Side Radical Research Articles

Calorimetric study of dissolution of amino carboxylic acids in water at 298.15 K

The enthalpies of solution of glycine, DL-alanine, D-valine, and L-serine in water at 298.15 K were measured on a special ampule calorimeter equipped with an isothermal shell. The enthalpies of hydration of 12 α-amino acids differing in the steric configurations of the side radical were estimated using the measured values and the published data on the heats of solution and sublimation for biologically active substances. The influence of hydrophobicity of the substances on their dissolution and hydration was considered.

Solitary psoas muscle metastasis after radical nephrectomy for renal cell carcinoma

Skeletal muscle is a very rare location for the metastasis of renal cell carcinoma (RCC) and only one case of solitary metastasis to the psoas muscle has been reported. We present a 63-year-old male patient with late recurrence (14 years) after left side radical nephrectomy for RCC. He first visited Chikushi Hospital, Fukuoka University, Japan in January 2000 for a postoperative follow-up because he had shifted residence to the area. Follow-up was by abdominal computed tomography (CT) and chest X-ray. In December 2001, a CT scan showed a 1.5 cm enhanced mass in the right psoas muscle without any other metastasis. The mass was resected that month and histological study showed RCC metastasis.

The genetics of renal oncocytosis: a possible modelfor neoplastic progression

Renal oncocytosis is a rare condition characterized by the presence of numerous oncocytomas and oncocytic changes in the renal tubules. Other than oncocytomas associated with the Birt-Hogg-Dube (BDH) syndrome, the genetics of oncocytosis is not known. Whether oncocytomas and oncocytosis are similar to BDH syndrome, in which the tumors diploid (as most oncocytomas are), or show chromosomal losses may be significant regarding the observation that in oncocytosis, there frequently is morphological evidence of progression to chromophobe carcinoma. Here we report on the case of a 69-year old male who underwent a staged procedure of partial nephrectomy on the left side and right radical nephrectomy for multiple renal tumors. The tumors were studied by routine hematoxylin and eosin morphology, immunohistochemistry, cytogenetics, and loss of heterozygosity analysis. Both kidneys had numerous oncocytic neoplasms morphologically progressing from oncocytomas to hybrid tumors with chromophobe carcinoma. Genetic studies demonstrated progression from normal cytogenetics to chromosomal losses similar to those in some oncocytomas and in chromophobe carcinomas. The genetics of this apparently nonfamilial oncocytoma differs from that of BDH syndrome and is characterized by losses involving chromosomes 1, 14, 21, and Y. To our knowledge, this is the first report of the genetic and cytogenetic findings in oncocytosis not related to BDH syndrome and may suggest a possible model of progression from oncocytoma to chromophobe renal cell carcinoma.

Side radical influence on the nonlinear optical properties and thermal stability of poled polymer films

Films of polyetherketone doped with the chromophores Disperse Red 1 (DR1) and Disperse Red 13 (DR13) were prepared by spin-coating method. By the in situ Second-harmonic Generation (SHG) signal intensity measurement, the optimal poling temperatures were obtained. For the investigated polyetherketone polymer doped with DR1 (DR1/PEK-c) and polyetherketone polymer doped with DR13 (DR13/PEK-c) films, the optimal poling temperatures were 150°C and 140°C, respectively. Under the optimal poling conditions, the high second-order nonlinear optical coefficient χ33(2) = 11.02 pm/V has been obtained for the DR1/PEK-c; and for DR13/PEK-c at the same conditions the coefficient is 17.9 pm/V. The SHG signal intensity DR1/PEK-c could maintain more than 80% of its initial value when the temperature was under 100°C, and the SHG signal intensity of the DR13/PEK-c could maintain more than 80% of its initial value when the temperature was under 135°C.

CDW Transition and Instability in Interchain Coupled Organic Ferromagnets with Next-Nearest Neighboring Hopping Interaction

Considering interchain interaction and the intrachain next-nearest neighboring hopping interaction, within the self-consistent-field Hartree-Fock approximation, we deal with two neighboring organic ferromagnetic chains. We also take into account the itineracy of π-electrons, the Hubbard repulsion and antiferromagnetic correlation between π-electrons and side radical electrons. It is shown that there appear two kinds of CDW successively when the next-nearest neighboring hopping interaction is greater than a critical value, which decreases with the interchain coupling. The first CDW is accompanied with bond-order-wave and the second one with no distortion of lattice. The SDW along the main chain is modulated by the CDW. It is also found that the interchain coupling and the next-nearest neighbor hopping integral instabilizes the ferromagnetic ground states.

The Kink Distortion in Quasi-One-Dimensional Conjugated Polymer with a Side Radical

Based on a theoretical model for quasi-one-dimensional polymer, the kink distortion in a π-conjugated carbon chain with a single side radical, which contains an unpaired electron, is investigated. When the hopping integral between the main chain and the side radical is larger than a critical value, there exists a transition from the Peierls dimerization to a solitonlike structure along the main chain. In addition, it is found that the up spin density at the dangling site has been transferred to the main chain, while the down spin density of the main chain is transferred to the side radical due to the hopping mediated interaction between the main chain and side radical.

The pair of soliton-like distortions in organic ferromagnetic conjugated polymers

We study a soliton-like distortion in a quasi-one-dimensional conjugated carbon chain with a single side radical, which contains an unpaired electron, by taking into account the electron–phonon interaction, an extended Hubbard term due to on-site electron–electron interactions and intersite e–e interactions, and the ferromagnetic correlation between itinerant π-electrons and the unpaired radical electron. It is shown that a critical value of hopping integral exists between the side radical and the main chain, at which a transition from a single soliton-like distorted structure to a pair of soliton-like distortions occurs along the main chain. In addition, the spin density at the dangling site is transferred to the main chain due to the hopping interaction between the main chain and the side radical, and the spin density at the side radical is decreased to zero when the hopping integral is larger than the critical value.

Charge density wave transition and instability in interchain coupled organic ferromagnets with next-nearest-neighbor hopping interaction

Considering interchain interaction and the intrachain next-nearest-neighbor hopping interaction, within the self-consistent-field Hartree–Fock approximation, we deal with two neighboring organic ferromagnetic chains. We take into account the π-electrons, the Hubbard repulsion, and antiferromagnetic correlation between π-electrons and side radical electrons. It is shown that there appear to be two kinds of charge density waves successively when the next-nearest-neighbor hopping interaction is greater than a critical value, which decreases with the interchain coupling. The first charge density wave is accompanied by a bond order wave and the second one has no lattice distortion. The spin density wave along the main chain is modulated by the charge density wave. It is also found that the interchain coupling and the next-nearest-neighbor hopping integral destabilizes the ferromagnetic ground states.

Interchain coupling model for quasi-one-dimensional π-conjugated organic ferromagnets

Two neighboring \ensuremath{\pi}-conjugated organic-polymer ferromagnetic chains are described individually by a Hamiltonian, which is the Su-Schrieffer-Heeger Hamiltonian added by the Hubbard electron-electron repulsion. In consideration of the topological structure of the system, the interchain coupling is taken into account as an interchain electron-transfer term, which is different with respect to different sites in chains. The splitting of energy levels with respect to different chains, the ferromagnetic order, and the dimerization are studied in detail. It is shown that in the high-spin ground state of the system, different configurations with interchain coupling will result in transfer of spin density between the main chain and side radical, and appropriate coupling strength stabilizes the high-spin ground state. However, as the coupling reaches a critical value, the energy gap disappears and the high-spin state does not exist. It is also found that the dimerization along the main chain varies with the interchain coupling.

Synthesis of and Ferromagnetic Coupling in Poly(phenylenevinylene)s Bearing Built-in t-Butyl Nitroxides

Abstract Poly[[2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]-1,4- or 1,2-phenylene]vinylene] was synthesized by polymerizing 4- or 2-bromo-2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]styrene with a palladium catalyst, respectively. They were deprotected and chemically oxidized to yield poly(1,4- or 1,2-phenylenevinylene)s bearing a 2- or 4-substituted built-in nitroxide radical. The polyradicals were chemically stable, and their spin concentration was increased to 0.8 spin/unit. A SQUID measurement which included the corresponding diradicals and triradicals indicated that a partial, but strong, intramolecular ferromagnetic coupling was established through the conjugated backbone, despite a spin defect in the side radical moiety, for the poly(1,2- phenylenevinylene) bearing 4-substituted built-in nitroxide radical.

Dielectric relaxation in polydialkoxyphosphazenes

A study has been made of dielectric relaxation in six linear polydialkoxyphosphazene polymers with side methylene chains of differeing length. Transitions associated with localized and segmental forms of molecular motion were found in all the homologues. The results of diffraction investigations show that an increase in the size of the side radical leads to ordered structures appearing at the X-ray and optical levels. It was noted that changes in the temperatures of both transitions as a function of the size of side radicals differ from those occurring in organic polymers. This is associated with properties of the inorganic backbone of polydialkoxyphosphazenes.

Electronic structure, conformation and reactivity of active centres of anionic polymerization with an aluminium counterion

The quantum-chemical CNDO/2 method was used in connection with the anionic polymerization of unsaturated compounds initiated by organoaluminium compounds. Comparison of the results for model compounds Al(XH n) 3 H 2AlXHP n (X = O, N, C) with the data for analogous lithium and magnesium derivatives showed that the polarity of the MtX bond (calculated taking account of the metal valency) and the order of this bond are reactivity indices. According to these indices, amido- and alkoxy-alkylaluminium derivatives should be reactive in initiation. Absent of activity for the alkoxy derivatives is probably due to the stability of their aggregates. The optimization of the geometry of the molecule CH 3CH(COOCH 3)AlH 2, modelling the propagation active centre, showed that, as a result of the competing interaction of the Al atom with the growing chain and the side radical, the AlC bond is greatly weakened. Its reactivity evaluated from the above mentioned indices exceeds that of alkylaluminium amide initiators. The geometry of the complex of the model compound, CH 3AlH 2, with the methyl acrylate molecule was favourable for the subsequent insertion of the monomer into the chain. Possible reasons for the discrepancy between the experimental and calculated data are considered for acrylonitrile.

Polarized luminescence as used for analyses of high frequency twisting vibrations in macromolecules

Theoretical correlations for degrees of luminescence polarization have been analysed for different models of inhibited internal rotation and twisting vibrations. It was found that average amplitudes can be determined for high-frequency twisting vibrations (HTV) in the main chain and in side radicals by means of the polarized luminescence of “labelled” macromolecules with luminescing groups (LG). The HTV amplitudes were found by comparing theoretical considerations with experimental findings. The HTV amplitudes depend on interactions between the anthracene nucleus and the macromolecular units nearest to the LG, and likewise on the length and flexibility of the side radical containing the LG. Matters relating to these correlations are discussed.

Pressure Viscosity Characteristics of a Series of Siloxane Fluids

The viscosity-pressure-temperature behavior of a series of 14 siloxane polymers is reported. The series of fluids includes a range of degree of polymerization and of size and nature of side radicals. The variations span the range of siloxane fluids currently available and considered as possible lubricants. The major conclusion is that the pressure viscosity coefficient considered important to elastohydrodynamic lubrication is only influenced by changing the nature of the side radical and not by the degree of polymerization or the size of alkyl side groups on the siloxane chain.

Rheological properties of comb-like polyalkylacrylates and polyalkylmethacrylates

A study was made of the viscosities of polyalkylacrylate (PA) and polyalkylmethacrylate (PMA) melts containing 4 to 18 carbon atoms in the side chain. It was shown that with an increase in the length of side branches, viscosity and any anomaly in viscosity in homologous series markedly decreases, the viscosity of polymers with the same side radical being higher for PMA, compared with PA. The activation energy of viscous flow E decreases with an increase in the length of the side radical. The maximum corresponds to the first members of the series—polymethylmethacrylate and polymethylacrylate. The value of E for polymers with long alkyl side radicals is equal to the value of E of polypropylene, in contrast to the poly-α-olefin series, for which E corresponds to E of linear polyethylene for higher homologues. It was found that PA and PMA with long side branches capable of being crystallized may flow at temperatures somewhat lower than melting point. The formation of discontinuities is a typical feature of flow curves in this case. It was shown that the formation of this discontinuity is due to the breakdown of crystalline structure of the polymer.

Hydrodynamic and optical properties of polyvinylstearate molecules in solution

The viscosity, light-scattering, diffusion, sedimentation and flow birefringence of polyvinylstearate (PVS) solutions were investigated. The optical anistropy and thermodynamic rigidity of the molecular chains of PVS have been determined. A regular rise in the equilibrium rigidity of the main chain accompanying lengthening of the side radical has been confirmed by comparing the properties of PVS with those of other vinyl polymers.

The effect of the method of preparation and the size of the side radical on the viscometric properties of polyarylates

The effect of the method of preparation and the size of the side radical on the viscometric properties of polyarylates

Clinical trial of tetrahydrozoline hydrochloride; a valuable new nasal decongestant.

This report presents details of a clinical trial of tetrahydrozoline hydrochloride (Tyzine), a new sympathomimetic agent useful in 0.1% aqueous solution as a topical vasoconstrictor and nasal decongestant. The effectiveness of tetrahydrozoline, as measured by its promptness of action, degree of relief provided, and the percentage of patients benefited, is superior. The decongestive action of tetrahydrozoline is notably prolonged, so that instillations every four to eight hours, or at longer intervals in some cases, are sufficient to maintain continuous relief; instillation at bedtime provides relief that carries through the night. Tetrahydrozoline is also free of both local and systemic side-effects. BACKGROUND Pharmacologic tests with tetrahydrozoline, which is designated chemically as 2-(1,2,3, 4-tetrahydro-1-naphthyl) imidazoline hydrochloride, suggested that this recently synthesized compound should prove highly effective and free of the disadvantages of its predecessors. The structural formula of tetrahydrozoline is as follows: Tetrahydrozoline consists structurally of an aromatic nucleus and a side radical