scholarly journals Thermogravimetric study of the behaviour of organic and inorganic polymers contained in four dental resin-based composites

2020 ◽  
pp. 096739112096753
Author(s):  
Thibault Canceill ◽  
Paul Pages ◽  
Sarah Garnier ◽  
Jany Dandurand ◽  
Sabine Joniot
Keyword(s):  
Thermal Stability ◽  
Resin Composite ◽  
Inorganic Polymers ◽  
Dental Resin ◽  
Humid Atmosphere ◽  
Water Imbibition ◽  
Before And After ◽  
Dimensional Variation ◽  
Loss Of Mass ◽  
Over Time

The composition of dental resin-based composite (RBC) matrix is partly responsible for many clinical failures in restorations, which may come from dimensional variation or instability in a wet environment. The objective of this study is therefore to evaluate the thermal stability over time of four dental RBC with different matrices. Silicone cylinders were filled with four different materials and then photopolymerized. To simulate ageing in the buccal environment, half of the samples were placed in a dark place at 37°C for 45 days in sealed compartments containing 2 ml of water. All the RBC produced were subjected to thermogravimetric analysis to measure the loss of mass as a function of temperature. Bis-GMA-based resins and Ormocer materials have similar curves before and after soaking in humid atmosphere. The curves of the UDMA resin are different before and after water ageing, meaning that water imbibition has modified the structure of the composite and its degradation. Even if many curves are similar within the same RBC at different polymerization times or at different pre- and post-ageing times, it is rare to observe a common kinetics between two different composites. Our results show good wet stability of polymerized dental RBC according to the manufacturer’s instructions, although the UDMA-based materials show more variation. It therefore seems that Ormocer resin composite with mass placement have ageing properties that can compete with those of conventional composites whereas those incremented on 2 mm layers are more sensitive to the time necessary for polymerization.

Inhibitive Effect of a New Dental Resin Composite on Enamel Artificial Caries

2014 ◽  
Vol 1058 ◽  
pp. 323-328
Author(s):  
Xin Yi Zhao ◽  
Shao Jie Hou ◽  
Shi Bao Li
Keyword(s):  
Resin Composite ◽  
Surface Hardness ◽  
Filling Material ◽  
Dental Resin ◽  
Buffer Solution ◽  
Partially Saturated ◽  
Enamel Demineralization ◽  
Restorative Materials ◽  
Before And After

Purpose To investigate the cariostatic effect of six restorative materials in vitro. Method Enamel blocks of bovine incisors were restored with six restorative materials (a conventional GIC, FujiIILC, Compoglass F, BeautifilII,Charisma and an experimental fluoride releasing resin composite) respectively with a gap of 270μm in width between each filling material and enamel. Then all restorations were immersed in a partially saturated acidic buffer solution at 37C for 3days. The surface enamel microhardness of the enamel blocks were measured before and after demineralization and the depth of enamel demineralization was measured using polarization microscope for each restoration.Results Enamel surface hardness of all restorations demonstrated significant reduced after demineralization ( p<0.05), and the order of hardness reduction is as follows: Charisma >BeautifilII≈Compoglass F≈Experimental Resin>FujiIILC>GIC ( p> 0.05). The order of the depth of enamel demineralization along the surface and the interface near the gap for the 5 materials is as follows: Charisma >BeautifilII≈Compoglass F ≈Experimental Resin>FujiIILC>GIC (P > 0.05). Conclusion The new fluoride releasing and recharging composite resin has the ability to prevent recurrent caries around the restoration and its ability is comparable to compomer materials.

Weekly Exercise Consistently Reinstates Positive Mood

1998 ◽  
Vol 3 (4) ◽  
pp. 271-280 ◽  
Author(s):  
Hannah Steinberg ◽  
Briony R. Nicholls ◽  
Elizabeth A. Sykes ◽  
N. LeBoutillier ◽  
Nerina Ramlakhan ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Negative Mood ◽  
Real Life ◽  
Positive Mood ◽  
Field Investigation ◽  
Single Bout ◽  
Before And After ◽  
Exercise Class ◽  
Negative Feelings ◽  
Over Time

Mood improvement immediately after a single bout of exercise is well documented, but less is known about successive and longer term effects. In a “real-life” field investigation, four kinds of exercise class (Beginners, Advanced, Body Funk and Callanetics) met once a week for up to 7 weeks. Before and after each class the members assessed how they felt by completing a questionnaire listing equal numbers of “positive” and “negative” mood words. Subjects who had attended at least five times were included in the analysis, which led to groups consisting of 18, 20, 16, and 16 subjects, respectively. All four kinds of exercise significantly increased positive and decreased negative feelings, and this result was surprisingly consistent in successive weeks. However, exercise seemed to have a much greater effect on positive than on negative moods. The favorable moods induced by each class seemed to have worn off by the following week, to be reinstated by the class itself. In the Callanetics class, positive mood also improved significantly over time. The Callanetics class involved “slower,” more demanding exercises, not always done to music. The Callanetics and Advanced classes also showed significantly greater preexercise negative moods in the first three sessions. However, these differences disappeared following exercise. Possibly, these two groups had become more “tolerant” to the mood-enhancing effects of physical exercise; this may be in part have been due to “exercise addiction.”

UK Fiscal Squeezes over a Century

2017 ◽  
Author(s):  
Christopher Hood ◽  
Rozana Himaz
Keyword(s):  
Data Sources ◽  
Fiscal Consolidation ◽  
Financial Outcomes ◽  
Financial Conditions ◽  
Deficit Reduction ◽  
Before And After ◽  
The Uk ◽  
Changes Over Time ◽  
Spending Cuts ◽  
Over Time

This chapter draws on historical statistics reporting financial outcomes for spending, taxation, debt, and deficit for the UK over a century to (a) identify quantitatively and compare the main fiscal squeeze episodes (i.e. major revenue increases, spending cuts, or both) in terms of type (soft squeezes and hard squeezes, spending squeezes, and revenue squeezes), depth, and length; (b) compare these periods of austerity against measures of fiscal consolidation in terms of deficit reduction; and (c) identify economic and financial conditions before and after the various squeezes. It explores the extent to which the identification of squeeze episodes and their classification is sensitive to which thresholds are set and what data sources are used. The chapter identifies major changes over time that emerge from this analysis over the changing depth and types of squeeze.

scholarly journals Effect of sizing agent on interfacial properties of carbon fiber-reinforced PMMA composite

2021 ◽  
Vol 30 ◽  
pp. 2633366X2097865
Author(s):  
Li Jian
Keyword(s):  
Shear Strength ◽  
Surface Treatment ◽  
Photoelectron Spectroscopy ◽  
Resin Composite ◽  
Contact Angles ◽  
Static Contact ◽  
Before And After ◽  
C Value ◽  
Interlayer Shear Strength ◽  
Pmma Resin

The surface treatment of carbon fibers (CFs) was carried out using a self-synthesized sizing agent. The effects of sizing agent on the surface of CFs and the interface properties of CF/polymethyl methacrylate (PMMA) composites were mainly studied. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and static contact angle were used to compare and study the CFs before and after the surface treatment, including surface morphology, surface chemical element composition, and wettability of the surface. The influence of sizing agent on the mechanical properties of CF/PMMA resin composite interface was investigated. The results show that after sizing treatment, the CF surface O/C value increased by 35.1% and the contact angles of CF and resin decreased by 16.2%. The interfacial shear strength and interlayer shear strength increased by 12.6%.

scholarly journals Land Policy and Food Prices: Evidence from a Land Consolidation Program in Rwanda

2021 ◽  
Vol 19 (1) ◽  
pp. 63-73
Author(s):  
Aimable Nsabimana ◽  
Fidele Niyitanga ◽  
Dave D. Weatherspoon ◽  
Anwar Naseem
Keyword(s):  
Food Prices ◽  
Land Policy ◽  
Land Consolidation ◽  
Easy Access ◽  
Food Crops ◽  
White Potato ◽  
Before And After ◽  
Price Differences ◽  
The Impact ◽  
Over Time

Abstract Rwanda’s “Crop Intensification Program (CIP)” is primarily a land consolidation program aimed at improving agricultural productivity and food security. The program, which began in 2007, focuses on monocropping and commercialization of six priority crops: maize, wheat, rice, white potato, beans, and cassava. CIP has facilitated easy access to improved seed stocks, fertilizer, extension services, and postharvest handling and storage services. Although studies have documented the impact of CIP on changes in farm yield, incomes, and productivity, less is known about its impact on food prices. In this study, we examine the crop-food price differences in intensive monocropped CIP and non-intensive monocropped CIP zones in Rwanda. Specifically, the study evaluates price variations of beans and maize along with complementary food crops in intensive and non-intensive monocropped zones before and after the introduction of the CIP policy. We find that the CIP policy is not associated with differences in CIP crop prices between the intensive and non-intensive monocropped zones. Over time, prices increased for CIP crops but generally, the crop prices in the two zones were cointegrated. Prices for non-CIP crops in the two different zones did show price differentials prior to the implementation of CIP, with the prices in intensive monocropped zones being greater than in the non-intensive monocropped zones. Moreover, the prices in intensive areas are cointegrated with prices in non-intensive areas for maize and beans and these prices are converging. This indicates that farmers who intensively produced one CIP crop were able to go to the market and purchase other food crops and that price differences between zones have decreased over time, potentially making the CIP intensive farmers better off.

How Collective-Action Failure Shapes Group Heterogeneity and Engagement in Conventional and Radical Action Over Time

2021 ◽  
pp. 095679762097056
Author(s):  
Morgana Lizzio-Wilson ◽  
Emma F. Thomas ◽  
Winnifred R. Louis ◽  
Brittany Wilcockson ◽  
Catherine E. Amiot ◽  
...  
Keyword(s):  
Social Movements ◽  
Collective Action ◽  
Latent Profile Analysis ◽  
Profile Analysis ◽  
Social Identification ◽  
Future Research ◽  
Group Efficacy ◽  
Before And After ◽  
Using Data ◽  
Over Time

Extensive research has identified factors influencing collective-action participation. However, less is known about how collective-action outcomes (i.e., success and failure) shape engagement in social movements over time. Using data collected before and after the 2017 marriage-equality debate in Australia, we conducted a latent profile analysis that indicated that success unified supporters of change ( n = 420), whereas failure created subgroups among opponents ( n = 419), reflecting four divergent responses: disengagement (resigned acceptors), moderate disengagement and continued investment (moderates), and renewed commitment to the cause using similar strategies (stay-the-course opponents) or new strategies (innovators). Resigned acceptors were least inclined to act following failure, whereas innovators were generally more likely to engage in conventional action and justify using radical action relative to the other profiles. These divergent reactions were predicted by differing baseline levels of social identification, group efficacy, and anger. Collective-action outcomes dynamically shape participation in social movements; this is an important direction for future research.

354 Trends in the Drug-Sparing Effects for Benzodiazepines and Prescription Opioids among Insomnia Patients on Suvorexant in the US

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A141-A141
Author(s):  
Hrishikesh Kale ◽  
Rezaul Khandker ◽  
Ruchit Shah ◽  
Marc Botteman ◽  
Weilin Meng ◽  
...  
Keyword(s):  
Interrupted Time Series ◽  
Charlson Comorbidity Index Score ◽  
Prescription Opioid ◽  
Prescription Opioids ◽  
Opioid Use ◽  
Before And After ◽  
Prescription Opioid Use ◽  
Incident Cohort ◽  
Over Time ◽  
Post Period

Abstract Introduction Use of benzodiazepines to treat insomnia has been associated with serious side effects and abuse potential. Insomnia patients are at high risk of opioid abuse and better sleep patterns may help to reduce opioid use. This study examined the trend in the use of benzodiazepines and prescription opioids before and after initiation of suvorexant in insomnia patients. Methods The study analyzed 2015–2019, Optum Clinformatics Data Mart. Insomnia patients, identified using ICD-9/10 codes and prescribed suvorexant were included. The study included incident (newly diagnosed) and prevalent cohorts of insomnia patients. The proportion of patients on benzodiazepines or prescription opioids were calculated for 12 monthly intervals before (pre-period) and after initiation of suvorexant (post-period). Interrupted time series (ITS) analysis was conducted to assess trends for use of benzodiazepine or prescription opioids over time. Results A total of 5,939 patients from the incident insomnia cohort and 18,920 from the prevalent cohort were included. For the incident cohort, mean age was 64.47 (SD: 15.48), 63% were females, 71% had Medicare Advantage coverage, 59% had Charlson comorbidity index score (CCI) ≥ 1, 27% had an anxiety disorder and 16% had substance abuse disorder. Prevalent insomnia cohort was similar but had higher CCI. Results from ITS suggested that at the beginning of the pre-period, 28% of incident insomnia patients used either opioids or benzodiazepines with the rate of use in the pre-period increasing by 0.11% per month. In the post-period, the rate of use decreased by 0.33% per month. About 26% patients used benzodiazepines or opioids at 12-month after suvorexant initiation. In the absence of suvorexant, this proportion would have been 31%. Similar findings were observed for the prevalent insomnia cohort. A larger decrease was observed for opioid use than benzodiazepines. Conclusion The rate of benzodiazepines or prescription opioid use decreased over time after the initiation of suvorexant. Suvorexant has the potential to reduce the use of opioids and benzodiazepines among insomnia patients. Further research is needed to confirm these findings. Support (if any) This study was sponsored by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

scholarly journals Oral rehydration therapies in Senegal, Mali, and Sierra Leone: a spatial analysis of changes over time and implications for policy

BMC Medicine ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Kirsten E. Wiens ◽  
Lauren E. Schaeffer ◽  
Samba O. Sow ◽  
Babacar Ndoye ◽  
Carrie Jo Cain ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Healthcare Access ◽  
Scale Up ◽  
National Policy ◽  
Geostatistical Model ◽  
Oral Rehydration ◽  
Severe Diarrhea ◽  
Before And After ◽  
Changes Over Time ◽  
Over Time

Abstract Background Oral rehydration solution (ORS) is a simple intervention that can prevent childhood deaths from severe diarrhea and dehydration. In a previous study, we mapped the use of ORS treatment subnationally and found that ORS coverage increased over time, while the use of home-made alternatives or recommended home fluids (RHF) decreased, in many countries. These patterns were particularly striking within Senegal, Mali, and Sierra Leone. It was unclear, however, whether ORS replaced RHF in these locations or if children were left untreated, and if these patterns were associated with health policy changes. Methods We used a Bayesian geostatistical model and data from household surveys to map the percentage of children with diarrhea that received (1) any ORS, (2) only RHF, or (3) no oral rehydration treatment between 2000 and 2018. This approach allowed examination of whether RHF was replaced with ORS before and after interventions, policies, and external events that may have impacted healthcare access. Results We found that RHF was replaced with ORS in most Sierra Leone districts, except those most impacted by the Ebola outbreak. In addition, RHF was replaced in northern but not in southern Mali, and RHF was not replaced anywhere in Senegal. In Senegal, there was no statistical evidence that a national policy promoting ORS use was associated with increases in coverage. In Sierra Leone, ORS coverage increased following a national policy change that abolished health costs for children. Conclusions Children in parts of Mali and Senegal have been left behind during ORS scale-up. Improved messaging on effective diarrhea treatment and/or increased ORS access such as through reducing treatment costs may be needed to prevent child deaths in these areas.

The Analysis of Reinforcing the Bottom Chord around the Tapped Holes Based on the Thermosetting Resin Composite Materials

2012 ◽  
Vol 531 ◽  
pp. 609-612
Author(s):  
Xue Dong Han ◽  
Li Wei ◽  
Gang Luo ◽  
Li Ping Chang
Keyword(s):  
Composite Material ◽  
Resin Composite ◽  
Steel Bridge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Steel Truss Bridge ◽  
The Finite Element Analysis ◽  
Before And After ◽  
Truss Bridge

The intensity of the joint in the bottom chord would affect the quality of the whole bridge because that the force of the bottom-through bridge is transferred mainly through the bottom chord, and the members of the truss connect each other by using the thread. In this paper, the bottom chord around the tapped holes is reinforced by composite material , and the stress on the bottom chord is analyzed before and after the reinforcement using the finite element analysis method, and the stress distributions in the directions of X,Y and Z on every layer of the composite material under the bilateral reinforcing condition are extracted and compared. The results show that: Reinforcing the bottom chord around the tapped holes using the composite material can change the stress level of the bottom chord effectively, helping to improve the quality of the construction of the steel bridge and the effect of the bilateral reinforcing is better than the unilateral reinforcing and providing certain reference for the security of the steel truss bridge

Impact of Resin Composite Viscosity and Fill-technique on Internal Gap in Class I Restorations: An OCT Evaluation

2021 ◽  
Author(s):  
KR Kantovitz ◽  
LL Cabral ◽  
NR Carlos ◽  
AZ de Freitas ◽  
DC Peruzzo ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Resin Composite ◽  
Oral Care ◽  
High Viscosity ◽  
Class I ◽  
Low Viscosity ◽  
Significant Difference ◽  
Before And After ◽  
Internal Adaptation ◽  
Internal Gap

SUMMARY The aim of this in vitro study was to quantitatively evaluate the internal gap of resin composites of high-and low-viscosity used in single- and incremental-fill techniques in Class I cavities exposed to thermal cycling (TC) using optical coherence tomography (OCT). Cavities of 4-mm depth and 3-mm diameter were prepared in 36 third molars randomly distributed into four groups, according to viscosity of restorative resin-based composite (high or low viscosity, all from 3M Oral Care) and technique application (bulk or incremental fill) used (n=9): RC, high-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Universal Restorative); BF, high-viscosity, bulk-fill, resin-based composite (Filtek One Bulk Fill); LRC, low-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Flowable Universal Restorative); and LBF, low-viscosity, bulk-fill, resin-based composite (Filtek Flowable Restorative). Single Bond Universal Adhesive system (3M Oral Care) was used in all the experimental groups. The incremental-fill technique was used for RC and LRC groups (2-mm increments), and a single-layer technique was used for BF and LBF groups, as recommended by the manufacturer. The internal adaptation of the resin at all dentin walls was evaluated before and after TC (5000 cycles between 5°C and 55°C) using OCT images. Five images of each restored tooth were obtained. Images were analyzed using ImageJ software that measured the entire length of the gaps at the dentin–restoration interface. The length of gaps (μm) was analyzed using two-way repeated measures ANOVA and the Tukey tests (α=0.05). There was a significant interaction between material types and TC (p=0.006), and a significant difference among all material types (p&lt;0.0001), before and after TC (p&lt;0.0001). Increased internal gaps at the dentin–restoration interface were noticed after TC for all groups. RC presented the lowest value of internal gap before and after TC, while LBF showed the highest values of internal gap after TC. In conclusion, TC negatively affected the integrity of internal gap, whereas high-viscosity, incremental-fill, resin-based composite presented better performance in terms of internal adaptation than low-viscosity, bulk-fill materials in Class I cavities.

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