Synthesis of water-soluble polymers containing sulfonic acid and amine moieties for the recovery of metal ions using ultrafiltration

Copolymers from 2-acrylamido-2-methyl-propane sulfonic acid (APSA) and N-acryloyl-N-methyl piperazine (AP) were synthesized by radical polymerization with ammonium peroxydisulfate as the initiator. The copolymerization yield ranged between 93 and 95%. The copolymers were completely water soluble, and were characterized by FTIR and NMR spectroscopy. The copolymer composition was determined from elemental analysis through the S/C ratio. The binding capacity for metal ion was studied by the LPR technique at different pH and filtration factors. The retention depended strongly on the pH and on the copolymer composition. With increasing pH and increasing content of APSA units in the copolymer, the metal ion retention increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 22–30, 2001     

Enhancing the stability and crystallinity of CsPbIBr2 through antisolvent engineering

All inorganic lead-based perovskites containing bromine-iodine alloys, such as CsPbIBr_2, have arisen as one of the most attractive candidates for absorber layers in solar cells. That said, there remains a large gap when it comes to film and crystal quality between the inorganic and hybrid perovskites. In this work, antisolvent engineering is employed as a simple and reproducible method for improving CsPbIBr₂ thin films. We found that both the antisolvent used and the conditions under which it was applied have a measurable impact on both the quality and stability of the final product. We arrived at this conclusion by characterising the samples using scanning electron microscopy, X-ray diffraction, UV–visible and photoluminescence measurements, as well as employing a novel system to quantify stability. Our findings, and the application of our novel method for quantifying stability, demonstrate the ability to significantly enhance CsPbIBr₂ samples, produced via a static one-step spin coating method, by applying isopropanol 10 s after commencing the spin programme. The antisolvent quenched CsPbIBr₂ films demonstrate both improved crystallinity and an extended lifespan.

     

Solution conformation and dynamics of an extracellular polysaccharide isolated from Bradyrhyzobium as deduced from 1H-NMR off resonance ROESY and 13C-NMR relaxation measurements

The conformational and dynamical features of an extracellular branched deacetylated polysaccharide isolated from Bradyrhizobium (Chamaecytisus proliferus) have been investigated by homo and heteronuclear NMR methods. 1H-NMR cross relaxation rates have been obtained for this polysaccharide through regular NOESY and ROESY spectra as well as by modern off resonance ROESY techniques. Local proton-proton correlation times as well as interproton distances have been obtained. 13C-NMR relaxation parameters (T1, T2, NOE) have also been measured at two different magnetic fields and interpreted using different approximations based on the Lipari and Szabo model free approach. The analysis of the data indicates the existence of important flexibility for the different linkages of the polysaccharide. Motions in the range of several ns contribute to the relaxation of the macromolecule, although faster internal motions in the 600-800 ps time scales are also present. These time scales indicate that segmental motions as well as internal motions around the glycosidic linkages are the major sources of relaxation for this molecule at 299 K.     

A saponin from the roots of Gypsophila bermejoi

A new saponin was isolated from the methanol extract of the roots of Gypsophila bermejoi and identified by a combination of chemical degradation and spectral methods, which included negative FABMS and extensive 1D and 2D-NMR analysis (DQCOSY, TOCSY, ROESY, HMQC and HMBC), as gypsogenin 28-O-beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl (1-->6)]-beta-D-glucopyranoside.     

Substrate influences on the properties of SnS thin films deposited by chemical spray pyrolysis technique for photovoltaic applications

Herein, we report on tin monosulfide (SnS) thin films elaborated by the Chemical Spray Pyrolysis (CSP) technique onto various substrates as simple glass, ITO-, and Mo-coated glasses in order to study the influence of substrates on the physical and chemical properties of Sns thin films. Structural analysis revealed that all films crystallize in orthorhombic structure with (111) as the sole preferential direction without secondary phases. In addition, film prepared onto pure glass exhibits a better crystallization compared to films deposited onto coated glass substrates. Raman spectroscopy analysis confirms the results obtained by X-ray diffraction with modes corresponding well to SnS single-crystal orthorhombic ones (47, 65, 94, 160, 186, and 219 cm ^?1) without any additional parasite secondary phase like Sn₂S₃ or SnS₂. Field emission scanning electron microscope revealed that all films have a cornflake-like particles surface morphology, and energy dispersive X-ray spectroscopy analysis showed the presence of sulfur and tin with a nearly stoichiometric ratio in films deposited onto pure glass. High surface roughness and large grains are observable in film deposited onto glass. From optical spectroscopy, it is inferred that band gap energy of SnS/glass and SnS/ITO were 1.64 and 1.82 eV, respectively.     

The 2D wavelet transform on emerging architectures: GPUs and multicores

Because of the computational power of today??s GPUs, they are starting to be harnessed more and more to help out CPUs on high-performance computing. In addition, an increasing number of today??s state-of-the-art supercomputers include commodity GPUs to bring us unprecedented levels of performance in terms of raw GFLOPS and GFLOPS/cost. In this work, we present a GPU implementation of an image processing application of growing popularity: The 2D fast wavelet transform (2D-FWT). Based on a pair of Quadrature Mirror Filters, a complete set of application-specific optimizations are developed from a CUDA perspective to achieve outstanding factor gains over a highly optimized version of 2D-FWT run in the CPU. An alternative approach based on the Lifting Scheme is also described in Franco et al. (Acceleration of the 2D wavelet transform for CUDA-enabled Devices, 2010). Then, we investigate hardware improvements like multicores on the CPU side, and exploit them at thread-level parallelism using the OpenMP API and pthreads . Overall, the GPU exhibits better scalability and parallel performance on large-scale images to become a solid alternative for computing the 2D-FWT versus those thread-level methods run on emerging multicore architectures.     

Metal ion interaction of water‐soluble copolymers containing carboxylic acid groups in aqueous phase by membrane filtration technique

This article reports the synthesis of poly(N‐maleoylglycine‐co‐itaconic acid) by radical copolymerization under different feed mole ratios and its properties to remove various metal ions, such as Cu(II), Cr(III), Co(II), Zn(II), Ni(II), Pb(II), Cd(II), and Fe(III), in aqueous phase with the liquid‐phase polymer‐based retention(LPR) technique. The interactions of inorganic ions with the hydrophilic water‐soluble polymer were determined as a function of pH and filtration factor. Metal ion retention was found to strongly depend on the pH. Metal ion retention increased as pH and MG content units in the macromolecular backbone increased. The copolymers were characterized by elemental analysis, FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. Additionally, intrinsic viscosity, molecular weight, and polydispersity have been determined for the copolymers. Copolymer and polymer–metal complex thermal behavior was studied using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques under nitrogen atmosphere. The thermal decomposition temperatures (TDT) were influenced by the copolymer composition. The copolymers present lower TDT than the polymer–metal complex with the same copolymer composition. All copolymers present a single T_g, indicating the formation of random copolymers. A slight deviation of the T_g for the copolymers and its complexes can be observed. The copolymer T_g is higher than the T_g value for the polymer–metal complexes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of functionalized trititanate nanotubes on the properties of crosslinked cationic polymer nanocomposite

The synthesis and characterization of a crosslinked polymer nanocomposite containing titanium oxide nanotubes as filler are presented. First, the TiO₂ nanotubes were synthesized using a hydrothermal procedure and further functionalized using the organosilane reagent γ‐methacryloxypropyltrimethoxysilane. Subsequently, the modified nanotubes were incorporated into a polymer matrix using in situ polymerization of a mixture of monomer, crosslinker and initiator. Diverse characterization techniques were used at different stages of the synthesis, including transmission (TEM) and scanning electron microscopies, X‐ray diffraction (XRD), solid‐state ²⁹Si NMR and ¹³C NMR spectroscopy and nitrogen adsorption isotherms at 77 K. The as‐synthesized nanotubes correspond to the trititanate phase verified using XRD, and their presence within the nanocomposite was confirmed using TEM analysis. In addition, TiO₂ particles were detected on the surface of the nanocomposite. The nanocomposite exhibited a slight increase of Vickers microhardness while the water absorption decreased with oxide content attributed to trititanate nanotubes acting as multifunctional crosslinker.© 2015 Society of Chemical Industry