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Wyszukujesz frazę "covalent bond" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Study of conceptual knowledge and mode of reasoning relating to the characteristics of covalent bonds in future algerian physics teachers
Autorzy:
Hazzi, Salah
Djouahra, Idris
Dumon, Alain
Powiązania:
https://bibliotekanauki.pl/articles/2175228.pdf
Data publikacji:
2022
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
covalent bond
orbital overlap
bond stability
bond length
localised system
conjugated system
wiązania kowalencyjne
stabilność wiązania
długość wiązania
układ miejscowy
układy sprzężone
Opis:
In this study we tried to analyse how future teachers of Ecole Normale Supérieure (ENS) school who are at the end of education have integrated the specifications of covalent bonds in the different bond orders in terms of symmetry, stability, length, localisation (in the case of structures of ethane, ethylene and acetylene) or delocalisation of electrons (case of benzene). The analysis of responses to a written questionnaire shows that the majority of students have only integrated some knowledge, which may be termed as procedural, on the structural elements of molecules such as stability and the length of bonds. Although possessing some conceptual knowledge, students tend to use an alternative way of reasoning arising from the mental representation that single and multiple bonds are independent entities: the single bond is a ”σ bond” while the double bond is considered only as a ”π bond”.
Źródło:
Chemistry-Didactics-Ecology-Metrology; 2022, 27, 1-2; 105--121
2084-4506
Pojawia się w:
Chemistry-Didactics-Ecology-Metrology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemiczne aspekty celowanej terapii przeciwnowotworowej I. Kowalencyjne połączenia ligand-nośnik
Chemical as pects of targeted anticancer therapy I. Covalent bond of ligand to carier
Autorzy:
Werengowska, K. M.
Wiśniewski, M.
Terzyk, A.P.
Gurtowska, N.
Drewa, T. A.
Powiązania:
https://bibliotekanauki.pl/articles/171972.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
nanonośniki leków
terapia celowana
ligandy
wiązania kowalencyjne
system dostarczania leków przeciwnowotworowych
nanocarriers of drugs
targeted therapy
ligands
covalent bond
anticancer drug delivery system
Opis:
In this study we describe the most popular biomedical engineering nanoparticles including carbon nanotubes [17-20], liposomes [4-7], polymeric micells [11-13], quantum dots [3, 21-23], hydrogels [24-27], dendrimers [14-16] which are recently considered as modern drug carriers. These nanomaterials are applied for cancer diagnostic and targeted delivery of active compounds as chemotherapeutics in so called targeted therapy. Thus, we characterized the ideas of targeted therapy for which compositions of carriers with antibody are constructed (Figs. 3, 4). We also compared the traditional and targeted mechanisms [1, 3, 28-29] of drug delivery (Fig. 2). During targeted therapy only the essential dose of drug (less than during conventional chemotherapy) is delivering to the cancer cell. In additional, the application of targeted therapy reduces side effects, being very characteristic for the traditional treatment. The anticancer compound can selectively hits the target only, due to the presence of the ligands attached to the surface of nanocarirer. We characterized ligands which are often use in nanomedicine: antibodies [33-37], folic acid [30-33], peptides [33, 38, 39], aptamers [33, 40, 41] and transferrin [33, 42-44]. The purpose of this study is description of the bioconjugation of ligand-nanocarrier. This step is necessary and very important in synthesis of the novel drug delivery systems in targeted anticancer therapy. We report recent advances in the field showing the formation of amides (Figs. 6-8) [51-57], thioethers (Figs. 9-11) [52, 60-66], disulfides (Fig. 12) [69], and acethyl-hydrazone groups (Fig. 13) [73]. Special attention is paid to the process such as Diels-Alder (Figs. 14, 15) [74, 75] and "click chemistry" through the cycloaddition of Huisgen (Figs. 16, 17) [79-82]. We describe also the reaction of Staudinger [83] and the process of formation Schiff 's base [84]. The processes enable very mild and selective modification of the carriers through formation of amide bound. These methods ware less popular but allow the fictionalization of nanocarriers in biomedical application. Each reaction or process needs special and individual environment and conditions, which are summarized in Table 1.
Źródło:
Wiadomości Chemiczne; 2011, 65, 9-10; 887-915
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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