116 research outputs found

    The Impact of Plasma Treatment of Cercon® Zirconia Ceramics on Adhesion to Resin Composite Cements and Surface Properties

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    Background: In recent years, the use of Ceramic base zirconia is considered because of chemical stability, biocompatibility, good compressive and flexural strength in dentistry for all ceramic restorations. However, due to its chemical stability, there is a challenge with dental bonding. Several studies have done to improving zirconia bonding but they are not reliable. Purpose of this research is a study of effect of plasma on bonding strength Zirconia.  Methods: In this research zirconia blocks' surfaces polished with 1200grit sandpaper. Samples were processed with plasma of oxygen, argon, air and oxygen-argon combination with 90-10 and 80-20 ratio.  Surface modifications were evaluated by contact angle, surface roughness, and topographical assessments. Cylindrical Panavia f2 resin-cement and Diafill were used for micro shear strength bond measurements. The data analysis was performed by SPSS 20.0 software and one-way analysis of variance. Results: The results showed that plasma can increase micro cutting bond strength, decrease surface roughness, increase surface activation energy. Maximum cutting bond strength by using Panavia f2 cement, is for air and argon plasma, and by using margin bond and Diafill composition cement, is for air and combination of oxygen and argon with 20-80 ratio.  Conclusion: According to this research plasmatic processing with dielectric barrier method in atmospheric pressure can increase Zirconia bonding strength

    Cytotoxicity of Selected Nanoparticles on Human Dental Pulp Stem Cells

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    Introduction: Nanoparticles are being increasingly applied in dentistry due to their antimicrobial and mechanical properties. This in vitro study aimed to assess and compare the cytotoxicity of four metal oxide nanoparticles (TiO2, SiO2, ZnO, and Al2O3) on human dental pulp stem cells. Methods and Materials: Four suspension with different concentrations (25, 50, 75, 100 µg/mL) of each nanoparticle were prepared and placed into cavities of three 96-well plates (containing 1×104 cells per well that were seeded 24 earlier). All specimens were incubated in a humidified incubator with 5% CO2 at 37°C. Mosmann’s Tetrazolium Toxicity (MTT) assay was used to determine in vitro cytotoxicity of test materials on pulpal stem cells. Cell viability was determined at 24, 48, and 72 h after exposure. Data comparisons were performed using a general linear model for repeated measures and Tukey's post hoc test. The level of significance was set at 0.05. Results: The tested nanoparticles showed variable levels of cytotoxicity and were dose and time dependant. The minimum cell viability was observed in ZnO followed by TiO2, SiO2 and Al2O3. Conclusion: The results demonstrated that cell viability and morphological modifications occurred at the concentration range of 25 to 100 µg/mL and in all nanoparticles. The higher concentration and longer duration of exposure increased cellular death. Our results highlight the need for a more discrete use of nanoparticles for biomedical applications.Keywords: Cytotoxicity; Dental Pulp Stem Cells; Metal Oxide Nanoparticle

    Analyses, calibration and validation of evapotranspirationmodels to predict grass-reference evapotranspiration in theSenegal river delta

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    Study region: Grass-reference evapotranspiration estimation by the Penman-Monteithmethod (PM-ETo) requires a number of climate variables which are not always availableat all weather stations. Different alternative ETo equations have been developed and theirutilization for various local climate conditions requires analyses of their accuracy as com-pared to the standardized Penman-Monteith method. There is a significant lack of data andinformation on this topic in the Senegal River Delta (SRD). Study focus: The objective of this study was to evaluate, calibrate and validate six EToequations ((Trabert, Mahringer, Penman1948, Albrecht, Valiantzas1 and Valiantzas2) forthe SRD. Although all six equations showed good agreement with the PM-ETo (R2\u3e 0.60)for daily ETo estimates, the Valiantzas2 equation was the best model for the Senegal RiverDelta and had the lowest root mean squared difference (RMSE) of 0.45 mm/day and thelowest percent error of estimate (PE) about 7.1%. New hydrological insights for the region: In the case of data limitations, the equationscalibrated in this study are recommended for ETo estimation in the Senegal River Delta. Theresults of this study could be used by agricultural producers, crop consultants, universityresearchers, policy makers for the agricultural, hydrological, and environmental studies aswell as proper allocation and use and forecasting in the SRD where lowland irrigated riceis predominant

    Prevalence of Cardiac Depression and its Related Factors among Patients with Acute Coronary Syndrome

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    Cardiac depression is one of the most common psychological reactions of patients with acute coronary syndrome (ACS).This study aimed to determine the prevalence of cardiac depression and its related factors among patients with ACS. Thiscross-sectional study was conducted during 2016 in patients with ACS who were admitted to hospitals affiliated to theMazandaran University of Medical Sciences, Iran. In the present study, 407 patients completed the Cardiac DepressionScale (CDS) within two months (March - June). The data were analyzed by a chi-square test and a general linear modelmultivariate analysis. According to the results, the mean cardiac depression score in patients with ACS was 109.00 ± 16.49(CI95: 107.39 to 110.60). Among the participants, 37 (9.1%), 72 (17.7%), and 298 (73.2%) patients had mild, moderate,and severe levels of depression, respectively. Although the two-way ANOVA was not significant, but there was a differencebetween cardiac depression score of a type of ACS. Given the high prevalence of cardiac depression among these patients,it is necessary to develop measures for routine screening in cardiac treatment units

    Local impact analysis of climate change on precipitation extremes : are high-resolution climate models needed for realistic simulations?

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    This study explores whether climate models with higher spatial resolutions provide higher accuracy for precipitation simulations and/or different climate change signals. The outputs from two convection-permitting climate models (ALARO and CCLM) with a spatial resolution of 3-4 km are compared with those from the coarse-scale driving models or reanalysis data for simulating/projecting daily and sub-daily precipitation quantiles. Validation of historical design precipitation statistics derived from intensityduration-frequency (IDF) curves shows a better match of the convection-permitting model results with the observations-based IDF statistics compared to the driving GCMs and reanalysis data. This is the case for simulation of local subdaily precipitation extremes during the summer season, while the convection-permitting models do not appear to bring added value to simulation of daily precipitation extremes. Results moreover indicate that one has to be careful in assuming spatial-scale independency of climate change signals for the delta change downscaling method, as high-resolution models may show larger changes in extreme precipitation. These larger changes appear to be dependent on the timescale, since such intensification is not observed for daily timescales for both the ALARO and CCLM models

    The CORDEX.be initiative as a foundation for climate services in Belgium

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    The CORDEX.be project created the foundations for Belgian climate services by producing high-resolution Belgian climate information that (a) incorporates the expertise of the different Belgian climate modeling groups and that (b) is consistent with the outcomes of the international CORDEX ("COordinated Regional Climate Downscaling Experiment") project. The key practical tasks for the project were the coordination of activities among different Belgian climate groups, fostering the links to specific international initiatives and the creation of a stakeholder dialogue. Scientifically, the CORDEX.be project contributed to the EURO-CORDEX project, created a small ensemble of High-Resolution (H-Res) future projections over Belgium at convection-permitting resolutions and coupled these to seven Local Impact Models. Several impact studies have been carried out. The project also addressed some aspects of climate change uncertainties. The interactions and feedback from the stakeholder dialogue led to different practical applications at the Belgian national level

    Discordance in diagnosis of osteoporosis using spine and hip bone densitometry

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    BACKGROUND: Diagnostic discordance for osteoporosis is the observation that the T-score of an individual patient varies from one key measurement site to another, falling into two different diagnostic categories identified by the World Health Organization (WHO) classification system. This study was conducted to evaluate the presence and risk factors for this phenomenon in a large sample of Iranian population. METHODS: Demographic data, anthropometric measurements, and risk factors for osteoporosis were derived from a database on 4229 patients referred to a community-based outpatient osteoporosis testing center from 2000 to 2003. Dual-energy X-ray absorptiometry (DXA) was performed on L1–L4 lumbar spine and total hip for all cases. Minor discordance was defined as present when the difference between two sites was no more than one WHO diagnostic class. Major discordance was present when one site is osteoporotic and the other is normal. Subjects with incomplete data were excluded. RESULTS: In 4188 participants (3848 female, mean age 53.4 ± 11.8 years), major discordance, minor discordance, and concordance of T-scores were seen in 2.7%, 38.9% and 58.3%, respectively. In multivariate logistic regression analysis, older age, menopause, obesity, and belated menopause were recognized as risk factors and hormone replacement therapy as a protective factor against T-score discordance. CONCLUSION: The high prevalence of T-score discordance may lead to problems in interpretation of the densitometry results for some patients. This phenomenon should be regarded as a real and prevalent finding and physicians should develop a particular strategy approaching to these patients

    Heat stress increase under climate change twice as large in cities as in rural areas : a study for a densely populated midlatitude maritime region

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    Urban areas are usually warmer than their surrounding natural areas, an effect known as the urban heat island effect. As such, they are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine unprecedented long-term (35years) urban climate model integrations at the convection-permitting scale (2.8km resolution) with information from an ensemble of general circulation models to assess temperature-based heat stress for Belgium, a densely populated midlatitude maritime region. We discover that the heat stress increase toward the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heat waves, and urban expansion. Cities experience a heat stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat stress surpasses everywhere the urban hot spots of today. Our results demonstrate the need to combine information from climate models, acting on different scales, for climate change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas

    The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

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    Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe
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