Assessment of concrete damage and strength degradation caused by reinforcement corrosion

Structural performance deterioration of reinforced concrete structures has been extensively investigated, but very limited studies have been carried out to investigate the effect of reinforcement corrosion on time-dependent reliability with consideration of the influence of mechanical characteristics of the bond interface due to corrosion. This paper deals with how corrosion in reinforcement creates different types of defects in concrete structure and how they are responsible for the structural capacity deterioration of corrosion affected reinforced concrete structures during their service life. Cracking in cover concrete due to reinforcement corrosion is investigated by using rebar-concrete model and realistic concrete properties. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution due to reinforcement corrosion, which is examined by the experimental data available. The time-dependent reliability analysis is undertaken to calculate the life time structural reliability of corrosion damaged concrete structures by stochastic deterioration modelling of reinforced concrete. The results from the numerical example show that the proposed approach is capable of evaluating the damage caused by reinforcement corrosion and also predicting the structural reliability of concrete structures during their lifecycle

Increase in cotton yield through improved leaf physiological functioning under the soil condition of reduced chemical fertilization compensated by the enhanced organic liquid fertilization

IntroductionLow agricultural nutrient input efficiency remains a significant impediment for crop production globally. To address this issue in cotton agroecosystems, there is a need to develop sustainable crop nutrient management strategies to achieve high crop yields. We hypothesized that organic liquid fertilizer (OF) combined with reduced chemical fertilizer (CF) would enhance cotton yield by improving leaf functioning and soil properties. However, the underlying mechanism and its related process is poorly understood.MethodsThis study explored the effects of OF combined with reduced CF on cotton yield, physiology and soil properties. Treatments included a single application of CF (CF: N, P2O5 and K2O applied at 228, 131 and 95 kg ha−1) and combined applications of OF and CF (OF0.6−OF1.4) in the following ratios: OF0.6, OF+60% CF; OF0.8, OF+80% CF; OF1.0, OF+100% CF; OF1.2, OF+120% CF; OF1.4, OF+140% CF. Results and discussionThe result showed that compared with CF, OF0.8, OF1.0 and OF1.2 increased soil organic matter (SOM) content by 9.9%, 16.3% and 23.7%, respectively. Compared with CF, the OF0.6, OF0.8, OF1.0, and OF1.2 treatments increased leaf area (LA) by 10.6−26.1%, chlorophyll content (Chl content) by 6.8−39.6%, and the efficiency of photosystem II (PSII) light energy (Y(II)), electron transfer rate of PSII (ETR) and photochemical quenching (qP) by 3.6−26.3%, 4.7−15.3% and 4.3−9.8%, respectively. The OF0.8 treatment increased net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E) by 22.0%, 27.4% and 26.8%, respectively, resulting in higher seed cotton yield. The seed cotton yield and economic coefficient were positively correlated with Pn, E, Gs and Y(II) from the full boll stage to the boll opening stage. In summary, the OF0.8 treatment can maintain a high SOM content and photosynthetic performance with reduced chemical fertilizer input without sacrificing yield. The integration of OF+80% CF (OF0.8) is a promising nutrient management strategy for highly efficient cotton production under mulch drip irrigation systems

Analytical model for residual bond strength of corroded reinforcement in concrete structures

Bond strength deterioration in corrosion-damaged reinforced concrete structures significantly affects serviceability and load-carrying capacity in their remaining service life. This paper presents a new analytical model for predicting the cracking development in the surrounding concrete and the residual bond strength of rebar in concrete structures due to reinforcement corrosion. The proposed analytical method adopts the thick-walled cylinder model for the cover concrete and considers the realistic properties of the corrosion-induced cracked concrete such as anisotropic behavior, residual tensile strength, and reduced tensile stiffness. As corrosion progresses, three phases for bond strength evolution associated with concrete cracking development are defined and the corresponding corrosion levels in each phase are determined. By using the constructed new governing equation, the crack width growth in the concrete cover and the radial bursting pressure at the bond interface are evaluated. The ultimate bond strength is then estimated from the contributions of adhesion, confinement, and corrosion pressure as a function of corrosion level. Finally, the effectiveness of the proposed analytical model is demonstrated by comparing the predicted results with experimental data available, and the results show that the proposed model is useful for predicting the bond strength evolution of the corroded rebar in concrete structures

The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019

Background In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15-39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15-39 years to define adolescents and young adults. Findings There were 1.19 million (95% UI 1.11-1.28) incident cancer cases and 396 000 (370 000-425 000) deaths due to cancer among people aged 15-39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59.6 [54.5-65.7] per 100 000 person-years) and high-middle SDI countries (53.2 [48.8-57.9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14.2 [12.9-15.6] per 100 000 person-years) and middle SDI (13.6 [12.6-14.8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23.5 million (21.9-25.2) DALYs to the global burden of disease, of which 2.7% (1.9-3.6) came from YLDs and 97.3% (96.4-98.1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe

Global, regional, and national progress towards Sustainable Development Goal 3.2 for neonatal and child health: all-cause and cause-specific mortality findings from the Global Burden of Disease Study 2019

Background Sustainable Development Goal 3.2 has targeted elimination of preventable child mortality, reduction of neonatal death to less than 12 per 1000 livebirths, and reduction of death of children younger than 5 years to less than 25 per 1000 livebirths, for each country by 2030. To understand current rates, recent trends, and potential trajectories of child mortality for the next decade, we present the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 findings for all-cause mortality and cause-specific mortality in children younger than 5 years of age, with multiple scenarios for child mortality in 2030 that include the consideration of potential effects of COVID-19, and a novel framework for quantifying optimal child survival. Methods We completed all-cause mortality and cause-specific mortality analyses from 204 countries and territories for detailed age groups separately, with aggregated mortality probabilities per 1000 livebirths computed for neonatal mortality rate (NMR) and under-5 mortality rate (USMR). Scenarios for 2030 represent different potential trajectories, notably including potential effects of the COVID-19 pandemic and the potential impact of improvements preferentially targeting neonatal survival. Optimal child survival metrics were developed by age, sex, and cause of death across all GBD location-years. The first metric is a global optimum and is based on the lowest observed mortality, and the second is a survival potential frontier that is based on stochastic frontier analysis of observed mortality and Healthcare Access and Quality Index. Findings Global U5MR decreased from 71.2 deaths per 1000 livebirths (95% uncertainty interval WI] 68.3-74-0) in 2000 to 37.1 (33.2-41.7) in 2019 while global NMR correspondingly declined more slowly from 28.0 deaths per 1000 live births (26.8-29-5) in 2000 to 17.9 (16.3-19-8) in 2019. In 2019,136 (67%) of 204 countries had a USMR at or below the SDG 3.2 threshold and 133 (65%) had an NMR at or below the SDG 3.2 threshold, and the reference scenario suggests that by 2030,154 (75%) of all countries could meet the U5MR targets, and 139 (68%) could meet the NMR targets. Deaths of children younger than 5 years totalled 9.65 million (95% UI 9.05-10.30) in 2000 and 5.05 million (4.27-6.02) in 2019, with the neonatal fraction of these deaths increasing from 39% (3.76 million 95% UI 3.53-4.021) in 2000 to 48% (2.42 million; 2.06-2.86) in 2019. NMR and U5MR were generally higher in males than in females, although there was no statistically significant difference at the global level. Neonatal disorders remained the leading cause of death in children younger than 5 years in 2019, followed by lower respiratory infections, diarrhoeal diseases, congenital birth defects, and malaria. The global optimum analysis suggests NMR could be reduced to as low as 0.80 (95% UI 0.71-0.86) deaths per 1000 livebirths and U5MR to 1.44 (95% UI 1-27-1.58) deaths per 1000 livebirths, and in 2019, there were as many as 1.87 million (95% UI 1-35-2.58; 37% 95% UI 32-43]) of 5.05 million more deaths of children younger than 5 years than the survival potential frontier. Interpretation Global child mortality declined by almost half between 2000 and 2019, but progress remains slower in neonates and 65 (32%) of 204 countries, mostly in sub-Saharan Africa and south Asia, are not on track to meet either SDG 3.2 target by 2030. Focused improvements in perinatal and newborn care, continued and expanded delivery of essential interventions such as vaccination and infection prevention, an enhanced focus on equity, continued focus on poverty reduction and education, and investment in strengthening health systems across the development spectrum have the potential to substantially improve USMR. Given the widespread effects of COVID-19, considerable effort will be required to maintain and accelerate progress. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd

Reliability-based performance assessment and optimum maintenance of corroded reinforced concrete structures

Reinforcement corrosion is one of the major causes of deterioration of reinforced concrete structures exposed to aggressive environments. Deterioration caused by reinforcement corrosion reduces the serviceability and load bearing capacity of the concrete structures to an extent of serious structural failure. Consequently, this increases the resources required for the maintenance and rehabilitation over time. Due to uncertainties associated with the performance deterioration, it is difficult to accurately assess the residual strength and remaining useful life of corrosion damaged concrete structure. Therefore, the reliability-based performance assessment techniques based on stochastic deterioration modelling has significant potential for assessing the present and future performance of these structures. This can be ultimately helpful in sustainable and cost-effective infrastructure management. This research presents new analytical methods for evaluating concrete crack evolution, estimating rebar bond strength degradation and predicting residual flexural strength of concrete structures affected by reinforcement corrosion. At first, cracking in cover concrete due to reinforcement corrosion is investigated by using rebar-concrete model and realistic concrete properties. The bond strength evolution of the corroded rebar is then evaluated at different stages of cover cracking by considering adhesion, confinement and corrosion pressure acting at the bond interface. Furthermore, the residual flexural strength of concrete beams is predicted with consideration of bond failure between the rebar and concrete. The gamma process is adopted for stochastic modelling of concrete crack growth and strength deterioration with uncertainties. Then, a time-dependent reliability analysis is undertaken to evaluate the probability of failure in serviceability and load carrying capacity of corrosion damaged concrete beams. Optimal repair planning during the service life is also determined by balancing the cost for maintenance and the risk of structural failure. Finally, the results evaluated from the proposed methods are examined by available experimental and field data and the applicability is demonstrated by numerical examples. The results obtained show that the proposed methods are capable of evaluating the performance and can also provide risk-cost balanced repair strategy during the lifetime of corrosion damaged concrete structures. The knowledge gained from this research contributes to the better understanding of the mechanics of performance deterioration associated with reinforcement corrosion. Furthermore, the methods presented in this study could be helpful in assessing the actual state of performance deterioration and making decision regarding the optimal repair

Seed-Primed and Foliar Oxozinc Nanofiber Application Increased Wheat Production and Zn Biofortification in Calcareous-Alkaline Soil

Low Zinc (Zn) availability in alkaline calcareous soil is one of the major causes of low cereal yield and quality. Conventional application of Zn sulfate (ZnSO4) fertilizer through soil application attains minimal Zn efficiency as it is readily fixed in such soils. Oxozinc nanofiber (ZnONF) was evaluated for wheat Zn biofortification using different application methods to tackle this issue. Pots in triplicate (each with 7 kg soil) were arranged in a completely randomized design with a control treatment without Zn application. The conventional ZnSO4 fertilizer recommended dose (5.5 µg Zn kg−1 of soil) was used for comparison and applied through soil addition, foliar spray, and seed priming, while the ZnONF was applied through foliar spray, seed coating, and seed priming (@ 0.5 kg ha−1) either alone or in combination with ½ZnSO4 applied to the soil. The application of ZnONF significantly improved wheat plant growth as evidenced by increased plant height (14.5%), spikelets per spike (13.7%), and Zn use efficacy (611%) regardless of application methods as compared to control. The highest Zn uptake efficiency (34%) for nanofibers was obtained for theseed primed, followed by seed coating (23%) and foiar application (7%), respectively. Moreover, at the combined ZnONF and ½ZnSO4 application, further improvements for spike length, number of spikelets spike−1, grain, leaf, root, and stem Zn concentrations, as well as their respective Zn contents, were noted. These results elucidated that Zn nutrition with ZnONF was either at par with or higher than the conventional ZnSO4 fertilizer application despite significantly reduced ZnONF quantity, irrespective of the application method used. Additionally, the combined ZnONF and ½ZnSO4 (foliar spray, seed coating, or seed priming) maximized the crop Zn accumulation, wherein the ½ZnSO4 + ZnONF through foliar application exceeded grain Zn biofortification. Thus, various Oxozinc nanofibers application modes may be recommended for wheat biofortification either separately or in combination with ZnSO4 in Zn deficient calcareous soils for improved Zn nourishment

Seed-Primed and Foliar Oxozinc Nanofiber Application Increased Wheat Production and Zn Biofortification in Calcareous-Alkaline Soil

Low Zinc (Zn) availability in alkaline calcareous soil is one of the major causes of low cereal yield and quality. Conventional application of Zn sulfate (ZnSO4) fertilizer through soil application attains minimal Zn efficiency as it is readily fixed in such soils. Oxozinc nanofiber (ZnONF) was evaluated for wheat Zn biofortification using different application methods to tackle this issue. Pots in triplicate (each with 7 kg soil) were arranged in a completely randomized design with a control treatment without Zn application. The conventional ZnSO4 fertilizer recommended dose (5.5 µg Zn kg−1 of soil) was used for comparison and applied through soil addition, foliar spray, and seed priming, while the ZnONF was applied through foliar spray, seed coating, and seed priming (@ 0.5 kg ha−1) either alone or in combination with ½ZnSO4 applied to the soil. The application of ZnONF significantly improved wheat plant growth as evidenced by increased plant height (14.5%), spikelets per spike (13.7%), and Zn use efficacy (611%) regardless of application methods as compared to control. The highest Zn uptake efficiency (34%) for nanofibers was obtained for theseed primed, followed by seed coating (23%) and foiar application (7%), respectively. Moreover, at the combined ZnONF and ½ZnSO4 application, further improvements for spike length, number of spikelets spike−1, grain, leaf, root, and stem Zn concentrations, as well as their respective Zn contents, were noted. These results elucidated that Zn nutrition with ZnONF was either at par with or higher than the conventional ZnSO4 fertilizer application despite significantly reduced ZnONF quantity, irrespective of the application method used. Additionally, the combined ZnONF and ½ZnSO4 (foliar spray, seed coating, or seed priming) maximized the crop Zn accumulation, wherein the ½ZnSO4 + ZnONF through foliar application exceeded grain Zn biofortification. Thus, various Oxozinc nanofibers application modes may be recommended for wheat biofortification either separately or in combination with ZnSO4 in Zn deficient calcareous soils for improved Zn nourishment

Residual Effect of Finely-Ground Biochar Inoculated with Bio-Fertilization Impact on Productivity in a Lentil–Maize Cropping System

Biochar fertilization improves soil fertility and carbon sequestration, implying agricultural and environmental advantages. The effect of different sized previously applied biochar and biofertilizer agents on succeeding crops remains poorly known for legume–cereal cropping cycles. This study compared different particle-sized biochar and biofertilizer strains applied to lentils for their residual impact on subsequent maize growth, nutrition, and soil fertility without further polluting the environment. Three particle sizes (<2, 2–5, 5–10 mm) of Babul tree (Acacia arabica) wood biochar was obtained through grinding and sieving and applied prior to the lentil (first) crop at a rate of 500 g m−2. The commercial Rhizobium leguminosarum products Biozote-N and Rhizogold were inoculated to lentil seeds before sowing. The effect of biochar and biofertilizer agents on the succeeding maize (second) crops was evaluated for soil and crop performance. Findings revealed that particle sizes of <2 mm biochar and Biozote-N inoculation enhanced plant height, leaf area and leaf area index, biological yield, and thousand grain weight of the subsequent maize crop. Maize grain yield was enhanced by 2.5%, tissue N uptake by 15%, nitrogen uptake efficiency by 17%, grain protein content by 15%, extractable P by 17%, and soil bulk density by 3% with a residual biochar particle size of <2 mm and Biozote-N inoculation. It was concluded that the finely grounded (<2 mm) biochar particle combined with inoculation of Biozote-N was superior to larger particle sizes for enhancing crop growth and improving soil fertility status at the residual level, benefiting the subsequent crop in a legume–cereal rotation system