RESUMEN
A sustainable method to reduce the use of natural resources and the negative effects of the concrete industry on the environment is to use waste lateritic aggregate in self-compacting concrete and evaluate its fresh, mechanical and durability characteristics. Using RSM's central composite design (CCD), Thirteen different SCC mixtures have been designed with varying input factor combinations (LA: 0-100%, PPF: 0-2%) and tested for eight responses (rheological properties, like slump flow, V-funnel time, and T500; mechanical properties, like compressive, split-tensile, and flexural strengths, and durability properties like drying shrinkage and rapid chloride penetration test). The analysis of variance (ANOVA) test was performed to determine the accuracy of the mathematical models developed following the experimental results. ANOVA was used to verify eight response models (seven quadratic and one linear). The inclusion of laterite aggregate has been found to linearly reduce the workability of fresh concrete. Self-compacting concrete will have a lower V-funnel value if any combination of components falls below these two limit values (31% LA and 1.12% PPF). The area bounded by the 760-mm contour line and the graph axes recorded the highest slump flow at (28% LA and 1.26% PPF). Similarly, SCC with a lower T500 value will be produced by any combination of components below these two limit values (25% LA and 1.11% PPF). By replacing 28.5% of the granite aggregate with laterite aggregate and adding 1.24% polypropylene fiber, the compressive strength of M30 grade self-compacting concrete increased by 12.33% after 28 days. A similar strength gain of 7.89% was seen in the splitting tensile by replacing 28% of the granite aggregate with laterite aggregate and adding 1.46% polypropylene fiber over the control mix, and a flexural strength gain of 14.46% was seen by replacing 31.4% of laterite aggregate and adding 1.2% polypropylene fiber, respectively. The low drying shrinkage values are related to a combination of LA concentration (34.4% replacement) and PPF (1.31%) and minimum chloride ingress is located in the region with a LA concentration (30.5% replacement) and a PPF content (1.26%), The projected optimal data were verified experimentally with an error rate of less than 5%. Thus, it is highly recommended that the created model be adequate and capable of optimizing both the experimental and analytical values. It is recommended that the utilization of 25% LA and 1% PPF in lateritic self-compacting concrete provides optimum outcomes for the construction industry in the field of civil engineering.
RESUMEN
Background: Estimating seroepidemiolgical prevalence of SARS-CoV-2 antibody is an essential public health strategy. There is insufficient evidence of prevalence among those belonging to young age population in India. Objective: To compare the SARS-CoV-2 seropositivity rate between children and adults in selected sites from India. Materials and Methods: This was a multicentric population-based seroepidemiological study conducted in selected urban and rural areas of five sites selected from four states (Delhi, Odisha, Uttar Pradesh, Tripura) of India. Participants aged ≥1 year were included from different clusters of each area. Total serum antibody against SARS-CoV-2 virus was assessed qualitatively by using a standard enzyme-linked immunosorbent assay (ELISA) kit. Results: Data collection period was from 15 March 2021 to 10 June 2021. Total available data was of 4509 participants, of whom 700 were <18 years of age and 3809 were ≥18 years of age. The site-wise number of available data among those aged 2-17 years was 92, 189, 165, 146 and 108 for the sites of Delhi urban, Delhi rural, Bhubaneswar rural, Gorakhpur rural and Agartala rural area, respectively. The seroprevalence was 55.7% in the <18 years age group and 63.5% in the ≥18 years age group. The prevalence among female children was 58% and among male children was 53%. Conclusion: SARS-CoV-2 seropositivity rate among children was high and comparable to that of the adult population. Hence, it is unlikely that any future third wave by prevailing SARS-CoV-2 variant would disproportionately infect children 2 years or older.
RESUMEN
The recent SARS-CoV-2 outbreak has been declared a global health emergency. It will take years to vaccinate the whole population to protect them from this deadly virus, hence the management of SARS-CoV-2 largely depends on the widespread availability of an accurate diagnostic test. Toward addressing the unmet need of a reliable diagnostic test in the current work by utilizing the power of Systematic Evolution of Ligands by EXponential enrichment, a 44-mer G-quadruplex-forming DNA aptamer against spike trimer antigen of SARS-CoV-2 was identified. The lead aptamer candidate (S14) was characterized thoroughly for its binding, selectivity, affinity, structure, and batch-to-batch variability by utilizing various biochemical, biophysical, and in silico techniques. S14 has demonstrated a low nanomolar KD, confirming its tight binding to a spike antigen of SARS-CoV-2. S14 can detect as low as 2 nM of antigen. The clinical evaluation of S14 aptamer on nasopharyngeal swab specimens (n = 232) has displayed a highly discriminatory response between SARS-CoV-2 infected individuals from the non-infected one with a sensitivity and specificity of â¼91% and 98%, respectively. Importantly, S14 aptamer-based test has evinced a comparable performance with that of RT-PCR-based assay. Altogether, this study established the utility of aptamer technology for the detection of SARS-CoV-2.