Robust method of manufacturing rubber waste‐based water repellent surfaces

A novel method of rubber waste recycling is presented. Shredded rubber is processed into a biomimetic superhydrophobic material demonstrating high apparent contact angles (APCAs). Wetting properties of the obtained surfaces are reported. The presented method of rubber waste processing is robust, inexpensive and promises a good potential for building industry. Copyright © 2008 John Wiley & Sons, Ltd.     

Patterned Monolayers of Neutral and Charged Functionalized Manganese Arene Complexes on a Highly Ordered Pyrolytic Graphite Surface

Complex patterns : The arene manganese tricarbonyl complexes [Mn(η⁵‐2,5‐didodecoxy‐1,4‐semiquinone)(CO)₃] and [Mn(η⁶‐1,4‐dioctyloxybenzene)(CO)₃] BF₄ form patterned monolayers on the surface of highly ordered pyrolytic graphite (HOPG), as a result of hydrogen‐bonding, hydrophobic, and electrostatic interactions, leading to an ordered 2D array of manganese atoms or ions.

     

The Nitrogen‐Assisted Triphenylphosphine Displacement of 3‐Hydroxypyridine and 3‐Aminopyridine Ligands in Palladium(II) Complexes: Crystal Structures of [Pd(PPh3)Br]2{μ,η2‐C5H3N(OH)}2 and [Pd(PPh3)Br]2{μ,η2‐C5H3N(NH2)}2

Treatment of Pd(PPh₃₎₄ with 2‐bromo‐3‐hydroxypyridine [C₅H₃N(OH)Br] and 3‐amino‐2‐bromopyridine [C₅H₃N(NH₂)Br] in dichloromethane at ambient temperature cause the oxidative addition reaction to produce the palladium complex [Pd(PPh₃₎₂{η¹‐C₅H₃N(OH)}(Br)], 2 and [Pd(PPh₃₎₂{η¹‐C₅H₃N(NH₂)}(Br)], 3 , by substituting two triphenylphosphine ligands, respectively. In dichloromethane solution of complexes 2 and 3 at ambient temperature for 3 days, it undergo displacement of the triphenylphosphine ligand to form the dipalladium complexes [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(OH)}₂, 4 and [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(NH₂)}₂, 5 , in which the two 3‐hydroxypyridine and 3‐aminopyridine ligands coordinated through carbon to one metal center and bridging the other metal through nitrogen atom, respectively. Complexes 4 and 5 are characterized by X‐ray diffraction analyses.     

Rheology of high internal phase emulsions

The mechanical dispersion technology used in this study employs rotor-stator mixers that produce water-continuous high internal phase emulsions (HIPEs) with narrow drop size distributions and small drop sizes, even when the internal phase (oil) viscosity is quite high. Analysis of these HIPEs reveals trends that are consistent with formation by a capillary instability mechanism in which a shear deformation produces highly elongated drops that rupture to form uniform, small droplets. In the search for a predictive tool to aid in the manufacture and use of HIPEs, rheology data for these shear-thinning HIPEs have been compared to data for models in the literature. Existing models do not correctly account for the effect of a high internal phase viscosity on the rheological properties of the HIPE. Another shortcoming is failure to correctly address the shear-thinning exponent. Whereas internal phase viscosity does not seem to affect the shear-thinning exponent, the surfactant apparently plays an important role, possibly through its modification of the interfacial tension and continuous phase rheology.     

The rigorous derivation of Young, Cassie–Baxter and Wenzel equations and the analysis of the contact angle hysteresis phenomenon

The rigorous derivation of Young, Cassie–Baxter and Wenzel equations carried out in the framework of the unified thermodynamic approach is presented. Wetting of rough surfaces controlled with external stimuli is treated. Areas of validity of Cassie–Baxter and Wenzel approaches are discussed. General properties of the contact angle hysteresis are investigated on the same thermodynamic basis.     

Bounds for the Entries of Matrix Functions with Applications to Preconditioning

Let A be a symmetric matrix and let f be a smooth function defined on an interval containing the spectrum of A. Generalizing a well-known result of Demko, Moss and Smith on the decay of the inverse we show that when A is banded, the entries of f(A)are bounded in an exponentially decaying manner away from the main diagonal. Bounds obtained by representing the entries of f(A)in terms of Riemann-Stieltjes integrals and by approximating such integrals by Gaussian quadrature rules are also considered. Applications of these bounds to preconditioning are suggested and illustrated by a few numerical examples.     

Picard groups and infinite matrix rings

We describe a connection between the Picard group of a ring with local units and the Picard group of the unital overring . Using this connection, we show that the three groups , , and are isomorphic for any unital ring . Furthermore, each element of arises from an automorphism of , which yields an isomorphsm between and . As one application we extend a classical result of Rosenberg and Zelinsky by showing that the group is abelian for any commutative unital ring .

     

A multishift QR iteration without computation of the shifts

Each iteration of the multishift QR algorithm of Bai and Demmel requires the computation of a shift vector defined bym shifts of the origin of the spectrum that control the convergence of the process. A common choice of shifts consists of the eigenvalues of the trailing principal submatrix of orderm, and current practice includes the computation of these eigenvalues in the determination of the shift vector. In this paper, we describe an algorithm based on the evaluation of the characteristic polynomial of a Hessenberg matrix, which directly produces the shift vector without computing eigenvalues. This algorithm is stable, more accurate, faster, and simpler than the current alternative. It also allows for a consistent shift strategy with dynamic adjustment of the number of shifts.The work of this author was in part supported by the National Science Foundation, grant number ESC-9003107, and the Army Research Office, grant number DAAL-03-91-G-0038.     

Construction of simple approximants for the structure factor and magnetization for the simple cubic Ising model

A renormalization group method is used to construct approximants for the magnetization,m, and the static structure factor, (q), for the simple cubic Ising model. Using the best values for the thermal critical index, the transition temperature, and the nearest-neighbor correlation function as input, we obtain recursion relations form and (q) which lead to reasonable results over a wide range of temperatures and wave numbers.     

Traceless Solid‐Phase Synthesis of Cyclopenta[c]quinolines and Cyclopenta[c]chromenes via Hetero [6+3] Cycloadditions of Fulvene. A Facile Approach to the 11‐Heterosteroids Framework

The hetero [6+3] cycloaddition of fulvenes to benzoquinones and iodoanilines provides an efficient route to the synthesis of cyclopenta[c]‐4H‐chromen‐8‐ol, benzo[d]cyclopenta[e]‐3H‐3‐azin‐8‐ol and other 11‐hetero steroids. The structure of the cyclopenta[c]chromene skeleton was confirmed by the X‐ray structure analysis of thep‐bromobenzoate of 39 . A small library consisting of 110 examples was prepared by reacting benzoquinones or iodoanilines with resin 17 .