Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids

In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol, trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl₄ ⁻/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NO _x with the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction.     

Enrichment of activated sludge for enhanced hydrogen production from crude glycerol

Enriched activated sludge that can effectively convert crude glycerol into bio-hydrogen was selected by an eco-biotechnological approach, in very strict conditions, using biodiesel-derived glycerol as the only carbon source. The thus obtained functional consortium was characterized by the genera Klebsiella, Escherichia/Shigella and Cupriavidus. During enrichment, the dominant metabolic end-product shifted from a 1,3 propanediol to ethanol, with a concomitant increase of the hydrogen yield from 0.18 ± 0.003 to 0.66 ± 0.06 mol/mol and an almost five-fold increase of the hydrogen production. Glycerol degradation efficiency showed an increase of around 50%. In optimized and upscaled conditions it was possible to obtain a hydrogen production rate of 2960 mL H₂/L/day ± 185 at a near stoichiometric yield (of 0.90 mol/mol ± 0.01), with a carbon recovery of almost 90%, both in sterile and non-sterile conditions. Glycerol was almost totally degraded (degradation efficiency of 97.42% ± 0.98), independently of the glycerol type used.     

Multiple regression models and Computer Vision Systems to predict antioxidant activity and total phenols in pigmented carrots

The relationships between colour parameters obtained by a Computer Vision System (CVS) and both antioxidant activity (AA) and total phenol contents (TP) on coloured carrots were expressed as multivariate models obtained by multiple linear regression. The AA and TP predicted by the proposed models showed a good correlation with the real AA (R² = 0.97, P ? 0.001) and TP (R² = 0.94, P ? 0.001) measurements on the data set including internal and external parts of carrots. The predictions on the data set including only the internal (unevenly pigmented) parts of the carrots exhibited lower determination coefficients (R² = 0.93 for AA and R² = 0.86 for TP, P ? 0.001). The effectiveness of the models was checked also on the colour information provided by a colorimeter whose measures proved to be more sensitive to the uneven pigmentation of the carrots. Finally, the proposed models were able to successfully estimate the AA and the TP contents of pigmented carrots when applied to colours measured by the CVS.     

Microstructure and properties of Co-, Ni-, Zn-, Nb- and W-modified multiferroic BiFeO3 ceramics

BiFeO₃ polycrystalline ceramics were prepared by the mixed oxide route and a chemical route, using additions of Co, ZnO, NiO, Nb₂O₅ and WO₃. The powders were calcined at 700 °C and then pressed and sintered at 800–880 °C for 4 h. High density products up to 96% theoretical were obtained by the use of CoO, ZnO or NiO additions. X-ray diffraction, SEM and TEM confirmed the formation of the primary BiFeO₃ and a spinel secondary phase (CoFe₂O₄, ZnFe₂O₄ or NiFe₂O₄ depending on additive). Minor parasitic phases Bi₂Fe₄O₉ and Bi₂₅FeO₃₉ reduced in the presence of CoO, ZnO or NiO. Additions of Nb₂O₅ and WO₃ did not give rise to any grain boundary phases but dissolved in BiFeO₃ lattice. HRTEM revealed the presence of domain structures with stripe configurations having widths of typically 200 nm. In samples prepared with additives the activation energy for conduction was in the range 0.78–0.95 eV compared to 0.72 eV in the undoped specimens. In co-doped specimens (Co/Nb or Co/W) the room temperature relative permittivity was ～110 and the high frequency dielectric loss peaks were suppressed. Undoped ceramics were antiferromagnetic but samples prepared with Co or Ni additions were ferromagnetic; for 1% CoO addition the remanent magnetization (M_R) values were 1.08 and 0.35 emu/g at temperatures of 5 and 300 K, respectively.     

Fabrication of biocompatible monolithic microchannels with high pressure‐resistance using direct polymerization of PEG‐modified PMMA

Withstanding high pressures in polymeric microchannels is an important requirement for many biological applications. Here, a simple direct polymerization through a polyester photomask is applied to obtain monolithic polyethylene glycol (PEG)‐modified poly(methyl methacrylate) (PMMA) (PEGMA) microchannels, showing the ability to withstand pressure up to 12 MPa in burst pressure tests. The ability of withstanding high pressures is observed to increase with increasing ratio between the thickness of the cover polymer layer forming the microchannel lid and the width of the microchannel. A simplified finite element modeling model of the burst pressure test is set up to interpret the experimental findings. The outcomes of the modeling activity, along with direct scanning electron microscopy observation of the fracture surfaces, confirm the effectiveness of the polymerization method for the production of monolithic PEGMA microchannels. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41031.     

Production scale plasma modification of polypropylene baselayer for improved water management properties

Through its hydrophobic properties, polypropylene (PP) offers unique potential as a functional fiber for a wide range of applications, for example, in nonwovens for hygiene applications or as a baselayer in sports textiles. Current work is focused on the modification of PP presently used in baselayers for sports textiles to increase the hydrophilicity by use of a production scale plant for low pressure plasma treatment. Attention was directed toward an increase in hydrophilicity and time stability of the achieved modification during storage. Changes in the fabric were characterized by sorption of the cationic dye (methylene blue), water retention value, water transport properties, Fourier transform infrared spectroscopy and color measurement. The obtained results indicate an improved wettability and wicking. The extent of modification decreased with storage time and parallel yellowing of treated samples was observed. This indicates chemical rearrangement of the products initially formed on the fiber surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41294.     

Location estimation‐based radio environment map construction in fading channels

Latest regulations on TV white space communications and trend toward spectrum access through geolocation databases relax the regulatory constraints on cognitive radios. Radio environment map (REM) is a kind of improved geolocation database and an emerging topic with the latest regulations on TV white space communications. It constructs a comprehensive temperature map of the cognitive radio network operation area by utilizing multi‐domain information from geolocation databases, characteristics of spectrum use, geographical terrain models, propagation environment, and regulations. REMs act as cognition engines by building long‐term knowledge via processing spectrum measurements collected from sensors to estimate the state of locations without any measurement data. Active transmitter LocatIon Estimation based REM construction technique is proposed and compared with the well‐known REM construction techniques such as Kriging and inverse distance weighted interpolation in shadow and multipath fading channels. The simulation results suggest that the LocatIon Estimation based REM construction outperforms the compared methods in terms of RMSE and correct detection zone ratio by utilizing additional information about channel parameters that can be estimated by classical least squares method easily.Copyright © 2013 John Wiley & Sons, Ltd.