Effect of thickness on shrinkage stress and bottom‐to‐top hardness ratio of conventional and bulk‐fill composites

2021 ◽  
Author(s):  
Daniella Cristo Santin ◽  
Marilia Mattar de Amoêdo Campos Velo ◽  
Francielly da Silva Camim ◽  
Nair Cristina Margarido Brondino ◽  
Heitor Marques Honório ◽  
...  
Keyword(s):  
Shrinkage Stress ◽  
Hardness Ratio ◽  
Bottom To Top

Extensive Assessment of the Physical, Mechanical, and Adhesion Behavior of a Low-viscosity Bulk Fill Composite and a Traditional Resin Composite in Tooth Cavities

2017 ◽  
Vol 42 (5) ◽  
pp. E159-E166 ◽  
Author(s):  
RX Sousa-Lima ◽  
LJA Silva ◽  
LVF Chaves ◽  
S Geraldeli ◽  
RCB Alonso ◽  
...  
Keyword(s):  
Resin Composite ◽  
Testing Machine ◽  
Physical And Mechanical Properties ◽  
Bending Test ◽  
Shrinkage Stress ◽  
Three Point Bending ◽  
Low Viscosity ◽  
Adhesion Behavior ◽  
Bottom To Top ◽  
Push Out

SUMMARY Objectives: To compare the degree of conversion (DC), depth of polymerization (DP), shrinkage stress (SS), flexural strength (FS), elastic modulus (EM), and bond strength (BS) of a low-viscosity bulk fill resin composite and a paste-like traditional composite. Methods: Tetric Evo-Flow Bulk Fill (TBF) and Empress Direct (ED; Ivoclar Vivadent) composites were used. DC (%) and FS/EM (MPa/GPa) were evaluated in bar specimens (7×2×1 mm; n=10) using Fourier-transform infrared spectroscopy and a three-point bending test in a universal testing machine (UTM), respectively. For DP and BS tests, conical cavities (n=10) were prepared in bovine dentin and restored with the composites. DP was analyzed by calculating the bottom-to-top surface microhardness ratio (BTHR), and BS (MPa) was determined by push-out testing in the UTM. SS (MPa) was measured for one increment of TBF and two increments of ED in a UTM attached to an extensometer (n=5). Data were analyzed using Student t-test and analysis of variance (α=0.05). Results: TBF presented higher values than ED for DC (85.7±6.6% vs 54.2±4.9%) and BS (0.95±0.70 MPa vs 0.35±0.15 MPa). TBF values were lower than ED values for FS (76.6±16.8 MPa vs 144.9±24.1 MPa) and maximum SS (0.77±0.07 MPa vs 1.07±0.15 MPa). TBF and ED values were similar for BTHR (0.83±0.16 vs 0.84±0.08) and EM (11.5±2.8 GPa vs 12.5±2.6 GPa). Conclusions: The physical and mechanical properties of TBF, a bulk fill resin composite, were similar or superior to those of ED, a conventional composite, with the exception of FS measurements.

Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes

2018 ◽  
Vol 43 (2) ◽  
pp. 136-143 ◽  
Author(s):  
JK Gan ◽  
AU Yap ◽  
JW Cheong ◽  
N Arista ◽  
CBK Tan
Keyword(s):  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Energy Output ◽  
Significance Level ◽  
Light Emitting ◽  
Soft Start ◽  
Significant Difference ◽  
Hardness Ratio ◽  
Post Hoc ◽  
Bottom To Top

SUMMARY This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm2 (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm2 (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm2 (5 seconds) → 1200 mW/cm2 (10 seconds); Bluephase N Monowave (NM), 800 mW/cm2 (15 seconds); QHL75 (QH), 550 mW/cm2 (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm2 for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37°C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% ± 5.19% to 49.25% ± 6.38% for TNC and 50.67% ± 1.54% to 67.62% ± 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.

INFLUENCE OF FORCED CONVECTION IN LIQUID INSIDE THE TIN ON DURATION OF STERILIZATION IN THE COURSE OF FISH PROCESSING

2017 ◽  
pp. 137-144
Author(s):  
Gennadiy Valentinovich Alexeev ◽  
Elena Igorevna Verboloz
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Forced Convection ◽  
Thermal Process ◽  
Processing Time ◽  
Fish Processing ◽  
Study Results ◽  
Equipment Modernization ◽  
Bottom To Top

The article focuses on the process of intensive mixing of liquid phase in the tin during high-temperature sterilization, i.e. sterilization when temperature of the heat carrier reaches 150-160°C. It has been stated that for intensification of the thermal process during sterilization of tinned fish with liquid filling it is preferable to turn a tin from bottom to top. This operation helps to increase the driving power of the process and to shorten warming time. Besides, high-temperature sterilization carried out according to experimental modes, where the number of tin turnovers is calculated, greatly shortens processing time and improves quality of the product. In this case there is no superheating, all tins are evenly heated. The study results will contribute to equipment modernization and to preserving valuable food qualities.

scholarly journals Associations Between Music Training and the Dynamics of Writing Music by Hand

2020 ◽  
pp. 102986492097214
Author(s):  
Aurélien Bertiaux ◽  
François Gabrielli ◽  
Mathieu Giraud ◽  
Florence Levé
Keyword(s):  
Classical Music ◽  
Music Notation ◽  
Musical Score ◽  
Music Training ◽  
Video Recordings ◽  
Musical Structures ◽  
Music Recognition ◽  
High Level ◽  
Bottom To Top ◽  
Western Classical Music

Learning to write music in the staff notation used in Western classical music is part of a musician’s training. However, writing music by hand is rarely taught formally, and many musicians are not aware of the characteristics of their musical handwriting. As with any symbolic expression, musical handwriting is related to the underlying cognition of the musical structures being depicted. Trained musicians read, think, and play music with high-level structures in mind. It seems natural that they would also write music by hand with these structures in mind. Moreover, improving our understanding of handwriting may help to improve both optical music recognition and music notation and composition interfaces. We investigated associations between music training and experience, and the way people write music by hand. We made video recordings of participants’ hands while they were copying or freely writing music, and analysed the sequence in which they wrote the elements contained in the musical score. The results confirmed experienced musicians wrote faster than beginners, were more likely to write chords from bottom to top, and they tended to write the note heads first, in a flowing fashion, and only afterwards use stems and beams to emphasize grouping, and add expressive markings.

scholarly journals Uterine Cervical Change at Term Examined Using Ultrasound Elastography: A Longitudinal Study

2020 ◽  
Vol 10 (1) ◽  
pp. 75
Author(s):  
Hyun Soo Park ◽  
Hayan Kwon ◽  
Ja-Young Kwon ◽  
Yun Ji Jung ◽  
Hyun-Joo Seol ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Cervical Length ◽  
Labor Induction ◽  
Ultrasound Elastography ◽  
Antenatal Visit ◽  
Mean Values ◽  
Nulliparous Women ◽  
Hardness Ratio ◽  
Cesarean Delivery Rate ◽  
Time Of Admission

The aim of the study was to investigate if there are changes in elastographic parameters in the cervix at term around the time of delivery and if there are differences in the parameters between women with spontaneous labor and those without labor (labor induction). Nulliparous women at 36 weeks of gestation eligible for vaginal delivery were enrolled. Cervical elastography was performed and cervical length were measured using the E-CervixTM system (WS80A Ultrasound System, Samsung Medison, Seoul, Korea) at each weekly antenatal visit until admission for spontaneous labor or labor induction. E-Cervix parameters of interest included elasticity contrast index (ECI), internal os strain mean level (IOS), external os strain mean level (EOS), IOS/EOS strain mean ratio, strain mean level, and hardness ratio. Regression analysis was performed using days from elastographic measurement at each visit to admission for delivery and the presence or absence of labor against cervical length, and each E-Cervix parameter fitted to a linear model for longitudinal data measured repeatedly. A total of 96 women were included in the analysis, (spontaneous labor, n = 39; labor induction, n = 57). Baseline characteristics were not different between the two groups except for cesarean delivery rate. Cervical length decreased with advancing gestation and was different between the two groups. Most elastographic parameters including ECI, IOS, EOS, strain mean, and hardness ratio were significantly different between the two groups. In addition, ECI, IOS, and strain mean values significantly increased with advancing gestation. Our longitudinal study using ultrasound elastography indicated that E-cervix parameters tended to change linearly at term near the time of admission for delivery and that there were differences in E-Cervix parameters according to the presence or absence of labor.

scholarly journals High-resolution isotope stratigraphy of the Lower Ordovician St. George Group of western Newfoundland, Canada: implications for global correlation

2009 ◽  
Vol 46 (6) ◽  
pp. 403-423 ◽  
Author(s):  
Karem Azmy ◽  
Denis Lavoie
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Sea Level Changes ◽  
Global Correlation ◽  
Lower Ordovician ◽  
Isotope Stratigraphy ◽  
Platform Carbonates ◽  
The Baltic ◽  
Marine Platform ◽  
Bottom To Top

The Lower Ordovician St. George Group of western Newfoundland consists mainly of shallow-marine-platform carbonates (∼500 m thick). It is formed, from bottom to top, of the Watts Bight, Boat Harbour, Catoche, and Aguathuna formations. The top boundary of the group is marked by the regional St. George Unconformity. Outcrops and a few cores from western Newfoundland were sampled at high resolution and the extracted micritic materials were investigated for their petrographic and geochemical criteria to evaluate their degree of preservation. The δ13C and δ18O values of well-preserved micrite microsamples range from –4.2‰ to 0‰ (VPDB) and from –11.3‰ to –2.9‰ (VPDB), respectively. The δ13Ccarb profile of the St. George Group carbonates reveals several negative shifts, which vary between ∼2‰ and 3‰ and are generally associated with unconformities–disconformities or thin shale interbeds, thus reflecting the effect of or link with significant sea-level changes. The St. George Unconformity is associated with a negative δ13Ccarb shift (∼2‰) on the profile and correlated with major lowstand (around the end of Arenig) on the local sea-level reconstruction and also on those from the Baltic region and central Australia, thus suggesting that the St. George Group Unconformity might have likely had an eustatic component that contributed to the development–enhancement of the paleomargin. Other similar δ13Ccarb shifts have been recorded on the St. George profile, but it is hard to evaluate their global extension due to the low resolution of the documented global Lower Ordovician (Tremadoc – middle Arenig) δ13Ccarb profile.

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