63 research outputs found

    Badania pilotażowe o wiedzy i stosowaniu mnemonik z przedmiotów ścisłych przez polsklich uczniów

    Get PDF
    Mnemonic devices are specific ways, which during coding new information apply known elements for improving subsequent access to that information in the memory. Consequently, not much is known about techniques for optimizing recall performance with mnemonic devices or the suitability of using mnemonic devices in educational applications. Moreover, in literature there are a lot of examples in chemistry, biology, physics and mathematics mnemonics approaches, however in the related literature, there is a lack of current and reliable studies for this subject. In this original work we describe mnemonic methods from this point of view in the learning and teachings of science subjects. A large trumps of this article is the demonstration of the old well-known method of the learning/teaching in the new scene. This is the first article in literature that present actual data about this topic according to learning and studying the science subjects by mnemonic studies.Strategie mnemoniczne to specyficzne sposoby, które podczas kodowania nowej informacji wykorzystują znane już elementy do polepszenia późniejszego dostępu do tej informacji w pamięci. Strategie te mogą często wspomagać uczenie się oraz późniejsze przywoływanie informacji. Jednak niewiele wiadomo na temat technik optymalizowania przywoływania myśli za pomocą metod mnemotechnicznych lub stosowalności metod mnemotechnicznych w praktyce edukacyjnej. Ponadto, w literaturze jest wiele przykładów metod i podejść mnemotechnicznych w chemii, biologii, fizyce czy matematyce, jednakże w literaturze fachowej brak jest aktualnych i miarodajnych badań na ten temat. Artykuł ten stanowi autorskie podejście do zagadnienia metod mnemotechnicznych z punktu widzenia uczenia i nauczania przedmiotów przyrodniczo-ścisłych. Dużym atutem artykułu jest demonstracja starych i dobrze znanych metod uczenia/nauczania w nowym wymiarze. Zgodnie z naszą wiedzą jest to pierwszy artykuł w literaturze opisujący aktualne dane na temat związany z uczeniem i studiowaniem przedmiotów ścisłych przy użyciu metod mnemotechnicznych

    Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

    Get PDF
    The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5- dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes

    Synthesis, structure and properties of V(V) monooxido complex with ONO tridentate Schiff base

    Get PDF
    The oxidovanadium(V) Schiff base complex of formula [VO(L)(EtO)(EtOH)] (where H2L = Schiff base ligand derived from 5-methoxysalicylaldehyde and phenylacetic hydrazide) was synthesized and described. Complex crystalizes in triclinic P-1 space group. Octahedral geometry of the vanadium(V) centre is filed with oxido, ONO L2- ligand and two solvent molecules both in ethoxo and as neutral ethanol form. The complex is neutral, with 5- and 6-memebered ring formed by ONO ligand coordinated in octahedral plane with oxido and EtOH ligands in vertical positions. Two isomers are present in the unit cell, with different position of 5-membered ring versus vertical plane. The elemental analysis, magnetic susceptibility, thermogravimetry and spectroscopy (IR, UV-Vis) measurements were measured and are discussed. The cyclic voltammetry measurements show irreversible processes for vanadium(IV/V) redox system. Thermal stability both in a solid state (TG and SDTA measurements) as well as in solutions (at pH 7.0 and 2.0, studied by UV-Vis spectroscopy) is discussed

    Synthesis, structure and properties of V(III,IV and V) complexes with ONO Schiff bases

    Get PDF
    The synthesis and physicochemical properties of vanadium(III,IV,V) complexes with Schiff base ligands based on 3,5-dibromo-4-methoxy-salicylaldehyde and phenylacetic hydrazide (H2L1), 5-chlorosalicylaldehyde and 4-hydroxybenzhydrazide (H2L2) and 5- chlorosalicylaldehyde and 2-hydroxybenzhydrazide (H2L3) were presented. The formulas of the complexes {[V(L1)(HL2)]·EtOH (1), [VO(L2)(phen)]·2H2O (2) and [VO(L3)(EtO)] (3)} were proposed based on the elemental analysis, IR and UV-Vis spectra. Additionally, the IR and UV-Vis spectra (in solvents as well as in a solid state) have been discussed from the vanadium oxidation state point of view. The single crystal structure of 3 shows triclinic, P-1 space group, structure is stabilized by hydrogen bonds and strong π-π stacking interactions. The oxidation state of the metal centre was also confirmed by the magnetic susceptibility measurements. The stability of the complexes was measured in pH = 7.00 and in pH = 2.00 which allows to evaluate the use of these compounds as insulin mimetic compounds

    Ionic dioxidovanadium(V) complexes with Schiff-base ligands as potential insulin-mimetic agents : substituent effect on structure and stability

    Get PDF
    Four dioxidovanadium(V) complexes with Schiff-base ligands based on 2-hydroxybenzhydrazide with four different substituted salicylaldehydes (5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 5-nitrosalicylaldehyde, 3-bromo-5-chlorosalicylaldehyde) were synthesized and described, by using V(2)O(5) and triethylamine. The single crystal X-ray structure measurements as well as elemental analyses and IR spectra confirmed the formulas of the ionic complexes with a protonated triethylamine acting as counterion, HTEA[VO(2)(L)] (HL = Schiff-base ligand). The kinetic stability of the complexes at pH = 2 and 7 was discussed with respect to the neutral vanadium(V) complexes previously studied as potential insulin-mimetic agents. A correlation between the substituents in an aromatic ring of the Schiff-base ligands with crystal packing, and also with the stability of the compounds, was presented

    Tridentate hydrazido-hydrazones vanadium complexes : synthesis, properties and biological activity

    Get PDF
    Nine new vanadium complexes, with tridentate Schiff base ligand based on 3,5-di-tertbutyl-2-hydroxybenzaldehyde and different hydrazides, are described and characterized. The X-ray crystal structure of complex 8 shows distorted octahedral geometry of vanadium, with ONO ligand in equatorial position. The tridentate Schiff base ligand forms six membered and five-membered chelate rings at the V(V) acceptor center, with the corresponding bite angles being 82.97(9)˚ and 74.48(9)˚. The molecules are gathered by means of intermolecular OH...N hydrogen bond and layered by π...π interactions involving the pyridine and phenolate rings. Such interactions expand the structure along the crystallographic a axis. The complexes were characterized by the elemental analyses, IR, UV-Vis, EPR spectroscopy, cyclic voltammetry, thermogravimetry and magnetic susceptibility measurements. The stabilization role of co-ligands is discussed. The cytotoxicity versus HepG2 hepatocytes and inhibition of human recombinant PTP1B was studied
    corecore