scholarly journals Comparative Study of Ag Nanostructures: Molecular Simulations, Electrochemical Behavior, and Antibacterial Effect

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Álvaro de Jesús Ruíz-Baltazar ◽  
Simón Yobanny Reyes-López ◽  
D. Larrañaga ◽  
R. Pérez
Keyword(s):  
Cyclic Voltammetry ◽  
Ethylene Glycol ◽  
Comparative Study ◽  
Sodium Borohydride ◽  
Electrochemical Behavior ◽  
Antibacterial Effect ◽  
Chemical Reduction ◽  
Molecular Simulations ◽  
The Other ◽  
E Coli

Nanoparticles of Ag with different sizes and structures were obtained and studied. Two methods for reductions of Ag ions were employed, chemical reduction by sodium borohydride and ethylene glycol. Cuboctahedral and icosahedral structures were obtained. Molecular simulations were carried out in order to evaluate the reactivity of both structures. On the other hand, the electrochemical activity and antibacterial effect (E. coli) of the cuboctahedral and icosahedral structures were measured experimentally. The results obtained by molecular simulation, cyclic voltammetry, and antibacterial effect were compared and discussed in this work.

scholarly journals Surfactant-free synthesis of carbon-supported silver (Ag/C) nanobars as an efficient electrocatalyst for alcohol tolerance and oxidation of sodium borohydride in alkaline medium

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Santanu Dey ◽  
Pradipta Chakraborty ◽  
Dhiraj Kumar Rana ◽  
Subhamay Pramanik ◽  
Soumen Basu
Keyword(s):  
Cyclic Voltammetry ◽  
Ethylene Glycol ◽  
Alkaline Medium ◽  
Sodium Borohydride ◽  
Metallic Silver ◽  
Alcohol Tolerance ◽  
Current Ratio ◽  
X Ray ◽  
Scan Rate ◽  
Borohydride Oxidation

AbstractWe have synthesized carbon-supported silver (Ag/C) nanobars by a simple surfactant-free hydrothermal method using glucose as the reducing reagent as well as the source of carbon in Ag/C nanobars. Physicochemical characterization of the materials was performed by X-ray Diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The XRD pattern confirmed the presence of a pure metallic silver phase. No carbon phase was detected, which indicates that the carbon exists mainly in the amorphous form. The electrocatalytic activity of Ag/C in different electrolyte solutions such as 0.5 M NaOH, 0.5 M NaOH + 1 M ethanol (EtOH), 0.5 M NaOH + 1 M ethylene glycol (EG), and 0.5 M NaOH + 0.01 M NaBH4 (sodium borohydride) was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) study. Alcohol tolerance of the catalysts was also established in the presence of ethanol and ethylene glycol. The forward-to-backward current ratio from cyclic voltammetry (CV) study of Ag/C-20 (20 h) in 0.5 M NaOH + 1 M ethanol solution at 100 mV s−1 scan rate is 4.13 times higher compared to that of Ag/C-5 (5 h). Hence, Ag/C-20 is a better candidate for the tolerance of ethanol. In the presence of ethylene glycol (1 M) in 0.5 M NaOH solution, it is obtained that the forward-to-backward current ratio at the same scan rate for Ag/C-20 is lower than that in the presence of ethanol. The durability of the catalyst was studied by chronoamperometry measurement. We studied the electrochemical kinetics of Ag/C catalysts for borohydride oxidation in an alkaline medium. The basic electrochemical results for borohydride oxidation show that Ag/C has very well strength and activity for direct borohydride oxidation in an alkaline medium. The reaction of borohydride oxidation with the contemporaneous BH4−. hydrolysis was noticed at the oxidized silver surface. Among all the synthesized Ag/C catalysts, Ag/C-20 exhibited the best electrocatalytic performance for borohydride oxidation in an alkaline medium. The activation energy and the number of exchange electrons at Ag/C-20 electrode surface for borohydride electro-oxidation were estimated as 57.2 kJ mol−1 and 2.27, respectively.

Survival of bacteria on wood and plastic particles: Dependence on wood species and environmental conditions

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 72-81 ◽  
Author(s):  
Annett Milling ◽  
Rolf Kehr ◽  
Alfred Wulf ◽  
Kornelia Smalla
Keyword(s):  
Wood Species ◽  
Antibacterial Effect ◽  
The Other ◽  
Marker Genes ◽  
Bacterial Dna ◽  
E Coli ◽  
Hygroscopic Properties ◽  
Independent Analysis ◽  
Blot Hybridisation ◽  
Southern Blot Hybridisation

AbstractThe survival of two hygienically relevant bacteria,Escherichia colipIE639 andEnterococcus faecium, was followed on wooden sawdust of seven different European woods (pine, spruce, larch, beech, maple, poplar, and oak) versus polyethylene chips by using cultivation-dependent and molecular-based methods in parallel. The survival of the bacteria on wood was dependent on various factors such as the wood species, the type of the inoculated bacterium, the ambient temperature, and humidity. The bacterial titre decreased fastest on pine followed by oak compared to the other woods and plastic. Cultivation-independent analysis employing DNA extraction, Southern blot hybridisation, and PCR-based detection of marker genes of the test bacteria confirmed this result. The decline in bacterial numbers correlated with the decrease of bacterial DNA in the samples. Amounts of DNA ofE. coliandE. faeciumrecovered from pine and oak-wood sawdust were generally lower compared to the other woods and plastic.The presented study shows that pine and oak exhibit substantially better hygienic performance than plastic and indicates an antibacterial effect caused by a combination of the hygroscopic properties of wood and the effect of wood extractives.

scholarly journals ELECTROCHEMICAL BEHAVIOR OF 5-(PYRID-3-YL)-10,15,20-TRIPHENYLPORPHYRIN AND ITS Co-, (Py)Co-COMPLEXES

2018 ◽  
Vol 59 (2) ◽  
pp. 7
Author(s):  
Nadezhda M. Berezina ◽  
Nataliya N. Tumanova ◽  
Ngok Do Minh ◽  
Mikhail I. Bazanov
Keyword(s):  
Cyclic Voltammetry ◽  
Comparative Study ◽  
Molecular Oxygen ◽  
Alkaline Solution ◽  
Electrochemical Behavior ◽  
Electrocatalytic Activity ◽  
Electrochemical Behaviour ◽  
Redox Potentials ◽  
Aqueous Alkaline Solution ◽  
The Comparative Study

The comparative study of electrochemical behaviour of 5-(pyrid-3-yl)-10,15,20-tri-phenylporphyrin (H2(3-Py)triPhP) and its Co-, (Py)Co-complexes was carried out by the method of cyclic voltammetry in an aqueous alkaline solution. The influence of the nature of the functional substituents and the metal, as well as additional extraligand on the character of cyclic I,E- curves, values of the redox potentials and the electrocatalytic activity of the compounds in the reaction of ionization of molecular oxygen was established.

Electroréduction de dérivés dinitrés aromatiques. V. influences du matériau d'électrode et de systèmes rédox sur les réductions du 4,4′-dinitrodibenzyle et de l'acide 4,4′-dinitrostilbène-2,2′-disulfonique

1996 ◽  
Vol 74 (7) ◽  
pp. 1409-1417 ◽  
Author(s):  
Anne-Marie Martre ◽  
Guy Mousset ◽  
Veronica Cosoveanu ◽  
Virginia Danciu
Keyword(s):  
Electrochemical Behavior ◽  
Chemical Reduction ◽  
Redox Couple ◽  
The Other ◽  
Disulfonic Acid ◽  
Reaction Products ◽  
Redox Systems ◽  
Experimental Conditions ◽  
Redox Couples ◽  
The One

This work concerns the electrochemical and chemical reductions of 4,4′-dinitrodibenzyl and 4,4′-dinitrostilbene 2,2′-disulfonic acid under various experimental conditions. On the one hand, the electrochemical reduction is realized on Sn, monel, and Hg electrodes with or without the presence of a redox couple, and on the other hand, the chemical reduction is performed by mean of an electrochemically generated reducing agent (Sn0). According to the type of redox couple used (Ti3+/Ti4+ or sn0/sn2+), important changes in the nature and the ratio of reaction products are observed. The best conditions for obtaining di- or monoamines are defined, they correspond to 90% yield for the diamines, 70% and 50%, respectively, for 4-amino-4′-nitrodibenzyl and for 4-amino-4′-nitrostilbene-2,2′-disulfonic acid. The electrochemical behavior of the dinitro derivatives and of TiOSO4, TiCl4, and SnCl2, used as precursors of the redox couples is studied under conditions of macroscale electrolyses (5 N H2SO4–EtOH 50/50, 2.5 N H2SO4, and 10% HCl). Key words: 4,4′-dinitrodibenzyl, 4,4′-dinitrostilbene 2,2′-disulfonic acid, electrochemistry, reduction, Ti3+/Ti4+ and Sn0/Sn2+ redox systems.

Effect of Reducing Agent on the Dispersion of Pt Nanoparticles on Electrospun Nb0.1Ti0.9O2 Nanofibers

2013 ◽  
Vol 1542 ◽  
Author(s):  
Esmaeil Navaei Alvar ◽  
Biao Zhou ◽  
S. Holger Eichhorn
Keyword(s):  
Electron Microscopy ◽  
Ethylene Glycol ◽  
Surface Area ◽  
Sodium Borohydride ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Surfactant Solution ◽  
Pem Fuel Cells ◽  
Active Surface Area ◽  
X Ray

ABSTRACTDegradation of the catalyst and catalyst support is an essential limitation of polymer electrolyte membrane (PEM) fuel cells containing commercial platinum on carbon catalysts. Catalysts based on platinum nanoparticles coated onto nanostructured TiO2 materials are presently investigated as a more stable and equally cost effective alternative. Reported here is the synthesis of two different Pt/Nb0.1Ti0.9O2 catalysts that were prepared by chemical reduction of H2PtCl6 with either sodium borohydride in ethanolic surfactant solution or ethylene glycol. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy confirmed the deposition of Pt nanoparticles on the surface of the nanofibers and revealed average sizes of 5.4 nm and 7.6 nm for reduction with ethylene glycol and sodium borohydride, respectively. The formation of smaller sized Pt nanoparticles in ethylene glycol is reasoned with the passivation of the nanoparticle surface by glycolic anions. Cyclic voltammetry measurements confirmed a higher electrochemical specific surface area (ESCA) of about 5.45 m2/gPt for the catalyst with smaller nanoparticles while the other catalyst reached only 4.96m2/gPt. Both catalysts retain about 60% of their electrochemically active surface area after 1000 voltammetric cycles in the range of 0.03 to 1.4 V vs. RHE. This relatively high value of activity retention is explained with a strong interaction between Pt nanoparticles and Nb0.1Ti0.9O2 support.

Three-Dimensional Reconstruction of Two Forms of the Chaperonin GRO EL

1990 ◽  
Vol 48 (1) ◽  
pp. 258-259
Author(s):  
J.L. Carrascosa ◽  
G. Abella ◽  
S. Marco ◽  
M. Muyal ◽  
J.M. Carazo
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Series Method ◽  
Three Dimensional Reconstruction ◽  
Structural Components ◽  
E Coli ◽  
Dimensional Reconstruction ◽  
Morphogenetic Factors ◽  
Tilt Series

Chaperonins are a class of proteins characterized by their role as morphogenetic factors. They trantsiently interact with the structural components of certain biological aggregates (viruses, enzymes etc), promoting their correct folding, assembly and, eventually transport. The groEL factor from E. coli is a conspicuous member of the chaperonins, as it promotes the assembly and morphogenesis of bacterial oligomers and/viral structures.We have studied groEL-like factors from two different bacteria:E. coli and B.subtilis. These factors share common morphological features , showing two different views: one is 6-fold, while the other shows 7 morphological units. There is also a correlation between the presence of a dominant 6-fold view and the fact of both bacteria been grown at low temperature (32°C), while the 7-fold is the main view at higher temperatures (42°C). As the two-dimensional projections of groEL were difficult to interprete, we studied their three-dimensional reconstruction by the random conical tilt series method from negatively stained particles.

Comparative Study of Proactivators of the Fibrinolysin System in Three Mammalian Species

1969 ◽  
Vol 21 (03) ◽  
pp. 594-603 ◽  
Author(s):  
Y Takada ◽  
A Takada ◽  
J. L Ambrus
Keyword(s):  
Guinea Pig ◽  
Comparative Study ◽  
Human Plasma ◽  
Mammalian Species ◽  
Gel Filtration ◽  
Plasminogen Activators ◽  
The Other ◽  
Rabbit Plasma ◽  
Plate Test ◽  
Fibrin Plate

SummarySephadex gel filtration of human plasma gave results suggesting the presence of two proactivators of plasminogen, termed proactivators A and B.Activity resembling that of proactivator A was found in rabbit plasma, but not in guinea pig plasma.Plasminogen activators produced by the interaction of proactivator A of human plasma with streptokinase had no caseinolytic or TAMe esterolytic effect.Proactivator A can be separated in a form apparently free from plasminogen, as shown by the heated fibrin plate test and by immunological analysis. On the other hand, proactivator B concentrates prepared so far are contamined with plasminogen.Human proactivators appear to be far more susceptible to streptokinase than are rabbit proactivators.Inhibitors of the fibrinolysin system were observed in the plasmas of all 3 species. These inhibitors are not present in the euglobulin fraction of plasma. Sephadex fractionation of euglobulin fractions results in proactivator preparations that do not contain inhibitors.

Empire Loyalism and Nationalism in Ukraine and Ireland

2020 ◽  
Vol 53 (3) ◽  
pp. 88-106
Author(s):  
Taras Kuzio
Keyword(s):  
Soviet Union ◽  
Northern Ireland ◽  
Comparative Study ◽  
The Other ◽  
History And Memory ◽  
Memory Politics ◽  
Irish History ◽  
British Rule ◽  
Five Factors ◽  
Post Colonialism

This is the first comparative article to investigate commonalities in Ukrainian and Irish history, identity, and politics. The article analyzes the broader Ukrainian and Irish experience with Russia/Soviet Union in the first and Britain in the second instance, as well as the regional similarities in conflicts in the Donbas region of Eastern Ukraine and the six of the nine counties of Ulster that are Northern Ireland. The similarity in the Ukrainian and Irish experiences of treatment under Russian/Soviet and British rule is starker when we take into account the large differences in the sizes of their territories, populations, and economies. The five factors that are used for this comparative study include post-colonialism and the “Other,” religion, history and memory politics, language and identities, and attitudes toward Europe.

Disinfection of Fruits with Activated Water

2019 ◽  
Vol 10 ◽  
pp. 1864-1872
Author(s):  
Prof. Teodora P. Popova
Keyword(s):  
Antimicrobial Activity ◽  
Aqueous Solutions ◽  
Antimicrobial Properties ◽  
The Other ◽  
Gram Negative Bacteria ◽  
High Antimicrobial Activity ◽  
Gram Negative ◽  
E Coli ◽  
Number Of Microorganisms ◽  
Lower Effect

The effect of ionized aqueous solutions (anolytes and catholyte) in the processing of fruits (cherries, morellos, and strawberries) for decontamination has been tested. Freshly prepared analytes and catholyte without the addition of salts were used, as well as stored for 7 months anolytes, prepared with 0.5% NaCl and a combination of 0.5% NaCl and 0.5% Na2CO3. The anolyte prepared with a combination of 0.5% NaCl and 0.5% Na2CO3, as well as the anolyte obtained with 0.5% NaCl, exhibit high antimicrobial activity against the surface microflora of strawberries, cherries, and sour cherries. They inactivate E. coli for 15 minutes. The other species of the fam. Enterobacteriaceae were also affected to the maximum extent, as is the total number of microorganisms, especially in cherries and sour cherries. Even stored for 7 months, they largely retain their antimicrobial properties. Anolyte and catholyte, obtained without the addition of salts, showed a lower effect on the total number of microorganisms, but had a significant effect on Gram-negative bacteria, and especially with regard to the sanitary indicative E. coli.

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