Bioinspired Chemical Communication between Synthetic Nanomotors

While chemical communication plays a key role in diverse natural processes, the intelligent chemical communication between synthetic nanomotors remains unexplored. The design and operation of bioinspired synthetic nanomotors is presented. Chemical communication between nanomotors is possible and has an influence on propulsion behavior. A chemical “message” is sent from a moving activator motor to a nearby activated (receiver) motor by release of Ag⁺ ions from a Janus polystyrene/Ni/Au/Ag activator motor to the activated Janus SiO₂/Pt nanomotor. The transmitted silver signal is translated rapidly into a dramatic speed change associated with the enhanced catalytic activity of activated motors. Selective and successive activation of multiple nanomotors is achieved by sequential localized chemical communications. The concept of establishing chemical communication between different synthetic nanomotors paves the way to intelligent nanoscale robotic systems that are capable of cooperating with each other.     

The mechanism of the reaction between hydroxyl ions and some internally hydrogen-bonded acids

The kinetics of the proton transfer between hydroxyl ions and phenylazoresorcinol, 4-(p-nitrophenylazo), and 4-(m-nitrophenylazo) resorcinol have been investigated at 25°C and an ionic strength of 0.1M, in a wider pH range than had been done by previous authors. The rate at first decreased with decreasing [OH^?], reached a minimum, and then started to increase with decreasing [OH^?]. This unusual effect is explained by a mechanism suggested earlier for tropaeolin O. Rate constants and equilibrium constants have been evaluated and discussed. The experimental data were obtained by the T-jump method.     

Sensitive and rapid amperometric magnetoimmunosensor for the determination of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

The preparation and characteristics of a disposable amperometric magnetoimmunosensor, based on the use of functionalized magnetic beads (MBs) and gold screen-printed electrodes (Au/SPEs), for the specific detection and quantification of Staphylococcal protein A (ProtA) and Staphylococcus aureus (S. aureus) is reported. An antiProtA antibody was immobilized onto ProtA-modified MBs, and a competitive immunoassay involving ProtA antigen labelled with HRP was performed. The resulting modified MBs were captured by a magnetic field on the surface of tetrathiafulvalene-modified Au/SPEs and the amperometric response obtained at −0.15 V vs the silver pseudo-reference electrode of the Au/SPEs after the addition of H₂O₂ was used as transduction signal. The developed methodology showed very low limits of detection (1 cfu S. aureus/mL of raw milk samples), and a good selectivity against the most commonly involved foodborne pathogens originating from milk. These features, together with a short analysis time (2 h), the simplicity, and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site analysis.     

One-Shot Decoupling

If a quantum system A, which is initially correlated to another system, E, undergoes an evolution separated from E, then the correlation to E generally decreases. Here, we study the conditions under which the correlation disappears (almost) completely, resulting in a decoupling of A from E. We give a criterion for decoupling in terms of two smooth entropies, one quantifying the amount of initial correlation between A and E, and the other characterizing the mapping that describes the evolution of A. The criterion applies to arbitrary such mappings in the general one-shot setting. Furthermore, the criterion is tight for mappings that satisfy certain natural conditions. One-shot decoupling has a number of applications both in physics and information theory, e.g., as a building block for quantum information processing protocols. As an example, we give a one-shot state merging protocol and show that it is essentially optimal in terms of its entanglement consumption/production.     

Catalytic regioselective sulfonylation of alpha-chelatable alcohols: scope and mechanistic insight

This paper describes a convenient protocol for the regioselective sulfonylation of alpha-chelatable alcohols. Typically, the reaction of alpha-heterosubstituted alcohols with 1 equiv of p-TsCl and 1 equiv of Et(3)N in the presence of 2 mol % of Bu(2)SnO leads to rapid, regioselective, and exclusive monotosylation. The pK(a) of the amine was correlated to the reaction rate. A plausible mechanism for this reaction has been proposed on the basis of (119)Sn NMR studies.     

The deprotonation of internally hydrogen-bonded acids. Mechanistic conclusions from the influence of general bases

The reactions between alizarin yellow G and six different bases B (including OH^?) and between tropaeolin 0 and eight different bases have been investigated at 25°C and an ionic strength of 0.5M, using the temperature-jump method. From the form of the log k_B versus ΔpK curves it is concluded that for alizarin yellow G the observed relaxation time is due chiefly to a diffusion-controlled reaction between the base and that fraction which is present in the “open” non-hydrogen-bonded form, whereas for tropaeolin 0 the base attacks the hydrogen bridge. The dissociation constants for the internally bound hydrogen have been measured under the same conditions of temperature and ionic strength, using a spectrophotometric method.     

Laser induced synthesis: selective formation of cyclohexene episulphide from molecular sulphur s8

1,2-Epithiocyclohexane was obtained selectively by irradiation of a mixture of cyclohexene and sulphur with a pulsed laser (266 nm).     

A Catalyst Designed for the Enantioselective Construction of Methyl‐ and Alkyl‐Substituted Tertiary Stereocenters

Tertiary methyl‐substituted stereocenters are present in numerous biologically active natural products. Reported herein is a catalytic enantioselective method for accessing these chiral building blocks using the Mukaiyama–Michael reaction between silyl ketene thioacetals and acrolein. To enable remote enantioface control on the nucleophile, a new iminium catalyst, optimized by three‐parameter tuning and by identifying substituent effects on enantioselectivity, was designed. The catalytic process allows rapid access to chiral thioesters, amides, aldehydes, and ketones bearing an α‐methyl stereocenter with excellent enantioselectivities, and allowed rapid access to the C4–C13 segment of (?)‐bistramide A. DFT calculations rationalized the observed sense and level of enantioselectivity.     

Thermal and spectroscopic studies on a double-salt-type pyridine–silver perchlorate complex having κ1-O coordinated perchlorate ions

Journal of Thermal Analysis and Calorimetry - A simple synthetic method was developed to prepare 4[Agpy2ClO4]·[Agpy4]ClO4 in a low-temperature decomposition process of [Agpy4]ClO4. A detailed...