Fast and continuous chemical isolation of short-lived isotopes of Hf,Ta and W as homologs of elements 104, 105 and 106

Some short-lived isotopes of Hf, Ta and W, synthesized at the U-400 cyclotron of JINR-Dubna, have been isolated using a previously elaborated fast continuous method of chemical isolation of element 104 from nuclear reaction products. The products were transported by a NaCl aerosol jet, from the irradiated targets to a separation device in which Hf, Ta and W were isolated by using three coupled ion-exchange columns.     

Synthesis of oxychelerythrine using lithiated toluamide-benzonitrile cycloaddition

Oxychelerythrine, benzo[c]phenanthridine alkaloid, was synthesized from easily available starting toluamide 5 and benzonitrile 6 using toluamide-benzonitrile cycloaddition reaction in 6 steps.     

Zur Kenntnis der μ-Peroxo-bis(pentacyanokobaltate(III)). Neuartige Darstellung,Beschreibung eines μ-Hydroperoxo-komplexes K5[Co2OOH(CN)10] · 2 H2O und eines μ-Peroxo-Carbonato-Komplexes K6[Co2CO4(CN)10] · 2 H2O

Investigations on Metal Catalysts. XXII. Chemisorption of Hydrogen on Pt? Ru and η-Al₂O₃ Supported Pt? Ru Catalysts Measurements of the H₂ chemisorption by volumetric method were carried out on several series of Pt? Ru and η-Al₂O₃ supported Pt? Ru catalysts. Addition of Ru to Pt and vice versa effects a remarkable influence on the sorption behaviour of the starting samples. For mixtures of carrier-free catalysts and η-Al₂O₃ as well as Pt? Ru/η-Al₂O₃ catalysts a hydrogen-spillover effect was found.     

Trace analysis of rapamycin in human blood by micellar electrokinetic chromatography

A capillary electrophoretic method with UV detection at 278 nm has been developed for analysis of the immunosuppressant rapamycin (sirolimus) in human blood at low microgram per liter levels. Separation has been achieved in an acidic carrier electrolyte containing sodium dodecylsulfate and 30% (v/v) acetonitrile. For sample clean-up and preconcentration, an off-line solid-phase extraction step using a silica-based reversed-phase material and an on-capillary focussing technique were employed. The latter allows the injection of increased sample volumes without excessive band broadening. Although this new method is less sensitive than existing liquid chromatographic procedures combined with mass spectrometry, it is fully suited to routine analysis of rapamycin in blood from patients treated with this drug. Last but not least the low costs make it an attractive alternative to established methods.     

Bismuth compounds in organic synthesis. A one-pot synthesis of homoallyl ethers and homoallyl acetates from aldehydes catalyzed by bismuth triflate

[reaction: see text] Three one-pot methods for the conversion of aldehydes to homoallyl ethers catalyzed by Bi(OTf)(3).xH(2)O (1 < x < 4) have been developed. The one-pot synthesis of homoallyl ethers can be achieved either by in situ generation of the acetal followed by its reaction with allyltrialkylsilane or by a three-component synthesis in which the aldehyde, trimethylorthoformate or an alkoxytrimethylsilane and allyltrimethylsilane are mixed together in the presence of bismuth triflate (0.1-1.0 mol %). In addition, a three-component synthesis of homoallyl acetates, which is achieved by reacting the aldehyde, acetic anhydride, and allyltrimethylsilane in the presence of bismuth triflate (3.0-5.0 mol %), has been developed. The use of a relatively nontoxic, easy to handle, and inexpensive catalyst adds to the versatility of these methods.     

Gap exponents for percolation processes with triangle condition

A study is made of the gap exponents for percolation processes with the triangle condition in the subcritical region. It is show that the gaps are given by _t =2 fort=2, 3,. Scaling theory predicts thatP _p (¦C ₀¦S(p))–(p _c –p) andE _p (1/¦C ₀¦; ¦C ₀¦S(p))–(p _c –p)³, whereS(p) is the typical cluster size. It is found that (p _c –p)P _p (|C ₀S(p) ^1–)(p _c –p)^1–2 and (p _c –p)³E _p (1/|C ₀|;|C ₀|S(p) ^1–))(p _c –p)^3–4.     

Signal amplification and detection via a supramolecular allosteric catalyst

The design of a supramolecular allosteric catalyst system for catalytic signal amplification and detection is presented. The catalyst was switched "on" by the introduction of an analyte that also behaves as an allosteric activator. Concentrations of Cl- ions as low as 800 nM were catalytically amplified and detected. The signal was transduced via a pH-sensitive fluorescent probe and observed visually using a laboratory, handheld UV lamp and by spectrophotometry. Furthermore, the allosteric effect was quantified using gas chromatography for a range of Cl- concentrations. This three-part detection scheme involving analyte binding, allosteric catalyst activation, and signal transduction represents a new approach to small-molecule detection.     

Rational materials design of sorbent coatings for explosives: applications with chemical sensors

A series of chemoselective polymers had been designed and synthesized to enhance the sorption properties of polymer coated chemical sensors for polynitroaromatic analytes. To evaluate the effectiveness of the chemoselective coatings, a polynitroaromatic vapor test bed was utilized to challenge polymer coated surface acoustic wave (SAW) devices with different explosive vapors. Dinitrotoluene detection limits were determined to be in the <100 parts per trillion ranges. ATR-FTIR studies were used to determine the nature of the polymer-polynitroaromatic analyte interactions, and confirm the presence of hydrogen-bonding between polymer pendant groups and the nitro functional groups of polynitroaromatic explosive materials.