Preparation and characterization of increased-efficiency photocatalytic TiO2-2xNx thin films

We report here on the characteristics of RF-sputtered 300 nm thick films of TiO_2-2xN_x prepared on glass substrates at 350 °C, by adjusting the N₂:Ar partial pressure ratio in the deposition chamber between 0.00 and 0.33. XRD, XPS, AFM and contact angle data were used to derive film structure, elemental composition and oxidation state of Ti, surface morphology and hydrophilicity, respectively. The band gap was derived from spectral data in the 350-450 nm range. Film structure and composition were changed by adjusting the partial pressure of the reactive gases during sputtering and by post-deposition annealing at 400 °C in air, for 90 min. The values of the contact angle of films' surface with de-ionized water and of surface free energy per unit area show that films are super-hydrophilic for high-nitrogen content. Correlations are made between film structure, elemental composition, electronic and wettability properties.     

Leader-member exchange and citizenship behaviors: A meta-analysis.

This article provides a meta-analytic review of the relationship between the quality of leader-member exchanges (LMX) and citizenship behaviors performed by employees. Results based on 50 independent samples (N = 9,324) indicate a moderately strong, positive relationship between LMX and citizenship behaviors (ρ=.37). The results also support the moderating role of the target of the citizenship behaviors on the magnitude of the LMX-citizenship behavior relationship. As expected, LMX predicted individual-targeted behaviors more strongly than it predicted organizational targeted behaviors (ρ = .38 vs. ρ = .31), and the difference was statistically significant. Whether the LMX and the citizenship behavior ratings were provided by the same source or not also influenced the magnitude of the correlation between the 2 constructs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Microfluidic Ion Sensor Array

A balanced concentration of ions is essential for biological processes to occur. For example, [H⁺] gradients power adenosine triphosphate synthesis, dynamic changes in [K⁺] and [Na⁺] create action potentials in neuronal communication, and [Cl^?] contributes to maintaining appropriate cell membrane voltage. Sensing ionic concentration is thus important for monitoring and regulating many biological processes. This work demonstrates an ion‐selective microelectrode array that simultaneously and independently senses [K⁺], [Na⁺], and [Cl^?] in electrolyte solutions. To obtain ion specificity, the required ion‐selective membranes are patterned using microfluidics. As a proof of concept, the change in ionic concentration is monitored during cell proliferation in a cell culture medium. This microelectrode array can easily be integrated in lab‐on‐a‐chip approaches to physiology and biological research and applications.     

From Glucose Direct to Succinic Acid: an Optimized Recyclable Bi-functional Ru@MNP-MWCNT Catalyst

Ru@MNP-MWCNT catalysts were obtained via functionalization of nanostructured carbon-based carriers (ie, MWCNT) with base molecules (ie, 2-aminophenol and ethylenediamine) followed by the complexation with RuCl₃. These structures demonstrated a highly efficient behavior for the selective wet oxidation of levulinic acid and glucose to succinic acid. However, to ensure an easy recovery and high recyclability the MWCNTs nanotubes were modified by incorporation of super-paramagnetic Fe₃O₄ nanoparticles into porous structure. Besides the catalytic performances the resulted composites showed a good mechanical resistance.     

Biomass productivity and wood energy of Salix species after 2 years growth in SRIC fertilized with wastewater sludge

The energy equivalent of willows in short-rotation intensive culture (SRIC) varies in terms of yield and woody biomass characteristics. Three willow species (Salix discolor Mühl., Salix petiolaris Smith and Salix viminalis L.) were planted on two sites, well-drained and poorly drained, in two different densities (20 000 and 30 000 plants per ha). Four doses of dried and granulated sludge were applied: the equivalents of 0, 100, 200 and 300 kg “available” N per ha. At the end of the second season, above-ground biomass was similar for S. discolor and S. viminalis, and greater than that of S. petiolaris on both sites and for all sludge treatments. On the well-drained site, each increment in the sludge dose significantly increased the performance of the species, regardless of plant density. Fertilized with a sludge dose equivalent to 300 kg N per ha, S. viminalis and S. discolor yielded 30.17 and 24.97 t/ha of dry matter respectively. On the poorly drained site, differences in performance were also observed between fertilized and unfertilized plots, but not among the various treatments. The calorific value of the wood of the three species being similar (19.21–19.59 kJ/g), the energy equivalent of a hectare of willows is proportional to the yield of each species. Thus the energy equivalent of S. viminalis and S. discolor is two to three times that of S. petiolaris. S. viminalis had the highest woody biomass quality, with an FVI (fuelwood value index) of 1030.58 (100%), followed by S. petiolaris with 954.25 (92.6%) and S. discolor with 849.08 (82.4%).     

Growth patterns and biomass productivity of two Salix species grown under short-rotation intensive culture in southern Quebec

Samples of two species of Salix, Salix discolor, which grows naturally in the northern half of North America and S. viminalis, which originated from central Europe, were studied to compare their productivity and their growth patterns under the short-rotation, intensive-culture system (SRIC). The study was conducted in the nursery of the Montreal Botanical Garden on former agricultural land. The plantation was established at a density of 27,000 trees per hectare from unrooted cuttings without any fertilizer or irrigation. Growth parameters were measured at regular intervals during summer of the two first years following planting. At the end of each growing season, after leaf drop, a part of each plot was cut down and the stems and branches were harvested and weighed to evaluate their annual growth rates and their biomass yields. For the first growing season, height growth in both species was greater than 2 m. Although S. viminalis grew more rapidly early in summer, S. discolor grew about three weeks longer and its total height at the end of the growing season was greater than the former. Meanwhile the stem-branch dry weight of S. discolor was similar to the one produced by S. viminalis. Two growing seasons after establishment, the total tree height was about 3.5 m for both species, while the biomass of stems and branches of S. viminalis was weakly superior in comparison to S. discolor and reached very high values-about 27 Mg ha⁻¹ for S. viminalis. The growth patterns and yields of the one-year-old coppice (one-year-cycle) were similar to those recorded at the end of the first year for trees developed directly from cuttings. Both species produced a comparable quantity of sprout biomass. The yield of the trees harvested two years after planting was about twice the total biomass harvested two times, at the end of each growing season, suggesting that a two-year cycle is more productive than a one-year cycle.     

PEGylation Effects on the Interaction of Sphingomyelin Nanoemulsions with Serum Albumin: A Thermodynamic Investigation

The recent focus in the development of novel nanosystems for biomedical applications lays firmly on their interactions with biomolecules. Thermodynamic parameters driving the interaction between nanoparticles and proteins provide insights into complex processes at bio/nanointerface. The present work aims to investigate the binding mechanisms and the dominant contributions that determine the adsorption processes during the interactions of a model protein, that is, bovine serum albumin, with a new type of drug delivery systems, Vitamin E/sphingomyelin nanoemulsions, plain and coated with polyethylene glycol, and d -ɑ-tocopheryl polyethylene glycol succinate. The binding parameters (binding constant, binding stoichiometry, enthalpy, Gibbs energy, and entropy changes of binding) are evaluated by the isothermal titration calorimetry with a MicroCaliTC200 equipment. The effect of nanoemulsions on the protein stability is examined by measuring the thermodynamic parameters for the protein's unfolding (heat capacity; enthalpy, entropy, and free energy changes) with a NanoDSC (TA Instrument) apparatus. The thermodynamic profile shows for all compositions an entropy-driven interaction dominated by hydrophobic forces due to the rearrangements/displacement of the surrounding water molecules, while maintaining the native conformation of the protein. All the information acquired by thermodynamic approach may significantly enhance the knowledge with special focus on PEGylated nanoemulsions used for biomedical applications.