4 research outputs found
Modeling the flow-induced anisotropic effective viscosity of fiber suspensions by mean-field and full-field homogenization
Palladium Nanoparticle–Graphene Catalysts for Asymmetric Hydrogenation
We report for the first time the application of
palladium nanoparticle-graphene (Pd/Gn) catalysts in the
asymmetric hydrogenation of aliphatic a,b-unsaturated
carboxylic acids using cinchonidine as chiral modifier. Pd/
Gns were prepared by deposition–precipitation from the
aqueous phase over graphite oxide and subsequent simultaneous
reduction of both the support and the metal precursor
with NaBH4. The materials obtained were
characterized by ICP optical emission spectroscopy, X-ray
diffraction spectroscopy, Raman spectroscopy, transmission
electron microscopy and X-ray photoelectron spectroscopy.
We demonstrate that the Pd/Gns modified by
cinchonidine can act as efficient catalysts in the asymmetric
hydrogenation of a,b-unsaturated carboxylic acids for
producing optically enriched saturated carboxylic acids
SzĂ©n nanocsĹ‘ jellegű nanoszerkezetek előállĂtása, mĂłdosĂtása Ă©s jellemzĂ©se fizikai, kĂ©miai Ă©s szimuláciĂłs mĂłdszerekre alapozva = Production, modification and characterization by physical, chemical and computer simulation of carbon nanotube type nanostructures
Kimutattuk, hogy a nem-hatszöges (n-H) gyűrűket is tartalmazĂł szĂ©n nanoszerkezetek (Y-elágazás, hengerspirálok, stb.) növekedĂ©sĂ©t az n-H gyűrűk beĂ©pĂĽlĂ©sĂ©nek mikĂ©ntje határozza meg, Ăşj modellt javasoltunk hengerspirálok szerkezetĂ©re. ElsĹ‘kĂ©nt kĂ©szĂtettĂĽnk Si3N4/szĂ©n nanocsĹ‘ kompozitokat Ă©s megmutattuk, hogy megfelelĹ‘ szinterelĂ©si paramĂ©terek alkalmazásával megĹ‘rizhetĹ‘k az elektromosan vezetĹ‘vĂ© tett mátrix jĂł tulajdonságai. Ăšj nanocsĹ‘ növesztĂ©si mĂłdszereket dolgoztunk ki. ElsĹ‘kĂ©nt bizonyĂtottuk, hogy az ionos besugárzás nyomán a szĂ©n nanocsöveken, valĂłban a szimuláciĂłknak megfelelĹ‘ topográfiai alakzatok jelennek meg. ElmĂ©leti modellt adtunk a hibák környezetĂ©ben azt STM felvĂ©teleken megfigyelhetĹ‘ szuperstruktĂşrák eredetĂ©re. Megmutattuk, hogy a funkcionalizálás mĂłdjátĂłl fĂĽggĹ‘en a funkciĂłs csoportok szigetszerűen, vagy folytonoshelyezkednek el. A funkciĂłs csoportok megváltoztatják a nanocsövek válaszjelĂ©t a környezetben jelenlĂ©vĹ‘ gázokra/gĹ‘zökre. Sikeresen fejlesztettĂĽnk elmĂ©leti mĂłdszereket a gyengĂ©n kölcsönhatĂł nagy atomszámĂş rendszerek leĂrására Ă©s elsĹ‘kkĂ©nt vizsgáltuk sok szĂ©n nanocsöbĹ‘l felĂ©pĂĽlĹ‘ kötegekben a csövek egymással valĂł kölcsönhatását. ElsĹ‘ elvekre illetve sűrűsĂ©gfunkcionál mĂłdszerre alapozva vizsgáltuk a duplafalĂş szĂ©n nanocsövek, illetve a nanocsĹ‘ben elhelyezkedĹ‘ szĂ©nláncok tulajdonságait. A sajátfejlesztĂ©sű hullámcsomagdinamikai mĂłdszerĂĽnkkel elsĹ‘kkĂ©nt vizsgáltuk az elektronhullámok terjedĂ©sĂ©t szĂ©n nanocsĹ‘ Y elágazásokban. | We showed that the growth of carbon nanostructures containing non-hexagonal (n-H) rings (Y-branches, coils etc.) is determined by the incorporation of the n-H rings, we proposed a new model for the structure of regularly coiled carbon nanotubes. We prepared the first Si3N4/carbon nanotube composites and we showed the under proper sintering conditions the composite can be made conductive while keeping the remarkable properties of the matrix. We developed new growth methods for carbon nanotubes. We showed for the first time that ion irradiation of carbon nanotubes indeed creates the features predicted by simulations. We proposed a theoretical description of the superstructures observed in STM in the vicinity of the defects. Depending on the way in which the functionalization is done, the functional groups appear on the nanotubes in an island-like or a continuous fashion. Their presence influences the response of the carbon nanotubes to the gases/vapors present in the atmosphere. We developed successfully theoretical tools for the description of weakly interacting large system and investigated for the first time the interaction of tubes in carbon nanotube bundles containing many tubes. Based on first principle and density functional calculations we investigated the double wall carbon nanotubes and linear carbon chains located inside a SWCNT. Using our own wave packet dynamical software we investigated the propagation of electronic waves in carbon nanotube Y junctions