Superparamagnetic polyvinylpyrrolidone/chitosan/Fe3O4 electrospun nanofibers as effective U(VI) adsorbents

Magnetoactive electrospun fibrous membranes consisting of polyvinylpyrrolidone (PVP), chitosan (CS) and pre-fabricated, double-layer oleic acid-coated magnetite nanoparticles (OA.OA.Fe₃O₄) were fabricated and evaluated as new adsorbent materials for the removal and recovery of uranium (U(VI)) from aqueous solutions. The adsorption has been investigated by batch-type experiments and the solid material has been characterized by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy/energy dispersive X-ray analysis (TEM/EDX) and vibration sample magnetometry (VSM) measurements prior and after uranium adsorption. The experimental adsorption data were found to be well fitted with the Langmuir isotherm and the pseudo-second order kinetic model. The results indicate that PVP/CS/OA.OA.Fe₃O₄ fibrous adsorbents exhibit good adsorption properties towards U(VI) in aqueous solutions, achieving a q_max value of 0.77 mol kg⁻¹ (183.3 mg g⁻¹) at pH 6.0. The experiments regarding the regeneration and reuse of the magnetoactive adsorbents were carried out using Na₂CO₃, at pH ~11. After four cycles, the percentage relative adsorption remained stable (~100%) whereas the desorption percentage decreased from 31.9% to 21.0%. Generally, the presented results demonstrate that the incorporation of the Fe₃O₄ NPs has a positive effect on the adsorption efficiency of U(VI) from aquatic environments.     

Active time scheduling for rechargeable sensor networks

Recent progress in energy harvesting technologies made it possible to build sensor networks with rechargeable nodes which target an indefinitely long operation. In these networks, the goal of energy management is to allocate the available energy such that the important performance metrics, such as the number of detected threats, are maximized. As the harvested energy is not sufficient for continuous operation, the scheduling of the active and inactive time is one of the main components of energy management. The active time scheduling protocols need to maintain the energy equilibrium of the nodes, while considering the uncertainties of the energy income, which is strongly influenced by the weather, and the energy expenditures, which are dependent on the behavior of the targets. In this paper, we describe and experimentally compare three active time scheduling protocols: (a) static active time, (b) dynamic active time based on a multi-parameter heuristic and (c) utility-based uniform sensing. We show that protocols which take into consideration the probabilistic models of the energy income and expenditure and can dynamically adapt to changes in the environment, can provide a significant performance advantage.     

The effect of co-encapsulation of Lactobacillus rhamnosus GG ATCC 53103 with inulin on alginate/chitosan matrix: the viability in fermented soy blend and simulated digestive system

This research verified the ability of Lactobacillus rhamnosus encapsulated with inulin to tolerate the simulated digestive system and their viability in a soy blend. Probiotic encapsulated in alginate-chitosan matrix without inulin presented a better encapsulation efficiency (80.92%) than encapsulation with inulin (57.39%). On the 28th day, the count of probiotics decreased by 3.42 and 1.99 logarithmic cycles of free and encapsulated cells without inulin, respectively. In contrast, the microorganisms encapsulated with inulin showed an increase of 1.26 logs CFU g⁻¹. During gastrointestinal simulation, cell counts decreased by 0.78, 1.55 and 1.95 CFU g⁻¹ logs for encapsulated cells without inulin, free and encapsulated with inulin, respectively. Sensory panellists liked the fermented soy blend with encapsulated lactobacilli, and this result shows the possibility to create new probiotic foods of plant origin. Therefore, the alginate/chitosan matrix can be considered adequate for the encapsulation of L. rhamnosus. The inulin reduces the encapsulation efficiency and increases the cell loss in gastrointestinal simulation. Considering cellular losses, the best option for preparing a fermented soy blend is to use L. rhamnosus encapsulated without inulin.     

Direct and Simultaneous Determination of Several Impurity Elements in Manganese Tetroxide using ICP-AES

1 IntroductionManganic mine resource is Chinese particular re-source,only fewcountries have manganic mine resourceinthe world. Manganese tetroxide whichis made of puremanganese is an important high-tech product that hasbeenregarded as a kind of combat readiness material inseveral countries[1 ,2]. Manganese tetroxide with a highpure and high specific surface area has been ranked inproject of high tech industrialization with preferential de-velopment andsupportinspecial purpose electron material…     

Changes in optical properties caused by UV-irradiation of aquatic humic substances from the amazon river basin: seasonal variability evaluation

Aquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winter and summer corresponding to floody and dry periods, were structurally characterized by 13C nuclear magnetic ressonance. Subsequently, AHS aqueous solutions were irradiated with a polychromatic lamp (290-475 nm) and monitored by its total organic carbon (TOC) content, ultraviolet-visible (UV-vis) absorbance, fluorescence, and Fourier transformed infrared spectroscopy (FTIR). As a result, a photobleaching up to 80% after irradiation of 48 h was observed. Conformational rearrangements and formation of low molecular complexity structures were formed during the irradiation, as deduced from the pH decrement and the fluorescence shifting to lower wavelengths. Additionally a significant mineralization with the formation of CO2, CO, and inorganic carbon compounds was registered, as assumed by TOC losses of up to 70%. The differences in photodegradation between samples expressed by photobleaching efficiency were enhanced in the summer sample and related to its elevated aromatic content. Aromatic structures are assumed to have high autosensitization capacity effects mediated by the free radical generation from quinone and phenolic moieties.     

Waste from brewing (trub) as a source of protein for the food industry

The use of agro-industrial waste for food enrichment can be limited, due to taste, odour, colour and other unpleasant characteristics. Trub (brewing waste) has important nutrients, such as proteins and carbohydrates, and phytochemical compounds; however, its applications are hindered by the astringent flavour. In order to reduce the bitterness of trub, aqueous extractions were realized at high temperature (100 °C per 1 h) in five steps. Two fractions were obtained; a liquid fraction (containing bitter compounds) and a solid fraction (the trub after the extraction process; TAP). Both fractions and the trub before the extraction process (TBP) were evaluated. The bitterness of TBP was significantly reduced in TAP while the protein content increased; TAP presented a branched network and changes in its structure. The reduction in bitterness and the high protein content allows the use of trub in the food industry.     

Time-parallel simulation of wireless ad hoc networks

In this paper, we study time-parallel simulation of wireless networks based upon the concept of the perturbation induced by a networking event and present a layer-by-layer analysis of the impact of perturbations on the wireless network. This analysis allows us to propose several methods to improve the accuracy of time-parallel simulation. We describe an implementation based on the widely used ns-2 simulator and on the iterative extension of the warmup period. We introduce a method for initial state approximation which can improve the accuracy of the simulation for table-driven ad hoc routing protocols. A series of experiments show that on typical scenarios time-parallel simulation leads to a significant speedup while maintaining a high level of accuracy.     

Analysis of Large Complex Structures With the Synthetic-Functions Approach

An innovative procedure is presented that allows the method of moments (MoM) analysis of large and complex antenna and scattering problems at a reduced memory and CPU cost, bounded within the resources provided by a standard (32 bit) personal computer. The method is based on the separation of the overall geometry into smaller portions, called blocks, and on the degrees of freedom of the field. The blocks need not be electrically unconnected. On each block, basis functions are generated with support on the entire block, that are subsequently used as basis functions for the analysis of the complete structure. Only a small number of these functions is required to obtain an accurate solution; therefore, the overall number of unknowns is drastically reduced with consequent impact on storage and solution time. These entire-domain basis functions are called synthetic functions; they are generated from the solution of the electromagnetic problem for the block in isolation, under excitation by suitably defined sources. The synthetic functions are obtained from the responses to all sources via a procedure based on the singular-value decomposition. Because of the strong reduction of the global number of unknowns, one can store the MoM matrix and afford a direct solution. The method is kernel-free, and can be implemented on existing MoM codes.     

Multiresolution analysis of printed antennas and circuits: adual-isoscalar approach

A new approach is presented for the integral equation analysis of multilayer printed circuits, antennas and arrays. It is based on the introduction of new multiresolution vector functions with properties similar to those of the scalar wavelets, and flexible enough to accommodate for general shapes. The resulting method of moments (MoM) impedance matrix shows a good conditioning, that allows its safe sparsification and the efficient use of iterative methods for the solution of the linear system. The results of the analysis of various real-life structures show the advantage of the method     

Analysis of the inducer-responsive CAR1 upstream activation sequence (UASI) and the factors required for its operation

Induced production of arginase (CAR1) enzyme activity and steady-state CAR1 mRNA in Saccharomyces cerevisiae requires wild-type ARG80/ARGRI and ARG81/ARGRII gene products. We demonstrate here that these gene products, along with that of the MCM1 gene, are required for the inducer-dependent UAS_I-A, UAS_I-B and UAS_I-C elements to function but they are not required for operation of inducer-independent CAR1 UAS_C1 or UAS_C2M. Through the use of single and multiple point mutations, the CAR1 UAS_I-B and UAS_I-C elements were demonstrated to be at least 23 bp in length. Moreover, simultaneous mutation of both ends of an elements gave stronger phenotypes than mutations at either end. The center of the element was more sensitive to mutation than were the ends.