Combined effect of isothermal annealing and pre-compression on mechanical properties of Cu_(36)Zr_(48)Al_8Ag_8 bulk metallic glass

The combined effects of isothermal annealing and pre-compression on the mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass （BMG） were investigated. The as-cast specimens were first annealed at 743 K for 10 min, and then pre-compressed under 800 MPa for 1, 3, 5 and 10 h, respectively. The results indicated that annealing resulted in the formation of nanocrystals with a diameter of -10 nm in the amorphous matrix and a drastic decrease of the free volume, leading to complete loss of the plasticity of the BMG. Applying pre-compression under a stress of 800 MPa for a proper duration （5 h） resumed part of the lost free volume in the BMG matrix and therefore partially recovered the plasticity. A very long period of pre-compression （10 h） decreased the free volume again, which was caused by the excessive crystal growth.

Pre-Compression Volume on Flow Ripple Reduction of a Piston Pump

Axial piston pump with pre-compression volume（PCV） has lower flow ripple in large scale of operating condition than the traditional one. However, there is lack of precise simulation model of the axial piston pump with PCV, so the parameters of PCV are difticult to be determined. A finite element simulation model for piston pump with PCV is built by considering the piston movement, the fluid characteristic（including fluid compressibility and viscosity） and the leakage flow rate. Then a test of the pump flow ripple called the secondary source method is implemented to validate the simulation model. Thirdly, by comparing results among the simulation results, test results and results from other publications at the same operating condition, the simulation model is validated and used in optimizing the axial piston pump with PCV. According to the pump flow ripples obtained by the simulation model with different PCV parameters, the flow ripple is the smallest when the PCV angle is 13~, the PCV volume is 1.3 ~ I0-4 m3 at such operating condition that the pump suction pressure is 2 MPa, the pump delivery pressure 15 MPa, the pump speed 1 000 r/min, the swash plate angle 13~. At the same time, the flow ripple can be reduced when the pump suction pressure is 2 MPa, the pump delivery pressure is 5 MPa,15 MPa, 22 MPa, pump speed is 400 r/min, 1 000 r/rain, 1 500 r/rain, the swash plate angle is ll~, 13~, 15~ and 17~, respectively. The finite element simulation model proposed provides a method for optimizing the PCV structure and guiding for designing a quieter axial piston pump.

Grain size dependence of annealing strengthening of an extruded Mg-Gd-Zn alloy subjected to pre-compression deformation

In this work, pre-strain annealing strengthening(PSAS) effect was investigated in an extruded Mg-1.0Gd-1.5 Zn(wt.%) alloy with respect to different grain sizes. The evolution of microstructures was provided by scanning electron microscopy(SEM), electron backscattered diffraction(EBSD), transmission electron microscopy(TEM) and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM) under the initial state, pre-compression, intermediate annealing and re-compression conditions. The obtained results showed a grain size-dependent PSAS effect in the alloy. The sample with larger grain sizes corresponded to a higher strengthening effect, which mainly resulted from a more remarkable hindrance for the growth of existing twins and a larger proportion of activation for the nucleation of new twins. This was closely associated with the increase of back stress and friction stress for twin boundary motion impeded by the larger restraint of dislocations, the higher stress field surrounding solutes and the more Zn segregation. In addition to twinning behavior, Guinier Preston(G.P.) zones on basaldislocations were found after intermediate annealing and provided an extra strengthening by inhibiting the motions of gilding pre-existing dislocations and newly formed ones, but it was independent on the grain size.

Effects of pre-compression on formation of dynamic precipitates and creep anisotropy of hot-extruded AZ91−2Y magnesium alloy

The creep anisotropy behavior under different stresses at 180℃ of hot-extruded AZ91−2Y magnesium alloy with pre-compression(PC)and without pre-compression(NPC)was studied.Microstructure,texture and mechanical properties of the alloy were examined by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM)and tensile creep tests.The results revealed that the creep resistance was proportional to the volume fraction of spherical Mg_(17)Al_(12) precipitates.The dynamic precipitation of large volume fraction of lamellar Mg_(17)Al_(12) in NPC samples leads to the basaláañslip as the dominant creep mechanism,and the NPC samples have obvious anisotropy.In the PC samples,dynamic precipitation of large volume fraction of spherical Mg_(17)Al_(12) has inhibitory effect on the basaláañslip.The pyramidalác+añslip and twinning improve the creep anisotropy resistance significantly.

Simulation and reconstruction of particle trajectories in the CEPC drift chamber

The circular electron-positron collider(CEPC)is designed to precisely measure the properties of the Higgs boson,study electroweak interactions at the Z-boson peak,and search for new physics beyond the Standard Model.As a component of the 4th conceptual CEPC detector,the drift chamber facilitates the measurement of charged particles.This study implemented a Geant4-based simulation and track reconstruction for the drift chamber.For the simulation,detector construction and response were implemented and added to the CEPC simulation chain.The development of track reconstruction involves track finding using the combinatorial Kalman filter method and track fitting using the tool of GenFit.Using the simulated data,the tracking performance was studied.The results showed that both the reconstruction resolution and tracking efficiency satisfied the requirements of the CEPC experiment.

Fudan multi-purpose active target time projection chamber(fMeta-TPC)for photonuclear reaction experiments

Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fudan multi-purpose active target time projection chamber(fMeta-TPC)with 2048 channels was developed to studyα-clustering nuclei.This study focused on the photonuclear reaction with a laser Compton scattering gamma source,particularly for the decay of the highly excitedαcluster state.The design of fMeta-TPC is described in this paper.A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and ^(241)Amαsource.The results showed that the intrinsic angular resolution of the detector was within 0.30°,and the detector had an energy resolution of 6.85%for 3.0 MeVαparticles.The gain uniformity of the detector was approximately 10%(RMS/Mean),as tested by the ^(55)Fe X-ray source.

Effect of coil and chamber structure on plasma radial uniformity in radio frequency inductively coupled plasma

Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma(ICP)to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing.This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP.The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density.Furthermore,optimizing the coil within the ICP reactor,using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity,elevating it from 56%to 96%within the range of the model sizes.Additionally,when the chamber aspect ratio k changes from 2.8 to 4.7,the plasma distribution changes from a center-high to a saddleshaped distribution.Moreover,the plasma uniformity becomes worse.Finally,adjusting process parameters,such as increasing source power and gas pressure,can enhance plasma uniformity.These findings contribute to optimizing the etching process by improving plasma radial uniformity.

Clinical Effect Analysis of Posterior Chamber Intraocular Lens Implantation for Correcting High Myopia and Astigmatism

Objective:To explore the corrective effect of posterior chamber intraocular lens implantation with phakic eyes in the treatment of high myopia and astigmatism.Methods:From May 2023,the hospital began to collect the case data of diagnosis and treatment of high myopia and astigmatism.By May 2024,310 cases were included,all of which were treated with posterior chamber intraocular lens implantation.The visual acuity,astigmatism and axial position of the intraocular lens were observed before and after treatment.Results:At different time points after the operation,the patient’s vision was significantly improved compared with that before the operation(P<0.05),and the vision level was equal to or greater than the best-corrected vision before the operation.At different time points after the operation,the average rotation of the intraocular lens was less than 5 degrees.Astigmatism was significantly lower than that before the operation(P<0.05).After the operation,the intraocular pressure increased in 11 cases,accounting for 3.55%,with no adverse complications such as lens turbidity,glare and obvious halo occurring.Conclusion:The posterior chamber intraocular lens implantation with phakic eyes has an ideal correction effect in the treatment of high myopia and astigmatism,which can effectively improve the vision level of patients and reduce the degree of astigmatism,and has high effectiveness and safety.

罗丹明123经大鼠空肠黏膜的体外Ussing chamber渗透研究

目的:检测并评价罗丹明123(R123)经空肠黏膜渗透的特点,分析此法的可行性。方法:配制R123溶液,采用体外Ussing chamber实验法,考察R123经时经大鼠空肠黏膜吸收方向和分泌方向的累计透过量,并计算各自渗透系数。结果:R123吸收和分泌方向的表观渗透系数Papp(×10-5,cm.s-1)分别为(1.9±1.3)和(7.4±5.2),差异具显著性。结论:R123作为P-糖蛋白的底物,其经肠黏膜渗透以分泌方向为主;Ussing chamber实验用于评价药物在肠道内转运具有易操作,简便等特点,值得推广使用。

基于Ussing Chamber技术的红景天苷大鼠肠黏膜透过性研究

[目的]研究红景天苷在大鼠离体肠黏膜中的透过情况。[方法]采用Ussing Chamber技术,考察不同浓度红景天苷于大鼠肠黏膜透过情况,并考察维拉帕米(Ver)和十二烷基硫酸钠(SDS)对红景天苷大鼠肠黏膜透过的影响。[结果]不同浓度红景天苷在大鼠不同肠段的单位时间转运速率(Flux)随浓度升高而增大,不同肠段表观渗透系数(P_(app))无统计学差异(P>0.05)。Ver加入一定量的SDS后,红景天苷在回肠和结肠的P_(app)显著增加(P<0.01或P<0.05),当SDS浓度为2 g/L时,回肠P_(app)增加为对照组的2.76倍。[结论]红景天苷在大鼠全肠段均有吸收,且吸收具有浓度依赖性,以被动吸收为主,Ver对红景天苷大鼠各肠吸收无影响,SDS促进了红景天苷回肠和结肠吸收。

A Smog Chamber Facility for Qualitative and Quantitative Study on Atmospheric Chemistry and Secondary Organic Aerosol

In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.

Ussing Chamber技术在家禽肠道营养物质转运研究中的应用

本文简要介绍Ussing chamber(尤斯灌流)系统的基本构造和原理,总结Ussing chamber技术在家禽肠道营养物质转运中的应用,指出使用过程中可能存在的问题,并探讨解决问题的途径。

地塞米松磷酸钠脂质体经兔结肠粘膜的体外Ussing chamber渗透研究

目的观测并评价载药脂质体经结肠粘膜渗透的特点。方法制备地塞米松磷酸钠(DSP)脂质体,采用体外Uss-ing chamber 实验法,考察DSP经时经兔结肠粘膜的累积透过量及在粘膜内的分布量。结果和DSP溶液比较,DSP脂质体能延缓和减少DSP经结肠粘膜的透过量。DSP脂质体的表观渗透系数(×10-6,cm/s)为31.95±7.65,和DSP溶液(88.61±18.61)比较,具有显著差异。透过实验120 min和300 min时,DSP脂质体在结肠粘膜中的分布量均明显高于DSP溶液。结论和DSP溶液比较,DSP 脂质体在治疗局部结肠炎时,可能具有更小的毒性,更高的疗效,值得进一步开发研究。

全边壁条件下CASSON流体在Flow Chamber中流动特性的研究

针对Casson流体在FlowChamber中的流动问题，考虑全边壁条件，用Galerkin有限元方法对流场进行了分析，并将结果与平面应力假设条件下的牛顿流体和Casson流体的情况进行了比较。

Flow Chamber流动实验中非定常流动特性的研究

利用本征函数法得到了ＦｌｏｗＣｈａｍｂｅｒ流动实验中非定常流动的速度表达式。它不仅满足任意激励形式下的速度变化过程，而且可以描述速度从初始时刻到任意时刻的变化过程。

Ussing chamber在肠道屏障功能研究中的进展

该文作者对Ussing chamber(尤斯室,尤斯灌流室)的基本原理和构造作简要综述,并综合国外学者的研究进展,总结了Ussing chamber在肠道屏障功能研究中的应用。

Flow Chamber流动腔高度的数值研究

平行平板流动腔是当前研究不同切应力下细胞的变形特点的主要工具之一,通过ANSYS计算力学软件,对相同压力边界条件下不同高度的流动腔内的定常不可压粘性流体的流动进行了数值研究,发现FlowChamber流动腔底部切应力只有在离两端有一定距离的中间部分才是均匀分布的,而在入口和出口都有比较大的跳跃,入口处的切应力值明显要大于出口处.

Flow Chamber流动试验模型

从Navier-Stokes方程出发,运用无量纲化及虚宗量Bessel函数法求解。导得Flow Chamber系统中流体流动的速度场、切应力场等分布规律.并且,本文公式简化为定常状态时,无论是和Cao等人的理论结果,还是和他们的实验结果比较。都是相当一致的.

Early Development of Pollen Chamber in Ginkgo biloba Ovule

The early stage of pollen chamber development in ovule and the cytological mechanism of nucellar cell death were studied in Ginkgo biloba L. DNA ladder appearance and TUNEL assay demonstrated that the nucellar cell death, doomed to bring about pollen chamber formation, was a process of programmed cell death (PCD). A spatial distribution of PCD was visualized during the development of pollen chamber. Together with the observation under the scanning electron microscope, these results have revealed that the early developmental pattern of pollen chamber consists of four phases. Firstly, several layers of the nucellar cells at the micropylar end elongate longitudinally. Thereafter, the uppermost layer of the nucellar cells at the micropylar end initiate PCD; and the nucellar cell death extends in a basally and laterally oriented direction to form a cavity. Finally, the epidermal cells at the micropylar end detach from the other epidermis by dehiscence, bringing about the opening of the pollen chamber. The early development of pollen chamber begins sometime after the stage of megasporocyte and continues by the time of the formation of megaspore tetrad, and finally completes at the stage of development of female gametophyte. This shows a synchronous development of megaspore and pollen chamber.

Morphological Changes in Nucellar Cells Undergoing Programmed Cell Death (PCD) During Pollen Chamber Formation in Ginkgo biloba

Programmed cell death (PCD) of the nucellar cells at the micropylar end is involved in pollen chamber morphogenesis in Ginkgo biloba L. A development-course observation of the morphological changes in the nucellar cells undergoing PCD to form pollen chamber was performed. During the PCD, the nucellar cells degraded their cellular components through an orderly progression. Through the vactiolation, the cytosol was engulfed by the enlarging vacuole, leaving out various organelles, which remained morphologically integrated. As the vacuolation continued, the vacuole collapsed with the breakage of the tonoplast and the cytosol disappeared completely. Organelles were subsequently destroyed. Ultimately, nucellar cells digested away all of their cytoplasm, leaving with cell walls. They became collapsed as the nucellus developed. Intracellular membranes were strikingly changed, playing a role in leading to cell death. Some of these noticeable changes were the appearance of multivesicular body, multicycle-like membranes, membrane-bounded bodies containing some organelles, tonoplast rupture and numerous vesicles. The dehiscence of the apical epidermis, resulting in the opening, appeared to have followed two different pathways with one involving a specific epidermal cell autolysis and the other by detachment from middle lamella of two neighboring epidermal cells without cell autolysis. The specific epidermal cells had been dead prior to the dehiscence of the apical epidermis, which marked the sites of the dehiscence followed. In view of the changes in the cellular morphology, a process of nucellar cell PCD in the course of the pollen chamber formation was demonstrated.