Thermodynamics of surfactant-dye complex formation in aqueous solutions. Sodium alkyl sulfates and azo oil dye systems

Thermodynamics of surfactant-dye complex formation have been studied, in terms of equilibrium coefficient, using a spectrophotometer. The systems are 6 sodium alkyl sulfates, which have different alkyl chain lengths, and 4-phenylazo-1-naphthylamine. A pronounced spectral change in the dye solution occurs on addition of the surfactant; the change has a definite isosbestic point and a new absorption band at 535 nm because of surfactant-dye complex formation, which is caused by hydrophilic-hydrophilic interaction. As the alkyl chain length in the surfactant increases, the values of free energy change (negative) increase, while the value of enthalpy change (negative) increases and the value of entropy change (positive) decreases. The longer the alkyl chain length in surfactant increase, the more stable the surfactant-dye complex becomes.Surfactant-dye complex will form due to hydrophilic-hydrophilic interaction and will become more stable due to hydrophobic-hydrophobic interaction.     

Sodium borosilicate glasses prepared by the sol-gel process

A sodium borosilicate gel of composition 80SiO₂·15B₂O₃·5Na₂O (wt%) was prepared from tetraethyl orthosilicate, trimethyl borate, sodium methylate, H₂O, and HCl as the catalyst. Variation of specific surface area and porosity as a function of heating temperature indicated that closed pores were opened at temperatures lower than 400°C and collapsed above 450°C. From TG and DTA curves, about 19% Si and B atoms are evaluated to have −OH bonds. X-ray diffraction patterns indicated crystallization of low-cristobalite out of the gel when it was heated at 700°C for 5 h, showing a difference from a melt-quenched glass of the same composition.     

Effect of hydrogen bonds on gelation by introduction of carboxyl groups in the free‐radical crosslinking copolymerization of butyl methacrylate with 1,6‐hexanediol dimethacrylate

The preliminary study of the effect of physical crosslinking on the gelation in monovinyl/divinyl copolymerizations is described. Thus, mono(2‐methacryloyloxyethyl) succinate was added to the crosslinking copolymerization of butyl methacrylate with 1,6‐hexanediol dimethacrylate and the gelation was explored in terms of the effect of hydrogen bonds formed between carboxyl groups introduced into the primary polymer chain.     

Effects of band structure and matrix element on RKKY interaction

The effects of band structure and matrix elements on the RKKY interaction J(R) are separately investigated. When the Fermi surface has planes perpendicular to R, effects appear on the period of oscillation, the phase shift and the amplitude of J(R). The applicable region of the asymptotic form for large R and the validity of the free electron approximation are also examined. If there are no tangential planes perpendicular to R, it is found that: 1) when two interacting localized spins are on lattice points in the crystal, exponential damping appears even for the constant matrix element model and the matrix element effects introduce competing terms causing a sign change; 2) when one of the spins is at an interstitial position, the constant matrix model gives a weaker J(R) ∝ R^-2 damping, but the character of this term changes into the exponential damping by taking into account matrix elements.     

Vacuum ion source diagnostics at the Tokyo Institute of Technology

After a brief review of various diagnostics for vacuum ion sources measured data are presented for the particle distributions within the anode/cathode gap regions using passive spectroscopy, active laser interferometry, and resonant laser-induced fluorescence, while the extracted ion beams were observed by particle track detectors of both time-integrated and time-resolved types. Also measured were the prompt gamma-rays and the D-D neutrons when the beams hit the targets. The experimental arrangements of these diagnostics, together with some examples of the typical results obtained, are shown. It is discussed how various kinds of particles were distributed within the ion diodes, and how they were extracted from the source regions     

Concerted and sequential Coulomb explosion processes of N2O in intense laser fields by coincidence momentum imaging

The Coulomb explosion dynamics of N2O in intense laser fields (800 nm, 60 fs, approximately 0.16 PWcm2) is studied by the coincidence momentum imaging method. From the momentum correlation maps obtained for the three-body fragmentation pathway, N2O3+-->N++N++O+, the ultrafast structural deformation dynamics of N2O prior to the Coulomb explosion is extracted. It is revealed that the internuclear N-N and N-O distances stretch simultaneously as the bond angle less than approximately N-N-O decreases. In addition, two curved thin distributions are identified in the momentum correlation maps, and are interpreted well as those originating from the sequential dissociation pathway, N2O3+-->N++NO2+-->N++N++O+.     

Micrometer-sized graphitic balls produced together with single-wall carbon nanohorns

We present in this report a new type of particles with micrometer-order sizes, which we called giant graphitic balls (GG balls). The GG balls are produced by CO2 laser ablation of graphite together with single-wall carbon nanohorns. They have graphitic structures whose layers tend to align parallel with the GG-ball surfaces, resulting in polygonal-like arrangements. Comparing the GG-ball structure with that of the previously reported polygonal graphite-particles, the growth mechanism of the GG ball is discussed briefly.     

Simultaneous measurements of endogenous and deuterium-labelled tracer variants of androstenedione and testosterone by capillary gas chromatography-mass spectrometry

A capillary gas chromatographic-mass spectrometric method for the simultaneous determination of androstenedione and testosterone in human plasma using [19,19,19-2H3]androstenedione and [19,19,19-2H3]testosterone as internal standards is described. For calculation of plasma androstenedione and testosterone, peak heights were measured by selected-ion monitoring of the molecular ions of the heptafluorobutyryl derivatives of androstenedione and [2H3]androstenedione (m/z 482 and 485) and of testosterone and [2H3]testosterone (m/z 680 and 683). The isotope dilution method needed no complex corrections for contributions and provides a sensitive and reliable technique with good accuracy, precision and reproducibility.