In spite of the key role of hydrogen bonding in the structural stabilization of the prototypic hybrid halide perovskite, CH3NH3PbI3 (MAPbI3), little progress has been made in our in-depth understanding of the hydrogen-bonding interaction between the MA(+)-ion and the iodide ions in the PbI6-octahedron network. Herein, we show that there exist two distinct types of the hydrogen-bonding interacti...

Simple and efficient procedures for the Pd-catalyzed cross-coupling of primary and secondary amines with halo-7-azaindoles(pyrrolo[2,3-b]pyridine) are presented. Previously, no general method was available to ensure the highly selective reaction of the heteroaryl halide in the presence of the unprotected azaindole N-H. Using palladium precatalysts recently reported by our group, such reactions ...

We propose the idea of a Quantum Cheque Scheme, a cryptographic protocol in which any legitimate client of a trusted bank can issue a cheque, that cannot be counterfeited or altered in anyway, and can be verified by a bank or any of its branches. We formally define a Quantum Cheque and present the first Unconditionally Secure Quantum Cheque Scheme and show it to be secure against any no-signali...

Tiny sap-sucking insects that are a scourge to gardeners also have the upside of helping trees survive in seasonally dry forests in Central America. How? Scale insects use carbon they get from Cordia alliodora trees to make sugar-rich ‘‘honeydew’’ for Azteca pittieri ants, which in turn defend the trees against leaf-munching insects. Mutualism is often stronger when resources are scarce, but th...

Catch-bonds refer to the counterintuitive notion that the average lifetime of a bond has a maximum at a nonzero applied force. They have been found in several ligand-receptor pairs and their origin is still a topic of debate. Here, we use coarse-grained simulations and kinetic theory to demonstrate that a multimeric protein, with self-interacting domain pairs, can display catch-bond behavior. O...

■ Abstract On laboratory time scales, the energy landscape of a weak bond along a dissociation pathway is fully explored through Brownian-thermal excitations, and energy barriers become encoded in a dissociation time that varies with applied force. Probed with ramps of force over an enormous range of rates (force/time), this kinetic profile is transformed into a dynamic spectrum of bond rupture...

in this paper, the ultrasonic absorption of amino acids was measured using a small cylindrical resonator at physiological ph and 25°c and a concentration of 0.1. m. the absorption of mixtures of some amino acids was also measured. in the case of cysteine-histidine, the absorption of mixtures is much larger (more than twice) than the summation of absorption of the individual amino acid. this may...