Coupling of electrodialysis and leaching processes for removing of cadmium from phosphate ore

Phosphate rock is a valuable material that is used for the production of large phosphorus chemicals. However, this natural material usually contains some toxic elements such as cadmium (Cd). Cd is a non-nutritive metal regarded as harmful to both humans and the environment. The main toxic effects of Cd on human health are the kidney and renal cortex diseases. Other effects were observed on pulmonary, cardiovascular, and musculoskeletal systems, in addition to including Cd as a human carcinogen. In order to reduce the cadmium content in the phosphate ore, an original method was studied and consists of coupling both leaching and electrodialysis. The effects of process parameters, such as reaction time, nature, and concentration of the extracting agent, liquid/phosphate ore ratio, pH, temperature, and current density, were investigated. The obtained results show that the cadmium extraction from phosphate ore using simple batch leaching does not reduce the cadmium content to the required level. However, the application of leaching- electrodialysis coupled method at optimum current density of 10 mA cm^?2 increases the cadmium extraction efficiency up to 84.3%. This synergetic process could be applied to the treatment of phosphate ore containing cadmium.     

A cooperative architecture for target localization using multiple AUVs

A recent concern in marine robotics is to consider the deployment of fleets of autonomous underwater vehicles (AUVs) and autonomous surface vehicles (ASVs). Multiple vehicles with heterogeneous capabilities have several advantages over a single vehicle system, and in particular the potential to accomplish tasks faster and better than a single vehicle. This paper addresses in this context the problem of underwater targets localization. A systematic and exhaustive coverage strategy is not efficient in terms of exploration time: it can be improved by making the AUVs share their information to cooperate, and optimize their motions according to the state of their knowledge on the target localization. We present techniques to build environment representations on the basis of which adaptive exploration strategies can be defined, and define an architecture that allows information sharing and cooperation between the AUVs. Simulations are carried out to evaluate the proposed architecture and the adaptive exploration strategies.     

Interpolymer‐specific interactions and miscibility in poly(styrene‐co‐acrylic acid)/poly(styrene‐co‐N,N‐dimethylacrylamide) blends

The miscibility or complexation of poly(styrene‐co‐acrylic acid) containing 27 mol % of acrylic acid (SAA‐27) and poly(styrene‐co‐N,N‐dimethylacrylamide) containing 17 or 32 mol % of N,N‐dimethylacrylamide (SAD‐17, SAD‐32) or poly(N,N‐dimethylacrylamide) (PDMA) were investigated by different techniques. The differential scanning calorimetry (DSC) analysis showed that a single glass‐transition temperature was observed for all the mixtures prepared from tetrahydrofuran (THF) or butan‐2‐one. This is an evidence of their miscibility or complexation over the entire composition range. As the content of the basic constituent increases as within SAA‐27/SAD‐32 and SAA‐27/PDMA, higher number of specific interpolymer interactins occurred and led to the formation of interpolymer complexes in butan‐2‐one. The qualitative Fourier transform infrared (FTIR) spectroscopy study carried out for SAA‐27/SAD‐17 blends revealed that hydrogen bonding occurred between the hydroxyl groups of SAA‐27 and the carbonyl amide of SAD‐17. Quantitative analysis carried out in the 160–210°C temperature range for the SAA‐27 copolymer and its blends of different ratios using the Painter–Coleman association model led to the estimation of the equilibrium constants K₂, K_A and the enthalpies of hydrogen bond formation. These blends are miscible even at 180°C as confirmed from the negative values of the total free energy of mixing ΔG_M over the entire blend composition. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1011–1024, 2007     

Effect of cloisite 30B on the thermal and tensile behavior of poly(butylene adipate-co-terephthalate)/poly(vinyl chloride) nanoblends

Ternary PBAT/PVC/C30B nanoblends were successfully prepared via melt blending process at 130 °C and characterized by different techniques. The properties of the elaborated PBAT/PVC/C30B nanoblends were compared with those of the nonfilled PBAT/PVC blends to examine the C30B effects on the structure and properties of PBAT/PVC/C30B nanoblends. FTIR spectra revealed the presence of specific interactions between C=O of PBAT and acidic hydrogen of PVC, supporting the formation of miscible nanoblends. The PBAT/PVC/C30B morphology was investigated by both X-ray diffraction and transmission electron microscopy analyses. It was suggested the formation of mixed intercalated/partially exfoliated structures. Differential scanning calorimetry thermograms of PBAT/PVC/C30B nanoblends exhibited a single T _g and a full disappearance of the PBAT melting endotherm, confirming the complete compatibilization between PVC and PBAT. It was found that the T _g of the nanoblends were higher than those of the pristine blends due to their mixed intercalated/partially exfoliated structures. PBAT and PVC chains would be confined in a same C30B gallery causing a reduction of the chain mobility. Nanoblends showed a reduction of their thermal stability compared to their pristine blends, as a result of the catalytic effect of the C30B in the thermal degradation process. Tensile measurements displayed an improvement of mechanical properties for the ternary PBAT/PVC/C30B nanoblends relative to their virgin blends due to the insertion of clay particles into composite matrix.     

Preparation of chitosan‐g‐poly(acrylamide)/montmorillonite superabsorbent polymer composites: Studies on swelling,thermal, and antibacterial properties

Superabsorbent composites based on chitosan‐g‐poly(acrylamide) and montorillonite (CTS‐g‐PAAm/MMT) were synthesized through in situ radical polymerization by grafting of crosslinked acrylamide onto chitosan backbone in presence of MMT at different contents. The formation of the grafted network was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). The obtained porous structure was observed by scanning electron microscope (SEM). The presence of clay and its interaction with chitosan‐g‐poly(acrylamide) (CTS‐g‐PAAm) matrix was evidenced by ATR‐FTIR analysis. The morphology was investigated by both X‐ray diffraction (XRD) and SEM analyses. It was suggested the formation of mostly exfoliated structures with more porous structures. Besides, the thermal stability of these composites, observed by TGA analysis, was slightly affected by the clay loading as compared to the matrix. These hydrogel composites were also hydrolyzed to achieve anionic hydrogels with ampholytic properties. Swelling behaviors were examined in doubly distilled water, 0.9 wt % NaCl solution and buffer solutions. The water absorbency of all superabsorbent composites was enhanced by adding clay, where the maximum was reached at 5 wt % of MMT. Their hydrolysis has not only greatly optimized their absorption capacity but also improved their swelling rate and salt‐resistant ability. The hydrolyzed superabsorbent showed better pH‐sensitivity than the unhydrolyzed counterparts. The results of the antibacterial activity of these superabsorbents composites against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), assayed by the inhibitory zone tests, have showed moderate inhibition of the bacteria growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39747.     

Interpolymer interactions and miscibility in poly(n‐butyl methacrylate‐co‐methacrylic acid)/poly(styrene‐co‐N,N‐dimethyl acrylamide) blends

The miscibility of poly(n‐butyl methacrylate‐co‐methacrylic acid) containing 18 mol % methacrylic acid (BMAM‐18) and poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 17 mol % N,N‐dimethyl acrylamide (SAD‐17) was investigated with viscometry, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The DSC analysis showed a single glass‐transition temperature for all the blends, indicating that these copolymers were miscible over the entire composition range. The glass‐transition temperatures of these blends were higher than those calculated with the additivity rule. This was characteristic of the presence of specific interactions. The interactions between BMAM‐18 and the tertiary amide of SAD‐17 were studied with FTIR spectroscopy, which revealed that hydrogen‐bonding interactions occurred between the hydroxyl groups of BMAM‐18 and the carbonyl amide of SAD‐17. A new band characterizing these interactions appeared around 1613 cm^?1. The quantitative results showed that the fraction of the associated amide increased with an increase in the amount of the acidic BMAM‐18 copolymer. Although BMAM‐18 and SAD‐17 led to homogeneous solutions in butan‐2‐one, as the concentration of N,N‐dimethyl acrylamide increased to 32 mol % [as within the poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 32 mol % N,N‐dimethyl acrylamide], complexation occurred when this latter compound was mixed with BMAM‐18 in butan‐2‐one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2717–2724, 2006     

Multimodal magnetic resonance imaging for Alzheimer's disease diagnosis using hybrid features extraction and ensemble support vector machines

Magnetic resonance imaging (MRI) is increasingly used in the diagnosis of Alzheimer's disease (AD) in order to identify abnormalities in the brain. Indeed, cortical atrophy, a powerful biomarker for AD, can be detected using structural MRI (sMRI), but it cannot detect impairment in the integrity of the white matter (WM) preceding cortical atrophy. The early detection of these changes is made possible by the novel MRI modality known as diffusion tensor imaging (DTI). In this study, we integrate DTI and sMRI as complementary imaging modalities for the early detection of AD in order to create an effective computer-assisted diagnosis tool. The fused Bag-of-Features (BoF) with Speeded-Up Robust Features (SURF) and modified AlexNet convolutional neural network (CNN) are utilized to extract local and deep features. This is applied to DTI scalar metrics (fractional anisotropy and diffusivity metric) and segmented gray matter images from T1-weighted MRI images. Then, the classification of local unimodal and deep multimodal features is first performed using support vector machine (SVM) classifiers. Then, the majority voting technique is adopted to predict the final decision from the ensemble SVMs. The study is directed toward the classification of AD versus mild cognitive impairment (MCI) versus cognitively normal (CN) subjects. Our proposed method achieved an accuracy of 98.42% and demonstrated the robustness of multimodality imaging fusion.     

ITO substrate resistivity effect on the properties of CuInSe<Subscript>2</Subscript> deposited using two-electrode system

The purpose of this work is to deposit the CuInSe₂ films on the ITO substrate by electrodeposition technique using a simplified two electrodes system and to investigate the effect of ITO sheet resistance on the fundamental properties of the resulting films. The as deposited films were annealed under argon atmosphere at 300 °C during 30 min. The structural, morphological and electrical properties were characterized respectively by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical resistivity measurements. The optical band gap of samples was estimated using the optical absorption technique. After annealing, the XRD spectra show diffraction peaks corresponding to the single-phase chalcopyrite CuInSe₂ with (112) as main reflection. The SEM images reveal a homogeneous surface and the estimated grain size was calculated from Scherrer’s Equation with (112) peak lay in the range of 165–272 Å. The band gap, E _g, is a decreasing function with the ITO sheet resistance.     

Preventing expulsive hemorrhage using an anterior chamber maintainer to eliminate hypotony

We describe a method in which constant infusion inflow through an anterior chamber maintainer (ACM) is used to maintain positive intraocular pressure (IOP) during cataract extraction through a self-sealing tunnel incision. A retrospective review of patient records showed that the difference in the incidence of intraoperative suprachoroidal hemorrhage was significantly greater in eyes in which IOP was not constant throughout surgery than in eyes in which IOP was maintained using the ACM system.     

Triplet EPR Dynamics of Randomly Oriented Dications and Dianions of Tetraoxaporphyrinoids

This paper deals with the photoexcited triplet state of several tetraoxaporphyrinoids studied by time-resolved electron paramagnetic resonance (EPR). The porphyrinoids studied are tetraoxa[18]porphyrin ( 1a ⁺⁺), octaethyl-tetraoxa[18]porphyrin ( 1b ⁺⁺), tetra-n-butyl tetraoxa[18]porphyrin ( 1c ⁺⁺), octaethyl-tetraoxa[26]porphyrin ( 2 ⁺⁺), and tetraoxa[18]porphycene ( 3 ⁺⁺), all of them as per-chlorate salts. To qualify as stable aromatic 18π- (or 26π-) electron systems, they must exist as dications. Analysis of the triplet EPR spectra is characterized by unique features not found in their parent porphyrins and porphycenes. While in the case of the axially-symmetric tetraphenylporphyrin, the triplet EPR spectra indicate deviation from axial symmetry, the tetraoxaporphyrin 1a ⁺⁺ exhibits, as expected, a vanishing E-term of the zero-field splitting (ZFS) tensor. A conspicuous difference is found between the triplet EPR spectra of the dications and the dianions of all tetraoxa compounds. The results are discussed in terms of the electronic structures of the porphyrinoids.