Data‐Driven Identification of Hydrogen Sulfide Scavengers

Hydrogen sulfide (H₂S) is an important signaling molecule whose up‐ and down‐regulation have specific biological consequences. Although significant advances in H₂S up‐regulation, by the development of H₂S donors, have been achieved in recent years, precise H₂S down‐regulation is still challenging. The lack of potent/specific inhibitors for H₂S‐producing enzymes contributes to this problem. We expect the development of H₂S scavengers is an alternative approach to address this problem. Since chemical sensors and scavengers of H₂S share the same criteria, we constructed a H₂S sensor database, which summarizes key parameters of reported sensors. Data‐driven analysis led to the selection of 30 potential compounds. Further evaluation of these compounds identified a group of promising scavengers, based on the sulfonyl azide template. The efficiency of these scavengers in in vitro and in vivo experiments was demonstrated.     

Heat Convection of Compressible Viscous Fluids: I

The stationary problem for the heat convection of compressible fluid is considered around the equilibrium solution with the external forces in the horizontal strip domain z ₀ < z < z ₀ + 1 and it is proved that the solution exists uniformly with respect to z ₀ ≥ Z ₀. The limit system as z ₀ → + ∞ is the Oberbeck–Boussinesq equations.     

Heat Convection of Compressible Viscous Fluids. II

We consider steady heat convections of compressible viscous fluids in the horizontal strip domain ${z_0 < z < z_0 + 1}$ under the gravity. Pattern formations are shown uniformly for ${z_0 \geq Z_0}$ . The limit of them as ${Z_0 \rightarrow + \infty}$ is that of Oberbeck-Boussinesq equations.     

Porous nanographene formation on γ-alumina nanoparticles via transition-metal-free methane activation

γ-Al₂O₃ nanoparticles promote pyrolytic carbon deposition of CH₄ at temperatures higher than 800 °C to give single-walled nanoporous graphene (NPG) materials without the need for transition metals as reaction centers. To accelerate the development of efficient reactions for NPG synthesis, we have investigated early-stage CH₄ activation for NPG formation on γ-Al₂O₃ nanoparticles via reaction kinetics and surface analysis. The formation of NPG was promoted at oxygen vacancies on (100) surfaces of γ-Al₂O₃ nanoparticles following surface activation by CH₄. The kinetic analysis was well corroborated by a computational study using density functional theory. Surface defects generated as a result of surface activation by CH₄ make it kinetically feasible to obtain single-layered NPG, demonstrating the importance of precise control of oxygen vacancies for carbon growth.

Oxygen vacancies on the (100) surface of γ-Al₂O₃ nanoparticles catalyse CH₄-CVD for single-layered nanoporous graphenes with no transition metal reaction centre. The rate-limiting step is the proton transfer (PT) in the activation of CH₄ on them.     

Exploiting a C–N Bond Forming Cytochrome P450 Monooxygenase for C–S Bond Formation

C–S bond formation reactions are widely distributed in the biosynthesis of biologically active molecules, and thus have received much attention over the past decades. Herein, we report intramolecular C–S bond formation by a P450 monooxygenase, TleB, which normally catalyzes a C−N bond formation in teleocidin biosynthesis. Based on the proposed reaction mechanism of TleB, a thiol-substituted substrate analogue was synthesized and tested in the enzyme reaction, which afforded the unprecedented sulfur-containing thio-indolactam V, in addition to an unusual indole-fused 6/5/8-tricyclic product whose structure was determined by the crystalline sponge method. Interestingly, conformational analysis revealed that the SOFA conformation is stable in thio-indolactam V, in sharp contrast to the major TWIST form in indolactam V, resulting in differences in their biological activities.     

Determination of elliptic curves with everywhere good reduction over real quadratic fields

All elliptic curves having everywhere good reduction over \Bbb Q(?{29})\Bbb Q(\sqrt {29}) are determined by studying the fields of 2- and 3-division points. As a byproduct of the argument, the elliptic curves over some real quadratic fields are determined. Though part of the result are already obtained in [2], [4], [5], [10], the proof given in the present paper is simpler.     

Construction of Trinervitane and Kempane Skeletons Based on Biogenetical Routes

Based on the putative biogenesis of trinervitane‐ and kempane‐type diterpenes (Scheme 1), a biogenetic‐type transformation was simulated by cyclization of 7,16‐secotrinervita‐7,11,15‐triene‐2α,3α,17‐triol ( 23 ) and of its 17‐chloro derivative 30 . The requisite substrates were prepared from geranylgeranoic acid chloride 6 (Schemes 2, 4, and 5). Treatment of 30 with AgClO₄ at −20° provided the trinervitantrienediols 32 and 33 in 68 and 5% yields, while kempadienediol 35 was obtained in 50% yield by the same reagent at +20° (Scheme 7). The structures of the cyclization products were elaborated from detailed inspection of NMR spectra including H,H COSY, C,H COSY, and NOESY (Tables 1 and 2). The conformation of 30 and its plausible cyclization intermediate was discussed with the help of physical evidence, including X‐ray crystallographic analysis.     

Optical-limiting property of cyclic phenylacetylene oligomer synthesized under high pressure

The optical-limiting property of a new cyclic phenylacetylene oligomer was investigated. Toluene solutions of the oligomer contained within a quartz cell were irradiated with the pulse from frequency doubled Nd: Yag laser at 532 nm. At low input fluence, the transmittance of the toluene solution was constant and agreed well with that obtained by spectrophotometer. At high input fluence, the transmittance of the solution above a concentration of 5 wt % decreased with input fluence. The oligomer had an optical limiting property. As the concentration of the oligomer increased from 5 to 20 wt %, the threshold for optical limiting decreased. The threshold was independent of the molecular weight. The optical limiting property was analyzed by the following equation obtained according to the reverse saturable absorption mechanism; log(I₀/I) = K(I₀ - I) + A_g, where I₀ is the input fluence, I is the output fluence, K is a parameter depending on the absorption cross section and the relaxation time, and A_g is the absorbance of the ground state. © 1996 John Wiley & Sons, Inc.     

Electro‐optic effects and phase behavior of liquid‐crystalline physical gels: self‐assembly of hydrogen‐bonded molecules for the formation of dynamically functional composites

Anisotropic physical gels of liquid crystals are obtained by the formation of non‐covalently‐bonded networks through self‐organization of low molecular weight compounds in nematic solvents. They exhibit thermoreversible transitions between isotropic liquid and isotropic gel, and between isotropic gel and liquid‐crystalline gel, whose temperatures are dependent on the components. Electro‐optic properties of liquid‐crystalline gels are examined with twisted nematic cells. A nematic liquid crystal in a gel structure can respond to electric fields twice faster than a single liquid‐crystalline component.