Immobilization of Catalysts of Biological Interest on Porous Oxidized Silicon Surfaces

The present paper deals with the immobilization of redox mediators and proteins onto protected porous silicon surfaces to obtain their direct electrochemical reactions and to retain their bioactivities. This paper shows that MP-11 and viologens are able to establish chemical bonds with 3-aminopropyltriethoxylsilane-modified porous silicon surface. The functionalization of the surfaces have been fully characterized by energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) to examine the immobilization of these mediators onto the solid surface. Amperometric and open circuit potential measurements have shown the direct electron transfer between glucose oxidase and the electrode in the presence of the viologen mediator covalently linked to the 3-aminopropyltriethoxylsilane (APTES)-modified porous silicon surfaces.

Polyaniline/layered zirconium phosphate nanocomposites: Secondary-like doped polyaniline obtained by the layer-by-layer technique

In the present work, nanocomposites of polyaniline (PANI) and layered alpha-Zr(HPO4)(2).H2O (alpha-ZrP) were prepared using two different approaches: (i) the in situ aniline polymerization in the presence of the layered inorganic material and (ii) the layer-by-layer (LBL) assembly using an aqueous solution of the polycation emeraldine salt (ES-PANI) and a dispersion of exfoliated negative slabs of alpha-ZrP. These materials were characterized spectroscopically using mainly resonance Raman scattering at four exciting radiations and electronic absorption in the UV-VIS-NIR region. Structural and textural characterizations were carried out using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The polymer obtained by the in situ aniline polymerization is located primarily in the external surface of the inorganic material although aniline monomers were intercalated between alpha-ZrP interlayer regions before oxidative polymerization. Through resonance Raman spectroscopy, it was observed that the formed polymer has semiquinone units (ES-PANI) and also azo bonds (-N = N-), showing that this method results in a polymer with a different structure from the usual ""head-to-tail"" ES-PANI. The LBL assembly of pre-formed ES-PANI and exfoliated alpha-ZrP particles produces homogeneous films with reproducible deposition from layer to layer, up to 20 bilayers. Resonance Raman (lambda(0) = 632.8 nm) spectrum of PANI/ZrP LBL film shows an enhancement in the intensity of the polaronic band at 1333 cm(-1) (nu C-N center dot+) and the decrease of the band intensity at 1485 cm(-1) compared to bulk ES-PANI. Its UV-VIS-NIR spectrum presents an absorption tail in the NIR region assigned to delocalized free charge carrier. These spectroscopic features are characteristic of highly conductive secondary doped PANI suggesting that polymeric chains in PANI/ZrP LBL film have a more extended conformation than in bulk ES-PANI.

XPS characterization of sensitized n-TiO2 thin films for dye-sensitized solar cell applications

TiO2 thin films, employed in dye-sensitized solar cells, were prepared by the sol-gel method or directly by Degussa P25 oxide and their surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of adsorption of the cis-[Ru(dcbH(2))(2)(NCS)(2)] dye, N3, on the surface of films was investigated. From XPS spectra taken before and after argon-ion sputtering procedure, the surface composition of inner and outer layers of sensitized films was obtained and a preferential etching of Ru peak in relation to the Ti and N ones was identified. The photoelectrochemical parameters were also evaluated and rationalized in terms of the morphological characteristics of the films. (c) 2007 Elsevier B.V. All rights reserved.

Optical changes and writing on hydrotalcite supported gold nanoparticles

Gold nanoparticles (AuNP) incorporated into hydrotalcite (HT), provide an interesting type of pigment in which temperature can modulate the plasmon resonance and the aggregation phenomenon. As inferred from microscopy techniques, the preferential binding sites are located at the border of the HT external basal surface, leading to aggregates of gold nanoparticles displaying characteristic plasmon resonance and interference bands around 520 and 700 nm, respectively. The thermally induced color changes in the HT-supported gold material arise from the competition between of nanoparticles aggregation and fusion processes, as characterized by TEM and STM. A laser beam can also induce such changes, allowing the writing of optical information on this type of material.

A New Insight on the Preparation of Stabilized Alpha-Nickel Hydroxide Nanoparticles

Nickel hydroxide can provide an outstanding cathode material in alkaline secondary batteries, however the progressive decrease of the charge capacity as a function of the number of oxidation/reduction cycles is a challenging problem to be solved. New improvements on the electrochemical properties of electrode materials can be achieved by exploiting the much better performance of alpha-nickel hydroxide. Such materials were obtained in a stable form by sol-gel method and characterized by thermogravimetric analyses, UV-Vis spectroscopy, X-ray diffractometry, scanning and transmission electron microscopy, cyclic voltammetry and electrochemical quartz crystal microbalance techniques. The results revealed not only the formation of the alpha-Ni(OH)(2) phase, but also a much better electrochemical reversibility and stability as compared with similar materials obtained by electrochemical precipitation method.

Electrical and optical properties of poly(2-dodecanoylsulfanyl-p-phenylenevnylene) and its application in electroluminescent devices

We describe the optical and electrical characterization of a poly(p-phenylenevinylene) derivative: poly(2-dodecanoylsulfanyl-p-phenylenevinylene) (12COS-PPV). The electrical characterization was carried out on devices with the FTO\PEDOT:PSS\12COS-PPV/Al structure. Positive charge carrier mobility mu(h) of similar to 1.0 x 10(-6) cm(2) V(-1) s(-1) and barrier height phi of similar to 0.1 eV for positive charge carrier injection at the PEDOT:PSS/12COS-PPV interface were obtained using a thermionic injection model. FTO\PEDOT:P55\12COS-PPV/Ca devices exhibited green-yellow electroluminescence with maximum emission at lambda = 540 nm.

Using Polycarbonate Membranes as Templates for the Preparation of Au Nanostructures for Surface-Enhanced Raman Scattering

Polycarbonate membranes (PCM) of various pores sizes (400, 200, 100 and 50 nm) were used as templates for gold deposition. The electrodeposition from gold ions resulted in the formation of gold nanotubes when large pores size PCMs (400 and 200 nm) were used. On the other hand, gold nanowires were predominant for the PCMs with smaller pores size (100 and 50 nm). Surface-enhanced Raman scattering (SERS) from the probe molecule 4-mercaptopyridine (4-MPy) was obtained from all these nanostructures. The SERS efficiency of the substrates produced using the PC M templates were compared to two commonly used SERS platforms: a roughened gold electrode and gold nanostructures electrodeposited through organized polystyrene spheres (PSS). The SERS signal of the probe molecule increased as the pore diameter of the PCM template decreased. Moreover, the SERS efficiency from the nanostructures produced using 50 nm PCM templates was four and two times better than the signal from the roughened gold electrode and the PSS template, respectively. The SERS substrates prepared using PCM templates were more homogenous over a larger area (ca. 1 cm(2)), presented better spatial and sample to sample reproducibility than the other substrates. These results show that SERS substrates prepared using PCM templates are promising for the fabrication of planar SERS platforms for analytical/bioanalytical applications.

Effects of hydroxyl group distribution on the reactivity, stability and optical properties of fullerenols

We investigate the impact of hydroxyl groups on the properties of C(60)(OH)(n) systems, with n = 1, 2, 3, 4, 8, 10, 16, 18, 24, 32 and 36 by means of first-principles density functional theory calculations. A detailed analysis from the local density of states has shown that adsorbed OH groups can induce dangling bonds in specific carbon atoms around the adsorption site. This increases the tendency to form polyhydroxylated fullerenes (fullerenols). The structural stability is analyzed in terms of the calculated formation enthalpy of each species. Also, a careful examination of the electron density of states for different fullerenols shows the possibility of synthesizing single molecules with tunable optical properties.

Electrodeposition and characterization of thin selenium films modified with lead ad-atoms

The deposition and characterization of Se films doped with Pb underpotentially deposited (UPD) ad-atoms was studied in this work. The employed experimental techniques were cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, UV-vis spectroscopy and atomic force microscopy. The initial deposition of Se film by chronoamperometry yielded a thin film composed of approximately 700 layers. The Pb UPD on Se was achieved by chronoamperometry in a potential value previously determined in voltammetric experiments. This deposition yielded a deposition charge of approximately 7.5% of the total one. The film resistance altered from 320 Omega cm(2) for Se to 65 Omega cm(2) for the Se/Pb one. Flat band potential values and number of acceptors and donors were also calculated for both films and the values obtained were + 0.95 and -0.51 V for Se and Se/Pb, respectively. The Se coating presented 1.2 x 10(17) cm(3) acceptors while the Se/Pb one presented 3.2 x 10(17) cm(3) donors. The band gap values for both films were 2.4 eV and 1.9 eV, correspondingly. (C) 2008 Elsevier B.V. All rights reserved.

Perpendicularly self-oriented and shape-controlled L1(0)-FePt nanorods directly synthesized by a temperature-modulated process

The synthesis and self-assembly of tetragonal phase-containing L1(0)-Fe(55)Pt(45) nanorods with high coercive field is described. The experimental procedure resulted in a tetragonal/cubic phase ratio close to 1:1 for the as-synthesized nanoparticles. Using different surfactant/solvent proportions in the process allowed control of particle morphology from nanospheres to nanowires. Monodisperse nanorods with lengths of 60 +/- 5 nm and diameters of 2-3 nm were self-assembled in a perpendicular oriented array onto a substrate surface using hexadecylamine as organic spacer. Magnetic alignment and properties assigned, respectively, to the shape anisotropy and the tetragonal phase suggest that the self-assembled materials are a strong candidate to solve the problem of random magnetic alignment observed in FePt nanospheres leading to applications in ultrahigh magnetic recording (UHMR) systems capable of achieving a performance of the order of terabits/in(2).

Selective photoinactivation of C. albicans and C. dubliniensis with hypericin

The genus Candida includes different species that have the potential to invade and colonize the human body and C. albicans is the most common cause of skin, nail and mucous infections. The increasing resistance against antifungal drugs has renewed the search for new treatment procedures and antimicrobial photodynamic inactivation (PDI) is a propitious candidate. Hypericin (HY) has several wanted properties to be used as a photosensitizer in this technique including a high quantum yield of singlet oxygen generation, a high extinction coefficient near 600 nm, and a relatively low dark toxicity. Although the phototoxicity of HY on several tumor cells has been reported, the data concerning its photoactivity on microorganisms are scarce. The aim of this study was to obtain the experimental parameters to achieve an acceptable selective hypericinphotoinactivation of two species of Candida comparing with fibroblasts and epithelial cells which are the constituents of some potential host tissues, such mucosas, skin and cavities. Microorganisms and cells were incubated with the same HY concentrations and short incubation time followed by irradiation with equal dose of light. The best conditions to kill just Candida were very low HY concentration (0.1-0.4 mu g ml(-1)) incubated by 10 min and irradiated with LED 590 nm with 6 J cm(-2).

Organic additive-copper(II) complexes as plating precursors

Cu(II) ions previously coordinated with typical electroplating organic additives were investigated as an alternative source of metal for plating bath. The coordination complexes were isolated from reaction between CuSO(4) and organic additives as ligands (oxalate ion, ethylenediamine or imidazole). Deposits over 1010 steel were successfully obtained from electroplated baths using the complexes without any addition of free additives, at pH = 4.5 (H(2)SO(4)/Na(2)SO(4)). These deposits showed better morphologies than deposits obtained from CuSO(4) solution either in the absence or presence of oxalate ion as additive (40 mmol L(-1)), at pH = 4.5 (H(2)SO(4)/Na(2)SO(4))It is suggestive that the starting metal plating coordinated with additives influences the electrode position processes, providing deposits with corrosion potentials shifted over + 200 mV in 0.5 mol L(-1) NaCl (1 mV s(-1)). The resistance against corrosion is sensitive to the type of additive-complex used as precursor. The complex with ethylenediamine presented the best deposit results with the lowest pitting potential (-0.27 V vs 3.0 mol L(-1) CE). It was concluded that the addition of free additives to the electrodeposition baths is not necessary when working with previously coordinated additives. Thus, the complexes generated in ex-situ are good alternatives as plating precursors for electrodeposition bath. (C) 2009 Elsevier B.V. All rights reserved.

Hirsch's index: a case study conducted at the Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo

An analysis of scientific bibliographic productivity using the Hirsch h-index, information from the Institute of Scientific Information database and the Curriculum Lattes (CNPq, Brazil) was performed at the Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (FFCLRP-USP) that has four departments in natural, biological and social sciences. Bibliometric evaluations of undergraduate programs showed a better performance of the departments of Chemistry (P < 0.001) and Biology (P < 0.001) when compared to the departments of Physics and Mathematics and Psychology and Education. We also analyzed the scientific output of the six graduate programs of FFCLRP: Psychology, Psychobiology, Chemistry, Physics Applied to Medicine and Biology, Comparative Biology, and Entomology. The graduate program in Psychology presented a lower h-index (P < 0.001) and had fewer papers indexed by the ISI web of science (P < 0.001) when compared to the other graduate programs. The poorer performance of the Psychology program may be associated with the limited coverage by the Thompson Institute of Scientific Information database.

Cirurgia a laser e anestesia

JUSTIFICATIVA E OBJETIVOS: As cirurgias com a utilização do laser apresentam riscos para o paciente e para a equipe médica. O objetivo deste artigo é apresentar noções básicas sobre o laser e regras para aumentar a segurança dos procedimentos com sua utilização. CONTEÚDO: O presente artigo contém noções de física aplicadas ao laser, regras de segurança e a conduta em caso de ocorrência de eventos adversos com a utilização do laser. CONCLUSÕES: Concluímos que, quando manipulado por profissionais treinados, e respeitadas as normas de segurança, o laser é útil e seguro, tanto para o paciente quanto para a equipe médica.

Produção científica na faculdade de filosofia, ciencias e letras de ribeirao preto-usp: Apliçãcao do índice de hirsch

In this work, an analysis of scientific bibliographic productivity was made using the Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo (FFCLRP-USP) as example. It is a special Institution in the Brazilian University system which encompasses four important areas of knowledge (fields of concentration) in natural, biological, humanities, and social areas. It is composed by four departments which offer altogether eight undergraduate courses: 1) Psychology, 2) Pedagogy, 3) Chemistry, 4) Biology, 5) Medical Physics, 6) Biomedical Informatics, 7) Sciences of Information and Documentation and 8) Mathematics Applied to Business and six graduate programs leading to M.S. and Ph.D. degrees. Moreover, when analyzing the different courses of FFCLRP, they represent typical academic organization in Brazil and Latin America and could be taken as a model for analyzing other Brazilian research institutions. This analysis was made using: 1) the total number of papers (indexed in Curriculum Lattes database), 2) the number of papers indexed by Thomson ISI Web of Science database, and 3) the Hirsch (h-index). Bibliometric evaluations of undergraduate courses showed a better performance of the courses of Chemistry (P < 0.05), Biology (P < 0.05) and Medical Physics (P < 0.05) when compared to the Pedagogy, Sciences of Information and Documentation (P < 0.05) and Psychology (P < 0.05). We also analyzed the scientific output of the six graduate programs of FFCLRP-USP: 1) Chemistry, 2) Physics Applied to Medicine and Biology, 3) Entomology, 4) Compared Biology, 5) Psychology, 6) Psychobiology. The graduate programs in Psychobiology, Chemistry, Physics Applied to Medicine and Biology, Compared Biology, and Entomology presented very similar results, concerning the assessment of the three indexes. The graduate program in Psychology presented a lower h-index (P < 0.05) and had fewer papers indexed by the ISI (P < 0.05) when compared to the other graduate programs. The worse performance of the psychology program, pedagogy, sciences of information and documentation, psychology courses may be associated to the limited coverage of ISI database and some particular characteristics of this field of concentration.