Preparation of monodisperse hydrophilic polyamide by anionic polymerization of bicyclic oxalactam

The preparation of a monodisperse hydrophilic polyamide was achieved in the anionic polymerization of a bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2.1]octan-7-one (abbreviated BOL) with the use of N-benzoyl BOL and potassium pyrrolidonate (2 and 0.5 mol % to BOL, respectively) in dimethyl sulfoxide at 25°C. The number-average molecular weight of the polyamide increased in direct proportion to the monomer conversion, and was consistent with the value calculated from the amounts of the consumed monomer and activator. The molecular weight distribution (MWD) of the polyamide obtained until the middle stage of polymerization (polymerization time, < 10 min; monomer conversion, < 60%) was found to be narrow (M_w/M_n = 1.1). The MWD was gradually broadened in the later stage of the polymerization, which may result from the redistribution of molecular weight of the resulting polyamide not only by the polymerization–depolymerization equilibrium, but also by transamidation between polymer chains.     

Microwave spectra of deuterated ethylenes: Dipole moment and rz structure

The pure rotational spectra of three deuterated ethylenes, CH₂CD₂, CH₂CHD, and cis-CHDCHD, were observed by microwave spectroscopy, and the rotational and centrifugal distortion constants were determined precisely. The dipole moment of CH₂CD₂ was calculated from the Stark effects to be 0.0091 ± 0.0004 D. From the observed rotational constants the average structure was calculated to be $\text{r}{}_{\mathrm{z}}\text{(CC)}\text{= 1.3391 ± 0.0013}\text{A}\text{?}$, $\text{r}{}_{\mathrm{z}}\text{(CH)}\text{= 1.0869 ± 0.0013}\text{A}\text{?}$, θ_z(CCH) = 121.28 ± 0.10°, and $\text{r}{}_{\mathrm{z}}\text{(CH)}\text{- r}{}_{\mathrm{z}}\text{(CD)}\text{= 0.00137 ± 0.00037}\text{A}\text{?}$, where the errors include one standard deviation in the fitting and errors due to an uncertainty (±0.03°) in θ_z(CCH) - θ_z(CCD).     

Particle picture in external fields,quantum holonomy,and gauge anomaly

We formulate a path integral of chiral gauge theories by means of the canonical quantization of fermions in time-dependent background gauge fields. The expression of the path integral is composed of two parts. One is due to the nontrivial holonomy of the fermionic Fock vacua and the other is the conventional form which is used in the perturbation theory. The nontrivial holonomy part is expected to be a nonlocal counter term. We show a possibility of the perturbative calculation     

Localized pits and peaks in forbush decrease, associated with stratified structure of disturbed and undisturbed magnetic fields

Summary Forbush decrease (FD) is generally interpreted as a result of diffusion-convection of cosmic rays in a disturbed interplanetary magnetic field associated with the magnetohydrodynamic shock wave caused by solar flare. In this paper, we point out that a large number of FDs contain an isolated region or regions with pit-type time profile, in which cosmic rays are not in a diffusion-convection state but in a trapped state in undisturbed, uniform and strong magnetic field perpendicular to the solar wind. The trapped state is also characterized with a large ratio of the magnetic to ion thermal energy. The median duration time of the state is about 8 hours. About half of these states are associated with the northward (or southward) magnetic field, while the other half with the eastward (or westward) magnetic field. Flares responsible for the former state seem to be concentrated in an eastward region from about 30°W on the solar disk, while those for the latter state seem rather symmetric with respect to the centre of the solar disk. It is suggested that the trapped state is produced inside a magnetic tube of force which is not of a small scale such as that of the magnetic bubble pointed out by Klein and Burlaga, but of a large scale, having a horseshoe structure with its ends supposed to be connected to somewhere in an inner region near the Sun and with its cross-section supposed to be of a thin filament with radial and transverse dimensions of ≈0.1 a.u. and ≈1.1 a.u. at the Earth’s orbit. This belt-like tube of force is supposed to be produced on the solar surface or near the Sun and to be carried out by solar wind in a frozen state, trapping in itself low-density cosmic rays near the Sun. In addition to the pits, we point out also the existence of some peaks which are observed not only in the trapped region but also in a region of extremely disturbed magnetic field neighbouring in between two trapped regions. It is suggested that cosmic rays in the region of the latter type are supposed to be guided freely (or easily) from outer space through a path with similarly disturbed magnetic state, and therefore, they could maintain their density in the region always higher than in the neighbouring regions. Two kinds of cosmic-ray-guiding mechanism in the above can be regarded as being at opposite poles.     

Dianion of N-phenyl-2-(phenylsulfonylmethyl)propenamide: an efficient synthetic reagent for (E)-trisubstituted olefins and 5,6-dihydro-2H-pyrans

The dianion of N-phenyl-2-(phenylsulfonylmethyl)propenamide was found to be an efficient reagent for the synthesis of (E)-α,β-unsaturated amides and 5,6-dihydro-2H-pyrans.     

Lactose hydrolysis and beta-galactosidase activity in sonicated fermentation with Lactobacillus strains

Milk fermentation with four Lactobacillus strains, including L. delbrueckii subsp. bulgaricus B-5b, L. helveticus LH-17, L. delbrueckii subsp. lactis SBT-2080 and L. acidophilus SBT-2068, was carried out under sonicated conditions. Under continuous sonication, viable cell count decreased or grew less than in conventional fermentation, but it increased considerably in static incubation after sonication. Sonication caused beta-galactosidase release from lactic acid bacteria cells to the culture medium, thus resulting in higher total beta-galactosidase activity. However, lactose hydrolysis was enhanced only when beta-alactosidase was effectively released. With L. delbrueckii subsp. bulgaricus B-5b and L. helveticus LH-17. the degrees of lactose hydrolysis achieved were about 75% which is much higher than those in conventional fermentation (below 40%). Results presented here showed that a high viable cell count and a high degree of lactose hydrolysis could be simultaneously achieved by a suitable sonication method.     

Cesium fluorohydrogenate, Cs(FH)2.3F

Cs(FH)_2.3F is a liquid salt exhibiting a low viscosity of 20.1 cP and a high conductivity of 86.3 mS cm⁻¹ at 25 °C, in spite of the relatively high melting point (16.9 °C). The high density of 2.82 g cm⁻³ at the liquid state is due to the heavy atomic weight and small size of cesium atom compared to the organic cations of general ionic liquids. The infrared spectroscopy indicates that this salt contains (FH)₂F⁻ as a main anionic species. The other anionic species such as (FH)₃F⁻ found in the cases of other M⁺(HF)_2.3F (M = a univalent organic cation) ionic liquid salts is not detected, suggesting its small abundance as well as the presence of neutral HF in the form of molecular and/or oligomers. The result of ¹H NMR also suggests that the anions exchange HF between them. These observations coincide with the experimental result that Cs(FH)_2.3F acts as an acid against general ionic liquid fluorohydrogenates such as EMIm(FH)_2.3F (EMIm = 1-ethyl-3-methylimidazolium) to lose HF and give Cs(FH)₂F precipitate.     

Naphthyridine‐Benzoazaquinolone: Evaluation of a Tricyclic System for the Binding to (CAG)n Repeat DNA and RNA

The expansion of CAG repeats in the human genome causes the neurological disorder Huntington's disease. The small‐molecule naphthyridine‐azaquinolone NA we reported earlier bound to the CAG/CAG motif in the hairpin structure of the CAG repeat DNA. In order to investigate and improve NA ‐binding to the CAG repeat DNA and RNA, we conducted systematic structure‐binding studies of NA to CAG repeats. Among the five new NA derivatives we synthesized, surface plasmon resonance (SPR) assay showed that all of the derivatives modified from amide linkages in NA to a carbamate linkage failed to bind to CAG repeat DNA and RNA. One derivative, NBzA , modified by incorporating an additional ring to the azaquinolone was found to bind to both d(CAG)₉ and r(CAG)₉. NBzA binding to d(CAG)₉ was similar to NA binding in terms of large changes in the SPR assay and circular dichroism (CD) as well as pairwise binding, as assessed by electron spray ionization time‐of‐flight (ESI‐TOF) mass spectrometry. For the binding to r(CAG)₉, both NA and NBzA showed stepwise binding in ESI‐TOF MS, and NBzA ‐binding to r(CAG)₉ induced more extensive conformational change than NA ‐binding. The tricyclic system in NBzA did not show significant effects on the binding, selectivity, and translation, but provides a large chemical space for further modification to gain higher affinity and selectivity. These studies revealed that the linker structure in NA and NBzA was suitable for the binding to CAG DNA and RNA, and that the tricyclic benzoazaquinolone did not interfere with the binding.     

Ion chromatographic determination of hydroxide ion on monolithic reversed-phase silica gel columns coated with nonionic and cationic surfactants

The determination of hydroxide by ion chromatography (IC) is demonstrated using a monolithic octadecylsilyl (ODS)-silica gel column coated first with a nonionic surfactant (polyoxyethylene (POE)) and then with a cationic surfactant (cetyltrimethylammonium bromide (CTAB)). This stationary phase, when used in conjunction with a 10 mmol/l sodium sulfate eluent at pH 8.2, was found to be suitable for the rapid and efficient separation of hydroxide from some other anions, based on a conventional ion-exchange mechanism. The peak directions and detection responses for these ions were in agreement with their known limiting equivalent ionic conductance values. Under these conditions, a linear calibration plot was obtained for hydroxide ion over the range 16 micromol/l to 15 mmol/l, and the detection limit determined at a signal-to-noise ratio of 3 was 6.4 micromol/l. The double-coated stationary phase described above was shown to be superior to a single coating of cetyltrimethylammonium bromide alone, in terms of separation efficiency and stability of the stationary phase. A range of samples comprising solutions of some strong and weak bases was analyzed by the proposed method and the results obtained were in good agreement with those obtained by conventional potentiometric pH measurement.     

Selective determination of ammonium ions by high-speed ion-exclusion chromatography on a weakly basic anion-exchange resin column

This paper describes an ion-exclusion chromatographic system for the rapid and selective determination of ammonium ion. The optimized ion-exclusion chromatographic system was established with a polymethacrylate-based weakly basic anion-exchange resin column (TSKgel DEAE-5PW) as the separation column, an aqueous solution containing 0.05 mM tetramethylammonium hydroxide (pH 9.10) as eluent with conductimetric detection for the analyte determination. Under the optimum chromatographic conditions, ammonium ion was determined within 2.3 min with a detection limit (S/N=3) better than 0.125 microM. Ammonium ion in rain and river waters was precisely determined using this ion-exclusion chromatographic system.