In silico design, synthesis and evaluation of 3'-O-benzylated analogs of salacinol, a potent α-glucosidase inhibitor isolated from an Ayurvedic traditional medicine "Salacia"

With the aid of an in silico method, α-glucosidase inhibitors with far more potent activities than salacinol (1), a potent natural α-glucosidase inhibitor isolated from an Ayurvedic traditional medicine Salacia reticulata, have been developed.     

Andirolides H–P from the flower of andiroba (Carapa guianensis,Meliaceae)

Three new gedunins, an andirobin, three mexicanolides, and two phragmalin-type limonoids named andirolides H (1), I (2), J (3), K (4), L (5), M (6), N (7), O (8), and P (9) were isolated from an oil of the flower of Carapa guianensis Aublet (Meliaceae). Their structures including the absolute configurations were determined by means of the NMR and CD spectra as well as FABMS. Andirolide H (1) showed antimalarial activity against Plasmodium falciparum in vitro.     

A comparison of electromigration failure of metal lines with fracture mechanics

Atoms constructing an interconnecting metal linein a semiconductor device are transported by electron flowin high density.This phenomenon is called electromigration,which may cause the line failure.In order to characterize theelectromigration failure,a comparison study is carried outwith some typical phenomena treated by fracture mechanicsfor thin and large structures.An example of thin structures,which have been treated by fracture mechanics,is silica optical fibers for communication systems.The damage growth ina metal line by electromigration is characterized in comparison with the crack growth in a silica optical fiber subjectedto static fatigue.Also a brief comparison is made betweenthe electromigration failure and some fracture phenomena inlarge structures.     

Study of electronic states for V thin films deposited on 6H-SiC substrates by soft X-ray emission spectroscopy

Silicon carbide (SiC) is a candidate material for electronic devices to operate upon crucial environment. Electronic states of silicides and/or carbide/graphite formed in metal/SiC contact system is fundamentally important from the view point of device performance.We study interface electronic structure of vanadium (V) thin-film deposited on 6H-SiC(0 0 0 1) Si-face by using a soft X-ray emission spectroscopy (SXES). For specimens of V(38 nm)/6H-SiC (substrate) contact systems annealed at 850 °C, the Si L_2,3 emission spectra indicate different shapes and peak energies from the substrate. The product of materials such as silicides and/or ternary materials is suggested. Similarly, the C Kα emission spectra show the shape and peak energy characteristic of vanadium carbide including substrate 6H-SiC signal.     

Practical Route to Neokotalanol and Its Natural Analogues: Sulfonium Sugars with Antidiabetic Activities

An efficient and divergent approach toward the synthesis of all four de‐O‐sulfonated sulfonium type α‐glucosidase inhibitors, originally isolated from plants of genus Salacia, is reported for the first time. The key strategy features a coupling reaction between thiol derivatives and a diiodide counterpart. The newly designed thiol coupling partner presents high chemical stability, while the diiodide partner could be easily obtained with increased overall yields compared with conventional routes. The intermolecular nucleophilic substitution reaction followed by a diastereoselective intramolecular cyclization provided the target five‐member sulfonium salt structure, which was connected in an α‐orientation to a polyhydroxylated side‐chain moiety.     

In situ surface-enhanced Raman spectroscopy in Li–O2 battery research

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive vibrational technique to obtain the structural information of chemical species on their surface and interface. In this short article, we briefly review the current research regarding the reaction mechanism and kinetics on the cathode surface of the Li–O₂ battery by in situ SERS observations, including reaction intermediates and products, influence of solvent, discharge/charge mechanisms, and mediation mechanism of redox mediators.     

Relaxation in systems with hierarchical organization: Analytical derivation of the relaxation and dispersion functions

We report a successful attempt to derive a closed-form expression for the relaxation function of a complex system by solving a set of coupled kinetic equations connecting the excitation/de-excitation rates to the number of particles (such as electrical charges, dipoles, etc.) in excited states. Our approach, originating from developments in dielectric and mechanical relaxation studies, allows the use of a unified treatment for a wide array of natural processes which often pose challenges to theoretical modeling. We use the notions that (i) a dipole represents any pair formed by a particle in an excited state (such as an energy level in optically excited molecules, or an electrode in dielectric spectroscopy) and its image in the ground state (or reference electrode), that (ii) coupling between such dipoles may be described as particle transfer from one excited state to another with lower energy, and that (iii) the relaxation function for such a system of dipoles is mathematically equivalent to the cumulative distribution function of particles, i.e., the total number of particles that are still in an excited state at a time t following excitation. Taken together, these ideas naturally lead to the identification of two types of relaxation – parallel and serial relaxation – and allow one to tackle systems with either geometrical or physical self-similarity within a unified mathematical scheme.     

Morphology and properties of globular polymeric materials in the solid state: A composite material of DNA with a cationic surfactant

The aim of the present study was to control entanglements in order to regulate the properties of polymeric solids. Initially, fabrication of polymeric solids with few entanglements was attempted. Films of the DNA–cationic surfactant, cetyltrimethylammonium bromide (CTAB) (DNA–CTA), were cast from ethanol solution at room temperature. Morphological examination of DNA–CTA complex films using atomic force microscopy (AFM) revealed that these films were constructed by particle‐like substances. Geometrical analysis of AFM images showed that the particle‐like substances were the aggregates of several DNA–CTA globules. Mechanical characterization suggested that there were fewer entanglements than with normal plastic films. Small angle X‐ray scattering experiments during annealing indicated that molecular motions were highly excited in the surface region of each particle. In conclusion, a globular polymeric film with fewer entanglements was fabricated. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 730–738     

Rapid current-penetration in turbulent heating of a high-density plasma

Radial distribution of electron temperature as well as that of plasma current has been measured in the skin phase in turbulent heating of a high-density plasma (n ? 2 × 10¹⁴m^?3). Anomalously rapid disappearance of the current skin is observed, while the skin profile of the electron temperature remains longer near the plasma core, indicating that the plasma current is redistributed without electron heat transfer across the magnetic field.