455 research outputs found
On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field
At concentrated electrolytes,
the ionāion electrostatic
correlation effect is considered an important factor in electrokinetics.
In this paper, we compute, in theory and simulation, the dipole moment
for a spherical particle (charged, dielectric) under the action of
an alternating electric field using the modified continuum PoissonāNernstāPlanck
(PNP) model by Bazant et al. [Double Layer in Ionic Liquids: Overscreening Versus Crowding. Phys. Rev. Lett. 2011, 106, 046102] We investigate
the dependency of the dipole moment in terms of frequency and its
variation with such quantities like Ī¶-potential, electrostatic
correlation length, and double-layer thickness. With thin electric
double layers, we develop simple models through performing an asymptotic
analysis of the modified PNP model. We also present numerical results
for an arbitrary Debye screening length and electrostatic correlation
length. From the results, we find a complicated impact of electrostatic
correlations on the dipole moment. For instance, with increasing the
electrostatic correlation length, the dipole moment decreases and
reaches a minimum and then it goes up. This is because of initially
decreasing of surface conduction and finally increasing due to the
impact of ionāion electrostatic correlations on ionās
convection and migration. Also, we show that in contrast to the standard
PNP model, the modified PNP model can qualitatively explain the data
from the experimental results in multivalent electrolytes
Secrecy performance analysis of a cognitive network for IoT over k-Ī¼ channels
With the development of Internet of Things (IoTs), devices are now connecting and communicating together on a heretofore
unheard-of scale, forming huge heterogeneous networks of mobile IoT-enabled devices. For beyond 5G- (B5G-) enabled
networks, this raises concerns in terms of spectral resource allocation and associated security. Cognitive radio is one effective
solution to such a spectrum sharing issue which can be adopted to these B5G networks, which works on the principle of sharing
spectrum between primary and secondary users. In this paper, we develop the confidentiality of cognitive radio network (CRNs)
for IoT over k-Ī¼ fading channels, with the information transmitted between secondary networks with multiple cooperative
eavesdroppers, under the constraint of the maximum interference that the primary users can tolerate. All considered facilities
use a single-antenna receiver. Of particular interest, the minimum limit values of secure outage probability (SOP) and the
probability of strictly positive secrecy capacity (SPSC) are developed for this model in a concise form. Finally, the Monte Carlo
simulations for the system are provided to support the theoretical analysis presente
Study of the molecular array behaviours and interfacial activities of green surfactant alkyl polyglycoside and the mixed systems with other surfactants on oilāwater interface
<p>The widely performance of surfactants is closely related to their interfacial activity, which is essentially determined by the molecular array behaviours at the interface, of which the studies are significance for clearly understanding their structure-performance relationships. In this paper, the detailed molecular array behaviours of green surfactant alkyl polyglycoside (APG) and the mixed systems with other types of surfactants on oil/water interface have been studied using molecular dynamics simulations, and the key theoretical principle was confirmed by quantum chemistry calculations. It was found that the hydrophilic maltose ring head groups of decyl polyglycoside (C<sub>10</sub>-APG) are prone to lie flatly at the oilāwater interface, the steric hindrance results in the low interfacial density, which critically determines the limit of the interfacial activity. The interfacial adsorption behaviours of the binary mixtures of C<sub>10</sub>-APG and SDS or DATB and the ternary mixtures of C<sub>10</sub>-APG, SDS and DATB were studied in detail, how the efficient synergism effect could be achieved for the mixture to get super high interfacial activity was discussed. This study provides a strategy to reveal how the molecular interfacial behaviours determine the key interfacial characteristics of the novel surfactants, which might provide help to promote their applications.</p
Mechanically Robust Flexible Polyurethane Foams Formulated with Polyols Comprising Soybean Protein
Soybean protein is a compelling raw material for the
preparation
of high-performance biobased polyurethane (PU) foams in light of its
rich polyfunctional moieties containing active hydrogens. However,
soybean protein is immiscible with polyols owing to the presence of
numerous carboxylic groups of strong polarity, which in turn results
in below-par mechanical performance when it is simply applied as a
spherical physical filler in a target matrix. In this study, the solubility
of soybean protein in polyols is realized through esterification to
enable a designated hydroxyl functionality. The esterification process
not only converts the original carboxylic group into an ester moiety
but also correspondingly introduces hydroxyl groups into the macromolecules.
This increases the content of active hydrogens, which ultimately facilitates
the subsequent reactions with isocyanates. As a result, the esterified
soybean protein (ESP)-derived flexible PU foam exhibits dual excellence
in tensile strength and toughness, and its compressive strength and
modulus have been improved by 3.2 and 2.5 times, respectively, when
compared to the unmodified SP-reinforced PU. Moreover, the incorporation
of ESP into the PU framework on a molecular level enables the formation
of a secondary interpenetrating network that improves the resilience
of the matrix. The as-fabricated foam delivers a superior compressive
recovery rate of up to 98.6% even after 150 cycles, which stands out
prominently among reports on biobased PU. This work demonstrates a
simple and green method to transform soybean protein into biomass-derived
multifunctional polyols, which could spur innovations from the community
toward high-performance biobased polymeric materials
A Co-Crystal Strategy to Tune the Supramolecular Patterns and Luminescent Properties: Ten Well-Designed Salts Assembled by Arenedisulfonic Acid with Diverse Diamines
Ten salts assembled by arenedisulfonic acid with hydrazine,
flexible aliphatic diamines, rigid and semirigid aromatic diamines,
namely, (H<sub>2</sub>HA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>1</b>), (H<sub>2</sub>EDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>2</b>), (H<sub>2</sub>PDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>3</b>), (H<sub>2</sub>BTDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>4</b>), (H<sub>2</sub>BDMA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·2H<sub>2</sub>O (<b>5</b>), 2Ā(<i>o</i>-HBDA)<sup>+</sup>Ā·(NDS)<sup>2ā</sup> (<b>6</b>), (<i>m</i>-H<sub>2</sub>BDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>7</b>), (H<sub>2</sub>MBDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·3H<sub>2</sub>O (<b>8</b>), (H<sub>2</sub>SDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·H<sub>2</sub>O (<b>9</b>), and 2Ā(HSDA)<sup>+</sup>Ā·(NDS)<sup>2ā</sup>Ā·H<sub>2</sub>O (<b>10</b>) (H<sub>2</sub>NDS = 1,5-naphthalenedisulfonic
acid, HA = hydrazine, EDA = 1,2-ethanediamine, PDA = 1,3-propanediamine,
BTDA = 1,4-butanediamine, BDMA = 1,3-benzenedimethanamine, <i>o</i>-BDA = 1,2-benzenediamine, <i>m</i>-BDA = 1,3-benzenediamine,
MBDA = 4-methyl-1,3-benzenediamine, SDA = 4,4ā²-sulfonyldiamiline),
have been constructed and characterized by elemental analysis, infrared,
thermogravimetric analysis, phospholuminescence, and powder and single-crystal
X-ray diffraction. Structural analyses indicate that the nature of
the diamines can effectively influence the final structures of the
salts through diverse noncovalent bonding interactions, such as hydrogen
bonds, ĻĀ·Ā·Ā·Ļ stacking, NāHĀ·Ā·Ā·Ļ,
CāHĀ·Ā·Ā·Ļ, and lone pairĀ·Ā·Ā·Ļ
interactions, which result in six types of architectures. Crystals <b>1</b>ā<b>3</b> exhibit a three-dimensional (3-D)
pillared layered supramolecular network with the diammonium cations
being sandwiched among the sulfonate groups, while crystal <b>4</b> exhibits a 3-D āhoneycombā network with the ā(CH<sub>2</sub>)<sub>4</sub>ā groups being encapsulated among the
NDS<sup>2ā</sup> anions. In comparison with crystal <b>4</b>, crystals <b>5</b>, <b>7</b>, and <b>8</b> exhibit
a different 3-D supramolecular network, in which the phenylene, phenyl,
and methylphenyl groups interpenetrate with the naphthyl rings of
NDS<sup>2ā</sup> anions through continuous ĻĀ·Ā·Ā·Ļ
interactions. Crystal <b>6</b> is two-dimensional pillared layered
network with the <i>o</i>-HBDA<sup>+</sup> cations arranging
along the two sides of the layer. Crystal <b>9</b> possesses
an organic 3-D supramolecular network formed by the CāHĀ·Ā·Ā·Ļ
and sulfonyl involved lone pairĀ·Ā·Ā·Ļ interactions
which encapsulates a one-dimensional (1-D) infinite [āSO<sub>3</sub>Ā·Ā·Ā·H<sub>3</sub>Nā]<sub><i>n</i></sub> nanotube in the large voids. By contrast, crystal <b>10</b> possesses an organic 3-D supramolecular network formed by intricate
CāHĀ·Ā·Ā·Ļ, ĻĀ·Ā·Ā·Ļ,
and sulfonyl involved C/NāHĀ·Ā·Ā·O interactions
which encapsulates 1-D ācentipede-shapedā [āSO<sub>3</sub>Ā·Ā·Ā·H<sub>3</sub>Nā]<sub><i>n</i></sub> chains in the large voids. Luminescent investigations demonstrate
that the salts containing aliphatic diamines exhibit stronger emission
intensity than those containing aromatic diamines. This result indicates
that the H<sub>2</sub>NDS might be used to distinguish the aliphatic
diamine from aromatic diamine qualitatively through the luminescent
signal
Mechanically and Electrically Enhanced CNTāCollagen Hydrogels As Potential Scaffolds for Engineered Cardiac Constructs
With
the development of biomimetic scaffolds for engineered cardiac
constructs, a considerable number of biomaterials has been evaluated.
However, in most previously reported cardiac constructs, the function
of the cardiomyocytes (CMs) is restricted because of mismatches in
the mechanics, conductivity, and submicrometer structure of the matrix.
In this work, type I collagen hydrogels were combined with carbon
nanotubes (CNTs) to assess potential improvements in hydrogel strength
and conductivity and potential effects on the hydrogel structure.
CMs seeded within the CNTācollagen hybrid hydrogels showed
improved cardiac cell functions compared to those within pure collagen
hydrogels, which suggested great promise of CNTācollagen hydrogels
as functional scaffold materials for cardiac construct engineering
Equivalent Reactor Network Model for the Modeling of Fluid Catalytic Cracking Riser Reactor
Modeling
description of riser reactors is a highly interesting
issue in design and development of fluid catalytic cracking (FCC)
processes. However, one of the challenging problems in the modeling
of FCC riser reactors is that sophisticated flow-reaction models with
high accuracy require time-consuming computation, while simple flow-reaction
models with fast computation result in low-accuracy predictions. This
dilemma requires new types of coupled flow-reaction models, which
should own time-efficient computation and acceptable model accuracy.
In this investigation, an Equivalent Reactor Network (ERN) model was
developed for a pilot FCC riser reactor. The construction procedure
of the ERN model contains two main steps: hydrodynamic simulations
under reactive condition and determination of the equivalent reactor
network structure. Numerical results demonstrate that with the ERN
model the predicted averaged error of the product yields at the riser
outlet is 4.69% and the computation time is ā¼5 s. Contrast
to the ERN model, the predicted error with the plug-flow model is
almost three times larger (12.79%), and the computational time of
the CFD model is 0.1 million times longer (6.7 days). The superiority
of the novel ERN model can be ascribed to its reasonably simplifying
transport process and avoiding calculation divergences in most CFD
models, as well as taking the back-mixing behavior in the riser into
consideration where the plug-flow model does not do so. In summary,
the findings indicate the capabilities of the ERN model in modeling
description of FCC riser reactors and the possibilities of the model
being applied to studies on the dynamic simulation, optimization,
and control of FCC units in the future
Lagrange stress versus stretch in the plane of symmetry for loading velocity of 10 mms-1 (strain rate 2s-1), 100 mms-1 (strain rate 20s-1), and 500 mms-1 (strain rate100s-1).
<p>Lagrange stress versus stretch in the plane of symmetry for loading velocity of 10 mms-1 (strain rate 2s-1), 100 mms-1 (strain rate 20s-1), and 500 mms-1 (strain rate100s-1).</p
A Co-Crystal Strategy to Tune the Supramolecular Patterns and Luminescent Properties: Ten Well-Designed Salts Assembled by Arenedisulfonic Acid with Diverse Diamines
Ten salts assembled by arenedisulfonic acid with hydrazine,
flexible aliphatic diamines, rigid and semirigid aromatic diamines,
namely, (H<sub>2</sub>HA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>1</b>), (H<sub>2</sub>EDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>2</b>), (H<sub>2</sub>PDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>3</b>), (H<sub>2</sub>BTDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>4</b>), (H<sub>2</sub>BDMA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·2H<sub>2</sub>O (<b>5</b>), 2Ā(<i>o</i>-HBDA)<sup>+</sup>Ā·(NDS)<sup>2ā</sup> (<b>6</b>), (<i>m</i>-H<sub>2</sub>BDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup> (<b>7</b>), (H<sub>2</sub>MBDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·3H<sub>2</sub>O (<b>8</b>), (H<sub>2</sub>SDA)<sup>2+</sup>Ā·(NDS)<sup>2ā</sup>Ā·H<sub>2</sub>O (<b>9</b>), and 2Ā(HSDA)<sup>+</sup>Ā·(NDS)<sup>2ā</sup>Ā·H<sub>2</sub>O (<b>10</b>) (H<sub>2</sub>NDS = 1,5-naphthalenedisulfonic
acid, HA = hydrazine, EDA = 1,2-ethanediamine, PDA = 1,3-propanediamine,
BTDA = 1,4-butanediamine, BDMA = 1,3-benzenedimethanamine, <i>o</i>-BDA = 1,2-benzenediamine, <i>m</i>-BDA = 1,3-benzenediamine,
MBDA = 4-methyl-1,3-benzenediamine, SDA = 4,4ā²-sulfonyldiamiline),
have been constructed and characterized by elemental analysis, infrared,
thermogravimetric analysis, phospholuminescence, and powder and single-crystal
X-ray diffraction. Structural analyses indicate that the nature of
the diamines can effectively influence the final structures of the
salts through diverse noncovalent bonding interactions, such as hydrogen
bonds, ĻĀ·Ā·Ā·Ļ stacking, NāHĀ·Ā·Ā·Ļ,
CāHĀ·Ā·Ā·Ļ, and lone pairĀ·Ā·Ā·Ļ
interactions, which result in six types of architectures. Crystals <b>1</b>ā<b>3</b> exhibit a three-dimensional (3-D)
pillared layered supramolecular network with the diammonium cations
being sandwiched among the sulfonate groups, while crystal <b>4</b> exhibits a 3-D āhoneycombā network with the ā(CH<sub>2</sub>)<sub>4</sub>ā groups being encapsulated among the
NDS<sup>2ā</sup> anions. In comparison with crystal <b>4</b>, crystals <b>5</b>, <b>7</b>, and <b>8</b> exhibit
a different 3-D supramolecular network, in which the phenylene, phenyl,
and methylphenyl groups interpenetrate with the naphthyl rings of
NDS<sup>2ā</sup> anions through continuous ĻĀ·Ā·Ā·Ļ
interactions. Crystal <b>6</b> is two-dimensional pillared layered
network with the <i>o</i>-HBDA<sup>+</sup> cations arranging
along the two sides of the layer. Crystal <b>9</b> possesses
an organic 3-D supramolecular network formed by the CāHĀ·Ā·Ā·Ļ
and sulfonyl involved lone pairĀ·Ā·Ā·Ļ interactions
which encapsulates a one-dimensional (1-D) infinite [āSO<sub>3</sub>Ā·Ā·Ā·H<sub>3</sub>Nā]<sub><i>n</i></sub> nanotube in the large voids. By contrast, crystal <b>10</b> possesses an organic 3-D supramolecular network formed by intricate
CāHĀ·Ā·Ā·Ļ, ĻĀ·Ā·Ā·Ļ,
and sulfonyl involved C/NāHĀ·Ā·Ā·O interactions
which encapsulates 1-D ācentipede-shapedā [āSO<sub>3</sub>Ā·Ā·Ā·H<sub>3</sub>Nā]<sub><i>n</i></sub> chains in the large voids. Luminescent investigations demonstrate
that the salts containing aliphatic diamines exhibit stronger emission
intensity than those containing aromatic diamines. This result indicates
that the H<sub>2</sub>NDS might be used to distinguish the aliphatic
diamine from aromatic diamine qualitatively through the luminescent
signal
Theoretical curves for the Fung, Gent and Ogden models at each loading velocity.
<p>Theoretical curves for the Fung, Gent and Ogden models at each loading velocity.</p
- ā¦