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The paper discusses different possibilities for controlling piezoelectric properties of ferroelectric materials and devices. The piezoelectric properties engineering can be made on different scales. Tuning of the piezoelectric response by controlling contributions from domain walls displacement is used to illustrate engineering on nanometer scale. Texture control in ferroelectric films and grain size control is discussed as an example of property control on micrometer scale. Finally, engineering on macroscopic (millimeter) scale is illustrated by amplification methods employed in multilayer actuators and different bimorph-type structures as well as by control of electro-mechanical properties in polymer-ceramic composites.El presente trabajo discute las diferentes posibilidades existentes en el control de las propiedades piezoeléctricas de materiales ferroeléctricos y dispositivos piezoeléctricos. La ingeniería de las propiedades piezoeléctricas se puede llevar a cabo a diferentes niveles. El ajuste de dichas propiedades controlando las contribuciones del desplazamiento de paredes de dominios se usa para ilustrar el diseño a escala nanométrica. El control de la textura en láminas delgadas ferroeléctricas y el control del tamaño de grano serán tratados como un ejemplo del control de propiedades a nivel micrométrico. Por último, la ingeniería de materiales a escala macroscópica (milimétrica) será ilustrada mediante algunos métodos de amplificación empleados en actuadores multicapa y diferentes estructuras de tipo bimorfo, al igual que por métodos de control de las propiedades electromecánicas en materiales compuestos polímerico-cerámicos.

BACKGROUND/OBJECTIVES: The vitamin E derivative, a-tocopheryl acetate, is often included in formulations used in enteral nutrition. In this respect, we compared α-tocopherol and a-tocopheryl acetate absorption under 'maldigestion' conditions, such as occurring during enteral tube feeding, using differentially labeled RRR-[5,7-methyl-(²[H.sub.6])]- α-tocopherol and RRR[5-methyl-²[H.sub.3]]-α-tocopheryl acetate allowing direct comparison between free and esterified forms. SUBJECTS/METHODS: The two derivatives were given together in a single dose to six volunteers directly into the jejunum using a double-balloon perfusion system. Perfusion lasted for 1 h, and the collected blood and effluent samples were analyzed by liquid chromatography-mass spectrometry. RESULTS: In the isolated 20-cm length of exposed jejunum, on average ~6% of the two vitamin E forms were absorbed >1 h based on subtraction of effluent from influent. There was substantial difference in the absolute absorbed quantity between individuals, but no significant differences were observed in the absorption between the two labeled forms as assessed in the plasma. ²[H.sub.3]-α-tocopherol was not present in the influent, but appeared in the effluent, indicating that the acetylated form of vitamin E is cleaved by brush border enzymes in the small intestine. CONCLUSIONS: This study shows that even in the absence of digestive enzymes and bile salts, the appropriately solubilized acetylated form of α-tocopherol exhibits the same bioavailability as free α-tocopherol. This suggests that both forms can be absorbed equally under maldigestion conditions such as present clinically during enteral tube feeding. doi:10.1038/ejcn.2012.183;published online 5 December 2012 Keywords: vitamin E; bioavailability; jejunal segmental perfusion; pancreas, INTRODUCTION Natural vitamin E is a generic designation for a group of eight compounds (tocopherols and tocotrienols) synthesized by plants. (1,2) The supplemented form of vitamin E is mostly its [...]

The addition of a TiO2 seed layer when growing textured PbTiO3 and Pb(Zr,Ti)O3 thin films on textured Pt(111) thin film substrates allows the PcTiO3 texture to be turned from (100) to (111) orientation. X-ray photoelectron diffraction measurements indicate epitaxial ordering in the seed layer. The textured microstructure of the seed layer most probably corresponds to rutile(110). A crystalline, few nanometer thick TiO2 film has been shown to be a very efficient seed layer for the nucleation of PZT(111).

The design and characterization of low resistive wafer-fused heterojunctions between p-InP and p-GaAs were investigated. Doping profiles across the interface and interface contamination with carbon or oxygen were characterized using secondary ion mass spectroscopy. Results showed that the wafer-fused heterojunctions had high crystalline quality. Moreover, the large lattice mismatch between InP and GaAs was accommodated by edge dislocations.

We have examined the crystallographic structure of GaAs/InP interfaces obtained by wafer fusion following different procedures. Plan-view and cross-sectional transmission electron microscopy reveal that the interface is not only composed of a regular array of two sets of edge dislocations and is more complex than generally supposed. If a twist is created due to misalignment of the two substrates, the dislocations are not edge dislocations but also have a screw component. Dislocations for which the Burgers vectors have a component normal to the interface are also present. Those dislocations probably result from steps and some of them accommodate the tilt between the two substrates. Inclusions and voids as well as a low number of volume dislocations are present in all the samples. The observed volume dislocation density near the interface lies in the 10[sup 5]–10[sup 7] cm[sup -2] range and these volume dislocations may be associated with thermal mismatch. The origin of all these defects is discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Thephase behavior of the ternary unsaturated monoglycerides (UMG)–dl-α-tocopheryl acetate–water system has been studied.The effects of lipid composition in both bulk and dispersed lyotropicliquid crystalline phases and microemulsions were investigated. Inexcess water, progressive addition of dl-α-tocopherylacetate to a binary UMG mixture results in the following phase sequence:reversed bicontinuous cubic phase, reversed hexagonal (HII) phase, and a reversed microemulsion. The action of dl-α-tocopherylacetate is then compared to that of other lipids such as triolein,limonene, tetradecane, and dl-α-tocopherol. The impactof solubilizing these hydrophobic molecules on the UMG–waterphase behavior shows some common features. However, the solubilizationof certain molecules, like dl-α-tocopherol, leads tothe presence of the reversed micellar cubic phase (space group number227 and symmetry Fd3̅m) whilethe solubilization of others does not. These differences in phasebehavior are discussed in terms of physical–chemical characteristicsof the added lipid molecule and its interaction with UMG and water.From an applications point of view, phase behavior as a function ofthe solubilized content of guest molecules (lipid additive in ourcase) is crucial since macroscopic properties such as molecular releasedepend strongly on the phase present. The effect of two hydrophilicemulsifiers, used to stabilize the aqueous dispersions of UMG, wasstudied and compared. Those were Pluronic F127, which is the mostcommonly used stabilizer for these kinds of inverted type structures,and the partially hydrolyzed emulsifier lecithin (Emultop EP), whichis a well accepted food-grade emulsifier. The phase behavior of particlesstabilized by the partially hydrolyzed lecithin is similar to thatof bulk sample at full hydration, but this emulsifier interacts significantlywith the internal structure and affects it much more than F127. [ABSTRACT FROM AUTHOR]

BACKGROUND: Plant sterols reduce cholesterol absorption, which leads to a decrease in plasma and LDL-cholesterol concentrations. Plant sterols also lower plasma concentrations of carotenoids and alpha-tocopherol, but the mechanism of action is not yet understood. OBJECTIVES: The aims of this clinical study were to determine whether plant sterols affect the bioavailability of beta-carotene and alpha-tocopherol in normocholesterolemic men and to compare the effects of plant sterol esters and plant free sterols on cholesterol absorption. DESIGN: Twenty-six normocholesterolemic men completed the double-blind, randomized, crossover study. Subjects consumed daily, for 1 wk, each of the following 3 supplements: a low-fat milk-based beverage alone (control) or the same beverage supplemented with 2.2 g plant sterol equivalents provided as either free sterols or sterol esters. During this 1-wk supplementation period, subjects consumed a standardized diet. RESULTS: Both of the milks enriched with plant sterols induced a similar (60%) decrease in cholesterol absorption. Plant free sterols and plant sterol esters reduced the bioavailability of beta-carotene by approximately 50% and that of alpha-tocopherol by approximately 20%. The reduction in beta-carotene bioavailability was significantly less with plant free sterols than with plant sterol esters. At the limit of significance (P = 0.054) in the area under the curve, the reduction in alpha-tocopherol bioavailability was also less with plant free sterols than with plant sterol esters. CONCLUSIONS: Both plant sterols reduced beta-carotene and alpha-tocopherol bioavailability and cholesterol absorption in normocholesterolemic men. However, plant sterol esters reduced the bioavailability of beta-carotene and alpha-tocopherol more than did plant free sterols. Copyright © 2004 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]