Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents.Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions.In this study,the composition and content of liquefied solvents were analyzed.As model compounds,hexadecane,toluene,naphthalene,tetrahydronaphthalene,and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic,bicyclic,and tricyclic aromatic hydrocarbons.The solubility of hydrogen X(mol/mol)in pure solvent components and mixed solvents(alkanes and aromatics mixed in proportion to the chain alkanes+bicyclic aromatic hydrocarbons,bicyclic saturated aromatic hydrocarbons+bicyclic aromatic hydrocarbons,and bicyclic aromatic hydrocarbons+compounds containing het-eroatoms composed of mixed components)are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa.The results demonstrated that at high temperatures and pressures,the solubility of hydrogen in the solvent increases with the increase in temperature and pressure,with the pressure having a greater impact.Further-more,the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents,and the solubility of eicosanoids reaches a maximum of 0.296.The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number.The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons.The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents.Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Characterization of local chemical ordering and deformation behavior in high entropy alloys by transmission electron microscopy

Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed compositions,and varied locations.Transmission electron microscopy(TEM)as well as its aberration correction techniques are powerful for characterizing SROs in these compositionally complex alloys.In this short communication,we summarized recent progresses regarding characterization of SROs using TEM in the field of HEAs.By using advanced TEM techniques,not only the existence of SROs was confirmed,but also the effect of SROs on the deformation mechanism was clarified.Moreover,the perspective related to application of TEM techniques in HEAs are also discussed.

Detection of the expression of heat shock protein 70 using quantum dots as fluorescence probe in human renal carcinoma

Objective： To detect the expression of heat shock protein 70 （HSP70） in human renal carcinoma tissues and cultured ACHN cells by using quantum dots-tagged fluorescence technology and its significance. Methods： Using the fluorescence property of quantum dots, indirect immunofluorescence method and immunocytochemical method were used to detect the expression of HSP70 tagged by quantum dots in renal carcinoma tissues and ACHN cells cultured in vitro. Results： Confocal fluorescence microscopy showed that HSP70 were significantly expressed in renal carcinoma tissues and ACHN cells cultured in vitro characterized by homogeneous distribution of intensive salmon pink fluorescence. Compared with FITC tagging, quantum dots tagged fluorescence had good specificity and signal to background. There was no notable quenching after excitation by quantum dots for 30 rain. Conclusion： Quantum dots can be used to label subcellular proteins and have obvious advantages compared with the traditional fluorescence methods. The quantum dots-tagged fluorescence could be applied as a new method for clinical labeling detection.

H-TOSSIM: Extending TOSSIM with Physical Nodes

As the development of Wireless Sensor Network (WSN), software testing for WSN-based applications be-comes more and more important. Simulation testing is an important approach to WSN-based software testing, and TOSSIM is the most widely used simulation testing tool targeted at TinyOS which is the most popular operating system nowadays. However, simulation testing tools such as TOSSIM can not reveal program er-rors about communication detail or timing, and lack accurate power consumption model and even can not support power consumption estimation. In this paper, a hybrid testbed H-TOSSIM is proposed, which ex-tends TOSSIM with physical nodes. H-TOSSIM uses three physical nodes, of which, one shares the simu-lated environment with all virtual nodes to test the WSN program, and the other two bridge the real world and the simulated environment. H-TOSSIM combines the advantages of both the simulation in physical node and the simulation testing tools in WSN software testing. Through experiments, we show that H-TOSSIM really reveals program errors which the pure simulation testing can not capture, and can support power con-sumption estimation for large WSN with high accuracy and low hardware cost.

In Situ Analysis of Tobacco Leaves Based on Microwave Plasma Torch Desorption Ionization Mass Spectrometry

Tobacco is an important economic crop worldwide.Tobacco leaves contain a large number of natural products.Therefore,the analysis of tobacco composition is crucial for the control of tobacco safety and quality assessment.Microwave plasma torch desorption ionization mass spectrometry(MPT-MS) is an emerging ambient mass spectrometry(AMS) technique that can be used for rapid real-time analysis of s amples without pretreatment.Our work focuses on the chemical composition analysis of tobacco using MPT-MS,and 14 compounds were detected in green flue-cured tobacco leaves,while 30 compounds were detected in cured flue-cured tobacco leaves,which confirms that curing can enhance the flavor of cigarettes.Furthermore,we successfully in situ identified characteristic fragment ions of α/β-CBD(α/β-cembranoids),an important aroma compound in tobacco by MPT-MS.The results demonstrate the capability of MPT-MS for in situ analysis of tobacco components and its potential for evaluating tobacco quality.

Experimental research on aero-propulsion coupling characteristics of a distributed electric propulsion aircraft

Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section,we built a DEP demonstrator with 24"high-lift"Electric Ducted Fans(EDFs)distributed along the wing’s trailing edge.This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed,throttle,and EDF mounting surface deflection angles using a series of wind tunnel tests.We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15-25 m/s freestream flow and angles of attack from-4°to 16°.The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration.The results show that the EDFs can produce significant lift increment and drag reduction simultaneously,which is accordant with the potential benefit of Boundary Layer Ingestion(BLI)at low airspeed.

Visible Light-Driven Catalyst-Free Amination of Indoles Initiated by Electron Donor-Acceptor Complexes

The visible light-driven C2 or C3 amination of indoles without any additives was initiated via electron donor-acceptor (EDA) complex formed by indole and N-aminopyridinium salt.This method was compatible with a wide range of substrates and could proceed smoothly without the addition of any photocatalysts,transition-metal catalysts,or bases.A variety of studies were carried out to examine the presence of EDA complex.

Pd-Ni-P非晶合金多形性转变的成分依赖性

非晶合金复杂的化学成分特征为理解多形性转变带来了巨大挑战.在本文中,我们系统研究了(PdNi)_(100−x)P_(x)(15 at%<x<21 at%)非晶合金中加热诱导多形性转变的化学成分依赖性.差热分析与结构因子的演化规律表明重入型玻璃转变会随着P含量的增加(不超过17 at%)而逐渐被抑制,扩展X射线吸收精细结构分析拟合后的结构参数与原位升温同步辐射结果显示重入型玻璃转变的成分依赖性来源于金属–类金属键对(即Pd/Ni–P对)的成键能力差异以及由此导致的短程至中程有序化转变.这种成分依赖性可以导致重入型液-液转变和玻璃转变在Pd_(41.5)Ni_(41.5)P_(17)非晶合金中均可发生.本研究有助于加深对重入型玻璃转变原子机制的认识,同时澄清了对于Pd–Ni–P非晶合金体系中多形性转变结构起源的困惑.

Circulating current suppression for ground tied variable frequency to constant frequency converter system in aircraft

This paper presents a solution to the circulating current fault of aircraft power supply.The DC-link type Variable Frequency to Constant Frequency(VFCF)converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply.Due to the requirement of aircraft standards,both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft.With such a tied ground,the DC bus voltage rises greatly,and a large circulating current appears in the casing as the ground,which leads to equipment failure and potential safety hazards.According to the existing methods of circulating current fault suppression,this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods.Therefore,a Common-Mode(CM)choke-based method is proposed to provide a high impedance in the path of the CM circulating current.By doing so,the circulating current can be suppressed without the additional burden of the hardware and control algorithm,which is quite friendly for quality control of mass-production aircraft.Moreover,a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke,which saves the weight of passive devices to the greatest extent.Finally,simulation and experimental results are studied to verify the effectiveness of the proposed method.

Effects of trace elements on mechanical properties of the TiZrHfNb high-entropy alloy

Refractory high-entropy alloys have great potential to be utilized as high-temperature materials,and the repeatability and reproducibility of their mechanical properties are critical for practical applications.In this work,nevertheless,we found that the mechanical properties of the TiZrHfNb HEA greatly varied with the content of impurities in the samples even using high-purity raw materials.Specifically,the oxygen impurity is mainly responsible for the increment of the yield stress due to the strong interstitial hardening effect,whilst the ductility deterioration closely associates with the content of metalloid elements B,C,and Si.Our analysis reveals that the metalloid elements not only tend to segregate at grain boundaries but also enhance the aggregation of Zr and Ti.Such co-segregation induced the formation of strong(Zr,Ti)-metalloid bonds,resulting in grain boundary embrittlement and brittle fracture.Our current work demonstrates that the impurity contents in refractory HEAs need to be strictly controlled during production in order to improve their stability of mechanical performance.

State of art on energy management strategy for hybrid-powered unmanned aerial vehicle

New energy sources such as solar energy and hydrogen energy have been applied to the Unmanned Aerial Vehicle(UAV), which could be formed as the hybrid power sources due to the requirement of miniaturization, lightweight, and environmental protection issue for UAV. Hybrid electrical propulsion technology has been used in UAV and it further enforces this trend for the evolution to the Hybrid-Powered System(HPS). In order to realize long endurance flight mission and improve the energy efficiency of UAV, many researching works are focused on the Energy Management Strategy(EMS) of the HPS with digital simulation, ground demonstration platforms and a few flight tests for the UAV in recent years. energy management strategy, in which off-line or on-line control algorithms acted as the core part, could optimize dynamic electrical power distribution further and directly affect the efficiency and fuel economy of hybrid-powered system onboard.In order to give the guideline for this emerging technology for UAV, this paper presents a review of the topic highlighting energy optimal management strategies of UAV. The characteristics of typical new energy sources applied in UAV are summarized firstly, and then the classification and analysis of the architecture for hybrid power systems in UAV are presented. In the context of new energy sources and configuration of energy system, a comprehensive comparison and analysis for the state of art of EMS are presented, and the various levels of complexity and accuracy of EMS are considered in terms of real time, computational burden and optimization performance based on the optimal control and operational modes of UAV. Finally, the tendency and challenges of energy management strategy applied to the UAV have been forecasted.

A fast arc fault detection method for AC solid state power controllers in MEA

Arc fault detection is desperately required in Solid State Power Controllers（SSPC） in addition to their fundamental functions because arcs will provoke growing harm and threat to aircraft safety. Experimental study has been done to obtain the faulted current data. In order to improve the detection speed and accuracy, two fast arc fault detection methods have been proposed in this paper with the analysis of only half cycle data. Both Fast Fourier Transform（FFT） and Wavelet Packets Decomposition（WPD） have been adopted to distinguish arc fault currents from normal operation currents. Analysis results show that Alternating Current（AC） arcs can be effectively and accurately detected with the proposed half cycle data based methods. Moreover,experimental verification results have also been provided.

N-doped defective carbon with trace Co for efficient rechargeable liquid electrolyte-/all-solid-state Zn-air batteries

Simple synthesis of multifunctional electrocatalysts with plentiful active sites from earth-abundant materials is especially fascinating. Here, N-doped defective carbon with trace Co （1.5 wt%） was prepared via a scalable one pot solid pyrolysis process. The sample exhibits efficient bifunctional OER/ORR activiW in alkaline, mainly ascribed to the unique micro-mesoporous structure （1-3 nm）, high population of graphitic-N doping （up to 49.0%）, abundant defects and the encapsulated Co nanoparticles with graphitized carbon. The according rechargeahle liquid Zn-air batteries showed excellent performance （maximum power density of 154.0 mWcm-2： energy density of 773Wh kg -1 at 5 mAcm 2 and charging-discharging cycling stability over 100 cycles）. As a proof-of-concept, the flexible, rechargeable all-solid-state Zn-air batteries were constructed, and displayed a maximum power density as high as 45.9 mW cm 2 among the top level of those reported previously.

Value sharing of meromorphic functions and some questions of Dyavanal

In this paper, we shall study the uniqueness problems on meromorphic functions sharing nonzero finite value or fixed point. We have answered some questions posed by Dyavanal. Our results improve or generalize a few of known results.

Compressive surface strained atomic-layer Cu2O on Cu@Ag nanoparticles

Control of surface structure at the atomic level can effectively tune catalytic properties of nanomaterials.Tuning surface strain is an effective strategy for enhancing catalytic activity;however,the correlation studies between the surface strain with catalytic performance are scant because such mechanistic studies require the precise control of surface strain on catalysts.In this work,a simple strategy of precisely tuning compressive surface strain of atomic-layer Cu2O on Cu@Ag (AL-Cu2O/Cu@Ag) nanoparticles (NPs) is demonstrated.The AL-Cu2O is synthesized by structure evolution of Cu@Ag core-shell nanoparticles,and the precise thickness-control of AL-Cu2O is achieved by tuning the molar ratio of Cu/Ag of the starting material.Aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) and EELS elemental mapping characterization showed that the compressive surface strain of AL-Cu2O along the [111] and [200] directions can be precisely tuned from 6.5% to 1.6% and 6.6% to 4.7%,respectively,by changing the number of AL-Cu2O layer from 3 to 6.The as-prepared AL-Cu2O/Cu@Ag NPs exhibited excellent catalytic property in the synthesis of azobenzene from aniline,in which the strained 4-layers Cu2O (4.5% along the [111] direction,6.1% along the [200] direction) exhibits the best catalytic performance.This work may be beneficial for the design and surface engineering of catalysts toward specific applications.

Micellar Catalysis:Visible-Light Mediated Imidazo[1,2-a]pyridine C—H Amination with N-Aminopyridinium Salt Accelerated by Surfactant in Water

A light-promoted metal-free protocol for the amination of imidazo[1,2-a]pyridines with N-aminopyridinium salt by the assistance of surfactants in water was reported,charactering mild and environmentally benign conditions,as well as great functional group tolerance.Micelles with negatively charged polar surface and hydrophobic core formed from sodium dodecyl sulfate serve as an ideal medium for visible-light mediated radical reaction of cationic pyridine salt and imidazo[1,2-a]pyridine in aqueous phase.The electrostatic interaction between positively charged N-aminopyridinium and negatively charged surface of micelles is of great significance in this method.

Experimental study on the space charge properties in haze events

In recent years,haze has posed a serious threat to the global climate change,ecological balance and human health.In this study,the laboratory experiments and field observations were performed and a possible charging mechanism was proposed to investigate the space charge properties in haze events.The laboratory experiments showed that the charge polarity of primary aerosol is determined by species of combustion fuels while the magnitude is dependent on the combustion completeness.The field observations revealed that the space charge of atmosphere aerosol in haze events differs from that of fair weather and is closely related to PM2.5 concentration when Relative Humidity(RH)<60%,with 1 to 2 orders of magnitude less than the case when RH≥60%.The analysis of equivalent chargeto-mass ratio(ECTM)suggested that in haze events the space charge is governed by primary aerosol emitted by combustion of fossil fuel in a low relative humidity,whereas it is manipulated by the secondary chemical reaction of atmosphere aerosol in a high relative humidity.And we can identify the main pollutants in haze events according to the polarity of atmosphere aerosol and quickly take measures when RH<60%.Accordingly,the dusthaze of RH<80% can be divided into dry-dust-haze when RH<60%and wet-dust-haze when 60%≤RH<80%.Our study firstly elucidated the space charge properties of atmosphere aerosol in haze events and can provide a new perspective for the prevention and control of air pollution.

On-chip bias circuit for W-band silicon–germanium power amplifier

The performance of the power amplifier determines the detection capability of 77 GHz automotive radar, and the bias circuit is one of the most important parts of a silicon-germanium power amplifier. In this paper,we discussed and designed an on-chip bias circuit based on a silicon-germanium heterojunction bipolar transistor,which is used for the W-band silicon-germanium power amplifier. Considering the low breakdown voltage and the correlation between characteristic frequency and bias current density of the silicon-germanium heterojunction bipolar transistor, the bias circuit is designed to improve the breakdown voltage of the power amplifier and meet the W band characteristic frequency at the same time. The simulation results show that the designed bias circuit can make the amplifier operate normally from-40 to 125 ℃. In addition, the output power and smooth controllability of the power amplifier can be adjusted by controlling the bias circuit.

Global research on artificial intelligence in thyroid-associated ophthalmopathy:A bibliometric analysis

Purpose:To provide an overview of global publications on artificial intelligence(AI)in thyroid-associated oph-thalmopathy(TAO)through bibliometric analysis.Methods:Publications related to AI in TAO from inception until April 2023 were retrieved from the Web of Science database.The trends of publications and citations,publishing performance,collaboration among countries and institutions,and the funding agencies,relevant research domains,leading journals,hotspots and their evolution were identified.Results:A total of 55 publications were included for analysis.The number of publications and citations continued to grow since 1998,with a significant acceleration of growth after 2020.China is the most productive country with the highest number of productive institutions,followed by the United States.European countries have the most extensive collaboration.The most relevant research domain was radiology,nuclear medicine&medical imaging.The European Journal of Radiology was one of the most productive journals,with the most influential articles published."Thyroid-associated ophthalmopathy"and"neural network"maintain hotspots during the entire period.Studies were more focused on clinical features during 1998 and 2016,clinical features and medical data during 2017 and 2020,and medical data and AI techniques during 2021 and 2023.Conclusions:This study summarized the global research status regarding AI in TAO in terms of trends,countries,institutions,research domains,journals,and key topics.AI has shown great potential in TAO.Sponsored by funding agencies such as NSFC,China has become the most productive country in the field of AI in TAO.Our findings help researchers better understand the development of this field and provide valuable clues for future research directions.