Treatment Of Liquid Media Research Articles

Features of distribution of electric field strength and current density in the reactor during treatment of liquid media with high-voltage pulse discharges

Purpose. Development and use of a mathematical model of the stages of formation of high-voltage pulse discharges in gas bubbles in the discharge gap «rod-plane» to identify the features of the electric field intensity distribution in the reactor and determine the current density in the load during disinfection and purification of liquid media by high-voltage pulse discharges and find the most rational treatment. Methodology. To achieve this goal, we used computer modeling using the finite element method as a method of numerical analysis. An experimental reactor model was created that takes into account the dynamics of discharges in gas bubbles in water. The equations describing the system include the generalized Ampere equation, the Poisson equation and the electric displacement equation, taking into account the corresponding initial and boundary conditions, as well as the properties of materials. The dependence of the potential of a high-voltage electrode on time has the form of a damped sinusoid, and the specific electrical conductivity in a gas bubble is a function of time. Processes occurring at the front of the voltage pulse from 0 to 20 ns are considered. Results. It is shown that with an increase in conductivity and high-voltage potential to amplitude values in a gas bubble, the electric field strength in the water layer in the reactor reaches 70 kV/cm, and it is in the water layer that there is a strong electric field. The calculations show that already by 19th ns the density of conduction currents in water prevails over that of displacement currents. At the same time, additional inclusions in the water significantly affect the distribution of electric field strength and current density, creating a significant difference in their values at the boundaries of the interface between the bubble, conductive element and water. Originality. A simulation of the dynamics of transient discharge processes in a gas bubble and a layer of water with impurities was carried out, including an analysis of the distribution of the electric field strength and current density in a system with rod-plane electrodes in the phase transition section of a gas bubble-water. This approach allows us to reveal the features of processes in reactors and to investigate the influence of phase transitions on the distribution of electrophysical quantities. Practical value. Computer simulations confirm the prospect of using nanosecond discharges generated in gas bubbles within a volume of water for widespread industrial use and are of great interest for further experimental and theoretical research. References 25, figures 9.

Antibacterial Effect of Acoustic Cavitation Promoted by Mesoporous Silicon Nanoparticles.

As-prepared mesoporous silicon nanoparticles, which were synthesized by electrochemical etching of crystalline silicon wafers followed by high-energy milling in water, were explored as a sonosensitizer in aqueous media under irradiation with low-intensity ultrasound at 0.88 MHz. Due to the mixed oxide-hydride coating of the nanoparticles' surfaces, they showed both acceptable colloidal stability and sonosensitization of the acoustic cavitation. The latter was directly measured and quantified as a cavitation energy index, i.e., time integral of the magnitude of ultrasound subharmonics. The index turned out to be several times greater for nanoparticle suspensions as compared to pure water, and it depended nonmonotonically on nanoparticle concentration. In vitro tests with Lactobacillus casei revealed a dramatic drop of the bacterial viability and damage of the cells after ultrasonic irradiation with intensity of about 1 W/cm2 in the presence of nanoparticles, which themselves are almost non-toxic at the studied concentrations of about 1 mg/mL. The experimental results prove that nanoparticle-sensitized cavitation bubbles nearby bacteria can cause bacterial lysis and death. The sonosensitizing properties of freshly prepared mesoporous silicon nanoparticles are beneficial for their application in mild antibacterial therapy and treatment of liquid media.

УЛЬТРАЗВУК: ЭФФЕКТИВНОСТЬ ПРИМЕНЕНИЯ И ТЕХНИЧЕСКИЕ СРЕДСТВА

The purpose of research is to evaluate the effectiveness of ultrasound for the treatment of components of diesel mixed fuel (DMF).Ultrasonic vibrations can change the aggregate state of a substance, disperse, emulsify it, change the rate of diffusion, crystallization and dissolution of substances, activate chemical reactions, intensify technological processes. The use of ultrasonic vibrations in the treatment of liquid media gives them new proper-ties, which lead to the widespread use of ultrasound in various industrial processes. Currently, biological fuels are widely used as motor fuel in diesel engines of automotive engineering. One of the types of liquid biological fuels is diesel mixed fuel (DMF), the components of which are commercial oil diesel fuel and any vegetable oil produced from oilseeds (canola, ginger, oil radish, flax oil, wood, white mustard, soybean, Abyssinian crab, etc.). For the mix-ing of oil and vegetable components directly «on Board» of automotive equipment, static mixers are usually used, which do not fully provide high-quality mixing of components and processing of DMF by ultrasound. The ultrasonic mixer developed and manufactured by the authors due to high-frequency oscillations of the piezoe mitter allows not only to mix biological and oil components of the mixed fuel qualitatively, but also to process them by ultrasound with a radiation frequency of 25 kHz to obtain a homogeneous fine composition, which leads to a smaller decrease in engine power and a smaller increase in the specific effective consumption of the mixed fuel compared to the operation of the diesel on the untreated ultrasound mixed fuel.

Factors affecting the character of plasma discharge with electrolytic cathode at a fixed pressure

The influence of process parameters of plasma chemical treatment of aqueous solutions on the plasma discharge behavior at different values of the current, fixed pressure and the interelectrode gap was investigated in the paper. This was done to identify additional factors that affect the characteristics of the discharge - fluid system. As an electrolytic cathode, distilled and tap water, as well as CuSO 4 and AgNO 3 solutions in distilled water, were used. It was found that one of the factors affecting the gas-plasma discharge are charged bubbles in the electrolytic cathode layer, in the case when the metal electrode is put down in it. It was determined that bubbles could play a significant role in the delivery of charged particles to the gas-plasma discharge zone. In addition, microdischarges, emerging at a current I>125mA in gas bubbles are an additional source of charged particles. The results will be used to create a refined mathematical model of plasma chemical treatment of liquid media.

Drug Uptake, Lipid Rafts, and Vesicle Trafficking Modulate Resistance to an Anticancer Lysophosphatidylcholine Analogue in Yeast

The ether-phospholipid edelfosine, a prototype antitumor lipid (ATL), kills yeast cells and selectively kills several cancer cell types. To gain insight into its mechanism of action, we performed chemogenomic screens in the Saccharomyces cerevisiae gene-deletion strain collection, identifying edelfosine-resistant mutants. LEM3, AGP2, and DOC1 genes were required for drug uptake. Edelfosine displaced the essential proton pump Pma1p from rafts, inducing its internalization into the vacuole. Additional ATLs, including miltefosine and perifosine, also displaced Pma1p from rafts to the vacuole, suggesting that this process is a major hallmark of ATL cytotoxicity in yeast. Radioactive and synthetic fluorescent edelfosine analogues accumulated in yeast plasma membrane rafts and subsequently the endoplasmic reticulum. Although both edelfosine and Pma1p were initially located at membrane rafts, internalization of the drug toward endoplasmic reticulum and Pma1p to the vacuole followed different routes. Drug internalization was not dependent on endocytosis and was not critical for yeast cytotoxicity. However, mutants affecting endocytosis, vesicle sorting, or trafficking to the vacuole, including the retromer and ESCRT complexes, prevented Pma1p internalization and were edelfosine-resistant. Our data suggest that edelfosine-induced cytotoxicity involves raft reorganization and retromer- and ESCRT-mediated vesicular transport and degradation of essential raft proteins leading to cell death. Cytotoxicity of ATLs is mainly dependent on the changes they induce in plasma membrane raft-located proteins that lead to their internalization and subsequent degradation. Edelfosine toxicity can be circumvented by inactivating genes that then result in the recycling of internalized cell-surface proteins back to the plasma membrane.

PH-changes during pulsed electric field treatments — Numerical simulation and in situ impact on polyphenoloxidase inactivation

Abstract Pulsed electric field (PEF) treatment of liquid media was investigated with focus on the pH shifts occurring in a batch parallel plate electrode treatment chamber. A numerical simulation of pH-shifts during PEF application was performed, which was experimentally verified by the application of an optical method based on digital image processing. Numerical, as well experimental results showed pH-shifts of up to 4.04 units already after a treatment time of 34 μs at electric field strength of 10 kV/cm. As a result, pH values of 10.9 and 3.3 were observed at the cathode and anode respectively after PEF treatment of a salt solution with an initial pH of 7.1. Furthermore, it was shown that the PEF treatment may cause partial PPO inactivation not directly related to the electric field impact on the enzyme. This finding contributes to the understanding of PEF side effects, such as electrochemical reactions and pH changes during PEF treatments. Industrial Relevance Microbial and enzyme inactivation by PEF processing depends not only on treatment parameters, such as electric field strength, pulse number, temperature and frequency, but also on food properties, such as electrical conductivity, ion strength and pH. It has been widely reported that pH alters the microbial inactivation by PEF and also that PEF can produce pH-shifts. The presented investigation contributes to the understanding of pH-shifts by the application of PEF processing and the application of a simple digital imaging method for measuring and analyzing the pH during the PEF treatment, as well as, the understanding on PPO inactivation due to pH-shifts during PEF treatments.

Effect of structural characteristics of rotary-disk mixers on hydrodynamic regimes used for treatment of liquid media

Among mixing equipment, mixers with effective members in the form of alternating stationary and rotating perforated disks – rotary-disk mixers – have become highly recommended in practice. This study demonstrates how the arrangement of perforations on the disks of the rotor and stator, and their size and geometric shape affect hydrodynamic phenomena that develop during the treatment of liquid media.

THE EFFECT OF SOME FUNGICIDES AND TOTAL SAPONIN ON SELECTED CHEMICAL COMPONENTS OF CERTAIN FUNGI

The present study aimed to evaluate the effect of total saponin (TS) extracted from mulberry root bark and some fungicides using EC50 for each on the chemical components (total soluble sugars, free amino acids or total protein) and some enzymes (amylase, peroxidase, catalase, polyphenol oxidase (PPO), protease, polygalacturonase (PG), polymethyl esterase (PME) and cellulase of certain fungi i.e. Al. alternata, B. cinerea, F. oxysporum, R. solani and S. rolfsii. Electrophoresis studies were carried out on selected fungi grown in liquid media treated with total saponin at EC50 comparing with untreated media. Results concluded that, TS and carboxin fungicide decreased the biochemical components F. oxysporum, R. solani and S. rolfsii. Thiophanate-methyl and TS decreased total soluble sugars, free amino acids and total protein. The inhibition percentage of free amino acids and total protein in B. cinerea treated with thiophanate-methyl were 37.0 and 43.1, respectively, compared with the untreated controls. Amylase activity produced by B. cinerea treated with TS or thiophanate-methyl was decreased comparing with the untreated control. PPO activity was completely inhibited in B. cinerea when liquid media was treated with thiophanate-methyl. The reduction of catalase and protease activities was recorded in B. cinerea treated with TS or thiophanate-methyl and compared with the untreated control. Thiophanate-methyl induced a significant (p < 0.01) decrease in peroxidase activity produced by B. cinerea comparing with the untreatment, while the treatment with TS induced non significant decrease in peroxidase activity compared with the untreated control. Adding TS to liquid medium was more effective than thiophanate-methyl in reducing cellulase and PG activities produced by B. cinerea. Also, the treatment of liquid media with TS or thiophanate-methyl caused highly inhibition in PME activity, which reached 62.3 and 65.4%, respectively. The reduction of free amino acids and total protein were observed in Al. alternata treated with TS or copper sulfate, which recorded 24.3, 32.0% and 29.9, 46.2%, respectively, of that produced in untreated media. Amylase activity produced by Al. alternata was completely inhibited other treatment with TS, while copper sulfate caused significant (p < 0.001) decrease in this enzyme compared to the untreated control. In contract, TS expressed non significant decrease in PPO activity, but, copper sulfate expressed a significant (p < 0.01) decrease in PPO activity produced by Al. alternata. TS and copper sulfate caused greatly decrease and significant (p < 0.01) protease activity comparing with the untreated control. The inhibition of protease activity for treated Al. alternata recorded 48.8 and 53.5%, respectively. TS induced non significant decrease in preoxidase activity, while, copper sulfate caused a low significant (p < 0.05) decrease in the enzyme activity produced by Al. alternata compared to the untreatment. In contract, TS was more effective than copper sulfate on the reduction of cellulase and PG activities. The electrophoresis studies showed that S. rolfsii was more sensitive to TS comparing with the other selected fungi.

Power determination for small-volume rotary disintegrator-mixers used for the treatment of liquid media

It is noted that simple and reliable mechanization is required for continuity of a production process involving the treatment of liquid media, and regulation of their mixing parameters over a broad range. It is demonstrated that a production mixture with required properties can be obtained with a minimum of energy expenditures when rotary mixers are used. A small-volume unit with working elements in the form of perforated disks — rotary disintegrator-mixer — is described. As a result of this structural layout, the unit satisfies requirements set forth for modern production mixing equipment. Since the power consumed by the unit is a basic parameter characterizing the treatment effectiveness of production media, a relationship is derived for determination of the given amount and structural parameters, depending on the properties of the mixture being treated. Comparison of experimental and theoretical data enable us to conclude that the proposed model adequately describes actual processes.

On convection phenomena during high pressure treatment of liquid media

In the current contribution, investigations of the high hydrostatic pressure process up to 400 MPa and temperatures up to 353 K are carried out by means of dimensional analysis. The thermofluiddynamical mechanisms are analysed for three different sizes of a high pressure chamber, two different pressure generation systems and two model-fluids that differ in viscosity. Forced convection during compression/decompression and free convection during constant pressure phase are considered separately. The results contain process parameter study based on dimensionless numbers derived from conservation equations of mass, momentum and energy. Either dimensionless process parameters or the fluid dynamical and thermodynamical time scales are presented as a function of pressure and temperature. Relations according to heat transfer and fluid flow mechanisms during high pressure treatment are discussed.

Chromosome doubling procedures of onion (Allium cepa L.) gynogenic embryos.

A novel approach for chromosome doubling that consists of treating embryos instead of parts of micropropagated plants was investigated. Following 2-year trials, amiprofos-methyl (APM) was found to be superior to oryzalin on the basis of a lower toxicity, and we were able to narrow the range of concentrations of APM. The addition of 2% dimethyl sulphoxide (DMSO) and 1% Triton X-100 to 25 microM APM had no effect in all treatments. A final experiment with 6,658 embryos demonstrated that a 2-day treatment in liquid media supplemented with 50 microM APM was the most successful with respect to chromosome doubling-36.7% of the plants were diploid-but the survival rate was reduced to 52.5% of that of the non-treated control. A 2-day treatment in liquid medium supplemented with 25 microM APM or a 2-day treatment on solid medium with 50 microM APM resulted in the production of diploids at a frequency of 28.9% and 21.3%, respectively. These may represent alternative methods for chromosome doubling since compared to the untreated control these two treatments reduced the survival rate by only about 24%. Final ploidy and fertility of the large proportion of induced mixoploid plants (up to 30.3%) need to be evaluated in further studies.

Cryopreservation of horse-chestnut (Aesculus hippocastanum L. ) somatic embryos using three different freezing methods

Cryopreservation of somatic embryos of Aesculus hippocastanum L. cultured on nutritive media containing abscisic acid (ABA) at concentrations of 0.75 μM, 7.5 μM and 75.0 μM was evaluated for three cooling methods: (i) slow freezing with cryoprotectants, (ii) fast freezing with cryoprotectants, and (iii) fast freezing with desiccation techniques. The ‘cryoprotectant’ freezing techniques included the embryo pretreatment on ABA containing medium for 4 days, followed by cryoprotective treatment in liquid medium containing 0.5 M dimethylsulfoxide, 0.5 M glycerol, 1.0 M sucrose, and cooled at slow, and rapid rates. Embryos pretreated on a medium containing 0.75 μM ABA, and cooled to −35 °C at 1°C /min, held for 30 min at this transfer temperature and then immersed in liquid nitrogen (LN) had the best embryo recovery (43%). The ‘desiccation’ method involved an air drying step of similar ABA-pretreated, non-cryoprotected embryos followed by rapid cooling. Embryos precultured on 0.75 μM ABA, then subjected to a 4 h period of air desiccation (water content reduction to 13%) showed about the same level of survival (46%) as found with the ‘cryoprotectant’ slow freezing technique. The air-dry ‘desiccation’ method is easier to apply than the more complicated ‘cryoprotectant’ method.

Transformation of an Australian Variety of Carica papaya Using Microprojectile Bombardment

We have developed a method for the stable transformation and regeneration of a dioecious Australian cultivar of Carica papaya (papaw or papaya) by microprojectile bombardment. This method was developed after investigation of both zygotic and somatic embryos as target tissue and optimisation of a number of parameters using transient expression of the uidA reporter gene. The tissue culture regime prior to bombardment was critical in optimisation of transformation. Factors such as age of embryos and various treatments prior to bombardment, increased transient expression by up to 22-fold. Highest uidA transient expression results were obtained when somatic embryos 3 weeks since last subculture on solid medium were given a 3 day treatment in liquid medium, and a 2 h osmotic treatment pre- and post-bombardment. Stably transformed plants were obtained 6 months after bombardment using this system. Transformation efficiency was high with two experiments yielding 45% and 37.5% of bombarded plates regenerating plantlets on media containing kanamycin. The presence of both the uidA and aphA genes, (selectable marker) which code for the enzymes β-glucuronidase (GUS), and neomycin phosphotransferase II (NPTII) respectively, was confirmed in regenerated plantlets by Southern hybridisation.