Composite constituent: lactucenyl acetate, a novel migrated lupane triterpenoid from Lactuca indica revision of structure of tarolupenyl acetate

Lactucenyl acetate (1), a new member of migrated lupane triterpenoids was isolated from Lactuca indica and its structure was elucidated on the basis of spectral analyses. The structure of tarolupenyl acetate was revised as lup-19(21)-en-3β-yl acetate (2).     

Ferroelectric mobile water

In molecular dynamics simulations single-domain ferroelectric water is produced under ordinary ambient conditions utilizing carbon nanotubes open to a water reservoir. This ferroelectric water diffuses while keeping its proton-ordered network intact. The mobile/immobile water transitions and the step-wise changes in net polarization of water are observed to occur spontaneously. The immobile water becomes mobile by transforming into the single-domain ferroelectric water. Our general notion of relating a more highly ordered structure with a lower temperature has so far restricted researchers' attention to very low temperatures when experimenting on proton-ordered phases of water. The present study improves our general understanding of water, considering that the term 'ferroelectric water' has so far practically stood for 'ferroelectric ice,' and that single-domain ferroelectric water has not been reported even for the ice nanotubes.     

Real-time propagation time-dependent density functional theory study on the ring-opening transformation of the photoexcited crystalline benzene

Mechanism of the ring-opening transformation in the photoexcited crystalline benzene is investigated on the femtosecond scale by a computational method based on the real-time propagation (RTP) time-dependent density functional theory (TDDFT). The excited-state dynamics of the benzene molecule is also examined not only for the distinction between the intrinsic properties of molecule and the intermolecular interaction but for the first validation using the vibration frequencies for the RTP-TDDFT approach. It is found that the vibration frequencies of the excited and ground states in the molecule are well reproduced. This demonstrates that the present method of time evolution using the Suzuki-Trotter-type split operator technique starting with the Franck-Condon state approximated by the occupation change of the Kohn-Sham orbitals is adequately accurate. For the crystalline benzene, we carried out the RTP-TDDFT simulations for two typical pressures. At both pressures, large swing of the C-H bonds and subsequent twist of the carbon ring occurs, leading to tetrahedral (sp3-like) C-H bonding. The nu4 and nu16 out-of-plane vibration modes of the benzene molecule are found mostly responsible for these motions, which is different from the mechanism proposed for the thermal ring-opening transformation occurring at higher pressure. Comparing the results between different pressures, we conclude that a certain increase of the intermolecular interaction is necessary to make seeds of the ring opening (e.g., radical site formation and breaking of the molecular character) even with the photoexcitation, while the hydrogen migration to fix them requires more free volume, which is consistent with the experimental observation that the transformation substantially proceeds on the decompression.     

Transannular cyclization of (4S,5S)-germacrone-4,5-epoxide into guaiane and secoguaiane-type sesquiterpenes

Germacrone (1) and (4S,5S)-germacrone-4,5-epoxide (2) were isolated, along with guaiane and secoguaiane-type sesquiterpenes, from Curcuma aromatica plants. Compound 2 was derived from 1 and cyclized through transannular (T-A) reactions into various guaiane and secoguaiane-type sesquiterpenes in C. aromatica. The cyclization reaction of 2 was initiated by protonation at an epoxide oxygen atom, followed by cleavage of the epoxide ring and the formation of a C-C bond between C-1 and C-5 to give guaiane-type derivatives. Acidic and thermal treatments of 2 produced twelve sesquiterpenes having guaiane and secoguaiane skeletons. The structures of these products were elucidated by spectral methods, including 2D-NMR spectroscopy. Most were identified as sesquiterpenes isolated from C. aromatica as natural products. The T-A cyclization of 2 occurred via two transition states, a cross conformation and a parallel conformation. The mechanism of the T-A cyclization reaction of 2 is discussed.     

Secure key distribution using correlated randomness in lasers driven by common random light

We propose a secure key distribution scheme based on correlated physical randomness in remote optical scramblers driven by common random light. The security of the scheme depends on the practical difficulty of completely observing random optical phenomena. We describe a particular realization using the synchronization of semiconductor lasers injected with common light of randomly varying phase. We experimentally demonstrate the feasibility of the scheme over a distance of 120 km.     

An application of EGA-MS with skimmer interface to pyrolysis behavior of DHTAM, an antibacterial and antifungal material with thermostability

An application of evolved gas analysis-mass spectrometry (EGA-MS) with skimmer interface was carried out to investigate the pyrolysis mechanism of an antibacterial and antifungal material that is expected with thermostability. The skimmer interface between a furnace and a vacuum chamber with a mass spectrometer transmitted the gaseous species, which were trapped by a general capillary interface. As a result, it became clear that the thermostability of antimicrobial activity was limited by the heat resistance of the coordinate bond between nitrogen and silver in the silver chelate.     

New antitumor sesquiterpenoids from Santalum album of Indian origin

Three new campherenane-type (1, 4, 7) and three new santalane-type (9, 11, 12) sesquiterpenoids, and two aromatic glycosides (21, 22) together with 12 known metabolites including α,β-santalols (14, 18), (E)-α,β-santalals (15, 19), α,β-santaldiols (16, 20), α-santalenoic acid (17), and vanillic acid 4-O-neohesperidoside were isolated from Santalum album chips of Indian origin. The structures of the new compounds, including absolute configurations, were elucidated by 1D- and 2D-NMR spectroscopic and chemical methods. The antitumor promoting activity of these isolates along with several neolignans previously isolated from the same source was evaluated for both in vitro Epstein-Barr virus early antigen (EBV-EA) activation and in vivo two-stage carcinogenesis assays. Among them, compound 1 exhibited a potent inhibitory effect on EBV-EA activation, and also strongly suppressed two-stage carcinogenesis on mouse skin.     

Carbon nanotube motors driven by carbon nanotube

We propose a new type of carbon nanotube (CNT) motor composed of a single-wall CNT (SWCNT) and a double-wall CNT (DWCNT), that are in mechanical contact. The rotational motion of our CNT motor is controllable by the translational motion of the SWCNT along the axis of the DWCNT. From molecular dynamics simulations, we show how our CNT motor can be driven in a controlled manner.     

Reduction of Pt usage in fuel cell electrocatalysts with carbon nanotube electrodes

The 12 wt% Pt-deposited carbon nanotube electrode gives 10% higher voltages than 29 wt% Pt-deposited carbon black and reduces the Pt usage by 60% in polymer electrolyte fuel cells with hydrogen and oxygen.     

Two‐dimensional microcavity lasers

Advances in processing technology, such as quantum‐well structures and dry‐etching techniques, have made it possible to create new types of two‐dimensional (2D) microcavity lasers which have 2D emission patterns of output laser light although conventional one‐dimensional (1D) edge‐emitting‐type lasers have 1D emission. Two‐dimensional microcavity lasers have given nice experimental stages for fundamental researches on wave chaos closely related to quantum chaos. New types of 2D microcavity lasers also can offer the important lasing characteristics of directionality and high‐power output light, and they may well find applications in optical communications, integrated optical circuits, and optical sensors. Fundamental physics of 2D microcavity lasers has been reviewed from the viewpoint of classical and quantum chaos, and recently developed theoretical approaches have been introduced. In addition, nonlinear dynamics due to the interaction among wave‐chaotic modes through the active lasing medium is explained. Applications of 2D microcavity lasers for directional emission with strong light confinement are introduced, as well as high‐precision rotation sensors designed by using wave‐chaotic properties.