Search results for "fusion"
showing 10 items of 4513 documents
Das lösungsverhalten von polyäthylenterephthalat
1970
Das Losungsverhalten von fraktioniertem Polyathylenterephthalat wurde viskosimetrisch, durch Sedimentation und Diffusion sowie durch osmotische Messungen untersucht. Daneben wurden die durch Endgruppentitration erhaltenen Molekulargewichte ermittelt. Fur M aus Sedimentation und Diffusion ergibt sich in o-Chlorphenol bei 25°C die Viskositats-Molekulargewichtsbeziehung Die Temperaturabhangigkeit der Viskositat was in o-Chlorphenol negativ, dagegen in m-Kresol schwach positiv. Aus dem Zusammenhang [η] = f(M) wurde die ungestorte Dimension nach STOCKMAYER-FIXMAN ermittelt. Sie ist etwa σ = 1,3 mal so gros wie die zu vollig freier Drehbarkeit um die Ketteneinfachbindungen gehorende Dimension. De…
The Role of Tissue Pressure and Bulk Flow in the Formation and Resolution of Cold-Induced Edema
1976
The mechanisms responsible for the dynamics of cold-induced edema, its spread and resolution, were examined. The findings indicate that bulk flow and not diffusion should be considered as the main mechanism for the edema spreading through the extracellular spaces of the white matter.
Studies on supramolecular gel formation using DOSY NMR
2015
Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential…
Transport coefficients of n-butane into and through the surface of silicalite-1 from non-equilibrium molecular dynamics study
2009
We have studied coupled heat and mass transfer of n-butane through a membrane of silicalite-1. A description of the surface was given using non-equilibrium thermodynamics, and transport coefficients were determined. Three independent coefficients were found for the whole surface: the resistance to heat transfer, the coupling coefficient and the resistance to mass transfer. These coefficients were defined in stationary state. All resistances are significant, and show that the surface acts as a barrier to transport. A new scheme was devised to find the enthalpy of adsorption, from two particular coupling coefficients, namely the measurable heats of transfer. The method yields the enthalpy of …
Diffusion Control in Single-Site Zinc Reticular Amination Catalysts.
2020
Zn-containing metal-organic frameworks have been used for the first time as heterogeneous catalysts in the amination of C-Cl bonds. The use of extended bis(pyrazolate) linkers can generate highly porous architectures, which favor the diffusion of amines to the confined spaces with respect to other imidazolate frameworks with narrower pore windows. The N4Zn nodes of the Zn-reticular framework show comparable activity to state-of-the-art homogeneous Zn amination catalysts, avoiding the use of basic conditions, precious metals, or other additives. This is combined with long-term activity and stability upon several reaction cycles, without contamination of the reaction product. ispartof: INORGA…
Transfer of Water and Active Molecules at the Interfaces in Complex Food Systems: Theoretical and Practical Aspects
2011
Abstract During processing, storage and consumption, mass transfer of various molecules (water, gases, flavour compounds or other solutes) occur between the different phases in complex food products, and/or also between the complex food and its surroundings. These mass transfers can lead to physical and/or chemical changes and thus induce food quality modifications. The objective of this presentation is to better understand the behaviour of small molecules at the interfaces, especially in model heterogeneous food systems. Different techniques have been developed to characterize their properties and their impact on the mass transfers. Particularly, techniques such as rotative diffusion cell …
Li-ion diffusion in Li_{x}Nb_{9}PO_{25}$
2013
Abstract Wadsley–Roth phase Li x Nb 9 PO 25 has been studied as a potential candidate for anode material of Li-ion batteries. Its crystal structure, which consists of ReO 3 -type blocks of NbO 6 octahedra connected with PO 4 tetrahedra, provides a good stability and performance during Li + insertion/removal. Li-ion chemical diffusion coefficient ( D chem ) in Li x Nb 9 PO 25 was determined by means of potentiostatic intermittent titration technique and electrochemical impedance spectroscopy. Different data treatments (classical Warburg equation or the model of an electrode system with ohmic potential drop and/or slow kinetics of the interfacial Li + ion transfer across the electrode/electro…
Spatially limited diffusion coupled with ohmic potential drop and/or slow interfacial exchange: a new method to determine the diffusion time constant…
2004
Abstract We have analyzed chronoamperometric curves, I ( t ), after small-amplitude potential steps Δ E (PITT technique) for the model of linear diffusion of a species inside an electroactive film, taking into account ohmic effects in the external media (solution and electrode) as well as a finite rate of the interfacial exchange. For its short-time interval, t ≪ τ d ( τ d is the diffusion time constant, corresponding to unlimited diffusion from the interface), three approximate analytical expressions have been proposed. One of these represents an interpolation formula between the value of the current at the start of the diffusion process, I (0)=Δ E / R ext (after the end of the EDL chargin…
Effects of pressure, temperature and atomic exchanges on phase separation dynamics in Au/Ni(111) surface alloy: Kinetic Monte Carlo study
2015
Abstract Instability of the Au/Ni(111) surface alloy is studied in different CO gas pressure, p , and temperature limits using kinetic Monte Carlo simulations. We analyze the reaction front dynamics and formation of Au clusters using the model which takes into account surface adatom pair and three-body interactions, CO adsorption and desorption, catalytic carbonyl formation reaction, Au and Ni adatom diffusion and their concerted exchange. Variation of interaction parameters allows us to identify three possible reaction front propagation limits with different pressure dependencies: (i) slow channel-like flow in agreement with experimental data [1] (step flow rate, R , increases with p ), (i…
Probing the spectral dynamics of single terrylenediimide molecules in low-temperature solids
1999
Abstract Fluorescence excitation lines of single terrylenediimide (TDI) molecules were recorded in the matrices polyethylene (PE) and hexadecane (HD) in the temperature range between 1.4 and 13 K. From line width distributions at 2.5 K in both matrices it was concluded that the disorder, theoretically modeled by a distribution of two-level systems (TLSs), is about three times stronger in PE. Temperature-dependent measurements of the line shape of single chromophores showed a reversible broadening and shift of the zero-phonon lines. We attributed this behavior to dephasing caused by pseudolocal phonons and to spectral diffusion caused by fluctuating TLSs of the disordered host. Following the…