Investigation for a Drastic Change of the Core in 23O and 24O

We study the radius and energies of oxygen isotopes towards the neutron drip-line. The abrupt increase of the radius at ²³O is investigated with two different approaches; the m-scheme cluster-orbital shell model (COSM) and a simplified model approach with the core plus one and two valence neutrons. We investigate properties of the oxygen isotopes by changing the radius of the ¹⁶O-core in the m-scheme COSM approach and obtain the result that the broad structure of ¹⁶O is favored in the ²³O and ²⁴O. In the simplified model approach, we estimate the magnitude of the change of the size of ²²O in ²³O and ²⁴O.     

Microbial degradation of physiologically active peptides by strain B-9

The reaction of some physiologically active peptides with bacterial strain B-9 has been investigated. Bradykinin, β-endorphin, and [Leu(5)]enkephalin were quickly degraded, with half-lives of <5 min. Somatostatin, substance P, and angiotensin I were degraded relatively smoothly, with half-lives of 10 min to 1 h, whereas oxytocin and insulin were slowly degraded, with half-lives of 1 and 4 days, respectively. Vasopressin was barely degraded, with a half-life of >7 days. Linearized vasopressin, prepared by the reductive cleavage of the disulfide bond followed by alkylation with iodoacetamide, was degraded significantly faster than intact vasopressin, with a half-life of 2.5 h. A loop formed by disulfide bond formation was regarded as one of the degradation-resistant factors. Hydrolysis of the peptides in this study took place through cleavage of various peptide bonds, and the strain B-9 may bear similarities to the neutral endopeptidase in terms of its broad selectivity.     

Resistive superconducting transition of vanadium films

The resistive superconducting transition of vanadium films is studied experimentally. The behavior of the resistance is well explained by fluctuation theory. In parallel magnetic fields the pair-breaking parameter increases with the increase of the strength of the magnetic field.     

CO-transfer carbonylation reactions. A catalytic Pauson-Khand-type reaction of enynes with aldehydes as a source of carbon monoxide

The reaction of enynes with aldehydes in the presence of a catalytic amount of [RhCl(cod)](2)/dppp results in the Pauson-Khand-type reaction without the use of gaseous carbon monoxide to give bicyclic cyclopentenones in high yields (14 examples). Aldehydes serve as a source of carbon monoxide, and their carbonyl moiety is transferred to enynes, resulting in the formation of the carbonylated products. This reaction represents the first example of a CO-transfer carbonylation.     

A novel synthetic method for γ-acetoxy-(E)-α,β-unsaturated esters by the palladium catalyzed regio- and stereoselective acetoxylation of β,γ-unsaturated esters

A new synthetic method for γ-acetoxy-α,β-unsaturated esters by the acetoxylation of β,γ-unsaturated esters catalyzed by PdCl₂ in the presence of KOAc and pentyl nitrite in acetic acid is presented. The reaction takes place at γ-position of the esters regioselectively with double bond migration to α,β-position. The E configuration of the double bond was confirmed by NMR analysis. Preliminary investigation to synthesize pyrenophorin and pyrenophorol using this reaction is described.     

Influence of functional sulfonic acid groups on styrene–divinylbenzene copolymer pyrolysis

The decomposition ratio of cation exchange resin (sulfonated ST-DVB copolymer) after pyrolysis is only 50 wt%, while that of ST-DVB copolymer is 90 wt%. Fundamental experiments were performed to investigate the reason for the low decomposition ratio of the former. The cation resin consists of base polymer (ST-DVB copolymer) and functional sulfonic acid groups. Chemical analyses of the pyrolysis products showed that most of the functional groups decomposed at about 300°C and generated SO₂ gas. However, only a small amount of the base polymer was pyrolyzed even at 600°C and the total decomposition ratio was only 50 wt%. The XPS studies on the residue showed that 35% of the functional sulfonic acid groups was converted to sulfonyl and sulfur bridges between the base polymers during pyrolysis. These bridges made the base polymers, namely ST-DVB copolymer, thermally stable.     

RhI‐Catalyzed Intramolecular Carbonylative C−H/C−I Coupling of 2‐Iodobiphenyls Using Furfural as a Carbonyl Source

Synthesis of fluoren‐9‐ones by a Rh‐catalyzed intramolecular C?H/C?I carbonylative coupling of 2‐iodobiphenyls using furfural as a carbonyl source is presented. The findings indicate that the rate‐determining step is not a C?H bond cleavage but, rather, the oxidative addition of the C?I bond to a Rh^I center.     

Molecular-orbital structure in Be isotopes

The structure of ¹²Be is investigated using a microscopic α+α+4n model based on the molecular-orbit (MO) model. It is shown that the remark-able α-clustering and the contribution of the spin-orbit interaction make the binding of the state with the (3/2^?)²(1/2⁺)² configuration for the valence neutrons properly stronger in comparison with the closed p-shell (3/2^?)²(1/2^?)² configuration. The molecular-like structure of the C isotopes is also investigated using a microscopic α+α+α+n+n+... model.     

Diastereodifferentiating the [2+2] Photocycloaddition of Ethylene to Arylmenthyl Cyclohexenonecarboxylates: Stacking‐Driven Enhancement of the Product Diastereoselectivity That Is Correlated with the Reactant Ellipticity

Upon diastereodifferentiating the [2+2] photocycloaddition of ethylene to a series of p‐substituted (?)‐8‐phenylmenthyl cyclohexenonecarboxylates, the diastereoselectivity was critically controlled by the nature of the substituent introduced to the chiral auxiliary, and the p‐nitro‐substituted substrate afforded the cycloadducts in 90 % diastereomeric excess (de) and with 97 % isolated yield. Detailed experimental and theoretical conformation analyses revealed that the stacking interaction of the aromatic auxiliary with the cyclohexenone moiety plays the decisive role in determining the substrate conformation and is, therefore, responsible for the dramatic enhancement of the de. Of particular interest, the product de was directly related to the ellipticity of the substrate, enabling us to “predict” the de prior to photoirradiation.     

Surface functionalization chemistries on highly sensitive silica-based sensor chips

The surfaces of silica-based sensor chips, designed for evanescent-field-coupled waveguide-mode sensors, were functionalized using various surface chemistries. The immobilization of molecular entities on the functionalized silica surfaces was monitored using various microscopic techniques (scanning electron, fluorescence, and atomic force microscopies). Further, gold nanoparticle-based signal enhancement analyses were performed with protein conjugation on different functionalized surfaces using a waveguide-mode sensor. Based on these analyses, the sensor surfaces modified with glutaraldehyde (Glu) and carbonyldiimidazole were found to be good for molecules of different sizes. In addition, it can be inferred that the Glu-modified surface may be suitable for small molecules with diameters around 5 nm owing to its surface roughness. The modified surface with carbonyldiimidazole is suitable for the direct immobilization of larger molecules especially for biomolecular assemblies without intermediate chemical modifications.