Vibrational spectra and surface-enhanced resonance Raman scattering of palladium phthalocyanine evaporated films

The vibrational spectra of palladium phthalocyanine (PdPc) evaporated thin solid films are reported, including the resonance Raman scattering, surface-enhanced resonance Raman scattering (SERRS) and SERRS mapping of the film surface using micro-Raman spectroscopy with 633 nm laser radiation. SERRS of PdPc was obtained by evaporating an overlayer of Ag nanoparticles on to the PdPc film on glass. The SERRS enhancement factor is estimated as similar to10(4) with reference to PdPc evaporated films on glass. The molecular organization of the PdPc evaporated films was probed using transmission and reflection-absorption infrared spectra. It was established that a random molecular distribution found in PdPc evaporated films is independent of temperature. No evidence of thermal degradation due to thermal annealing was found in the films. Electronic absorption and emission spectra are also discussed. Copyright (C) 2002 John Wiley Sons, Ltd.

Structural and surface properties of thermally prepared Ti/RhxTi(1-x)Oy electrodes: I - influence of preparation parameters

Electrodes of RhxTi(1-x) O-y nominal composition were prepared by thermal decomposition of the chloride or nitrate precursor salts dissolved in strongly acidic medium and applied by brush to both sides of a Tidegrees support. A systematic study of the influence of calcination temperature and time as well as oxygen flux was conducted. The coatings were characterised by SEM, EDAX, XRD, open circuit potential measurements and cyclic voltammetry (CV). Visible-ultraviolet spectrophotometry was employed to identify the chemical form of the precursor in solution while thermogravimetric analysis (TGA) was used to assess the decomposition temperature ranges. Optimisation of the coating preparation parameters showed coatings obtained from [Rh(H2O)(6)](NO3)(3) precursor dissolved in HNO3 1:2 (v/v) and fired at 430 degreesC for 2 h in a 5 1 min (-1) oxygen stream-furnished stable electrodes having the highest electrochemically active surface area. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Fmoc-POAC: [(9-fluorenylmethyloxycarbonyl)-2,2,5,5-tetramethylpyrrolidine-N-oxyl-3-amino-4-carboxylic acid]: A novel protected spin labeled beta-amino acid for peptide and protein chemistry

The stable free radical 2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid (TOAC) is the only spin labeled amino acid that has been used to date to successfully label peptide sequences for structural studies. However, severe difficulty in coupling the subsequent amino acid has been the most serious shortcoming of this paramagnetic marker. This problem stems from the low nucleophilicity of TOAC's amine group towards the acylation reaction during peptide chain elongation. The present report introduces the alternative beta -amino acid 2,2,5,5-tetramethylpyrrolidine-N-oxyl-3-amino-4-carboxylic acid (POAC), potentially useful in peptide and protein chemistry. Investigations aimed at addressing the stereochemistry of this cyclic molecule through X-ray diffraction measurements of crystalline and bulk samples revealed that it consists only of the trans conformer. The 9-fluorenylmethyloxyearbonyl group (Fmoc) was chosen for temporary protection of the POAC amine function, allowing insertion of the probe at any position in a peptide sequence. The vasoactive octapeptide angiotensin II (AII, DRVYIHPF) was synthesized by replacing Pro(7) with POAC. The reaction of Fmoc-POAC with the peptidyl-resin occurred smoothly, and the coupling of the subsequent amino acid showed a much faster reaction when compared with TOAC. POAC(7)-AII was obtained in good yield, demonstrating that, in addition to TOAC, POAC is a convenient amino acid for the synthesis of spin labeled peptide analogues. The present findings open the possibility of a wide range of chemical and biological applications for this novel beta -amino acid derivative, including structural investigations involving its differentiated bend-inducing characteristics.

Molecular engineering strategies to control photo-induced birefringence and surface-relief gratings on layer-by-layer films from an azopolymer

The interactions governing adsorption of layer-by-layer (LBL) films from an azopolymer, PS-119(R), and poly(allylamine hydrochloride) (PAH) have been controlled by modifying the pH of the solutions used to form the films. The thickness per bilayer was varied by one order of magnitude, from 10 to 240 A, as the pH changed from 4 to 10. Thick layers were formed at higher pHs because in this case the PAH is only partially charged adopting a loopy conformation. This change in molecular conformation caused the kinetics of isomerization and mass transport to be much slower than at lower pHs. The writing time defined as the time to achieve 50% of maximum birefringence dropped from 110 to 18 min for films prepared from solutions with pH 10 and pH 4, respectively. This decrease is probably due to the higher free volume for isomerization in the films prepared at lower pHs, in which PAH molecules are less coiled than at higher pHs. For the same reason, the rate of inscription of surface-relief gratings with an interference pattern of p-polarized light was also much slower at higher pHs. (C) 2003 Elsevier B.V. All rights reserved.

Film formation and surface growth on tin electrodes in bicarbonate solutions: an impedance spectroscopy study

The electrochemical behaviour of potentiodynamically formed thin anodic films of polycrystalline tin in aqueous sodium bicarbonate solutions (pH approximate to 8.3) were studied using cyclic voltammetry and electrochemical impedance spectroscopy. Different equivalent circuits corresponding to various potential regions were employed to account for the electrochemical processes taking place under each condition. (C) 2004 Elsevier Ltd. All rights reserved.

Renal Evaluation of Aotus azarai infulatus by Ultrasonography and Serum Chemistry Profile

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aerosol and precipitation chemistry measurements in a remote site in Central Amazonia: the role of biogenic contribution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and surface morphology characterizations of oriented LiNbO3 thin films grown by polymeric precursor method

Polymeric precursor solution was used to deposit LiNbO3 thin films by dip coating on sapphire substrates. The effects of processing variables, such as heat treatment conditions and number of deposited layers, on crystallinity and morphology of the final films were investigated. X-ray diffraction patterns show the oriented growth of the films. The rocking curves, obtained around the (006) LiNbO3 peak, revealed that the shape peak and the FWHM value were influenced by the processing variables. According to these parameters, some films presented very homogeneous dense and smooth surfaces, as shown by the SEM and AFM studies.

Compositional modulation and surface stability in InGaP films: Understanding and controlling surface properties

We investigate the formation of compositional modulation and atomic ordering in InGaP films. Such bulk properties - as well as surface morphologies - present a strong dependence on growth parameters, mainly the V/III ratio. Our results indicate the importance of surface diffusion and, particularly, surface reconstruction for these processes. Most importantly from the application point of view, we show that the compositional modulation is not necessarily coupled to the surface instabilities, so that smooth InGaP films with periodic compositional variation could be obtained. This opens a new route for the generation of templates for quantum dot positioning and three-dimensional arrays of nanostructures. © 2007 American Institute of Physics.

Hematological and serum chemistry values for the ring-necked pheasant (Phasianus colchicus): Variation with sex and age

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of hardness and surface roughness of two maxillofacial silicones following disinfection

The purpose of this study was to evaluate the Shore A hardness and surface roughness of two silicones for maxillofacial prosthetic treatment, under the influence of chemical disinfection and storage. Twenty-eight specimens were obtained, half of which were made of Silastic MDX 4-4210 silicone and, the other half were made of Silastic 732 RTV silicone. The specimens were divided into four groups: Silastic 732 RTV and MDX 4-4210 with disinfection 3 times a week with Efferdent tablets and the same materials without disinfection. The hardness of the materials was analyzed with a Shore A Durometer. The surface roughness was established by a digital portable roughness tester, initially and 2 months after the confection of the specimens. A variance test was applied (2-way ANOVA), followed by Tukey test (the level of significance was set at 1%). The storage time factor statistically influenced (p < 0.01) the materials' properties of hardness and roughness. MDX 4-4210 (28.59 Shore A, 0.789 Ra) presented higher values than Silastic 732 RTV (18.08 Shore A, 0.656 Ra) for both properties. Regarding the disinfection period, there was no significant difference in any of the materials tested. © 2009 Sociedade Brasileira de Pesquisa Odontológica.

Effect of green machining on distortion and surface finishing in advanced ceramic

An alternative for grinding of sintered ceramic is the machining on the green state of the ceramic, which presents easy cutting without the introduction of harmful defects to its mechanical resistance. However, after sintering there are invariably distortions caused by the heterogeneous distribution of density gradients, which are located in the most outlying portions of the compacted workpiece. In order to minimize these density gradients, this study examined the influence of different allowance values and their corresponding influence in distortion after sintering alumina specimens with 99.8 % purity by turning operation using cemented carbide tool. Besides distortion, other output variables were analyzed, such as tool wear, cutting force and surface roughness of green and sintered ceramics. Results showed a distortion reduction up to 81.4%. Green machining is beneficial for reducing surface roughness in both green and sintered states. Cutting tool wear has a direct influence on surface roughness and cutting force.

Antimicrobial activity and surface properties of an acrylic resin containing a biocide polymer

Objective: To evaluate the antimicrobial activity and surface properties of an acrylic resin containing the biocide polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA). Background: Several approaches have been proposed to prevent oral infections, including the incorporation of antimicrobial agents to acrylic resins. Materials and methods: Specimens of an acrylic resin (Lucitone 550) were divided into two groups: 0% (control) and 10% PTBAEMA. Antimicrobial activity was assessed by adherence assay of one of the microorganisms, Staphylococcus aureus, Streptococcus mutans and Candida albicans. Surface topography was characterised by atomic force microscopy and wettability properties determined by contact angle measurements. Results: Data of viable cells (log (CFU + 1)/ml) for S. aureus (control: 7.9 ± 0.8; 10%: 3.8 ± 3.3) and S. mutans (control: 7.5 ± 0.7; 10%: 5.1 ± 2.7) showed a significant decrease with 10% of PTBAEMA (Mann-Whitney, p < 0.05). For C. albicans (control: 6.6 ± 0.2; 10%: 6.6 ± 0.4), there was no significant difference between control and 10% of PTBAEMA (Kruskal-Wallis, p > 0.05). Incorporating 10% PTBAEMA increased surface roughness and decreased contact angles. Conclusion: Incorporating 10% PTBAEMA into acrylic resins increases wettability and roughness of acrylic resin surface; and decreases the adhesion of S. mutans and S. aureus on acrylic surface, but did not exhibit antimicrobial effect against C. albicans. © 2012 The Gerodontology Society and John Wiley & Sons A/S.