Dynamic pattern of wrinkles in a dielectric elastomer

Soft Matter
A membrane of a dielectric elastomer may undergo electromechanical phase transition from the flat to wrinkled state, when the applied voltage reaches a critical value. The wrinkled region is observed to expand at the expense of the flat region during phase transition. In this paper, we report on a dynamic pattern of wrinkles in a circular membrane of a dielectric elastomer. During phase transition, both the flat and wrinkled regions move interchangeably in the membrane. The radial prestretch is found to significantly affect electromechanical phase transition. For example, a membrane of a small prestretch can exhibit a dynamic pattern of wrinkles, which is essentially related to snap-through instability. However, a membrane of a large prestretch undergoes continuous phase transition, without exhibiting the dynamic pattern. An analytical model is developed to interpret these experimental phenomena. Finite element simulations are performed to predict the wrinkle morphology, especially...  Read more

Photophysical Properties of a Series of Cycloplatinated(II) Complexes Featuring Allyldiphenylphosphane

New Journal of Chemistry
A series of cycloplatinated(II) complexes with general formula of [Pt(C^N)(Me)(PPh2allyl)], 1-4, C^N = deprotonated form of 2-phenylpyridine (ppy, 1), 2,2'-bipyridine (bpy, 2), 2,2'-bipyridine N-oxide (O-bpy, 3) and 7,8-benzohquinoline (bzq, 4) ligands, has been synthesized. The new complexes were characterized spectroscopically and the structures of complexes 1 and 4 were confirmed by single crystal X-ray crystallography. With the exception of the complex 3 (containing O-bpy), all the complexes exhibited strong luminescence at 298 K (solid) and 77 K (solution and solid). Upon photoexcitation, these complexes revealed the structured emission profiles which have a mixed 3ILCT/3MLCT (L = cyclometalated moieties) character in the emissive states. Besides, they represent a long...  Read more

Immobilization of Sulfur by Constructing Three-dimension Nitrogen Rich Carbons for Long Life Lithium-Sulfur Batteries

Journal of Materials Chemistry A
Lithium-sulfur (Li-S) batteries have been considered as next-generation rechargeable energy storage systems due to their high theoretical energy densities and low cost; however, the capacity decay resulting from the shuttle of lithium polysulfides (LiPSs) hinders the practical application. Herein, we describe a strategy to synthesize highly pyidinic-N-doped three-dimension (3D) carbons for chemisorption of LiPSs, which consist of zeolitic imidazolate framework-8-derived carbon (ZIF-8(C)) coated on the surface of N-doped carbon nanotubes supported by carbon nanosheets (NCNTs-CS-ZIF-8(C)). Using the obtained carbons as sulfur hosts, the S/NCNTs-CS-ZIF-8(C) cathodes show high sulfur utilization of 86 % at 0.1 C, low capacity decay rate of 0.052 % per cycle over 700 cycles at 1 C and impressive cycling life that is 564 mAh g-1 after 700 cycles at 1 C. First principle calculations based on Vienne Ab-Initio Simulation Package (VASP) reveal that increasing amount of pyidinic-N components can...  Read more

Unraveling viscosity effects on the hysteresis losses of magnetic nanocubes

Nanoscale
Hysteresis losses in magnetic nanoparticles constitute the basis of magnetic hyperthermia for delivering a local thermal stress. Nevertheless, this therapeutic modality is only to be realised through a careful appraisal of the best possible intrinsic and extrinsic conditions to the nanoparticles for which they maximise and preserve their heating capabilities. Low frequency (100 kHz) hysteresis loops accurately probe the dynamical magnetic response of magnetic nanoparticles in a more reliable manner than calorimetry measurements, providing conclusive quantitative data under different experimental conditions. We consider here a set of iron oxide or cobalt ferrite nanocubes of different sizes, through which we experimentally and theoretically study the influence of the viscosity of the medium on the low frequency hysteresis loops of magnetic colloids, and hence their ability to produce and dissipate heat to the surroundings. We analyse the role of nanoparticle size, size distribution,...  Read more

Grating-coupled surface plasmon resonance enhanced organic photovoltaic devices induced by Blu-ray disc recordable and Blu-ray disc grating structures

Nanoscale
In this work, we studied the performance enhancement of organic thin-film solar cells (OSCs) originating from the presence of diffraction gratings on the surfaces of the active layer. Two types of diffraction gratings, periodic gratings (Blu-ray disc recordable: BD-R) and quasi-random gratings (Blu-ray disc: BD), were employed as master templates for the grating structures. The grating structures were introduced to the surfaces of poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) films, which were the active layers of the solar cells. The addition of the grating structures led to an increase of light absorption in the absorption region of P3HT:PCBM induced by light scattering. Furthermore, the grating-coupled surface plasmon resonance generated additional light absorption peaks. With illumination of non-polarized light at a normal incident angle, the short-circuit current densities of the BD-R and BD solar cells improved by 11.05% and 10.6%, respectively....  Read more

Unique agreement of experimental and computational infrared spectroscopy: a case study of lithium bromide solvation in an important electrochemical solvent

Physical Chemistry Chemical Physics
Infrared (IR) spectroscopy is a widely used and invaluable tool in the studies of solvation phenomena in electrolyte solutions. Using state-of-the-art chemometric analysis of a spectral series measured in a concentration-dependent manner, the spectrum of the solute-affected solvent can be extracted, providing a detailed view of the structural and energetic states of the solvent molecules influenced by the solute. Concurrently, ab initio molecular dynamics (AIMD) simulations provide the solvation shell picture at an atomistic detail level and allow for a consistent decomposition of the theoretical IR spectrum in terms of distance-dependent contributions of the solvent molecules. Here, we show for the first time how the chemometric techniques designed with the analysis of experimental data in mind can be harnessed to extract corresponding information from the computed IR spectra for mutual benefit, but without any mutual input. The wide applicability of this two-track approach...  Read more

Application of machine/statistical learning, artificial intelligence and statistical experimental design for modeling and optimization of methylene blue and Cd (II) removal from binary aqueous solution by natural walnut carbon

Physical Chemistry Chemical Physics
Analytical chemists applied statistical methods for both validation and prediction of a proposed model. They need methods that were flexible adequate to find typical features of a dataset, such as nonlinearities and interactions. Boosted regression tree (BRT) as an ensemble technique is fundamentally different than other conventional techniques that aim of them is fit a single parsimonious model. In this work, BRT, artificial neural network (ANN) and response surface methodology (RSM) have been used for the optimization and/or modeling of stirred time (min), pH, adsorbent mass (mg) and concentrations of MB and Cd2+ ions (mg L-1) to develop respective predictive equations for simulation of the efficiency of MB and Cd2+ adsorption based on experimental data set. Activated carbon, as adsorbent, was synthesized from walnut wood waste which was abundant, non-toxic, cheap and locally available. This adsorbent was characterized by using different techniques such as FT-IR, BET, SEM, point...  Read more

Inclusion of lipopeptides into the DMPC lipid bilayer prevents Aβ peptide insertion

Physical Chemistry Chemical Physics
Using all-atom explicit water model and replica exchange with solute tempering molecular dynamics we have studied the binding of Abeta10-40 peptide to the mixed cationic bilayer composed of DMPC lipids and C14-KAAK lipopeptides (LP). Using as a control our previous replica exchange simulations probing binding of the same peptide to the zwitterionic DMPC bilayer we assessed the impact of lipopeptides on Abeta binding mechanism. We found that binding to the mixed DMPC+LP bilayer does not enhance Abeta helix propensity as much as binding to the pure DMPC bilayer. Tertiary interactions also differ in the peptide bound to the DMPC+LP bilayer due to reduced helix content, salt bridge disruption, and formation of new long-range hydrophobic interactions. More importantly, we showed that mixing lipopeptides into the DMPC bilayer prevents Abeta10-40 insertion forcing the peptide to reside on the bilayer surface and considerably destabilizes Abeta-bilayer interactions leading to formation of a...  Read more

Swelling-induced structural changes and microparticle uptake of gelatin gels probed by NMR and CLSM

Soft Matter
Gelatin gels are increasingly involved in many industrial applications due to several advantages including cost efficiency and biocompatibility. Generally, their production requires the use of aqueous solvents, which cause a significant swelling, due to the ability of solvent molecules to penetrate through the gel microstructure and increase its volume. Since swelling mechanisms and their effect on gel structure are not fully understood, further investigations are required. In this work, we combine macroscopic measurements of the swelling ratio (SR) with Nuclear Magnetic Resonance (NMR) and Confocal Laser Scanning Microscopy (CLSM) to investigate changes in gelatin structure as a function of both polymer concentration and swelling time. SR values increase as a function of time until a maximum is reached and then show a slight drop for all the gelatin concentrations after 24 h swelling time, probably due to a network relaxation process. NMR allows to determine mass transport and...  Read more

A new precursor to synthesize g-C3N4 with superior visible light absorption for photocatalytic application

Catalysis Science & Technology
Graphitic carbon nitride (g-C3N4) was synthesized with a new precursor (thiourea oxide) by a simple one-pot calcination method. The sulphur-oxygen co-doping could modulate the band structure of pristine g-C3N4, resulting in its absorbance edge up to 600 nm,which well consisted with DFT calculation. Thus, its photocatalytic property was enhanced.Read more

X-Ray Crystallographic and Computational Study on Uranyl-Salophen Complexes Bearing Nitro Groups

Dalton Transactions
In the solid state, salophen-UO2 complexes bearing one, two or three NO2 groups, lack of the pronounced ligand curvature which represents a structural hallmark for this class of compounds. A detailed structural study based on single crystal X-ray crystallography and computational methods, comprising Molecular Dynamics, gas phase Hartree Fock and DFT calculations, probes the coordination properties of the uranyl cation.Read more

Local remodeling of synthetic extracellular matrix microenvironments by co-cultured endometrial epithelial and stromal cells enables long-term dynamic physiological function

Integrative Biology
Mucosal barrier tissues, comprising a layer of tightly-bonded epithelial cells in intimate molecular communication with an underlying matrix-rich stroma containing fibroblasts and immune cells, are prominent targets for drugs against infection, chronic inflammation, and other disease processes. Although human in vitro models of such barriers are needed for mechanistic studies and drug development, differences in extracellular matrix (ECM) needs of epithelial and stromal cells hinder efforts to create such models. Here, using the endometrium as an example mucosal barrier, we describe a synthetic, modular ECM hydrogel suitable for 3D functional co-culture, featuring components that can be remodeled by cells and that respond dynamically to sequester local cell-secreted ECM characteristic of each cell type. The synthetic hydrogel combines peptides with off-the-shelf reagents and is thus accessible to cell biology labs. Specifically, we first identified a single peptide as...  Read more

Tunable and sizable bandgap of g-C3N4/ graphene /g-C3N4 sandwich heterostructure: a van der Waals density functional study

Journal of Materials Chemistry C
The structural and electronic properties of g-C3N4/graphene/g-C3N4 (g-C3N4/SLG/g-C3N4) sandwich heterostructures have been systematically investigated by density functional theory with van der Waals corrections. The results indicate that the band gap of g-C3N4/SLG/g-C3N4 sandwich heterostructure can be opened to 106 meV without strain. The strain is a promising way to tune the electronic properties of sandwich heterostructure. After applying uniaxial strain, the heterostructure can withstand larger tensile strain than compression strain without damaging the structure and the band gap is more easily increased by X-direction strain. When the 5% X-direction strain is applied, the band gap could be opened to 525 meV and meanwhile maintain a high carrier mobility. These electronic properties may provide a potential application in nanodevices.Read more

Large gap two dimensional topological insulators: bilayer triangular lattice TlM (M = N, P, As, Sb)

Journal of Materials Chemistry C
Based on density functional theory and Berry curvature calculations, we predict that emph{p}-emph{p} band inversion type quantum spin Hall effect (QSHE) can be realized in a series of two dimensional (2D) bilayer honeycomb TlM (M = N, P, As, Sb), which can be effectively equivalent to bilayer triangular lattice for low energy electrons. Further topological analysis reveals that the band inversion between $p_{z}^{-}$ and $p_{x,y}$ of M atom contributes to the nontrivial topological nature of TlM. The band inversion is independent of spin-orbit coupling which is distinctive from conventional topological insulators (TIs). A tight binding model based on triangle lattice is constructed to describe the QSH states in the systems. Besides the interesting 2D triangular lattice p-p type inversion for the topological mechanism, the maximal 550 meV local band gap (TlSb) and their tunable global band gap of the systems provide a new choice for future room temperature quantum spin Hall Insulator...  Read more

High-affinity metal binding by the Escherichia coli [NiFe]-hydrogenase accessory protein HypB is selectively modulated by SlyD

Metallomics
[NiFe]-hydrogenase, which catalyzes the reversible conversion between hydrogen gas and protons, is a vital component of the metabolism of many pathogens. Maturation of [NiFe]-hydrogenase requires selective nickel insertion that is completed, in part, by the metallochaperones SlyD and HypB. Escherichia coli HypB binds nickel with sub-picomolar affinity, and the formation of the HypB-SlyD complex activates nickel release from the high-affinity site (HAS) of HypB. In this study, the metal selectivity of this process was investigated. Biochemical experiments revealed that the HAS of full length HypB can bind stoichiometric zinc. Moreover, in contrast to the acceleration of metal release observed with nickel-loaded HypB, SlyD blocks the release of zinc from the HypB HAS. X-ray absorption spectroscopy (XAS) demonstrated that SlyD does not impact the primary coordination sphere of nickel or zinc bound to the HAS of HypB. Instead, computational modeling and X-ray absorption spectroscopy of...  Read more

A STOCHASTIC METHOD FOR ASPHALTENE STRUCTURE FORMULATION FROM EXPERIMENTAL DATA: AVOIDANCE OF IMPLAUSIBLE STRUCTURES

Physical Chemistry Chemical Physics
This work presents a stochastic procedure designed to formulate a discrete set of molecular structures that, as a whole, adjust properly to experimental asphaltene data. This algorithm incorporates the pentane effect concept and Clar’s sextet rule to the formulation process. The set of viable structures was constructed based on probability distribution functions obtained from experimental information and an isomer database containing all plausible configurations for a given number of rings, avoiding high-energy structures. This procedure was applied to a collection of experimental data from the literature. Ten sets, consisting of 5000 structures each, were obtained. Each set was then optimized. For the most accurate representation, four molecules were sufficient to properly reproduce the experimental input. The asphaltene system obtained is consistent with the reported molecular weight, number of aromatic rings and heteroatom content. Molecular dynamic simulations showed that the...  Read more

Distribution of Dopant Ions Around Poly(3,4-ethylenedioxythiophene) Chains: A Theoretical Study

Physical Chemistry Chemical Physics
The effect of counterions and multiple polymer chains on the properties and structure of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with have been examined using density functional theory (DFT) calculations with periodic boundary conditions (PBC). Calculations on a one-dimensional periodic model with four explicit polymer repeat units and two molecules indicate that the latters are separated as much as possible, the salt structure and band gap obtained from such distribution being in excellent agreement with those determined experimentally. On the other hand, DFT calculations on periodic models that include two chains indicate that neighboring PEDOT chains are shifted along the molecular axis by a half of the repeat unit length, dopant ions intercalated between the polymer molecules acting as cement. In order to support these structural features, classical Molecular Dynamics (MD) simulations have been performed on a multiphasic system consisting of 69 explicit PEDOT chains...  Read more

Preexisting domain motions underlie protonation-dependent structural transitions of the Ca2+-ATPase

Physical Chemistry Chemical Physics
We have performed microsecond molecular dynamics (MD) simulations to determine the mechanism for protonation-dependent structural transitions of the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Release of two H+ from the transport sites activates SERCA by inducing a structural transition between low (E2) and high (E1) Ca2+-affinity states (E2-to-E1 transition), but the structural mechanism by which transport site deprotonation facilitates this transition is unknown. We performed microsecond all-atom MD simulations to determine the effects of transport site protonation on the structural dynamics of the E2 state in solution. We found that the protonated E2 state has structural characteristics that are similar to those observed in crystal structures of E2. Upon deprotonation, a single Na+ ion rapidly (<10 ns) binds to the transmembrane transport sites and induces a kink in M5, disrupts the M3-M5 interface, and increases the mobility of M3/A-M3 linker. Principal component analysis...  Read more

ZnO Powders As Multi-Facet Single Crystals

Physical Chemistry Chemical Physics
Oxides are most commonly found in divided forms with the properties difficult to control since their crystallographic orientations usually escape analysis. To overcome this an appropriate model system can be provided by ZnO smoke which, obtained by combustion of Zn in air, exhibits nanoparticles with well-defined surface facets. The present work focuses on the interaction of water with ZnO smokes by combining density functional theory based simulations and infrared spectroscopy measurements with applied pressures from 10-7 to 1 mbar. We demonstrate the application of ultra-high vacuum to play a key factor within the adsorption process and report on water structures on ZnO (11-20) for the first time. We furthermore show that ZnO powders behave as multi-facet single crystals involving (10-10), (11-20), (0001), and (000-1) surfaces with the polar orientations corresponding to 25% of the total surface area. A great deal of cross-agreements between experimental...  Read more

How does ytterbium chloride interact with DMPC bilayers? A computational and experimental study

Physical Chemistry Chemical Physics
Lanthanide salts have been studied for many years, primarily in Nuclear Magnetic Resonance (NMR) experiments of mixed lipid–protein systems and more recently to study lipid flip-flop in model membrane systems. It is well recognised that lanthanide salts can influence the behaviour of both lipid and protein systems, however a full molecular level description of lipid–lanthanide interactions is still outstanding. Here we present a study of lanthanide–bilayer interactions, using molecular dynamics computer simulations, fluorescence electrostatic potential experiments and nuclear magnetic resonance. Computer simulations reveal the microscopic structure of DMPC lipid bilayers in the presence of Yb3+, and a surprising ability of the membranes to adsorb significant concentrations of Yb3+ without disrupting the overall membrane structure. At concentrations commonly used in NMR experiments, Yb3+ ions bind...  Read more