On the Hamilton-Jacobi Treatment of Constrained Systems

Systems with singular-higher order Lagrangians are investigated by two methods: Dirac method and Hamilton-Jacobi method. An example is studied and it is shown that the Hamilton-Jacobi method gives the correct canonical generalized equations of motion, contrary to Dirac method, where Dirac conjecture is invalid.     

Synthesis and self‐catalyzed phase transfer reaction of novel methacrylate polymers

Ethyl α‐chloromethylacrylate was converted to an ester derivative using 5‐chlorovaleric acid in a single step. The homopolymerization of the new monomer (CEMA) and its copolymerization with methyl methacrylate were performed using photoinitiator Irgacure 651. The polymers were reacted with N,N‐dimethyldodecylamine to obtain polymers with pendant quaternary ammonium (QA) moieties. The polymers with pendant QA groups were used in self‐catalyzed phase transfer reactions with sodium phenoxide and 1‐dodecanethiol. The syntheses of the monomer and polymers were followed by FTIR, ¹H NMR, and ¹³C NMR. The average polymer molecular weights and polydispersities were determined by size exclusion chromatography. Thermal analysis was carried out using thermogravimetric analysis and differential scanning calorimetry. The copolymer composition, degree of quaternization, and degree of conversion in phase transfer reaction were determined by ¹H NMR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5844–5854, 2005     

Effective spectral emissivity measurements of superalloys and YSZ thermal barrier coating at high temperatures using a 1.6μm single wavelength pyrometer

A method which employs an integrating sphere and a single-wavelength (1.6 μm) pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range (=650–1050°C) is described. The spectral effective emissivities for five superalloys, namely, MARM-247, MARM-509, CMSX-4, Inconel-718, N-155 and two René-N6 samples coated with YSZ thermal barrier coating were measured. Correcting the pyrometer measurements for the variations in the object emissivity would reduce the uncertainty in the temperature measurements to <±1%.     

The Aldehyde Ketone Rearrangement. Rearrangement of Bis(4-methoxyphenyl)-acetaldehyde into 4,4′-Dimethoxydeoxybenzoin

The formyl carbonyl group in bis(4-methoxyphenyl)-acetaldehyde does not contribute to the formation of the carbonyl group in 4,4′-dimethoxydeoxybenzoin when the former rearranges to the latter by treatment with 50% (w/w) sulfuric acid.     

Preparation and characterisation of some 4,4-dimethylbuta-1,3-dienone-transition metal carbonyls

(4,4-Dimethylbuta-1,3-dienone)iron tricarbonyl (IIa) is obtained in 70% yield from 3,3-dimethylcyclopropene (I) and nonacarbonyldiiron and in 17% yield from I and pentacarbonyliron. Analogously (4,4-dimethylbuta-1,3-dienone)-(η⁵-cyclopentadienyl)manganese carbonyl (V) is formed from I and (η⁵-cyclopentadienyl)(tetrahydrofuran)manganese dicarbonyl. Complexes IIa and V have been characterised by physical and chemical methods. Triphenylphosphine displaces one CO ligand from IIa to yield the corresponding triphenylphosphine-iron complex. The structure of IIa has been determined by X-ray diffraction.     

Kerr modulation of planar waveguides

We describe two methods for employing materials with giant Kerr nonlinearities for modulating waveguides. A beam, of relatively intense light, is used to vary the propagation constant of a waveguide with the guiding layer, or the substrate, made from a nonlinear material.     

Electric-analog studies of impact dampers

An experimental study is made of the general behavior of single-particle impact dampers, using an electronic-analog computer and a mechanical model. It is found that, under practically realizable conditions, impact damping is effective in reducing the vibration-amplitude levels resulting from sinusoidal or random excitation. Paper was presented at 1966 SESA Spring Meeting held in Detroit, Mich., on May 4–6.     

Heating mechanism in relation to the laser machining process

Laser workpiece interaction mechanism is an important phenomenon which will assist in the development of laser machining systems. The interaction mechanism is generally complicated and depends on the laser and workpiece properties. In the present study a mathematical analysis for the laser material removal by evaporation and radial ejection of liquid is carried out. In the analysis the time unsteady problem is solved and nucleation explosions are predicted.     

Quantum Effect on the Energy Levels of Eu2+ Doped K2Ca2(SO4)3 Nanoparticles

Quantum confinement effect on the energy levels of Eu²⁺ doped K₂Ca₂(SO₄)₃ nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu²⁺ doped K₂Ca₂(SO₄)₃ microcrystalline sample observed at ～436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f⁶5d energy level of Eu²⁺. Energy band gap values of the micro and nanocrystalline K₂Ca₂(SO₄)₃ samples were also determined by measuring the UV–visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises.     

Fast HPLC method for the determination of glimepiride, glibenclamide, and related substances using monolithic column and flow program

This work presents a fast method for the simultaneous separation and determination of glimepiride, glibenclamide, and two related substances by RP LC. The separation was performed on a Chromolith Performance (RP-18e, 100 mm x 4.6 mm) column. As mobile phase, a mixture of phosphate buffer pH 3, 7.4 mM, and ACN (55:45 v/v) was used. Column oven temperature was set to 30 degrees C. The total chromatographic run time was 80 s. This was achieved using a flow program from 5 to 9.9 mL/min. Precisions of the interday and the intraday assay for both retention times and peak areas for the four analyzed compounds were less than 1.2%. The method showed good linearity and recovery. The short analysis time makes the method very valuable for quality control and stability testing of drugs and their pharmaceutical preparations.