Electrostatic coupling and local structural distortions at interfaces in ferroelectric/paraelectric superlattices

The performance of ferroelectric devices is intimately entwined with the structure and dynamics of ferroelectric domains. In ultrathin ferroelectrics, ordered nanodomains arise naturally in response to the presence of a depolarizing field and give rise to highly inhomogeneous polarization and structural profiles. Ferroelectric superlattices offer a unique way of engineering the desired nanodomain structure by modifying the strength of the electrostatic interactions between different ferroelectric layers. Through a combination of X-ray diffraction, transmission electron microscopy, and first-principles calculations, the electrostatic coupling between ferroelectric layers is studied, revealing the existence of interfacial layers of reduced tetragonality attributed to inhomogeneous strain and polarization profiles associated with the domain structure.     

Room temperature electrical manipulation of giant magnetoresistance in spin valves exchange-biased with BiFeO3

Magnetoelectric multiferroics are attractive materials for the development of low-power electrically controlled spintronic devices. Here we report the optimization of the exchange bias as well as the giant magnetoresistance effect (GMR) of spin valves deposited on top of BiFeO(3)-based heterostructures. We show that the exchange bias can be electrically controlled through a change in the relative proportion of 109° domain walls and propose solutions toward a reversible process.     

Ex vivo Activities of β‐Lapachone and α‐Lapachone on Macrophages: A Quantitative Pharmacological Analysis Based on Amperometric Monitoring of Oxidative Bursts by Single Cells

Artificial synapses for femtomolar detection : Amperometry at platinized carbon fibre electrodes has been used to unravel the complexity of β‐lapachone's effects on cellular oxidative stress. α‐Lapachone, the pharmacologically inactive para‐quinone isomer, did not display such characteristics, but over longer incubation periods both quinones induced apoptosis. The observed effects were interpreted in terms of two mechanisms involving opposite reactivities of quinones in living cells.

     

The Protein Environment Drives Selectivity for Sulfide Oxidation by an Artificial Metalloenzyme

Magic Mn–salen metallozyme : The design of an original, artificial, inorganic, complex‐protein adduct, has led to a better understanding of the synergistic effects of both partners. The exclusive formation of sulfoxides by the hybrid biocatalyst, as opposed to sulfone in the case of the free inorganic complex, highlights the modulating role of the inorganic‐complex‐binding site in the protein.

     

In situ Raman spectroscopy: a process analytical technology tool to monitor a de-protection reaction carried out in aqueous solution

The application of in situ Raman spectroscopy at small scale (maximum 80 mL) during the development of a manufacturing process is disclosed. The reaction was run in aqueous solution between ambient and 100 °C. Raman spectroscopy has proven to be a viable method to track the reaction. Three distinct phases could be followed: dissolution of the starting material, production of a reactive intermediate, and then subsequent conversion of that intermediate to form product. The objective of the work was to confirm the presence of a reactive intermediate and this could only be carried out via in situ spectroscopy as the intermediate was known to be unstable. Toward the end, the reaction passes though several neutralization points and these are consistent with changes in the spectra. Comparison of data obtained at an illumination wavelength of 998 nm with that obtained at 785 nm is also disclosed. The data obtained at shorter wavelength was contaminated by reasonably strong fluorescence, whereas the data obtained at 998 nm was free of fluorescence. An unexpected observation from this work was that the reaction time was much shorter than expected and this work was key in showing that a reduction in batch cycle time was possible during commercial manufacture.     

Experimental validation of a simple approximation to determine the linewidth of a laser from its frequency noise spectrum

Laser frequency fluctuations can be characterized either comprehensively by the frequency noise spectrum or in a simple but incomplete manner by the laser linewidth. A formal relation exists to calculate the linewidth from the frequency noise spectrum, but it is laborious to apply in practice. We recently proposed a much simpler geometrical approximation applicable to any arbitrary frequency noise spectrum. Here we present an experimental validation of this approximation using laser sources of different spectral characteristics. For each of them, we measured both the frequency noise spectrum to calculate the approximate linewidth and the actual linewidth directly. We observe a very good agreement between the approximate and directly measured linewidths over a broad range of values (from kilohertz to megahertz) and for significantly different laser line shapes.     

Baby foods: formulations and interactions (a review)

Infant foods have a special place among food products mainly because of nutritional aspects and preparations methods. A great increase of baby foods incomes is predicted in near future. Formulation, handling, and storage of baby foods are important to keep nutritional quality and physicochemical properties of these foods. During storage some reactions and interactions occur which change physicochemical and nutritional properties of baby foods. Lactose crystallization, Maillard reaction, oxidation, and interactions between micronutrients and other components are the most important aspect of preparation and storage of baby foods. These reactions and interactions influence physical properties such as flowability of powder, solubility, and other functional properties. Controlling of storage conditions such as temperature and moisture content and oxygen quantity in headspace of product is required to keep product quality. In this paper the composition and interactions of baby foods between major components and their effect on nutritional quality of baby foods are explained.     

In vivo registration of both electrogoniometry and medical imaging: development and application on the ankle joint complex

An in vivo method for joint kinematics visualization and analysis is described. Low-dose computed tomography allowed three-dimensional joint modeling, and electrogoniometry collected joint kinematic data. Data registration occurred using palpated anatomical landmarks to obtain interactive computer joint simulation. The method was applied on one volunteer's ankle, and reproducibility was tested (maximal discrepancy: 3.6 deg and 5.5 mm for rotation and translation respectively).     

On Analytic Continuation of Solutions of Linear Partial Differential Equations

We study analytic continuation properties of solutions of linear partial differential equations of Cauchy–Kowalewski type, with respect to one complex variable in sectors of infinite radius. Growth estimates are also investigated. 2000 Mathematics Subject Classification. 35C10, 35C20.     

Landfill-stimulated iron reduction and arsenic release at the Coakley Superfund Site (NH)

Arsenic is a contaminant at more than one-third of all Superfund Sites in the United States. Frequently this contamination appearsto resultfrom geochemical processes rather than the presence of a well-defined arsenic source. Here we examine the geochemical processes that regulate arsenic levels at the Coakley Landfill Superfund Site (NH), a site contaminated with As, Cr, Pb, Ni, Zn, and aromatic hydrocarbons. Long-term field observations indicate that the concentrations of most of these contaminants have diminished as a result of treatment by monitored natural attenuation begun in 1998; however, dissolved arsenic levels increased modestly over the same interval. We attribute this increase to the reductive release of arsenic associated with poorly crystalline iron hydroxides within a glaciomarine clay layer within the overburden underlying the former landfill. Anaerobic batch incubations that stimulated iron reduction in the glaciomarine clay released appreciable dissolved arsenic and iron. Field observations also suggest that iron reduction associated with biodegradation of organic waste are partly responsible for arsenic release; over the five-year study period since a cap was emplaced to prevent water flow through the site, decreases in groundwater dissolved benzene concentrations at the landfill are correlated with increases in dissolved arsenic concentrations, consistent with the microbial decomposition of both benzene and other organics, and reduction of arsenic-bearing iron oxides. Treatment of contaminated groundwater increasingly is based on stimulating natural biogeochemical processes to degrade the contaminants. These results indicate that reducing environments created within organic contaminant plumes may release arsenic. In fact, the strong correlation (>80%) between elevated arsenic levels and organic contamination in groundwater systems at Superfund Sites across the United States suggests that arsenic contamination caused by natural degradation of organic contaminants may be widespread.