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Chiral recognition in the host–guest complexation systems of chiral crown ether hosts and amino ester guests was thoroughly examined using the electrospray ionization (ESI) mass spectrometry/enantiomer labeled (EL)-guest method. In this method, the mass spectra of a mixture of three components in a solution, a chiral host (H), an equal amount of an (S)-enantiomer guest labeled with deuterium atoms (GS-dn+) and an unlabeled (R)-enantiomer guest (GR+), were measured and the relative peak intensity value [I(H+GR)+/ I(H + GS-dn)+=IRIS] of the host–guest complex ions, observed with an excess guest concentration, was taken to provide the chiral recognition ability of the host. In our earlier report (1996), we demonstrated that the apparent chiral recognition abilities using a mass spectrometer with a homemade ESI interface were depressed by about one tenth compared with the corresponding abilities obtained by fast-atom bombardment (FAB) MS. In the present study, the enantioselective complexation behaviors of various combinations of chiral crown hosts with chiral guests were further investigated in detail mainly using a modern commercial ESI/ion trap (IT) mass spectrometer. Consequently, it was found that the apparent IRISvalues from the ESI-MS/EL-guest method changed significantly, depending upon the instrument used, and in particular, upon the ESI interfaces. Moreover, under the specific measuring conditions in ESI-IT-MS, the degrees of depression of the apparent chiral recognition abilities are roughly grouped into three classes, depending upon the number (or probably the type) of the hydrophobic substituents of the hosts. Representing the degrees by the slopes when plotting the apparent IRISvalues in ESI-MS versus those in FAB-MS, the slopes for the three classes are (1) 1.0, (2) 0.7 and (3) 0.3; the higher the hydrophobicity of the hosts (and then, the host–guest complex ions), the lower the slope (the apparent enantioselectivity). Strengthening the degree of depression may be caused by an increase in the local concentration of the host close to the surface of the droplets produced during the electrospary ionization process. The chiral recognition ability (KR/KS) in an equilibrated solution agrees quite well with the IRISvalue in FAB-MS rather than that in ESI-MS.

The enantiomeric excess (ee) of organic amine compounds has been determined using fast-atom bombardment (FAB) mass spectrometry based on the chiral host–guest complexation systems. The method uses a 1:1 mixture of the given chiral crown ether hosts (HRRRRand HSSSS-dn), one of whose enantiomers is isotopically labeled, for the ee-determination of a given amine salt guest (G+). The peak intensity ratio {I[(HRRRR+ G)+] / I[(HSSSS-dn+ G)+] = IRIS} of the two diastereomeric host–guest complex ions clearly changes with the change in the eeof the guest. The intensity excess (Ie) of the two complex ion peaks is newly defined as Ie= (IRIS−1) / (IRIS+ 1). The two sets of mass spectrometrically obtained Ievalues vs a set of eevalues of phenylalanine methyl ester and leucine methyl ester hydrochlorides show excellent linear relationships through the zero point (R2= 0.9989 and R2= 0.9970, respectively). This indicates the potential utility of the present ee-determination method to within ± 3% ee. Furthermore, based on the solution equilibrium distributions of the complex ions, the linearity is mathematically justified. Therefore, the ee-determination can be simplified as ee(%) = (|Ie| / |Ie(100)|) × 100: here, Ie(100)is the corresponding Ievalue obtained using an enantiomerically pure (100% ee) guest as a reference. The present chiral dimethoxyphenyl crown ether host pairs employed are effective (IRIS≥ 1.5) for the ee-determination of most α-amino acid esters, but not effective (IRIS≈ 1.0) for most simple alkylamines.

This study examines whether Japanese firms face borrowing constraints in investment decision. We find that the Euler equation derived from intertemporal maximization is violated in most of the industries when borrowing constraints are not properly taken into consideration. We also parameterize the Lagrangian multiplier attached to the borrowing constraints as a function of land assets or cash flow of the firm and evaluate the extent to which the borrowing constraints are prevalent. The borrowing constraints are notably severe for industries with many small firms, which is consistent with the literature that stresses asymmetric information in business cycles.J. Japan. Int. Econ., June 1996,10(2), pp. 122–149. Institute of Economic Research, Osaka University, 6-1 Mihogaoka, Ibaraki, Osaka 567, Japan; Graduate School of International Cooperation Studies, Kobe University, 2-1 Rokkodai-cho, Nadaku, Kobe 657, Japan; and Economic Research Institute, Economic Planning Agency, 3-1-1 Kasumigaseki, Chiyodaku, Tokyo 100, Japan.

The monocyclopropanation of 4-pyrones with dimethyloxosulfonium methylide, using a dimethyl sulfoxide hexamethylphosphoric triamide medium in place of neat dimethyl sulfoxide, gave homo-4-pyrone derivatives, which were then rearranged into the 2-furylacetone derivatives, along with hydra ted triketones or the dehydrated naphtho[2,1-b]furan derivative, by means of strong acid catalysis at room temperature.

Vinylcyclopropane derivatives could be synthesized with one-pot procedure from α,β-unsaturated thione (chromothione) derivatives by dimethyloxosulfonium methylide. Extremely facile addition of tetracyanoethylene with 4-methylene-4H-homochromenes gave dihydrobenzoxazepine derivatives. The reaction may be well interpreted with the homoaromatic stabilization of the cationic part in a zwitterionic intermediate which would be formed at the rate-determining step.

A novel secondary cyclopropylphenylmethyl acetate was prepared from a chromone skeleton viahomochromone derivatives in order to study solvolytic behavior. Reduction of the cyclopropyl ketone (homochromone) with lithium aluminum hydride in ether to the corresponding secondary alcohol, was found to be highly stereospecific giving only one of the geometrical isomers. The alcohol was converted into its acetate and subjected to solvolysis in 80% acetone–water. The acetate was hydrolyzed at the rate of 3×10-5s-1(25 °C) undergoing alkyloxygen fission. This rate constant was as high as the most reactive secondary esters in solvolyses ever reported, and about 20 times as high as the corresponding carbocyclic ester by estimation of the same leaving group. Product studies were undertaken in the presence of sodium hydrogencarbonate, and seven-membered hemiacetal was obtained in good yield. The structural characteristics of the homochromenol ester in the solvolysis are discussed and benzohomopyrylium ion, an extremely delocalized homoaromatic species, is proposed as an intermediate carbocation.

The 55 SuperKEKB final focusing superconducting magnets are assembled into two cryostats, located at the left side and the right side of the accelerator interaction point, respectively. The two cryostats are cooled by sub-cooled liquid helium at 0.16 MPa with two independent refrigerators of about 250 W cooling capacity. From August 2016, the two cryostats were installed into the accelerator beam line and were connected with their own sub-coolers and refrigerators. As cryogenic systems, commissioning was carried out to cool down the cryostats, to excite superconducting magnets, and to test system interlock protections against some emergencies. This paper introduces the cryostats and cryogenic systems, and the commissioning processes. The cryostat heat loads were measured and the results are presented in this paper.

The final focusing magnet system at the SuperKEKB interaction region has been designed under stringent space constraints and consists of 8 main Superconducting (SC) quadrupole magnets, 4 compensation SC solenoids, and 43 SC correction coils. SC correction coils are directly wound on the inner containment tubes of liquid helium (LHe) vessels, which serve as support bobbins for SC cables. Beam pipes, which are kept at room temperature ([?]300 K), are inserted into the cold bores of the vessel inner tubes. Between them, the minimal radial gaps are only 3.5 mm. Heat transfer from the warm beam pipes causes the raised operation temperatures of SC cables and increases heat leaks into cryostats. Multilayer insulation (MLI) is adopted to reduce heat flux in the narrow gaps. MLI performance as a function of the layer number was studied with a vertical anti-cryostat of dedicated design. The measurements were carried out by a calorimeter of thermal conduction and a modified LHe boil-off method. This paper presents the cryogenic measurement system and discusses the experimental results for the cryostats of the SuperKEKB final focusing SC magnets.

The reactions of the methylenehomochromene (titled compound) (1) with orthoformates (2a,b) or acetals (2c–f) easily took place in the presence of anhydrous zinc chloride to give 5-alkoxyethyl-2, 3-dihydro-l-benzooxepin derivatives (3a–f) in moderate to good yields. Unusually high reactivity of 1, may be due to homoaromatic stabilization in the reaction intermediate.

From (+)-catechin under radical reaction with 2,2′-azobis(2-methylpropionitrile), a novel intramolecular cyclization product was isolated and its structure has been characterized to be 2,4′,5′,12-tetrahydroxy-9,10-benzo-7-oxatricyclo[6.2.2.01,6]dodeca-2,5,9-trien-4-one by the spectroscopic analyses and the chemical transformation.

2-Acylcyclopent-3-en-1-ol derivatives, 2, were synthesized by the reaction of homopyrones with phenyllithium. The intermediate may be a cyclopropylmethanol derivative, 3, which was isomerized into 2. Similar treatment with methyllithium, methylmagnesium iodide, or lithium aluminium hydride also gave 2.

A novel quasi-dimeric oxidation product of (+)-catechin, formed during the radical-scavenging reaction that prevents lipid peroxidation, was isolated by chromatography, and its structure was elucidated by infrared, ultraviolet and1H and13C nuclear magnetic resonance spectra and mass spectrometry. It was 5'-[3-[3,4-(3',5'-dihydroxy) benzo-8-oxo-2,7-dioxabicyclo [4.4.0] deca-3,9-dien-10-yl]acryloyl]-(+)-catechin. It is an unusual type of dimer of flavan-3-ol derivatives, which is different from the naturally formed dimer, procyanidin.

A novel quasi-dimeric oxidation product of (+)-catechin, formed during the radical-scavenging reaction that prevents lipid peroxidation, was isolated by chromatography, and its structure was elucidated by infrared, ultraviolet and1H and13C nuclear magnetic resonance spectra and mass spectrometry. It was 5′-[3-[3,4-(3′,5′-dihydroxy) benzo-8-oxo-2,7-dioxabicyclo [4.4.0] deca-3,9-dien-10-yl]acryloyl]-(+)-catechin. It is an unusual type of dimer of flavan-3-ol derivatives, which is different from the naturally formed dimer, procyanidin.

The enantiomeric excess of α-amino acid ester hydrochlorides is determined for the first time using FAB mass spectrometry coupled with enantiomer-labelled host method.

The reaction of 2,6-dimethyl-3,5-diphenyl-4H-pyran-4-thione with dimethyloxosulfonium methylide occurred facilely to give two kinds of 2-thienylacetones, accompanied by a five-membered a,ß-unsaturated thione, a naphtho-[2,1-b]thiophene derivative, and a hemithioacetal.

A large thin wall superconducting solenoid magnet adopting a newly developed internal winding method has been constructed for the high energy particle detector "TOPAZ" at the TRISTAN e+e-collider. Various measurements were carried out on stability of such a thin solenoid in forced quench, sudden switch-off and forced mass flow during excitations. The results of these measurements are presented and evaluated.

A large thin wall superconducting solenoid magnet was constructed as a major component of the high energy particle detector "TOPAZ" for the TRISTAN e+e-collider at KEK. A newly developed "internal winding method" was an essential technique to fabricate a large coil as thin as possible. The magnet has been successfully tested with iron return yoke. It has been cooled down to 4.5 K and excited up to the rated current of 3650 A with a magnetic field of 1.21 T. Results of the tests and preliminary analyses are reported.