698 research outputs found
Intense ultraviolet emission from needle-like WO3 nanostructures synthesized by noncatalytic thermal evaporation
Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges. The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states
Programmable spectral shaping to improve the measurement precision of frequency comb mode-resolved spectral interferometric ranging
Comb-mode resolved spectral domain interferometry (CORE-SDI), which is
capable of measuring length of kilometers or more with precision on the order
of nanometers, is considered to be a promising technology for next-generation
length standards, replacing laser displacement interferometers. In this study,
we aim to improve the measurement precision of CORE-SDI using programmable
spectral shaping. We report the generation of effectively broad and symmetric
light sources through the programmable spectral shaping. The light source used
here was generated by the spectrally-broadened electro-optic comb with a
repetition rate of 17.5 GHz. Through the programmable spectral shaping, the
optical spectrum was flattened within 1 dB, resulting in a square-shaped
optical spectrum. As a result, the 3-dB spectral width was extended from 1.15
THz to 6.7 THz. We performed a comparison between the measurement results of
various spectrum shapes. We confirmed an improvement in the measurement
precision from 69 nm to 6 nm, which was also corroborated by numerical
simulations. We believe that this study on enhancing the measurement precision
of CORE-SDI through the proposed spectral shaping will make a significant
contribution to reducing the measurement uncertainty of future CORE-SDI
systems, thereby advancing the development of next-generation length standards.Comment: 22 pages, 10 figure
Public-Good Nature of Environmental Conflicts : Individual and Collective Litigations
In environmental conflicts where private citizens sue a
polluter, a private citizens participation in the fight for
environmental damages is characterized by the public good
nature. We examine how the introduction of collective litigation
and asymmetric reimbursement rule affects each citizen's choice
between free-riding and participation in the collective litigation.
Following a Stackelberg model, we assume that citizens move
first and the firm follows, while each citizen has to state his
environmental damages to the court in the process. Important
findings are as follows: First, in the individual litigation, the
hungriest citizen who most highly values environmental damages
is the only one to participate. Second, in the collective litigation,
all citizens participate, provided the total damages of the
citizens' group are sufficiently larger than the damages of the
hungriest citizen. Third, under certain conditions, introduction of
the asymmetric reimbursement rule enhances the possibility that
all citizens participate in the collective litigation
Emerging respiratory infections threatening public health in the Asia-Pacific region: a position paper of the Asian Pacific Society of Respirology
In past decades, we have seen several epidemics of
respiratory infections from newly emerging viruses,
most of which originated in animals. These emerging
infections, including severe acute respiratory syndrome
coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and the pandemic
influenza A(H1N1) and avian influenza (AI) viruses,
have seriously threatened global health and the economy. In particular, MERS-CoV and AI A(H7N9) are still
causing infections in several areas, and some clustering
of cases of A(H5N1) and A(H7N9) may imply future possible pandemics. Additionally, given the inappropriate
use of antibiotics and international travel, the spread of
carbapenem-resistant Gram-negative bacteria is also a
significant concern. These infections with epidemic or
pandemic potential present a persistent threat to public
health and a huge burden on healthcare services in the
Asia-Pacific region. Therefore, to enable efficient infection prevention and control, more effective international surveillance and collaboration systems, in the
context of the ‘One Health’ approach, are necessary
Improved production of docosahexaenoic acid in batch fermentation by newly-isolated strains of Schizochytrium sp. and Thraustochytriidae sp. through bioprocess optimization
Thraustochytrids, rich in docosahexaenoic acid (DHA, C22:6??3), represent a potential source of dietary fatty acids. Yet, the effect of culture conditions on growth and fatty acid composition vary widely among different thraustochytrid strains. Two different thraustochytrid strains, Schizochytrium sp. PKU#Mn4 and Thraustochytriidae sp. PKU#Mn16 were studied for their growth and DHA production characteristics under various culture conditions. Although they exhibited similar fatty acid profiles, PKU#Mn4 seemed a good candidate for industrial DHA fermentation while PKU#Mn16 displayed growth tolerance to a wide range of process conditions. Relative DHA content of 48.5% and 49.2% (relative to total fatty acids), respectively, were achieved on glycerol under their optimal flask culture conditions. Maximum DHA yield (Yp/x) of 21.0% and 18.9% and productivity of 27.6 mg/L-h and 31.9 mg/L-h were obtained, respectively, in 5-L bioreactor fermentation operated with optimal conditions and dual oxygen control strategy. A 3.4- and 2.8-fold improvement of DHA production (g/L), respectively, was achieved in this study. Overall, our study provides the potential of two thraustochytrid strains and their culture conditions for efficient production of DHA-rich oil
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