114例颈椎定点复位法加扶阳罐治疗颈椎小关节微错缝的临床观察

目的:探讨颈椎定点复位法加扶阳罐治疗颈椎小关节微错缝的临床疗效。方法:114例患者均采用颈椎定点复位法加扶阳罐治疗。具体分四步。手法定位;松解肌肉;颈椎定点旋转复位;扶阳罐理筋温熨。5次一疗程。若还有症状,休息二天后,重复一疗程。结果:治愈率89.47%,总有效率99.12%。结论:此法可纠正颈椎紊乱的关节,缓解痉挛的肌肉,解除神经、血管的刺激和压迫,改善局部血液循环,使颈椎各关节保持相对的稳定。疗效好,安全易行,值得推广。

微钛钉种植支抗治疗骨性Ⅱ类错牙合畸形18例

目的探讨微钛钉种植支抗在骨性Ⅱ类错（牙合）中的临床应用。方法18例Ⅱ类错（牙合）患者，上颌前突，矫治设计为拔除双侧第一前磨牙，支抗设计为磨牙强支抗，用微钛钉植入上颌第一磨牙第二前磨牙颊侧根尖之间的牙槽间隔，结合直丝弓技术进行滑动法关闭拔牙间隙。以每侧150～200g力滑动法内收前牙。比较内收前牙前、后头颅定位侧位片，测量前牙内收情况和磨牙支抗的变化。结果18例牙弓突度均得到明显改善，切牙切缘平均内收6．5mm，支抗磨牙平均前移0．5mm，有效地控制了后牙支抗。结论微钛钉种植支抗作为稳定的正畸支抗，不依赖患者的合作，能有效地控制后牙支抗，使前突的牙弓得到较完美的矫治，扩大了正畸治疗的范围。

孪生诱发塑性(TWIP)钢的研究现状

综述了孪生诱发塑性(TWIP)钢的研究现状及进展。重点介绍了各合金元素对TWIP效应的作用以及Fe-Mn-Si-Al、Fe-Mn-C、FevMn-C-Al3种不同成分系列TWIP钢的组织性能特点。总结了热处理工艺及应变条件对Fe-Mn-Si-Al系列TWIP钢孪生组织和力学性能的影响。简述了层错能对TWIP效应的重要影响作用以及几种测算层错能的方法。

Microstructures of PM Ti-45Al-10Nb alloy fabricated by reactive sintering

Powder metallurgy Ti-45Al-10 Nb alloys was successfully fabricated by reactive sintering of milled powders at 1350 °C for 2 h in vacuum. The microstructure, in particular, constituent phases, grain size, precipitates of the product was investigated in detail. The results indicate that a double phase γ＋α2 microstructure containing Ti2 Al C precipitate is obtained under the sintering condition, and the alloy exhibits a fine and homogenous microstructure compared with traditional Ti Al base. In fine grain structure, the average grain sizes for the γ and α2 phases are（2.3±0.05） and（5.6±0.05） μm, respectively. Additionally, numerous dislocations are observed in the alloy, and the dislocation density in γ phase is significantly higher than that in α2 phase. The formation mechanisms of the dislocation in the present alloy were also discussed in detail.

Effect of Mg on nucleation process of recrystallization in Al-Mg-Si/SiC_p composite

The recrystallization nucleation processes of two cold-rolled Al-Mg-Si/SiCpcomposites with different contents of Mg are investigated mainly by dynamic mechanical analyzer （DMA） and electron microscopy including high angle annular dark field scanning transmission electron microscopy （HAADF-STEM） andhigh-resolution transmission electron microscopy （HRTEM）. Internal friction and electron microscopy results show that solute atom clusters are present in association with dislocationsin supersaturated cold-rolled composites. During recrystallization process, the internal friction peak position of Al-Mg-Si/3SiCp/2Mg （volume fraction,%） is higher than that of Al-Mg-Si/3SiCp（volume fraction,%） due to more solute atom clusters formed in association with the dislocations in the cold-rolled composite with a much higher Mg content, indicating a strongerresistance for the recrystallization nucleation.

Microstructure evolution and mechanical properties of Mg-7Gd-3Y-1Nd-1Zn-0.5Zr alloy

X-ray diffraction （XRD）, optical microscopy （OM）, scanning electronic microscopy （SEM）, transmission electron microscopy （TEM） and tensile tests at room temperature （RT） were performed to investigate the effect of homogenization on microstructure evolution and mechanical properties of Mg-7Gd-3Y-1Nd-1Zn-0.5Zr （mass fraction,%） alloy. The results indicate that the microstructure of the as-cast alloy is composed of α-Mg, （Mg, Zn）3RE phase and stacking fault （SF）, the homogenization results in the disappearance of （Mg, Zn）3RE phase and stacking fault （SF） as well as the emergence of 14H-type long-period stacking ordered （LPSO） phase. The ultimate tensile strength （UTS）, yield strength （YS） and elongation of the as-cast alloy are 187 MPa, 143 MPa and 3.1%, and the UTS, YS and elongation of the as-homogenized alloy are 229 MPa, 132 MPa and 7.2%, respectively.

Micro-bending of metallic crystalline foils by non-local dislocation density based crystal plasticity finite element model

A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.

Quasicontinuum simulation of indentation on FCC metals

Quasicontinuum simulations were performed to study the processes of incipient plastic deformation on three FCC metals (Ag,Ni and Pd) under the action of a rigid indenter.Four widths (9.3,18.6,27.9 and 37.2 ) of the indenters were modelled for each metal specimen.A series of load-displacement responses and the strain energy versus displacement responses of the indenter were presented.It is shown that the abrupt drop of the load in the load-displacement response is triggered by the nucleation of dislocations in the metals.The critical load of each metal specimen increases with the increase of the indenter width,while the hardness of the metal specimen decreases as the indenter width increases.Furthermore,the microscopic mechanism of deformation in the films was analyzed.Two dislocations are nucleated respectively beneath the right and left sides of the indenter.Each dislocation successively decomposes into two Shockley partial dislocations after the first nucleation process.The distances between the two partial dislocations are equal for both sides of the indenter,which are in agreement with the theoretical values.

Influence of Cr addition on microstructure of a 5% Re-containing single crystal nickel-based superalloy

Based on a 5% （mass fraction） Re-containing single crystal nickel-based superalloy with 3% （mass fraction） Cr, the microstructural variation with Cr addition was investigated. The experimental results show that segregation of alloying elements was enhanced in as-cast microstructure with Cr addition; and the volume fraction of eutectic is increased. However, the solidus and liquidus temperatures are remarkably reduced. With the increase of Cr content, the average γ＇ size and volume fraction are decreased in the fully heat treated microstructure. X-ray diffraction results indicate that γ/γ＇ lattice misfit becomes more negative. According to the energy dispersive spectroscopy （EDS） results, Cr is mainly distributed in the γ matrix; and more y-forming elements, such as Re and W, enter the γ matrix, while the γ/γ＇ partition ratio of Cr is inversely decreased.

Evolution of Self-Organized Ge Quantum Dots During Ultra High Vacuum Annealing

The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When the sample temperature rises to 630℃,a great amount of new dots emerge on the wetting layer,which are believed to be incoherent islands compared with the dislocation free coherent islands formed during molecular beam epitaxy growth.

Microstructural evolution during hot and cold deformation of Ti-36Nb-2Ta-3Zr-0.35O alloy

The Ti-36Nb-2Ta-3Zr-0.350 （mass fraction, %） （TNTZO） alloy was produced by cold isostatic pressing and sintering from elemental powders, followed by hot and cold deformation. The effects of deformation process on microstructures and mechanical properties were investigated using the SEM, TEM, OM and the universal material testing machine. Results show that the alloy can be easily hot forged and cold swaged due to the fine-grained microstructure. Only after cold swaging by 85%, the alloy shows the typical ＂marble-like＂ structure. And thecold deformation is accompanied by stress-induced a＂ phase transformations. Moreover, both the strength and the ductility of the alloy are significantly improved by hot and cold working.

Experimental Study on Revolving Cross-flow Microfiltration of Highly Viscous Liquids

Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.

Microstructures,tensile properties and serrated flow of Al_xCrMnFeCoNi high entropy alloys

Microstructures and mechanical properties of dual-phase AlxCrMnFeCoNi (x=0.4, 0.5, 0.6, at.%) alloys were investigated. Thermomechanical processing leads to a microstructural evolution from cast dendritic structures to equiaxed ones, consisting of face-centered cubic (fcc) and body-centered cubic (bcc) phases in the two states. The volume fraction of bcc phase increases and the size of fcc grain decreases with increasing Al content, resulting in remarkably improved tensile strength. Specifically, the serrated flow occurring at the medium temperatures varies from type A+B to B+C or C as the testing temperature increases. The average serration amplitude of these Al-containing alloys is larger than that of CoCrFeNiMn alloy due to the enhanced pinning effect. The early small strain produces low-density of dislocation arrays and bowed dislocations in fcc grains while the dislocation climb and shearing mechanism dominate inside bcc grains. The cross-slip and kinks of dislocations are frequently observed and high-density-tangled dislocations lead to dislocation cells after plastic deformation with a high strain.

Experimental and CFD Studies on the Performance of Microfiltration Enhanced by a Turbulence Promoter

This paper reports experimental and computational fluid dynamics(CFD) studies on the performance of microfiltration enhanced by a helical screw insert.The experimental results show that the use of turbulence pro-moter can improve the permeate flux of membrane in the crossflow microfiltration of calcium carbonate suspension,and flux improvement efficiency is strongly influenced by operation conditions.The energy consumption analysis indicates that the enhanced membrane system is more energy saving at higher feed concentrations.To explore the intrinsic mechanism of flux enhancement by a helical screw insert,three-dimensional CFD simulation of fluid flow was implemented.It reveals that hydrodynamic characteristics of fluid flow inside the channel are entirely changed by the turbulence promoter.The rotational flow pattern increases the scouring effect on the tube wall,reducing the particle deposition on the membrane surface.The absence of stagnant regions and high wall shear stress are respon-sible for the enhanced filtration performance.No secondary flow is generated in the channel,owing to the streamline shape of helical screw insert,so that the enhanced performance is achieved at relatively low energy consumption.

Adaptive fault-tolerant control of heavy lift launch vehicle via differential algebraic observer

A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle （HLLV）. By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second-order systems, i.e., pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer （DAO） was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral- differential （PID） controllers with disturbance compensation were designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be ultimately uniformly bounded by utilization of Lyapunov＇s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performance in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults.

Effect of pulsed current on AZ31B magnesium sheets during annealing

The annealing tests heated by pulsed current(PC)or furnace for AZ31B magnesium sheets were carried out,and the effects of PC on the microstructure and dislocation density of the alloy were analyzed.The results show that PC strengthens the migration of boundaries,and then the twin grains,most of which distribute in the coarse grains,“spheroidize”to equiaxed grains,thus separating the coarse grains and refining the microstructure.This process homogenizes the initial microstructure and eliminate the typically lamellar twin grains.Moreover,PC also strengthens the dislocation annihilation.When the specimens were annealed by PC at 300℃for 4 min,the dislocation density was even lower than that annealed by furnaces at 400℃for 3 h before deformation.Furthermore,dislocation annihilation is enhanced with the increase of peak current density and the decrease of pulsed frequency.

Dynamic Membrane for Cross-flow Micro-filtration in Treating Activated Sludge

Mixed liquid of activated sludge (AS) were micro-filtrated by dynamic membrane (DM) made of 6000 mesh kaolin. The results illustrated that the permeate quality and flux with DM filtration were superior to that with direct filtration in treating AS. The experiments of membrane washing showed that DM could abate the internal fouling of membranes efficiently, and the permeate flux of renewed membrane reached 90% of that of new membranes. The denser the mixed liquid suspended solids (MLSS) were, the lower the permeate flux was. Increasing of both flow velocity over the membrane surface and trans-membrane pressure (TMP) could lead to some enhancement of permeate flux, while the former approach could be carried out more economically. The feasibility of application of the DM to membrane bioreactor (MBR) has been ascertained.

Synergy of staggered stacking confinement and microporous defect fixation for high‐density atomic Fe^(Ⅱ)‐N_(4)oxygen reduction active sites

The development of high‐performance nonprecious metal catalysts(NPMCs)to supersede Pt‐based catalysts for the oxygen reduction reaction(ORR)in polymer electrolyte membrane fuel cells is highly desirable but remains challenging.In this paper,we present a pyrolysis strategy for spatial confinement and active‐site fixation using iron phthalocyanine(FePc),phthalocyanine(Pc)and Zn salts as precursors.In the obtained carbon‐based NPMC with a hierarchically porous nanostructure of thin‐layered carbon nanosheets,nearly 100%of the total Fe species are Fe^(Ⅱ)‐N_(4) active sites.In contrast,pyrolyzing FePc alone forms Fe‐based nanoparticles embedded in amorphous carbon with only 5.9%Fe^(Ⅱ)‐N_(4) active sites.Both experimental characterization and density functional theory calculations reveal that spatial confinement through the staggeredπ–πstacking of Pc macrocycles effectively prevents the demetallation of Fe atoms and the formation of Fe‐based nanoparticles via aggregation.Furthermore,Zn‐induced microporous defects allow the fixation of Fe^(Ⅱ)‐N_(4) active sites.The synergistic effect of staggered stacking confinement and microporous defect fixation results in a high density of atomic Fe^(Ⅱ)‐N_(4) active sites that can enhance the ORR.The optimal Fe^(Ⅱ)‐N_(4)‐C electro‐catalyst outperforms a commercial Pt/C catalyst in terms of half‐wave potential,methanol toler‐ance,and long‐term stability in alkaline media.This modulation strategy can greatly advance efforts to develop high‐performance NPMCs.

Effects of non-isothermal annealing on microstructure and mechanical properties of severely deformed aluminum samples:Modeling and experiment

In order to investigate the evolution of microstructure and flow stress during non-isothermal annealing,aluminum samples were subjected to strain magnitudes of 1, 2 and 3 by performing 2, 4 and 6 passes of multi-directional forging. Then, the samples were non-isothermally annealed up to 150, 200, 250, 300 and 350 ℃. The evolution of dislocation density and flow stress was studied via modeling of deformation and annealing stages. It was found that 2, 4 and 6 passes multi-directionally forged samples show thermal stability up to temperatures of 250, 250 and 300 ℃, respectively. Modeling results and experimental data were compared and a reasonable agreement was observed. It was noticed that 2 and 4 passes multi-directionally forged samples annealed non-isothermally up to 350 ℃ have a lower experimental flow stress in comparison with the flow stress achieved from the model.The underlying reason is that the proposed non-isothermal annealing model is based only on the intragranular dislocation density evolution, which only takes into account recovery and recrystallization phenomena. However, at 350℃ grain growth takes place in addition to recovery and recrystallization,which is the source of discrepancy between the modeling and experimental flow stress.