Effect of Curing Time and Percentage of Concrete Additives on Increasing the Compressive Strength and Shear Strength of Silty Sand Soils

The existence of silty sand in the infrastructure under concrete constructions, hydraulic structures, and irrigation systems has always caused challenges. Improving this kind of soil is always a challenging approach to increase compressive strength and shear stress. There is a conception that adding some extra material such as concrete can increase the stability of this soil against contributed forces. The present study investigated the effects of curing time (3, 7, 14, 21, and 28 days) and different percentages of various additives (3%, 5%, and 7%) on the strength of the silty sand soils. A series of laboratory tests were carried out to measure the Uniaxial Compressive Strength (UCS) and California Bearing Ratio (CBR) by evaluating the effect of additives on the strength parameters of silty sand soil. In total, 299 experimental tests have been conducted in the soil mechanics laboratory of SRBIAU. Results indicated that adding additives such as concrete to silty sand soil improved significantly the compressive strength and shear strength. The comparisons among the experimental test illustrate that due to increasing the curing time, the aforementioned parameters were increased significantly; however, Confix and Bentonite aggregates did not have a marginal effect on the compressive strength and shear strength. Also, after the 21st day of the curing time, the rate of increment of the UCS and CBR reached slightly and then attained a constant value. Also, after this duration, the curing time is an independent factor in the variation of the UCS and CBR tests. Furthermore, the addition of 5% Pozzolana cement and 7% Portland cement with 28 days of curing had the highest CBR number and UCS resistance of 176.26 and 17.58 kg/cm2, respectively. Also, the sketch of the different failure patterns was shown during the curing time. Finally, by increasing the curing time, the behavior of specimens from semi-brittle to brittle made them harder

Numerical Study of the Rough Bed Impact on Energy Dissipation and Cavitation on Chute Spillways

Using a rough bed for spillway compare to common dissipation methods such as stilling basins, stepped spillways, ski jumps, and bed elements may be more efficient to boost energy dissipation. In this research, the impact of spillway continuous bed roughness on energy dissipation was investigated. For this purpose, a non-dimensional relationship was developed, and by calibrating the numerical model based on the present experimental study, energy dissipation over the spillway for three slopes of 15, 22.5, and 30 (degree) with six roughness sizes of 0.0, 0.005, 0.0072, 0.0111, 0.016, and 0.022 (m) and three discharges of 170, 110, and 90 (lit/s) was investigated. Based on the present results, using a rough bed spillway will increase energy dissipation. Also, the ratio of energy lost per meter length of rough bed spillway to that of smooth spillway increases by chute slope. The results showed that the highest amount of relative energy consumption in the presence of roughness was related to the slope of 22.5 degrees and 22.2 mm for roughness (85%), and the lowest relative energy consumption was observed in the control state (25%). As a result of the present study, a natural rough bed without concrete coating has befitted in terms of environmental aspects, construction cost, and energy loss

Systematic review and meta-analytic findings on the association between killer-cell immunoglobulin-like receptor genes and susceptibility to pulmonary tuberculosis

Several studies have evaluated the association between killer-cell immunoglobulin-like receptors (KIR) genes and susceptibility risk to tuberculosis (TB) infection. Nonetheless, their outcomes have not been conclusive and consistent. Here we implemented a systematic review and meta-analysis of KIR genes association to susceptibility risk of pulmonary TB (PTB) infection to attain a clear understanding of the involvement of these genes in susceptibility to PTB infection. A systematic search was conducted in the MEDLINE/PubMed and Scopus databases to find case-control studies published before November 2020. Pooled odds ratio (OR) and 95 confidence interval (95 CI) were calculated to determine the association between KIR genes and risk of PTB infection. After comprehensive searching and implementing the inclusion and exclusion criteria, 10 case-control studies were included in the meta-analysis. Four KIR genes were found to have significant positive association with PTB susceptibility risk of infection, including 2DL3 (OR = 1.454, 95 CI = 1.157�1.827; P = 0.001), 2DS1 (OR = 1.481, 95 CI = 1.334�1.837; P < 0.001), 2DS4 (OR = 1.782, 95 CI = 1.273�2.495; P = 0.001) and 3DL1 (OR = 1.726, 95 CI = 1.277�2.333; P < 0.001). However, the results showed that the remaining KIR genes (2DS2-4, 2DL1, 2, 4, 3DL1-2) and two pseudogenes (2DP1 and 3DP1) did not have significant associations with risk of PTB infection. This meta-analysis provides reliable evidence that the KIR genes 2DL3, 2DS1, 2DS4, and 3DL1 may be associated with an increased risk of PTB infection. © 2020 Informa UK Limited, trading as Taylor & Francis Group

Multi-facets of neutrophil extracellular trap in infectious diseases: Moving beyond immunity

peer reviewedNeutrophil extracellular traps (NETs) are networks of extracellular chromosomal DNA fibers, histones, and cytoplasmic granule proteins. The release of NET components from neutrophils is involved in the suppression of pathogen diffusion. Development of NETs around target microbes leads to disruption of the cell membrane, eventuating in kind of cell death that is called as NETosis. The very first step in the process of NETosis is activation of Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase upon signaling by innate immune receptors. Afterwards, produced Reactive oxygen species (ROS) trigger protein-arginine deiminase type 4, neutrophil elastase, and myeloperoxidase to generate decondensed chromatin and disrupted integrity of nuclear membrane. Subsequently, decondensed chromatin is mixed with several enzymes in the cytoplasm released from granules, leading to release of DNA and histones, and finally formation of NET. Several reports have indicated that NETosis might contribute to the immune responses through limiting the dissemination of microbial organisms. In this review, we discuss recent advances on the role of neutrophils, NETs, and their implications in the pathogenesis of microbial infections. Additionally, the prospective of the NET modulation as a therapeutic strategy to treat infectious diseases are clarified. © 2021 Elsevier Lt