Search results for "Micro"
showing 10 items of 23412 documents
Green conditions for the Suzuki reaction using microwave irradiation and a new HNT- supported ionic liquid-like phase (HNT-SILLP) catalyst
2014
A new catalytic system based on modified halloysite nanotubes was employed in the Suzuki reaction under microwave irradi- ation. A set of solvents, times and bases was screened and the best experimental conditions were obtained when the reactions were carried out for 10 min in water–ethanol at 120 °C in presence of K2CO3 as base. Good recyclability was observed. The new catalytic system was employed using either 1 mol% or 0.1 mol%. The palladium catalyst displayed good activity, allowing the synthesis of several biphenyl compounds in high yield working with only 0.1 mol% palladium loading. The application of mi- crowave irradiation decreased the reaction time and also improved conversion wi…
Determination of metal concentrations in certified plastic reference materials after small-size autoclave and microwave-assisted digestion followed w…
2017
Abstract The digestion methods for the determination of As, Cd, Cr, Pb, Sb, Sn and Zn concentrations in plastic samples using microwave-assisted digestion (MW-AD) and small-size autoclave digestion was developed. The certified polyethylene, polypropylene, polyvinyl chloride and acrylonitrile butadiene styrene certified reference materials were used in order to find digestion method working properly for several sample matrices. Efficiency of the digestion methods was evaluated by analyzing the residual carbon in digests by TOC analyzer. MW-AD using a mixture of 7 mL of HNO 3 and 3 mL of H 2 O 2 as a digestion solution resulted in excellent recoveries for As, Cd, Pb, Sb and Zn, and were in th…
Antioxidant activity and sensory attributes of tomatoes dehydrated by combination of microwave and convective heating
2013
Tomato halves were dried in a combined microwave-hot air system. Drying experiments were carried out by applying the microwave energy (0.5 W/g) at the beginning of the dehydration process (for 2 and 3.5 hours); simultaneously combining microwave (0.25 W/g) with convective hot-air drying (70°C); and by applying only convective hot air at 70°C. The combined microwave-hot air heating reduced significantly the drying time (up to 50 %), if compared with the only convective system. Simultaneous convective and microwave heating allowed besting preserving antioxidant activity of dried tomatoes, by minimizing lycopene and phenols losses, while ensuring satisfied texture characteristics and less perc…
Investigation on the stability of dispersion of zirconia nanoparticles prepared by microwave- hydrothermal synthesis
2005
Difficulties in reproducing the performances of nanoparticles dispersions are obstructive for the progress of the nanotechnology. A plausible reason for this variability is the lack of the control of the stability as well as the dimensions of the nanoparticles in the dispersions. In this work we report results of investigations on the stability of zirconia nanoparticles in aqueous medium, monitoring nanoparticles sizes by means of Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS). Nanocrystalline zirconia powders, prepared by microwave-hydrothermal synthesis, were determined to be 6-8 nm in size by TEM observations. By using DLS technique the as-prepared dispersions wit…
Microéconomie résidentielle et géométrie fractale : calibrage d'une aire urbaine française
2002
International audience
Silmitön ja väkivaltainen : erään mielisairaalapotilaan ura 1900-luvulla
2018
Artikkelissa tarkastellaan yhden pitkäaikaisen potilaan, ”Katrin”, potilaskertomuksen kautta mielisairauteen liitettyjen kriteerien muuttumista, diagnostiikan ja sairastuneiden lääketieteellisen hallinnan kehitystä sekä mielisairaanhoidon muuttumista psykiatriaksi. Artikkelissa kysytään, millä perusteella mielisairaalapotilas lähetettiin hoitolaitokseen, millaisia hoitokäytänteitä häneen sovellettiin ja miksi ja auttoivatko ne. Kysymyksiin vastaamiseen tarvitaan kontekstin, suomalaisen psykiatrian, tuntemista. Katrin yhteenlaskettu hoitoaika piirimielisairaalassa kesti yli 40 vuotta, ja tuo ajanjakso sisältää miltei kaikki 1900-luvulla käytetyt hoitomuodot. Sairauskertomuksen lääketieteelli…
Tuberculosis among Migrant Populations in Sicily: A Field Report
2021
Background. In the EU, tuberculosis (TB) mainly affects vulnerable people, including migrants. From 2014 to 2017, we have estimated the frequency of both tuberculosis and latent tuberculosis infection (LTBI) among the migrant population hosted in 41 reception centers in western Sicily (ITaCA network). Materials and Methods. All migrants were consecutively recruited for the screening of TB infection with physical examination and TST in 1,020 migrants and with IGRA in the others 2,690. The screening was carried out 4–8 weeks after landing in Sicily. For all migrants with a positive screening test, chest X-ray and smear examination were performed. LTBI was defined by positivity of TST or IGRA …
Microwave-assisted conversion of novel biomass materials into levulinic acid
2018
Levulinic acid is considered one of the most important platform chemicals. It is currently produced mainly from lignocellulosic biomasses. However, there are also other abundant biomass materials, which could be used as raw materials for levulinic acid production. In this work, levulinic acid was produced from two novel biomasses in the presence of Brønsted (H2SO4) and Lewis acid (CrCl3·6H2O or AlCl3·6H2O) catalysts. The studied materials were carbohydrate-rich potato peel waste and sporocarps of the fungus Cortinarius armillatus. Reaction conditions, i.e., time, temperature, H2SO4, and Lewis acid concentrations, were studied by utilizing full 24-factorial experimental designs. Microwave ir…
An ultrasound-assisted digestion method for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical em…
2007
method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of toxic element concentrations (arsenic, barium, cobalt, copper, lead, nickel, strontium, vanadium and zinc) in ash samples was developed. All the measurements were performed in robust plasma conditions which were tested by measuring the Mg(II) 280.270 nm/Mg(I) 285.213 nm line intensity ratios. The highest line intensity ratios were observed when a nebulizer gas flow of 0.6 L minˉ¹, auxiliary gas flow of 0.2 L minˉ¹ and plasma power of 1400 W were used for radially viewed plasma. The analysis of SRM 1633b showed that the ultrasound-assisted metho…
Local eukaryotic and bacterial stream community assembly is shaped by regional land use effects
2023
With anticipated expansion of agricultural areas for food production and increasing intensity of pressures stemming from land-use, it is critical to better understand how species respond to land-use change. This is particularly true for microbial communities which provide key ecosystem functions and display fastest responses to environmental change. However, regional land-use effects on local environmental conditions are often neglected, and, hence, underestimated when investigating community responses. Here we show that the effects stemming from agricultural and forested land use are strongest reflected in water conductivity, pH and phosphorus concentration, shaping microbial communities a…