Dexamethasone Attenuates the Expression of MMP-13 in Chondrocytes through MKP-1.

Mitogen-activated protein kinase phosphatase-1 (MKP-1) is upregulated in inflammation and reduces the activity of proinflammatory mitogen-activated protein kinases (MAP kinases) by dephosphorylation. MAP kinases are intracellular signaling pathways that mediate the cellular effects of proinflammatory cytokines. In the present study, we investigated the effects of the glucocorticoid dexamethasone on the expression of catabolic enzymes in chondrocytes and tested the hypothesis that these effects are mediated through MKP-1.

Transient Receptor Potential Ankyrin 1 Enhances Ovalbumin-Induced Acute Allergic Inflammation in Murine Models.

Background: Transient receptor potential ankyrin 1 (TRPA1) is an ion channel known to mediate nociception and neurogenic inflammation, and to be activated by reactive oxygen and nitrogen species (ROS and RNS) produced at the sites of inflammation. Because neurogenic inflammation as well as the release of ROS and RNS are typical features of early stages of allergic responses, we hypothesized that TRPA1 may be involved in triggering and/or amplifying allergic inflammation.

Objective: This study aims at exploring the role of TRPA1 ion channel in acute ovalbumin-induced allergic inflammation in applicable murine models.

Kohn-Sham Decomposition in Real-Time Time-Dependent Density-Functional Theory: An Efficient Tool for Analyzing Plasmonic Excitations.

Electronic excitations can be efficiently analyzed in terms of the underlying Kohn-Sham (KS) electron-hole transitions. While such a decomposition is readily available in the linear-response time-dependent density-functional theory (TDDFT) approaches based on the Casida equations, a comparable analysis is less commonly conducted within the real-time-propagation TDDFT (RT-TDDFT). To improve this situation, we present here an implementation of a KS decomposition tool within the local-basis-set RT-TDDFT code in the free GPAW package.

Substitutional carbon doping of free-standing and Ru-supported BN sheets: a first-principles study.

The development of spatially homogeneous mixed structures with boron (B), nitrogen (N) and carbon (C) atoms arranged in a honeycomb lattice is highly desirable, as they open the possibility of creating stable two-dimensional materials with tunable band gaps. However, at least in the free-standing form, the mixed BCN system is energetically driven towards phase segregation to graphene and hexagonal BN. It is possible to overcome the segregation when BCN material is grown on a particular metal substrate, for example Ru(0 0 0 1), but the stabilization mechanism is still unknown.

Computational model for noncontact atomic force microscopy: energy dissipation of cantilever.

We propose a computational model for noncontact atomic force microscopy (AFM) in which the atomic force between the cantilever tip and the surface is calculated using a molecular dynamics method, and the macroscopic motion of the cantilever is modeled by an oscillating spring. The movement of atoms in the tip and surface is connected with the oscillating spring using a recently developed coupling method. In this computational model, the oscillation energy is dissipated, as observed in AFM experiments.

Quantized Evolution of the Plasmonic Response in a Stretched Nanorod.

Quantum aspects, such as electron tunneling between closely separated metallic nanoparticles, are crucial for understanding the plasmonic response of nanoscale systems. We explore quantum effects on the response of the conductively coupled metallic nanoparticle dimer. This is realized by stretching a nanorod, which leads to the formation of a narrowing atomic contact between the two nanorod ends.

Monosodium iodoacetate-induced inflammation and joint pain are reduced in TRPA1 deficient mice--potential role of TRPA1 in osteoarthritis.

Objectives: Intra-articularly injected monosodium iodoacetate (MIA) induces joint pathology mimicking osteoarthritis (OA) and it is a widely used experimental model of OA. MIA induces acute inflammation, cartilage degradation and joint pain. Transient Receptor Potential Ankyrin 1 (TRPA1) is an ion channel known to mediate nociception and neurogenic inflammation.

Nanoplasmonics simulations at the basis set limit through completeness-optimized, local numerical basis sets.

We present an approach for generating local numerical basis sets of improving accuracy for first-principles nanoplasmonics simulations within time-dependent density functional theory. The method is demonstrated for copper, silver, and gold nanoparticles that are of experimental interest but computationally demanding due to the semi-core d-electrons that affect their plasmonic response. The basis sets are constructed by augmenting numerical atomic orbital basis sets by truncated Gaussian-type orbitals generated by the completeness-optimization scheme, which is applied to the photoabsorption spectra of homoatomic metal atom dimers.

Urate crystal induced inflammation and joint pain are reduced in transient receptor potential ankyrin 1 deficient mice--potential role for transient receptor potential ankyrin 1 in gout.

Introduction: In gout, monosodium urate (MSU) crystals deposit intra-articularly and cause painful arthritis. In the present study we tested the hypothesis that Transient Receptor Poten-tial Ankyrin 1 (TRPA1), an ion channel mediating nociceptive signals and neurogenic in-flammation, is involved in MSU crystal-induced responses in gout by utilizing three experi-mental murine models.

Methods: The effects of selective pharmacological inhibition (by HC-030031) and genetic depletion of TRPA1 were studied in MSU crystal-induced inflammation and pain by using 1) spontaneous weight-bearing test to assess MSU crystal-induced joint pain, 2) subcutaneous air-pouch model resembling joint inflammation to measure MSU crystal-induced cytokine production and inflammatory cell accumulation, and 3) MSU crystal-induced paw edema to assess acute vascular inflammatory responses and swelling.

Formation, migration, and clustering of point defects in CuInSe2 from first principles.

The electronic properties of high-efficiency CuInSe(2) (CIS)-based solar cells are affected by the microstructural features of the absorber layer, such as point defect types and their distribution. Recently, there has been controversy over whether some of the typical point defects in CIS--V(Cu), V(Se), In(Cu), Cu(In)--can form stable complexes in the material. In this work, we demonstrate that the presence of defect complexes during device operational time can be justified by taking into account the thermodynamic and kinetic driving forces acting behind defect microstructure formation.

Dynamical coupling of plasmons and molecular excitations by hybrid quantum/classical calculations: time-domain approach.

The presence of plasmonic material influences the optical properties of nearby molecules in untrivial ways due to the dynamical plasmon-molecule coupling. We combine quantum and classical calculation schemes to study this phenomenon in a hybrid system that consists of a Na(2) molecule located in the gap between two Au/Ag nanoparticles. The molecule is treated quantum-mechanically with time-dependent density-functional theory, and the nanoparticles with quasistatic classical electrodynamics.

Coronene encapsulation in single-walled carbon nanotubes: stacked columns, peapods, and nanoribbons.

Encapsulation of coronene inside single-walled carbon nanotubes (SWNTs) was studied under various conditions. Under high vacuum, two main types of molecular encapsulation were observed by using transmission electron microscopy: coronene dimers and molecular stacking columns perpendicular or tilted (45-60°) with regard to the axis of the SWNTs. A relatively small number of short nanoribbons or polymerized coronene molecular chains were observed.

First-principles study of layered antiferromagnetic CuCrX2 (X = S, Se and Te).

We present detailed electronic band-structure calculations for antiferromagnetic chromium compounds, CuCrX(2) (X = S, Se or Te), carried out using spin-polarized density functional theory within the generalized-gradient approximation (GGA). A narrow-band semiconductor-to-metal transition is observed upon replacement of S or Se by Te. The indirect bandgap is found at 0.

Fast convergence to equilibrium for long-chain polymer melts using a MD/continuum hybrid method.

Effective and fast convergence toward an equilibrium state for long-chain polymer melts is realized by a hybrid method coupling molecular dynamics and the elastic continuum. The required simulation time to achieve the equilibrium state is reduced compared with conventional equilibration methods. The polymers move on a wide range phase space due to large-scale fluctuation generated by the elastic continuum.

Are we van der Waals ready?

We apply a range of density-functional-theory-based methods capable of describing van der Waals interactions with weakly bonded layered solids in order to investigate their accuracy for extended systems. The methods under investigation are the local-density approximation, semi-empirical force fields, non-local van der Waals density functionals and the random-phase approximation. We investigate the equilibrium geometries, elastic constants and binding energies of a large and diverse set of compounds and arrive at conclusions about the reliability of the different methods.

d0 ferromagnetic interface between nonmagnetic perovskites.

We use computational and experimental methods to study d(0) ferromagnetism at a charge-imbalanced interface between two perovskites. In SrTiO(3)/KTaO(3) superlattice calculations, the charge imbalance introduces holes in the SrTiO(3) layer, inducing a d(0) ferromagnetic half-metallic 2D hole gas at the interface oxygen 2p orbitals. The charge imbalance overrides doping by vacancies at realistic concentrations.

van der Waals bonding in layered compounds from advanced density-functional first-principles calculations.

Although the precise microscopic knowledge of van der Waals interactions is crucial for understanding bonding in weakly bonded layered compounds, very little quantitative information on the strength of interlayer interaction in these materials is available, either from experiments or simulations. Here, using many-body perturbation and advanced density-functional theory techniques, we calculate the interlayer binding and exfoliation energies for a large number of layered compounds and show that, independent of the electronic structure of the material, the energies for most systems are around 20  meV/Å2. This universality explains the successful exfoliation of a wide class of layered materials to produce two-dimensional systems, and furthers our understanding the properties of layered compounds in general.

Asthmatic cough and airway oxidative stress.

The mechanisms of cough in asthma are unclear. Asthma is associated with an oxidative stress. Many reactive oxygen species sensitize or activate sensory C-fibers which are capable to induce cough.

TRPA1 contributes to the acute inflammatory response and mediates carrageenan-induced paw edema in the mouse.

Transient receptor potential ankyrin 1 (TRPA1) is an ion channel involved in thermosensation and nociception. TRPA1 is activated by exogenous irritants and also by oxidants formed in inflammatory reactions. However, our understanding of its role in inflammation is limited.

Vacancies in CuInSe2: new insights from hybrid-functional calculations.

We calculate the energetics of vacancies in CuInSe(2) using a hybrid functional (HSE06, HSE standing for Heyd, Scuseria and Ernzerhof), which gives a better description of the band gap compared to (semi)local exchange-correlation functionals. We show that, contrary to present beliefs, copper and indium vacancies induce no defect levels within the band gap and therefore cannot account for any experimentally observed levels. The selenium vacancy is responsible for only one level, namely, a deep acceptor level ε(0/2-).

Synthesis of graphene nanoribbons encapsulated in single-walled carbon nanotubes.

A novel material, graphene nanoribbons encapsulated in single-walled carbon nanotubes (GNR@SWNT), was synthesized using confined polymerization and fusion of polycyclic aromatic hydrocarbon (PAH) molecules. Formation of the GNR is possible due to confinement effects provided by the one-dimensional space inside nanotubes, which helps to align coronene or perylene molecules edge to edge to achieve dimerization and oligomerization of the molecules into long nanoribbons. Almost 100% filling of SWNT with GNR is achieved while nanoribbon length is limited only by the length of the encapsulating nanotube.

Mechanisms of postsynthesis doping of boron nitride nanostructures with carbon from first-principles simulations.

Electron-beam-mediated postsynthesis doping of boron-nitride nanostructures with carbon atoms [Nature (London) 464, 571 (2010); J. Am. Chem.