Base promoted transformation on thiadiazolopyridinium chlorides

1,2,4-Thiadiazolo[2,3-a]pyridinium chlorides undergo a very facile base promoted transformation to give bispyridilimino-1,2,4-thiadiazolidines. The unequivocal structural assignment of these last compounds was achieved by spectroscopic ¹H, 13C and ¹⁵N two dimensional methods.     

Signatures andS-discrete lattice-ordered groups

The central theme of this article is the approximation of lattice-ordered groups (l-groups) first by Specker groups and, subsequently, by the so-calledS-discretel-groups. The sense of these approximations is made precise via the notion of a signature, defined below, and by that ofa ^*-subgroups. Sample result: ifG is a projectablel-group then it has anl-subgroupH which is Specker and for which the mapPPH defines a boolean isomorphism between the algebras of polars ofG andH.Presented by L. Fuchs.This article was written while this author was a Stouffer Visiting Professor at the University of Kansas. He wishes to thank the members of the Mathematics Department of that institution for their hospitality.     

Preparation of Chiral Amino Esters by Asymmetric Phase‐Transfer Catalyzed Alkylations of Schiff Bases in a Ball Mill

The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase‐transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified.     

An efficient and scalable block parallel algorithm of Neville elimination as a tool for the CMB maps problem

This paper analyses the performance of several versions of a block parallel algorithm in order to apply Neville elimination in a distributed memory parallel computer. Neville elimination is a procedure to transform a square matrix A into an upper triangular one. This analysis must take into account the algorithm behaviour as far as execution time, efficiency and scalability are concerned. Special attention has been paid to the study of the scalability of the algorithms trying to establish the relationship existing between the size of the block and the performance obtained in this metric. It is important to emphasize the high efficiency achieved in the studied cases and that the experimental results confirm the theoretical approximation. Therefore, we have obtained a high predicting ability tool of analysis. Finally, we will present the elimination of Neville as an efficient tool in detecting point sources in cosmic microwave background maps.     

Variational quantum Monte Carlo simulations with tensor-network states

We show that the formalism of tensor-network states, such as the matrix-product states (MPS), can be used as a basis for variational quantum Monte Carlo simulations. Using a stochastic optimization method, we demonstrate the potential of this approach by explicit MPS calculations for the transverse Ising chain with up to N=256 spins at criticality, using periodic boundary conditions and D x D matrices with D up to 48. The computational cost of our scheme formally scales as ND3, whereas standard MPS approaches and the related density matrix renormalization group method scale as ND5 and ND6, respectively, for periodic systems.     

Polyarginine nanocapsules: a new platform for intracellular drug delivery

This report describes the development of a new nanocarrier, named as polyarginine (PArg) nanocapsules, specifically designed for overcoming cellular barriers. These nanocapsules are composed of an oily core and a PArg corona. The attachment of the PArg corona was mediated by its interaction with the oily core, which was conveniently stabilized with phosphatidylcholine. Hybrid PArg/PEG nanocapsules could also be obtained by introducing PEG-stearate in the nanocapsules formation process. The nanocapsules had an average size in the range of 120–160 nm, and a positive surface charge, which varied between +56 and +28 mV for PArg and PArg/PEG nanocapsules, respectively. They could accommodate significant amounts of lipophilic drugs, i.e., docetaxel, in their core, and also polar negatively charged molecules, i.e., plasmid DNA, on their coating. As a preliminary proof-of-principle, we explored the ability of these nanocarriers to enter cancer cells and to inhibit proliferation in the non-small cell lung cancer NCI-H460 cell line, using flow cytometry and confocal microscopy analysis. The results indicated that PArg nanocapsules are rapidly and massively accumulated into the NCI-H460 cells and that the PArg shell plays a critical role in the internalization process. Moreover, the incubation with docetaxel-loaded nanocapsules with NCI-H460 cells led to an enhanced inhibition of their proliferation, as compared to the free drug. Overall, this is the first report of the potential of PArg nanocapsules as intracellular drug delivery vehicles.

     

Depth-dependent acoustic features of diving sperm whales (Physeter macrocephalus) in the Gulf of Mexico

Three-dimensional dive trajectories of three sperm whales in the Gulf of Mexico have been obtained by measuring the relative arrival times and bearings of the animals' acoustic multipath reflections, using two elements of a towed hydrophone array deployed at an unknown depth and orientation. Within the first 6-12 min of the start of a dive, the intervals between successive "clicks" of all three whales corresponded closely with the two-way travel time of an acoustic pulse traveling vertically between the animals' position and the ocean bottom. The click spectra contained multiple peaks, including a faint band of energy originally centered near 10 kHz. As the animals descended over 500 m in depth, the center frequency of this band shifted to nearly 15 kHz, but subsequently remained near this value during the rest of the dive. This frequency shift is consistent with that expected from energy scattering from an ensemble of incompressible small-scale air-filled resonators, with diameters on the order of 4 mm. One possible candidate for such an ensemble is proposed to reside in the collapsed frontal sac of the animal. A comparison of the received levels for the bottom and direct multipath arrivals indicates that the whales' acoustic directivity must range between 10-30 dB in the 5-20-kHz region.