Authors:A. Calvo, J. Morante, Sz. Plánder, and E. Székely
Supercritical fluid extraction (SFE) was used for fractionation of grape seed to be applied in natural products of the food, cosmetic, or pharmaceutical industry. A two-step process was developed, consisting of conventional alcoholic extraction followed by SFE with carbon dioxide. The effects of pressure and concentration of co-solvent (ethanol) at constant temperature and solvent to feed-ratio were evaluated. The antioxidant activity of extracts and raffinates was measured with the DPPH* free radical scavenging assay. It was observed that supercritical carbon dioxide can be used in the described process for fractionation of an alcoholic grape seed extract to obtain a product with noticeably high antioxidant activity and a second one with no antioxidant activity or pro-oxidant activity.
During the production of natural gas one of the major problems is the formation of hydrate crystals in the pipeline. The forming hydrate crystals can form hydrate plugs in the pipeline. The hydrate plugs lengthen production outages and result in financial losses for the producer, because the removal of the plugs is a time consuming procedure. One of the solutions used to prevent hydrate formation is the injection of modern compositions to the gas flow. The modern compositions help to dehydrate the gas, thus, the size of hydrate crystals does not increase. The substances, used in low concentrations, have to be locally injected, at the gas well sites. Inhibitor dosing depends on the amount of gas hydrate present. In the article a neural network based predictive detection solution is presented, which uses four factors.
Authors:B. Oláhné Horváth, E. Fazekas, N. Kellner, and I. Magyar
microfiltration ( Magyar, 2011 ). In some cases, it is a challenge to meet the upper limit of total SO 2 concentration set by EU Commission legislation 607/2009/ EC ( EC, 2009 ). Consequently, any effective SO 2 replacement could facilitate botrytised
Authors:Joanna Wiśniewska, Grzegorz Wrzeszcz, Stanisław Koter, and Tomasz Ligor
direct one-electron transfer between many organic compounds in noncatalytic and catalytic processes, the relatively low oxidation rate and the strong influence of the concentration of sulfate(VI) and the H + ion concentrations on both the rate of
Authors:Magdalena Janus, Ewelina Kusiak-Nejman, and Antoni Waldemar Morawski
temperatures (20, 30, 40, 50, and 60 °C) for 90 min (samples were taken every 10 min). 0.02 g of the photocatalyst was added to 100 mL of terephthalic acid solution with a concentration of 830 mg/L (5 × 10 −4 M). The • OH radicals are generated by means of UV
Authors:Messaouda Rais, Adel Boumerzoug, and Balint Baranyai
usually expressed by the CO 2 concentration in the space and the air ventilation rate [ 12 ]. This study presents the evaluation of a typical existing social house design in Algerian hot and dry climate region, which represent the major part of the
Authors:Elena Burakova, Alexandr Melezhyk, Alyona Gerasimova, Evgeny Galunin, Nariman Memetov, and Alexey Tkachev
In the present research, phenol-formaldehyde resins were used instead of common surfactants for dispersing carbon nanotubes and graphene nanoplatelets in order to develop new composite materials. The use of such resins makes it possible to increase the concentration of nanoparticles in solution by approximately two orders of magnitude. The presence of reactive groups on the surface of the phenol-formaldehyde-resin-modified carbonnanotubes and graphene nanoplatelets promotes synthesis of a variety of composites. According to the experiments performed herein, the modification of the nanomaterials with the phenol-formaldehyde resin significantly improves their compatibility and provides good water-solubility. While dispersing in water, the aggregates of the carbon nanotubes disappear, giving rise to an ordered structure. Besides, they form stable colloidal solutions at slightly alkaline pH values, but coagulate when decreasing the pH. This effect allows for self-assembly of carbon and composite nanostructures from nanoparticles in solution due to pH adjustment. This enables easy synthesis of hybrid composite materials based on carbon nanotubes, graphene nanoplatelets and phenol-formaldehyde resins.
of NaOH solutions of suitable concentrations and assayed. To each sample, 1.0 mL of the internal standard (theophylline 0.1 mg mL −1 ) was added.
HPLC chromatograms of: solution of doripenem at t
Authors:Sz. Gy. Szerencsés, S. Beszédes, Zs. László, G. Veréb, D. Szalay, Zs. Hovorkáné Horváth, C. Hodúr, G. Rákhely, and Sz. Kertész
. Membrane separation processes can be applied for wastewater treatment ( Couto et al., 2018 ). Ultrafiltration ( UF ) and nanofiltration ( NF ) separation technologies, based on the concentration of macromolecules, have many industrial applications: from
, Jenkins D. , Parker D. S.
Relationship between organic loading, dissolved oxygen concentration and sludge settle-ability in the completely-mixed activated sludge process , Journal Water Pollution Control Federation , Vol. 52 , No. 10