scholarly journals Electrochemical triggering of lipid bilayer lift-off oscillation at the electrode interface

2019 ◽  
Vol 16 (150) ◽  
pp. 20180626 ◽  
Author(s):  
Nikolay V. Ryzhkov ◽  
Natalya A. Mamchik ◽  
Ekaterina V. Skorb
Keyword(s):  
Lipid Bilayer ◽  
Gold Electrode ◽  
Electrochemical Impedance ◽  
Solid Support ◽  
Polymer Support ◽  
Layer By Layer ◽  
Free Standing ◽  
Electrochemical Approach ◽  
Lift Off

In situ studies of transmembrane channels often require a model bioinspired artificial lipid bilayer (LB) decoupled from its underlaying support. Obtaining free-standing lipid membranes is still a challenge. In this study, we suggest an electrochemical approach for LB separation from its solid support via hydroquinone oxidation. Layer-by-layer deposition of polyethylenimine (PEI) and polystyrene sulfonate (PSS) on the gold electrode was performed to obtain a polymeric nanocushion of [PEI/PSS] 3 /PEI. The LB was deposited on top of an underlaying polymer support from the dispersion of small unilamellar vesicles due to their electrostatic attraction to the polymer support. Since lipid zwitterions demonstrate pH-dependent charge shifting, the separation distance between the polyelectrolyte support and LB can be adjusted by changing the environmental pH, leading to lipid molecules recharge. The proton generation associated with hydroquinone oxidation was studied using scanning vibrating electrode and scanning ion-selective electrode techniques. Electrochemical impedance spectroscopy is suggested to be a powerful instrument for the in situ observation of processes associated with the LB–solid support interface. Electrochemical spectroscopy highlighted the reversible disappearance of the LB impact on impedance in acidic conditions set by dilute acid addition as well as by electrochemical proton release on the gold electrode due to hydroquinone oxidation.

Densification kinetics of glass films constrained on rigid substrates

1995 ◽  
Vol 10 (5) ◽  
pp. 1321-1326 ◽  
Author(s):  
Jaecheol Bang ◽  
Guo-Quan Lu
Keyword(s):  
Polyvinyl Butyral ◽  
Silica Content ◽  
Free Standing ◽  
Free Film ◽  
Lift Off ◽  
Free Films ◽  
Mylar Sheet ◽  
Blade Casting ◽  
Kinetics Of

The kinetics of constrained-film sintering were studied in a borosilicate glass (BSG) + silica system because of their applications in microelectronic packaging technologies. Samples with a silica content by 20% by volume were prepared from slurries of powder mixtures in a commercial polyvinyl butyral (PVB) binder solution. Constrained films about 0.2 mm thick were formed by doctor-blade casting the slurries on silicon wafers. Free-standing films about 0.6 mm thick were also produced by casting the slurries on a treated mylar sheet for easy lift-off. Sintering experiments were carried out in a hot stage at temperatures between 715 °C and 775 °C. Shrinkage profiles of the free and constrained (shrinkage in thickness only) films were determined in situ using a custom-designed optical system. The densification rates measured in the constrained films were slower than those in the free films. However, the substrate constraint had no effect on the activation energy of densification which was found equal to 385 ± 10 kJ/mol, the same for both free and constrained films. A relation between the constrained-film and free-film densification profiles was derived using the viscous analogy for the constitutive equations of a porous sintering body.

scholarly journals An Immunosensor for Pathogenic Staphylococcus aureus Based on Antibody Modified Aminophenyl-Au Electrode

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Amani Chrouda ◽  
Mohamed Braiek ◽  
Karima Bekir Rokbani ◽  
Amina Bakhrouf ◽  
Abderrazak Maaref ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Electron Transfer ◽  
Gold Electrode ◽  
High Selectivity ◽  
Electrochemical Impedance ◽  
Transfer Resistance ◽  
Acidic Aqueous Solution ◽  
Stepwise Assembly ◽  
Electron Transfer Resistance

The objective of this work is to elaborate an immunosensing system which will detect and quantify Staphylococcus aureus bacteria. A gold electrode was modified by electrografting of 4-nitrophenyl diazonium, in situ synthesized in acidic aqueous solution. The immunosensor was fabricated by immobilizing affinity-purified polyclonal anti S. aureus antibodies on the modified gold electrode. Cyclic voltammetry (CV) and Faradaic Electrochemical Impedance Spectroscopy (EIS) were employed to characterize the stepwise assembly of the immunosensor. The performance of the developed immunosensor was evaluated by monitoring the electron-transfer resistance detected using Faradaic EIS. The experimental results indicated a linear relationship between the relative variation of the electron transfer resistance and the logarithmic value of S. aureus concentration, with a slope of 0.40 ± 0.08 per decade of concentration. A low quantification limit of 10±2 CFU per ml and a linear range up to 107±2×106 CFU per mL were obtained. The developed immunosensors showed high selectivity to Escherichia coli and Staphylococcus saprophyticus.

scholarly journals Highly flexible and free-standing carbon nanotube/hollow carbon nanocage hybrid films for high-performance supercapacitors

RSC Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 6655-6661
Author(s):  
Qiang Qiang Shi ◽  
Hang Zhan ◽  
Yu Zhang ◽  
Jian Nong Wang
Keyword(s):  
Carbon Nanotube ◽  
High Performance ◽  
Hybrid Film ◽  
Electrolyte Transport ◽  
Layer By Layer ◽  
Hybrid Films ◽  
Free Standing ◽  
Carbon Nanocage ◽  
Hollow Carbon

A carbon nanotube-hollow carbon nanocage hybrid film is fabricated via a facile layer-by-layer strategy. The in situ addition of hollow carbon nanocages to the film is beneficial for preventing CNT stacking and thus promoting electrolyte transport.

scholarly journals Pressure induced structural phase crossover of a GaSe epilayer grown under screw dislocation driven mode and its phase recovery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nhu Quynh Diep ◽  
Ssu Kuan Wu ◽  
Cheng Wei Liu ◽  
Sa Hoang Huynh ◽  
Wu Ching Chou ◽  
...  
Keyword(s):  
Screw Dislocation ◽  
Lattice Structure ◽  
Structural Phase ◽  
Layer By Layer ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Out Of Plane ◽  
Layer Stacking ◽  
Diamond Anvil

AbstractHydrostatically pressurized studies using diamond anvil cells on the structural phase transition of the free-standing screw-dislocation-driven (SDD) GaSe thin film synthesized by molecular beam epitaxy have been demonstrated via in-situ angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy. The early pressure-driven hexagonal-to-rock salt transition at approximately ~ 20 GPa as well as the outstandingly structural-phase memory after depressurization in the SDD-GaSe film was recognized, attributed to the screw dislocation-assisted mechanism. Note that, the reversible pressure-induced structural transition was not evidenced from the GaSe bulk, which has a layer-by-layer stacking structure. In addition, a remarkable 1.7 times higher in bulk modulus of the SDD-GaSe film in comparison to bulk counterpart was observed, which was mainly contributed by its four times higher in the incompressibility along c-axis. This is well-correlated to the slower shifting slopes of out-of-plane phonon-vibration modes in the SDD-GaSe film, especially at low-pressure range (< 5 GPa). As a final point, we recommend that the intense density of screw dislocation cores in the SDD-GaSe lattice structure plays a crucial role in these novel phenomena.

Mineralization of Bone-Like Apatite in Chitosan Hydrogel

2010 ◽  
Vol 434-435 ◽  
pp. 605-608 ◽  
Author(s):  
Bao Qiang Li ◽  
Yan Ming Huang ◽  
Yong Liang Wang ◽  
Yu Zhou
Keyword(s):  
Negative Charge ◽  
Porous Wall ◽  
Layer By Layer ◽  
Amino Groups ◽  
Free Standing ◽  
Chitosan Hydrogel ◽  
Modification Process ◽  
Nucleation Sites ◽  
Short Period

Polymers with negative charge groups, such as carboxylic or phosphatic groups, were frequently used to induce or promote the apatite deposition. However, chitosan with potentially chelated calcium ions, were ignored. Inspired by layer by layer technology, chitosan hydrogel without any surface modification process was used as framework to mineralize bone-like apatite. XRD and IR results shown that in situ synthesis bone-like apatite, similar to apatite in rib of rabbit, was carbonate ions partially substituted apatite and preferred growth orientation in direction of their c-axis. Bone-like apatite with nano-flake shape with size of 1um fully covered chitosan in short period of time. In case of chelation effect of amino groups, chitosan hydrogel provided heterogeneous apatite nucleation sites, which supported by fact that bone-like apatite tended to deposit on porous wall of chitosan, rather than grow in form of free-standing.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

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