scholarly journals Stability of external and internal implant connections after a fatigue test

2013 ◽  
Vol 07 (03) ◽  
pp. 267-271 ◽  
Author(s):  
Paulo Cesar Pinheiro Feitosa ◽  
Ana Paula Barbosa de Lima ◽  
Laís Regiane Silva-Concílio ◽  
William Cunha Brandt ◽  
Ana Christina Claro Neves
Keyword(s):  
Mechanical Testing ◽  
Fatigue Test ◽  
Analysis Of Variance ◽  
Mechanical Cycling ◽  
Before And After ◽  
Lower Variation

ABSTRACT Objective: The objective of this study was to compare the torque and detorque values of screw intermediates of external hexagon, internal hexagon, and Morse taper implants in single restorations before and after mechanical cycling. Materials and Methods: The study sample was divided into three groups (n = 10) as follows: group EH - external hexagon implant, group IH - internal hexagon implant, and group MT - Morse taper implant. Universal abutments were screwed on the implants, and metal crowns were cemented onto the abutment. The samples were submitted to a mechanical testing of 1 million cycles, with a frequency of 8 cycles per second under a 400 N load. The application and registration of the screw torque (T0) and detorque (T1) values of the intermediate were performed before and after the test. The results were statistically evaluated by analysis of variance (ANOVA) and Tukey′s test (α = 0.05). Results: There was no difference between the values of T0 and T1 in the intra-group samples. However, the inter-group difference in T0 between the EH (12.8 N cm) and MT (18.6 N cm) groups and in T1 between the EH (10.4 N cm) and IH (13.8 N cm), EH and MT (19.4 N cm), and MT and IH (P = 0.001) groups were significant. The MT group showed a lower variation of T0 and T1. Conclusion: The internal implants, particularly MT, showed better stability in these cases when used for single restorations.

scholarly journals Awareness of basic life support among Saudi dental students and interns

2017 ◽  
Vol 11 (04) ◽  
pp. 521-525 ◽  
Author(s):  
Hashem Motahir Al-Shamiri ◽  
Sadeq Ali Al-Maweri ◽  
Bassam Shugaa-Addin ◽  
Nader Ahmed Alaizari ◽  
Abdulrahman Hunaish
Keyword(s):  
Mechanical Testing ◽  
Analysis Of Variance ◽  
Basic Life Support ◽  
Life Support ◽  
Dental Students ◽  
Mechanical Cycling ◽  
Before And After ◽  
Lower Variation

ABSTRACT Objective: The objective of this study was to compare the torque and detorque values of screw intermediates of external hexagon, internal hexagon, and Morse taper implants in single restorations before and after mechanical cycling. Materials and Methods: The study sample was divided into three groups (n = 10) as follows: group EH - external hexagon implant, group IH - internal hexagon implant, and group MT - Morse taper implant. Universal abutments were screwed on the implants, and metal crowns were cemented onto the abutment. The samples were submitted to a mechanical testing of 1 million cycles, with a frequency of 8 cycles per second under a 400 N load. The application and registration of the screw torque (T0) and detorque (T1) values of the intermediate were performed before and after the test. The results were statistically evaluated by analysis of variance (ANOVA) and Tukey′s test (α = 0.05). Results: There was no difference between the values of T0 and T1 in the intra-group samples. However, the inter-group difference in T0 between the EH (12.8 N cm) and MT (18.6 N cm) groups and in T1 between the EH (10.4 N cm) and IH (13.8 N cm), EH and MT (19.4 N cm), and MT and IH (P = 0.001) groups were significant. The MT group showed a lower variation of T0 and T1. Conclusion: The internal implants, particularly MT, showed better stability in these cases when used for single restorations.

SEM Validation Technique for FEA of Small Specimens

2007 ◽  
Author(s):  
Kelly Pike ◽  
Z. C. Lin ◽  
Alan Tahran
Keyword(s):  
Fatigue Test ◽  
Before And After ◽  
Surface Measurements ◽  
Small Test ◽  
Individual Specimen ◽  
Validation Technique

The use of the SEM to make direct surface measurements on small test specimens enables the FEA analyst to construct and validate an individual specimen model. The technique is also valuable to engineers so that they can calibrate their fatigue test samples before and after fatigue test regimes.

Application of the CLSI EP15-A3 Guideline as an Alternative Troubleshooting Tool for Verification of Assay Precision

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S88-S88
Author(s):  
Jose Jara Aguirre ◽  
Karl Ness ◽  
Alicia Algeciras-Schimnich
Keyword(s):  
Quality Control ◽  
Carcinoembryonic Antigen ◽  
Laboratory Investigation ◽  
Analysis Of Variance ◽  
Experimental Approach ◽  
Biological Variation ◽  
Analytical Performance ◽  
Microsoft Excel ◽  
Before And After ◽  
Assay Precision

Abstract Introduction The CLSI EP15-A3 guideline “User Verification of Precision and Estimation of Bias” provides a simple experimental approach to estimate a method’s imprecision and bias. The objective is to determine if the laboratory precision performance of repeatability (SR) and within-laboratory imprecision (SWL) are in accordance to the manufacturer specification claims (MSCs). Objectives Evaluate the utility of the EP15-A3 protocol to verify method precision during a troubleshooting investigation and after major instrument maintenance, using a carcinoembryonic antigen (CEA) immunoassay as an example. Methods CEA was performed on the Beckman Coulter DxI (Beckman Coulter, Brea, CA). Quality control (QC) levels (L1: 2.89; L2: 21.10; L3: 39.10 ng/mL) (Bio-Rad Laboratories, Irvine, CA) were used. Each QC level was measured before and after instrument maintenance as follows: five replicates per run, one run per day, and during 5 days. Imprecision estimates (IEs) for SR (%CVR) and SWL (%CVWL) were calculated by one-way analysis of variance using Microsoft Excel Analyse-it software. Estimated imprecision was compared to MSC and desirable imprecision specifications based on biological variation (BV). Results A change in the analytical performance of CEA was detected by a decreased sigma-metric indicator. After a bias problem was ruled out, the observed %CVR for L1, L2, and L3 were 7.2%, 3.7%, and 4.8%, respectively. The %CVWL were 8.3%, 5.0%, and 5.5%, which exceeded the MSC of %CVWL~4.0% to 4.5%. After a laboratory investigation, major instrument maintenance was performed by the manufacturer. The %CVR and %CVWL estimates for L1, L2, and L3 after maintenance were 3.2%, 3.8%, 3.5% and 3.9%, 4.2%, 4.0%, respectively. After maintenance, the CEA performance was consistent with the MSC for each of the levels analyzed and within the BV impression goal of %CV ≤6.4. Conclusion CLSI EP15-A3 guideline is an alternative troubleshooting tool that can be used to investigate and verify method precision performance before and after significant instrument maintenance.

scholarly journals Influence of Different Pigmentations and Accelerated Aging on the Hardness and Tear Strength of the A-2186 and MDX4-4210 Silicones

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Estefânia Marrega Malavazi ◽  
Daniela Micheline dos Santos ◽  
Clóvis Lamartine de Moraes Melo Neto ◽  
Fernanda Pereira de Caxias ◽  
Emily Vivianne Freitas da Silva ◽  
...  
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Accelerated Aging ◽  
Hardness Test ◽  
Strength Test ◽  
Tear Strength ◽  
Tukey Test ◽  
Repeated Measures Analysis ◽  
Before And After ◽  
Hardness Values

Objective. To evaluate the influence of different pigmentations and accelerated aging on the hardness and tear strength of the A-2186 and MDX4-4210 silicones. Materials and Methods. The samples A-2186 and MDX4-4210 were manufactured without and with pigmentations (black, bronze, and pink). For the Shore A hardness test, 80 samples of each silicone were fabricated, and for the tear strength test, 320 samples of each silicone were fabricated. Eight groups were created for each test (n = 10). These tests were performed before and after 252, 504, and 1008 hours of aging. Three-way repeated-measures analysis of variance and the Tukey test were performed (α = 0.05). Results. The A-2186 silicone showed higher hardness and tear strength when compared with the MDX4-4210 silicone p<0.05, except in the hardness of the A-2186 and MDX4-4210 groups without pigmentation after 1008 hours p>0.05. All hardness values were between 25 and 35 units, regardless of the silicone type, period, and pigmentation (or no pigmentation). In most situations, the hardness of silicones used increased after 252 hours p<0.05. The nonpigmented MDX4-4210 group and all A-2186 groups showed an increase in tear strength after 252 hours p<0.05. For the nonpigmented MDX4-4210 group, from 252 to 1008 hours, there was no change in tear strength p>0.05. All pigmented MDX4-4210 groups showed no change in tear strength from 0 (initial) to 1008 hours of aging p>0.05. In all A-2186 groups, from 252 to 504 hours, there was a reduction in tear strength p<0.05, and from 504 to 1008 hours, there was an increase in tear strength p<0.05, except in the bronze A-2186 group p>0.05. Conclusion. In most situations, the A-2186 silicone showed significantly higher values of hardness and tear strength than the MDX4-4210 silicone. All hardness values were considered clinically acceptable. Accelerated aging could increase, decrease, or not significantly change the hardness and tear strength of the silicones used. The results of hardness and tear strength suggest that MDX4-4210 was more influenced by the presence of pigmentation after aging.

scholarly journals Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

2017 ◽  
Vol 13 ◽  
pp. 372-383 ◽  
Author(s):  
Maximilian Maier ◽  
Magnus S Schmidt ◽  
Markus Ringwald ◽  
Christoph P Fik
Keyword(s):  
Refractive Index ◽  
Mechanical Testing ◽  
Functional Groups ◽  
Nmr Spectra ◽  
Dsc Measurements ◽  
Alkyl Groups ◽  
Before And After ◽  
Reactive Liquid ◽  
Synergistic Combination ◽  
C Nmr

Six polymerizable N,N’-diacylamides containing spatially arranged N-acryl, N-allyl and/or N-alkyl groups were prepared via two-step syntheses and characterized by 1H/13C NMR-spectra, refractive index (RI) and viscosity measurements. Photo DSC measurements on activated samples provided reactivity parameters ∆H p, R p,max and t max, while FTIR spectra before and after curing elucidated the underlying polymerization mechanism. Mechanical testing of the obtained polymers exhibited gradual differences in network densities, depending on the intramolecular arrangement and number of functional groups. Overall, a general building principle for highly reactive, liquid diacrylamides via synergistic combination of optimally arranged functional groups could be identified. The highest possible level of intramolecular synergism was found for low viscous N,N'-diacryloyl-N,N'-diallyl-1,4-but-2-enediamine.

Sour Resistant High Strength Seamless Pipes for Risers

2013 ◽  
Author(s):  
Matteo Ortolani ◽  
Ettore Anelli ◽  
Paolo Novelli ◽  
Emanuele Paravicini Bagliani
Keyword(s):  
Heat Treatment ◽  
Mechanical Testing ◽  
High Strength ◽  
Post Weld Heat Treatment ◽  
Water Quenching ◽  
Potential Solution ◽  
Steel Pipes ◽  
Before And After ◽  
Hot Rolled ◽  
Sour Service

In case of a Weld On Connector’s riser using ASTM A182 F22 forged joints, high strength (SMYS of 80 ksi) steel pipes for sour service (hardness below or equal to 250 HV10) suitable for welding to the connectors are required. Welding is challenging because of the Post Weld Heat Treatment (PWHT) needed to reduce the hardness in the F22 HAZ while maintaining the required strength in the pipe. Theoretical evaluations were performed by means of metallurgical models and a potential solution was identified in grade P22-like steel (2¼ Cr - 1 Mo), with minor modifications with respect to the standard ASTM A335 and supplied in Q&T condition. A trial heat was cast and hot-rolled into pipes. After water quenching, the response to tempering was assessed by means of laboratory heat treatments and subsequent mechanical testing, together with metallurgical examination. Simulated PWHTs were also performed on Q&T material. 80 ksi grade P22 seamless pipes were finally produced and qualification involved mechanical testing before and after simulated PWHT: SMYS of 80 ksi and HV10 ≤ 250 requirements were met. The material also exhibited excellent toughness and resistance to HIC and SSC cracking.

scholarly journals Effects of Laundering on Seaming Attributes of a Fabric for Public Basic school uniforms

2021 ◽  
pp. 90-96
Author(s):  
Patience Danquah Monnie ◽  
Docea Fianu ◽  
Efua Vandyck ◽  
Cynthia Gadegbeku
Keyword(s):  
Analysis Of Variance ◽  
School Uniforms ◽  
Hypotheses Testing ◽  
Sewing Thread ◽  
Stitch Density ◽  
Alpha Level ◽  
Before And After ◽  
Basic School

Quality seams have great impact on the quality of garments. The study evaluated effect of laundering on plain seam in a suitable fabric for Ghanaian public basic school uniforms by varying sewing thread and stitch density to establish suitable ones for the achievement of quality in school uniforms. A total number of 290 specimens were used. Washed specimens were subjected to three cycles of washing using Launder-Ometer (Gyrowash 315) and seam strength, efficiency and elongation were evaluated. Means of the attributes were determined and analysis of variance at 0.05 alpha level are used for hypotheses testing. Sewing thread brand B in 14 stitches per inch (spi) provided greater seam strength, efficiency and elongation before and after washing.

scholarly journals The effects of the trefoil pedagogical approach on encouraging creative behaviour in students

2016 ◽  
Vol 48 (2) ◽  
pp. 207-230
Author(s):  
Jasmina Sefer ◽  
Snezana Mirkov
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Research Work ◽  
Extensive Study ◽  
Pedagogical Approach ◽  
Positive Effects ◽  
School Year ◽  
Before And After ◽  
Teachers And Students ◽  
Student Questionnaire

?his paper presents a portion of the results obtained in a more extensive study dealing with monitoring of the work methods and the effects of an experimental implementation of the Trefoil pedagogical approach, developed based on pedagogical theories by the researchers from Belgrade. The Trefoil is based on using group work, creative play, openended tasks, critical dialogue, research work and students? involvement in projects for which teachers were trained through implementation and reflexive practice. The aim of this longitudinal study is to determine the effects of the Trefoil on encouraging initiative, cooperation and creativity in students. Research participants were all teachers and students of an urban primary school during one school year. Data on students? creative work were collected and compared before and after the experiment, obtained by expert observation of classes and a teacher and student questionnaire. Data were processed using one-way analysis of variance for repeated measures and two-way mixed analysis of variance. The results pointed to positive effects of the Trefoil approach, which, according to qualitative data, could probably have been bigger if the experiment had lasted longer. Different assessors noticed progress in encouraging students? creativity, but in different domains. The results have confirmed the justifiability of using the Trefoil approach, provided that its validity is tested by implementation in other educational contexts for the purposes of further research and enhancement of the initial conception.

scholarly journals Application of multivariate analysis of vari-ance (MANOVA) to distance refractive vari-ability and mean distance refractive state

2006 ◽  
Vol 65 (2) ◽  
Author(s):  
S Abelman
Keyword(s):  
Multivariate Analysis ◽  
Analysis Of Variance ◽  
Refractive State ◽  
Experimental Trial ◽  
Level Of Confidence ◽  
Significant Difference ◽  
Sample Data ◽  
Before And After ◽  
Multiple Measurements

Refractive state can be regarded as a dynam-ic quantity. Multiple measurements of refractive state can be determined easily and rapidly on a number of different occasions using an autore-fractor. In an experimental trial undertaken by Gillan, a 30-year-old female was subjected to 30 autorefractor measurements each taken at vari-ous intervals before and after the instillation of Mydriacyl 1% (tropicamide) into her right eye. The purpose of this paper is to apply multivar-iate analysis of variance (MANOVA) to Gillan’s sample data in order to assess whether instillation of Mydriacyl into the eye affects variability of distance refractive state as well as mean distance refractive state as measured by an autorefractor. In  five  of  the  seven  cases  where  pairwise hypotheses  tests  were  performed,  it  is  con-cluded that at a 99% level of confidence there is no difference in variability of distance refrac-tive state before and after cycloplegia. In two of the three cases where MANOVA was applied, there is a significant difference at a 95% and at a 99% level of confidence in both variability of distance refractive state and mean distance refractive  state  with  and  without  cycloplegia.

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