Search results for "Yield"
showing 10 items of 1338 documents
“Ice” juice from apples obtained by pressing at subzero temperatures of apples pretreated by pulsed electric fields
2016
Abstract The impact of apple pretreatment by pulsed electric field (PEF) on juice extraction using the freezing-assisted pressing was studied. Apple discs were PEF pretreated at electric field strength of E = 800 V/cm and then air blast frozen inside the freezer (− 40 °C). Then, pressing experiments in a laboratory-pressing chamber (2–5 bars) were started at sub-zero temperature (− 5 °C). Time evolution of juice yield and its nutritional qualities were compared for PEF and untreated apple samples. High improvements of juice yield were obtained for freeze-thawed (FT) and PEF + FT samples. The combination of PEF + pressing (5 bar) at sub-zero temperature gave optimum results for juice extrac…
Production of ethyl lactate by activated carbon-supported Sn and Zn oxide catalysts utilizing lignocellulosic side streams
2021
Abstract In this study, activated carbon-supported Sn and Zn oxide catalysts were prepared from hydrolysis lignin and used for the conversion of model solutions of trioses, hexoses, and lignocellulosic biomass hydrolysates to ethyl lactate. Both catalysts, SnO2@AC and ZnO@AC, were able to produce ethyl lactate in high yields. SnO2@AC was a more active and selective catalyst in triose (dihydroxyacetone) conversion, providing 99% yield to ethyl lactate. ZnO@AC, by contrast, was more selective in glucose and hydrolysate conversion, with a yield of 60% and 85%, respectively. The ethyl lactate yields were significantly higher than those from the optimized model solution experiments when using Zn…
Sulfonation of Triphenylphosphines and Separation of Sulfonated Triphenylphosphines by Crystallization and Solvent Extraction
2007
Abstract The effect of sulfonation conditions on the formation of sulfonated triphenylphosphines and their separation from the post‐reaction mixture, containing concentrated sulphuric acid, was studied. The solvent extraction was found to be a suitable technique to separate sulfonated triphenylphosphines from concentrated sulphuric acid, and the purity and yield was higher than obtained by crystallization from various solvents. Tributyl phosphate was a suitable extractant. Sodium salts of sulfonated triphenylphosphines could then be recovered as precipitates by treating the organic phase with the sodium hydroxide solution and separation by crystallization. The solvent extraction simplified …
Polymer-supported molybdenyl thioglycolate as oxygen atom transfer reagent
2000
Abstract Oxo-transfer reactions of a variety of substrates in DMF or methanol using polymer-supported molybdenyl thioglycolate (PSMT) have been investigated. The clean oxidation of Me 2 PhP, n -butanethiol or benzoin to yield Me 2 PhPO, disulfide or benzil, respectively, occurs in high yield. In the presence of air or pyridine N-oxide, a catalytic cycle is accomplished which goes on until the completion of the substrate.
IM-5 zeolite for steam catalytic cracking of naphtha to produce propene and ethene. An alternative to ZSM-5 zeolite
2013
Steam catalytic cracking of naphtha in smaller FCC units can be considered an option to produce more ethene and propene. These units will operate at high reaction temperatures and in the presence of steam. The profitability of these units could be improved with the use of new catalysts with higher activity and hydrothermal stability, without compromising the selectivity to light olefins. We have explored the possibilities of IM-5 zeolite for high temperature steam catalytic cracking (SCC) of a naphtha, as an alternative to commonly used ZSM-5 zeolite. So, we compare the catalytic activity, the effect of operating variables of the process and the yields of interest products between the two z…
Quantification de l’ablation d’un bassin versant marno-calcaire alpin durant le Petit Age Glaciaire par l’étude d’un système lacustre (cas du lac du «…
2002
Measurements of present-day erosion may give heterogeneous results according to the methods used. This article proposes an approach to erosion during the Little Ice Age by the quantitative analysis of detritical materials trapped in a dammed lake. This infill is recognized through two drillings, and these specific observations are supplemented by a seismic reflexion survey which provided a reliable estimate of the geometry of the lake infill. The sedimentary production is calculated from three pieces of data: (1) the surface of the drainage area, (2) duration of the lake system activity and (3) the volume of trapped sediments. From the three determined variables, we propose a detritical product…
Synthesis of Densely Functionalised 5-Halogen-1,3-oxazin-2-ones byHalogen-Mediated Regioselective Cyclisation of N-Cbz-ProtectedPropargylic Amines: A…
2013
A very efficient synthesis of 5-halogen-1,3-oxazin-2-ones has been accomplished by the halocyclisation reaction of chiral nonracemic N-carbobenzyloxy (N-Cbz)-protected propargylic amines by using I-2, Br-2 and Cl-2 as electrophile sources. The nature of the halogen influences the reaction time and yield. However, in all cases the reaction is totally regioselective taking place through a 6-endo-dig process regardless of the nature of the halogen and of the substituents in the starting material. To rationalise the experimental results, theoretical studies at the B3LYP/6-311G* level have been performed.
Planting density, above-ground dry-matter partitioning and fruit quality in greenhouse-grown 'Flordaprince' peach (Prunus persica L. Batsch) trees tr…
1999
SummaryThe effect of planting density on yield, fruit quality and above-ground dry-matter partitioning into vegetative and reproductive organs of six year old peach trees was investigated in Sicily on the very early-ripening cv Flordaprince in greenhouse. Increasing the number of trees per hectare from 1500 to 5000 significantly reduced total above-ground dry matter, trunk cross-sectional area and total leaf area. Differences in growth did not result in substantial modifications in the source-sink relationships between the vegetative and the reproductive organs of the above-ground part of the tree, as shown by the lack of statistical differences in dry-matter partitioning into fruit, leaves…
The role of pyrimidine nucleobase excimers in DNA photophysics and photoreactivity
2009
Abstract Quantum chemical studies using the accurate CASPT2//CASSCF procedure show that π-stacked interactions in biochromophores such as pyrimidine (Pyr) DNA/RNA nucleobases pairs yield excimer-like situations which behave as precursors of processes like charge transfer (CT) or photoreactivity and are the source of the emissive properties in DNA. Examples are the CT between adjacent DNA nucleobases in a strand of oligonucleotides and the photodimerization taking place in cytosine (C) pairs leading to cyclobutanecytosine (CBC) mutants. These processes take place through nonadiabatic photochemical mechanisms whose evolution is determined by the presence and accessibility of conical intersect…
On the Intrinsically Low Quantum Yields of Pyrimidine DNA Photodamages: Evaluating the Reactivity of the Corresponding Minimum Energy Crossing Points
2020
The low quantum yield of photoformation of cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) adducts in DNA bases is usually associated with the presence of more favorable nonreactive decay paths and with the unlikeliness of exciting the system in a favorable conformation. Here, we prove that the ability of the reactive conical intersection to bring the system either back to the absorbing conformation or to the photoproduct must be considered as a fundamental factor in the low quantum yields of the mentioned photodamage. In support of the proposed model, the one order of magnitude difference in the quantum yield of formation of the cyclobutane thymine dimer with respect to the t…