PlantPIs--an interactive web resource on plant protease inhibitors

PlantPIs is a web querying system for a database collection of plant protease inhibitors data. Protease inhibitors in plants are naturally occurring proteins that inhibit the function of endogenous and exogenous proteases. In this paper the design and development of a web framework providing a clear and very flexible way of querying plant protease inhibitors data is reported. The web resource is based on a relational database, containing data of plants protease inhibitors publicly accessible, and a graphical user interface providing all the necessary browsing tools, including a data exporting function. PlantPIs contains information extracted principally from MEROPS database, filtered, annotated and compared with data stored in other protein and gene public databases, using both automated techniques and domain expert evaluations. The data are organized to allow a flexible and easy way to access stored information. The database is accessible at http://www.plantpis.ba.itb.cnr.it/.     

Os and Pd Modified Tin Oxide Films for Sensors by the Sol Gel Process

Pure, Pd and Os modified SnO₂ films were prepared by the sol gel process and used as active materials in gas sensing devices. The films have been prepared starting from tin tetrachloride in alcoholic solution hydrolysed with water. The modifier was added to the sol as inorganic salt. Pd acetate and Os chloride were the Pd and Os precursors respectively. A structural and morphological study was carried out by means of Atomic Force Microscope (AFM), Secondary Ion Mass Spectrometer (SIMS) and x-ray Diffraction (XRD). The electrical resistance variations as a function of various gaseous atmospheres and temperature were measured to evaluate the sensing properties of the films. CO, CH₄, CH₃OH and C₂H₅OH gases were used for the tests. Following results were obtained: Pd is present in the form of PdO nanoclusters in the polycrystalline SnO₂ matrix as evidenced by XRD spectra whereas Os is a cationic modifier uniformly dispersed as evidenced in SIMS studies. Optimum sensing temperature and the sensitivity variations, with respect to the undoped films, differ according to the gaseous species. It looks therefore promising to use inexpensive, sol-gel derived, array of films in smart gas sensing devices that are able to recognise gas species and concentration.     

Sol-Gel Preparation of Selective Emitters for Thermophotovoltaic Conversion

Selective emitters are materials characterized by a high temperature emissivity significantly changing in different spectral regions. One of the crucial steps for the development of Thermophotovoltaic (TPV) generators is given by an optimal matching of the spectral emissivity of an IR radiation source with the spectral region where is maximum the efficiency of photovoltaic cells. The emitters should retain good structural properties at the working temperature above 1300°C and they can be either an external coating for the a burner or, as a structural material, a burner and emitter at once.In this work, oxide glass and ceramics containing rare earths have been prepared and characterized as selective emitters candidates. Different approaches and materials have been attempted all based on a colloidal route. Rare earths oxides (erbium and holmium) have been incorporated in transparent silica glass and in polycrystalline alumina and zirconia using their hydrated salts as oxide precursors. Rare earth modified silica glass were obtained by sintering silica xerogel containing fumed silica and hydrolysed ortholisicate. Rare earth modified alumina and mixed alumina-zirconia ceramics were obtained from slurries containing alumina colloidal particles and milled ceramic fibres. Functional properties i.e. the high temperature spectral emissivities have been measured by means of a specially designed apparatus where the working conditions of the selective emitters can be reproduced and monitored.     

Porous Garnet Coatings Tailoring the Emissivity of Thermostructural Materials

The power radiated by a surface influences the energy transfer processes following a T⁴ slope. It is therefore clear that, at high temperature, the study and control of spectral emissivity of materials play a key role in many important technologies: re-entry-vehicle thermal protection shields, high temperature radiators, selective emitters in thermophotovoltaic generators, etc. We have developed a class of thick porous garnet coatings that may raise or lower the spectral emissivity of thermostructural materials in the VIS, NIR, and IR regions. The porosity of the coatings nearly cancels any emission contribution from the underlying materials due to the scattering in the inhomogeneous system: pore/high refraction garnet. The yttrium aluminum garnet polycrystals vary their emissivity as a function of the doping rare earth elements they contain. We achieved an emission control capability in the range 700–3000 nm. Porous coatings have been prepared from ceramic slips containing a reactive colloidal phase and rare earth garnet powders prepared by drying and calcining mixed oxide aqueous gels. Garnet coatings containing Er, Yb, and Tm were prepared with thickness ranging between 50 and 400 microns. The coatings have been investigated by morphological and microstructural studies. A dedicated experimental set up has been developed to measure the spectral emissivity up to 1700 K under different heating conditions.     

Photocatalytic TiO2 coatings on limestone

The application of photocatalytic coatings on stone has been investigated for providing surface protection and self-cleaning properties. Sol–Gel and hydrothermal processes were used to synthesise TiO₂ colloidal suspensions and coatings with enhanced photocatalytic activity without any thermal curing of the coated stone. The stone was a porous limestone (apulian sedimentary carbonatic, calcite stone). Films and powders prepared from TiO₂ sols were studied using X-ray diffraction to evaluate the microstructure and identify rutile and anatase phases. A morphological and physical characterisation was carried out on coated and uncoated stone to establish the changes of appearance, colour, water absorption by capillarity and water vapour permeability. The photocatalytic activity of the coated surface was evaluated under UV irradiation through NO _x and organics degradation tests. The performances of the synthesised TiO₂ sols were compared with commercial TiO₂ suspension. Since the coating doesn’t need temperature treatments for activating the photocatalytic properties, the nano-crystalline hydrothermal TiO₂ sols seem good candidate for coating applications on stone that cannot be annealed after the coating application.