360 research outputs found
Performance Analysis of a Near-Field Thermophotovoltaic Device with a Metallodielectric Selective Emitter and Electrical Contacts for the Photovoltaic Cell
A near-field thermophotovoltaic (TPV) system with a multilayer emitter of
alternate tungsten and alumina layer is proposed in this paper. The
fluctuational electrodynamics along with the dyadic Green function for a
multilayered structure is applied to calculate the spectral heat flux, and the
charge transport equations are solved to get the photocurrent generation and
electrical power output. The spectral heat flux is much enhanced when plain
tungsten emitter is replaced with multilayer emitter. The mechanism of surface
plasmon polariton coupling in the tungsten thin film, which is responsible for
the heat flux enhancement, is analyzed. In addition, the invalidity of
effective medium theory to predict the optical properties of multilayer
structure in near-field radiation is discussed. The tungsten and alumina layer
thicknesses are optimized to match the spectral heat flux with the bandgap of
TPV cell. Practically, with a gold reflector placed on the back of TPV cell,
which also acts as the back electrode, and a 5-nm-thick indium tin oxide (ITO)
layer as the front contact, when the emitter and receiver temperature are
respectively set as 2000 K and 300 K, the conversion efficiency and electrical
power output can be achieved to 23.7% and 0.31 MW/m2 at a vacuum gap distance
of 100 nm
Effect and Evaluation of an Ultrasonic Atomizer With Large Vibration Amplitude
An ultrasonic atomizer can produce large vibration amplitude is
designed. Different from the structure of the usually seen ultrasonic
spray nozzle, the atomizer is fundamentally constructed with a hollow tube encircled with several pieces of sectional type piezoelectric
actuators, which can radially oscillate the tube to generate desired
vibration profile. Atomization is formed on the surface around the
liquid outlet of the tube where maximum vibration amplitude
occurs. In search of resonance frequency and vibration amplitude,
modal and harmonic analyses of the ultrasonic atomizer are carried
out by ANSYS. In comparison the simulated results with the experimental results, both are in good agreement. A measurement system
is set up for detecting the atomization droplets and calculating the
droplet size and distribution. An attempt is to design an ultrasonic
atomizer can produce high distribution and small diameter droplets
for some application-level requirements, droplet diameter around
20�60 lm is assumed to be the specification for performance verification of the proposed atomizer. In experiment, it is found nearly
90% of atomized droplets fit for the requirement. Besides the most
important factor of operating frequency, a relation of amplitude is
found to include in the well-known Lang and Rayleigh�s equation
Taiwan Oscillation Network
The Taiwan Oscillation Network (TON) is a ground-based network to measure solar intensity oscillations to study the internal structure of the Sun. K-line full-disk images of 1000 pixels diameter are taken at a rate of one image per minute. Such data would provide information onp-modes withl as high as 1000. The TON will consist of six identical telescope systems at proper longitudes around the world. Three telescope systems have been installed at Teide Observatory (Tenerife), Huairou Solar Observing Station (near Beijing), and Big Bear Solar Observatory (California). The telescopes at these three sites have been taking data simultaneously since October of 1994. Anl – v diagram derived from 512 images is included to show the quality of the data
Fermi surface topology and low-lying electronic structure of a new iron-based superconductor Ca10(Pt3As8)(Fe2As2)5
We report a first study of low energy electronic structure and Fermi surface
topology for the recently discovered iron-based superconductor
Ca10(Pt3As8)(Fe2As2)5 (the 10-3-8 phase, with Tc = 8K), via angle-resolved
photoemission spectroscopy (ARPES). Despite its triclinic crystal structure,
ARPES results reveal a fourfold symmetric band structure with the absence of
Dirac-cone-like Fermi dots (related to magnetism) found around the Brillouin
zone corners in other iron-based superconductors. Considering that the
triclinic lattice and structural supercell arising from the Pt3As8 intermediary
layers, these results indicate that those layers couple only weakly to the FeAs
layers in this new superconductor, which has implications for the determination
of its potentially novel pairing mechanism.Comment: 5 pages, 4 figure
Discovery of New Eunicellins from an Indonesian Octocoral Cladiella sp.
Two new 11-hydroxyeunicellin diterpenoids, cladieunicellin F (1) and (–)-solenopodin C (2), were isolated from an Indonesian octocoral Cladiella sp. The structures of eunicellins 1 and 2 were established by spectroscopic methods, and eunicellin 2 was found to be an enantiomer of the known eunicellin solenopodin C (3). Eunicellin 2 displayed inhibitory effects on the generation of superoxide anion and the release of elastase by human neutrophils. The previously reported structures of two eunicellin-based compounds, cladielloides A and B, are corrected in this study
Pilot Scale Production of Highly Efficacious and Stable Enterovirus 71 Vaccine Candidates
BACKGROUND: Enterovirus 71 (EV71) has caused several epidemics of hand, foot and mouth diseases (HFMD) in Asia and now is being recognized as an important neurotropic virus. Effective medications and prophylactic vaccine against EV71 infection are urgently needed. Based on the success of inactivated poliovirus vaccine, a prototype chemically inactivated EV71 vaccine candidate has been developed and currently in human phase 1 clinical trial. PRINCIPAL FINDING: In this report, we present the development of a serum-free cell-based EV71 vaccine. The optimization at each step of the manufacturing process was investigated, characterized and quantified. In the up-stream process development, different commercially available cell culture media either containing serum or serum-free was screened for cell growth and virus yield using the roller-bottle technology. VP-SFM serum-free medium was selected based on the Vero cell growth profile and EV71 virus production. After the up-stream processes (virus harvest, diafiltration and concentration), a combination of gel-filtration liquid chromatography and/or sucrose-gradient ultracentrifugation down-stream purification processes were investigated at a pilot scale of 40 liters each. Although the combination of chromatography and sucrose-gradient ultracentrifugation produced extremely pure EV71 infectious virus particles, the overall yield of vaccine was 7-10% as determined by a VP2-based quantitative ELISA. Using chromatography as the downstream purification, the virus yield was 30-43%. To retain the integrity of virus neutralization epitopes and the stability of the vaccine product, the best virus inactivation was found to be 0.025% formalin-treatment at 37 °C for 3 to 6 days. Furthermore, the formalin-inactivated virion vaccine candidate was found to be stable for >18 months at 4 °C and a microgram of viral proteins formulated with alum adjuvant could induce strong virus-neutralizing antibody responses in mice, rats, rabbits, and non-human primates. CONCLUSION: These results provide valuable information supporting the current cell-based serum-free EV71 vaccine candidate going into human Phase I clinical trials
Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks
A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV
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