76 research outputs found
Review of recent progress in unassisted photoelectrochemical water splitting: from material modification to configuration design
Photoelectrochemical (PEC) energy conversion systems have been considered as a highly potential strategy for clean solar fuel production, simultaneously addressing the energy and environment challenges we are facing. Tremendous research efforts have been made to design and develop feasible unassisted PEC systems that can efficiently split water into hydrogen (H2) and oxygen with only the energy input of sunlight. A fundamental understanding of the concepts involved in PEC water splitting and energy conversion efficiency enhancement for solar fuel production is important for better system design. This review gives a concise overview of the unassisted PEC devices with some state-of-the-art progress toward efficient PEC devices for future sustainable solar energy utilization
Beyond Myopia: Learning from Positive and Unlabeled Data through Holistic Predictive Trends
Learning binary classifiers from positive and unlabeled data (PUL) is vital
in many real-world applications, especially when verifying negative examples is
difficult. Despite the impressive empirical performance of recent PUL methods,
challenges like accumulated errors and increased estimation bias persist due to
the absence of negative labels. In this paper, we unveil an intriguing yet
long-overlooked observation in PUL: \textit{resampling the positive data in
each training iteration to ensure a balanced distribution between positive and
unlabeled examples results in strong early-stage performance. Furthermore,
predictive trends for positive and negative classes display distinctly
different patterns.} Specifically, the scores (output probability) of unlabeled
negative examples consistently decrease, while those of unlabeled positive
examples show largely chaotic trends. Instead of focusing on classification
within individual time frames, we innovatively adopt a holistic approach,
interpreting the scores of each example as a temporal point process (TPP). This
reformulates the core problem of PUL as recognizing trends in these scores. We
then propose a novel TPP-inspired measure for trend detection and prove its
asymptotic unbiasedness in predicting changes. Notably, our method accomplishes
PUL without requiring additional parameter tuning or prior assumptions,
offering an alternative perspective for tackling this problem. Extensive
experiments verify the superiority of our method, particularly in a highly
imbalanced real-world setting, where it achieves improvements of up to
in key metrics. The code is available at
\href{https://github.com/wxr99/HolisticPU}{https://github.com/wxr99/HolisticPU}.Comment: 25 page
Processable graphene oxide-embedded titanate nanofiber membranes with improved filtration performance
Graphene oxide (GO)-embedded titanate nanofiber (TNF) membranes with improved filtration performance are prepared successfully by a two-step method including electrostatic assembly of GO and TNFs into hybrids and subsequent processing of them into membranes by vacuum filtration. The embedded contents of GO sheets in films and thickness of as-assembled films can be adjusted facilely, endowing such composite films with good processability. Owing to the skilful introduction of GO sheets, the pore and/or channel structures in these hybrid membranes are modified. By treating different dye solutions (Direct Yellow and Direct Red), the filtration properties of these membranes show that the introduction of certain amount of GO sheets efficiently improve the separation performance of the membranes. Interestingly, these GO-embedded TNF membranes also display superior selective separation performance on filtrating the mixture solutions of such two dyes, making these hierarchical membranes more flexible and versatile in water treatment areas
Multiple resolution seismic attenuation imaging at Mt. Vesuvius
A three-dimensional S wave attenuation tomography of Mt. Vesuvius has been ob-
tained with multiple measurements of coda-normalized S-wave spectra of local small
magnitude earthquakes. We used 6609 waveforms, relative to 826 volcano-tectonic
earthquakes, located close to the crater axis in a depth range between 1 and 4 km
(below the sea level), recorded at seven 3-component digital seismic stations. We
adopted a two-point ray-tracing; rays were traced in an high resolution 3-D velocity
model. The spatial resolution achieved in the attenuation tomography is comparable
with that of the velocity tomography (we resolve 300 m side cubic cells). We statisti-
cally tested that the results are almost independent from the radiation pattern. We
also applied an improvement of the ordinary spectral-slope method to both P- and
S-waves, assuming that the di¤erences between the theoretical and the experimental
high frequency spectral-slope are only due to the attenuation e¤ects.We could check
the coda-normalization method comparing the S attenuation image obtained with
the two methods. The images were obtained with a multiple resolution approach.
Results show the general coincidence of low attenuation with high velocity zones.
The joint interpretation of velocity and attenuation images allows us to interpret
the low attenuation zone intruding toward the surface until a depth of 500 meters
below the sea level as related to the residual part of solidi ed magma from the last
eruption. In the depth range between -700 and -2300 meters above sea level, the
images are consistent with the presence of multiple acquifer layers. No evidence of
magma patches greater than the minimum cell dimension (300m) has been found.
A shallow P wave attenuation anomaly (beneath the southern ank of the volcano)
is consitent with the presence of gas saturated rocks. The zone characterized by
the maximum seismic energy release cohincides with a high attenuation and low
velocity volume, interpreted as a cracked medium
Recent progress on visible light responsive heterojunctions for photocatalytic applications
Photocatalysis has attracted much attention in recent years due to its potential in solving energy and environmental issues. Even though numerous achievements have been made, the photocatalytic systems developed to date are still far from practical applications due to the low efficiency and poor durability. Efficient light absorption and charge separation are two of the key factors for the exploration of high performance photocatalytic systems, which is generally difficult to be obtained in a single photocatalyst. The combination of various materials to form heterojunctions provides an effective way to better harvest solar energy and to facilitate charge separation and transfer, thus enhancing the photocatalytic activity and stability. This review concisely summarizes the recent development of visible light responsive heterojunctions, including the preparation and performances of semiconductor/semiconductor junctions, semiconductor/cocatalyst junctions, semiconductor/metal junctions, semiconductor/non-metal junctions, and surface heterojunctions, and their mechanism for enhanced light harvesting and charge separation/transfer
Opposite effects of single-dose and multidose administration of the ethanol extract of danshen on
The aim of this study was to investigate the effect of single-and multidose administration of the ethanol extract of danshen on in vivo CYP3A activity in healthy volunteers. A sequential, open-label, and three-period pharmacokinetic interaction study design was used based on 12 healthy male individuals. The plasma concentrations of midazolam and its metabolite 1-hydroxymidazolam were measured. Treatment with single dose of the extract caused the mean max of midazolam to increase by 87% compared with control. After 10 days of the danshen extract intake, the mean AUC 0-12 , max , and 1/2 of midazolam were decreased by 79.9%, 66.6%, and 43.8%, respectively. The mean clearance of midazolam was increased by 501.6% compared with control. The in vitro study showed that dihydrotanshinone I in the extract could inhibit CYP3A, while tanshinone IIA and cryptotanshinone could induce CYP3A. In conclusion, a single-dose administration of the danshen extract can inhibit intestinal CYP3A, but multidose administration can induce intestinal and hepatic CYP3A
Facet and defect engineering of metal oxide photoanodes for efficient photoelectrochemical water splitting
Recent progress of tungsten- and molybdenum-based semiconductor materials for solar-hydrogen production
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