Unusual redox behaviour of the magnetite/hematite core-shell structures processed by the laser floating zone method.

Magnetite (Fe3O4) offers unique physical and chemical properties, being an important material for many industrial applications. Certain limitations on the application conditions are, however, imposed by the redox stability issue. Fine control of the iron oxidation states represents a challenge for materials engineering. The present work explores relevant redox processes in iron oxides, processed under highly non-equilibrium laser floating zone (LFZ) conditions under atmospheres with different oxygen activities. The as-grown fibres showed a structure composed of the Fe3O4 core and the Fe2O3 shell. This study uncovers unexpectedly lower hematite content and shell thickness for the fibres processed under more oxidizing conditions. Combined structural and microstructural studies, supported by the analysis of the existing literature data, strongly suggest that the redox processes during the LFZ process can be rather determined by kinetics of melt crystallization, nuclei formation and heat transfer than by the oxygen content in the gas phase. The proposed mechanisms are further confirmed by electrical and magnetic studies of the composite fibres.

Nucleation, Growth Mechanism, and Controlled Coating of ZnO ALD onto Vertically Aligned N-Doped CNTs.

Zinc oxide thin films were deposited on vertically aligned nitrogen-doped carbon nanotubes (N-CNTs) by atomic layer deposition (ALD) from diethylzinc and water. The study demonstrates that doping CNTs with nitrogen is an effective approach for the "activation" of the CNTs surface for the ALD of metal oxides. Conformal ZnO coatings are already obtained after 50 ALD cycles, whereas at lower ALD cycles an island growth mode is observed. Moreover, the process allows for a uniform growth from the top to the bottom of the vertically aligned N-CNT arrays. X-ray photoelectron spectroscopy demonstrates that ZnO nucleation takes place at the N-containing species on the surface of the CNTs by the formation of the Zn-N bonds at the interface between the CNTs and the ZnO film.

Toxic effects of the administration of Mikania glomerata Sprengel during the gestational period of hypertensive rats.

Herbal medicine is an ancient practice that has been gaining acceptance of the medical class through scientific studies that prove its effectiveness. However, its use should still be cautious. Medicinal plants have potential toxic effects not yet discovered, and may have unproven interactions with other medications. The use of drugs during pregnancy is still very dangerous and vigorously studied; however, there are few studies of herbal medicines in pregnant women. Existing studies prioritize on teratogenic or abortifacient effects. The aim of this study was to analyze the toxic effects of Mikania glomerata Sprengel administration, popularly known as "guaco" during the gestational period of hypertensive rats. For this experimental groups consisting of pregnant Wistar rats received treatments with guaco extract (1 to 2 mL). In order to analyze the possible toxic effects of guaco during pregnancy, weight gain of rats was assessed during pregnancy; reproductive performance of rats, morphological parameters, and fetal placental histology were compared. Although some parameters presented significant differences, we can conclude that changes prioritized by literature, such as toxicity, vasodilation and hypotension, have not been caused by guaco. The only fetal changes observed were due to the maternal hypertension. Some studies have reported vasodilator and hypotensive effects of guaco. However, only a few studies exist, and its actual effects remain unknown. Specific studies should be developed with higher doses of guaco for a definitive conclusion of its toxic and non-toxic effects.

Environmental factors associated with American cutaneous leishmaniasis in a new Andean focus in Colombia.

OBJECTIVE: To evaluate the environmental and ecological factors associated with Leishmania transmission and vector abundance in Chaparral, Tolima-Colombia. METHODS: First, we compared the ecological characteristics, abundance of phlebotomies and potential reservoir hosts in the peridomestic environment (100 m radius) of randomly selected houses, between two townships with high and low cutaneous leishmaniasis incidence. Second, we examined peridomestic correlates of phlebotomine abundance in all 43 houses in the higher risk township. RESULTS: The high transmission township had higher coverage of forest (23%vs. 8.4%) and shade coffee (30.7%vs. 11%), and less coffee monoculture (16.8%vs. 26.2%) and pasture (6.3%vs. 12.3%), compared to the low transmission township. Lutzomyia were more abundant in the high transmission township 2.5 vs. 0.2/trap/night. Lutzomyia longiflocosa was the most common species in both townships: 1021/1450 (70%) and 39/80 (49%). Numbers of potential wild mammal reservoirs were small, although four species were found to be infected with Leishmania (Viannia) spp. In the high transmission township, the overall peridomiciliary capture rate of L. longiflocosa was 1.5/trap/night, and the abundance was higher in houses located nearer to forest (ρ = -0.30, P = 0.05). CONCLUSION: The findings are consistent with a domestic transmission cycle with the phlebotomies dependent on dense vegetation near the house.

Characterization of MSWI bottom ashes towards utilization as glass raw material.

The characterization of the bottom ashes produced by two Portuguese municipal solid waste incinerators (MSWI) was performed with the aim of assessing the feasibility of using this waste as raw material in the production of glass that can be further processed as glass-ceramics for application in construction. Density and particle size distribution measurements were carried out for physical characterization. Chemical characterization revealed that SiO(2), a network glass former oxide, was present in a relatively high content (52-58wt%), indicating the suitability for this waste to be employed in the development of vitreous materials. CaO, Na(2)O and K(2)O, which act as fluxing agents, were present in various amounts (2-17wt%) together with several other oxides normally present in ceramic and glass raw materials. Mineralogical characterization revealed that the main crystalline phases were quartz (SiO(2)) and calcite (CaCO(3)) and that minor amounts of different alkaline and alkaline-earth aluminosilicate phases were also present. Thermal characterization showed that the decomposition of the different compounds occurred up to 1100 degrees C and that total weight loss was <10wt%. Heating both bottom ashes at 1400 degrees C for 2h resulted in a melt with suitable viscosity to be poured into a mould, and homogeneous black-coloured glasses with a smooth shiny surface were obtained after cooling. The vitrified bottom ashes were totally amorphous as confirmed by X-ray diffraction. The results from the present experimental work indicate that the examined bottom ashes can be a potential material to melt and to obtain a glass that can be further processed as glass-ceramics to be applied in construction.

The fluorapatite-anorthite system in biomedicine.

Glasses and glass ceramics of fluorapatite-anorthite (eutectic composition) were produced and characterized in order to evaluate their potential application in biomedicine. Bio-reactivity was determined by in vitro tests by immersion of powders in simulated plasma liquids as well as by in vivo experiments by implantation in rabbits. According to the results, the investigated materials are bio-acceptable since no toxic or other harmful evidence was detected. Glass-ceramics showed remarkable inertness, whereas glasses spontaneously dissolved in SBF and after 1 week moderate formation of apatite was observed, that however ceased within a month.

[Primary adenosquamous carcinoma of the stomach]. / Carcinoma adenoescamoso primário do estômago.

BACKGROUND: Primary adenosquamous carcinoma of the stomach is a rare tumour, the incidence of which does not exceed 1% of gastric tumours. This tumour shows two different cell components: one squamous and the other adenomatous. MATERIAL AND METHODS: The authors report a case of a primary adenosquamous carcinoma of the stomach in a 55-year-old Caucasian (white) man, whose pathology and immunohistochemistry show the presence of both types of cells: adenomatous and squamous. CONCLUSION: The authors show an interesting and rare case of adenosquamous tumour, discuss its pathogenesis, diagnosis, clinics and pathologic features.

Carcinoma adenoescamoso primário do estômago / Primary adenosquamous carcinoma of the stomach

O carcinoma adenoescamoso primário do estômago é um tumor raro, cuja incidência nao excede 1 por cento dos tumores gástricos. Esse tumor mostra dois tipos celulares distintos: um escamoso e outro adenocarcinomatoso. Material e Método. Os autores reportam um caso de carcinoma adenoescamoso primário do estômago em um paciente branco de 55 anos, cuja patologia e imuno-histoquímica mostram a presença dos dois tipos celulares: adenocarcinomatoso e escamoso. Conclusao. É discutido um caso de um tumor raro e interessante do estômago, com relaçao à sua patogênese, diagnóstico e aspectos clínico-patológicos.

[Intestinal obstruction caused by inflammatory fibroid polyp. Report of a case]. / Polipofibróide inflamatório causando obstrução intestinal. Relato de caso.

The inflammatory fibroid polyps are rare lesions of the digestive tract, they were firstly described occurring in the stomach, however their distribution is universal. Several other denominations have been used to same lesion such as fibroma and eosinophilic granuloma. The clinical presentation varies according to the its location, frequently they are mistaken as gastrointestinal neoplasias. Intestinal obstruction is one of the manifestations, mainly when the lesion occurs nearby the ileum cecal region. The authors present a case of intestinal obstruction caused by a inflammatory fibroid polyp located in the ileum cecal valve, treated successfully by right colectomy.

Tumor misto de pele. / Mixed tumor of the skin

E apresentado um caso de tumor misto da pele. Foi realizada uma breve revisao da literatura, e os aspectos clinicos e histologicos do caso sao descritos e comparados aos da literatura mundial