Graphene Oxide: Surface Activity and Two‐Dimensional Assembly

Graphene oxide (GO) is a promising precursor for preparing graphene‐based composites and electronics applications. Like graphene, GO is essentially one‐atom thick but can be as wide as tens of micrometers, resulting in a unique type of material building block, characterized by two very different length scales. Due to this highly anisotropic structure, the collective material properties are highly dependent on how these sheets are assembled. Therefore, understanding and controlling the assembly behavior of GO has become an important subject of research. In this Research News article the surface activity of GO and how it can be employed to create two‐dimensional assemblies over large areas is discussed.     

Efficient phosphate binding using a combination of gluconolactate and carbonate calcium salts

Although renal-failure-related hyperphosphataemia can be corrected by various phosphate binders, there remains a need for safer and more efficient formulations to precipitate phosphate. This work describes both a theoretical approach and a phosphate precipitation test in order to design efficient binding calcium salts formulations. The results show that the combination of a soluble calcium salt (the gluconolactate) and a proton-consuming calcium salt (the carbonate) can precipitate phosphate effectively. Furthermore, the theoretical computations correlate well with the ability of the salt to bind phosphate in vitro.     

Processing of interfacial tension data in solvent extraction studies. Interfacial properties of various acidic organophosphorus extractants

Basically, the interfacial tension data can be plotted as a function of logarithm C where C denotes the concentration of any form of the surface active species considered. The various relationships y vs In C are discussed here from a mathematical point of view and it is shown that ambiguities may arise from the use of the interfacial tension curves versus the total extractant concentration for the interfacial tension data interpretation. The method recommended in this work is based on the computation of the whole surface excess curves (Γ vs concentration of individual species). This is achieved by matching various adsorption equations (e.g. Szyszkowski or Temkin relationships) or empirical equations to the interfacial tension data (y vs C). The term dy/dln C can then be analytically calculated and introduced into the Gibbs equation [Γ = ?(1/RT)dy/dln C] to derive mathematical expressions for the surface excess curves. To exemplify our approach, interfacial data are interpreted for dibutylphosphoric acid (HDBP), di(2-ethylhexyl)phosphoric acid (HDEHP), di(hexoxyethyl)phosphoric acid (HDHOEP), 2-ethylhexyl-2-ethylhexylphosphonic acid (HEH[EHP]) and di(2-ethylhexyl)phosphinic acid (H[DEHP]) at various liquid-liquid interfaces.     

Scattering from the perfectly conducting cube

The scattering cross sections in the E-plane, H-plane, and 45°-plane of the perfectly conducting cube illuminated broadside by an incident plane wave are computed using both a uniform high-frequency diffraction solution and magnetic-field integral equations. The computed cross sections are compared with measured cross sections for cube perimeters of 3, 6, 12, and 20 wavelengths. The total scattering cross section versus the perimeter of the cube is also computed and compared to that of the sphere     

A neural network-based method for tracking features from satellitesensor images

A new approach for feature tracking on sequential satellite sensor images using neural networks has been developed. The method defines the correspondence problem between features as the minimization of a cost function using a Hopfield neural network. It has been tested on Meteosat radiometer images by tracking a cloud with rotational movement and compared to the maximum cross-correlation method. The Hopfield net was found to be more accurate and faster.     

Efficiently detecting switches against non-stationary opponents

Interactions in multiagent systems are generally more complicated than single agent ones. Game theory provides solutions on how to act in multiagent scenarios; however, it assumes that all agents will act rationally. Moreover, some works also assume the opponent will use a stationary strategy. These assumptions usually do not hold in real world scenarios where agents have limited capacities and may deviate from a perfect rational response. Our goal is still to act optimally in these cases by learning the appropriate response and without any prior policies on how to act. Thus, we focus on the problem when another agent in the environment uses different stationary strategies over time. This will turn the problem into learning in a non-stationary environment, posing a problem for most learning algorithms. This paper introduces DriftER, an algorithm that (1) learns a model of the opponent, (2) uses that to obtain an optimal policy and then (3) determines when it must re-learn due to an opponent strategy change. We provide theoretical results showing that DriftER guarantees to detect switches with high probability. Also, we provide empirical results showing that our approach outperforms state of the art algorithms, in normal form games such as prisoner’s dilemma and then in a more realistic scenario, the Power TAC simulator.     

Evaluation of musculoskeletal health outcomes in the context of job rotation and multifunctional jobs

Higher physical demands at work are associated with health outcomes such as discomfort, disorders and sick leave. Variations in work exposure patterns, introduced by multifunctional jobs and ergonomic interventions, bring confounders into the complex relation between occupational risks and musculoskeletal disorders. This study compared whole-body rating of perceived exertion (RPE), discomfort, ergonomic workplace analysis (EWA) and sick leave due to musculoskeletal disorders, among workers exposed to diversified work. The results showed that EWA performed by the observer differed from workers' ratings. There were no differences between groups of workers taking or not taking sick leave regarding RPE and discomfort at their current workstations. Workers significantly discriminated between progressive workload levels, and RPE scores for specific tasks were nonlinear during shifts. These differences might be associated with exposure variability. Thus, in the context of diversified work, the RPE scale seems more appropriate for evaluating acute effects of work variability.     

Optimal mode selection and synchronization for robust videocommunications over error-prone networks

We describe an effective method for increasing error resilience of video transmission over bit error prone networks. Rate-distortion optimized mode selection and synchronization marker insertion algorithms are introduced. The resulting video communication system takes into account the channel condition and the error concealment method used by the decoder, to optimize video coding mode selection and placement of synchronization markers in the compressed bit stream. The effects of mismatch between the parameters used by the encoder and the parameters associated with the actual channel condition and the decoder error concealment method are evaluated. Results for the binary symmetric channel and wideband code division multiple access mobile network models are presented in order to illustrate the advantages of the proposed method