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Absolute Orientation of Molecules with Competing Hydrophilic Head Groups at the Air/Water Interface Probed with Sum Frequency Generation Vibrational Spectroscopy

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Chinese Journal of Chemical Physics 2009年第2期22卷 197-203页

作者： feng Wang Zhi Huang Zhi-feng cui Hong-fei Wang Department of Physics Anhui Normal University Wuhu 241000 China Beijing National Laboratory for Molecular Sciences State Key Laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China

The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation （SFG） spectra provides a direct measurement of the absolute orientation of these molecular groups. This simple approach can be employed to interrogate absolute molecular orientations other than using the complex absolute phase measurement in the SFG studies. We used the -CN group in the p-cyanophenol （PCP） molecule as the internal phase standard, and we measured the phases of the SFG fields of the -CN groups in the 3,5-dimethyl-4-hydroxy-benzonitrile （35DMHBN） and 2,6-dimethyl-4-hydroxy-benzonitrile （26DMHBN） at the air/water interface by measuring the SFG spectra of the aqueous surfaces of the mixtures of the PCP, 35DMHBN, and 26DMHBN solutions. The results showed that the 35DMHBN had its -CN group pointing into the aqueous phase; while the 26DMHBN, similar to the PCP, had its -CN group pointing away from the aqueous phase. The tilt angles of the -CN group for both the 35DMHBN and 26DMHBN molecules at the air/water interface were around 25°-45° from the interface normal. These results provided insights on the understanding of the detailed balance of the competing factors, such as solvation of the polar head groups, hydrogen bonding and hydrophobic effects, etc., on influencing the absolute molecular orientation at the air/water interface.

关键词： Sum frequency generation vibrational spectroscopy Air/water interface Molecule orientation p-cyanophenol

Structures and Electronic Properties of Cu_N (N≤13) Clusters

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Communications in Theoretical Physics 2009年第10期52卷 675-680页

作者： feng cui-Ju ZHANG Xiao-Yan Department of Basic Courses North China Institute of Science and Technology Beijing 101601 China

A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copper clusters. Our results show that the three-dimensional isomers of copper clusters start from Cu7 cluster and then show a tendency to form more compact structures. The results of the formation energy and the second derivative of binding energy with duster size show that besides N = 8, N =11 is also a magic number. Furthermore, it is the first time to find that the ground state of 11-atom clusters is a biplanar structure as same as the 13-atom cluster. The clear odd-even alternation as cluster size for the formation energy indicates the stability of electronic close shell existed in the range studied.

关键词： first-principles calculations density functional for molecules copper clusters

Dynamic Modeling and Analysis of 9-DOF Omnidirectional Legged Vehicle

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 515-521页

作者： GAO feng WANG Guofu cui Ying YANG Xinhong School of Transportation Science ＆ Engineering Beihang University Beijing 100191 China

The omnidirectional legged vehicle with steering-rails has a specific mechanism feature, and it can be controlled flexibly and accurately in omnidirectional motion. Currently there lacks further research in this area. In this paper, the mechanical characteristics of independent walking control and steering control and its kinematics principle are introduced, and a vehicle has a composite motion mode of parallel link mechanism and steering mechanism is presented. The motion direction control of the proposed vehicle is only dependant on its steering rails, so its motion is simple and effective to control. When the relative motion between the walking and steering is controlled cooperatively, the vehicle can walk perfectly. By controlling the steering rails, the vehicle can walk along arbitrary trajectory on the ground. To achieve a good result of motion control, an equivalent manipulator model needs to be built. In terms of the mechanism feature and the kinematic principle, the simplified manipulator model consists of a rail in stance phase, a rail in swing phase, and an equivalent leg. Considering the ground surface slope during walking, a parameter of inclination angle is added. Based on such a RPP manipulator model, the equations of motion are derived by means of Lagrangian dynamic approach. To verify the dynamic equations, the motion of the manipulator model is simulated based on linear and nonlinear motion planning. With the same model and motion parameters, the dynamic equations can be solved by Matlab and the calculation data can be gained. Compared with the simulation data, the result confirms the manipulator dynamic equations are correct. As a result of such special characteristics of the legged mechanism with steering rails, it has a potential broad application prospects. The derivation of dynamics equation could benefit the motion control of the mechanism.

关键词： legged vehicle omnidirectional motion steering rails dynamic modeling dynamic simulation

Behaviors of different inhibitors during secondary recrystallization of a grain-orientated silicon steel

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 314-319页

作者： feng-e cui Ping Yang Wei-min Mao School of Materials Science and Engineering University of Science and Technology Beijing 100083 China

The behaviors of different inhibitors including their composition, size, distribution, coalescence and coarsening were experimen-tally studied. It was observed that during secondary recrystallization of the tested steel, the key inhibition effect was produced by Cu2S and AlN, but not MnS. With the increase of temperature, the size distributions of AlN and Cu2S were changed to some extent. However, signifi-cant changes in particle size were not observed. The initial temperature of abnormal growth was determined by measuring the evolution of particle sizes and their distribution density during heat treatment. AlN and Cu2S are the dominant inhibitors and both are necessary, which is verified by calculating the Zener factor.

关键词： silicon steel secondary recrystallization inhibitors grain growth

Experimental study of an ellipsoidal particle in tube Poiseuille flow

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Journal of Hydrodynamics 2020年第3期32卷 616-622页

作者： Yuan-feng cui Xiang-ting Chang Hai-bo Huang Department of Modern Mechanics University of Science and Technology of ChinaHefei 230026China

Behaviors of a prolate ellipsoid inside circular tube Poiseuille flow are studied experimentally. In the study, Reynolds number Re ∈ (100,700) and the confinement ratio D/A ∈ (1.2,2.8) are considered, where D is the diameter of the tube and A is the length of the major axis of the ellipsoid. Two typical stable motion modes are identified, namely, the horizontal, and inclined modes. Then another inclined mode (inclined mode II) is found at high Reynolds number (Re ∈ (1000,3200)) and small D/A, and the inclined angle of ellipsoid increases with the increase of Re. The possible mechanism is explained. Our experiment shows that the lagging velocity U increases as Re increases. Further numerical analysis using FLUENT shows that due to the increase of U, the moment acting on the particle would make the inclined angle of the particle increase.

关键词： Ellipsoidal particle Poiseuille flow circular tube experiment

Large-scale gene expression reveals different adaptations of Hyalopterus persikonus to winter and summer host plants

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Insect Science 2017年第3期24卷 431-442页

作者： Na cui Peng-Cheng Yang Kun Guo Le Kang feng cui State Key Laboratory of Integrated Management of Pest Insects & Rodents Institute of Zoology Chinese Academy of Sciences Beijing 100101 Beijing Institutes of Life Science Chinese Academy of Sciences Beijing 100101 Institute of Medicinal Plant Development Chinese Academy of Medical Sciences Peking Union Medical College Beijing 100193 University of Chinese Academy of Sciences Being 100049 China

Host alternation, an obligatory seasonal shifting between host plants of distant genetic relationship, has had significant consequences for the diversification and success of the superfamily of aphids. However, the underlying molecular mechanism remains unclear. In this study, the molecular mechanism of host alternation was explored through a large-scale gene expression analysis of the mealy aphid Hyalopterus persikonus on winter and summer host plants. More than four times as many unigenes of the mealy aphid were significantly upregulated on summer host Phragmites australis than on winter host Rosaceae plants. In order to identify gene candidates related to host alternation, the differentially expressed unigenes of H. persikonus were compared to salivary gland expressed genes and secretome of Acyrthosiphon pisum. Genes involved in ribosome and oxidative phosphorylation and with molecular functions of heme-copper terminal oxidase activity, hydrolase activity and ribosome binding were potentially upregulated in salivary glands of//. persikonus on the summer host. Putative secretory proteins, such as detoxification enzymes （carboxylesterases and cytochrome P450s）, antioxidant enzymes （peroxidase and superoxide dismutase）, glutathione peroxidase, glucose dehydrogenase, angiotensin-converting enzyme, eadherin, and calreticulin, were highly expressed in H. persikonus on the summer host, while a SCP GAPR-I-like family protein and a salivary sheath protein were highly expressed in the aphids on winter hosts. These results shed light on phenotypic plasticity in host utilization and seasonal adaptation of aphids.

关键词： aphid host alternation parasite-host interaction phenotypic plasticity salivary gland transcriptome

A Piezoelectrically Driven Microrobot Using a Novel Monolithic Spatial Parallel Mechanism as Its Hip Joint

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Journal of Bionic Engineering 2024年第2期21卷 803-820页

作者： Guangping Wu Ziyang Wang Jiaxin Zhao feng cui Xinghan Cai National Key Laboratory of Advanced Micro and Nano Manufacture Technology Shanghai Jiao Tong UniversityShanghai200240China Department of Micro-Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai200240China

Inspired by the fast,agile movements of insects,we present a 1.9 g,4.5 cm in length,piezoelectrically driven,quadrupedal *** microrobot uses a novel spatial parallel mechanism as its hip joint,which consists of two spatially orthogonal slider-crank *** mechanism maps two inputs of two independent actuators to the decoupled swing and lift outputs of a leg,and each leg can produce the closed trajectories in the sagittal plane necessary for robot ***,the kinematics of the transmission are analyzed,and the parameters of the flexure hinges are designed based on geometrical constraints and yield *** hip joints,legs and exoskeletons are integrated into a five-layer standard laminate for monolithic fabrication which is composed of two layers of carbon fiber,two layers of acrylic adhesive and a polyimide *** measured output force(15.97 mN)of each leg is enough to carry half of the robot’s weight,which is necessary for the robot to move *** has been proven that the robot can successfully perform forward and turning *** to the microrobot fabricated with discrete components,the monolithically fabricated microrobot is more capable of maintaining the original direction of locomotion when driven by a forward signal and has a greater speed,whose maximum speed is 25.05 cm/s.

关键词： Insect-like Crawling microrobot Piezoelectric drive Parallel mechanism Monolithic fabrication

Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep and thick seam

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Mining Science and Technology 2011年第1期21卷 99-105页

作者： Miao Shengjun Lai Xingping cui feng Civil ＆ Environmental Engineering School University of Science and Technology Beijing 100083 China School of Energy Engineering Xi＇an University of Science and Technology Xi＇an 710054 China

Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing *** the caving ratio is low,which might result in some disasters,such as roof falls,induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body,the tall,broken section of the top coal（a granular medium）of an extremely steep seam（over 60°）shows clear characteristics of nonlinear *** have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed *** on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas,we conclude that the weakened top coal can be regarded as a non-continuous *** used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal *** results of our simulation, experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving,relieve space for large area dynamic collapse of top coal,prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining.

关键词： Top coal flowsExtremely steep and thick coal seamHigh section top coal caving (HSTCC)Particle flow

Explicit Representations for Local Lagrangian Numerical Differentiation

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Acta Mathematica Sinica,English Series 2007年第2期23卷 365-372页

作者： He Yu WANG feng cui Xing Hua WANG Computing Center Zhejiang University Department of Mathematics Hong Kong Baptist University Department of Mathematics Zhejiang University

It is shown that in Lagrangian numerical differentiation formulas, the coefficients are explicitly expressed by means of cycle indicator polynomials of symmetric group. Moreover, asymptotic expansions of the remainders are also explicitly represented as a fixed number of interpolation nodes approaching infinitely to the point at which the derivative is evaluated. This implies that complete explicit formulas for local Lagrangian numerical differentiation can be obtained.

关键词： numerical differentiation explicit representation local estimate symmetric group cycle indicator