Search results for "Physis"
showing 10 items of 102 documents
Adsorption of hydrogen isotopes in the zeolite NaX: Experiments and simulations
2017
Abstract Among the different methods to separate hydrogen isotopes one is based on the physisorption at low temperature (below 100 K) where quantum effects induce a particular behavior. In the present work, we study the adsorption of single H 2 and D 2 on the zeolite NaX by combining experiments (manometry) from 30 to 150 K and molecular dynamics simulations at 40 and 77 K. Simulations also include the adsorption analysis for T 2 . Adsorption on NaX membranes is simulated and quantum corrections are introduced by using the well-known Feynman–Hibbs approach into the interaction potentials. Experimental adsorption isotherms are reproduced by using the Toth equation and it is shown that the ad…
Symphysis. Patocka face à ‘‘l’empirie trop grossière et naïve’’ d’Aristote
2014
International audience
Theoretical study of the interaction between carbon nanotubes and carboplatin anticancer molecules
2015
International audience; Full DFT calculations were carried out to study the interactions between single-wall functionalized carbon-based metallic nanotubes (CNTs) and carboplatin anticancer drugs. The geometry of the CNT-carboplatin was optimized considering different molecular configurations on inner and outer surfaces of the nanotubes. Simulation results show that the most stable physisorption state for molecules is to be located inside the nanotubes in a parallel configuration. Furthermore{,} we demonstrated that the molecular physisorption was reinforced as soon as the number of encapsulated carboplatin molecules increased{,} leading to a favored state where the nanovector is filled by …
Theoretical use of boron nitride nanotubes as a perfect container for anticancer molecules
2016
International audience; In recent years great interest has emerged in the development of nanocarriers for drug transport. One of themajor challenges is to obtain a drug delivery system able to control the drug release profile, transportabsorption and distribution, in the view of improving efficacy and safety. Herein, we present theoreticalresults based on density functional theory (DFT) to determine the best adsorption site for the anticancerifosfamide molecule in boron nitride nanotubes. For this functionalized system we determine thedependence of the adsorption energy on the displacement of molecules in the outer and inner boronnitride surfaces, together with their local morphological and…
Influence of dissolved organic matter from terrestrial origin on the changes of dinoflagellate species composition in the Gulf of Riga, Baltic Sea
2004
A mesocosm experiment was used to investigate the effect of terrestrial-origin dissolved organic matter (DOM) on the development of dinoflagellates in natural summer phytoplankton from the Gulf of Riga. Seawater was collected in the central part of the Gulf of Riga and at the entrance of the Gulf in June 1999. DOM was extracted from Parnu River water by use of tangential ultrafiltration. Experimental series were enriched with DOM, DOM in combination with nitrate and phosphate, and only with inorganic nutrients. Enrichments were added in ranges of their natural concentrations. Dinophysis acuminata, Protoperidinium brevipes and Gymnodinium spp. were dominant species in the initial dinoflagell…
Progressive femoral cortical and cancellous bone density loss after uncemented tapered-design stem fixation
2010
Background Aseptic implant loosening and periprosthetic bone loss are major problems after total hip arthroplasty (THA). We present an in vivo method of computed tomography (CT) assisted osteodensitometry after THA that differentiates between cortical and cancellous bone density (BD) and area around the femoral component.Method Cortical and cancellous periprosthetic femoral BD (mg CaHA/mL), area (mm2) and contact area between the prothesis and cortical bone were determined prospectively in 31 patients 10 days, 1 year, and 6 years after uncemented THA (mean age at implantation: 55 years) using CT-osteodensitometry.Results 6 years postoperatively, cancellous BD had decreased by as much as 41%…
Solitary central osteoma of mandible in a geriatric patient: Report and review
2016
UNLABELLED Solitary central osteomas of jaw are extremely rare lesions with only few previously documented cases. This paper reports a case of large solitary central osteoma involving mandible symphysis- parasymphysis region in an elderly female patient. A brief review of similar cases reported in the literature is also provided in this paper. KEY WORDS Osteomas, osteogenic,bone, tumor, jaw, mandible.
Definizione e significati della physis in Aristotele a partire dal confronto con la techne Il logos come apertura della physis alla techne in Fisica …
2015
Oltre all' idea della genesi della dottrina delle cause dal confronto fra techne e physis, l’ipotesi che guida questo studio, a tale idea strettamente connessa, è l’interpretazione della techne aristotelica come sussunzione del divenire naturale, e delle sue catene causali, entro l’operare umano in vista di un fine: la similitudine fra techne e physis viene colta da Aristotele nell’essere entrambe movimenti che producono enti imponendo una forma ad una materia adeguata e secondo un piano finalizzato; in entrambi questi processi la causa formale e la causa finale del movimento giungono, da un certo punto di vista, ad identificarsi.
Imidazolium functionalized carbon nanotubes for the synthesis of cyclic carbonates: reducing the gap between homogeneous and heterogeneous catalysis
2016
Single walled carbon nanotubes (SWCNTs) were functionalized with imidazolium salts bearing vinyl functionalities. An extremely high loading of active species was achieved through a straightforward one-pot procedure involving self-assembly of the imidazolium moieties followed by radical initiated polymerization of the double bonds. The materials were extensively characterized by transmission electron microscopy, Raman spectroscopy, nitrogen physisorption and combustion chemical analysis. The imidazolium functionalized SWCNTs displayed excellent catalytic activity for the reaction of CO2 and epoxides to produce cyclic carbonates as demonstrated by the excellent turnover numbers (TON). Moreove…
Interaction Mechanisms between guaiacols and lignin: the conjugated double bond makes the difference.
2011
Lignin is considered to be responsible for a selective sorption of phenolic compounds on wood. In order to investigate the mechanisms involved, two similar guaiacol compounds--only differing by the nature of the para side chain--were adsorbed on oak wood extracted lignin. Vapor sorption-desorption isotherms indicated that about 3.5 wt % of 4-vinylguaiacol is adsorbed near saturation whereas it is only 0.8% for 4-ethylguaiacol. For both compounds, the isotherms displayed a hysteresis though significantly greater for 4-vinylguaiacol. Analyses of the hydroxyl stretching region of FTIR spectra of the lignin/4-ethylguaiacol and lignin/4-vinylguaiacol complexes indicated that physisorption via hy…