Owing to the difficulty in detecting and manipulating the magnetic states of antiferromagnetic materials, studying their switching dynamics using electrical methods remains a challenging task. By ...employing heavy-metal-rare-earth-transition-metal alloy bilayers, we experimentally study current-induced domain wall dynamics in an antiferromagnetically coupled system. We show that the current-induced domain wall mobility reaches a maximum at the angular momentum compensation point. With experiment and modeling, we further reveal the internal structures of domain walls and the underlying mechanisms for their fast motion. We show that the chirality of the ferrimagnetic domain walls remains the same across the compensation points, suggesting that spin orientations of specific sublattices rather than net magnetization determine Dzyaloshinskii-Moriya interaction in heavy-metal-ferrimagnet bilayers. The high current-induced domain wall mobility and the robust domain wall chirality in compensated ferrimagnetic material opens new opportunities for high-speed spintronic devices.
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Manipulating the photophysical properties of light-absorbing units is a crucial element in the design of biomimetic light-harvesting systems. Using a highly tunable synthetic platform combined with ...transient absorption and time-resolved fluorescence measurements and molecular dynamics simulations, we interrogate isolated chromophores covalently linked to different positions in the interior of the hydrated nanoscale cavity of a supramolecular protein assembly. We find that, following photoexcitation, the time scales over which these chromophores are solvated, undergo conformational rearrangements, and return to the ground state are highly sensitive to their position within this cavity and are significantly slower than in a bulk aqueous solution. Molecular dynamics simulations reveal the hindered translations and rotations of water molecules within the protein cavity with spatial specificity. The results presented herein show that fully hydrated nanoscale protein cavities are a promising way to mimic the tight protein pockets found in natural light-harvesting complexes. We also show that the interplay between protein, solvent, and chromophores can be used to substantially tune the relaxation processes within artificial light-harvesting assemblies in order to significantly improve the yield of interchromophore energy transfer and extend the range of excitation transport. Our observations have implications for other important, similarly sized bioinspired materials, such as nanoreactors and biocompatible targeted delivery agents.
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IJS, KILJ, NUK, PNG, UL, UM
The Student Dust Counter (SDC) experiment of the New Horizons Mission is an impact dust detector to map the spatial and size distribution of dust along the trajectory of the spacecraft across the ...solar system. The sensors are thin, permanently polarized polyvinylidene fluoride (PVDF) plastic films that generate an electrical signal when dust particles penetrate their surface. SDC is capable of detecting particles with masses
m
>10
−12
g, and it has a total sensitive surface area of about 0.1 m
2
, pointing most of the time close to the ram direction of the spacecraft. SDC is part of the Education and Public Outreach (EPO) effort of this mission. The instrument was designed, built, tested, integrated, and now is operated by students.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU
, a cold classical Kuiper Belt object approximately 30 ...kilometers in diameter. Such objects have never been substantially heated by the Sun and are therefore well preserved since their formation. We describe initial results from these encounter observations. MU
is a bilobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color or compositional heterogeneity. No evidence for satellites, rings or other dust structures, a gas coma, or solar wind interactions was detected. MU
's origin appears consistent with pebble cloud collapse followed by a low-velocity merger of its two lobes.
Current approaches to nanoscale therapeutic delivery rely on the attachment of a drug of interest to a nanomaterial scaffold that is capable of releasing the drug selectively in a tumor environment. ...One class of nanocarriers receiving significant attention is protein nanomaterials, which are biodegradable and homogeneous in morphology and can be equipped with multiple functional handles for drug attachment. Although most protein-based nanocarriers are spherical in morphology, recent research has revealed that nonspherical nanomaterials may have favorable tumor uptake in comparison to their spherical counterparts. It is therefore important to expand the number of nonspherical protein-based nanocarriers that are available. Herein, we report the development of a self-assembling nanoscale disk derived from a double arginine mutant of recombinantly expressed tobacco mosaic virus coat protein (RR-TMV). RR-TMV disks display highly stable double-disk assembly states. These RR-TMV disks were functionalized with the chemotherapy drug doxorubicin (DOX) and further modified with polyethylene glycol (PEG) for improved solubility. RR-TMVDOX‑PEG displayed cytotoxic properties similar to those of DOX alone when incubated with U87MG glioblastoma cells, but unmodified RR-TMV did not cause any cytotoxicity. The RR-TMV disk assembly represents a promising protein-based nanomaterial for applications in drug delivery.
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We present molecular mechanics and spectroscopic calculations on prototype artificial light harvesting systems consisting of chromophores attached to a tobacco mosaic virus (TMV) protein scaffold. ...These systems have been synthesized and characterized spectroscopically, but information about the microscopic configurations and geometry of these TMV-templated chromophore assemblies is largely unknown. We use a Monte Carlo conformational search algorithm to determine the preferred positions and orientations of two chromophores, Coumarin 343 together with its linker and Oregon Green 488, when these are attached at two different sites (104 and 123) on the TMV protein. The resulting geometric information shows that the extent of disorder and aggregation properties and therefore the optical properties of the TMV-templated chromophore assembly are highly dependent on both the choice of chromophores and the protein site to which they are bound. We use the results of the conformational search as geometric parameters together with an improved tight-binding Hamiltonian to simulate the linear absorption spectra and compare with experimental spectral measurements. The ideal dipole approximation to the Hamiltonian is not valid because the distance between chromophores can be very small. We found that using the geometries from the conformational search is necessary to reproduce the features of the experimental spectral peaks.
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We have developed a method for integrating the self-assembling tobacco mosaic virus capsid into hydrophobic solvents and hydrophobic polymers. The capsid was modified at tyrosine residues to display ...an array of linear poly(ethylene glycol) chains, allowing it to be transferred into chloroform. In a subsequent step, the capsids could be transferred to a variety of hydrophobic solvents, including benzyl alcohol, o-dichlorobenzene, and diglyme. The thermal stability of the material against denaturation increased from 70 °C in water to at least 160 °C in hydrophobic solvents. With a view toward material fabrication, the polymer-coated TMV rods were also incorporated into solid polystyrene and thermally cast at 110 °C. Overall, this process significantly expands the range of processing conditions for TMV-based materials, with the goal of incorporating these templated nanoscale systems into conductive polymer matrices.
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The research aimed at the construction of the ranking of the human capital index in the regions of the Russian Federation based on the available data on the significant factors of sustainable ...development. Based on the premise that the components of the Human Capital Index calculated by the World Bank coincide with the Sustainable Development Goals from Agenda 2030 “Transforming our world”, the authors construct a Regional Rating of Human Capital Development in Russia using measurable indicators for 85 Russian regions for Targets 3 and 4 from National Sustainable Development Goals Indicator Set. The indicators were grouped into three pillars (subsets): Health, Education and Living standard, each pillar consisting of 2-4 sub-pillars and 2-6 indicators. All data for the indicator’s calculation is taken from official statistics. No expert assessment is used. The research methodology is based on generalized modified principal component analysis (GMPCA), verified by the authors' previous research. The study reflects an integrated approach to assessing the efforts of Russian regional authorities in human capital development. The research lays the foundation for regular analysis of the rating and dynamics of its components in the Russian regions, which will allow for an assessment of the current state and potential of human capital development in Russian regions and can serve to improve regional socio-economic policy.
Tuberous sclerosis complex (TSC) is a tumor predisposition syndrome with significant renal cystic and solid tumor disease. While the most common renal tumor in TSC, the angiomyolipoma, exhibits a ...loss of heterozygosity associated with disease, we have discovered that the renal cystic epithelium is composed of type A intercalated cells that have an intact Tsc gene that have been induced to exhibit Tsc‐mutant disease phenotype. This mechanism appears to be different than that for ADPKD. The murine models described here closely resemble the human disease and both appear to be mTORC1 inhibitor responsive. The induction signaling driving cystogenesis may be mediated by extracellular vesicle trafficking.
TSC renal cystic disease develops in about half of the patients. The disease appears to caused by an induction mechanism such that a small population of mutant cells can cause significant renal cystic disease comprised of mostly genetically normal cells.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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