Gestão e práticas socialmente responsáveis na cooperação agrícola

Through its history, agricultural cooperation has developed standards and values, leading specific decision making processes. The article proposes a model of decision based on "dialectical tension". By taking into account the dynamic relationship between stakeholders and organizations, this innovative model overcomes the limits of the stakeholders’ theory

The Synthesis, Self-Assembly and Self-Organisation of Polysilane Block Copolymers

Block copolymers containing polysilane blocks are unique in that the polysilane components possess electro-active properties and are readily photodegradable. This review will discuss and assess the two major approaches to the synthesis of polysilane block copolymers via pre-formed polymer chain coupling and living polymerisation techniques. The self-organisation of polysilane block copolymers and the morphologies adopted in thin films are reviewed. Amphiphilic polysilane-containing block copolymers self-assemble in solvents selective for one block and a number of examples are highlighted. The versatility of these materials is highlighted by recent significant applications including the preparation of hollow crosslinked micellar aggregates in aqueous solutions and in patterned thin film generation subsequently employed as templates for the growth of cell cultures and CaCO (3.

Synthesis and properties of polysilanes: versatile new organic materials

The most important synthetic methods including the Wurtz reaction, the activated alkali metal mediated reductive coupling, the electrochemical polymerization of dichlorosilanes using sacrificial anodes, the anionic ring-opening polymerization of tetrasilacyclobutanes and of masked disilenes, and the transition metal (Ti, Zr, Hf) catalyzed dehydrogenative coupling of hydrosilanes are briefly overviewed. A short discussion of the thermal and electronic properties of polysilanes allows for anticipating respectively their excellent processability and their technological applications. Among the latter, the most important ones appear to be microlithography for electronics, manufacture of light-emitting diodes (LEB) for various display devices, and fabrication of high tensile strength silicon carbide fibers, as well as heat resistant machineable objects. Other promising potential applications in optoelectronics are based on the interesting nonlinear optical (NLO) and photoconductive properties of suitably substituted polysilanes

Optimization of the structural parameters on new potentiometric pH and urea sensors based on polyaniline and a polysaccharide coupling layer

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