A study on PDC drill bits quality

The quality of innovating PDC (Polycrystalline Diamond Compact) bits materials needs to be determined with accuracy by measuring cutting efficiency and wear rate, both related to the overall mechanical properties. An original approach is developed to encompass cutting efficiency and wear contribution to the overall sample quality. Therefore, a lathe-type test device was used to abrade specific samples from various manufacturers. Post-experiment analyzes are based on models establishing coupled relationships between cutting and friction stresses related to the drag bits excavation mechanism. These models are implemented in order to evaluate cutting efficiency and to estimate wear of the diamond insert. Phase analysis by XRD and finite element simulations were performed to explain the role of physicochemical parameters on the calculated quality factor values. Four main properties of PDC material were studied to explain quality results obtained in this study: cobalt content in samples that characterizes hardness/fracture toughness compromise, undesired phase as tungsten carbide weakening diamond structure, diamond grains sizes and residual stresses distribution affecting abrasion resistance

Hydrogen bonding and coordination in normal and supercritical water from X-ray inelastic scattering

A direct measure of hydrogen bonding in water under conditions ranging from the normal state to the supercritical regime is derived from the Compton scattering of inelastically-scattered X-rays. First, we show that a measure of the number of electrons $n_e$ involved in hydrogen bonding at varying thermodynamic conditions can be directly obtained from Compton profile differences. Then, we use first-principles simulations to provide a connection between $n_e$ and the number of hydrogen bonds $n_{HB}$. Our study shows that over the broad range studied the relationship between $n_e$ and $n_{HB}$ is linear, allowing for a direct experimental measure of bonding and coordination in water. In particular, the transition to supercritical state is characterized by a sharp increase in the number of water monomers, but also displays a significant number of residual dimers and trimers.Comment: 14 pages, 5 figures, 1 tabl

Phonon dispersion and lifetimes in MgB2

We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experiment. Anomalous broadening of the E_2g phonon mode is found all along Gamma-A. The dominant contribution to the linewidth is always the electron-phonon coupling.Comment: 4 pages, 3 figure

O Mapa das Cortes: perspectivas cartográficas

O presente trabalho realiza uma análise exaustiva do Mapa das Cortes, aplicando critérios da cartografia, em particular da cartografia matemática. Assim, analisam-se: autor, escala, projeção, meridiano de origem, cores, convenções, simbologia e outros. Após uma análise morfológica qualitativa, passa-se a um exame quantitativo, comparando esse mapa com um atual, bastante preciso: com o auxílio de um programa de cartografia digital e uma planilha eletrônica foram comparadas as coordenadas geográficas (latitude e longitude) de mais de 430 pontos. A quantificação sistemática e detalhada dos erros em diferentes regiões, da costa atlântica à região amazônica, mostrou aspectos surpreendentes de como o Mapa das Cortes (MC) foi habilmente construído. Essa análise permitiu quantificar de maneira mais precisa as distorções, identificando em que locais foram introduzidas e seu caráter indubitavelmente proposital.In this paper, we present a thorough analysis of the Map of the Courts based on criteria used in cartography, particularly mathematical cartography. As such, it takes into account the following elements: author, scale, projection, the prime meridian, colors, conventions, symbology, and other. After a qualitative morphological analysis, we move on to a quantitative examination by comparing the said map with a quite accurate present-day chart, using a digital cartography software application and spreadsheet to match the geographic coordinates (latitude and longitude) of over 430 points. The systematic and detailed quantification of errors in various areas, from the Atlantic coast to the Amazon region, revealed surprising aspects as to how skillfully the Map of the Courts was constructed. This analysis enabled us to quantify the distortions more accurately and thus identify the locations where they were introduced as well their unquestionable intentional character

Linear programming can help identify practical solutions to improve the nutritional quality of food aid.

OBJECTIVES: To assess the nutritional quality of food aid delivered by food banks in France and to identify practical modifications to improve it. DESIGN: National-level data were collected for all food aid distributed by French food banks in 2004, and its nutrient content per 2000 kcal was estimated and compared with French recommendations for adults. Starting with the actual donation and allowing new foods into the food aid donation, linear programming was used to identify the minimum changes required in the actual donation to achieve the French recommendations. RESULTS: French food-bank-delivered food aid does not achieve the French recommendations for dietary fibre, ascorbic acid, vitamin D, folate, magnesium, docosahexaenoic acid, alpha-linolenic acid and the percentage of energy from saturated fatty acids. Linear programming analysis showed that these recommendations are achievable if more fruits, vegetables, legumes and fish were collected and less cheese, refined cereals and foods rich in fat, sugar and/or salt. In addition, new foods not previously collected are needed, particularly nuts, wholemeal bread and rapeseed oil. These changes increased the total edible weight (42%) and economic value (55%) of the food aid donation, with one-third of its edible weight coming from fruits and vegetables, one-third from staples, one-quarter from dairy products and approximately a tenth from meat/fish/eggs. CONCLUSIONS: Important changes in the types and amounts of food collected will improve the nutritional quality of food-bank-delivered food aid in France. Such changes are recommended to improve the diets of deprived French populations

Metastatic Pancreatic Adenocarcinoma After Total Pancreatectomy Islet Autotransplantation for Chronic Pancreatitis

Total pancreatectomy with islet autotransplantation (TPIAT) is being used increasingly as a definitive treatment for chronic pancreatitis. Patients with chronic pancreatitis have an elevated risk of pancreatic cancer, which can also masquerade as acute or chronic pancreatitis, making the diagnosis challenging. We describe here the first case of pancreatic ductal adenocarcinoma developing in the liver of a patient after TPIAT for presumed benign chronic pancreatitis. Retrospective analysis of the patient’s preoperative serum revealed normal carbohydrate antigen 19-9 and carcinoembryonic antigen levels but elevated levels of microRNAs -10b, -30c, and -106b compared with controls. Screening guidelines are important to reduce the risk of transplantation of malignant tissue. More sensitive screening tools, including the potential use of microRNAs, are needed to detect early preclinical disease, given the highly malignant nature of pancreatic cancer