Autogenous healing in cement: A kinetic Monte Carlo simulation of CaCO3 precipitation

Autogenous healing induced by the dissolution of C-S-H and CH in a cracked cement paste was modelled in this study, at the mesoscale of tens of nanometres. The pore solution contains carbon dioxide (CO2) resulting in the precipitation of calcium carbonate (CaCO3) into the crack. The simulations were performed using MASKE, a recently developed coarse-grained Kinetic Monte Carlo framework where the molecules of the solid phases are modelled as mechanically interacting particles that can also precipitate and dissolve. The precipitation of CaCO3 molecules was initially observed in tiny gel pores within the C-S-H, but eventually extends completely filling the crack. The mechanical properties of the healed system were also investigated by straining the simulation box, computing the corresponding virial stress, and plotting the resulting stress-strain relationship

Advancements in bacteria based self-healing concrete and the promise of modelling

In the last two decades self-healing of concrete through microbial based carbonate precipitation has emerged as a promising technology for making concrete structures more resilient and sustainable. Currently, progress in the field is achieved mainly through physical experiments, but their duration and cost are barriers to innovation and keep the number of large scale applications still very limited. Modelling and simulation of the phenomena underlying microbial based healing of concrete may provide a key to complement the experimental efforts, but their development is still in its infancy. In this review, we briefly present the field, introduce some key aspects emerged from the experiments, present the main ongoing developments in modelling and simulation of mineral and microbial systems, and discuss how their synergy may be accomplished to speed up progress in the near future

Carbonation and self-healing in concrete: Kinetic Monte Carlo simulations of mineralization

Industrial applications of carbonation such as self-healing and carbon capture and storage have been limited, due to a lack of reliable predictive models linking the chemistry of carbonation at the molecular scale to microstructure development and macroscopic properties. This work proposes a coarse-grained Kinetic Monte Carlo (KMC) approach to simulate microstructural evolution of a model cement paste during carbonation, along with evolution of pore solution chemistry and saturation indexes of solid species involved. The simulations predict the effective rate constants for Ca(OH)2 dissolution and CaCO3 precipitation as kCa(OH)2 = 2.20 × 10−5 kg/m3/s and kCaCO3 = 4.24 × 10−6 kg/m3/s. These values are directly fed to a macroscale reactive transport model to predict carbonate penetration depth. The rate constants from the molecular scale are used in a boundary nucleation and growth model to predict self-healing of cracks. Subsequently these results are compared with experimental data, and provide good agreement. This proposed multiscale approach can help understand and manage the carbonation of both traditional and new concretes, supporting applications in residual lifetime assessment, carbon capture, and self-healing

DISCONNECTION: DESIGNS AND DESIRES

One of the paradoxes of disconnection is that social platforms like Facebook frame it as a threat to our prosperity while critics associated with “the techlash” maintain that quite on the contrary it is the only thing that brings back the possibility for good life. Disconnection means different things for different actors and these differences manifest in varying desires and designs. The five papers in this panel draw on empirical research and media and cultural theory to find answers to questions such as what process have led to the desires to disconnect; how does something disconnect; when does it disconnect; what does it disconnect; and whose disconnection it is? Two of the papers map the choice to disconnect in situations where on one hand digital participation has become structurally necessary by the demands of the society and on the other where users are doing outdoor activities and it is connection that requires activity. Three of the papers focus on particular designs of disconnection from Facebook’s off-Facebook Activity Tool to UX Design Decks and the Light Phone. As a whole, the panel describes the different ways disconnection is becoming central to our online existence

SPONTANEOUS ADVERSE DRUG REACTION REPORTING IN A TERTIARY CARE HOSPITAL IN CALICUT

Objective: The study was conducted to assess the adverse drug reactions (ADRs) reported in a tertiary care hospital in Calicut.Methods: Spontaneous ADR reporting method was followed for the study. The ADRs reported by the health-care professionals, or the patients were confirmed with the physician-in-charge. Further, the assessments of type, severity, and preventability of reported ADRs were done using Wills and Brown classification, modified Schumock and Thornton severity scale, and modified Hartwig and Siegel preventability scale.Results: A total of 30 ADRs were reported. A study found that the incidence of ADRs was more in males (1.14%) when compared to females (0.79%). Geriatric patients showed more incidences of ADRs (1.04%) when compared to pediatrics (0.69%) and adults (1.02%). More number of ADRs was associated with antibiotics (23.33%) and anticonvulsants (23.33%) than another category of drugs. Based on type or mechanism involved 80% of ADRs were pharmacologically related (Augmented) ADRs. Severity assessment showed that 50% were mild, 46.67% were moderate, and 3.33% were severe. Assessment of preventability showed that 63.33% of ADRs were not preventable, 30% were preventable, and 6.67% were probably preventable.Conclusion: The study was useful in finding the age category and drugs that were more prone to ADRs. This will render precautions and monitoring in the future. The importance of ADR monitoring unit and aid of clinical pharmacist in the monitoring and assessment were very well considered during the study

Emphysema Progression and Lung Function Decline Among Angiotensin Converting Enzyme Inhibitors and Angiotensin-Receptor Blockade Users in the COPDGene Cohort

BackgroundAttenuation of transforming growth factor β by blocking angiotensin II has been shown to reduce emphysema in a murine model. General population studies have demonstrated that the use of angiotensin converting enzyme inhibitors (ACEis) and angiotensin-receptor blockers (ARBs) is associated with reduction of emphysema progression in former smokers and that the use of ACEis is associated with reduction of FEV1 progression in current smokers.Research questionIs use of ACEi and ARB associated with less progression of emphysema and FEV1 decline among individuals with COPD or baseline emphysema?MethodsFormer and current smokers from the Genetic Epidemiology of COPD Study who attended baseline and 5-year follow-up visits, did not change smoking status, and underwent chest CT imaging were included. Adjusted linear mixed models were used to evaluate progression of adjusted lung density (ALD), percent emphysema (%total lung volume <-950 Hounsfield units [HU]), 15th percentile of the attenuation histogram (attenuation [in HU] below which 15% of voxels are situated plus 1,000 HU), and lung function decline over 5 years between ACEi and ARB users and nonusers in those with spirometry-confirmed COPD, as well as all participants and those with baseline emphysema. Effect modification by smoking status also was investigated.ResultsOver 5 years of follow-up, compared with nonusers, ACEi and ARB users with COPD showed slower ALD progression (adjusted mean difference [aMD], 1.6; 95% CI, 0.34-2.9). Slowed lung function decline was not observed based on phase 1 medication (aMD of FEV1 % predicted, 0.83; 95% CI, -0.62 to 2.3), but was when analysis was limited to consistent ACEi and ARB users (aMD of FEV1 % predicted, 1.9; 95% CI, 0.14-3.6). No effect modification by smoking status was found for radiographic outcomes, and the lung function effect was more pronounced in former smokers. Results were similar among participants with baseline emphysema.InterpretationAmong participants with spirometry-confirmed COPD or baseline emphysema, ACEi and ARB use was associated with slower progression of emphysema and lung function decline.Trial registryClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov

Alpha-1 Antitrypsin MZ Heterozygosity Is an Endotype of Chronic Obstructive Pulmonary Disease.

Rationale: Multiple studies have demonstrated an increased risk of chronic obstructive pulmonary disease (COPD) in heterozygous carriers of the AAT (alpha-1 antitrypsin) Z allele. However, it is not known if MZ subjects with COPD are phenotypically different from noncarriers (MM genotype) with COPD. Objectives: To assess if MZ subjects with COPD have different clinical features compared with MM subjects with COPD. Methods: Genotypes of SERPINA1 were ascertained by using whole-genome sequencing data in three independent studies. We compared outcomes between MM subjects with COPD and MZ subjects with COPD in each study and combined the results in a meta-analysis. We performed longitudinal and survival analyses to compare outcomes in MM and MZ subjects with COPD over time. Measurements and Main Results: We included 290 MZ subjects with COPD and 6,184 MM subjects with COPD across the three studies. MZ subjects had a lower FEV1% predicted and greater quantitative emphysema on chest computed tomography scans compared with MM subjects. In a meta-analysis, the FEV1 was 3.9% lower (95% confidence interval [CI], -6.55% to -1.26%) and emphysema (the percentage of lung attenuation areas <-950 HU) was 4.14% greater (95% CI, 1.44% to 6.84%) in MZ subjects. We found one gene, PGF (placental growth factor), to be differentially expressed in lung tissue from one study between MZ subjects and MM subjects. Conclusions: Carriers of the AAT Z allele (those who were MZ heterozygous) with COPD had lower lung function and more emphysema than MM subjects with COPD. Taken with the subtle differences in gene expression between the two groups, our findings suggest that MZ subjects represent an endotype of COPD

Pulmonary Arterial Pruning and Longitudinal Change in Percent Emphysema and Lung Function The Genetic Epidemiology of COPD Study

BackgroundPulmonary endothelial damage has been shown to precede the development of emphysema in animals, and vascular changes in humans have been observed in COPD and emphysema.Research questionIs intraparenchymal vascular pruning associated with longitudinal progression of emphysema on CT imaging or decline in lung function over 5 years?Study design and methodsThe Genetic Epidemiology of COPD Study enrolled ever smokers with and without COPD from 2008 through 2011. The percentage of emphysema-like lung, or "percent emphysema," was assessed at baseline and after 5 years on noncontrast CT imaging as the percentage of lung voxels < -950 Hounsfield units. An automated CT imaging-based tool assessed and classified intrapulmonary arteries and veins. Spirometry measures are postbronchodilator. Pulmonary arterial pruning was defined as a lower ratio of small artery volume (< 5 mm2 cross-sectional area) to total lung artery volume. Mixed linear models included demographics, anthropomorphics, smoking, and COPD, with emphysema models also adjusting for CT imaging scanner and lung function models adjusting for clinical center and baseline percent emphysema.ResultsAt baseline, the 4,227 participants were 60 ± 9 years of age, 50% were women, 28% were Black, 47% were current smokers, and 41% had COPD. Median percent emphysema was 2.1 (interquartile range, 0.6-6.3) and progressed 0.24 percentage points/y (95% CI, 0.22-0.26 percentage points/y) over 5.6 years. Mean FEV1 to FVC ratio was 68.5 ± 14.2% and declined 0.26%/y (95% CI, -0.30 to -0.23%/y). Greater pulmonary arterial pruning was associated with more rapid progression of percent emphysema (0.11 percentage points/y per 1-SD increase in arterial pruning; 95% CI, 0.09-0.16 percentage points/y), including after adjusting for baseline percent emphysema and FEV1. Arterial pruning also was associated with a faster decline in FEV1 to FVC ratio (-0.04%/y per 1-SD increase in arterial pruning; 95% CI, -0.008 to -0.001%/y).InterpretationPulmonary arterial pruning was associated with faster progression of percent emphysema and more rapid decline in FEV1 to FVC ratio over 5 years in ever smokers, suggesting that pulmonary vascular differences may be relevant in disease progression.Trial registryClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov

Machine Learning Characterization of COPD Subtypes Insights From the COPDGene Study

COPD is a heterogeneous syndrome. Many COPD subtypes have been proposed, but there is not yet consensus on how many COPD subtypes there are and how they should be defined. The COPD Genetic Epidemiology Study (COPDGene), which has generated 10-year longitudinal chest imaging, spirometry, and molecular data, is a rich resource for relating COPD phenotypes to underlying genetic and molecular mechanisms. In this article, we place COPDGene clustering studies in context with other highly cited COPD clustering studies, and summarize the main COPD subtype findings from COPDGene. First, most manifestations of COPD occur along a continuum, which explains why continuous aspects of COPD or disease axes may be more accurate and reproducible than subtypes identified through clustering methods. Second, continuous COPD-related measures can be used to create subgroups through the use of predictive models to define cut-points, and we review COPDGene research on blood eosinophil count thresholds as a specific example. Third, COPD phenotypes identified or prioritized through machine learning methods have led to novel biological discoveries, including novel emphysema genetic risk variants and systemic inflammatory subtypes of COPD. Fourth, trajectory-based COPD subtyping captures differences in the longitudinal evolution of COPD, addressing a major limitation of clustering analyses that are confounded by disease severity. Ongoing longitudinal characterization of subjects in COPDGene will provide useful insights about the relationship between lung imaging parameters, molecular markers, and COPD progression that will enable the identification of subtypes based on underlying disease processes and distinct patterns of disease progression, with the potential to improve the clinical relevance and reproducibility of COPD subtypes