Synthesis and structure of potential Lewis acid–Lewis base bifunctional catalysts: 1-N,N-dimethylamino-8-borononaphthalene derivatives

A new series of boronate-amine substituted potential bifunctional catalysts have been prepared by directed lithiation of 1-N,N-dimethylnaphthalene, followed by reaction borate esters. Both diisopropyl and pincacol ester derivatives of the resulting boronates were prepared, together with a novel boroxine which shows novel N–B interactions in the crystal structure. The corresponding dimethyl-[8-(difluoroborolyl)-naphthalen-1-yl]-amine was directly accessed from the boroxine by reaction with potassium hydrogen fluoride.     

A fiber connectorized MEMS variable optical attenuator

A voltage-controlled moving-mirror microelectro-mechanical systems variable optical attenuator is described that has less than 1-dB fiber-to-fiber insertion loss at 1550-nm wavelength and greater than 50-dB dynamic range. The device was configured with a simple feedback circuit to operate as an optical power regulator capable of stabilizing the output power to within 0.26 dB for a 12-dB input power excursion     

Alpha-induced coulomb excitation for the determination of vanadium and molybdenum in steels

A simple, rapid and non-destructive method for the determination of vanadium and molybdenum in steels is described. The method uses prompt spectrometry of the gammarays obtained from coulomb excitation with 5 MeV alpha particle beams. Using the 320 KeV gamma-ray, 3.3% precision was obtained for vanadium analysis. The precision for molybdenum was 3.2% and 5.3% using the gamma-rays of 204 and 536 keV, respectively. The extent of interference from other elements is discussed.     

Routing in optical multistage interconnection networks: a neuralnetwork solution

There has been much interest in using optics to implement computer interconnection networks. However, there has been little discussion of any renting methodologies besides those already used in electronics. In this paper, a neural network routing methodology is proposed that can generate control bits for a broad range of optical multistage interconnection networks (OMIN's). Though we present no optical implementation of this methodology, we illustrate its control for an optical interconnection network. These OMIN's can be used as communication media for distributed computing systems. The routing methodology makes use of an artificial neural network (ANN) that functions as a parallel computer for generating the routes. The neural network routing scheme can be applied to electrical as well as optical interconnection networks. However, since the ANN can be implemented using optics, this routing approach is especially appealing for an optical computing environment. Although the ANN does not always generate the best solution, the parallel nature of the ANN computation may make this routing scheme faster than conventional routing approaches, especially for OMIN's that have an irregular structure. Furthermore, the ANN router is fault-tolerant. Results are shown for generating routes in a 16×16, 3-stage OMIN     

Tailoring the microwave permittivity and permeability of composite materials

The microwave permittivity (?_r) and permeability (µ_r) of composite materials are tailored by adding various loading agents to a host plastic and are subsequently modeled using the Maxwell Garnett theory and second order polynomials. With the addition of manganese zinc ferrite, strontium ferrite, nickel zinc ferrite, barium tetratitanate and graphite powders, materials with values of ?′, e″, µ′, µ″ as high as 22, 5, 2.5 and 1.7 have been obtained. Permittivity and permeability data are calculated at 2.0245 GHz from reflection and transmission measurements performed in a 7 mm coaxial test line. The Maxwell Garnett (MG) theory successfully models ?_r if the filling factor is less than 0.30 and ratio |?₁| (host)/ |?₂| (powder) is greater than 0.04. As this ratio decreases, the MG theory is shown to be independent of ?₂ and second order polynomials are used to effectively model the dielectric constant. Polynomials are also used for the ferrite composites because it was determined that the MG theory was unable to model µ_r. This deficiency is attributed to the difference of domain structures that exist in powdered and sintered ferrites.     

An abnormal fries rearrangement induced by a peri-methoxyl group in monoacetates of naphthohydroquinones.

The acetyl group of two 1-acetoxy-4-hydroxy-5-methoxynaphthalenes migrates to C-3 on treatment with boron trifluoride etherate.     

Related necessary conditions for completing partial latin squares

Three classes of necessary conditions for completing partial latin squares are studied. These condition classes are derived via network flow theory, bipartite graph matching theory and by relating the completion problem to triply stochastic matrices. The latter formulation suggest an integer programming model of the completion problem which is convenient for analyzing the relative strength of the three condition classes. It is shown that these classes are nested and examples are given to demonstrate that this nesting is proper.