Preparation and evaluation of nickelmesogen for micropacked gas chromatography

The preparation and mesomorphic properties of a substituted bis(dithiolene)nickel complex derived from 4, 4'-dimethoxybenzil are reported. The phase transition temperatures were based on data obtained by polarized light microscopy and differential scanning calorimetry. The mesogenic phase existed over the temperature range from 77 to 175 degrees C. A novel micropacked column (1.5 or 3 m x 1 mm i.d.) prepared from the slurry of bis[1,2-bis(4-n-undecyloxyphenyl)ethane-1,2-dithiolene] nickel(II) (5%, w/w), coated on Chromosorb W was applied for the separation of dialkyl sulfides. The non-linearity (discontinuity) of Van't Hoff plots suggests that the liquid crystal property existed even in the coated phase. Factors affecting the retention and the sample selectivity on the prepared column were examined by using a flame photometric detector (FPD). The separation might be based on the mechanism of ligand exchange, shape selectivity and polarity interaction besides the vapor pressure. LOD for the determination of dialkyl sulfides was below 1 ng for most of the analytes.     

Fields as Kolmogzrov flows

It is widely recognized that for highly unstable dynamical systems there exists a fundamental limitation on predictability and determinism. An important class of such highly unstable systems is the class of K-flow, which is further characterized by the existence of time-asymmetric objects in the form of K-partition. Our recent approach to the problem of irreversibility has shown that when the implications of the limitation on determinism arising from strong form of instability and those of the existence of K-partition are consistently taken into account, one is naturally led from the physically unrealizable deterministic evolution of phase points to an entropy-increasing stochastic Markovian evolution. Furthermore, this transition is not the result of extraneously imposed coarse graining and/or approximation schemes, but can be brought about by an invertible transformation whose existence and construction are determined by the nature of the instability of the dynamical system itself. After a brief review of this theory which also contains some relatively new remarks, we prove that classical Klein-Gordon field (both massive and massless) possess the structure of K-flow. This seems to provide the first examples of relativistic systems that are K-flows. Some of the implications of this result are briefly discussed. From a mathematical point of view, this seems to be a first step toward an ergodic theory of partial differential equations. In the process, we also provide an independant group-theoretic proof of the existence of incoming and outgoing subspaces of the scattering theory of Lax and Phillips for the wave equation.     

Kinetics of oxidation of some disaccharides in ammoniacal medium

Kinetics of oxidation of lactose, maltose, cellobiose and melibiose has been studied by hexacyanoferrate(III) in the presence of ammonia. A general mechanism involving the formation of intermediate enodiol anion has been suggested. The effects of dielectric constant and salts have been studied in detail. The oxidation products have been characterised by descending paper chromatography. Compensation effects have been observed.     

Vinyl polymerization of acrylamide initiated by Thallium(III) ions in solution

Kinetics of polymerization of acrylamide initiated by Thallium(III) perchlorate was investigated in aqueous perchloric acid medium in the temperature range of 55–70°C. The rates of polymerization were measured varying the concentration of the monomer, initiator, and perchloric acid. The rate of polymerization was found to increase with increase of temperature, monomer concentration, initiator concentration, and perchloric acid concentration. The effect of additives like different solvents, surfactants, and retarders on the rate of polymerization was studied. Molecular weights of the polymer were determined by viscometry. The chain transfer constants for the monomer (C_M) and that for the solvent dioxan (C_s) were calculated to be 7.33 × 10^?3 and 6.66 × 10^?3, respectively. From the Arrhenius plot, the overall activation energy (E_a) was calculated to be 10.68 kcal/mol. The energy of initiation was calculated to be 12.36 kcal/mol. Depending on the results obtained, a suitable reaction mechanism has been suggested and a rate equation has been derived.     

Studies on some newer polyhydrazides containing amide linkages. III

Novel polyhydrazides having inherent viscosities in the range of 0.24–0.38 dL g^?1 were prepared by polymerizing a series of hydrazides with different diacid chlorides in polar aprotic solvents. These polymers display a wide range of solubility in a number of solvents. They start decomposing at about 200°C in air. Results of differential thermal and thermogravimetric analysis show that a steep weight loss takes place mainly in the range of 300–440°C.     

Remote Raman and fluorescence studies of mineral samples

In the present study, we investigated remote laser-induced fluorescence (LIF), at a distance of 4.8 m, of a variety of natural minerals and rocks, and Hawaiian Ti (Cordyline terminalis) plant leaves. These minerals included calcite cleavage, calcite onex and calcite travertine, gypsum, fluorapatite, Dover flint and chalk, chalcedony and nephelene syenite, and rubies containing rock. Pulsed laser excitation of the samples at 355 and 266 nm often resulted in strong fluorescence. The LIF bands in the violet-blue region at approximately 413 and approximately 437 nm were observed only in the spectrum of calcite cleavage. The green LIF bands with band maxima in the narrow range of approximately 501-504 nm were observed in the spectra of all the minerals with the exception of the nephelene syenite and ruby rocks. The LIF red bands were observed in the range approximately 685-711 nm in all samples. Excitation with 532 nm wavelength laser gave broad but relatively low fluorescence background in the low-frequency region of the Raman spectra of these minerals. One microsecond signal gating was effective in removing nearly all background fluorescence (with peak at approximately 610 nm) from calcite cleavage Raman spectra, indicating that the fluorescence was probably from long-lifetime inorganic phosphorescence.     

Spectroscopic study of solid-state photoreaction in organic crystal: Photopolymerization of dimethyl ester of α,α′-dicyano-p-phenylenediacrylic acid and diethyl ester of p-phenylenediacrylic acid

Raman spectroscopy has been used to study solid-state photopolymerization reactions in dimethyl ester of α,α′-dicyano-p-phenylenediacrylic acid (p-CPAMe) and diethyl ester of p-phenylenediacrylic acid (p-PDAEt). The reactants and products were characterized by infrared and Raman spectroscopy. Excitation and emission spectra suggest that in p-CPAMe exciton–phonon coupling is strong, but in the other monomer it is very weak. Raman phonon spectroscopic study reveal that in both the samples the reaction mechanism is homogeneous in the initial stages. However, in the later stages the reaction becomes heterogeneous in p-PDAEt. In p-CPAMe the lattice becomes disordered with the progress of polymerization and finally becomes amorphous whereas in p-PDAEt the lattice remains highly ordered. © 1992 John Wiley & Sons, Inc.     

Oscillation of higher order delay differential equations

A sufficient condition was obtained for oscillation of all solutions of theodd-order delay differential equation $$x^{(n)} (t) + \sum\limits_{i = 1}^m {p_i (t)} x(t - \sigma _{_i } ) = 0,$$ wherep _i (t) are non-negative real valued continuous function in [T ∞] for someT≥0 and σ_i,∈(0, ∞)(i = 1,2,…,m). In particular, forp _i (t) =p _i ∈(0, ∞) andn > 1 the result reduces to $$\frac{1}{m}\left( {\sum\limits_{i = 1}^m {(p_i \sigma _i^m )^{1/2} } } \right)^2 > (n - 2)!\frac{{(n)^n }}{e},$$ implies that every solution of (*) oscillates. This result supplements forn > 1 to a similar result proved by Ladaset al [J. Diff. Equn.,42 (1982) 134–152] which was proved for the casen = 1.     

Laser Raman spectroscopic study of photoreaction dynamics in p -chloro cinnamic acid crystal

Raman phonon spectroscopy has been used to study photodimerization reaction inp-chloro cinnamic acid (pCCA) crystal. The β-form of the crystal yields the 4,4′-dichloro-β-truxinic acid dimer. Six distinct low frequency phonon bands are observed in thepCCA monomer crystal. On reaction progress, these bands show a monotonic shift to lower frequencies and broaden out. Finally, in the dimer crystal the phonon spectrum shows two weak broad bands. These results suggest that the reaction is homogeneous in the initial stages and, as the product concentration increases, the lattice becomes highly disordered. The reactant and the product were characterised by infrared and Raman spectroscopy. The disappearance of aliphatic C=C bond stretching vibration and appearance of cyclobutane ring deformation and cyclobutane ring-breathing vibrations on reaction confirm photodimerization by cyclobutane ring formation. The large Stoke's shift between the absorption and emission band suggest strong exciton-phonon coupling in the monomer lattice. This reaction seems to be phonon-mediated.