Self-assembly of boehmite nanopetals to form 3D high surface area nanoarchitectures

A flower-like boehmite nanostructure was prepared through a template-free chemical route by the self-assembly process of nanosize petals 800–1000 nm long, 200–250 nm wide, 20–50 nm thick and having an average crystallite size of about 2.21 nm. X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), DTA/TGA analyses and Brunauer–Emmet–Teller (BET-N₂) analyses were used in order to characterize the product obtained. XRD results exhibited that the obtained nanostructures composed of pure orthorhombic AlOOH phase. The effects of Cl⁻ ions and TEA on the growth of boehmite three-dimensional nanoarchitectures in the presence of NO₃^-\mathrm{NO}_{3}^{-} ions were investigated. BET analyses of as-prepared material demonstrate that this nanostructure material has a high specific surface area, as high as 123 m² g⁻¹.     

Remote photoacoustic imaging on solid material using a two-wave mixing interferometer

We report on remote and contactless photoacoustic imaging (PAI) for the inspection of solid materials using a two-wave mixing interferometer. In this Letter, a semitransparent sample was excited with picosecond laser pulses. The local absorption of the electromagnetic radiation led to generation of broadband ultrasonic waves inside the sample. Ultrasonic waves arriving at the sample surface were detected utilizing a two-wave mixing interferometer. After data acquisition, the initial pressure distribution was reconstructed using a Fourier space synthetic aperture technique algorithm. We show the potential of PAI for the inspection of semitransparent solid materials.     

Clustering Categorical Data via Ensembling Dissimilarity Matrices

We present a technique for clustering categorical data by generating many dissimilarity matrices and combining them. We begin by demonstrating our technique on low-dimensional categorical data and comparing it to several other techniques that have been proposed. We show through simulations and examples that our method is both more accurate and more stable. Then we give conditions under which our method should yield good results in general. Our method extends to high-dimensional categorical data of equal lengths by ensembling over many choices of explanatory variables. In this context, we compare our method with two other methods. Finally, we extend our method to high-dimensional categorical data vectors of unequal length by using alignment techniques to equalize the lengths. We give an example to show that our method continues to provide useful results, in particular, providing a comparison with phylogenetic trees. Supplementary material for this article is available online.     

Modeling elongational viscosity of blends of linear and long-chain branched polypropylenes

To enhance the melt strength of a conventional linear polypropylene (L-PP), blends with a long-chain branched polypropylene (LCB-PP) were produced by adding 2, 5, 10, 25, 50, and 75 wt% of LCB-PP to L-PP and mixing in a twin screw extruder. It was found that, already, an addition of 10% or less of LCB-PP to L-PP leads to significant strain hardening. Elongational viscosity data of L-PP and LCB-PP and those of their blends were analyzed by the use of the molecular stress function (MSF) theory. While L-PP is characterized by the MSF parameter, β=1 (typical for linear melts), and shows very little chain stretch (), melt elongational behavior of LCB-PP is characterized by the MSF parameters, β=2 (typical of LCB melts), and (which corresponds to a maximum stretch of molecular chains by a factor of 15). By extruding LCB-PP, a refining effect is observed similar to the refining effects seen in low density polyethylene (LDPE), which reduces the steady-state elongational viscosity and reduces to 121. A second-order mixing rule for the fractional relaxation moduli, g _i , was found to show good agreement with the linear-viscoelastic data of the blends. To simulate the elongational viscosities of the L-PP/LCB-PP blends, a similar second-order mixing rule was used for the MSF parameter, β, while a first-order mixing rule was found to be appropriate for . This allows for a quantitative prediction of the time-dependent elongational viscosities of all L-PP/LCB-PP blends on the basis of the linear and nonlinear parameters of the mixing components L-PP and LCB-PP only. Comparison between the steady-state elongational viscosities as obtained from creep experiments shows good agreement with predictions.     

Homotopy analysis method for multiple solutions of the fractional Sturm-Liouville problems

In this paper, Homotopy Analysis Method (HAM) is applied to numerically approximate the eigenvalues of the fractional Sturm-Liouville problems. The eigenvalues are not unique. These multiple solutions, i.e., eigenvalues, can be calculated by starting the HAM algorithm with one and the same initial guess and linear operator L\mathcal{L}. It can be seen in this paper that the auxiliary parameter (^h/_2p),\hbar, which controls the convergence of the HAM approximate series solutions, has another important application. This important application is predicting and calculating multiple solutions.     

A note on slant submanifolds of nearly trans-Sasakian manifolds

The geometry of slant submanifolds of a nearly trans-Sasakian manifold is studied when the tensor field Q is parallel. It is proved that Q is not parallel on the submanifold unless it is anti-invariant and thus the result of [CABRERIZO, J. L.—CARRIAZO, A.—FERNANDEZ, L. M.—FERNANDEZ, M.: Slant submanifolds in Sasakian manifolds, Glasg. Math. J. 42 (2000), 125–138] and [GUPTA, R. S.—KHURSHEED HAIDER, S. M.—SHARFUDIN, A.: Slant submanifolds of a trans-Sasakian manifold, Bull. Math. Soc. Sci. Math. Roumanie (N.S.) 47 (2004), 45–57] are generalized.     

Certain strict topologies on the space of regular Borel measures on locally compact groups

Let G   denote a locally compact Hausdorff group and M(G)$M(G)$ be the space of all bounded complex-valued regular Borel measures on G  . In this paper, we define two strict topologies on M(G)$M(G)$ and study various properties of these topologies such as metrizability, barrelledness and completeness. We also determine the dual space of M(G)$M(G)$ and consider various continuity properties for the convolution product on M(G)$M(G)$ under these topologies.     

Antiferromagnetic half-metallicity of transition metal nitrides under volume expansion

The transition metal pnictides ABX₂ have been recently proposed as half-metallic fully compensated ferrimagnets, also briefly referred to as half-metallic “antiferromagnets” [N. Long, M.Ogura, H. Akai, J. Phys.: Condens. Matter 21, 064241 (2009)]. In this work we carry out a systematic study of the more promising cases of the transition metal nitrides MnCoN₂ and NiCrN₂ on the basis of density functional theory in the framework of full-potential linearized augmented plane wave method. The electronic structures and the magnetic properties of the above hypothetical compounds in Zinc-blende-type, NaCl-type, and Wurtzite-type structure are calculated within generalized gradient approximation. The results reveal that, although these compounds are metallic in their bulk equilibrium in all three structures, they exhibit antiferromagnetic half-metallicity under negative stress or volume expansion in a limited range of lattice parameters, which is significantly larger than the equilibrium values. This suggests that a situation in which half-metallicity may arise, is when these compounds are coated on semiconducting layers of larger lattice constant.     

A presentation for reduced extended affine weyl groups

In 1985 K. Saito [Sal] introduced the concept of an extended affine Weyl group (EAWG), the Weyl group of an extended affine root system (EARS). In [A2, Section 5J, we gave a presentation called “a presentation by conjugation” for the class of EAWGs of index zero, a subclass of EAWGs. In this paper we will give a presentation wh.ich we call a “generalized present.ation by conjugation” for the class of reduced EAWGs. If the extended affine Weyl group is of index zero this presentation reduces to “a presentation by conjugation”. Our main result states that when the nullity of the EARS is 2, these two presentations coincide that is, EAWGs of nullity 2 have “a presentation by conjugation”. In [ST] another presentation for EAWGs of nullity 2 is given.