Effect of adding copper oxide nanoparticles on the mass/heat transfer in falling film absorption

Absorber is an essential component that affects the efficiency of absorption refrigeration unit. Falling film absorption is one of the most widespread forms of the heat/mass transfer in absorption system. In this paper, based on the software COMSOL Multiphysics, the finite element method is used to establish the model of falling film absorption. The falling film absorption properties of nanofluids was studied by adding CuO nanoparticles. The results reveal that as the film flow rate increases, the average mass transfer flux rises first and then decreases. The average mass transfer flux increases with the rise of the concentration of solution at the inlet, the decrease of the temperature of solution at the inlet and the reduction of cooling water inlet temperature. After adding copper oxide nanoparticles to lithium bromide solution, the vapor absorption performance of lithium bromide solution can be significantly improved

A practical graphitic carbon nitride (g-C₃N₄)based fluorescence sensor for the competitive detection of trithiocyanuric acid and mercury ions

[EN] A fluorescent sensor for the detection of trithiocyanuric acid (TCA) and Hg was developed based on competitive interactions: non-covalent stacking between g-CN and TCA vs coordinative interaction between TCA and Hg. Electrostatic simulations were used to evaluate the interactions and help describe the detection mechanism. Moreover, normalized 2D fluorescence contour plots have been used to understand the fluorescence phenomenon. When TCA was added into a g-CN nanosheet solution free of Hg, TCA interacted with g-CN nanosheets via hydrogen bonding and π-π interactions, resulting in fluorescence quenching of the g-CN nanosheets. However, upon the addition of Hg, the fluorescence of the TCA-g-CN nanosheet hybrid system was restored, due to coordination of Hg with TCA through the S atoms, breaking the TCA-g-CN stacking interaction. Our results provide a new approach for the design of multifunctional nanosensors suitable for the detection of environmental pollutants.The present work is supported by the National Natural Science Foundation of China (No. 21607044), the Natural Science Foundation of Hebei Province (No. B2017502069) and the Fundamental Research Funds for the Central Universities (No. 2018MS113). All data sup-porting this study are provided as supplementary information accom-panying this paper. T.D.J. wishes to thank the Royal Society for a Wolfson Research Merit Award

Microstructural characterizations of metallized Al2O3 before/after surface treatment and Al2O3/Cu soldered joint

Joining Al2O3 ceramics to Cu heat pipes should be conducted at low temperatures since Cu heat pipes may fail at temperatures higher than 320 °C. Due to the poor wettability of low-temperature solder on Al2O3 ceramics, it is essential to metallize Al2O3 ceramics before joining Al2O3 to Cu with a low-temperature solder. Surface metallization of Al2O3 has been conducted using Ag-Cu-Ti active metal filler at 900 °C. Microanalysis indicates that an interfacial reaction occurs between the active metal filler and the Al2O3, leading to the formation of a Cu3Ti3O reaction layer. The metal layer on the surface of Al2O3 is primarily composed of Ag (s, s) (solid solution), Cu (s, s) and Ti2Cu. The polishing treatment of the surface metal layer in metallized Al2O3 results in a reduction of the oxide content and contaminants, which subsequently allows joining at low temperature. Low-temperature joining of metallized Al2O3 to Cu has been carried out using Sn-Ag-Cu solder at 280 °C. The joining area of the joint includes a Cu3Ti3O reaction layer, a metal layer and a solder layer. The solder layer mainly consists of Sn (s, s), Ag3Sn and Cu6Sn5. The Al2O3/Cu joint fractures in the solder layer after the shearing test, indicating that the strength of the solder is relatively low. However, the interfacial bonding between the metallized Al2O3, solder layer and Cu base material is satisfactory

Soybean Breeding on Seed Composition Trait

Soybean is a most important crop providing edible oil and plant protein source for human beings, in addition to animal feed because of high protein and oil content. This review summarized the progresses in the QTL mapping, candidate gene cloning and functional analysis and also the regulation of soybean oil and seed storage protein accumulation. Furthermore, as soybean genome has been sequenced and released, prospects of multiple omics and advanced biotechnology should be combined and applied for further refine research and high-quality breeding

Intrinsic Electronic Structure and Nodeless Superconducting Gap of YBa2Cu3O7−δ\mathrm{YBa_{2} Cu_{3} O_{7-\delta} } Observed by Spatially-Resolved Laser-Based Angle Resolved Photoemission Spectroscopy

The spatially-resolved laser-based high resolution ARPES measurements have been performed on the optimally-doped $\mathrm{YBa_{2} Cu_{3} O_{7-\delta} }$ (Y123) superconductor. For the first time, we found the region from the cleaved surface that reveals clear bulk electronic properties. The intrinsic Fermi surface and band structures of Y123 are observed. The Fermi surface-dependent and momentum-dependent superconducting gap is determined which is nodeless and consistent with the d+is gap form

Nodal s± pairing symmetry in an iron-based superconductor with only hole pockets

The origin of high-temperature superconductivity in iron-based superconductors is still not understood; determination of the pairing symmetry is essential for understanding the superconductivity mechanism. In the iron-based superconductors that have hole pockets around the Brillouin zone centre and electron pockets around the zone corners, the pairing symmetry is generally considered to be s±, which indicates a sign change in the superconducting gap between the hole and electron pockets. For the iron-based superconductors with only hole pockets, however, a couple of pairing scenarios have been proposed, but the exact symmetry is still controversial. Here we determine that the pairing symmetry in KFe2As2—which is a prototypical iron-based superconductor with hole pockets both around the zone centre and around the zone corners—is also of the s± type. Our laser-based angle-resolved photoemission measurements have determined the superconducting gap distribution and identified the locations of the gap nodes on all the Fermi surfaces around the zone centres and the zone corners. These results unify the pairing symmetry in hole-doped iron-based superconductors and point to spin fluctuation as the pairing glue in generating superconductivity

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve