Search results for "nuclear chemistry"
showing 10 items of 1124 documents
On the inverse-voltammetric determination of zinc in acidic solution
1977
Zur Bestimmung kleiner Zinkmengen in salzsauren Losungen ist die inverse Wechselspannungsvoltammetrie geeignet. Besonderheiten des Einflusses der Elektrolysezeit und kleinerer Kupfergehalte werden beschrieben. Die Standardabweichung der Einzelbestimmung mit 50 ng Zn/ml betrug ± 1,6%.
Über Tetrathiowolframsäure und Tetrathiomolybdänsäure
1966
Durch Behandeln mit einem Kationenaustauscher in der H+-Form werden aus verdunnten wasrigen Losungen von (NH4)2WS4 und (NH4)2MoS4 die entsprechenden freien Sauren hergestellt. Die Tetrathiomolybdansaure ist wesentlich unbestandiger als die Tetrathiowolframsaure.
3,3?,5,5?-Tetramethylbenzidme for the colorimetric determination of manganese in water
1998
Manganese can be determined by colorimetry with previous oxidation of Mn(II) in a strong basic medium, using 3,3′,5,5′-tetramethylbenzidine as a chromogenic reagent. The molar absorptivity of the reaction product is 3.4 × 104 mol−1l cm−1l, the detection limit 3 ng/ml, the RSD (0.5 mg/l,n = 8) 0.9% and the calibration range (1-cm cells) 0.02–0.8 mg/1 V(V), Cr(VI) and Co(II) are the most significant interferences. The new method was compared with an AAS procedure (air-acetylene flame) with previous solvent extraction and also with a colorimetric method for the determination of manganese in sea and drinking water.
Preliminary study on analysis and removal of wax from a Carrara marble statue
2015
This preliminary study has mainly focused on the wax identification by nuclear magnetic resonance (NMR) and removal. Wax is used for many purposes in the field of art as protective coatings on wooden, stone or metal objects. From the comparison of the spectra H NMR and in particular with the correspondence of the resonance peaks of the samples taken from the statue and beeswax and paraffin, we can conclude that the wax applied on the statue surface is beeswax. From our data, it can be concluded that, to remove the beeswax, from any stone support, the more effective solvent is the mixture of cyclohexane/ethyl acetate. The removal percentages ranged from 19 to 99%. Lower percentages of remova…
N-Methyl-4-(4-nitrophenyl)-N-nitroso-1,3-thiazol-2-amine
2017
The title compound, C10H8N4O3S, is almost planar [dihedral angle between the rings = 2.2 (2)°; r.m.s. deviation for the non-H atoms = 0.050 Å]. In the crystal, C—H...O and C—H...N hydrogen bonds link the molecules into (10-2) layers.
Design and preparation of core-shell structured magnetic graphene oxide@MIL-101(Fe): Photocatalysis under shell to remove diazinon and atrazine pesti…
2020
Abstract A magnetically separable support with core-shell morphology comprising amine-functionalized Fe3O4 wrapped with graphene oxide (AFG) was successfully prepared and used to support MIL-101(Fe). The ternary AFG@MIL-101(Fe) composite was investigated as a photo-Fenton catalyst for the degradation of recalcitrant diazinon (DIZ) and atrazine (ATZ) pesticides. After 105 min visible light irradiation, the AFG@30MIL-101(Fe) photocatalyst achieved 100 ± 1% and 81 ± 1% photocatalytic degradation efficiency for DIZ and ATZ pollutants, respectively. The recorded data indicated superior photocatalytic ability of the nanocomposite as compared to AF@30MIL-101(Fe) and MIL-101(Fe) photocatalysts for …
Efficient alkali iodide promoted 18F-fluoroethylations with 2-[18F]fluoroethyl tosylate and 1-bromo-2-[18F]fluoroethane
2003
Abstract Radiochemical 18 F-fluorination yields of several compounds using the secondary labelling precursors 2-[ 18 F]fluoroethyl tosylate ([ 18 F]FETos) and 1-bromo-2-[ 18 F]fluoroethane ([ 18 F]BFE) could be considerably enhanced by the addition of an alkali iodide. The radiochemical yield of [ 18 F]fluoroethyl choline for example could be doubled with [ 18 F]BFE and increased from 13% to ≈80% with [ 18 F]FETos. By addition of alkali iodide to the precursor, the 18 F-fluoroethylation yields of established radiopharmaceuticals, especially in the case of automated syntheses, could be significantly increased without major changes of the reaction conditions.
Copper-catalyzed click reactions: quantification of retained copper using 64Cu-spiked Cu(I), exemplified for CuAAC reactions on liposomes
2018
Abstract The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a powerful, highly reliable and selective reaction which allows for a rapid synthesis in high yields and under mild conditions (pH, temperature). However, the cytotoxicity of copper requires its complete removal prior to an application in vivo. This is an issue especially when it comes to CuAAC reactions on macromolecular structures or drug delivery systems, as copper might be retained by these systems. Thus, a quantification of the final copper content of these systems is inevitable, which we exemplified for a CuAAC reaction on liposomes using 64Cu-spiked Cu(I). In this respect, a Cu(II) nitrate solution was irradiated at t…
Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes
2001
A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.
Protocol for development of various plants leaves extract in single-pot synthesis of metal nanoparticles
2012
This article is aimed to extend a simple protocol for preparation of various plant leaves extract and their application to green synthesis of the metallic nanoparticles. Five plant leaves extract showed mild reduction and stabilization ability for silver and gold nanoparticles (AgNPs and AuNPs) at room temperature. The particle size range varied from 25 to 42 nm and 21 to 47 nm for AgNPs and AuNPs, respectively. Plant leaves extract-mediated nanoparticles were characterized to confirm the shape, size, crystallinity, and content using different spectroscopic investigations. Differences in stability of nanoparticles at different pH were also measured by zeta potential.