Concrete sewer pipe corrosion induced by sulphuric acid environment

Corrosion of concrete sewer pipes induced by sulphuric acid attack is a recognised problem worldwide, which is not only an attribute of countries with hot climate conditions as thought before. The significance of this problem is by far only realised when the pipe collapses causing surface flooding and other severe consequences. To change the existing post-reactive attitude of managing companies, easy to use and robust models are required to be developed which currently lack reliable data to be correctly calibrated. This paper focuses on laboratory experiments of establishing concrete pipe corrosion rate by submerging samples in to 0.5 pH sulphuric acid solution for 56 days under 10ºC, 20ºC and 30ºC temperature regimes. The result showed that at very early stage of the corrosion process the samples gained overall mass, at 30ºC the corrosion progressed quicker than for other temperature regimes, however with time the corrosion level for 10ºC and 20ºC regimes tended towards those at 30ºC. Overall, at these conditions the corrosion rates of 10 mm/year, 13,5 mm/year and 17 mm/year were observed

Fasting plasma glucose, or 2-hour post 75-g oral glucose tolerance test, or hemoglobin HbA1c by age group.

<p>Fasting plasma glucose, or 2-hour post 75-g oral glucose tolerance test, or hemoglobin HbA1c by age group.</p

Number/% classification of normal, risk for (prediabetes), and DM2 according to each test type, but OGTT as a reference.

<p>Number/% classification of normal, risk for (prediabetes), and DM2 according to each test type, but OGTT as a reference.</p

Diagnosis of DM2 (N = 259) by fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), oral glucose tolerance test (OGTT), and by combinations of these tests.

<p>Diagnosis of DM2 (N = 259) by fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), oral glucose tolerance test (OGTT), and by combinations of these tests.</p

Characteristics of population.

<p>Mean ± standard deviation, except weight status (%). Differences between boys and girls calculated using Wilcoxon rank-sum test, except for glucose using ANOVA and weight status (χ² test). BMI, body mass index; Weight status, classified according to Barlow <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093150#pone.0093150-Barlow1" target="_blank">[22]</a>; CRF, Cardiorespiratory fitness; PAQ-C score, Physical activity questionnaire; SBP, systolic blood pressure; DBP, diastolic blood pressure; HOMA index, homeostatic model assessment index; HDL, High Density Lipoprotein; TC/cHDL, Total cholesterol/High Density Lipoprotein; CRP, C-Reactive Protein.</p><p>*data missing for 11 participants.</p><p>**data missing for 15 participants.</p

Handgrip strength quartiles and risk of clustered metabolic risk in 8–14 year old children (n = 536).

<p>Quartile 4 is highest handgrip strength category (used as referent). Handgrip quartiles are age and sex specific handgrip/kg body mass unadjusted (grey bars) or adjusted for cardiorespiratory fitness (white bars). Clustered risk is defined as 1 SD above the age and sex specific mean. Panel A: Adjusted for Odds ratios (95% CI) for clustered metabolic risk by HG across quartiles in 8–14 year olds (n = 546) age, sex, and maturation status. Panel B: Additionally adjusted for % body fat category.</p

Partial correlations between handgrip or cardiorespiratory fitness and risk factors.

<p>Handgrip (HG) is handgrip (kg) adjusted for body mass. Cardiorespiratory fitness (CRF) is number of 20 m shuttles.</p><p>*p<0.05;</p><p>**p<0.001.</p

Metabolic risk score according to quartile of handgrip strength in 8–14 year old children (n = 536).

<p>Quartile 4 is the highest HG category. Handgrip quartiles are age and sex specific handgrip/kg body mass. Linear trend evaluated using Kruskal–Wallis test. Metabolic risk score is summed standardized residuals (z-score) by age and sex for HOMA score, waist circumference, TG, HDL-c, and systolic blood pressure.</p

Handgrip strength quartiles and risk of clustered metabolic risk in 8–14 year old girls (Panel A, n = 306) and boys (Panel B, n = 330).

<p>Quartile 4 is highest handgrip strength category (used as referent). Adjusted for age, maturation status and % body fat category (grey bars) and additionally for cardiorespiratory fitness (white bars). Clustered risk is defined as 1 SD above the age and sex specific mean.</p

Association between handgrip strength/kg body mass and metabolic risk factors in 8–14 year old children.

<p>Linear regression analysis adjusted for sex, age, tanner and cardiorespiratory fitness. T1–T2 = Low and middle third of % body fat; T3 = Upper third of % body fat.</p