Search results for "visual_art.visual_art_medium"

UV-Free Microfluidic Particle Fabrication at Low Temperature Using ARGET-ATRP as the Initiator System

2016

Space Charge Dynamics in Nanostructured Epoxy Resin

2008

The results of a comparative analysis performed on specimens of nanostructured epoxy resins obtained by different filler concentrations are reported in this paper. The specimens were prepared by dispersion of bohemite nanoparticles into a cycloaliphatic epoxy resin cross linked under UV. Dielectric properties, in particular space charge accumulation, are measured as a function of nanofiller content. Results indicate that space charge build up and charge mobility are affected largely by filler content. Concentrations of nanofiller of 5-7 wt% show a significant decrease of the space charge with respect to the base epoxy-resin and an increased mobility of negative carriers .

Rheological study of gel phenomena during epoxide network formation in the presence of sepiolite

2012

The dynamic behaviour during the crosslinking of an epoxy polymer near the gel point was monitored using rheological multiple frequency experiments. The influence of a needle-shaped inorganic nanofiller, sepiolite, either non-modified or organically surface modified during the cure process in the presence of an aliphatic and an aromatic hardener was investigated. The validity of various criteria for determining the gel point was examined for the crosslinking of these filled thermosets. The Winter–Chambon criterion at the gel point is obeyed by the unfilled and by the non-modified sepiolite-filled epoxy matrix with either of the two hardeners. However, physical gels are formed in the presenc…

Acid-catalyzed mechanocatalytic pretreatment to improve sugar release from birch sawdust: Structural and chemical aspects

2022

Abstract This study examined acid-catalyzed mechanocatalytic pretreatment of birch sawdust without a separate impregnation step. Catalyst amount and pretreatment time were the key variables. Pretreated material was mixed with water for hydrolysis (100 °C, 60 min). The efficient release of total reducing sugars from birch sawdust is significant to the path towards biofuels and biochemicals. Based on the results, the structure and surface of birch sawdust changed as a function of mechanocatalytic pretreatment. Milling time caused significant transformations in birch structure and also increased the yields of reducing sugars. The highest yield of total reducing sugar from pretreated sawdust wa…

Environmentally Friendly Photocatalytic Oxidation of Aromatic Alcohol to Aldehyde in Aqueous Suspension of Brookite TiO(2)

2008

WOS: 000260509000008

Cover Feature: Metal‐ and Reagent‐Free Electrochemical Synthesis of Alkyl Arylsulfonates in a Multi‐Component Reaction (Chem. Eur. J. 38/2020)

2020

Cytochemical techniques for zinc and heavy metals localization in nerve cells

2002

Zinc is one of the most abundant oligoelements in the living cell. It appears tightly bound to metallothioneins, loosely bound to some metalloproteins and nucleic acids, or even as free ion. Small amounts of zinc ions (in the nanomolar range) regulate a plentitude of enzymatic proteins, receptors, and transcription factors; thus, cells need accurate homeostasis of zinc ions. Some neurons have developed mechanisms to accumulate zinc in specific membrane compartments ("vesicular zinc") which can be revealed using histochemical techniques. This article is a short report on the different direct-indirect experimental approaches for zinc and heavy metal detection in neurons. Substances giving a b…

The geometry of the silver 1,1′-dibenzyl-2,2′-biimidazole complexes

2013

Abstract The argentophilic interactions and interactions of weakly coordinated nitrate and water with silver metal were studied by investigating the reaction of 1,1′-dibenzyl-2,2′-biimidazole (Bn2bim) with silver nitrate. Three new silver complexes [Ag4(Bn2bim)4(NO3)2]·4(CH3CH2OH)·2(NO3)·0.5(H2O) (1), [Ag4(Bn2bim)4(H2O)4]·4(NO3) (2) and [Ag4(Bn2bim)4(NO3)4]·6(CH2Cl2)·2(H2O) (3) were synthesized and characterized. Complexes 1-3 have rare tetranuclear twisted closed cyclic structure with four bridging biimidazoles and variable nitrate/water ratio. The interactions between the nitrate ligand and Ag as well as water ligands and Ag are considered to be weak due to the ease of exchanging them. Th…

Mononuclear coordination compounds based on a novel chelating triazole ligand: 1-vinyl-3-acetylamino-1,2,4-triazole

2002

The synthesis, X-ray structure, magnetic and spectroscopic properties of new Co(II), Ni(II) and Cu(II) complexes with 1-vinyl-3-acetylamino-1,2,4-triazole (vaat) are reported. The crystal structures of [Ni(vaat)2(H2O)2](NO3)2 and [Cu(vaat)2(H2O)2]Cl2 have been determined by X-ray diffraction. In these mononuclear complexes, the metal ion is surrounded by two water molecules in axial positions and two oxygen and two nitrogen (N4) atoms coming from two trans-oriented chelating vaat molecules. Anions are noncoordinated and are involved in a hydrogen bonding network. The complex cations of [Cu(vaat)2(H2O)2]Cl2 are aligned within chains. In the structure of [Ni(vaat)2(H2O)2](NO3)2 the nitrate an…

Optical properties of different polymer thin films containing in situ synthesized Ag and Au nanoparticles

2009

Here we report on the in situ synthesis of Ag and Au nanoparticles inside several polymer matrixes by solid-state chemical reduction of a metallic salt. Poly(ethyleneimine) (PEI), poly(hydroxyethyl methacrylate) (PHEMA), poly(vinylpyrrolidone) (PVP), novolak, poly(4-vinylphenol) (P4VP), poly(4-vinylphenol)-co-(methyl methacrylate) (P4VP-co-MMA) and poly(styrene-co-allyl alcohol) (PS-co-AA) were able to reduce Ag(I) and Au(III) to the corresponding nanoparticles during the baking process. The nanoparticle diameters of Ag and Au were found to range from 2 to 25 nm. TEM also indicated a uniform distribution of nanoparticles embedded in the thin film. This approach is suitable for controlling t…