Effect of acid gases on the solubility of n-propylmercaptan in 50 wt% methyl-diethanolamine aqueous solution

In this communication, we have measured the solubility and partition coefficient of n-propylmercaptan in 50 wt% MDEA aqueous solution at 366 K in the presence of single and mixed acid gases (CO₂ and H₂S). A static analytic method was used for performing all the measurements. Methane was used to maintain the total pressure of the system in equilibrium cell. The concentration of n-propylmercaptan in aqueous phase was in the 50–1000 ppm (mole) range. The effect of acid gas loadings on the physical and chemical solubility of n-propylmercaptan is discussed.     

Domain Switching During Electromechanical Poling in Lead Zirconate Titanate Ceramics

In many polycrystalline piezoelectric ceramics, domain switching during the poling process leads to the development of a macroscopic polarization and piezoelectric behavior. Traditionally, poling involves the application of electric fields across two parallel electrodes. In the present work, a radial mechanical compressive stress is applied transverse to the electric field, increasing the potential for domain alignment during poling by taking advantage of ferroelasticity. Experiments demonstrate that poling of lead zirconate titanate using a combination of an electric field and a transverse mechanical compressive stress increases the d ₃₃ coefficient from 435 to 489 pC/N. Using neutron diffraction and pole figure inversion methods, the degree of non-180° domain switching is described using pole density distributions of the tetragonal c -axis (002). The degree of 002 domain alignment parallel to the electric field after the electromechanical poling process increases from 1.30 multiples of a random distribution (mrd) to >1.40 mrd at stresses exceeding 40 MPa.     

Prolonged display or rapid internalization of the IgG-binding protein ZZ anchored to the surface of cells using the diphtheria toxin T domain

We have shown previously that the diphtheria toxin transmembranedomain (T) may function as a membrane anchor for soluble proteinsfused at its C-terminus. Binding to membranes is triggered byacidic pH. Here, we further characterized this anchoring device.Soluble proteins may be fused at the N-terminus of the T domainor at both extremities, without modifying its membrane bindingproperties. This allows one to choose the orientation of theprotein to be attached to the membrane. Maximum binding to thecell surface is reached within 1 h. Anchoring occurs on cellspreviously treated with proteinase K, suggesting that T interactswith the lipid phase of the membrane without the help of cellsurface proteins. Binding does not permeabilize cells or affectcell viability, despite the fact that it permeabilizes liposomesand alters their structure. When attached to L929 fibroblasts,the proteins are not internalized and remain displayed at theirsurface for more than 24 h. When bound to K562 myeloid cells,the molecules are internalized and degraded. Thus, dependingon the cell type, soluble proteins may be anchored to the surfaceof cells by the T domain for an extended time or directed towardsan internalization pathway.     

Transport properties in polypyrrole–PVA composites: Evidence for hopping conduction

Experimental results on electrical conductivity and thermoelectric power for FeCl₃-doped polyvinyl alcohol-polypyrrole composites, with polypyrrole content exceeding the percolation threshold, are presented. The electrical conductivity is analyzed in terms of the hopping theory, whereas the thermoelectric power displays a metallic-like dependence. A model involving both the intrinsic resistance of the fibrils (V.R.H. hopping mechanisms) and the resistance of the junctions between fibrils (fluctuations-induced tunneling conduction) has been retained.     

Simplified Model and Closed-Loop Control of a Commutatorless DC Motor

A simplified dynamic model of a current-fed, self-commutated synchronous motor, operating with a constant angle between the motor counter electromotive force (CEMF) and the input current. The model, which is justified experimentally, includes only two time constants, associated with the rotor inertia and the dc link inductance. This permits the design of the current and speed controlling loops along the same principles used for classical armature-controlled dc motor drives. In this way, the experience which is widely available in industry can be applied, at least with a good approximation, to design of the commutatorless dc motor drives. Various control configurations are discussed. Control loops are designed and closed around the basic motor-inverter block. An experimental result is obtained for each control configuration, thus validating the proposed model.