Determination of total nitrogen content by different approaches in petroleum matrices

Two analytical methods are developed and validated for determination of low total nitrogen levels (below 0.0150%) in different petroleum matrices. The experimental and the instrumental conditions are optimized during the study. The oxidative combustion method with chemiluminescence’s detection is automatic with less handling while the Kjeldahl method involves more manual handling procedures and hence, has more potential for problems rise from contamination. The oxidative combustion with chemiluminescence’s detection method is more sensitive, faster (i.e. the determination requires few minutes compared to several hours with Kjeldahl method) and lees hazardous (i.e. no handling of dangerous boiling sulfuric acid). The estimated analytical characteristics suggest that two methods are reliable: the mean values of recovery for the Kjeldahl method and the other method are respectively 91.5% and 98.6%. The relative uncertainties are less than 2.5% and 2.8% respectively for the developed methods. The detection limits, based on the triple standard deviation, are 5 and 0.03 mgN kg⁻¹ respectively.     

Bioavailability and Antioxidant Activity of Black Chokeberry (Aronia melanocarpa) Polyphenols: in vitro and in vivo Evidences and Possible Mechanisms of Action: A Review

Abstract: Black chokeberry (Aronia melanocarpa) is a distinctive berry with a high content of polyphenol compounds and possesses one of the highest in vitro antioxidant activities among fruits. The bioavailability of aronia polyphenols seems to be low, but there is ample evidence for chokeberry health benefits including antidiabetic, cardioprotective, hepatoprotective, antimutagenic, and anticarcinogenic effects. This review presents the available information for the bioavailability and antioxidant activity of chokeberry polyphenols and explains the possible mechanisms of action in vivo in the prevention and treatment of oxidative stress‐related diseases. The review shows the available data for chokeberry antioxidant activity in vitro, in isolated cells and cell lines, and in vivo, in both human subjects and animals. It is evident that in vivo antioxidant action of chokeberry extends far beyond radical scavenging and includes suppression of reactive oxygen and nitrogen species formation, inhibition of prooxidant enzymes, restoration of antioxidant enzymes, and probably cellular signaling to regulate the level of antioxidant compounds and enzymes. The original contribution of this work is that it compiles the available information up to date and outlines the gaps and future directions in the assessment of chokeberry antioxidant action in vivo.     

Methanol Oxidation over Iron-Molybdate Catalysts: Optimization of the Process

This research aims to shed more light on the possibilities to optimize the process of selective oxidation of methanol over oxide catalysts using an adiabatic layer by determining border values of basic parameters of the process in the adiabatic layer that ensure a maximum rate of methanol oxidation at high selectivity. Laboratory experiments were performed to clarify the influence of the most important parameters of the process (temperature, space velocity and methanol concentration) on the efficiency of the adiabatic layer. An industrial experiment was carried out to verify the results obtained.     

UV damage of the anterior ocular surface – microstructural evidence by in vivo confocal microscopy

Purpose

To evaluate and describe the microstructural changes at the ocular surface in response to habitual ocular sun exposure, correlate them with the UV protection habits and follow their dynamics using in vivo confocal microscopy(ICM).

On the optimal planning of a hydrogen refuelling station participating in the electricity and balancing markets

This paper presents an optimisation model to assess the techno-economic feasibility of a hydrogen refuelling station, which purchases power from the electricity market, supplies the mobility sector with hydrogen, and participates in the ancillary service market. The problem is formed as a mixed-integer nonlinear programming model to investigate the optimal operational plans considering the nonlinear behaviour of an electrolyser and grid costs calculation model. Obtained results from various scenarios in 2020 and 2030 show that participation in the reserve market considering optimal sizing and dispatch of components increase revenues up to 16%, and as a result, decrease the hydrogen break-even price by up to 4.7% and 6.4% in 2020 and 2030, respectively. Exemption from tax and levies for connection to the grid reduces the hydrogen break-even price by up to 13%. Plant operators could benefit from the proposed approach to schedule components reliably while meeting the hydrogen demand and maximising the annual profits.     

Solution processable,precursor based zinc oxide buffer layers for 4.5% efficient organic tandem solar cells

In this work we present regular and inverted organic tandem solar cells from poly[N-9′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole): [6,6]-phenyl C₇₀-butyric acid methyl ester (PCDTBT:PC₇₁BM) with power conversion efficiencies of up to 4.5%. The recombination zone comprises an electron conducting, precursor based zinc oxide buffer layer that was applied from solution under ambient conditions and at moderate processing temperatures. Optimized active layer thicknesses in both subcells were derived from optical Transfer Matrix simulations. The short circuit current density of the tandem cell exceeds half the short circuit current density of the single absorber cells indicating a real gain in quantum yield when utilizing the tandem architecture.     

Bioactive phytonutrients (omega fatty acids,tocopherols, polyphenols), in vitro inhibition of nitric oxide production and free radical scavenging activity of non-cultivated Mediterranean vegetables

Hydroalcoholic extracts from 18 non-cultivated vegetables traditionally consumed in Southern Italy were tested for their free radical scavenging activity (FRSA) in the DPPH (1,1-diphenyl-2-picrylhydrazil radical) screening assay and for their in vitro inhibition of nitric oxide (NO) production. The strongest activity was shown for Rubus caesius (leaves), Mentha spicata subsp. glabra (leaves) and Origanum vulgare subsp. viridulum (stems and leaves) with IC₅₀ values of 5, 6, 8 μg/ml, respectively. Extracts from non-cultivated Foeniculum vulgare subsp. piperitum (seeds), Amaranthus retroflexus (leaves) and M. spicata subsp. glabra (leaves) showed high in vitro inhibition of nitric oxide production, with an activity comparable to a reference drug, indomethacin. A significant cytotoxic effect was shown for the seeds of F. vulgare subsp. piperitum. A. retroflexus (leaves) presented the highest content in linoleic acid. R. caesius and M. spicata subsp. glabra had relatively high polyphenols content, 482 and 334 mg/g of extract, respectively.     

High-range-resolution velocity-estimation techniques for coherent Doppler lidars with exponentially shaped laser pulses

On the basis of an analysis of the autocovariance of the complex heterodyne signal, some novel algorithms are derived and investigated for recovering the nonuniform Doppler-velocity coherent-lidar profiles within the lidar resolution interval conditioned by the sensing laser-pulse length. The case of exponentially shaped sensing laser pulses is considered. The algorithm performance and efficiency are studied and illustrated by computer simulations (based on the use of pulse models and real laser pulses), taking into account the influence of additive noise and radial-velocity fluctuations. It is shown that, at some reasonable number of signal realizations used and with appropriate data processing to suppress the noise effects, the Doppler-velocity profiles can be determined with a considerably shorter resolution interval in comparison with that (usually accepted as a lower bound) determined by the pulse length.     

Ex-situ bioremediation of polycyclic aromatic hydrocarbons in sewage sludge

Polycyclic aromatic hydrocarbons (PAH) are regarded as environmental pollutants. A promising approach to reduce PAH pollution is based on the implementation of the natural potential of some microorganisms to utilize hydrocarbons. In this study Proteiniphilum acetatigenes was used for bioaugmentation of sewage sludge to improve the PAH removal. Bioaugmentation experiments were performed in parallel semi-continuously fed reactors started up with digested primary and secondary sludge. Three bioaugmentation approaches were investigated: A1, addition of bacteria once during starting up; A2, addition of bacteria at the beginning and then every 2nd day and A3, addition of encapsulated bacteria once during starting up. Removal of PAH was found to be both biotic and abiotic. All three approaches had a positive effect of the biological removal of PAH. Highest biological removal of individual PAH (up to 80%) was observed using continuous addition (approach A2) of the bacteria to the reactors. In general, the effect of bioaugmentation was higher in the reactors fed with primary sludge compared to the reactors fed with mixed sludge. Bioaugmentation resulted in biological removal of low molecular weight PAH in the reactors fed with primary sludge using all three approaches while clear biological removal of the medium- and high molecular weight PAH only was observed if the bacteria were added continuously (approach A2).