Influence of heat-treatment environment on Ni-ferrite nanoparticle formation from coconut water precursor

The kinetics of formation of NiFe₂O₄ nanoparticles were investigated where the nanoparticles were produced by the proteic-sol–gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe₂O₄ nanoparticles in a superparamagnetic state as determined from Mössbauer spectroscopy. In general, heat treatment at high temperature leads to a nanocomposite rich in NiFe₂O₄. In air, annealing at 1173 K for 8 h favored the formation of the magnetically ordered NiFe₂O₄ inverse spinel structure, with bulk characteristics and average crystal sizes of approximately 66 nm. In a nitrogen atmosphere and in compacted BN powder under air atmosphere, the NiFe₂O₄ spinel structure stabilized for temperatures up to 873 and 773 K, respectively, however, decomposition of the NiFe₂O₄ phase into other undesired structures was observed above 873 K.     

Environmental performance assessment of a provider of logistical services in an industrial supply chain

This paper presents a method for assessing environmental performance in industrial operations. The method was applied to three logistical operations in an industrial supply chain performed by a single operator: road transportation, warehousing, and urban transportation. Environmental performance was treated as a complex object and was structured according to the following five criteria: atmospheric emissions, liquid effluents, solid waste, natural and energy resources, and managerial and legal regulations. The first four criteria address a direct impact on the environment, whereas the last is a necessary condition for the first four to have a satisfactory performance. Six experts in environmental management prioritized the criteria and defined sets of indicators for the field appraisal. The indicators were expected to be correlated for the same criteria. The validity of the indicators was assessed through questionnaires answered by six managers of the operation. Finally, three overall indices corresponding to the environmental performance of the three logistical operations were calculated for the operations and were found to be 73.58, 79.21, and 76.28% (higher is better). These indicate good results because the maximum performance is expected to be 100%. This environmental performance assessment can aid in reformulating the environmental strategies embedded in the operational strategy of the company.     

Estimating the upcrossings index

For stationary sequences, under general dependence restrictions, any limiting point process for time normalized upcrossings of high levels is a compound Poisson process, i.e., there is a clustering of high upcrossings, where the underlying Poisson points represent cluster positions and the multiplicities correspond to cluster sizes. For such classes of stationary sequences, there exists the upcrossings index η, 0≤η≤1, which is directly related to the extremal index θ, 0≤θ≤1, for suitable high levels. In this paper, we consider the problem of estimating the upcrossings index η for a class of stationary sequences satisfying a mild oscillation restriction. For the proposed estimator, properties such as consistency and asymptotic normality are studied. Finally, the performance of the estimator is assessed through simulation studies for autoregressive processes and case studies in the fields of environment and finance. Comparisons with other estimators derived from well known estimators of the extremal index are also presented.     

RF integrated inductor modeling and its application to optimization-based design

In this paper an optimization-based approach for the design of RF integrated inductors is addressed. For the characterisation of the inductor behaviour the double ??-model is used. The use of this model is twofold. On one hand it enables the generation of the inductor characterisation in a few seconds. On the other hand its integration into the optimization procedure is straightforward. For the evaluation of the model element values analytical expressions based on technology parameters as well as on the device geometric characteristics are used. The use of a technology-based methodology for the evaluation of the model parameters grants the adaptability of the model to any technology. The inductor analytical characterization is integrated into an optimization-based tool for the automatic design of RF integrated inductors. This tool uses a modified genetic algorithm (MGA) optimization procedure, which has proved its validation in previous work. Due to the design parameter constraints nature as well as the topology constraints, discrete variables optimization techniques are used. The accuracy of the results is checked against a non-commercial software.     

On the regional incidence of highway investments in the USA

The objective of this paper was to investigate the regional incidence of the aggregate effects of investment in highways in the US taking into consideration the presence of regional spillovers. The empirical results are based on VAR estimates at both the aggregate and state levels using output, employment, and investment, as well as different measures of highway investments. Empirical results allow us to establish several stylized facts. First, investment in highways affects private sector variables positively at the aggregate level as well as in most states. Second, the regional spillover effects are very significant for all private sector variables. Third, these spillovers have a clear geographical pattern in that they tend to be more important in western states and the corridor between the Great Lakes and the Gulf Coast.     

Modification of coconut fibers with polyaniline for manufacture of pressure‐sensitive devices

This article studies the modification of coconut fibers with polyaniline (PAni) with help of statistical experimental design techniques. The main factors studied here were the techniques used for particle dispersion (sonication vs. magnetic stirring) and the type of initiator (ammonium persulfate, APS, vs. ammonium cerium sulfate dihydrate, Ce(IV)). The obtained materials were characterized through low field nuclear magnetic resonance, small‐and wide‐angle X‐ray scattering, scanning electron microscopy, fourier transform infrared spectroscopy, and ultraviolet–visible spectroscopy. Additionally, the electrical resistivities and respective sensitivities to variations of the applied pressure were evaluated for all obtained samples, with help of standard volume resistivity measurements and electro‐mechanical tests. The materials prepared through magnetic stirring with APS presented the best electrical and electromechanical properties, although materials prepared through sonication with Ce(IV) also presented good electrical and electromechanical properties and could be prepared much faster. As a consequence, modification of coconut fibers with PAni, using sonication as the particle dispersion technique and Ce(IV) as initiator, constitutes a very promising procedure for manufacture of pressure‐sensitive devices. POLYM. ENG. SCI., 54:2887–2895, 2014. © 2014 Society of Plastics Engineers     

Nanosized dispersions based on chitosan and NaPSS

Interpolyelectrolyte complexes (IPECs) were obtained by the solution mixing method from chitosan and poly(sodium 4-styrenesulfonate), NaPSS. XRD, FTIR spectroscopy, and thermogravimetric analysis indicated that IPEC formation inhibits the occurrence of crystalline regions in the resultant solid IPECs. Turbidimetry, viscometry, conductometry, and zeta potential measurements showed that at a sulfonate to aminium molar ratio = 1, the process of IPEC production is optimum. Average hydrodynamic diameters, calculated from DLS measurements, showed that IPEC formation occurs in two stages: first there is a decrease in macromolecular dimensions, as sulfonate to aminium molar ratio is increased. At a characteristic sulfonate to aminium molar ratio, soluble IPEC structures collapse to form phase segregated clusters that begin to nucleate the formation of larger, insoluble, IPEC particles.