Biosynthesis of Indole Diterpene Lolitrems: Radical-Induced Cyclization of an Epoxyalcohol Affording a Characteristic Lolitremane Skeleton

Lolitrems are tremorgenic indole diterpenes that exhibit a unique 5/6 bicyclic system of the indole moiety. Although genetic analysis has indicated that the prenyltransferase LtmE and the cytochrome P450 LtmJ are involved in the construction of this unique structure, the detailed mechanism remains to be elucidated. Herein, we report the reconstitution of the biosynthetic pathway for lolitrems employing a recently established genome-editing technique for the expression host Aspergillus oryzae. Heterologous expression and bioconversion of the various intermediates revealed that LtmJ catalyzes multistep oxidation to furnish the lolitrem core. We also isolated the key reaction intermediate with an epoxyalcohol moiety. This observation allowed us to establish the mechanism of radical-induced cyclization, which was firmly supported by density functional theory calculations and a model experiment with a synthetic analogue.     

Embedding of RCD⁎(K,N) spaces in L2 via eigenfunctions

In this paper we study the family of embeddings ${\mathrm{\Phi }}_t$ of a compact ${\mathrm{RCD}}^{?}(K,N)$ space $(X,\mathsf{d},\mathfrak{m})$ into $L^2(X,\mathfrak{m})$ via eigenmaps. Extending part of the classical results [10], [11] known for closed Riemannian manifolds, we prove convergence as $t\downarrow 0$ of the rescaled pull-back metrics ${\mathrm{\Phi }}_t^{?}{g}_{L^2}$ in $L^2(X,\mathfrak{m})$ induced by ${\mathrm{\Phi }}_t$. Moreover we discuss the behavior of ${\mathrm{\Phi }}_t^{?}{g}_{L^2}$ with respect to measured Gromov-Hausdorff convergence and t. Applications include the quantitative $L^p$-convergence in the noncollapsed setting for all $p<\infty$, a result new even for closed Riemannian manifolds and Alexandrov spaces.     

Topological “interfacial” polymer chemistry: Dependency of polymer “shape” on surface morphology and stability of layer structures when heating organized molecular films of cyclic and linear block copolymers of n‐butyl acrylate‐ethylene oxide

The “topological polymer chemistry” of amphiphilic linear and cyclic block copolymers at an air/water interface was investigated. A cyclic copolymer and two linear copolymers (AB‐type diblock and ABA‐type triblock copolymers) synthesized from the same monomers were used in this study. Relatively stable monolayers of these three copolymers were observed to form at an air/water interface. Similar condensed‐phase temperature‐dependent behaviors were observed in surface pressure–area isotherms for these three monolayers. Molecular orientations at the air/water interface for the two linear block copolymers were similar to that of the cyclic block copolymer. Atomic force microscopic observations of transferred films for the three polymer types revealed the formation of monolayers with very similar morphologies at the mesoscopic scale at room temperature and constant compression speed. ABA‐type triblock linear copolymers adopted a fiber‐like surface morphology via two‐dimensional crystallization at low compression speeds. In contrast, the cyclic block copolymer formed a shapeless domain. Temperature‐controlled out‐of‐plane X‐ray diffraction (XRD) analysis of Langmuir–Blodgett (LB) films fabricated from both amphiphilic linear and cyclic block copolymers was performed to estimate the layer regularity at higher temperatures. Excellent heat‐resistant properties of organized molecular films created from the cyclic copolymer were confirmed. Both copolymer types showed clear diffraction peaks at room temperature, indicating the formation of highly ordered layer structures. However, the layer structures of the linear copolymers gradually disordered when heated. Conversely, the regularity of cyclic copolymer LB multilayers did not change with heating up to 50 °C. Higher‐order reflections (d₀₀₂, d₀₀₃) in the XRD patterns were also unchanged, indicative of a highly ordered structure. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 486–498     

Effect of a topical formulation containing Calophyllum brasiliense Camb. extract on cutaneous wound healing in rats

This study evaluated the wound healing effects of topical application of an emulsion containing the HPLC-standardised extract from Calophyllum brasiliense Cambess (Clusiaceae) leaves in rats. The macroscopic analysis demonstrated that the wounds treated with the C. brasiliense emulsion healed earlier than the wounds treated with emulsion base and Dersani®. The percentage of wound healing in the group treated with the C. brasiliense emulsion was significantly higher than in the other groups at 7 and 14 days. On day 14, the animals treated with the C. brasiliense emulsion exhibited a 90.67% reduction of the wound areas. The histological evaluation revealed that on day 21, the group treated with the C. brasiliense emulsion exhibited a significant increase in fibroblasts compared with the other groups. Thus, the C. brasiliense emulsion had healing properties in the topical treatment of wounds and accelerated the healing process.     

Electrochemical Fluorination of Dithiocarbonates Using a Triarylamine Mediator

Electrochemical oxidation of O-(4-chlorobenzyl) S-methyl dithiocarbonate using tris(2,4-dibromophenyl)amine as a redox mediator was studied by cyclic voltammetric measurements. The triarylamine mediated anodic fluorodesulfurization of O-(4-chlorobenzyl) and O-(4-bromobenzyl) S-methyl dithiocarbonates provided 4-chloro- and 4-bromobenzyl fluorides, respectively in moderate yields. On the other hand, similar anodic fluorination of O-(2-phenethyl) S-octyl dithiocarbonate and O-(4-bromophenyl) S-methyl dithiocarbonate afforded 2-phenethyl trifluoromethyl ether and difluoro(methylthio)methyl 4-bromophenyl ether, respectively. Mechanistic aspects are also discussed.     

Experimental study of heat and mass transfer from a horizontal cylinder in downward air-water mist flow with blockage effect

An experimental study was made on convective heat and mass transfer from a horizontal heated cylinder in a downward flow of air-water mist at a blockage ratio of 0.4. The measured local heat transfer coefficients agree fairly well with the authors' numerical solutions obtained previously for the front surface of a cylinder over the ranges mass flow ratio 0–4.5×10⁻², a temperature difference between the cylinder and air 10–43 K, gas Reynolds number (7.9–23)×10³, Rosin-Rammler size parameter 105–168 μm, and dispersion parameter 3.4–3.7. Heat transfer augmentation, two-pahse to single-phase of greater than 19 was attained at the forward stagnation point. For heat transfer in the rear part of the cylinder, an empirical formula is derived by taking into account the dimensionless governing variables, that is, coolant-feed and evaporation parameters.     

Interaction of highly charged ions with carbon-based materials using Kobe EBIS

Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Ar^q+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials.