Depth‐Resolved Modulation of Metal–Oxygen Hybridization and Orbital Polarization across Correlated Oxide Interfaces

Interface‐induced modifications of the electronic, magnetic, and lattice degrees of freedom drive an array of novel physical properties in oxide heterostructures. Here, large changes in metal–oxygen band hybridization, as measured in the oxygen ligand hole density, are induced as a result of interfacing two isovalent correlated oxides. Using resonant X‐ray reflectivity, a superlattice of SrFeO₃ and CaFeO₃ is shown to exhibit an electronic character that spatially evolves from strongly O‐like in SrFeO₃ to strongly Fe‐like in CaFeO₃. This alternating degree of Fe electronic character is correlated with a modulation of an Fe 3d orbital polarization, giving rise to an orbital superstructure. At the SrFeO₃/CaFeO₃ interfaces, the ligand hole density and orbital polarization reconstruct in a single unit cell of CaFeO₃, demonstrating how the mismatch in these electronic parameters is accommodated at the interface. These results provide new insight into how the orbital character of electrons is altered by correlated oxide interfaces and lays out a broadly applicable approach for depth‐resolving band hybridization.     

Digital signature to help network management using flow analysis

Because of constant growth in proportion and complexity of networks, flow analysis has become an indispensable tool for network management mechanisms. Through this resource, a traffic characterization, called digital signature of network segment using flow analysis (DSNSF), is accomplished. The models used for this purpose are the ant colony optimization metaheuristic, the Holt–Winters forecasting method and the statistical procedure, principal component analysis. The obtained DSNSF by each model is compared with the actual traffic of packets and bits and then subjected to specific evaluations in order to measure its accuracy. The experimental results show that the three methods could achieve good correlation indices and low normalized mean square error values between the DSNSF curve and the real traffic movement, indicating a good adaptability and efficiency in characterizing a network traffic segment. Copyright © 2015 John Wiley & Sons, Ltd.     

Conical and biconical ultra-high-Q optical-fiber nanowire microcoil resonator

New 3D geometries of the optical nanowire microcoil resonator are suggested and investigated theoretically. The dependence of the Q factor on coupling parameters is calculated and compared for three different profiles. Results suggest that ultra-high-Q resonators can be fabricated more easily when the nanowire microcoil resonator has a biconical profile.     

Rheological behavior of anionic collagen injectable gels in the presence of rhamsan for plastic surgery applications

The present paper describes the rheological properties of anionic collagen gels and anionic collagen:rhamsan composites gels in the concentration of 0.7, 4 and 6%, estimated to be used as injectable biomaterials for plastic reconstruction. Rheological studies of these gels showed that independently of pH, composition and concentration the viscoelastic behavior was dependent on the frequency, with the storage modulus always greater than the loss modulus (G′ > G″ and δ < 45°). Creep experiments showed that anionic collagen:rhamsan composites equilibrated at pH 7.4 were less elastic and more susceptible to deformation in comparison to gels equilibrated at pH 3.5. Flow experiments indicated that the force needed for the extrusion of anionic collagen:rhamsan composites, in comparison to anionic collagen, was significantly smaller and with a smoother flow, suggesting the association with rhamsan may be a good alternative in the replacement of glutaraldehyde to stabilize the microfibril assembly of commercial collagen gel preparations. Finally, on the basis of dynamic viscosity profiles found for different preparations, some of these composites are potential candidates to be utilized in laryngology.     

Thermodynamics of coherently-strained GexSi1-x nanocrystals on Si(001): alloy composition and island formation

We determined the enthalpic and entropic contributions to the thermodynamics of coherently strained nanocrystals grown via deposition of pure Ge on Si(001) surfaces at 600 and 700 degrees C by analyzing their composition profile and local strain. We found that the free energy associated with the entropy of mixing, which drives GexSi1-x alloy formation, was significantly larger than the relaxation enthalpy that produces the islands. Thus, entropy plays a significant role in the evolution of the size and shape of the islands during growth through the strong thermodynamic drive to form an alloy.     

Effect of rotor–tower interaction,tilt angle,and yaw misalignment on the aeroelasticity of a large horizontal axis wind turbine with composite blades

This paper presents a detailed analysis of the rotor–tower interaction and the effects of the rotor's tilt angle and yaw misalignment on a large horizontal axis wind turbine. A high‐fidelity aeroelastic model is employed, coupling computational fluid dynamics (CFD) and structural mechanics (CSM). The wind velocity stratification induced by the atmospheric boundary layer (ABL) is modeled. On the CSM side, the complex composite structure of each blade is accurately modeled using shell elements. The rotor–tower interaction is analyzed by comparing results of a rotor‐only simulation and a full‐machine simulation, observing a sudden drop in loads, deformations, and power production of each blade, when passing in front of the tower. Subsequently, a tilt angle is introduced on the rotor, and its effect on blade displacements, loads, and performance is studied, representing a novelty with respect to the available literature. The tilt angle leads to a different contribution of gravity to the blade deformations, sensibly affecting the stresses in the composite material. Lastly, a yaw misalignment is introduced with respect to the incoming wind, and the resulting changes in the blade solicitations are analyzed. In particular, a reduction of the blade axial displacement amplitude during each revolution is observed.     

Comparison of acid and amyloglucosidase hydrolysis for estimation of non‐structural polysaccharides in feed samples

Enzymatic methods (amyloglucosidase) and methods based on acid solutions (0.1, 0.2 and 0.3 M H₂SO₄ for 1, 2 and 3 h at 100 °C) for the hydrolysis of non‐structural carbohydrates from different feed samples were compared. The monomeric units resulting from the enzymatic and acid hydrolysis were determined by the glucose oxidase and reducing sugar methods. There was a significant effect of acid concentration and of time of hydrolysis on the glucose and reducing sugar values in the hydrolysate. Glucose values were similar for both the amyloglucosidase method and the most intense conditions of hydrolysis (0.3 M for 3 h) for some samples. Under these conditions, however, the reducing sugar values were higher. No acid hydrolysis method was found to estimate correctly the total non‐structural carbohydrates, but α‐linked glucose polymers in biological samples may be determined by sample hydrolysis with a 0.3 M H₂SO₄ solution for 3 h at 100 °C since the glucose in the hydrolysate is determined by the glucose oxidase method and the sucrose content of the sample is negligible. © 1999 Society of Chemical Industry     

Functional properties and health benefits of bioactive peptides derived from Spirulina: A review

Bioactive peptides represent specific sequences of amino acids that have biological activity with several health effects and potential applications, which can be obtained from diverse protein sources. Spirulina, the cyanobacterium known for its high protein content and therapeutic properties, has been investigated as a potential source of bioactive peptides. Some bioactive peptides derived from Spirulina are under study for their ability to offer specific health benefits, such as antimicrobial, antiallergic, antihypertensive, antitumor, and immunomodulatory properties. Bioactive peptide fractions from Spirulina biomass can be obtained through a series of operations, including cell lysis and protein extraction, enzymatic hydrolysis, potential bioactivity screening, fractionation, and purification. Potentially, Spirulina-derived peptide fractions can be applied as nutraceutical ingredients in foods and pharmaceuticals. This article reviews the functional properties and health benefits of bioactive peptides from Spirulina, and presents potential mechanisms by which bioactive components can be exploited in the development of novel foods with special health claims. In addition, this article describes recent developments in proteomics, bioactivity screening methods, and opportunities for designing future peptide-based foods.     

Assessment of variance components in nonlinear mixed-effects elliptical models

The issue of assessing variance components is essential in deciding on the inclusion of random effects in the context of mixed models. In this work we discuss this problem by supposing nonlinear elliptical models for correlated data by using the score-type test proposed in Silvapulle and Silvapulle (1995). Being asymptotically equivalent to the likelihood ratio test and only requiring the estimation under the null hypothesis, this test provides a fairly easy computable alternative for assessing one-sided hypotheses in the context of the marginal model. Taking into account the possible non-normal distribution, we assume that the joint distribution of the response variable and the random effects lies in the elliptical class, which includes light-tailed and heavy-tailed distributions such as Student-t, power exponential, logistic, generalized Student-t, generalized logistic, contaminated normal, and the normal itself, among others. We compare the sensitivity of the score-type test under normal, Student-t and power exponential models for the kinetics data set discussed in Vonesh and Carter (1992) and fitted using the model presented in Russo et al. (2009). Also, a simulation study is performed to analyze the consequences of the kurtosis misspecification.     

Energy efficiency standards for refrigerators in Brazil: A methodology for impact evaluation

In Brazil energy efficiency standards for cold appliances was established in 2007. A specified single set of MEPS (minimum energy performance standards) for refrigerators, freezers and freezer refrigerators was implemented without evaluating its impacts and estimation of potential electricity savings. This paper presents a methodology for assessing the impacts of the Brazilian MEPS for cold appliances. It uses a bottom-up approach to estimate residential end-use consumption and to evaluate the energy saving potential for refrigerators. The household electricity consumption is projected by modeling appliance ownership using an econometric approach based on the recent household survey data. A cost–benefit analysis for more stringent standards is presented from the perspective of the society and electricity customers. The results showed that even considering the current market conditions (high discount rate for financing new efficient equipment) some MEPS options are advantageous for customers. The analysis also demonstrates significant cost-effective saving potential from the society perspective that could reach 21 TWh throughout the period of 2010–2030—about 25% of current residential consumption.