Ionic liquids as a novel solvent for lanthanide extraction.

Octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) dissolved in an ionic liquids, 1-butyl-3-methyl-imidazolium hexafluorophosphate, greatly enhances extractability and selectivity of lanthanide cations compared to that dissolved in conventional organic solvents; further, the recovery of lanthanides extracted into ionic liquids can be accomplished using several stripping solutions containing complexing agents. The possibility of utilizing ionic liquids as novel separation media in an industrial liquid-liquid extraction process was demonstrated.     

Low noise submillimeter SIS receiver with niobium nitride quasiparticle tunnel junctions

We have developed and tested a submillimeter waveguide SIS mixer with NbN-MgO-NbN quasiparticle tunnel junctions. The two junction array is integrated in a full NbN printed circuit. The NbN film critical temperature is 15 K and the junction gap voltage is 5 mV. The size of the junctions is 1.4 × 1.4 µm and Josephson critical current density is about 1.5 KA/cm² resulting in junction R_NC product about 40. The inductive tuning circuit in NbN is integrated with each junction in two junction array. A single non contacting backshort was tuned at each frequency in the mixer block.At 306 GHz the minimum DSB receiver noise temperature is as low as 230 K. The sources of the receiver noise and of the limits of the NbN SIS submillimeter mixer improvement are discussed.     

Potentiometric discrimination of organic amines by liquid membrane electrodes based on a long alkyl chain derivative of β-cyclodextrin

A long alkyl chain derivative of -cyclodextrin (6^A,6^B,6^C,6^D,6^E,6^F,6^G-hepta-S-dodecyl-6^A, 6^B,6^C,6^D,6^E,6^F,6^G-heptathio--cyclodextrin tetradecaacetate) was examined as a new type of sensory element of an ion-selective electrode for organic amines. Poly(vinyl chloride) (PVC) matrix liquid membrane electrodes based on this host were prepared by using several membrane solvents, among which 2-fluoro-2-nitrodiphenyl ether (FNDPE) was found to be by far most effective for potentiometric responses by the cyclodextrin host. Guest-induced potential changes were examined at pH 5.0 for several groups of protonated organic amine guests having different types of nonpolar moieties. The magnitude of the guest-induced potential change was in the order of 2-phenylethylamine > 1-adamantanamine > benzylamine > cyclohexanamine > dopamine. Potentiometric discrimination was also observed for the positional isomers of di- and trimethoxybenzylamines, though the discrimination between the isomers of monomethoxybenzylamines was negligible. These potentiometric selectivities were quite different from those for a liquid membrane electrode containing no particular sensory element. No appreciable effect was observed by addition of potassium tetrakis(p-chlorophenyl)borate as a fixed anionic site. Such a characteristic feature of this cyclodextrin-based liquid membrane electrode was explained in terms of the availability of an inclusion complex between the cyclodextrin host and each guest in a geometry that would be stable at the membrane surface.Presented in part at the IUPAC 2nd International Symposium on Bioorganic Chemistry, Fukuoka, Japan, June 6–10, 1993. Abstracts, p. 239     

Creation of polynucleotide-assisted molecular assemblies in organic solvents: general strategy toward the creation of artificial DNA-like nanoarchitectures

The influence of added polynucleotide on the gelation ability of nucleobase-appended organogelators was investigated. Uracil-appended cholesterol gelator formed a stable organogel in polar organic solvents such as n-butanol. It was found that the addition of the complementary polyadenylic acid (poly(A)) not only stabilizes the gel but also creates the helical structure in the original gel phase. Thymidine and thymine-appended gelators can form stable gel in apolar solvents, such as benzene, where poly(A)-lipid complex can act as a complementary template for the gelator molecules to create the fibrous composites. Based on these findings, we can conclude that self-assembling modes and gelation properties of nucleobase-appended organogelators are controllable by the addition of their complementary polynucleotide in organic solvents. We believe, therefore, that the present system can open the new paths to accelerate development of well-controlled one-dimensional molecular assembly systems, which would be indispensable for the creation of novel nanomaterials based on organic compounds.     

High-throughput screening for combinatorial thin-film library of thermoelectric materials

A high-throughput method has been developed to evaluate the Seebeck coefficient and electrical resistivity of combinatorial thin-film libraries of thermoelectric materials from room temperature to 673 K. Thin-film samples several millimeters in size were deposited on an integrated Al2O3 substrate with embedded lead wires and local heaters for measurement of the thermopower under a controlled temperature gradient. An infrared camera was used for real-time observation of the temperature difference Delta T between two electrical contacts on the sample to obtain the Seebeck coefficient. The Seebeck coefficient and electrical resistivity of constantan thin films were shown to be almost identical to standard data for bulk constantan. High-throughput screening was demonstrated for a thermoelectric Mg-Si-Ge combinatorial library.     

Local existence and blow-up criterion for the Euler equations in Besov spaces of weak type

We introduce Besov type function spaces, based on the weak L ^p -spaces instead of the standard L ^p -spaces, and prove a local-in-time unique existence and a blow-up criterion of solutions in those spaces for the Euler equations of perfect incompressible fluid in . For the proof, we establish the Beale-Kato-Majda type logarithmic inequality and commutator type estimates in our weak spaces. Abbreviate title: Euler equations in Besov spaces of weak type     

Synthesis and determination of the absolute configuration of chiral tetracosanaphthalenes

Tetracosanaphthalenes with diethylaminocarbonylmethoxy side chains were constructed by bottom-up synthesis, and their absolute configurations were determined by an exciton chirality method.     

Application of polyglycolized glycerides in protection of amorphous form of etoricoxib during compression

Polymorphic transition and stability problems during amorphous drug formulation are the major limiting factors in pharmaceutical technology. The purpose of the study was to evaluate the ability of polyglycolized glycerides (Gelucire) in protection of amorphous form of drug during compression and shelf life with lower proportion. Amorphous etoricoxib (AET) was prepared by spray drying technique. Tablets of AET and melt granules of AET (MG-AET) with Gelucire 50/13 were prepared. Tablets parameters like hardness, disintegration and content uniformity were evaluated. Tablets were evaluated immediately after compression and on storage for 3 months at ambient conditions to determine degree of transformation using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and dissolution profiles. Spray drying yielded the amorphous etoricoxib. Content uniformity in the tablet was in between 95 to 105%. Other parameters like disintegration and hardness were well within the limits. The results showed significant difference in the degree of crystallinity between AET tablet and MG-AET tablet. MG-AET tablet showed absence of crystallinity after 3 months storage. The reason could be formation of hydrogen bonding between the Gelucire and AET. Also Gelucire can be tableted very easily under low pressure and showed elastic recovery. Gelucire yielded a soft embedding during tableting, which prevented the polymorphic transformation. Polyglycolized glycerides (Gelucire 50/13) are able to protect amorphous etoricoxib during compression. As excipient required is low, it became possible to prepare tablet formulation as compared to other excipient like polyvinylpyrrolidon (PVP).