Seaweeds for the remediation of wastewaters contaminated with zinc(II) ions

Eleven different species of marine macroalgae were screened at different pH conditions on the basis of zinc(II) biosorption potential. Among the seaweeds, a green alga, Ulva reticulata, exhibited a highest uptake of 36.1 mg/g at pH 5.5 and 100 mg/l initial zinc(II) concentration. Further experiments were conducted to evaluate the zinc(II) biosorption potential of U. reticulata. Sorption isotherm data obtained at different pH (5-6) and temperature (25-35 degrees C) conditions were fitted well with Sips model followed by Freundlich, Redlich-Peterson and Langmuir models. A maximum zinc(II) biosorption capacity of 135.5 mg/g was observed at optimum conditions of 5.5 (pH) and 30 degrees C (temperature), according to the Langmuir model. It was observed from the kinetic data that the zinc(II) biosorption process using U. reticulata follows pseudo-second-order kinetics. Various thermodynamic parameters, such as DeltaG degrees , DeltaH degrees and DeltaS degrees were calculated and they indicated that the present system was a spontaneous and an endothermic process. The influence of the co-ions (Na(+), K(+), Ca(2+) and Mg(2+)) along with zinc(II) present in the wastewater was also studied. Desorption of zinc(II) ions from the zinc(II)-loaded biomass were examined using 0.1 M CaCl(2) at different pH conditions in three sorption-desorption cycles. A fixed-bed column (2 cm i.d. and 35 cm height) was employed to evaluate the continuous biosorption performance of U. reticulata. The column experiments at different bed heights and flow rates revealed that the maximum zinc(II) uptake was obtained at the highest bed height (25 cm) and the lowest flow rate (5 ml/min). Column data were fitted well with Thomas, Yoon-Nelson and modified dose-response models. The column regeneration studies were carried out for three sorption-desorption cycles. A loss of sorption performance was observed during regeneration cycles indicated by a shortened breakthrough time and a decreased zinc(II) uptake.     

An Easily Accessible NIR-Absorbing Tetraimide Dye and its Biotherapeutics Based Photothermal and Photodynamic Therapy

Organic π-systems with strong absorption in the near-infrared (NIR) region are promising candidates for photothermal therapy (PTT) and photodynamic therapy (PDT). However, the synthesis of NIR π-systems involves several steps and many of them display poor photothermal conversion efficiency (PTCE). Here we present the synthesis of a tetraimide-based donor-acceptor NIR π-system, 2EHex-B having absorbance in the range of 350–900 nm. Importantly, 2EHex-B is synthesized in two steps with a 70 % high yield. Moreover, 2EHex-B shows excellent PTCE up to 50 % and good biocompatibility when encapsulated in liposomes. The liposome coated 2EHex-B , ( L-2EHex-B) showed good thermal stability and efficiently kills cancer cells via PTT. Additionally, L-2EHex-B shows good reactive singlet oxygen generation ability when irradiated with a 750 nm laser. 3D cell culture model - multicellular spheroids test was performed to evaluate the efficiency of PTT. The spheroids treated with L-2EHex-B after NIR light irradiation showed increased cell death from the core of the tumor toward the periphery. The easy access to 2EHex-B makes it a potential candidate for minimally invasive cancer treatment.     

Wear of a Fe2.5Ni2.5CrAl Multiprincipal Element Alloy: A Combined Experimental and Molecular Dynamics Study

The Fe2.5Ni2.5CrAl multiprincipal element alloy (MPEA) is a promising material for engineering applications because of its high strength and plasticity values. To evaluate the friction and wear performance, reciprocating dry sliding tests and molecular dynamics (MD) simulations are performed to determine the wear mechanism over a range of length scales. This alloy exhibits a lower average friction coefficient and wear volume loss during dry sliding compared with the well-known Fe2Ni2CrAl alloy. The worn surface morphology reveals abrasive scratches, grooves, and delamination. The fine wear debris possesses high oxygen content, leading to higher wear resistance. The wear mechanism involves abrasive, adhesive, and oxidative wear. The wear, atomic stress and shear strain, dislocations, and lattice structure are analyzed by MD simulations. Point defects, atomic clusters, and stacking faults are identified in the nanowear process. The behavior of the $1/6<112>$(Shockley)-type dislocations is identified as the main dislocation mechanism during sliding. Stacking faults produced during the stress release process are present in the indentation. This work provides a deep insight into the friction and wear behavior of Fe2.5Ni2.5CrAl MPEAs.     

Thermal diffusivity of lead titanate/polyvinylidene fluoride-trifluoroethylene nanocomposites by the mirage method

Thermal diffusivity D of lead titanate/polyvinylidene fluoride-trifluoroethylene {PT/P(VDF-TrFE)} nanocomposites has been measured by the skimming configuration of the mirage method. Diffusivity values are calculated by measuring the phase variation of the probe beam deflection signal upon changing both the vertical and horizontal probe beam offset values at different modulation frequencies of the pump beam. The thermal diffusivity of the nanocomposites is found to depend on the volume fraction of the ceramic in the composites. The composites with higher volume fraction of ceramic have higher thermal diffusivity and conductivity. Different models were used to predict the thermal conductivity (k) of composites and the measured values agree quite well with the Looyenga model.     

Synthesis of Silver Nanoparticles Using Syzygium malaccense Fruit Extract and Evaluation of Their Catalytic Activity and Antibacterial Properties

Journal of Inorganic and Organometallic Polymers and Materials - In this study, green synthesis of silver nanoparticles, an aqueous&nbsp;Syzygium malaccense&nbsp;fruit extract, was employed...