High-performance extraction operation using emulsion flow protected by surfactants in a liquid-liquid countercurrent centrifugal extractor

A small-size countercurrent centrifugal extractor with Taylor vortices in a narrow fluid region between an inner rotor and a stationary outer wall has been developed for high-performance liquid–liquid extraction. The extractor enables fast multistage extraction, and control of the emulsion flow is important for achieving superior extraction performance. To achieve a higher number of theoretical stages, rotation speed is initially increased to 1500 rpm to form an emulsion flow and subsequently decreased to the required level. The addition of (1) two types of surface-activating agents (sodium di(2-ethylhexyl) sulfosuccinate and sodium dodecyl sulfate) and (2) polymer protective agents (polyethylene glycol) was tested for maintaining a stable emulsion flow without sacrificing effective oil–water contact at lower rotation speeds. It was found that addition of a small amount of such agents allows for multistage extraction with a higher number of theoretical stages.     

Multi-staging for extraction of cesium from nitric acid by a single liquid–liquid countercurrent centrifugal extractor with Taylor vortices

Fission products that emit considerable decay heat and radioactivity, such as ¹³⁷Cs, have a large impact on waste management. Small and high-performance extractor is desirable for separating such nuclei. In this study, we implemented the continuous extraction of Cs from nitric acid in a single liquid–liquid countercurrent centrifugal extractor with Taylor Vortices by calix[4]arene-bis(t-octylbenzo-crown-6)(BOBCalixC6) as an extractant with trioctylamine(TOA) as a suppressant and with 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) as a phase modifier. Because of slow extraction kinetics of this process, extraction with multiple theoretical stages by just replacing conventional extractors into the single centrifugal extractor is difficult. Hence, we improved the dispersion of organic phase by an inner rotor made of lipophilic epoxy resin and elevating the solution temperature to lower the viscosity. Higher temperature was not appropriate from the aspect of chemical equilibrium in this process, but extraction with multiple theoretical stages was found to be possible.     

Structure and Complexation Studies on 2,2′-Bipyridyl and Trivalent Lanthanides

Separation of trivalent lanthanides (Ln) and trivalent actinides (An) is important task in reprocessing high-level liquid waste. In this study, the relationship between structures of complexes of 2,2′-bipyridyl (Bpy) and Ln (Nd, Er) and coordination strengths were investigated by X-ray diffraction and UV titration. With the decrease in ionic radius from Nd to Er, the N(Bpy)-Ln distance and N(Bpy)-Ln-N(Bpy) angle decreased, the dihedral angle of the Bpy pyridines increased, and the stability constant increased. This information about structure and coordination strength is important for designing better ligands for separating Ln and An ions.     

Formation of phase structure and crystallization behavior from disordered melt for ethylene-isoprene block copolymers and their blends

The structure formation and crystallization kinetics in crystallization from a disordered melt were investigated for a polyethylene-polyisoprene block copolymer (LEI) having M_n = 3.2 × 10⁴ and 53 wt% of polyethylene content and for its blends with the corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp), using synchrotron small-angle X-ray scattering techniques (SAXS) and differential scanning calorimetry (DSC). For LEI copolymer and the blends, no microphase separation structure was observed in the molten state. In the crystalline state of the neat LEI, the first and higher order scattering peaks were clearly observed, in which the intensity of the higher order peaks was considerably strong. This unusual behavior of the higher order peaks was explained by the lamellar insertion model of Hama and Tashiro. From the analyses based on this model and one-dimensional electron density correlation function with a three phase model, the phase structure in the crystalline state of the neat LEI was concluded to be a regular lamellar structure consisting of crystalline lamella of PE block and amorphous layers of PE and PIp blocks. This phase structure was quite different from that reported previously for a polyethylene-polyisoprene block copolymer (HEI) with a higher molecular weight in which HEI crystallized with keeping the microphase separation structure in the melt. For the blends of LEI with PIp homopolymer, the phase structure is affected by the blend composition, while for the blends with PE homopolymer, the phase structure depended on the crystallization temperature as well as the molecular weight and composition of the added PE. The Avrami index was 2-3 for neat LEI, all blends and PE homopolymers.     

Tracer monitored titrations: measurement of dissolved oxygen

The tracer monitored titration (TMT) technique is evaluated for measurement of dissolved oxygen. The TMT developed in this work uses a simple apparatus consisting of a low-precision pump for titrant delivery and an optical detector based on a white LED and two photodiodes with interference filters. It is shown that the classic Winkler method can be made free of routine volumetric and gravimetric measurements by application of TMT theory, which allows tracking the amounts of titrant and sample using a chemical tracer. The measurement precision of the prototype setup was 0.3% RSD.     

In vitro and in vivo investigations of upconversion and NIR emitting Gd2O3:Er3+,Yb3+ nanostructures for biomedical applications

The use of an “over 1000-nm near-infrared (NIR) in vivo fluorescence bioimaging” system based on lanthanide containing inorganic nanostructures emitting in the visible and NIR range under 980-nm excitation is proposed. It may overcome problems of currently used biomarkers including color fading, phototoxicity and scattering. Gd₂O₃:Er³⁺,Yb³⁺ nanoparticles and nanorods showing upconversion and NIR emission are synthesized and their cytotoxic behavior is investigated by incubation with B-cell hybridomas and macrophages. Surface modification with PEG-b-PAAc provides the necessary chemical durability reducing the release of toxic Gd³⁺ ions. NIR fluorescence microscopy is used to investigate the suitability of the nanostructures as NIR–NIR biomarkers. The in vitro uptake of bare and modified nanostructures by macrophages is investigated by confocal laser scanning microscopy. In vivo investigations revealed nanostructures in liver, lung, kidneys and spleen a few hours after injection into mice, while most of the nanostructures have been removed from the body after 24?h.     

Miscibility in blends of linear and branched poly(ethylene oxide) with methacrylate derivative random copolymers and estimation of segmental χ parameters

Miscibility in the blends of poly(ethylene oxide) (PEO) with n-hexyl methacrylate-methyl methacrylate random copolymers (HMA-MMA) and 2-ethylhexyl methacrylate-MMA random copolymers (EHMA-MMA) was evaluated using glass transition and light scattering methods. EHMA-MMA was more miscible with PEO than HMA-MMA. Both blends of PEO with HMA-MMA and EHMA-MMA showed UCST-type miscibility although homopolymer blends PEO/PMMA were predicted to be of LCST-type. This was attributed to an increase in the exchange enthalpy with increasing HMA or EHMA composition in the random copolymer. From the copolymer composition dependence of miscibility the segmental χ parameters of HMA/MMA, EHMA/MMA, EO/HMA and EO/EHMA were estimated using the Flory-Huggins theory extended to random copolymer systems. Miscibility in the blends of branched PEO with HMA-MMA whose HMA copolymer composition was 0.16 was compared with that in the linear PEO blends. The former blends were more miscible with HMA-MMA than the latter one by about 35 °C at the maximum cloud point temperature.     

Sensorless salient‐pole PM synchronous motor drive in all speed ranges

This paper presents a position sensorless drive of salient‐pole PM synchronous motors in all speed ranges including zero speed. Two position and speed estimation algorithms using the current differences between the actual and the estimated currents are proposed. One is based on the back emf estimation in the medium‐ and high‐speed ranges. Another is based on the position dependency of the winding inductances in the low‐speed ranges including zero speed. The effectiveness of the proposed algorithm has been verified with a six‐pole, 1.5‐kW, 1500‐rpm test motor. Stable sensorless speed control from zero to 3000 rpm within ±100% load torque range was achieved. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 64–73, 2001     

Water absorption of water-based anticorrosive coatings and its effect on mechanical property and adhesive performance

We focused on the water absorption of newly developed water-based anticorrosive coatings, which contain low volatile organic compounds. We investigated (1) the water absorption behavior of the coatings, (2) the effect of water absorption on the mechanical property of the coatings, and (3) the relationship between the water-absorbing properties and adhesive performance under accelerated aging conditions. It was found that the water absorption of the coatings indicated Fickian diffusion, and the saturated water content M _∞ and diffusion coefficient D of the coatings were quantitatively determined. The storage modulus E′ of the coatings decreased due to water absorption. However, in the coating that exhibited higher crosslink density, the effect of water absorption on the decrease in E′ was relatively small in spite of its higher M _∞ . The lower M _∞ and higher D coating resulted in better adhesive performance than the higher M _∞ and lower D coating. Thus, M _∞ value affected adhesive performance under accelerated aging conditions much more than D value.     

Country domain governance: an analysis by data-mining of country domains

Along with protocols, domain names are critical internet resources. To build a safe, secure, and globally ubiquitous internet, all entities responsible for the governance of domains must allocate their lower-level domains with competence and discipline following the basic principle of decentralized governance. The governance and operation of a country code top-level domain is delegated to the governing and operating entity of the relevant country or territory. There are great differences among these entities in domain allocation policy, fees, discipline, and technical competence. The undertaking of governing a global infrastructure requiring high integrity, such as the internet, on the basic principle of decentralized governance is unprecedented. To enable this governance to work well, it is necessary to set up proper objectives for the governance of country domains, and to use highly transparent criteria for a multi-faceted evaluation of how far these objectives have been achieved. This article presents a set of country domain governance indicators which is intended to be used for the construction of a safe and secure ubiquitous global network.