Preparation of 2-, 3-, 4- and 7-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans and their BLT1 and/or BLT2 inhibitory activities

Several 2-alkylcarbamoyl-1-alkylvinylbenzo[b]furans were designed to find a selective leukotriene B4 (LTB4) receptor antagonist. 2-(2-Alkylcarbamoyl-1-alkylvinyl)benzo[b]furans having a substituent group at the 3-position, 4-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans having a substituent group at the 3-position, and 7-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans and 3-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans were prepared and evaluated for LTB4 receptor (BLT1 and BLT2) inhibitory activities. (E)-3-Amino-4-[2-[2-(3,4-dimethoxyphenyl)ethylcarbamoyl]-1-methylvinyl]benzo[b]furan ((E)-17c) showed potent and selective inhibitory activity for BLT2. On the other hand, (E)-7-(2-diethylcarbamoyl-1-methylvinyl)benzo[b]furan ((E)-27a) showed potent inhibitory activity for both BLT1 and BLT2.     

Velocity spectrometer for a neutral atomic beam

A velocity spectrometer for a neutral atomic beam has been developed to prepare a monovelocity atomic beam. In order to disperse a relatively fast atomic beam according to its longitudinal velocity, a magnetic quadrupole lens with a large magnetic gradient has been used. The device was made using NdFeB permanent magnets. The magnetic gradient in the quadrupole was measured to be sufficiently large (1 T/cm) and uniform along the radial direction. The resonance fluorescence spectra of the Li atomic beam after passing through the magnetic quadrupole lens have been measured by using a single-mode tunable laser. From the peak shift of the fluorescence spectrum, the exerted force on Li atoms by the magnetic lens was 8160 times as large as the acceleration of gravity. Using the present spectrometer, we have measured the longitudinal velocity distribution of the thermal Li beam at 800 °C, which was in good agreement with the result from the fluorescence spectra. It is expected that a monovelocity Li atomic beam of 1000 m/s with a velocity spread narrower than 1% can be easily formed with a compact experimental arrangement using the developed velocity spectrometer. In this case, the available flux given as a fraction of the incident Li flux is estimated to be about 1%. A high-velocity resolution of 0.03% is expected at the available fractional flux of about 0.01%. Received: 5 June 2000 / Revised version: 14 August 2000 / Published online: 8 November 2000     

Lifetime of metastable fluorine atoms

For laser collimation of neutral F atoms, a resonance transition cycle between the metastable and the upper excited states (3s⁴ P _5/2?3p⁴ D ⁰ _7/2) can be used as a two-level closed system. We have determined the lifetime of the metastable state (3s⁴ P _5/2) in F atoms by measuring the decay curve of the fluorescence intensity as a function of distance from the plasma source. Combining the measured velocity of F radicals from the Doppler shift of the fluorescence peak, we have obtained the lifetime of the F metastable state as 3.7±0.5 μs. With this short metastable lifetime of F radicals, the simple Doppler cooling method using spontaneous light force is not practical for laser collimation of F radicals. Use of stimulated light force may be necessary to collimate F radical beams in a short distance. Received: 4 July 2000 / Published online: 13 September 2000     

A Disposable Sensor Chip Using a Paste Electrode with Surface-Imprinted Graphite Particles for Rapid and Reagentless Monitoring of Theophylline

This work focuses on a carbon-based imprinted polymer composite, employed as a molecular recognition and sensing interface in fabricating a disposable electrochemical sensor. The carbon-paste electrode was made of a molecularly imprinted polymer comprising a copolymer of methacrylic acid as the functional monomer and blended crosslinking monomers of N,N′-methylenebisacrylamide, and ethylene glycol dimethacrylate, with theophylline as the template. The analytical properties of the proposed theophylline sensor were investigated, and the findings revealed an increase in differential pulse voltammetric current compared to the non-imprinted electrode. Under optimized conditions, the sensor has shown high sensitivity, high selectivity, lower detection limit (2.5 µg/mL), and satisfactory long-term stability. Further, the sensor was tested in whole bovine blood and validated without any matrix effect and cross-reactivity. Additionally, chronoamperometry of the sensor chip supported a rapid determination of THO with a short response time of 3 s. This carbon-paste electrode is highly specific for theophylline and may be applied as a drug sensor for clinical use.     

Performance comparison of artificial neural networks and expert systems applied to flow pattern identification in vertical ascendant gas–liquid flows

Instantaneous readouts of an electrical resistivity probe are taken in an upward vertical air–water mixture. The signals are further processed to render the statistical moments and the probability density functions here used as objective flow pattern indicators. A series of 73 experimental runs have its flow pattern identified by visual inspection assisted by the analyses of the void fraction’s trace and associated probability density function. The flow patterns are classified into six groups and labeled as: bubbly, spherical cap, slug, unstable slug, semi-annular and annular. This work compares and analyzes the performance of artificial neural networks, ANN, and expert systems to flow pattern identification. The employed ANNs are Multiple Layer Perceptrons, Radial Basis Functions and Probabilistic Neural Network, with single and multiple outputs. The performance is gauged by the percentage of right identifications based on experimental observation. The analysis is extended to clustering algorithms to assist the formation of knowledge base employed during the learning stages of the ANNs and expert systems. The performance of the following clustering algorithms: self organized maps, K-means and Fuzzy C-means are also tested against experimental data.     

Novel Water‐Soluble Poly(m‐benzamide)s: Precision Synthesis and Thermosensitivity in Aqueous Solution

Summary: Chain‐growth polycondensations of 3‐aminobenzoic acid methyl esters 1a and 1b , bearing a tri‐ or tetra(ethylene glycol) methyl ether unit on the amino group, respectively, were carried out with lithium hexamethyldisilazide (LiHMDS) as a base and phenyl 4‐methylbenzoate ( 2 ) as an initiator in THF at 0 °C. The poly(m‐benzamide)s obtained in the presence of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) possessed narrow molecular weight distributions ( < 1.2) with molecular weights that were determined by the feed ratios of [ 1 ]₀/[ 2 ]₀. Poly 1a and poly 1b were each soluble in water and exhibited a lower critical solution temperature (LCST) in water. Furthermore, the phase separation in water depended on the length of the oligo(ethylene glycol) side chain and on the molecular weight and molecular weight distribution of poly 1 .

Thermally sensitive water‐soluble poly(m‐benzamide)s.     

A novel process for synthesizing polystyrene and polyarylate block copolymers utilizing telechelic polystyrene

A novel process for synthesizing polystyrene (PS) and polyarylate (PAr) block copolymers utilizing telechelic polystyrene was proposed. This process was comprised of three steps. In the first step, carboxyl-terminated telechelic polystyrene (COOH PS COOH) was prepared by free radical polymerization with 4,4′-azobis(cyanovalelic acid) (ACVA). In the second step, COOH PS COOH was reacted with bisphenol-A by the use of triphenylphosphine, hexachloroethane, and triethylamine to convert carboxyl groups into phenol groups (OH PS OH). In the third step, to produce the PS PAr block copolymer, OH PS OH was added to a polyarylate synthesizing system where bisphenol-A and the mixture of tere/isophthaloyl dichloride (1 : 1 mole ratio) were polymerized by solution polycondensation. PS PAr block copolymers were successively obtained with relatively high PS copolymerization ratio. The ratio was over 70%, while there was a wide variety in molecular composition and molecular weight. Furthermore, by this process PS PAr block copolymers can be obtained from step 1 through step 3 consecutively without isolating the intermediates. This method has potential for industrial applications. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2839–2847, 1998     

Polymeric fibers and microporous films by photo‐crosslinking of triphenylene‐derived liquid crystals

Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one ( TPC1 _n ) or two ( TPC2 _n ) n‐alkoxy groups (C _nH_2n+1O; n = 10–14), respectively, as peripheral groups are synthesized. Both of them are polymerized into fibers up to 2 mm long by UV irradiation in liquid paraffin in the columnar LC temperature ranges. The fiber structures seem to be preconstructed in liquid paraffin. In addition, TPC2 _n are shown to form microporous films up to 15 μm in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the films in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1 _n and the hydrogenated derivative of TPC2 ₁₂ , the porous film‐forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 605–612     

Optical properties of Ni-doped single crystals grown by floating zone method

The single crystal growth conditions and spectroscopic characterization of Ni-doped MgGa₂O₄ with inverse-spinel structure crystal family are described. Single crystals of this material have been grown by floating zone method. Ni-doped MgGa₂O₄ single crystals have broadband fluorescence in the 1100–1600 nm wavelength range, 1.6 ms room temperature lifetime, 56% quantum efficiency and stimulated emission cross section at the emission peak. This new material is very promising for tunable laser applications covering the important optical communication and eye safe wavelength region.     

D3h‐Symmetrical Shape‐Persistent Macrocycles Consisting of Pyridine–Acetylene–Phenol Conjugates as an Efficient Host Architecture for Saccharide Recognition

Hexagonal shape‐persistent macrocycles (SPMs) consisting of three pyridine and three phenol rings linked with acetylene bonds were developed as a preorganized host for saccharide recognition by push–pull‐type hydrogen bonding. Three tert‐butyl or 2,4,6‐triisopropylphenyl substituents were introduced on the host to suppress self‐aggregation by steric hindrance. In spite of the simple architecture, association constants K_a of the host with alkyl glycoside guests reached the order of 10⁶ m ^?1 on the basis of UV/Vis titration experiments. This glycoside recognition was much stronger than that in the cases of acyclic equivalent hosts because of the entropic advantage brought by preorganization of the hydrogen‐bonding sites. Solid–liquid extraction and liquid–liquid transport through a liquid membrane were demonstrated by using native saccharides, and much preference to mannose was observed.