Foam formation during drainage of a surfactant solution in a microfluidic porous medium model.

Foam has been shown to have great potential to significantly improve sweep efficiency during gas injection in oil recovery, remediation of contaminated sites, gas storage, and acidification processes. The gas mobility reduction largely depends on the generation and stability of lamellae in the pore space that traps the gas phase. Most available analyses focus on foam formation during the co-injection of gas and liquid phases at different fractional flow (foam quality) or flow of foam formed before being injected in the porous media. During surfactant-alternating-gas (SAG) injection, foam is formed as the aqueous phase is displaced by the gas slug that follows. The dynamics of lamellae formation and their stability are different from that of a co-injection process, since the amount of surfactant available to stabilize the gas-liquid interfaces is fixed as fresh surfactant solution is not injected together with the gas phase. This work studies foam formation during the drainage of a surfactant solution by gas injection at a fixed flow rate. A transparent microfluidic model of a porous medium is used in order to enable the correlation of pore-scale phenomena and macroscopic flow behavior. The results show that the maximum number of lamellae increases with surfactant concentration, even much above the critical micelle concentration (CMC). The availability of surfactant molecules needed to stabilize newly formed gas-liquid interfaces rises with concentration. The higher number of lamellae formed at higher surfactant concentration leads to stronger mobility reduction of the gas phase and longer time needed for the gas to percolate through the porous medium.

Three-Dimensional Characterization of Polyurethane Foams Based on Biopolyols.

Two biopolyol-based foams derived from banana leaves (BL) or stems (BS) were produced, and their compression mechanical behavior and 3D microstructure were characterized. Traditional compression and in situ tests were performed during 3D image acquisition using X-ray microtomography. A methodology of image acquisition, processing, and analysis was developed to discriminate the foam cells and measure their numbers, volumes, and shapes along with the compression steps. The two foams had similar compression behaviors, but the average cell volume was five times larger for the BS foam than the BL foam. It was also shown that the number of cells increased with increasing compression while the average cell volume decreased. Cell shapes were elongated and did not change with compression. A possible explanation for these characteristics was proposed based on the possibility of cell collapse. The developed methodology will facilitate a broader study of biopolyol-based foams intending to verify the possibility of using these foams as green alternatives to the typical petrol-based foams.

Pore Scale Visualization of Drainage in 3D Porous Media by Confocal Microscopy.

We visualize the dynamics of immiscible displacement of a high viscosity wetting phase by a low viscosity non-wetting phase in a three-dimensional (3D) glass bead packing using confocal microscopy. Both phases were doped with two different fluorescent dyes, which enabled visualization of both phases simultaneously and quantification of the phase volumes without the need of image subtraction operations. The transient results show details of the displacement process and how pores are invaded by the non-wetting displacing phase. The static images at the end of the displacement process reveal how the trapped ganglia volume and morphology change with capillary number. The wetting phase is trapped as pendular rings spanning one to multiple pore necks. Details of the pore scale flow of oil wet media revealed with the experimental methods presented here can lead to better fundamental understanding of the physical processes and optimized enhanced oil recovery methods, CO2 sequestration and aquifer remediation.

Influence of the Cement Film Thickness on the Push-Out Bond Strength of Glass Fiber Posts Cemented in Human Root Canals.

The present study evaluated the influence of the cement film thickness on the push-out bond strength of glass fiber posts in the cervical, medium, and apical thirds of root canal spaces. Thirty roots were randomly divided into three groups, according to the fiber post system's drills: (G1) #2; (G2) #3; (G3) #4. The posts were cemented using a self-adhesive cement, and a small amount of powdered Rhodamine B was used as a stain. Images of both sides of each slice were obtained before and after the push-out test. To determine the cement thickness, a macro routine was developed using the software KS 400. The data were analyzed statistically using Kruskal-Wallis and Dunn's test. G2 (14.62 ± 5.15 MPa) showed statistically higher bond strength values than G1 (10.04 ± 5.13 MPa) and G3 (7.68 ± 6.14 MPa). All groups presented higher bond strength values in the apical third. The bur diameter significantly influenced the results of the shear bond strength for the push-out test. The slight increase in the cement thickness allowed an increase in the values of shear bond strength when compared to very thin or very thick cement films.

Micro-CT Evaluation of Non-instrumented Canal Areas with Different Enlargements Performed by NiTi Systems

The aim of this study was to compare the percentage of non-instrumented area of root canals prepared with different enlargements using single-file reciprocating systems (Reciproc and WaveOne) and a conventional multi-file rotary (BioRaCe) system by micro-computed tomographic analysis. Thirty mesial roots of mandibular molars with moderate curvature (10° to 20°) presenting a type II Vertucci canal configuration and similar internal volume were chosen and scanned at an isotropic resolution of 14.16 µm. The sample was assigned to 3 groups (n=10) according to the system used for root canal preparation: Reciproc, WaveOne, and BioRaCe groups. Second and third scans were taken after the canals were prepared with instruments sizes 25 and 40, respectively. The recorded images of the surface area voxels of the canals, before and after preparation were examined from the furcation level to the apex to quantify the non-instrumented surface. Statistical data were compared using GLM for repeated-measures with a significance level set at 5%. Instrumentation systems did not influence the percentage of untouched root canal surfaces (p=0.690) whilst a significant reduction in the percentage of static voxels was observed after the enlargement of the root canal (p=0.010) in all groups (p=0.507). None of the systems was able to prepare the entire surface area of the mesial root canal of mandibular molars. The increased final apical size resulted in a significant positive effect on the shaping ability of the tested systems.

Resumo O objetivo deste estudo foi comparar a porcentagem de área não-instrumentada de canais radiculares preparados com diferentes ampliações utilizando sistemas reciprocantes de lima única (Reciproc e WaveOne) e um sistema rotatório convencional de múltiplas limas (BioRaCe) usando a análise da micro tomografia computadorizada. Trinta raízes mesiais de molares inferiores com curvatura moderada (10º a 20º) apresentando a configuração classe II de Vertucci e semelhança de volume do canal foram selecionadas e escaneadas em uma resolução isotrópica de 14,16 µm. A amostra foi dividida em 3 grupos (n=10) de acordo com o sistema utilizado para a preparação do canal radicular: grupo Reciproc, grupo WaveOne e grupo BioRaCe. Segundo e terceiro escaneamentos foram realizados após os canais serem preparados com instrumentos tamanhos 25 e 40, respectivamente. As imagens registradas de voxels da área de superfície dos canais, antes e após o preparo, foram examinadas desde o nível da furca até o ápice para quantificar a superfície não instrumentada. Os dados foram comparados estatisticamente através de GLM para medidas repetidas com um nível de significância de 5%. Os sistemas de instrumentação não influenciaram o percentual de superfícies não tocadas dos canais radiculares (p=0,690), enquanto que uma redução significativa no percentual de voxels estáticos foi observada após o alargamento do canal radicular (p=0,010) em todos os grupos (p=0,507). Nenhum dos sistemas foi capaz de preparar toda a área de superfície do canal mesial dos molares inferiores. O aumento do tamanho final apical resultou num efeito positivo significativo sobre a capacidade de modelar dos sistemas testados.

Dental bleaching agents with calcium and their effects on enamel microhardness and morphology

Aim: To evaluate enamel microhardness and morphology after bleaching with hydrogen peroxide containing calcium in different concentrations. Methods: One hundred specimens of human teeth were ground and polished and had the initial microhardness evaluated. The specimens were randomly assigned into five groups (n=20): Group 1 - Control group (no treatment); Group 2 - Home Peroxide 6% (without calcium); Group 3 - Home Peroxide 7.5% (without calcium); Group 4 - White Class 6% (with calcium); Group 5 - White Class 7.5% (with calcium). For each group, the bleaching was performed according to the manufacturer's specifications. The specimens were bleached once a day for 5 days and subjected to pH cycling. Microhardness and scanning electron microscopy (SEM) analysis were performed before and after bleaching. Results: The results showed that groups submitted to bleaching treatment presented hardness loss compared to the control group. The group of 7.5% hydrogen peroxide with calcium showed a lower percentage of hardness loss in relation to other groups. Conclusion: Calcium in association with a higher hydrogen peroxide concentration may decrease microhardness changes on enamel.

Accumulated hard tissue debris produced during reciprocating and rotary nickel-titanium canal preparation.

INTRODUCTION: This study compared the amount of hard tissue debris produced after different apical enlargement with single-file reciprocating systems (WaveOne [Dentsply Maillefer, Baillaigues, Switzerland] and Reciproc [VDW, Munich, Germany]) and a conventional multifile rotary system (BioRaCe [FKG Dentaire, La-Chaux-de-Fonds, Switzerland]) using micro-computed tomographic imaging. METHODS: Thirty moderately curved mesial roots of mandibular molars presenting 2 independent root canals were selected and scanned at an isotropic resolution of 14.16 µm. The sample was assigned to 3 groups (n = 10) with respect to the root length and degree of curvature of the mesial root according to the system used for the root canal preparation: Reciproc, WaveOne, and BioRaCe. Second and third scans were taken after the root canals were prepared up to ISO sizes 25 and 40, respectively. The matched images of the mesial canals, before and after preparation, were examined from the furcation level to the apex to evaluate the amount of hard tissue debris (%). Data were statistically compared using a general linear model for repeated-measures with a significance level set at 5%. RESULTS: Instrumentation systems per se did not influence the amount of hard tissue accumulation (P > .05), whereas a significant reduction in the percentage of hard tissue debris was observed after sequential enlargement in all groups (P < .05). CONCLUSIONS: None of the systems yielded root canals completely free from packed hard tissue debris. The increased final apical size resulted in significantly less debris accumulation for both reciprocating and rotary systems.

Micro-CT Evaluation of Non-instrumented Canal Areas with Different Enlargements Performed by NiTi Systems.

The aim of this study was to compare the percentage of non-instrumented area of root canals prepared with different enlargements using single-file reciprocating systems (Reciproc and WaveOne) and a conventional multi-file rotary (BioRaCe) system by micro-computed tomographic analysis. Thirty mesial roots of mandibular molars with moderate curvature (10° to 20°) presenting a type II Vertucci canal configuration and similar internal volume were chosen and scanned at an isotropic resolution of 14.16 µm. The sample was assigned to 3 groups (n=10) according to the system used for root canal preparation: Reciproc, WaveOne, and BioRaCe groups. Second and third scans were taken after the canals were prepared with instruments sizes 25 and 40, respectively. The recorded images of the surface area voxels of the canals, before and after preparation were examined from the furcation level to the apex to quantify the non-instrumented surface. Statistical data were compared using GLM for repeated-measures with a significance level set at 5%. Instrumentation systems did not influence the percentage of untouched root canal surfaces (p=0.690) whilst a significant reduction in the percentage of static voxels was observed after the enlargement of the root canal (p=0.010) in all groups (p=0.507). None of the systems was able to prepare the entire surface area of the mesial root canal of mandibular molars. The increased final apical size resulted in a significant positive effect on the shaping ability of the tested systems.

Assessing accumulated hard-tissue debris using micro-computed tomography and free software for image processing and analysis.

INTRODUCTION: The accumulation of debris occurs after root canal preparation procedures specifically in fins, isthmus, irregularities, and ramifications. The aim of this study was to present a step-by-step description of a new method used to longitudinally identify, measure, and 3-dimensionally map the accumulation of hard-tissue debris inside the root canal after biomechanical preparation using free software for image processing and analysis. METHODS: Three mandibular molars presenting the mesial root with a large isthmus width and a type II Vertucci's canal configuration were selected and scanned. The specimens were assigned to 1 of 3 experimental approaches: (1) 5.25% sodium hypochlorite + 17% EDTA, (2) bidistilled water, and (3) no irrigation. After root canal preparation, high-resolution scans of the teeth were accomplished, and free software packages were used to register and quantify the amount of accumulated hard-tissue debris in either canal space or isthmus areas. RESULTS: Canal preparation without irrigation resulted in 34.6% of its volume filled with hard-tissue debris, whereas the use of bidistilled water or NaOCl followed by EDTA showed a reduction in the percentage volume of debris to 16% and 11.3%, respectively. The closer the distance to the isthmus area was the larger the amount of accumulated debris regardless of the irrigating protocol used. CONCLUSIONS: Through the present method, it was possible to calculate the volume of hard-tissue debris in the isthmuses and in the root canal space. Free-software packages used for image reconstruction, registering, and analysis have shown to be promising for end-user application.

Mapping large extensions of flat dentin through digital microscopy: introduction to the method and possible applications.

PURPOSE: To introduce a mapping method to characterize large dentin surfaces using digital microscopy and to discuss the advantages and possible applications of the method. MATERIALS AND METHODS: Twenty unerupted third molars were sectioned transversally exposing coronal dentin surfaces. The microscopic mosaic method was used to generate a large field image with the resolution necessary to measure characteristics of dentin tubules. The AxioVision 4.7 software was used to control a motorized optical microscope and the process of acquiring approximately 400 small images to generate each dentin mosaic. An image analysis routine measured the number of tubules (NT) and the ratio between the total area of tubules and the area of the mosaic - the area fraction (AF) - of each mosaic. An automatic procedure transformed the mosaic image into a color map, providing a direct visual representation of tubule density through colors. The dentin maps were used for a comparative qualitative analysis of tubule density distribution of each sample. RESULTS: The results for NT (92450 to 196029 tubules/sample) and AF (4.12% to 11.10%) demonstrated a wide variation among dentin samples. The maps confirmed the microstructure variety, also revealing strong local variations in tubule density within each sample. CONCLUSION: The mapping method was able to perform dentin morphology characterization and is a valuable tool for producing a baseline for dentin adhesion studies. The method could be also useful in determining the real contribution of dentin structures to the final adhesion quality.

Mechanical and microstructural properties of a nickel-chromium alloy after casting process

Introduction: There is a growing concern on the development of adequate materials to interact with the human body. Several researches have been conducted on the development of biomaterials for dental applications. Objective: This study aimed to determine the microstructural and mechanical properties of a nickel- based alloy, after the casting process. Material and methods: The alloy was melted through lost wax technique and centrifugation, by using blowtorch with liquefied petroleum gas. To evaluate the mechanical properties, tensile bond strength and microhardness tests were performed. The microstructural characterization was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Statistical analyses were performed on microhardness results, through Student t test. A program for digital image processing was used to determine the percentage of the existing phases. Results and Conclusion: The tensile strength was higher than that reported by the manufacturer, 559.39±25.63MPa versus 306 MPa, respectively. However, the yield strength was slightly lower, 218.71±29.75 MPa versus 258 MPa, reported by the manufacturer. The microhardness tests showed about 70 HV, far above the value informed by the manufacturer (21 HV). It can be affirmed with 95% confidence interval that the casting process did not alter the material's hardness. The alloy's microstructure is formed by a matrix with dendritic aspect and gray color and a second white interdendritic phase with equally distributed precipitates as well as porosities. EDS tests showed that the matrix is rich in nickel and chromium, the interdendritic second phase is rich in molybdenum and the precipitates in titanium or silicon. The matrix represents 86% of the area and the second phase 12%.

Critical appraisal of published smear layer-removal studies: methodological issues.

The smear layer phenomenon has been extensively addressed over the past 3 decades. However, there still are unanswered questions on this issue and the main responsible factor is the qualitative and nonreproducible character of most in vitro smear layer removal studies. The methodological reasons that led to the current lack of reliable conclusions on procedures aiming to remove the smear layer are comprehensively addressed. The limitations and outcomes related to different assessment methods are discussed as well. General speaking, the results by score-based conventional SEM studies are not trustworthy and reproducible. Computational routines able to automatically extract quantitative data of dentin morphology are necessary to minimize the human bias. An ideal experimental model should have a longitudinal observational character, in which a given dentin area can be observed at different times. The use of flat dentin samples should be avoided because of the influence of gravity as well as root canal anatomy on the final result of the chelating process. The experimental model also needs to take into consideration the amount and distribution of sclerotic dentin and irregular secondary dentin, otherwise the final results can be compromised. Inasmuch as there is a clear lack of scientific standard, simple comparative SEM evaluations are pointless at the present moment. The ideal experimental model to assess smear layer removal is not currently available. Therefore, further research efforts should be directed to the development of and testing of new methodological approaches to be used in the smear layer removal studies. The improvement of the experimental models is a requirement to draw up optimized clinical guidelines for the chemical treatment of the root dentin.

Influência do processo de fabricação de reconstruções metalocerâmicas na microestrutura de liga níquel-cromo / Manufacture process of metal-ceramic reconstructions influence on the nickel-chromium alloy microestructure

Introdução: Durante a fabricação de reconstruções dentárias, que utilizam sistemas metalocerâmicos, é utilizado um tratamento térmico para promover a adesão da porcelana ao metal. Entretanto, sabe-se que tratamentos térmicos podem alterar a microestrutura do material metálico, modificando suas propriedades. Objetivo: Este trabalho objetivou avaliar as possíveis modificações causadas na microestrutura de liga à base de níquel-cromo utilizada para reconstruções metalocerâmicas, quando a mesma é submetida ao tratamento térmico para adesão da porcelana.Material e método: O material pesquisado foi dividido nos grupos CR, F e TT, que representam, respectivamente, o material como recebido do fabricante, o material apenas submetido ao processo de fundição e o material após fundição e tratamento térmico. Os grupos CR e F foram submetidos à análise química quantitativa. A caracterizaçãomicroestrutural dos três grupos foi realizada através da técnica de microscopia eletrônica de varredura, com um sistema de Energy Dispersive Spectroscopy. Técnicas de análise e processamento digital de imagens foram aplicadas às micrografias dos grupos F e TT, para determinação de possíveis modificações quantitativas nas fases presentes. Resultado: A microestrutura da liga era formada por uma matriz de estrutura dendrítica de coloração cinza, rica em níquel; uma segunda fase interdendrítica de coloração branca e aspecto rendilhado, rica em molibidênio, e precipitados de coloração preta, podendo ser ricos em silício ou titânio. Também foram identificadas porosidades.Conclusão: A microestrutura após o processo de fundição apresentou um tamanho da fase interdendrítica menor. Não foram identificadas mudanças na microestrutura e na composição química das fases após o tratamento térmico.

Introduction: Manufacturing process of metal-ceramic dental reconstructions systems includes heat treatment to promote adhesion of the porcelain in the metal. However, it is known that heat treatment can promote changes in the microstructure of metallic materials, thereby affecting their properties. Objective: This work evaluated themicrostructure stability of dental quality nickel base alloy submitted to the heat treatment aiming at achieving porcelain adhesion. Material and method: The samples divided into three sets, CR, F and TT, representing,respectively, the material received from the manufacturer, the material just before the casting process and the material after casting end heat treatment. The CR and F sample sets were submitted to quantitative chemical analysis. The samples of CR, F and TT sets was submitted to the microstructural characterization by scanning electron microscopy and energy dispersive spectroscopy. Digital images processing techniques were applied to micrographics of F and TT sets to determine the changes in the material microstructure before and after heat treatment. Result: The alloy microstructure exhibits a gray dendritic structure in a clear matrix, rich in nickel, and a white inter-dendritic second phase, rich in molybdenum, with scattered precipitates, rich in titanium or silicon,and porosity. Conclusion: The microstructure has an average size of the interdendritic phase less than the alloy after casting. Changes in the microestructure and in the chemical composition of each phase were not identified, whether before nor after thermal treatment.

Push-out bond strength of Resilon/Epiphany and Resilon/Epiphany self-etch to root dentin.

INTRODUCTION: The present study was designed to investigate the bond strength produced by Epiphany and Epiphany SE to root canal dentin. METHODS: A sample of 36 human upper canines was prepared and assigned to experimental groups (n = 12), designated as group 1, Resilon/Epiphany; group 2, Resilon/Epiphany SE; and group 3, AH Plus/gutta-percha. After the filling procedures, each tooth was prepared for push-out assessment by using root slices of 1-mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey test for multiple comparisons were used to compare the results among the experimental groups. RESULTS: AH Plus/gutta-percha root fillings showed significantly higher push-out bond strength than both Resilon/Epiphany and Resilon/Epiphany SE (P < .05). There was no significant difference between Epiphany/Resilon and Epiphany SE/Resilon (P > .05). CONCLUSIONS: Under the present in vitro conditions, the adhesiveness quality to root dentin promoted by both Epiphany sealers is compromised even when teeth with simple anatomic features were obturated under well-monitored laboratory conditions.

Strong effect on dentin after the use of high concentrations of citric acid: an assessment with co-site optical microscopy and ESEM.

OBJECTIVES: To perform a longitudinal analysis of the effect of four substances (citric acid at 1%, 5% and 10% concentrations and 17% EDTA) on dentin. METHODS: Sixteen human molars had their crowns removed exposing cervical root dentin. A grinding procedure was used to produce a standardized smear layer and to create a smooth surface for analysis. Environmental scanning electron microscopy (ESEM) was used for qualitative observations while co-site optical microscopy (CSOM) and image analysis (IA) provided a quantitative comparison of the effect of the substances for several experimental times from 15 to 300s. The methods allowed the observation of the same areas after each experimental time. The open tubule area fraction was measured for several CSOM image fields, at each experimental time, for the four substances. Thus, it was possible to follow the phenomenon and quantitatively analyze the effect of the substances. Kolmogorov-Smirnov, Kruskal-Wallis H and Wilcoxon signed-ranks (with Bonferroni correction) tests were used to analyze the data. The level of significance was set at p<0.05. RESULTS: The CA solutions showed the greatest chelating effect, which was proportional to concentration (EDTA: 9.4-32.8% (15-300s); 1% CA: 21.1-32.2% (15-300s); 5% CA: 32.4-43.1% (15-300s); 10% CA: 35.1-39.5% (15-30s). Erosive effects were observed on inter and peritubular dentin for 5% CA and 10% CA after 60s. SIGNIFICANCE: ESEM allowed a detailed qualitative comparison of the effect of the four substances. CSOM and IA provided a quantitative comparison method with good statistical significance. Future studies should focus on the consequences of dentin erosion caused by citric acid.

Dentin demineralization when subjected to BioPure MTAD: a longitudinal and quantitative assessment.

In the present study, the demineralizing ability of BioPure MTAD (Dentsply/Tulsa, Tulsa, OK), 17% EDTA, and 5% citric acid on radicular dentin was quantitatively and longitudinally analyzed. 3 mm thick disks were obtained at the root cervical third from 9 maxillary human molars, and a standardized smear layer was produced. Cosite images of the dentin surface were obtained after several cumulative demineralization times. Sixteen images were obtained in each dentin sample for each experimental time, at 1000x magnification. An image processing and analysis sequence measured sets of images, providing data of area fraction for thousands of tubules over time. Thus, it was possible to follow the demineralization phenomenon and quantitatively analyze the effect of the various substances. The nonparametric Kruskal-Wallis H-test was used to analyze the data. Based on the present results, it can be concluded that the demineralization kinetics promoted by both 5% CA and BioPure MTAD was significantly faster than by 17% EDTA.

Polymicrobial leakage of four root canal sealers at two different thicknesses.

The present study investigated the sealing ability of four root canal sealers at two different thicknesses. There were 82 maxillary incisors roots prepared with Gates Glidden drills up to size 6 and divided into four groups: Pulp Canal Sealer, EndoREZ, Sealapex, and AH Plus. Each group was divided in two subgroups and gutta-percha cylinders 1.5 or 1 mm wide were used, respectively. The roots were mounted in a bacterial leakage model and the system was checked daily during the following 12 wk. Data were analyzed by Log-Rank test and Student t-test. In the thin layer samples, the sealers demonstrated similar results while, in the thick layer samples, AH Plus revealed the best performance. Generally, greater sealer thickness influenced negatively the sealing ability of the root canal filling, except in AH Plus samples.

Uptake of host cell transforming growth factor-beta by Trypanosoma cruzi amastigotes in cardiomyocytes: potential role in parasite cycle completion.

The cytokine transforming growth factor-beta (TGF-beta) plays various functions in the control of Trypanosoma cruzi infectivity and in the progression of Chagas' disease. When we immunostained T. cruzi-infected cardiomyocytes (after either in vivo or in vitro infections) for TGF-beta, we observed stronger immunoreactivity in parasites than in host cells. TGF-beta immunoreactivity evolved during parasite cycle progression, with intense staining in amastigotes versus very faint staining in trypomastigotes. TGF-beta was present on the surface of amastigotes, in the flagellar pocket, and in intraparasitic vesicles as revealed by electron microscopy. However, no ortholog TGF-beta gene could be identified in the genome of T. cruzi by in silico analysis or by extensive polymerase chain reaction and reverse transcriptase-polymerase chain reaction studies. Immunoreactive TGF-beta was most probably taken up by the parasite from the host cell cytoplasm because such an internalization process of biotinylated TGF-beta could be observed in axenic amastigotes in vitro. These observations represent the first example of a novel mechanism by which a primitive unicellular protozoan can use host cell TGF-beta to control its own intracellular life cycle.

Automatic classification of graphite in cast iron.

A method for automatic classification of the shape of graphite particles in cast iron is proposed. In a typical supervised classification procedure, the standard charts from the ISO-945 standard are used as a training and validation population. Several shape and size parameters are described and used as discriminants. A new parameter, the average internal angle, is proposed and is shown to be relevant for accurate classification. The ideal parameter sets are determined, leading to validation success rates above 90%. The classifier is then applied to real cast iron samples and provides results that are consistent with visual examination. The method provides classification results per particle, different from the traditional per field chart comparison methods. The full procedure can run automatically without user interference.