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A new route of fabricating porous polyimide membranes

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 782-785页

作者： Jiu-mei Xiao Xin-chun Shang Li-ping Qin School of Applied Science University of Science and Technology Beijing Beijing 100083 China

A novel experimental route to fabricate porous polyimide membranes （PPMs） with ideal air permeability was reported. The polymer solution layer consisting of the corresponding polyamic acid （PAA）, solvent, and dibutyl phthalate （DBP） with a boiling temperature of 340℃ was treated by a simple process. The polymer solution layer was first treated at a lower temperature （about 150℃）, then the received solid membrane was further imidized at a higher temperature （about 270℃）, and finally, DBP was removed from the membrane at a temperature above its boiling temperature. The final asymmetric polyimide membrane with a dense skin layer was obtained. To improve the air permeability of the polyimide membranes, the polymer solution layer was treated between two substrates. And the PPMs with open pores on both sides are fabricated and the air permeability of the films is improved greatly.

关键词： polyimide polyamic acid membrane additive porous materials

Effects of correlation time between noises on the noise enhanced stability phenomenon in an asymmetric bistable system

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Frontiers of physics 2015年第1期10卷 95-101页

作者： chun Li Zheng-Lin Jia Dong-Cheng mei Department of Computer Science Puer College Puer 665000 China Department of Physics Yuxi Normal University Yuxi 653100 China Department of Physics Yunnan University Kunming 650091 China

The effects of the correlation time τ between noises on the noise-enhanced stability （NES） phe- nomenon in an asymmetric bistable system driven by cross-correlated noise are investigated. The ex- pressions for the average escape time from the left metastable state TL and from the right metastable state TR are derived. The results indicate that： i） The NES effect is suppressed as the correlation time τ increases for two metastable states; ii） The increase in τ speeds up the escape process from the right state for positively correlated noise, whereas its role is reverses for negatively correlated; iii） In the escape process from the left state, the role of τ is opposite to that in escape from the right state.

关键词： asymmetric bistable system noise correlation time noise enhanced stability

FLOW PATTERN AND PRESSURE LOSS OF OIL-WATER TWO-PHASE FLOW IN HORIZONTAL STEEL PIPE

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Journal of Hydrodynamics 2005年第2期17卷 194-198页

作者： CHENJie YANDa-fan ZHAOJing-mei ANWei-jie YANDa-chun DepartmentofPetroleumEngineering UniversityofPetroleumBeijing102249China／／DepartmentofMechanicsPekingUniversityBeijing100871China／／CnoocResearchCenterBeijing100027China DepartmentofPetroleumEngineering UniversityofPetroleumBeijing102249China CnoocResearchCenter Beijing100027China DepartmentofMechanics PekingUniversityBeijing100871China

Experimental Study on oil-water two-phase flow patterns and pressure loss was conducted on a horizontal steel pipe loop with 26.1mm inner diameter and 30m total length. The working fluids are white oil, diesel oil and tap water. Several instruments, including a new type of liquid-probe are successfully integrated to identify 7 different flow patterns. The characteristics of the flow patterns and the transition process were observed and depicted in this paper. Investigation revealed that the pressure loss was mainly depended on the flow patterns.

关键词： oil water flow pattern pressure loss

Band Offset and Optical Property of (ZnS)_(n)/(Si2)_(n) (110) Superlattice

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Chinese Physics Letters 1996年第6期13卷 458-460页

作者： LI Kai-hang HUANG mei-chun WANG Ren-zhi Department of Physics Xiamen UniversityXiamen 361005

Supercell self-consistent calculation of band structures of(ZnS)_(n)/(Si_(2))_(n) (110) (n=2,3,4,5)has been performed by means of linear muffin-tin orbitals *** valence-band offset of such systems is calculated by frozen optential method and their Joint density of states has been computed by tetrahedron *** results show that the(ZnS)n/(Si_(2))n(110)superlattices have a large valence-band offset and their optical properties integrate exellent optical properties of bulk ZnS and that of Si.

关键词： method Si_(2)

Damage behavior of tungsten fiber-reinforced copper matrix composite after high-speed impact

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Rare Metals 2014年第3期33卷 330-336页

作者： Zhe Wu chun-mei Yang Qian-Jun Liu Yan Ma College of Mechanical and Electrical Engineering Northeast Forestry University

Wf/Cu82Al10Fe4Ni4composite was fabricated by means of infiltration casting. By the microstructure observation of the composite with the aid of scanning electron microscopy（SEM） and transmission electron microscopy（TEM）, it can be found that there are（Fe, Ni）,AlFe, Al3 Ni, and Cu3 Al precipitated phases existing in the matrix alloy. By two-stage light gas gun, Wf/Cu82Al10-Fe4Ni4composite hypervelocity projectile into concrete target test with the speed of 2.2 kmás-1is finished. By microstructure observation, it can be found that the failure mode of Wf/Cu82Al10Fe4Ni4composite projectile during penetration is the rapid peeling of tungsten fibers from the projectile, which makes the projectile display good selfsharpening property. Meanwhile, it can be found that microstructure morphology change of Wf/Cu82Al10Fe4Ni4composite occurs after hypervelocity impact. The density of dislocations around the large-dimensional（Fe, Ni）,AlFe, Al3 Ni, and Cu3 Al precipitated phases in the matrix alloy rises sharply. At the same time, there are largedimensional deformed twins existing in local regions and stacking faults existing inside the twins.

关键词： Composites Microstructure Damagebehavior High-speed impact

Geometrical statistical channel model arisen from scatterers around the mobile with an inverted-parabolic spatial distribution

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The Journal of China Universities of Posts and Telecommunications 2012年第5期19卷 1-8页

作者： ZHOU Jie LI chun-mei QIU Lin HISAKAZU Kikuchi Department of Communications Nanjing University of Information Science and Technology Nanjing 210044 China Department of Electronic and Electrical Engineering Niigata University Niigata 950-2181 Japan

In this paper, firstly presented a geometrically based statistical channel model with scatterers that are with an inverted parabolic spatial distribution around mobile station （MS） within a circle wherein the base station （BS） and MS are included. This paper proposed a technique to simply derive probability density functions （PDFs） of angle of arrival （AOA）, time of arrival （TOA） and Doppler spectra to characterize the outdoor macrocell and microcell environments by employing various distances between BS and MS, or different size of circular region. Employing this channel model, we analyze the impacts of a directional antenna at BS with the main-lobe width 2~z on the fading and the Doppler spectra.

关键词： inverted parabolic PDFs circular and elliptical scattering models directional antenna macrocell and microcell

Synthesis and Crystal Structure of [Cp_2Ln(OC(SEt)NPh )]_2

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Chinese Journal of Structural Chemistry 2006年第2期25卷 131-134页

作者： ZHANG chun-mei LIU Rui-Ting ZHOU Xi-Geng Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China Department of Chemistry East China University of Science and Technology Shanghai 200237 China

Treatment of Cp3Y with EtSH, followed by reaction with an equivalent of PhNCO, yielded the dinuclear complex [Cp2Y（μ-η^1：η^3-OC（SEt）NPh）]2. The structure was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction analysis. The title compound crystallizes in triclinic, space group P1^- with a = 8.643（3）, b = 10.752（4）, c = 11.161（4）A°, α= 117.840（5）, β = 94.086（5）, γ= 101.008（5）°, V = 884.8（6） A°^3, Z = 1, Mr = 798.66 （C38H40N2O2S2Y2）, λ（MoKα） = 0.710730 .A°, ,μ= 3.417 mm^-1, Dc = 1.499 g/cm^3, F（000） = 408, the final R = 0.0453 and wR = 0.1007 for 3067 unique reflections （Rint = 0.0317） with 2357 observed ones （I 〉 2σ（I））. X-ray analysis reveals an unusual bonding mode of the OC（SEt）NPh ligand and the OCN fragment acts as a both bridging and side-on chelating ligand. Each yttrium atom is coordinated by two η^5-cyclopentadienyl groups, one chelating η^3-OC（SEt）NPh ligand and one bridging O atom from another η^3-OC（SEt）NPh ligand.

关键词： organolanthanide isocyanate insertion structure cyclopentadienyl

Efficacy of Acupuncture Combined with Local Anesthesia in Ischemic Stroke Patients with Carotid Artery Stenting:A Prospective Randomized Trial

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Chinese Journal of Integrative Medicine 2020年第8期26卷 609-616页

作者： XIONG Wei ZHAO chun-mei AN Li-xin XIE Si-ning JIA chun-rong Department of Anesthesiology Beijing Tiantan HospitalCapital Medical UniversityBeijing 100015China Department of Anesthesiology Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China Department of Traditional Chinese Medicine Beijing Tiantan HospitalCapital Medical UniversityBeijing 100015China

Objective:To evaluate the efficacy of electro-acupuncture(EA)or transcutaneous electrical acupoint stimulation(TEAS)on perioperative cerebral blood flow(CBF)and neurological function in ischemic stroke(IS)patients undergoing carotid artery stenting(CAS).Methods:In total,124 consecutive IS patients were randomly allocated to the EA,TEAS,and sham groups(groups A,T,and S;41,42,and 41 cases,respectively)by softwarederived random-number *** A and T received EA and TEAS,respectively,at the Shuigou(GV 26)and Baihui(GV 20),Hegu(LI4)and Waiguan(TE 5)*** S received sham *** stimulation was started from 30 min before surgery until the end of the *** primary outcome was the CBF at 30 min after surgery,which was measured by transcranial Doppler *** secondary outcomes included hyperperfusion incidence and neurological *** Institutes of Health Stroke Scale(NIHSS)and General Evaluation Scale(GES)scores were recorded at 1 week,1 month,and 3 months ***:Mean CBF velocity at 30 min after surgery in groups A and T was much lower than that in Group S(P<0.05);the incidence of hyperperfusion in Groups A and T was also lower than that in group S(P<0.05).Acupuncture was an independent factor associated with reduced incidence of hyperperfusion(OR=0.042;95%CI:0.002–0.785;P=0.034).NIHSS and GES scores improved significantly at 1 week postoperatively in Groups A and T than in Group S(P<0.05).Relative to Group S,groups A and T exhibited significantly lower incidences of moderate pain,as well as higher incidences of satisfaction with anesthesia,at 1 day postoperatively(P<0.05).Conclusion:EA or TEAS administered in combination with local anesthesia during CAS can inhibit transient increases in CBF,reduce the incidence of postoperative hyperperfusion,and improve neurological function.

关键词： electro-acupuncture transcutaneous electrical acupoint stimulation carotid artery stenting cerebral blood flow neurological function

Inter-granular liquid phase aiding grain boundary sliding in superplastic deformation of fine-grained ZK60 Mg alloy

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Transactions of Nonferrous Metals Society of China 2010年第B07期20卷 576-579页

作者： LEE Shyong CHIANG Chih-te CHU chun-lin hsu Chang-chuan Department of Mechanical Engineering National Central University Jhong-li Taiwan China chun-Shan Institute of Science Lung-tan Taiwan China

For 7475 Al alloy,there were micrographs showing filaments or whiskers formation during the separation stage of superplastic *** indicates the presence of liquid phase which accommodates grain boundary sliding to reach *** the other hand,there is no such phenomenon reported regarding Mg alloy in *** electron microscopic(SEM)fractography exceptionally exhibits a mark of grain boundary sliding and its accommodating mechanism of inter-granular liquid *** the testing conditions of 350℃ and 1×10- 4s -1,the initially fine-grained structure(3.7μm)yields 642%superplastic elongation and exhibits fluffy appearance on the fractured *** other specimens showing less superplasticity,their fractured surfaces exhibit partial fluffy appearance.

关键词： Mg alloy inter-granular phase grain boundary sliding superplastic deformation