Critical Amount Research Articles

Society and people

Science and philosophy has a strong polar division from the very beginning of human civilization. People have been using the both to tackle down the issues and troubles of the society, domesticity and of personal levels. While the western has been seeking, practical solutions to the problems through science, The Arabs in spite of internal turbulence and external pressure have retained their strong individuality preferred to look at life in poetic and philosophical terms. The Arab has a dominance of religious biasness instead of scientific developments. The writers from the area also respected the same and have captured the spirit of masses, portraying their devotion to home and their blind fidelity to their rules. Arab writers have left freedom of expression with their own unconventional pattern and no amount of outside pressure or criticism has been able to divert them from it. The social, political and religious issues were very widely discussed in the works of some Arabic writers. One of the most notable one is Jibran Khalil Jibran, the paper aims to explore these social concerns through his one of most celebrated short story collections- “ "عرائس المروج "Nymphs of the Valley”.

Metallurgical byproducts application aimed at improving ore concentration efficiency at Talnakh Concentrator

Talnakh Concentrator processes the mixture of high-grade and cupriferous ores to produce copper and nickel-pyrrhotite concentrates via the process implemented in 2016. Since 2018, pursuing a comprehensive use of raw materials, Talnakh Concentrator proceeded with reconcentration of low-nickel pyrrhotite product to produce low-grade reflotation concentrate (0.8–1.2% of nickel) sent to Nadezhda Metallurgical Plant named after B.I. Kolesnikov (hereinafter, NMP) for hydrometallurgical processing. Testing of Copper Plant’s byproducts application was aimed at increasing nickel recovery as a result of the nickeliferous pyrrhotite surface activation by copper ions. It is impractical to apply blue vitriol, traditionally used for this purpose, as it leads to a significant decrease in technical and economic performance due to an increase in operating costs for reconcentration. The Copper Plant products, such as decopperized electrolyte and a coppernickel solution from PGM Concentrator were tested as activators. These products contain not only residual amount of copper ions, but also a substantial quantity of sulphuric acid. The study showed that Copper Plant’s solution application increased the amount of nickel recovered to the product of reconcentration and improved the product pyrrhotite content that favorably effected its subsequent pressure oxidation leaching. Application of the copper-nickel solution from PGM Concentrator is considered to be the best option due to a higher ratio of copper ions to sulphuric acid. Solutions applied during nickel-pyrrhotite flotation at Talnakh Concentrator were also studied. The authors simulated the initial composition alteration of Talnakh Concentrator’s feed with an increase in a share of cupriferous ore, containing much less pyrrhotite than high-grade ore. It was found out that if the feed contained critical amount of cupriferous ore, application of Copper Plant’s solutions contributed to maintenance of sulphur content in the nickel-pyrrhotite concentrate of Talnakh Concentrator that provided energy potential required for the appropriate thermal conditions of NMP’s smelting vessels.

The effect of enriched accreted matter on the development of novae

ABSTRACT The development of a nova eruption is well known to be determined by the white dwarf (WD) mass and the rate at which it accretes mass from its donor. One of the advancements in this field is the understanding that the occurrence of a nova eruption depends on the presence of heavy elements in the envelope, and that the concentration of these elements is highly dependent on the time allotted for accretion. This results in many features of the eruption being correlated with the mass fractions of heavy elements in the ejected material, however, the accreted material is always assumed to be of solar metallicity. Here, we explored the entire range of accretion rates on to a 1.25 $\, \mathrm{M}_\odot$ WD for two cases of highly enriched accreted material and find enrichment to have an influence on certain features for high accretion rates, while the effect of enrichment on low accretion rates is negligible. We further find that the ignition of the thermonuclear runaway which is known to be dependent on the accumulation of a critical mass, is actually dependent on the accumulation of a critical amount of heavy elements.

Oxidative Refining of Metallurgical Grade Silicon: Lab-Scale Measurements on the Overarching Refining Behavior of Ca and Al

Oxidative ladle refining (OLR) is the most widely used refining process for removal of dissolved Ca and Al in the industrial production of metallurgical grade silicon (MG-Si). Refining occurs by purging the silicon alloy with an oxygen–air mixture at temperatures preferably between 1823 K and 1873 K, forming a SiO_{2}–CaO–Al_{2}O_{3} slag, which is then separated from the liquid alloy before casting. To meet higher quality demands and customer specifications, it is paramount to achieve greater process control of the industrial system, which requires a deeper understanding of the Ca and Al mass transfer kinetics, and the general refining behavior. In this work, laboratory-scale experiments have been performed, aiming to emulate the industrial process. Five different alloy compositions, with varying initial Ca and Al concentration, were refined over 11 experiments, with samples taken at 0, 5, 7, 10, and 15 minutes at 1873 K. A FactSage-based model was used to explore the underlying thermodynamic system behavior. The results suggest that OLR of MG-Si occurs in three primary steps, initially by the formation of slag by surface oxidation and purge gas, through the depletion of dissolved Ca in the melt, and secondarily by the formation of silica. Towards the end of the refining process, a critical amount of slag has been formed by the previous steps such that a global equilibrium is attained between the SiO_{2}–CaO–Al_{2}O_{3} slag and the silicon alloy.

The Biological Robots Are Coming! But Note They Have Been Here for ∼3.5 Billion Years

The Biological Robots Are Coming! But Note They Have Been Here for ∼3.5 Billion Years

Optimization of Infectious Disease Prevention and Control Policies Using Artificial Life

The spread of an infectious disease such as COVID-19 is governed by complex social interactions that are challenging to model. Policy makers must take measures to control the spread of infection despite the unknowns that accompany a novel epidemic. The principles of artificial life govern the intricacies of social interaction through which diseases can spread. Agent-based models can capture these complexities for a subset of the population by defining the behavior of individual agents. While they can be computationally expensive for large populations, their outcomes are stochastic. Therefore, they can be used to test disease prevention policies, that can be difficult to simulate using deterministic approaches. We developed an agent-based model that is inspired by several interactive simulations on the internet for describing the COVID-19 pandemic. We define metrics to estimate the socio-economic cost of disease prevention policies on the population. We present a policy-making tool based on blackbox optimization and evolutionary computation that provides well-rounded intervention measures in terms of socio-economic cost and disease control. Several intervention measures are suggested by the algorithms with varying degrees of disease control and socio-economic cost. Policy makers can choose an intervention measure based on their preference. This research recommends combining computational intelligence principles and the use of mathematical algorithms for identifying the critical amount of intervention necessary to control infectious diseases and formulate intervention policies that minimize socio-economic cost.

Development of the system of state financing of Compulsory Health Insurance

Objective: to study the potential for the development of financing the Compulsory Health Insurance (CHI) system in Russia.Material and methods. Оur research estimates the amount of funds available in the CHI system based on fractal analysis and ARIMA modeling. The proposed approach makes it possible to determine the critical amount of funds in the CHI system. Once the limit is reached, the chance of violating the economic security requirements will increase. Results. Аn increase in the volume of available funds in the CHI sector is expected in the mid-term perspective on the verge of quarter 1, 2023. The amount of funds required to pay for medical care for the respective period of time will increase by 0.77% quarterly.Conclusion. Gaining additional funds might be possible by optimizing the internal networks for generating cash flows in the CHI system, as well as applying additional ways of financing medical care (particularly Voluntary Health Insurance policies). It would be practical to redistribute the functions of financing health care between the Federal Fund for CHI and its territorial branches. It is essential to review the role of health insurance companies in monitoring the health care quality by improving the communication with citizens.

Colorimetric biofilm sensor with anthocyanin for monitoring fresh pork spoilage

The colorimetric biofilm sensor was prepared for monitoring of freshness pork based on natural composite polymer including agar, sodium alginate and polyvinyl alcohol mixed with anthocyanin as an indicator and coated on chromatographic paper. The anthocyanin was extracted from red cabbage by boiling with distilled water at 80 °C for 90 min and adjusted to pH 2. The colorimetric biofilm sensor mixed with anthocyanin extracts obviously a clear color response from pink to green at pH 2.0–11.0. The composite polymers can be enhancing the stability of anthocyanin extracts. The colorimetric biofilm sensor was stored at 4 °C in darkness has more color stability than room temperature for 30 days. The colorimetric biofilm sensor was evaluated by a test on monitoring pork spoilage, the color was changed from pink to orange when total volatile basic nitrogen (TVB–N) reached higher than the critical amount (25 mg N/100 g.). These results can be concluded that the development of colorimetric biofilm sensor could be used to monitor pork freshness.

Effect of different chloride environments on corrosion behavior of secondary AlSi7Mg0.6 cast alloy with higher Fe content

Secondary aluminum alloys are materials with higher Fe content. There are currently several studies on the corrosion behavior of casts from metal molds, but sand casts are being forgotten despite being still primarily used in gravity casting. Secondary Al-alloys have exceptional benefits as they are made from scrap and can be cast as thin-walled, which has a positive effect on the lightening of constructions, and on environmental impact. Unfortunately, the Fe is a common impurity but in higher content decrease properties of aluminum casts. The removal of the Fe content is very expensive, and therefore the effect of Fe content in a larger amount is monitored. This work is focused on the corrosion behavior of the heat-hardening aluminum alloys commonly used to produce castings AlSi7Mg0.6 for automotive. The experimental alloy was intentionally contaminated with Fe for reaching the critical amount of Fe in aluminum casts. Metallographic analysis (using optical and scanning electron microscopy, energy dispersive X-ray analysis) was used before corrosion tests. The microstructure of experimental alloys with higher content of Fe contains large Fe-rich phases in the form of needles. These changes in microstructure lead to the formation of a higher amount and size of porosity but the α-phase was not affected. Corrosion properties were examined by three basic corrosion tests: immersion test, potentiodynamic test, and Audi test. Corrosion characteristics of materials were evaluated using a stereo and optical microscope. Corrosion evaluation of the alloys shows the presence of pitting corrosion, which increases with increasing Fe content.

Recycling of dielectric electroactive materials enabled through thermoplastic PDMS.

In the green transition, actuators and generators play an essential role in the development of sustainable solutions across a broad range of applications. In this context, dielectric transducers are advocated as one of the most promising solutions in terms of effectiveness, lifetime and running costs. However, they are classically produced as sandwich structures, whereby a cross-linked dielectric material is placed between two compliant electrodes. From a materials consumption viewpoint, this is problematic, since it will inherently result in a loss of material during production as well as inhibit the recycling of expended systems when their life comes to an end. Herein, we present a cleaning method employing surfactants and sonication to remove electrodes from the surface of the dielectric material. By applying a thermoplastic silicone elastomer as the dielectric material, it is possible to reprocess the material by hot-pressing, and to prepare new actuators after the rinsing process. This effectively shows that recycling production scrap, for example, is possible. By comparing the cleaned material with a directly recycled material, it is clear that cleaning removes a critical amount of metals from the material and enables recycling for at least five cycles. Comparatively, a directly recycled material is prone to a high leakage current and premature electronic breakdown after only two cycles. This simple cleaning process, in combination with use of a thermoplastic dielectric material, enables less waste from production as well as the possibility of reclaiming and recycling materials in general.

Modeling HMM Map Matching Using Multi-label Classification

Map matching deals with matching GPS coordinates to corresponding points or segments on a road network map. The work has various applications in both vehicle navigating and tracking domains. Traditional rule-based approach for solving the Map matching problem yielded great matching results. However, its performance depends on the underlying algorithm and Mathematical/Statistical models employed in the approach. For example, HMM Map Matching yielded O(N2) time complexity, where N is the number of states in the underlying Hidden Markov Model. Map matching techniques with large order of time complexity are impractical for providing services, especially within time-sensitive applications. This is due to their slow responsiveness and the critical amount of computing power required to obtain the results. This paper proposed a novel data-driven approach for projecting GPS trajectory onto a road network. We constructed a supervised-learning classifier using the Multi-Label Classification (MLC) technique and HMM Map Matching results. Analytically, our approach yields O(N) time complexity, suggesting that the approach has a better running performance when applied to the Map matching-based applications in which the response time is the major concern. In addition, our experimental results indicated that we could achieve Jaccard Similarity index of 0.30 and Overlap Coefficient of 0.70.

Spallation-based numerical simulations of ice-induced vibration of structures

A full-scale 3D numerical simulation model of ice-induced vibration of structures has been developed (using LS-Dyna™) and applied to the Molikpaq facility for an ice-encroachment event similar to that which occurred on May 12, 1986 in the Beaufort Sea. The bulk ice sheet used for the simulations had elastic properties, and its dimensions were 6 km × 6 km × 2.5 m. Where ice crushing occurred at the structure-ice interface the ice model used was a crushable foam that incorporated regular spallation events. Typical characteristics of ice-crushing in the brittle regime were manifested by the model. That is, a narrow horizontal hard zone (relatively-intact high-interface-pressure ice) was present in the mid-height region of the ice-edge contact area. Soft-zone material (shattered spall debris from the hard zone) was also represented. Evolution of the hard-zone contact area involved rapid reductions in size during spallation events, immediately followed by fast growth during consequent elastic surging of the near-field ice sheet and structure towards each other, and then some slower growth (due to the bulk ice-sheet velocity) until the next spalling event. The specified ‘thickness’ of the spalls was 5.4 cm, as previously determined from Molikpaq records of the frequency of the spalling events as a function of ice-sheet speed. Spallation (and associated rapid drops in load) occurred at regular intervals whenever a critical amount of hard-zone stress was reached at the ice-structure interface. The amplitude of the Molikpaq repetitive movements in response to the sawtooth loading from the spalling events depended on whether the resonant frequency of the structure/ice system was higher (for a strong response) or lower (for a weak response) than the spalling frequency, where the spalling frequency is directly proportional to the ice-sheet speed. The continuously variable resonant frequency of the structure/ice system had a maximal limiting value (~ 2.1 Hz), designated as the At-Spallation-Resonant-Frequency (ASRF), that was essentially determined by the time duration of load drops at spallation events. The simulations inherently accounted for the variable effective mass and effective spring constant of the ice sheet.

Manual Application versus Autonomous Release of Water Repellent Agent to Prevent Reinforcement Corrosion in Cracked Concrete

Cracks in reinforced concrete are preferential ingress paths for aggressive substances such as chlorides. As soon as a critical amount of chlorides has reached the steel reinforcement, corrosion will occur. Therefore, crack healing is of utmost importance. However, manual crack repair is very labour intensive. Therefore, the potential of self-healing through the release of a water repellent agent from embedded capsules was compared with the effectiveness of applying this agent on the concrete surface before or after cracking and the effectiveness of injection of the agent into a crack. From the electrochemical corrosion measurements, it was shown that only uncracked samples were able to withstand 135 weekly cycles of exposure to a 33 g/L chloride solution without corrosion initiation of the reinforcement. While samples with manually injected and autonomously healed cracks resisted the exposure conditions for about 50 cycles or more, samples for which the water repellent agent was applied onto the surface after cracking resisted the exposure conditions for 5–42 cycles, while samples for which the agent was applied onto the surface before cracking showed an immediate corrosion initiation similar as was noted for the untreated cracks. From a visualization of the chloride ingress front and determination of the chloride content in the vicinity of the crack, it was noticed that none of the crack treatment techniques performed as well as the uncracked series. Visual inspection of the corroded rebars and determination of the corroded volume of the rebars through computed tomography and macro-cell corrosion current measurements proved again that the uncracked series outperformed the other series. While the corroded volume of the rebars from the uncracked series was almost zero, this value ranged from 15–95 mm3 for the rebars of the other series. However, the latter investigations also showed that release of the agent into the crack, whether this was done in a manual way or autonomously through release from embedded capsules, resulted in a delayed corrosion initiation and lower corrosion propagation rate compared to the application of a water repellent agent onto the surface. This is a beneficial outcome for the further implementation of self-healing approaches, more specifically though the release of encapsulated water repellent agent, in the market.

Ramping Loss Analysis of No-Insulation HTS Coil Under External Field Using an Improved Equivalent Circuit Model

This article is to study the ramping loss of no-insulation (NI) high temperature superconducting (HTS) racetrack coil under different external magnetic fields during the charging process. An improved equivalent circuit electromagnetic coupling model for the HTS racetrack coil is introduced with good computational speed and accuracy. The simulation results show that the turn-to-turn loss and the change of the lowest critical current position are obviously influenced by the external field that have not been mentioned from our knowledge base. During the rising time of the power supply current, there is little difference in current distribution under different external fields. But after that, steady state of charging process is deeply influenced by the external field. A larger external field will lead to a lower charging current and the external bypass phenomenon. Another result is that the relationship between direction of external field and orientation of coils will influence the lowest critical current amount and position. The relationship between turn-to-turn resistivity of co-winding materials and ramping loss is also discussed in the paper. The distributed unevenness and value of the turn-to-turn loss change with the increase of turn-to-turn resistivity.

Matching the Cellulose/Silica Films Surface Properties for Design of Biomaterials That Modulate Extracellular Matrix.

The surface properties of composite films are important to know for many applications from the industrial domain to the medical domain. The physical and chemical characteristics of film/membrane surfaces are totally different from those of the bulk due to the surface segregation of the low surface energy components. Thus, the surfaces of cellulose acetate/silica composite films are analyzed in order to obtain information on the morphology, topography and wettability through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle investigations. The studied composite films present different surface properties depending on the tetraethyl orthosilicate (TEOS) content from the casting solutions. Up to a content of 1.5 wt.% TEOS, the surface roughness and hydrophobicity increase, after which there is a decrease in these parameters. This behavior suggests that up to a critical amount of TEOS, the results are influenced by the morphology and topographical features, after which a major role seems to be played by surface chemistry—increasing the oxygenation surfaces. The morphological and chemical details and also the hydrophobicity/hydrophilicity characteristics are discussed in the attempt to design biological surfaces with optimal wettability properties and possibility of application in tissue engineering.

A Rabbit Model for the Evaluation of Drugs for Treating the Chronic Phase of Botulism.

Antitoxin, the only licensed drug therapy for botulism, neutralizes circulating botulinum neurotoxin (BoNT). However, antitoxin is no longer effective when a critical amount of BoNT has already entered its target nerve cells. The outcome is a chronic phase of botulism that is characterized by prolonged paralysis. In this stage, blocking toxin activity within cells by next-generation intraneuronal anti-botulinum drugs (INABDs) may shorten the chronic phase of the disease and accelerate recovery. However, there is a lack of adequate animal models that simulate the chronic phase of botulism for evaluating the efficacy of INABDs. Herein, we report the development of a rabbit model for the chronic phase of botulism, induced by intoxication with a sublethal dose of BoNT. Spirometry monitoring enabled us to detect deviations from normal respiration and to quantitatively define the time to symptom onset and disease duration. A 0.85 rabbit intramuscular median lethal dose of BoNT/A elicited the most consistent and prolonged disease duration (mean = 11.8 days, relative standard deviation = 27.9%) that still enabled spontaneous recovery. Post-exposure treatment with antitoxin at various time points significantly shortened the disease duration, providing a proof of concept that the new model is adequate for evaluating novel therapeutics for botulism.

Spinel oxide incorporated photoanode for better power conversion efficiency in dye-sensitized solar cells

In this study, ZnMn2O4 (ZMO) nanoparticles were synthesized and mixed with the commercial TiO2 to prepare composite photoanode. Dye sensitized solar cells (DSSC) device was fabricated and highest power conversion efficiency of 5.09% was obtained for the cell with 0.1 wt% of ZMO in the photoanode, while in similar condition the device with pure TiO2 photoanode showed power conversion efficiency of 4.124%. This improvement in the power conversion efficiency of the composite photoanode based cell was attributed to the presence of critical amount of ZMO which synergistically improve the light absorption, charge transport properties prevented charge recombination, eventually it improved open-circuit voltage (Voc) and short-circuit current (Isc).

The #ReframeCovid initiative

Abstract From the beginning of the COVID-19 pandemic, governments, health agencies, public institutions and the media around the world have made use of metaphors to talk about the virus, its effects and the measures needed to reduce its spread. Dominant among these metaphors have been war metaphors (e.g. battles, front lines, combat), which present the virus as an enemy that needs to be fought and beaten. These metaphors have attracted an unprecedented amount of criticism from diverse social agents, for a variety of reasons. In reaction, #ReframeCovid was born as an open, collaborative and non-prescriptive initiative to collect alternatives to war metaphors for COVID-19 in any language, and to (critically) reflect on the use of figurative language about the virus, its impact and the measures taken in response. The paper summarises the background, aims, development and main outcomes to date of the initiative, and launches a call for scholars within the metaphor community to feed into and use the #ReframeCovid collection in their own basic and applied research projects.

Effect of CO2 injection on CH4 desorption rate in poor permeability coal seams: An experimental study

CO2 injection into coal seams is an effective way for reducing greenhouse gas emissions and increasing gas recovery in coal seams. To study the influence rule of CO2 injection on the CH4 desorption rate, an experimental system of CO2 displacing CH4 was used to analyse the changes in gas composition, outlet flow rate, coal seam temperature, and displacement efficiency parameters during CO2 injection. From the perspective of enhancing CH4 recovery, the CO2 critical injection amount (Vinc) is 297.4 L and critical injection time is 188.75 min. When the CO2 injection amount V < Vinc, the amount of CH4 desorption, CO2 storage, and CH4/CO2 gas content all increased. When V > Vinc, except CH4 desorption amount remained almost unchanged, the other parameters increased. In the process of CO2 displacing CH4, the coal seam temperature rises (exothermic process), showing a law of “hierarchical displacement”. With the injection of CO2, the pore pressure first decreased and then increased, the CH4 partial pressure decreased, and the effective diffusion coefficient first increased and then decreased. After the injection of CO2, the desorption time of CH4 was 269.45min earlier and the desorption rate of CH4 was increased by 12.43 %.

Hybrid Silica-Based Fillers in Nanocomposites: Influence of Isotropic/Isotropic and Isotropic/Anisotropic Fillers on Mechanical Properties of Styrene-Butadiene (SBR)-Based Rubber.

The improvement of mechanical properties of polymer-based nanocomposites is usually obtained through a strong polymer–silica interaction. Most often, precipitated silica nanoparticles are used as filler. In this work, we study the synergetic effect occurring between dual silica-based fillers in a styrene-butadiene rubber (SBR)/polybutadiene (PBD) rubber matrix. Precipitated Highly Dispersed Silica (HDS) nanoparticles (10 nm) have been associated with spherical Stöber silica nanoparticles (250 nm) and anisotropic nano-Sepiolite. By imaging filler at nano scale through Scanning Transmission Electron Microscopy, we have shown that anisotropic fillers align only in presence of a critical amount of HDS. The dynamic mechanical analysis of rubber compounds confirms that this alignment leads to a stiffer nanocomposite when compared to Sepiolite alone. On the contrary, spherical 250 nm nanoparticles inhibit percolation network and reduce the nanocomposite stiffness.