Effective boundary conditions for dense granular flows

We derive an effective boundary condition for granular flow taking into account the effect of the heterogeneity of the force network on sliding friction dynamics. This yields an intermediate boundary condition which lies in the limit between no-slip and Coulomb friction; two simple functions relating wall stress, velocity, and velocity variance are found from numerical simulations. Moreover, we show that this effective boundary condition corresponds to Navier slip condition when GDR MiDi's model is assumed to be valid, and that the slip length depends on the length scale that characterises the system, \emph{viz} the particle diameter.Comment: 4 pages, 5 figure

Characterization of virulence factors in the newly described <i>Salmonella enterica</i> serotype Keurmassar emerging in Senegal (sub-Saharan Africa)

From 2000 to 2001, nine strains of Salmonella enterica belonging to the new serotype Keurmassar have been isolated from human and poultry samples at the Senegalese National Salmonella and Shigella Reference Laboratory at the Pasteur Institute, in Dakar. All strains carried virulence factors including Salmonella Pathogenicity Islands (SPI)-1, -2, -3 and -5 encoded genes. Strains did not harbour virulence plasmid. Ribotyping analysis revealed a single clone identical to Salmonella Decatur isolated in Zimbabwe. These data suggest that strains are closely related, and may have been spread clonally. In this new serotype, insertion sequence IS200 is not present

Shear bands in granular flow through a mixing length model

We discuss the advantages and results of using a mixing-length, compressible model to account for shear banding behaviour in granular flow. We formulate a general approach based on two function of the solid fraction to be determined. Studying the vertical chute flow, we show that shear band thickness is always independent from flowrate in the quasistatic limit, for Coulomb wall boundary conditions. The effect of bin width is addressed using the functions developed by Pouliquen and coworkers, predicting a linear dependence of shear band thickness by channel width, while literature reports contrasting data. We also discuss the influence of wall roughness on shear bands. Through a Coulomb wall friction criterion we show that our model correctly predicts the effect of increasing wall roughness on the thickness of shear bands. Then a simple mixing-length approach to steady granular flows can be useful and representative of a number of original features of granular flow.Comment: submitted to EP

Solid-state compatibility of Ca:LaNbO4 with perovskite cathodes: Evidences from X-ray microspectroscopy

The solid-state compatibility between calcium-doped lanthanum niobate and three perovskite cathode materials was investigated using two X-ray microbeam techniques, micro X-ray fluorescence and micro X-ray absorption spectroscopy. The cathode powders (lanthanum strontium ferrite, either cobalt or copper-doped, and lanthanum strontium cobaltite) in contact with the dense electrolyte pellet were annealed at 1150°C for 12–144 h to simulate the effect of thermal stresses due to fabrication and long-term operation. As a result, several interdiffusion phenomena were then observed on the bilayer cross-sections: in particular, the chemical state and coordination environment of calcium, iron, niobium and lanthanum were probed with space-resolved X-ray absorption spectroscopy. The ab initio modeling of the near-edge X-ray absorption spectra reveal that the cation interdiffusion is facilitated by the structural flexibility of the perovskite structure, which is able to accommodate a variety of foreign cations in different oxidation states. Limited stability at high-temperatures was found for all candidate perovskite compositions in contact with lanthanum niobate

Strategies in Outsourcing R&D Processes to Maintain Market Competitiveness

In the 21st century, managing outsourced research and development (R&D) processes is critical to an organization\u27s success. Guided by the logistic outsourcing theory developed by de Boer, Gaytan, and Arroyo, the purpose of this single case study was to explore strategies and processes organizational leaders used to manage outsourced R&D to maintain market competitiveness. Semistructured interviews were conducted with 5 purposefully selected business leaders who were responsible for outsourcing R&D in a single Fortune 500 corporation in the Mid-Atlantic region of the United States. Company records were also gathered as data. Yin\u27s 5-step process for a case study and key words in context analysis were used to analyze the data. Findings included 3 main themes: (a) the outsourcing decision-making process with internal and external constraints, (b) the effectiveness of managing outsourcing services and processes, and (c) the influence of outsourcing on business effectiveness and new products. Findings also indicated no practical system to measure effectiveness of outsourced R&D services on market competitiveness. The lack of measurement effectiveness was due to a lack of processes in place to measure R&D performance and no practical approach to measure impact of R&D on market competitiveness. Findings offered insight into strategies used by business leaders to manage outsourced R&D processes. Findings may also have implications for positive social change such as impacting communities through employment, generating government revenues through taxes, and creating a positive impact on job creation in the industries that promote R&D outsourcing

Maternal and fetal fatty acid composition in ovine muscle tissues

In species characterized by a cotyledonary placenta, as sheep, the relative contribution of maternally derived and placenta synthesized fatty acids is not fully understood. For this reason, the FA composition of mother muscle and the deposition of FA in the fetal muscle were studied by gas-chromatography. Five pregnant Sarda ewes were slaughtered at approximately 145 days of pregnancy. Semitendinosus, semimembranosus and femoral biceps muscles were immediately removed from ewes and fetuses. Data were analyzed by a paired t-test, to detect differences in FA composition between fetus and mother tissues. Results showed that FA profile of fat muscle differed markedly between fetus and mother. The intramuscular fat content were 6.38% and 11.79% on DM basis in fetus and mother muscle, respectively. Linoleic (LA; 18:2n-6), and linolenic (ALA; 18:3n-3) acid were found at smaller concentrations in fetus (0.77 and 0.01 mg/100 mg total FA for LA and ALA, respectively) than in maternal muscle (5.55 and 1.04 for LA and ALA, respectively). On the contrary, a higher proportion of their long-chain polyunsaturated metabolites, like arachidonic (AA; 20:4n-6) and docoexadienoic (DHA; 22:6n-3) acid in fetus compared to mother tissue (AA, 2.32 vs 1.30; DHA, 0.83 vs 0.09 mg/100 mg total FA) indicates a preferential fetal accumulation of those FA which are important for fetuses growth and central nervous system development. The c9,t11 Conjugated linoleic acid (CLA) isomer concentration in mother tissue was 0.72 mg/100 mg FA. It was found also in fetus muscle (0.11 mg/100 mg total FA) suggesting a transplacental fatty acid passage to fetal tissues or a desaturation activity on vaccenic acid (VA; 18:1 t11) in the placental or in the fetal tissue. Surprisingly, the c9,t11-CLA was not the most abundant CLA isomer found in fetus fat. Others CLA isomers, separated but not identified, were found in concentration of 0.17, 0.15 and 0.53 mg/100 mg of FA. Concentrations of these CLA isomers were lower in mother tissue (0.12, 0.05 and 0.10 mg/100 mg of FA). The concentration of VA was 0.46 and 0.90 in fetus and mother muscle, respectively. Correlation analysis between FA profile of mothers and fetuses evidenced a close relationship only for odd-numbered long-chain fatty (r = -0.72 for C15:0 and r = -0.88 for C17:0). The results suggested a different FA metabolism in the muscle tissue of mother and fetus in dairy sheep

Effects of industrial processing on pesticide multiresidues transfer from raw tomatoes to processed products

Pesticides are broadly used to improve food safety, although they can lead to adverse health effects on consumers. Various food processing approaches, at the industrial or domestic level, have been found to highly reduce the amount of pesticide residues in most food materials. In this work, samples of raw tomatoes were collected directly from the field and processed at the industrial level to produce purée, triple concentrated paste, fine pulp, and diced tomatoes. A multiresidue method based on a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged e Safe) sample preparation, followed by liquid chromatography‐tandem mass spectrometry analysis (LC‐MS/MS) for the assessment of 116 pesticides residues, was used. The analytical method has been validated according to SANTE indications. The recovery yields ranged from 75.5% to 115.3%, repeatability (RSDr) ranged from 3.4% to 18.3%, while reproducibility (RSDwR) ranged from 5.4% to 19.8%. The limit of quantifications (LOQs) ranged from 2.35 μg kg−1 for benthiavalicarb to 6.49 μg kg−1 for allethrin. A total of 159 raw tomato samples were collected from the field. The analysis showed the presence of 46 pesticides with azoxystrobin and chlorantraniliprole the most represented. On the other hand, all industrially processed samples showed values ≤ LOD, confirming that post‐harvest processes can lead to a decrease in pesticide residues from agricultural commodities

Efficient three-dimensional survey techniques and their comparison in open software in the archaeological test site of "Ninfeo Maggiore" and "Ninfeo Minore" of Formia (Latina, Italy)

In Europe and beyond, the cultural and archaeological heritage may have considerable extensions of hundreds of square metres if not kilometres. It is then necessary to study highly efficient techniques able , at the same time, to maintain centimetric accuracy. In these contexts, the SLAM technique can be an efficient solution. We tested the latter in a survey of a portion of the so-called Roman Villa of Caposele, also known as Villa Rubino in Formia, (Italy): the "Ninfeo Maggiore"and "Ninfeo Minore"(Major and Minor nymphaeum). The two structures had to be surveyed for both conservation and study purposes and to allow a virtual visit, which is particularly important since they are located inside a private property. The structure is complex, with a succession of rooms and environments in an archaeological complex extending approximately 480 metres in an east-west direction and approximately 50 metres in a south-north direction. We decided to survey both nymphaea with the "GEOSLAM Zeb Horizon", also surveying all the internal connecting rooms and corridors between them. Both nymphaea were also surveyed with a "Faro"terrestrial laser scanning, to allow comparison. To verify the validity of the SLAM on the outside, a survey was carried out using a DJI Matrix drone with laser scanning. The comparison showed very limited deviations whose statistical validation is in progress, demonstrating that the SLAM technique can advantageously be used in such vast archaeological complexes where the efficiency and completeness of the survey is more important than the millimetric accuracy.</p

An Exploratory Assessment of Applying Risk Management Practices to Engineered Nanomaterials

The widespread industrial application of nanotechnology has increased the number of workers exposed to engineered nanomaterials (ENMs), but it is not clear to what extent prevention guidance is practiced. Our aim was to explore the extent that companies manufacturing and/or using ENMs apply risk assessment and management measures. Thirty-four companies were surveyed with an international 35-item questionnaire investigating company and workforce features, types of ENM handled, and risk evaluation and preventive measures adopted. Among participating companies, 62% had a maximum of 10 employees. Metal-based nanomaterials were most frequently identified (73%). Environmental monitoring was performed by 41% of the companies, while engineering exposure controls were approximately reported by 50%. Information and training programs were indicated by 85% of the sample, only 9% performed specific health surveillance for ENM workers. Personal protective equipment primarily included gloves (100%) and eye/face protection (94%). This small-scale assessment can contribute to the limited amount of published literature on the topic. Future investigations should include a greater number of companies to better represent ENM workplaces and a direct access to industrial settings to collect information on site. Finally, deeper attention should be paid to define standardized frameworks for ENM risk assessment that may guide nano-specific preventive actions