Publications by authors named "Grams C"

Article Synopsis
  • Protein structure is crucial for understanding protein function and characterization, with new tools from DeepMind and the Baker lab enabling prediction of the entire human proteome's 3D structures.
  • The Sequence Coverage Visualizer (SCV) is introduced to assist researchers in visualizing protein sequence coverage and integrating structural insights into proteomics experiments.
  • SCV enhances the utility of proteomics data by allowing for the visualization of post-translational modifications and comparisons of different protein structures, thereby aiding in the accuracy of protein structure predictions.
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The extracellular matrix (ECM) is a complex assembly of proteins that constitutes the scaffold organizing cells, tissues, and organs. Over the past decade, mass-spectrometry-based proteomics has become the method of choice to profile the composition of the ECM, or the matrisome, of tissues. To assist non-specialists with the reuse of ECM proteomic datasets, we released MatrisomeDB (https://matrisomedb.

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Article Synopsis
  • Understanding electric dipole switching in multiferroic materials, particularly in LiNbO-type polar magnets, requires examining atomic-scale structural changes, which remains poorly defined in high-pressure synthesized samples.
  • The discovery of Zn-ion splitting in the ZnFeNbO compound, validated through various diffraction techniques, highlights the presence of a paraelectric-like phase within its lattice and prompts a reevaluation of A-site atomic splitting in other similar compounds.
  • The study concludes that A-site splitting is common in LiNbO-type structures with mixed B-site or anionic configurations, with the extent of displacement being influenced by magnetic interactions and bonding dynamics between cations.
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Article Synopsis
  • Designing exotic perovskites has been difficult due to inadequate geometric descriptors and costly high-pressure synthesis processes, which complicate the understanding of their properties.
  • A new data-mining approach is proposed to streamline the discovery of exotic perovskites, focusing on the 'O family, including the polar magnet CoTeO.
  • CoTeO shows promising characteristics, such as magnetic transitions and unique spin structures, achieved at high pressure, suggesting the method could speed up the discovery of new materials across different families.
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The corundum-related oxides MnScNbO and MnScTaO were synthesized at high pressure and high temperature (6 GPa and 1475 K). Analysis of the synchrotron powder X-ray diffraction shows that MnScNbO and MnScTaO crystallize in NiTeO-type noncentrosymmetric crystal structures with space group 3. The asymmetric crystal structure was confirmed by second harmonic generation measurement.

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LiCuVO is a model system of a 1D spin-1/2 chain that enters a planar spin-spiral ground state below its Néel temperature of 2.4 K due to competing nearest and next nearest neighbor interactions. The spin-spiral state is multiferroic with an electric polarization along the a axis which has been proposed to be caused purely by the spin supercurrent mechanism.

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LiGeTeO prepared at ambient pressure adopts the corundum derivative ordered ilmenite structure (rhombohedral R3). When heated at 1073 K and 3-5 GPa, the as-made LiGeTeO can convert into a LiSbO-derived LiTiTeO-type phase (orthorhombic Pnn2), which is the third LiSbO-derived double ABB'O phase in addition to LiTiTeO and LiSnTeO. This Pnn2 LiGeTeO phase spontaneously reverts to the R3 phase if annealed up to 1023 K at ambient pressure.

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Double corundum-related polar magnets are promising materials for multiferroic and magnetoelectric applications in spintronics. However, their design and synthesis is a challenge, and magnetoelectric coupling has only been observed in NiTeO among the known double corundum compounds to date. Here we address the high-pressure synthesis of a new polar and antiferromagnetic corundum derivative MnMnWO, which adopts the NiTeO-type structure with low temperature first-order field-induced metamagnetic phase transitions (T  = 58 K) and high spontaneous polarization (~ 63.

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As wind and solar power provide a growing share of Europe's electricity1, understanding and accommodating their variability on multiple timescales remains a critical problem. On weekly timescales, variability is related to long-lasting weather conditions, called weather regimes2-5, which can cause lulls with a loss of wind power across neighbouring countries6. Here we show that weather regimes provide a meteorological explanation for multi-day fluctuations in Europe's wind power and can help guide new deployment pathways which minimise this variability.

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Mn(2+)2 Fe(2+)W(6+)O6 , a new polar magnetic phase, adopts the corundum-derived Ni3TeO6 -type structure with large spontaneous polarization (PS) of 67.8 μC cm(-2), complex antiferromagnetic order below ≈75 K, and field-induced first-order transition to a ferrimagnetic phase below ≈30 K. First-principles calculations predict a ferrimagnetic (udu) ground state, optimal switching path along the c-axis, and transition to a lower energy udu-udd magnetic double cell.

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By using broadband dielectric spectroscopy in the radio frequency and microwave range, we studied the magnetoelectric dynamics in the multiferroic chiral antiferromagnet MnWO_{4}. Above the multiferroic phase transition at T_{N2}≈12.6  K we observe a critical slowing of the corresponding magnetoelectric fluctuations resembling the soft-mode behavior in canonical ferroelectrics.

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Competing interactions in the so-called spin-ice compounds stabilize a frustrated ground state with finite zero-point entropy and, interestingly, emergent magnetic monopole excitations. The properties of these monopoles are at the focus of recent research with particular emphasis on their quantum dynamics. It is predicted that each monopole also possesses an electric dipole moment, which allows to investigate their dynamics via the dielectric function ε(ν).

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Above-room-temperature polar magnets are of interest due to their practical applications in spintronics. Here we present a strategy to design high-temperature polar magnetic oxides in the corundum-derived A2BB'O6 family, exemplified by the non-centrosymmetric (R3) Ni3TeO6-type Mn(2+)2Fe(3+)Mo(5+)O6, which shows strong ferrimagnetic ordering with TC = 337 K and demonstrates structural polarization without any ions with (n-1)d(10)ns(0), d(0), or stereoactive lone-pair electrons. Density functional theory calculations confirm the experimental results and suggest that the energy of the magnetically ordered structure, based on the Ni3TeO6 prototype, is significantly lower than that of any related structure, and accounts for the spontaneous polarization (68 μC cm(-2)) and non-centrosymmetry confirmed directly by second harmonic generation.

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Polar oxides are technically of great interest but difficult to prepare. Our recent discoveries predicted that polar oxides can be synthesized in the corundum-derivative A2BB'O6 family with unusually small cations at the A-site and a d(0) electron configuration ion at B'-site. When magnetic transition-metal ions are incorporated more interesting polar magnetic oxides can form.

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We have expanded the double perovskite family of materials with the unusual combination of layered order in the A sublattice and rock salt order over the B sublattice to compounds NaLaFeWO6 and NaNdFeWO6. The materials have been synthesized and studied by powder X-ray diffraction, neutron diffraction, electron diffraction, magnetic measurements, X-ray absorption spectroscopy, dielectric measurements, and second harmonic generation. At room temperature, the crystal structures of both compounds can be defined in the noncentrosymmetric monoclinic P2(1) space group resulting from the combination of ordering both in the A and B sublattices, the distortion of the cell due to tilting of the octahedra, and the displacement of certain cations.

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Several promising initiator systems for the ambient polymerization of dental monomers were developed utilizing the oxidation-reduction reactions of certain organic peroxides and certain transition metal compounds with L(+) ascorbic acid and its derivatives.

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