Simulation of Dielectric Properties of Nanocomposites with Non-Uniform Filler Distribution.

Dielectric properties for nanocomposites with metallic fillers inside a polymer matrix were determined using CST STUDIO SUITE-Electromagnetic field simulation software followed by the free-space Nicolson-Ross-Weir procedure. The structure is randomly generated to simulate the intrinsic non-uniformity of real nanomaterials. Cubic insertions were equated to corresponding spherical particles in order to provide either the same volume index or the same exterior surface index. The energy concentration around the inserts and within the entire material was determined as useful information in practice in order to design materials tailored to avoid exceeding the field/temperature limit values. The paper successfully associated the dialectic measurements with the results from the computer simulations, which are mainly based on energetic effects in electromagnetic applications. The experimental results are comparable with the software simulation in terms of precision. The conclusions outline the practical applications of the method for both electromagnetic shielding and microwave domain/telecommunications applications.

Evidence of the Anomalous Fluctuating Magnetic State by Pressure-Driven 4f Valence Change in EuNiGe3.

In rare-earth compounds with valence fluctuation, the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration and the magnetic moment. Here, we provide direct experimental evidence for an induced magnetic polarization of the Eu3+ atomic shell with J = 0, due to intra-atomic exchange and spin-orbital coupling interactions with the Eu2+ atomic shell. By applying external pressure, a transition from antiferromagnetic to a fluctuating behavior in EuNiGe3 single crystals is probed. Magnetic polarization is observed for both valence states of Eu2+ and Eu3+ across the entire pressure range. The anomalous magnetism is discussed in terms of a homogeneous intermediate valence state where frustrated Dzyaloshinskii-Moriya couplings are enhanced by the onset of spin-orbital interaction and engender a chiral spin-liquid-like precursor.

Chiral surface spin textures in Cu2OSeO3 unveiled by soft X-ray scattering in specular reflection geometry.

Resonant elastic soft X-ray magnetic scattering (XRMS) is a powerful tool to explore long-periodic spin textures in single crystals. However, due to the limited momentum transfer range imposed by long wavelengths of photons in the soft x-ray region, Bragg diffraction is restricted to crystals with the large lattice parameters. Alternatively, small-angle X-ray scattering has been involved in the soft energy X-ray range which, however, brings in difficulties with the sample preparation that involves focused ion beam milling to thin down the crystal to below a few hundred nm thickness. We show how to circumvent these restrictions using XRMS in specular reflection from a sub-nanometer smooth crystal surface. The method allows observing diffraction peaks from the helical and conical spin modulations at the surface of a Cu   2 OSeO   3 single crystal and probing their corresponding chirality as contributions to the dichroic scattered intensity. The results suggest a promising way to carry out XRMS studies on a plethora of noncentrosymmetric systems hitherto unexplored with soft X-rays due to the absence of the commensurate Bragg peaks in the available momentum transfer range.

Perpendicular and in-plane hole asymmetry in a strained NiFe2O4film.

Strained materials can exhibit drastically modified physical properties in comparison to their fully relaxed analogues. We report on the x-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of a strained NiFe2O4inverse spinel film grown on a symmetry matched single crystal MgGa2O4substrate. The Ni XAS spectra exhibit a sizable difference in the white line intensity for measurements with the x-ray electric field parallel to the film plane (normal incidence) vs when the electric field is at an angle (off-normal). A considerable difference is also observed in the FeL2,3XMCD spectrum. Modeling of the XAS and XMCD spectra indicate that the modified energy ordering of the cation 3dstates in the strained film leads to a preferential filling of 3dstates with out-of-plane character. In addition, the results point to the utility of x-ray spectroscopy in identifying orbital populations even with elliptically polarized x-rays.

Observation of compact ferrimagnetic skyrmions in DyCo3 film.

Owing to the experimental discovery of magnetic skyrmions stabilized by the Dzyaloshinskii-Moriya and/or dipolar interactions in thin films, there is a recent upsurge of interest in magnetic skyrmions with antiferromagnetic spins in order to overcome the fundamental limitations inherent with skyrmions in ferromagnetic materials. Here, we report on the observation of compact ferrimagnetic skyrmions for the class of amorphous alloys consisting of 4f rare-earth and 3d transition-metal elements with perpendicular magnetic anisotropy, using a DyCo3 film, that are identified by combining X-ray magnetic scattering, scanning transmission X-ray microscopy, and Hall transport technique. These skyrmions, with antiparallel aligned Dy and Co magnetic moments and a characteristic core radius of about 40 nm, are formed during the nucleation and annihilation of the magnetic maze-like domain pattern exhibiting a topological Hall effect contribution. Our findings provide a promising route for fundamental research in the field of ferrimagnetic/antiferromagnetic spintronics towards practical applications.

Ferromagnetic Resonance with Magnetic Phase Selectivity by Means of Resonant Elastic X-Ray Scattering on a Chiral Magnet.

Cubic chiral magnets, such as Cu_{2}OSeO_{3}, exhibit a variety of noncollinear spin textures, including a trigonal lattice of spin whirls, the so-called skyrmions. Using magnetic resonant elastic x-ray scattering (REXS) on a crystalline Bragg peak and its magnetic satellites while exciting the sample with magnetic fields at gigahertz frequencies, we probe the ferromagnetic resonance (FMR) modes of these spin textures by means of the scattered intensity. Most notably, the three eigenmodes of the skyrmion lattice are detected with large sensitivity. As this novel technique, which we label REXS FMR, is carried out at distinct positions in reciprocal space, it allows us to distinguish contributions originating from different magnetic states, providing information on the precise character, weight, and mode mixing as a prerequisite of tailored excitations for applications.

Biocompatibility of Polyimides: A Mini-Review.

Polyimides (PIs) represent a benchmark for high-performance polymers on the basis of a remarkable collection of valuable traits and accessible production pathways and therefore have incited serious attention from the ever-demanding medical field. Their characteristics make them suitable for service in hostile environments and purification or sterilization by robust methods, as requested by most biomedical applications. Even if PIs are generally regarded as "biocompatible", proper analysis and understanding of their biocompatibility and safe use in biological systems deeply needed. This mini-review is designed to encompass some of the most robust available research on the biocompatibility of various commercial or noncommercial PIs and to comprehend their potential in the biomedical area. Therefore, it considers (i) the newest concepts in the field, (ii) the chemical, (iii) physical, or (iv) manufacturing elements of PIs that could affect the subsequent biocompatibility, and, last but not least, (v) in vitro and in vivo biocompatibility assessment and (vi) reachable clinical trials involving defined polyimide structures. The main conclusion is that various PIs have the capacity to accommodate in vivo conditions in which they are able to function for a long time and can be judiciously certified as biocompatible.

Ferroelectric Control of Interface Spin Filtering in Multiferroic Tunnel Junctions.

The electronic reconstruction occurring at oxide interfaces may be the source of interesting device concepts for future oxide electronics. Among oxide devices, multiferroic tunnel junctions are being actively investigated as they offer the possibility to modulate the junction current by independently controlling the switching of the magnetization of the electrodes and of the ferroelectric polarization of the barrier. In this Letter, we show that the spin reconstruction at the interfaces of a La_{0.7}Sr_{0.3}MnO_{3}/BaTiO_{3}/La_{0.7}Sr_{0.3}MnO_{3} multiferroic tunnel junction is the origin of a spin filtering functionality that can be turned on and off by reversing the ferroelectric polarization. The ferroelectrically controlled interface spin filter enables a giant electrical modulation of the tunneling magnetoresistance between values of 10% and 1000%, which could inspire device concepts in oxides-based low dissipation spintronics.

Benzobis(imidazolium) salts as templates for the self-assembly of starburst [24]pseudorotaxanes and their corresponding carbene-based classic [22]pseudorotaxanes.

Benzobis(imidazolium) salts ([BBI-H2-R4]2+, R = alkyl, aryl) interact with crown ethers through a combination of hydrogen bonds, ion-dipole, and π-π stacking interactions to form starburst [24]pseudo-rotaxanes. This new recognition motif allows the extension of four side-arms directly from the cavity of the crown ether, thus positioning the wheel component in a straddled orientation onto the axle, while their carbene-based derivatives show the classical shape of regular [22]pseudorotaxanes.

Multiple coordination modes of a new ditopic bis(pyrazolyl)methane-based ligand.

A new ditopic ligand, N-(2,2-bis(pyrazolyl)ethyl)-2,2-bis(pyrazolyl)acetamide ((pz)2CH-C(O)-NH-CH2-CH(pz)2, L4Pz, pz = pyrazolyl ring), comprising two bis(pyrazolyl)methane donor groups linked via an amide bridge, has been prepared from the reaction of HOOCCH(pz)2 and H2NCH2CH(pz)2. The ligand coordinates to various metallic salts (i.e. AgO3SCF3, PdCl2, Re(CO)5Br, and Fe(BF4)2), in either a κ2-µ-κ2 or a κ3-µ-κ2 fashion, depending on the coordination preferences of the metallic center. These compounds were characterized by NMR, UV-Vis and IR spectroscopy, and in solid state by single crystal X-ray diffraction. In the case of silver(i), a mono-dimensional coordination polymer was obtained, while the others were found to be discrete complexes. The synthesis and characterization of a heterobimetallic complex is also described. In solid state, all compounds are associated into supramolecular architectures via hydrogen bonding and pyrazolyl embrace interactions.

Silver(I) and rhenium(I) metal complexes of a 2,2'-bipyridine-functionalized third-generation tris(pyrazolyl)methane ligand.

Heterotopic ligands offer the possibility of preparing polynuclear bimetallic complexes. Recent studies of heteroditopic ligands and their metal complexes have focused on novel supramolecular systems, biological activity, and the development of MRI contrast agents. The heteroditopic ligand Bipy-CH2-O-CH2-C(pz)3 (Bipy-L; Bipy is 2,2'-bipyridine and pz is pyrazolyl) reacts with AgBF4 to produce the coordination polymer catena-poly[[silver(I)-(µ-5-{[tris(pyrazol-1-yl)methoxy]methyl-κ2N,N'}-2,2'-bipyridine-κ2N,N')] diethyl ether hemisolvate], {[Ag(C22H20N8O)]BF4·0.5C4H10O}n, and with Re(CO)5Br to form the discrete compound bromidotricarbonyl(5-{[tris(pyrazol-1-yl)methoxy]methyl}-2,2'-bipyridine-κ2N,N')rhenium(I), [ReBr(C22H20N8O)(CO)3]. The silver(I) compound is a one-dimensional coordination polymer, built up by a κ2 coordination mode of the bipyridine group and a κ2-κ0 coordination mode of the -C(pz)3 donor set. In [ReBr(Bipy-L)(CO)3], the ligand coordinates only via the bipyridine end, leaving the -C(pz)3 donor set free for further coordination interactions.

A cadmium(II) coordination polymer formed from a third generation tetratopic tris(pyrazolyl)methane ligand.

The reaction of a third generation tetratopic tris(pyrazolyl)methane ligand, namely 1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene {1,2,4,5-C6H2[CH2OCH2C(pz)3]4, L4}, and [Cd2(thf)5](BF4)4 (thf is tetrahydrofuran) produces the coordination polymer catena-poly[[[bis[acetonitrilecadmium(II)]-µ4-1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene] tetrakis(tetrafluoroborate)]-diethyl ether-acetonitrile (1/2/2)], {[Cd2(CH3CN)2(C54H54N24O4)](BF4)4·2C4H10O·2CH3CN}n. The CdII center is coordinated in a κ3-fashion by one tris(pyrazolyl)methane group and in a κ2-κ0 fashion by another, while the sixth coordination site on the CdII cation is occupied by an acetonitrile molecule. This bonding mode of the ligand generates an infinite one-dimensional structure built upon 32-atom metallomacrocycles connected by the C6H2 spacer. This compound is isostructural with the silver(I) analogue of this ligand, i.e. {[Ag2(L4)](BF4)2·4CH3CN}n, thus showing the tendency of this system to form metal-based macrocyclic architectures.

Modern drug delivery systems for targeting the posterior segment of the eye.

Some of the most dangerous diseases of the eye are related to the posterior segment. Diseases such as age-related macular degeneration, cytomegalovirus retinitis, diabetic retinopathy, posterior uveitis and retinitis pigmentosa are difficult to treat using classical methods because of the many internal barriers of the eye which affect the drug efficiency. In this review, we will summarize the main research directions in the field of medicamentous treatment of posterior eye disorders belonging to the controlled drug delivery concept. The review is starting with the most important knowledge regarding anatomy and pathology of the posterior segment of the eye and is continuing with the current treatment methods of the eye posterior segment illnesses and drawbacks of these methods, the drugs administration pathways to the posterior segment of the eye. The last three sections present the state of the art regarding the latest discoveries including the commercial products in the modern drug delivery systems; the main classes of materials treated in the present review are implants, hydrogels and nano- microparticulate systems.

ALICE­An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities.

We report on significant developments of a high vacuum reflectometer (diffractometer) and spectrometer for soft x-ray synchrotron experiments which allows conducting a wide range of static and dynamic experiments. Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. The versatility of the instrument was testified by a series of pilot experiments. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. We demonstrate here the capabilities of the system to host a variety of experiments, featuring ALICE as one of the most versatile and demanded instruments at the Helmholtz Center in Berlin-BESSY II synchrotron center in Berlin, Germany.

Laser induced magnetization switching in a TbFeCo ferrimagnetic thin film: discerning the impact of dipolar fields, laser heating and laser helicity by XPEEM.

We investigate laser induced magnetic switching in a ferrimagnetic thin film of Tb22Fe69Co9 by PEEM. Using a small laser beam with a spot size of 3-5 µm in diameter in combination with high resolution magnetic soft X-ray microscopy we are able to discriminate between different effects that govern the microscopic switching process, namely the influence of the laser heating, of the helicity dependent momentum transfer, and of the dipolar coupling. Applying a sequence of femtosecond laser pulses to a previously saturated TbFeCo film leads to the formation of ring shaped magnetic structures in which all three effects can be observed. Laser helicity assisted switching is only observed in a narrow region within the Gaussian profile of the laser spot. Whereas in the center of the laser spot we find clear evidence for thermal demagnetization and in the outermost areas magnetic switching is determined by dipolar coupling with the surrounding film. Our findings demonstrate that by reducing the laser spot size the influence of dipolar coupling on laser induced switching is becoming increasingly important.

Dual-mode-locking mechanism for an akinetic dispersive ring cavity swept source.

A fast dual-mode-locked akinetic optical swept source in the 1550-nm wavelength band is presented that is tested up to a sweep rate of 797 KHz. It comprises a voltage-controlled oscillator-driven wideband semiconductor optical amplifier (SOA) along with a dispersion compensation fiber, in a ring laser configuration. A Faraday rotating mirror is employed in the cavity as a reflective element in order to achieve better polarization control. By driving the SOA at a high-MHz-frequency value multiple of the resonant frequency f(R), equal to the inverse round trip time, a first-mode locking mechanism is imposed. A second locking mechanism consists in sweeping the radio frequency of the locking signal at a rate slightly detuned from f(R). A dynamic linewidth of 0.8 nm is assessed by measuring the decay of interference signal strength versus optical path difference in a Mach-Zehnder interferometer.

MKK3 regulates mitochondrial biogenesis and mitophagy in sepsis-induced lung injury.

Sepsis is a systemic inflammatory response to infection and a major cause of death worldwide. Because specific therapies to treat sepsis are limited, and underlying pathogenesis is unclear, current medical care remains purely supportive. Therefore targeted therapies to treat sepsis need to be developed. Although an important mediator of sepsis is thought to be mitochondrial dysfunction, the underlying molecular mechanism is unclear. Modulation of mitochondrial processes may be an effective therapeutic strategy in sepsis. Here, we investigated the role of the kinase MKK3 in regulation of mitochondrial function in sepsis. Using clinically relevant animal models, we examined mitochondrial function in primary mouse lung endothelial cells exposed to LPS. MKK3 deficiency reduces lethality of sepsis in mice and by lowering levels of lung and mitochondrial injury as well as reactive oxygen species. Furthermore, MKK3 deficiency appeared to simultaneously increase mitochondrial biogenesis and mitophagy through the actions of Sirt1, Pink1, and Parkin. This led to a more robust mitochondrial network, which we propose provides protection against sepsis. We also detected higher MKK3 activation in isolated peripheral blood mononuclear cells from septic patients compared with nonseptic controls. Our findings demonstrate a critical role for mitochondria in the pathogenesis of sepsis that involves a previously unrecognized function of MKK3 in mitochondrial quality control. This mitochondrial pathway may help reveal new diagnostic markers and therapeutic targets against sepsis.

Tris(pyrazolyl)methane and 1,8-naphthalimide-functionalized dialkynylgold(I) anionic complexes.

The reaction of tetrapropylammonium bis(acetylacetonato)gold(I) with alkyne derivatives of the tris(pyrazolyl)methane and 1,8-naphthalimide functional groups yielded two new compounds, both bridged by the linear C[triple-bond]C-Au-C[triple-bond]C spacer, namely tetrapropylammonium bis{3-[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]prop-1-yn-1-yl}aurate(I), (C16H28N)[Au(C14H13N6O)2], and tetrapropylammonium {η(2)-µ-3-[2,4-dioxo-3-azatricyclo[7.3.1.0(5,13)]trideca-1(12),5,7,9(13),10-pentaen-3-yl]prop-1-yn-yl}bis{3-[2,4-dioxo-3-azatricyclo[7.3.1.0(5,13)]trideca-1(12),5,7,9(13),10-pentaen-3-yl]prop-1-yn-1-yl}digold(I) deuterochloroform disolvate, (C16H28N)[Au2(C15H8NO2)3]·2CDCl3. The alkyne-functionalized scorpionate ligand [Au{C[triple-bond]CCH2OCH2C(pz)3}2](-) features two potentially tridentate tris(pyrazolyl)methane donor groups oriented in a `trans' position relative to the C[triple-bond]C-Au-C[triple-bond]C spacer. The naphthalimide-containing compound comprises a σ-bonded NI-CH2-C[triple-bond]C-Au-C[triple-bond]C-CH2-NI unit (NI is the naphthalimide group) π-coordinated to an NI-CH2-C[triple-bond]C-Au neutral fragment. The crystal packing of this compound is supported by π-π stacking interactions of the NI unit, generating a three-dimensional network containing channels accommodating the tetrapropylammonium cations and deuterated chloroform solvent molecules.

Post-synthesis surface-modified silicas as adsorbents for heavy metal ion contaminants Cd(II), Cu(II), Cr(III), and Sr(II) in aqueous solutions.

To analyze the influence of silica surface modification and confined space effects on specific interactions of divalent and trivalent metal cations with surface functionalities, three different high surface area silicas with different pore size distributions were modified with the following organosilanes: 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-(trimethoxysilylpropyl)diethylenetriamine, N-(triethoxysilylpropyl)ethylenediaminetriacetic acid (EDTrA), and 3-(2,4-dinitrophenylamino)propyltriethoxysilane. The silicas were characterized by N(2) adsorption and reflectance FTIR spectroscopy before and after surface modification. N(2) adsorption and pore size distributions showed an increase in the pore width for all EDTrA-modified silicas, opposite to what occurred with the other organosilanes. Adsorption isotherms of Cd(II), Cr(III), Cu(II), and Sr(II) obtained from aqueous solutions were compared and analyzed by silica type, organosilane functional group, and metal adsorbed. Reflectance FTIR spectroscopy was used to probe the acetate functionality in EDTrA as a function of adsorbed metal content. A band shift to higher energy for Cr(III) on the wide pore silica studied indicated that the interaction with the acetate groups can be probed in this manner. In general, the wider pore distribution silica provided larger adsorption maxima, whereas the narrower pore distribution silica provided more favorable ΔG because of stronger binding of the cations. Cr(III) and Cu(II) exhibited larger adsorption maxima compared to Cd(II) and Sr(II), with the grafted organosilanes studied since the first cations have a greater charge/radius ratio than the second ones that provide a greater binding energy.

Fluid management in acute respiratory distress syndrome.

PURPOSE OF REVIEW: Fluid management is one of the most important measures shown to impact acute respiratory distress syndrome (ARDS) outcomes. This review summarizes the current strategies aimed at evaluating and modulating lung fluid balance. RECENT FINDINGS: Multiple recent studies have shown that a conservative fluid management in ARDS patients had beneficial effects on morbidity and mortality. These findings were replicated also in different patient populations assumed to have potential deleterious effects from this approach. So far, only one retrospective study raised the possibility of impaired cognitive function in ARDS patients managed with a conservative fluid strategy. Thermodilution methods and serum biomarkers can be used to monitor lung fluid balance and guide therapy. Recent evidence has indicated significant detrimental effects associated with beta-2 agonists use in ARDS, despite a putative beneficial role in the resolution of alveolar edema seen in preliminary studies. SUMMARY: Dynamic monitoring of lung fluid balance needs to be implemented to guide fluid therapy in ARDS patients. A conservative fluid strategy seems safe and yields overall good clinical outcomes, but its impact on cognitive function needs to be evaluated in further studies. The role of colloids and other pharmacological agents deserves further investigation.