Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel.

An environmental analysis for comparing waste management options and strategies.

The debate on different waste management practices has become an issue of utmost importance as human activities have overloaded the assimilative capacity of the biosphere. Recent Italian law on solid waste management recommends an increase in material recycling and energy recovery, and only foresees landfill disposal for inert materials and residues from recovery and recycling. A correct waste management policy should be based on the principles of sustainable development, according to which our refuse is not simply regarded as something to eliminate but rather as a potential resource. This requires the creation of an integrated waste management plan that makes full use of all available technologies. In this context, eMergy analysis is applied to evaluate three different forms of waste treatment and construct an approach capable of assessing the whole strategy of waste management. The evaluation included how much investment is needed for each type of waste management and how much "utility" is extracted from wastes, through the use of two indicators: Environmental yield ratio (EYR) and Net eMergy. Our results show that landfill is the worst system in terms of eMergy costs and eMergy benefits. Composting is the most efficient system in recovering eMergy (highest EYR) from municipal solid waste (MSW) while incineration is capable of saving the greatest quantity of eMergy per gram of MSW (highest net eMergy). This analysis has made it possible to assess the sustainability and the efficiency of individual options but could also be used to assess a greater environmental strategy for waste management, considering a system that might include landfills, incineration, composting, etc.

1H-NMR studies on the self-association of chloroquine in aqueous solution.

The concentration dependences of 1H-NMR chemical shifts and spin-lattice relaxation rates were measured for chloroquine in aqueous solution. The weak self-association constant was evaluated according to a dimerization equilibrium with the formation of self-stacked adducts (Kd = 4.52 +/- 0.68 l mol-1). The motional correlation times were evaluated for the monomer and the dimer by measuring intramolecular dipolar cross-relaxation rates of aromatic vicinal protons (tau cm = 0.06 ns and tau cd = 0.26 ns). The geometry of the stacked dimer was elucidated by measuring intermolecular dipolar cross-relaxation rates and interpreted in terms of partial superposition of quinoline moieties.

Conformational and dynamic features of cocaine in DMSO-d6 solution.

13C spin-lattice relaxation rates, 13C {1H} NOESs, 1H spin-spin relaxation rates and 1H two-dimensional magnetization transfer spectroscopy were used for delineating conformational features of cocaine in DMSO-d6 solution. Two main conformations differing in the orientation of the plane made by the benzoxy substituent with respect to the piperidine ring principal axis were observed. Relatively slow interconversions of the piperidine ring were delineated together with the main motional features of the whole molecule.

Environmental aspects of pesticide use in Italian agriculture.

Pesticides used in agriculture accumulate in organisms and reach man through complex metabolic pathways. Accurate analysis of pesticides presence in each step of the food chain is necessary because of the high number of these substances, their potential toxicity and the presence of amplified toxic effects due to synergic interactions. In the same way it is necessary to evaluate the environmental effects of the whole pesticides cycle, from industrial production until final disposal of used containers and residuals. Furthermore recent introduction of new categories of chemicals which are not strictly classifiable as pesticides (photosynthetic activity stimulators, aesthetic aspect enhancers) and not yet sufficiently studied in their metabolic behaviour, increase the problem complexity. Complete studies about these complex problems and about the effects on ecosystems have not yet been carried out in Italy, due to ambiguous laws and regulations, inadequate data collection methods and decisional influence of the chemical industry on agriculture policy.

Effects of bioaccumulation of PCBs on biodiversity and distribution of fish in two creeks in east Tennessee (USA).

The Oak Ridge Reservation, established in Tennessee during World War II as a research, development and process facilities support for the Manhattan Project, released large quantities of organic, inorganic and radionuclear contaminants into the environment. Their effects are particularly evident in aquatic ecosystems, as chemical concentrations in water, and as a disease in biodiversity and species richness. East Fork Poplar Creek and its tributary, Bear Creek flow inside the Reservation and have highly degraded natural habitats, unsatisfactory water quality and impoverished biota. PCB concentrations exceed recommended criteria for aquatic life safety and appear as a primary cause of environment degradation and reduced species richness. An uptake model, FGETS (Food and Gill Exchange of Toxic Substances) was used to analyse fish biodiversity and distribution in the two streams in relation to bioaccumulation of PCB congeners 1254 and 1260. Bioaccumulation of the two polychlorinated biphenyls was estimated in four different species of fish common in Tennessee rivers and streams: Catostomus commersoni, Lepomis macrochirus, Cyprinus carpio and Micropterus salmoides to integrate the available set of data and to evaluate the entity of human impact on these escosystems.

Binding features of diacetylmorphine (heroin) in whole blood and in blood fractions.

Binding features of heroin in whole blood and in blood fractions were delineated by measuring the selective spin-lattice relaxation rates of heroin protons in physiologic conditions. Interaction with some receptor located in the whole human blood or in the human plasma was detected and the apparent binding constant calculated (K = 39 mol-1 dm3). Inferences about molecular dynamics of the bound heroin could be also gained.

Modeling interpretation of microbe metabolism detected by nuclear magnetic resonance.

A new modeling approach is discussed for the analysis of microbial dynamics. It is based on structurally nonlinear compartmental models and on the dynamics of the substrate and product. Experimental data were acquired by NMR spectroscopy which is a noninvasive technique. This combined approach was tested with the fermentation of glucose to ethanol by Saccharomyces cerevisiae. The model was fitted with the experimental data to obtain the values of the parameters of the model. Similar processes can be analyzed and compared using this approach.