2,186 research outputs found
19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact.
We demonstrate an InP heterojunction solar cell employing an ultrathin layer (ā¼10 nm) of amorphous TiO2 deposited at 120 Ā°C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm2 and a high power conversion efficiency of 19.2%
The RNA helicase, eIF4A-1, is required for ovule development and cell size homeostasis in Arabidopsis
eIF4A is a highly conserved RNAāstimulated ATPase and helicase involved in the initiation of mRNA translation. The Arabidopsis genome encodes two isoforms, one of which (eIF4Aā1) is required for the coordination between cell cycle progression and cell size. A TāDNA mutant eif4a1 line, with reduced eIF4A protein levels, displays slow growth, reduced lateral root formation, delayed flowering and abnormal ovule development. Loss of eIF4Aā1 reduces the proportion of mitotic cells in the root meristem and perturbs the relationship between cell size and cell cycle progression. Several cell cycle reporter proteins, particularly those expressed at G2/M, have reduced expression in eif4a1 mutant meristems. Single eif4a1 mutants are semisterile and show aberrant ovule growth, whereas double eif4a1Ā eif4a2 homozygous mutants could not be recovered, indicating that eIF4A function is essential for plant growth and development
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Elucidating Reversible Electrochemical Redox of Li6PS5CI Solid Electrolyte
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Current Development of Biodegradable Polymeric Materials for Biomedical Applications
In the last half-century, the development of biodegradable polymeric materials for biomedical applications has advanced significantly. Biodegradable polymeric materials are favored in the development of therapeutic devices, including temporary implants and three-dimensional scaffolds for tissue engineering. Further advancements have occurred in the utilization of biodegradable polymeric materials for pharmacological applications such as delivery vehicles for controlled/sustained drug release. These applications require particular physicochemical, biological, and degradation properties of the materials to deliver effective therapy. As a result, a wide range of natural or synthetic polymers able to undergo hydrolytic or enzymatic degradation is being studied for biomedical applications. This review outlines the current development of biodegradable natural and synthetic polymeric materials for various biomedical applications, including tissue engineering, temporary implants, wound healing, and drug delivery. Ā© 2018 Song et al
Learning to Generate Image Embeddings with User-level Differential Privacy
Small on-device models have been successfully trained with user-level
differential privacy (DP) for next word prediction and image classification
tasks in the past. However, existing methods can fail when directly applied to
learn embedding models using supervised training data with a large class space.
To achieve user-level DP for large image-to-embedding feature extractors, we
propose DP-FedEmb, a variant of federated learning algorithms with per-user
sensitivity control and noise addition, to train from user-partitioned data
centralized in the datacenter. DP-FedEmb combines virtual clients, partial
aggregation, private local fine-tuning, and public pretraining to achieve
strong privacy utility trade-offs. We apply DP-FedEmb to train image embedding
models for faces, landmarks and natural species, and demonstrate its superior
utility under same privacy budget on benchmark datasets DigiFace, EMNIST, GLD
and iNaturalist. We further illustrate it is possible to achieve strong
user-level DP guarantees of while controlling the utility drop
within 5%, when millions of users can participate in training
Dust Ejection from Planetary Bodies by Temperature Gradients: Laboratory Experiments
Laboratory experiments show that dusty bodies in a gaseous environment eject
dust particles if they are illuminated. We find that even more intense dust
eruptions occur when the light source is turned off. We attribute this to a
compression of gas by thermal creep in response to the changing temperature
gradients in the top dust layers. The effect is studied at a light flux of 13
kW/(m*m) and 1 mbar ambient pressure. The effect is applicable to
protoplanetary disks and Mars. In the inner part of protoplanetary disks,
planetesimals can be eroded especially at the terminator of a rotating body.
This leads to the production of dust which can then be transported towards the
disk edges or the outer disk regions. The generated dust might constitute a
significant fraction of the warm dust observed in extrasolar protoplanetary
disks. We estimate erosion rates of about 1 kg/s for 100 m parent bodies. The
dust might also contribute to subsequent planetary growth in different
locations or on existing protoplanets which are large enough not to be
susceptible to particle loss by light induced ejection. Due to the ejections,
planetesimals and smaller bodies will be accelerated or decelerated and drift
outward or inward, respectively. The effect might also explain the entrainment
of dust in dust devils on Mars, especially at high altitudes where gas drag
alone might not be sufficient.Comment: 7 pages, 10 figure
Metal-catalyzed crystallization of amorphous carbon to graphene
Metal-catalyzed crystallization of amorphous carbon to graphene by thermal annealing is demonstrated. In this "limited source" process scheme, the thickness of the precipitated graphene is directly controlled by the thickness of the initial amorphous carbon layer. This is in contrast to chemical vapor deposition processes, where the carbon source is virtually unlimited and controlling the number of graphene layers depends on the tight control over a number of deposition parameters. Based on the Raman analysis, the quality of graphene is comparable to other synthesis methods found in the literature, such as chemical vapor deposition. The ability to synthesize graphene sheets with tunable thickness over large areas presents an important progress toward their eventual integration for various technological applications.open826
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