Filters
total: 1455
filtered: 1143
displaying 1000 best results Help
Search results for: UNSATURATED FATTY ACID
-
Modelling water flow in unsaturated porous media: Accounting for nonlinear permeability and material heterogeneity
PublicationW pracy przedstawiono problematykę matematycznego modelowania przepływów w nienasyconych ośrodkach porowatych, ze szczególnym uwzględnieniem dwóch aspektów. Pierwszym z nich jest obliczanie średniego współczynnika przewodności hydraulicznej między węzłami siatki w numerycznym rozwiązaniu równania przepływu nienasyconego. Drugim zagadnieniem jest wpływ lokalnej zmienności parametrów ośrodka porowatego (współczynnika przewodności...
-
Computing internodal conductivities in numerical modeling of two dimensional unsaturated flow on rectangular grid
PublicationW artykule porównano rozwiązania numeryczne dwuwymiarowego równania przepływu nienasyconego z użyciem różnych metod uśredniania współczynnika przewodności hydraulicznej między sąsiednimiwęzłami. Uwzględniono średnia arytmetyczną, geometryczną, "pod prad" oraz całkową, a także niedawno zaproponowany sposób uśredniania oparty na analizie przepływu ustalonego. Ten ostatni sposób okazałsię najbardziej uniwersalny, gdyż umożliwiał otrzymanie...
-
Encapsulation of Amikacin into Microparticles Based on Low-Molecular-Weight Poly(lactic acid) and Poly(lactic acid-co-polyethylene glycol)
PublicationThe aim of this study was to fabricate novel microparticles (MPs) for efficient and long-term delivery of amikacin (AMI). The emulsification method proposed for encapsulating AMI employed low-molecular-weight poly(lactic acid) (PLA) and poly(lactic acid-co-polyethylene glycol) (PLA−PEG), both supplemented with poly(vinyl alcohol) (PVA). The diameters of the particles obtained were determined as less than 30 μm. Based on an in-vitro...
-
Electron attachment and electron iozization of acetic acid clusters embedded in helium nanodroplets
PublicationThe effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic productsejected in to the gas phase aredetected by mass spectrometry.
-
ASCORBIC ACID IN POLYURETHANE SYSTEMS FOR TISSUE ENGINEERING
PublicationThe introduction of the paper was devoted to the main items of tissue engineering (TE) and the way of porous structure obtaining as scaffolds. Furthermore, the significant role of the scaffold design in TE was described. It was shown, that properly designed polyurethanes (PURs) find application in TE due to the proper physicochemical, mechanical and biological properties. Then the use of L-ascorbic acid (L-AA) in PUR systems for...
-
Interaction of low energy electrons with formic acid monomer, dimer and trimer
PublicationConfigurations of the formic acid monomer, dimer and trimer are presented. We have calculated the total energies for these structures. We have considered also the negatively charged clusters and discussed the possible pathways of interaction of low energy electrons with monomers and clusters. Calculations have been executed using 6-311G** and 6-311++G** basis sets. The electron affinities of monomer and clusters are presented....
-
Synthesis and biological activity of mycophenolic acid-amino acid derivatives
Publication -
CROSS SECTIONS CALCULATIONS FOR ELECTRON SCATTERING FROM RHODANINE AND CYANOACETIC ACID
PublicationCross sections for electron-impact ionization and for elastic electron scattering for rhodanine (C3H3NOS2) and cyanoacetic acid (C3H3NO2) have been calculated in wide impinging electron energy range.
-
The synthesis and structure of a potential immunosuppressant: N-mycophenoyl malonic acid dimethyl ester
PublicationThe synthesis of a potential immunosuppressant, i.e. dimethyl ester of N-mycophenoyl malonic acid was optimized in the reaction of mycophenolic acid (MPA) with amino malonic dimethyl ester in the presence of propanephosphonic anhydride (T3P) as a coupling reagent. The structural properties of the obtained MPA derivative were investigated by NMR, MS and single crystal X-ray diffraction methods. Theoretical considerations of conformational...
-
Thermal energy storage using stearic acid as PCM material
PublicationThis work presents an experimental study of thermal energy storage by use of PCM. The aim of the study was to establish the influence of different inlet temperature of heat transfer fluid (HTF) and different Reynolds number of HTF on intensity of charging process. The PCM used in this study was stearic acid and water was used as HTF. A copper helical coil mounted in cylindrical container served as a heat transfer surface.
-
The effect of high pressure and sub-zero temperature on total antioxidant capacity and the content of vitamin C, fatty acids and secondary products of lipid oxidation in human milk
PublicationThe objective of this study was to compare of the effects of high pressure of 193 MPa at - 20°C and Low Temperature Long Time pasteurization (LTLT or holder pasteurization, 62,5°C; 30 min) on the content and composition of fatty acids (FAs), concentrations of secondary products of lipid oxidation (TBARS), the total antioxidant capacity (TAC), total vitamin C and ascorbic acid (AsA) content in human milk. It was shown that no significant...
-
Collagen and hyaluronic acid hydrogel in water-in-oil microemulsion delivery systems
PublicationThe efficacy of microemul-sion in dermal and transdermal delivery of active ingredients. Here, we assessed the water-in-oilmicroemulsion capacity to incorporate two natural polymers, i.e. collagen and hyaluronic acid withlow and high molecular weight. Systems were extensively characterized in terms of conductivity, phaseinversion studies, droplet diameter, polydispersity index and rheological properties. The results of thisresearch...
-
Application of Headspace Solid-phase Microextraction with Poly(1-vinyl-3- Hexylimidazolium Chloride) Polymeric Ionic Liquid Coating using GC - MS to Determine Volatile Fatty Acids in Dairy Wastewater
PublicationVolatile fatty acids were determined in this study using headspace solid-phase microextraction (HS-SPME) with a poly(1-vinyl-3-hexylimidazolium chloride) polymeric ionic liquid coated fiber followed by gas chromatography - mass spectrometry. Experimental parameters such as extraction time and temperature, sample volume as well as desorption time and temperature were optimized. Detection limits of the method were in the range of...
-
The Use of Raman Spectroscopy to Monitor Changes in the Intensity of Ratio of Integral Unsaturated Bands in Bio-Greases
Publication -
Occurrence and Determination of Volatile Fatty Acids in Wastewater of Different Origin
PublicationOpracowano metodykę oznaczania krótkołańcuchowych alifatycznych kwasów monokarboksylowych w ściekach rożnego pochodzenia stosując ekstrakcję za pomocą eteru metylo-tert-butylowego na etapie przygotowania próbek i chromatografię gazową z kolumną kapilarną Stabilwax-DA i Rtx-624, natomiast na etapie detekcji stosowano spektrometr mas.
-
Peroxidative metabolism of fatty acids in the course of tick-borne encephalitis
Publication -
Green Analytical Chemistry in Determination of Volatile Fatty Acids in Wastewater
PublicationCharakterystyka metodyk oznaczania lotnych kwasów tłuszczowych w próbkach wodnych, opierających się na Zasadach Zielonej Chemii. Opis zastosowania techniki bezpośredniego dozowania próbki wodnej do chromatografu gazowego, techniki analizy fazy nadpowierzchniowej oraz techniki mikroestrakcji do fazy stacjonarnej.
-
Photoresponsive, amide-based derivative of embonic acid for anion recognition
PublicationThe synthesis and ion-binding properties of amide-based derivative of embonic acid andp-aminoazobenzenewere described. The new compound was characterized by X-ray structural analysis and spectroscopic methods.Ligand interacts in acetonitrile with Y-shaped anions (benzoates and acetates) and dihydrogen phosphatesforming complexes of 1:1 stoichiometry. In more polar DMSO the complexes stoichiometry changes to 2:1(L:anion). Light-inducedtranstocisisomerization...
-
Electron-impact ionization cross section of formic acid
PublicationExperimental electron-impact ionization cross sections of one of the simplest carboxylic acids, formic acid, are presented. The molecular target was studied in two independent experimental setups applying different methods: the total ion collection and the electron–impact mass spectrometry methods. Experimental data were taken at incident electron energies ranging from ionization threshold [11.31 eV; J.C. Traeger, Int. J. Mass...
-
Investigations on the immunosuppressive activity of derivatives of mycophenolic acid in immature dendritic cell
PublicationThe main activity of mycophenolic acid (MPA) and its analogs is the inhibition of proliferation of T cells. Here, we hypothesized that MPA and its conjugates inhibits also the activity of antigen-presenting cells (APC) including dendritic cells (DCs). We tested the effect of novel amino acid derivatives of MPA and conjugates of MPA with acridines/acridones on DCs by flow cytometry, ELISA and MLR assay. Both acridines/acridone derivatives...
-
Novel amides of mycophenolic acid and some heterocyclic derivatives as immunosuppressive agents
PublicationThe group of new amide derivatives of mycophenolic acid (MPA) and selected heterocyclic amines was synthesised as potential immunosuppressive agents functioning as inosine-5'-monophosphate dehydrogenase (IMPDH) uncompetitive inhibitors. The synthesis employed uronium-type activating system (TBTU/HOBt/DIPEA) while or phosphonic acid anhydride method (T3P/Py) facilitating amides to be obtained in moderate to excellent yields without...
-
Diamine derivatives of dimerized fatty acids and bio-based polyether polyol as sustainable platforms for the synthesis of non-isocyanate polyurethanes
PublicationA series of environmentally friendly non-isocyanate polyurethanes (NIPUs) were successfully prepared via the polyaddition reaction of bio-based polyether polyol-based cyclic carbonate with diamine derivative of dimerized fatty acids. The syntheses of NIPUs were realized by the three-step method in the absence of toxic solvents and, importantly, the process of carbonation did not require the use of elevated pressure. The effect...
-
Improvement of derivatized amino acid detection sensitivity in micellar electrokinetic capillary chromatography by means of acid-induced pH-mediated stacking technique
PublicationDerivatization is a frequently used sample prepara-tion procedure applicable to the enhancement of analyte de-tection sensitivity. Amino acids mostly require derivatization prior to electrophoretic or chromatographic analysis, especial-ly if spectrophotometric detection is used. This study presents an on-line preconcentration technique for derivatized amino acids. The sensitivity of the method was improved by the utilization of...
-
Experimental investigation on heat pipes supported by soy wax and lauric acid for electronics cooling
PublicationThis paper presents an experimental study of heat pipes for electronics cooling that were supported by energy storage materials (i.e. phase change materials - PCMs) coated at the adiabatic section. The PCMs utilized included two materials, namely lauric acid and soy wax, the latter being considered as a more cost-effective alternative. The study focused on three different powers: 20 W, 25 W, and 30 W. Both heating, cooling, and...
-
The mechanical properties and bactericidal degradation effectiveness of tannic acid-based thin films for wound care
PublicationThe surface area is the most important aspect when considering the interactions between a material and the surrounding environment. Chitosan (CTS) and tannic acid (TA) were previously successfully tested by us to obtain thin films to serve as wound dressings or food packaging materials. However, surface properties as well as the antimicrobial activity of the material were not considered. They are important if the material is likely...
-
Dissociation of furan-2-carboxylic acid by low energy electrons
PublicationElectron attachment to molecular target can lead to a variety of negative fragment ions. We experi- mentally probe the main dissociative electron attachment channels in furan-2-carboxylic acid (C3H3O2 − COOH) - a molecular target composed of two important structural units: a furan ring and a carboxylic group. In our studies we utilise nearly mono-energetic electrons at electron energies from 0 eV up to 15 eV. Our detection setup...
-
Dissociative electron attachment and anion-induced dimerization in pyruvic acid
PublicationWe report partial cross sections for the dissociative electron attachment to pyruvic acid. A rich fragmentation dynamics is observed. Electronic structure calculations facilitate the identification of complex rearrangement reactions that occur during the dissociation. Furthermore, a number of fragment anions produced at electron energies close to 0 eV are observed, that cannot originate from single electron-molecule collisions....
-
Preparation of Pseudopeptides Building Blocks with Retro-Thioamide Bond Mediated via Thiocarbamoyl Meldrum's Acid
PublicationAn easy and efficient synthesis of pseudo tripeptide containing a thiomalonamide moiety was developed. Isothiocyanate derivatives of amino acids react smoothly with 2,2-dimethyl-1,3-dioxane-4,6-dione yielding new thiocarbamoyl Meldrum's acids. Thermal decomposition of this new Meldrum's acid derivatives generate thiocarbamoyl ketenes, which acylate amino acid esters to give pseudo tripeptides.
-
Synthesis, chemical structure and properties of cross-linked poly(esterourethanes) based on unsaturated oligo(alkyleneester)diols
PublicationW pracy przedstawiono wyniki badań struktury chemicznej i właściwości nienasyconych oligo(alkilenoestro)dioli oraz syntetyzowanych z ich udziałem poli(estrouretanów). Strukturę oligomeroli oraz poliuretanów ustalono w oparciu o wyniki badań FTIR, NMR, analizę elementarną. Właściwości poli(estrouretanów) określono przez pomiary stabilności termicznej, analizę termomechaniczną oraz obliczenia ciężaru cząsteczkowego łańcuchów polimerowych...
-
Modelling of Capillary Pressure-driven Water Flow in Unsaturated Concrete Using Coupled DEM/CFD Approach.
PublicationSformułowano nowatorskie, połączone podejście do modelowania dwufazowego przepływu wody napędzanego kapilarami w nienasyconym betonie. Dzięki połączeniu metody elementów dyskretnych (DEM) z obliczeniową dynamiką płynów (CFD) w warunkach izotermicznych proces został zbadany numerycznie w mezoskali w warunkach dwuwymiarowych. Niewielkie próbki betonu o uproszczonej mezostrukturze cząstek poddano w pełni sprzężonym hydromechanicznym...
-
Formation, occurrence and determination of volatile fatty acids in environmental and related samples
PublicationKrótkołańcuchowe alifatyczne kwasy monokarboksylowe mogą być oznaczane w różnych próbkach środowiskowych,za pomocą techniki mikroekstrakcji do fazy stacjonarnej z fazy nadpowierzchniowej na etapie przygotowanie próbek oraz chromatografii gazowej sprzężonej ze spektrometrią mas na etapie oznaczeń końcowych.Opracowana metodykę z powodzeniem zastosowano do oznaczenia tych kwasów w próbkach ścieków pochodzących z farmy bydła.
-
A Comprehensive Review of Chemistry, Sources and Bioavailability of Omega-3 Fatty Acids
Publication -
Characterization of fatty acids composition in the European beaver (Castor fiber L.).
PublicationW pracy przedstawiono zawartość lipidów , klas lipidów i skład kwasów tłuszczowych lipidów ogólnych uzyskanych z różnych tkanek bobra europejskiego (tkanka okołojelitowa, tkanka okołonerkowa, miesień uda, mięsień kreskowy, podskórna tkanka tłuszczowa, ogon). Wykazano różnice w zawartości lipidów i składzie KT w tkankach samic (n=7) i samców (n=3). Wykazano wysokie zawartości nienasyconych KT w tkankach bobrów w porównaniu z tkankami...
-
Chromogenic amides of pyridine-2,6-dicarboxylic acid as anion receptors
PublicationThe synthesis of simple, chromogenic pyridine-2,6-dicarboxylic acid amides, derivates of isomeric nitroanilines and aminonitrophenols, and their ion binding properties are described. The ligands' response to ionic species was examined by naked eye and was studied with the use of UV-Vis spectroscopy in DMSO and its mixture with water. The effect of the localisation and the type of the substituents in aromatic rings were discussed....
-
Atom-economic thiophosphoroselenenylations of C–H acid esters and amides
PublicationThree improved thiophosphoroselenenylation procedures of CHacids, including derivatives of malonic and acetyl-, phosphono-, 4-nitrophenyl- and 3-pyridylacetic acids, have been described and compared to previously reported thiophosphoroselenylation of diethyl malonate using bis(disopropoxyphosphinothioyl)diselenide alone or with the aid of methyl iodide. The use of iodine makes it possible to utilize both equivalents of the selenenylating...
-
Synthesis and antiproliferative activity of new mycophenolic acid conjugates with adenosine derivatives
PublicationNew conjugates of mycophenolic acid (MPA) and adenosine derivatives were synthesized and assessed as potential immunosuppressants on Jurkat cell line and peripheral blood mononuclear cells (PBMC) from healthy donors. As compared to MPA, all compounds were found to be more active against Jurkat cell line. The antiproliferative activities were compared with MPA and adenosine, in both 2′,3′-O-isopropylidene protected and free hydroxyl...
-
Investigation of corrosion behavior of 6060 and 6082 aluminum alloys under simulated acid rain conditions
PublicationInstantaneous impedance changes of 6060 and 6082 type aluminum alloys in pure water, and simulated acid rain poured into the pure water was investigated by dynamic electrochemical impedance spectroscopy (DEIS). In this way, the influence of aluminum content on the corrosion behavior of 6060 and 6082 type aluminum alloys immersed in simulated acid rain was determined. The corrosion rate of the alloy decreased with increasing Al...
-
The physicochemical properties of 3D materials based on hyaluronic acid modified by tannic acid addition
Publication -
Influence of the Type of Amino Acid on the Permeability and Properties of Ibuprofenates of Isopropyl Amino Acid Esters
Publication -
Application of Monte-Carlo method to modelling influence of selected soil heterogeneity on macrodispersion of pollutants in unsaturated soil medium
PublicationThe influence of soil heterogeneity on miscible solute transport in soil is analyzed. The transport process is simulated numerically using the Monte-Carlo method. This paper shows how different types of soil heterogeneity influence the process of contaminant spreading. If independent flow paths exist in the soil, the degree of the mixing of pollutants in the outflow from the soil profile is larger. If the preferential flow paths...
-
Single-Step Symmetrical Double Alkylation of β,γ-Unsaturated δ-Lactams via Magnesium ‘Ate’ Complexes
Publication -
Estimation of groundwater recharge in a shallow sandy aquifer using unsaturated zone modeling and water table fluctuation method
PublicationQuantification of groundwater recharge is one of the most important issues in hydrogeology, especially in view of the ongoing changes in climate and land use. In this study, we use numerical models of 1D vertical flow in the vadose zone and the water table fluctuation (WTF) analysis to investigate local-scale recharge of a shallow sandy aquifer in the Brda outwash plain in northern Poland. We show that these two methods can be...
-
On the origin of surfaces-dependent growth of benzoic acid crystal inferred through the droplet evaporation method
PublicationCrystal growth behavior of benzoic acid crystals on different surfaces was examined. The performed experiments documented the existence of very strong influence introduced by polar surfaces as glass, gelatin, and polyvinyl alcohol (PVA) on the growth of benzoic acid crystals. These surfaces impose strong orientation effect resulting in a dramatic reduction of number of faces seen with x-ray powder diffractions (XPRD). However,...
-
On the origin of surfaces-dependent growth of benzoic acid crystal inferred through the droplet evaporation method
PublicationCrystal growth behavior of benzoic acid crystals on different surfaces was examined. The performed experiments documented the existence of very strong influence introduced by polar surfaces as glass, gelatin, and polyvinyl alcohol (PVA) on the growth of benzoic acid crystals. These surfaces impose strong orientation effect resulting in a dramatic reduction of number of faces seen with x-ray powder diffractions (XPRD). However,...
-
On the origin of surfaces-dependent growth of benzoic acid crystal inferred through the droplet evaporation method
PublicationCrystal growth behavior of benzoic acid crystals on different surfaces was examined. The performed experiments documented the existence of very strong influence introduced by polar surfaces as glass, gelatin, and polyvinyl alcohol (PVA) on the growth of benzoic acid crystals. These surfaces impose strong orientation effect resulting in a dramatic reduction of number of faces seen with x-ray powder diffractions (XPRD). However,...
-
Poly-L-Lysine-modified boron-doped diamond electrodes for the amperometric detection of nucleic acid bases
PublicationBoron-doped diamond (BDD) is a very promising supporting material used in the construction of biosensors for molecular recognition. The direct immobilization of structurally-organized huge molecules, such as poly-L-Lysine (PLL) provides the possibility of determining organic molecules, e.g. nucleic acid bases (e.g. adenine, guanine) or peptides and proteins. This paper describes the direct method for chemical and electrochemical...
-
Long chain polyunsaturated fatty acids in smoked Atlantic mackerel and Baltic sprats
PublicationWyniki pracy wykazały, że zmienność w składzie kwasów tłuszczowych w surowcu, (makrela, szprot), pochodzącym z różnych dostaw, była większa niż zmiany wywołane wędzeniem i przechowywaniem wędzonego produktu.
-
Separation of fatty acids, their methyl esters and triacylglycerols by non-aqueous electrochromatography and HPLC.
PublicationElektrochromatografię kapilarną (CEC) oraz HPLC w odwróconym układzie faz zastosowano do rozdzielenia wolnych kwasów tłuszczowych, ich estrów metylowych oraz triacylogliceroli TAG. Zaproponowano własną konstrukcję zestawu laboratoryjnego do CEC oraz sposób preparowania mikrokolumn o średnicy 100 mm i długości złoża (Hypersil ODS 3 mm) 200 mm. Z porównania względnych czasów retencji TAG rozdzielanych technikami CEC i HPLC przy użyciu...
-
Transdermal transport of collagen and hyaluronic acid using water in oil microemulsion
PublicationCollagen and hyaluronic acid (HA) are biopolymers that affect the appearance and condition of the skin. Delivery of these compounds into the skin is highly challenging since have a number of disadvantageous properties, such as high molecular weight and hydrophilicity. Here, we evaluated the transdermal penetration of low and high molecular weight collagen and HA from microemulsions. A number of microemulsion formulations, differing...
-
Deep Eutectic Solvents or Eutectic Mixtures? Characterization of Tetrabutylammonium Bromide and Nonanoic Acid Mixtures
PublicationDeep eutectic solvents have quickly attracted the attention of researchers because they better meet the requirements of green chemistry and thus have the potential to replace conventional hazardous organic solvents in some areas. To better understand the nature of these mixtures, as well as expand the possibilities of their use in different industries, a detailed examination of their physical properties, such as density, viscosity,...