Bulk Quantities Research Articles

Latent Nucleophilic Carbenes.

Using DFT and ab initio calculations, we demonstrate that noncyclic formamidines can undergo thermal rearrangement into their isomeric aminocarbenes under rather mild conditions. We synthesized the silylformamidine, for which the lowest activation energy in this process was predicted. Experimental studies proved it to serve as a very reactive nucleophilic carbene. The reactions with acetylenes, benzenes, and trifluoromethane proceeded via insertion into sp, sp2, and sp3 CH bonds. The carbene also reacted with the functional groups, such as CHO, COR, and CN at double or triple bonds, displaying high mobility of the trimethylsilyl group. The obtained silylformamidine can be considered as a latent nucleophilic carbene. It can be prepared in bulk quantities, stored, and used when the need arises. Calculation results predict similar behavior for some other silylated formamidines and related compounds.

An Unsupervised Fault Detection and Classification Scheme of Power Converters

Faults in a power electronic component (inverter, converter, modules, etc.) can severely affect the reliability, efficiency, as well as the security of the entire power conversion system if not detected by early warning. The inverters that are the most common power converters in the industry are widely used in power supplies, energy management systems, motor control, etc. Nevertheless, due to the diverse operating conditions and complexity of the drive system, the power converters employed in drive systems are more prone to faults. Moreover, collecting a large amount of labeled data in the nonlinear industrial environment is not practical, and this imposes challenges to the prior approaches as they claim a bulk amount of labeled data to be generalized. Taking this as a research challenge, this letter proposes a sparse-autoencoder-based unsupervised power converter fault detection and classification scheme that learns the fault-oriented features from the unlabeled dataset. In addition, the precision and sensitivity study are conducted in this letter to justify whether the proposed scheme delivers a reliable performance or not.

Calibration-free laser-based spectroscopic study of Sn-based alloys

The elemental quantification of liquid metal divertor (LMD) surface is important for understanding the material erosion, migration, re-deposition, and fuel retention in Plasma-Facing Components (PFCs). Currently, LMD are attractive candidates for the short- and long-term operation of fusion devices like DEMO. Liquid metals can provide self-cooling, self-replenishing plasma-facing surfaces requiring very little upkeep. In a previous work, we studied Li and LiSn layers deposited on attachment screws in the COMPASS tokamak by means of Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS). Several problems were encountered related to the detection of Sn in LiSn. Thus, in the present work, we are optimizing the experimental conditions for the detection of Sn I-II and Pb I-II in Pb-containing Sn-based alloys, performing the quantification of Pb in traces and in bulk quantities using CF-LIBS approach.

Development of a Purified Viral Preparation for Studies of COVID-19 (SARS-CoV-2) Biology.

Different methods for producing bulk quantities of concentrated and purified SARS-CoV-2 for the use as antigens and for the research into COVID-19 biology were tested.

Thermophysical and Compositional Analyses of Dunes at Hargraves Crater, Mars

Abstract We analyze thermal emission spectra using the 2001 Mars Odyssey Thermal Emission Imaging System and the Mars Global Surveyor Thermal Emission Spectrometer to characterize grain size and mineralogical composition of dunes at Hargraves crater, Mars. Thermal inertia and bulk composition of the dunes were compared to inferred provenances from the thermal infrared response of surface constituent materials. We use a Markov Chain Monte Carlo technique to estimate the bulk amount of mineralogy contributed by each inferred provenance to the dune field composition. An average thermal inertia value of 238 ± 17 Jm−2 K−1 s−0.5 was found for the dunes, corresponding to a surface composed of an average effective grain size of ∼391 ± 172 μm. This effective particle size suggests the presence of mostly medium sand-sized materials mixed with fine and coarse grain sands. The dunes are likely composed of a weakly indurated surface mixed with unconsolidated materials. Compositional analysis specifies that the dunes are composed of a mixture of feldspar, olivine, pyroxene, and relatively low bulk-silica content. Dune materials were likely derived from physical weathering, especially aeolian erosion, predominantly from the crater ejecta unit at the crater, mixed with a small amount from the crater floor and crater rim and wall lithologies—indicating that the dune materials were likely sourced locally.

Flax processing waste – A low-cost, potential biosorbent for treatment of heavy metal, dye and organic matter contaminated industrial wastewater

A huge quantity of dye and heavy metal contaminated wastewater is generated from the textile industries every year all over the world. Additionally, water retting of flax fibre in sub-tropical humid climate also produces bulk amount of wastewater. Extraction of flax fibre from stem produces a large quantity of flax processing waste mainly composed of broken shives. A potential and cost-effective biosorbent can be formulated using these flax processing wastes to remediate the wastewater. However, no such previous studies were conducted to evaluate its potentiality as a biosorbent in detail. Keeping such a wide research-gap in mind, this study was done to explore the potentiality of almost freely available flax processing waste as a biosorbent. The present study demonstrated the efficient adsorption of heavy metals like adsorption of zinc (Zn), lead (Pb), and copper (Cu) as well as reduction of dyes viz. malachite green (MG), methylene blue (MB) and Congo red (CR) from contaminated wastewater treated with flax-biosorbent. Calculated maximum adsorption capacity values were obtained as 8.32, 13.35, and 7.12 mg g−1 for Cu, Pb, and Zn, correspondingly; and 163.9, 94.3 and 85.5 mg g−1 for MB, MG, and CR, respectively. Such values strongly indicate the higher adsorption competence of the flax-waste based biosorbent. The optimum pH ranged from 5.0 to 7.0 concerning heavy metal-adsorption on this biosorbent, while, the optimal pH for the removal of dyes was ranged from 6.5 to 6.7. The adsorption kinetics for heavy metals and dyes followed the pseudo-second-order path. Significant improvements of flax-retting wastewater were also found after treating it with flax-biosorbent at the rate of 2 g L−1. All these results strongly depict the potentiality of flax processing waste as a low-cost biosorbent to treat industrial wastewater as well as the leftover flax retting water. Thus, this technology might be a breakthrough to ensure cleaner production and sustainable development goals.

The Future of Flash Graphene for the Sustainable Management of Solid Waste.

Graphene research has steadily increased, and its commercialization in many applications is becoming a reality because of its superior physicochemical properties and advances in synthesis techniques. However, bulk-scale production of graphene still requires large amounts of solvents, electrochemical treatment, or sonication. Recently, a method was discovered to convert bulk quantities of carbonaceous materials to graphene using flash Joule heating (FJH) and, so named, flash graphene (FG). This method can be used to turn various solid wastes containing the prerequisite element carbon into FG. Globally, more than 2 billion tons of municipal solid waste (MSW) are generated every year and, in many municipalities, are becoming unmanageable. The most commonly used waste management methods include recycling, composting, anaerobic digestion, incineration, gasification, pyrolysis, and landfill disposal. However, around 70% of global waste ends up in landfills or open dumps, while the rest is recycled, composted, or incinerated. Even the various waste valorization techniques, such as pyrolysis and gasification, produce some waste residues that have their ultimate destination in landfills. Thus, technologies that can minimize waste volume or convert waste into valuable products are required. The thermal treatment process of FJH for FG production provides both waste volume reduction and valorization in the form of FG. In this Perspective, we provide an overview of FJH and its possible applications in various types of waste conversion/valorization. We describe the typical current MSW management system as well as the potential for creating FG at various stages and propose a schematic plan for the incorporation of FG in MSW management. We also analyze the strengths, weaknesses, opportunities, and threats of MSW as an FG precursor in terms of technical, economic, environmental, and social sustainability. This valuable waste valorization and management strategy can help achieve near-zero waste and an economy-boosting MSW management system.

Defluorination of Omega-Hydroperfluorocarboxylates (ω-HPFCAs): Distinct Reactivities from Perfluoro and Fluorotelomeric Carboxylates.

Omega-hydroperfluorocarboxylates (ω-HPFCAs, HCF2-(CF2)n-1-COO-) are commercially available in bulk quantities and have been applied in agrochemicals, fluoropolymer production, and semiconductor coating. In this study, we used kinetic measurements, theoretical calculations, model compound experiments, and transformation product analyses to reveal novel mechanistic insights into the reductive and oxidative transformation of ω-HPFCAs. Like perfluorocarboxylates (PFCAs, CF3-(CF2)n-1-COO-), the direct linkage between HCnF2n- and -COO- enables facile degradation under UV/sulfite treatment. To our surprise, the presence of the H atom on the remote carbon makes ω-HPFCAs more susceptible than PFCAs to decarboxylation (i.e., yielding shorter-chain ω-HPFCAs) and less susceptible to hydrodefluorination (i.e., H/F exchange). Like fluorotelomer carboxylates (FTCAs, CnF2n+1-CH2CH2-COO-), the C-H bond in HCF2-(CF2)n-1-COO- allows hydroxyl radical oxidation and limited defluorination. While FTCAs yielded PFCAs in all chain lengths, ω-HPFCAs only yielded -OOC-(CF2)n-1-COO- (major) and -OOC-(CF2)n-2-COO- (minor) due to the unfavorable β-fragmentation pathway that shortens the fluoroalkyl chain. We also compared two treatment sequences-UV/sulfite followed by heat/persulfate and the reverse-toward complete defluorination of ω-HPFCAs. The findings will benefit the treatment and monitoring of H-containing per- and polyfluoroalkyl substance (PFAS) pollutants as well as the design of future fluorochemicals.

Transmembrane transport in inorganic colloidal cell-mimics.

A key aspect of living cells is their ability to harvest energy from the environment and use it to pump specific atomic and molecular species in and out of their system-typically against an unfavourable concentration gradient1. Active transport allows cells to store metabolic energy, extract waste and supply organelles with basic building blocks at the submicrometre scale. Unlike living cells, abiotic systems do not have the delicate biochemical machinery that can be specifically activated to precisely control biological matter2-5. Here we report the creation of microcapsules that can be brought out of equilibrium by simple global variables (illumination and pH), to capture, concentrate, store and deliver generic microscopic payloads. Borrowing no materials from biology, our design uses hollow colloids serving as spherical cell-membrane mimics, with a well-defined single micropore. Precisely tunable monodisperse capsules are the result of a synthetic self-inflation mechanism and can be produced in bulk quantities. Inside the hollow unit, a photoswitchable catalyst6 produces a chemical gradient that propagates to the exterior through the membrane's micropore and pumps target objects into the cell, acting as a phoretic tractor beam7. An entropic energy barrier8,9 brought about by the micropore's geometry retains the cargo even when the catalyst is switched off. Delivery is accomplished on demand by reversing the sign of the phoretic interaction. Our findings provide a blueprint for developing the next generation of smart materials, autonomous micromachinery and artificial cell-mimics.

Impact of the Covid-19 Pandemic Outbreak on Panic Buying Behavior in the FMCG Sector

There is no doubt that a very challenging market climate has been created by the crisis triggered by the global coronavirus pandemic. Many firms have faced partial and even extended stoppages, with employees facing financial uncertainties and concerns for months. Consumer behavior has been compelled involuntarily to alter their habit of consumption in a large scale. Distress over the delivery of the commodities has led many individuals to panic purchasing of vital materials in bulk quantities. The view of a long-term recession and financial instability will have a notable effect on customer expectations, outlook and actions.
 The current research attempts to analyze and quantify customer preferences, emotions and consumer behavior during the coronavirus crisis. The report also reflects on the transition in eating patterns after the outbreak of COVID-19. It will also examine and present the variations in eating habits and behavior across different genders and ages.

The effect of an inline blockage on the formation of a turbulent free jet

In many equilibrium-based models for droplet size prediction, the fundamental parameters of turbulence are removed in favour of bulk quantities like velocity, and diameter. In this work we show that the upstream conditions of the jet are of critical importance and cannot be neglected, as they influence the turbulence field in jets in ways that are not accounted for in models based entirely on bulk parameters. This work presents the results of a single-phase investigation into the effect of upstream disturbances on a turbulent free jet.Reynolds Averaged Navier-Stokes Simulations of turbulent free jets with disturbances (in the form of orifice plates with a β ratio of 0.5) located at varying locations upstream of the pipe exit have been undertaken. Validation against experimental data for an orifice plate in a pipe found the Standard k-ε model to be the most accurate of the RANS models tested for this geometry.The additional turbulence generated from the upstream disturbances was found to be advected downstream and did not dissipate prior to the jet exit. The increased turbulence levels and altered form of the turbulence profile at exit was found to affect the evolution and observed turbulence levels of the free jet.Two distinct ‘modes’ were observed for the influence of the disturbances on the free jet. When the orifice plate is near the exit the free jet is dominated by the behaviour of semi-confined jet forming from the blockage. For the deeper set disturbances, the predicted form of the free jet was similar to that of the free jet from a straight pipe, though the turbulence levels are still elevated at the exit, affecting spreading rates and turbulence levels in the jet.Measures based on averages of TKE and TDR over hemispheres of varying radii are proposed for the development of models that do take into account the turbulent state of the exiting jet.

Synthesis of Poly(Methyl Methacrylate) Reinforced by Graphene Nanoplates

Graphene nanoplatelets (GNPs) was used as a nanofiller in Poly(methyl methacrylate) (PMMA) synthesized by the Atom Transfer Radical Polymerization (ATRP) method. The first step in the synthesis of the PMMA/GNPs was the dispersion of GNPs in the PMMA liquid monomers by combining the solutions so that GNPs had superior mechanical properties, thermal stability, and electrical conductivity also lower density of mass. Then the crosslinked PMMA/GNPs nanocomposite samples were synthesized by using the in-situ polymerization method. However, there was a challenging technical problem in the application of GNPs (at a large amount) in the polymer. For the purpose of benefiting from the advantageous properties of GNPs (especially in bulk quantities) at PMMA, the major problem at the synthesis of PMMA/GNPs nanocomposite was the GNPs dispersion in the polymer matrix. This research has focused on solving that dispersion problem with the aim of enhancing the mechanical properties of the nanocomposite by utilizing the ATRP method as the effective production technic. The structural characterization of PMMA/GNPs nanocomposite was performed for the examination of the integration of GNPs in PMMA. The surface morphology of the nanocomposite was analyzed using SEM images. X-Ray Diffraction (XRD) as a non-destructive test method was used to examine the changes in the crystalline properties of the nanocomposite structure with the rise of the GNPs amount in PMMA. The bonding interactions with each other were investigated by using Raman analysis.

Weighting gates in circuit complexity and holography

Abstract Motivated by recent studies of quantum computational complexity in quantum field theory and holography, we discuss how weighting certain classes of gates building up a quantum circuit more heavily than others affects the complexity. Utilizing Nielsen’s geometric approach to circuit complexity, we investigate the effects for a regulated field theory for which the optimal circuit is a representation of $GL(N,\mathbb{R})$. More precisely, we work out how a uniformly chosen weighting factor acting on the entangling gates affects the complexity and, particularly, its divergent behavior. We show that assigning a higher cost to the entangling gates increases the complexity. Employing penalized and unpenalized complexities for the $\mathcal{F}_{\kappa=2}$ cost, we further find an interesting relation between the latter and that based on the unpenalized $\mathcal{F}_{\kappa=1}$ cost. In addition, we exhibit how imposing such penalties modifies the leading-order UV divergence in the complexity. We show that appropriately tuning the gate weighting eliminates the additional logarithmic factor, thus resulting in a simple power-law scaling. We also compare the circuit complexity with holographic predictions, specifically based on the complexity=action conjecture, and relate the weighting factor to certain bulk quantities. Finally, we comment on certain expectations concerning the role of gate penalties in defining complexity in field theory and also speculate on possible implications for holography.

Contribution of Different Molecules and Moieties to the Surface Tension in Aqueous Surfactant Solutions. II: Role of the Size and Charge Sign of the Counterions.

Understanding the role of the counterion species in surfactant solutions is a complicated task, made harder by the fact that, experimentally, it is not possible to vary independently bulk and surface quantities. Here, we perform molecular dynamics simulations at constant surface coverage of the liquid/vapor interface of lithium, sodium, potassium, rubidium, and cesium dodecyl sulfate aqueous solutions. We investigate the effect of counterion type and charge sign on the surface tension of the solution, analyzing the contribution of different species and moieties to the lateral pressure profile. The observed trends are qualitatively compatible with the Hofmeister series, with the notable exception of sodium. We point out a possible shortcoming of what is at the moment, in our experience, the most realistic nonpolarizable force field (CHARMM36) that includes the parametrization for the whole series of alkali counterions. In the artificial system where the counterion and surfactant charges are inverted in sign, the counterions become considerably harder. This charge inversion changes considerably the surface tension contributions of the counterions, surfactant headgroups, and water molecules, stressing the key role of the hardness of the counterions in this respect. However, the hydration free energy gain of the counterions, occurring upon charge inversion, is compensated by the concomitant free energy loss of the headgroups and water molecules, leading to a negligible change in the surface tension of the entire system.

Secret Sharing-based Personal Health Records Management for the Internet of Health Things

The holistic concept of smart cities has been adopted to increase economic, environmental, and social sustainability. For the sustainable health of a smart city inhabitant, there is a requirement for innovations in implementing health solutions. Given the exponential growth of the Internet of Health Things (IoHT) in health infrastructures, bulk amounts of health-related data are accumulated in Personal Health Records (PHR) and processed in storage data centers. One of the major challenges in this scenario is the security of this enormous medical data. The conventional encryption schemes generate single cipher images making the cryptosystem vulnerable to single-point attacks. This paper evaluates a distributed security module for the clinical images that form 80% of the health data. We utilize the Rivest Cipher 6 (RC6) encryption algorithm with a Computational Secret Sharing Scheme (CSIS) for distributed storage of clinical images. The key is shared using a Perfect Secret Sharing (PSS) scheme. We show that (k-1) key-shares and the 'n' image shares can be made public because of the perfect security of the scheme. The rest of the key shares can be secured using the Deoxyribonucleic Acid substitution (DNA substitution) method. Analysis of the shares generated reveals the strength of the cryptosystem and gives an insight into the degree of security provided to the health-related data. The entropy of the generated shares is higher than 7.99, and structural similarity (SSIM) values are negligible. The Number of Pixels Change Rate (NPCR) values are greater than 99.55% for all the shares that show a high diffusion measure. Comparison with state-of-the-art schemes reveals and validates the robustness of the cryptosystem.

Bulk synthesis of tungsten-oxide nanomaterials by a novel, plasma chemical reactor configuration, studies on their performance for waste-water treatment and hydrogen evolution reactions

We report a novel, yet simple, DC non-transferred thermal plasma torch assisted, green, plasma-chemical reactor configuration, for high-rate synthesis of tungsten-oxide nanomaterials, up to two hundred grams per hour. An expanded argon/oxygen plasma beam is produced with a collimated, frozen structure, which interacts uniformly and in a controlled manner, over a large area of the remotely placed, tungsten target, to produce superfine particles in bulk amounts and without mixed with large aggregates. The target surface gets oxidized to form volatile tungsten-oxide, from which nanoparticles are nucleated by gas phase condensation process. Optical emission spectroscopic studies reveal that a massive argon plasma ion density leads to the production of reactive atomic oxygen radicals that were responsible for the rapid oxidation kinetics. Non-stoichiometric tungsten-oxide in pale blue colour and nanometer sizes were deposited on the water-cooled walls of the vacuum chamber. This sample was annealed to produce nanocrystalline, tungsten-oxide in yellow colour, which was characterized with narrow size distribution and fine material crystallinity. Functional properties of the synthesized nanomaterials were also measured, their photocatalytic characteristics for the degradation of the dye Rhodamine-B and antibacterial properties against E. coli bacteria. The annealed powder sample could remove the dye almost completely in about three hours. The same nanopowders demonstrated promising antibacterial properties, which may therefore lead to multi-functionality during the treatment of wastewater. Their hydrogen evolution reaction activity is also investigated that demonstrates moderate performance.

Can't touch this: Highly omniphobic coatings based on self-textured C6-fluoroponytailed polyvinylimidazolium monoliths

The quaternization of 1-vinylimidazole with 1H,1H,2H,2H-perfluorooctyl iodide, followed by anion metathesis reactions, allowed for the synthetic access of novel polymerizable fluorosurfactant salts with excellent yields, scalable from multigram up to bulk quantities on the kg scale. Subsequently, a series of doubly fluoroponytailed monomers as well as bridged bis-vinylimidazolium cross-linkers have been prepared via expedient thionation / S-alkylation. Thus, the resulting pool of these late stage intermediates offers great potential in task-specific surface tuning. Through polymerization in appropriate porogen mixtures combined with the micellar self-aggregation of the perfluoroalkyl moieties along with synergistic ionic interactions of the novel fluorosurfactants, the formation of nano-scalar monolithic structures is induced as evidenced by SEM imaging. According to contact angle measurements, the lotus-like textures hereby created drastically enhance oil and water repellency of the resulting polymer surface. Heeding the well-established cooperative concepts of chemical surface functionalization, accompanied by physical roughness, represents a proven strategy to impart high omniphobicity. However, the applicative maturity of systems based on nanophysics is frequently restricted by tedious and intricate patterning techniques as well as the environmental constraints of surface-active fluoroorganic compounds, on which high-performance systems indispensably rely.

Ultrafast and Controllable Phase Evolution by Flash Joule Heating.

Flash Joule heating (FJH), an advanced material synthesis technique, has been used for the production of high-quality carbon materials. Direct current discharge through the precursors by large capacitors has successfully converted carbon-based starting materials into bulk quantities of turbostratic graphene by the FJH process. However, the formation of other carbon allotropes, such as nanodiamonds and concentric carbon materials, as well as the covalent functionalization of different carbon allotropes by the FJH process, remains challenging. Here, we report the solvent-free FJH synthesis of three different fluorinated carbon allotropes: fluorinated nanodiamonds, fluorinated turbostratic graphene, and fluorinated concentric carbon. This is done by millisecond flashing of organic fluorine compounds and fluoride precursors. Spectroscopic analysis confirms the modification of the electronic states and the existence of various short-range and long-range orders in the different fluorinated carbon allotropes. The flash-time-dependent relationship is further demonstrated to control the phase evolution and product compositions.

Comparative investigation on HVDC and HVAC for bulk power delivery

A high voltage direct current (HVDC) is an efficient technology used to design and deliver a bulk amount of electricity over a long distance with negligible losses. When the time progresses simultaneously the load demand is also increasing, so there should be only two possibilities either to increase power generation or to minimize the losses, therefore, using HVDC can greatly reduce the power transmission losses. The cost is one of the most important factors, hence HVDC is a more suitable option for bulk power delivery as the total cost of the HVDC transmission system is very less as compared to that of a high voltage alternating current (HVAC) system transmitting the same amount of the electricity over the same distance. In this paper performance of HVDC under different load and faulty conditions is analyzed for various parameters under consideration with given constraints. Matlab Simulink is used for modeling the 12pulse HVDC transmission system. Results show that HVDC is the best option for bulk power transmission. A comparative analysis of HVDC and HVAC power transmission systems has also been done for its acceptability.

Analysis of energy transfer through direct numerical simulations of magnetohydrodynamic Orszag–Tang vortex

Direct numerical simulations of magnetohydrodynamic turbulence with Orszag–Tang vortex initial conditions are presented here for two different Reynolds numbers. Simulations of this transition-to-turbulence problem are carried out using a pseudo-spectral code with a grid resolution fine enough to resolve the Kolmogorov scale. The power-law behavior of bulk quantities like kinetic energy, magnetic energy, integral length scales, and enstrophy is analyzed. For a low Reynolds number, weak turbulence spectra are observed with a slope of −2.0 in the inertial subrange, while for a higher Reynolds number, the spectra exhibit a slope very close to the Kolmogorov spectra of −5/3. The Q-criteria isosurfaces at the time instant of maximum enstrophy are used for the visualization of turbulence developed within the flow. Furthermore, a new approach is presented to understand the dynamics of the transfer between kinetic and magnetic energies in the early period of development using the energy flux spectra, rate of change of kinetic and magnetic energies, and current density structures, which employ a three-dimensional representation of the alignment between velocity and magnetic field across the structures.