Shape-selective alkylation of biphenyl catalyzed by H-Mordenites

Liquid phase alkylation of biphenyl was studied over large pore zeolites. Selective formation of the narrowest products, 4,4′’-diisopropylbiphenyl (4,4′’-DIPB), occurred only over HM among the zeolites with twelvemembered pore openings. These shape-selective catalyses are ascribed to steric restriction of transition state and to entrance of bulky substrates into the pores. The dealumination of HM enhanced catalytic activity and the selectivity of 4,4′’-DIPB because of the decrease of coke-deposition, while the activity and the selectivity were low over HM with the low SiO₂/Al₂O₃ ratio. Non-regioselective catalysis occurs on external acid sites because severe cokedeposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with propylene pressure and/or with reaction temperature. 4,4′’-DIPB yielded selectively under high propylene pressure (<0.3 MPa) at 250 °C, while the selectivity of 4,4′’-DIPB decreased under such low propylene pressure as 0.2MPa. Selective formation of 4,4′’-DIPB was observed at moderate temperature such as 250 °C, whereas the decrease of the selectivity of 4,4′’-DIPB occurred at higher temperature as 300 °C. However, 4,4′’-DIPB was almost exclusively isomer in the encapsulated DIPB isomers inside the pores under every pressure and temperature. These decreases of the selectivity of 4,4′’-DIPB are due to the isomerization of 4,4′’-DIPB on the external acid sites. The deactivation of external acid sites of HM was examined to reduce non-regioselective alkylation and isomerization. External acid sites were deactivated by calcination after impregnation of cerium on HM without the decrease in pore radii. Selectivities of 4,4′’-DIPB were improved even at high temperatures in the isopropylation of biphenyl because of the suppression of non-regioselective alkylation and isomerization at the external acid sites. The selectivity of 4,4′’-diethylbiphenyl (4,4′’-DEBP) in the ethylation of biphenyl was much lower than that in the isopropylation. Among the DEBP isomers, 4,4′’-DEBP has the highest reactivity for the ethylation to polyethylbiphenyls inside the pores, whereas the isopropylation of 4,4′’-DIPB was negligibly low inside the pores. These differences are ascribed to the difference in steric restriction at the transition state composed of substrate, alkylating agent, and acid sites inside the pores.     

The Hydroamination of methyl acrylates with amines over zeolites

H-form zeolites, H-FAU and H-BEA have been studied as heterogeneous catalysts for the hydroamination. They catalyzed the reaction of methyl acrylate with aniline to give N-[2-(methoxycarbonyl)ethyl]aniline (1) as a main product. H-BEA and H-FAU zeolites efficiently catalyzed the hydroamination to afford anti-Markovnikov adduct as a main product. The conversion of aniline around 55–85% was achieved within 18 h over H-BEA and H-FAU zeolites with SiO₂/Al₂O₃ molar ratio of 25–30; however, the formation of N,N-bis[2-(methoxycarbonyl)ethyl]aniline (2) as a product of double addition of methyl acrylate to aniline has also been observed as a by-product over H-BEA and H-FAU catalysts. The influences of the reaction parameters such as temperature and catalyst amount, and type of α,β-unsaturated esters and amines have been also investigated.     

Characterization of mutant myosins of Dictyostelium discoideum equivalent to human familial hypertrophic cardiomyopathy mutants. Molecular force level of mutant myosins may have a prognostic implication

Recent studies have revealed that familial hypertrophic cardiomyopathy (FHC) is caused by missence mutations in myosin heavy chain or other sarcomeric proteins. To investigate the functional impact of FHC mutations in myosin heavy chain, mutants of Dictyostelium discoideum myosin II equivalent to human FHC mutations were generated by site-directed mutagenesis, and their motor function was characterized at the molecular level. These mutants, i.e., R397Q, F506C, G575R, A699R, K703Q, and K703W are respectively equivalent to R403Q, F513C, G584R, G716R, R719Q, and R719W FHC mutants. We measured the force generated by these myosin mutants as well as the sliding velocity and the actin-activated ATPase activity. These measurements showed that the A699R, K703Q, and K703W myosins exhibited unexpectedly weak affinity with actin and the lowest level of force, though their ATPase activity remained rather high. F506C mutant which has been reported to have benign prognosis exhibited the least impairment of the motile and enzymatic activities. The motor functions of R397Q and G575R myosins were classified as intermediate. These results suggest that the force level of mutant myosin molecule may be one of the key factors for pathogenesis which affect the prognosis of human FHC.     

Recursive learning method for knowledge-based planning system

In the status selection planning system, which is a kind of knowledge-based planning system, the quality of the solution depends on the status selection rules. However, it is usually difficult to acquire useful knowledge from human experts. The learning method of a status selection rule using inductive learning is proposed. The status selection rules are divided into several stages according to the planning process. Gathering a training set and learning a part of the knowledge inductively are repeated one by one from the previous stage rules. From the result of application to a job-shop problem, the effectiveness of the proposed method is shown.     

The promoter function of molybdenum in Rh/Mo/SiO2 catalysts for CO hydrogenation

A series of Rh/Mo/SiO₂ catalysts with fixed Rh and different Mo contents were studied by FT-IR, chemisorption and CO hydrogenation. The FT-IR results at room temperature under CO atmosphere indicate that the addition of Mo to Rh/SiO₂ suppresses the linear and bridged CO species and promotes the twin CO species, which is consistent with the chemisorption results. It is suggested that the Mo promoter works via stabilization of Rh^1– ions and the coverage of Rh sites. The molybdenum promotes the formation of oxygenates and shifts the selectivity from hydrocarbons to oxygenates.     

Anti-atherogenicity in women does not prevent restenosis after balloon angioplasty

To test the hypothesis that anti-atherogenicity in women exerts beneficial effects to prevent restenosis formation after coronary angioplasty, we studied 493 men (988 lesions) and 81 women (159 lesions), aged 40-60 years, who had undergone successful balloon angioplasty and had follow-up angiography, 4.9 +/- 4.1 months later. We compared the extent of restenosis between men and women, and between pre- and post-menopausal women, which was assessed by a categorical definition of restenosis (more than 50% diameter stenosis at follow-up) and by percent diameter measured immediately after angioplasty and at follow-up. Hypertension was more frequent in women and a significantly lower percentage of women smoked. In women, the levels of total cholesterol and low-density lipoprotein cholesterol were higher. The location of dilated lesions, frequency of angioplasty for lesions with chronic total occlusion, and frequency of emergency angioplasty in patients with unstable angina or acute myocardial infarction were similar in men and women. Restenosis formation, estimated by the categorical definition or percent diameter, did not differ between men and women, or between pre- and post-menopausal women. Menopausal status or sex was not an independent predictor of restenosis by multivariate analysis. Thus, the benefit of anti-atherogenicity in women does not play an important role in preventing restenosis after coronary angioplasty.     

Effect of lateral forces on the movement of myosin-coated beads on actin cables studied using a centrifuge microscope

We developed an in vitro motility assay system, in which myosin-coated polystyrene beads were made to slide on actin filament arrays (actin cables) in giant algal cells and subjected to centrifugal forces, which were parallel to the direction of bead movement to serve as external loads on actin-myosin sliding (Oiwa et al. (1990) Proc Natl Acad Sci USA 87: 7893-7897), and succeeded in determining the steady-state force-velocity relation of ATP-dependent actin-myosin sliding. To give further information about the properties of actin-myosin sliding, we have applied centrifugal forces, in parallel with the plane of actin-myosin sliding but at right angles with the direction of bead movement, and have found that such "lateral" centrifugal forces reduced the velocity of bead movement. In addition, we have also found that the velocity of bead movement is reduced more markedly with lateral forces applied from the left side of the bead ("left" lateral forces) than those applied from the right side of the bead ("right" lateral forces). These results are discussed in connection with the direction of sliding force generated by the myosin heads on the bead which interact with the right-handed double helix of actin monomers constituting actin filaments.     

Teleoperation of robot arm with position measurement via angle-pixel characteristic and visual supporting function

In this paper, a teleoperation system of a robot arm with position measurement function and visual supporting function is developed. The working robot arm is remotely controlled by the manual operation of the human operator and the autonomous control via visual servo. The visual servo employs the template matching technique. The position measurement is realized using a stereo camera based on the angle-pixel characteristic. The visual supporting function to give the human operator useful information about the teleoperation is also provided. The usefulness of the proposed teleoperation system is confirmed through experiments using an industrial articulated robot arm.     

Giant domain formation in Langmuir-Blodgett films based on Alkylammonium-Au(dmit)2 salt

The crossed polarized-light microscopy has revealed that the as-deposited LB film of the 2C₁₄-Au(dmit)₂ salt consists of giant domains of several hundred microns, which have a uni-axial molecular arrangement. By the electrochemical oxidation, the giant domains disappear and smaller domains of 5-10 μm appear. According to the atomic force microscopy (AFM) observation, the as-deposited film consists of domains of several microns but it appears that the observed domains are fragments formed by cracks generated in much larger domains, as seen by the shapes. It is hypothesized that there exist giant domains at the air/water interface but cracks are made during the transfer process. Thus, the uni-axial molecular arrangement is kept over the macroscopic range. Considering the random potentials set up by grain boundaries and/or defects, fabrication of the crack-free LB film is considered to be indispensable for realizing metallic properties down to much lower temperatures and global superconductivity.     

Selective Isopropylation of Isobutylbenzene over H-Mordenite in Supercritical CO2 Medium: Remarkable Enhancement in Catalytic Activity and Selectivity for 4-Isobutylcumene

Remarkable enhancement in the catalytic activity and selectivity for the formation of 4-isobutylcumene (4-IBC) was observed in the isopropylation of isobutylbenzene (IBB) over highly dealuminated H-mordenite in supercritical CO₂ (sc-CO₂) medium. Thermogravimetric analyses confirm that reduced coking of the catalysts in sc-CO₂ medium and stronger acid sites in dealuminated H-mordenite (MOR) are the key factors for superior activity and selectivity for 4-IBC.