Improving the Stability of Organic Semiconductors: Distortion Energy versus Aromaticity in Substituted Bistetracene

2016 ◽  
Vol 28 (23) ◽  
pp. 8504-8512 ◽  
Author(s):  
Simil Thomas ◽  
Jack Ly ◽  
Lei Zhang ◽  
Alejandro L. Briseno ◽  
Jean-Luc Bredas
Keyword(s):  
Organic Semiconductors ◽  
Distortion Energy ◽  
The Stability

scholarly journals Investigation on the Quench Sensitivity of 7085 Aluminum Alloy with Different Contents of Main Alloying Elements

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 965
Author(s):  
Chengbo Li ◽  
Dongdong Chen
Keyword(s):  
Aluminum Alloy ◽  
Lattice Distortion ◽  
Supersaturated Solid Solution ◽  
Alloying Elements ◽  
Quench Sensitivity ◽  
Transmission Electron ◽  
Distortion Energy ◽  
Temperature Transformation ◽  
The Stability ◽  
Mgzn2 Phase

The quench sensitivity of 7085 aluminum alloy with different contents of the main alloying elements (Zn, Mg and Cu) was investigated using time-temperature-transformation (TTT) curves and end quenching experiments. Then, the quenching microstructure was analyzed using transmission electron microscopy. With increasing the contents of the main alloying elements, the transitions and nose temperatures of the TTT curves are obviously increased, while the incubation time of 0.5% η (MgZn2) phase precipitation content is decreased. In addition, as the contents of the main alloying elements decrease, the conductivity of the quenched samples is increased, but the hardness of the quenched samples is decreased. Moreover, the size and area fraction of the η phase are increased with increasing the contents of the main alloying elements. Based on the experimental results, the increase of Mg and Cu contents can decrease the stability of supersaturated solid solution and increase the lattice distortion energy, which can increase the quench sensitivity of 7085 aluminum alloy.

scholarly journals High-performance and stable photoelectrochemical water splitting cell with organic-photoactive-layer-based photoanode

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Je Min Yu ◽  
Jungho Lee ◽  
Yoon Seo Kim ◽  
Jaejung Song ◽  
Jiyeon Oh ◽  
...  
Keyword(s):  
Water Splitting ◽  
Organic Semiconductors ◽  
High Performance ◽  
Energy Levels ◽  
Photocurrent Density ◽  
Hydrogen Electrode ◽  
Photoactive Layer ◽  
Onset Potential ◽  
The Stability ◽  
Double Hydroxides

Abstract Considering their superior charge-transfer characteristics, easy tenability of energy levels, and low production cost, organic semiconductors are ideal for photoelectrochemical (PEC) hydrogen production. However, organic-semiconductor-based photoelectrodes have not been extensively explored for PEC water-splitting because of their low stability in water. Herein, we report high-performance and stable organic-semiconductors photoanodes consisting of p-type polymers and n-type non-fullerene materials, which is passivated using nickel foils, GaIn eutectic, and layered double hydroxides as model materials. We achieve a photocurrent density of 15.1 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) with an onset potential of 0.55 V vs. RHE and a record high half-cell solar-to-hydrogen conversion efficiency of 4.33% under AM 1.5 G solar simulated light. After conducting the stability test at 1.3 V vs. RHE for 10 h, 90% of the initial photocurrent density are retained, whereas the photoactive layer without passivation lost its activity within a few minutes.

On the energy instability of liquid crystals

1998 ◽  
Vol 9 (1) ◽  
pp. 23-36
Author(s):  
V. A. VLADIMIROV ◽  
K. I. ILIN
Keyword(s):  
Growth Rate ◽  
Initial Data ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Upper And Lower Bounds ◽  
Direct Lyapunov Method ◽  
Distortion Energy ◽  
The Stability ◽  
Energy Instability ◽  
General Equilibria

The direct Lyapunov method is used to investigate the stability of general equilibria of a nematic liquid crystal. First, we prove the converse Lagrange theorem stating that an equilibrium is unstable to small perturbations if the distortion energy has no minimum at this equilibrium (i.e. if the second variation of the distortion energy evaluated at the equilibrium is not positive definite). The proof is constructive rather than abstract: we explicitly construct a functional that grows exponentially with time by virtue of linearized equations of motion provided the condition of the theorem is satisfied. We obtain an explicit formula that gives the dependence of the perturbation growth rate upon the equilibrium considered and the initial data for the perturbation. Secondly, we obtain the upper and lower bounds for growing solutions of the linearized problem, and we identify the initial data corresponding to the most unstable mode (i.e. to the perturbation with maximal growth rate). All results are obtained in quite a general formulation: a nematic is inside a three-dimensional domain of an arbitrary shape and strong anchoring on the boundary is supposed; the standard equations of nematodynamics are employed as the governing equations.

Stable hybrid organic/inorganic photocathodes for hydrogen evolution with amorphous WO3 hole selective contacts

2017 ◽  
Vol 198 ◽  
pp. 433-448 ◽  
Author(s):  
Alessandro Mezzetti ◽  
Francesco Fumagalli ◽  
Antonio Alfano ◽  
Daniele Iadicicco ◽  
Maria Rosa Antognazza ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Low Cost ◽  
Water Environment ◽  
Selective Layer ◽  
Onset Potential ◽  
Inorganic Semiconductors ◽  
Photo Induced Electron Transfer ◽  
The Stability ◽  
Operational Activity ◽  
Stable Hybrid

Photoelectrochemical H2 production through hybrid organic/inorganic interfaces exploits the capability of polymeric absorbers to drive photo-induced electron transfer to an electrocatalyst in a water environment. Photoelectrode architectures based on solution-processed organic semiconductors are now emerging as low-cost alternatives to crystalline inorganic semiconductors based on Si, oxides and III–V alloys. In this work, we demonstrate that the stability of a hybrid organic/inorganic photocathode, employing a P3HT:PCBM blend as photoactive material, can be considerably improved by introducing an electrochemically stable WO3 hole selective layer, paired with a TiO2 electron selective layer. This hybrid photoelectrode exhibits a photocurrent of 2.48 mA cm−2 at 0 VRHE, +0.56 VRHE onset potential and a state-of the art operational activity of more than 10 hours. This work gives the perspective that photoelectrodes based on organic semiconductors, coupled with proper inorganic selective contacts, represent a sound new option for the efficient and durable photoelectrochemical conversion of solar energy into fuels.

scholarly journals Tailored polymeric, photovoltaic, and near-infrared-responsive neuroprosthesis

2020 ◽  
Author(s):  
Marta Jole Ildelfonsa Airaghi Leccardi ◽  
Naïg Aurelia Ludmilla Chenais ◽  
Laura Ferlauto ◽  
Maciej Kawecki ◽  
Elodie Geneviève Zollinger ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Organic Semiconductors ◽  
Near Infrared ◽  
Organic Materials ◽  
Visible Spectrum ◽  
Building Blocks ◽  
Aqueous Environment ◽  
Retinal Stimulation ◽  
Neuronal Stimulation ◽  
The Stability

AbstractOrganic materials, such as conjugated polymers, are attractive building blocks for bioelectronic interfaces. In particular, organic semiconductors showed excellent performances in light-mediated excitation and silencing of neuronal cells and tissues. However, the main challenges of these organic photovoltaic interfaces compared to inorganic prostheses are the limited stability of conjugated polymers in the aqueous environment and the exploitation of materials only responsive in the visible spectrum. In this report, we show a new photovoltaic organic interface tailored for neuronal stimulation in the near-infrared spectrum. Also, we adjusted the organic materials by chemical modification in order to improve the stability in aqueous environment and to modulate the photoelectrical stimulation efficiency. As proof of principle, we tested this interface for retinal stimulation. Our results provide an efficient, reliable, and stable implant applicable for neural stimulation.

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

Symmetric Multistep Methods Revisited: II. Numerical Experiments

1999 ◽  
Vol 173 ◽  
pp. 309-314 ◽  
Author(s):  
T. Fukushima
Keyword(s):  
Multistep Methods ◽  
Computational Time ◽  
Integration Time ◽  
Implicit Methods ◽  
Symmetric Methods ◽  
Celestial Bodies ◽  
The Stability ◽  
Predictor Corrector ◽  
Symmetric Multistep Methods ◽  
Integration Errors

AbstractBy using the stability condition and general formulas developed by Fukushima (1998 = Paper I) we discovered that, just as in the case of the explicit symmetric multistep methods (Quinlan and Tremaine, 1990), when integrating orbital motions of celestial bodies, the implicit symmetric multistep methods used in the predictor-corrector manner lead to integration errors in position which grow linearly with the integration time if the stepsizes adopted are sufficiently small and if the number of corrections is sufficiently large, say two or three. We confirmed also that the symmetric methods (explicit or implicit) would produce the stepsize-dependent instabilities/resonances, which was discovered by A. Toomre in 1991 and confirmed by G.D. Quinlan for some high order explicit methods. Although the implicit methods require twice or more computational time for the same stepsize than the explicit symmetric ones do, they seem to be preferable since they reduce these undesirable features significantly.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

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