Filtry
wszystkich: 1129
wybranych: 1025
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: CHEMICAL STRUCTURE
-
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...
-
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...
-
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’...
-
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...
-
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.
-
Quantum chemical modeling of electrochromism of tungsten oxide films
Publikacja -
Ionization of tocopherols and tocotrienols in atmospheric pressure chemical ionization
Publikacja -
New materials and technologies used in chemical equipment design
Publikacja -
Chemical Hand Warmers in Protective Gloves: Design and Usage
Publikacja -
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...
-
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...
-
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...
-
The Influence of Waste Expanded Perlite on Chemical Durability of Mortars
Publikacja -
Chemical Composition and Antimicrobial Activity of New Honey Varietals
Publikacja -
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.
-
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...
-
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...
-
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...
-
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...
-
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.
-
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...
-
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...
-
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...
-
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...
-
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,...
-
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...
-
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)...
-
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...
-
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...
-
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....
-
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...
-
Chemical instability of the cobalt oxyhydrate superconductor under ambient conditions
Publikacja -
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...
-
On the sensitivity, selectivity, sensory information and optimalsize of resistive chemical sensors
PublikacjaWykorzystano pojęcia teorii informacji do określenia możliwości poprawy selektywności i czujności rezystancyjnych sensorów gazu. Podano ogólne rozważania dotyczące limitu selektywnoœci dla tych sensorów. Porównano iloraz sygnału do szumów oraz pojemność kanału informacyjnego dla sensorów chemicznych wykorzystujących jako sygnał zjawiska fluktuacyjne z klasycznymi sensorami charakteryzowanymi jedną wartością. Ogólne rozważania wsparto...
-
Chemical order and crystallographic texture of FePd:Cu thin alloy films
Publikacja -
Quantum chemical modelling of the process of lithium insertion into WO3 films
Publikacja -
Characterization of the natural chemical and osmotic environment of early wheat embryogenesis
Publikacja -
Health Benefits and Chemical Composition of Matcha Green Tea: A Review
Publikacja -
Effect of Genetically Modified Feeds on Physico-Chemical Properties of Pork
Publikacja -
Application of Discrete Wavelet Transform in the Analysis of Nonlinear Chemical System
Publikacja -
Chemical and Genetic Diversity of Nodularia spumigena from the Baltic Sea
Publikacja -
Physical, Chemical and Mechanical Properties of Novel Poly(Urethaneamideimide)s
Publikacja -
Clinoptilolite as a natural, active zeolite catalyst for the chemical transformations of geraniol
Publikacja -
Fog water chemical composition in different geographic regions of Poland
PublikacjaPróbki wody z mgły pobierane były w latach 2005-2006 na terenie Szrenicy, Zakopanego i Borucina. Analiza statystyczna ujawniła znaczące różnice w składzie chemicznym próbek wody z mgły w zależności od regionu geograficznego, wysokości pobierania próbek, ale także od momentu pobierania próbki. Stwierdzono również różnice składu chemicznego pomiędzy mgłą radiacyjna a orograficzną.
-
The origin of luminescence accompanying electrochemical reduction or chemical decomposition of peroxydisulfates
Publikacja -
Chemical Composition of Industrial Wood Waste and the Possibility of its Management
Publikacja -
Chemical Theory of Machines, basic principles of strength with examples of calculations
PublikacjaThis book encompasses the essential range of information on technical aspects of mechanical design. It was written primarily for the students and staff of chemistry faculties of technical universities, yet it may also be utilized by everyone, who ether would like to try or already enjoys designing, but cannot take advantage of typical stress & machine construction handbooks. These handbooks often require familiarity with the concepts...
-
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...
-
Chemical characteristics of new nanopowder of titania doped with nitrogen atoms
PublikacjaW pracy zaprezentowano charakterystykę domieszkowanego azotem ditlenku tytanu otrzymanego na drodze jednoetapowej syntezy z kompleksu tytanu (IV) z ligandami zawierającymi atomy azotu. ikrostruktura i morfologia nowego materiału została określony za pomocą badań XRD, AFM, UV-VIS i FT-IR. Raport przedstawia również badania elektrochemiczne, które pozowliły na wyznaczenie potencjału pasma płaskiego na podstawie wykresu Mott
-
Law requirements of explosion proof protection at working with chemical substances
Publikacja