Steroidal alkaloid glycosides, esculeosides C and D, from the ripe fruit of cherry tomato

Two new steroidal alkaloid glycosides, esculeosides C and D, have been isolated from the ripe fruit of Cherry tomato [Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF.], along with three known steroidal alkaloid glycosides, esculeoside A, esculeoiside B, and lycoperoside G. Their chemical structures were determined on the basis of spectroscopic data.     

Synthesis of an optically active Al(salalen) complex and its application to catalytic hydrophosphonylation of aldehydes and aldimines

Optically active aluminum(salalen) complex 2 was newly synthesized in a modular synthetic manner, and it was found to serve as an efficient catalyst for hydrophosphonylation of aldehydes and aldimines, giving the corresponding alpha-hydroxy and alpha-amino phosphonates with high enantioselectivity, respectively. The scope of the hydrophosphonylation was wide, and both aliphatic and aromatic aldehydes and aldimines were successfully used as substrates for the reaction. The potent catalysis of the complex is attributed to its unique structure: it adopts a distorted trigonal bipyramidal configuration which allows the salalen ligand to take a cis-beta-like structure wherein the chiral amino group is located close to the metal center.     

Viscosity, shear waves, and atomic-level stress-stress correlations

The Green-Kubo equation relates the macroscopic stress-stress correlation function to a liquid's viscosity. The concept of the atomic-level stresses allows the macroscopic stress-stress correlation function in the equation to be expressed in terms of the space-time correlations among the atomic-level stresses. Molecular dynamics studies show surprisingly long spatial extension of stress-stress correlations and also longitudinal and transverse waves propagating in liquids over ranges which could exceed the system size. The results reveal that the range of propagation of shear waves corresponds to the range of distances relevant for viscosity. Thus our results show that viscosity is a fundamentally nonlocal quantity. We also show that the periodic boundary conditions play a nontrivial role in molecular dynamics simulations, effectively masking the long-range nature of viscosity.