Cell growth on 3D microstructured surfaces.

Chinese Hamster Ovary (CHO) cell cultures were grown on surfaces lithographed with periodic 3D hexagonal microcavity array morphology. The range of microcavity size (inscribed circle diameter) was from 12 µm to 560 µm. CHO cells were grown also on flat surfaces. The characterization was performed with respect to cell growth density (number of nuclei per unit area) by fluorescence optical microscopy and evaluated by correlation function analysis. We found that optimum microcavity radius was 80 µm, concerning to the maximum cell growth density, being even greater than the growth density on a flat (unstructured) substrate of the same material. This finding can be important for optimization of biotechnological processes and devices.

Gold ion implantation into alumina using an "inverted ion source" configuration.

We describe an approach to ion implantation in which the plasma and its electronics are held at ground potential and the ion beam is injected into a space held at high negative potential, allowing considerable savings both economically and technologically. We used an "inverted ion implanter" of this kind to carry out implantation of gold into alumina, with Au ion energy 40 keV and dose (3-9) × 10(16) cm(-2). Resistivity was measured in situ as a function of dose and compared with predictions of a model based on percolation theory, in which electron transport in the composite is explained by conduction through a random resistor network formed by Au nanoparticles. Excellent agreement is found between the experimental results and the theory.

Performance of an inverted ion source.

Whereas energetic ion beams are conventionally produced by extracting ions (say, positive ions) from a plasma that is held at high (positive) potential, with ion energy determined by the potential drop through which the ions fall in the beam formation electrode system, in the device described here the plasma and its electronics are held at ground potential and the ion beam is formed and injected energetically into a space maintained at high (negative) potential. We refer to this configuration as an "inverted ion source." This approach allows considerable savings both technologically and economically, rendering feasible some ion beam applications, in particular small-scale ion implantation, that might otherwise not be possible for many researchers and laboratories. We have developed a device of this kind utilizing a metal vapor vacuum arc plasma source, and explored its operation and beam characteristics over a range of parameter variation. The downstream beam current has been measured as a function of extraction voltage (5-35 kV), arc current (50-230 A), metal ion species (Ti, Nb, Au), and extractor grid spacing and beamlet aperture size (3, 4, and 5 mm). The downstream ion beam current as measured by a magnetically-suppressed Faraday cup was up to as high as 600 mA, and with parametric variation quite similar to that found for the more conventional metal vapor vacuum arc ion source.

Environmental effects in Kelvin force microscopy of modified diamond surfaces.

We have explored the effects of atmospheric environment on Kelvin force microscopy (KFM) measurements of potential difference between different regions of test polycrystalline diamond surfaces. The diamond films were deposited by microwave plasma-assisted chemical vapor deposition, which naturally produces hydrogen terminations on the surface of the films formed. Selected regions were patterned by electron-beam lithography and chemical terminations of oxygen or fluorine were created by exposure to an oxygen or fluorine plasma source. For KFM imaging, the samples were mounted in a hood with a constant flow of helium gas. Successive images were taken over a 5-h period showing the effect of the environment on KFM imaging. We conclude that the helium flow removes water molecules adsorbed on the surface of the samples, resulting in differences in surface potential between adjacent regions. The degree of water removal is different for surfaces with different terminations. The results highlight the importance of taking into account the atmospheric environment when carrying out KFM analysis.

A high voltage pulse power supply for metal plasma immersion ion implantation and deposition.

We describe the design and implementation of a high voltage pulse power supply (pulser) that supports the operation of a repetitively pulsed filtered vacuum arc plasma deposition facility in plasma immersion ion implantation and deposition (Mepiiid) mode. Negative pulses (micropulses) of up to 20 kV in magnitude and 20 A peak current are provided in gated pulse packets (macropulses) over a broad range of possible pulse width and duty cycle. Application of the system consisting of filtered vacuum arc and high voltage pulser is demonstrated by forming diamond-like carbon (DLC) thin films with and without substrate bias provided by the pulser. Significantly enhanced film∕substrate adhesion is observed when the pulser is used to induce interface mixing between the DLC film and the underlying Si substrate.

Pelvic osteosarcoma ressection in a bitch: case report / Ressecção de osteossarcoma pélvico em cadela: relato de caso

An osteosarcoma involving the pelvis was diagnosed in a 9-year-old neutered Labrador bitch. The clinical signs manifested by the patient before surgical removal of the tumor included urinary difficulty, dyschezia, and inconstant non-weight-bearing on the hindlimbs. These signs were linked to the localization of the tumor, which was identified as a firm and painful mass of the size of an orange in the caudal abdomen. The favorable short term clinical results after surgery and carboplatin chemotherapy showed that the association of these approaches can be employed to manage discomfort inflicted by tumor and, therefore improve the quality of life of patient of bone cancer.

Diagnosticou-se um osteossarcoma pélvico em uma cadela da raça Labrador de nove anos. Os sinais clínicos manifestados pela paciente antes da remoção do tumor incluiam dificuldade urinária, disquezia e dificuldade de sustentação do trem posterior. Estes sinais estavam associados à localização do tumor, identificado como uma massa firme e dolorosa do tamanho de uma laranja à região caudal do abdômen. Os resultados clínicos favoráveis observados em curto prazo depois da instauração de tratamento cirúrgico e quimioterápico com carboplatina mostram que a associação dessas condutas pode ser empregada para diminuir o desconforto imposto pelo tumor e, portanto melhorar a qualidade de vida em pacientes com câncer ósseo.

Small plasma source for materials application.

We describe a small hollow-cathode plasma source suitable for small-scale materials synthesis and modification application. The supporting electrical system is minimal. The gaseous plasma source delivers a plasma ion current of up to about 1 mA. Here we outline the source construction and operation, and present some of its basic performance characteristics.

Atomic force microscope nanolithography of polymethylmethacrylate polymer.

We describe a nanolithography process for a polymethylmethacrylate (PMMA) surface using scanning contact atomic force microscopy. Parallel furrows were scribed with a pyramidal silicon tip using the same scan mechanism as used to image samples. The PMMA was first electron beam irradiated using a scanning electron microscope and developed. The topography formed is reproducible and predictable. Material from the region where the tip scribes is moved to nearby regions, and aligned, elongated PMMA fragments are seen to decorate the valleys between furrows.