7,681 research outputs found
Synthesis and Photocatalytic Activity for Toluene Removal of CDs/TiO2 - Zeolite Y
Hydrothermally synthesized carbon nanodots (CDs) were impregnated on TiO2. The product (CDs/TiO2) was mechanically mixed with zeolite Y for application in toluene photocatalytic oxidation reaction under UV radiation. Material properties of the samples were investigated by different methods. Toluene vapor was chosen as a typical volatile organic compound to investigate the performance of CDs/TiO2 â zeolite Y photocatalyst when these technological parameters were changed: toluene concentration, gas flow rate, humidity and UV light intensity. In each reaction, only one parameter was changed and the remaining conditions were fixed. The toluene concentrations at the beginning and the end of each reaction were analyzed with the use of gas chromatography (GC). The results of different reaction conditions show the trends for toluene treatment of the CDs/TiO2 â zeolite Y catalyst, thereby providing specific explanations for these trends. The experiments also show that toluene removal is highest when the toluene concentration in the inlet gas is 314 ppmv, the flow rate is 3 L/h, the humidity is 60%, and the catalyst (CDs/TiO2 â zeolite Y composite with 70% zeolite in weight) is illuminated by 4 UV lamps. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Dirac-Brueckner Hartree-Fock Approach: from Infinite Matter to Effective Lagrangians for Finite Systems
One of the open problems in nuclear structure is how to predict properties of
finite nuclei from the knowledge of a bare nucleon-nucleon interaction of the
meson-exchange type. We point out that a promising starting point consists in
Dirac-Brueckner-Hartree-Fock (DBHF) calculations us- ing realistic
nucleon-nucleon interactions like the Bonn potentials, which are able to
reproduce satisfactorily the properties of symmetric nuclear matter without the
need for 3-body forces, as is necessary in non-relativistic BHF calculations.
However, the DBHF formalism is still too com- plicated to be used directly for
finite nuclei. We argue that a possible route is to define effective
Lagrangians with density-dependent nucleon-meson coupling vertices, which can
be used in the Relativistic Hartree (or Relativistic Mean Field (RMF)) or
preferrably in the Relativistic Hartree- Fock (RHF) approach. The
density-dependence is matched to the nuclear matter DBHF results. We review the
present status of nuclear matter DBHF calculations and discuss the various
schemes to construct the self-energy, which lead to differences in the
predictions. We also discuss how effective Lagrangians have been constructed
and are used in actual calculations. We point out that completely consistent
calculations in this scheme still have to be performed.Comment: 16 pages, to be published in Journal of Physics G: Nuclear and
Particle Physics, special issue
Spin symmetry in Dirac negative energy spectrum in density-dependent relativistic Hartree-Fock theory
The spin symmetry in the Dirac negative energy spectrum and its origin are
investigated for the first time within the density-dependent relativistic
Hartree-Fock (DDRHF) theory. Taking the nucleus O as an example, the
spin symmetry in the negative energy spectrum is found to be a good
approximation and the dominant components of the Dirac wave functions for the
spin doublets are nearly identical. In comparison with the relativistic Hartree
approximation where the origin of spin symmetry lies in the equality of the
scalar and vector potentials, in DDRHF the cancellation between the Hartree and
Fock terms is responsible for the better spin symmetry properties and
determines the subtle spin-orbit splitting. These conclusions hold even in the
case when significant deviations from the G-parity values of the
meson-antinucleon couplings occur.Comment: 13 pages, 7 figures, 1 table, accepted by Eur. Phys. J.
Integrated optical multi-ion quantum logic
Practical and useful quantum information processing (QIP) requires
significant improvements with respect to current systems, both in error rates
of basic operations and in scale. Individual trapped-ion qubits' fundamental
qualities are promising for long-term systems, but the optics involved in their
precise control are a barrier to scaling. Planar-fabricated optics integrated
within ion trap devices can make such systems simultaneously more robust and
parallelizable, as suggested by previous work with single ions. Here we use
scalable optics co-fabricated with a surface-electrode ion trap to achieve
high-fidelity multi-ion quantum logic gates, often the limiting elements in
building up the precise, large-scale entanglement essential to quantum
computation. Light is efficiently delivered to a trap chip in a cryogenic
environment via direct fibre coupling on multiple channels, eliminating the
need for beam alignment into vacuum systems and cryostats and lending
robustness to vibrations and beam pointing drifts. This allows us to perform
ground-state laser cooling of ion motion, and to implement gates generating
two-ion entangled states with fidelities . This work demonstrates
hardware that reduces noise and drifts in sensitive quantum logic, and
simultaneously offers a route to practical parallelization for high-fidelity
quantum processors. Similar devices may also find applications in neutral atom
and ion-based quantum-sensing and timekeeping
A nonlinear fractional RayleighâStokes equation under nonlocal integral conditions
In this paper, we study the fractional nonlinear RayleighâStokes equation under nonlocal integral conditions, and the existence and uniqueness of the mild solution to our problem are considered. The ill-posedness of the mild solution to the problem recovering the initial value is also investigated. To tackle the ill-posedness, a regularized solution is constructed by the Fourier truncation method, and the convergence rate to the exact solution of this method is demonstrated.This research was funded by the National Research Foundation of Korea under grant number NRF-2020K1A3A1A05101625 and received the support from the Institute of Construction and Environmental Engineering at Seoul National University
Optimal Planning and Operational Management of Open-Market Community Microgrids
In this article, a new business model comprising multiple stakeholders is proposed to develop a frame for future flexible retail energy market in community microgrids. The microgrid comprises multiple and different distributed energy resources (DERs) such as renewable generation units, battery energy storage systems (BESSs), and micro diesel engines (MDE), to minimize daily operational costs of the system. To solve the defined complex optimization model, some operational strategies are proposed and then genetic algorithm is adopted to determine the hourly optimal power dispatch. The case study shows that the proposed model minimizes the daily operating cost of the community system effectively
A novel approach in crude enzyme laccase production and application in emerging contaminant bioremediation
Laccase enzyme from white-rot fungi is a potential biocatalyst for the oxidation of emerging contaminants (ECs), such as pesticides, pharmaceuticals and steroid hormones. This study aims to develop a three-step platform to treat ECs: (i) enzyme production, (ii) enzyme concentration and (iii) enzyme application. In the first step, solid culture and liquid culture were compared. The solid culture produced significantly more laccase than the liquid culture (447 vs. 74 ÎŒM/min after eight days), demonstrating that white rot fungi thrived on a solid medium. In the second step, the enzyme was concentrated 6.6 times using an ultrafiltration (UF) process, resulting in laccase activity of 2980 ÎŒM/min. No enzymatic loss due to filtration and membrane adsorption was observed, suggesting the feasibility of the UF membrane for enzyme concentration. In the third step, concentrated crude enzyme was applied in an enzymatic membrane reactor (EMR) to remove a diverse set of ECs (31 compounds in six groups). The EMR effectively removed of steroid hormones, phytoestrogen, ultraviolet (UV) filters and industrial chemical (above 90%). However, it had low removal of pesticides and pharmaceuticals
Low dose CT vs plain abdominal radiography for the investigation of the acute abdomen
Background: To compare low-dose abdominal computed tomography (LDCT) with plain abdominal radiography (AR) in the primary investigation of acute abdominal pain to determine if there is a difference in diagnostic yield, the number of additional investigations required and hospital length of stay (LOS).
Methods: This randomized controlled trial was approved by the institutional review board, and informed consent was obtained. Patients presenting to the emergency department with an acute abdomen and who would normally be investigated with AR were randomized to either AR or LDCT. The estimated radiation dose of the LDCT protocol was 2â3 mSv compared to 1.1 mSv for AR. Pearson\u27s chi-square and the independent samples t-test were used for the statistical analysis.
Results:âA total of 142 patients were eligible, and after exclusions and omitting those with incomplete data, 55 patients remained for analysis in the AR arm and 53 in the LDCT arm. A diagnosis could be obtained in 12 (21.8%) patients investigated with AR compared to 34 (64.2%) for LDCT (P \u3c 0.001). Twenty-eight (50.9%) patients in the AR group required further imaging during their admission compared to 14 (26.4%) in the LDCT group (P= 0.009). There was no difference in the median hospital LOS (3.84 days for AR versus 4.24 days for LDCT, P= 0.83).
Conclusion:âLDCT demonstrates a superior diagnostic yield over AR and reduces the number of subsequent imaging tests for a minimal cost in radiation exposure. However, there is no difference in the overall hospital LOS between the two imaging strategies
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