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We report, for the first time, results on transparent ZnO:Al thin films deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by magnetron sputtering. The structural, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (0 0 2) perpendicular to the substrate surface. The ZnO:Al thin films with 83% transmittance in the visible region and a resistivity as low as 3.6 × 10-2 Ωcm have been obtained, as deposited. The obtained results are comparable to those obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices. © 2002 Elsevier Science Ltd. All rights reserved.

A new experimental procedure combining usual isothermal DC charging and discharging with non-isothermal current measurements has been recently proposed. It is mainly suitable for very high insulating polymers and it was successfully applied to the study of space charge trapping and transport in low-density polyethylene. The analysis of the isothermal currents revealed the presence of different traps whose characteristic (de)trapping times can be deduced. The isothermal procedures allowed the selective charging of the sample. By choosing the charging field and the ratio of charge/discharge times, non-isothermal analysis permitted the differentiation of three or four peaks (at approximate to50degreesC, approximate to65degreesC, approximate to70degreesC and approximate to85degreesC) associated with charge detrapping from surface or near-surface (<20 mum) traps. These traps have activation energies between 0.21 and 1.54 eV. The mobility at 30degreesC is around 5 x 10(-16) m(2) V-1 s(-1). Samples had to be conditioned before each experiment in order to obtain reproducible results.

A new experimental procedure combining usual isothermal DC charging and discharging with non-isothermal current measurements has been recently proposed. It is mainly suitable for very high insulating polymers and it was successfully applied to the study of space charge trapping and transport in low-density polyethylene. The analysis of the isothermal currents revealed the presence of different traps whose characteristic (de)trapping times can be deduced. The isothermal procedures allowed the selective charging of the sample. By choosing the charging field and the ratio of charge/discharge times, non-isothermal analysis permitted the differentiation of three or four peaks (at approximate to50degreesC, approximate to65degreesC, approximate to70degreesC and approximate to85degreesC) associated with charge detrapping from surface or near-surface (<20 mum) traps. These traps have activation energies between 0.21 and 1.54 eV. The mobility at 30degreesC is around 5 x 10(-16) m(2) V-1 s(-1). Samples had to be conditioned before each experiment in order to obtain reproducible results.

In this work, we study the electro-optical behaviour of cellulose/liquid crystal-based composite systems, in particular the influence of the flexible substrates and its conductive layers in the electro-optical behaviour of these kind of cells. Four cells were made using, respectively, two different substrates (a flexible polymer (poly(ethylene terephthalate) (PET)) and a soda lime glass) and two different conductive layers (indium tin oxide (ITO) and aluminium zinc oxide (AZO)). The conductive layer (AZO) was deposited in both, flexible and rigid substrates, for the same conditions, and the same substrates coated with ITO are commercially available. The cells were prepared from solid films of hydroxypropylcellulose (HPC) (30 μm thick) cross linked with 1,4-diisocyanatobutane (BDI) (7% w/w) and the nematic liquid crystal E7 (Merck, UK). The four different substrates were electrically and morphologically characterised. We have analysed all samples by light transmission and determined the maximum transmission, contrast and Von. We show a comparison of the results obtained for both flexible and rigid cells and discuss them in terms of the proposed working mechanism for these systems. © 2002 Elsevier Science B.V. All rights reserved.

In this work we present results concerning the composition and structure of intrinsic thin film silicon carbide alloys obtained by hot wire and hot wire plasma assisted techniques using ethylene as carbon gas source. The data show that by increasing the percentage of ethylene in the gas mixture from 14% to 60% the optical band gap is enhanced from 1.8 eV to 2.3 eV, for films produced by hot wire technique at a filament temperature of 2123K (1850°C). This is attributed to the increase of carbon incorporation, which was confirmed by the infrared spectra data where an increase is observed in the SiC stretching vibration mode ascribed to the peak located at around 750cm-1. On the other hand, the films produced by combining hot wire and rf plasma show a more efficient carbon incorporation. The SEM photographs of samples produced with hot wire technique reveal an amorphous structure, confirmed by micro-Raman spectroscopy data, while the samples produced with plasma assisting the process show a granular structure with grain sizes in the range of 100-200nm. © 2002 Elsevier Science Ltd. All rights reserved.

Working teams in enterprise environment are considered as the most advanced forms of work organisation. This means the forms that can improve productivity quality of working life. Nevertheless, it prevail a slow development and dissemination of these advanced organisational forms in European companies. The reason for that lays in a complex linkage factors from social values to the economical pressures. But other factors are also related to the national systems of education training, to the different systems of industrial relations and technology policy.

The structural changes in the heme macrocycle and substituents caused by binding of Ca2+ to the diheme cytochrome c peroxidase from Paracoccus pantotrophus were clarified by resonance Raman spectroscopy of the inactive fully oxidized form of the enzyme. The changes in the macrocycle vibrational modes are consistent with a Ca2+-dependent increase in the out-of-plane distortion of the low-potential heme, the proposed peroxidatic heme. Most of the increase in out-of-plane distortion occurs when the high-affinity site I is occupied, but a small further increase in distortion occurs when site II is also occupied by Ca2+ or Mg2+. This increase in the heme distortion explains the red shift in the Soret absorption band that occurs upon Ca2+ binding. Changes also occur in the low-frequency substituent modes of the heme, indicating that a structural change in the covalently attached fingerprint pentapeptide of the LP heme occurs upon Ca2+ binding to site I. These structural changes may lead to loss of the sixth ligand at the peroxidatic heme in the semireduced form of the enzyme and activation.

The reactivity of mono-substituted HC=CR (R =Ph. a; CH2OH, b; CH2CH2CH2CH3, c) and di-substituted RC=CR (R = CH2CH3, d; CO2CH3, e; Ph. f) acetylenes was studied in supercritical carbon dioxide (scCO(2)) using the easily available complex CpCo(CO)(2) as catalyst. The reaction of phenylacetylene produced a mixture of the isomeric cyclotrimers 1,3,5- (2a) and 1.2,4-triphenylbenzene (2a '). in a 1:5 ratio, and traces of cobaltcyclopentadienone complexes CPCO(eta (4)-C4H2[Ph](2)CO) (6a, mixture of isomers). The possible product formed by the incorporation of CO, to alkynes, i.e. diphenylpyrone (7a) was not observed. The reaction of the cobaltacyclopentadiene complex CpCo(1.4-sigma -C-4[Ph](4))(PPh)(3) (8f), in scCO(2), was performed. No insertion of CO2 into the Co-C a-bond to form tetraphenylpyrone (7f) by reductive elimination was observed, instead the cobaItcyclobutadiene Complex CpCo(eta (4)-C-4[Ph](4)) (9f) was formed. In the reactions with other alkynes, lower yields were obtained in general, except in the cyclotrimerisation of the highly activated alkyne, propargyl alcohol (b). Reaction of the non-activated alkynes, 1-hexyne (c) and 3-hexyne (d), produced complex mixtures of cobalt complexes in low yield in which the alkyne was coordinated to cobalt. Finally, the highly hindered diphenylacetylene (f) gave a mixture of the known Complexes CpCo(eta (4)-C-4[Ph](4)) (9f) and CpCo(eta (4)- C-4[Ph](4)CO) (6f) in agreement with the results observed in conventional organic solvents. (C) 2001 Elsevier Science B.V, All rights reserved.