The Relationship Between Oxide Adherence and Porcelain-Metal Bonding

1988 ◽  
Vol 67 (2) ◽  
pp. 474-478 ◽  
Author(s):  
J.R. Mackert ◽  
R.D. Ringle ◽  
E.E. Parry ◽  
A.L. Evans ◽  
C.W. Fairhurst

The lack of a reliable bond test has hindered the elucidation of the mechanism for porcelain-metal bonding in dental systems, because a test capable of detecting differences among porcelain-metal bonds of various qualities is required before the reasons for these differences may be ascertained. A method was developed in the present study whereby specimens of alloys with differing physical properties may be deformed to a constant strain to yield a fracture surface suitable for measurement of the area fraction of retained porcelain by an x-ray spectrometric technique described previously. The method proved sufficiently discriminating that significant differences could be found in 48 of the possible 66 comparisons among alloys and treatments. Linear regression analysis revealed a strong correlation (r 2 = 0.947) between the area fractions of retained porcelain measured in the present study and the oxide adherence strength values measured previously. This strong correlation, when considered in light of the literature evidence for the presence of an oxide layer at the porcelain-metal interface, provides compelling support for the oxide layer theory of porcelain-metal bonding in dental alloy systems.

2020 ◽  
Vol 27 (4) ◽  
pp. 303-312 ◽  
Author(s):  
Ruifang Li ◽  
Hong Li ◽  
Sarula Yang ◽  
Xue Feng

Background: It is currently believed that protein folding rates are influenced by protein structure, environment and temperature, amino acid sequence and so on. We have been working for long to determine whether and in what ways mRNA affects the protein folding rate. A large number of palindromes aroused our attention in our previous research. Whether these palindromes do have important influences on protein folding rates and what’s the mechanism? Very few related studies are focused on these problems. Objective: In this article, our motivation is to find out if palindromes have important influences on protein folding rates and what’s the mechanism. Method: In this article, the parameters of the palindromes were defined and calculated, the linear regression analysis between the values of each parameter and the experimental protein folding rates were done. Furthermore, to compare the results of different kinds of proteins, proteins were classified into the two-state proteins and the multi-state proteins. For the two kinds of proteins, the above linear regression analysis were performed respectively. Results : Protein folding rates were negatively correlated to the palindrome frequencies for all proteins. An extremely significant negative linear correlation appeared in the relationship between palindrome densities and protein folding rates. And the repeatedly used bases by different palindromes simultaneously have an important effect on the relationship between palindrome density and protein folding rate. Conclusion: The palindromes have important influences on protein folding rates, and the repeatedly used bases in different palindromes simultaneously play a key role in influencing the protein folding rates.


2021 ◽  
Vol 13 (6) ◽  
pp. 3584
Author(s):  
Shiwang Yu ◽  
Jianxia Bao ◽  
Wen Ding ◽  
Xue Chen ◽  
Xiaonan Tang ◽  
...  

During China’s rapid economic development and urbanization, numerous cases of urban malodorous black river (MBR) have occurred. MBR refers to a polluted urban river that smells bad, is almost black in color, has no aquatic plants or animals, and that consequently causes many social and environmental problems. The Chinese government has sought public participation during the whole process of MBR treatment as part of a comprehensive action plan to improve residents’ satisfaction with their environment. To investigate the influencing factors of public participation and satisfaction, a questionnaire survey was conducted among residential communities close to an MBR. SPSS 22.0 was employed to conduct an analysis of the collected data, using factor analysis, correlation analysis, and linear regression analysis. The results indicate that there is a direct relationship between public satisfaction and the factors of government treatment, public perception and public participation behaviors, such as engagement behavior, supervision behavior, health influence, and compensation measures.


2021 ◽  
pp. 002076402199351
Author(s):  
Emmanouil K Symvoulakis ◽  
Manolis Linardakis ◽  
Apostolos Kamekis ◽  
Myfanwy Morgan ◽  
Spyridon Klinis

Purpose: An individual’s lack of social connections and social isolation is often associated with feelings of loneliness which is regarded as having a negative effect on health. This paper describes the development and assessment of a 10 item ‘Personal Sociability and Connections Scale’ (PeSCS) to measure individual’s disposition and accompanying skills to seek out companionship and engage in interpersonal relations. Methods: The study was conducted at a rural primary care unit in Northern Greece. A total of 199 attenders were recruited over a 6-week period in 2020 and questionnaires completed. This informed the 10-items PeSCS that comprises Social, Behavioral, and Emotional components focusing on the expression of social comfort, willingness to share experiences, stories and concepts, and feelings of similarity at first contact. Reliability of the PeSC scale was assessed and the relationship with scale scores examined as an indicator of convergent validity. A multivariate linear regression analysis was performed to examine the relationship of PeSC scale score with the characteristics of participants. Results: Assessment of reliability of PeSC scale produced a Cronbach’s alpha of 0.809. The relationship between components and the total PeSCS scores identified significant correlations ( p < .001). At a multivariate level, male gender was the sample characteristic with a significant association with scale levels ( p < .05) and higher annual income with Social component ( p < .05). Otherwise the distribution of sociability dispositions was similar across population groups. Conclusion: The 10-item PeSC scale forms a simple and quick to complete measure whose overall reliability was rated as ‘meritorious’. The PeSC instrument may be a useful tool for assessing the causes and appropriate responses to the negative health effects of loneliness and social isolation.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Meng ◽  
Yunping Zhou ◽  
Yunxia Jiang

AbstractObjectivesThe results of existing studies on bisphenol A (BPA) and puberty timing did not reach a consensus. Thereby we performed this meta-analytic study to explore the association between BPA exposure in urine and puberty timing.MethodsMeta-analysis of the pooled odds ratios (OR), prevalence ratios (PR) or hazards ratios (HR) with 95% confidence intervals (CI) were calculated and estimated using fixed-effects or random-effects models based on between-study heterogeneity.ResultsA total of 10 studies involving 5621 subjects were finally included. The meta-analysis showed that BPA exposure was weakly associated with thelarche (PR: 0.96, 95% CI: 0.93–0.99), while no association was found between BPA exposure and menarche (HR: 0.99, 95% CI: 0.89–1.12; OR: 1.02, 95% CI: 0.73–1.43), and pubarche (OR: 1.00, 95% CI: 0.79–1.26; PR: 1.00, 95% CI: 0.95–1.05).ConclusionsThere was no strong correlation between BPA exposure and puberty timing. Further studies with large sample sizes are needed to verify the relationship between BPA and puberty timing.


2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
C Delgado ◽  
M Delgado-Lelievre ◽  
D Lelievre ◽  
A Delgado-Almeida

Abstract Introduction The sodium voltage-gated channel alpha subunit 7 (SCN7A) has been associated to renal Na regulation and hypertension. This study explores the relationship between blood pressure (BP) and urinary overnight Na/K ratio (UONaK) in hypertensives (HT) and normotensive (NT) subjects from from National Heart, Lung and Blood Institute funded, Family Blood Pressure Program (FBPP) that were genotyped for 3 SNPs for SCN7A: CV2161217, CV 356958 and CV433036. Hypothesis Genetic variations in the SCNA7 are differently associated to BP and UONaK in HT and NT. Methods 1,749 subjects genotyped for SCN7A SNPs CV2161217, CV 356958 and CV433036 were analyzed from FBPP. Subjects with diastolic BP (DBP) ≥80 or systolic BP (SBP) ≥130 mmHg were classified HTN; subjects with SBP &lt;130 and DBP &lt;80 mmHg were classified as NT. UONAK was calculated by dividing overnight Na by K concentration. Correlation analysis done with partial variables (use of antihypertensive drug, use of diuretics, overnight urine creatinine). Results For the CV2161217, HTN group (n=1,030), 52% had C/C, 39% C/T and 9% T/T. In NT group (n=719), 52% had C/C, 38% C/T and 10% T/T. In the HT group, subjects with CC genotype showed strong correlation between DBP and UONaK (Fig 1a) while no significant correlation with SBP. Those with CT genotype maintained the correlation between SBP and UONaK (r=0.10, p=0.03) with no correlation with SBP. The TT showed no correlation between UONaK and SBP or DBP. In the NT, subjects with TT genotype showed strong correlation between DBP and UONaK (Fig 1b) and with SB (r=0.256, p=0.03). Those with CT or TT genotypes showed no correlation between UONaK and SBP or DBP. Similar finding were obtained for CV356958 SNP; no similar association was observed in the CV433036 SNP. Conclusions Subjects with the genetic variations in the SCNA7, such as CV2161217 and CV 356958 SNPs, showed significant correlation between blood pressure and overnight urinary sodium potassium. This finding could have important implications in non dipping status observed in some hypertensive patients. Funding Acknowledgement Type of funding source: None


Cardiology ◽  
2021 ◽  
pp. 1-6
Author(s):  
John Michael Cochran ◽  
Vincent R. Siebert ◽  
Jeffrey Bates ◽  
Djenita Butulija ◽  
Anna Kolpakchi ◽  
...  

Background: Identification and modification of cardiovascular risk factors is paramount to reducing cardiovascular disease morbidity and mortality. Hypertension is a major risk factor for cardiovascular disease, but its association with height remains largely underrecognized. Objectives: The objective of this manuscript is to review the evidence examining the association between blood pressure and human stature and to summarize the plausible pathophysiological mechanisms behind such an association. Methods: A systematic review of adult human height and its association with hypertension and coronary artery disease was undertaken. The literature evidence is summarized and tabulated, and an overview of the pathophysiological basis for this association is presented. Results: Shorter arterial lengths found in shorter individuals may predispose to hypertension in a complex hemodynamic interplay, which is explained predominantly by summated arterial wave reflections and an elevated augmentation index. Our systemic review suggests that an inverse relationship between adult height and blood pressure exists. However, differences in the studied populations and heterogeneity in the methods applied across the various studies limit the generalizability of these findings and their clinical application. Conclusion: Physiological studies and epidemiological data suggest a potential inverse association between adult height and blood pressure. Further research is required to define the relationship more clearly between adult height and blood pressure and to assess whether antihypertensive therapeutic approaches and goals should be modified according to patients’ heights.


2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1740.1-1740
Author(s):  
J. H. Kang ◽  
S. E. Choi ◽  
H. Xu ◽  
D. J. Park ◽  
S. S. Lee

Background:Several studies have evaluated the association between serum adiponectin levels and knee and hand osteoarthritis (OA), with mixed results.Objectives:The aim of this study was to investigate the relationship between OA and serum adiponectin levels according to the radiographic features of knee and hand OA.Methods:A total of 2,402 subjects were recruited from the Dong-gu Study. Baseline characteristics were collected via a questionnaire, and X-rays of knee and hand joints were scored by a semi-quantitative grading system. The relationship between serum adiponectin levels and radiographic severity was evaluated by linear regression analysis.Results:Subjects with higher tertiles of serum adiponectin were older and had a lower body mass index than those with lower tertiles. In the knee joint scores, serum adiponectin levels were positively associated with the total score (P<0.001), osteophyte score (P=0.003), and joint space narrowing (JSN) score (P<0.001) among the three tertiles after adjustment for age, sex, body mass index, smoking, alcohol consumption, education, and physical activity. In the hand joint scores, no association was found between serum adiponectin levels and the total score, osteophyte score, JSN score, subchondral cyst score, sclerosis score, erosion score, and malalignment score among the three tertiles after adjustment.Conclusion:In this study, we found that increased adiponectin levels were associated with higher radiographic scores in the knee joint, but not in the hand joint, suggesting different pathophysiologic mechanisms in the development of OA.Disclosure of Interests:None declared


Author(s):  
Brian D. Lowe

Psychophysical approaches to quantifying perceived effort have been used to evaluate the physical demand of many industrial work activities. An experiment was conducted to examine the relationship between ratings of whole-body perceived exertion and differentiated, regional ratings of exertion. The Borg, CR-10 scale was used by 16 subjects performing a simulated repetitive lifting task. Ratings of perceived exertion were obtained for the arms, legs, torso, and central (cardiorespiratory) effort sensations as well as a rating of overall, whole-body exertion. A multiple linear regression analysis was used to predict the whole-body rating of exertion from the differentiated ratings in lifting tasks using both a squat and stoop posture. In the stoop posture condition the coefficient of determination between whole-body perceived exertion and the model including arm, torso, and central ratings was R2=0.81. In the squat posture condition, the final regression model predicting whole-body exertion contained only the rating from the legs (R2 = 0.62). Differentiated ratings explained the majority of the variance in whole-body perceived exertion for squat and stoop lifting tasks.


2021 ◽  
Author(s):  
Paola Mazzoglio ◽  
Ilaria Butera ◽  
Pierluigi Claps

&lt;p&gt;The intensity and the spatial distribution of precipitation depths are known to be highly dependent on relief and geomorphological parameters. Complex environments like mountainous regions are prone to intense and frequent precipitation events, especially if located near the coastline. Although the link between the mean annual rainfall and geomorphological parameters has received substantial attention, few literature studies investigate the relationship between the sub-daily maximum annual rainfall depth and geographical or morphological landscape features.&lt;br&gt;In this study, the mean of the rainfall extremes in Italy, recently revised in the so-called I&lt;sup&gt;2&lt;/sup&gt;-RED dataset, are investigated in their spatial variability in comparison with some landscape and also some broad climatic characteristics. The database includes all sub-daily rainfall extremes recorded in Italy from 1916 until 2019 and this analysis considers their mean values (from 1 to 24 hours) in stations with at least 10 years of records, involving more than 3700 stations.&lt;br&gt;The geo-morpho-climatic factors considered range from latitude, longitude and minimum distance from the coastline on the geographic side, to elevation, slope, openness and obstruction morphological indices, and also include an often-neglected robust climatological information, as the local mean annual rainfall.&lt;br&gt;Obtained results highlight that the relationship between the annual maximum rainfall depths and the hydro-geomorphological parameters is not univocal over the entire Italian territory and over different time intervals. Considering the whole of Italy, the highest correlation is reached between the mean values of the 24-hours records and the mean annual precipitation (correlation coefficient greater than 0.75). This predominance remains also in sub-areas of the Italian territory (i.e., the Alpine region, the Apennines or the coastal areas) but correlation decreases as the time interval decreases, except for the Alpine region (0.73 for the 1-hour maximum). The other geomorphological parameters seem to act in conjunction, making it difficult to evaluate, with a simple linear regression analysis, their impact. As an example, the absolute value of the correlation coefficient between the elevation and the 1-hour extremes is greater than 0.35 for the Italian and the Alpine regions, while for the 24-hours interval it is greater than 0.35 over the coastal areas.&lt;br&gt;To further investigate the spatial variability of the relationship between rainfall and elevation, a spatial linear regression analysis has been undertaken. Local linear relationships have been fitted in circles centered on any of the 0.5-km size pixels in Italy, with 1 to 30 km radius and at least 5 stations included. Results indicate the need of more comprehensive terrain analysis to better understand the causes of local increasing or decreasing relations, poorly described in the available literature.&lt;/p&gt;


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