Interaction of polyvinylpyrrolidone with methyl orange and its homologs in aqueous solution: Thermodynamics of the binding equilibria and their temperature dependences

The interaction of polyvinylpyrrolidone with methyl orange, ethyl orange, propyl orange, and butyl orange has been studied by an equilibrium dialysis method at 5, 15, 25, and 35°C. The first binding constants and the thermodynamic parameters in the course of the binding have been calculated. It was found that the free energy and the enthalpy changes are all negative and the entropy change is largely positive. The longer the alkyl chain of the dyes, the more positive is the enthalpy change (though it is always in the negative direction) and hence the larger is the entropy change. The favorable free energy of the binding of butyl orange observed for the formation of the dye–polymer complex seems to be a result of a favorable entropy change rather than any favorable enthalpy change. Temperature dependences of the thermodynamic functions were apparently observed. That is, ΔF and ΔH become larger in absolute magnitude as the temperature increases. The positive quantity of ΔS tends to decrease with increasing temperture. All these facts obtained can be interpreted satisfactorily by the hydrophobic interaction between hydrocarbon portions of the dyes and nonpolar parts of the macromolecule.     

PHYTOCHROME-MEDIATED PHOTOTROPISM IN Adiantum PROTONEMATA-I. PHOTOTROPISM AS A FUNCTION OF THE LATERAL Pfr GRADIENT*

Abstract— Phytochrome-mediated phototropism of the protonema of the fern Adiantum capillus-veneris was studied in view of the hypothesis that phototropism is controlled by the gradient of Pfr (phytochrome in the far-red-absorbing form) across the short axis of the protonema. Fluence-response relationships were investigated using a microbeam irradiation technique that allowed simultaneous stimulation of the two sides of the subapical portion of the protonema with different fluences of red light. Mathematical models describing the tropic response as a function of fluence were derived from the hypothesis in consideration of the minimal phototransformation kinetics of phytochrome. and the fitness of the functions to the experimental data was examined. The analytical results were then evaluated in view of the photochemical properties of phytochrome known from the literature. It is concluded that the extent of the tropic response is determined by the difference in the Pfr concentrations between the two sides of the protonemal cell. It is further suggested that, even if phytochrome exists as a dimer in vivo, the physiological unit of phytochrome is the monomer.     

Determination of cadmium and bismuth in high-purity zinc metal by inductively coupled plasma mass spectrometry with on-line matrix separation

Traces of cadmium and bismuth in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of the potassium iodide (KI) system was applied to the separation of the analytes from the matrix zinc. The analytes, cadmium and bismuth, were adsorbed on the anion-exchange (BIORAD AG1-X8) mini-column (1.0 mm i.d.× 100 mm bed length), while the matrix zinc can be completely removed from the anion-exchange resin. The analytes were eluted by 2 mol/l HNO₃ and directly introduced into the ICP-MS. The detection limits (D.L.) obtained by using a single injection (350 l) were 0.81 and 0.075 ngg^-1 for cadmium and bismuth, respectively. In the case of multi-injection concentration onto the anion-exchange mini-column (five injections 350 l each), the detection limits could be improved to 0.16 and 0.014 ngg^-1 for cadmium and bismuth, respectively. The reproducibilities of the single injection and the multi-injection method were satisfactory with a relative standard deviation of less than 5% (at the 10 and 1 ngml^-1 level for the single injection and the multi-injection method, respectively). The method was successfully applied to the determination of trace impurities in four samples of high-purity zinc metal (7 nines grade) and three standard reference materials of high-purity unalloyed zinc samples (from NIST).     

Interaction of crosslinked polyvinylpyrrolidone with a homologous series of methyl orange derivatives in aqueous and nonaqueous solutions: Thermodynamics of the binding equilibria

The extent of binding of methvI orange, ethyl orange, propyl orange, and butyl orange by crosslinked polyvinylpyrrolidone was measured in all aqueous Solution. The first binding constants and the thermodynamic parameters accompanying the binding were evaluated. These values were compared with those of water-soluble polyvinylpyrrolidone. The first binding constant, the absolute magnitude of ΔF°, and the value of ΔS° of the crosslinked polyvinylpyrrolidone are substantially larger than those of the water-soluble product for any particular dye. These behaviors can be accounted for in terms of increased hydrophobic domains in the former and enhanced hydrophobic contribution in the binding process. Also the binding of the dye by the crosslinked polymer in a nonaqueous solvent, ethylene glycol, was measured to assess the contribution of hydrophobic interaction to the dye-polymer complex formation in aqueous medium. It was found that the binding of butyl orange by the crosslinked polymer is suppressed in ethylene glycol and the contribution of entropy term to the free energy change in the aqueous environment is large compared with that in ethylene glycol. The significance of the hydrophobic of the hydrophobic interaction in the dye-polymer association process is described.     

Usefulness of bone imaging in diagnosis of sternocostoclavicular hyperostosis

Sternocostoclavicular hyperostosis (SCCH) is a rare disease that is characterized by hyperostosis and soft tissue ossification between the clavicles and the anterior part of the upper ribs. There have been few published reports of 99mTc-MDP bone imaging findings in this disease. Thirty-three patients who were suspected to have SCCH were studied with 99mTc-MDP bone imaging. Bone images were abnormal in 31 (94%) of 33 patients. Chest radiographs were available in 30 patients, but negative in 14 (46%) of them. Bone imaging revealed also radionuclide accumulations in other bones such as the vertebrae, femur or sacroiliac joints in ten (14 sites) of 33 cases. Bone scintigraphy was useful in the diagnosis of sternoclavicular hyperostosis.     

Remarkable stereocontrol observed in the ring formation by intramolecular hosomi-sakurai reaction

The cyclization of 2-(3′,4′-dimethyl6?′-trimethylsilyl-4′-hexenyl)-2-cyclohexenone with TiCl₄, afforded stereospecifically 6α,7α-dimethyl-6β-vinyl-5βH-1-decalone derivative and the two-fold diastereoselection involved is reasoned in terms of orientation control and folding strain control.     

Interaction of α-poly-L-lysine and ε-poly-L-lysine with methyl orange and its homologs in aqueous solution: Results from dialysis and spectroscopic measurements

The interaction of α-poly-L -lysine and ε-poly-L -lysine with methyl and ethyl orange was studied by equilibrium dialysis and spectroscopic methods. The results of the dialysis measurements indicated that the extent of binding by ε-polypeptide is substantially higher than that by α-polypeptide, despite the much greater molecular weight of the latter. This difference in binding affinity was interpreted in terms of the increased conformational adaptability of ε-polypeptide because of its highly flexible structure. Furthermore, ε-polypeptide exhibited strong cooperative binding. In addition, the effect of the successive addition of α- and ε-polypeptides on the absorption spectra of methyl and ethyl orange was investigated. The addition of α-polypeptide with a molecular weight of 400,000 produced a new absorption peak at a shorter wavelength, due to the stacked dye molecules on the polypeptide chain, whereas that of ε-polypeptide did not. From the results of spectroscopic measurements a possible mode of interaction between these two polypeptides and the small molecule is discussed.     

Simultaneous Measurement of Refractive Index and Thickness of Transparent Plates by Low Coherence Interferometry

We demonstrate a novel low coherence Michelson interferometer which can provide simultaneous measurement of the refractive index and thickness of transparent plates used as a measured object. Unlike the existing low coherence interferometers reported so far, either an object or a focusing lens aligned on the signal arm is scanned repeatedly by a precise translation stage in synchronization with movement of a reflection mirror on the reference arm. The so-called object or lens scanning method gives us two measured quantities a movement distance of the stage between two light focusing states on the front and rear planes of an object and the corresponding optical path difference. These two measured quantities, result in desirable values of the index and thickness of the object with a short calculation. The measurement accuracy of ≤0.1% is expected for a thickness of more than 1 mm. In the experiment using the object scanning method, the accuracy of 0.3% or less was successfully attained for nearly 1-mm thick plates of fused quartz, sapphire, LiTaO₃ and slide glass.     

Modification of Tencel with Treatment of Ferric Sodium Tartrate Complex Solution I. Effect of Treatment Condition

Partial dissolution of cellulose by ferric sodium tartrate complex (FeTNa) solution was examined as refining treatment of the organic-solvent spun cellulose fiber (Tencel). The treatment conditions were discussed in terms of solvent strength, temperature, duration of the treatment, and free NaOH concentration by measuring the weight loss, crystallinity, and tenacity of the resultant yarns. For improving fibrillation resistance, the optimized solution of the FeTNa complex was composed of 1–1.5M FeCl₃ with 20% excess sodium tartrate and 1 N free NaOH, and the duration of the treatment was 60 min at 20°C. The loss in weight and tenacity could be maintained as low as 5% and 30–40%, respectively, by the optimized conditions. The resulting yarn showed significantly improved fibrillation resistance.     

Cation-sensitive fluorescence of anionic polymers bearing naphtho-18-crown-6 units

Changes in the fluorescence intensity of anionic polymers bearing naphtho-18-crown-6 moieties on addition of cations were studied in water at 30 °C. On addition of alkali metal cations, the fluorescence intensity of the polymers decreased sharply for Tl⁺ less for Cs⁺ and little for Li⁺, K⁺ and Rb⁺. On addition of alkaline earth metal cations, Ba²⁺ caused the strongest decrease of the fluorescence intensity of the polymers. The decrease of the fluorescence intensity of the polymers was suggested to be caused by the external heavy-atom effect of the cations bound to the cavity of the crowned naphthalene moiety. The content of the crowned naphthalene units in the polymers affected the cation-dependent fluorescence change. The fluorescence change of the polymers based on the cation complexation competition was also studied.