•A wet electrostatic precipitator (WESP) with high efficiency was designed and tested.•The present WESP enhances nanoparticle collection efficiency by condensational growth.•Wall-cleaning water keeps ...both the collection electrodes and wires clean for long-term operation.•Good agreement between the present predictions and experimental data was obtained.•The present model can be used to facilitate the design of the wet electrostatic precipitator.
An efficient wire-to-plate single-stage wet electrostatic precipitator (WESP) was designed and tested to control nanoparticles, submicron and micron-sized particles emitted from semiconductor manufacturing processes. Tungsten-wires of 0.36mm in diameter were used as discharge electrodes and a fixed voltage of −15kV was supplied to generate the electric field and corona ions. Fine water mist at room temperature was used to quench the high temperature exhaust gas to enhance particle condensation growth and improve the collection efficiency of nanoparticles. Experimental results showed that without fine water mist, nanoparticle collection efficiency was 67.9–92.9%, which was greatly enhanced to 99.2–99.7% when the WESP was operated with fine water mist. A predictive method was developed to calculate the particle collection efficiency equation η(%) in the form as η(%)=1−exp(−α(NDe)β+γ)×100%, in which α, β and γ are regression coefficients and NDe is the Deutsch number. Good agreement was obtained between present predictions and experimental data. For longer term operation, the periodic wall-cleaning water was used to clean discharge electrodes and collection electrodes regularly. In the field tests, the total collection efficiencies (40⩽dp⩽8100nm) of the WESP were found to maintain greater than 98.7% and 97.3% for continuous operation for 35 and 22day at fab A and fab B, respectively.
Wolfram syndrome is characterized by early onset diabetes mellitus, diabetes insipidus, deafness, and optic atrophy, but retinal degeneration has not been described as a major component of the ...phenotype. We present two cases with Wolfram syndrome and evidence of retinal degeneration.
Observational case series. Patients underwent complete ocular examinations as well as retinal imaging and electroretinography.
Both patients had electroretinographic evidence of retinal dysfunction/degeneration in addition to optic atrophy with an otherwise normal-appearing retina.
Some patients with Wolfram syndrome have a mild retinal degeneration that may be a manifestation of the neuronal involvement that is present in this condition.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A polyoxometalate flow battery Pratt, Harry D.; Hudak, Nicholas S.; Fang, Xikui ...
Journal of power sources,
08/2013, Letnik:
236, Številka:
C
Journal Article
Recenzirano
A redox flow battery utilizing two, three-electron polyoxometalate redox couples (SiVV3WVI9O407–/SiVIV3WVI9O4010− and SiVIV3WVI9O4010−/SiVIV3WV3WVI6O4013−) was investigated for use in stationary ...storage in either aqueous or non-aqueous conditions. The aqueous battery had coulombic efficiencies greater than 95% with relatively low capacity fading over 100 cycles. Infrared studies showed there was no decomposition of the compound under these conditions. The non-aqueous analog had a higher operating voltage but at the expense of coulombic efficiency. The spontaneous formation of these clusters by self-assembly facilitates recovery of the battery after being subjected to reversed polarity. Polyoxometalates offer a new approach to stationary storage materials because they are capable of undergoing multi-electron reactions and are stable over a wide range of pH values and temperatures.
► Construction of a flow battery with vanadium- and tungsten-polyoxometalates. ► Coulombic efficiencies were greater than 95% with low capacity fading. ► The compounds are stable over a wide range of conditions. ► Polyoxometalates undergo multi-electron reactions.
Wolfram syndrome is a monogenic disease mainly caused by mutations in the WFS1 gene. Mutations in the WFS1 gene give rise to diabetes. Here, we characterized mutant WFS1 proteins by studying the ...stability of full‐length wild‐type (WT) WFS1, a missense mutant P724L, and two C‐terminally truncated mutants, W837X and Y652X. We compared their stability by overexpressing them in MIN6 and HEK293T cells. The C‐terminally truncated mutants W837X and Y652X are degraded more rapidly than the missense P724L mutant or wild‐type WFS1 in MIN6 cells. In contrast, Y652X is more stable than WT or other mutant WFS1 proteins in HEK293T. In conclusion, we found that C‐terminally truncated WFS1 mutants are selectively degraded in a cell type‐specific manner.
The WFS1 gene is mutated in Wolfram syndrome, characterized by diabetes mellitus and optic atrophy. We compared the stability of full‐length WFS1 (wild‐type or a missense mutant) and C‐terminally truncated mutants by overexpressing them in a pancreatic beta cell or non‐pancreatic beta cell line. We found that the C‐terminally truncated mutants are selectively degraded in the pancreatic beta cell line.
Photocatalytic and photoelectrochemical (PEC) water splitting to generate clean fuel H
2
and O
2
from water and solar energy using semiconductor nanomaterials is a green technology which could ...fulfill the growing energy need of the future and environment concerns. WO
x≤3
has received considerable attention in photo-assisted water splitting due to its fascinating advantages such as absorbance in visible region up to ~ 480 nm, low cost, and stability in acidic and oxidative conditions. In this review, an attempt is made to summarize the important efforts made in the literature on the employment of WO
3
for PEC water splitting in the last 5 years. Great milestones in PEC performance of WO
3
have been reached with possible improvements via morphology control, crystal structure/facet, introduction of oxygen vacancy/defects and choice of suitable electrolyte. It is established that, WO
3
nanostructure thin films require annealing, usually between 450 and 550 °C to attain more crystallinity and monoclinic phase of WO
x≤3
is the most stable phase at room temperature and demonstrated highest photocatalytic activity when compared to other crystal phases. WO
3
structures that are tightly interconnected and strongly bound to the metal collector substrate result in increased photogenerated charge collection efficiency while increase in PEC operating temperature augments the gas evolution quantity. Finally, we provide possibility for further improvements in WO
3
-based PCE which may be required to enhance its efficiency in water splitting.
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•Hierarchical structure of HY zeolite enhanced silanol density.•Higher silanol density increased formation of active isolated tungsten oxo species.•Dealuminated aluminosilicate ...structure reduced side reactions.•W/Hi-HY exhibited high propene conversion and ethene/butenes selectivity.
The formation of isolated tungstate sites on hierarchical structured SiO2 nanoparticles and HY zeolite with high Si/Al ratio (Si/Al 500) was investigated in the self-metathesis of propene over supported WOx-based catalysts. The synthesis of hierarchical HY not only increased the tungsten dispersion in the forms of isolated tungstate oxo species (mono-oxo and di-oxo) by increasing the terminal silanol group density of the support for these oxides to be grafted on but also greatly reduced the heavy hydrocarbon formation simultaneously by elimination of some alumina from the zeolite. As a consequence, higher propene conversion was obtained without the undesired reactions especially during the initial stage, when the metallocarbene was not fully developed. The results present a facile method for the development of heterogeneous WOx-based metathesis catalysts and a better correlation between the surface properties of catalyst support and the formation of tungsten pre-catalysis active species.
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•Doping of TiO2 with W or Mo leads to a higher photo-activity.•Low content of W or Mo is related to the best performance of TiO2 as photocatalyst.•Addition of dopants eliminates the ...need of oxygen addition.
W-doped TiO2 and Mo-doped TiO2 photocatalysts were synthesized by EISA method and were characterized by different techniques. The photoactivity of these materials was evaluated by the degradation of 4-chlorophenol without oxygen supply. The catalysts exhibited only anatase crystalline phase and high specific surface areas of about 179m2g−1. The amount of dopant cations in TiO2 was a key parameter to increase the photoactivity. The results obtained show that with low dopant concentrations the degradation is improved, and this can be attributed to an increase in the lifetime of the photogenerated charges due to that dopant cations may easily trap electrons decreasing the recombination rate. Doped photocatalysts degraded 95% of 4CP, three times faster than Degussa P25. 69% reduction of total organic carbon (TOC) content was achieved by 1wt.% W-doping.
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•Ti-W mixed oxide photocatalysts were prepared by the sol-gel method and calcined.•W addition induced TiO2 anatase phase stabilization up to calcination at 700°C.•Atomically dispersed ...tungsten is incorporated into the titania lattice.•Best photocatalytic performances were attained with a W/Ti molar ratio of 1%.
TiO2 and Ti-W mixed oxide photocatalysts, with W/Ti molar ratios in the 0–5% range, were prepared through a simple sol-gel method, followed by annealing at 500 or 700°C, and their photoactivity was tested in the photo-oxidation of formic acid in the aqueous phase under ambient aerobic conditions. XRPD analysis evidenced that in the presence of tungsten the anatase phase was stable even after calcination at 700°C, with a progressively larger surface area and smaller particle dimensions with increasing tungsten content. Tungsten can both enter the titania lattice, as demonstrated by HAADF-STEM analysis, and also segregate as amorphous WO3 on the photocatalysts surface, as suggested by XPS analysis. The best performing Ti/W oxide photocatalyst is that containing 1.0mol% W/Ti, mainly due to the tungsten-induced stabilization effect of the anatase phase, whereas electron transfer from TiO2 to WO3, though compatible with the here performed EPR measurements, appears to have no beneficial effect in the investigated reaction, likely due to the low energy level of the conduction band of WO3, from which electrons cannot efficiently transfer to adsorbed dioxygen.
Excitons in two-dimensional transition metal dichalcogenide monolayers (2D-TMDs) are of essential importance due to their key involvement in 2D-TMD-based applications. For instance, exciton ...dissociation and exciton radiative recombination are indispensible processes in photovoltaic and light-emitting devices, respectively. These two processes depend drastically on the photogeneration efficiency and lifetime of excitons. Here, we incorporate femtosecond pump-probe spectroscopy to investigate the ultrafast dynamics of exciton formation and decay in a single crystal of monolayer 2D tungsten disulfide (WS
2
). Investigation of the formation dynamics of the lowest exciton (X
A
) indicated that the formation time linearly increases from ∼150 fs upon resonant excitation, to ∼500 fs following excitation that is ∼1.1 eV above the band-gap. This dependence is attributed to the time it takes highly excited electrons in the conduction band (CB) to relax to the CB minimum (CBM) and contribute to the formation of X
A
. This is confirmed by infrared measurements of electron intraband relaxation dynamics. Furthermore, pump-probe experiments suggested that the X
A
ground state depletion recovery dynamics depend on the excitation energy as well. The average recovery time increased from ∼10 ps in the case of resonant excitation to ∼50 ps following excitation well above the band-gap. Having the ability to control whether generating short-lived or long-lived electron-hole pairs in 2D-TMD monolayers opens a new horizon for the application of these materials. For instance, long-lived electron-hole pairs are appropriate for photovoltaic devices, but short-lived excitons are more beneficial for lasers with ultrashort pulses.
Excitons in two-dimensional transition metal dichalcogenide monolayers (2D-TMDs) are of essential importance due to their key involvement in 2D-TMD-based applications.
Schottky barriers formed by graphene (monolayer, bilayer, and multilayer) on 2D layered semiconductor tungsten disulfide (WS
2
) nanosheets are explored for solar energy harvesting. The ...characteristics of the graphene-WS
2
Schottky junction vary significantly with the number of graphene layers on WS
2
, resulting in differences in solar cell performance. Compared with monolayer or stacked bilayer graphene, multilayer graphene helps in achieving improved solar cell performance due to superior electrical conductivity. The all-layered-material Schottky barrier solar cell employing WS
2
as a photoactive semiconductor exhibits efficient photon absorption in the visible spectral range, yielding 3.3% photoelectric conversion efficiency with multilayer graphene as the Schottky contact. Carrier transport at the graphene/WS
2
interface and the interfacial recombination process in the Schottky barrier solar cells are examined.
Schottky barriers formed by graphene (monolayer, bilayer, and multilayer) on 2D layered semiconductor tungsten disulfide (WS
2
) nanosheets are explored for solar energy harvesting.
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