Search results for "General Chemistry"
showing 10 items of 13910 documents
Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts
2019
A versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc-gallium oxynitrides and zinc-gallium-indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well-defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2 g-1 ). X-ray diffraction studies show that the final material is not a…
Dual Enzyme-Triggered Controlled Release on Capped Nanometric Silica Mesoporous Supports
2012
The development of nanoscopic hybrid materials equipped with “molecular gates” showing the ability of releasing target entrapped guests upon the application of an external trigger has attracted great attention and has been extensively explored during recent years.1 These nanodevices are composed of two subunits, namely, a suitable support and certain capping entities grafted on the surface of the scaffolding.2 The support is used as a suitable reservoir in which certain chemicals can be stored whereas the molecules grafted in the outer surface act as a “gate” and can control the release of the entrapped molecules at will. Both components are carefully selected and arranged in order to achie…
Tietoa ja taitoa toisen asteen verkko-opetukseen
2007
Siirtyminen perinteisestä opetuksesta verkko-opetukseen ei käy käden käänteessä. Paine lisääntyvään tieto- ja viestintäteknologian ja verkon opetuskäyttöön kuitenkin kasvaa. Verkko-opetus ja -opiskelu edellyttävät opettajilta uusia tapoja opettaa, mutta ne vaativat myös opiskelijoilta uusia tyylejä oppia. Tarvitaan virtuaalisia opetus- ja opiskelutaitoja. Kirjoituksessa kerrotaan Keski-Suomen Opinpolku projektista ja sen jälkivaiheista. Opinpolku tarjosi opettajille vierikoulusta, jonka tavoitteena oli kohentaa didaktisia perustaitoja tietotekniikan opetuskäytössä. Haasteina ovat opettajien ajankäyttö, verkkodidaktiikka ja tekniikka.
Thermodynamically driven self-assembly of pyridinearene to hexameric capsules
2019
Pyridinearene macrocycles have previously shown unique host–guest properties in their capsular dimers including endo complexation of neutral molecules and exo complexation of anions. Here, we demonstrate for the first time the formation of hydrogen bonded hexamer of tetraisobutyl-octahydroxypyridinearene in all three states of matter – gas phase, solution and solid-state. Cationic tris(bipyridine)ruthenium(II) template was found to stabilize the hexamer in gas phase, whereas solvent molecules do this in condensed phases. In solution, the capsular hexamer was found to be the thermodynamically favoured self-assembly product and transition from dimer to hexamer occurred in course of time. The …
Conformational Dynamics of the Dengue Virus Protease Revealed by Fluorescence Correlation and Single-Molecule FRET Studies.
2021
The dengue virus protease (DENV-PR) represents an attractive target for counteracting DENV infections. It is generally assumed that DENV-PR can exist in an open and a closed conformation and that active site directed ligands stabilize the closed state. While crystal structures of both the open and the closed conformation were successfully resolved, information about the prevalence of these conformations in solution remains elusive. Herein, we address the question of whether there is an equilibrium between different conformations in solution which can be influenced by addition of a competitive inhibitor. To this end, DENV-PR was statistically labeled by two dye molecules constituting a FRET …
Dating archaeological copper/bronze artifacts by using the voltammetry of microparticles.
2014
A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.
Dialogioppiminen ryhmä- ja yksilötasoilla hoitotyön kontekstissa
2000
Artikkelissa dialogioppimista on tulkittu hoitotyön oppimisen ja opettamisen erilaisissa käytänteissä. Käsitys dialogista perustuu Bahtinin puheen teoriaan, jossa näkökulmien vastakkaisuutta pidetään dialogin syntymisen ehtona. Käsitys oppimisesta perustuu kontekstuaaliseen näkemykseen, jossa oppimisen kohteeksi rajataan arkitodellisuus ja sieltä nousevat ongelmat. Koska arjen ristiriitaiset käytänteet kiinnittyvät erilaisiin ajattelu- ja toimintamalleihin, puheesta on etsitty historiallisia ääniä, vakiintuneiksi muodostuneita hoitamisen ja oppimisen muotoja. Tarkoituksena on ollut selvittää, millaisten dialogien avulla näistä erilaisista äänistä rakennetaan jaettua ja yksilöllistä tietämys…
Sähköpostin avulla perustelevaan keskusteluun?
1997
Vuorovaikutus muiden ihmisten kanssa edistää argumentointitaitojen ja kriittisen ajattelun kehittymistä. Entä kun vuorovaikutus tapahtuu sähköpostin avulla? – Kirjoittaja väitteli kasvatustieteiden tohtoriksi 7.6.1997 Jyväskylän yliopistossa. Väitöskirjan aiheena oli Studying argumentation in higher education by electronic mail.
On the convergence of zero-point vibrational corrections to nuclear shieldings and shielding anisotropies towards the complete basis set limit in wat…
2016
The method and basis set dependence of zero-point vibrational corrections (ZPVCs) to nuclear magnetic resonance shielding constants and anisotropies has been investigated using water as a test system. A systematic comparison has been made using the Hartree–Fock, second-order Møller–Plesset perturbation theory (MP2), coupled cluster singles and doubles (CCSD), coupled cluster singles and doubles with perturbative triples corrections (CCSD(T)) and Kohn–Sham density functional theory with the B3LYP exchange-correlation functional methods in combination with the second-order vibrational perturbation theory (VPT2) approach for the vibrational corrections. As basis sets, the correlation consisten…
Water in stereoselective organocatalytic reactions
2009
In this review, recent advances in asymmetric organocatalytic reactions carried out with variable amounts of water, from substoichiometric to a large excess (reaction medium), are discussed. We also summarize several proposed mechanisms for the different possibilities of the action of water both in the increased activity of the catalyst and in the asymmetric induction. Finally, the application of this catalytic methodology to the enantioselective synthesis of valuable compounds through enamine or iminium catalysis is presented.