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An ion-exchange material – Poly(diallyldimethylammonium carbonate) (PDDACA) containing mobile carbonate has been prepared and it has been blended in a fixed carrier membrane material – polyvinylamine (PVAm) containing abundant amine-group to adjust the carrier microenvironment of the fixed carrier membrane. It makes the mobile carrier cruise around the fixed carrier. On one hand, the CO2 can be transported continuously in the swing area of fixed carrier through the mobile carriers, the passivity of fixed carrier can be overcome and the utilization efficiency of fixed carrier can be enhanced. On the other hand, a loose and low crystalline system will be obtained by blending two polymers, the number of effective mobile carrier will be increased with mobile carriers unlocking from the crystalline area, and the loose and low crystalline system will provide a good environment for the movement of mobile carriers. These are conducive to enhance the performance of blend membrane in comparision with single polymer membrane. The CO2 permeance and CO2/N2 selectivity of PVAm-PDDACA membrane, which concurrently contains fixed amine carriers and movable carbonate carriers, can reach 909 GPU and 102 at 0.11 MPa, respectively. The performance of PVAm-PDDACA membrane is enhanced obviously in comparision with PVAm membrane and PDDACA membrane.

The results of experimental studies on the batch extraction of L-lysine by emulsion liquid membrane are discussed and the capabilities of this method in the separation of solute from dilute aqueous solutions are shown. Studies on the extraction equilibrium for organic and aqueous phases were performed. The experimental results showed that the degree of extraction was increased by an increase in the pH of the feed phase, the concentration of [H + ] in the internal phase, and concentration of the carrier in the organic phase. An optimum value of stirring speed was achieved. The rate of water swelling as an undesirable phenomenon was also measured.

In the present work, the effect of different anions such as Cl − ,N O 3 − ,S O 4 2− ,C H 3COO − and ClO3 − on the separation of copper and zinc by supported liquid membrane using TOPS-99 as mobile carrier was studied. Celgard 2400, a micro-porous poly-propylene film was used as the solid support for the liquid membrane. It was observed that, the presence of 10 mol/m 3 of NaCl, NaNO3 ,N a 2SO4, and NaClO3 in the feed solution enhanced the zinc flux, JZn from 2.5 × 10 −5 to 4.52 × 10 −5 , 4.99 × 10 −5 , 5.2 × 10 −5 and 3.333 × 10 −5 mol/m 2 /s, respectively. Further increase of anion concentration up to 1000 mol/m 3 in the feed, decreased the zinc flux to 3.45 × 10 −5 , 3.6 × 10 −5 , 2.19 × 10 −5 and 2.00 × 10 −5 mol/m 2 /s, respectively. In presence of CH3COONa in the feed, the zinc flux remained constant up to 10 mol/m 3 but with further increase in salt concentration, the zinc flux decreased. At pH 2.5 the co-permeation of copper with zinc was negligible and the highest separation factor was obtained at this pH. The maximum values of separation factor obtained in presence of NaCl, NaNO3 ,N a 2SO4 ,C H 3COONa and NaClO3 were 1127.18, 1244.38, 1296.75, 623.44 and 831.17, respectively. © 2004 Elsevier B.V. All rights reserved.

Transition from p- to n-type response, induced by the change in the gas concentration and the operating temperature, was observed for α-Fe 2 O 3 -based semiconducting sensors. This phenomenon is due to the formation of an inversion layer at the surface and therefore to the inversion of the type of mobile carrier at the surface. Different gas atmospheres leads to the different contribution of surface electrons and holes in the overall conductivity, which leads for the predominating either p- or n-type response.

This paper presents a two dimensional analytical model for the on state of a lateral insulated gate bipolar transistor (IGBT). Using the conformal mapping technique, the dependence of the mobile carrier concentration in the drift region on the geometrical device parameters is determined. Moreover, the current distribution of the lateral IGBT is directly linked to the geometrical parameters. Two dimensional device simulations with MEDICI have been carried out to verify the model and quantify its accuracy.

This paper examines the influence of mobile network competition on the prices of fixed-to-mobile calls. Because fixed line customers cannot, in general, distinguish the identity of a specific mobile network, these networks have market power when setting termination charges for calls from fixed lines. We show that: (1) unregulated mobile termination charges will result in higher than monopoly call prices; (2) the regulation of termination charges and prices downward will affect mobile subscription rates and may lower these rates; and (3) regulation of any mobile carrier’s termination charges can reduce fixed to mobile prices but will result in an increase in unregulated carriers’ termination charges. When fixed line consumers can distinguish between the different mobile networks they are calling, fixed to mobile call prices will fall relative to their level under customer ignorance. Direct mobile charging for termination also exerts downward pressure on the total fixed to mobile call price. A low cost method of lowering fixed to mobile charges would be to facilitate the identification of carriers by consumers and to restructure billing so that mobile networks are able to directly charge fixed line consumers for termination services.

We have investigated the contributions of CuO2 planes and CuO chains on the transport properties of YBa2Cu4O8 by measuring the electrical resistivity and thermoelectric power (S) of Y1−xPrxBa2(Cu1−yZny)4O8, Y1−xCaxBa2Cu4O8 and YBa2(Cu1−xGax)4O8. Pr reduces the mobile carrier concentration in the CuO2 planes in YBa2Cu4O8, as a consequence, the superconducting transition temperature is progressively decreased with increasing Pr. The S(T) data suggest that the metallic behavior at lower temperature of the Pr and Zn doped compounds is contributed by the double CuO chains. On the other hand, the S(T) behavior of Ca doped samples is opposite to that of the Pr doped samples because the doping of Ca in Y-site introduces holes in the CuO2 planes. However, the substitution of Ga in Cu(1)-site suppresses the carrier concentration in CuO chains and increases the normal-state resistivity revealing the important contribution from CuO chains on the metallic behavior of YBa2Cu4O8 and PrBa2Cu4O8.

A liquid membrane containing N503, N,N-di(1-methylheptyl) acetamide, as a mobile carrier, is proposed for the high efficient removal of phenol from waste water. Effects of different factors on phenol removal are investigated. Under the optimum operation condition obtained very satisfactory results have been achieved for the treatment of four kinds of high concentration industrial phenolic waste water.

We study the effect of peer influence in the diffusion of the iPhone 3G across a number of communities sampled from a large dataset from a major European Mobile carrier in one country. We identify tight communities of users in which peer influence may play a role and use instrumental variables to control for potential correlation between unobserved subscriber heterogeneity and friends’ adoption. We provide evidence that the propensity of a subscriber to adopt increases with the percentage of friends who have already adopted. During a period of 11 months, we estimate that 14% of the iPhones 3G sold by this carrier were due to peer influence. This result is obtained after controlling for social clustering, gender, previous adoption of mobile Internet data plans, ownership of technologically advanced handsets and heterogeneity in the regions where subscribers move during the day and spend most of their evenings. This result remains qualitatively unchanged when we control for changes over time in the structure of the social network. We provide results from several policy experiments showing that with this level of effect of peer influence the carrier would have hardly benefited from using traditional marketing strategies to seed the iPhone 3G to benefit from viral marketing.

An emulsion liquid membrane containing Span-80, CHCl 3 and o -phenanthroline, as a mobile carrier, is proposed for the preparation of nanosized semiconductor CdS particles. Effects of the different factors on the synthetic reaction were investigated. The structure and morphology of the products were characterized, and the opto-electronic properties were detected. Under the conditions of Roi 2.0, Rew 1.5 and pH 5, in 10 min of contact between ELM and the external aqueous phase, the CdCl 2 in the external aqueous phase was completely transferred and reacted with the Na 2 S in internal aqueous phase, and turned into size-quantized CdS nanocrystals with the average size of about 4.5 nm. The ELM method may open a new synthetic route for a series of nanostructured inorganic materials.

IN RECENT years, the reaction-diffusion systems have been studied and applied extensively to various models arisen from biology and chemistry. In [3] Witta Ebel introduced the concept of a mobile carrier combining reversibly with a substrate as a possible mechanism for facilitated transport across biological membranes (cf. [7]). The equations for this model in a onedimensional domain are given by the system

This paper examines the influence of mobile network competition on the prices of fixed-to-mobile calls. Because fixed line customers cannot, in general, distinguish the identity of a specific mobile network, these networks have market power when setting termination charges for calls from fixed lines. We show that: (1) unregulated mobile termination charges will result in higher than monopoly call prices; (2) the regulation of termination charges and prices downward will affect mobile subscription rates and may lower these rates; and (3) regulation of any mobile carrier's termination charges can reduce fixed to mobile prices but will result in an increase in unregulated carriers' termination charges. When fixed line consumers can distinguish between the different mobile networks they are calling, fixed to mobile call prices will fall relative to their level under customer ignorance. Direct mobile charging for termination also exerts downward pressure on the total fixed to mobile call price. A low cost method of lowering fixed to mobile charges would be to facilitate the identification of carriers by consumers and to restructure billing so that mobile networks are able to directly charge fixed line consumers for termination services.

Pressure effect on Hall coefficient, R H was investigated in Y 0.9 Ca 0.1 Ba 2 Cu 3 O y (6.72⩽y⩽6.98) samples with Cu O chain structure and Y 1− x Ca x Ba 2 Cu 3 O y (y=6) samples without Cu O chain structure. Its is found that the Cu O chain structure is a source of the pressure-induced mobile carrier.

The substitution effects on the different sites in YBa 2 Cu 3 O 7−y were investigated experimentally. It is shown that there are two type mechanisms which affect the T c of samples. Namely the substitution outside CuO 2 plane changes the mobile carrier concentration and the substitution of Cu(II) within CuO 2 planes leads to destroying of the magnetic ordering, producing magnetic pairbreaking. Both of them determine the T c of the systems directly.

A liquid membrane was prepared by entrapping tributyl phosphate (TBP) in a cellulose triacetate (TAC) membrane matrix. The membrane was used to separate two aqueous solutions, one acidic and the other alkaline, which were saturated with TBP to prevent its loss from the membrane. Uphill transport of uranium was achieved with the TBP liquid membrane. Both solutions containing TBP were stirred magnetically. When the initial concentration of uranium in the two solutions was 3.5 mM, more than 50% of the uranium contained in the acidic solution was transported to the alkaline solution across the liquid membrane within 5 h. A transport mechanism is described in which the membrane-bound TBP acts as a mobile carrier for uranium.

63,65 Cu NMR and NQR studies of YBa 2 Cu 3 O 7−δ are described for compositions, δ, of 0.0, 0.3, and 0.9. Spin-lattice relaxation rates in YBa 2 Cu 3 O 7 reveal significantly different electron dynamics at the two Cu sites in both the normal and superconducting states. In YBa 2 Cu 3 O 6.7 , the relaxation rates of the sites giving a 31 MHz NQR line are dramatically lower (by a factor ∼ 1/1500) than in YBa 2 Cu 3 O 7 indicating the essential vanishing of mobile carrier density on these sites. In contrast, relaxation at the 22 MHz sites is reduced only about 30%. Interpretation of these and other NMR and NQR data is discussed in relation to the question of assignment of the NQR lines to the appropriate crystalline sites.

The analysis of transport kinetics has lacked both a unified treatment in which general rate equations are written entirely in terms of experimental parameters, and a convention by which these parameters may be designated in a concise yet immediately recognizable manner. Such a treatment is presented here in an easily accessible form, and a simple system of nomenclature is proposed resembling that in use in enzyme kinetics. The treatment is independent of assumptions about rate-limiting steps in transport, and applies to both active and facilitated systems, including obligatory exchange. A single substrate is characterized by twelve different parameters, only five of which are required in theory to calculate the others. If a second substrate is present on the trans side of the membrane there are six more parameters. All eighteen parameters are linked by multiple relationships which provide a complete set of rejection criteria for the generalized form of the mobile carrier. Relationships among parameters are also defined that give information on the rate-limiting steps in transport. Equations governing any individual experiment, involving only experimental parameters, are easily written out from the general expressions, for example under conditions of zero trans and infinite trans flux, equilibrium exchange, or competitive inhibition.

Two dimensional mobile carrier transport in a semiconductor is simulated using the finite element method. Two algorithms are compared for computational efficiency and accuracy in modeling an IGFET transistor. With the first, the non-linear partial differential equations are decoupled and solved sequentially using a minor and a major iterative cycle. In the second, Newton's method is used to linearize the equations, and they are solved simultaneously using only a major loop. Results show the decoupled approach to be faster and require less storage than the coupled Newton approach for simulation of device operation where the mobile carrier densities are equal to or less than the fixed charge density. The coupled approach is more efficient for highly non-linear problems where the mobile carrier densities exceed the fixed charge density but requires far more storage (2.5x) and set up time (100x).

The possibility of a mobile carrier model for phosphate transport in rat liver mitochondria was examined on the basis of counterflux experiments. The rate of Pi uptake and Pi exchange were identical and depended on the external pH value. The alkalization of the suspending medium of Pi-preloaded mitochondria induced an efflux of Pi. The induction of a net Pi efflux by alkalization of the external medium stimulated the rate of 32Pi uptake. Arsenate was shown to be an alternative substrate for Pi-carrier. A net efflux of inorganic arsenate (Asi), induced by alkalization of the external medium, also supported an acceleration of the 32Pi uptake. When mitochondria were first preloaded with Asi and 32Pi and then diluted into a more alkaline buffer free of Asi, a transient uptake of 32Pi was observed. These results are discussed in terms of reorientation of the active site of the Pi carrier under the conditions where a net efflux of Pi or Asi occurred. This conclusion was supported by a change in the accessibility of the SH groups of the carrier toward poorly permeant thiol reagents during that process.

Sodium permeability in phospholipidic large unilamellar vesicles induced by two 15-0 5 macrocyclic polyether derivatives, a carboxylic one 1a and a neutral one 1b , has been studied. The neutral derivative, 1b , appears to behave as a classical mobile carrier such as valinomycin and the carboxylic carrier, 1a , as an ionophore of the nigericin group.

Substrate bias can be used as a powerful diagnostic tool for studying the magneto-transport in an inversion layer. One can accurately determine the mobile carrier threshold by such a study. Marked changes in the mobility occur with increasing confinement to the surface; a decrease for high electrons densities and an increase for low electron densities. The former was expected while the latter was not.

Solute uptake by a mobile carrier mechanism has been simulated with an analog computer for the case where the movement of the carrier across the membrane is rate-limiting. The ratio of the rate constants for the translocation of the loaded carrier to those for the translocation of the empty carrier was varied to simulate three important conditions of transport: a ratio greater than unity, which led as previously predicted to trans stimulation; a ratio less than unity, which led as predicted to trans inhibition; and a ratio equal to unity, which eliminated any effect of solute concentration on the trans flux. In addition, transients related to the relative amount of the mediator species are recorded. When previous loading of the cells with the solute was simulated, we obtained overshoots in the uptake of labeled solute corresponding to those often seen experimentally. The inhibitory action of 2,4-dinitrofluorobenzene on a well characterized laboratory example of trans stimulation was analyzed in terms of the model. Whereas the simulation shows that a change in the ratio of the rate constants for translocation can modify the intensity of the trans phenomenon, the action of dinitrofluorobenzene proved instead to arise from decreases in the two carrier fluxes that cause the transport in question to be uphill. The distribution of the influence between these two fluxes may assist identification of the mode of energization of the process.

The in vitro studies reported here are concerned with the interactions of bile salt alone and of bile salt, fatty acid, monoglyceride and triglyceride in various combinations, with the mucosal surface of paired everted sacs prepared from the rat small intestine. Lipid-induced changes were noted in transmural potential (ΔPD) and in short-circuit current ( ΔI sc ) during incubation in buffered media. Increments in PD and I sc appeared to be saturable functions of graded concentrations of taurocholate and of glyceryl monooleate in the mucosal medium. This was confirmed by Line-weaver-Burk plots of the data and apparent K m values for the interaction of taurocholate and of monooleate with the ileal mucosal epithelium were estimated by extrapolation to be 3.6 and 6.0 mM, respectively. The lipid-membrane interactions are Na+-dependent. For example, apparent K m values increased as the Na+ concentration of the medium was decreased by isosmolar replacement with Tris+ or K+. Moreover, K+, compared with Tris+, seemed to inhibit markedly the bile salt interaction, but had little effect on the interaction of monoglyceride other than deprivation of Na+. Furthermore, this Na+ dependency is reflected in a mutual competitive inhibition between glucose and these lipids as well as between the lipids themselves. A comparison of ΔPD and ΔI sc data, obtained with mixed lipids containing oleic acid or triolein, suggests that 3-component preparations (with taurocholate and monoglyceride) are more effective in interacting with the mucosal surface of the sac than are the corresponsing 2-component preparations (without monoglyceride). The studies with [14C]triolein indicate that (1) a small but significant fraction of the lipid may actually enter the mucosal tissues and (2) uptake, determined under open-circuit and short-circuit conditions, appears to be an active, Na+-dependent process.

Recent studies from several laboratories suggest that the uptake of catecholamines into adrenal medullary vesicles is mediated by a mobile carrier in the vesicle membrane. A transport model is proposed in which catecholamines attach to the carrier on the outside of the membrane and are detached on the inside surface by the action of ATP; probable loci of action of uptake inhibitors (reserpine and N-ethylmaleimide) are identified.

A study has been made of carrier-mediated transport of uranium(VI) by a liquid membrane of 7-dodecenyl-8-quinolinol (Kelex 100). Uranium is transported across the membrane and concentrated in a stripping acid. The apparent rate constant of uranium transport increases slightly with increase in carrier concentration and in the pH of the feed solution. Uranium can be effectively recovered from spiked sea-water through the liquid membrane without any preliminary treatment.