scholarly journals Effect of Ultrasonic Vibration on Structural and Physical Properties of Resin-Based Dental Composites

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2054
Author(s):  
Abdul Samad Khan
Keyword(s):  
Physical Properties ◽  
Structural Changes ◽  
Hybrid Composites ◽  
Dental Composites ◽  
Micro Computed Tomography ◽  
Ultrasonic Activation ◽  
Linear Behavior ◽  
The Difference ◽  
Post Hoc ◽  
Flowable Composites

This study aimed to investigate the influence of ultrasonic heat before photo-polymerization on the structural and physical properties of dental composites. Commercially available bulk-fill, nano-hybrid, micro-hybrid, and flowable composites were used. The samples were divided into three groups i.e., (i) without ultrasonic activation, (ii) ultrasonic activation at 15 Hz for 30 s, and (iii) ultrasonic activation at 15 Hz for 60 s. The degree of conversion percentage (DC%) and structural changes were evaluated with Fourier transform infrared spectroscopy. The presence of voids in restored tooth cavities were investigated with micro-computed tomography. The statistical analysis was performed using a one-way analysis of variance (ANOVA) post hoc Tukey’s test. The DC% was significantly increased with ultrasonic application in all groups except for flowable composites, whereby flowable composite showed a significant increase with 30 s ultrasonic activation only. The highest DC% was observed in 60 s ultrasonically activated nano-hybrid and micro-hybrid composites. The voids were reduced linearly with ultrasonic application in flowable and bulk-fill composites; however, non-linear behavior was observed with micro-hybrid and nano-hybrid composites, whereby the difference was significant within the groups. The frequency and time of the ultrasonic application is an important factor to consider and can be used to preheat composites before clinical application.

High disease activity is associated with higher blood pressure in recent onset rheumatoid arthritis patients, post-hoc analyses of IMPROVED study

2021 ◽  
Vol 28 (Supplement_1) ◽  
Author(s):  
M Gegenava ◽  
SA Bergstra ◽  
H Maassen ◽  
CF Allaart
Keyword(s):  
Rheumatoid Arthritis ◽  
Blood Pressure ◽  
Disease Activity ◽  
Classification Criteria ◽  
Recent Onset ◽  
American College Of Rheumatology ◽  
Cardiovascular Morbidity And Mortality ◽  
The Difference ◽  
Post Hoc ◽  
Acpa Status

Abstract Funding Acknowledgements Type of funding sources: None. Background Rheumatoid arthritis (RA) is a chronic autoimmune disease with a high prevalence of cardiovascular morbidity and mortality. Purpose: purpose of our project was to investigate the association between disease activity and systolic and diastolic blood pressure (SBP, DBP) in patients with recent-onset rheumatoid arthritis (RA 2010 criteria) or undifferentiated arthritis (UA) who were treated to target disease activity score (DAS)<1.6 in the IMPROVED study. Methods: The associations between disease activity and SBP/DBP were tested for 610 patients (364 RA, 246 UA), cross-sectionally and over time. GEE analyses were performed with both SBP and DBP as outcome measures and disease activity categories (DAS<1.6;>1.6 but ≤2.4; >2.4), CRP level, treatment arms or the number of visits on a certain drug as potential predictors in separate analyses. Separate analyses tested potential contributions of gender, anti-cyclic citrullinated peptide antibodies (ACPA) status, and fulfilling the 2010 ACR/EULAR (American college of rheumatology/ European league against rheumatism) classification criteria. In addition association of BP with various levels of disease activity was tested with T-test. Results: At the baseline mean (SD) SBP was 133 (20) and DBP mean (SD) was 80 (10).  SBP > 140mm Hg was observed in 40% of patients and DBP > 90 mm Hg  in 21% of patients. SBP and DBP statistically significantly decreased during 5 years follow up (mainly during year 1), but the difference in mm Hg was small. Estimates from GEE analysis showed that patients with high DAS >2.4 (HDAS) had a statistically significantly higher SBP (average 3 mm Hg higher, 95% CI 1.7; 4.2, p < 0.01), than the patients in with DAS ≤2.4. ANOVA analyses showed a statistically significant association between SBP and DAS. In addition, post hoc analyses showed that patients with HDAS had a statistically significantly higher  SBP (mean (SD) 132 (19) than the patients with DAS < 1.6 (remission) (mean (SD) 129 (20), p < 0.01), and patients in LDAS but DAS≥1.6 had a statistically significantly higher SBP (mean (SD) 131 (19) than the patients in remission (mean (SD)  129 (20), p = 0.02) (Figure 1), whereas no association was found between DAS category and DBP. Gender, ACPA status or fulfilling the 2010 classification criteria did not influence the relation between DAS and blood pressure. Conclusions: In patients with RA or UA, a higher DAS is associated with higher blood pressure, but the clinical impact is unclear. Abstract Figure 1

scholarly journals Characteristics of anteroposterior curvatures of the spine in soccer and futsal players

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Krystyna Chromik ◽  
Anna Burdukiewicz ◽  
Jadwiga Pietraszewska ◽  
Aleksandra Stachoń ◽  
Paweł Wolański ◽  
...  
Keyword(s):  
College Students ◽  
Statistical Analysis ◽  
Injury Prevention ◽  
Analysis Of Variance ◽  
Statistical Significance ◽  
Body Posture ◽  
Soccer Players ◽  
Prevention Training ◽  
The Difference ◽  
Post Hoc

AbstractPurpose. The aim of the study was to determine differences in anteroposterior spine curvatures between futsal players, soccer players, and non-training students. The results may contribute to the development of present-day knowledge of posturometry, and its implementation in training can help reduce the risk of body posture disorders in athletes. Methods. The examined group consisted of 48 athletes and 38 non-training college students. Body posture parameters were measured with the use of Posturometr-S. The normality of distribution was checked with the Shapiro-Wilk test, and the differences between the groups were measured with ANOVA and the Bonferroni post-hoc test. The level of statistical significance was set at p < 0.05. Results. The analysis of angle values revealed the widest and most similar measurements in the group of futsal players and soccer players. The analysis of variance proved statistically significant differences between the soccer players and futsal players (p = 0.003). The difference between the soccer players and non-training students was statistically significant. The highest γ angular value was measured in non-training students, followed by futsal players and soccer players. The statistical analysis revealed significant differences between the non-training students and futsal players, as well as non-training students and soccer players (p < 0.001). Conclusions. A complex assessment of athletes’ body posture is crucial in injury prevention. Training overloads may often lead to disorders of the organ of locomotion and affect the correct body posture in athletes. This, in turn, may result in pains and injuries.

Physical properties of biaxially oriented PA6 film for simultaneous stretching and sequential processing

2011 ◽  
Vol 31 (1) ◽  
Author(s):  
Masao Takashige ◽  
Toshitaka Kanai
Keyword(s):  
Impact Strength ◽  
Physical Properties ◽  
Physical Property ◽  
High Impact ◽  
Thermal Shrinkage ◽  
Double Bubble ◽  
Biaxial Stretching ◽  
High Impact Strength ◽  
The Difference ◽  
Stretching Process

Abstract There are two different stretching processes that produce the biaxially oriented film, namely the tenter process and double bubble tubular film process. Furthermore, there are two tenter processes, i.e., the sequential biaxial stretching process and simultaneous biaxial stretching process. There is no report describing the difference among film physical properties of the three different processes. The biaxially oriented polyamide film using the double bubble tubular process has good balanced physical property and high impact strength, thus it is used for proper applications utilizing their advantage properties. In this report, the influence of each biaxial stretching process on film physical properties of polyamide, which has hydrogen bond, was studied in detail. As a result, the tentering process film has anisotropic tensile properties between machine direction (MD) and transverse direction (TD). This result was influenced by a later stretching process, namely TD stretching. On the contrary, the double bubble tubular film has good balanced properties, especially thermal shrinkage and impact strength. Tentering simultaneous stretching film has much larger shrinkage in MD than in TD. The sequential stretching film has larger shrinkage in TD than in MD. The double bubble tubular film has high impact strength, because it corresponds to the balanced molecular orientation.

scholarly journals A study into the structure and physical properties of the Cr18Ni9-grade steel following long-term irradiation as part of the BN-600 reactor internals

2020 ◽  
Vol 6 (1) ◽  
pp. 1-6
Author(s):  
Irina A. Portnykh ◽  
Aleksandr V. Kozlov ◽  
Valery L. Panchenko ◽  
Vyacheslav S. Shikhalev
Keyword(s):  
Physical Properties ◽  
Young’S Modulus ◽  
Structural Changes ◽  
Young's Modulus ◽  
Void Size ◽  
Initial State ◽  
Porosity Distribution ◽  
Grade Steel ◽  
Reactor Internals

The microstructures and physical properties of the austenitic Cr18Ni9-grade steel after 22 and 33 years of operation as part of the reactor internals were tested for assessing the conditions of the BN-600 reactor non-replaceable components (internals) and the potential of their subsequent use in predicting the reactor ultimate life. The paper presents histograms of the porosity distribution depending on the void size, in samples taken from portions that were subjected to neutron irradiation with displacement rates ranging from 1.0×10–9 to 4.3×10–8 dpa/s at temperatures from 370 to 440 °C. The elasticity characteristics were measured by resonance-type ultrasonic technique for the samples taken from the same portions of material. It was demonstrated that swelling calculated using the histograms of the porosity distribution depending on the void size has the maximum value at ~415 °C and after 33 years of irradiation reaches values of ~3%. Long-term variations of Young’s modulus demonstrate non-monotonous dependence on the damage dose. The maximum relative variation of Young’s modulus after 22 and 33 years of operation does not exceed 2% and 6%, respectively, of the values corresponding to the initial state. It was shown that along with the irradiation-induced swelling the changes in the physical properties are also affected in the process of irradiation by other structural changes and, in particular, by the formation of secondary phases. As shown by the results of the studies, operation of the BN-600 reactor internals made of Cr18Ni9-grade steel can be extended beyond 33 years of service. The comparison of the results obtained for the material after 22 and 33 years of operation contains information required for describing subsequent changes of the structure and properties of the Cr18Ni9 internals. The obtained results can be used for forecasting the reactor ultimate life within the framework of existing and developed models.

scholarly journals Kekasaran Permukaan Resin Komposit Nanofilled dan Nanohybrid Setelah Paparan Asap Rokok Kretek

2019 ◽  
Vol 8 (1) ◽  
pp. 30
Author(s):  
Johanna Chandra ◽  
Laksmiari Setyowati ◽  
Setyabudi Setyabudi
Keyword(s):  
Surface Roughness ◽  
Physical Properties ◽  
Cigarette Smoke ◽  
Public Health Problem ◽  
Composite Resins ◽  
Dental Composites ◽  
Distilled Water ◽  
Control Groups ◽  
The Past ◽  
Nanohybrid Composite

Background: Cigarette smoking is a public health problem that may influence physical properties of dental composites. Surface roughness is one of the physical properties of restorative materials that can influence their success. The use of nanofilled and nanohybrid composites in dentistry has substantially increased over the past few years. Purpose: The purpose of this study was to evaluate the surface roughness of nanofilled and nanohybrid composite resins exposed to kretek cigarette smoke. Methods: Twelve cylindrical specimens were prepared of each material and divided into two groups (n=6). For the control groups, the specimens were immersed in distilled water for 24 hours at 37oC and the water was renewed daily. For the experimental groups, the specimens were exposed daily to kretek cigarette smoke, then washed and stored in distilled water at 37oC. After 21 days, specimens were measured using a Surface Roughness Tester and the data was statistically analyzed. Result: Independent-T Test revealed that there were statistically significant differences in the surface roughness between control and experimental groups both nanofilled and nanohybrid, and between experimental groups nanofilled and nanohybrid. Conclusion: The exposure to kretek cigarette smoke can significantly increase the surface roughness of nanohybrid composites more than nanofilled composites.

scholarly journals Study of Mechanical and Physical Properties of Natural Hybrid Composites

2019 ◽  
Vol 7 (6) ◽  
pp. 240-244
Author(s):  
I. K. Adi Atmika ◽  
I. D. G. Ary Subagia ◽  
I. W. Surata ◽  
I. N. Sutantra
Keyword(s):  
Physical Properties ◽  
Hybrid Composites ◽  
Natural Hybrid ◽  
Mechanical And Physical Properties

scholarly journals Serum Interleukin-2 (IL-2) Levels in Untreated and Treated in Batak Tribe Patients with Schizophrenia

2021 ◽  
Vol 4 (1) ◽  
pp. 1449-1460
Author(s):  
Julius Martin Siagian ◽  
Elmeida Effendy ◽  
Mustafa M. Amin
Keyword(s):  
General Hospital ◽  
Pearson Correlation ◽  
Interleukin 2 ◽  
Cross Sectional ◽  
Welch Test ◽  
Pearson Correlation Test ◽  
Healthy Control ◽  
The Difference ◽  
Post Hoc ◽  
One Way Anova

To find out the difference of serum IL-2 levels between untreated and treated in the Batak tribe patients with schizophrenia and healthy control and also to find out the association between serum IL-2 levels with PANSS score in the Batak tribe patients with schizophrenia. This study was cross-sectional approach using a one-way ANOVA welch test and to find a correlation between serum IL-2 levels with PANSS score in the Batak tribe patients with schizophrenia which is conducted in Prof. Dr. M. Ildrem Psychiatric Hospital Medan and Dr. Pirngadi General Hospital Medan from September 2019-November 2019. Subjects of untreated were 55 subjects and treated in the Batak tribe patients with schizophrenia were 55 subjects and healthy control were 55 subjects. There were significant differences between these three groups using post hoc Games-Howell test on the value of p<0.001 and also been found there was a significant correlation between serum IL-2 levels with PANSS score in the Batak tribe patients with schizophrenia using the Pearson correlation test (r=0.599, p=0.001 and r=0.501, p=0.001). It was founded that there were significant differences between serum IL-2 levels in three groups and also founded there was a significant correlation between serum IL-2 levels with PANSS score in the Batak tribe patients with schizophrenia. 

scholarly journals Summertime canopy albedo is sensitive to forest thinning

2013 ◽  
Vol 10 (9) ◽  
pp. 15373-15414 ◽  
Author(s):  
J. Otto ◽  
D. Berveiller ◽  
F.-M. Bréon ◽  
N. Delpierre ◽  
G. Geppert ◽  
...  
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Structural Changes ◽  
Near Infrared ◽  
Canopy Structure ◽  
Model Parameters ◽  
Transfer Model ◽  
Forest Thinning ◽  
Crown Volume ◽  
The Difference

Abstract. Despite an emerging body of literature linking canopy albedo to forest management, understanding of the process is still fragmented. We combined a stand-level forest gap model with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning, that is removing trees at a certain time during the forest rotation, on summertime canopy albedo. The effects of different forest species (pine, beech, oak) and four thinning strategies (light to intense thinning regimes) were examined. During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning on summertime canopy albedo. These trends continue until the end of the rotation where thinning explains up to 50% of the variance in near-infrared canopy albedo and up to 70% of the variance in visible canopy albedo. More intense thinning lowers the summertime shortwave albedo in the canopy by as much as 0.02 compared to unthinned forest. The structural changes associated with forest thinning can be described by the change in LAI in combination with crown volume. However, forests with identical canopy structure can have different summertime albedo values due to their location: the further north a forest is situated, the more the solar zenith angle increases and thus the higher is the summertime canopy albedo, independent of the wavelength. Despite the increase of absolute summertime canopy albedo values with latitude, the difference in canopy albedo between managed and unmanaged forest decreases with increasing latitude. Forest management thus strongly altered summertime forest albedo.

scholarly journals Physical Properties and Non-Isothermal Crystallisation Kinetics of Primary Mechanically Recycled Poly(l-lactic acid) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3396
Author(s):  
Luboš Běhálek ◽  
Jan Novák ◽  
Pavel Brdlík ◽  
Martin Borůvka ◽  
Jiří Habr ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Physical Properties ◽  
Structural Changes ◽  
The Other ◽  
Half Time ◽  
Crystallisation Kinetics ◽  
Isothermal Crystallisation ◽  
Melt Crystallisation ◽  
Kinetics Of ◽  
Crystallisation Rate

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

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