3,139 research outputs found
Recommended from our members
Rainfall Runoff and Dissolved Pollutant Transport Processes Over Idealized Urban Catchments
Urban stormwater runoff is often considered as one of the most significant contributors to water pollution. Particulates are commonly regarded as the primary form of pollutant transport in the urban environment, but the contribution from the dissolved pollutants can also be significant. This study aims to investigate the dissolved pollutant transport process over urban catchments, especially the effects of buildings and spatial distribution of pollutants. The concept of “exchange layer” has been adopted and an equation has been proposed to describe the release process of dissolved pollutant from the exchange layer to the runoff water. A horizontal two-dimensional water flow and pollutant transport model has been developed for predicting dissolved pollutant runoff based on the shallow water assumptions and the advection-diffusion equation. A series of laboratory experiments have been conducted to verify the proposed model. It has been demonstrated that both the rainfall runoff and the pollutant runoff can be predicted accurately. Buildings slow down the runoff and pollutant transport processes, especially when buildings are staggered. The non-uniform distribution of pollutants over the catchment greatly influences the pollutant transport process over the catchment. This work provides insight into the effects of buildings and initial pollutant distribution on the dissolved pollutant transport phenomenon, which can help better design the pollution mitigation strategies
Characterization of high-resolution aerosol mass spectra of primary organic aerosol emissions from Chinese cooking and biomass burning
Aerosol mass spectrometry has proved to be a powerful tool to measure
submicron particulate composition with high time resolution. Factor analysis
of mass spectra (MS) collected worldwide by aerosol mass spectrometer (AMS)
demonstrates that submicron organic aerosol (OA) is usually composed of
several major components, such as oxygenated (OOA), hydrocarbon-like (HOA),
biomass burning (BBOA), and other primary OA. In order to help
interpretation of component MS from factor analysis of ambient OA datasets,
AMS measurements of different primary sources is required for comparison.
Such work, however, has been very scarce in the literature, especially for
high resolution MS (HR-MS) measurements, which performs improved
characterization by separating the ions of different elemental composition
at each <i>m</i>/<i>z</i> in comparison with unit mass resolution MS (UMR-MS)
measurements. In this study, primary emissions from four types of Chinese
cooking (CC) and six types of biomass burning (BB) were simulated
systematically and measured using an Aerodyne High-Resolution Time-of-Flight
AMS (HR-ToF-AMS). The MS of the CC emissions show high similarity, with <i>m</i>/<i>z</i>
41 and <i>m</i>/<i>z</i> 55 being the highest signals; the MS of the BB emissions also
show high similarity, with <i>m</i>/<i>z</i> 29 and <i>m</i>/<i>z</i> 43 being the highest signals. The
MS difference between the CC and BB emissions is much bigger than that
between different CC (or BB) types, especially for the HR-MS. The O/C ratio
of OA ranges from 0.08 to 0.13 for the CC emissions and from 0.18 to 0.26
for the BB emissions. The UMR ions of <i>m</i>/<i>z</i> 43, <i>m</i>/<i>z</i> 44, <i>m</i>/<i>z</i> 57, and <i>m</i>/<i>z</i> 60,
usually used as tracers in AMS measurements, were examined for their HR-MS
characteristics in the CC and BB emissions. In addition, the MS of the CC
and BB emissions are also compared with component MS from factor analysis of
ambient OA datasets observed in China, as well as with other AMS
measurements of primary sources in the literature. The MS signatures of
cooking and biomass burning emissions revealed in this study can be used as
important reference for factor analysis of ambient OA datasets, especially
for the relevant studies in East Asia
Brassinosteroids Regulate Anthocyanin Biosynthesis in the Ripening of Grape Berries
Anthocyanins are important components in the skins of grapes and in the development of wine colour.Various environmental factors cause poor coloration in some areas, even for the same cultivars planted indifferent production areas. The objective of this study was to evaluate the effect of exogenous brassinosteroids(BR) on the accumulation of anthocyanins and gene expression of anthocyanin biosynthesis in wine grapeberry skins. The results show that total anthocyanin content in BR-treated grapes was higher than that inthe control (CT) grapes, and that 0.4 mg/L was the most effective treatment concentration. The effect ofBR on downstream genes was more effective than that on upstream genes. Full coloration of BR-treatedgrapes was achieved seven days earlier than in the case of CT. Moreover, BR enhanced the transcriptlevel of the downstream genes of anthocyanin biosynthesis, which caused the total anthocyanin contentto increase. The induction of structural and regulatory genes of the flavonoid pathway suggests that theinterrelationships between developmental and environmental signalling pathways were magnified by BRtreatment, which actively promoted fruit coloration, namely anthocyanin biosynthesis
Recommended from our members
A physically-based model for dissolved pollutant transport over impervious surfaces
Dissolved pollutant transport over the ground surface is one of the main contributors to water pollution in urban environment. However, existing widely applied transport models are semi-empirical and the mechanism of the dissolved pollutant runoff is still not well understood. A novel physically-based transport model for dissolved pollutant is herein proposed by adopting a “control layer” concept in the overland flow. This transport model assumes that the dissolved pollutant in the upper runoff water is completely mixed with that in the underneath control layer. To verify the proposed model, a series of laboratory experiments were conducted. It showed that the predictions made by the model are in good agreement with the experimental results. The depth of the control layer is mainly correlated with the bed slope and shows no obvious dependence on rainfall intensity. The minimum depth of the control layer is bounded by a limiting value. In addition, the maximum pollutant transport rate is found to occur at the time of concentration. The rainfall intensity, bed slope, surface roughness and catchment length are dominant factors that control the dissolved pollutant transport. The wash-off coefficient is a function of time and is found to be the reciprocal of the average water depth of the catchment area over which the equilibrium state has been reached. This study advances the understanding of the mechanism of the dissolved pollutant transport in urban environment.This work was financially supported by the National Key Research and Development Program of China (2016YFC0402605), the Natural science foundation of Jiangsu province (BK20191299), the 111 Project (B17015), the Royal Academy of Engineering UK-China Urban Flooding Research Impact Programme (UUFRIP\100051) and the Special Fund of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(20195025712)
Isorhamnetin: A review of pharmacological effects.
Isorhamnetin is one of the most important active ingredients in the fruits of Hippophae rhamnoides L. and the leaves of Ginkgo biloba L., which possesses extensive pharmacological activities. At present, there have been numerous investigations on isorhamnetin, which has the effects of cardiovascular and cerebrovascular protection, anti-tumor, anti-inflammatory, anti-oxidation, organ protection, prevention of obesity, etc. The related mechanisms involve the regulation of PI3K/AKT/PKB, NF-κB, MAPK and other signaling pathways as well as the expression of related cytokines and kinases. Isorhamnetin has a high value of development and application. However, the investigations on its mechanism of action are limited and lack of detailed scientific validation. The manuscript reviewed the pharmacological effects of isorhamnetin and related mechanisms of action for the development of its medicinal properties further
Application of GGBFS and Bentonite to Auto-Healing Cracks of Cement Paste
Cracks are caused by many factors. Shrinkage and external loading are the most common reason. It becomes a problem when the ingression of aggressive and harmful substance penetrates to the concrete gap. This problem reduces the durability of the structures. It is well known that self – healing of cracks significantly improves the durability of the concrete structure. This paper presents self-healing cracks of cement paste containing bentonite associated with ground granulated blast furnace slag. The self-healing properties were evaluated with four parameters: crack width on the surface, crack depth, tensile strength recovery, and flexural recovery. In combination with microscopic observation, a healing process over time is also performed. The results show that bentonite improves the healing properties, in terms of surface crack width and crack depth. On the other hand, GGBFS could also improve the healing process, in terms of crack depth, direst tensile recovery, and flexural stiffness recovery. Carbonation reaction is believed as the main mechanism, which contributes the self-healing process as well as the continuous hydration progress
An improved method for calculating the regional crop water footprint based on a hydrological process analysis
Fresh water is consumed during agricultural production. With the shortage of
water resources, assessing the water use efficiency is crucial to effectively
manage agricultural water resources. The water footprint is an improved index
for water use evaluation, and it can reflect the quantity and types of water
usage during crop growth. This study aims to establish a method for
calculating the regional-scale water footprint of crop production based on
hydrological processes, and the water footprint is quantified in terms of
blue and green water. This method analyses the water-use process during the
growth of crops, which includes irrigation, precipitation, groundwater,
evapotranspiration, and drainage, and it ensures a more credible evaluation
of water use. As illustrated by the case of the Hetao irrigation
district (HID), China, the water footprint of wheat, corn and sunflowers were
calculated using this method. The results show that canal water loss and
evapotranspiration were responsible for most of the water consumption and
accounted for 47.9 % and 41.8 % of the total consumption, respectively.
The total water footprint of wheat, corn and sunflowers were 1380–2888, 942–1774 and
2095–4855 m3 t−1, respectively, and the blue footprint accounts
for more than 86 %. The spatial distribution pattern of the green, blue and
total water footprints for the three crops demonstrated that higher values
occurred in the eastern part of the HID, which had more precipitation and was
further away from the irrigation gate. This study offers a vital reference
for improving the method used to calculate the crop water footprint.</p
Nonlocal Phases of Local Quantum Mechanical Wavefunctions in Static and Time-Dependent Aharonov-Bohm Experiments
We show that the standard Dirac phase factor is not the only solution of the
gauge transformation equations. The full form of a general gauge function (that
connects systems that move in different sets of scalar and vector potentials),
apart from Dirac phases also contains terms of classical fields that act
nonlocally (in spacetime) on the local solutions of the time-dependent
Schr\"odinger equation: the phases of wavefunctions in the Schr\"odinger
picture are affected nonlocally by spatially and temporally remote magnetic and
electric fields, in ways that are fully explored. These contributions go beyond
the usual Aharonov-Bohm effects (magnetic or electric). (i) Application to
cases of particles passing through static magnetic or electric fields leads to
cancellations of Aharonov-Bohm phases at the observation point; these are
linked to behaviors at the semiclassical level (to the old Werner & Brill
experimental observations, or their "electric analogs" - or to recent reports
of Batelaan & Tonomura) but are shown to be far more general (true not only for
narrow wavepackets but also for completely delocalized quantum states). By
using these cancellations, certain previously unnoticed sign-errors in the
literature are corrected. (ii) Application to time-dependent situations
provides a remedy for erroneous results in the literature (on improper uses of
Dirac phase factors) and leads to phases that contain an Aharonov-Bohm part and
a field-nonlocal part: their competition is shown to recover Relativistic
Causality in earlier "paradoxes" (such as the van Kampen thought-experiment),
while a more general consideration indicates that the temporal nonlocalities
found here demonstrate in part a causal propagation of phases of quantum
mechanical wavefunctions in the Schr\"odinger picture. This may open a direct
way to address time-dependent double-slit experiments and the associated causal
issuesComment: 49 pages, 1 figure, presented in Conferences "50 years of the
Aharonov-Bohm effect and 25 years of the Berry's phase" (Tel Aviv and
Bristol), published in Journ. Phys. A. Compared to the published paper, this
version has 17 additional lines after eqn.(14) for maximum clarity, and the
Abstract has been slightly modified and reduced from the published 2035
characters to the required 1920 character
A detailed analysis of a multi-agent diverse team
In an open system we can have many different kinds of agents. However, it is a challenge to decide which agents to pick when forming multi-agent teams. In some scenarios, agents coordinate by voting continuously. When forming such teams, should we focus on the diversity of the team or on the strength of each member? Can a team of diverse (and weak) agents outperform a uniform team of strong agents? We propose a new model to address these questions. Our key contributions include: (i) we show that a diverse team can overcome a uniform team and we give the necessary conditions for it to happen; (ii) we present optimal voting rules for a diverse team; (iii) we perform synthetic experiments that demonstrate that both diversity and strength contribute to the performance of a team; (iv) we show experiments that demonstrate the usefulness of our model in one of the most difficult challenges for Artificial Intelligence: Computer Go
- …