New diarylheptanoids from Amomum muricarpum ELMER

Two new diarylheptanoids, designated muricarpones A and B, together with three known diarylheptanoids, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, 1-(3',4'-dihydroxyphenyl)-7-(4'-hydroxyphenyl)-4-hepten-3-one, and 1,7-bis(p-hydroxyphenyl)-4-hepten-3-one, were isolated from the rhizomes of Amomum muricarpum ELMER (Zingiberaceae). Their structures were determined using spectroscopic analyses.     

New neolignans and lignans from Vietnamese medicinal plant Machilus odoratissima NEES

Four new natural neolignans and lignans, which were given the trivial names odoratisols A-D (1-4), together with (-)-licarin A, kachirachirol B, obovatifol, and machilin-I were isolated from the air-dried bark of the Vietnamese medicinal plant Machilius odoratissima NEES (Lauraceae). Their absolute structures were determined on the basis of spectroscopic analyses including circular dichroism spectra.     

Gravitational lensing and the maximum number of images

We show that in a configuration of point masses, replacing one of the point deflectors by a spherically symmetric distributed mass only introduces one extra image. This extra image is located inside the radius of the distributed mass added. We extend a result available for a set of n point masses, by showing that the maximum number of images that n distributed lensing objects located on a plane can create is N _max = 6(n − 1) + 1 for n ≥ 2. Our result is generic in that the mass density for each deflector is only constrained to diverge slower than 1/r as r approaches the center of the mass.     

Altering the landscape of viruses and bionanoparticles

In recent years, protein-based nanoparticles or bionanoparticles (BNPs), have been used as primary building blocks to generate ornate nanomaterials for a wide-range of applications. Over the past fifty years, numerous BNPs have been chemically modified or genetically engineered to function as smart drug/gene delivery vehicles, advanced vaccine vehicles, and isolated reaction vessels for inorganic, metallic, and semi-conductive depositions. These studies have contributed invaluable insights to the expansive capabilities of these simple, yet highly robust, nanosized building materials. Here we highlight some of the recent progress in the chemical modifications of BNPs and hopefully inspire the development of many new materials in the near future.     

On formulas for the velocity of Stoneley waves propagating along the loosely bonded interface of two elastic half-spaces

Formulas for the velocity of Stoneley waves propagating along the loosely bonded interface of two isotropic elastic half-spaces are derived using the complex function method. The derivation also shows that if a Stoneley wave exists, then it is unique. By using the obtained formulas, we can easily reproduce the numerical results previously obtained by Murty [G. S. Murty, Phys. Earth Planet. Interiors 11 (1975), 65–79.] by directly solving the secular equation.     

Efficient copper-induced coupling between NH-fluoroalkylated sulfoximines and aryl iodides or bromides

A high yielding, simple, and flexible copper-based system for N-arylation of fluorinated sulfoximines is reported. Best results were achieved using copper iodide in combination with DMEDA and Cs₂CO₃ to provide a wide range of N-arylated perfluoroalkylated sulfoximines. These conditions tolerate a great number of substituents on either aromatic cycle, including heteroaromatic rings, for the N-functionalization.     

Queues with boundary assistance: the effects of truncation

We study a system of two queues with boundary assistance, represented as a continuous-time Quasi-Birth-and-Death process (QBD). Under our formulation, this QBD has a ‘doubly infinite’ number of phases. We determine the convergence norm of Neuts’ R-matrix and, consequently, the interval in which the decay rate of the infinite system can lie.