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Damage in soft biological tissues are a major domain of study as tissues may either undergo degradation with time or may experience in vivo failure during invasive procedures leading to a multitude of medical complications. Continuum damage models have been very successful recently to predict damage that can take place either due to fatigue loading, as a consequence of cyclic physiological loads or if the tissue is exposed to supra physiological loads especially during medical interventions. In this current work we use the mathematical framework of oblique contravariant tensors and their associated invariants to propose a damage function that takes into account the two important stages of progressive damage in collagen fibers (a) damage due to shear between matrix and fiber that can lead to debonding of the fibers and (b) total rupture of fibers. A model for the damage in the matrix has also been taken into account using the concept of equivalent stretch.The model was fitted with uniaxial experimental results from literature and showed very good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Coronavirus disease (COVID-19) spread across the globe through the human transmission. The World Health Organization suggested social distancing to curb the community spread. After national social lockdown started in India, air quality improved drastically. This further hypothesized to influence the environment and human health, and this study is positively the first to weigh it using multiple indices. The calculated environmental indices are photochemical ozone creation potential (POCP), acidification potential (AP), and eutrophication potential (EP). The cancer risk, chronic health index (CHI), and acute health index (AHI) were considered to calculate the health risk. The spatial trend change in the air pollution reflecting on these indices are calculated for four Indian megacities Delhi, Bangalore, Hyderabad, and Kolkata. Temporal variation was accounted for monthly (2019 vs 2020), one-week and two-weeks period during the social lockdown. The results showed a significant decrease in environmental and health risk during the lockdown due to a corresponding decrement in air pollution. The decrease in the particulate matter was found to play a vital role in altering the air pollution mediated risks of interest. Delhi showed a maximum difference in POCP and Acute HI by recording a dip of 70.79% and 43.53% respectively in 2020 during lockdown. The maximum reduction in health risk indices was 41%, 31%, 17%, 19% for Delhi, Bangalore, Hyderabad, and Kolkata. Bangalore recorded the maximum decline in EP, Cancer risk, Chronic HI by 66.66%, 58.62%, and 58.76% in 2020 compared to 2019. A maximum fall in AP was seen in Kolkata by 57.23% in 2020 among all cities. The connection between these drop-in indices and the cause of air pollutants were well discussed. This present paper gives more in-depth insights into air pollution's effect on environmental and health parameters by connecting and converging various air pollution aspects into a single scale. This study also enlightens the importance of controlling air pollution to have a better environment and healthy life to attain sustainable development. Conceptual illustration of impact of COVID-19 enabled social lockdown on environmental and health risk indices in India. [Display omitted] • Detailed study on COVID-19 lockdown vs environmental and health indices in India. • Included three time periods & four megacities Delhi, Mumbai, Bangalore & Kolkata. • Noticeable reduction in particulate matter and indices during lockdown. • Maximum health risk reduction in Delhi (41%) and Bangalore (31%). • Bangalore recorded maximum reduction in EP, Cancer risk, Chronic HI. [ABSTRACT FROM AUTHOR]