On the design and performance of printed-circuit filters and diplexers for millimeter-wave integrated circuits

This paper describes the design and performance of various millimeter-wave printed-circuit filters and diplexers. These components include microstrip/suspended stripline and finline lowpass filters, capacitive-gap and inductive-iris-coupled bandpass filters, spurline bandstop filters, and finline diplexers. State-of-the-art performances from Ka-band (26.5 to 40 GHz) to D-band (110 to 170 GHz) have been obtained. Agreement between the measured and calculated results was also achieved.     

Meeting the Requirements of the Silver/Silver Chloride Reference Electrode

Potentiometric cells from which the pH values of standard buffer solutions are computed rely on the silver–silver chloride reference electrode which has proved to be convenient, reproducible and reliable. Of the various methods of preparation of silver-silver chloride electrodes only one concerns us here: the thermal–electrolytic type that has been used more extensively than any other form. Once prepared, the electrodes need to be equilibrated before use and between experiments. The equilibration technique must ensure voltage stability and inter-electrode, or bias, potential below 0.1 mV. In potentiometry the stability of a reference electrode is of utmost importance since an offset of 1 mV is equivalent to a deviation of about 0.02 in the pH value.     

Synthesis, structure, and nonlinear optical properties of diarylpolyynes

A series of alpha,omega-diarylpolyynes has been synthesized. In addition to the synthesis of three hexaynes (3a-c), a notably improved synthesis of 1,16-diphenylhexadecaoctayne (5) is described. The third-order nonlinear optical characteristics for these molecules have been studied and show a substantial increase in molecular hyperpolarizability (gamma) as a function of increasing length. The unusual solid-state structures of compounds 3a and 3b are reported.     

Studies on the syntheses of heterocyclic compounds—DXCI : Total synthesis of (±)-cherylline and corgoine through quinonoid intermediates

Acid catalysed cyclisation of N - (4′ - benzyloxy - β - methoxyphenethyl) - 3 - benzyloxy - 4 - methoxy - N-methylbenzylamine (18) gave (±)-cherylline (1), one of the Amaryllidaceae alkaloids. Fusion of 4-hydroxybenzyl alcohol (22) with 1,2,3,4-tetrahydroisoquinoline (24) also gave corgoine (5).     

Flash photolysis study of the NO-catalyzed recombination of bromine atoms

The recombination of bromine atoms at room temperature has been studied by flash photolysis in the range of 1–100 atm of the inert diluent He, leading to a value for the third-order rate constant of (1.5 ± 0.2) × 10¹⁵ cm⁶/mol².sec. In the presence of NO the recombination is considerably accelerated. The falloff curve of the recombination Br + NO (+He) → BrNO (+He) was also measured resulting in a value for the limiting low-pressure rate constant of (3.4 ± 1.3) × 10¹⁵ cm⁶/mol².sec. In experiments with excess NO, rate constants of (2.2 ± 1) × 10¹⁴ cm³/mol·sec for the reaction Br + BrNO → Br₂ + NO, and (6.1 ± 0.4) × 10⁹ cm⁶/mol².sec for the reaction Br₂ + 2NO → 2BrNO were obtained.     

DSC Application in the Conservation Field

Differential scanning calorimetry (DSC) has been scarcely used in conservation field and in particular, in the study of painting layers. However DSC is a micro-destructive technique (sample from .05 to 1 mg can be analysed) because no pre-treatment of the sample is required and so it can give rapid and useful information. The aim of the present work is, in fact, to describe useful applications of DSC on the study of materials used in art. The analyses have been conducted under oxygen flow in order to register the thermo-oxidative reactions of the organic binder or protective. In the first part of the paper, materials of different chemical composition have been analysed to build up a data base of DSC profiles. Standard painting layers artificially degraded by treatment with ultraviolet light (365 nm) for 21 days and with NO_x (5 ppm)have be en analysed. Comparing the behaviour of the treated to the reference sample, it is useful to study what kind of changes the treatments have produced on the sample. Another possible application of DSC is the study of the formation of the film; analysing the raw,liquid binders and the different naturally aged films an evolution of the chemical structure canbe registered. As a conclusion, DSC analyses on standard used in artistic field allow to investigate their thermal behaviour and to understand the effect of natural and artificial ageing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Existence of Finite-Time Hyperbolic Trajectories for Planar Hamiltonian Flows

We present a shadowing theorem on the existence of hyperbolic trajectories on finite time intervals based on the EPH partition by George Haller and apply it to an example which is inspired by the problem of two-dimensional symmetric vortex merger.     

Two New Glycosides from the Water Extract of Lepisanthes rubiginosa Collected in Vietnam

Chemistry of Natural Compounds - In this attempt to seek promising compounds from Lepisanthes rubiginosa, a widely used folk medicine in the middle of Vietnam, we isolated four compounds from the...