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Acetylcholine (ACh), a quaternary ammonium cation, is known as one of the itch inducer in atopic dermatitis (AD), an inflammatory skin disease with intense itching. Previous research has reported accumulation of ACh in lesional site of AD patients. Generally, ACh is metabolized by cholinesterase (ChE). Therefore, one of the causes of ACh accumulation may be the suppression of ChE activity. Increased levels of the multifunctional bioactive sphingolipid sphingosylphosphorylcholine (SPC) have also been detected in AD. Since SPC possesses a quaternary ammonium cation, like ACh, it is possible that SPC affects the activity of ChE catalyzing ACh metabolization. We investigated whether SPC influences the activity of ChE by performing enzymatic analysis of ChE in the presence of SPC. We found that SPC strongly suppressed acetylcholinesterase (AChE) activity, but the suppression of butyrylcholinesterase by SPC was quite low. The Michaelis constant (Km) of AChE in the presence of SPC increased, and the maximum velocity (Vmax) decreased, indicating that SPC acts as mixed-type inhibitor for AChE. The analysis of SPC analogs clarified the importance of both the quaternary ammonium cation and the carbon chain length of SPC for the AChE inhibitory effect and showed that SPC was unique in AChE inhibition among the sphingolipids in this study. These findings indicate a novel function of SPC on AChE inhibition. Thus, the inhibition activity of SPC may be a factor in the increase of ACh in AD.

We isolated highly-purified photochemically active photosystem (PS) II reaction center (RC) complexes from the cyanobacterium Synechocystis sp. PCC 6803 using a histidine-tag introduced to the 47 kDa chlorophyll protein, and characterized their spectroscopic properties. Purification was carried out in a one-step procedure after isolation of PS II core complex. The RC complexes consist of five polypeptides, the same as in spinach. The pigment contents per two molecules of pheophytin a were 5.8 ± 0.3 chlorophyll (Chl) a and 1.8 ± 0.1 β-carotene; one cytochrome b 559 was found per 6.0 Chl a molecules. Overall absorption and fluorescence properties were very similar to those of spinach PS II RCs; our preparation retains the best properties so far isolated from cyanobacteria. However, a clear band-shift of pheophytin a and β-carotene was observed. Reasons for these differences, and RC composition, are discussed on the basis of the three-dimensional structure of complexes.

Photochemically active photosystem (PS) I complexes were purified from the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina MBIC 11017, and several of their properties were characterized. PS I complexes consist of 11 subunits, including PsaK1 and PsaK2; a new small subunit was identified and named Psa27. The new subunit might replace the function of PsaI that is absent in A. marina. The amounts of pigments per one molecule of Chl d' were 97.0 +/- 11.0 Chl d, 1.9 +/- 0.5 Chl a, 25.2 +/- 2.4 alpha-carotene, and two phylloquinone molecules. The light-induced Fourier transform infrared difference spectroscopy and light-induced difference absorption spectra reconfirmed that the primary electron donor of PS I (P740) was the Chl d dimer. In addition to P740, the difference spectrum contained an additional band at 728 nm. The redox potentials of P740 were estimated to be 439 mV by spectroelectrochemistry; this value was comparable with the potential of P700 in other cyanobacteria and higher plants. This suggests that the overall energetics of the PS I reaction were adjusted to the electron acceptor side to utilize the lower light energy gained by P740. The distribution of charge in P740 was estimated by a density functional theory calculation, and a partial localization of charge was predicted to P1 Chl (special pair Chl on PsaA). Based on differences in the protein matrix and optical properties of P740, construction of the PS I core in A. marina was discussed.

Photosynthetic light-harvesting complexes, found in aquatic photosynthetic organisms, contain a variety of carotenoids and chlorophylls. Most of the photosynthetic dinoflagellates possess two types of light-harvesting antenna complexes: peridinin (Peri)-chlorophyll (Chl) a/c-protein, as an intrinsic thylakoid membrane complex protein (iPCP), and water-soluble Peri-Chl a-protein, as an extrinsic membrane protein (sPCP) on the inner surface of the thylakoid. Peri is a unique carotenoid that has eight C=C bonds and one C=O bond, which results in a characteristic absorption band in the green wavelength region. In the present study, excitation relaxation dynamics of Peri in solution and excitation energy transfer processes of sPCP and the thylakoid membranes, prepared from the photosynthetic dinoflagellate, Symbiodinium sp., are investigated by ultrafast time-resolved fluorescence spectroscopy. We found that Peri-to-Chl a energy transfer occurs via the Peri S1 state with a time constant of 1.5 ps or 400 fs in sPCP or iPCP, respectively, and that Chl c-to-Chl a energy transfer occurs in the time regions of 350-400 fs and 1.8-2.6 ps.

DNA helicases are known to play important roles in the maintenance of genome integrity including the replication of trinucleotide repeats in the cells. Here, we report the HFM1 gene, which encodes the putative human DNA helicase. The HFM1 gene comprises 39 exons mapping to human chromosome 1p22.2. The HFM1 cDNA encompasses 4931 nucleotides with a single open reading frame (ORF) of 1435 amino acid residues encoding a predicted 172 kDa protein (hHFM1). The deduced protein sequence shares similar domain and motif structures to those of Mer3, a DNA helicase of Saccharomyces cerevisiae; seven consecutive motifs conserved among the DEXH-box type of DNA/RNA helicases at the N-terminal and a single putative zinc finger motif at the C-terminal regions of the protein. Further, the HFM1 transcript is preferentially expressed in testis and ovary. Collectively, hHFM1 is the evolutionally conserved putative human DNA helicase, which may function as a modulator for genome integrity in germ-line tissues.

Oxide-based electronic devices are expected to have fascinating properties, unlike those made from conventional semiconductors. SrTiO3 (STO) is a key material for this new field of electronics1,2,3,4,5,6,7,8,9,10,11. Here we report on blue-light emission at room temperature from Ar+-irradiated, metallic STO. The irradiation introduces oxygen deficiencies to a depth of ∼20 nm from the crystal surface. These deficiencies generate conduction carriers and stabilize a hole level in a self-trapped state. We propose a model by which the doped conduction electrons and the in-gap state produce a radiative process that results in blue-light emission. The emitting region can be patterned into any size and shape with conventional microscopic fabrication techniques.

Silk fibroin of Bombyx mori is secreted from the posterior silk gland (PSG) as a 2.3-MDa elementary unit, consisting of six sets of a disulfide-linked heavy chain (H-chain)-light chain (L-chain) heterodimer and one molecule of fibrohexamerin (fhx)/P25. Fhx/P25, a glycoprotein, associates noncovalently with the H-L heterodimers. The elementary unit was found and purified from the endoplasmic reticulum (ER) extract of PSG cells. A substantial amount of fhx/P25 unassembled into the elementary unit was also present in ER. In normal-level fibroin-producing breeds (J-139 and C108), the elementary unit contained fhx/P25 of either 30 kDa (major) or 27 kDa (minor). The 27-kDa fhx/P25 was produced from the 30-kDa form by digestion with the bacterial alpha1,2-mannosidase in vitro. The elementary unit in the ER extract contained only the 30-kDa fhx/P25, whereas both 30- and 27-kDa forms of fhx/P25 were present in the ER plus Golgi mixed extracts. In naked-pupa mutants [Nd(2), Nd-s and Nd-sD], extremely small amounts of fibroin were produced and they consisted of one molecule of 27-kDa fhx/P25 and six molecules of H-chain but no L-chain. When the Nd-sD mutant was subjected to transgenesis with the normal L-chain gene, the (H-L)6fhx1-type elementary unit containing the 30-kDa fhx/P25, was produced. These results suggest that fhx/P25 in the elementary unit is largely protected from digestion with Golgi alpha1,2-mannosidases when L-chains are present in the unit. Models suggesting a role of L-chain for the protection of alpha1,2-mannose residues of fhx/P25 are presented.

The thermotropic collapse of the hydrogel of copolymer N-isopropylacrylamide with acrylic acid (NIPA−AAc) upon heating has been studied by high-sensitivity differential scanning calorimetry. Curves of the polymer partial heat capacity have been measured at different pH (from pH 2 to 11) and different concentrations of cationic ligands: CaCl2, dodecyltrimethylammonium bromide (DTAB), and cetyltrimethylammonium bromide (CTAB). Dependencies of the main thermodynamic parameters of the gel collapsetemperature, enthalpy, and width of the transition on pH and ligand concentrationhave been obtained. It has been found that the collapse is characterized by a negative value of the heat capacity increment Δtcp. Its average value determined over all variables studied is Δtcp = −0.62 ± 0.02 J/(g K). This result is in accordance with the observed correlation between the transition enthalpy and temperature of the NIPA−AAc gel. The free energy of the collapse has been calculated as a function of pH and concentration of C...

We report the data on concurrent multiple point adsorption of two oppositely charged species of “target molecules” (aluminum ions and 1,3,6,8-pyrenetetrasulfonic sodium salt (Py-4)) by a polyampholyte gel of N-isopropylacrylamide (NIPA, 6 M) with methacrylic acid (MAA, 80 mM) and methacrylamidopropyl trimethylammonium chloride (MAPTAC, 80 mM). The goal of this study is to test the mutual frustrations created by adsorption of one species on the adsorption of the other. Understanding these frustrations is an important step toward elucidating the memory of conformations in heteropolymer systems. We found that in the absence of aluminum, the adsorption of Py-4 was suppressed by gel collapse, presumably because of an increase in MAA/MAPTAC ionic pairs that prevents the formation of potential adsorbing centers. Adding a moderate amount of aluminum significantly enhances adsorption of Py-4 by the collapsed gel, indicating that aluminum ions compete for bonds with MAA and help release vacant MAPTAC centers. Final...

Weakly cross-linked heteropolymer gels that memorize molecular pairs have been designed and synthesized. The polymer consists of a main monomer component responsible for volume phase transition, methacrylic acid that adsorbs one divalent ion as a pair, and cross-links. The memory of pairing of methacrylic acids within the gels was encoded in the primary sequence of main monomers, methacrylic acids and cross-links within the gels, which was achieved by “imprinting”, namely, by synthesizing gels while methacrylic monomers were paired prior to polymerization. The control gels, where methacrylic monomers were randomly distributed, showed frustration in forming pairs, whereas such frustration was completely diminished in the imprinted gels allowing the memory of pair formation.

スチレンオリゴマーの内分泌撹乱作用の有無を検証することを目的として, スチレンモノマー (SM), ダイマー (SD) 3検体及びトリマー (ST) 2検体に, 新たに構造決定がなされたST1検体を加え, エストロゲン受容体結合試験, アンドロゲン受容体結合試験, 甲状腺ホルモン受容体結合試験, 去勢雄ラット反応試験及びラット血清プロラクチン濃度試験を行った. その結果, これらのSM, SD及びSTはいずれの試験項目において有意な作用を示さず, 内分泌撹乱作用を有さないものと推察された.

Fibroin light (L-) chain and P25 are low molecular weight protein components of silk fibroin which are secreted from the posterior silk gland cells of the silkworm, Bombyx mori. The primary structure of L-chain was determined previously by cDNA cloning and peptide analysis, but that of P25 has only been deduced from its genomic sequence. Our previous studies with specific antibodies against L-chain and P25 have shown that L-chain and H-chain are linked by disulfide bond(s) but P25 is not covalently linked to H-chain. Here, we present evidence that P25 associates with the H-L complex primarily by hydrophobic interactions and that P25 is a glycoprotein containing Asn-linked oligosaccharide chains. From the analysis of three fibroin-secretion-deficient 'naked pupa' mutant breeds [Nd(2), Nd-s and Nd-sD], it is suggested that P25 interacts with H-chain in the absence of H-L linkage but its content of oligosaccharide is reduced when the H-L linkage is not formed. From these results, models are presented implying that the H-L complex and P25 are associated to form a higher-order complex of specific conformation during the processes of intracellular transport and secretion, and that the Asn-linked glycosylation of P25 is partially altered under such conditions.

Protein folding is one of the most challenging problems in science. How can polymers memorize and fold into unique conformations? How can they recognize molecules, catalyze chemical reactions, transfer molecular information, and create motions! The principle behind these mechanisms lies in the concept of thernodynamically stable phases of heteropolymers. Recent theories predict that the collapsed phase should be further classified into three phases: freely fluctuating like liquid, frozen in degenerate conformations, and frozen in a unique conformation. This yields a clue on how one can attempt creation artificial polymers capable to mimic some of the protein properties and functions. The reversible adsorption of target molecules is suggested as a primary means to achieve this goal. Target molecules with multiple adsorption sites play a twofold role. First, they mediate specific interactions between monomers and thus serve as “gluons”. Second, monitoring the adsorption provides the experimental possibility to test directly on monomer contacts, which is directly related to observation of the order parameter associated with heteropolymer freezing transition. A slight change in the backbone conformation alters the spacial arrangement of the group, allowing for reversible adsorption and release. Polymer gels are developed that can reversibly change their affinity to target molecules by orders of magnitude. The gels are made of copolymers of backbone monomers that can reorganize themselves through thermal volume phase transition and of monomers that can attract the target at multiple contact points. Further the gels “imprinted” with the target showed a marked increase in the affinity, thus mimicing a protein-like ability to memorize and recognize certain target.

Powder silica and elemental silicon enriched with 30Si were prepared at the request of nuclear physicists who had needed the isotopic samples for their research on neutron-rich nuclei. The enrichment of 30Si was performed by means of the IRMPD of Si2F6 to SiF4 using a CO2 laser. The 30Si-enriched SiF4 was further converted either to silica by hydrolysis with aqueous ammonia or to silicon by LiAlH4 reduction to SiH4 followed by its thermal decomposition. As the final products we obtained 11.35 g of silica with 20.6% 30Si, and 3.06 g of silicon with 17.5% 30Si.

The antioxidant activities of ten thiobisphenols were evaluated by an oxygen-absorption method at 60°C in tetralin and determination of peroxide values at 160°C in paraffin. For the 4,4′-thiobisphenols, alkyl groupsortho to the phenolic hydroxyl groups increased the induction period compared to that of other thiobisphenols for both oxidation of tetralin and paraffin. The data on electrochemical oxidation potentials that were determined by linear-sweep voltammetry and the13C nuclear magnetic resonance chemical shifts (δ) of these compounds were associated with antioxidant activities. In particular, the activities exhibited during the induction period closely correlated with the13C chemical shifts of ipso-carbon of the OH substituent.

We present the operation of indirectly pumped InGaAs/InAlAs THz quantum-cascade lasers of which active/injector structures were grown by MOVPE. A laser exhibits a low threshold-current-density of ∼560 A/cm2 at 7 K and a T max ∼84 K.

Ultrasmall CdS particles, whose average size was controlled by thiols to range from 2 to 4 nm, were embedded in poly(vinyl alcohol) films. Shift of the fluorescence peak associates with the shift of the absorption threshold of the films, and the fluorescence intensity increases with the decrease in the size of CdS. Laser ablation at 308 nm was investigated by monitoring the emission spectra. Third-harmonic generation was measured for various sizes of CdS particles, and the optical nonlinearity in the nonresonance region was found to remain almost constant in the diameter range studied. © 1993 John Wiley & Sons, Inc.

Swelling equilibrium of poly(acrylic acid) (PAA) gels in aqueous poly(ethylene glycol) (PEG) solutions has been studied. First order volume transition was observed as the concentration of PEG was varied. The pH of the solution and the molecular weight of PEG are the key factors in determining the phase behavior of the PAA gel in this system. The transition concentration of PEG varies many orders of magnitude for different molecular weights. PEG with molecular weight 600 does not induce a transition. Reentrant phase transition was observed for the molecular weight of 18 500. Namely, at low PEG concentrations, the PAA gel is swollen; as the concentration is increased the gel collapses, but swells again as PEG is further added to the solution. PEG and PAA are known to form a polycomplex through hydrogen bonds. As the hydrogen bonds are formed, the hydrophilic side of polymers are hidden and the polymers become effectively hydrophobic, inducing the collapse. A simple theoretical model is presented to qualitatively explain the phenomena.

Thermal diffusion columns, consisting of water-cooled glass tubes and a coaxial red-hot metal wire, were applied as the reactor to dehydrogenative coupling of ethylene or C4 hydrocarbons. This application was intended to separate hydrogen spontaneously from other products, especially from aromatics, leading to enhanced yields. Hydrogen gas would ascend the red-hot wire, while the aromatics would descend the cold glass walls. When the metal wire was actually red-hot in the reactant hydrocarbon flow, oily products were really formed, most of which were mono- and bicyclic aromatic compounds such as benzene, styrene, and naphthalene. Product distributions were measured for different reactant species, wire metals, wire temperatures, and a few additional variables. Especially notable was the selective formation of 4-vinyl-1-cyclohexene from 1,3-butadiene at relatively low temperatures near 600 °C.

An ab initio molecular orbital theory has been applied to a study of the hydrogen abstractions of phenolic antioxidants in the chain process of autoxidation. The optimum structures of phenols, of peroxides, and of those compounds in the transition states were obtained with a Hartree–Fock/STO-3G basis set. From the values of enthalpy (ΔH) and activation energy (Ea) obtained, it was found that the rates of the reaction of peroxyl radical with phenolic antioxidant were faster than those with organic substrate in the propagation, and that the effect of the aromatic ring of the antioxidants not only stabilized a product state but also decreased an energy level in the transition state. The para-substituent effect that an electron-releasing substituent increased the antioxidant activity, whereas an electron-withdrawing one decreased it, was recognized. The relationship between ΔH and Ea values followed the Evans–Polanyi rule. The transition states in the hydrogen abstractions with lower Ea values prefer reactant...

Spectral properties, particularly fluorescence spectra and their time-dependent behavior, were investigated for a mutant of the cyanobacterium Synechocystis sp. PCC 6803 lacking the 43 kDa chlorophyll-protein (CP43, PsbC). Lack of CP43 was confirmed by a size shift of the corresponding gene and by Western blotting. The CP43-deletion mutant grown under heterotrophic conditions accumulated a small amount of photosystem (PS) II, but virtually no PS II fluorescence was observed. A 686-nm fluorescence band was clearly observed by phycocyanin excitation, coming from the terminal pigments of phycobilisomes. In contrast, no PS I fluorescence was detected by phycocyanin excitation when accumulation of PS II components was not proved by a fluorescence excitation spectrum, indicating that energy transfer to PS I chlorophyll a was mediated by PS II chlorophyll a. Direct connection of phycobilisomes with PS I was not suggested. Based on these fluorescence properties, the energy flow in the CP43-deletion mutant cells is discussed.

3n a previous report, we demonstrated in vivo ameliorating effects of conjugated estrogen in women suffering from senile dementia-Alzheimer's type. To investigate the effects of estrogen on the growth of cholinergic neurons, the present study was performed using rat cholinergic tissue implanted into the anterior chamber of the eye. Fetal diagonal band tissue containing cholinergic neurons was grafted into the anterior eye chamber of adult female rats that had either been treated or not with 2 mg estradiol valerate injected every 3 days after oophrectomy. Two and four weeks after transplantation, the axonal and/or dendritic growth of cholinergic neurons in the graft was studied using acetylcholinesterase histochemistry. At both times, acetylcholinesterase positive processes were densely distributed in the grafts of estradiol valerate treated rats, while in rats without estradiol valerate treatment acetylcholinesterase positive reaction was essentially localized only on the cell bodies. These findings were more obvious at 2 weeks after transplantation than at 4 weeks. These results suggest that estrogen acts on cholinergic neurons as a growth factor.

The effects of a diet supplemented with branched-chain amino acids (BCAA; 4.8% or 6.2%) on BCAA catabolism and glycogen metabolism in rats were examined. Rats were fed a BCAA diet or control diet for 4 wk and part of the rats were subjected to exercise training during the experimental period. Feeding the BCAA diet increased serum BCAA concentrations and activity of the hepatic branched-chain alpha-keto acid dehydrogenase complex, the rate-limiting enzyme in the catabolism of BCAA, suggesting that dietary BCAA promotes BCAA catabolism. Although the serum glucose concentration and glycogen contents in the liver and gastrocnemius muscle of rested rats were not significantly affected by feeding of the BCAA diet, those in rats exhausted by acute exercise were 2-4-fold higher in rats fed the BCAA diet than in rats fed the control diet. The activity of pyruvate dehydrogenase complex in the liver and gastrocnemius muscle after acute exercise showed reverse trends; the complex activities (especially in liver) tended to be less in the BCAA diet group than in the control diet group. These results suggest that dietary BCAA spares glycogen stores in liver and skeletal muscle during exercise and that the decrease in pyruvate dehydrogenase complex activity in these tissues by dietary BCAA is involved in the mechanisms.

We report an experimental realization of a gel system in which frustrations exist and can be minimized, thus meeting two crucial criteria predicted to enable memory of conformations in polymers. The gels consist of a thermosensitive major monomer component and two minor components. One minor component is positively charged and will form complexes around negatively charged target molecules placed in solution. The complexes can be imprinted into the gel by then cross-linking the second minor component, which will form cross-links additional to those in the major polymer matrix. The complexes are destroyed and reformed upon swelling and reshrinking of the gels, showing that memorization has been achieved.

A general approach is presented for creating polymer gels that can recognize and capture a target molecule by multiple-point interaction and that can reversibly change their affinity to the target by more than one order of magnitude. The polymers consist of majority monomers that make the gel reversibly swell and shrink and minority monomers that constitute multiple-point adsorption centers for the target molecule. Multiple-point interaction is experimentally proven by power laws found between the affinity and the concentration of the adsorbing monomers within the gels.

A new sesquiterpene alcohol has been isolated as a racemate from the title alga. The absolute structure of each enantiomer resolved by means of HPLC using chiral supports, was determined by the correlation with the synthetic intermediate, whose absolute structure was established by X-ray crystallographic analysis.

In order to evaluate the endocrine-disrupting effects of the styrene oligomers in polystyrene, used in cups for instant noodles, we examined the effects of styrene monomer (SM), styrene dimers (SD: NSD-01, 08, 09) and styrene trimers (ST: NST-01, 02, 03) on the estrogen receptor (ER) binding assay, the androgen receptor (AR) binding assay, the proliferation of MCF-7 human breast cancer cells, the steroidogenesis in Leydig cells of rats and the uterotrophic assay of immature rats. SM, SD and ST did not significantly bind to ER or AR of rats, did not induce the proliferation of MCF-7 cells, did not inhibit testosterone production in Leydig cells of rats, and did not induce estrogen-like alteration in the uterus and vagina of immature female rats. Therefore, it appears that these SM, SD and ST have no endocrine-disrupting effects through ER, AR and steroidogenesis mechanisms.

Deuteration of 4-t-butyl-1-cyclohexenyl methyl ether was carried out at 80 °C in cyclohexane under pressure. Over Ru, Rh, and Pd, the reaction products consisted almost entirely of the cis and trans mixtures of the corresponding saturated ethers (cis- and trans-4-t-butyl-1-cyclohexyl methyl ether), whereas over Os, Ir, and Pt, hydrogenolysis to t-butylcyclohexane was not negligible. The isomeric mixtures were separated and analyzed for isotopic distributions by mass spectrometry (MS) and for deuterium positions within each molecule by NMR spectroscopy. With most catalysts, the MS-determined isotopic distribution pattern for the cis ether was quite different from that of the trans ether. Also the NMR-based deuterium distributions were markedly different between these isomers. These dissimilarities can be best explained by assuming a few staggered αβ-diadsorbed species as intermediates in enol ether hydrogenation.

The reaction profiles of consecutive hydrogenation A → B → C (A. geraniol; B, citronellol; C, 3,7-dimethyloctanol) were compared for Ir and IrCl 2 H(Pph 3 ) 3 catalysts. The results suggest that on both catalysts this seemingy consecutive reaction is essentially simultaneous, B ← A → C, both B and C being formed from A through a common intermediate. The hydrogenation of A on IrCl 2 H(Pph 3 ) was accelerated by the addition of H 2 O 2 . Acceleration by H 2 O 2 addition was also noted for the hydrogenation of allyl alcohol and diethyl fumarate.

Four catalysts (Ru, Rh, Ru(PPh3)3Cl2, and Rh(PPh3)3Cl) were compared using geraniol (A) as a substrate in hydrogenation at high pressures. With all the catalysts, A was first hydrogenated mainly to citronellol (B) and then further to 3,7-dimethyloctanol (C), accompanied by the formation of a few side products. Analysis of the kinetic data suggests that this seemingly consecutive reaction sequence A → B → C is mechanistically regarded as a simultaneous process B → A → C on heterogeneous catalysts although for homogeneous catalysts it is indeed consecutive. No hydrogenolysis accompanied the hydrogenation in homogeneous catalysis, whereas in heterogeneous catalysis, hydrogenolysis to 2,6-dimethyloctane was not negligible. The Rh complex was unique in its significant activity for hydrogen transfer to produce aldehydes, namely, citronellal and 3,7-dimethyloctanal. A mechanism is presented for each of the homogeneous and heterogeneous catalyses.

Methylenecyclohexane and its 2-methyl derivative were hydrogenated competitively in cyclohexane at 30 °C over platinum group metals. The methyl derivative was less reactive than the unsubstituted olefin on all the metal catalysts used. The reactivity of the methyl derivative relative to the unsubstituted olefin was not much different in going from one catalyst to another. However, Pd was unique in its very high activity for double bond migration. MINDO/2 calculations have revealed that the olefinic double bonds of the substituted and unsubstituted olefins are essentially identical in bond order but somewhat different in charge density. The observed methyl substituent effect is compared with that observed previously in hydrogenation of cyclohexanone and its 2-methyl derivative.

Substituent effects in platinum-metal-catalyzed hydrogenation were studied using 4-substituted cyclohexanones (substituent = OH, OMe, Cl, COOEt, Ph, C 6 H 11 , COOH, NMe 2 ) as reaction substrates. The hydrogenation rates of these derivatives were compared with that of cyclohexanone in both individual and competitive reactions. Despite the employment of several different metals and a variety of substituents, including acidic COOH and basic NMe 2 , all of the relative rates fell within a rather limited range: 0.05–6.3 for competitive reactions and 0.10–2.1 for individual reactions. An analysis of these relative rate data indicates that in most cases the adsorption strength of the substituent-bearing cyclohexanones is greater than that of cyclohexanone, thus suggesting an attractive substituent-metal surface interaction. Palladium was distinguished from other platinum-group metals in its unusual weakness of carbonyl adsorption. In order to better understand the substituent effects of COOH and NMe 2 , the effects of acid and base addition were also examined.

Cyclohexanone (1) and its 2-alkyl derivatives (2-methyl-, 2-ethyl-, and 2-propylcyclohexanone (2m, 2e, and 2p)) were hydrogenated both individually and competitively in pairs (1+2) in cyclohexane using Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3 as catalysts. For all the catalysts, the reaction rates in competitive reaction decreased in the sequence, l>>2m>2e>2p, while those in individual reaction were in the relation, 1>2m≈2e≈2p. By the analysis of these kinetic data, the relative values of adsorption equilibrium constants have been estimated for 2m, 2e, and 2p. These experimental values are in good agreement with the theoretical ones which have been derived on the basis of statistical mechanics using an adsorption model characterized by immobile adsorption of the substrate ketones.

The catalytic reactions between 2-methylcyclohexanone and deuterium on platinum group metals were studied by means of mass and NMR spectrometry. Over Ru, Os, and Ir, only reduction to the corresponding alcohols occurred, brought about by simple addition of two deuterium atoms to the carbonyl bond. In contrast, over Rh and Pd, significant isotopic exchange at the C 2 and C 6 positions also occurred. The results over Pt were intermediate between these two groups. The axial and equatorial deuterium contents at each carbon position were also estimated for Rh and Pd. One characteristic feature was that, over Rh, the axial D content at C 6 is greater than that at C 2 and the reverse is true over Pd. A reaction mechanism for reduction and exchange is presented and discussed.

Three samples of LaCoO/sub 3/ were prepared by two different methods and calcined at 800 or 1000/sup 0/C. They had BET areas of 1, 12, and 16 m/sup 2//g and all of them showed pure perovskite X-ray diffraction patterns with identical unit cell dimensions. In a series of experiments the oxide, having larger surface area, was stepwise reduced in hydrogen at temperatures between 60 and 500/sup 0/C. The XPS spectra, taken at room temperature after evacuation at 400/sup 0/C at each reduction level, showed that the surface concentration of Co/sup 0/ was very low up to 300/sup 0/C but increased sharply between 300 and 350/sup 0/C (9-75%). This concentration further increased to 100% after 10 min reduction at 450/sup 0/C, but upon heating in hydrogen for an additional 10 min at 500/sup 0/C it decreased again to 75%. In another series of experiments the mixed oxide was reoxidized after each reduction. A fresh sample was reduced to 350 and 400/sup 0/C by contacting with hydrogen for 1 hr and evacuated at temperatures between 400 and 500/sup 0/C. Both high evacuation temperatures and reduction at 400/sup 0/C during 1 hr produced a sharp decrease in Co/sup 0/ surface concentration. These resultsmore » are consistent with the catalytic behavior of this perovskite reported earlier by E. A. Lombardo et al. A model is proposed to interpret the reduction of LaCoO/sub 3/.« less

Cyclohexanone and one of its methyl-substituted derivatives (2-, 3-, or 4-methylcyclohexanone) were hydrogenated competitively in pairs in cyclohexane solvent at 30 °C over group VIII metal catalysts. All of the methyl-substituted ketones were less reactive than cyclohexanone. The reactivity of a methylcyclohexanone relative to cyclohexanone was dependent upon the reaction mechanism and the atomic radius of the catalyst. INDO calculations, on the other hand, revealed that the carbonyl groups of the substituted and unsubstituted ketones are nearly identical in charge distribution and bond order, thus suggesting that the methyl substituent effect upon the hydrogenation rate is due primarily to steric hindrance to adsorption.

The antioxidative activities of nineteen compounds of seven series of alkylidene- and benzylidenebisphenols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin. The electrochemical oxidation potentials determined using linear-sweep voltammetry and the 13C NMR chemical shifts (δ) of these compounds were obtained. These data were associated with the antioxidative activities. In particular, the activities exhibited by the induction period (min) were found to closely correlate with the 13C chemical shifts of the ipso-carbon of the OH substituent (corr. coeff.=0.991). Very good activities have been observed with a series of 2,2′-alkylidene- and benzylidenebis(4,6-dimethylphenol) derivatives.

2-Methyl and 2-ethyl derivatives of cyclohexanone were allowed to react with deuterium in tBuOD using platinum group metals as catalysts. The product alcohols and the remaining ketone were examined by mass spectrometry. Over Ru, Os, and Ir, the simple addition of two deuterium atoms to the carbonyl linkage was predominant, accompanied by little isotopic exchange. Over Pt, however, isotopic exchange was significant and over Rh and Pd quite extensive. The samples obtained over Rh and Pd were further analyzed by NMR spectroscopy to determine the loci of the incorporated deuterium atoms. Deuterium exchange over Pd was almost entirely confined to the C(2) and C(6) positions, while that over Rh was smeared beyond these positions. These results can be accounted for by assuming the intermediacy of π-absorbed π-oxaallylic species on Pd and of αβ-diadsorbed species on Rh.

The photochemistry of ethylindium(III) tetraphenylporphyrin, C/sub 2/H/sub 5/In/sup III/TPP, in benzene solutions was studied by steady light and laser flash photolysis. From the analysis of the products, the C/sub 2/H/sub 5/-In bond in C/sub 2/H/sub 5/In/sup III/TPP was confirmed to be photodissociated. The quantum yields for the photodecomposition of C/sub 2/H/sub 5/In/sup III/TPP were found to be diminished by the addition of ferrocene. However, 2,4,7-trinitro-9-fluorenone, a strong electron acceptor, was found to increase the quantum yields. The laser photolysis studies revealed that the photoreaction of C/sub 7/H/sub 5/In/sup III/TPP occurs via the triplet state originating from the porphyrin ligand.

Cyclohexanone (1) and one of its 2-alkyl (methyl, ethyl, or propyl) derivatives (2) were hydrogenated competitively at 30 °C in cyclohexane over platinum group metals. The alkyl derivatives 2 were all less reactive than 1 on all the catalysts used. The relative reactivity R2⁄R1 was given by log10(R2⁄R1)=σ**+k, with σ** depending only upon the substituent and k upon the catalyst. The greater the substituent size, the more negative was the substituent constant σ**. The catalyst-dependent constant K was in general more negative for a catalyst metal having a smaller atomic radius. The above empirical rate expression has been interpreted based on the absolute reaction rate theory. The σ** values calculated on this theoretical ground were in excellent agreement with the observed values.

15Nをトレーサーとして用い, 二重促進鉄触媒上, 470℃でアンモニア分解反応の動力学的研究を行なった。とくに問題としたのは, アンモニア分解反応のなかの2つの段階, (I) アンモニアの吸着水素原子と吸着窒素原子への分解と (III) 吸着窒素の脱離のうちいずれの段階が律速的かということであった。律速段階の化学量数νrの実測値は1に近く, このことは (III) の段階が律速的であることを示唆している。なお, (I) の段階の速度を (III) のに比べると4～10倍程度大きかった。しかるに前報における430℃のデータではこの比はもっとはるかに大きかった。これらの結果は, 高温においては (I) の段階が律速的になることを暗示している。

In order to gain some insight into the mechanism of ketone hydrogenation to alcohol, cyclohexanone was deuterated over platinum metal catalysts under elevated pressure at 80 °C. The straightforward addition of two deuterium atoms to the carbonyl linkage was predominant over the heavy triad (Os, Ir, Pt). In contrast, the deuteration over the light triad (Ru, Rh, Pd) was accompanied by considerable isotopic exchange at the C-2 or C-6 position, leading to substantial proportions of the polydeuterated alcohols. A mechanism for cyclohexanone hydrogenation is presented which consists of three interlinked hydrogenation paths each having a different half-hydrogenated intermediate. The deuterium incorporation into the C-2 or C-6 position is attributable to alternation between the 1-monoadsorbed and 1,2-di-adsorbed intermediates.

The rates of hydrogenation of cyclohexanone and its 2-alkyl derivatives have been measured using decalin as the solvent in a temperature range of −5 to 68 °C over Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3 catalysts. As predicted previously, 2-methyl-, 2-ethyl-, and 2-propylcyclohexanone have exhibited nearly identical temperature dependencies in adsorption and hydrogenation, while cyclohexanone and 2-isopropylcyclohexanone had quite different dependencies.

A series of TiO2 catalysts loaded with transition metals were prepared by photodeposition. The activity order for these catalysts in the title reaction was as follows: Pt/TiO2>Rh/TiO2>Pd/TiO2>Ru/TiO2>Ir/TiO2>TiO2. Upon heat treatment the activities of all the metal/TiO2 catalysts were enhanced, but the above sequence was unaltered.

Cyclohexanone (1) and one of its 2-alkyl (methyl, ethyl, or propyl) derivatives (2) were hydrogenated competitively at 30 °C in cyclohexane over platinum group metals. The alkyl derivatives 2 were all less reactive than 1 on all the catalysts used. The relative reactivity R2⁄R1 was given by log10(R2⁄R1)=σ**+k, with σ** depending only upon the substituent and k upon the catalyst. The greater the substituent size, the more negative was the substituent constant σ**. The catalyst-dependent constant K was in general more negative for a catalyst metal having a smaller atomic radius. The above empirical rate expression has been interpreted based on the absolute reaction rate theory. The σ** values calculated on this theoretical ground were in excellent agreement with the observed values.

Several Pt/TiO2 catalysts were prepared by photodeposition from aqueous H2PtCl6 in the presence or absence of a CH3COOH–CH3COONa buffer. The examination of these catalysts by X-ray photoelectron spectroscopy (XPS) revealed that the higher the buffer concentration, the more highly reduced the deposited platinum became.

Cyclohexanone (1) and its 2-alkyl derivatives (2-methyl-, 2-ethyl-, and 2-propylcyclohexanone (2m, 2e, and 2p)) were hydrogenated both individually and competitively in pairs (1+2) in cyclohexane using Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3 as catalysts. For all the catalysts, the reaction rates in competitive reaction decreased in the sequence, l>>2m>2e>2p, while those in individual reaction were in the relation, 1>2m≈2e≈2p. By the analysis of these kinetic data, the relative values of adsorption equilibrium constants have been estimated for 2m, 2e, and 2p. These experimental values are in good agreement with the theoretical ones which have been derived on the basis of statistical mechanics using an adsorption model characterized by immobile adsorption of the substrate ketones.