Amyloid beta peptides electrochemistry: A review

Alzheimer disease is a progressive age-related neurodegenerative disorder estimated to affect up to 107 million people by 2050, its pathology is associated with the dysfunction of the amyloid beta (Aβ) peptide mechanism, among others. Electrochemical methods were successfully applied for Aβ electrochemical characterisation and have received increased attention in Aβ research. This review discusses the recent advances on the direct electrochemical detection of Aβ redox mechanisms, fibrilization and interaction with metal ions based on the electrochemical detection of the Aβ′s

,

and

amino acid residues oxidation peaks.     

To be or not to be – nematic liquid crystals from shape-persistent V-shaped nematogens with the ‘magic angle’

The tetrahedral bending angle in V-shaped nematogens was claimed to be the optimum for finding a biaxial nematic liquid crystal phase. The benzo[1,2-b:4,3-b’]dithiophene core, recently successfully applied as a tetrahedral bending unit in mesogens with lateral flexible chains, is here embedded in a scaffold with only terminal chains, which conventionally promotes the formation of nematic phases at low temperature. A series of new mesogens has been successfully prepared, realising hockey-stick, hockey-stick dimer and V-shaped molecular topologies. Only the hockey-stick mesogens assemble in uniaxial nematic phases over a broad temperature range. Single crystal structure analysis of a hockey-stick and V-shaped compound reveal remarkable similarities with the benzodithiophene core wrapped by aliphatic chains. A model explaining the absence of nematic mesophases in the family of V-shaped, shape-persistent mesogens with terminal aliphatic chains is presented and results in the proposal of a new design for biaxial nematogens.     

Study of the 2-Benzimidazolylaminomethylphosphonic Acid Derivatives by Mass Spectroscopy

Abstract

The present paper reports the mass spectra of some compounds of 2-alkylenbenzimidazolylaminomethylphosphonates with the general formula:     

Upconversion luminescence of Er3+/Yb3+ co-doped nanolangasite synthesized by a modified Pechini route

Nanopowders of langasite (La₃Ga₅SiO₁₄) doped with 1 at.% Er³⁺ and 3 at.% Yb³⁺ were synthesized for the first time by a modified Pechini route and annealed in air at 700, 750, 800, 900, and 1,000?°C. The langasite powders were characterized by XRD, FTIR and luminescence techniques. Crystallization began at 750?°C and pure langasite phase was obtained for the samples annealed at 800 and 900?°C. Traces of LaGaO₃ and Ga₂O₃ were observed in the sample annealed at 1,000?°C. Bright green and red luminescence was observed for pumping at 973?nm whose intensity increased with annealing temperature due to the removal of the adsorbed impurities and the improvement of crystallinity.     

In vivo imaging of the human brain at 1.5 T with 0.6-mm isotropic resolution

We present high-resolution in vivo anatomical scans with 3D whole-brain coverage and an isotropic resolution of 0.6 mm, obtained at a clinical field of 1.5 T. The data are acquired in 10 independent scans over two sessions using a 3D magnetization-prepared, gradient echo sequence, modified to output phase images in addition to magnitude images. The independent scans are coregistered to correct for head motion, prior to performing complex averaging. The resolution of the final, averaged image, is found to be equal to the nominal one.     

Characteristic temperatures and electron number densities in an R.F. capacitively coupled plasma

The excitation temperatures of Ar and Fe, the ionization temperatures of Ar and Ca and the electron number densities have been determined for a radiofrequency capacitively coupled plasma in the tip-ring electrode geometry. The temperatures and the electron number densities possess their maximum value close to the electrodes.     

Preparation and characterization of polyvinyl alcohol—chitosan biocompatible magnetic microparticles

This work addresses the obtaining of biocompatible magnetic polyvinyl alcohol—chitosan microspheres, specifically tailored/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a high yield of colloidally stable and uniformly sized particles with significant magnetization of saturation, bearing surface amino groups that can be further used to bind blood toxins directly. The particles were characterized regarding their size distribution and surface charge (laser diffraction analysis), morphology (transmission electron microscopy), magnetic properties, chemical composition (Fourier transform infrared spectroscopy) and concentration of the surface amino groups (conductometric titration).     

Structural investigations of Ge nanoparticles embedded in an amorphous SiO2 matrix

Transmission electron microscopy and X-ray photoelectron spectroscopy analyses are performed to investigate Ge nanoparticles embedded in an amorphous SiO₂ matrix. GeSiO thin films are prepared by two methods, sol?Cgel and radio frequency magnetron sputtering. After the deposition, the sol?Cgel films are annealed in either N₂ (at 1 atm and 800 °C) or H₂ (at 2 atm and 500 °C), and the sputtered films in H₂ (at 2 atm and 500 °C), to allow Ge segregation. Amorphous Ge-rich nanoparticles (3?C7 nm size) are observed in sol?Cgel films. Crystalline Ge nanoparticles in the high pressure tetragonal phase (10?C50 nm size) are identified in the sputtered films. The size of the nanoparticles increases with Ge concentration in the volume of the film. At the film surface, the Ge concentration is much larger that in the volume for both sol?Cgel and sputtered films. At the same time, at the film surface, only oxidized Ge is observed.