The presence of ferroelectric polarization in 2D materials is extremely rare due to the effect of the surface depolarizing field. Here, we use first-principles calculations to show the largest ...out-of-plane polarization observed in a monolayer in functionalized MXenes (Sc2CO2). The switching of polarization in this new class of ferroelectric materials occurs through a previously unknown intermediate antiferroelectric structure, thus establishing three states for applications in low-dimensional nonvolatile memory. We show that the armchair domain interface acts as an 1D metallic nanowire separating two insulating domains. In the case of the van der Waals bilayer we observe, interestingly, the presence of an ultrathin 2D electron/hole gas (2DEG) on the top/bottom layers, respectively, due to the redistrubution of charge carriers. The 2DEG is nondegenerate due to spin–orbit coupling, thus paving the way for spin–orbitronic devices. The coexistence of ferroelectricity, antiferroelectricity, 2DEG, and spin–orbit splitting in this system suggests that such 2D polar materials possess high potential for device application in a multitude of fields ranging from nanoelectronics to photovoltaics.
•Studied three different roller arrangements in backward flow-forming via user defined sub-routines in a FE framework.•Created 3D fracture strain maps for stress triaxiality/Lode parameter and stress ...triaxiality/thermal softening factor.•Highligted the limitations of the wedge flow-forming test to evaluate the flow-formability.•Characterized the fracture locus to evaluate the flow-formability.•Developed a summary chart correlating the process parameters and flow-formability.
A shear modified coupled damage criterion based on continuum damage mechanics has been proposed in this study. Khan-Huang-Liang (KHL) model is implemented to predict the constitutive behavior of Ti-6Al-4 V (Ti64) alloy. A VUMAT subroutine has been developed for the damage model using a stress integration algorithm. Multiple simulations with tensile, compression and shear geometries are carried out in Abaqus/Explicit and compared with the experimental results to benchmark the hardening and damage criteria. The flow forming process involves a complex triaxial state of stress. This study is focused on understanding the contribution of triaxiality and shear during deformation and fracture in the flow-forming process with different roller arrangements. For this purpose, the flow-forming processes with three different roller arrangements, single roller, three roller, and wedge roller, are modeled, and their formability is compared by implementing a shear modified continuous damage model. A single roller flow-forming (SRF) arrangement undergoes high triaxiality due to excessive material displacement by the roller and high strain gradient in the axial direction. The fracture occurs near the interface of the reducing and thinning zone. The three-rollers flow-forming (TRF) provided maximum reduction till fracture and material fails due to excessive strain in the thinning zone at a relatively large percentage reduction. The wedge roller flow-forming (WRF) suffers a lack of uniform material softening, and fracture occurs near the interface of the uplift and reducing zone under high triaxiality. 3-D process maps have been developed for predicting fracture strain as a function of stress triaxiality/Lode parameter and stress triaxiality/thermal softening factor (E/σ¯2). Finally, a summary chart correlating the parameters, and flow-formability has been developed.
Main conclusion
While transgenic technology has heralded a new era in crop improvement, several concerns have precluded their widespread acceptance. Alternative technologies, such as cisgenesis and ...genome-editing may address many of such issues and facilitate the development of genetically engineered crop varieties with multiple favourable traits.
Genetic engineering and plant transformation have played a pivotal role in crop improvement via introducing beneficial foreign gene(s) or silencing the expression of endogenous gene(s) in crop plants. Genetically modified crops possess one or more useful traits, such as, herbicide tolerance, insect resistance, abiotic stress tolerance, disease resistance, and nutritional improvement. To date, nearly 525 different transgenic events in 32 crops have been approved for cultivation in different parts of the world. The adoption of transgenic technology has been shown to increase crop yields, reduce pesticide and insecticide use, reduce CO
2
emissions, and decrease the cost of crop production. However, widespread adoption of transgenic crops carrying foreign genes faces roadblocks due to concerns of potential toxicity and allergenicity to human beings, potential environmental risks, such as chances of gene flow, adverse effects on non-target organisms, evolution of resistance in weeds and insects etc. These concerns have prompted the adoption of alternative technologies like cisgenesis, intragenesis, and most recently, genome editing. Some of these alternative technologies can be utilized to develop crop plants that are free from any foreign gene hence, it is expected that such crops might achieve higher consumer acceptance as compared to the transgenic crops and would get faster regulatory approvals. In this review, we present a comprehensive update on the current status of the genetically modified (GM) crops under cultivation. We also discuss the issues affecting widespread adoption of transgenic GM crops and comment upon the recent tools and techniques developed to address some of these concerns.
Overview of Fungal Lipase: A Review Singh, Abhishek Kumar; Mukhopadhyay, Mausumi
Applied biochemistry and biotechnology,
2012/1, Letnik:
166, Številka:
2
Journal Article
Recenzirano
Lipases (triacylglycerolacyl hydrolases, EC3.1.1.3) are class of enzymes which catalyze the hydrolysis of long-chain triglycerides. In this review paper, an overview regarding the fungal lipase ...production, purification, and application is discussed. The review describes various industrial applications of lipase in pulp and paper, food, detergent, and textile industries. Some important lipase-producing fungal genera include
Aspergillus
,
Penicillium
,
Rhizopus
,
Candida
, etc. Current fermentation process techniques such as batch, fed-batch, and continuous mode of lipase production in submerged and solid-state fermentations are discussed in details. The purification of lipase by hydrophobic interaction chromatography is also discussed. The development of mathematical models applied to lipase production is discussed with special emphasis on lipase engineering.
A sustainable solution to biomass burning by converting agricultural residues into biochar was provided. Biochar application was investigated to improve soil fertility, sequester carbon, and increase ...crop production. Rice husk (RHBC) and corn stover (CSBC) biochars were obtained by slow pyrolysis at 650° and 550 °C, respectively. RHBC and CSBC were characterized (SEM, SEM-EDX, TEM, FTIR, XRD, elemental analyses, and S
BET
). Unpyrolyzed husks and stover were also used for soil amendments and compared to biochars in different proportions under a controlled incubation environment over 107 days. Fertilizers were not applied. An increase in water holding capacity, total organic carbon, cation exchange capacity, and a decrease in soil CO
2
emission were observed after biochar application to soil
versus
the application of the parent husks or stover. These biochars improved soil fertility and enhanced eggplant crop growth (height, leaf number, fresh and dry weight). In addition, carbon mitigation was achieved because the biochar remained stable in the soil achieving longer term carbon sequestration. Both chars can be used for carbon sequestration and soil amendments.
•Establishing structure-property linkages in Ni- and Co- based superalloys.•Advanced image processing techniques employed to segregate different phases of superalloys with high accuracy.•Feature ...generation from scanning electron microscope images using statically derived n-point correlations.•Development of highly accurate machine learning based models to predict Vickers hardness of superalloys using compositions and n-point correlations.•Identification of important elements and microstructural characteristics for enhancement of Vickers hardness.
Display omitted
Superalloys constitute an important class of materials that are heavily employed in turbines of aircraft engines and power plants. Vickers hardness is an important mechanical property for selection of a material. In this work, we develop an alternate approach, which uses the microstructures to estimate the hardness of a Co- and Ni- based superalloys. Advanced image processing techniques coupled with data-driven machine learning (ML) are used to predict the Vickers hardness of these superalloys. Complex image derived properties such as 2-point correlations and compositions of superalloys are utilized as a feature to develop highly accurate ML model. The ML model trained through Gaussian process regression (GPR) using microstructure and compositional features show unprecedented accuracy with root mean square error (RMSE) of 0.14 and R2 of 0.98. Further analysis of the model is done to establish a relationship between the Vickers hardness with microstructural and compositional parameters. Addition of certain compounds such as iron and titanium can in general lead to increase in Vickers hardness, while addition of elements such as aluminium, tantalum and hafnium negatively affect the Vickers hardness. Most importantly, the developed ML model is trained on experimental data, as opposed to simulated data, making our approach directly applicable for accurate prediction of Vickers hardness.
Abstract
The revolutionary 5G cellular systems represent a breakthrough in the communication network design to provide a single platform for enabling enhanced broadband communications, virtual ...reality, autonomous driving, and the internet of everything. However, the ongoing massive deployment of 5G networks has unveiled inherent limitations that have stimulated the demand for innovative technologies with a vision toward 6G communications. Terahertz (0.1-10 THz) technology has been identified as a critical enabler for 6G communications with the prospect of massive capacity and connectivity. Nonetheless, existing terahertz on-chip communication devices suffer from crosstalk, scattering losses, limited data speed, and insufficient tunability. Here, we demonstrate a new class of phototunable, on-chip topological terahertz devices consisting of a broadband single-channel 160 Gbit/s communication link and a silicon Valley Photonic Crystal based demultiplexer. The optically controllable demultiplexing of two different carriers modulated signals without crosstalk is enabled by the topological protection and a critically coupled high-quality (
Q
) cavity. As a proof of concept, we demultiplexed high spectral efficiency 40 Gbit/s signals and demonstrated real-time streaming of uncompressed high-definition (HD) video (1.5 Gbit/s) using the topological photonic chip. Phototunable silicon topological photonics will augment complementary metal oxide semiconductor (CMOS) compatible terahertz technologies, vital for accelerating the development of futuristic 6G and 7G communication era driving the real-time terabits per second wireless connectivity for network sensing, holographic communication, and cognitive internet of everything.
The strikingly contrasting optical properties of various phases of chalcogenide phase change materials (PCM) has recently led to the development of novel photonic devices such as all‐optical non‐von ...Neumann memory, nanopixel displays, color rendering, and reconfigurable nanoplasmonics. However, the exploration of chalcogenide photonics is currently limited to optical and infrared frequencies. Here, a phase change material integrated terahertz metamaterial for multilevel nonvolatile resonance switching with spatial and temporal selectivity is demonstrated. By controlling the crystalline proportion of the PCM film, multilevel, non‐volatile, terahertz resonance switching states with long retention time at zero hold power are realized. Spatially selective reconfiguration at sub‐metamaterial scale is shown by delivering electrical stimulus locally through designer interconnect architecture. The PCM metamaterial also features ultrafast optical modulation of terahertz resonances with tunable switching speed based on the crystalline order of the PCM film. The multilevel nonvolatile, spatially selective, and temporally tunable PCM metamaterial will provide a pathway toward development of novel and disruptive terahertz technologies including spatio‐temporal terahertz modulators for high speed wireless communication, neuromorphic photonics, and machine‐learning metamaterials.
A chalcogenide phase‐change material, germanium antimony telluride, integrated with a terahertz metamaterial, shows multilevel nonvolatile resonance switching states, electrically controlled spatial terahertz modulation, and tunable ultrafast resonance modulation under optical stimulus. The unique properties of GST open up a new paradigm of multidimensional manipulation of terahertz waves across spectral, spatial and temporal domains.
This article proposes an interleaved, highly efficient, high-gain modified boost converter. High-gain and transformerless converter operation makes the converter suitable for integrating photovoltaic ...(PV) power to standalone dc microgrid. A coupled inductor is used with two diodes and one switch per phase with a common clamping capacitor to modify the conventional boost converter. The common clamping capacitor and the coupled inductor reduce the converter's component count and size; thus, high efficiency is achieved at a low cost. The proposed converter achieves a high step-up gain and low voltage stress on switches. Interleaved converters are deemed ideal for PV power extraction as they exhibit low input current ripple. A 900-W prototype of a two-phase interleaved modified boost converter is designed and developed to verify the working principle of the converter and performance testing.
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