scholarly journals Ion–Ion Repulsions and Charge-Shielding Effects Dominate the Permeation Mechanism through the OmpF Porin Channel

2018 ◽  
Vol 123 (1) ◽  
pp. 86-94 ◽  
Author(s):  
Juan Carlos Ahumada ◽  
Carlos Alemán ◽  
Jorge Soto-Delgado ◽  
Juan Torras
Keyword(s):  
Ompf Porin ◽  
Shielding Effects

Mutations that alter the pore function of the ompF porin of Escherichia coli K12

1988 ◽  
Vol 203 (4) ◽  
pp. 961-970 ◽  
Author(s):  
S.A. Benson ◽  
J.L.L. Occi ◽  
B.A. Sampson
Keyword(s):  
Escherichia Coli ◽  
Ompf Porin ◽  
Escherichia Coli K12

scholarly journals Discrimination of ablation, shielding, and interface layer effects on the steady-state formation of persistent bubbles under liquid flow conditions during laser synthesis of colloids

2021 ◽  
Author(s):  
Mark-Robert Kalus ◽  
Riskyanti Lanyumba ◽  
Stephan Barcikowski ◽  
Bilal Gökce
Keyword(s):  
Steady State ◽  
Laser Ablation ◽  
Liquid Flow ◽  
Production Efficiency ◽  
Synthesis Method ◽  
Target Surface ◽  
Interface Layer ◽  
Nanosecond Laser ◽  
Viscous Liquids ◽  
Shielding Effects

AbstractOver the past decade, laser ablation in liquids (LAL) was established as an innovative nanoparticle synthesis method obeying the principles of green chemistry. While one of the main advantages of this method is the absence of stabilizers leading to nanoparticles with “clean” ligand-free surfaces, its main disadvantage is the comparably low nanoparticle production efficiency dampening the sustainability of the method and preventing the use of laser-synthesized nanoparticles in applications that require high amounts of material. In this study, the effects of productivity-dampening entities that become particularly relevant for LAL with high repetition rate lasers, i.e., persistent bubbles or colloidal nanoparticles (NPs), on the synthesis of colloidal gold nanoparticles in different solvents are studied. Especially under batch ablation conditions in highly viscous liquids with prolonged ablation times both shielding entities are closely interconnected and need to be disentangled. By performing liquid flow-assisted nanosecond laser ablation of gold in liquids with different viscosity and nanoparticle or bubble diffusivity, it is shown that a steady-state is reached after a few seconds with fixed individual contributions of bubble- and colloid-induced shielding effects. By analyzing dimensionless numbers (i.e., Axial Peclet, Reynolds, and Schmidt) it is demonstrated how these shielding effects strongly depend on the liquid’s transport properties and the flow-induced formation of an interface layer along the target surface. In highly viscous liquids, the transport of NPs and persistent bubbles within this interface layer is strongly diffusion-controlled. This diffusion-limitation not only affects the agglomeration of the NPs but also leads to high local densities of NPs and bubbles near the target surface, shielding up to 80% of the laser power. Hence, the ablation rate does not only depend on the total amount of shielding matter in the flow channel, but also on the location of the persistent bubbles and NPs. By comparing LAL in different liquids, it is demonstrated that 30 times more gas is produced per ablated amount of substance in acetone and ethylene glycol compared to ablation in water. This finding confirms that chemical effects contribute to the liquid’s decomposition and the ablation yield as well. Furthermore, it is shown that the highest ablation efficiencies and monodisperse qualities are achieved in liquids with the lowest viscosities and gas formation rates at the highest volumetric flow rates.

Shielding effects and hypoxia in photodynamic therapy

1994 ◽  
Vol 23 (6) ◽  
pp. 406-408 ◽  
Author(s):  
M. Herzog ◽  
J. Moser ◽  
B. Wagner ◽  
J. Broecker
Keyword(s):  
Photodynamic Therapy ◽  
Shielding Effects

scholarly journals Parameter Modeling Analysis and Experimental Verification on Magnetic Shielding Cylinder of All-Optical Atomic Spin Magnetometer

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Hong Zhang ◽  
Sheng Zou ◽  
Xi-Yuan Chen ◽  
Wei Quan
Keyword(s):  
Magnetic Measurement ◽  
Magnetic Shielding ◽  
Key Factors ◽  
Actual Measurement ◽  
Atomic Spin ◽  
Modeling Analysis ◽  
Measurement Results ◽  
All Optical ◽  
Ultrahigh Sensitivity ◽  
Shielding Effects

The ultrahigh sensitivity atomic spin magnetometer as the magnetic measurement sensor has received much concern. The performance of the magnetic shielding cylinder is one of the key factors constraining the atomic spin magnetometer’s sensitivity. In order to effectively improve the performances of the magnetic shielding, the parameter optimization models of the magnetic shielding cylinder were established in this paper. Under the condition of changing only one parameter while the others keeping constant, the effects of various parameters influencing the axial shielding coefficient were comprehensively analyzed, and the results showed that the smaller the innermost length, the innermost radius, and the radial spacing were, and the greater the axial spacing was, the better the shielding performance could be obtained. According to these results and the actual needs, the magnetic shielding cylinder was optimally designed, and then the shielding effects were simulated via the software Ansoft. The simulation results showed that the optimized magnetic shielding cylinder had the advantages of small size, high shielding performance, and lager uniformity than that of the nonoptimized one. The actual measurement results showed that the residual magnetism in the optimized magnetic shielding cylinder was below 0.1 nT, which was 2~4 times lower than the nonoptimized one.

Magnetic Shielding Effects in Compounds of Vanadium

1952 ◽  
Vol 87 (3) ◽  
pp. 541-542 ◽  
Author(s):  
H. E. Walchli ◽  
H. W. Morgan
Keyword(s):  
Magnetic Shielding ◽  
Shielding Effects

Journey of Poly-Nucleotides through OmpF Porin

2015 ◽  
Vol 119 (20) ◽  
pp. 6113-6128
Author(s):  
Hamid Hadi-Alijanvand ◽  
Maryam Rouhani
Keyword(s):  
Ompf Porin

Dynamic shielding effects in partially ionized gases

1972 ◽  
Vol 7 (2) ◽  
pp. 285-292 ◽  
Author(s):  
Hong-Sup Hahn ◽  
E. A. Mason ◽  
E. J. Miller ◽  
S. I. Sandler
Keyword(s):  
Charged Particle ◽  
Transport Properties ◽  
Particle Interactions ◽  
Partially Ionized ◽  
Predicted Values ◽  
Convergent Solution ◽  
Shielding Effects

The effects of dynamic shielding of charged-particle interactions on the predicted values of hte transport properties of partially ionized argon are considered. It is found that, at low degreesof ionization, dynamic shielding effects are of little importance, because charged-particle encounters are infrequent, so that the perturbed Lorentzian method may be used to obtain a rapidly convergent solution. At higher degrees of ionization, where the Chapman–Enskog solution converges rapidly, dynamic shielding effects can be taken into account using the expressions presented in the appendix to this paper. It is also found that the static shielding model, assuming complete shielding by electrons only, yields results that are quite close to those obtained when dynamic shielding is considered.

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