scholarly journals The Mechanisms of Antibacterial Activity of Magnesium Alloys with Extreme Wettability

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5454
Author(s):  
Alexandre M. Emelyanenko ◽  
Alexander G. Domantovsky ◽  
Valery V. Kaminsky ◽  
Ivan S. Pytskii ◽  
Kirill A. Emelyanenko ◽  
...  
Keyword(s):  
Dispersion Medium ◽  
Experimental Studies ◽  
Ion Concentration ◽  
Nanosecond Laser ◽  
Bacterial Cells ◽  
Buffer Solution ◽  
Surface Microrelief ◽  
Bacterial Titer ◽  
Hierarchical Roughness ◽  
Phosphate Buffered Saline

In this study, we applied the method of nanosecond laser treatment for the fabrication of superhydrophobic and superhydrophilic magnesium-based surfaces with hierarchical roughness when the surface microrelief is evenly decorated by MgO nanoparticles. The comparative to the bare sample behavior of such surfaces with extreme wettability in contact with dispersions of bacteria cells Pseudomonas aeruginosa and Klebsiella pneumoniae in phosphate buffered saline (PBS) was studied. To characterize the bactericidal activity of magnesium samples with different wettability immersed into a bacterial dispersion, we determined the time variation of the planktonic bacterial titer in the dispersion. To explore the anti-bacterial mechanisms of the magnesium substrates, a set of experimental studies on the evolution of the magnesium ion concentration in liquid, pH of the dispersion medium, surface morphology, composition, and wettability was performed. The obtained data made it possible to reveal two mechanisms that, in combination, play a key role in the bacterial decontamination of the liquid. These are the alkalization of the dispersion medium and the collection of bacterial cells by microrods growing on the surface as a result of the interaction of magnesium with the components of the buffer solution.

scholarly journals Experimental study of the stratification of polydisperse emulsions in a cell with heated walls

2021 ◽  
Vol 2057 (1) ◽  
pp. 012041
Author(s):  
V I Valiullina ◽  
A I Mullayanov ◽  
A A Musin ◽  
L A Kovaleva
Keyword(s):  
Experimental Study ◽  
Deposition Rate ◽  
Thermal Convection ◽  
Dispersion Medium ◽  
Experimental Studies ◽  
Oil Emulsion ◽  
Convective Flows ◽  
A Cell ◽  
Increasing Temperature ◽  
Water In Oil Emulsion

Abstract Experimental studies of the gravitational deposition of a polydisperse water-in-oil emulsion under heat influence are carried out. When the rate of thermal convection exceeds the rate of precipitation, partial delamination of the emulsion is found to occur. The viscosity of the dispersion medium decreases with increasing temperature, which contributes to an increase in the deposition rate of water droplets in the emulsion. In the presence of a temperature difference, convective flows occur in the liquid, while the drops of the emulsion coagulate and form larger agglomerates that settle faster to the bottom of the cell.

scholarly journals Laser Formation of Periodic Micro- and Nanostructures on the Surface of Monocrystalline Silicon

2020 ◽  
Vol 21 (2) ◽  
pp. 215-218
Author(s):  
I. A. Mohylyak ◽  
O. Yu. Bonchyk ◽  
S. A. Korniy ◽  
S. G. Kiyak ◽  
D. I. Popovych
Keyword(s):  
Periodic Structures ◽  
Experimental Studies ◽  
Laser Pulses ◽  
Pulse Mode ◽  
Semiconductor Surface ◽  
Nanosecond Laser ◽  
Periodic Nanostructures ◽  
Nanosecond Laser Pulses ◽  
Electron Microscopes ◽  
Microscopic Investigations

Experimental studies of the features of the formation of laser-induced periodic nanostructures on the surface of silicon wafers in the zones of action of second, millisecond and nanosecond laser pulses are conducted in the work. The results of microscopic investigations by optical and electron microscopes of periodic structures formed on surfaces with crystallographic orientation (111), (100) are presented. The obtained results can be used to optimize the laser pulse mode for controlled micro- nanostructuring of the semiconductor surface.

scholarly journals Effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential / Vpliv naravnih protimikrobnih snovi na bakterijsko hidrofobnost, adhezijo in zeta potencial

2016 ◽  
Vol 67 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Marija Kurinčič ◽  
Barbara Jeršek ◽  
Anja Klančnik ◽  
Sonja Smole Možina ◽  
Rok Fink ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Bacterial Adhesion ◽  
Bacterial Cell ◽  
Early Stage ◽  
Experimental Studies ◽  
Adhesion Prevention ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Natural Antimicrobials ◽  
Cell Hydrophobicity

Abstract Interactions between bacterial cells and contact materials play an important role in food safety and technology. As bacterial strains become ever more resistant to antibiotics, the aim of this study was to analyse adhesion of selected foodborne bacterial strains on polystyrene surface and to evaluate the effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential as strategies of adhesion prevention. The results showed strain-specific adhesion rate on polystyrene. The lowest and the highest adhesion were found for two B. cereus lines. Natural antimicrobials ferulic and rosmarinic acid substantially decreased adhesion, whereas the effect of epigallocatechin gallate was neglectful. Similar results were found for the zeta potential, indicating that natural antimicrobials reduce bacterial adhesion. Targeting bacterial adhesion using natural extracts we can eliminate potential infection at an early stage. Future experimental studies should focus on situations that are as close to industrial conditions as possible.

scholarly journals Potential Use of Silica Nanoparticles for the Microbial Stabilisation of Wine: An In Vitro Study Using Oenococcus oeni as a Model

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1338
Author(s):  
Kamila Pachnowska ◽  
Krzysztof Cendrowski ◽  
Xymena Stachurska ◽  
Paweł Nawrotek ◽  
Adrian Augustyniak ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Oenococcus Oeni ◽  
Chemical Oxidation ◽  
Alternative Methods ◽  
Bacterial Cells ◽  
Silica Nanospheres ◽  
Cell Counts ◽  
Transmission Electron ◽  
Phosphate Buffered Saline

The emerging trend towards the reduction of SO2 in winemaking has created a need to look for alternative methods to ensure the protection of wine against the growth of undesired species of microorganisms and to safely remove wine microorganisms. This study describes the possible application of silica nanospheres as a wine stabilisation agent, with Oenococcus oeni (DSM7008) as a model strain. The experiment was conducted firstly on model solutions of phosphate-buffered saline and 1% glucose. Their neutralising effect was tested under stirring with the addition of SiO2 (0.1, 0.25, and 0.5 mg/mL). Overall, the highest concentration of nanospheres under continuous stirring resulted in the greatest decrease in cell counts. Transmission electron microscope (TEM) and scanning electron microscopy (SEM) analyses showed extensive damage to the bacterial cells after stirring with silica nanomaterials. Then, the neutralising effect of 0.5 mg/mL SiO2 was tested in young red wine under stirring, where cell counts were reduced by over 50%. The obtained results suggest that silica nanospheres can serve as an alternative way to reduce or substitute the use of sulphur dioxide in the microbial stabilisation of wine. In addition, further aspects of following investigations should focus on the protection against enzymatic and chemical oxidation of wine.

scholarly journals Effects of salinity changes on aquatic organisms in a multiple stressor context

2018 ◽  
Vol 374 (1764) ◽  
pp. 20180011 ◽  
Author(s):  
Josefa Velasco ◽  
Cayetano Gutiérrez-Cánovas ◽  
María Botella-Cruz ◽  
David Sánchez-Fernández ◽  
Paula Arribas ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Synergistic Effects ◽  
Experimental Studies ◽  
Aquatic Organisms ◽  
Joint Effect ◽  
Freshwater Ecosystems ◽  
Ion Concentration ◽  
Joint Effects ◽  
Multiple Stressor ◽  
Meta Analyses

Under global change, the ion concentration of aquatic ecosystems is changing worldwide. Many freshwater ecosystems are being salinized by anthropogenic salt inputs, whereas many naturally saline ones are being diluted by agricultural drainages. This occurs concomitantly with changes in other stressors, which can result in additive, antagonistic or synergistic effects on organisms. We reviewed experimental studies that manipulated salinity and other abiotic stressors, on inland and transitional aquatic habitats, to (i) synthesize their main effects on organisms' performance, (ii) quantify the frequency of joint effect types across studies and (iii) determine the overall individual and joint effects and their variation among salinity–stressor pairs and organism groups using meta-analyses. Additive effects were slightly more frequent (54%) than non-additive ones (46%) across all the studies ( n = 105 responses). However, antagonistic effects were dominant for the stressor pair salinity and toxicants (44%, n = 43), transitional habitats (48%, n = 31) and vertebrates (71%, n = 21). Meta-analyses showed detrimental additive joint effects of salinity and other stressors on organism performance and a greater individual impact of salinity than the other stressors. These results were consistent across stressor pairs and organism types. These findings suggest that strategies to mitigate multiple stressor impacts on aquatic ecosystems should prioritize restoring natural salinity concentrations. This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.

Effect of Concentration and pH of PBS to the Electrocatalytic Performance of Enzymatic Glucose Biosensor

2019 ◽  
Vol 290 ◽  
pp. 193-198
Author(s):  
Mohamad Nor Noorhashimah ◽  
Abdul Razak Khairunisak ◽  
Zainovia Lockman
Keyword(s):  
Modified Electrode ◽  
Indium Tin Oxide ◽  
Glucose Sensor ◽  
Glucose Biosensor ◽  
Glass Electrode ◽  
Ion Concentration ◽  
Glucose Detection ◽  
Buffer Solution ◽  
Electrocatalytic Performance ◽  
Ito Glass

Phosphate buffer saline (PBS) is commonly applied as an electrolyte for glucose sensor application because ion concentration and osmolality of PBS are similar to the human body. Therefore, it is important to study the effect of concentration and pH of PBS to the electrocatalytic performance of the modified electrode in glucose detection. In this study, the modification of indium tin oxide (ITO) glass electrode by utilizing iron oxide nanoparticles (IONP) coated with citric acid (CA), glucose oxidase (GOx) enzyme and Nafion layer (Nafion/Gox/IONP-CA/ITO) were performed. IONP was prepared by using the precipitation technique through formation of colloidal stable IONP in water at physiological pH. The size of IONP-CA precipitates was ~19 nm with maghemite (γ-Fe2O3) phase characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. Increasing the PBS concentration increased the electrocatalytic performance of the bioelectrode whereas pH of PBS buffer solution affected the GOx bioactivity. The modified electrode Nafion/Gox/IONP-CA/ITO displayed good electrochemical and electrocatalytic performance in glucose detection.

scholarly journals Antimicrobial susceptibility of H. pylori isolated from suspected patient using stool sample at Malali Hospital and Maternity Clinic Kaduna, Kaduna State – Nigeria

2021 ◽  
Vol 14 (3) ◽  
pp. 122-128
Author(s):  
Rabilu Sani
Keyword(s):  
Helicobacter Pylori ◽  
Stool Sample ◽  
Antimicrobial Susceptibility ◽  
Atmospheric Oxygen ◽  
Bacterial Cells ◽  
Selective Media ◽  
H Pylori ◽  
Phosphate Buffered Saline ◽  
Maternity Clinic ◽  
Environment Condition

The antimicrobial susceptibility of Helicobacter pylori isolated from suspected patient using stool sample at Beijing greatest college of health sciences and technology, Kaduna, demonstration clinic. The analyses were carried out to further understand the intestinal environment condition of the sample sites. As it has been noted that: it is difficult of growing Helicobacter pylori in a broth, hence, no specific enrichment has been proposed. Note: As everything present in the stomach would be found in the stools, hence there is no doubt that Helicobacter pylori can be eliminated via this route and successful culturing of Helicobacter pylori from the stool sample had been achieved. [4]. The stool was diluted to a 20% w/v solution of in phosphate buffered saline (PBS) and the suspension was sieved through a 250 um strainer before plating onto the selective media. The sample was passed through a series of dilution techniques and centrifugation before finally plating on to the deoxycholate citrate agar (selective) and incubates at 37oC under the microacrobic atmospheric oxygen concentration of 7 – 12% (O2) for four (4) days. Across the cultured, the cultured plate there was marked abundant of bacterial cells with some colonies having the characteristics of Helicobacter pylori which later sub-cultured and isolated for antimicrobial test.

scholarly journals ДОСЛІДЖЕННЯ ВПЛИВУ ПОКРИТТІВ І ТЕХНОЛОГІЧНИХ МЕТОДІВ ВИГОТОВЛЕННЯ НАПРЯМНИХ ЕЛЕМЕНТІВ НА ЇХ ЗНОСОСТІЙКІСТЬ

2021 ◽  
pp. 33-47
Author(s):  
Є. А. Фролов ◽  
Н. К. Резніченко ◽  
Є. С. Дерябкіна ◽  
С. І. Кравченко ◽  
В. В. Агарков ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Surface Hardening ◽  
Experimental Studies ◽  
High Hardness ◽  
Carbide Powder ◽  
Test Duration ◽  
Test Results ◽  
Detonation Spraying ◽  
Surface Microrelief ◽  
Diamond Burnishing

The matter of the experimental studies of the effect of coatings and technological methods of manufacturing guide elements of universal prefabricated readjustable tooling on their wear resistance are presented. The coatings investigated were made of VK15 carbide powder, which were applied by detonation spraying, and a titanium nitride-based coating produced by condensation with ion bombardment, as well as the surface hardening of guide elements by diamond burnishing for various steels: 20V, 12KhN3A, 40Kh, 38KhMYuA-B and others.During the process of diamond smoothing the roughness improves by 2 - 3 classes and the very nature of the roughness changes: a surface microrelief is created with rounded peaks and valleys instead of microroughness with sharp peaks and valleys, which are characteristic of surfaces after grinding. In this case the bearing surface of the samples increases essentially, and their running-in is accelerated. According to the results of tests under a load of 50, 75 and 100 kgf, a graph of the dependence of wear on the specific pressure was built and it was found that the wear of samples after burnishing decreases by 25 ... 40% compared to polished and at a load of 20 kgf/cm, respectively, is for steel 20 ... 2.7 and 1.9 μm, for steel 12XN3A – 2.3 and 1.6 μm, for steel 40X – 1.8 and 1.3 μm and for steel 38XMYUA – 1.4 and 0.8 μm.With increasing the load the wear of the ground specimens increases sharply, and for the flattened specimens this process is much slower. Based on the test results, graphs of the wear rate were plotted depending on the test duration, as well as for wear in relation to the number of cycles. According to the test results, it was found that steel 38KhMYuA has less wear, which is associated with its high hardness and insignificant tendency to metal seizure. Based on the research results, it was found that different methods of processing parts (previous) grinding and diamond burnishing have different wear. It has been found that diamond burnishing is a very effective surface hardening process.As a result of the tests carried out, it was found that the best performance in testing for wear resistance obtained for a column with TiN coating, the thickness of which does not exceed 0.1 μm, is 5 - 6 times less than the wear resistance of columns with a hard-alloy coating. For the system of directly changeable dies, a pair is recommended, which includes a guide column with a detonation coating VK15 and a holder (sleeve) with a CIB coating based on TiN, since these coatings showed high performance properties and had practically no wear.

scholarly journals Bacteriophages as an Alternative Strategy for Fighting Biofilm Development

2014 ◽  
Vol 63 (2) ◽  
pp. 137-145 ◽  
Author(s):  
SYLWIA PARASION ◽  
MAGDALENA KWIATEK ◽  
ROMUALD GRYKO ◽  
LIDIA MIZAK ◽  
ANNA MALM
Keyword(s):  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Bacterial Resistance ◽  
Bacterial Species ◽  
Experimental Studies ◽  
Alternative Methods ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Coagulase Negative Staphylococci ◽  
Biofilm Development

The ability of microbes to form biofilms is an important element of their pathogenicity, and biofilm formation is a serious challenge for today's medicine. Fighting the clinical complications associated with biofilm formation is very difficult and linked to a high risk of failure, especially in a time of increasing bacterial resistance to antibiotics. Bacterial species most commonly isolated from biofilms include coagulase-negative staphylococci, Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. The frequent failure of antibiotic therapy led researchers to look for alternative methods and experiment with the use of antibacterial factors with a mechanism of action different from that of antibiotics. Experimental studies with bacteriophages and mixtures thereof, expressing lytic properties against numerous biofilm-forming bacterial species showed that bacteriophages may both prevent biofilm formation and contribute to eradication of biofilm bacteria. A specific role is played here by phage depolymerases, which facilitate the degradation of extracellular polymeric substances (EPS) and thus the permeation of bacteriophages into deeper biofilm layers and lysis of the susceptible bacterial cells. Much hope is placed in genetic modifications of bacteriophages that would allow the equipping bacteriophages with the function of depolymerase synthesis. The use of phage cocktails prevents the development of phage-resistant bacteria.

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