24378 research outputs found
Sort by
Aluminum Foam Sandwiches A Lighter Future for Car Bodies
Get PDFAn aluminum foam sandwich AFS is a lightweight material that has great potential for applications in the automotive industry. In this work, the production routes of metal foams and metal foam sandwiches are reviewed. We compare the mechanical properties of AFS, such as high mass specific bending stiffness, compressive strength and crash absorption capacity, with other materials such as steel, aluminum alloys, or fiber composites and place them in a cost weight comparison. Additional functional properties such as high electromagnetic damping, increased sound absorption, and improved fire resistance underline its multi functional character. Furthermore, possible joining techniques and parts of AFS for modern car bodies, such as the battery box, are discusse
Materials Acceleration Platforms MAPs Accelerating Materials Research and Development to Meet Urgent Societal Challenges
Get PDFClimate Change andMaterials Criticality challenges are driving urgent responses from global governments. These global responses drive policy to achieve sustainable, resilient, clean solutions with Advanced Materials AdMats for industrial supply chains and economic prosperity. The research landscape comprising industry, academe, and government identified a critical path to accelerate the Green Transition far beyond slow conventional research through Digital Technologies that harness Artificial Intelligence, Smart Automation and High Performance Computing through Materials Acceleration Platforms, MAPs. In this perspective, following the short paper, a broad overview about the challenges addressed, existing projects and building blocks of MAPs will be provided while concluding with a review of the remaining gaps and measures to overcome the
Thirty Years of Hide and Seek Capturing Abundant but Elusive MIII C 3v 8 C82 Isomer, and the Study of Magnetic Anisotropy Induced in Dy3 Ion by the Fullerene Ligand
No full textOur knowledge about endohedral metallofullerenes EMFs is restricted to the structures with sufficient kinetic stability to be extracted from the arc discharge soot and processed by chromatographic and structural techniques. For the most abundant rare earth monometallofullerene MIII C82, experimental studies repeatedly demonstrated C2v 9 and Cs 6 carbon cage isomers, while computations predicted equal stability of the missing C3v 8 isomer. Here we report that this isomer is indeed formed but has not been recovered from soot using standard protocols. Using a combination of redox extraction and subsequent benzylation and trifluoromethylation with single crystal XRD analysis of CF3 adduct, we prove that Dy C3v 8 C82 is one of the most abundantly produced metallofullerenes, which was not identified in earlier studies because of the low kinetic stability. Further, using the Dy C3v 8 C82 CF3 and Dy C3v 8 C82 CH2Ph monoadducts for the case study, we analyzed the role of metal fullerene bonding on the single ion magnetic anisotropy of Dy in EMFs. The multitechnique approach, combining ab initio calculations, EPR spectroscopy, and SQUID magnetometry, demonstrated that coordination of the Dy ion to the fullerene cage induces moderate, nonaxial, and very fluid magnetic anisotropy, which strongly varies with small alterations in the Dy fullerene coordination geometry. As a result, Dy C3v 8 C82 CH2Ph is a weak field induced single molecule magnet SMM , whose signatures of magnetic relaxation are detectable only below 3 K. Our results demonstrate that metal cage interactions should have a detrimental effect on the SMM performance of EMFs. At the same time, the strong variability of the magnetic anisotropy with metal position suggests tunability and offers strategies for future progres
Stability and Reactivity of Aromatic Radical Anions in Solution with Relevance to Birch Reduction
Get PDFWe investigate the electronic structure of aromatic radical anions in the solution phase employing a combination of liquid jet LJ photoelectron PE spectroscopy measurements and electronic structure calculations. By using recently developed protocols, we accurately determine the vertical ionization energies of valence electrons of both the solvent and the solute molecules. In particular, we first characterize the pure solvent of tetrahydrofuran THF by LJ PE measurements in conjunction with ab initio molecular dynamics simulations and G0W0 calculations. Next, we determine the electronic structure of neutral naphthalene Np and benzophenone Bp as well as their radical anion counterparts Np and Bp in THF. Wherever feasible, we performed orbital assignments of the measured PE features of the aromatic radical anions, with comparisons to UV vis absorption spectra of the corresponding neutral molecules being instrumental in rationalizing the assignments. Analysis of the electronic structure differences between the neutral species and their anionic counterparts provides understanding of the primarily electrostatic stabilization of the radical anions in solution. Finally, we obtain a very good agreement of the reduction potentials extracted from the present LJ PES measurements of Np and Bp in THF with previous electrochemical data from cyclic voltammetry measurements. In this context, we discuss how the choice of solvent holds significant implications for optimizing conditions for the Birch reduction process, wherein aromatic radical anions play crucial roles as reactive intermediate
Elucidating the Unconventional Binding Mode of a DNA Encoded Library Hit Provides a Blueprint for Sirtuin 6 Inhibitor Development
No full textSirtuin 6 Sirt6 , an NAD dependent deacylase, has emerged as a promising target for aging related diseases and cancer. Advancing the medicinal chemistry of Sirt6 modulators is crucial for the development of chemical probes aimed at unraveling the intricate biological functions of Sirt6 and unlocking its therapeutic potential. A proprietary DNA encoded library yielded Sirt6 inhibitor 2 Pr, displaying remarkable inhibitory activity and isoform selectivity, and featuring a chemical structure distinct from reported Sirt6 modulators. In this study, we explore the inhibitory mechanism of 2 Pr, evaluating the impact of chemical modifications and presenting a crystal structure of the Sirt6 ADP ribose 2 Pr complex. Notably, co crystal structure analysis reveals an unexpected and unprecedented binding mode of Sirt6, with 2 Pr spanning the acyl channel of the enzyme, extending into the acetyl lysine binding pocket, and reaching toward the C site. This unique binding mode guides potential avenues for developing potent and selective Sirt6 inhibitor
Ir C multilayers for the NewAthena X ray mirrors
No full textDevelopment and qualification of X ray reflective mirror coatings for the NewAthena mission is progressing with a focus on enabling scientific capabilities of the telescope, given the updated requirements of the redefined mission. In this work, we consider both design and development of Ir C multilayer coatings optimised to ensure the required performance across the spectral range, facilitating the mission science objectives. We present demonstration of manufacturing capability for the optimised Ir C multilayer coatings, and compatibility with the Silicon Pore Optics SPO technology. Characterisation of X ray mirror coatings is performed using X ray reflectometry with a focus on mirror design qualification and long term stabilit
Determination of omega end functionalities in tailored poly 2 alkyl 2 oxazoline s by liquid chromatography and mass spectrometry
Get PDFThe in depth analytical characterization of polymers, in particular regarding intended biomedical applications, is becoming increasingly important to elucidate their structure property relationships. Specifically, end group analysis of e.g. polymers featuring a stealth effect towards the immune system is of particular importance because of their use in coupling reactions to bioactive compounds. Herein, we established a liquid chromatography LC protocol to analyse bicyclo[6.1.0]nonyne functionalized poly 2 alkyl 2 oxazoline s POx s as promising functional polymers that can be applied in strain promoted click reactions. This work involved the synthesis of poly 2 methyl 2 oxazoline PMeOx and poly 2 ethyl 2 oxazoline PEtOx by living cationic ring opening polymerization CROP with different molar masses ranging from 2 up to 17.5 kDa and, to our knowledge, the first liquid chromatographic analysis of PMeOx. The developed analytical protocol enables the quantitative determination of post polymerization reaction sequences with respect to the conversion of the omega end groups. All synthesized polymers were straightforwardly analysed on a C18 derivatized silica monolithic column under reversed phase chromatographic conditions with a binary mobile phase gradient comprising a mixture of acetonitrile and water. Subsequent mass spectrometry of collected elution fractions enabled the confirmation of the desired omega end group functionalities and the identification of synthetic by product
Thermoresponsive scaffolds fabricated using covalent organic frameworks for the selective removal of water contaminants
Get PDFWell defined channels and inert and hydrolyzable structures of covalent organic frameworks make them excellent templates for the construction of polymeric scaffolds with a defined topology and properties. In this work, we report on the synthesis of thermoresponsive PNIPAM scaffolds templated by boronate ester COFs. Polymerization of N isopropylacrylamide by azobisisobutyronitrile, encapsulated in COF channels, followed by the removal of the host framework resulted in PNIPAM scaffolds. The obtained scaffolds displayed different sizes and morphologies depending on whether polymerization was performed in the presence or absence of a crosslinking agent. In the presence of a crosslinking agent, porous PNIPAM scaffolds retained the size and the morphology of the COF, while without a crosslinking agent spindle like microstructures were obtained. Constructed scaffolds were highly thermoresponsive and their morphology changed dramatically upon small temperature variations. This property was used for the controlled and selective removal of dye impurities from water. UV visible absorption spectra showed that the obtained porous PNIPAM scaffold could effectively adsorb cationic and anionic dyes such as methylene blue MB , rhodamine B RhB , and fluorescein FL from wastewater. FL and RhB were effectively adsorbed by this scaffold, but a lower affinity was observed for MB. The absorption capacity of the PNIPAM1 sponge for FL, RhB and MB was 231 mg g 1, 245 mg g 1 and 36 mg g 1, respectively. Taking advantage of the high adsorption capacity and recyclability of the absorbant, it can be used for wastewater treatmen
Recent Advances and Prospects in High Performance Bio Based Phthalonitrile Resins
Get PDFPhthalontirile resins are renowned as the most heat resistant polymeric materials and exhibit exceptional performance under harsh conditions. Consequently, phthalonitrile thermosets offer the potential to substitute metals in hot parts, thereby broadening the operational limits of plastic materials in high tech applications. Given their unique combination of properties, phthalonitriles have garnered significant demand across sectors such as aerospace, automotive, electronics, and renewable energy. With industrial production and application of phthalonitriles recently initiated in several countries, questions regarding the sustainability of these materials have naturally arisen. Thermosetting materials, owing to their highly cross linked architecture, cannot be recycled, necessitating the adoption of synthetic methods utilizing bio feedstock raw materials and green protocols to mitigate their environmental impact. The present prospective review summarizes and analyzes the current state of the art in bio based phthalonitrile resins and discusses potential directions for research and development of new application areas, with a focus on the challenge of maintaining high performance levels during the transition to bio based raw material
Cyanide Linkage Isomerization Induced by Cobalt Oxidation State Changes at a Co Fe Prussian Blue Analogue ZnO Interface
Get PDFUnderstanding the interfacial composition in heterostructures is crucial for tailoring heterogenous electrochemical and photoelectrochemical processes. This work aims to elucidate the structure of a series of Co Fe Prussian blue analogue modified ZnO PBA ZnO electrodes with interface sensitive vibrational sum frequency generation VSFG spectroscopy. Our measurements revealed, for the first time, a cyanide linkage isomerism at the PBA ZnO interface, when the composite is fabricated at elevated temperatures. In situ VSFG spectro electrochemistry measurements correlate the CoII gt; CoIII oxidation with the flip of the bridging CN ligand from Co NC Fe coordination mode to a Co CN Fe one. Photoluminescence measurements and X ray photoelectron spectroscopy reveal that this unprecedented linkage isomerism originates from surface defects, which act as oxidation sites for the PBA. The presence of such surface defects is correlated with the fabrication temperature for PBA ZnO. Thus, this contribution identifies the interplay between the surface states of the ZnO substrates and the chemical composition of PBA at the ZnO surface, suggesting an easily accessible approach to control the chemical composition of the interfac