Voltage‐Induced Coercivity Reduction in Nanoporous Alloy Films: A Boost toward Energy‐Efficient Magnetic Actuation

Magnetic data storage and magnetically actuated devices are conventionally controlled by magnetic fields generated using electric currents. This involves significant power dissipation by Joule heating effect. To optimize energy efficiency, manipulation of magnetic information with lower magnetic fields (i.e., lower electric currents) is desirable. This can be accomplished by reducing the coercivity of the actuated material. Here, a drastic reduction of coercivity is observed at room temperature in thick (≈600 nm), nanoporous, electrodeposited Cu–Ni films by simply subjecting them to the action of an electric field. The effect is due to voltage‐induced changes in the magnetic anisotropy. The large surface‐area‐to‐volume ratio and the ultranarrow pore walls of the system allow the whole film, and not only the topmost surface, to effectively contribute to the observed magnetoelectric effect. This waives the stringent “ultrathin‐film requirement” from previous studies, where small voltage‐driven coercivity variations were reported. This observation expands the already wide range of applications of nanoporous materials (hitherto in areas like energy storage or catalysis) and it opens new paradigms in the fields of spintronics, computation, and magnetic actuation in general.     

Parameter estimation in time-triggered and event-triggered model-based control of uncertain systems

In this article on-line parameter estimation of dynamical systems is addressed in the context of model-based networked control systems (MB-NCSs). Stability conditions that are robust to parameter uncertainties and lack of feedback for extended intervals of time are presented. The updated model is used to control the real system the next time feedback information is unavailable. Additionally, new estimation models are proposed that offer better convergence properties than typical state-space parameter estimation methods; common assumptions such as availability of persistently exciting inputs and estimation of only a canonical form of the system are relaxed. The implementation of upgraded models in MB-NCSs results in better usage of the network by allowing longer intervals without the need for measurement updates.     

The influence of dietaryβ-carboline alkaloids on growth rate,food consumption,and food utilization of larvae ofSpodoptera exigua (Hubner)

-Carboline alkaloids are found worldwide in many plant families. Harman, harmine, and other simple -carboline alkaloids were tested for activity against a generalist phytophagous insect, the beet army worm [Spodoptera exigua (Hubner)]. Chronic dietary exposure tests (neonate to pupa) reveal potent antifeedant and possible toxic effects. Acute dietary exposure tests on fifth-instar larvae also demonstrate antifeedant activity.     

Prediction of gas hold-up and liquid velocity in airlift reactors using two-phase flow friction coefficients

The overall friction coefficient (K_f) of airlift reactors was estimated using equivalent lengths (L_eq) and friction factors ( f ). The friction factor was calculated taking into account the riser liquid velocity profile corresponding to the two-phase flow and using classical one-phase equations. A previously described model was used to obtain simultaneously both gas hold-up and liquid circulation velocity. The model simulates experimental data obtained in a wide range of configurations of internal (2 and 30 dm³ volume) and external (from 8 to 600 dm³ volume) airlift reactors with Newtonian (water and alcohol solutions) and non-Newtonian (carboxymethylcellulose (CMC) solutions) systems. Com-parison with other models from the literature yielded similar results.     

On‐Chip Self‐Assembly of a Smart Hybrid Nanocomposite for Antitumoral Applications

A hybrid nanocomposite comprised by porous silicon nanoparticles and a stimuli responsive polymeric material, polyethylene glycol‐block‐poly(L‐histidine), is spontaneously formed by nanoprecipitation in a flow‐focusing microfluidic chip. The nanocomposite presents a novel hybrid compound micelle structure with a great robustness for therapeutic applications. Therefore, the nanocomposite is developed and tested as a “smart” multistage drug delivery system (MDDS) in response to some of the current problems that cancer treatment presents. Based on the stimuli‐responsive behavior of the nanocomposite, a chemotherapeutic agent is successfully loaded into the nanosystem and released upon changes in the pH‐values. The nanocomposite demonstrates enhanced stability in plasma, narrow size distribution, improved surface smoothness, and high cytocompatibility. Furthermore, the nanocomposite presents reduced nanoparticle internalization by phagocytic macrophage cells and pH‐dependent cell growth inhibition capacity. Overall, the developed hybrid nanocomposite shows very promising features for its further development as a “smart” pH‐responsive MDDS.     

Applications of the multidimensional equations to complex fuel assembly problems

For the analysis of reactors with complex fuel assemblies or fine mesh applications as pin by pin neutron flux reconstruction, the usual approximation of the neutron transport equation by the multigroup diffusion equation does not provide good results. A classical approach to solve the neutron transport equation is to apply the spherical harmonics method obtaining a finite approximation known as the P_L equations. In this line, a nodal collocation method for the discretization of these equations on a rectangular mesh is used in this paper to analyse reactors with MOX fuel assemblies. Although the 3D P_L nodal collocation method becomes feasible due to the improvements in computer hardware, a complete treatment of the detailed structure of the fuel assemblies in actual three-dimensional geometry is still prohibitive, thus, an assembly homogenization method is necessary. A homogenization method compatible with our multidimensional P_L code is proposed and tested performing heterogeneous and homogenized calculations. In this work, we apply the method to 2D complex fuel assembly configurations.     

Tunable Magnetism in Nanoporous CuNi Alloys by Reversible Voltage‐Driven Element‐Selective Redox Processes

Voltage‐driven manipulation of magnetism in electrodeposited 200 nm thick nanoporous single‐phase solid solution Cu₂₀Ni₈₀ (at%) alloy films (with sub 10 nm pore size) is accomplished by controlled reduction‐oxidation (i.e., redox) processes in a protic solvent, namely 1 m NaOH aqueous solution. Owing to the selectivity of the electrochemical processes, the oxidation of the CuNi film mainly occurs on the Cu counterpart of the solid solution, resulting in a Ni‐enriched alloy. As a consequence, the magnetic moment at saturation significantly increases (up to 33% enhancement with respect to the as‐prepared sample), while only slight changes in coercivity are observed. Conversely, the reduction process brings Cu back to its metallic state and, remarkably, it becomes alloyed to Ni again. The reported phenomenon is fully reversible, thus allowing for the precise adjustment of the magnetic properties of this system through the sign and amplitude of the applied voltage.     

Use of clay-based construction and demolition waste as additions in the design of new low and very low heat of hydration cements

In light of the large amounts of cement used in plain concrete and given the exothermal reactions involved in its hydration, the control and assessment of heat of hydration are instrumental to prevent future shortcomings in structural durability. This article describes the design of new eco-efficient cements containing different percentages of fired clay-based construction and demolition waste (CC&DW). The new cements (CCDWC) were characterised for pozzolanicity and their heat of hydration was assessed based on a semi-adiabatic method described in European standards. The inclusion of CC&DW retarded the heating of mortar and lowered its maximum temperatures, more significantly with the increase of replacement ratios. The design of such CC&DW-bearing low and very low heat of hydration cements may well prompt the introduction of new applications of bulk cement or cement-high mixes, in which heat may have adverse effects on durability.     

Analysis of pressure signals using a Singular System Analysis (SSA) methodology

Pressure signals are used for control and monitoring the safety in nuclear power plants. These pressure transmitters are tested periodically. In particular, we are only interested in the transmitters checked to analyse the response times. The noise analysis is a very efficient tool to obtain adequate response times, but although this method can produce accurate results if performed properly, inherent problems in the tests can produce invalid results, for example if the test signal is oscillatory. An approach to remove the oscillatory contamination contribution from the pressure transmitter signal is the Singular Spectrum Analysis (SSA). This method is based on the fact that the dynamics associated with the signal can be described statistically in a linear way by its principal axes.

Many or most directions in the embedding space can be associated with noise and typically a small number of these principal directions can explain the main dynamic characteristics of the signal; these principal directions are related with the singular values of the correlation matrix signal.

This methodology has been applied successfully to several pressure signals of a typical Pressurized Water Reactor which show an oscillatory contribution of 0.6 Hz. The SSA method removes this oscillatory contamination very efficiently.