Heavy metal accumulation in soil has been rapidly increased due to various natural processes and anthropogenic (industrial) activities. As heavy metals are non-biodegradable, they persist in the ...environment, have potential to enter the food chain through crop plants, and eventually may accumulate in the human body through biomagnification. Owing to their toxic nature, heavy metal contamination has posed a serious threat to human health and the ecosystem. Therefore, remediation of land contamination is of paramount importance. Phytoremediation is an eco-friendly approach that could be a successful mitigation measure to revegetate heavy metal-polluted soil in a cost-effective way. To improve the efficiency of phytoremediation, a better understanding of the mechanisms underlying heavy metal accumulation and tolerance in plant is indispensable. In this review, we describe the mechanisms of how heavy metals are taken up, translocated, and detoxified in plants. We focus on the strategies applied to improve the efficiency of phytostabilization and phytoextraction, including the application of genetic engineering, microbe-assisted and chelate-assisted approaches.
Enzymes as Active Matter Ghosh, Subhadip; Somasundar, Ambika; Sen, Ayusman
Annual review of condensed matter physics,
03/2021, Letnik:
12, Številka:
1
Journal Article
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Nature has designed multifaceted cellular structures to support life. Cells contain a vast array of enzymes that collectively perform essential tasks by harnessing energy from chemical reactions. ...Despite the complexity, intra- and intercellular motility at low Reynolds numbers remain the epicenter of life. In the past decade, detailed investigations on enzymes that are freely dispersed in solution have revealed concentration-dependent enhanced diffusion and chemotactic behavior during catalysis. Theoretical calculations and simulations have determined the magnitude of the impulsive force per turnover; however, an unequivocal consensus regarding the mechanism of enhanced diffusion has not been reached. Furthermore, this mechanical force can be transferred from the active enzymes to inert particles or surrounding fluid, thereby providing a platform for the design of biomimetic systems. Understanding the factors governing enzyme motion would help us to understand organization principles for dissipative self-assembly and the fabrication of molecular machines. The purpose of this article is to review the different classes of enzyme motility and discuss the possible mechanisms as gleaned from experimental observations and theoretical modeling. Finally, we focus on the relevance of enzyme motion in biology and its role in future applications.
Lateral organization in the plane of the plasma membrane is an important driver of biological processes. The past dozen years have seen increasing experimental support for the notion that lipid ...organization plays an important role in modulating this heterogeneity. Various biophysical mechanisms rooted in the concept of liquid-liquid phase separation have been proposed to explain diverse experimental observations of heterogeneity in model and cell membranes with distinct but overlapping applicability. In this review, we focus on the evidence for and the consequences of the hypothesis that the plasma membrane is poised near an equilibrium miscibility critical point. Critical phenomena explain certain features of the heterogeneity observed in cells and model systems but also go beyond heterogeneity to predict other interesting phenomena, including responses to perturbations in membrane composition.
To address the concern of material chemists over the issue of stability and photoluminescent (PL) characteristics of Cu nanoclusters (NCs), herein we present an efficient protocol discussing PL Cu ...NCs (Cu/HSA) having blue emission and high photostability. These PL NCs were illustrated as efficient probes for Förster resonance energy transfer (FRET) with a compatible fluorophore (Coumarin 153). Our spectroscopic results were well complemented by our molecular docking calculations, which also favored our proposed mechanism for Cu NC formation. The beneficial aspect and uniqueness of these nontoxic Cu/HSA NCs highlights their temperature-dependent PL reversibility as well as the reversible FRET with Coumarin 153, which enables them to be used as a nanothermometer and a PL marker for sensitive biological samples.
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This review is focused on the sustainable management of harvested water hyacinth (WH) via thermochemical conversion to carbonaceous materials (CMs), biofuels, and chemicals for energy ...and environmental applications. One of the major challenges in thermochemical conversion is to guarantee the phytoremediation performance of biochar and the energy conversion efficiency in biowaste-to-energy processes. Thus, a circular sustainable approach is proposed to improve the biochar and energy production. The co-conversion process can enhance the syngas, heat, and energy productions with high-quality products. The produced biochar should be economically feasible and comparable to available commercial carbon products. The removal and control of heavy and transition metals are essential for the safe implementation and management of WH biochar. CMs derived from biochar are of interest in wastewater treatment, air purification, and construction. It is important to control the size, shape, and chemical compositions of the CM particles for higher-value products like catalyst, adsorbent or conductor.
Automated vehicles are a revolutionary step in mobility, providing a safe and convenient riding experience while keeping the human-driving task minimal to none. Therefore, these intelligent vehicles ...are equipped with sophisticated perception sensors (e.g., cameras and radars), high-performance computers, artificial intelligence (AI)-driven algorithms, and connectivity with other internet-of-things (IoT) devices. This makes autonomous vehicles (AVs) a special kind of cyber-physical system (CPS) that is moving at speed in highly interactive and dynamic environments (e.g., public roads). Thus, AV is a potential target for cyber attackers to weaponize, compromising safety and mobility on the road. The first step in addressing this problem is to have a robust threat modeling framework that can address the evolving cyber-physical threats, especially to AV applications. In this regard, two areas are studied in this paper: the common practice of threat modeling in automotive and the ISO/SAE 21434 standard, and sensors and machine learning (ML) algorithms for AV perception systems and potential cyber-physical attacks. A comparative threat analysis for an AV perception system with the ISO/SAE 21434 standard and a system-theoretic process analysis for security (STPA-Sec) approach is also demonstrated in this paper. Based on the analysis, this paper proposes a robust threat analysis and risk assessment framework with mathematical modeling to identify cyber-physical threats to AV perception systems that are critical for the driving behaviors and complex interactions of AVs in their operational design domain.
The present computational study using B3LYP functional and 6-31+G(d) basis set has been accomplished to investigate the mechanism of the inverse demand Diels-Alder reaction between pyridyl imine and ...propene. The highly charged dicationic superelectrophilic diene with exceptionally low-lying LUMO makes the cycloaddition reaction with propene more favorable by significantly lowering the activation energy. The Wiberg bond indices are calculated in accordance with the formation and breaking processes of bonds. The synchronicity concept is also utilized to explain the global nature of the reaction. A potential outcome of this investigation is the utilization of propene as a
C
2
building block in the industry.
Graphical abstract
The solvation dynamics of three coumarin dyes with widely varying polarities were studied in acetonitrile–water (ACN–H2O) mixtures across the entire composition range. At low ACN concentrations ACN ...mole fractions (XACN)≤0.1, the solvation dynamics are fast (<40 ps), indicating a nearly homogeneous environment. This fast region is followed by a sudden retardation of the average solvation time (230–1120 ps) at higher ACN concentrations (XACN≈0.2), thus indicating the onset of nonideality within the mixture that continues until XACN≈0.8. This nonideality regime (XACN≈0.2–0.8) comprises of multiple dye‐dependent anomalous regions. At very high ACN concentrations (XACN≈0.8–1), the ACN–H2O mixtures regain homogeneity, with faster solvation times. The source of the inherent nonideality of the ACN–H2O mixtures is a subject of debate. However, a careful examination of the widths of time‐resolved emission spectra shows that the origin of the slow dynamics may be due to the diffusion of polar solvent molecules into the first solvation shell of the excited coumarin dipole.
What a mix! The solvation dynamics of three coumarin dyes with various polarities were studied in acetonitrile–water (ACN–H2O) mixtures. Mixtures with ACN mole fractions between 0.2 and 0.8 show unexpectedly slow solvation times. The source of this nonideality is studied by time‐resolved emission spectroscopy and is revealed to be the diffusion of polar solvent molecules into the first solvation shell of the excited coumarin dipole.
We study the microstructures in the drying droplets of gelatinized starch solutions on a flat substrate. Cryogenic scanning electron microscopy studies on the vertical cross-section of these drying ...droplets for the first time reveal a relatively thinner solid elastic crust of uniform thickness at the free surface, an intermediate mesh region below the crust, and an inner core of a cellular network structure made of starch nanoparticles. We find that the deposited circular films formed after drying are birefringent and azimuthally symmetric with a dimple at their center. We propose that the dimple formation in our sample occurs due to the evaporation-induced stress on the gel network structure in the drying droplet. The polarizing optical microscopic studies show that these films are optically uniaxial at their center and increasingly biaxial away from the center.
The import demand for energy resources, including liquefied natural gas (LNG), has been steadily increasing in the Asia-Pacific region. Australia, the Middle East (Qatar), the Russian Federation, and ...the U.S. are the major players who compete strategically to capture this ever-growing market for LNG. The objective of this paper is to examine the potential for Canada’s entry into this market as another LNG exporter and what impact that can have on the existing suppliers. Using a game-theoretic LNG export competition model, we explore the conditions under which Canada can make a profitable entry. We also investigate the effect of Canada’s entry on the profitability of the four incumbent exporters. Employing a multi-leader Stackelberg model, we found that Canada’s entry could be a Pareto superior outcome under certain conditions because it benefits all competing firms and consumers. Further, Canada’s entry into the LNG export market always helps the low-cost incumbent firms by increasing their output and profit. However, the high-cost incumbent firms’ output falls, while their profit may increase or decrease depending on the unit cost and market size parameters. With differential export costs between Canada and the U.S., the latter has an incentive to act strategically to affect the entrance of the former.
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