Analysis of ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide

An NMR method for the analysis of the ethylene oxide sequence of the acetal copolymer from trioxane and ethylene oxide has not yet been established. We found three novel cyclic compounds composed of 1 mol of ethyelene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different ¹H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that have one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the ¹H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequence by the ¹H NMR method for the copolymer from trioxane and ethylene oxide. Good agreement was observed between the ¹H NMR method and the hydrolysis method for the analysis of the ethylene oxide sequences. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3239–3245, 2001     

High-Sensitivity Two-Dimensional Observation of Thermal Birefringence Compensation in Laser-Diode Pumped Nd: Glass Laser Rods

We measured the two-dimensional birefringence compensation in laser-diode (LD) pumped Nd:glass (HAP4) laser rods with a high-sensitivity polarimeter. The compensation was performed by inserting a 90° quartz rotator between two identical LD pumped Nd:glass rods with conductive cooling. A considerable reduction of birefringence loss from 9.8% to less than 0.9% after compensation was observed.     

Ionic diffusion and structural changes in lithium compounds

⁷Li NMR measurements have been performed to study milling effects on ionic diffusion in lithium cobalt oxide, LiCoO₂ and piezoelectric compound, LiNbO₃ prepared by mechanical milling method. The milling process gives quite different effects on NMR spectra of these compounds. Both ⁷Li MAS and static NMR spectra of the milled LiCoO₂ show the line broadening with increasing milling time. ⁵⁹Co static spectra also show specific changes in the line shape with increasing milling time. These results would be attributed to the change in an electronic state of Co 3d orbitals because of charge compensation associated with oxygen vacancies and/or defects. ⁷Li static NMR spectrum of milled LiNbO₃ shows complicated line shape with increasing milling time. It is explained by superposition of two spectra arising from mobile Li⁺ ions and non-mobile ones settled on the fixed site. It is shown that the ratio of mobile Li⁺ ions increases up to a maximum of 9.4% with increasing milling time. Milling effects on the Li⁺ ionic diffusion in LiCoO₂ and LiNbO₃ are discussed in connection with changes in local structure.     

0.85-PW, 33-fs Ti:sapphire laser

We have successfully produced a laser pulse with a peak power of 0.85 PW for a pulse duration of 33 fs in a four-stage Ti:sapphire amplifier chain based on chirped-pulse amplification. To our knowledge this result represents the highest peak power pulses yet produced in any Ti:sapphire chirped-pulse amplification system.     

Quantitative elucidation of macrocyclic effect on extraction-ability and -selectivity. Benzo-18-crown-6 and its open-ring analog 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene–alkali metal picrate systems

The constants of overall extraction equilibrium (K_ex) and partition (K_D,MLA) for various diluents and aqueous ion-pair formation (K_MLA) of alkali metal (Li–Cs) picrate (MA) 1:1:1 complexes (MLA) with benzo-18-crown-6 (B18C6) and its open-ring analogue 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (AC·B18C6) were determined at 25 °C, L being B18C6 or AC·B18C6; the distribution constants of AC·B18C6 were measured at 25 °C. The partition behavior of AC·B18C6 and the MLA complexes closely obeys regular solution theory, omitting chloroform; the molar volumes and the solubility parameters of AC·B18C6 and the MLA complexes were determined. The extraction selectivities of AC·B18C6 and B18C6 for the alkali metal picrates increase in the order Li < Na < Cs < K or Rb < or ≈ Rb or K and Li  Na < Cs < Rb < K, respectively. The extraction selectivity of B18C6 for neighboring alkali metal ions in the periodic table is superior to that of AC·B18C6. The macrocyclic effect on the extraction-ability and -selectivity was quantitatively elucidated by the four fundamental equilibrium constants.     

Combined anion-exchange separation and spectrophotometric determination of traces of titanium in sea water

Summary Traces of titanium in sea water have been preconcentrated by anion-exchange from acidified samples in the presence of thiocyanate. Titanium adsorbs strongly on a column of Amberlite CG 400 (SCN^–) and can be stripped easily by elution with 2 M hydrochloric acid — 1.5% hydrogen peroxide solution. Titanium in the effluent is determined spectrophotometrically with diantipyrylmethane as colour reagent. The combined method allows to determine traces of titanium very selectively and sensitively in sea water as well as non-saline water on a 41 sample basis. The method yields a coefficient of variation of 7% at a titanium level of 0.4 g per l.

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Kombinierte Anionenaustauscher-Trennung und spektralphotometrische Bestimmung von Titanspuren in Meerwasser

Zusammenfassung Titanspuren wurden in Gegenwart von Thiocyanat durch Anionenaustausch aus der angesäuerten Probe angereichert. Titan wird an Amberlite CG 400 (SCN^–) stark adsorbiert und kann durch Elution mit 2M HCl — 1,5% H₂O₂ leicht abgelöst werden. Im Eluat wird es spektralphotometrisch mit Diantipyrylmethan bestimmt. Die kombinierte Methode gestattet eine selektive und empfindliche Bestimmung in einer 41-Probe von Meer- oder auch Süßwasser. Für einen Gehalt von 0,4 g Ti/l beträgt der Variationskoeffizient 7%.

     

Biological recycling of plastics containing ester bonds

Biodegradable blend plastics such as polycaprolactone (PCL)-conventional plastics blends, PCL-polystyrene blend foams, PCL-poly-3-hydroxybutyrate (PHB) blends, PCL-raw cornstarch (CS) blends and PCL-CaCO₃ blends were developed. It was suggested that the thermophilic composting of biodegradable plastics containing PCL was one of powerful technologies for recycling of biodegradable plastics. Furthermore, we tried to get useful products from biodegradable plastics by microbial fermentation processes. Polypropylene (PP)-CS blend and PCL-CS blend plastics were aerobically converted into ethanol by Bacillus polymyxa. PHB and PP-CS blend and PCL-CS blend plastics were anaerobically converted into some organic acids and methane gas by mixed microbial cultures with a methanogenic bacterium.