Rare earth doped HfO2 nanoparticles embedded in SiO2-HfO2 planar waveguides. Preparation, optical, structural and spectroscopic characterization

In this work we present results on the preparation of planar waveguides based on HfO2 and HfO2-SiO2. Stable sols containing europium and erbium doped HfO2 nanoparticles have been prepared and characterized. The nanosized sol was either deposited (spin-coating) on quartz substrates or embedded in (3-glycidoxipropil)trimethoxisilane (GPTS) used as a hybrid host for posterior deposition. The refractive index dispersion and luminescence characteristics were determined for the resulting HfO2 films. The optical parameters of the waveguides such as refractive index, thickness and propagation losses were measured for the hybrid composite. The planar waveguides present thickness of a few micra and support well confined propagating modes.

Electrocatalytic and voltammetric determination of sulfhydryl compounds through iron nitroprusside modified graphite paste electrode

Iron nitroprusside Fe(II)NP was incorporated into a carbon paste electrode and the electrochemical studies were performed with cyclic voltammetry. The cyclic voltammogram of Fe(II)NP exhibits two redox couple with formal potential (E0')1 = 0.24 e (E0')2 = 0.85 V vs SCE attributed to Fe(II)/Fe(II) and Fe (II)(CN)5NO/Fe(III)(CN)5NO, respectively. The redox couple with (E0')2 = 0.85 V presents an electrocatalytic response for sulfhydryl compounds. The electrocatalytic oxidation of sulfhydryl compounds by the mediator has been used for the determination of L-cysteine and N-acetylcysteine. The modified graphite paste electrode gives a linear range from 9.2 x 10-4-2.0 x 10-2;; 9.6 x 10-4-1.4 x 10-2mol L-1 for the determination of L-cysteine and N-acetylcysteine, respectively, with detection limit of 1.9 x 10-4 mol L-1;; 1.5 x 10 -4 mol L-1 and relative standard desviations ± 5% and 1.5 x 10-3 mol L-1 ± 4% (n=3). The amperometric sensitivities are 0.024 and 0.027 μA/μmol L-1 for L-cysteine and N-acetylcysteine, respectively. The application of this electrode was tested and a commercial pharmaceutical product (Fluimucil) has been determined.

Thermal Behavior and Spectroscopic Study of Neutral and Cationic Mononuclear Cyclopalladated Compounds

The reactions of the precursor [Pd(N,C-dmba)(MeCN)2](NO 3) (1) (dmba = N,N-dimethylbenzylamine), with the proligands 3,5-dimethylpyrazole (Hdmpz), 2-quinolinethiol (qnSH) and 1,1′- bis(diphenylphosphine)ferrocene (dppf) afforded the compounds [Pd(N,C-dmba)(Hdmpz)(ONO2)]0.5CH2Cl2 (2), [Pd(N,C-dmba)(qnSH)(ONO2)] 0.5CH2Cl2 (3) and [Pd(N,C-dmba)(dppf)](NO3) (4), respectively. The mononuclear species 2,3 and 4 were characterized by elemental analysis, infrared spectroscopy, NMR and thermogravimetric analysis. The IR spectra show bands which are consistent with terminal monodentate nitrate group for 2-3 and ionic nitrate for 4. The 1H and 13C NMR data confirm that coordination of the organic ligands has occurred and the 31P{1H} NMR data for 4 clearly evidences the occurrence in solution of three cyclopalladated species with the dppf acting as a bridging ligand in two cases and as a chelate in one. The thermal behavior of compounds 1-4 suggests that complex 2 is the most stable. The X-ray diffractometry results show the formation of PdO from 1 and 2, Pd2OSO4 from 3, and of a mixture of PdO and Fe 2(PO4)3 from 4, as final decomposition products.

Serum iron analysis of adults receiving three different iron compounds

Iron deficiency is one of the most prevalent nutritional problems in the world. Iron compounds are used for the prevention and treatment of this deficiency. A double-blind randomized crossover study with 12 volunteers was carried out to compare the effect of three iron compounds, ferrous glycine chelate (GLY), ferric EDTA (EDTA), and ferrous sulfate (FS) on serum iron, and to examine serial serum iron levels. The products were offered as tablets, and blood samples were drawn hourly for 4 hours. FS produced higher serum iron levels than EDTA or GLY (P <0.05). Data for GLY and EDTA were similar. The areas under the curve (AUC) for serum iron for the different compounds gave AUCFS > AUCGLY = AUCEDTA (P < 0.05). Iron from FS had a significantly greater bioavailability than for the other two compounds. © 2004 Elsevier Inc. All rights reserved.

Synthesis, characterization and thermal behaviour of solid-state compounds of 4-methoxybenzoate with some bivalent transition metal ions

Solid-state M-4-MeO-Bz compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to have information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds. © 2005 Akadémiai Kiadó, Budapest.

Evaluation of the effects of different extraction methods for main volatile compounds from Bambusa textilis leaves

Bambusa textilis is widely used in popular medicine to treat all kinds of wound inflammation, chronic fever, pulmonary and infectious diseases. The aim of this study was to compare the chemical composition of the extracts of B. textilis leaves obtained by three different extraction methods: solid/liquid extraction, Soxhlet and Clevenger system using gas chromatography with flame ionization detector (GC-FID) and gas chromatography with mass spectrometry (GC-MS) analyses. The analytical characteristics of the extracts showed some differences and the GC-MS analysis indicated the presence of higher concentrations of nitro compounds and alkalis. © VSP 2005.

Central nifedipine-induced alterations in salivary flow and compounds: Role of nitric oxide

The aim of this study was to examine the role of nifedipine and Nitric Oxide (NO) on salivary flow and compounds (salivary amylase, saliva total proteins, saliva calcium, sodium and potassium). Male Holtzman rats weighting 200-250 g were anesthetized with zoletil 50 mg kg -1 (tiletamine chloridrate 125.0 mg and zolazepan chloridrate 125.0 mg) into quadriceps muscle and stainless steel cannulas were implanted into their lateral ventricle of the brain (LV). Animals in divided group were injected with nifedipine (50 μg μL -1) alone and in combination with 7-nitroindazol (7-NIT) (40 μg μL -1), neuronal NO Sinthase Inhibitor (nNOSI) and Sodium Nitroprussate (SNP) (30 μg μL -1) NO donor agent. As a secretory stimuli, pilocarpine dissolved in isotonic was administered intraperitoneally (ip) at a dosage of 10 mg kg -1 body weight. Saliva was collected for 7 min with four cotton balls weighing approximately 20 mg each, two of which were placed on either side of the oral cavity, with the other two placed under the tongue. Nifedipine treatment induced a reduction in saliva secretion rate and concentration of amylase, total protein and calcium without changes in sodium and potassium concentration in comparison with controls. Co-treatment of animals with nifedipine and SNP retained flow rate and concentration of amylase, total protein and calcium in normal levels. Co-treatment of animals with nifedipine and 7-NIT potentiated the effect of nifedipine on the reduction of saliva secretion and concentrations of amylase, total protein and calcium. Nifedipine (dihydroperidine) calcium-channel blocker widely in use is associated with salivary dysfunction acting in the central nervous system structures. NO might be the mechanism for protective effect against the nifedipine-induce salivary dysfunction, acting in the CNS. © 2006 Asian Network for Scientific Information.

Antimicrobial endodontic compounds do not modulate alkylation-induced genotoxicity and oxidative stress in vitro

Objective: To investigate if formocresol, paramonochlorophenol, or calcium hydroxide modulate the genotoxic effects induced by the oxidatively damaging agent hydrogen peroxide (H 2O 2) or the alkylating agent methyl methanesulfonate (MMS) in vitro by using single cell gel (comet) assay. Study design: Chinese hamster ovary (CHO) cells in culture were exposed directly to formocresol, paramonochlorophenol, or calcium hydroxide (adjusted to 100 μg/mL) for 1 hour at 37°C. Subsequently the cultures were incubated with increasing concentrations (0-10 μmol/L) of MMS in phosphate-buffered solution (PBS) for 15 minutes at 37°C or of H 2O 2 at increasing concentrations (0-100 μmol/L) in distilled water for 5 minutes on ice. The negative control cells were treated with PBS for 1 hour at 37°C. The parameter from the comet assay (tail moment) was assessed by the Kruskal-Wallis nonparametric test followed by a post hoc analysis (Dunn test). Results: Clear concentration-related effects were observed for the genotoxin-exposed CHO cells. Increase of MMS-induced DNA damage was not significantly altered by the presence of the compounds tested. Similarly, no significant changes were observed when hydrogen peroxide was used with the endodontic compounds evaluated. Conclusion: Formocresol, paramonochlorophenol, and calcium hydroxide are not able to modulate alkylation-induced genotoxicity or oxidative DNA damage as depicted by the single cell gel (comet) assay. © 2006 Mosby, Inc. All rights reserved.

Amphibian secretions for drug discovery studies: A search for new antiparasitic and antifungal compounds

The antiparasitic and antifungal activities of nine amphibian skin secretions were studied in different in vitro models. Seven secretions presented a considerable antiprotozoan activity and one showed promising results against Candida sp. These results can be the basis for the development of new drugs, especially for neglected parasitic diseases. © 2007 Bentham Science Publishers Ltd.

Citotoxicity and immune response induced by organopalladium(II) compounds in mice bearing Ehrlich ascites tumour

Cyclometallated palladium(II) complexes are reactive inorganic compounds employed in several biological studies because of their antitumour potential and interaction with immune system. In the present study, the immune and citotoxic response induced by two organopalladated complexes: [{Pd(N,C-dmba)} 2(μ-NCS) 2] (1), [Pd(C-dmba)(NCS)(dppp)] (2) [dmba = N,N′-dimethylbenzylamine, dppp = 1,3-bis(diphenylphosphino)propane] and cisplatin (cis-DDP), as standard, were investigated in mice bearing Ehrlich ascites tumour. The mice were divided into five groups and inoculated with the compounds (1) or (2) or cisplatin, or only vehicle or phosphate-buffered saline (PBS). Many parameters were evaluated, such as tumour cell percentage in the peritoneal exsudate, levels of seric nitric oxide (NO) and tumour necrosis factor-alpha (TNF-α) and increase in life span. Analysis of all data revealed, for compound (2), an activity similar to that presented by cisplatin, resulting in increased life span, lower levels of seric TNF-α and increase in NO production. ©2007 Sociedade Brasileira de Química.

Comparative study of disk diffusion and microdilution methods for evaluation of antifungal activity of natural compounds against medical yeasts Candida spp and Cryptococcus sp

Antifungal activity of natural products has been tested by adapting methods designed for synthetic drugs. In this study, two methods for the determination of antifungal activity of natural products, agar diffusion and broth microdilution, the CLSI reference methods for synthetic drugs, are compared and discussed. The microdilution method was more sensitive. The minimal inhibitory concentrations (MIC) of crude extracts, fractions and pure substances from different species of the plant families Piperaceae, Rubiaceae, Clusiaceae, Fabaceae and Lauraceae, from the Biota project, were determined. Antifungal activities against Candida albicans, C.krusei, C.parapsilosis and Cryptococcus neoformans were produced by several samples.

Evaluation of two mineral trioxide aggregate compounds as pulp-capping agents in human teeth

Aim: The present randomized, controlled prospective study evaluated the histomorphological response of human dental pulps capped with two grey mineral trioxide aggregate (MTA) compounds. Methodology: Pulp exposures were performed on the occlusal floor of 40 human permanent pre-molars. The pulp was capped either with ProRoot (Dentsply) or MTA-Angelus (Angelus) and restored with zinc oxide eugenol cement. After 30 and 60 days, teeth were extracted and processed for histological examination and the effects on the pulp were scored. The data were subjected to Kruskal-Wallis and Conover tests (α = 0.05). Results: In five out of the 40 teeth bacteria were present in pulp tissue. No significant difference was observed between the two materials (P > 0.05) in terms of overall histological features (hard tissue bridge, inflammatory response, giant cells and particles of capping materials). Overall, 94% and 88% of the specimens capped with MTA-Angelus and ProRoot, respectively, showed either total or partial hard tissue bridge formation (P > 0.05). Conclusions: Both commercial materials ProRoot (Dentsply) and MTA-Angelus (Angelus) produced similar responses in the pulp when used for pulp capping in intact, caries-free teeth. © 2009 International Endodontic Journal.

Immunostimulatory effects of the phenolic compounds from lichens on nitric oxide and hydrogen peroxide production

The effects of isolated compounds from Brazilian lichens and their derivatives on H 2O 2 and NO production were studied using murine macrophages as a part of an attempt to understand their possible immunomodulatory properties. The compound cytotoxicity was studied using MTT assay. Macrophage stimulation was evaluated by the determination of NO (Griess assay) and H 2O 2 (horseradish peroxidase/phenol red) in supernatants of peritoneal macrophage cultures of Swiss mice. This research demonstrated stimulatory activities of some phenolic compounds isolated from lichens and their derivatives on H 2O 2 and NO production. Structure-activity relationships suggest several synthetic directions for further improvement of immunological activity.

Thermal behaviour of succinic acid, sodium succinate and its compounds with some bivalent transitions metal ions in dynamic N 2 and CO 2 atmospheres

Thermal stability and thermal decomposition of succinic acid, sodium succinate and its compounds with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA) in nitrogen and carbon dioxide atmospheres and TG-FTIR in nitrogen atmosphere. On heating, in both atmospheres the succinic acid melt and evaporate, while for the sodium succinate the thermal decomposition occurs with the formation of sodium carbonate. For the transition metal succinates the final residue up to 1180 °C in N 2 atmosphere was a mixture of metal and metal oxide in no simple stoichiometric relation, except for Zn compound, where the residue was a small quantity of carbonaceous residue. For the CO 2 atmosphere the final residue up to 980 °C was: MnO, Fe 3O 4, CoO, ZnO and mixtures of Ni, NiO and Cu, Cu 2O.

Nanoscale effects and polaronic relaxation in CaCu3Ti 4O12 compounds

In the present communication, by using dielectric spectroscopy measurement, the correlations between Nanosized Barrier Layer Capacitance (NBLC) (Bueno et al. (2009) [7]) and the high frequency polaronic near-Debye dipolar relaxation found in CaCu3Ti4O12 compounds was discussed. The polaronic process was confirmed to be closely associated with the ultrahigh dielectric features of CaCu3Ti4O12 materials and its concomitant dielectric loss. Herein, the shift in relaxation frequency as a function of temperature was used for calculating the activation energy for hopping electronic conduction. The value obtained was 33 meV, an energy whose magnitude is compatible and confirmed the hypothesis of polaronic features for this high frequency dipolar relaxation process. Furthermore, it is shown that the nanosized barrier inferred from the NBLC model has a polaronic feature with dielectric permittivity exiting orthogonally to dielectric loss, a phenomenological pattern that contradicts the normally observed behavior for traditional dielectrics but explain the dielectric and conductivity feature of CaCu3Ti4O12 compounds. © 2010 Elsevier Ltd. All rights reserved.