等宽多孔介质壁面管道中磁流体的流动

研究等宽管道中,磁场、可渗透壁面、Darcy速度和滑动参数,对流体稳定流动的综合影响.假设管道中流动的流体是均匀的、不可压缩的Newton流体.利用Beavers-Joseph滑动边界条件,得到控制方程的解析解.详细地讨论了磁场、可渗透性、Darcy速度和滑动参数对轴向速度、滑动速度和剪应力的影响.可以看出,Hartmann数、Darcy速度、多孔参数和滑动参数,在改变流动方向,进而改变剪应力方面,起着至关重要的作用.     

Effect of RF power and sputtering pressure on the structural and optical properties of TiO2 thin films prepared by RF magnetron sputtering

TiO₂ thin films were deposited onto quartz substrates by RF magnetron sputtering. The samples deposited at various RF powers and sputtering pressures and post annealed at 873 K, were characterized using X-ray diffraction (XRD), micro Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. XRD spectrum indicates that the films are amorphous-like in nature. But micro-Raman analysis shows the presence of anatase phase in all the samples. At low sputtering pressure, increase in RF power favors the formation of rutile phase. Presence of oxygen defects, which can contribute to PL emission is evident in the XPS studies. Surface morphology is much affected by changes in sputtering pressure which is evident in the SEM images. A decrease in optical band gap from 3.65 to 3.58 eV is observed with increase in RF power whereas increase in sputtering pressure results in an increase in optical band gap from 3.58 to 3.75 eV. The blue shift of absorption edge in all the samples compared to that of solid anatase is attributed to quantum size effect. The very low value of extinction coefficient in the range 0.0544-0.1049 indicates the excellent optical quality of the samples. PL spectra of the films showed emissions in the UV and visible regions.     

Depth-dependent Anisotropy of Proteoglycan in Articular Cartilage by Fourier Transform Infrared Imaging

Fourier transform infrared microscopic imaging (FTIRI) was used to quantitatively examine the anisotropies of proteoglycan (PG) and collagen in articular cartilage. Dried 6 μm thick sections of canine humeral cartilage were imaged at 6.25 μm pixel-size in FTIRI with an infrared analyzer set at 26 different angles between 0° and 180° polarization. Like the amide II and amide III peaks, the 1338 cm⁻¹ band confirms the anisotropy of collagen fibrils in cartilage. The absorption profile of the sugar band shows an anisotropic flipping at the deeper part in the radial zone, just above the tidemark. Together with the reduction in the PG concentration and subsequent increase in tissue calcification in this region, this anisotropy flipping of sugar might be caused by the orientational change in the collagen-attaching PG from orthogonal to parallel when the fibrils are entering the calcified zone.     

Synthesis and biological evaluation of 3-hydroxypyrazoles as aquaporin 9 inhibitors

A series of 3-hydroxypyrazole derivatives have been synthesized by a base-promoted reaction of nitro-substituted donor–acceptor cyclopropanes with hydrazines. The synthesized compounds have been investigated for their ability to inhibit aquaporin 9 (AQP9) in rat Leydig cells (LC-540). The protein data bank structure for AQP9 was predicted using homology modeling; and the protein–ligand interaction for the synthesized hydroxyl pyrazole derivatives were analyzed using molecular modeling and docking studies. The results of in silico analyses showed that compound 5b had a higher binding affinity with AQP9 than other compounds. Further, in vitro studies conducted in LC-540 cells confirmed that compound 5b effectively inhibits AQP9. Hence, compound 5b may be used as an inhibitor in enhancing our understanding of AQP9 function, and in the treatment of several diseases.     

Hydrogen-bonded ferroelectrics: Evidence for Slater configurations from E.P.R. studies of X-irradiated KH2AsO4 and NH4H2AsO4

The temperature dependence of the powder E.P.R. spectrum of the AsO₄ ^4- centre in x-irradiated samples of KH₂AsO₄ and NH₄H₂AsO₄ yields results which can be understood as arising from exchange processes taking place between the six configurations in the Slater model for this type of hydrogen-bonded ferroelectric and antiferroelectric. Knowing that the ⁷⁵As hyperfine parameters have rhombic symmetry in the compounds studied, it is possible to interpret certain specific features in the spectra as being associated with the Slater configurations of higher energy.     

Two circles and their common tangents

Given two circles C ₁ and C ₂ in a plane such that neither one of the two circles is contained in the other, there are either four common tangents when the circles do not intersect at all or the circles have three common tangents when they touch each other externally or only two common tangents when the circles intersect exactly at two points. The article oulines analytical procedures for computing the equations of these common tangents. Using the built-in Maple of the software Scientific Work Place 3.0, the diagrams of the circles with their common tangents are incorporated in this article.     

The construction of a special equilateral triangle

This article deals with the construction of an equilateral triangle that must satisfy the following special constraint conditions. If the equilateral triangle is denoted by ΔABC, then the radii of the inscribed circle, the three escribed circles of ΔABC, and the circumcircle of ΔABC all must have positive integral radii. The inscribed circle radius is required to be 1 unit. The three escribed circles that have equal radii must have 3 units each, and the circumcircle of the triangle must have 2 units. All these requirements may seem outlandish. The aim is to teach crucial Geometric principles that Geometric designs must take into account before the constructions are implemented. This article hopefully may be useful to students of College Geometry as well as teachers.     

On the Lusternik–Schnirelmann category of Peano continua

We define the LS-category _catg${\mathrm{cat}}_g$ by means of covers of a space by general subsets, and show that this definition coincides with the classical Lusternik–Schnirelmann category for compact metric ANR spaces. We apply this result to give short dimension theoretic proofs of the Grossman–Whitehead theorem and Dranishnikov?s theorem. We compute _catg${\mathrm{cat}}_g$ for some fractal Peano continua such as Menger spaces and Pontryagin surfaces.     

Contemplations on the impressions of MeV swift heavy ion irradiation on nonlinear optical dimethyl-amino-pyridinium-4-nitrophenolate-4-nitro-phenol (DMAPNP) single crystals

Organic nonlinear optical crystal dimethyl-amino-pyridinium-4-nitrophenolate-4-nitro-phenol was subjected to 100 MeV Ag⁸⁺ ions and 50 MeV Si⁸⁺ ions. The radiation effects are studied in terms of processes observed with the pristine samples and in comparison with them. The dielectric properties of the crystals were studied before and after irradiation from 100 Hz to 5 MHz at various temperatures (308–383 K). A drastic increase in the dielectric constant is seen due to irradiation. The dielectric constant and conductivity increases with the increase of irradiation fluence for the samples. The observed results are discussed in detail.