INMdok (Leibniz Institute for New Materials)
Not a member yet
931 research outputs found
Sort by
Raman and NMR spectroscopic and theoretical investigations of the cubic laves-phases REAl2 (RE = Sc, Y, La, Yb, Lu)
Get PDFThe cubic Laves-phase aluminides REAl2 with RE = Sc, Y, La, Yb and Lu were prepared from the elements by arc-melting or using refractory metal ampoules and induction heating. They all crystallize in the cubic crystal system with space group Fd[3 with combining macron]m and adopt the MgCu2 type structure. The title compounds were characterized by powder X-ray diffraction and spectroscopically investigated using Raman and 27Al and in the case of ScAl2 by 45Sc solid-state MAS NMR. In both, the Raman and NMR spectra, the aluminides exhibit only one signal due to the crystal structure. DFT calculations were used to calculate Bader charges illustrating the charge transfer in these compounds along with NMR parameters and densities of states. Finally, the bonding situation was assessed by means of ELF calculations rendering these compounds aluminides with positively charged REδ+ cations embedded in an [Al2]δ− polyanion
Bioactive Constituents of Verbena officinalis Alleviate Inflammation and Enhance Killing Efficiency of Natural Killer Cells
Get PDFNatural killer (NK) cells play key roles in eliminating pathogen-infected cells. Verbena officinalis (V. officinalis) has been used as a medical plant in traditional and modern medicine for its anti-tumor and anti-inflammatory activities, but its effects on immune responses remain largely elusive. This study aimed to investigate the potential of V. officinalis extract (VO extract) to regulate inflammation and NK cell functions. We examined the effects of VO extract on lung injury in a mouse model of influenza virus infection. We also investigated the impact of five bioactive components of VO extract on NK killing functions using primary human NK cells. Our results showed that oral administration of VO extract reduced lung injury, promoted the maturation and activation of NK cells in the lung, and decreased the levels of inflammatory cytokines (IL-6, TNF-α and IL-1β) in the serum. Among five bioactive components of VO extract, Verbenalin significantly enhanced NK killing efficiency in vitro, as determined by real-time killing assays based on plate-reader or high-content live-cell imaging in 3D using primary human NK cells. Further investigation showed that treatment of Verbenalin accelerated the killing process by reducing the contact time of NK cells with their target cells without affecting NK cell proliferation, expression of cytotoxic proteins, or lytic granule degranulation. Together, our findings suggest that VO extract has a satisfactory anti-inflammatory effect against viral infection in vivo, and regulates the activation, maturation, and killing functions of NK cells. Verbenalin from V. officinalis enhances NK killing efficiency, suggesting its potential as a promising therapeutic to fight viral infection
Understanding the charging of supercapacitors by electrochemical quartz crystal microbalance
Get PDFSupercapacitors are highly valued energy storage devices with high power density, fast charging ability, and exceptional cycling stability. A profound understanding of their charging mechanisms is crucial for continuous performance enhancement. Electrochemical quartz crystal microbalance (EQCM), a detection means that provides in situ mass change information during charging–discharging processes at the nanogram level, has received greatly significant attention during the past decade due to its high sensitivity, non-destructiveness and low cost. Since being used to track ionic fluxes in porous carbons in 2009, EQCM has played a pivotal role in understanding the charging mechanisms of supercapacitors. Herein, we review the critical progress of EQCM hitherto, including theory fundamentals and applications in supercapacitors. Finally, we discuss the fundamental effects of ion desolvation and transport on the performance of supercapacitors. The advantages and defects of applying EQCM in supercapacitors are thoroughly examined, and future directions are proposed
Toward MBenes Battery Electrode Materials: Layered Molybdenum Borides for Li-Ion Batteries
Get PDFLithium-ion and sodium-ion batteries (LIBs and SIBs) are crucial in our shift toward sustainable technologies. In this work, the potential of layered boride materials (MoAlB and Mo2AlB2) as novel, high-performance electrode materials for LIBs and SIBs, is explored. It is discovered that Mo2AlB2 shows a higher specific capacity than MoAlB when used as an electrode material for LIBs, with a specific capacity of 593 mAh g−1 achieved after 500 cycles at 200 mA g−1. It is also found that surface redox reactions are responsible for Li storage in Mo2AlB2, instead of intercalation or conversion. Moreover, the sodium hydroxide treatment of MoAlB leads to a porous morphology and higher specific capacities exceeding that of pristine MoAlB. When tested in SIBs, Mo2AlB2 exhibits a specific capacity of 150 mAh g−1 at 20 mA g−1. These findings suggest that layered borides have potential as electrode materials for both LIBs and SIBs, and highlight the importance of surface redox reactions in Li storage mechanisms
The double-well Bose Hubbard model with nearest-neighbor and cavitymediated long-range interactions
Get PDFWe consider a one-dimensional Bose-Hubbard model (BHM) with on-site double-well potentials and study the effect of nearest-neighbor repulsion and cavity-mediated long-range interactions by calculating the ground-state phase diagrams with quantum Monte-Carlo simulations. We show that when the intra-well repulsion is as strong as the on-site repulsion a dimerized Mott insulator phase appears at the tip of the dimerized Density Wave phase for a density of one particle per double well. Furthermore, we find a dimerized Haldane insulator phase in the double-well BHM with nearest-neighbor interaction, which is identical to a dimerized BHM with repulsive interactions up to the third neighbor
A printed luminescent flier inspired by plant seeds for eco-friendly physical sensing
Get PDFContinuous and distributed monitoring of environmental parameters may pave the way for developing sustainable strategies to tackle climate challenges. State-of-the-art technologies, made with electronic systems, are often costly, heavy, and generate e-waste. Here, we propose a new generation of self-deployable, biocompatible, and luminescent artificial flying seeds for wireless, optical, and eco-friendly monitoring of environmental parameters (i.e., temperature). Inspired by natural Acer campestre plant seeds, we developed three-dimensional functional printed luminescent seed–like fliers, selecting polylactic acid as a biocompatible matrix and temperature as a physical parameter to be monitored. The artificial seeds mimic the aerodynamic and wind dispersal performance of the natural ones. The sensing properties are given by the integration of fluorescent lanthanide–doped particles, whose photoluminescence properties depend on temperature. The luminescent artificial flying seeds can be optically read from a distance using eye-safe near-infrared wavelengths, thus acting as a deployable sensor for distributed monitoring of topsoil environmental temperatures
Analytical and numerical results for the elasticity and adhesion of elastic films with arbitrary Poisson’s ratio and confinement
Get PDFWe present an approximate, analytical treatment for the linearly elastic response of a film with arbitrary Poisson's ratio ?, which is indented by a flat cylindrical punch while resting on a rigid foundation. Our approach is based on a simple scaling argument allowing the vast changes of the elastomer?s effective modulus E? with the ratio of film height h and indenter radius a to be described with a compact, analytical expression. This yields exact asymptotics for large and small reduced film heights h/a, whereby it also reproduces the observation that E?(h/a) has a pronounced minimum for ?>0.49 at h/a≈1.6. Using Green?s function molecular dynamics (GFMD), we demonstrate that the predictions for E?(h/a) are reasonably correct and generate accurate reference data for effective modulus and pull-off force. GFMD also reveals that the nature of surface instabilities occurring during stable crack growth as well as the crack initiation itself depend sensitively on the way how continuum mechanics is terminated at small scales, that is, on parameters beyond the two dimensionless numbers h/a and ? defining the continuum problem
Cononsolvency of the responsive polymer poly(N-isopropylacrylamide) in water/methanol mixtures: a dynamic light scattering study of the effect of pressure on the collective dynamics
Get PDFThe collective dynamics of 25 wt% poly(N-isopropylacrylamide) (PNIPAM) solutions in water or an 80:20 v/v water/methanol mixture are investigated in the one-phase region in dependence on pressure and temperature using dynamic light scattering. Throughout, two dynamic modes are observed, the fast one corresponding to the relaxation of the chain segments within the polymer blobs and the slow one to the relaxation of the blobs. A pressure scan in the one-phase region on an aqueous solution at 34.0 °C, i.e., slightly below the maximum of the coexistence line, reveals that the dynamic correlation length of the fast mode increases when the left and the right branch of the coexistence line are approached. Thus, the chains are rather swollen far away from the coexistence line, but contracted near the phase transition. Temperature scans of solutions in neat H2O or in H2O/CD3OD at 0.1, 130, and 200 MPa reveal that the dynamic correlation length of the fast mode shows critical behavior. However, the critical exponents are significantly larger than the value predicted by mean-field theory for the static correlation length, ν = 0.5, and the exponent is significantly larger for the solution in the H2O/CD3OD mixture than in neat H2O
Water as a "glue" : Elasticity-enhanced wet attachment of biomimetic microcup structures
Get PDFOctopus, clingfish, and larva use soft cups to attach to surfaces under water. Recently, various bioinspired cups have been engineered. However, the mechanisms of their attachment and detachment remain elusive. Using a novel microcup, fabricated by two-photon lithography, coupled with in situ pressure sensor and observation cameras, we reveal the detailed nature of its attachment/detachment under water. It involves elasticity-enhanced hydrodynamics generating “self-sealing” and high suction at the cup-substrate interface, converting water into “glue.” Detachment is mediated by seal breaking. Three distinct mechanisms of breaking are identified, including elastic buckling of the cup rim. A mathematical model describes the interplay between the attachment/detachment process, geometry, elasto-hydrodynamics, and cup retraction speed. If the speed is too slow, then the octopus cannot attach; if the tide is too gentle for the larva, then water cannot serve as a glue. The concept of “water glue” can innovate underwater transport and manufacturing strategies. Under-water soft cups form strong attachment with solid surfaces upon retraction by generating large transient suction