Electrolyte cation length influences electrosorption and dynamics in porous carbon supercapacitors
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catalysis (heterogeneous)↗
Engineering topics
Zhang, Yu
Publications and source records attributed to Zhang, Yu.
Understanding coastal wetland hydrology with a new regional‐scale, process‐based hydrological model
Abstract Coastal wetlands represent an ecotone between ocean and terrestrial ecosystems, providing important services, including flood mitigation, fresh water supply, erosion control, carbon sequestration, and wildlife habitat. The environmental setting of a wetland and the hydrological connectivity between a wetland and adjacent terrestrial and aquatic systems together determine wetland hydrology. Yet little is known about regional‐scale hydrological interactions among uplands, coastal wetlands, and coastal processes, such as tides, sea level rise, and saltwater intrusion, which together control the dynamics of wetland hydrology. This study presents a new regional‐scale, physically based, distributed wetland hydrological model, PIHM‐Wetland, which integrates the surface and subsurface hydrology with coastal processes and accounts for the influence of wetland inundation on energy budgets and evapotranspiration (ET). The model was validated using in situ hydro‐meteorological measurements and Moderate Resolution Imaging Spectroradiometer (MODIS) ET data for a forested and herbaceous wetland in North Carolina, USA, which confirmed that the model accurately represents the major wetland hydrological behaviours. Modelling results indicate that topographic gradient is a primary control of groundwater flow direction in adjacent uplands. However, seasonal climate patterns become the dominant control of groundwater flow at lower coastal plain and land–ocean interface. We found that coastal processes largely influence groundwater table (GWT) dynamics in the coastal zone, 300 to 800 m from the coastline in our study area. Among all the coastal processes, tides are the dominant control on GWT variation. Because of inundation, forested and herbaceous wetlands absorb an additional 6% and 10%, respectively, of shortwave radiation annually, resulting in a significant increase in ET. Inundation alters ET partitioning through canopy evaporation, transpiration, and soil evaporation, the effect of which is stronger in cool seasons than in warm seasons. The PIHM‐Wetland model provides a new tool that improves the understanding of wetland hydrological processes on a regional scale. Insights from this modelling study provide benchmarks for future research on the effects of sea level rise and climate change on coastal wetland functions and services.
Zhang, Yu↗
Polypeptides having endoglucanase activity and polynucleotides encoding same
The present invention relates to isolated polypeptides having endoglucanase activity and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
59 BASIC BIOLOGICAL SCIENCES↗
Impact of Building-Level Motor Protection on Power System Transient Behaviors
Transmission and distribution system level protection strategies have been extensively investigated to advise better coordination of physical protection devices. A diversity of functional motors with dedicated protection schemes are popularized in increasing number of commercial, residential and industrial buildings. This paper focuses on implementing several most popular protection schemes on Eletro-Magnetic Transient Program (EMTP) simulation for three-phase and single-phase induction motors that exist in commercial buildings connected to typical distribution feeders. Voltage depressions are played in at the head of the feeder fully loaded with functional induction motors to investigate the behaviors of single-phase motor stalling, the action of motor protection and reconnection, and the impacts of device-level protection on system-level dynamics. Several distribution feeders are represented in standard IEEE 39-bus transmission system to simulate fault-induced delayed voltage recovery (FIDVR) and explore mitigation strategies by optimally configuring the building-level motor protection settings.
Liu, Yuan↗
Plasmonic Hot-Carrier-Mediated Tunable Photochemical Reactions
Hot-carrier generation from surface plasmon decay has found applications in many branches of physics, chemistry, materials science, and energy science. Recent reports demonstrated that the hot carriers generated from plasmon decay in nanoparticles can transfer to attached molecules and drive photochemistry which was thought impossible previously. Here, we have computationally explored the atomic-scale mechanism of a plasmonic hot-carrier-mediated chemical process, H 2 dissociation. Numerical simulations demonstrate that, after photoexcitation, hot carriers transfer to the antibonding state of the H 2 molecule from the nanoparticle, resulting in a repulsive-potential-energy surface and H 2 dissociation. This process occurs when the molecule is close to a single nanoparticle. However, if the molecule is located at the center of the gap in a plasmonic dimer, dissociation is suppressed due to sequential charge transfer, which efficiently reduces occupation in the antibonding state and, in turn, reduces dissociation. An asymmetric displacement of the molecule in the gap breaks the symmetry and restores dissociation when the additional charge transfer is significantly suppressed. Furthermore, these models demonstrate the possibility of structurally tunable photochemistry via plasmonic hot carriers.
36 MATERIALS SCIENCE↗
Polypeptides having cellulolytic enhancing activity and polynucleotides encoding same
The present invention provides isolated polypeptides having cellulolytic enhancing activity and polynucleotides encoding the polypeptides. The invention also provides nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
59 BASIC BIOLOGICAL SCIENCES↗
Generation of Composite Load Protection Profiles for Reliable System Operation
A correct representation of the dynamic load is vital for power system planning and operation. In a composite load model, different motor types have different protection schemes. In addition, motor types vary significantly in different building type. Existing load models are inadequate to handle the growing importance of protective devices in buildings. This work proposed a methodology to generate composite protection profiles in one-hour interval in one year, for different commercial buildings in representative cities from different climate zones. This work can be used to develop the composite protection model, and to study the aggregated performance of the protection of all the motor loads in the composite load model.
protection model, Composite load model, Commercial↗
Impact of post-rainfall evaporation from porous roof tiles on building cooling load in subtropical China
Rainfall occurs frequently in subtropical regions of China, with the subsequent water evaporation from building roofs impacting the thermal performance and the energy consumption of buildings. In this paper, we proposed a novel simulation method using actual meteorological data to evaluate this impact. New features were developed in EnergyPlus to enable the simulation: (1) an evaporation latent heat flux source term was added to the heat balance equation of the external surface and (2) algorithms for the evaporative cooling module (ECM) were developed and implemented into EnergyPlus. The ECM experimental results showed good agreement with the simulated results. The ECM was used to assess the impact of evaporation from porous roof tiles on the cooling load of a one-floor building in subtropical China. The results show that the evaporation process decreased the maximal values of the external and internal roof surface temperatures by up to 6.4 °C and 3.2 °C, respectively, while the lower internal surface temperature decreased the room accumulated cooling load by up to 14.8% during the hot summer period. Lastly, the enhanced EnergyPlus capability can be used to evaluate the evaporative cooling performance of roofs with water-storage mediums, as well as to quantify their impact on building cooling loads.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Site-Specific Photodecomposition in Conjugated Energetic Materials
Nonadiabatic excited-state molecular dynamics (NEXMD) has been used to study photodecomposition in a class of recently synthesized bicyclic conjugated energetic materials (CEMs) composed of fused tetrazole and tetrazine derivatives with increasing oxygen substitutions. Modification by oxygen functionalization has already been demonstrated to increase the two-photon absorption intensity in the target CEMs while simultaneously improving oxygen balance. Photodecomposition mechanisms in materials that undergo nonlinear absorption could be used to achieve controlled, direct optical initiation. For this study, we use NEXMD simulations to model the nonradiative relaxation and photodecomposition in CEMs following photoexcitation by a simulated Nd:YAG laser pulse. Excess electronic energy is quickly converted into vibrational energy on a sub-100 fs time scale resulting in bond dissociation. We find that, for the studied tetrazine derivatives, the bicyclic framework is an important structural feature that enhances the photochemical quantum yield and the high atomic oxygen content increases the relaxation lifetime and opens additional photodissociation pathways targeting the oxygen-substituted sites. The presented analysis scheme based on bond orders in the swarm of NEXMD trajectories is a useful tool for determining photochemical reactions.
36 MATERIALS SCIENCE↗
Monitoring Ultrafast Spin Crossover Intermediates in an Iron(II) Complex by Broad Band Stimulated X-ray Raman Spectroscopy
Here, the photoinduced spin crossover dynamics of transition metal complexes is of fundamental scientific importance and is used for sensor device applications and solar energy harvesting. Current X-ray and optical spectroscopy experiments for [Fe II (bpy) 3 ], an archetypal earth-abundant metal complex, show conflicting spin dynamics. We have simulated the broad band transient X-ray absorption and hybrid (broad + narrow band) X-ray stimulated Raman signals at the N and Fe K-edges of the key excited state intermediates involved in the spin crossover process of this complex. We find that these signals are much more sensitive to electron and spin populations than transition absorption and may be useful in the design of photovoltaic and artificial photosynthetic systems.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Polypeptides having beta-xylosidase activity and polynucleotides encoding same
The present invention relates to isolated polypeptides having beta-xylosidase activity and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
Liu, Ye↗
Traditional Chinese medication Tongxinluo attenuates apoptosis in ox-LDL-stimulated macrophages by enhancing Beclin-1-induced autophagy
Highlights: • TXL attenuates ox-LDL-impaired apoptosis in THP-1 macrophages. • TXL attenuates ox-LDL-impaired apoptosis in THP-1 macrophages by enhancing autophagy. • TXL treatment inhibits macrophage apoptosis by enhancing macrophage autophagy in advanced atherosclerotic plaques. • TXL stabilizes atherosclerotic plaques by attenuating macrophage apoptosis and enhancing Beclin-1-induced autophagy. In advanced atherosclerosis, a large number of necrotic core increases plaque vulnerability, which leads to the occurrence of acute atherothrombotic cardiovascular events. Macrophage apoptosis plays an important role in secondary necrosis. The present study aimed to examine and describe the effect of the traditional Chinese medication Tongxinluo (TXL) on macrophage apoptosis in advanced atherosclerotic plaques and to explore its mechanism. By observing the effect of TXL on ox-LDL-stimulated macrophage apoptosis, it was shown that TXL significantly inhibited ox-LDL-induced apoptosis of macrophages by enhancing autophagy. Therapeutic mechanism of TXL included increasing the expression of Beclin-1 and improving the dissociation of Bcl-2-Beclin-1 Complex. Apolipoprotein E knockout (apoE−/−) mice with a high fat diet were divided into four groups: saline group (Saline gavage), low dose TXL group (0.38 g/kg/d, gavage), medium dose TXL group (0.75 g/kg/day, gavage), and high dose TXL group (1.5 g/kg/day, gavage). 4 weeks after carotid-artery surgery, lentiviral of Beclin-1 silencing was injected through the tail vein. TXL treatment significantly reduced macrophage apoptosis dose-dependently and the result was blocked by Beclin-1 silencing. In addition, the increased Lc3b dots by TXL almost localized to macrophages in advanced atherosclerotic plaque. Compared with the same dose of TXL shBeclin-1 group, plaque area and vulnerability index of TXL groups decreased. The anti-apoptosis effects of TXL on atherosclerosis was related to the improvement of autophagy via Beclin-1.
60 APPLIED LIFE SCIENCES↗
Recirculating Th2 cells induce severe thymic dysfunction via IL-4/STAT6 signaling pathway
Highlights: • Th2 cell is the most powerful factor in the inhibition of T cell development. • The effect caused by Th2 cells is principally due to the direct action of IL-4. • IL-4/STAT6 signaling is a major contributor to the ruins of T cell development. • The effect has a positive significance associated with thymic involution. Thymic involution happened early in life, but a certain ratio of activated CD4{sup +} T cells will persistently recirculate into the thymus from the periphery and it have been suggested to be able to inhibit the development of embryonic thymocytes. Our present study was aimed to elucidate the specific mechanism how activated CD4{sup +} T cells could influence upon developing thymocytes by using fetal thymic organ culture (FTOC) and kidney capsule transplantation. Our results demonstrated that Th2 cells were found to play a fundamental role in the inhibition of embryonic thymocyte development since a very low concentration of Th2 cells could obviously reduce the total number of thymocytes. And this effect was not tenable in other Th cell type. Notably, IL-4, the major cytokine secreted by Th2 cells, was suggested the key factor playing the inhibition role. In addition to reduced cell population, the proportion of double positive (DP) T cells was also heavily decreased. Furthermore, we demonstrated that it was the downstream effector signal transducer and activator of transcription 6 (STAT6) of IL-4 partially manipulate this inhibition. Together, these findings reveal a novel influence of Th2 cells re-entering the thymus on thymic involution.
60 APPLIED LIFE SCIENCES↗
Stark control of electrons along nanojunctions
Ultrafast control of currents on the nanoscale is essential for future innovations in nanoelectronics. Recently it was experimentally demonstrated that strong non-resonant few-cycle 4 fs laser pulses can be used to induce phase-controllable currents along gold–silica–gold nanojunctions in the absence of a bias voltage. However, since the effect depends on a highly non-equilibrium state of matter, its microscopic origin is unclear and the subject of recent controversy. Here we present atomistically detailed (time-dependent non-equilibrium Green’s function) electronic transport simulations that recover the main experimental observations and offer a simple intuitive picture of the effect. The photoinduced currents are seen to arise due to a difference in effective silica-metal coupling for negative and positive field amplitudes induced by lasers with low temporal symmetry. These insights can be employed to interpret related experiments, and advance our ability to control electrons in matter using lasers.
Science & Technology - Other Topics↗
Microstructure and mechanical performance of welded joint between a novel heat-resistant steel and Inconel 617 weld metal
Highlights: • MGBs were suspected as the DDC crack source during high-temperature tensile test. • Microhardness variations in different passes of joint denote grain refinement effect induced by the multi-pass welds. • After tensile test, changes in microhardness can be attributed to the extent of deformation and amount of precipitation. - Abstract: In the present study, the microstructure and mechanical performance of a tungsten inert gas welded joint between a novel heat-resistant austenitic steel and Inconel 617 weld metal were examined. Migrated grain boundaries were discovered more frequently in the lower portion of the weld metal that solidifies in austenite type. Ti-rich precipitates were observed in weld metal and Cr-rich and Nb-rich precipitates were observed in base metal. The fusion boundary area had the lowest impact toughness due to the large non-homogeneity of the microstructure. Microhardness profiles of the joint were obtained and the backing passes were found to produce the highest microhardness values, which was caused by the grain refinement effect. Ductile failure with slipping separation occurred in those joints ruptured after tensile tests at both room temperature and 923 K. In addition, multiscale precipitates in the joint after high-temperature tensile tests were inspected, where it was found that nanoscale particles contributed to the high-temperature resistance of the joint. Furthermore, microhardness changes in the joint after tensile tests were analysed according to the precipitation and strain-hardening mechanism.
36 MATERIALS SCIENCE↗
Comparison of Two Methods for Estimating the Sampling-Related Uncertainty of Satellite Rainfall Averages Based on a Large Radar Data Set
The uncertainty of rainfall estimated from averages of discrete samples collected by a satellite is assessed using a multi-year radar data set covering a large portion of the United States. The sampling-related uncertainty of rainfall estimates is evaluated for all combinations of 100 km, 200 km, and 500 km space domains, 1 day, 5 day, and 30 day rainfall accumulations, and regular sampling time intervals of 1 h, 3 h, 6 h, 8 h, and 12 h. These extensive analyses are combined to characterize the sampling uncertainty as a function of space and time domain, sampling frequency, and rainfall characteristics by means of a simple scaling law. Moreover, it is shown that both parametric and non-parametric statistical techniques of estimating the sampling uncertainty produce comparable results. Sampling uncertainty estimates, however, do depend on the choice of technique for obtaining them. They can also vary considerably from case to case, reflecting the great variability of natural rainfall, and should therefore be expressed in probabilistic terms. Rainfall calibration errors are shown to affect comparison of results obtained by studies based on data from different climate regions and/or observation platforms.
Lau, William K. M.↗