Stabilization/solidification of heavy metal-contaminated marl soil using a binary system of cement and fuel fly ash.

The stabilization/solidification (S/S) method is one of the most effective remediation techniques for treating contaminated soils. Several stabilizers, mostly the cementitious materials, have been used for the S/S treatment. In this paper, the feasibility of utilizing fuel fly ash (FFA) as a partial replacement of ordinary Portland cement (OPC) for the S/S treatment of marl soil contaminated with heavy metals was investigated. Two industrial waste materials, namely steel and electroplating wastes, were used to synthetically contaminate the marl soil. The stabilizers comprising of OPC and FFA were mixed with the contaminated soil at different dosages ranging from 10 to 40%, by mass, and a total of 48 S/S-treated soil mixtures were prepared. A series of experiments, including density, porosity, permeability, unconfined compressive strength (UCS), and toxicity characteristics leaching procedure (TCLP), were carried out on the soil mixtures to evaluate the efficiency of the proposed S/S treatment. Test results showed that the incorporation of FFA at higher volumes reduced the density and increased the porosity and permeability of the treated mixtures. Although FFA addition resulted in reducing the UCS values by an average of 46%, and this reduction was more significant at higher FFA percentages, the UCS values of all mixtures were more than 0.35 MPa (350 kPa), which passed the minimum requirements set by USEPA. In addition, the metal immobilization ability of the proposed treatment was confirmed by the TCLP analysis. As compared to the negative effect of the contamination of the soil by the electroplating waste, the contamination of the soil by steel waste had a higher negative effect. The results of this study would contribute in selecting an environment-friendly treatment of the contaminated soils using industrial waste materials, such as FFA, as a partial replacement of OPC. Nevertheless, the present study is an initial attempt to explore the possibility of utilizing FFA as a partial replacement of OPC in S/S treatment of marl soil contaminated with heavy metals. It is recommended to conduct another study in future including analysis of the treated soil mixtures using XRD, SEM, and FTIR techniques to better understand the stabilization/solidification mechanism and its implications on the test results.

Association between e-cigarette use and myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: The popularity of e-cigarettes has risen dramatically over the last few years, particularly among the younger population. Although the use of combustible cigarettes has established evidence to be associated with the development of several adverse cardiopulmonary diseases, the investigations regarding the prospective long-term effects of e-cigarette use on the cardiovascular system have just begun. We set to investigate if there is an association between the history of MI and e-cigarette use among smokers and non-smokers? METHODS: The current review aims to assess the association of myocardial infarction with e-cigarette consumption. PubMed, Google Scholar, and Cochrane Central Register of Controlled Trials (CENTRAL) were queried up to October 2022 to identify articles assessing the incidence of myocardial infarction among e-cigarette users. Data were meta-analyzed using a random-effects model to derive odds ratios (OR) and 95% confidence intervals. RESULTS: Nine studies involving 984,764 patients were included. The mean age of e-cigarette smokers was less than the controls, and female participants dominated the sample size. E-cigarette users were associated with increased odds of MI than non-users [OR = 1.44; 95% CI (1.22, 1.74); P < 0.0001]. Dual users were also associated with increased odds of MI with large effect when compared to non-users [OR = 4.04; 95% CI (3.40, 4.81); P < 0.00001]. CONCLUSIONS: Dual use is associated with an increased risk of MI than e-cigarette use only. Similarly, dual and solely e-cigarette consumption patterns of nicotine delivery are at a higher risk of MI than non-smokers.

Are Academic Emergency Radiologists Systematically Disadvantaged Compared With Diagnostic Radiology Subspecialty Counterparts When It Comes to Promotion?

PURPOSE: The aim of this study was to assess academic rank differences between academic emergency and other subspecialty diagnostic radiologists. METHODS: Academic radiology departments likely containing emergency radiology divisions were identified by inclusively merging three lists: Doximity's top 20 radiology programs, the top 20 National Institutes of Health-ranked radiology departments, and all departments offering emergency radiology fellowships. Within departments, emergency radiologists (ERs) were identified via website review. Each was then matched on career length and gender to a same-institutional nonemergency diagnostic radiologist. RESULTS: Eleven of 36 institutions had no ERs or insufficient information for analysis. Among 283 emergency radiology faculty members from 25 institutions, 112 career length- and gender-matched pairs were included. Average career length was 16 years, and 23% were women. The mean h indices for ERs and non-ERs were 3.96 ± 5.60 and 12.81 ± 13.55, respectively (P < .0001). Non-ERs were twice as likely as ERs (0.21 versus 0.1) to be associate professors at h index < 5. Men had nearly 3 times the odds of advanced rank compared with women (odds ratio, 2.91; 95% confidence interval, 1.02-8.26; P = .045). Radiologists with at least one additional degree had nearly 3 times the odds of advancing rank (odds ratio, 2.75; 95% confidence interval, 1.02-7.40; P = .045). Each additional year of practice increased the odds of advancing rank by 14% (odds ratio, 1.14; 95% confidence interval, 1.08-1.21; P < .001). CONCLUSIONS: Academic ERs are less likely to achieve advanced rank compared with career length- and gender-matched non-ERs, and this persists even after adjusting for h index, suggesting that academic ERs are disadvantaged in current promotions systems. Longer term implications for staffing and pipeline development merit further attention as do parallels to other nonstandard subspecialties such as community radiology.

3D Printable Geopolymer Composites Reinforced with Carbon-Based Nanomaterials - A Review.

Three-dimensional (3D) geopolymer printing (3DGP) technology is a rapidly evolving digital fabrication method used in the construction industry. This technology offers significant benefits over 3D concrete printing in terms of energy saving and reduced carbon emissions, thus promoting sustainability. 3DGP technology is still evolving, and researchers are striving to develop high-performance printable materials and different methods to improve its robustness and efficiency. Carbon-based nanomaterials (CBNs) with beneficial properties have a wide range of applications in various fields, including as concrete/geopolymer systems in construction. This paper comprehensively reviews the research progress on carbon-based nanomaterials (CBNs) used to develop extrusion-based 3D geopolymer printing (3DGP) technology, including dispersion techniques, mixing methods, and the materials' performance. The rheological, mechanical, durability, and other characteristics of these materials are also examined. Furthermore, the existing research limitations and the prospects of using 3DGP technology to produce high-quality composite mixtures are critically evaluated.

Synthesis of waste limestone powder-based alkali-activated binder: experimental, optimization modeling, and eco-efficiency assessment.

More than half of the CO2 emissions during the manufacturing of ordinary Portland cement (OPC) occur due to the calcination of calcium carbonate in addition to burning of fossil fuel to power the process. Consequently, there is a concerted effort to decrease the carbon footprint associated with this process, by minimizing the use of OPC. In line with this trend, an attempt was made in the reported study to synthesize a novel alkali-activated binder using CaCO3-rich waste limestone powder (WLSP) as a precursor. Utilizing the Taguchi method, four important parameters were varied at three levels to optimize the alkali-activated mixture. Analysis of variance (ANOVA) of the obtained results was performed to assess the impact of each of the factors on the properties of the developed binder. To enhance the strength further, OPC was added as a partial replacement of WLSP. The binder was characterized using scanning electron microscopy. The results have indicated that alkaline activator to binder ratio, Na2SiO3 to NaOH ratio, and sand to binder ratio of 0.575, 1.57, and 2.5, respectively, were the optimum to obtain satisfactory strength and workability with a 13.7-M NaOH activator solution. The incorporation of a small quantity of OPC in the mixture remarkably improved the density and strength of the alkali-activated-WLSP binder. Pirssonite (CaCO3.Na2CO3.2H2O) and C/N-A-S-H were the dominant mineral phases formed in the developed binder, particularly in the ones alkali-activated WLSP/OPC. In addition, the eco-efficiency assessment revealed that the WLSP is a promising low-carbon binder that can be used in developing more sustainable alkali-activated binder. The results have shown that the WLSP can be potentially utilized in developing binder that can be potentially used in the structural applications.

Electrical Stability and Piezoresistive Sensing Performance of High Strain-Range Ultra-Stretchable CNT-Embedded Sensors.

Highly flexible and stretchable sensors are becoming increasingly widespread due to their versatile applicability in human/robot monitoring sensors. Conductive polymeric composites have been regarded as potential candidates for such sensors, and carbon nanotubes (CNTs) are widely used to fabricate such composites. In the present study, CNT-embedded high flexible sensors were fabricated using a facile three-roll milling method, which mitigates the drawbacks of the conventional fabrication methods. CNTs content varied between 0.5 and 4.0 wt.%, and the percolation threshold range was obtained via conductivity/resistivity values of the fabricated sensors. Following this, the electrical stability of the sensors was examined against the various DC and AC signals. Furthermore, the fabricated sensors were stretched up to 500% strain, and their sensitivity against varying strain amplitudes was investigated in terms of the change in resistance and gauge factors. Lastly, the fabricated sensors were applied to human fingers for monitoring finger bending and releasing motions to validate their potential applications. The experimental results indicated that these sensors have a percolation threshold of around 2% CNTs content, and the sensors fabricated with 2 to 4% CNTs content showed measurable resistance changes against the applied strain amplitudes of 50-500%. Among these sensors, the sensor with 2% CNTs content showed the highest sensitivity in the studied strain range, exhibiting a resistance change and gauge factor of about 90% and 1.79 against 50% strain amplitude and about 18,500% and 37.07 against 500% strain amplitude, respectively. All these sensors also showed high sensitivity for finger motion detection, showing a resistance change of between 22 and 69%.

Facile Synthesis of Sprayed CNTs Layer-Embedded Stretchable Sensors with Controllable Sensitivity.

Flexible electronic devices have gained significant interest due to their different potential applications. Herein, we report highly flexible, stretchable, and sensitive sensors made of sprayed CNT layer, sandwiched between two polymer layers. A facile fabrication process was employed in which the CNT solution was directly sprayed onto a patterned bottom polymer layer, above which a second polymer layer was casted to get a sandwiched composite structure. Varying amounts of CNT solution (i.e., 10, 25, 40, 70, and 100 mL) were sprayed to get conductive CNT layers of different thicknesses/densities. The physical characteristics of the conductive CNT layers were studied through SEM and optical images. The starting electrical resistance values (without strain) as well as the changes in electrical resistance against human body motions were monitored. The synthesized samples exhibited good response against finger and wrist bending. The conductivity of the samples increased with increase of CNT solution volume while the sensitivity followed the inverse relation, suggesting that the sensors with controlled sensitivity could be fabricated for targeted strain ranges using the proposed method.

Integrating High-Fidelity Simulation into a Medical Cardiovascular Physiology Curriculum.

INTRODUCTION: The challenges of transitioning from basic sciences to clerkships are well identified in medical education. High-fidelity simulations, which have established a track record of improving clinical reasoning and clinical skills, have been proposed as a viable approach to bridge the gap between basic sciences and clerkships. However, little is known about the results of using simulation to address the gap. METHODS: In 2018, Morehouse School of Medicine enhanced the first-year cardiovascular physiology curriculum by integrating the high-fidelity simulation iStan into the cardiovascular physiology curriculum, with the purpose of early clinical exposure, cardiovascular concept mastery, and increased clinical associations. The integration included three structural design elements: (a) simulated clinical case introduction; (b) simulated clinical case development; and (c) student-led clinical case study. RESULTS: The first-year medical (MD1) students' cardiovascular physiology learning outcomes have significantly improved compared to the last two cohorts of MD1 students, and the students' test-taking time was significantly reduced compared to the performance of the last two counterpart cohorts. Students reported increased engagement in the simulation-enhanced cardiovascular physiology curriculum. CONCLUSION: The findings provide preliminary evidence to suggest that the structural integration of high-fidelity simulation in the cardiovascular physiology curriculum proved successful in terms of students' learning experience and learning outcomes. The three central elements of high-fidelity simulation integration can inform future endeavor as a structural solution to effectively bridge the gaps between basic science concepts and clinical reasoning by using high-fidelity simulations.

The Effects of Temperature on the Hydrothermal Synthesis of Hydroxyapatite-Zeolite Using Blast Furnace Slag.

Blast furnace slag, an industrial by-product, is emerging as a potential raw material to synthesize hydroxyapatite and zeolite. In this study, the effects of temperature on the hydrothermal synthesis of hydroxyapatite-zeolite from blast furnace slag were investigated. Specimens were synthesized at different temperatures (room temperature, 50, 90, 120, or 150 °C). The synthesized specimens were analyzed qualitatively and quantitatively via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), BET/BJH, and scanning electron microscopy/energy dispersive using X-ray analysis (SEM/EDX). It was found that the hydroxyapatite phase was synthesized at all the reaction temperatures, while faujasite type zeolite appeared in the specimens synthesized at 90 and 120 °C. Moreover, faujasite was replaced by hydroxysodalite in the specimens synthesized at 150 °C. Additionally, the crystals of the hydroxyapatite tended to become larger and total crystallinity increased as the reaction temperature increased.

Synthesis of geopolymer-supported zeolites via robust one-step method and their adsorption potential.

The present study proposes a robust one-step hydrothermal treatment method for synthesis of high strength geopolymer-supported zeolites utilizing industrial by-products (fly ash and blast furnace slag), which can be potentially used as bulk-type solid adsorbents. The results revealed that the geopolymer-supported zeolites, possessing distinct strengths, zeolite phases (Na-P1, Na-chabazite, and analcime) and pore features depending on the mix design and synthesis conditions, can be easily synthesized employing the proposed one-step method. The geopolymer-supported zeolites exhibited the characteristics of mesoporous materials which are typically desired for commercial adsorbents. The maximum adsorption capacity for Pb2+ was found to be about 37.9 mg/g which is relatively higher than the other bulk-type adsorbents reported for Pb2+ to date. Since industrial by-products are used for synthesis of these materials, it will help in reducing the environmental hazards associated with the permanent disposal of such by-products, with an added advantage that these bulk-type solid adsorbents can be easily retrieved after use unlike granular adsorbents.