Adoption and impact of integrated Striga and soil fertility management strategy in Mali

The possibility to vary the energy matrix, thus reducing the dependency on fossil fuels, has amplified the acceptance of biomass as an alternative fuel. Despite being a cheap and renewable option of waste from agriculture and forestry activities, the use of these materials has barriers due to its low density and low energetic efficiency, which can raise the costs of its utilization. Biomass densification has drawn attention due to its advantage in comparison to in natura biomass due to its better physical and combustion characteristics. Work has been carried out in this areas namely in the densification (briquettes) forestry wastes, kiwi and vine punning waste and their respectively elementary characterization. In a subsequent step, this work also presents the study of the thermal performance and combustion hygiene of the different briquettes produced in a burning hot water boiler. The thermal efficiency was determined by the direct method and it was found that the boiler thermal performance was quite similar for the different types of fuel tested and did not depend on the fuel feeding rate

Addition of H_2O and O_2 to Acetone and Dimethylsulfoxide Ligated Uranyl(V) Dioxocations

Gas-phase complexes of the formula [UO_2(lig)]^+ (lig = acetone (aco) or dimethylsulfoxide (dmso)) were generated by electrospray ionization (ESI) and studied by tandem ion-trap mass spectrometry to determine the general effect of ligand charge donation on the reactivity of UO_2^+ with respect to water and dioxygen. The original hypothesis that addition of O_2 is enhanced by strong σ-donor ligands bound to UO_2^+ is supported by results from competitive collision-induced dissociation (CID) experiments, which show near exclusive loss of H_2O from [UO_2(dmso)(H_2O)(O_2)]^+, whereas both H_2O and O_2 are eliminated from the corresponding [UO_2(aco)(H_2O)(O_2)]^+ species. Ligand-addition reaction rates were investigated by monitoring precursor and product ion intensities as a function of ion storage time in the ion-trap mass spectrometer: these experiments suggest that the association of dioxygen to the UO_2^+ complex is enhanced when the more basic dmso ligand was coordinated to the metal complex. Conversely, addition of H_2O is favored for the analogous complex ion that contains an aco ligand. Experimental rate measurements are supported by density function theory calculations of relative energies, which show stronger bonds between UO_2^+ and O_2 when dmso is the coordinating ligand, whereas bonds to H_2O are stronger for the aco complex

Interactions of Poly(amidoamine) Dendrimers with Human Serum Albumin: Binding Constants and Mechanisms

The interactions of nanomaterials with plasma proteins have a significant impact on their in vivo transport and fate in biological fluids. This article discusses the binding of human serum albumin (HSA) to poly(amidoamine) [PAMAM] dendrimers. We use protein-coated silica particles to measure the HSA binding constants (K_b) of a homologous series of 19 PAMAM dendrimers in aqueous solutions at physiological pH (7.4) as a function of dendrimer generation, terminal group, and core chemistry. To gain insight into the mechanisms of HSA binding to PAMAM dendrimers, we combined ^1H NMR, saturation transfer difference (STD) NMR, and NMR diffusion ordered spectroscopy (DOSY) of dendrimer−HSA complexes with atomistic molecular dynamics (MD) simulations of dendrimer conformation in aqueous solutions. The binding measurements show that the HSA binding constants (K_b) of PAMAM dendrimers depend on dendrimer size and terminal group chemistry. The NMR ^1H and DOSY experiments indicate that the interactions between HSA and PAMAM dendrimers are relatively weak. The ^1H NMR STD experiments and MD simulations suggest that the inner shell protons of the dendrimers groups interact more strongly with HSA proteins. These interactions, which are consistently observed for different dendrimer generations (G0-NH_2vs G4-NH_2) and terminal groups (G4-NH_2vs G4-OH with amidoethanol groups), suggest that PAMAM dendrimers adopt backfolded configurations as they form weak complexes with HSA proteins in aqueous solutions at physiological pH (7.4)

Development and Validation of a ReaxFF Reactive Force Field for Cu Cation/Water Interactions and Copper Metal/Metal Oxide/Metal Hydroxide Condensed Phases

To enable large-scale reactive dynamic simulations of copper oxide/water and copper ion/water interactions we have extended the ReaxFF reactive force field framework to Cu/O/H interactions. To this end, we employed a multistage force field development strategy, where the initial training set (containing metal/metal oxide/metal hydroxide condensed phase data and [Cu(H_2O)_n]^(2+) cluster structures and energies) is augmented by single-point quantum mechanices (QM) energies from [Cu(H_2O)_n]^(2+) clusters abstracted from a ReaxFF molecular dynamics simulation. This provides a convenient strategy to both enrich the training set and to validate the final force field. To further validate the force field description we performed molecular dynamics simulations on Cu^(2+)/water systems. We found good agreement between our results and earlier experimental and QM-based molecular dynamics work for the average Cu/water coordination, Jahn−Teller distortion, and inversion in [Cu(H_2O)_6]^(2+) clusters and first- and second-shell O−Cu−O angular distributions, indicating that this force field gives a satisfactory description of the Cu-cation/water interactions. We believe that this force field provides a computationally convenient method for studying the solution and surface chemistry of metal cations and metal oxides and, as such, has applications for studying protein/metal cation complexes, pH-dependent crystal growth/dissolution, and surface catalysis