Equilibrium and stationary nonequilibrium states in a chain of colliding harmonic oscillators

Equilibrium and nonequilibrium properties of a chain of colliding harmonic oscillators (ding-dong model) are investigated. Our chain is modeled as harmonically bounded particles that can only interact with neighboring particles by hard-core interaction. Between the collisions, particles are just independent harmonic oscillators. We are especially interested in the stationary nonequilibrium state of the ding-dong model coupled with two stochastic heat reservoirs (not thermostated) at the ends, whose temperature is different. We check the Gallavotti-Cohen fluctuation theorem [G. Gallavoti and E. G. D. Cohen, Phys. Rev. Lett. 74, 2694 (1995)] and also the Evans-Searles identity [D. Evans and D. Searles, Phys. Rev. E. 50, 1994 (1994)] numerically. It is verified that the former theorem is satisfied for this system, although the system is not a thermostated system.     

99Ru Mössbauer spectroscopic study on salts of ruthenocene with halogens

⁹⁹Ru Mössbauer spectra at 5 K have been measured on samples of salts of ruthenocene with halogens, expressed as [Ru(C₅H₅)₂X]Y (X=Cl, Br, Y=PF₆, and X=1, Y=13). The values of both the isomer shift and the quadrupole splitting of these salts with halogens are larger compared to those of ruthenocene. It is concluded that ruthenocene gives salts having direct chemical bonding between Ru and Cl, Br, or I, and that the Ru atom in each salt is in a higher oxidation state than 2+ in ruthenocene.     

Emulsion polymerization of styrene under high pressure

Summary The emulsion polymerization of styrene was studied at 40 °C over a pressure range of 1 to 1000 bar. By measuring the ratio of the overall reaction rate under high pressure and at atmospheric pressure, the activation volume for the prouagation was obtained as –23.5 cm³/mol which was rather smaller than the literature values. The underestimation by the method of emulsion polymerization would be due to the character of polymerization processes and the emulsion polymerization method is not appropriate to determine the accurate value of the activation volume of propagation reactions.

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Zusammenfassung Es wird die Emulsionspolymerisation von Styrol bei 40 °C über den Druckbereich von 1 bis 1000 bar untersucht. Durch Messung des Verhältnisses der Reaktionsgeschwindigkeit unter hohem Druck und bei Atmosphärendruck wurde das Aktivierungsvolumen für die Ausbreitungsgeschwindigkeit zu –23,5 cm³/mol gefunden, ein Werr, der ziemlich kleiner als die Literaturwerte ist, Die Unterschätzung bei der Methode der Emulsionspolymerisation dürfte dem Charakter des Polymerisationsprozesses zuzuschreiben sein, und die Emulsionspolymerisation ist nicht geeignet, den exakten Wer für das Aktivierungsvolumen zu erhalten.

     

A hexapeptide motif that electrostatically binds to the surface of titanium

A hexapeptide motif, RKLPDA, that recognizes the surface of titanium was identified from a peptide phage selection. Mutational analyses showed electrostatic interaction was a major factor in the binding, paving a new way to modify the surface of Ti with active biomolecules.     

Formation of low-symmetric 2D superlattices of gold nanoparticles through surface modification by acid-base interaction

In the present work, a novel method was developed for the fabrication of 2D superlattices with different symmetries. Same-surface amino-functionalized Au nanoparticles as building blocks were self-assembled to form different 2D superlattices using surface modification with organic acids. The 2D superlattices of quasi-honeycomb and square structures were obtained by neutralizing amino-functionalized Au nanoparticles with 1,3,5-tribenzenecarboxylic acid and acetic acid, respectively. These results strongly suggest that the different types of 2D or 3D superlattices can be constructed by simple addition of proper acid to nanoparticles functionalized with amino groups. This method will allow us to obtain various desired metal superlattices without fully synthesizing the ligands.     

Reactions of the monoxides of 2,6-disubstituted pyrazines with phosphoryl chloride and acetic anhydride

The monoxides of 2, 6-dimethyl-( 1 ), 2, 6-diphenyl-( 2 ), and 2-methyl-6-phenylpyrazines ( 3 ) were subjected to the reactions with phosphoryl chloride and acetic anhydride. Some reactions of the chloropyrazines and hydroxypyrazines obtained thus were also investigated.     

Spectrofluorimetric determination of triethylenethiophosphoramide in blood

The method is based on a reaction of the ethyleneimine group with sodium sulfide, taurine and o-phthalaldehyde to give a fluorescent product. Triethylenethiophosphoramide (thioTEPA) can be determined in the range 9.4–945 ng in 100 μl of 1-propanol with a relative standard deviation of 2.3–4.7%. The method is applied to the determination of thioTEPA in rabbit blood plasma. The use of Extrelut 3 proved to be efficient for the clean-up of thioTEPA in plasma samples.     

Valence-delocalization of the mixed-valence oxo-centered trinuclear iron propionates [Fe 2 III FeIIO(C2H5CO2)6(py)3]npy;n=0, 1.5

Mixed-valence trinuclear iron propionates [Fe ₂ ^III Fe^IIO(C₂H₅CO₂)₆(py)₃]npy, wheren=0, 1.5, were synthesized and the structure of the pyridine-solvated complex was determined by single-crystal X-ray diffraction. Mössbauer spectra of the solvated propionate complex showed a temperature-dependent mixed-valence state related to phase transitions, reaching an almost delocalized valence state at room temperature. On the other hand, the non-solvated propionate showed a remarkable change of the spectral shape related to a phase transition, remaining in a localized valence state at higher temperatures up to room temperature.