Fracture resistance and failure mode of posterior fixed dental prostheses fabricated with two zirconia CAD/CAM systems

Background: In recent years there has been an improvement of zirconia ceramic materials to replace posterior missing teeth. To date little in vitro studies has been carried out on the fracture resistance of zirconia veneered posterior fixed dental prostheses. This study investigated the fracture resistance and the failure mode of 3-unit zirconia-based posterior fixed dental prostheses fabricated with two CAD/CAM systems. Material and Methods: Twenty posterior fixed dental prostheses were studied. Samples were randomly divided into two groups (n=10 each) according to the zirconia ceramic analyzed: Lava and Procera. Specimens were loaded until fracture under static load. Data were analyzed using Wilcoxon ́s rank sum test and Wilcoxon ́s signed-rank test ( P <0.05). Results: Partial fracture of the veneering porcelain occurred in 100% of the samples. Within each group, significant differences were shown between the veneering and the framework fracture resistance ( P =0.002). The failure occurred in the connector cervical area in 80% of the cases. Conclusions: All fracture load values of the zirconia frameworks could be considered clinically acceptable. The connector area is the weak point of the restoration

Public Health Considerations for PM₁₀ in a High-Pollution Megacity: Influences of Atmospheric Condition and Land Coverage

Restrictions apply to the availability of these data. Data was obtained from Red de Monitoreo de Calidad del Aire de Bogotá (RMCAB) and are available at http://201.245.192.252:81/Report/stationreport with the permission of RMCAB.[Abstract] This paper analyzes the PM₁₀ concentrations and influences of atmospheric condition (AC) and land coverage (LC) on a high-pollution megacity (Bogota, Colombia) from a public health viewpoint. Information of monitoring stations equipped with measuring devices for PM₁₀/temperature/solar-radiation/wind-speed were used. The research period lasted eight years (2007–2014). AC and LC were determined after comparing daily PM₁₀ concentrations (DPM₁₀) to reference limits published by the World Health Organization (WHO). ARIMA models for DPM₁₀ were also developed. The results indicated that urban sectors with lower atmospheric instability (AI) had a 2.85% increase in daily mortality (DM) in relation to sectors with greater AI. In these sectors of lower AI, impervious LC predominated, instead of vegetated LC. An ARIMA analysis revealed that a greater extent of impervious LC around a station led to a greater effect on previous days’ DPM₁₀ concentrations. Extreme PM₁₀ episodes persisted for up to two days. Extreme pollution episodes were probably also preceded by low mixing-layer heights (between 722–1085 m). The findings showed a 13.0% increase in WHO standard excesses (PE) for each 10 µg/m³ increase in DPM₁₀, and a 0.313% increase in DM for each 10% increase in PE. The observed average reduction of 14.8% in DPM₁₀ (−0.79% in DM) was probably due to 40% restriction of the traffic at peak hours.http://201.245.192.252:81/Report/stationrepor

Analysis of Particulate Matter Concentration Intercepted by Trees of a Latin-American Megacity

Restrictions apply to the availability of these data. Data was obtained from Red de Monitoreo de Calidad del Aire de Bogotá (RMCAB) and Botanical Garden of Bogotá (JBB), and are available at http://201.245.192.252:81/Report/stationreport (accessed on 6 February 2020) and http://sigau.jbb.gov.co/SigauJBB/VisorPublico/VisorPublico (accessed on 6 February 2020) with the permission of RMCAB and JBB, respectively.[Abstract] Urban areas with trees provide several ecosystem services to citizens. There is a growing interest in ecosystem services for the removal of air pollutants such as particulate matter. The objective of this paper is to show a study on the variation of intercepted particulate matter concentration (IPMC) by tree leaves in the megacity of Bogotá (Colombia). The relationship between IPMC and PM2.5 concentrations observed in air quality stations in two urban zones with different air pollutions was studied. Influences of climate and leaf morphology variables on IPMC were also analyzed. The species under study were Ligustrum-lucidum, Eucalyptus-ficifolia, Tecoma-stans, Callistemon-citrinus, Lafoensia-acuminata, and Quercus-humboldtii. The results showed that leaf IPMC decreased as the PM2.5 concentration increased. Species that best described this trend were Ligustrum-lucidum and Lafoensia-acuminata. These two species also showed the largest IPMC in their leaves. Indeed, species that showed the largest leaf area were those with the highest IPMC. On average, it was observed that for each 5.0 µg/m3 increase in PM2.5 concentration the IPMCs of the species Ligustrum-lucidum and Lafoensia-acuminata decreased by 33.6% and 23.1%, respectively. When wind speed increased, there was also an increase in PM2.5 concentrations and a reduction in the leaf IPMCs.http://201.245.192.252:81/Report/stationreporthttp://sigau.jbb.gov.co/SigauJBB/VisorPublico/VisorPublic

Diseño e implementación de un sistema computacional de peticiones, quejas y reclamos

CD-T 005.12 L881;100 p.Implementación de una herramienta informática para la solución de problemas logísticos relacionados con las peticiones, quejas y reclamos de los clientes de la empresa Transportes Terrestres del Risaralda ubicada en la ciudad de Pereira.Universidad Libre Seccional Pereir

Phosphogypsum weathering and implications for pollutant discharge into an estuary

Approximately 100 million tons of phosphogypsum were stockpiled onto marsh soils of the Tinto River estuary (Huelva, SW Spain). This study focuses on the hydraulic response of the phosphogypsum stack to the different weathering agents, as well as on the hydrochemical behavior of highly acidic and polluted effluents from its leaching during different hydrological conditions. To address these issues, a CTD-Diver was installed in a bore-hole within a phosphogypsum stack profile, which recorded the variations in the water-table of the stack, and edge outflows samples were collected around the perimeter of the stack during four sampling periods in different seasons. During dry periods, the water-table of the stack remains almost static and is controlled only by the tide oscillations. However, during rainy events this water-level rapidly increases up to 20 cm and subsequently decreases, defining peaks that coincide with the rainfalls. Having a hydraulic connection to the sea and groundwater flow in conduits, the phosphogypsum stack behaves as an anthropogenic karstic-coastal aquifer. Regarding the hydrochemical behavior of the edge outflows, the concentrations of most pollutants (e.g., PO4, Al, As, Cd or U) showed a slight decrease from the dry-warm to the rainy period. These leachates releases high concentrations of contaminants to the estuary, e.g., PO4, As and U (average values of 5000, 6.9 and 3.0 t/yr, respectively). The results obtained in this study could contribute to the development of effective treatment systems for leachates from phosphogypsum stack of Huelva and to minimize their impact on the surrounding estuarine environment.This work was supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund and the University of Huelva under the research projects TRAMPA (MINECO; PID2020-119196RB-C21), VALOREY (MINECO; RTI 2018-101276-JI00) and EMFHA-SIST (FEDER; UHU-486 1253533). C.R C´anovas thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference RYC2019- 027949-I. Funding for open access charge: Universidad de Huelva/ CBUA. We would also like to thank Dr. Huaming Guo (Editor-in-Chief) and two anonymous re-viewers for the support and comments that significantly improved the quality of the original paper

Impact of COVID-19 Pandemic on University Students' Physical Activity Levels: An Early Systematic Review

[EN] Purpose: This systematic review aimed to analyze the impact that the COVID-19 lockdown had on the amount of physical activity performed by university students. Materials and Methods: A systematic electronic search for studies providing information regarding physical activity levels pre and during COVID-19 pandemic in university students was performed up to 20th October 2020 in the databases Cochrane Library, PubMed, SPORTDiscus, and Web of Science. The risk of bias of external validity quality of included studies was assessed by means of those the Newcastle-Ottawa Scale (NOS). The quality of the evidence for main outcomes was graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Results and Conclusions: A total of 10 studies were selected. Physical activity levels were assessed by means of questionnaires (10 studies) and accelerometer (1 study). Risk of bias was regarded as low and high in six and four investigations, respectively. The quality of evidence was downgraded to low. A significant reduction of physical activity levels were observed in 9 studies. Compared to pre-lockdown values, five studies showed a reduction of light/mild physical activity (walking) between 32.5 and 365.5%, while seven studies revealed a reduction of high/vigorous physical activity between 2.9 and 52.8%. Walking, moderate, vigorous, and total physical activity levels have been reduced during the COVID-19 pandemic confinements in university students of different countries. Despite of the reductions, those who met the current minimum PA recommendations before the lockdown generally met the recommendations also during the confinements

Arquitectura reconfigurable basada en redes de difracción de Bragg para redes convergentes indoor ópticas

This paper presents an approach for dynamic reconfiguration of wavelength channels for future indoor network architectures. The approach exploits the tunability and the rejection profile of Fiber Bragg Gratings (FBG) to implement service distribution strategies that includes Unicast, Broadcast and Multicast scenarios for fixed and mobile users. Experimental demonstrations based on two implementations show results with 1% average degradation for Error Vector Magnitude (EVM) values and up to 2,2 dB for 1x10-12 Bit Error Rate (BER). In particular, the proposed architectures fit for large in-building networksEste artículo presenta una propuesta para la implementación de reconfiguración dinámica de canales ópticos en futuras arquitecturas de red tipo indoor. La propuesta se basa en las características de sintonización y perfil de rechazo de Redes de Difracción de Bragg (FBG) para implementar estrategias de distribución de servicios de tipo Unicast, Broadcast y Multicast a usuarios en redes indoor tipo campus. La demostración experimental, que incluye dos diferentes implementaciones, muestra resultados con un 1% en promedio de degradación en la magnitud del vector de error (EVM) para los servicios inalámbricos y penalizaciones de potencia de hasta 2,2 dB de penalización para una tasa de error de bit (BER) de 1x10-12 para los servicios fijos

Comparative analysis of trueness between conventional and digital impression in dental-supported fixed dental prosthesis with vertical preparation

Biologically oriented preparation technique (BOPT) is a vertical preparation technique without a finish line to create a new anatomic crown with a prosthetic emergence profile. This case report describe the protocol realized digitally in a patient who required a new fixed partial denture (FPD) in the anterior esthetic zone. After time of temporary restoration, definitive conventional (CI) (double-cord retraction and vinyl polysiloxane material), and digital impression (DI) with three different intraoral scanner (IOS) (Trios®, True Definition® and iTero®) were taken. All digital impression were obtained through three different scans: temporary restoration in the mouth after healing period, prepared teeth, and temporary restoration out of the mouth. To establish which of the IOS was the most accurate, it was necessary to compare the STL files obtained from each of the IOS with the STL file of the conventional impression, which was digitized with a laboratory scanner (3Shape D800). All these STL were imported to a software (ExoCAD 2.4 Plovdiv®), and they were superimposed. To establish the difference in trueness with SC, 6 points were chosen, 3 points in teeth, and another 3 points in soft tissue. The mean measurement in terms of trueness in teeth were: STS (0,039 mm), SI (0,054 mm), STD (0,067 mm); and in soft tissue were: STS (0,051 mm), SI (0,09 mm), STD [0,236 mm]. The IOSs showed differences between them in terms of trueness, being the Trios the most accuracy IOS. Final restoration was fabricated and cemented. The patient was examined at 3, 6 and 12 months, without any type of biological or mechanical complications. Digital impression with an IOS seems to be a viable alternative to perform zirconia FPD in the BOPT tecbique

Nucleation and growth of gold nanoparticles in the presence of different surfactants: a dissipative particle dynamics study

Colloids; Computational chemistry; NanoparticlesColoides; Química computacional; NanopartículasCol·loides; Química computacional; NanopartículesNanoparticles (NPs) show promising applications in biomedicine, catalysis, and energy harvesting. This applicability relies on controlling the material’s features at the nanometer scale. Surfactants, a unique class of surface-active molecules, have a remarkable ability to tune NPs activity; provide specific functions, avoid their aggregation, and create stable colloidal solutions. Surfactants also control nanoparticles’ nucleation and growth processes by modifying nuclei solubility and surface energy. While nucleation seems independent from the surfactant, NP’s growth depends on it. NP`s size is influenced by the type of functional group (C, O, S or N), length of its C chain and NP to surfactant ratio. In this paper, gold nanoparticles (Au NPs) are taken as model systems to study how nucleation and growth processes are affected by the choice of surfactants by Dissipative Particle Dynamics (DPD) simulations. DPD has been mainly used for studying biochemical structures, like lipid bilayer models. However, the study of solid NPs, and their conjugates, needs the introduction of a new metallic component. To represent the collective phenomena of these large systems, their degrees of freedom are reduced by Coarse-Grained (CG) models. DPD behaved as a powerful tool for studying complex systems and shedding some light on some experimental observations, otherwise difficult to explain.Authors are gratefully acknowledged for a fellowship to R.S-L provided by Universitat Autònoma de Barcelona, and for the financial support obtained through grant number RTI2018-099965-B-I00 from Ministerio de Ciencia, Innovación y Universidades, Spain. NGB and VP acknowledge financial support from R&D&I projects for international joint programming from MCIN/AEI (CONCORD, PCI2019-103436) cofunded by the European Union and from Generalitat de Catalunya (2017-SGR-1431). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya

Physical activity, dietary habits and sleep quality before and during COVID-19 lockdown: A longitudinal study

[EN] The COVID-19 pandemic has forced the health public authorities to impose a lockdown as an epidemiological containment strategy. This study aimed to provide information regarding the impact of the mandatory confinement on the physical activity, eating disorders risk, sleep quality and well-being on a Spanish sample. An online survey that included the Minnesota Leisure Time Physical Activity Questionnaire, the Eating Attitude Test-26, and Pittsburgh Sleep Quality Index was administered two days after the state of alarm was stablished in Spain and five days after such measures began to be eased. Out of the 693 people who answered the first questionnaire, 161 completed the second one. These participants spent a total of 48 days locked at home, a period during which a significant worsening in all the variables assessed except for the risk of developing eating disorders, was observed: weight (kg), 67.3 ± 14.8 vs 67.7 ± 15.1, p = 0.012; physical activity (MET minutes per week), 8515.7 ± 10260.0 vs 5053.5 ± 5502.0, p < 0.001; sleep problems (total score), 6.2 ± 3.5 vs 7.2 ± 3.9, p < 0.001; self-perceived well-being (score), 4 (3–4) vs 3 (3–4), p < 0.001. The confinement had a significant differential effect on physically active participants, who experienced a significant decline (p < 0.05) on their physical activity levels, quality of sleep and well-being; whereas physically inactive participants did not experience significant changes. Findings from this longitudinal study indicate that a lockdown period due to COVID-19 had a negative impact on the physical activity levels, sleep quality and well-being in a group of physically active Spanish adults. Public health authorities should be aware that people who usually lead an active lifestyle, might be particularly susceptible to such disruptionsS