mixing, more than the mixing time, significantly impacts the reaction. The use of the fluid segment size distribution to capture this effect is proposed. The effective Damköhler number derived from the fluid segment size distribution predicted the reaction yield well. To demonstrate the utility of the mixing profile design strategy, we fabricated a novel micromixer with multiple partial rapid mixing zones. This micromixer achieved excellent results both in a CFD simulation and an experiment. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1154–1161, 2016     

Planar textures in superfluid 3He-A

Making use of the Ginzburg-Landau free energy, singularities such as disgyrations and vortex lines and stable textures in the planar (or two-dimensional) texture are studied. Here both % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaaieqaceWFSbGbaK% aaaaa!3883!\[{\hat l}\] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaaieqaceWFKbGbaK% aaaaa!387B!\[{\hat d}\] vectors, characterizing the texture in ³He-A, are assumed parallel to each other and lie always in a plane. The dynamics of disgyrations is also considered.Work supported by the National Science Foundation under grant number DMR76-21032.     

Optical properties of the anisotropic C3A

This study deals with optical properties of the anisotropic C₃A-form. With an increase in SiO₂ or Fe₂O₃ in the orthorhombic form of C₃A dispersion formula varies from v > r to v < r with different optic planes (010 and 100 respectively), so that for a certain intermediate content the optic planes for colors at the extremes of the visible spectrum are crossed. In the case of the monoclinic phase dispersion takes place by a rotation of the optic plane around the acute bisectrix X(=c). The characteristic abnormal interference color of the anisotropic C₃A can be explained by these various types of dispersion.     

Inelastic neutron scattering from the vortex lattice in type-II superconductors. I

The inelastic neutron scattering from the vortex lattice in dirty type-II superconductors is considered. In the high-field region, the correlation function for the local magnetization is given in terms of the fluctuation propagator of the superconducting order parameter. In particular it is shown that the Fourier transform of the correlation function for the local magnetization diverges as /q –G _i /^–2, when the transverse transfered momentumq approaches the reciprocal lattice vectorG _i of the Abrikosov lattice. This term gives rise to tails around each Bragg peak in the inelastic neutron-scattering cross section.     

Surface impedance of clean type II superconductors

The surface impedance of clean type II superconductors in calculated in fields nearH _c2 . A marked dependence of the surface impedance on mean free path1, is predicted which is consistent with experiment. The dependence of the surface impedance on the direction of propagation of the microwave is also discussed.     

Syntheses and properties of surfactants containing organometals: IV. Organo silicone

The authors synthesized nonionic surfactants containing dimethylpolysilane, dimethylpolysilmethylene and dimethylopolysiloxane as the hydrophobic groups, and investigated their surface activities. In their ability to lower the aqueous surface tension, the polysiloxane surfactants were the most active, and there is little reason to choose between the other two kinds of surfactants. With regard to the ability of lowering the interfacial tension between water and silicone oil, the polysilmethylene surfactants were most effective when the concentration of aqueous solution was below 0.5 wt %. Above this concentration, however, the polysiloxane surfactants were superior. Also investigated was the lowering of surface tension of nonaqueous polyols and their ability to wet low energy hydrophobic surfaces such as polyethylene.