Combinatorial and approximative analyses in a spatially random division process

For a spatial characteristic, there exist commonly fat-tail frequency distributions of fragment-size and -mass of glass, areas enclosed by city roads, and pore size/volume in random packings. In order to give a new analytical approach for the distributions, we consider a simple model which constructs a fractal-like hierarchical network based on random divisions of rectangles. The stochastic process makes a Markov chain and corresponds to directional random walks with splitting into four particles. We derive a combinatorial analytical form and its continuous approximation for the distribution of rectangle areas, and numerically show a good fitting with the actual distribution in the averaging behavior of the divisions.     

Total Synthesis of the 7,10‐Epimer of the Proposed Structure of Amphidinolide N,Part II: Synthesis of C17–C29 Subunit and Completion of the Synthesis

The total synthesis of 7,10‐epimer of the proposed structure of amphidinolide N was accomplished. The requisite chiral C17–C29 subunit was assembled stereoselectively via Keck allylation, Shi epoxidation, diastereoselective 1,3‐reduction, and a later oxidative synthesis of the THF framework. The C1–C13 and C17–C29 subunits were successfully coupled using a Enders RAMP “linchpin” as the C14–C16 three carbon unit, thereby controlling the chirality at C14 and C16. The labile allyl epoxy moiety was successfully constructed by Grieco–Nishizawa olefination at a final stage of the synthesis.     

Nonbonded P···P and P···Se Interactions in Naphthalene 1,8-Positions: Role of Lone-Pair Orbitals

The lone pair-lone pair repulsion plays an important role in the nonbonded P;;;P interaction in naphthalene 1,8-positions. The conformations around P and Se in 8-(PhSe)-1-(Ph 2 P=O)C 10 H 6 are determined by the attractive O;;;Se--C 3c-4e type interaction. The P;;;Se interaction in the 1,8-positions is also discussed.     

Grafting of Polymers Having Pendant Peroxycarbonate Groups Onto Carbon Black and Postpolymerization of Vinyl Monomers

Abstract

Postpolymerization of vinyl monomers initiated by pendant peroxycarbonate groups of grafted polymer chains on carbon black (CB) was investigated. The grafting of polymers having pendant peroxycarbonate groups onto CB was achieved by the trapping of polymer radicals formed by the thermal decomposition of copolymers of t-butylperoxy-2-methacryloyloxyethyl-carbonate (HEPO) with vinyl monomers such as vinyl acetate (VAc), styrene (St) and methyl methacrylate (MMA). The copolymers having pendant peroxycarbonate groups were prepared by copolym-erization of HEPO with vinyl monomers using azo initiator under irradiation of UV light at room temperature. The amount of remaining pendant peroxycarbonate groups of the poly(VAc-co-HEPO)-grafted CB obtained from the reaction at 90°C was maximum and decreased above the temperature. Furthermore, the postpolymerization of vinyl monomers, such as St, MMA, and VAc was initiated in the presence of poly(VAc-co-HEPO)-grafted and poly(St-co-HEPO)-grafted CB and the corresponding polymers were postgrafted onto CB to give branched polymer-grafted CB. The percentage of poly(St)-postgrafting (proportion of post-grafted poly(St) to poly(MMA-co-HEPO)-grafted CB used) increased with increasing polymerization time, but became constant at 20% after 4 hours.     

Probe Design for the Effective Fluorescence Imaging of Intracellular RNA

Over the past two decades, the spatiotemporal analysis of fluorescently labeled single RNA species has provided a broad insight into the synthesis, localization, degradation, and transport of RNA. To elucidate the dynamic behavior of functional RNAs in living cells, researchers throughout the world have proposed numerous fluorometric strategies for intracellular RNA imaging. Because, like most other biological molecules, RNA is intrinsically nonfluorescent, the development of methods for the labeling of RNAs of interest with fluorescent molecules is essential. Several artificial tag sequences have been attached onto the 3′ end of target RNAs and used as scaffolds for interacting with their fluorescent counterparts. In this Personal Account, we focus on the methods that have been developed to show how RNAs expressed in cells can be labeled and visualized by fluorescent proteins, small molecules, or nucleic acids. Each of these methods is designed to increase the sensitivity and specificity for imaging or to decrease the background fluorescence.     

Linear Multiselenium Interactions in Dicationic Oligomers of 1,5‐(Diselena)canes: Behavior of Semc σ(mcc‐nee) (6≤mc≤16) Elucidated with QTAIM Dual Functional Analysis

Invited for this month''s cover picture is the group of Dr. Satoko Hayashi at Faculty of Systems Engineering and Chemistry at Wakayama University. The cover picture shows the linear Se₁₆ σ(16c–30e) interactions, illustrated by the molecular graph type on the optimized structure of the dicationic octamer of 1,5‐(diselena)cane. HOMO‐1 of ψ₄₆₂ is drawn on the structure, which is located predominantly on the Se atoms. The optimized structure is stable, due to the nice engagement between the (CH₂)₃ moieties. The contour maps of ρ(r) are also drawn on the molecular C _s planes of the dicationic dimer and trimer to demonstrate clearly the existence of the interactions between Se atoms. Read the full text of their Full Paper at 10.1002/open.202100017.

“… To improve the causality of experimental results, we have proposed a new concept, called “Keisan‐sendo…” Find out more about the story behind the front cover research at 10.1002/open.202100017.