Search results for "Roth"

Dehydration of Fructose to 5-HMF over Acidic TiO2 Catalysts

2020

Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated by means of X-ray diffraction (XRD), N2 adsorption isotherms, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements. Special attention was focused on the reaction conditions, both in terms of 5-HMF selectivity and the sustainability of the process, choosing water as the solvent. Among the various process condition…

Hydrothermal Synthesis of Ionic Liquid [Bmim]OH-Modified TiO2 Nanoparticles with Enhanced Photocatalytic Activity under Visible Light

2010

TiO(2) nanocomposites modified with the ionic liquid [Bmim]OH are synthesized by a hydrothermal procedure. X-ray diffraction, Zeta-potential measurement, TEM, thermogravimetric analysis, photoluminescence, UV/Vis, FTIR, and X-ray photoelectron spectroscopy are used to characterize the TiO(2) nanocomposites. The TiO(2) nanocomposites consist of pure anatase particles of about 10 nm. The modification of [Bmim]OH on the surface of the TiO(2) particles extends the TiO(2) absorption edge to the visible-light region. The electrochemical redox potentials indicated that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of [Bmim]OH match well with the valen…

Description and Life History of an Unusual Fern-Feeding Tortricid Moth (Lepidoptera: Tortricidae) from Brazil

2004

Tortrimosaica polypodivora Brown & Baixeras, new genus and new species, is described and illustrated from Sao Paulo, Brazil. We also describe and illustrate the last instar and pupa and provide notes on the life history. Larvae of the new species are gall inducers on the stems of Microgramma squamulosa (Kauf.) Sota (Polypodiaceae), an unusual behavior and host for a tortricid. Although placed provisionally in Hilarographini, tribal and subfamilial assignment of the new genus is extremely problematic owing to a mosaic of morphological characters, suggesting placement in a variety of different higher taxa. The larvae have a bisetose L-group on the prothorax, and the pupa has multiple rows of …

Photoelastic stress analysis assisted evaluation of fracture toughness in hydrothermally aged epoxies

2014

The present work has investigated the fracture toughness of a model DGEBA epoxy system subject to Hidro-Thermal aging. A Photoelastic Stress Analysis technique has been implemented, showing the evolution of stresses arising throughout the water uptake process due to the non-uniform swelling of the material. Gravimetric and Dynamic Mechanical Thermal Analyses have further complemented the characterization, showing the onset of plasticization effects with aging. The correlation of all previous characterizations has allowed to conclude that an increase of KIC fracture toughness is obtained at the fully saturated condition. In particular Photoelasticity has also revealed the onset of relevant s…

Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): The importance of major eleme…

2013

article An extensive data set on the compositional variation of tourmaline from granitic pegmatites, from migmatitic gneisses and from various types of hydrothermal veins from the Schwarzwald, Germany, is provided. The investigated tourmalines are members of the alkali and X-vacant groups representing mostly dravite- schorl solid solutions with some analyses belonging to the foitite-Mg-foitite series. Oxygen isotope data on quartz-tourmaline pairs indicate formation temperatures between 550 and 350 °C for most of the quartz-tourmaline veins. Most of the tourmalines show strong sector zonation, fractionating certain major (e.g., Na, Mg), minor (e.g., Ti, Ca) and trace elements (e.g., Sr, Pb,…

Effect of two antihypertensive combinations on metabolic control in type-2 diabetic hypertensive patients with albuminuria: a randomised, double-blin…

2001

The objective of this study was to compare, at equal blood pressure (BP) reduction, the effect of two different combinations on metabolic control and albuminuria in type 2 diabetic hypertensive patients with albuminuria. This was a prospective, randomised, double-blind, parallel, controlled trial carried out in 11 Spanish hospitals. A total of 103 type 2 diabetic patients with stable albuminuria and BP not controlled on monotherapy were randomised of which 93 finished the study. After a 4-week single-blind placebo period, patients were randomised to verapamil SR/trandolapril 180/2 mg (VT) or to enalapril/hydroclorothiazide 20/12.5 mg (EH). Treatment duration was 6 months. The main outcome m…

THERMO-CATALYTIC PROCESSES FOR BIOFUEL PRODUCTION

2017

Chromatographic monitoring of diuretics in urine samples using a sodium dodecyl sulphate—propanol micellar eluent

1994

Abstract The effect of a varying pH, in the range 3−7, on the retention of several diuretics eluted with a sodium dodecyl sulphate (SDS) micellar mobile phase and with UV detection was studied. Significant changes in the capacity factors ( K′ of the diuretics bumetanide, ethacrynic acid, furosemide, probenecid and xipamide were observed. The protonation constants of these compounds were calculated from the k′ data. A study was also performed to select the optimum composition of the mobile phase (pH, concentration of SDS and nature and concentration of alcohol) for the separation of the above diuretics and the diuretics amiloride, bendroflumethiazide, chlorthalidone, hydrochlorothiazide, spi…

The selective oxidative dehydrogenation of ethane over hydrothermally synthesised MoVTeNb catalysts

2002

Mo–V–Te–Nb metal oxide catalysts prepared by hydrothermal synthesis and heat-treated in N2 at high temperatures (600–700 °C) show high activity and selectivity for the oxidative dehydrogenation of ethane to ethene. Yields of ethene of 75% have been obtained at 400 °C on the best catalysts. Dejoz Garcia, Ana Maria, Ana.M.Dejoz@uv.es

Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica

2016

Texto completo del documento Volcanic eruptions involving interaction with water are amongst the most violent and unpredictable geologic phenomena on Earth. Phreatic eruptions are exceptionally difficult to forecast by traditional geophysical techniques. Here we report on short-term precursory variations in gas emissions related to phreatic blasts at Poás volcano, Costa Rica, as measured with an in situ multiple gas analyzer that was deployed at the edge of the erupting lake. Gas emitted from this hyper-acid crater lake approaches magmatic values of SO2/CO21–6 days prior to eruption. The SO2flux derived from magmatic degassing through the lake is measureable by differential optical absorpti…