NDMAP: the best material to study the Haldane's prediction

As predicted by Haldane, spin, S=1 one-dimensional (1D) Heisenberg antiferromagnet (HAF) has an energy gap between the singlet ground state and first excited triplet. On application of magnetic field, the triplet state Zeeman splits and the energy of one of the triplet state becomes zero at a critical field, H_c. Above H_c the system recovers magnetism. Then, we expect that a quasi-1D HAF will show a magnetic long-range ordering (LRO) at low temperatures due to the inter-chain coupling. This field-induced LRO has not been observed before due to complication of the crystal structure in the materials studied so far and/or technical difficulty.From a heat capacity measurement on a single crystal of an S=1 quasi-Q1D HAF, Ni(C₅H₁₄N₂)₂N₃(PF₆), we found an anomaly at a temperature in finite fields indicating a field-induced phase transition. A magnetic LRO is confirmed by a neutron diffraction measurement on the same sample. The temperature versus magnetic field phase diagram of this compound is constructed and discussed.     

Thermodynamic mixing properties of liquids in the system Na2O-SiO2

Enthalpies of fusion have been measured by differential scanning calorimetry for a Na₂O-SiO₂ system at 50, 66.6, and 74.4 mol% SiO₂. Enthalpies of mixing of liquids obtained from different calorimetry techniques are critically evaluated. The data on calorimetric enthalpy, activity of Na₂O, cristobalite liquidus, and immiscibility gap are used to determine the enthalpy and entropy of mixing of sodium-silicate liquids are determined as a function of composition by the least squares method. The derived mixing properties are based only on the experimental data and are independent of any assumption about the structure and chemical species in liquids. The enthalpy of mixing has a minimum value of −120 kJ/mol at 35-40 mol% SiO₂ and is convex upward around 80-90 mol% SiO₂. The entropy of mixing have a maximum value of + 6 J/K-mol at 75 mol% SiO₂, and it decreases with the SiO₂ content to −5 J/K-mol at 40 mol% SiO₂. This decrease in entropy can be accounted for by ideal mixing of Q⁴, Q³, and Q^{0 + 1 + 2} (= Q⁰ + Q¹ + Q²) species in the liquids and is responsible for the negative temperature dependence of the partial molar Gibbs energy of mixing of Na₂O, observed in activity measurements. Comparison of the present results with previous values suggests that a quasi-chemical model and the Adam-Gibbs model overestimate the configurational entropy of mixing of liquids.     

Removal of phosphate by aluminum oxide hydroxide

The development and manufacture of an adsorbent to remove phosphate ion for the prevention of eutrophication in lakes are very important. The characteristics of phosphate adsorption onto aluminum oxide hydroxide were investigated to estimate the adsorption isotherms, the rate of adsorption, and the selectivity of adsorption. Phosphate was easily adsorbed onto aluminum oxide hydroxide, because of the hydroxyl groups. The adsorption of phosphate onto aluminum oxide hydroxide was influenced by pH in solution: the amount adsorbed was greatest at pH 4, ranging with pH from 2 to 9. The optimum pH for phosphate removal by aluminum oxide hydroxide is 4. The selectivity of phosphate adsorption onto aluminum oxide hydroxide was evaluated based on the amount of phosphate ion adsorbed onto aluminum oxide hydroxide from several anion complex solutions. It is phosphate that aluminum oxide hydroxide can selectively adsorb. The selectivity of phosphate onto aluminum oxide hydroxide was about 7000 times that of chloride. This result indicated that the hydroxyl groups on aluminum oxide hydroxide have selective adsorptivity for phosphate and could be used for the removal of phosphate from seawater.     

Ultrafast Encapsulation of Metal Nanoclusters into MFI Zeolite in the Course of Its Crystallization: Catalytic Application for Propane Dehydrogenation

Encapsulating metal nanoclusters into zeolites combines the superior catalytic activity of the nanoclusters with high stability and unique shape selectivity of the crystalline microporous materials. The preparation of such bifunctional catalysts, however, is often restricted by the mismatching in time scale between the fast formation of nanoclusters and the slow crystallization of zeolites. We herein demonstrate a novel strategy to overcome the mismatching issue, in which the crystallization of zeolites is expedited so as to synchronize it with the rapid formation of nanoclusters. The concept was demonstrated by confining Pt and Sn nanoclusters into a ZSM-5 (MFI) zeolite in the course of its crystallization, leading to an ultrafast, in situ encapsulation within just 5 min. The Pt/Sn-ZSM-5 exhibited exceptional activity and selectivity with stability in the dehydrogenation of propane to propene. This method of ultrafast encapsulation opens up a new avenue for designing and synthesizing composite zeolitic materials with structural and compositional complexity.     

FEM calculation and the effects of hydrogen diffusion in fabrication processes of long-period fiber gratings

The wavelength shift of a long-period fiber grating (LPG) related to re-distribution of hydrogen molecules was studied by the finite-element method (FEM) calculation and by the experiment. The FEM calculation was performed solving a diffusion equation of hydrogen in glass fiber, and the wavelength of an LPG was calculated. In the experiment, the hydrogen-loaded fiber was out-diffused before laser exposure, and the resonance wavelengths of LPGs fabricated by exposure were measured. The wavelength depended on the duration of out-diffusion, and the variation was up to 114 nm. The FEM calculation considering the hydrogen re-distribution by out-diffusion agreed with the experiment. After the laser exposure, the wavelength of an LPG shifted towards the long wavelength without any exposure. The FEM calculation assuming hydrogen depletion in the core and its recovery agreed with the measured wavelength shift. Extension of the FEM to fibers with more complicated structures has been discussed.     

Separation of V(V)-4-(2-pyridylazo)resorcinolato complex from a large excess reagent using an ODS cartridge for high-performance liquid chromatography.

A selective off-line preconcentration technique for the V(V) complex with 4-(2-pyridylazo)resorcinol has been developed and successfully applied to the determination of V(V) in an air-borne sample. The target complex was separated from excess reagent using an ODS cartridge and water as the eluent. The complex was then concentrated on another ODS cartridge using tetrabutylammonium bromide and eluted with methanol; the eluate was applied to a one-drop concentration/HPLC. A detection limit as low as (6.05 +/- 0.82)x 10(-11) M (5 ppt) was achieved.     

Die Löslichkeit von aromatischen Verbindungen mit polaren Gruppen in Wasser

Zusammenfassung Die Löslichkeiten folgender Verbindungen wurden in Wasser bei 5°-Intervallen von 0° bis 40° bestimmt; Anilin, Mtrobenzol, Chlorbenzol,-Oxynaphthalin und-Nitronaphthalin. Aus diesen Ergebnissen wurden die thermodynamischen Parameter für den Lösungsprozeß der reinen flüssigen Verbindungen in Wasser berechnet. Das Resultat wurde mit Hilfe des Begriffs der Eisberge erklärt.Beim Benzol, Anilin und Chlorbenzol waren die Lösungswärmen negativ bei niedrigeren Temperaturen und wurden mit steigender Temperatur positiver. Dagegen traten beim Nitrobenzol,-Oxynaphthalin und-Nitronaphthalin stets die positiven Lösungswärmen auf. Dies sollte auf die großen intermolekularen Kräfte in der reinen Flüssigkeit zurückzuführen sein.     

Classical and quantum mechanical aspects of time-dependent Hartree-Fock trajectories

In terms of a quantum mechanical representation based on Slater determinants, classical and quantum mechanical aspects of TDHF trajectories are investigated. The invariant integration measure of the determinantal representation is obtained in a general closed form. Phase space structures of the TDHF equation and its solutions are discussed on this basis. The formal classical structures provide a way of finding a semiclassical expression for the quantum mechanical propagator, into which the superposition principle among TDHF trajectories is incorporated. General properties of the semiclassical propagator such as the time translation/reversal symmetry, unitarity, etc., are studied. Two simple hamiltonian systems are employed as examples which exhibit analytical solutions for the propagator. To illustrate the effects of superposition of TDHF paths, a system of interacting two-level nuclei is numerically studied and a comparison with the exact result is made.     

Photoelectron spectra and sum rule consideration: Effect of chlorine substitution on ionization energies for chloroethanes,chloroacetaldehydes and chloroacetyl chlorides

He(I) photoelectron spectra are reported for various series of chlorine-substituted compounds: (a) CH₃CH_3?mCl_m, (b) CH_3?mCl_mCCl₃, (c) CH_3?mCl_mCHO and (d) CH_3?mCl_mCOCl, where m = 1, 2 and 3. In each series it is shown that the total sum of vertical ionization energies over all p-type localized molecular orbitals (LO's) has an excellent linear relationship to the number of substituted chlorine atoms. The differences in the total orbital energy sum by successive chlorine substitutions are found to be 26.7 eV for series a and b and 27.2 eV for series c and d, yielding the corresponding experimental σ_CCl, energies useful for sum rule considerations. The photoelectron spectra of the chloro compounds studied are interpreted with the help of the sum rule as well as CNDO/2 calculations. Orbital correlation diagrams have been constructed for these compounds.