Chemical Neutralization Research Articles

Heat inactivation of clinical COVID-19 samples on an industrial scale for low risk and efficient high-throughput qRT-PCR diagnostic testing

We report the development of a large scale process for heat inactivation of clinical COVID-19 samples prior to laboratory processing for detection of SARS-CoV-2 by RT-qPCR. With more than 266 million confirmed cases, over 5.26 million deaths already recorded at the time of writing, COVID-19 continues to spread in many parts of the world. Consequently, mass testing for SARS-CoV-2 will remain at the forefront of the COVID-19 response and prevention for the near future. Due to biosafety considerations the standard testing process requires a significant amount of manual handling of patient samples within calibrated microbiological safety cabinets. This makes the process expensive, effects operator ergonomics and restricts testing to higher containment level laboratories. We have successfully modified the process by using industrial catering ovens for bulk heat inactivation of oropharyngeal/nasopharyngeal swab samples within their secondary containment packaging before processing in the lab to enable all subsequent activities to be performed in the open laboratory. As part of a validation process, we tested greater than 1200 clinical COVID-19 samples and showed less than 1 Cq loss in RT-qPCR test sensitivity. We also demonstrate the bulk heat inactivation protocol inactivates a murine surrogate of human SARS-CoV-2. Using bulk heat inactivation, the assay is no longer reliant on containment level 2 facilities and practices, which reduces cost, improves operator safety and ergonomics and makes the process scalable. In addition, heating as the sole method of virus inactivation is ideally suited to streamlined and more rapid workflows such as ‘direct to PCR’ assays that do not involve RNA extraction or chemical neutralisation methods.

Mechanical and Thermal Properties of Geopolymer Foams (GFs) Doped with By-Products of the Secondary Aluminum Industry.

The article deals with the investigation of geopolymer foams (GFs) synthesized using by-products coming from the (i) screening-, (iv) pyrolysis-, (iii) dust abatement- and (iv) fusion-processes of the secondary aluminum industry. Based on principles of the circular economy to produce new technological materials, the experimental study involves industrial by-products management through the recovery, chemical neutralization, and incorporation of these relatively hazardous waste into the GFs. The geopolymeric matrix, consisting of metakaolin (MK) and silica sand (SA) with a 1:1 wt.% ratio, and chopped carbon fibers (CFs, 1 wt.% MK), was doped with the addition of different aluminum-rich industrial by-products with a percentage from 1 to 10 wt.% MK. The gas (mainly hydrogen) produced during the chemical neutralization of the by-products represents the foaming agents trapped in the geopolymeric structure. Several experimental tests were carried out to characterize the mechanical (flexural, compressive, and Charpy impact strengths) and thermal properties (thermal conductivity, and diffusivity, and specific heat) of the GFs. Results identify GFs with good mechanical and thermal insulation properties, encouraging future researchers to find the best combination (for types and proportions) of the different by-products of the secondary aluminum industry to produce lightweight geopolymer foams. The reuse of these industrial by-products, which according to European Regulations cannot be disposed of in the landfill, also brings together environmental sustainability and safe management of hazardous material in workplaces addressed to the development of new materials.

Evolution of Mineral Phase in the Chemical Neutralization Process of Mn Dominated Acid Mine Drainage Under Different Aeration Conditions

Evolution of Mineral Phase in the Chemical Neutralization Process of Mn Dominated Acid Mine Drainage Under Different Aeration Conditions

Hydrogen-Rich Gas Produced by the Chemical Neutralization of Reactive By-Products from the Screening Processes of the Secondary Aluminum Industry

In the framework of the industry of secondary aluminum, the chemical neutralization of highly reactive materials that come from the pre-treatment screening processes of scraps (beverage cans and domestic appliances) was investigated through experiments in aqueous alkaline solutions. Metallic aluminum-rich by-products are classified, according to EU law, as dangerous waste, as they can potentially develop flammable gases capable of forming explosive mixtures with air. In this way they cannot be disposed of in landfills for non-hazardous wastes if chemical neutralization is not planned and performed beforehand. In this way, these experiments were mainly aimed at unraveling the oxidation rate and at quantifying the production of hydrogen-rich gases from the reactions of the metallic aluminum-rich by-products in a water-rich alkaline (liquid or vapor) environment. Reactions were carried out in a stainless-steel batch mini-reactor with metering and sampling valves, with the resulting gases analyzed by gas-chromatography (GC). The experimental setup was planned to avoid the following issues: (i) the corrosion of the reactor by the alkaline solution and (ii) the permeability of the system to hydrogen (i.e., possible leaks of H2), related to the fast kinetics and short duration of the reactions (which may hinder a pile-up-effect) between the solid by-products and the liquid. The procedure was defined by a controlled interaction process between metals and liquid, using NaOH to increase reaction rates. The experimental runs performed in the mini-reactor proved to be effective for eliminating the reactive metallic aluminum, reaching a maximum hydrogen production of 96% of the total gases produced in the experiments. The relations between gas generation (up to 55 bar of H2 in the experiments, which lasted for four days) and each specific parameter variation are discussed. All the obtained results can be transferred and applied to (i) the possible industrialization of the method for the chemical neutralization of these dangerous by-products, increasing sustainability and workplace safety, (ii) the use of the resulting hydrogen as a source of energy for the furnaces of the secondary aluminum industry itself, and (iii) new technological materials (e.g., “foamed geopolymers”), by using hydrogen as a foaming agent, coupled with aluminosilicate materials, during geopolymeric reactions.

Экологическая безопасность и перспективы развития малоотходных технологий в биотехнологическом производстве

Environmental pollution with industrial waste is an urgent problem today. A special place in the list of pollutants belongs to waste from biotechnological enterprises and industries, whose activities are related to the production of various drugs. Russian Research Anti-Plague Institute «Microbe» is the only manufacturer of unique immunobiological drugs in the Russian Federation – bivalent chemical cholera vaccine and rabies immunoglobulin from horse blood serum (AIG). At present, the institute actively uses fibrin as a basis for nutrient media – a waste in the production of AIG; a technology for the regeneration of alcohol waste has been developed; biologically active substances were obtained from the production waste of specific components of the cholera vaccine. The aim of the work was to assess the prospects of using waste products from the production of specific components of cholera vaccine (cholerogen-toxoid – X-AT, and O-antigen – O-AG) – formalized detoxified microbial-free filtrate (FMF), as a nutrient medium for the cultivation of industrial strains of microorganisms. It has been shown that the best methods for reducing formalin concentration are autoclaving and chemical neutralization with aqueous ammonia. During low-volume cultivation of Vibrio cholerae 569B and V. cholerae M-41 strains on all variants of experimental media based on PBP, an increase in biomass was noted. The production of Vibrio cholerae antigens at a level comparable to that of growing on a control nutrient medium was recorded in a medium variant based on O-AG production waste. The use of FMF as a nutrient medium in the future will reduce the volume of waste generated and reduce the load on the treatment facilities of the Institute, which will increase the environmental safety of production.

Evaluation of Cr(VI) Reduction Using Indigenous Bacterial Consortium Isolated from a Municipal Wastewater Sludge: Batch and Kinetic Studies

Hexavalent Chromium (Cr(VI)) has long been known to be highly mobile and toxic when compared with the other stable oxidation state, Cr(III). Cr(VI)-soluble environmental pollutants have been detected in soils and water bodies receiving industrial and agricultural waste. The reduction of Cr(VI) by microbial organisms is considered to be an environmentally compatible, less expensive and sustainable remediation alternative when compared to conventional treatment methods, such as chemical neutralization and chemical precipitation of Cr. This study aims to isolate and identify the composition of the microbial consortium culture isolated from waste activated sludge and digested sludge from a local wastewater treatment plant receiving high loads of Cr(VI) from an abandoned chrome foundry in Brits (North Waste Province, South Africa). Furthermore, the Cr(VI) reduction capability and efficiency by the isolated bacteria were investigated under a range of operational conditions, i.e., pH, temperature and Cr(VI) loading. The culture showed great efficiency in reduction capability, with 100% removal in less than 4 h at a nominal loading concentration of 50 mg Cr(VI)/L. The culture showed resilience by achieving total removal at concentrations as high as 400 mg Cr(VI)/L. The consortia exhibited considerable Cr(VI) removal efficiency in the pH range from 2 to 11, with 100% removal being achieved at a pH value of 7 at a 37 ± 1 °C incubation temperature. The time course reduction data fitted well on both first and second-order exponential rate equation yielding first-order rate constants in the range 0.615 to 0.011 h−1 and second order rate constants 0.0532 to 5 × 10−5 L·mg−1·h−1 for Cr(VI) concentration of 50–400 mg/L. This study demonstrated the bacterial consortium from municipal wastewater sludge has a high tolerance and reduction ability over a wide range of experimental conditions. Thus, show promise that bacteria could be used for hexavalent chromium remediate in contaminated sites.

Simultaneous Removal of Soluble Metal Species and Nitrate from Acidic and Saline Industrial Wastewater in a Pilot-Scale Biofilm Reactor

The hydrometallurgical treatment of waste printed circuit boards for the recovery of precious metals generates acidic wastewater containing nitrate, chloride and residual base metals. The scope of this work is the study of a biological treatment process for the concurrent metal sequestering, nitrate reduction and wastewater neutralization. A pilot-scale packed-bed biofilm reactor was set up, inoculated with the strain H. denitrificans and experimentally monitored. The range of operating parameters examined included: (a) nitrate concentration 750–5750 mg/L NO3−; (b) pH 3–8; (c) Cu, Ni, Zn and Fe at 50 mg/L and 100 mg/L; and (d) chloride concentration 5%–10% as NaCl. The presence of metals did not affect denitrification at the concentrations examined. H. denitrificans completely reduced nitrate and the intermediately produced nitrite at elevated chloride levels. Denitrification shifted pH towards circumneutral to alkaline values, where iron, zinc, copper and nickel were sequestered quantitatively from solution via bioprecipitation. The proposed simple, robust and low-cost biological treatment unit is advantageous compared to the conventional wastewater treatment, where metal precipitation is based on chemical neutralization and the problem of nitrate removal remains unresolved.

Recovery Method for Emergency Situations with Hazardous Substances Emission into the Atmosphere

The objective of this Article is development of a hazardous area extent reducing method in the atmosphere upon emergency situation occurrence with hazardous chemical and radioactive substances emission. To achieve the specified objective it is recommended to use deposition of gaseous, liquid and solid disperse hazardous particles from the atmosphere using artificial precipitation over a zone of emergency. For artificial intensification of precipitation, use of chemical and physical principles of impact on droplets formation processes in the area of clouds is proposed. A pyrotechnic composition was developed for chemical impact, which when combustion generates finely dispersed chemical centers of condensation and modifying components for hazardous chemical substances neutralization. Conducting the ionization of precipitation formation area by a strong impulse electromagnetic irradiation was proposed as a physical impact on the artificial precipitation formation processes. The laboratory study results confirmed the technical feasibility of this method implementation. To reduce the necessary radiator power, application of a multi-position radiators system with radiation focusing to one irradiation zone was proposed. The theoretical and experimental results obtained in the article are the base for development of emergency situation negative consequences reduction practical procedures through artificial precipitation initiation.

Strange quark star and the parameter space of the quasi-particle model

The properties of strange quark stars are studied within the quasi-particle model. Taking into account chemical equilibrium and charge neutrality, the equation of state (EOS) of -flavor quark matter is obtained. We illustrate the parameter spaces with constraints from two aspects: one is based on the astronomical results of PSR and GW 170 817 , and the other is based on the constraints proposed from the theoretical study of a compact star that the EOS must ensure the tidal deformability and support a maximum mass above . It is found that neither type of constraints can restrict the parameter space of the quasi-particle model in a reliable region and thus we conclude that the low mass compact star cannot be a strange quark star.

Gas-Neutralizing and Dust-Suppressing Stemming of Borehole Charges for Increasing the Environmental Safety of Explosion

Abstract The problem of environmental pollution during the explosive destruction of rocks in order to extract minerals is solved in the article. Two types of borehole charge stemming design have been developed, which, in addition to the function of locking the products of the explosion, allow completely neutralizing harmful gases. The first type is the stemming design, which includes the two-stage purification of harmful gases, formed during the explosive destruction of rocks, and is based on chemisorption of gases by quicklime or production waste and physicochemical sorption (adsorption) by zeolites. Such stemming can provide complete chemical neutralization of NO2 and CO2, as well as neutralization of CO by zeolites, during the explosion. The second type is stemming design, which includes chemisorption of gases by slaked lime. This type of stemming has a number of advantages over the previous one. It can not only provide complete chemical neutralization of NO2, CO2 and CO, but also allows abandoning zeolites, which significantly reduces the cost of its formation to obtain the effect of “irrigation” of the dust and gas cloud, which reduces the concentration of dust in the air after the explosion to provide a higher degree of conversion. The paper determines quantitative and qualitative characteristics of the adsorbent composition of the two types of stemming depending on the type of explosive, the amount and type of harmful gases formed during explosion, and the parameters of the borehole.

Complex flue gas cleaning of thermal power plants

Currently, there are significant emissions of pollutants from electric power facilities in our country. At the TPP, sulfur and nitrogen purification technologies are practically not used, most of the installed ash collectors operate with low efficiency and using outdated technology, and environmental indicators are significantly inferior to foreign analogues. At the same time, there is experience in the development and development on an industrial scale of various methods and tools that provide a significant reduction in emissions of particulate matter, sulfur oxides and nitrogen. The article considers an example of such a technology. For particle cleaning, a ceramic high-temperature filter with a catalytic coating is used to selectively remove nitric oxide when interacting with carbomide. The sulfur is removed by chemical neutralization with a lime sorbent.

Density-dependent quark mass model revisited: thermodynamic consistency, stability windows and stellar properties

In this work a density-dependent quark model is revisited, its thermodynamic consistency checked and the stability window for absolutely stable quark matter obtained. The hypotheses of both pure quark matter with equal quark chemical potentials and stellar matter subject to chemical stability and charge neutrality are investigated. The parameters that appear in the density-dependent mass and satisfy the Bodmer–Witten conjecture are then used to compute the masses and radii of strange stars. We show that the obtained values are compatible with the recently observed massive stars.

Improved method for tuberculocidal and mycobactericidal activity testing of disinfectants based on the European Standard EN 14348

Safe measurements to prevent the transmission of (multidrug-resistant) mycobacteria such as disinfection are essential in healthcare settings. In Europe chemical disinfectants are tested for their tuberculocidal and mycobactericidal efficacy by the internationally accepted test procedure described in EN 14348. However, especially for amine-based disinfectants, invalid results may occur by this procedure due to insufficient neutralization. In this multi-laboratory study the procedure described in EN 14348 was optimized by a combination of chemical neutralization and membrane filtration in order to obtain a valid and secure method especially for amine-based disinfectants.

Factors impacting the performance and microbial populations of three biofilters for co-treatment of H2S and NH3 in a domestic waste landfill site

Numerous volatile organic compounds and odors are generated when municipal solid wastes decompose in landfill sites. Three biofilters (BF-1, BF-2, and BF-3) were deployed to remove H2S and NH3 accumulated under high density polyethylene films in a 30,000 m2 area landfill site in North China. Results showed that the inlet concentrations of H2S and NH3 were 16.4–220.3 mg/m3 and 2.0–56.4 mg/m3, respectively. Outlet concentrations were reduced to 1.0–33.1 mg/m3 for H2S and 0–9.2 mg/m3 for NH3. The H2S removal efficiencies were around 91.1 % for BF-1, 87.0 % for BF-2, and 82.6 % for BF-3 in a steady state. The respective removals of NH3 were 92.0 %, 89.3 %, and 81.1 %. Thus, H2S and NH3 were both treated effectively by the biofilters. The intake load presented a seasonal variation. A high elimination capacity was obtained in the biofilter harvesting high inlet load. High throughput sequencing technology was utilized to assay the microbial populations in the biofilters. Pseudomonas sp., Alicyclobacillus sp., Sphingomonas sp., and Rhodanobacter sp, which were linked to the degradation of H2S and NH3, were isolated and identified. Their characteristics and distributions in the biofilters depended on the inlet concentration of substrates and the microenvironment within the packing materials. The results from this bio-product analysis indicated that most of H2S was bio-oxidized into sulfur and sulfate while NH3 was converted into nitrate or dissolved into the liquid phase mainly by absorption or chemical neutralization in the biofilters.

Characterization of Met25 as a color associated genetic marker in Yarrowia lipolytica

Yarrowia lipolytica offers an ideal host for biosynthesis of high value natural products and oleochemicals through metabolic engineering despite being restricted to a limited number of selective markers, and counter-selection achieved primarily with URA3. In this work, we investigate MET25, a locus encoding sulfide housekeeping gene within the cell, to be exploited as a standard genetic marker. Divalent lead supplemented in media induces lead sulfide (PbS) aggregation in MET25-deficient cells such that deficient cells grow brown/black, and cells with functional copies of MET25 grow white. Loss of MET25 did not induce strict auxotrophic requirements for methionine in Y. lipolytica, indicating MET25 deficiency could be rescued by alternative pathways. Plasmid and chromosomal-based complementation of MET25 in the met25 deficient cells on a double layer agar plate with nutrient gradients demonstrates delayed phenotype (white morphology) restoration, indicating post-transcriptional feedback regulation of methionine biosynthesis in this yeast. MET25 deficient Y. lipolytica could be used as an efficient whole-cell lead sensor with detection limit as low as 10 ​ppm of lead in drinking water. We further tested whether MET25 deficiency can be exploited to confer resistance to methyl-mercury through chemical neutralization and detoxification. Kinetic growth curves of wild type and MET25-deficient cells were obtained under varying concentrations of methylmercury and cellular toxicity to methyl mercury was calculated from the Hill equation. Our results indicate that methylmecury may not be used as the counter-selectable marker due to insignificant changes of growth fitness. This work demonstrates the utility of using MET25 as a sensitive lead sensor and the challenges of using MET25 as a counter-selectable genetic marker, as well as the complex regulation of methionine biosynthesis in Y. lipolyitca, which may shed lights for us to develop valuable biotechnological applications centering around the sulfur house-keeping metabolism of the nonconventional yeast.

Hydrolysis of Dimethyl Methylphosphonate (DMMP) in Hot-Compressed Water.

Dimethyl methylphosphonate (DMMP) is often used as a chemical surrogate for organophosphate nerve agents, as it exhibits similar physiochemical properties while having significantly lower toxicity. Continuous hydrolysis of DMMP in hot-compressed water is performed at temperatures from 200 to 300 °C, pressures of 20 and 30 MPa, and residence times from 30 to 80 s to evaluate the effects of pressure and temperature on reaction kinetics. DMMP hydrolysis is observed to follow pseudo-first-order reaction behavior, producing methylphosphonic acid and methanol as the only detectable reaction products. This is significant for the practical implementation of a continuous hydrothermal reactor for chemical warfare agent neutralization, as the process only yields stable, less-toxic compounds. Pressure has no discernible effect on the hydrolysis rate in compressed liquid water. Pseudo-first-order Arrhenius parameters are determined, with an activation energy of 90.17 ± 5.68 kJ/mol and a pre-exponential factor of 107.51±0.58 s-1.

Biogenic and Common Lime Characterization in Granular and Powder Forms and Their Application in Sowing Furrows for Soybean Crops

ABSTRACT The application of alternative and sustainable soil correctives to increase soil pH in sowing furrows can promote yield increases in soybean crops. The aim of this study was to characterize two different soil corrective sources in granular and powder forms and to evaluate the agronomic efficiency of their complementary application in a sowing furrow of a soybean crop. Two experiments were conducted. Regarding the first experiment, there were 5 treatments: control, biogenic lime powder, biogenic granular lime, common lime powder, and common granular lime. All applications were performed in a seeding furrow at a dose of 16 kg ha−1. The experiment was carried out in randomized blocks with five replicates. The second experiment involved the characterization of the sources and their forms by means of X-ray diffraction, total chemical analysis and neutralization power. The results showed that in comparison to the control, the application of correctives to increase soil pH in the sowing furrow promoted significantly higher growth and greater soybean yield, although the sources did not differ from each other. The soil pH corrective application in the sowing furrow was important for dissolution in the soil and consequently soybean yield. The neutralizing capacities of the correctives for all the granulometries tested were similar. Therefore, applying these soil pH correctives in granular or powder forms in sowing furrows might be an additional management alternative.

A 2D Titanium Carbide MXene Flexible Electrode for High-Efficiency Light-Emitting Diodes.

Although several transparent conducting materials such as carbon nanotubes, graphene, and conducting polymers have been intensively explored as flexible electrodes in optoelectronic devices, their insufficient electrical conductivity, low work function, and complicated electrode fabrication processes have limited their practical use. Herein, a 2D titanium carbide (Ti3 C2 ) MXene film with transparent conducting electrode (TCE) properties, including high electrical conductivity (≈11 670 S cm-1 ) and high work function (≈5.1 eV), which are achieved by combining a simple solution processing with modulation of surface composition, is described. A chemical neutralization strategy of a conducting-polymer hole-injection layer is used to prevent detrimental surface oxidation and resulting degradation of the electrode film. Use of the MXene electrode in an organic light-emitting diode leads to a current efficiency of ≈102.0 cd A-1 and an external quantum efficiency of ≈28.5% ph/el, which agree well with the theoretical maximum values from optical simulations. The results demonstrate the strong potential of MXene as a solution-processable electrode in optoelectronic devices and provide a guideline for use of MXenes as TCEs in low-cost flexible optoelectronic devices.

A Novel Fuzzy PI Control Approach for Nonlinear Processes

Classical fuzzy logic controllers fail to control nonlinear systems, which have strong nonlinearity around a certain operating point. In this case, if it is possible, the block-oriented modeling approach could be adopted to separate the highly nonlinear system into two subsystems as a linear time-invariant subsystem and a memoryless nonlinear subsystem. Thereby, a control operation could be carried out on the linear time-invariant block to control the whole system. Respecting this approach, here, a highly nonlinear system (neutralization process) was modeled by using the ARX–polynomial cascade connection. By this means, an opportunity is obtained that the inverse polynomial is utilized to be able to control the ARX subsystem by a classical fuzzy PI controller. And therefore, the fuzzy PI controller performance in controlling nonlinear processes was enhanced. The success of the new approach was confirmed by the results obtained from the control operation carried out in different pH regions for a chemical neutralization process. And also, the results show that the proposed control strategy is as successful as the multiregion fuzzy PI controller in the highly nonlinear process control.

Effect of the Refining Process on Total Hydroxytyrosol, Tyrosol, and Tocopherol Contents of Olive Oil.

The impact of the olive oil refining process on major antioxidant compound levels was evaluated by means of UHPLC analysis of lampante olive oils collected at different stages of the refining procedure (degumming, chemical and physical flash neutralization, bleaching, and deodorization). For this purpose, the evolution of the tocopherol fraction was investigated by means of the UHPLC-FL method, while the influence of the refining process on the total hydrolyzed phenolic content was assessed by measuring hydroxytyrosol and tyrosol levels after acid hydrolysis of the phenolic extracts. Refining was found to have a marked effect on total hydroxytyrosol and tyrosol contents, as they are completely removed in the early steps of the refining procedure. In contrast, the variation trends of tocopherols are not always clear-cut, and significant decreases in content from 7% to 16% were only revealed during refining in four out of nine samples. In addition, five of the nine refined oils showed final tocopherol concentrations higher than 200 mg/kg, the limit imposed by international standards regarding the content of such compounds in commercial olive oils. This study supports the need for a revision of the International Olive Oil Council (IOC) standard relative to the limit established for tocopherol addition to refined oils to avoid possible legal and economic trade issues.