The neutrino as a tachyon

We investigate the hypothesis that at least one of the known neutrinos travels faster than light. The current experimental situation is examined within this purview.     

Hydroxynitrile lyase catalysed synthesis of heterocyclic (R)- and (S)-cyanohydrins

Heterocyclic saturated five- and six-membered ring ketones sometimes bearing a methyl substituent were reacted with HCN under enzyme catalysis using recombinant hydroxynitrile lyase from Hevea brasiliensis, as a rule (S)-selective, and Prunus amygdalus, (R)-selective. The resulting cyanohydrins were stereochemically characterised. The steric outcome of these transformations was interpreted by molecular modelling.     

Maneuvering Aspects and 3D Effects of Active Airfoil Flow Control

An active flow control experiment was conducted on a cropped NACA 0018 airfoil to study 3D effects and maneuverability aspects made possible by a segmented actuation system installed in the airfoil. The 14 piezo-fluidic actuators were installed at the corner of the cropped region, inclined at 30° to the local surface, facing downstream. Operating all actuators at unison significantly increased lift and generated a pitch-down moment. Operating all actuators at the same magnitude but varying the phase along the span generated larger lift-increment, with respect to the uniform phase excitation. Significant rolling moment can be generated when only half-span of the wing is actuated. The latter effect, as indicated by the 3D pressure distribution, persists to the leading edge even though the excitation was introduced close to the trailing edge. When a pair, out of the possible fourteen actuators is not operating, very little of the control authority is lost. This is an important finding when issues like fault tolerance and robustness of fluidic-piezo actuators are considered.     

Synthesis and Structural Characterization of Stable Branched DNA G-Quadruplexes Using the Trebler Phosphoramidite

Guanine (G)-rich sequences can form a noncanonical four-stranded structure known as the G-quadruplex. G-quadruplex structures are interesting because of their potential biological properties and use in nanosciences. Here, we describe a method to prepare highly stable G-quadruplexes by linking four G-rich DNA strands to form a monomolecular G-quadruplex. In this method, one strand is synthesized first, and then a trebler molecule is added to simultaneously assemble the remaining three strands. This approach allows the introduction of specific modifications in only one of the strands. As a proof of concept, we prepared a quadruplex where one of the chains includes a change in polarity. A hybrid quadruplex is observed in ammonium acetate solutions, whereas in the presence of sodium or potassium, a parallel G-quadruplex structure is formed. In addition to the expected monomolecular quadruplexes, we observed the presence of dimeric G-quadruplex structures. We also applied the method to prepare G-quadruplexes containing a single 8-aminoguanine substitution and found that this single base stabilizes the G-quadruplex structure when located at an internal position.     

Special issue on conveying and handling of particulate solids–Challenges of discrete element simulation,application and calibration

<正>A series of international Conveying and Handling of Particulate Solids(CHoPS)conferences was initiated in Herzliya,Israel in 1995and has since proceeded with six successive conferences held in Jerusalem(1997),the Dead Sea(2000),Budapest(2003),Sorrento(2006),Brisbane(2009)and Friedrichshafen(2012).The conference series covers processes involving particulate solids,for example     

Role of quantum statistics in multi-particle decay dynamics

The role of quantum statistics in the decay dynamics of a multi-particle state, which is suddenly released from a confining potential, is investigated. For an initially confined double particle state, the exact dynamics is presented for both bosons and fermions. The time-evolution of the probability to measure two-particle is evaluated and some counterintuitive features are discussed. For instance, it is shown that although there is a higher chance of finding the two bosons (as oppose to fermions, and even distinguishable particles) at the initial trap region, there is a higher chance (higher than fermions) of finding them on two opposite sides of the trap as if the repulsion between bosons is higher than the repulsion between fermions. The results are demonstrated by numerical simulations and are calculated analytically in the short-time approximation. Furthermore, experimental validation is suggested.     

Liquid crystalline polymers at interfaces

Main chain liquid crystalline polymers (LCPs) at solid-nematic interfaces exhibit a variety of phase transition between distorted and undistorted states. In one case the transition results from the confinement of grafted chains immersed in a nematic solvent and subject to homeotropic anchoring. The general features of the transition are similar for long and for short chains. The detailed physics is different since long chains exhibit Gaussian, entropic elasticity while the elasticity of the short chain is due to their rigidity. As a result it is possible to weakly confine long chains without triggering a distortion while for short chains the nematic distortion occurs simultaneously with the buckling of the rod like LCPs. Related effects are found for uniformly adsorbed LCPs and for free, confined chains. Different scenarios are expected when homogeneous anchoring is imposed.     

Highly sensitive electrochemical detection of trace liquid peroxide explosives at a Prussian-blue 'artificial-peroxidase' modified electrode

A highly sensitive electrochemical assay of the peroxide-based explosives triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) at a Prussian-blue (PB) modified electrode is reported. The method involves photochemical degradation of the peroxide explosives and a low potential (0.0 V) electrocatalytic amperometric sensing of the generated hydrogen peroxide at the PB transducer and offers nanomolar detection limits following a short (15 s) irradiation times. The electrochemical sensing protocol should facilitate rapid field screening of peroxide explosives.     

Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites in urine by LC‐MS after derivatization and its application for differentiation between positional isomers of prilocaine

The demand for clinical toxicology analytical methods for identifying drugs of abuse and medicinal drugs is steadily increasing. Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites by GC‐EI‐MS and LC‐ESI‐MS/MS is of great analytical challenge. These compounds exhibit only/mostly fragments/product ions representing the amine‐containing residue, while the aromatic amide moiety remains unidentified. This task becomes even more complicated when discrimination between positional isomers of such compounds is required. Here, we report the development of a derivatization procedure for the differentiation and structural elucidation of a mixture of local anesthetic drugs and their metabolites that possess tertiary and secondary amines in water and urine. A method based on two sequential “in‐vial” instantaneous derivatization processes at ambient temperature followed by LC‐ESI‐MS/MS analysis was developed. 2,2,2‐Trichloro‐1,1‐dimethylethyl chloroformate (TCDMECF) was utilized to selectively convert the secondary amines into their carbamate derivatives, followed by hydrogen peroxide addition to produce the corresponding tertiary amine oxides. The resulting derivatives exhibited rich fragmentation patterns, enabling improved structural elucidation of the original compounds. The developed method was successfully applied to the differentiation and structural elucidation of prilocaine and its four positional isomers, which all possess similar GC and LC retention times and four of them exhibit almost identical EI‐MS and ESI‐MS/MS spectra, enabling their structural elucidation in a single LC‐ESI‐MS/MS analysis. The developed technique is fast and simple and enables discrimination between isomers based on different diagnostic ions/fragmentation patterns.