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Enhancement of catalytic activity for hydrogenation of nitroaromatic by anionic metal-organic framework

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Chinese Chemical Letters 2024年第3期35卷 144-148页

作者： Qi Wu Anyang Li Ruibo He Yaxi Wu lei hou Guoping Yang Wenyan Zhang Yao-Yu Wang Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry&Materials ScienceNorthwest UniversityXi'an 710127China

Nitroaromatic hydrogenation catalysis without precious metals remains a longstanding challenge.The rate of electron transfer is the crucial factor affecting hydrogenation catalysis.Herein,an ionic Cd-based metal-organic framework(I-Cd-MOF)exhibiting a unique structure with one-dimensional(1D)opening nanochannels and good electron transfer ability was synthesized for catalyzing hydrogenation of 4-nitrophenol(4-NP).The catalytic activity of the unique I-Cd-MOF without noble metals is detected,which is higher than most reported noble metal catalysts.Remarkably,the reaction rate of I-Cd-MOF(4.28 min^(-1))is about 47.6 times higher than that of the Cd-based neutral MOF(N-Cd-MOF)with the similar crystalline structure.Liquid chromatograph mass spectrometer(LC-MS)and theoretical results demonstrate that 4-NP and five intermediates are stabilized in the channels of I-Cd-MOF,which increases the possibility of contact with H^*and H_(2)g enerated at the Cd sites.The I-Cd-MOF was extended to other nitroaromatic hydrogenation catalysis,which still displays excellent activity.More importantly,the I-MOF@Filter membrane was successfully constructed for continuous hydrogenation catalytic reactions,which maintains a high catalytic performance after 7 cycles of recycling without washing.This work fills in the application of the I-MOFs in hydrogenation catalytic reactions and provides an effective way for the rapid and green degradation of nitroaromatic compounds.

关键词： Anions Metal-organic frameworks Catalysis Electron transfer Hydrogen production

Exploration of pathogenic microorganism within the small intestine of necrotizing enterocolitis

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World Journal of Pediatrics 2024年第2期20卷 165-172页

作者： Yan Wang Kun Jiang Qiao Xia Xia Kang Shan Wang Ji-Hong Yu Wen-Feng Ni Xiao-Qin Qi Ying-Na Zhang Jin-Bao Han Gang Liu lei hou Zhi-Chun Feng Liu-Ming Huang Clinical Biobank Center Medical Innovation Research Division of ChinesePLA General HospitalBeijingChina Institute of Basic Medical Sciences Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Senior Department of Pediatrics The Seventh Medical Center of PLA General HospitalBeijing 100700China Department of Neurology The First Medical CenterChinese PLA General HospitalBeijing 100853China Department of Emergency Center National Center for Children's HealthBeijing Children's HospitalCapital Medical UniversityBeijing 100045China

Background Necrotizing enterocolitis(NEC)is the most common severe gastrointestinal emergency in neonates.We designed this study to identify the pathogenic microorganisms of NEC in the microbiota of the small intestine of neonates.Methods Using the 16S ribosomal DNA(rDNA)sequencing method,we compared and analyzed the structure and diversity of microbiotas in the intestinal feces of different groups of neonates:patients undergoing jejunostomy to treat NEC(NP group),neonates undergoing jejunostomy to treat other conditions(NN group),and neonates with NEC undergoing conservative treatment(NC group).We took intestinal feces and saliva samples from patients at different time points.Results The beta diversities of the NP,NN,and NC groups were all similar.When comparing the beta diversities between different time points in the NP group,we found similar beta diversities at time points El to E3 but significant differences between the E2-E3 and E4 time points:the abundances of Klebsiella and Enterococcus(Proteobacteria)were higher at the E1-E3 time points;the abundance of Escherichia-Shigella(Proteobacteria)increased at the E2 time point,and the abundance of Klebsiella decreased significantly,whereas that of Streptococcus increased significantly at the E4 time point.Conclusions Our results suggest that the pathological changes of intestinal necrosis in the small intestine of infants with NEC are not directly caused by excessive proliferation of pathogenic bacteria in the small intestine.The sources of microbiota in the small intestine of neonates,especially in premature infants,may be affected by multiple factors.

关键词： Microbiota Necrotizing enterocolitis-Small intestine 16S rDNA

Optimization of the Pre-Hospital Rescue System for Out-of-Hospital Cardiac Arrest in China

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China CDC weekly 2022年第3期4卷 52-55页

作者： lei hou Yumeng Wang Wenlei Wang National Center for Chronic and Noncommunicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina Public Health School Baotou Medical CollegeBaotouInner Mongolia Autonomous RegionChina The Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region UrumqiXinjiang Uygur Autonomous RegionChina

Out-of-hospital cardiac arrest(OHCA)presents a significant public health challenge in China.A sharp contrast in survival rate after OHCA exists between China and more developed countries.Due to the short life-saving time window,emergency medical services(EMS)and bystanders peripheral to EMS are key contributors to survival after OHCA.Here we discuss limitations and challenges for current EMS in rescuing OHCA by reviewing requirements for EMS in China.We call for an updated public health-based prehospital rescue system that includes establishing a cardiac arrest registry,promoting a“Three Early’s”campaign[early dialing of emergency hotline 120,early cardiopulmonary resuscitation(CPR),and early defibrillation],and operating a mechanism comprised of professional public health institutions(EMS,CDC,specialized disease prevention and control institutions,and health education institutions)as well as many governmental departments,such as healthcare,industry and information technology,and education,and non-governmental organizations,such as the Red Cross Society.Following the optimization of the prehospital rescue system and the participation of the whole population in self-rescue and mutual rescue,we believe that a dramatic improvement in OHCA survival will come about in China.

关键词： prevention education Rescue

Crack Fault Diagnosis and Location Method for a Dual-Disk Hollow Shaft Rotor System Based on the Radial Basis Function Network and Pattern Recognition Neural Network

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 180-197页

作者： Yuhong Jin lei hou Zhenyong Lu Yushu Chen School of Astronautics Harbin Institute of TechnologyHarbin 150001China Institute of Dynamics and Control Science Shandong Normal UniversityJi’nan 250014China

The crack fault is one of the most common faults in the rotor system,and researchers have paid close attention to its fault diagnosis.However,most studies focus on discussing the dynamic response characteristics caused by the crack rather than estimating the crack depth and position based on the obtained vibration signals.In this paper,a novel crack fault diagnosis and location method for a dual-disk hollow shaft rotor system based on the Radial basis function(RBF)network and Pattern recognition neural network(PRNN)is presented.Firstly,a rotor system model with a breathing crack suitable for a short-thick hollow shaft rotor is established based on the finite element method,where the crack's periodic opening and closing pattern and different degrees of crack depth are considered.Then,the dynamic response is obtained by the harmonic balance method.By adjusting the crack parameters,the dynamic characteristics related to the crack depth and position are analyzed through the amplitude-frequency responses and waterfall plots.The analysis results show that the first critical speed,first subcritical speed,first critical speed amplitude,and super-harmonic resonance peak at the first subcritical speed can be utilized for the crack fault diagnosis.Based on this,the RBF network and PRNN are adopted to determine the depth and approximate location of the crack respectively by taking the above dynamic characteristics as input.Test results show that the proposed method has high fault diagnosis accuracy.This research proposes a crack detection method adequate for the hollow shaft rotor system,where the crack depth and position are both unknown.

关键词： Hollow shaft rotor Breathing crack Radial basis function network Pattern recognition neural network Machine learning

An effective crack position diagnosis method for the hollow shaft rotor system based on the convolutional neural network and deep metric learning

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Chinese Journal of Aeronautics 2022年第9期35卷 242-254页

作者： Yuhong JIN lei hou Yushu CHEN Zhenyong LU School of Astronautics Harbin Institute of TechnologyHarbin 150001China Institute of Dynamics and Control Science Shandong Normal UniversityJi'nan 250014China

In recent years, the crack fault is one of the most common faults in the rotor system and it is still a challenge for crack position diagnosis in the hollow shaft rotor system. In this paper, a method based on the Convolutional Neural Network and deep metric learning(CNN-C) is proposed to effectively identify the crack position for a hollow shaft rotor system. Center-loss function is used to enhance the performance of neural network. Main contributions include: Firstly, the dynamic response of the dual-disks hollow shaft rotor system is obtained. The analysis results show that the crack will cause super-harmonic resonance, and the peak value of it is closely related to the position and depth of the crack. In addition, the amplitude near the non-resonant region also has relationship with the crack parameters. Secondly, we proposed an effective crack position diagnosis method which has the highest 99.04% recognition accuracy compared with other algorithms. Then,the influence of penalty factor on CNN-C performance is analyzed, which shows that too high penalty factor will lead to the decline of the neural network performance. Finally, the feature vectors are visualized via t-distributed Stochastic Neighbor Embedding(t-SNE). Naive Bayes classifier(NB) and K-Nearest Neighbor algorithm(KNN) are used to verify the validity of the feature vectors extracted by CNN-C. The results show that NB and KNN have more regular decision boundaries and higher recognition accuracy on the feature vectors data set extracted by CNN-C,indicating that the feature vectors extracted by CNN-C have great intra-class compactness and inter-class separability.

关键词： Convolutional neural networks Cracked rotor Deep metric learning Fault diagnosis Hollow shaft rotor

Erratum to: A robust indium-organic framework with open tubular channels for efficient separation of acetylene

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Nano Research 2024年第4期17卷 3425-3425页

Erratum to Nano Research,2024,17(4):3139–3146 https://***/10.1007/s12274-023-6061-8 In the first page of the original version of this paper,the corresponding authors should be“Yanwei Sui”and“lei hou”,instead of“lei hou”and“Yao-Yu Wang”.And“Address correspondence to:lei hou,lhou2009@***;Yao-Yu Wang,wyds123456@***”should be corrected to“Address correspondence to:lei hou,lhou2009@***;Yanwei Sui,wyds123456@***”.

关键词： separation correspondence outlook

High-static-low-dynamic stiffness isolator based on an electromagnetic negative stiffness spring with long linear stroke

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Science China(Technological Sciences) 2024年第3期67卷 740-752页

作者： YUAN ShuJin WU YaJun SONG DaiPing PU HuaYan MOU LiSheng hou lei ZHAO Jinglei LI XuePing LUO Jun WU Jie HUANG XiaoXu State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China China Aerodynamics Research and Development Center Mianyang 621000China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Negative stiffness mechanisms can improve low-frequency vibration isolation performance and have been widely used in the vibration isolation of precision equipment. However, the negative stiffness mechanism usually introduces a nonlinear stiffness,resulting in a nonlinear response and worsening the vibration isolation performance, especially under large amplitude vibration.In this paper, an electromagnetic spring with linear negative stiffness(ESLNS) is proposed, in which the antagonistic ampere forces of the energized coils are used to generate negative stiffness within a long linear stroke. The magnetic field distribution is improved through the design of the magnetic circuit, thereby increasing the stiffness generation efficiency. The stiffness can be adjusted bidirectionally by current within the range of positive and negative stiffness. An electromagnetic stiffness model was established based on the equivalent magnetic circuit method. Experimental measurements verified the accuracy of the model and proved the linearity of the electromagnetic spring. A vibration isolator with high static and low dynamic stiffness(HSLDS) based on the ESLNS is designed and tested. The experimental results prove that the introduction of the ESLNS can effectively expand the isolation frequency band without changing the equilibrium position. Moreover, the vibration isolator with ESLNS does not produce nonlinear response. The proposed electromagnetic spring with linear negative stiffness extends the application range of HSLDS isolators to a large amplitude vibration environment.

关键词： linear negative stiffness mechanism low-frequency vibration isolation electromagnetic spring vibration control

Terahertz near-field microscopy based on an air-plasma dynamic aperture

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Light(Science & Applications) 2022年第6期11卷 1149-1157页

作者： Xin-Ke Wang Jia-Sheng Ye Wen-Feng Sun Peng Han lei hou Yan Zhang Beijing Key Laboratory of Metamaterials and Devices Key Laboratory of Terahertz Optoelectronics Ministry of EducationDepartment of PhysicsCapital Normal UniversityBeijing 100048China Applied Physics Department Xian University of TechnologyXianShaanxi 710048China

Terahertz(THz)near-field microscopy retains the advantages of THz radiation and realizes sub-wavelength imaging,which enables applications in fundamental research and industrial fields.In most THz near-field microscopies,the sample surface must be approached by a THz detector or source,which restricts the sample choice.Here,a technique was developed based on an air-plasma dynamic aperture,where two mutually perpendicular air-plasmas overlapped to form a cross-filament above a sample surface that modulated an incident THz beam.THz imaging with quasi sub-wavelength resolution(approximately λ/2,where λ is the wavelength of the THz beam)was thus observed without approaching the sample with any devices.Damage to the sample by the air-plasmas was avoided.Near-field imaging of four different materials was achieved,including metallic,semiconductor,plastic,and greasy samples.The resolution characteristics of the near-field system were investigated with experiment and theory.The advantages of the technique are expected to accelerate the advancement of THz microscopy.

关键词： field dynamic resolution

A novel adaptive harmonic balance method with an asymptotic harmonic selection

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Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1887-1910页

作者： Rongzhou LIN lei hou Yi CHEN Yuhong JIN N.A.SAEED Yushu CHEN School of Astronautics Harbin Institute of TechnologyHarbin 150001China Department of Physics and Engineering Mathematics Faculty of Electronic EngineeringMenoufia UniversityMenouf 32952Egypt Department of Automation Biomechanicsand MechatronicsFaculty of Mechanical EngineeringLodz University of TechnologyLodz 90924Poland Mathematics Department Faculty of ScienceGalala UniversityGalala 43511Egypt

The harmonic balance method(HBM)is one of the most widely used methods in solving nonlinear vibration problems,and its accuracy and computational efficiency largely depend on the number of the harmonics selected.The adaptive harmonic balance(AHB)method is an improved HBM method.This paper presents a modified AHB method with the asymptotic harmonic selection(AHS)procedure.This new harmonic selection procedure selects harmonics from the frequency spectra of nonlinear terms instead of estimating the contribution of each harmonic to the whole nonlinear response,by which the additional calculation is avoided.A modified continuation method is proposed to deal with the variable size of nonlinear algebraic equations at different values of path parameters,and then all solution branches of the amplitude-frequency response are obtained.Numerical experiments are carried out to verify the performance of the AHB-AHS method.Five typical nonlinear dynamic equations with different types of nonlinearities and excitations are chosen as the illustrative examples.Compared with the classical HBM and Runge-Kutta methods,the proposed AHB-AHS method is of higher accuracy and better convergence.The AHB-AHS method proposed in this paper has the potential to investigate the nonlinear vibrations of complex high-dimensional nonlinear systems.

关键词： harmonic balance method(HBM) adaptive harmonic balance(AHB)method harmonic selection nonlinear vibration multi-frequency excitation