26 research outputs found
UNDERSTANDING INTERNATIONAL RELATIONS THROUGH: SYSTEM APPROACH
System approach as a methodological tool of analyzing International Relations has gained great importance in the lexicology of political science. The meaning of this term is said to be quite imprecise and vague, but it become used wider. To better understand the main feature of the system approach in International Relations often is used the “international system”. The researches in the field developed basic framework to establish the basis on which the international arena can be regarded as a system. They regard not only nation-states, but also individuals as international actors, always standing in interaction with each other making the whole world as an organized complexity. Therefore, system approach contributes to understand and analyze International Relations as a system of interactions which are interdependent and interrelated
Synthesis of Core–Double Shell Nylon-ZnO/Polypyrrole Electrospun Nanofibers
Core–double shell nylon-ZnO/polypyrrole electrospun nanofibers were fabricated by combining three straightforward methods (electrospinning, sol–gel synthesis and electrodeposition). The hybrid fibrous organic–inorganic nanocomposite was obtained starting from freestanding nylon 6/6 nanofibers obtained through electrospinning. Nylon meshes were functionalized with a very thin, continuous ZnO film by a sol–gel process and thermally treated in order to increase its crystallinity. Further, the ZnO coated networks were used as a working electrode for the electrochemical deposition of a very thin, homogenous polypyrrole layer. X-ray diffraction measurements were employed for characterizing the ZnO structures while spectroscopic techniques such as FTIR and Raman were employed for describing the polypyrrole layer. An elemental analysis was performed through X-ray microanalysis, confirming the expected double shell structure. A detailed micromorphological characterization through FESEM and TEM assays evidenced the deposition of both organic and inorganic layers. Highly transparent, flexible due to the presence of the polymer core and embedding a semiconducting heterojunction, such materials can be easily tailored and integrated in functional platforms with a wide range of applications
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields
Polypyrrole Actuator Based on Electrospun Microribbons
The
development of soft actuators by using inexpensive raw materials
and straightforward fabrication techniques, aiming at creating and
developing muscle like micromanipulators, represents an important
challenge nowadays. Providing such devices with biomimetic qualities,
for example, sensing different external stimuli, adds even more complexity
to the task. We developed electroactive polymer-coated microribbons
that undergo conformational changes in response to external physical
and chemical parameters. These were prepared following three simple
steps. During the first step nylon-6/6 microribbons were fabricated
by electrospinning. In a second step the microribbons were one side
coated with a metallic layer. Finally, a conducting layer of polypyrrole
was added by means of electrochemical deposition. Strips of polypyrrole-coated
aligned microribbon meshes were tested as actuators responding to
current, pH, and temperature. The electrochemical activity of the
microstructured actuators was investigated by recording cyclic voltammograms.
Chronopontentiograms for specific current, pH, and temperature values
were obtained in electrolytes with different compositions. It was
shown that, upon variation of the external stimulus, the actuator
undergoes conformational changes due to the reduction processes of
the polypyrrole layer. The ability of the actuator to hold and release
thin wires, and to collect polystyrene microspheres from the bottom
of the electrochemical cell, was also investigated
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields
Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes
Eggshell
membranes were employed as biological scaffolds for developing
soft and versatile actuators. A particular architecture, consisting
of eggshell membrane coated with polypyrrole, has been fabricated
and has been found to be a green, inexpensive, lightweight, and easy
to handle class of actuators. The polypyrrole-coated eggshell membrane
devices were tested in liquid, ambient atmosphere and controlled humidity
environment, with the recorded movements proving their versatility.
In 1 M NaCl aqueous solution, by applying successive potential pulses,
the actuator contracts/expands owing to the expulsion/insertion of
the electrolyte ions out/into polypyrrole film, producing a displacement
of ∼0.1 cm. In air, upon application of voltages from 2 to
5 V on a V-shaped geometry actuator, it bends due to water desorption
from its structure induced by Joule heating, generating a displacement
which reaches ∼0.4 cm at 5 V. In a chamber with controlled
humidity, the decrease of humidity stimulates a bending/curling motion
of the actuator, achieving a displacement of ∼2.1 cm at 50%
relative humidity. Upon modification of the humidity, these actuators
move, hold, and release delicate and lightweight objects. Such polypyrrole-coated
eggshell membrane actuators which operate in different environments
and respond to multiple stimuli can have potential applications in
biomimetic micromanipulators or artificial muscle fields