CB‐TE2A+·Cl−·3H2O: a short intermolecular hydrogen bond between zwitterionic bicyclo[6.6.2]tetraamine macrocycles

1,4,8,11‐Tetraazabicyclo[6.6.2]hexadecane‐4,11‐diacetic acid (CB‐TE2A) is of much interest in nuclear medicine for its ability to form copper complexes that are kinetically inert, which is beneficial in vivo to minimize the loss of radioactive copper. The structural chemistry of the hydrated HCl salt of CB‐TE2A, namely 11‐carboxymethyl‐1,8‐tetraaza‐4,11‐diazoniabicyclo[6.6.2]hexadecane‐4‐acetate chloride trihydrate, C₁₆H₃₁N₄O₄⁺·Cl⁻·3H₂O, is described. The compound crystallized as a positively charged zwitterion with a chloride counter‐ion. Two of the amine groups in the macrocyclic ring are protonated. Formally, a single negative charge is shared between two of the carboxylic acid groups, while one chloride ion balances the charge. Two intramolecular hydrogen bonds are observed between adjacent pairs of N atoms of the macrocycle. Two intramolecular hydrogen bonds are also observed between the protonated amine groups and the pendant carboxylate groups. A short intermolecular hydrogen bond is observed between two partially negatively charged O atoms on adjacent macrocycles. The result is a one‐dimensional polymeric zigzag chain that propagates parallel to the crystallographic a direction. A second intermolecular interaction is a hydrogen‐bonding network in the crystallographic b direction. The carbonyl group of one macrocycle is connected through the three water molecules of hydration to the carbonyl group of another macrocycle.     

Computing the throughput of Concatenation State Machines

Concatenation State Machine (CSM) is a labeled directed And–Or graph representing a deterministic push-down transducer. In the high-performance version of CSM, labels associated to edges are words (rather than letters) over the input alphabet. The throughput of a path p is defined as the sum of the lengths of the labels of the path, divided by the number of edges of p. The throughput of a CSM M is defined as the infimum of the throughput of all accepting paths of M. In this paper we give an $\mathrm{O}(nm\log (\frac{\mathit{max}-\mathit{min}}{\epsilon }))$ algorithm, computing an ε-approximation of the throughput of a CSM M, where n is the number of nodes, m is the number of edges, and max (min) is the maximum (respectively, minimum) of the lengths of the edge labels of M. While we have been interested in a particular case of an And–Or graph representing a transducer, we have actually solved the following problem: if a real weight function is defined on the edges of an And–Or graph G, we compute an ε-approximation of the infimum of the complete hyper-path mean weights of G. This problem, if restricted to digraphs, is strongly connected to the problem of finding the minimum cycle mean.     

Separating convex sets in the plane

Given a setA inR ² and a collectionS of plane sets, we say that a lineL separatesA fromS ifA is contained in one of the closed half-planes defined byL, while every set inS is contained in the complementary closed half-plane.We prove that, for any collectionF ofn disjoint disks inR ², there is a lineL that separates a disk inF from a subcollection ofF with at least (n–7)/4 disks. We produce configurationsH _n andG _n , withn and 2n disks, respectively, such that no pair of disks inH _n can be simultaneously separated from any set with more than one disk ofH _n , and no disk inG _n can be separated from any subset ofG _n with more thann disks.We also present a setJ _m with 3m line segments inR ², such that no segment inJ _m can be separated from a subset ofJ _m with more thanm+1 elements. This disproves a conjecture by N. Alonet al. Finally we show that ifF is a set ofn disjoint line segments in the plane such that they can be extended to be disjoint semilines, then there is a lineL that separates one of the segments from at least n/3+1 elements ofF.     

A review of environment-dependent processes within FEL excited matter

In this review we discuss four examples of environment-dependent processes triggered by free-electron laser radiation within systems of various complexity. Those are: (i) non-thermal structural changes within irradiated solids, (ii) inverse bremsstrahlung during VUV irradiation of atomic clusters, (iii) shifts of ionic potentials due to a charged ion environment within a plasma, and (iv) fast thermalization of the electrons created after FEL irradiation. We show that FEL excitation enables access to a unique class of environment-influenced processes, depending on the radiation wavelength, pulse fluence and the structure of sample.     

Flux growth of ZnO crystals doped by transition metals

ZnO crystals doped with Cr, Mn, Fe and Co were grown by the flux method. The prepared crystals revealed no phase separation detectable by X-ray diffraction. Structure properties were characterized by Raman and photoluminescence spectroscopy. For ZnO:Co, Mn and Cr, no spontaneous ferromagnetic moment was observed up to T=2 K whereas for the ZnO:Fe crystals the m(H) curves suggest the existence of 5 nm superparamagnetic iron clusters. At low temperatures the m(H) curves can be interpreted as a superposition of major paramagnetic and minor antiferromagnetic contribution. The paramagnetic part corresponds to the presence of Co²⁺, Fe³⁺, Mn²⁺ ions and small Cr atom clusters.     

Doped biocompatible layers prepared by laser

The contribution deals with KrF laser synthesis and study of doped biocompatible materials with focus on diamond-like carbon (DLC) and hydroxyapatite (HA). Overview of materials used for dopation is given. Experimental results of study of HA layers doped with silver are presented. Films properties were characterized using profilometer, SEM, WDX, XRD and optical transmission. Content of silver in layers moved from 0.06 to 13.7 at %. The antibacterial properties of HA, silver and doped HA layers were studied in vivo using Escherichia coli cells.     

Visible light-induced polymerization initiated by borate salts of bicationic monochromophoric benzothiazolestyrylium dyes

A series of bicationic monochromophoric hemicyanine dyes based on benzothiazolestyrylium residues were synthesized. The dyeing photoinitiating systems consisting of N-[3-(4-methylpyridino)propyl]-2-(p-substituted styryl)benzothiazolium dihalides as chromophores and n-butyltriphenylborate anion as electron donor were also prepared to achieve an efficient photoinitiators for free-radical polymerization in a visible-light region. The relative photoinitiating efficiencies of novel photoinitiators of acrylate monomers polymerization were evaluated.     

Preliminary comparative study of laser-prepared DLC and Cr-doped DLC for bacteria adhesion

Diamond-like carbon (DLC) and Cr-doped DLC (chromium content 0–18 at.%) layers were deposited by dual pulsed laser ablation. The composition was analyzed using electron probe X-ray microanalysis with wavelength-dispersive spectrometers. Carbon and chromium bonds were determined by X-ray photoelectron spectroscopy. Ethylene glycol, diiodomethane and deionized water were used to measure contact angles and for the calculation of the surface free energy (SFE). Antibacterial properties were studied using gram positive and negative bacteria. The influence of the SFE, hydrophobicity, surface roughness and the zeta potential on antibacterial properties of doped layers was discussed. The relationships between physical and bio-properties are discussed.