scholarly journals Influence of electric fields and pH on biofilm structure as related to the bioelectric effect.

1997 ◽  
Vol 41 (9) ◽  
pp. 1876-1879 ◽  
Author(s):  
P Stoodley ◽  
D deBeer ◽  
H M Lappin-Scott
Keyword(s):  
Electric Fields ◽  
Electrostatic Interactions ◽  
Flow Cell ◽  
Mixed Species ◽  
Bioelectric Effect ◽  
Carboxylate Groups ◽  
Acidic Conditions ◽  
The Wire ◽  
Biofilm Structure ◽  
Increased Susceptibility

Mixed species biofilms of Klebsiella pneumoniae, Pseudomonas fluorescens, and Pseudomonas aeruginosa were grown in a flow cell fitted with two platinum wire electrodes. The biofilm growing on the wires reached a thickness of approximately 50 microm after 3 days. When a voltage was applied with oscillating polarity, the biofilm attached to the wire expanded and contracted. The biofilm expanded by approximately 4% when the wire was cathodic but was reduced to 74% of the original thickness when the wire was anodic. The phenomenon was reproduced by alternately flushing the flow cell with media adjusted to pH 3 and pH 10 with no electric current. At pH 10 the biofilm was unaltered, but it became compacted to 69% of the original thickness at pH 3. We explained these phenomena in terms of the molecular interactions between charged acidic groups in the biofilm slime and the bacterial cell walls. Contraction of the biofilm under acidic conditions may be caused by (i) the elimination of electrostatic repulsion from neutralization of negatively charged carboxylate groups through protonation and (ii) subsequent hydrogen bonding between the carboxylic acids and oxygen atoms in the sugars. Electrostatic interactions between negatively charged groups in the biofilm and the charged wire may also be expected to cause biofilm expansion when the wire was cathodic and contraction when the wire was anodic. The consequences of the explanation of the increased susceptibility of biofilm cells to antibiotics in an electric field, the "bioelectric effect," are discussed.

scholarly journals Separation of water–ethanol solutions with carbon nanotubes and electric fields

2016 ◽  
Vol 18 (48) ◽  
pp. 33310-33319 ◽  
Author(s):  
Winarto Winarto ◽  
Daisuke Takaiwa ◽  
Eiji Yamamoto ◽  
Kenji Yasuoka
Keyword(s):  
Carbon Nanotubes ◽  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interactions ◽  
Water Molecules ◽  
Ordered Structure

Under an electric field, water prefers to fill CNTs over ethanol, and electrostatic interactions within the ordered structure of the water molecules determine the separation effects.

Heat Transfer in Wire Bonding Process

1994 ◽  
Vol 116 (1) ◽  
pp. 44-48 ◽  
Author(s):  
M. A. Jog ◽  
I. M. Cohen ◽  
P. S. Ayyaswamy
Keyword(s):  
Electric Fields ◽  
Potential Temperature ◽  
Wire Bonding ◽  
Bonding Process ◽  
Heat Fluxes ◽  
Main Body ◽  
Discharge Parameters ◽  
Current Densities ◽  
The Wire ◽  
Microelectronic Manufacturing

We have analyzed an electric discharge between wire and planar electrodes with wire diameter and current densities that are typically used in upscaled experimental simulations of the wire bonding process employed in microelectronic manufacturing. A set of continuum conservation equations has been solved to obtain the variation of electric potential, temperature distributions, and the electrode heat fluxes. Results indicate that the main body of the discharge is quasineutral bounded by space charge sheaths at both electrodes. Strong electric fields are concentrated in the electrode sheaths. The heat flux to the wire is sharply peaked near the wire tip but on the plane it decays slowly away from the discharge axis. The model studied here may be used to establish optimum discharge parameters for wire bonding.

Sensitivity to change in electrical environment: a new bioelectric effect

1980 ◽  
Vol 239 (5) ◽  
pp. R424-R427 ◽  
Author(s):  
A. A. Marino ◽  
J. M. Cullen ◽  
M. Reichmanis ◽  
R. O. Becker ◽  
F. X. Hart
Keyword(s):  
Electric Field ◽  
Blood Cell ◽  
Electric Fields ◽  
Red Blood Cell ◽  
Low Frequency ◽  
Sensitivity To Change ◽  
Bioelectric Effect ◽  
Cell Concentrations ◽  
Inappropriate Choice

The action of a 60-Hz, 5 kV/m electric field on erythrocyte parameters in mice was determined. No effects attributable to the magnitude of the field were found, but a transition either from or to an environment containing the field caused decreased red blood cell concentrations and decreased hematocrits. The failure of others to observe effects on erythrocyte parameters following exposure to low-frequency electric fields may have been due to an inappropriate choice of duration of exposure.

scholarly journals Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4203 ◽  
Author(s):  
Louise Delahaye ◽  
John Thomas Hobson ◽  
Matthew Peter Rando ◽  
Brenna Sweeney ◽  
Avery Bernard Brown ◽  
...  
Keyword(s):  
Sorption Capacity ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Design ◽  
Alkali Treatment ◽  
Functional Theory ◽  
Computational Evaluation ◽  
Carboxylate Groups ◽  
Exchange Resins ◽  
Carbonate Salts

A model hydrochar was synthesized from glucose at 180 °C and its Cu(II) sorption capacity was studied experimentally and computationally as an example of molecular-level adsorbent design. The sorption capacity of the glucose hydrochar was less than detection limits (3 mg g−1) and increased significantly with simple alkali treatments with hydroxide and carbonate salts of K and Na. Sorption capacity depended on the salt used for alkali treatment, with hydroxides leading to greater improvement than carbonates and K+ more than Na+. Subsequent zeta potential and infrared spectroscopy analysis implicated the importance of electrostatic interactions in Cu(II) sorption to the hydrochar surface. Computational modeling using Density Functional Theory (DFT) rationalized the binding as electrostatic interactions with carboxylate groups; similarly, DFT calculations were consistent with the finding that K+ was more effective than Na+ at activating the hydrochar. Based on this finding, custom-synthesized hydrochars were synthesized from glucose-acrylic acid and glucose-vinyl sulfonic acid precursors, with subsequent improvements in Cu(II) adsorption capacity. The performance of these hydrochars was compared with ion exchange resins, with the finding that Cu(II)-binding site stoichiometry is superior in the hydrochars compared with the resins, offering potential for future improvements in hydrochar design.

scholarly journals Tobacco mosiac virus particle structure and the initiation of disassembly

1999 ◽  
Vol 354 (1383) ◽  
pp. 551-557 ◽  
Author(s):  
Gerald Stubbs
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Electrostatic Interactions ◽  
Site Directed Mutagenesis ◽  
Protein Subunit ◽  
Particle Structure ◽  
Defensive Responses ◽  
Carboxylate Groups ◽  
Viral Coat ◽  
Fibre Diffraction

The structure of an intact tobacco mosaic virus (TMV) particle was determined at 2.9 Å resolution using fibre diffraction methods. All residues of the coat protein and the three nucleotides of RNA that are bound to each protein subunit were visible in the electron density map. Examination of the structures of TMV, cucumber green mottle mosaic virus and ribgrass mosaic virus, and site–directed mutagenesis experiments in which carboxylate groups were changed to the corresponding amides, showed that initial stages of disassembly are driven by complex electrostatic interactions involving at least seven carboxylate side–chains and a phosphate group. The locations of these interactions can drift during evolution, allowing the viruses to evade plant defensive responses that depend on recognition of the viral coat protein surface.

scholarly journals A Preorganized Electric Field Leads to Minimal Geometrical Reorientation in the Catalytic Reaction of Ketosteroid Isomerase

2020 ◽  
Author(s):  
Yufan Wu ◽  
Stephen Fried ◽  
Steven Boxer
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Ground State ◽  
Active Site ◽  
Electrostatic Interactions ◽  
Stark Effect ◽  
Structural Changes ◽  
Enzymatic Catalysis ◽  
Ketosteroid Isomerase ◽  
Computational Enzyme Design

<div><p>Electrostatic interactions play a pivotal role in enzymatic catalysis and are increasingly modeled explicitly in computational enzyme design; nevertheless, they are challenging to measure experimentally. Using vibrational Stark effect (VSE) spectroscopy, we have measured electric fields inside the active site of the enzyme ketosteroid isomerase (KSI). These studies have shown that these fields can be unusually large, but it has been unclear to what extent they specifically stabilize the transition state (TS) relative to a ground state (GS). In the following, we use crystallography and computational modeling to show that KSI’s intrinsic electric field is nearly perfectly oriented to stabilize the geometry of its reaction’s TS. Moreover, we find that this electric field adjusts the orientation of its substrate in the ground state so that the substrate needs to only undergo minimal structural changes upon activation to its TS. This work provides evidence that the active site electric field in KSI is preorganized to facilitate catalysis and provides a template for how electrostatic preorganization can be measured in enzymatic systems. <br></p></div>

Dyeing of Silk with Natural Plant Extract from Rhizoma picrorhizae

2012 ◽  
Vol 441 ◽  
pp. 155-159
Author(s):  
Sha Sha Sun ◽  
Jie Jie Wang ◽  
Ren Cheng Tang
Keyword(s):  
Ultraviolet Light ◽  
Plant Extract ◽  
Electrostatic Interactions ◽  
Chemical Nature ◽  
Natural Dye ◽  
Silk Fabric ◽  
Natural Plant ◽  
Acidic Conditions ◽  
Silk Dyeing ◽  
Dyed Fabric

A new concept that uses natural plant extract from Rhizoma Picrorhizae (RP) as a natural dye in silk dyeing was proposed. The RP extract can be adsorbed by silk to provide yellow to brown color, depending on the RP concentration. The stabilities of RP solution against pH, heat, and ultraviolet light were investigated. Factors such as pH, temperature, dyeing time, RP concentration were studied in order to understand the dyeing properties of RP extract for silk fabric. After dyeing, some of the samples are mordanted with different mordants. It was founded that RP extract was stable at acidic conditions and stable to heat and ultraviolet light, and the interactions between silk and RP extract molecules were non-electrostatic interactions; and that RP extract showed good building-up properties on silk. Furthermore, the colors of the dyed fabric mordanted with different mordants as well as their depth were greatly dependent on the chemical nature of mordants. In conclusion, RP was a potential natural dye which can be applied to silk dyeing.

In situ monitoring of the biofilm formation of Pseudomonas putida on hematite using flow-cell ATR-FTIR spectroscopy to investigate the formation of inner-sphere bonds between the bacteria and the mineral

2008 ◽  
Vol 72 (1) ◽  
pp. 101-106 ◽  
Author(s):  
J. J. Ojeda ◽  
M. E. Romero-Gonzalez ◽  
H. M. Pouran ◽  
S. A. Banwart
Keyword(s):  
Pseudomonas Putida ◽  
Real Time ◽  
Chemical Interaction ◽  
Initial Step ◽  
Flow Cell ◽  
In Situ Monitoring ◽  
Mineral Surfaces ◽  
Germanium Crystal ◽  
Carboxylate Groups

AbstractIn situ flow-cell ATR-FTIR using a hematite-coated germanium crystal was used to investigate the chemical interactions between Pseudomonas putida and hematite in real time, when compared with cells not attached to the mineral surface. ATR-FTIR spectra of bacteria growing on hematite showed a shift in the carboxylate signal when compared to the samples obtained from free cells, indicating a chemical interaction between the carboxylate groups and the Fe metal ions of the hematite surface. Small differences in the polysaccharide and phosphoryl regions of the IR spectra of bacteria attached to hematite were also observed. This work shows how the use of in-situ flow-cell experiments with a mineral-coated germanium crystal allows a better description of the bacterial interactions with minerals in real time, as an initial step to understand the fundamental mechanisms involved in the relationship between bacteria and mineral surfaces.

scholarly journals Effects of Pulsed Electric Fields on Yeast with Prions and the Structure of Amyloid Fibrils

2021 ◽  
Vol 11 (6) ◽  
pp. 2684
Author(s):  
Justina Jurgelevičiūtė ◽  
Nedas Bičkovas ◽  
Andrius Sakalauskas ◽  
Vitalij Novickij ◽  
Vytautas Smirnovas ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interactions ◽  
Amyloid Fibrils ◽  
Translation Termination ◽  
Yeast Prions ◽  
Amyloid Aggregates ◽  
Perfect Model ◽  
Noncovalent Bonds ◽  
The Brain

Prions are misfolded, self-replicating, and transmissible proteins capable of causing different conditions that affect the brain and nervous system in humans and animals. Yeasts are the perfect model to study prion formation, dissemination, and the structure of protein aggregates. Yeast prions are related to stress resistance, cell fitness, and viability. Applying a pulsed electric field (PEF) as a factor capable of disintegrating the amyloid aggregates arises from the fact that the amyloid aggregates form via noncovalent bonds and stabilize via electrostatic interactions. In this research, we applied 2–26 kV/cm PEF delivered in sequences of 5 pulses of 1 ms duration to the Saccharomyces cerevisiae cell without prions and containing strong and weak variants of the [PSI+] prion (prion form of Sup35 translation termination factor). We determined that prions significantly increase cell survivability and resistance to PEF treatment. The application of PEF to the purified Sup35NM fibrils showed that the electric field causes significant reductions in the length of fibrils and the full disintegration of fibrils to Sup35 oligomers can be achieved in higher fields.

scholarly journals Study of Nanofiber Formation by Injecting Polymeric Solutions Inside Intense Electric Fields Using Different Electrode Configurations

2010 ◽  
Vol 5 (2) ◽  
pp. 148-153
Author(s):  
R. Furlan ◽  
S. V. Arroyo ◽  
R. O. F. Torres ◽  
J. A. M. Rosado ◽  
A. N. R. Da Silva
Keyword(s):  
Electric Fields ◽  
Fiber Orientation ◽  
Electrostatic Interactions ◽  
Fiber Diameter ◽  
Electrospinning Process ◽  
Floating Potential ◽  
Polymer Injection ◽  
Polymer Flow ◽  
Polymeric Solutions ◽  
Diameter Reduction

Electrospinning has been considered a straightforward way of producing nanofibers. In this work we are analyzing non-conventional approaches of the electrospinning process to better understand and explore the effect of electrostatic interactions. The processes we are investigating include the insertion of polymer inside the electric field keeping the capillary for polymer injection at a floating potential. Also, we are investigating different electrode configurations including: same as electrospinning (with and without polarization of the capillary for polymer injection), parallel macro electrodes and, microelectrodes (with tip to tip alignment). Image analysis reveals the occurrence of instabilities/oscillations of the polymer flow (caused by redistribution of charges). Improvement of polymer flow directionality and fiber diameter reduction are observed in comparison with conventional electrospinning. Fiber orientation can be obtained using parallel macro electrodes and micro electrodes.

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