Transport level

From these results it can be concluded that liver slices are a powerful tool for studying the mechanisms and specificity of carrier-mediated uptake of drugs and drug interactions which occur at the transport level. 

Chiral protoalkaloids, such as cathinone (55), a psychotropic constituent of Catha edulis Forssk. (khat), have provided probes for studying the mechanistic properties of biogenic amine transporters, and afforded information regarding the effect of stereochemistry at the transportation level of these nitrogenous compounds. ... 

All the motor drives must be placed below the transportation level. 

Wang ZQ, Bell-Farrow AD, Sonntag W, Cefalu WT. Effect of age and caloric restriction on insulin receptor binding and glucose transporter levels in aging rats. Exp Gerontol 1997 32 671-684. 

On average, a carrier located at can continue its motion only after thermal excitation. If all carriers were located at and a transport level existed at e = 0, the center of the DOS, the temperature dependence of the mobility should follow a non-Arrhenius dependence of the form exp[-(a/ 7)-2]. This temperature dependence has been recovered by both EMA studies and Monte Carlo simulations, although with a constant in the exponent of less than unity that accounts for the statistics of occupational energies. The predicted temperature dependence of the zero-field mobility is... 

Calcagno, A.M., Ludwig, J.A., Fostel, J.M., Gottesman, M.M. and Ambudkar, S.V. (2006) Comparison of drug transporter levels in normal colon, colon cancer, and Caco-2 cells impact on drug disposition and discovery. Molecular Pharmacology,... 

In addition to the reqnirements on the energy levels of donor and acceptor for interfacial charge separation, it is necessary that the work function of the electroncollecting electrode shonld be well matched to the LUMO of the acceptor material, and that of the hole-collecting material be well matched to the HOMO of the donor. In bnlk heterojunctions, photovoltaic action can only be achieved if electronic contact is made to the photoactive material nsing snitable asymmetric electrodes. For high efficiency the electrodes shonld also be condnctive and well matched in energy to the electron or hole transport levels. The constraints on electrode materials will be treated in more detail in Sections 7.5 and 7.6.5. The development and optimisation of bilayer and BHJ device types are reviewed in Sections 7.3 and 7.4 respectively. 

The already mentioned proteins OCTI and OCT3 transport small cationic substances, such as tetraalkyl ammonium compounds, polyamines such as spermine, monoamino-neurotransmitters, or N-methyl-nicotinamide across the basolateral plasma membrane [56]. OCTs play a key role in the distribution of cationic drugs and, therefore, drug interactions at the transporter level may become clinically relevant, as compounds with high affinity, such as prazosin or phenox-ybenzamine, may affect the excretion of other substrates. Certain liver diseases or obstructive cholestasis may result in alterations of hepatic clearance via these transporters. In rats, a 7-day bile duct ligation resulted in a marked downregulation of Octi and an increased hepatic accumulation of the Octi substrate tetraethylammonium [57]. 

The polaronic level of holes on the conjugated polymer donor phase is sUghtly above the HOMO of the polymer, and the transport level of the electrons is closely related to the LUMO level of the acceptor (n-type semiconductor, e.g., the fullerene). Thus, their resulting energetic sphtting has to be related to the difference between the HOMO of the donor and the LUMO of the acceptor and conceptually determines the maximum open circuit po-... 

Eg and Eh are denoted as transport levels. To carry a stationary current, they must be populated and depopulated. At each of the contacts, the contact barriers which exist there, that is the differences of the energies of the transport levels of the two contacting materials (metal/semiconductor or semiconductor 1/semiconductor 2), must be overcome in order for the contact to allow the passage of charges. And, on the other hand, the energy gap 1 ... 

Fig. 8.6 The energy diagram of an organic semiconductor, a The energy levels of the neutral isolated molecules. Sq Is the electronic ground state, S], S2. .. S are the electronic singlet excited states, Iq is the molecular ionisation energy, Aq the electron affinity of the isolated molecule, b The energy bands of the ionised states of the ideal crystal. /, is the energy of holes, VB = valence band = transport level of the holes Eg = is the energy of the conduction electrons, CB = conduction band = transport level of the electrons. P/, and Pg are the mean polarisation energies of the holes...

Fig. 8.22 The term diagram of an ideal intrinsic semiconductor with neutral contacts (see Fig. 8.21) and an applied voltage Vext- Here, only the transport levels are shown. F is the electric field strength the remaining notation is as in Figs. 8.19-8.21. The transport levels in semiconductors are flat and not curved only when the semiconductor is not p- or n-doped...

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