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    Wyświetlanie 1-13 z 13
    Tytuł:
    Effect of Technological Parameters on the Quality and Dimensional Accuracy of Castings Manufactured by Patternless Process Technology
    Wpływ technologiczny parametrów na jakość i dokładność wymiarową odlewów produkowanych bezmodelowo
    Autorzy:
    Krivoš, E.
    Pastirčák, R.
    Madaj, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/356923.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    silica sand
    patternless process
    cutting parameters
    gypsum
    piasek kwarcowy
    technologia bezmodelowa
    parametry skrawania
    gips
    Opis:
    Submitted article deals with the effect of selected technological parameters on the quality and dimensional accuracy of prototype castings made by Patternless process technology. During experiments were used two types of molding compounds (foamed gypsum and compound based on silica sand and resin). Experiments were focused on optimization of cutting parameters in terms of efficiency, accuracy and possibilities to minimize tool wear. Article deals also with the dimensional and shape accuracy of the castings made by Z-Cast technology. The main aim of the research is to optimize Patternless process technology to such an extent, that achieved dimensional and shape accuracy will be comparable to castings made by the Z-Cast technology.
    Artykuł dotyczy wybranych parametrów technologicznych, które wpływają na jakość i dokładność wymiarową odlewów prototypowych wykonanych technologią bezmodelową. Podczas eksperymentów wykorzystano dwa rodzaje form (spienionego gipsu i mas do formowania na bazie piasku kwarcowego i żywicy). Badania maja na celu optymalizacje parametrów cięcia w zakresie wydajności, dokładności i zminimalizowania zużycia narzędzi. Artykuł zajmuje sie również dokładnością wymiarów i kształtem odlewów wytwarzanych za pomocaąZ-cast. Głównym celem tego badania jest bezmodelowa technika optymalizacji tworzenia do takiego stopnia, aby osiągnąć dokładność wymiarów i kształtu odlewu wytworzonego z pomocą Z-cast.
    Źródło:
    Archives of Metallurgy and Materials; 2014, 59, 3; 1069-1072
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Plant biomass degradation supported by non-enzymatic proteins
    Autorzy:
    Madaj, R.
    Kalinowska, H.
    Sobiecka, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/410486.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej
    Tematy:
    cellulose
    enzymatic hydrolysis
    swollenins
    expansins
    loosenins
    celuloza
    hydroliza enzymatyczna
    swoleniny
    ekpansyny
    Opis:
    Lignocellulosic biomass, rich in potential carbon sources and value added products, has been intensively investigated in scope of its costefficient and effective decomposition. Many methods were developed, physicochemical or biological. Nevertheless, they are either expensive, inefficient or pose threat to the environment. Recently discovered proteins, lacking any hydrolytic activity, can be a key to solve problems associated with a slow process of enzymatical, eco-friendly degradation. These proteins belong to three related groups – swollenins, expansins and loosenins. Using different molecular mechanisms, they disrupt hydrogen bonds within cellulose chains, enabling enzymes to perform hydrolysis leading to decomposition of lignocellulosic complex.
    Źródło:
    Biotechnology and Food Science; 2017, 81, 1; 71-81
    2084-0136
    2299-6818
    Pojawia się w:
    Biotechnology and Food Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nitroaromatic enzymatic biodegradation system in Phanerochaete chrysosporium
    Autorzy:
    Madaj, R.
    Kalinowska, H.
    Sobiecka, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/410513.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej
    Tematy:
    applied biochemistry
    biochemical engineering
    biotechnology
    biotransformation
    denitrification
    detoxification
    biochemia stosowana
    inżynieria biochemiczna
    biotechnologia
    biotransformacja
    denitryfikacja
    detoksykacja
    Opis:
    Phanerochaete chrysosporium is an ubiquitous fungus having huge potential for application in biodegradation processes. Its enzymatic system, consisting of ligninases, membrane-associated oxidases and hydrogen peroxide generating enzymes is capable of degrading a wide range of pollutants like 2,4,6-trinitrotoluene, 2,5-dinitrophenol, 3,5-dinitrosalicylic acid or azodyes produced by military or civilian industry. Synergetic action between enzymes, based on providing substrates essential for their activity and their extreme low-specificity guarantees successful degradation of recalcitrant pollutants. Nevertheless, a development of a technique, taking into the account the type of pollutant, its concentration in the environment, its metabolic pathway and maintenance of the system is required. This paper presents a literature survey related to enzymatic system of a white rot fungus Phanerochaete chrysosporium and its potential application in biodegradation processes.
    Źródło:
    Biotechnology and Food Science; 2018, 82, 2; 113-128
    2084-0136
    2299-6818
    Pojawia się w:
    Biotechnology and Food Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badanie oddziaływania wankomycyny z fragmentem peptydoglikanu ściany komórkowej bakterii
    Study on interaction of vancomycin with bacterial cell wall peptidoglycan
    Autorzy:
    Samaszko-Fiertek, J.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172720.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    wankomycyna
    wysokosprawna chromatografia cieczowa
    HPLC
    elektroforeza kapilarna
    magnetyczny rezonans jądrowy
    NMR
    SAMs
    vancomycin
    high performance liquid chromatography
    capillary electrophoresis
    nuclear magnetic resonance (NMR)
    self-assembled monolayers
    Opis:
    Unfortunately, despite of work involved in understanding of the mechanism of bacterial virulence, especially Staphylococcus aureus, it has not been developed effective therapy against this bacteria. The first antibiotic used against this bacteria was penicillin, which was discovered by Alexander Fleming in 1928. A new generation of drugs introduced into therapy against Staphylococcus aureus and other Gram-positive bacteria are glycopeptide antibiotics. The most widespread and most commonly used are vancomycin and teicoplanin, discovered respectively in 1956 and 1978. As a result of frequent use of vancomycin VISA (ang. Vancomycin-intermediate Staphylococcus aureus) and VRSA (ang. Vancomycin-resistant Staphylococcus aureus) strains were discovered. The mechanism of action of this antibiotic based on the inhibition of the biosynthesis of bacterial cell wall peptidoglycan fragment. Forming stabilized by hydrogen bonds complex with terminal fragment of peptidoglycan (dipeptide d-Ala-d-Ala) vancomycin prevents its further crosslinking [2] (Fig. 1). However, in recent years other theories of the mechanism of action of glycopeptide antibiotics against Gram-positive bacteria were presented it seems to be crucial to find methods of selection of new antibiotics and for this purpose standard techniques of the analysis, including isothermal titration calorimetry (ITC) [3], nuclear magnetic resonance spectroscopy (NMR) [8–15], high performance liquid chromatography (HPLC) [16], capillary electrophoresis [17] or self-assembled monolayers (SAMs) [22] are used. Discovering new methods for studying of interaction between vancomycin and Gram-positive bacterial cell wall allows use it as a new technique for rapid selection of potential new antibiotics, including glycopeptide derivatives.
    Źródło:
    Wiadomości Chemiczne; 2015, 69, 7-8; 491-511
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Changes in alpha-amylases activity in wheat and malted wheat grain after long storage
    Ocena zmian aktywności alfa-amylaz w pszenicy i jej słodach po długotrwałym okresie przechowywania
    Autorzy:
    Warchalewski, J.R.
    Klockiewicz-Kamińska, E.
    Madaj, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398377.pdf
    Data publikacji:
    1985
    Wydawca:
    Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
    Tematy:
    wheat
    stored wheat
    malted wheat grain
    amylolytic activity
    Opis:
    The effect of prolonged storage on α-amylases activity in wheat and malted wheat grain was studied. It was demonstrated that four-year storage increases the activity of α-amylases and at the same time decreases the total activity of combined α- and β-amylases and the protein level.
    Badano wpływ długotrwałego czasu przechowywania na aktywność amylolityczną w ziarnie pszenicy i jej słodach. Do badań użyto ziarno pszenicy ozimej odmiany ARIA oraz jej słody: 4-dniowy z dodatkiem kwasu giberelinowego (GA3) i 6-dniowy bez GA₃. W ekstraktach z ziarniaków pszenicy i jej słodów oznaczono zawartość białka, łączną aktywność α i β-amylaz oraz aktywność α-amylaz, a także liczbę opadania. Wszystkie analizy wykonano 3 miesiące po zbiorze pszenicy i po 4 latach przechowywania ziarna. Stwierdzono, że 4-letni okres przechowywania ziarna w kontrolowanych warunkach wpływa na wzrost aktywności α-amylaz, jednocześnie obniżając łączną aktywność α i β-amylaz oraz poziom białka.
    Źródło:
    Acta Alimentaria Polonica; 1985, 11, 4; 379-384
    0137-1495
    Pojawia się w:
    Acta Alimentaria Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    D-Rybono-1,4-lakton. Część 2, Wykorzystanie w syntezie organicznej – wybrane reakcje
    D-Ribono-1,4-lactone. Part 2, Use in organic synthesis – selected reactions
    Autorzy:
    Madaj, J.
    Samaszko-Fiertek, J.
    Ślusarz, R.
    Dmochowska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/171521.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    D-Rybono-1,4-lakton
    C-glikozydy
    analogi nukleozydów
    neplanocyna
    D-ribono-1,4-lactone
    C-glycosides
    nucleosides analogs
    neplanocin
    Opis:
    There are many examples of syntheses with d-ribono-1,4-lactone as a substrate. Among all, its biggest advantage is undoubtedly its accessibility. It can be synthesized on a large scale from naturally available raw materials. Its characteristic feature is the stable configuration of individual carbon atoms in multiple reaction conditions. Very important is the presence of a carbonyl moiety, allowing for a variety of additions which is crucial for carbon-carbon bond formation, the most difficult synthesis in organic chemistry. In this article we present selected examples of articles that were published after 1984. In this year, the second article describing the Use of d-Ribonolactone in Organic Synthesis [36] was published. After this time many articles describing the use of the entitled lactone as a substrate in organic synthesis were published. We thought it would be worthwhile to present in Polish a selection of them. C-Glycosides and nucleoside analogs are a particularly important type of synthesized products. Examples of their synthesis are presented in this work, namely, neplanocin A [5], B [31] and F [24], citreovirdin [14], 2-bromopyridin α- and β-d-ribofuranosides [10], 4-deazaformicin A [27] and varitriol [ 33].
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 11-12; 861-885
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wybrane antybiotyki nukleozydowe
    Selected nucleoside antibiotics
    Autorzy:
    Samaszko-Fiertek, J.
    Dmochowska, B.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/171562.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    antybiotyki nukleozydowe
    tunikamycyna
    mureidomycyna
    muramycyna
    kapuramycyna
    nucleoside antibiotics
    tunicamycin
    mureidomycin
    muramycin
    capuramycin
    Opis:
    Every year there has been a growing increase in infections caused by strains of bacteria resistant to multiple drugs. This prompts scientists to search for new antibiotics that would be able to fight these infections. New therapeutics used in medicine, which offer greater hopes are nucleoside antibiotics. They represent a large family of natural compounds exhibiting a variety of biological functions [1]. These include antifungal, antiviral, antibacterial, insecticides, immunosuppressants or anticancer properties. These broad-spectrum antibiotics can be divided into three main groups: • antibacterial nucleoside antibiotics, responsible for the inhibition of bacterial translocation of phospho-N-acetylpentapeptides, involved in the biosynthesis of peptidoglycan cell wall of bacteria; • antifungal nucleoside antibiotics, which role is to inhibit chitin synthase, or stopping construction of the cell wall of fungi; • antiviral antibiotics nucleoside, their mechanism of action is mainly based on blocking the biosynthesis of proteins by peptide inhibition transferase. In recent years much attention has been focused on the construction, mechanism of action and biosynthesis of antibiotics [1–3]. The development of genetic engineering has opened the way for combinatorial biosynthesis and obtaining new or hybrid compounds. In this work we would like to discuss some of bioactive naturally occurring nucleoside antibiotics, such as tunicamycin (Fig. 6) [19–22], mureidomycin (Fig. 8) [31–34], muramycin (Fig. 9) [36] or capuramycin (Fig. 10) [38].
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 1-2; 15-32
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    D-Rybono-1,4-lakton. Część 1, Otrzymywanie i wybrane pochodne
    D-Ribono-1,4-lactone. Part 1, Preparation and seleced derivatives
    Autorzy:
    Madaj, J.
    Samaszko-Fiertek, J.
    Ślusarz, R.
    Dmochowska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/171744.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    D-Rybono-1,4-lakton
    otrzymywanie
    wybrane pochodne
    D-Ribono-1,4-lactone
    preparation
    seleced derivatives
    Opis:
    Sugars are extremely important chiral substrates in organic synthesis. Thanks to the possibility of obtaining them from natural sources, their prices are relatively low which increases their attractiveness. d-Ribono-1,4-lactone is included in these compounds. For years it has enjoyed great interest as a substrate. In the early 1980’s two review articles were published in reputable journals [4, 5]. It has been a long time since these articles were published so we have decided to prepare a more up- -to-date review article in Polish. d-Ribono-1,4-lactone can be synthesized in many ways. The most interesting way seems to be the oxidation with KMnO4 [9] or molecular Br2 [10]. The use of bromine may appear to be harmful to the environment. That is why the search for more environmentally friendly methods is ongoing. However, the new methods are not as sufficiently satisfactory and often more expensive than the conventional, previously named methods. Therefore, the most commonly used method is the oxidation of D-ribose with molecular bromine. Very important derivatives of d-ribonolactone are acetal derivatives: 2,3-O-isopropylidene [10, 16] and 3,4-O-benzylidene derivatives [17]. They are often the starting materials for further synthesis. In the case of the latter compound the proper structure was determined by crystallography many years after its synthesis [18]. Very important group of derivatives are derivatives modificated at C-5: sulphonic [21], fluorine [22], chlorine [23], bromine [16, 24], azide [25] and phosphate [27]. Especially important are 5-bromo-5-deoxy derivatives. Examples of their use for the synthesis of thioalditols and thiosugars are described in the literature. It is also worth mentioning the possibility of synthesis of 1,2-unsaturated [28–30] and 2,3-unsaturated [31] derivatives. Presented examples of derivatives prove that using a d-ribono-1,4-lactone a whole range of derivatives extremely useful for further synthesis of more complex compounds can be obtained.
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 11-12; 844-859
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cukrowe czwartorzędowe sole amoniowe
    Sugar quaternary ammonium salts
    Autorzy:
    Dmochowska, B.
    Sikora, K.
    Samaszko-Fiertek, J.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172328.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    czwartorzędowe sole amoniowe
    d-glikopiranozydy
    celuloza
    chitozan
    quaternary ammonium salts
    d-glicopyranosides
    cellulose
    chitosan
    Opis:
    Quaternary ammonium compounds (QACs) exhibit the properties of both inorganic and organic compounds, and their ionic nature gives them hydrophilic character. The popularity of these compounds is allied to their many applications and ease of synthesis. Most of QACs are stable up to 150°C, readily soluble in water, usually non-toxic in utilitarian concentrations, are surface active, and do not irritate the skin or have a noxious odour [1]. Many of them have fungicidal, bactericidal and algicidal properties [2–5]. The antiviral action of QACs, including against HIV [6, 7], has been reported. They are used as timber preservatives, disinfectants, fabric softeners, anti-electrostatic agents and antifriction substances [5, 8, 9]. In addition, certain drugs administered in cases of diabetes, cardiac arrhythmia, neuroses, allergies and even carcinomas are QACs. Finally, QACs are used in chemical synthesis as catalysts, in phase-boundary catalysis [11], in the reduction of aldehydes and alkenes, and in the Friedl-Crafts reaction. In literature there is only limited amount of information considering quaternary ammonium salts containing sugar substituents. Among them four group of compounds arises: salts linked to C6 atom in sugar, directly connected to anomeric carbon atom, linked trough hydrocarbon spacer and derivatives of polisacharides. Kirk at al. described the synthesis of biologically active QACs [15]. In the Menshutkin reaction between an iodo-derivative and trimethylamine (Scheme 4), these authors obtained compounds with bactericidal and fungicidal properties. The authors obtained a series of analogous compounds using carboxylic acids (with carbon chains of various lengths) ester linked to the C-6-OH group of a sugar derivative. Blizzard synthesized QAC derivatives of vancomycin [28]. It was noticed that the increased hydrophilicity of vancomycin following the addition to it of a suitable fragment enhanced its antibacterial properties [30, 31], one of the more active being a derivative containing an aminium group at position G-6 (Scheme 10). Examples of reactions, in which the terminal carbon atoms in methyl glucopyranosides and polysaccharides are functionalized, are the syntheses carried out by Engel et al. [33, 34], one of which is shown in Figure 5. These authors aimed to find compounds with antibacterial properties. In the first instance, the hydroxyl groups at atoms C-6 of the sugar units in cellulose were O-tosylated. Then, the terminal carbons were functionalized with tertiary amines, yielding QACs. The most effective bactericide among these compounds was the one with a 16-carbon chain, the structure of which is shown Figure 6.
    Źródło:
    Wiadomości Chemiczne; 2016, 70, 7-8; 497-518
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rutyna : budowa, właściwości
    Rutin : structure and properities
    Autorzy:
    Samaszko-Fiertek, J.
    Roguszczak, P.
    Dmochowska, B.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/171497.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    flawonoidy
    rutyna
    budowa
    właściwości antyoksydacyjne
    flavonoids
    rutin
    structure
    antioxidant properties
    Opis:
    Flavonoids commonly can be found in plants. They protect them against various microorganisms or insects [1]. Flavonoids demonstrate not only antioxidant properties, but also prevent the development of cancer [2]. This is attributed to their ability to induce apoptosis of tumor cells. The structure of this type of compound is based mainly on the flavone skeleton with the keto group in position 4 (Fig. 2). The difference in structure of flavonoids consists mainly in the number and nature of the substituents. Flavonoid compounds have a 15-carbon atoms skeleton, consisting of two aromatic rings (A and B) connected to 3 carbon atoms, by oxygen contained within the heterocyclic ring C (Fig. 2) [5]. Structural difference of the pyranose ring C and position of the phenyl ring B are the basis for the division flavonoids into seven groups (Fig. 3) [6]. In recent years a number of work focused on the study of flavonoids complexes with ions of copper(II) or iron(II) were published [20–22]. One of the most important flavonoids is rutoside, which has a number of important biological activities. One of the most important function of this compound is inhibition hyaluronidase activity by reducing the permeation and improveing the flexibility of blood vessels. It is used to treat diseases such as diabetic retinopathy, inflammation of the mucous membranes of the nose, atherosclerotic diseases or disorders of the venous circulation. Rutoside forms a relatively stable complex with ions of iron(II) or calcium(II) as well as nickel(II) and especially with copper(II). This type of complex protect from rapid degradation/oxidation of L-ascorbic acid [14, 15]. In 2011, Sak-Bosnar and colleagues proposed the structure of rutoside complex with ions of copper (II) (Fig. 9) [20]. In the same year was published work suggesting that a key role in this type of mechanism play hydroxyl group at the 3 ‚carbon atom, which becomes a „carrier” of the electron/radical (Fig. 5) [19].
    Źródło:
    Wiadomości Chemiczne; 2016, 70, 7-8; 435-453
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Egzopolisacharydy bakteryjne : budowa i funkcje
    Bacterial exopolysaccharides : structure and functions
    Autorzy:
    Samaszko-Fiertek, J.
    Kuźma, M.
    Dmochowska, B.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172244.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    egzopolisacharydy
    kwas hialuronowy
    celuloza bakteryjna
    dekstran
    żelan
    ksantan
    exopolysaccharides
    hyaluronic acid
    bacterial cellulose
    dextran
    gellan
    xanthan
    Opis:
    Exopolysaccharides fulfil protective functions and allow bacteria live in the communities, single or mixed, by facilitating adhesion to surfaces and to each other. Microbes prefer to exist in the form of a biofilm. The term biofilm was introduced in 1978 and is the group of microorganisms surrounded by extracellular, highly hydrated mucus, which allows adhesion on various surfaces and adhesion of cells to each other [1]. The extracellular slime owes its character mainly due to the presence of exopolysaccharides. Bacteria living in biofilms, have a high resistance to external factors, such as changes in temperature, pH, humidity, oxygenation, presence of bacteriocins, antibodies or antibiotics. They may be up to 1,000 times more resistant to antibiotics than planktonic forms. They can be synthesized inside and outside bacteria cell. The structure of the bacterial exopolysaccharide is very diverse, but very often, due to the presence of uronic acid residues, or non-sugar organic acids as pyruvic acid, succinic acid, as well as residues of inorganic acids such as phosphoric acid or sulfuric acid, they are negatively charged particles. In addition, a characteristic of most of the exopolysaccharides (EPS) is their enormous molecular mass of up to several million g/mol [11]. Thanks to its rheological properties, ease of isolation, and often biodegradable antioxidant activity extracellular polysaccharides are increasingly used in industry as a gelling agents, hardening and thickening agents, emulsifiers, food coatings and pharmaceutical products. In addition, they can be used as bandages, anti-cancer agents, cholesterol-lowering, antiulcer or immunomodulators [20–27]. This article discusses in details the selected exopolysaccharides such as xanthan, gellan, exopolysaccharides of lactic acid bacteria, dextran, bacterial cellulose, alginic acid, hyaluronic acid, mannans.
    Źródło:
    Wiadomości Chemiczne; 2016, 70, 7-8; 473-496
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Metody określania struktury polisacharydów
    Methods for determining polysaccharides structure
    Autorzy:
    Samaszko-Fiertek, J.
    Kuźma, M.
    Dmochowska, B.
    Ślusarz, R.
    Madaj, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172410.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    polisacharydy
    monosacharydy
    degradacja oksydacyjna
    analiza metylacyjna
    acetoliza
    NMR
    magnetyczny rezonans jądrowy
    MS
    polysaccharides
    monosaccharides
    oxidative degradation
    methylation analysis
    acetolysis
    nuclear magnetic resonance (NMR)
    Opis:
    Sequencing of polysaccharides is difficult to achieve because of the heterogeneous nature of the polysaccharide structure, high molecular weight (the size of a polysaccharide varies between approximately 16,000 and 16,000,000 daltons (Da)), and polydispersity of the polymer chains. The following information is essential to determine the primary structure of a polysaccharide: • monosaccharide composition: nature and molar ratios of the monosaccharide building blocks; • relative configuration of monosaccharides: d or l; • anomeric configuration: α- or β-configuration of the glycosidic linkage; • ring size: presence and distinction of furanosidic and pyranosidic rings; • linkage patterns: linkage positions between the monosugars and branches; • sequences of monosaccharide residues in the repeating units; • substitutions: position and nature of OH–modifications, such as O–phosphorylation, acetylation, O-sulfation, etc.; • molecular weight and molecular weight distribution. A polysaccharide extracted from plant materials or food products is usually purified before being subjected to structural analysis. The first step of characterizing a polysaccharide is the determination of its purity, which is reflected by its chemical composition, including total sugar content, level of uronic acids, proteins, ash, and moisture of the preparation. The second step is the determination of monosaccharide composition, which will unveil structural information such as the number of monosaccharides present in the polysaccharide and how many of each sugar unit. NMR spectroscopy has become the most powerful and noninvasive physicochemical technique for determining polysaccharide structures. It can provide detailed structural information of carbohydrates, including identification of monosaccharide composition, elucidation of α- or β-anomeric configurations, establishment of linkage patterns, and sequences of the sugar units in oligosaccharides and/or polysaccharides. Monosaccharide composition can be determined also by analysis of totally acid hydrolyzed polysacharide using high performance liquid chromatography (HPLC) or gas chromatography (GC). The ring size and glycosidic linkage positions of sugar units in a polysaccharide could be established by methylation analysis and/or cleavage reduction. The anomeric configuration is conventionally determined by oxidation, and this method can be combined with mass spectrometry to obtain more structural information.
    Źródło:
    Wiadomości Chemiczne; 2016, 70, 5-6; 299-318
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alditole i anhydroalditole
    Alditols and anhydroalditols
    Autorzy:
    Sikora, K.
    Samaszko-Fiertek, J.
    Ślusarz, R.
    Liberek, B.
    Madaj, J.
    Dmochowska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/171690.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    alditol
    anhydroalditol
    dianhydroalditol
    Opis:
    Alditols belong to the group of acyclic polyols. Formally, they are obtained from the aldose or ketose by reduction of the carbonyl group. Single or double dehydratation of alditols provides the cyclic compounds named anhydroalditols and dianhydroalditols, respectively. Alditols and anhydroalditols are widespread in both animal and plant kingdoms. They are in human blood and urine, and in the amniotic and cerebrospinal fluids. Herein the applications of alditols and anhydroalditols in medicine and human nutrition are presented. (For example d-mannitol is used as a diuretic agent or in osmotherapy to reduce acutely raised intracranial pressure; isosorbide mononitrate is used against angina pectoris. Xylitol (pentitol) can counteract several diseases, among others, the acute otitis media, osteoporosis, tooth decay and helps the remineralization of teeth, thanks to that it found use as an additive to chewing gum [4]. Most alditols including d-mannitol, d-glucitol and 1,4-anhydro-d,l-galactitol, are used as sweeteners and as well as additives for low caloric food or as diets for diabeties. Although they show lower sweetness than glucose or saccharose, their great advantage is that it does not cause a rapid increase of glucose level in blood [5,6]. While nitrates 1,4:3,6-dianhydro-d-mannitol and 1,4:3,6-dianhydro-d-glucitol thanks to the ability of blood vessels relaxant are commonly used for years in the treatment of heart diseases and blood system [10]). It is demonstrated that introduction of alditol or anhydroalditol to biologically active compound may improve its activity. Anhydroalditols are also useful substrates for the stereospecific synthesis of bicyclic compounds. Additionally, alditols and anhydroalditols are promising monomers for synthesis of polymers with interesting properties. Finally, methods of alditols and anhydroalditols syntheses are presented. Among them we consider: cyclization in an acid medium involving intramolecular dehydration, SN2 reaction with suitable leaving groups, deamination reaction combined with reduction, reduction of glycosyl halide, tioglycoside and glycoside, and addition of water or hydrogen to the double bond in glycals.
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 1-2; 65-86
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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