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Lately, considerable efforts have been directed towards investigating the practicality of using coarse recycled concrete aggregate as a potential substitute for natural coarse aggregate (NCA) in concrete construction. Research has shown that both the proportion of replacement and the properties of recycled aggregates play a significant role in affecting the tensile strength, compressive strength, and bonding characteristics of concrete. In certain cases, recycled aggregate concrete exhibits lesser mechanical properties when compared to concrete made with normal aggregates. The current study investigated the performance of Sika AnchorFix-1 to enhance the bond strength between steel bars and recycled aggregate concrete. The findings suggest that Sika AnchorFix-1 successfully prevented the concrete rupture in the case of concrete with recycled concrete aggregates, whereas concrete rupture could not be prevented in the case of concrete with recycled brick aggregates. Hence, a lower bond strength was obtained for specimens with recycled bricks aggregates than specimens with recycled concrete aggregates.

This study investigates the innovative use of industrial waste pozzolana, specifically pumice powder (PP), as a partial replacement for cement, combined with hybrid fibers in concrete. Seven formulations varying PP content from 10 % to 35 % were tested, identifying 15 % PP as optimal. PP improved porosity due to its fineness, leading to better homogeneity, a refined microstructure, and an optimum compressive strength of 28.8 MPa with reduced permeability, enhancing durability. Hybrid fibers, including steel fibers (SF) from waste tires and polypropylene fibers (PF), improved toughness, ductility, and resistance to brittle failure. Tests on hybrid fiber-reinforced concrete (HyFRC) mixes with 1 % and 2 % hybrid fibers showed up to an 18.09 % increase in compressive, tensile, and flexural strengths. Energy dissipation in compressive response improved by 544.20 %, while flexural and splitting responses increased by up to 299.65 % and 208.57 %. Durability assessments in hydrochloric (HCl) and sulfuric acid (H2SO4) exposure revealed the synergy of fibers and PP enhanced resistance to chemical degradation, with high PF mixes losing as little as 0.04 % strength. Scanning electron microscopy (SEM) confirmed a dense, well-bonded matrix with reduced porosity. Analytical characterizations of mixtures such as energy dispersive x-ray spectroscopy (EDX) were studied. Regression models developed using Popovic’s and Mander’s models, accurately predicted HyFRC stress-strain behavior, closely aligning with experimental results. The integration of PP and hybrid fibers not only improved mechanical properties but also extended service life in harsh environments, offering a cost-effective, sustainable concrete solution.

The manufacturing of Ordinary Portland Cement (OPC) is one of the primary contributors to atmospheric CO2. The use of high-volume OPC replacement materials in self-compacting concrete (SCC) has been the focus of several investigations owing to the increased demand for environmentally friendly building materials. This paper presents the experimental investigation of the properties of SCC, where 25–70 % OPC was replaced with fly ash and calcined calcium carbonate (BCC). Different experimental tests, such as workability, mechanical properties, durability, and microstructural characteristics, have been carried out. The test results of workability showed that all the mixes were conforming to satisfactory conditions of EFNARC for the T500 flow timings within the range from 2.50 to 4.55 seconds and slump flow values within the range from 650 to 800 mm. This mix, here called 20F5C, had optimum behaviour with its 91-day compressive strength of 73.8 MPa, a gain of 7.7 % over the control. Replacement ratio, microstructure, and mechanical properties were correlated. Even high-replacement mixes like 50F20C provided a 91-day compressive strength of 58.9 MPa. This clearly shows the prospect of a considerable reduction in cement consumption while maintaining structural integrity. These results indicate the possibility of reduced OPC consumption in concrete production, which again identifies low carbon emission and utilization of waste according to international sustainability goals. The findings have revealed that SCC made with high-volume replacements of OPC could be an economically viable and environmentally friendly solution for the construction industry worldwide.

Hurricanes and associated stormwater runoff events are expected to greatly impact coastal marine water quality, yet little is known about their immediate effects on microbiological quality of near-shore water. This study sampled Hilo Bay immediately after the impact of Hurricane Lane to understand the spatial and temporal variations of the abundance and diversity of fecal indicator enterococci, common fecal pathogens, and antibiotic resistance genes (ARGs). Water samples from seven sampling sites over 7 days were collected and analyzed, which showed that the overall microbiological water quality parameters [enterococci geometric mean (GM): 6–22 cfu/100 mL] fell within water quality standards and that the temporal dynamics indicated continuing water quality recovery. However, considerable spatial variation was observed, with the most contaminated site exhibiting impaired water quality (GM = 144 cfu/100 mL). The Enterococcuspopulation also showed distinct genotypic composition at the most contaminated site. Although marker genes for typical fecal pathogens (invAfor Salmonella, hipOfor Campylobacter, mipfor Legionella pneumophila, and eaeAfor enteropathogenic Escherichia coli) were not detected, various ARGs (ermB, qurS, tetM, blaTEM, and sul1) and integron-associated integrase intI1 were detected at high levels. Understanding the temporal and spatial variation of microbiological water quality at fine granularity is important for balancing economic and recreational uses of coastal water and the protection of public health post the impact of major hurricane events.

From birth to health, surfactants play an essential role in our lives. Due to the importance, their environmental impacts are well understood. One of the aspects that has been extensively studied is their impact on bacteria, particularly on their motility. Here, we uncover an alternate chemotactic strategy triggered by surfactants—diffusiophoresis. We show that even a trace amount of ionic surfactants, down to a single ppm level, can promote the bacterial diffusiophoresis by boosting the surface charge of the cells. Because diffusiophoresis is driven by the surface–solute interactions, surfactant-enhanced diffusiophoresis is observed regardless of the types of bacteria. Whether Gram-positive or -negative, flagellated or nonflagellated, the surfactants enable fast migration of freely suspended bacteria, suggesting a ubiquitous locomotion mechanism that has been largely overlooked. We also demonstrate the implication of surfactant-enhanced bacterial diffusiophoresis on the rapid formation of biofilms in flow networks, suggesting environmental and biomedical implications.

Recent research have highlighted the potential of hybrid confinement, combining high tensile strength fiber-reinforced polymers with large rupture strain confinement. This study presents experimental findings on 64 cylindrical and square-shaped specimens tested under axial compression, introducing a novel hybrid confinement method utilizing low-cost fiberglass chopped strand mat sheets and cotton ropes (COFS confinement). The experimental and analytical results yielded several key conclusions. Firstly, circular specimens exhibited significant peak strength increases in various subgroups, with enhancements ranging from 97.5% to 285.5%, and ultimate strain improvements ranging from 588.6% to 1650.0%. Similarly, square specimens under COFS confinement also demonstrated notable enhancements in ultimate strength and strain, with increases up to 244.7% and 1083.0%, respectively, particularly evident with higher levels of confinement. The influence of cross-sectional shape on compressive strength, strain, and energy dissipation was noted, with COFS confinement notably improving these factors for circular sections. Additionally, the study found that as the unconfined compressive strength increased, the enhancement in compressive strength, ultimate strain, and energy dissipation decreased. Moreover, the confinement ratio positively affected axial behavior improvement, with a proportional enhancement observed. However, the efficacy of the confinement ratio was influenced by cross-section type and plain concrete strength, emphasizing the need for considering these factors in COFS-based confinement design. Lastly, an analytical design-oriented model proposed for approximating stress vs. strain curves of COFS-confined concrete showed close agreement with experimental results, providing valuable insights for future design considerations.

This study presents an innovative approach to enhance the flexural capacity of cement-clay interlocking (CCI) brick walls using ferrocement jackets with an expanded wire mesh. The investigation involved 15 CCI brick walls subjected to flexural load testing, exploring various mesh sizes and anchor configurations on single and dual sides. The results revealed that while the primary failure mode involved dry joint opening and subsequent ferrocement debonding in the strengthened walls, effective anchorage mechanisms delayed dry joint opening until debonding occurred. The reinforced walls exhibited improved peak load capacity, notably in dual-sided reinforcement cases. With plastering on both sides and supplemented with anchors, an improvement of up to 221% in flexural capacity was obtained. The study emphasizes the influence of wire mesh size on anchorage effectiveness and its correlation with debonding susceptibility. Additionally, the moment-curvature analysis demonstrated resilient, ductile responses in load-bearing characteristics, with occasional abrupt declines due to ferrocement jacket debonding. Unlike control walls, the strengthened walls exhibited strains exceeding yield thresholds, indicating enhanced structural performance.

ABSTRACTCambodia's first-line artemisinin combination therapy, dihydroartemisinin-piperaquine (DHA-PPQ), is no longer sufficiently curative against multidrug-resistant Plasmodium falciparummalaria at some Thai-Cambodian border regions. We report recent (2008 to 2013) drug resistance trends in 753 isolates from northern, western, and southern Cambodia by surveying for ex vivodrug susceptibility and molecular drug resistance markers to guide the selection of an effective alternative to DHA-PPQ. Over the last 3 study years, PPQ susceptibility declined dramatically (geomean 50% inhibitory concentration [IC50] increased from 12.8 to 29.6 nM), while mefloquine (MQ) sensitivity doubled (67.1 to 26 nM) in northern Cambodia. These changes in drug susceptibility were significantly associated with a decreased prevalence of P. falciparummultidrug resistance 1 gene (Pfmdr1) multiple copy isolates and coincided with the timing of replacing artesunate-mefloquine (AS-MQ) with DHA-PPQ as the first-line therapy. Widespread chloroquine resistance was suggested by all isolates being of the P. falciparumchloroquine resistance transporter gene CVIET haplotype. Nearly all isolates collected from the most recent years had P. falciparumkelch13mutations, indicative of artemisinin resistance. Ex vivobioassay measurements of antimalarial activity in plasma indicated 20% of patients recently took antimalarials, and their plasma had activity (median of 49.8 nM DHA equivalents) suggestive of substantial in vivodrug pressure. Overall, our findings suggest DHA-PPQ failures are associated with emerging PPQ resistance in a background of artemisinin resistance. The observed connection between drug policy changes and significant reduction in PPQ susceptibility with mitigation of MQ resistance supports reintroduction of AS-MQ, in conjunction with monitoring of the P. falciparummdr1copy number, as a stop-gap measure in areas of DHA-PPQ failure.

Background Krathom (Mitragyna speciosaKorth.) is the most commonly used illicit substance in Thailand, and its use has become widespread internationally. Studies on krathom dependence and its health impact are scarce, as there has been no instrument to measure its dependence syndrome and classify krathom users. This study aimed to develop and explore the factor structure, reliability, and validity of a Krathom Dependence Scale (KDS).Methods This study comprised 2 phases. First, cross-sectional surveys were conducted with 523 (Phase I) and 595 (Phase II) male villagers aged >25 years who were regular, occasional, ex-, or nonusers of krathom. Scale construction was based on the qualitative results from users and previous literature. Exploratory factor analysis (EFA) using maximum likelihood extraction with oblimin rotation was conducted in Phase I and confirmatory factor analysis (CFA) in Phase II to confirm the construct of the scale. Internal consistency of the KDS was assessed using Cronbach's alpha coefficient. Discriminative validity was examined by checking its ability to differentiate between regular and occasional users and patterns of krathom use and its concurrent validity by comparing its levels of score with the Fagerstrom Test for Nicotine Dependence (FTND). The KDS contains 16 items on a 0–3 (never–always) rating scale, making a total score of 0–48.Results Phase I EFA revealed a single-factor solution for the scale, which was confirmed by the CFA in Phase II, with an alpha coefficient of .98. The KDS discriminates regular from occasional users reasonably well and is highly correlated with the FTND score. Two cutoffs were suggested: 34/35 for distinguishing moderate from high dependence and 13/14 for low from moderate.Conclusions The KDS appears to capture key theoretical constructs and correlates with indices of drug dependence by standard criteria. It should be useful in early intervention for those with krathom use disorders in community and primary care settings.

ABSTRACT.Background:Krathom (Mitragyna speciosaKorth.) is the most commonly used illicit substance in Thailand, and its use has become widespread internationally. Studies on krathom dependence and its health impact are scarce, as there has been no instrument to measure its dependence syndrome and classify krathom users. This study aimed to develop and explore the factor structure, reliability, and validity of a Krathom Dependence Scale (KDS). Methods:This study comprised 2 phases. First, cross-sectional surveys were conducted with 523 (Phase I) and 595 (Phase II) male villagers aged >25 years who were regular, occasional, ex-, or nonusers of krathom. Scale construction was based on the qualitative results from users and previous literature. Exploratory factor analysis (EFA) using maximum likelihood extraction with oblimin rotation was conducted in Phase I and confirmatory factor analysis (CFA) in Phase II to confirm the construct of the scale. Internal consistency of the KDS was assessed using Cronbach's alpha coefficient. Discriminative validity was examined by checking its ability to differentiate between regular and occasional users and patterns of krathom use and its concurrent validity by comparing its levels of score with the Fagerstrom Test for Nicotine Dependence (FTND). The KDS contains 16 items on a 0–3 (never–always) rating scale, making a total score of 0–48. Results:Phase I EFA revealed a single-factor solution for the scale, which was confirmed by the CFA in Phase II, with an alpha coefficient of .98. The KDS discriminates regular from occasional users reasonably well and is highly correlated with the FTND score. Two cutoffs were suggested: 34/35 for distinguishing moderate from high dependence and 13/14 for low from moderate. Conclusions:The KDS appears to capture key theoretical constructs and correlates with indices of drug dependence by standard criteria. It should be useful in early intervention for those with krathom use disorders in community and primary care settings.

Previously, ivermectin (1 to 10 mg/kg of body weight) was shown to inhibit the liver-stage development of Plasmodium bergheiin orally dosed mice. Here, ivermectin showed inhibition of the in vitrodevelopment of Plasmodium cynomolgischizonts (50% inhibitory concentration [IC50], 10.42 μM) and hypnozoites (IC50, 29.24 μM) in primary macaque hepatocytes when administered as a high dose prophylactically but not when administered in radical cure mode.