On‐Wafer Crystallization of Ultralow‐κ Pure Silica Zeolite Films

A higher goal : An on‐wafer crystallization process to prepare pure silica zeolite (PSZ) MEL‐type films that is superior to the previously used hydrothermal process is reported. These striation‐free MEL‐type films (right, see picture) outperform the traditional spin‐on films (left) in terms of the κ value, mechanical properties, surface roughness, mesopore size, and size distribution.

     

In‐situ Chemiluminescence‐Driven Reversible Addition–Fragmentation Chain‐Transfer Photopolymerization

The power of chemical light generation (chemiluminescence) is used to drive polymerization reactions. A biphasic reaction is developed such that light‐generating reactions are confined to the organic phase and photopolymerization occurs in the aqueous phase. Well‐defined RAFT‐capped polymers are synthesized and the kinetics are shown to be dictated by light generation.     

Compactification of Two Dimensions in General Relativity

Motivated by Kaluza-Klein theory and modern string theories, the class of exact solutions yielding product manifolds M ₂ × S ² in general relativity is investigated. The compact submanifold homeomorphic to S ² is chosen to be a very small sphere. Choosing an anisotropic fluid as the particular physical model, it is proved that very large mass density and tension provide the mechanism of compactification. In case the transverse pressure is chosen to be zero, the corresponding spacetime is homeomorphic to ² × S ², and thus provides a tractable non-flat metric. In this simple metric, the geodesic equations are completely solved, yielding motions of massive test particles. Next, the corresponding wave mechanics (given by the Klein-Gordon equation) is explored in the same curved background. A general class of exact solutions is obtained. Four conserved quantities are explicitly computed. The scalar particles exhibit a discrete mass spectrum.     

A tensor estimator for the homogenization of absolute permeability

An estimator for an effective permeability tensor based on one-phase incompressible flow is presented. Effective large-scale permeability tensors are well approximated by rough approximations to the fine-scale pressure. The estimator works for all kinds of heterogeneous reservoirs and is fairly independent of boundary conditions.     

Ab initio molecular orbital calculations on H3AlOH2, (H2AlOH)2, and some related species

Ab initio molecular orbital calculations have been carried out on H₃AlOH₂, (H₂AlOH)₂, and some related species, and the charge distribution and bonding are discussed on the basis of population analyses. It is found that the equilibrium conformation around the O atom in H₃AlOH and (H₂AlOH)₂ is intermediate between trigonal and tetrahedral. The energy minima are, however, very shallow. In H₃AlOH₂ the angle between the Al-O bond and the H₂O plane is 27°, in (H₂AlOH)₂ the angle between the two O-H bonds and the Al₂O₂ ring plane is 25°. The energy of a planar conformation of H₃AlOH₂ is 0.19 kcal mol^-1, the energy of a planar conformation of (H₂AlOH)₂ 0.35 kcal mol^-1 above the equilibrium conformation. There is no indication for the formation of dative pπ-dπ bonds between O and Al in the two molecules. It is suggested that the conformation adopted by analogous alkyl derivatives, R₃AlOR'₂ and (R₂AlOR')_n is determined by intramolecular van der Waals repulsion.     

Highly efficient photoreduction of water using energy transfer

The photochemistry of the system water-tris(2,2′-bipyridine)ruthenium(II) dication—9-anthracenecarboxylate anion—methylviologen—ethylenediaminetetraacetic acid—platinum has been studied. Efficient triplet energy transfer from the excited ruthenium complex to the anthracene derivative leads to the formation of hydrogen in quantum yields up to 0.85.