scholarly journals Electrochemical studies of grid and linear type M^2+ (M=Zn, Cd and Pb) complexes of a bis-(hydrazone) bearing two symmetric carboxylic groups

2018 ◽  
Vol 21 (1) ◽  
pp. 113
Author(s):  
Wilson Giraldo ◽  
Elkin Romero ◽  
Manuel Chaur
Keyword(s):  
Smart Materials ◽  
Spin Crossover ◽  
Electrochemical Studies ◽  
Redox Potentials ◽  
Linear Type ◽  
Wave Voltammetry ◽  
Carboxylic Groups ◽  
Different Temperatures ◽  
Linear Correlations ◽  
Transoid Conformation

Herein  we  present  the  preparation  of  a  bis-(hydrazone)  containing  a  pyridine-pyrimidine-pyridine framework. This compound can be visualized as a double arm system able of coordinating two metal ions in a terpyridine-like manner. By NMR (1D and 2D) it was determined a transoid conformation  and  an  E  configuration  around  the  two  imine  double  bonds.  Complexation  with M2+ (M = Zn, Cd, and Pb) ions resulted in grid and linear type structures which were studied by cyclic and squared wave voltammetry at different temperatures. No linear correlations of the redox potentials as a function of temperature were observed. The latter is likely due to rearrangements in the structure or to spin crossover events. The present results deserve further studies on the electronic properties of these types of compounds for the development of smart materials.

scholarly journals Substitution Effect on the Charge Transfer Processes in Organo-Imido Lindqvist-Polyoxomolybdate

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 44 ◽  
Author(s):  
Patricio Hermosilla-Ibáñez ◽  
Kerry Wrighton-Araneda ◽  
Walter Cañón-Mancisidor ◽  
Marlen Gutiérrez-Cutiño ◽  
Verónica Paredes-García ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Theoretical Study ◽  
Bathochromic Shift ◽  
Substitution Effect ◽  
Spectroscopic Properties ◽  
Electrochemical Studies ◽  
Redox Potentials ◽  
Metal Centre ◽  
Transfer Processes ◽  
Organic Fragment

Two new aromatic organo-imido polyoxometalates with an electron donor triazole group ([n-Bu4N]2[Mo6O18NC6H4N3C2H2]) (1) and a highly conjugated fluorene ([n-Bu4N]2[Mo6O18NC13H9]) (2) have been obtained. The electrochemical and spectroscopic properties of several organo-imido systems were studied. These properties were analysed by the theoretical study of the redox potentials and by means of the excitation analysis, in order to understand the effect on the substitution of the organo-imido fragment and the effect of the interaction to a metal centre. Our results show a bathochromic shift related to the charge transfer processes induced by the increase of the conjugated character of the organic fragment. The cathodic shift obtained from the electrochemical studies reflects that the electronic communication and conjugation between the organic and inorganic fragments is the main reason of this phenomenon.

scholarly journals Electrochemical behaviours of Eu(III)/E(II) and Ce(IV)/Ce(III) in H3PO4-H2O media : solvation and complexation reactions

2018 ◽  
Vol 149 ◽  
pp. 01092
Author(s):  
B. Belqat ◽  
S. Belcadi
Keyword(s):  
Rare Earth ◽  
Phosphoric Acid ◽  
Rare Earth Elements ◽  
Electrochemical Properties ◽  
Essential Elements ◽  
High Tech ◽  
Electrochemical Studies ◽  
Redox Potentials ◽  
Complexation Reactions ◽  
Phosphoric Acid Concentration

Many kinds of rare earth elements (REE) such as europium and cerium have been make them essential elements in many high-tech components. The electrochemical studies can be presented as an interesting indication for europium and cerium extraction from phosphoric solutions, including solvation and complexation reactions. The normal redox potentials of Eu3+/Eu2+ and Ce4+/Ce3+ systems have been determined in H3PO4-H2O media with various phosphoric acid concentration. The solvation of these elements in phosphoric media is characterized by their transfer activity coefficients "f" calculated from the corresponding normal redox potentials. The corresponding solvation increases with increasing the H3PO4 concentration. For each REE, the electrochemical properties depend on its number of charges and on its basic properties. Results suggest that solvation and complexation of REE phosphates are important in controlling REE concentration.

Thermo-Mechanical Behavior of Epoxy Shape Memory Polymer

2013 ◽  
Vol 721 ◽  
pp. 169-172 ◽  
Author(s):  
Yu Gu ◽  
Shao Xiong Li
Keyword(s):  
Mechanical Behavior ◽  
Shape Memory ◽  
Significant Influence ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Testing Temperature ◽  
Curing Agent ◽  
Different Temperatures ◽  
Viscoelastic Behaviors

The viscoelastic behaviors of shape memory polymers have a significant influence on the function realization of this kind of smart materials. In this study, stress-strain hysteresis under uniaxial tension of epoxy shape memory polymers with varied curing agent contents and types were tested at different temperatures. The effects of the testing temperature, curing-agent type and content on the viscoelastic behaviors of the materials were discussed.

Positronium Lifetimes and Gas Permeation in Aquivion® for Fuel Cells

2012 ◽  
Vol 733 ◽  
pp. 61-64 ◽  
Author(s):  
Hamdy F.M. Mohamed ◽  
Yoshinori Kobayashi ◽  
Seiichi Kuroda ◽  
Akihiro Ohira
Keyword(s):  
Fuel Cells ◽  
Relative Humidity ◽  
Free Volume ◽  
Room Temperature ◽  
Gas Permeability ◽  
Gas Permeation ◽  
Positronium Lifetime ◽  
Different Temperatures ◽  
Linear Correlations

Variations of ortho-positronium (o-Ps) lifetime and gas permeability of the Aquivion® E8705 membrane were studied as functions of temperature under vacuum and relative humidity at room temperature. When the temperature was varied between 0 and 100 °C in vacuum, the hole volume of Aquivion® E8705, deduced from the ortho-positronium lifetime, gradually increased. However, when the relative humidity was changed at room temperature, the hole volume was essentially unchanged. Good linear correlations between the logarithm of permeabilities of O2 and H2 and reciprocal hole volume at different temperatures indicates the importance role of free volume in gas permeation in dry Aquivion® E8705. However, for hydrated Aquivion® E8705 the permeability less depends on hole volume.

scholarly journals On the Spin-State Dependence of Redox Potentials of Spin Crossover Complexes

2020 ◽  
Vol 59 (24) ◽  
pp. 18402-18406
Author(s):  
Isabelle M. Dixon ◽  
Sylvain Rat ◽  
Alix Sournia-Saquet ◽  
Gábor Molnár ◽  
Lionel Salmon ◽  
...  
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
State Dependence ◽  
Redox Potentials ◽  
Spin Crossover Complexes

Smart Material Composites for Discrete Stiffness Materials

2018 ◽  
Author(s):  
Emily A. Allen ◽  
Lee D. Taylor ◽  
John P. Swensen
Keyword(s):  
Melting Point ◽  
Smart Materials ◽  
Biological Systems ◽  
Initial Step ◽  
Robotic Systems ◽  
Beam Structure ◽  
New Class ◽  
Different Temperatures ◽  
Materials Used ◽  
Local Stiffness

This paper presents an initial step towards a new class of soft robotics materials, where localized, geometric patterning of smart materials can exhibit discrete levels of stiffness through the combinations of smart materials used. This work is inspired by a variety of biological systems where actuation is accomplished by modulating the local stiffness in conjunction with muscle contractions. Whereas most biological systems use hydrostatic mechanisms to achieve stiffness variability, and many robotic systems have mimicked this mechanism, this work aims to use smart materials to achieve this stiffness variability. Here we present the compositing of the low melting point Field’s metal, shape memory alloy Nitinol, and a low melting point thermoplastic Polycaprolactone (PCL), composited in simple beam structure within silicone rubber. The comparison in bending stiffnesses at different temperatures, which reside between the activation temperatures of the composited smart materials demonstrates the ability to achieve discrete levels of stiffnesses within the soft robotic tissue.

Control of the Redox Potential by Oxygen Limitation Inhibits Bioleaching of Pyrite

2009 ◽  
Vol 71-73 ◽  
pp. 401-404 ◽  
Author(s):  
Biao Wu ◽  
Jian Kang Wen ◽  
Gui Ying Zhou ◽  
Ren Man Ruan
Keyword(s):  
Redox Potential ◽  
Dissolution Rate ◽  
Oxygen Limitation ◽  
Metal Sulfides ◽  
Electrochemical Studies ◽  
Redox Potentials ◽  
Nitrogen Gas ◽  
Copper Sulfides ◽  
Fe Content ◽  
Constant Potential

Based on the bioleaching mechanism and electrochemical studies of metal sulfides, the dissolution rate of secondary copper sulfides and pyrite are controlled by redox potentials. Experiment on the bioleaching of the secondary copper sulfides under constant potential by sparging with nitrogen gas demonstrated, by analyzing Cu and Fe content of the bioleaching solution and residues, the pyrite and secondary cooper sulfides dissolution rates have large difference in various redox potential. The pyrite and secondary cooper sulfides have good selection when the redox potential controlled between 700mV and 760mV, we can realize the secondary copper sulfides bioleaching process be controlled, then supply theoretical guide for the iron-acid balance during copper bioleaching process.

scholarly journals Multi-Material 3D Printed Shape Memory Polymer with Tunable Melting and Glass Transition Temperature Activated by Heat or Light

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 710 ◽  
Author(s):  
Ela Sachyani Keneth ◽  
Rama Lieberman ◽  
Matthew Rednor ◽  
Giulia Scalet ◽  
Ferdinando Auricchio ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Shape Memory ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
3D Structure ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Practical Applications ◽  
Different Temperatures ◽  
Robotic Devices

Shape memory polymers are attractive smart materials that have many practical applications and academic interest. Three-dimensional (3D) printable shape memory polymers are of great importance for the fabrication of soft robotic devices due to their ability to build complex 3D structures with desired shapes. We present a 3D printable shape memory polymer, with controlled melting and transition temperature, composed of methacrylated polycaprolactone monomers and N-Vinylcaprolactam reactive diluent. Tuning the ratio between the monomers and the diluents resulted in changes in melting and transition temperatures by 20, and 6 °C, respectively. The effect of the diluent addition on the shape memory behavior and mechanical properties was studied, showing above 85% recovery ratio, and above 90% fixity, when the concentration of the diluent was up to 40 wt %. Finally, we demonstrated multi-material printing of a 3D structure that can be activated locally, at two different temperatures, by two different stimuli; direct heating and light irradiation. The remote light activation was enabled by utilizing a coating of Carbon Nano Tubes (CNTs) as an absorbing material, onto sections of the printed objects.

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