Nitrogen implantation of tool steels and engineering coatings

Ion implantation modifies the surface composition and properties of materials by bombardment with high energy ions. The low temperature of the process ensures the avoidance of distortion and degradation of the surface or bulk mechanical properties of components. In the present work nitrogen ion implantation at 90 keV and doses above 1017 ions/cm2 has been carried out on AISI M2, D2 and 420 steels and engineering coatings such as hard chromium, electroless Ni-P and a brush plated Co-W alloy. Evaluation of wear and frictional properties of these materials was performed with a lubricated Falex wear test at high loads up to 900 N and a dry pin-on-disc apparatus at loads up to 40 N. It was found that nitrogen implantation reduced the wear of AISI 420 stainless steel by a factor of 2.5 under high load lubricated conditions and by a factor of 5.5 in low load dry testing. Lower but significant reductions in wear were achieved for AISI M2 and D2 steels. Wear resistance of coating materials was improved by up to 4 times in lubricated wear of hard Cr coatings implanted at the optimum dose but lower improvements were obtained for the Co-W alloy coating. However, hardened electroless Ni-P coatings showed no enhancement in wear properties. The benefits obtained in wear behaviour for the above materials were generally accompanied by a significant decrease in the running-in friction. Nitrogen implantation hardened the surface of steels and Cr and Co-W coatings. An ultra-microhardness technique showed that the true hardness of implanted layers was greater than the values obtained by conventional micro-hardness methods, which often result in penetration below the implanted depth. Scanning electron microscopy revealed that implantation reduced the ploughing effect during wear and a change in wear mechanism from an abrasive-adhesive type to a mild oxidative mode was evident. Retention of nitrogen after implantation was studied by Nuclear Reaction Analysis and Auger Electron Spectroscopy. It was shown that maximum nitrogen retention occurs in hard Cr coatings and AISI 420 stainless steel, which explains the improvements obtained in wear resistance and hardness. X-ray photoelectron spectroscopy on these materials revealed that nitrogen is almost entirely bound to Cr, forming chromium nitrides. It was concluded that nitrogen implantation at 90 keV and doses above 3x1017 ions/cm2 produced the most significant improvements in mechanical properties in materials containing nitride formers by precipitation strengthening, improving the load bearing capacity of the surface and changing the wear mechanism from adhesive-abrasive to oxidative.

A study of the growth and differentiation of the human adenocarcinoma of the colon cell line HT-29

The HT-29 human colon adenocarcinoma cell line, like many epithelial cells, displays an undifferentiated phenotype when cultured on plastic substrata. Biochemical markers of differentiation, such as brush border associated enzymes and carcinoembryonic antigen were expressed at very low levels. The differentiation-inducing effects of the culture of HT-29 cells on collagen type I gels were evaluated, and were assessed by morphological appearance, brush border associated enzyme activities and the secretion of CEA. The effect that this more physiological environment had on their chemosensitivity to a panel of chemotherapeutic agents was determined, so as to indicate whether this system could be used to improve the selectivity of screening for novel anticancer agents. Initial studies were performed on HT-29 cells derived from cells seeded directly from plastic substrata onto the collagen gels (designated Non-PPC gels). Their time of exposure to the collagen was limited to the time course of a single experiment and the results suggested that a longer, more permanent exposure might produce a more pronounced differentiation. HT-29 cells were then passaged continuously on collagen gels for a minimum of 10 passages prior to experimentation (designated PPC gels). The same parameters were measured, and compared to those for the cells grown on plastic and on the non-passaged collagen gels (Non-PPC) from the original studies. Permanently passaged cells displayed a similar degree of morphological differentiation as the non-passaged cells, with both culture conditions resulting in a more pronounced differentiation than that achieved by culture on plastic. It was noted that the morphological differentiation observed was very heterogeneous, a situation also seen in xenografted tumours in vivo. The activity of alkaline phosphatase and the production of CEA was higher in the cells passaged on collagen (PPC) than the cells cultured on non-passaged collagen gel (Non-PPC) and plastic. The biochemical determination of aminopeptidase activity showed that collagen gel culture enhanced the activity in both non-passaged and passaged HT-29 cells above that of the cells cultured on plastic. However, immunocytochemical localization of aminopeptidase and sucrase-isomaltase of samples of cells grown on the various substrata for 7, 14, 21 and 28 days showed a reduction in both enzymes in the cells grown on collagen gels when compared to cells grown on plastic. The reason for the discrepancy between the two assays for aminopeptidase is at this stage unexplained. Although, there was evidence to suggest that the culture of HT-29 cells on collagen gels was capable of inducing morphological and biochemical markers of enterocytic differentiation, there were no differences in the chemosensitivity of the different cell groups to a panel of anticancer agents. Preliminary studies suggested that the ability of the cells to polarize by their culture on porous filter chambers without any exogenous ECM was sufficient to enhance HT-29 differentiation and the onset of differentiation was probably correlated with the production of ECM by the cells themselves.

Viscoelasticity and high buckling stress of dense carbon nanotube brushes

We report on the mechanical behavior of a dense brush of small-diameter (1–3 nm) non-catalytic multiwall (2–4 walls) carbon nanotubes (CNTs), with ~10 times higher density than CNT brushes produced by other methods. Under compression with spherical indenters of different radii, these highly dense CNT brushes exhibit a higher modulus (~17–20 GPa) and orders of magnitude higher resistance to buckling than vapor phase deposited CNT brushes or carbon walls. We also demonstrate the viscoelastic behavior, caused by the increased influence of the van der Waals’ forces in these highly dense CNT brushes, showing their promise for energy-absorbing coatings.

Automatic object segmentation from calibrated images

This paper addresses the problem of automatically obtaining the object/background segmentation of a rigid 3D object observed in a set of images that have been calibrated for camera pose and intrinsics. Such segmentations can be used to obtain a shape representation of a potentially texture-less object by computing a visual hull. We propose an automatic approach where the object to be segmented is identified by the pose of the cameras instead of user input such as 2D bounding rectangles or brush-strokes. The key behind our method is a pairwise MRF framework that combines (a) foreground/background appearance models, (b) epipolar constraints and (c) weak stereo correspondence into a single segmentation cost function that can be efficiently solved by Graph-cuts. The segmentation thus obtained is further improved using silhouette coherency and then used to update the foreground/background appearance models which are fed into the next Graph-cut computation. These two steps are iterated until segmentation convergences. Our method can automatically provide a 3D surface representation even in texture-less scenes where MVS methods might fail. Furthermore, it confers improved performance in images where the object is not readily separable from the background in colour space, an area that previous segmentation approaches have found challenging. © 2011 IEEE.

Mechanical actuation by responsive polyelectrolyte brushes and triblock gels

Progress in the development of actuating molecular devices based on responsive polymers is reviewed. The synthesis and characterization of "grafted from brushes and triblock copolymers is reported. The responsive nature of polyelectrolyte brushes, grown by surface initiated atomic transfer radical polymerization (ATRP), has been characterized by scanning force microscopy, neutron reflectometry, and single molecule force measurements. The molecular response is measured directly for the brushes in terms of both the brush height and composition and the force generated by a single molecule. Triblock copolymers, based on hydrophobic end blocks and polyacid midblock, have been used to produce polymer gels where the deformation of the molecules can be followed directly by small angle Xray scattering (SAXS), and a correlation between molecular shape change and macroscopic deformation has been established. A Landolt pHoscillator, based on bromate/sulfite/ferrocyanide, with a room temperature period of 20 min and a range of 3.1

Integrative bioinformatics for functional genorne annotation:trawling for G protein-coupled receptors

G protein-coupled receptors (GPCR) are amongst the best studied and most functionally diverse types of cell-surface protein. The importance of GPCRs as mediates or cell function and organismal developmental underlies their involvement in key physiological roles and their prominence as targets for pharmacological therapeutics. In this review, we highlight the requirement for integrated protocols which underline the different perspectives offered by different sequence analysis methods. BLAST and FastA offer broad brush strokes. Motif-based search methods add the fine detail. Structural modelling offers another perspective which allows us to elucidate the physicochemical properties that underlie ligand binding. Together, these different views provide a more informative and a more detailed picture of GPCR structure and function. Many GPCRs remain orphan receptors with no identified ligand, yet as computer-driven functional genomics starts to elaborate their functions, a new understanding of their roles in cell and developmental biology will follow.

Otimização de parâmetros mecânicos e microestruturais dos moldes em areia de sílica ligados quimicamente pelo processo de cura a frio em fundição de aço

Surface defects on steel parts borne costs of smelting industries due to the need of rework. Sand molds are frequently used in foundry industries and largely responsible for providing surface defects. This study aims to optimize the levels of the molding process variables to minimize the occurrence of surface defects in steel castings in silica sand molds chemically linked by cold cure process. The methodology used the experimental design with split plot, being considered in the study the resin percentage factors in the mold formulation, addition of iron oxide, type of paint, the paint application method, amount of ink layers, use of hot air along the lines and waiting time of the mold before casting. They were analyzed as response variables erosion defects, sand inclusion, penetration, porosity and surface finish. Tensile strength tests were performed to evaluate the influence of factors on mechanical parameters and the microstructural parameters were carried out the analysis of X-ray diffraction, scanning electron microscopy (SEM) and thermal analysis (TG / DSC / dilatometry). The results elucidate that for the faulty erosion, the only significant factor with a 95% confidence level was the type of ink and the ink alumina-based superior results obtained. For the sand inclusion of defect, there were three significant factors, with best results obtained with alumina-based paint and spray applied using hot air in the mold before casting the metal. For the defect penetration, there were four significant factors, the best results being achieved with 0.8% of resin and addition of iron oxide in the molding formulation, the paint being applied by brush and standby time of 24 hours before leak. For the defect porosity with a 95% confidence level, no significant factors. For the defect surface finish, the best results were achieved with the 0.8% formulation of the resin in the mold and application of the paint brush. To obtain the levels of the factors that optimize all defects simultaneously, we performed a weighted average of the results of each type of fault, concluding that the best levels of the factors were: 0.8% resin and addition of iron oxide in the formulation of the template, application of two coats of paint applied with a brush or spray, using hot air in the mold before casting and 24 hours of waiting ready the mold before casting. These levels of the optimized factors were used in an experiment to confirm that ratified the results, helping to reduce rework and consequently reducing costs of cast steel parts.

Location and ages of terrestrial peatlands located on continental shelves and in coastal sediments

This synthesis dataset contains records of freshwater peat and lake sediments from continental shelves and coastal areas. Information included is site location (when available), thickness and description of terrestrial sediments as well as underlying and overlying sediments, dates (when available), and references.

Relação entre a cárie precoce da infância com o índice de Apgar e outros fatores de risco

The aim of this cross-sectional study was to investigate the association of early childhood caries (ECC) with the Apgar score (AS) and other variables related to the child (conditions at birth and medical history) and related to the child and parents and / or guardians and family (demographic, socioeconomic and behavioral). One hundred and twenty healthy children aged between 3-5 years-old treated by Pediatric Dentistry Area of Dentistry College of the Federal University of Uberlandia during 2015 were selected. To obtain qualitative and quantitative variables a questionnaire was applied as an interview to the parents and/or guardians. The 5-minute AS (interest exposure) was obtained through the record in the Child Health Handbook. To assess the prevalence of caries (clinical dependent variable), a single calibrated researcher conducted the clinical examination, according to the criteria of the World Health Organization. Caries experience was measured using the indexes dmft and dmfs. The children were classified into three groups, according to age and dmfs index: no caries (NC), with ECC and with severe early childhood caries (S-ECC). Data were tabulated and submitted to statistical analysis using the SPSS software (IBM, Inc, Chicago, Illinois, USA) 17th version. Three logistics models were carried out having the following classifications: NC and ECC, NC and S-ECC, ECC and S-ECC (p<0.05). The overall ECC prevalence, considering children with ECC and S-ECC, was 55,8% (n= 67). The AS was not a statistically significant variable. The child’s age, weaning age and recent hospitalization were variables associated with the ECC prevalence. The age of brush start and the educational level of the mother were variables associated with the S-ECC prevalence. Considering the ECC and the S-ECC groups, the child's age and the beginning of the use of fluoride toothpaste, recent hospitalization, the educational level of the mother and the father's income were associated with the S-ECC prevalence. Considering the methodology employed and the analysis of results, it was concluded that there was no association between the ECC with the AS in healthy children. However, an association was found of ECC and S-ECC with some variables related to birth and to medical history of the child (recent hospitalization), demographic (child’s age), socioeconomic (educational level of the mother and father's income) and behavioral (age of brush start, weaning age and use of fluoride toothpaste) related to children and to the parents and/or guardians.

Formation of sub-7 nm feature size PS-b-P4VP block copolymer structures by solvent vapour process

The nanometer range structure produced by thin films of diblock copolymers makes them a great of interest as templates for the microelectronics industry. We investigated the effect of annealing solvents and/or mixture of the solvents in case of symmetric Poly (styrene-block-4vinylpyridine) (PS-b-P4VP) diblock copolymer to get the desired line patterns. In this paper, we used different molecular weights PS-b-P4VP to demonstrate the scalability of such high χ BCP system which requires precise fine-tuning of interfacial energies achieved by surface treatment and that improves the wetting property, ordering, and minimizes defect densities. Bare Silicon Substrates were also modified with polystyrene brush and ethylene glycol self-assembled monolayer in a simple quick reproducible way. Also, a novel and simple in situ hard mask technique was used to generate sub-7nm Iron oxide nanowires with a high aspect ratio on Silicon substrate, which can be used to develop silicon nanowires post pattern transfer.

Saúde oral e cuidados primários em Odontopediatria

Introdução: A cárie dentária é uma doença multifatorial, infeciosa, transmissível e dependente da dieta, que provoca a desmineralização das estruturas dentárias. Devido a esta natureza etiológica multifatorial é fundamental o aumento da sensibilização e educação das crianças e pais, quer por profissionais de saúde, quer pelos professores em ambiente escolar. A aquisição de hábitos de higiene oral e nutricionais adequados pela criança é um fator imperativo para a manutenção de uma boa saúde oral. Objetivos: Avaliação da Saúde Oral e cuidados primários num grupo de crianças e adolescentes pertencentes ao Agrupamento de Escolas de Alijó. Método: A amostra é constituída por 216 alunos do Agrupamento de Escolas de Alijó, agrupados em três escalões etários: 6-9 anos, 10-14 anos e 15-16 anos. Foi realizada uma observação oral com base no índice de higiene oral simplificado e no índice de cárie (CPOd/cpod- Dentes Cariados, Perdidos e Obturados). Após esta observação foi aplicado um questionário escrito sobre diversos temas relacionados com a saúde oral. Resultados: A percentagem de crianças livres de lesões cariosas aos 6, 12 e 15 anos foi de 33,3%, 28,4% e 16,2%, respetivamente. Os valores da média de número de escovagens diárias aumentam de acordo com a faixa etária. O número de escovagens médias aos 6-9anos, 10-14anos e 15-16anos foi 1,37; 1,48 e 1,55 no sexo masculino, no caso de sexo feminino estes valores passam para 1,58; 1,80 e 1,89 respetivamente. Discussão: Os números registados no presente estudo são semelhantes aos do I Estudo Nacional de Prevalência da Cárie Dentária, onde se verificou percentagens de 33%, 27% e 18,9% para os escalões referentes aos 6 anos, 9 anos e 15 anos. Existe uma melhoria significativa em cada um destes escalões nos dois estudos seguintes realizados pela DGS. Em 2008 estas percentagens foram de 51%, 44% e 28%, respetivamente para cada um dos escalões. Em 2015 existiu apenas um pequeno acréscimo, com percentagens registadas de 54,8%, 53% e 32,4%, respetivamente. A última percentagem, de 32,4%, refere-se neste caso ao escalão dos 18 anos, uma vez que a DGS substituiu o escalão de estudo dos 15 anos de idade. Quando nos referimos ao número de escovagens médio, os números registados neste estudo têm uma evolução semelhante aos encontrados no III Estudo Nacional de Prevalência da Cárie Dentária, publicado em 2015 pela DGS, que refere que aos 6 anos 53% dos inquiridos escova duas vezes ao dia e 25,7% apenas uma vez, enquanto que aos 12 anos nos deparamos com uma descida para 19,9% dos que escovam 1x por dia e um aumento para 69,9% dos que escovam duas vezes. O mesmo estudo afirma ainda que as jovens escovam mais vezes os dentes, tal como no presente estudo. Conclusão: Os últimos anos têm-se revelado determinantes na melhoria da Saúde Oral dos portugueses e a aposta na prevenção, nomeadamente nos Cuidados Primários de Saúde Oral tem apresentado uma mais-valia inquestionável. Como em todos os percursos que se iniciam, a monitorização dos resultados e a sua melhoria contínua podem conduzir à otimização das estratégias e no seu conjunto contribuir para fazer ainda mais e melhor. Este estudo permitiu aferir, que a realidade, em contextos de Saúde Oral, no Concelho de Alijó é preocupante sugerindo que existem assimetrias em Portugal e cabe a todos os intervenientes em Saúde Oral diminuí-las. O envolvimento de cada Médico Dentista neste processo é fundamental.

An investigation of environmental conditions experienced during the life of high-value wood components and products

Australian forest industries have a long history of export trade of a wide range of products from woodchips (for paper manufacturing), sandalwood (essential oils, carving and incense) to high value musical instruments, flooring and outdoor furniture. For the high value group, fluctuating environmental conditions brought on by changes in temperature and relative humidity, can lead to performance problems due to consequential swelling, shrinkage and/or distortion of the wood elements. A survey determined the types of value-added products exported, including species and dimensions packaging used and export markets. Data loggers were installed with shipments to monitor temperature and relative humidity conditions. These data were converted to timber equilibrium moisture content values to provide an indication of the environment that the wood elements would be acclimatising to. The results of the initial survey indicated that primary high value wood export products included guitars, flooring, decking and outdoor furniture. The destination markets were mainly located in the northern hemisphere, particularly the United States of America, China, Hong Kong, Europe (including the United Kingdom), Japan, Korea and the Middle East. Other regions importing Australian-made wooden articles were south-east Asia, New Zealand and South Africa. Different timber species have differing rates of swelling and shrinkage, so the types of timber were also recorded during the survey. Results from this work determined that the major species were ash-type eucalypts from south-eastern Australia (commonly referred to in the market as Tasmanian oak), jarrah from Western Australia, spotted gum, hoop pine, white cypress, black butt, brush box and Sydney blue gum from Queensland and New South Wales. The environmental conditions data indicated that microclimates in shipping containers can fluctuate extensively during shipping. Conditions at the time of manufacturing were usually between 10 and 12% equilibrium moisture content, however conditions during shipping could range from 5 (very dry) to 20% (very humid). The packaging systems incorporated were reported to be efficient at protecting the wooden articles from damage during transit. The research highlighted the potential risk for wood components to ‘move’ in response to periods of drier or more humid conditions than those at the time of manufacturing, and the importance of engineering a packaging system that can account for the environmental conditions experienced in shipping containers. Examples of potential dimensional changes in wooden components were calculated based on published unit shrinkage data for key species and the climatic data returned from the logging equipment. The information highlighted the importance of good design to account for possible timber movement during shipping. A timber movement calculator was developed to allow designers to input component species, dimensions, site of manufacture and destination, to see validate their product design.