A influência de modificação química (por tratamento ácido seguido de funcionalização com trietilenotetramina, TETA) sobre a superfície de nanotubos de carbono de paredes múltiplas (MWCNT) foi estudada qualitativa e quantitativamente. A análise termogravimétrica (TGA) mostrou que, no caso do nanotubo funcionalizado com amina, 29% de perda de massa pode ser atribuída a -C(=O)TETA e grupos funcionais residuais que contêm oxigênio. A espectroscopia de fotoelétrons excitados por raios X (XPS) foi utilizada para observar as funções aminadas e oxigenadas ligadas covalentemente à superfície do nanotubo. As imagens de microscopia de força elétrica (EFM) indicaram que, à medida que se modifica a química superficial dos nanotubos em presença de ar, estes mostram respostas diferentes em função do potencial da ponta. Deslocamentos nos sinais de fase de EFM decrescem quando se modifica a superfície dos tubos com grupos funcionais contendo oxigênio e amina. Em atmosfera seca e inerte de N2, as três diferentes superfícies mostraram a mesma resposta à EFM. Além disso, o caráter hidrofílico dos "buckypapers" cresceu na ordem MWCNT < MWCNT-aminado < MWCNT-oxidado.

The influence of chemical modification by acid treatment followed by triethylenetetramine (TETA) functionalization on the surface of multi-walled carbon nanotubes (MWCNT) was evaluated, both qualitative and quantitatively. Thermogravimetric analysis (TGA) showed that, in the case of amine-functionalized nanotubes, 29% of mass loss can be attributed to -C(=O)TETA and residual oxygen-containing functional groups. X-ray photoelectron spectroscopy (XPS) was used to observe the oxygenated and aminated functions covalently linked to the nanotube surface. Electric force microscopy (EFM) images indicated that the nanotubes with diverse surface chemistry showed distinct responses to the tip potential in the presence of air. Shifts in EFM phase images decreased when the nanotube surface was modified with oxygen and amine-containing functional groups. In dry and inert N2 atmosphere, however, the three different surfaces showed the same response to EFM. In addition, the hydrophilic character of the buckypapers increased in the order MWCNT < aminated-MWCNT < oxidized-MWCNT.

Um cão Shar-pei de cinco anos de idade foi encaminhado para exame de necropsia com histórico de morte súbita. Ao exame macroscópico foram observadas, no coração, áreas pálidas extensas envolvendo o miocárdio do ventrículo direito e esquerdo. Ao exame histológico foi observada infiltração intensa de células adiposas bem diferenciadas no miocárdio de ambos os ventrículos associada à moderada atrofia e degeneração de cardiomiócitos. Os achados microscópicos foram compatíveis com diagnóstico de displasia miocardial ventricular bilateral.

Descreve-se um caso de carcinossarcoma mamário em uma gata, sem raça definida, de 13 anos de idade. A gata não era castrada e não recebeu anticoncepcionais. A paciente apresentou extensivos e coalescentes nódulos em todas as glândulas mamárias. Com base nos achados histológicos e imunoistoquímicos, firmou-se o diagnóstico de carcinossarcoma da glândula mamária.

A case of mammary carcinosarcoma is reported in a 13-year-old, mixed breed female cat, which was not spayed and had not received contraceptives. The patient presented extensive and coalescent nodules in all mammary glands. Based on the histological and immunohistochemical findings, the diagnosis of mammary carcinosarcoma was confirmed.

Cryptococcosis is a systemic mycosis usually affecting immunodeficient individuals. In contrast, immunologically competent patients are rarely affected. Dissemination of cryptococcosis usually involves the central nervous system, manifesting as meningitis or meningoencephalitis. Prostatic lesions are not commonly found. A case of prostate cryptococcal infection is presented and cases of prostatic cryptococcosis in normal and immunocompromised hosts are reviewed. A fifty-year-old HIV-negative man with urinary retention and renal insufficiency underwent prostatectomy due to massive enlargement of the organ. Prostate histopathologic examination revealed encapsulated yeast-like structures. After 30 days, the patient's clinical manifestations worsened, with headache, neck stiffness, bradypsychia, vomiting and fever. Direct microscopy of the patient's urine with China ink preparations showed capsulated yeasts, and positive culture yielded Cryptococcus neoformans. This fungus was later isolated from cerebrospinal fluid and blood cultures, demonstrating thus its dissemination. The patient was discharged after 27 days in hospital and, despite a regimen of amphotericin B, he died four months later. This case points to cryptococcosis as a possible cause of prostatic disease and reinforces the importance of communication between the medical team and pathology and microbiology laboratories aiming at a more accurate diagnosis and successful treatment.

In this work several structural and chemical properties of self-assembled InAs islands grown on GaAs(001) are studied using surface x-ray scattering with synchrotron radiation. The technique of x-ray diffraction under grazing incidence condition was employed to differentiate coherent and incoherent islands. We used a model of a strained pyramidal island to interpret the x-ray results and correlate size and strain-state of these islands. The degree of GaAs interdiffusion in the islands was inferred from the variation of volume of the unit cell. The Poisson's ratio of the two materials involved establishes a limit of tetragonal distortion for this material. Any variation in this distortion is associated with the presence of Ga inside the islands.

Some fundamentals of Mössbauer spectroscopy and of fluctuating magnetic hyperfine interactions are reviewed. An expression for calculation of spin-phonon interaction transition probabilities on the ground of a Debye model is given. Basic ideas of superparamagnetism and classical results for low-temperature relaxation rates are presented. A theory of superparamagnetism based on spin-phonon interaction is introduced. It is shown how to calculate from this Mössbauer spectra taking all spin-levels into account. Experimental spectra of ferrofluids are compared with simulated spectra and found in good accordance.

The data analyzed in this work were generated following the methodology developed by Molina et al.(J. Electroanal. Chem., 1979) for the calibration of a potentiometric system of measurement of hydrogen-ion concentrations resulting from neutralizations, at 25 ºC, of acidic or alkaline solutions at constant ionic strength (0.1 mol.l-1) held with NaClO4. The observed data present a serious deviation in relation to the mathematical model derived from the Nernst equation, for pH values ranging from 3 to 11, where pH=-log[H+]. We show that the minimization of the sum of the absolute values of the residuals gives estimates that are not influenced by outlying values.