Phytoremediation of heavy metals: A green technology

The environment has been contaminated with organic and inorganic pollutants. Organic pollutants are largely anthropogenic and are introduced to the environment in many ways. Soil contamination with toxic metals, such as Cd, Pb, Cr, Zn, Ni and Cu, as a result of worldwide industrialization has increased noticeably within the past few years. There are some conventional remediation technologies to clean polluted areas, specifically soils contaminated with metals. In spite of being efficient, these methods are expensive, time consuming, and environmentally devastating. Recently, phytoremediation as a cost effective and environmentally friendly technology has been developed by scientists and engineers in which biomass/microorganisms or live plants are used to remediate the polluted areas. It can be categorized into various applications, including phytofiltration, phytostabilization, phytoextraction, and phytodegradation. A brief review of phytoremediation of soils contaminated with heavy metals has been complied to provide an extensive applicability of this green technology.Key words: Phytoremediation, heavy metals, soil pollution, toxicity

Exploring User Needs in the Development of a Virtual Reality-Based Advanced Life Support Training Platform: Exploratory Usability Study

Background: Traditional methods of delivering Advanced Life Support (ALS) training and reaccreditation are resource-intensive and costly. Interactive simulations and gameplay using virtual reality (VR) technology can complement traditional training processes as a cost-effective, engaging, and flexible training tool. Objective: This exploratory study aimed to determine the specific user needs of clinicians engaging with a new interactive VR ALS simulation (ALS-SimVR) application to inform the ongoing development of such training platforms. Methods: Semistructured interviews were conducted with experienced clinicians (n=10, median age=40.9 years) following a single playthrough of the application. All clinicians have been directly involved in the delivery of ALS training in both clinical and educational settings (median years of ALS experience=12.4; all had minimal or no VR experience). Interviews were supplemented with an assessment of usability (using heuristic evaluation) and presence. Results: The ALS-SimVR training app was well received. Thematic analysis of the interviews revealed five main areas of user needs that can inform future design efforts for creating engaging VR training apps: affordances, agency, diverse input modalities, mental models, and advanced roles. Conclusions: This study was conducted to identify the needs of clinicians engaging with ALS-SimVR. However, our findings revealed broader design considerations that will be crucial in guiding future work in this area. Although aligning the training scenarios with accepted teaching algorithms is important, our findings reveal that improving user experience and engagement requires careful attention to technology-specific issues such as input modalities

Evaluation of heavy metal uptake and translocation by Acacia mangium as a phytoremediator of copper contaminated soil

Many organic and inorganic pollutants, including heavy metals are being transported and mixed with the cultivated soils and water. Heavy metals are the most dangerous pollutants as they are nondegradable and accumulate and become toxic to plants and animals. An experiment was conducted in the glasshouse to evaluate the potential of Acacia mangium as a phytoremediator to absorb heavy metals from contaminated soils. A. mangium seedlings were planted in the growth media (soil + different levels of copper). The different levels of Cu were: T0 (control, soil), T1 (50 ppm Cu), T2 (100 ppm Cu), T3 (200 ppm Cu), T4 (300 ppm Cu) and T5 (400 ppm Cu). The highest growth performance such as basal diameter, height and number of leaves was in T1. The highest biomass was recorded in T1. Highest accumulation of Cu (93.55 ppm) and Zn (79.13 ppm) were recorded in T5 while Cd (8.88 ppm) in T3. Cu was highly concentrated in the roots, Cd was accumulated in the leaves and roots, whereas, Zn was in stems and leaves. A. mangium showed high translocation factor (TF) and low bioconcentration factor (BCF) values in soil at higher metal concentrations as well as it was able to tolerate and accumulate high concentrations of Cd, Cu and Zn. It may be concluded that this species can be a good efficient phtyoremediator for heavy metals (Cd, Cu and Zn) contaminated soils to mitigate soil pollution.Key words: Heavy metals, phytoremediation, bioaccumulation capacity

Evaluation of the Capability of Carbon Dioxide Greenhouse Gas Absorption Using Nano Bio-Activated Carbon of Crataegus Sanguinea Core

BACKGROUND AND OBJECTIVE: Considerable increase in carbon dioxide gas in the Earth's atmosphere has caused several problems such as increasing the temperature of the earth, droughts and sudden changes in the climate. The purpose of this study was to evaluate the capability of carbon dioxide as greenhouse gas absorption using activated nanobiocarbon from the Crataegus Sanguinea core. METHODS: In this experimental study, the carbon dioxide gas penetration time in three subgroups with pressure (5,10,15 bars), flow (5,10,15 ml/min) and temperatures (20,30,60 °C) at concentrations of 0 to 1 gr / ml through a carbon dioxide gas capsule in a fixed bed column filled with 2 g of adsorbent synthesized by a carbon dioxide gas sensor. The synthesized nano-biocarbon adsorbent from the Crataegus Sanguinea Core was pyrolysed at a temperature of 300 ° C and activated at 600 °C. The research data were examined with pseudo -first-order and pseudo-second-order models. FINDINGS: Significant increase in gas infiltration time was observed at 15 bars pressure (86.71±0.09 min, p0.98 on empirical data from absorption. CONCLUSION: The results of the study showed that increasing pressure and decreasing temperature and flow increase the time of carbon dioxide penetration onto synthesized adsorbent

Numerical investigation of pool boiling on a staggered tube bundle for different working fluids

In the present work, a numerical approach is proposed to simulate two phase pool boiling on a staggered tube bundle. The simulations are carried out using the Eulerian–Eulerian framework for two phase flows, accounting for the nucleate pool boiling on the surface of the tube bundle. A favourable agreement was reported between the numerical results and previously published experimental data for pool boiling heat transfer. The numerical results are presented for four working fluids, including water, ethanol, R134a and R22, each at three different saturation temperatures. The effect of saturation temperature, the variation in the heat transfer within the tube bundle and the effect of the working fluid are fully addressed.http://www.elsevier.com/locate/ijmulflow2019-07-01hj2018Mechanical and Aeronautical Engineerin

Effects of vibration on pool boiling heat transfer from a vertically aligned array of heated tubes

In the present study, the use of mechanical vibration for the enhancement of pool boiling heat transfer is evaluated theoretically. For this purpose, a vertical array of vibrating circular tubes is considered. The array is submerged in a pool of water under atmospheric conditions and electrically heated for boiling to occur on the tube surfaces. To model this phase-change phenomenon, a two-fluid formulation is employed and accompanied by the Rensselaer Polytechnic Institute (RPI) model to estimate the boiling heat flux on a solid surface. A comprehensive parametric study is undertaken to investigate the effects of the amplitude and frequency of vibration, the magnitude of the heat flux, and the pitch-to-diameter ratio of the array on pool boiling heat transfer in the presence of mechanical vibration. An increase of up to 90% in the heat transfer rate is achieved within the simulated operating conditions.http://www.elsevier.com/locate/ijmulflow2020-09-01hj2019Mechanical and Aeronautical Engineerin

Numerical simulation of pool boiling on smooth, vertically aligned tandem tubes

In the present study, a numerical simulation of atmospheric pool boiling on tandem, inclined, electrically heated circular tubes is performed. An Eulerian-Eulerian description of the two-phase flow formulations is adopted together with a Rensselaer Polytechnic Institute (RPI) nucleate boiling model to account for the heat and mass transfer in the boiling phenomenon. The pool boiling is studied in the range of 0–100 kW/m2 for the heat flux and for inclination angles of 0–90°. The effect of the boiling liquid characteristics on the key features of the pool boiling phenomenon is studied, as well as using water, ethanol and FC-72 as the working fluid. The numerical results are validated against available experimental measurements, and the effects of the inclination angle, working fluid and magnitude of the heat flux are explored thoroughly.http://www.elsevier.com/locate/ijts2019-10-01hj2018Mechanical and Aeronautical Engineerin

CFD-based shape optimization of steam turbine blade cascade in transonic two phase flows

In this study CFD-based shape optimization of a 3D nozzle and a 2D turbine blade cascade is undertaken in the presence of non-equilibrium condensation within the considered flow channels. A two-fluid formulation is used for the simulation of unsteady, turbulent, supersonic and compressible flow of wet steam accounting for relevant phase interaction between nucleated liquid droplets and continuous vapor phase. An in-house CFD code is developed to solve the governing equations of the two phase flow and was validated against available experimental data. Optimization is carried out in respect to various objective functions. It is shown that nucleation rate and maximum droplet radius are the best suited target functions for reducing thermodynamic and aerodynamic losses caused by the spontaneous nucleation. The maximum increase of 2.1% in turbine blade efficiency is achieved through shape optimization process.http://www.journals.elsevier.com/applied-thermal-engineering/2018-02-28hb2017Mechanical and Aeronautical Engineerin

Crystal Structure of the Minimalist Max-E47 Protein Chimera

Max-E47 is a protein chimera generated from the fusion of the DNA-binding basic region of Max and the dimerization region of E47, both members of the basic region/helix-loop-helix (bHLH) superfamily of transcription factors. Like native Max, Max-E47 binds with high affinity and specificity to the E-box site, 5′-CACGTG, both in vivo and in vitro. We have determined the crystal structure of Max-E47 at 1.7 Å resolution, and found that it associates to form a well-structured dimer even in the absence of its cognate DNA. Analytical ultracentrifugation confirms that Max-E47 is dimeric even at low micromolar concentrations, indicating that the Max-E47 dimer is stable in the absence of DNA. Circular dichroism analysis demonstrates that both non-specific DNA and the E-box site induce similar levels of helical secondary structure in Max-E47. These results suggest that Max-E47 may bind to the E-box following the two-step mechanism proposed for other bHLH proteins. In this mechanism, a rapid step where protein binds to DNA without sequence specificity is followed by a slow step where specific protein:DNA interactions are fine-tuned, leading to sequence-specific recognition. Collectively, these results show that the designed Max-E47 protein chimera behaves both structurally and functionally like its native counterparts