Mechanism of micro-wetting of highly hydrophobic coal dust in underground mining and new wetting agent development

The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.

Unraveling the role of iron on Ni-Fe alloy nanoparticles during the electrocatalytic ethanol-to-acetate process

The anodic electrooxidation of ethanol to value-added acetate is an excellent example of replacing the oxygen evolution reaction to promote the cathodic hydrogen evolution reaction and save energy.Herein,we present a colloidal strategy to produce Ni-Fe bimetallic alloy nanoparticles(NPs)as efficient electrocatalysts for the electrooxidation of ethanol in alkaline media.Ni-Fe alloy NPs deliver a current density of 100 mA·cm^(-2) in a 1.0 M KOH solution containing 1.0 M ethanol merely at 1.5 V vs.reversible hydrogen electrode(RHE),well above the performance of other electrocatalysts in a similar system.Within continuous 10 h testing at this external potential,this electrode is able to produce an average of 0.49 mmol·cm^(-2)·h^(-1) of acetate with an ethanol-to-acetate Faradaic efficiency of 80%.A series of spectroscopy techniques are used to probe the electrocatalytic process and analyze the electrolyte.Additionally,density functional theory(DFT)calculations demonstrate that the iron in the alloy NPs significantly enhances the electroconductivity and electron transfer,shifts the rate-limiting step,and lowers the energy barrier during the ethanol-to-acetate reaction pathway.

Enhancing alkaline water oxidation with NiFe alloy-encapsulated nitrogen-doped vertical graphene array

Advancing efficient and affordable electrocatalysts to boost the oxygen evolution reaction(OER)is pivotal for sustainable green hydrogen production.Herein,we propose the fabrication of nickel-iron alloy nanoparticles-encapsulated on N-doped vertically aligned graphene array on carbon cloth(NiFe@NVG/CC)as a highly active three-dimensional(3D)catalyst electrode for OER.In 1 M KOH,such NiFe@NVG/CC demonstrates outstanding catalytic performance,necessitating merely overpotential of 245 mV for achieving a current density of 10 mA·cm^(−2),a remarkably low Tafel slope of 36.2 mV·dec^(−1).Furthermore,density functional theory calculations validate that the incorporate of N species into graphene can reinforce the electrocatalytic activity though reducing the reaction energy barrier during the conversion of*O to*OOH intermediates.The outstanding performance and structural benefits of NiFe@NVG/CC offer valuable insights for the development of innovative and efficient electrocatalysts for water oxidation.

青少年脊柱侧凸患者生活质量的现状调查

目的分析人口学参数和脊柱畸形测量参数间青少年脊柱侧凸(adolescent scoliosis,AS)患者在脊柱侧凸研究学会-22(scoliosis researth society-22,SRS-22)量表中疼痛、自我形象、功能状况和心理状况各维度得分的差异性及与之的相关性,了解AS患者的生活质量现状。方法收集2021年3月至2021年9月于昆明医科大学第二附属医院和云南(中德)骨科医院就诊的AS患者103例并完成SRS-22量表问卷,整理归纳所有研究对象的人口学资料和脊柱畸形测量数据,通过独立样本t检验、单因素方差分析、相关性分析SRS-22量表各维度得分间的差异性及与之的相关性。结果单弯与三弯、双弯与三弯在SRS-22量表功能状况维度上,差异有统计学意义(P<0.05);胸弯与双弯患者在SRS-22量表自我形象维度上,差异有统计学意义(P<0.05);胸弯与胸腰弯患者、胸弯与双弯患者在SRS-22量表心理状况维度上,差异有统计学意义(P<0.05);年龄与疼痛维度得分呈负相关(r=-0.328,P=0.000);主弯Cobb角分别与自我形象和心理状况维度得分呈负相关(r=-0.292,P=0.003;r=-0.203,P=0.039);顶椎旋转度分别与自我形象和心理状况维度得分呈负相关(r=-0.295,P=0.003;r=-0.236,P=0.017)。结论年龄越大,AS患者的疼痛程度越严重;主弯顶椎位置不同的AS患者其自我形象感受也不同,顶椎位置越靠近胸段的个体,自我形象感受越糟糕;同时主弯Cobb角和顶椎旋转度越严重,AS患者的自我形象感受越差;不同的侧弯数量会造成个体的功能状况不同,侧弯曲线数量为三弯的患者功能状况感知最不佳;主弯Cobb角和顶椎旋转度越严重的患者,心理状况也最不良;因此了解AS患者的生活质量很有必要,相关工作人员需要根据不同情况的个体给予相对应的个性化治疗。

Hierarchical platinum–iridium neural electrodes structured by femtosecond laser for superwicking interface and superior charge storage capacity

The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy for the platinum–iridium(Pt–Ir)electrode to optimize electrochemical performance and wettability.A series of surface micro/nano structures were fabricated on Pt–Ir electrodes with different combinations of four adjustable laser-processing parameters.Subsequently,the electrodes were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and wetting behavior.The results show that electrode performance strongly depends on the surface morphology.Increasing scanning overlap along with moderate pulse energy and the right number of pulses leads to enriched surface micro/nano structures and improved electrode performance.It raises the maximum charge storage capacity to 128.2 mC/cm^(2) and the interface capacitance of electrodes to 3.0×10^(4)μF/cm^(2) for the geometric area,compared with 4.6 mC/cm^(2) and 443.1μF/cm2,respectively,for the smooth Pt–Ir electrode.The corresponding optimal results for the optically measured area are 111.8 mC/cm^(2) and 2.6×10^(4)μF/cm^(2),which indicate the contribution of fner structures to the ablation profle.The hierarchical structures formed by the femtosecond laser dramatically enhanced the wettability of the electrode interface,giving it superwicking properties.A wicking speed of approximately 80 mm/s was reached.Our optimization strategy,leading to superior performance of the superwicking Pt–Ir interface,is promising for use in new neural electrodes.

Constitutive parameters identification of thermal barrier coatings using the virtual fields method

Thermal barrier coatings (TBCs) are widely applied in thermal components to protect metallic components. Owing to the complex layered structure of TBCs and difficult preparation of coating, the mechanical characterization of TBCs should be of primary importance. With regard to TBCs, this study deals with the constitutive parameters identification of bi-material. Considering the complex construction and boundary of bi material, the virtual fields method (VFM) was employed in this study. A methodology based on the optimized virtual fields method combined with moire interferometry was proposed for the constitutive parameters identification of bi-material. The feasibility of this method is verified using simulated deformation fields of a two-layer material subjected to three point ben ding loading. As an application, the deformation fields of the TBC specimens were measured by moire interferometry. Then, lhe mechanical parameters of the coating were identified by the proposed method. The identification results indicate that Young's modulus of the TBC top coating is 89.91 GPa, and its Poisson's ratio is 0.23.

High-performance flexural fatigue of carbon nanotube yarns

Carbon nanotube yarns(CNTY)possess good specific strength and specific conductivity.As such,their potential for commercial applications is significant.Fatigue performance is a significant consideration in yarn/wire applications.In this study,the flexural fatigue performance of CNTY spun from super-aligned carbon nanotube arrays was investigated using a reversed bending test.The results showed that CNTY exhibited excellent resistance to pure flexural fatigue,significantly outperforming stainless steel wire;CNTY failed where a combination of flexural fatigue and tension–tension fatigue had special hollow fracture morphology,and CNTY resistance remained fundamentally unchanged in the combination fatigue process.

Chronically monitoring the deep brain rhythms: from stimulation to recording

Humans have never stopped exploring their brains,one of the most complex systems in nature.A thorough understanding of the brain is the ultimate challenge for neuroscientists.As there is a rapid increase in the aging populations and the number of brain disorders,researchers are much more eager to clarify how the billions of

Electrochemical and biological performance of hierarchical platinum-iridium electrodes structured by a femtosecond laser

Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies.The recently proposed hierarchical platinum-iridium(Pt-Ir)electrodes produced by femtosecond lasers have exhibited superior electrochemical performance in vitro,but their in vivo performance is still unclear.In this study,we explored the electrochemical performance,biological response,and tissue adhesion of hierarchical Pt-Ir electrodes by implantation in adult rat brains for 1,8,and 16 weeks.Regular smooth Pt-Ir electrodes were used as a control.The results showed that the electrochemical performance of both electrodes decreased and leveled off during implantation.However,after 16 weeks,the charge storage capacity of hierarchical electrodes stabilized at~16.8 mC/cm^(2),which was 15 times that of the smooth control electrodes(1.1 mC/cm^(2)).Moreover,the highly structured electrodes had lower impedance amplitude and cutoff frequency values.The similar histological response to smooth electrodes indicated good biocompatibility of the hierarchically structured Pt-Ir electrodes.Given their superior in vivo performance,the femtosecond laser-treated Pt-Ir electrode showed great potential for neuromodulation applications.

A brief overview of the School of Aerospace Engineering of Tsinghua University

This article provides a brief overview of the teaching and research at the School of Aerospace Engineering(SAE) to celebrate the 80 th anniversary of the establishment of aeronautics as a discipline at Tsinghua University. The evolution of the school, undergraduate/graduate students and faculty members, and research activities and achievements have been described. The research input including research funding and research projects are summarized, showing a diversity of funding sources and a significant growth in either sum total or spending per researcher. The achievements including publications and inter/national academic awards are also introduced. It can be seen that the level of academic publications has been growing over the past decades. In addition,four representative research achievements have been briefly described to show the scientific contributions of the school.

Surface-derived phosphate layer on NiFe-layered double hydroxide realizes stable seawater oxidation at the current density of 1 A·cm^(−2)

Seawater electrolysis,especially in coastlines,is widely considered as a sustainable way of making clean and high-purity H2 from renewable energy;however,the practical viability is challenged severely by the limited anode durability resulting from side reactions of chlorine species.Herein,we report an effective Cl^(−) blocking barrier of NiFe-layer double hydroxide(NiFe-LDH)to harmful chlorine chemistry during alkaline seawater oxidation(ASO),a pre-formed surface-derived NiFe-phosphate(Pi)outerlayer.Specifically,the PO_(4)^(3−)-enriched outer-layer is capable of physically and electrostatically inhibiting Cl−adsorption,which protects active Ni^(3+)sites during ASO.The NiFe-LDH with the NiFe-Pi outer-layer(NiFe-LDH@NiFe-Pi)exhibits higher current densities(j)and lower overpotentials to afford 1 A·cm^(−2)(η1000 of 370 mV versusη1000 of 420 mV)than the NiFe-LDH in 1 M KOH+seawater.Notably,the NiFe-LDH@NiFe-Pi also demonstrates longer-term electrochemical durability than NiFe-LDH,attaining 100-h duration at the j of 1 A·cm^(−2).Additionally,the importance of surface-derived PO_(4)^(3−)-enriched outer-layer in protecting the active centers,γ-NiOOH,is explained by ex situ characterizations and in situ electrochemical spectroscopic studies.

Cauliflower-like Ni_(3)S_(2) foam for ultrastable oxygen evolution electrocatalysis in alkaline seawater

It is of great importance to design and develop electrocatalysts that are both long-lasting and efficient for seawater oxidation.Herein,a three-dimensional porous cauliflower-like Ni_(3)S_(2) foam on Ni foam(Ni_(3)S_(2) foam/NF)is proposed as a high-performance electrocatalyst for the oxygen evolution reaction in alkaline seawater.The as-synthesis Ni_(3)S_(2) foam/NF achieves exceptional efficacy,achieving a current density of 100 mA·cm^(−2)at mere overpotential of 369 mV.Notably,its electrocatalytic stability extends up to 1000 h at 500 mA·cm^(−2).

Ambient electrosynthesis of urea from carbon dioxide and nitrate over Mo_(2)C nanosheet

Electrocatalytic synthesis of urea through C-N bond formation,converting carbon dioxide(CO_(2))and ni-trate(NO 3-),presents a promising,less energy-intensive alternative to industrial urea production process.In this communication,we report the application of Mo_(2)C nanosheets-decorated carbon sheets(Mo_(2)C/C)as a highly efficient electrocatalyst for facilitating C-N coupling in ambient urea electrosynthesis.In CO_(2)-saturated 0.2 mol/L Na_(2)SO_(4)solution containing 0.05 mol/L NO 3-,the Mo_(2)C/C catalyst achieves an impres-sive urea yield of 579.13μg h^(-1)mg^(-1)with high Faradaic efficiency of 44.80%at-0.5 V versus the reversible hydrogen electrode.Further theoretical calculations reveal that the multiple Mo active sites enhance the formation of∗CO and∗NH_(2)intermediates and facilitate their C-N coupling.This research propels the use of Mo_(2)C-based electrodes in electrocatalysis and accentuates the capabilities of binary metal-based catalysts in C-N coupling reactions.