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Self Healing Behavior of Metallopolymers in Complex3D Structures Obtained by DLP Based 3D Printing
Get PDFThis current study focusses on the investigation of the self healing abilities of metallopolymers containing different kinds of metal complexes, which were processed by direct digital light processing DLP based three dimensional 3D printing. For this purpose, 2 phenoxyethyl acrylate is mixed with ligand containing monomers either based on triphenylmethyl trt histidine or terpyridine, respectively. Either zinc II or nickel II salts are successfully applied for a complexation of the ligand monomers in solution and, subsequently, photopolymerization is performed. The thermo mechanical properties of the obtained metallopolymers were characterized by differential scanning calorimetry DSC , thermogravimetric analysis TGA as well as dynamic mechanical thermal analysis DMTA . Multiple damages with defined forces ranging from 20 to 1500 mN were introduced into the 3D structures and successfully healed within 24 h at 70 degrees C or 120 degrees C, respectively without losing the structural integrity of the overall 3D structures. Herein, excellent healing efficiencies up to 97 were determined. Consequently, these hollow structures not only feature very good self healing abilities but also excellent retention of the 3D structure at and above the healing temperatur
Spectro Microscopy of Individual Pt Rh Core Shell Nanoparticles During Competing Oxidation and Alloying
No full textThe surface chemical composition of supported single Pt Rh core shell nanoparticles was studied to understand the Rh behavior in oxidizing and reducing gas environments using spectro microscopy with high spatial resolution. We combined in situ X ray photoemission electron microscopy with ex situ scanning electron , atomic force , and scanning Auger microscopy to distinguish Rh oxidation reduction, dewetting sintering, and alloying segregation during the course of the experiment. A more than 20 higher Rh 3d5 2 oxide to metal photoemission intensity ratio for the Rh layer on top of the Pt core was found as compared to the bare strontium titanate STO oxide catalyst support in close vicinity, where Rh RhOx nanoparticles are forming. At elevated temperatures, Rh diffuses into the Pt particle, and this alloying at the Pt metal surface competes with Rh oxidation, whereas the Rh RhOx nanoparticles on the STO support are observed to sinter under identical oxidizing and temperature environments. A nanoparticle facet dependent analysis of selected Pt core nanoparticles suggests that Rh oxidation is most advanced on a small nanoparticle with a low coordination top facet that we indexed by electron backscatter diffraction, demonstrating the strength of our correlative approac
Design, development and evaluation of a tritium labeled radiotracer for ecto 5 nucleotidase CD73 A versatile research tool and diagnostic agent for personalized medicine
No full textEcto 5 nucleotidase CD73 is the main enzyme that catalyzes the hydrolysis of extracellular AMP to produce anti inflammatory, immunosuppressive adenosine. Many tumor cells over express ectonucleotidases accumulating adenosine in the tumor microenvironment, which promotes tumor growth, metastasis, angiogenesis, and immune escape. CD73 is upregulated in inflammation, and possesses potential as a biomarker and as a novel drug target for inflammatory diseases and cancer immunotherapy. New, metabolically stable N6 disubstituted adenosine 5 diphosphate analogs were synthesized providing a basis for the design and preparation of the CD73 selective radioligand [3H]PSB 17230 by catalytic hydrogenation of a propargyl substituted precursor. It showed high, pico to low nanomolar affinity for human, rat and mouse CD73, slow dissociation kinetics, negligible non specific binding, and high selectivity, as confirmed by studies on an inactive CD73 mutant and CD73 knockout cells. A high resolution co crystal structure 2.35 amp; 8239; of PSB 17230 with human CD73 elucidated its binding interactions. Radioligand binding was employed to characterize competitive CD73 inhibitors and to study expression levels of the enzyme in tissues and tumor cell lines of different species. Moreover, [3H]PSB 17230 was employed in autoradiography studies to determine CD73 expression in healthy and diseased mouse and human tissues. Significant upregulation of CD73 was observed in a mouse asthma model and in kidney cancer biopsies as compared to healthy controls. [3H]PSB 17230 represents a high affinity tracer which is anticipated to find broad application in drug screening, preclinical studies, and for diagnostic purposes in inflammation and cancer, enabling drug monitoring and targeted therapie
Unveiling the Influence of Formation Voltage on Li Rich Layered Oxide Cathode
Get PDFLithium rich layered oxide LRLO cathodes are recognized for their high energy densities, primarily driven by oxygen related anionic redox activities, yet substantial activation of this process simultaneously induces structural instability. The typical voltage range in academic studies spans 2.0 4.8 V. Although 2.5 4.5 V are generally considered in industrial applications for enhanced capacity retention and electrolyte compatibility, this moderate voltage window leads to reduced capacity. To address energy density limitations, several top battery suppliers propose to separately increase the formation voltage during the initial cycle to enhance capacity, while other companies e.g., Contemporary Amperex Technology Co., Ltd., CATL claim that this high voltage formation protocol would exacerbate cycling capacity fading. Herein, we systemically demonstrate that high voltage formation promotes substantial Li extraction from the transition metal TM layers, creating vacancies in TM layer that drive in plane TM migration. This migration triggers a transformation in the OM6 M, cation configuration from O4 OLixTM2 to O5 OLiyTM1 . Such evolution simultaneously enhances both anionic and cationic redox activity, collectively boosting capacity. Nonetheless, the induced in plane TM migration would further aggravate out of plane TM migration, leading to progressive structural degradation, which has been elucidated as the main reason for cycling capacity fadin
TRMC as Technique to Evaluate the Radiation Hardness of Perovskite Film Passivation
No full textThe influence of high energy proton irradiation on the charge carrier kinetics in triple cation, triple halide semiconducting perovskite films with applications in medical instrumentation and space photovoltaics has been investigated with the contactless Time Resolved Microwave Conductivity Measurement technique. In the first experiment, the high sensitivity of the measurement setup for the characterization of the silicon solar cell degradation under the same optical excitation conditions has been demonstrated. Regarding the excess charge carrier kinetics after pulsed excitation in perovskite films, it is found that the TRMC transients are not following a single exponential decay. In contrast to the results on crystalline silicon only minor changes of the charge carrier decay are observed in these perovskite films after proton irradiation. It has also been shown, that the technique can be used to check for the efficient surface passivation of the perovskite films with PEAI layers. The stability of this passivation under irradiation has been investigated and a more pronounced change of the decay time is found for the passivated films as compared to the non passivated film. The results of these TRMC measurement have been compared to the properties of solar cells, using the same substrates and thin films layers as absorption layers. A good correlation between the transient measurements with the external quantum efficiency spectra, obtained from the solar cell characterization has been foun
Ni Co O anodes for the alkaline oxygen evolution reaction Multistage electrode optimization and plasma assisted activity enhancement enabled by a coherent workflow
No full textImproving the performance of oxygen evolution reaction OER catalysts through proper catalyst design and processing represents a critical step toward enhancing the efficiency of water electrolysis. While many studies focus on structure activity relationships and mechanistic insights confined to a particular stage during the anode fabrication, an integrated approach covering all process steps is crucial to optimize performance relevant properties such as composition, morphology, and electrode architecture. In this study, we demonstrate a comprehensive approach for developing Ni Co O anodes as a model system through the entire process chain. Starting from the initial powder characterization through operando to post catalysis analyses, we first underpin the critical impact of catalyst ink optimization through solvent matrix screening, enabling high quality electrode layers via ultrasonic spray coating on Ni plates. This enables us to uncover the effects of post nitrogen plasma treatment integrated into our coherent workflow yielding binder free Ni Co O anode surfaces with enhanced redox reversibility, Fe uptake, porosity, and wettability. These improvements reduce the OER overpotential by 43 mV at 100 mA cm2 compared to untreated counterparts. The durable performance of these electrodes is further demonstrated in a single cell configuration. Our holistic approach from catalyst powder to post mortem analysis highlights the benefits of a coherent anode development strategy employing plasma post processing which is broadly applicable and easily transferable to other benchmark electrocatalyst
Strain Relief and Domain Architecture in Epitaxial NiO Films on La2 3Sr1 3MnO3 SrTiO3 for Spin Transport Engineering
No full textThis study reports on the epitaxial growth and structural characterization of ultrathin NiO films deposited by magnetron sputtering on La2 3Sr1 3MnO3 LSMO films grown on SrTiO3 STO substrates with 001 and 111 orientations. X ray diffraction and atomic force microscopy show that all NiO layers are single phase, face centered pseudo cubic, atomically smooth, root main square RMS surface roughness lt;0.15 nm, and form abrupt interfaces with LSMO. High resolution reciprocal space maps reveal that the films are largely relaxed, but exhibit a slight compressive distortion, yielding unit cell volumes larger than bulk NiO. Despite a nominal amp; 8776;7 lattice mismatch, aberration corrected scanning transmission electron microscopy uncovers an array of misfit dislocations at the NiO LSMO interface that help to accommodate strain allowing epitaxial growth of NiO layers. On 001 oriented samples, the four antiferromagnetic T domains are oblique to the sample plane, while on the 111 case, one lies in plane. This in plane domain shows greater spacing between ferromagnetic 111 planes due to unit cell distortion. This structural domain splitting can influence magnetic order and spin transmission efficiency, highlighting crystallographic orientation as a key factor in designing high performance spintronic device
Resonant x ray scattering study of charge density wave correlations in YBa2Cu3O6 x under uniaxial stress
Get PDFWe report a comprehensive study of the uniaxial stress response of charge density wave CDW correlations in detwinned single crystals of the high temperature superconductor YBa2Cu3O6 x YBCO6 x with 0.40 x 0.93 hole doping levels 0.072 p 0.168 by means of Cu L3 edge resonant energy integrated x ray scattering REXS . We show that the influence of uniaxial stress is strongly doping dependent the quasi two dimensional CDW is enhanced by in plane uniaxial stress in a wide hole doping range 0.45 x 0.80 , but only barely affected in the most underdoped and optimally doped samples x 0.40 and 0.93 , where the CDW correlation length is minimal. A stress induced three dimensionally long range ordered 3D CDW was observed only in YBCO6.50 and YBCO6.67. The temperature dependence of the 3D CDW clearly indicates a strong competition with superconductivity. Based on the systematic strain , doping , and temperature dependent REXS measurements reported here, we discuss the relationship between charge order and superconductivity in YBCO6 x and other cuprate
N Heterocyclic Carbenes on a III V Semiconductor From Chain Formation to Ordered Monolayers
Get PDFN Heterocyclic carbenes NHCs are established ligands for various surfaces, known for their strong binding, ability to form self assembled monolayers, and modular structure. However, semiconductor surface modification with NHCs is still in its infancy despite its technological importance. Although previous studies focused on silicon, III V compound semiconductors offer direct bandgaps and high electron mobilities, making them ideal for opto electronics. This study examines the adsorption of different NHCs on GaAs, a prototypical III V material, using scanning tunneling microscopy, density functional theory, X ray photoelectron spectroscopy, low energy electron diffraction, and reflectance anisotropy spectroscopy. Covalent binding to the surface and the formation of well ordered NHC monolayers are observed, along with exceptionally large work function reductions. The unique structural features of NHCs enable precise control over film structure, ordering, and electronic propertie
Industrialization of perovskite solar cell fabrication strategies to achieve high throughput vapor deposition processes
Get PDFVapor phase deposition processes hold great potential for industrializing the deposition of perovskite based absorbers, offering a pathway to commercialization. Specifically, the scalability, ability to produce conformal coatings, and established use in industrial processing of optoelectronic devices lead to the assumption that thermal sublimation is inherently suitable for commercial scale perovskite solar cell production. However, ensuring economic viability requires a detailed assessment of achievable production throughputs, a key factor in achieving cost effective large scale manufacturing. This work bridges the gap between research focus and industry needs by introducing and analyzing three strategies to increase production throughput in an industrial context 1 we investigate the thermal stability of key perovskite precursor materials to provide guidelines for safe operation by mitigating decomposition risks. 2 We critically evaluate the industrial feasibility of common deposition modes, including co deposition and sequential deposition, as scaling from laboratory to industrial production introduces new challenges in terms of material utilization and compositional material homogeneity. In addition, we analyze the static deposition rate profiles of key perovskite precursor materials and use this data to conceptualize a linear sublimation source. 3 A simulation based approach allows an estimation of the horizontal scale out required to achieve a production throughput of 1000 M10 size wafers per hour, which is considered the minimum threshold for pilot scale production. This analysis explores strategies to achieve a fabrication throughput that is three orders of magnitude higher than the current academic discussion of accelerated vapor phase deposition based on laboratory scale equipment. The sublimation of the organic precursor material is identified as a critical bottleneck and alternative deposition methods for achieving high production throughput are discussed. By addressing these key technical and economic challenges, our study offers practical insights for the transition of sublimation based perovskite deposition from laboratory research to industrial scale manufacturin