Mixing Of Reagents Research Articles

Direct mechanocatalysis by resonant acoustic mixing (RAM).

We demonstrate the use of a metal surface to directly catalyse copper-catalysed alkyne-azide click-coupling (CuAAC) reactions under the conditions of Resonant Acoustic Mixing (RAM) - a recently introduced and scalable mechanochemical methodology that uniquely eliminates the need for bulk solvent, as well as milling media. By using a simple copper coil as a catalyst, this work shows that direct mechanocatalysis can occur in an impact-free environment, relying solely on high-speed mixing of reagents against a metal surface, without the need for specially designed milling containers and media. By introducing an experimental setup that enables real-time Raman spectroscopy monitoring of RAM processes, we demonstrate 0th-order reaction kinetics for several selected CuAAC reactions, supporting surface-based catalysis. The herein presented RAM-based direct mechanocatalysis methodology is simple, enables the effective one-pot, two-step synthesis of triazoles via a combination of benzyl azide formation and CuAAC reactions on a wide scope of reagents, provides control over reaction stoichiometry that is herein shown to be superior to that seen in solution or by using more conventional CuCl catalyst, and is applied for simple gram-scale synthesis of the anticonvulsant drug Rufinamide.

3D-printed chemiluminescence flow cells with customized cross-section geometry for enhanced analytical performance

Low force stereolithography is exploited for the first time for one-step facile fabrication of chemiluminescence (CL) flow-through cells that bear unrivalled features as compared to those available through milling or blowing procedures or alternative 3D printing technologies. A variety of bespoke cross-section geometries with polyhedral features (namely, triangular, square, and five-side polygon) as well as semicircular cross-section are herein critically evaluated in terms of analytical performance against the standardcircular cross-section in a flat spirally-shape format. The idea behind is to maximize capture of elicited light by the new designs while leveraging 3D printing further for fabrication of (i) customized gaskets that enable reliable attaching of the active mixing zone of the CL cell to the detection window, (ii) in-line 3D-printed serpentine reactors, and (iii) flow confluences with tailorable shapes for enhancing mixing of samples with CL reagents. Up to twenty transparent functional cells were simultaneously fabricated without inner supports following post-curing and surface treatment protocols lasting less than 5 h. In fact, previous attempts to print spirally-shaped cells in one-step by resorting to less cost effective photopolymer inkjet printing technologies were unsuccessful because of the requirement of lengthy procedures (>15 days) for quantitative removal of the support material. By exploiting the phthalazinedione-hydrogen peroxide chemistry as a model reaction, the five-side irregular pentagon cell exhibited superior analytical figures of merit in terms of LOD, dynamic range and intermediate precision as compared to alternative designs. Computational fluid dynamic simulations for mapping velocities at the entry region of the spiral cell corroborated the fact that the 5-side polygon cross-section flow-cell with Y-type confluence permitted the most efficient mixing of reagents and sample while enabling larger flow velocities near the inlet that contribute to a more efficient capture of the photons from the flash-type reaction. The applicability of the 3D-printed 5-side polygon CL cell for automatic determination of hydrogen peroxide using a computerized hybrid flow system was demonstrated for the analysis of high matrix samples, viz., seawater and saliva, with relative recoveries ranging from 83 to 103%.

Enhancing of detection resolution via designing of a multi-functional 3D connector between sampling and detection zones in distance-based microfluidic paper-based analytical device: multi-channel design for multiplex analysis.

One of the problems in the distance-based microfluidic paper-based analytical device (DB-µPAD) that limits the detection resolution is the mixing of reagents from the detection to the sampling zone or vice versa due to spreading by capillary action. In the present paper, to overcome mixing of the reagents in the zones, a multi-functional connector using a three-dimensional (3D) design has been developed externally to connect the two zones. Using such a novel design, it is acertained that there is no any mixing due to the dispersion of the reagents in the two zones. Interestingly, the simple 3D connector has other functions, such as its potential to be used as a masking zone and/or reaction zone whenever is needed. Based on this proposed 3D connector-based DB-µPAD, three parallel microchannels were built as detection zones with one sampling zone for multiplex analysis for the detection of Fe2+, Ni2+, and hardness of water. In the Ni2+ channel, the connector piece worked as both masking part and connection part. In the Fe2+ line, the connector served as the connector and reducing pad (Fe3+ to Fe2+ ions). While in the third channel, the connector has connection function only. Satisfactory limit of detection (LoD), accuracy, and precision were obtained using this design. The LODs obtained with the proposed design were 1.13, 0.62, and 1.87mg.L-1 for total hardness, Fe2+, and Ni2+, respectively.

Quantification of reagent mixing in liquid flow cells for Liquid Phase-TEM

Liquid-Phase Transmission Electron Microscopy (LP-TEM) offers the opportunity to study nanoscale dynamics of phenomena related to materials and life science in a native liquid environment and in real time. Until now, the opportunity to control/induce such dynamics by changing the chemical environment in the liquid flow cell (LFC) has rarely been exploited due to an incomplete understanding of hydrodynamic properties of LP-TEM flow systems. This manuscript introduces a method for hydrodynamic characterization of LP-TEM flow systems based on monitoring transmitted intensity while flowing a strongly electron scattering contrast agent solution. Key characteristic temporal indicators of solution replacement for various channel geometries were experimentally measured. A numerical physical model of solute transport based on realistic flow channel geometries was successfully implemented and validated against experiments. The model confirmed the impact of flow channel geometry on the importance of convective and diffusive solute transport, deduced by experiment, and could further extend understanding of hydrodynamics in LP-TEM flow systems. We emphasize that our approach can be applied to hydrodynamic characterization of any customized LP-TEM flow system. We foresee the implemented predictive model driving the future design of application-specific LP-TEM flow systems and, when combined with existing chemical reaction models, to a flourishing of the planning and interpretation of experimental observations.

Enabling Solution Processable COFs through Suppression of Precipitation during Solvothermal Synthesis.

Covalent organic frameworks (COFs) are crystalline, nanoporous materials of interest for various applications, but current COF synthetic routes lead to insoluble aggregates which precludes processing for practical implementation. Here, we report a COF synthesis method that produces a stable, homogeneous suspension of crystalline COF nanoparticles that enables the preparation of COF monoliths, membranes, and films using conventional solution-processing techniques. Our approach involves the use of a polar solvent, diacid catalyst, and slow reagent mixing procedure at elevated temperatures which altogether enable access to crystalline COF nanoparticle suspension that does not aggregate or precipitate when kept at elevated temperatures. On cooling, the suspension undergoes a thermoreversible gelation transition to produce crystalline and highly porous COF materials. We further show that the modified synthesis approach is compatible with various COF chemistries, including both large- and small-pore imine COFs, hydrazone-linked COFs, and COFs with rhombic and hexagonal topologies, and in each case, we demonstrate that the final product has excellent crystallinity and porosity. The final materials contain both micro- and macropores, and the total porosity can be tuned through variation of sample annealing. Dynamic light scattering measurements reveal the presence of COF nanoparticles that grow with time at room temperature, transitioning from a homogeneous suspension to a gel. Finally, we prepare imine COF membranes and measure their rejection of polyethylene glycol (PEG) polymers and oligomers, and these measurements exhibit size-dependent rejection and adsorption of PEG solutes. This work demonstrates a versatile processing strategy to create crystalline and porous COF materials using solution-processing techniques and will greatly advance the development of COFs for various applications.

Surface plasmon resonance tunable gold nanostar synthesis in a symmetric flow-focusing droplet device

Gold nanomaterials are known for their unique optical properties due to their localized surface plasmon resonance (LSPR). Controllable gold nanomaterials synthesis to tune LSPR of specific application demands is of great interest in the scientific community and is technically challenging to achieve in a conventional batch reactor. In this work, we tailored LSPR tunable gold nanostars (Au NS) using a symmetric flow-focusing droplet device after optimizing the flow parameters in 2D simulations. Simulations were used to represent the fluid interface within the device microchannels and helped to study the droplet evolution and their quantification. As nanomaterials synthesis in a droplet device demands the production of homogenous droplets and control over their size and production rate, we optimized the flow parameters from the simulation. By incorporating curved, sinusoidal geometries and semi-spiral microchannels, the mixing of reagents inside the droplet was improved for synthesizing heavily branched Au NS. The best performance was achieved when the flow rate of the shaping reagent was twice that of other reagents. As-synthesized Au NS are non-toxic, uniform and possess a small core diameter, large tip-to-tip length, negative surface zeta potential and red-shifted LSPR. These features are highly favourable for photothermal and photodynamic applications. Thus, our microfluidic platform can produce uniform droplets that provide sufficient mixing of reagents for the application-specific LSPR tunable synthesis of gold nanostars.

Microfluidic-assisted fiber production: Potentials, limitations, and prospects.

Besides the conventional fiber production methods, microfluidics has emerged as a promising approach for the engineered spinning of fibrous materials and offers excellent potential for fiber manufacturing in a controlled and straightforward manner. This method facilitates low-speed prototype synthesis of fibers for diverse applications while providing superior control over reaction conditions, efficient use of precursor solutions, reagent mixing, and process parameters. This article reviews recent advances in microfluidic technology for the fabrication of fibrous materials with different morphologies and a variety of properties aimed at various applications. First, the basic principles, as well as the latest developments and achievements of microfluidic-based techniques for fiber production, are introduced. Specifically, microfluidic platforms made of glass, polymers, and/or metals, including but not limited to microfluidic chips, capillary-based devices, and three-dimensional printed devices are summarized. Then, fiber production from various materials, such as alginate, gelatin, silk, collagen, and chitosan, using different microfluidic platforms with a broad range of cross-linking agents and mechanisms is described. Therefore, microfluidic spun fibers with diverse diameters ranging from submicrometer scales to hundreds of micrometers and structures, such as cylindrical, hollow, grooved, flat, core-shell, heterogeneous, helical, and peapod-like morphologies, with tunable sizes and mechanical properties are discussed in detail. Subsequently, the practical applications of microfluidic spun fibers are highlighted in sensors for biomedical or optical purposes, scaffolds for culture or encapsulation of cells in tissue engineering, and drug delivery. Finally, different limitations and challenges of the current microfluidic technologies, as well as the future perspectives and concluding remarks, are presented.

Closed EWOD-based low-cost portable thermal detection system for point-of-care applications

Electrowetting-on-Dielectric (EWOD) is a powerful technology for biological and chemical diagnostics. It offers advantages of low sample volume, high sensitivity, high throughput and the possibility of automation. Of special interest is a miniaturization of a thermal detection system by utilizing the EWOD technique since it can minimize effort while reducing cost and the system size. The present study describes the development of a closed EWOD device for droplet actuation that is integrated with thermal cycling and optical diagnostics. Important steps, including sample and reagent transportation, merging and mixing, and color detection, are performed on the integrated platform. The thermal module uses heating as well as Peltier elements and K-type thermocouples with a PID controller to perform precise thermal cycling needed in clinical and medical diagnostics. Experimentally recorded temperature distribution that is realized in the closed EWOD configuration is numerically validated using the COMSOL simulator. The efficacy of the integrated system is experimentally demonstrated by performing Fehling’s test for glucose detection in a glycerin solution. Furthermore, the device is used to demonstrate the transportation of a liquid drop of blood mimicking liquid at a relatively high temperature of 90 °C. The system thus developed is reliable, providing real-time proof-of-concept and the feasibility of building a low-cost point-of-care EWOD device. • A portable closed EWOD based medical diagnostic system with thermal cycling is demonstrated. • Thermal management using heating and cooling element is integrated with the closed EWOD device. • Temperature distribution within the device is measured experimentally and validated against simulation. • Droplet motion is successfully realized over the temperature range studied, providing real-time proof-of-concept. • The system developed is tested by performing Fehling’s test for glucose detection.

New Chemical Weapons Destruction Technologies as the Key to Successful Completion of Chemical Weapons Disarmament Process

The fulfillment of international obligations of the Russian Federation under the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction required the development and the creation of safe innovative industrial technologies and facilities for the destruction of chemical weapons. The purpose of this work is to give brief characteristics of the technologies for the destruction of chemical weapons developed and commercially implemented at various facilities. The destruction of chemical weapons was carried out at seven facilities specially designed and built for this purpose. These facilities were located in six regions of the country. The choice of technologies for the destruction (utilization) of chemical weapons was carried out on a competitive basis in the period from 1992 to 1995.The priority was given to the so-called two-stage technology. At the first stage, the toxic chemicals were extracted from the munitions or the containers and detoxified chemically in «soft» controlled conditions. Then the empty munitions were degassed. At the second stage, thermal neutralization or bituminization of the reaction masses was carried out with their subsequent burial. The two-stage technology for the destruction of mustard and mustard-lewisite mixtures was based on the interaction of toxic chemicals with an 80 ± 5% aqueous solution of monoethanolamine, which was supplied into the reactor at a temperature of 60–80 °C in the ratio toxic chemical: degassing formulation - 1:1.2 according to mass. The detoxification process was considered completed if the content of toxic chemicals in the reaction mass did not exceed 3,2×10 -3 %. To destroy lewisite, a «short scheme» in a jet-type reactor was implemented. The mixing of the initial reagents, lewisite and 20% alkali solution, was carried out using a nozzle of a special design, where lewisite was swirled with a special device (swirler) and supplied into the reactor. The first stage of the destruction of V-gases was carried out in munitions cases. The munitions were considered as chemical reactors. The process of detoxification of V-gases was considered completed when the residual content of toxic chemicals was at the level of 5×10 -4 %, and the reaction mass was delivered for thermal neutralization (second stage). In total, 39966,588 tons of toxic chemicals were destroyed. The whole number of destroyed containers with agents and chemical munitions amounted to 4,158,456 units. On September 27, 2017, the last chemical weapon was destroyed at the Kizner chemical weapons destruction facility, thus completing the process of complete destruction of chemical weapons stockpiles in the Russian Federation.

A film-lever actuated switch technology for multifunctional, on-demand, and robust manipulation of liquids

A lab-on-a-chip system with Point-of-Care testing capability offers rapid and accurate diagnostic potential and is useful in resource-limited settings where biomedical equipment and skilled professionals are not readily available. However, a Point-of-Care testing system that simultaneously possesses all required features of multifunctional dispensing, on-demand release, robust operations, and capability for long-term reagent storage is still a major challenge. Here, we describe a film-lever actuated switch technology that can manipulate liquids in any direction, provide accurate and proportional release response to the applied pneumatic pressure, as well as sustain robustness during abrupt movements and vibrations. Based on the technology, we also describe development of a polymerase chain reaction system that integrates reagent introduction, mixing and reaction functions all in one process, which accomplishes “sample-in-answer-out” performance for all clinical nasal samples from 18 patients with Influenza and 18 individual controls, in good concordance of fluorescence intensity with standard polymerase chain reaction (Pearson coefficients > 0.9). The proposed platform promises robust automation of biomedical analysis, and thus can accelerate the commercialization of a range of Point-of-Care testing devices.

Combustion of Layered Condensed Media Taking Into Account the Diffusive Mixing of Reagents

Combustion of Layered Condensed Media Taking Into Account the Diffusive Mixing of Reagents

Comparison between the Rotational Thromboelastometry (ROTEM) Delta device against the Cartridge-based Thromboelastography 6s and Quantra in a healthy third trimester pregnant cohort.

Rotational Thromboelastometry (ROTEM) Delta has been described in several postpartum hemorrhage algorithms, but this device requires pipetting and careful mixing of reagents to initiate the clotting reaction. In contrast, thromboelastography (TEG 6s) and the Quantra devices operate utilizing an automated pre-mixed cartridge that only requires a blood sample to start the clot strength analysis. We compared the correlation between 3 point of care viscoelastic testing (POCVT) devices to laboratory Clauss fibrinogen and platelets, their inter-device correlation, and the total running time difference between Quantra and ROTEM. A high correlation was noted between the Clauss fibrinogen and the fibrinogen parameters from ROTEM (r = 0.76-0.84, P < 0.0001), TEG6s (r = 0.71, P < 0.0001) and Quantra (r = 0.72, P = 0.0001). A moderate correlation between laboratory platelets and the ROTEM (r = 0.54;0.45, P < 0.0001; P = 0.0013) and Quantra (r = 0.66, P = 0.0001) parameters was noted. The inter-device correlation showed to be high when comparing the fibrinogen parameters of TEG6s and Quantra to that of ROTEM (r = 0.88 and 0.74, P < 0.0001, respectively). In contrast, a moderate correlation was noted between the platelet parameters of Quantra and ROTEM (r = 0.51, p = 0.0036). The Quantra device resulted 20.9min (95% CI -0.2 to 4.7, P = 0.07) faster than the ROTEM if the warming and pipetting of reagents of the latter were considered. All the POCVT devices demonstrated a high correlation to laboratory Clauss fibrinogen, making each beneficial for the early recognition and management of hypofibrinogenemia.

Droplet Microfluidic Device for Chemoenzymatic Sensing.

The rapid detection of pollutants in water can be performed with enzymatic probes, the catalytic light-emitting activity of which decreases in the presence of many types of pollutants. Herein, we present a microfluidic system for continuous chemoenzymatic biosensing that generates emulsion droplets containing two enzymes of the bacterial bioluminescent system (luciferase and NAD(P)H:FMN–oxidoreductase) with substrates required for the reaction. The developed chip generates “water-in-oil” emulsion droplets with a volume of 0.1 L and a frequency of up to 12 drops per minute as well as provides the efficient mixing of reagents in droplets and their distancing. The bioluminescent signal from each individual droplet was measured by a photomultiplier tube with a signal-to-noise ratio of up to 3000/1. The intensity of the luminescence depended on the concentration of the copper sulfate with the limit of its detection of 5 M. It was shown that bioluminescent enzymatic reactions could be carried out in droplet reactors in dispersed streams. The parameters and limitations required for the bioluminescent reaction to proceed were also studied. Hereby, chemoenzymatic sensing capabilities powered by a droplet microfluidics manipulation technique may serve as the basis for early-warning online water pollution systems.

A novel fabricated polyvinyl alcohol/ bentonite nanocomposite hydrogel generated into colloidal gas aphron

Polyvinyl alcohol/bentonite (PVA- Ben) nanocomposite hydrogel is commonly used as an adsorbent for removing many dye residues in wastewater treatment. In the present study, a novel polyvinyl alcohol/bentonite nanocomposite, (CGA-PVA-Ben) hydrogel, is fabricated by mixing polyvinyl alcohol and bentonite dispersions in the presence of a high shear force via a colloidal gas aphron (CGA) generator. X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and Fourier Transform Infrared (FTIR) spectroscopy methods are used to characterize both the novel (CGA-PVA-Ben) and also conventional (PVA-Ben) nanocomposite hydrogels. The results of EDS, XRD, and FTIR analyses show that the (CGA-PVA-Ben) hydrogel has the same bonds, functional groups, and exact composition as the (PVA-Ben) hydrogel. However, FE-SEM analysis demonstrates that the (CGA-PVA-Ben) has more porous and uneven surfaces. The presence of high shear forces during the mixing of polyvinyl alcohol and bentonite reagents in aphron generator reduces the mass density of hydrogel. Therefore, compared with neat hydrogel adsorbent, i.e., (PVA-Ben), the (CGA-PVA-Ben) has a unique characteristic behavior which is the adsorbent floatability after the adsorption process. This remarkable feature provides an alternative method in adsorption technology and it is an interesting advantage for easy removal of adsorbent from the contaminated effluents. Details of the adsorption characterization of this novel fabricated polyvinyl alcohol/ bentonite nanocomposite hydrogels will be discussed in a follow-up research paper.

SISTEM MONITORING SPEED SETTING PADA ROLLER MIXER BERBASIS MIKROKONTROLER ARDUINO UNO

Roller mixer is a laboratory tool that serves to mix blood samples and reagents. In this case, the substances that are mixed are blood and anti-clotting agents (coagulants). In the process of mixing the blood, the timer and the rotational value of the motor are set by the selector switch. The design of the speed setting of the roller mixer tool is made so that the user can control and monitor how much the value of the motor speed used is displayed on the 16x2 LCD display. This research will be conducted at the Electronics Laboratory of Sari Mutiara University, Helvetia District, Medan City. This type of research method is experimental research, namely conducting direct experiments. The components in monitoring this tool are microcontroller, display, timer setting, speed setting and roller. After carrying out the research process on the design of this tool, the measurement results obtained from the Infrared Sensor are displayed on the LCD, with a minimum speed measurement of 36, Medium 38 and a maximum of 44 rpm. With a comparison from a thacometer with an average value of Minimum 44 Medium 54 and maximum 56.

Abstract 2930: Intra- and inter-run repeatability assessment of the naica® 6-color digital PCR system for multiplex genetic detection

Abstract The genomic analysis of clinical samples, whether it be frozen tissue, FFPE or liquid biopsies, requires the ability to quantify low-level genetic aberrations in a complex DNA background with high precision and sensitivity. Stilla Technologies’ 6-color naica® system is an ultrasensitive, easy-to-use digital PCR technology capable of quantifying multiple biomarkers in a single reaction. The naica system workflow is comprised of optimized master mix reagents, microfluidic consumables, a 2-in-1 droplet generator and thermocycler, and a 6-color imager. For data analysis, the Crystal Miner analysis software allows for flexible sample analysis and inciteful data visualization. Altogether, the naica system workflow requires only a single pipetting step, thereby considerably limiting the variability contributed by the operator. The naica multiplex PCR MIX ensures optimal simultaneous quantification of multiple targets across the five-log dynamic range of the naica system, as well as robust quantification of low target concentrations in a highly abundant and complex DNA background. R² scores &amp;gt; 0.99 were obtained for all targets of a 6-color detection panel ranging from 0.2 to 13000 copies (cp)/µL. As repeatability is a key performance criterion to evaluate the quality of a digital PCR system and detection assay, we also assessed the intra- and inter-run repeatability of the naica® system with a 6-color assay. Three target concentrations from three different DNA sources were tested at 200, 2000, and 10,000 cp/μL. To allow robust statistical analysis on the means of concentration and variance of concentration, three runs of a total of 36 wells were performed for each target concentration using Stilla Technologies’ highly sensitive Sapphire chip. Our results showed that at each of the three tested concentrations, the inter-run and intra-run variability of the 6-color naica® system was less than 6%. For each of the three tested concentrations, no significant inter-run or intra-run differences (p&amp;lt;0.05, two-tailed Mann-Whitney statistical test) were found, neither on the concentration level nor on the variance of concentration level. The absence of a significant difference implies that among multiple runs neither the well position in the chip nor the chip position in the Geode or Prism6 instrument has a significant impact on the results. Hence, any sample, including positive and negative control samples, can be loaded anywhere on the chips without significantly impacting the results, confirming high performance while ensuring ultimate flexibility in the experiment design. Citation Format: Jean Fatien, Benjamin Foret, Oriane Gourdy, Allison C. Mallory. Intra- and inter-run repeatability assessment of the naica® 6-color digital PCR system for multiplex genetic detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2930.

Lithography-Free Technology for the Preparation of Digital Microfluidic (DMF) Lab-Chips with Droplet Actuation by Optoelectrowetting (OEW).

Electrically conducting liquid droplets can be activated and moved by electrowetting-on-dielectric (EWOD) and optoelectrowetting (OEW). An important application is droplet manipulation in digital microfluidics (DMF, lab-on-a-chip 2.0) as a chip-sized chemical laboratory. For spectroscopic analyses of chemical reactions, it is often necessary to prepare or examine the reagent droplets before, during, and after the reaction. With OEW, single droplets with volumes of 50–250 nl can be moved, analyzed, and merged in one pipetting step. To ensure analysis sensitivity in many applications, lab-chips should only be used once due to contamination of the surface and chemical modification of the layers by the droplets. Single-use chip preparation without a lithographic step, e.g., for the definition of the spacer layer, reduces efforts and costs. Here, exemplarily, we demonstrate the OEW-driven movement and mixing of chemical reagents in a simple color change reaction analyzed by absorption spectroscopy. Stripes made from the insulating tape serve as spacers between sub and superstrate, and any lithographic step can be avoided.

New Chemical Weapons Destruction Technologies as the Key to Successful Completion of Chemical Weapons Disarmament Process

The fulfillment of international obligations of the Russian Federation under the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction required the development and the creation of safe innovative industrial technologies and facilities for the destruction of chemical weapons. The purpose of this work is to give brief characteristics of the technologies for the destruction of chemical weapons developed and commercially implemented at various facilities. The destruction of chemical weapons was carried out at seven facilities specially designed and built for this purpose. These facilities were located in six regions of the country. The choice of technologies for the destruction (utilization) of chemical weapons was carried out on a competitive basis in the period from 1992 to 1995. The priority was given to the so-called two-stage technology. At the first stage, the toxic chemicals were extracted from the munitions or the containers and detoxified chemically in «soft» controlled conditions. Then the empty munitions were degassed. At the second stage, thermal neutralization or bituminization of the reaction masses was carried out with their subsequent burial. The two-stage technology for the destruction of mustard and mustard-lewisite mixtures was based on the interaction of toxic chemicals with an 80 ± 5% aqueous solution of monoethanolamine, which was supplied into the reactor at a temperature of 60–80 °C in the ratio toxic chemical: degassing formulation - 1:1.2 according to mass. The detoxification process was considered completed if the content of toxic chemicals in the reaction mass did not exceed 3,2×10-3%. To destroy lewisite, a «short scheme» in a jet-type reactor was implemented. The mixing of the initial reagents, lewisite and 20% alkali solution, was carried out using a nozzle of a special design, where lewisite was swirled with a special device (swirler) and supplied into the reactor. The first stage of the destruction of V-gases was carried out in munitions cases. The munitions were considered as chemical reactors. The process of detoxification of V-gases was considered completed when the residual content of toxic chemicals was at the level of 5×10-4%, and the reaction mass was delivered for thermal neutralization (second stage). In total, 39966,588 tons of toxic chemicals were destroyed. The whole number of destroyed containers with agents and chemical munitions amounted to 4,158,456 units. On September 27, 2017, the last chemical weapon was destroyed at the Kizner chemical weapons destruction facility, thus completing the process of complete destruction of chemical weapons stockpiles in the Russian Federation.

A microfluidic chemiluminescence biosensor based on multiple signal amplification for rapid and sensitive detection of E.coli O157:H7

E. coli O157:H7 has become a crucial foodborne pathogen with certain morbidity and mortality. However, the available methods still face the significant challenges including the improvement of detection specificity and sensitivity for real sample analysis. Herein, a microfluidic chemiluminescence biosensor based on a multiple signal amplification strategy was developed for rapid and ultrasensitive detection of E.coli O157:H7. The microfluidic device was consisted of an upstream snake-shape mixing channel and a downstream ship-shape microcavity with micropillar array for high efficient mixing of CL reagents, sufficient CHA amplification reaction and CL reaction. The multiple signal amplification was achieved by bacteria competitively bind to trigger catalytic hairpin assembly (CHA) and HRP-Au NPs catalyzed CL reaction. Based on the platform, the detection of target bacteria is converted to the detection of nucleic acid with a limit detection down to 130 CFU/mL, which is better or comparable to previously reported biosensors. Moreover, the whole analysis time was about 1.5 h with only 10 μL of sample. The biosensor exhibited an excellent recovery rate ranged from 90.0% to 110.0% and good selectivity to the target bacteria. Overall, this developed biosensor is a promising tool for ultrahigh sensitive and rapid detection of foodborne pathogens.

Parameter Optimization and Experimental Study of Jet Mixing Device Based on CFD

The parameters of jet mixing devices have an important influence on the mixing process, particle movement and interface regulation. At present, jet mixing devices are widely used in the coal slime flotation field, and their variable parameters lack systematic optimization. In this paper, the performance of reagent mixing and the distribution characteristics of flow field are taken as the evaluation indexes, and computational fluid dynamics (CFD) software (FLUENT) is used to optimize the variable parameters of the device. The results show that when the area ratio Ar=1.96~3.24, the throat-nozzle distance Le=0.2Dh~0.6Dh, the suction tube is located 1/4~1/2 Lz to the left of the nozzle outlet and is symmetrically arranged, the length of the throat tube L is from 6Dz to 12Dz, the mixing performance of the jet mixing device was optimal. The flow field distribution characteristics showed that the area ratio has a more significant effect. The larger the area ratio is, the more favorable the mixing of the working fluid and the injection fluid is. The throat-nozzle distance has little effect on the flow field distribution, and its optimal value ranges from 0.3Dh to 0.6Dh. The fog droplet size test showed that the dispersion effect was the best when the area ratio Ar=3.24. The diameter size test of the injected bubbles was carried out to verify the performance of the jet mixing device after parameter optimization. The experimental results and the simulation results confirm each other, which proves the correctness of the numerical simulation results.