3-D computational fluid dynamics for gas and gas-particle flows in a cyclone with different inlet section angles

A three-dimensional computational fluid dynamics (CFD) Reynolds stress model (RSM) was used to describe the gas and gas-solid flow in a cyclone with a scroll inlet duct at three different inlet section angles in relation to the cyclone body. The effects of the inlet section angles on the fluid dynamics inside the cyclone and on the performance parameters (collection efficiency and pressure drop) were analyzed by means of the finite volume method using a computational code and an industrial-sized cyclone for separation of gas-particle phases operated by Votorantim Cimentos Company. The numerical results show that the value for overall collection efficiency in this work increased to 77.2% for the 45° inlet section angle, while that for the normal inlet duct was 54.4% under the same operating conditions.     

Industry–research co‐operation within and across regional boundaries. What does innovation policy add?

The paper aims to show how regional policy‐makers can stimulate firms' co‐operation with research organizations by granting an R&D subsidy. Using an original dataset for the Italian region of Emilia‐Romagna, propensity score matching is first applied to identify the impact of the subsidy received. A generalized propensity score technique is then employed to investigate the effect of an increasing amount of support. The firm's co‐operation is policy sensitive. The award of a subsidy to regional firms affects their intra‐regional more than their extra‐regional co‐operation. The propensity toward the latter appears subject to a monetary effect and is influenced by the amount of public funding received providing the subsidy overcomes a minimum threshold.     

Treatment of the regional lymph nodes in squamous carcinoma of the penis

OBJECTIVES: We evaluated the management of the regional lymph nodes to determine the appropriate treatment for carcinoma of the penis. METHODS: The records of 36 patients with carcinoma of the penis were reviewed. Lymphadenectomy was performed in 18 patients, 17 were managed conservatively (watchful waiting) and 1 patient had a biopsy and received radiotherapy. RESULTS: Positive nodes were found in 2 of 2 pT4, 2 of 3 pT3, 8 of 13 pT2 and 2 of 12 pT1 patients submitted to lymphadenectomy. Concerning the histological grade, positive nodes were found in all of the 4 G3, 5 of 12 G2 and 3 of 20 G1 patients. The survival rate was 100% for the patients with negative lymph nodes (pNO = 6) or a single positive inguinal lymph node (pN1 = 5). A correlation was found between the T and the histological grade and the likelihood of lymph node invasion. CONCLUSIONS: The T and the histological grade of the primary lesion must be considered when deciding the approach in the management of the lymph nodes as unnecessary lymphadenectomy can be avoided and those at high risk of lymph node invasion can be treated radically and timely.     

Effects of slope exposure,altitude and yield on coffee quality in two altitude terroirs of Costa Rica,Orosi and Santa María de Dota

This study assessed the effects of slope exposure, altitude and yield on several cup quality criteria of coffees from two altitude terroirs of Costa Rica, Orosi (between 1020 and 1250 m above sea level) and Santa María de Dota (between 1550 and 1780 m above sea level). East‐facing slopes gave beverages with generally superior attributes, probably owing to better exposure to morning sunlight. These beverages were mainly more acid: at Orosi an acidity score of 2.73 out of 5 was obtained (3.64 for Santa María de Dota) for eastern exposures, as opposed to 2.36 on average (3.28 for Santa María de Dota) for other exposures. In addition, a positive relation was found between altitude and taster preferences in both terroirs. A negative relation was also found between yield and beverage acidity at Santa María de Dota, where some coffee trees produced up to 13 kg of coffee cherry. Coffees from Orosi were characterised by a floral flavour, which depended on slope exposure, whilst coffees from Santa María de Dota displayed a chocolate taste, which was more marked at high altitude. In both terroirs the caffeine, trigonelline, fat, sucrose and chlorogenic acid contents were not well correlated with the sensory characteristics. Copyright © 2005 Society of Chemical Industry     

Low temperature synthesis of zircon from silicone resins and oxide nano-sized particles

In this paper we present a new route for the realization of crack-free zircon monoliths, at very low temperature (1200 °C). Zircon ceramics are for the first time synthesized from a mixture of preceramic polymers, consisting of silicone resins, filled with active nano-sized fillers, being ZrO₂ nano-particles. The introduction of small quantities (up to 10 mol%) of TiO₂ as a sintering aid, and of zircon micro-powders, as seeds, has been also considered. The additives demonstrated to be extremely effective in increasing the zircon yield, with a synergistic effect when used together. Moreover, an appropriate mixture of different preceramic polymers as SiO₂ source was found to be critical for the obtainment of crack-free monoliths. This simple methodology demonstrated kinetic features comparable to those of sol–gel processes, but coupled with the possibility of an easy shaping of the desired ceramic before heat treatment.     

The association of dental caries with blood lead in children when adjusted for IQ and neurobehavioral performance

Associations between childhood lead exposures and dental caries in children have been reported for over 30 years, with widely varying findings and conclusions, and using measures of lead exposure which ranged from food sources and water to tooth, hair or blood lead concentrations. OBJECTIVES: This study examined the relationship of lead exposure and dental caries in a population of normatively healthy children. METHODS: This cross-sectional study used a population of 507 children aged 8-12 who were participating in a clinical trial of dental materials to examine the relationship between lead and caries. Blood lead concentrations and dental caries were examined for association in both primary and permanent teeth. Because it is possible that neurobehavioral status could be associated with both lead exposure and dental caries prevalence, we also examined neurobehavioral status of the subjects. RESULTS: A gender-specific association (males only) between lead exposure and dental caries was found in primary teeth only. Neurobehavioral measures and IQ were not associated with caries status in this population. CONCLUSIONS: This study did not support neurobehavioral status as mediating any association between lead exposure and caries in a normatively healthy population. A gender-specific association between lead and caries not previously reported was found in primary teeth, and no biological explanation for this has been suggested. We conclude that this study provides only weak evidence, if any, for an association of low-level lead exposure with dental caries.     

Parametric and nonparametric inference for the reliability of copula-based stress-strength models

This paper provides a general treatment of statistical inference for the reliability in copula-based stress-strength models. Most of the current literature is either focused on specific models that yield clean formulas or restricted to estimation and engineering aspects without addressing statistical inference. We present two general frameworks, one parametric, one nonparametric, for the estimation of the reliability. The parametric methodology is presented under the general framework of estimating equations, mostly as a combination of existing methodologies from the fields of multivariate analysis, reliability, and econometrics, with some new results. The nonparametric methodology is a novel application based on an existing bivariate kernel method combined with Monte Carlo estimation of the reliability without specification of the copula or the margins. We present results from a small simulation study designed to assess the robustness of the methods discussed in terms of model misspecification. We used geotechnical data and data from the Brazilian Household Survey to illustrate the proposed methodologies in the estimation of factors of safety and financial fragility.     

Functionalization of polydimethylsiloxane membranes to be used in the production of voice prostheses

Abstract

The voice is produced by the vibration of vocal cords which are located in the larynx. Therefore, one of the major consequences for patients subjected to laryngectomy is losing their voice. In these cases, a synthetic one-way valve set (voice prosthesis) can be implanted in order to allow restoration of speech. Most voice prostheses are produced with silicone-based materials such as polydimethylsiloxane (PDMS). This material has excellent properties, such as optical transparency, chemical and biological inertness, non-toxicity, permeability to gases and excellent mechanical resistance that are fundamental for its application in the biomedical field. However, PDMS is very hydrophobic and this property causes protein adsorption which is followed by microbial adhesion and biofilm formation. To overcome these problems, surface modification of materials has been proposed in this study. A commercial silicone elastomer, Sylgard^TM 184 was used to prepare membranes whose surface was modified by grafting 2-hydroxyethylmethacrylate and methacrylic acid by low-pressure plasma treatment. The hydrophilicity, hydrophobic recovery and surface energy of the produced materials were determined. Furthermore, the cytotoxicity and antibacterial activity of the materials were also assessed. The results obtained revealed that the PDMS surface modification performed did not affect the material's biocompatibility, but decreased their hydrophobic character and bacterial adhesion and growth on its surface.     

Optimal buffer inventory and preventive maintenance for an imperfect production process

In this paper we present a model to determine the optimal length of continuous production periods between maintenance actions and the optimal buffer inventory to satisfy demand during preventive maintenance or repair of a manufacturing facility. We include in the model the possibility of imperfect production. We consider that the duration and cost of the maintenance action depend on the state of the production facility.