High-Contrast Imaging of Nano-Channels Using Reflection Near-Field Scanning Optical Microscope Enhanced by Optical Interference

We demonstrated a contrast enhancement in a near-field scanning optical microscope (NSOM) by optical interference with an aperture probe in reflection (illumination-collection) mode operation. We observed a NiO film deposited on a sapphire substrate and clearly visualized 2-nm-deep nano-channel structures on the surface of the film. The reflection NSOM enhanced by optical interference is quite a promising instrument for high-resolution optical detection and estimation of low-contrast nanostructures.     

Synthesis of the spirocyclic center of fredericamycin a by phenoxy-enoxy radical coupling

Ferricyanide oxidation of the dianions of phenolic β-diketones $\text{2}$ effects intramolecular phenoxy-enoxy radical coupling to form spiro systems derived from C-C bond formation $\text{para}$ or $\text{ortho}$ to the phenolic oxygen.     

Chromatographic Removal of Host Cell DNA from Cellular Products Using Columns Packed with Cationic Copolymer Beads

This paper describes a method for selective removal of DNA from various cellular products using columns packed with cross-linked poly(ethyleneimine) (PEI) beads or cross-linked N,N-dimethylaminopropylacrylamide (DMAPAA) beads. Each bead type showed a high DNA-adsorbing activity under experimental conditions of pH 5.0–9.0 and ionic strength of μ = 0.05–0.4. When γ-globulin was present in solution with DNA under physiological conditions (pH 7.2, μ = 0.17), DNA-removing activity of PEI columns was unsatisfactory because both the DNA and the γ-globulin were adsorbed onto the column. In contrast, DMAPAA columns allowed removal of DNA from various protein solutions contaminated with DNA. DNA concentration in each treated protein solution was below 10 ng mL^?1, and high recovery of proteins was obtained.     

Synthesis of chromogenic crown ethers and liquid—liquid extraction of alkaline earth metal ions

New crown ether dyes carrying two pendent anionic side-arms were synthesized for the extraction-spectrophotometry of alkaline earth metal ions. In the extraction of alkaline earth metal ions by these dianionic reagents, size recognition by the crown ether ring was more remarkable than in the case of alkali metal ion extraction by a similar type of monoanionic reagents. Dramatic changes in metal selectivity were observed when the nature of the anionic side-arm was changed while the crown ether skeleton was kept the same. The structure/selectivity relationship is discussed in terms of “chelate” and “intramolecular ion-pair” formation. Typically, when the basicity of the pendent anions was relatively high and a six-membered chelate was structurally possible for the pendent anions and the crown-bound metal, the extraction of calcium was favored by up to a factor of 3000 in the ratio of the Ca/Ba extraction constants for reagents of the diaza-18-crown-6 type. In contrast, the reagents which had pendent anions with only poor coordination ability for metal ions seemed to form complexes of the ion-pair type, and calcium ion was 10⁵ times less extractable than barium ion for the same diaza-18-crown-6-skeleton. Strontium ion seemed to be extracted most effectively when the extracted complex assumed properties intermediate between the chelate and intramolecular ion-pair.     

Ultrasonic speeds and thermodynamic properties of (benzene + nitrobenzene) under high pressures

Ultrasonic speeds u in {(1?x)C₆H₆ + xC₆H₅NO₂} were measured by a fixed-path pulse technique at 293.15, 303.15, and 313.15 K under pressures up to 30 or 200 MPa with an observed error of less than 0.3 per cent. Curves of u(x) change smoothly in the benzene-rich region. But near x = 0.7, u(x) apparently deviates from a smooth curve, and the apparent gap becomes progressively greater as the temperature is reduced or the pressure is raised. From the experimental values, densities, isentropic compressibilities, and expansivities were calculated at high pressures. These quantities also show unusual behavior with x similar to that of u.     

A\overline {Poincar\acute{e}} gauge theory of gravity

We develop a gauge theory of gravity on the basis of the principal fiber bundle over the four-dimensional space-timeM with the covering groupP¯ ₀ of the proper orthochronous Poincaré group. The field components are constructed with the connection coefficients , and with a Higgs-type field. A Lorentz metricg is introduced with , which are then identified with the components of duals of the Vierbein fields. Associated with there is a spinor structure onM. For Lagrangian densityL, which is a function of , ,, matter field , and oftheir first derivatives, we give the conditions imposed by the requirement of the gauge invariance. The Lagrangian densityL is restricted to be of the formL =L ^tot (, T ^klm ,R ^klmn , _k , ), in whichT ^klm ,R ^klmn are the field strengths of , , respectively. Identities and conservation laws following from the gauge invariance are given. Particularly noteworthy is the fact that the energy momentum conservation law follows from theinternal translational invariance. The field equation of is automatically satisfied, if those of and of are both satisfied. The possible existence of matter fields with intrinsic energy momentum is pointed out. When is a field with vanishing intrinsic energy momentum, the present theory practically agrees with the conventional Poincaré gauge theory of gravity, except for the seemingly trivial terms in the expression of the spin-angular momentum density. A condition leading to a Riemann-Cartan space-time is given. The field holds a key position in the formulation.     

An efficient synthetic method for macrocyclic ketones by intramolecular alkylation of protected cyanohydrins,and its application to the syntheses of muscone and exaltone

A simple synthetic method for macrocyclic ketones based on intramolecular alkylation of carbanion, generated from protected cyanohydrin is reported. Subsequent mild treatment with acid and base of the cyclized products leads to macrocyclic ketones in high yields. The reaction is rapid and irreversible, and hence required short reaction time. The method was successfully applied to the syntheses of cyclohexadecanone and trans-2-cyclopentadecenone as a precursor of (±)-muscone and exaltone.     

Electronic and Conformational Effects on the Lipophilicity of Isomers and Analogs of the Neurotoxin 1-Methyl-4-phenylpyridinium (MPP+)

A number of isomers and analogs of the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺) were examined for their lipophilic behavior. Their partition coefficients in the 1-octanol/H₂O system were measured by centrifugal partition chromatography (CPC), which, being much faster and markedly more precise than the classical shake-flask method, proved a very promising alternative for assessing lipophilicity. A smaller-than-expected lipophilicity was shown by the ortho-isomer of MPP⁺ (M2PP⁺) and is explained in terms of electronic effects and rigidity, as revealed by UV and NMR spectroscopy, and conformational analysis. Implications of lipophilicity in modulating the in vivo dopaminergic neurotoxicity of the examined compounds are also discussed.     

Chromoionophores Based on Crown Ethers and Related Structures for Alkali Metal Ion Sensing in Aqueous Media

Recent progress in chromoionophores based on (1) spherand and hemispherand, (2) cryptand, and (3) dibenzo-16-crown-5 and calix[4]crown which selectively respond to alkali metal ions in aqueous media is reviewed in relation to their molecular structure and photometric function. The design concept of the chromoionophores for colorimetry in aqueous media is discussed in the light of their acid dissociation and metal complex formation equilibria.