1,720,994 research outputs found
Aukštesnės pridėtinės vertės komponentų išskyrimas iš sidabražolės (Potentilla fruticosa) ir kvapiosios stumbražolės (Hierochloe odorata) taikant aukšto slėgio ir fermentinės ekstrakcijos metodus.
No full textPotentilla fruticosa is a shrubby perennial plant, native to Northern areas of America and Europe. It is commonly consumed as an herbal tea and exhibits great antioxidant potential as well as antifungal, antibacterial and anti-inflammatory properties. Hierochloe odorata is an aromatic perennial grass, widely distributed in West Asia and Europe, whose roots and aerial parts have a sweet smell. H. odorata extracts have shown to have high antioxidant activity and insect-repellent properties. The aim of this work was to isolate and analyze functional characterization of high-added value fractions of P. fruticosa and H. odorata through the development of biorefining schemes utilizing conventional, high-pressure, and enzymatic treatment techniques. The chemical composition of P. fruticosa and H. odorata was studied using various basic methods. Conventional and high-pressure extraction techniques like Solid liquid extraction and supercritical carbon dioxide extraction, pressurized liquid extraction and enzyme assisted extraction were applied on P. fruticosa and H. odorata. Defatted P. fruticosa and H. odorata residues after supercritical carbon dioxide extraction were used for further extraction techniques. PLE conditions were optimized using response surface methodology to maximize the extraction yield and phenolic content. Enzyme assisted extractions of defatted plant material and water residue from PLE of P. fruticosa and H. odorata were performed. Total phenolic content was determined using Folin-Ciocalteu’s technique and antioxidant activity was measured by DPPH• and ABTS•+ assays. Initial solid plants materials, SLE and SFE-CO2 residue antioxidant activity were analyzed using QUENCHER procedure. SLE, SFE-CO2, PLE, enzyme treated extracts total phenolic content was determined using Folin-Ciocalteu’s technique. Antioxidant activity was measured by DPPH• and ABTS•+ assays. The phytochemical characterization of volatile compounds of P. fruticosa and H. odorata SFE-CO2 extracts were analyzed by GCxGC/TOF MS, chemical compounds of P. fruticosa and H. odorata PLE extracts were analyzed using UPLC/ESI-QTOF-MS/MS
Aukštesnės pridėtinės vertės komponentų išskyrimas iš titnaginių dumblių ir in vitro antioksidacinio aktyvumo įvertinimas.
No full textDiatom, Phaeodactylum tricornutum, was cultivated with various copper and iron concentrations. Copper and iron stress on Phaeodactylum tricornutum growth, changes in antioxidant activity and phenolic content were examined. Very high concentrations of copper and iron inhibited growth of Phaeodactylum tricornutum, lower but still relatively high concentrations of copper and iron negatively affected growth, but increased antioxidant activity and phenolic content of cultivated biomass. Diatoms Phaeodactylum tricornutum and Cylindrotheca closterium were cultivated with different glycerol concentrations. Their ability to grow under mixotrophic conditions were tested, changes in growth, antioxidant activity, phenolic content, fatty acid profile were examined. Phaeodactylum tricornutum and Cylindrotheca closterium were able to grow under mixotrophic conditions, glycerol addition promoted growth of both diatoms, with that antioxidant activity, phenolic content and fatty acid content were increase in both diatoms also. Phaeodactylum tricornutum pressurized liquid extraction (PLE) with three increasing polarity solvents (hexane, acetone, ethanol) at three temperatures (40oC, 80oC, 120oC) and three extraction times (15min, 39min, 60min) were performed. Total yield, EPA and DHA content in lipophilic fractions obtained by pressurized liquid extraction under various experimental conditions were examined. Total yield. total phenolic content (TPC) and in vitro antioxidant activity as measured by the ABTS+ assay in polar fractions obtained by pressurized liquid extraction under various experimental conditions were examined. Manufacturing process technology scheme for production of Phaeodactylum tricornutum extract using pressurized liquid extraction (PLE) was proposed
Phaeodactylum tricornutum biomasės perdirbimas į vertingus funkcionaliuosius komponentus taikant aukšto slėgio ekstrakcijos metodus.
No full textPhaeodactylum tricornutum, the only species in the genus Phaeodactylum, belongs to a significant group of microalgae called diatoms. P. tricornutum is considered a promising feedstock of high-value products. Mainly, due to its ability to synthesize polyunsaturated fatty acids, like eicosapentaenoic acid, and carotenoids, especially fucoxanthin – a valuable pigment with multiple biological activities. This work aimed to develop multi-step P. tricornutum processing schemes for isolation of high-added value fractions using conventional and high-pressure extraction techniques. Various standard methods achieved the determination of chemical composition. Conventional and high-pressure extraction techniques like solid-liquid extraction (SLE), supercritical fluid extraction (SFE), and pressurized liquid extraction (PLE) were applied using various solvents in order to obtain extracts of various polarity. The high-pressure extraction techniques, SFE and PLE, were optimized using response surface methodology (RSM) in order to maximize total yield, carotenoid, and fucoxanthin content. In vitro antioxidant capacity of initial material, as well as all extracts were determined using the total phenolic content (by the Folin-Ciocalteu method), DPPH• and ABTS•+ assays. The activity of solid residues was tested with the same in vitro antioxidant capacity assays following the QUENCHER approach. The qualitative determination of pigments and quantitative determination of fucoxanthin content was performed using HPLC-DAD. The fatty acid profile was determined using GC-FID. Moreover, for all extracts, the antimicrobial activity was using the disc diffusion assay, determining the minimal inhibitory concentration for the active ones. This work demonstrates the feasibility of high-pressure techniques for the isolation of high-added value products from this rather underutilized feedstock
Aukštesnės pridėtinės vertės komponentų išskyrimas iš stambiašaknio snapučio (Geranium macrorrhizum) ir paprastojo rapontiko (Rhaponticum carthamoides) taikant auškto slėgio ekstrakcijos metodus.
No full textGeranium macrorrhizum is a perennial herbaceous plant of the Geraniaceae family, widely found in Central Europe. Rhaponticum carthamoides belongs to Asteraceae family, Rhaponticum Vaill. genus, it is widely consumed for centuries in Russia and Eastern Europe. Both plants are used in a folk medicine for its analgesic, antimicrobial, antioxidant, hypotensive, spasmolytic, astringent, cardiotonic, hepatoprotective properties and capillary sedative activities. This research was aimed to isolate and analyse bigroot geranium and maral root, grown in Lithuania, components by high-pressure extraction techniques. In order to achieve this goal, two different high-pressure extraction techniques were carried out: supercritical carbon dioxide extraction and pressurized liquid extraction. Solid fat-free plant residues after supercritical carbon dioxide extraction were used for pressurized liquid extraction. SFE-CO2 conditions were optimized using response surface methodology to maximize the extraction yield. PLE conditions were optimized using response surface methodology to maximize the extraction yield, total phenolic content and antioxidants activity. SFE-CO2 geranium and maral root extract’s total phenolic content was determined using Folin-Ciocalteu’s technique. Antioxidant activity was measured by DPPH• and ABTS•+ assays, oxygen radical absorbance was measured by ORAC assay. Solid plants initial material and SFE-CO2 residues were analyzed using same methods approaching QUENCHER procedure. PLE geranium extract’s total phenolic content was determined using Folin-Ciocalteu’s technique. Antioxidant activity was measured by DPPH• (EC50) and ABTS•+ assays. Tentative chemical characterization of non-volatile compounds of geranium and maral root SFE-CO2 extracts were analyzed by UPLC/ESI-QTOF-MS, volatile compounds were analyzed using GCxGC/TOF MS. Characterization of phenolic profile of geranium PLE extract was performed using UPLC/ESI-QTOF-MS/MS
Ekstrakcijos procesų optimizavimas ir biorafinavimo schemų sukūrimas perdirbant melsvabakteres į aukštos pridėtinės vertės produktus.
No full textCyanobacteria are photosynthetic microorganisms widely distributed around the world. In water, cyanobacteria can live in large colonies and create water blooms. Over the last decades, the presence of wild cyanobacterial blooms has also been reported in the Curonian Lagoon. Recent reports indicate that priority should be given to the removal of wild cyanobacterial blooms from the Curonian Lagoon as a management measure. In this study, the utilization of wild cyanobacteria as a potential source of high added products is reported. Lipophilic products from wild cyanobacteria was isolated from Curonian Lagoon by supercritical carbon dioxide extraction (SFE-CO2) and the yield, under optimal conditions, was compared with conventional Soxhlet extraction. Under optimal conditions (42.5 MPa, 55 ºC and 120 min), SFE-CO2 yielded 4.43 g/100 g DW of non-polar extract, showing 20% higher extraction efficiency at 3-fold lower extraction time as compared to the conventional Soxhlet extraction. The SFE-CO2 extract under optimal conditions was also evaluated by determining fatty acids, tocopherols and in vitro antioxidant activity. Results showed that it was rich in α-linolenic acid (27% of total fatty acids) and α-tocopherol (293 μg/g extract). Phycobiliproteins from wild cyanobacteria was isolated by several traditional extraction methods, of which the most effective was homogenization (one cycle, 30 min, 30 ºC), but after combining traditional methods with ultrasound assisted extraction (UAE) the freeze-thaw extraction with liquid nitrogen combined with UAE had the highest yield of phycobiliproteins (139.28 mg/g DW) under optimal conditions (one cycle of freeze-thaw and 99 % of amplitude, 9.39 min of UAE). The antioxidant activity of phycobiliproteins extracts was evaluated by in vitro methods. 8 Central composite design (CCD) and response surface methodology (RSM) were employed to optimize SFE-CO2, phycobiliproteins extractions parameters (temperature, pressure, amplitude and time) to obtain high yield extracts. Biorefinery was performed by removal of lipophilic fraction using SFE-CO2 or solid liquid extraction (SLE) with hexane, and by removal of phycobiliproteins using homogenization combined with UAE, and then performing accelerated solvent extraction (ASE) to extract the remaining materials by polarity. The extracts yield after ASE from fresh wild cyanobacterial biomass was 5.9 and 2.8 times higher than extracts yield after ASE and after SFE with phycobiliproteins removal and extracts yield after ASE and after SLE with phycobiliproteins removal, respectively. The ASE and SLE extracts from fresh cyanobacterial biomass was also evaluated by determining fatty acids and all ASE extracts was evaluated by determining in vitro antioxidant activity. Results of fatty acids detection showed that the most abundant fatty acid was α-linolenic acid: 225.86 mg/g in ASE extract with hexane at 55 ºC (32 %), 260.85 mg/g in ASE extract with hexane at 70 ºC (34 %) and 430 mg/g in SLE extract (36 %). All these extracts showed higher yield of α-Linolenic acid comparing with SFE-CO2 or Soxhlet extracts. Thus, SFE-CO2, phycobiliprotein extractions and ASE methods could be utilized to valorize wild cyanobacteria into high-added value products with various industrial applications
Occurrence and synthesis of bacterial metabolites in the marine environment and study of their chemical interactions with diatoms
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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