Search results for "Sulphide"

Microstructure and phase composition of bronze Montefortino helmets discovered Mediterranean seabed to explain an unusual corrosion

2021

AbstractTwo Monterfortino helmets, recovered in the Mediterranean seabed, show unusual features with respect to the more common helmets of the same period and found in underwater environments. Hence, they were investigated by a multi-analytical approach, which allowed us to identify the compounds constituting the helmets and to make some considerations about their metallurgy, although all the metal was converted to degradation products. The helmets, originally made in bronze, have maintained their original shape because of copper sulphides formation. The observed differences in composition between the two helmets were attributed to the position modification, of one of them, into the seabed …

Distribution of trace elements in willemite from the Belgium non-sulphide deposits

2019

Samples of willemite (Zn2SiO4) mineralization from the historical non-sulphide Zn–Pb deposits of La Calamine (eastern Belgium) have been recovered from collections of the Geological Survey of Belgium. Textural and chemical analyses are used to evaluate the critical element distribution (Ge, In, Ga) and deportment. willemite occurs as a variety of types that continuously formed between the protore stage (sulphides) and the late supergene stage (carbonates and hydrated phases). Different types of willemite may be distinguished on the basis of their shape and zoning characteristics, supporting a polyphase non-sulphide mineralization after the protore stage. This is also marked by a significant…

On the determination of intramolecular potential functions : Application to hydrogen sulphide and methane

2008

Determination of intramolecular potential functions : Application to hydrogen sulphide and methane

2008

Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.

2018

‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…

Microwave radiation effect on the synthesis of cadmium sulphide nanoparticles in water in oil microemulsion: a preliminary study at different frequen…

2004

AbstractCadmium sulphide nanoparticles have been synthesised in water/sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/n- heptane microemulsions kept at 30 °C by microwave irradiation coupled with water-cooling and in conventional thermostatic conditions at the same temperature. The study has been performed exposing the reaction media to microwave radiation at five different frequencies (2.45, 2.85, 8, 12 and 18 GHz). For each frequency, a suitable microwave exposure set-up has been assembled. During the growth process, the dimensions of the nanoparticles have been characterised by means of UV-Vis spectroscopy. At the end of the growth process, the surface morphology of the nanoparticles has …

Hydrogen sulfide measurements in air by passive/diffusive samplers and high-frequency analyzer: A critical comparison

2016

In this study, hydrogen sulfide (H2S) measurements in air carried out using (a) passive/diffusive samplers (Radiello® traps) and (b) a high-frequency (60 s) real-time analyzer (Thermo® 450i) were compared in order to evaluate advantages and limitations of the two techniques. Four different sites in urban environments (Florence, Italy) and two volcanic areas characterized by intense degassing of H2S-rich fluids (Campi Flegrei and Vulcano Island, Italy) were selected for such measurements. The concentrations of H2S generally varied over 5 orders of magnitude (from 101e103 mg/m3), the H2S values measured with the Radiello® traps (H2SR) being significantly higher than the average values measure…

Identification of disulphide bonds in the refolding of bovine pancreatic RNase A

1996

Background: Comprehension of the rules that govern the folding process is still far from satisfactory, though it is nevertheless clear that all the information required to define the folding is encoded in the amino acid sequence. In proteins that contain disulphide bonds, folding is associated with disulphide bond formation. Protein species with different numbers of disulphides tend to accumulate during the process; these species can be trapped in a stable form, by quenching any remaining free SH groups, and then characterized in order to identify the disulphide bonds formed. Results The refolding pathway of reduced and denatured RNase A has been studied using mass spectrometric strategies …

Detection and localisation of disulphide bonds in a synthetic peptide reproducing the sequence 1-30 of Par j 1.0101 by electrospray ionisation mass s…

2001

The structural characterisation of a synthetic peptide reproducing the sequence 1–30 of Par j 1.0101, a major allergenic protein present in the pollen of Parietaria judaica, by combined use of chemical and enzymatic cleavage, reversed-phase high-performance liquid chromatography (RP-HPLC) and electrospray ionisation mass spectrometry (ESI-MS), is described. Direct ESI-MS of the synthetic peptide after reaction with methyl iodide showed that the product is a mixture of two peptides: one form in which two out of the four cysteine residues present in the sequence are oxidised and a minor amount of another form in which all the cysteines are fully reduced. It was ascertained, using the combined…

Biogas Pollution and Mineral Deposits Formed on the Elements of Landfill Gas Engines

2022

Municipal landfills generate a significant amount of high-energy biogas, which can be used as a renewable gaseous fuel. However, it is necessary to improve the quality of this biogas due to the presence of various chemical compounds. The most common pollutants in landfill biogas include volatile compounds of silicon, sulphur, phosphorus and chlorine. The aforementioned elements, as well as other metals, were found both in the deposits and in the engine oil. The paper presents detailed characteristics of the solid residues formed in selected parts of gas engines powered by landfill biogas. Its elemental composition and morphology were investigated in order to determine the structure and infl…