Highly enantioselective bioreduction of ethyl 3-oxohexanoate

Seven wild-type microorganism strains were used to reduce ethyl 3-oxohexanoate to ethyl (R)-3-hydroxyhexanoate. Free cells of Kluyveromyces marxianus and Aspergillus niger led to higher than 99% of conversion with higher than 99% ee. After immobilization in calcium alginate spheres, cells of K. marxianus exhibited high enantioselectivity (>99% ee) and conversion level (99%) within 24 h even if substrate was added at concentration of 10 g/L (62 mM).     

On a singular elliptic problem involving critical growth in {\mathbb{R}^{\bf N}}

In this paper, we prove a suitable Trudinger–Moser inequality with a singular weight in \mathbbR^N{\mathbb{R}^N} and as an application of this result, using the mountain-pass theorem we establish sufficient conditions for the existence of nontrivial solutions to quasilinear elliptic partial differential equations of the form

Noise rejection for two time-based multi-output modal analysis techniques

Modal analysis is a well-developed field with many applications. In particular, forced response multi-output approaches are well suited for system identification and online damage detection because they use the natural excitations the system undergoes during its normal operation. In this work, two of these approaches, smooth orthogonal decomposition (SOD) and direct system parameter identification (DSPI), are analyzed, compared, and improved upon. SOD was originally developed as a tool for detecting features of chaotic dynamical systems. Recently, it has been used as a time-based multi-output modal analysis approach. SOD has been demonstrated to work for the free vibration case and for random excitations. DSPI was developed as a time-based multi-input multi-output approach. When the inputs are not measured, DSPI is very similar to SOD and can handle both free vibrations and random excitations. However, if the inputs are measured or known DSPI can also handle arbitrary excitations. To improve the performance of these two methods when used with noisy data, novel noise filtering algorithms are proposed. Numerical simulations are performed to compare the two methods and to show the effectiveness of the filtering algorithms in improving frequency and mode shape extraction.     

Recurrence Theorem for Semigroup Actions

In this article the notion of Poincaré recurrence for semigroup actions is introduced. It recovers the well-known concept of recurrence in dynamical systems. The Poincaré recurrence theorem is extended from the setting of flows on metric spaces to the setting of semigroup actions on metric spaces. The results are applied to control systems and semigroups acting on fiber bundles.     

Computing confidence intervals for output-oriented DEA models: an application to agricultural research in Brazil

We define and model the research production at Embrapa, the major Brazilian institution responsible for applied agricultural research. The main theoretical framework is data envelopment analysis. We explore the economic interpretation and the statistical properties of these models to compute confidence intervals for output-oriented efficiency measurements. It was based on a parametric flexible model, defined by the truncated normal distribution. Intervals are calculated exploring a bootstrap approach. These results provide a better insight on the efficiency classification and allow comparisons among the decision making units involved in the evaluation process, taking into account random errors and inefficiency random variation.     

Role of spin-flip transitions in the anomalous Hall effect of FePt alloy

We carry out ab?initio calculations which demonstrate the importance of the non-spin-conserving part of the spin-orbit interaction for the intrinsic anomalous Hall conductivity of ordered FePt alloys. The impact of this interaction is strongly reduced if Pt is replaced by the lighter isoelectronic element Pd. An analysis of the interband transitions responsible for the anomalous velocity reveals that spin-flip transitions occur not only at avoided band crossings near the Fermi level, but also between well-separated pairs of bands with similar dispersions. We also predict a strong anisotropy in the anomalous Hall conductivity of FePt caused entirely by low-frequency spin-flip transitions.     

Emergence of atypical properties in assembled graphene nanoribbons

Graphitic nanowiggles (GNWs) are periodic repetitions of nonaligned finite-sized graphitic nanoribbon domains seamlessly stitched together without structural defects. These complex nanostructures have been recently fabricated [Cai et al., Nature (London) 466, 470 (2010)] and are here predicted to possess unusual properties, such as tunable band gaps and versatile magnetic behaviors. We used first-principles theory to highlight the microscopic origins of the emerging electronic and magnetic properties of the main subclasses of GNWs. Our study establishes a road map for guiding the design and synthesis of specific GNWs for nanoelectronic, optoelectronic, and spintronic applications.     

Solid solution formation, densification and ionic conductivity of Gd- and Sm-doped ceria

The processes of solid solution formation, densification and electrical conductivity in samaria and gadolinia-doped ceria solid electrolytes were studied by Raman spectroscopy, density and impedance spectroscopy measurements. Bulk specimens of Ce_0.9Gd_0.1O_1.95 and Ce_0.8Sm_0.2O_1.9 were prepared by solid state reactions at several dwell temperatures and holding times. Hydrostatic density results show a fast increase in sintered density up to 1 h holding time. Raman spectra of specimens sintered for 1 h show a prominent band at 463 cm^− 1 assigned to the cubic fluorite-type lattice of cerium oxide, and low-intensity bands at 344 and 363 cm^− 1 attributed to free samarium and gadolinium sesquioxides, respectively. Solid solution completion was achieved only at temperatures above 1400 °C. Electrical conductivity measurements were used to study mass transport. Analysis of impedance data allowed for determining the activation energy for cation diffusion in Ce_0.9Gd_0.1O_1.95 and Ce_0.8Sm_0.2O_1.9 sintered specimens.     

Defect chemistry of grain boundaries in proton-conducting solid oxides

The defect chemistry of charged grain boundaries in an acceptor-doped oxide in equilibrium with water vapour is examined theoretically. The basis of the theoretical approach is that the formation of charged grain boundaries and attendant space-charge zones is governed by differences in the standard chemical potentials of oxygen vacancies and hydroxide ions between bulk and grain-boundary core, that is, by the thermodynamic driving energies for defect redistribution. A one-dimensional continuum treatment is used to predict the space-charge potential and defect concentrations in the grain-boundary core as a function of water partial pressure, temperature and acceptor dopant concentration for various values of the two thermodynamic driving energies. The results are discussed with respect to experimental data in the literature for acceptor-doped perovskite oxides (e.g. BaZrO₃) and fluorite oxides (e.g. CeO₂).     

Bacterial Cellulose as Laryngeal Medialization Material: An Experimental Study

Hypothesis

The use of a material made of bacterial cellulose with the aim of obtaining vocal fold medialization has not hitherto been fully investigated. Although the material has been tested in other animal models, the evaluation did not include the larynx; hence, situations, such as tissue reaction, material absorption, and extrusion, need to be addressed to evaluate its usefulness as a material for laryngeal reconstruction.

Objective

To evaluate the medialization, tissue response, and healing of rabbit vocal folds, after the implantation of a membrane of bacterial cellulose.

Study Design

Experimental study.

Methods

A total of 32 rabbits were used, two of which were used to check out the adequacy of the implant location. The animals were followed for 4 months and grouped according to follow-up times of 2, 4, and 16 weeks. All test animals received an implant of bacterial cellulose in one vocal fold and the injection of distilled water in the other, both performed by videoendoscopic cervicotomy. At the end of the follow-up, the presence of inflammatory and medial displacement was evaluated.

Results

No statistically significant difference in the inflammatory parameters between the study and control vocal folds or among follow-up times was found. All animals receiving cellulose presented medial displacement of vocal folds, and all retained this material at the implant site up to study endpoint.

Conclusion

Bacterial cellulose is a useful material for laryngeal medialization, showing no signs of rejection or absorption.