3,655 research outputs found
Recent development of inorganic nanoparticles for biomedical imaging
Inorganic nanoparticle-based biomedical imaging probes have been studied extensively as a potential alternative to conventional molecular imaging probes. Not only can they provide better imaging performance but they can also offer greater versatility of multimodal, stimuli-responsive, and targeted imaging. However, inorganic nanoparticle-based probes are still far from practical use in clinics due to safety concerns and less-optimized efficiency. In this context, it would be valuable to look over the underlying issues. This outlook highlights the recent advances in the development of inorganic nanoparticle-based probes for MRI, CT, and anti-Stokes shift-based optical imaging. Various issues and possibilities regarding the construction of imaging probes are discussed, and future research directions are suggested.
Metal/graphene sheets as p-type transparent conducting electrodes in GaN light emitting diodes
We demonstrate the use of graphene based transparent sheets as a p-type current spreading layer in GaN light emitting diodes (LEDs). Very thin Ni/Au was inserted between graphene and p-type GaN to reduce contact resistance, which reduced contact resistance from similar to 5.5 to similar to 0.6 Omega/ cm(2), with no critical optical loss. As a result, LEDs with metal-graphene provided current spreading and injection into the p-type GaN layer, enabling three times enhanced electroluminescent intensity compared with those with graphene alone. We confirmed very strong blue light emission in a large area of the metal-graphene layer by analyzing image brightness.open281
Visible emission from Ce-doped ZnO nanorods grown by hydrothermal method without a post thermal annealing process
Visible light-emitting Ce-doped ZnO nanorods [NRs] without a post thermal annealing process were grown by hydrothermal method on a Si (100) substrate at a low temperature of 90°C. The structural investigations of Ce-doped ZnO NRs showed that the Ce3+ ions were successfully incorporated into the ZnO lattice sites without forming unwanted Ce-related compounds or precipitates. The optical investigation by photoluminescence spectra shows that the doped Ce3+ ions in the ZnO NRs act as an efficient luminescence center at 540 nm which corresponds to the optical transition of 5d → 4f orbitals in the Ce3+ ions. The photoluminescence intensity of the Ce-doped ZnO NRs increased with the increasing content of the Ce-doping agent because the energy transfer of the excited electrons in ZnO to the Ce3+ ions would be enhanced by increased Ce3+ ions
Self-supervised Image Denoising with Downsampled Invariance Loss and Conditional Blind-Spot Network
There have been many image denoisers using deep neural networks, which
outperform conventional model-based methods by large margins. Recently,
self-supervised methods have attracted attention because constructing a large
real noise dataset for supervised training is an enormous burden. The most
representative self-supervised denoisers are based on blind-spot networks,
which exclude the receptive field's center pixel. However, excluding any input
pixel is abandoning some information, especially when the input pixel at the
corresponding output position is excluded. In addition, a standard blind-spot
network fails to reduce real camera noise due to the pixel-wise correlation of
noise, though it successfully removes independently distributed synthetic
noise. Hence, to realize a more practical denoiser, we propose a novel
self-supervised training framework that can remove real noise. For this, we
derive the theoretic upper bound of a supervised loss where the network is
guided by the downsampled blinded output. Also, we design a conditional
blind-spot network (C-BSN), which selectively controls the blindness of the
network to use the center pixel information. Furthermore, we exploit a random
subsampler to decorrelate noise spatially, making the C-BSN free of visual
artifacts that were often seen in downsample-based methods. Extensive
experiments show that the proposed C-BSN achieves state-of-the-art performance
on real-world datasets as a self-supervised denoiser and shows qualitatively
pleasing results without any post-processing or refinement
Korea’s technical assistance for better governance
노트 : - Paper for International Conference on U.S.-Korea Dialogue on Strategies for Effective Development Cooperation
- Organized by Asia Foundation October 17-18, 2011 Seoul, Korea
행사명 : International Conference on U.S.-Korea Dialogue on Strategies for Effective Development Cooperatio
Quantifying and monitoring functional Photosystem II and the stoichiometry of the two photosystems in leaf segments: Approaches and approximations
Given its unique function in light-induced
water oxidation and its susceptibility to photoinactivation
during photosynthesis, photosystem II (PS II) is often the
focus of studies of photosynthetic structure and function,
particularly in environmental stress conditions. Here we
review four approaches for quantifying or monitoring PS II
functionality or the stoichiometry of the two photosystems
in leaf segments, scrutinizing the approximations in each
approach. (1) Chlorophyll fluorescence parameters are
convenient to derive, but the information-rich signal suffers
from the localized nature of its detection in leaf tissue. (2)
The gross O2 yield per single-turnover flash in CO2-enriched
air is a more direct measurement of the functional
content, assuming that each functional PS II evolves one
O2 molecule after four flashes. However, the gross O2 yield
per single-turnover flash (multiplied by four) could overestimate
the content of functional PS II if mitochondrial
respiration is lower in flash illumination than in darkness.
(3) The cumulative delivery of electrons from PS II to P700? (oxidized primary donor in PS I) after a flash is
added to steady background far-red light is a whole-tissue
measurement, such that a single linear correlation with
functional PS II applies to leaves of all plant species
investigated so far. However, the magnitude obtained in a
simple analysis (with the signal normalized to the maximum
photo-oxidizable P700 signal), which should equal
the ratio of PS II to PS I centers, was too small to match the
independently-obtained photosystem stoichiometry. Further,
an under-estimation of functional PS II content could
occur if some electrons were intercepted before reaching
PS I. (4) The electrochromic signal from leaf segments
appears to reliably quantify the photosystem stoichiometry,
either by progressively photoinactivating PS II or suppressing
PS I via photo-oxidation of a known fraction of
the P700 with steady far-red light. Together, these
approaches have the potential for quantitatively probing PS
II in vivo in leaf segments, with prospects for application
of the latter two approaches in the field
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