wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: CHEMICAL STRUCTURE
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Application of nonlinearity measures to chemical sensor signals
PublikacjaSzumy rezystancji sensorów gazu zawierają istotną informację, która może być przedstawiona nie tylko przez ich gęstość widmową mocy. Analiza tych szumów za pomocą różnych miar nieliniowości może prowadzić do znacznego wzrostu selektywności i czułości czujników gazu. Stwierdzono, że dla dostępnych na rynku czujników gazu zastosowanie funkcji bispektrum dostarcza dodatkowej informacji, potrzebnej do detekcji różnych gazów. Analizując...
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Selected Methods for the Chemical Phosphorylation and Thiophosphorylation of Phenols
PublikacjaThis Focus Review gathers together a selection of methods for the chemical phosphorylation of phenols that employ three‐ and four‐coordinate phosphorus compounds. Phosphorylated scaffolds can exhibit enhanced properties compared to their non‐phosphorylated analogues, such as increased biological activity and increased/decreased solubility; as such, phosphorus compounds have gained more and more interest in organic and medicinal...
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Chemical, biological and functional aspects of food lipids
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Review of ionic liquids applications in chemical processes
PublikacjaCiecze jonowe stały się obiektem zainteresowania naukowców. Składają się one z dużego organicznego kationu i małego anionu. Modyfikacje kationu i anionu pozwalają na dostosowanie ich właściwości do aktualnych potrzeb. Rozpuszczają one szerokie spektrum związków organicznych i nieorganicznych związków. Mogą zatem z powodzeniem zastąpić dotychczas stosowane tradycyjne rozpuszczalniki. Znajdują zastosowanie jako medium reakcyjne,...
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Fluorescence Measurements for chemical optical sensor of cobalt
PublikacjaW pracy zaproponowano i opisano optoelektroniczny fluorescencyjny sensor do pomiaru stężenia kobaltu w wodzie.
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Mass spectrometry based identification of geometric isomers during metabolic stability study of a new cytotoxic sulfonamide derivatives supported by quantitative structure-retention relationships
PublikacjaA set of 15 new sulphonamide derivatives, presenting antitumor activity have been subjected to a metabolic stability study. The results showed that besides products of biotransformation, some additional peaks occurred in chromatograms. Tandem mass spectrometry revealed the same mass and fragmentation pathway, suggesting that geometric isomerization occurred. Thus, to support this hypothesis, quantitative structure-retention relationships...
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The influence of Be addition on the structure and thermal properties of alkali-silicate glasses
PublikacjaBe-Na-(Li)-Si oxide glasses containing up to 15 mol% of BeO were prepared. Their structure was characterized by X-ray powder diffraction and Raman as well as infrared spectroscopic techniques, while their chemical compositions were examined by Inductively Coupled Plasma Optical Emission Spectrometry. All materials were found to be amorphous and contain Al contaminations from minor dissolution of the alumina crucibles. The results...
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The study on application of biopolyols obtained by cellulose biomass liquefaction performed with crude glycerol for the synthesis of rigid polyurethane foams
PublikacjaIn this work rigid polyurethane foams (PUR) were obtained by replacement of 0–70 wt% of petrochemical polyol with bio-polyol obtained via cellulose liquefaction in presence of crude glycerol. The foams with different content of a bio-polyol were prepared by single step method for NCO/OH ratio equals 1.5. The prepared materials were analyzed in terms of their morphology, chemical structure, thermal stability and basic physical and...
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Comprehensive Investigation of Stoichiometry–Structure–Performance Relationships in Flexible Polyurethane Foams
PublikacjaPolyurethane (PU) foams are versatile materials with a broad application range. Their performance is driven by the stoichiometry of polymerization reaction, which has been investigated in several works. However, the analysis was often limited only to selected properties and compared samples differing in apparent density, significantly influencing their performance. In the bigger picture, there is still a lack of comprehensive studies...
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Novel bio-based thermoplastic poly(ether-urethane)s. Correlations between the structure, processing and properties
PublikacjaThe main purpose of this work was to analyze the effect of the number of unreacted isocyanate groups and the [NCO]/[OH] molar ratio during the chain extension of a prepolymer during the polymerization process on the structure, processing and selected properties of thermoplastic poly(ether-urethane)s. Three series of novel thermoplastic polyurethanes were obtained via a prepolymer route. Three prepolymers were synthesized from diisocyanate...
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Poly(ε-Caprolactone)/Brewers’ Spent Grain Composites—The Impact of Filler Treatment on the Mechanical Performance
PublikacjaWaste lignocellulose materials, such as brewers’ spent grain, can be considered very promising sources of fillers for the manufacturing of natural fiber composites. Nevertheless, due to the chemical structure differences between polymer matrices and brewers’ spent grain, filler treatment should be included. The presented work aimed to investigate the impact of fillers’ reactive extrusion on the chemical structure and the poly(ε-caprolactone)/brewers’...
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Direct human contact with siloxanes (silicones): safety or risk. Part 1: characteristics of siloxanes (silicones
PublikacjaSiloxanes are commonly known as silicones. They belong to the organosiliconcompounds and are exclusively obtained by synthesis. Their chemical structuredetermines a range of physicochemical properties which were recognized as unique.Due to the susceptibility to chemical modifications, ability to create short, long orcomplex polymer particles, siloxanes found an application in many areas of human life.
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Eco-Friendly Ether and Ester-Urethane Prepolymer: Structure, Processing and Properties
PublikacjaThis study concerns bio-based urethane prepolymers. The relationship between the chemical structure and the thermal and processing parameters of bio-based isocyanate-terminated ether and ester-urethane prepolymers was investigated. Bio-based prepolymers were obtained with the use of bio-monomers such as bio-based diisocyanate, bio-based polyether polyol or polyester polyols. In addition to their composition, the bio-based prepolymers...
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Chemical and Mechanical Properties of 70-Year-Old Concrete
PublikacjaThe aim of this research is to determine the durability and strength of concrete continuous footing based on the chosen mechanical, physical, and chemical properties of the concrete. The presented investigations constitute some opinions from experts on the bearing capacity of concrete continuous footing and the possibilities of carrying additional loads and extended working life. The cylindrical specimens were taken from continuous...
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The Influence of Waste Expanded Perlite on Chemical Durability of Mortars
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Chemical Composition and Antimicrobial Activity of New Honey Varietals
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Ionization of tocopherols and tocotrienols in atmospheric pressure chemical ionization
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Chemical composition of water from roof in Gdańsk, Poland
PublikacjaThis study deals with the assessment of roof runoff waters from the region of Gdansk collected during the winter season (2007/2008). The chemical analysis includes 16 chemical variables: major ions, PAHs and PCBs measured at 3 sampling sites for 6-14 rain events. Although the data set is of limited volume the statistical data treatment using self-organizing maps (SOM) reveals the main factors controlling roof runoff water quality...
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New materials and technologies used in chemical equipment design
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Mechanical properties of dissimilar welded joints for chemical tankers
PublikacjaArtykuł przedstawia właściwości mechaniczne złączy różnoimiennych stali typu duplex oraz austenitycznej typu 316L otrzymanych za pomocą spawania automatycznego łukiem krytym. Wykazano możliwość wykorzystania wysokowydajnej metody SAW w miejsce dotychczas stosowanych metod GTAW i GMAW do spawania blach zbiorników statków do przewozu chemikaliów. Pomimo obawy uzyskania nieodpowiednich struktur złączy okazało się, że spawanie stali...
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Chemical instability of the cobalt oxyhydrate superconductor under ambientconditions.
PublikacjaPrzedstawiono badania dyfrakcyjne i termograwimetryczne uwodnionego, sodowo-kobaltowego tlenku nadprzewodzącego: NaxCoO2 yH2O (y=1.4). Materiał ten jest niestabilny już w temperaturze pokojowej i przechodzi w nowo odkrytą fazę = 0.6.
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Quantum chemical modeling of electrochromism of tungsten oxide films
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Toxicity and chemical analyses of airport runoff waters in Poland
PublikacjaThe aim of this study was to assess the ecotoxicological effects of various compounds in complex airport effluents using a chemical and ecotoxicological integrated strategy. The present work deals with the determination of sum of PCBs, PAHs, pesticides, cations, anions, phenols, anionic, cationic, non-ionic detergents, formaldehyde and metals – as well as TOC and conductivity – in runoff water samples collected from 2009 to 2011...
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Functionalization of Parylene During Its Chemical Vapor Deposition
PublikacjaTwo possible mechanisms for the reaction of four halogenated (metha)acrylate-based molecules with Parylene [poly (paraxylylene)] during its chemical vapor deposition were proposed. The chemical reactivity of acrylate double bond with the paraxylylene biradical was calculated for all four (metha)acrylate-based molecules. These calculations allowed the evaluation of the energetically favorable mechanism and indeed a direct correlation...
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Chemical reactivity and antimicrobial activity of N-substituted maleimides
PublikacjaZsyntezowano kilkanaście N-podstawionych maleimidów, zawierających w swojej strukturze podstawniki o różnej wielkości i polarności.Maleimidy o charakterze obojętnym wykazywały silny efekt przeciwgrzybowy; ich aktywność przeciwbakteryjna była zróżnicowana. Niską aktywność przeciwbakteryjną, ale wysoką aktywność cytostatyczną stwierdzono dla maleimidów o charakterze zasadowym. Reaktywność chemiczna i lipofilowość miały wpływ na aktywność...
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Chemical denudation and the role of sulfide oxidation at Werenskioldbreen, Svalbard
PublikacjaThis study aims to determine the rate of chemical denudation and the relationships between dominant geochemical reactions operating in the proglacial and subglacial environments of the polythermal glacier Werenskioldbreen (SW Svalbard) during an entire ablation season. Water sampling for major ion chemistry was performed at a proglacial hydrometric station and from subglacial outflows from May to September 2011. These data were...
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Polymerization of chloro-p-xylylenes, quantum-chemical study
PublikacjaThe p-xylylene monomers of parylene N, C and D have similar high polymerization reactivity. For effective copolymerization processes this fact is basically a draw- back and for instance the copolymerization with styrene doesn't go at all (Corley et al. J Pol Sc 13(68):137156, 1954). Substitution of terminal hydrogen atoms by chlorine atoms reduces reactivity dramatically. 7,7,8,8-tetrachloro-p- xylylene and 2,5,7,7,8,8-hexachloro-p-xylylene...
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Mobile chromatographs and spectrometers for the analysis of chemical warfare agents
PublikacjaThis article describes the technological state of readiness regarding mobile chromatographs and spectrometers and their appiicability for the analysis of chemical warfare agents (CWAs), degradation products, simulants, and precursors.
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Diamine derivatives of dimerized fatty acids and bio-based polyether polyol as sustainable platforms for the synthesis of non-isocyanate polyurethanes
PublikacjaA 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...
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Tailoring structural properties of lanthanum orthoniobates through an isovalent substitution on the Nb-site
PublikacjaTetragonal polymorph of lanthanum orthoniobate can be stabilized to room temperature by the substitution of Nb with an isovalent element. LaNb1-xAsxO4 (0 < x ≤ 0.3), where As is an element stabilizing tetragonal structure, were successfully synthesized with combined co-precipitation and solid-state reaction method. The phase transition temperature, above which the material has tetragonal structure, decreases linearly with increasing...
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Effect of Individual Components of Lignocellulosic Biomass on Methane Production and Methanogen Community Structure
PublikacjaOne of the major factors that influences the economic feasibility of biogas production is the availability of digestible feedstocks. There is little research on the influence of the chemical composition of biomass on biogas synthesis, especially with regard to the content of lignocellulosic materials. Therefore, the aim of this study was to estimate how differences in the content of cellulose and lignin in lignocellulosic biomass...
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Photocatalytic degradation and pollutant-oriented structure-activity analysis of carbamazepine, ibuprofen and acetaminophen over faceted TiO2
PublikacjaPhotocatalytic degradation of carbamazepine, ibuprofen, acetaminophen and phenol was studied in the presence of anatase photocatalyst, exposing three different crystal facets in the majority of {0 0 1}, {1 0 0} or {1 0 1}. It was found that octahedral anatase particles exposing {1 0 1} facets allow to achieve the best degradation and mineralization of all persistent organic pollutants. This confirms that the previous findings,...
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Chemistry and Nanochemistry 2022.
Kursy OnlineThe course consists of lectures (15 x 2 hours) and laboratories (5 x 3 hours).The goal of this course is to teach general chemistry and adequately apply it to nano-size systems, their synthesis and analysis. An emphasis is laid on an analysis of electronic structure of molecules and prediction of resulting properties and reasons of consequent behaviour in chemical reactions. The course also encloses laboratory classes, where the...
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Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ
PublikacjaBa1−xGd1−yLax+yCo2O6−δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is...
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Seasonal variability and morphological structure of bacteria in the Admiralty Bay (King George Island, Antarctic).
PublikacjaIntroduction: The aim of investigations was to state whether melting glaciers cause mass mortality of the sea stenohalyne organisms, what in consequence can lead to an increase of accumulation and growth of psychrophilic bacteria. It may be also that fresh melting water is unfavourable to the sea bacteria and front glacier's regions are not the areas of their intensive development. Methods: Field investigations were done in Admiralty...
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Structure, morphology and mechanical behaviour of novel bio-based polyurethane composites with microcrystalline cellulose
PublikacjaThe aim of this work was to obtain bio-based polyurethane composites using biocomponents such as, bio-glycol, modified natural oil-based polyol, and microcrystalline cellulose (MCC). The prepolymer method was used to prepare the bio-based polyurethane matrix. Prepolymer synthesised from 4,4’-diphenylmethane diisocyanate (MDI) and a polyol mixture containing 75% wt. commercial polyether and 25% wt. hydroxylated soybean oils (H3)...
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Effect of hydroxylated soybean oil and bio-based propanediol on the structure and thermal properties of synthesized bio-polyurethanes
PublikacjaThe aim of this work was to obtain bio-polyurethanes using synthetic compounds and bio-components, i.e. bio-glycols. Bio-polyurethanes were prepared by means of the prepolymer method. Prepolymers were synthesized from 4,4′-diphenylmethane diisocyanate (MDI) and a polyol mixture containing 75% by weight of commercial polyether and 25% by weight of hydroxylated soybean oils (H2 or H3), the latter being obtained in the reaction with...
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Insights into the Thermo-Mechanical Treatment of Brewers’ Spent Grain as a Potential Filler for Polymer Composites
PublikacjaThis paper investigated the impact of twin-screw extrusion parameters on the properties of brewers’ spent grain. The chemical structure, antioxidant activity, particle size, and color properties, as well as the emission of volatile organic compounds during extrusion, were investigated. The main compounds detected in the air during modifications were terpenes and terpenoids, such as α-pinene, camphene, 3-carene, limonene, or terpinene....
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SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF NIOBIUM-DOPED HYDROXYAPATITE CERAMICS
PublikacjaHydroxyapatite (HAp) ceramic materials are considered as one of the most promising implant materials in bone surgery and in dentistry. They exhibit unique biocompatibility, bioactivity, and osteoconductivity, which are the most desirable biomaterial features. However, HAp itself is brittle, has low strength, high degree of crystallinity and low solubility at physiological pH. Doping synthetic HAp with metal ions plays an important...
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Thermal and Chemical Expansion in Proton Ceramic Electrolytes and Compatible Electrodes
PublikacjaThis review paper focuses on the phenomenon of thermochemical expansion of two specific categories of conducting ceramics: Proton Conducting Ceramics (PCC) and Mixed Ionic-Electronic Conductors (MIEC). The theory of thermal expansion of ceramics is underlined from microscopic to macroscopic points of view while the chemical expansion is explained based on crystallography and defect chemistry. Modelling methods are used to predict...
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State of the art and prospects of methods for determination of lipophilicity of chemical compounds
PublikacjaLipophilicity of the compounds is useful to (i) explain their distribution in biological systems, which is different in plant and in animal organisms, (ii) predict the possible pathways of pollutant transport in the environment, and (iii) support drug discovery process and select optimal composition in terms of bioactivity and bioavailability. The lipophilic properties can be determined by two main approaches, experimental, which...
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The speciation and physico-chemical forms of metals in surface waters and sediments
PublikacjaWody powierzchniowe mogą być zanieczyszczone przez metale występujące w różnych formach fizykochemicznych przez metale w postaci jonowej jak i również metale związane z materia zawieszoną. Substancje nierozpuszczone występujące w postaci koloidów lub w postaci zaabsorbowanej na powierzchni materii zawieszonej mogą ulegać procesowi rozpuszczania w odpowiedzi na zamianę warunków chemicznych i fizycznych środowiska wodnego.Również...
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Fog water chemical composition in different geographic regions of Poland
PublikacjaPróbki wody z mgły były pobierane za pomocą pasywnych i aktywnych próbników na trzech stacjach pobierania próbek. Miejsca pobierania próbek usutuowane były w różnych regionach geograficznych Polski. Analizowano następujące parametry: przewodność, pH, wybrane kationy i aniony. Uzyskane wyniki mogą stanowić wartościową informacje na temat chemizmu atmosfery.Statystyczna analiza wyników wskazuje na znaczne różnice w wartościach otrzymanych...
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Functional properties of packaging materials from chemical modified stach.
PublikacjaThis work is focused on study of the mechanical and barrier properties of films obtained from potato starch modified with sodium tetrahydroxozincate generated in situ. The results show that the chemical modification of starch improved the water vapor permeability by about 25%, unfortunately decreased the elongation at break by 60%, when compared with unmodified starch films. However, placitization of films with glycerol at a concentration...
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Application of Discrete Wavelet Transform in the Analysis of Nonlinear Chemical System
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Clinoptilolite as a natural, active zeolite catalyst for the chemical transformations of geraniol
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Law requirements of explosion proof protection at working with chemical substances
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The relationship of potato tubers chemical composition with selected physiological indicators
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Chemical Composition of Industrial Wood Waste and the Possibility of its Management
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Variability of physico-chemical parameters in precipitation in Poland (1996-1999)
PublikacjaW publikacji przedstawiono wyniki badań przeprowadzonych w latach 1996-1999, dotyczących analizy próbek osadów atmosferycznych zebranych w trzech miejscach pobierania próbek. Zostały one porównane z wynikami otrzymanymi w pięciu innych miejscach na terenie Polski, rozmieszczonych zarówno na terenach objętych ochroną, takich jak parki narodowe, jak również narażonych na silny wpływ zanieczyszczeń pochodzących z aglomeracji miejskich...