Grain refinement of pure aluminum by direct current pulsed magnetic field and inoculation

The combined effects of direct current pulsed magnetic field （DC-PMF） and inoculation on pure aluminum were investigated, the grain refinement behavior of DC-PMF and inoculation was discussed. The experimental results indicate that the solidification micro structure of pure aluminum can be greatly refined under DC-PMF. Refinement of pure aluminum is attributed to electromagnetic undercooling and forced convection caused by DC-PMF. With single DC-PMF, the grain size in the equiaxed zone is uneven. However, under DC-PMF, by adding 0.05% （mass fraction） Al5Ti-B, the grain size of the sample is smaller, and the size distribution is more uniform than that of single DC-PMF. Furthermore, under the combination of DC-PMF and inoculation, with the increase of output current, the grain size is further reduced. When the output current increases to 100 A, the average grain size can decrease to 113 μn.

Effect of processing route on grain refinement in pure copper processed by equal channel angular extrusion

An experimental study of the microstructures in pure copper billets processed by 8 passes of equal channel angular extrusion （ECAE） via an extended range of processing routes with a 90° die is carried out. Each processing route is defined according to the inter-pass billet rotation angle （χ）, which varies from 0° to 180°. According to the generation of high-angle boundaries and reduction of grain size by electron backscatter diffraction （EBSD） measurements, the grain refinement is found to be most efficient for route with χ=90°and least efficient with χ=180°, among the seven routes studied. This trend is supported by supplementary transmission electron microscopy （TEM） measurements. Comparison of the EBSD and TEM data reveals the importance of considering the non-equiaxity of grain structures in quantitative assessment of microstructural differences in ECAE-processed materials.

EFFECTS OF TREATMENT TIME ON CORROSION OF DIFFUSION-ALLOYED COATINGS OF PURE MAGNESIUM

The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time （8, 16, and 24h）. The diffusion interaction effectiveness between Zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test （in 3.0% NaCl solution, temperature is （28±1）℃, and time is 96h）. Optical microscopy （OM） and EDS （energy dispersive spectrum） composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. It is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11Zn4 phase, which formed as a continuous phase due to the diffusion of Al, Zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones （especially the samples treated for 24h at 480℃）, was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of Al5Mg11Zn4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. It was concluded that the continuous Al5Mg11Zn4 phase （WP-zone） of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.

Grain refinement process of pure iron target under hypervelocity impact

The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The cross-section observation was performed to reveal the grain refinement process driven by plastic deformation. Firstly, low energy dislocation structures （LEDS） such as dense dislocation walls （DDWs） and dislocation tangles （DTs） refine the original grains and form intersecting lamellar structures. With increasing strain, DDWs and DTs transform into subboundaries with small misorientations to separate lamellar structure to cells. Subboundaries are converted to high misorientation grain boundaries, so ultrafine grains are formed. The formation of ultrafine grains was discussed in the dynamic recrystallization process due to the large strain and strain rate induced by spherical shock wave.

Implementation of Dynamic System Control Circuit Board Test System of Pure Electric Vehicles

The dynamic system control circuit board(DSCCB)is one of the most important components for dynamic system of pure electric vehicles. The current detection of the DSCCB is done manually, which is not only inefficient in the detection but also difficult to guarantee the data accuracy. In order to improve the detection efficiency and accuracy, a new testing system is designed by Labview. The total test time can be further reduced by about 75% compared with the results of the manual detection. In this paper, the three-parameter sine wave curve-fit algorithm theory is applied to the phase delay detection of the current sensor sampling circuit on the DSCCB. This method solves the problem of big error in the phase delay detection.

RETREATMENT WITH FLUDARABINE AND CYCLOSPORINE FOR ONE CASE OF REFRACTORY PURE RED CELL APLASIA

MANY cases of pure red cell aplasia （PRCA） were mediated by over-function of immune cells, and responded well to immunosuppressive therapy. Sometimes refractory cases also arose. Fludarabine is an analogue of adenosine resistant to deamination which is widely used for B-chronic lymphocytic leukemia （CLL） and other hematological malignancies.^2 As a strong immunosuppressive agent, fludarabine has generally been used in nonmyeloblative conditioning regimens for hematopoietic stem cells transplantation for hematological malignancies and severe aplastic anemia recently.^3 In this study,

Numerical and experimental investigations of weld pool geometry in GTA welding of pure aluminum

A 2-D numerical model was developed to predict the shape of weld pool in stationary GTA welding of commercial pure aluminium, without considering fluid flow in the weld pool. A Gaussian current density and heat input distribution on the surface of the workpiece were considered. The parameters of Gaussian distribution were modified by comparing calculated results with experimental ones. It was found that these distribution parameters are fimctions of applied current and arc length. Effects of arc length, applied current and welding time on the geometry of the weld pool were investigated. To check the validity of the model, a series of experiments were also conducted. In general, the agreement between calculated overall shape of the weld pool and the experimental one was acceptable, especially in low applied currents. Therefore, it can be concluded that in pure aluminium, the heat conduction is dominant mechanism of heat transfer in the weld pool.

Wigner Function：from Ensemble Average of Density Operator to Its Matrix Element in Entangled Pure States

We show that the Wigner function (an ensemble average of the density operator ρ, Δ is the Wigner operator) can be expressed as a matrix element of ρ in the entangled pure states. In doing so, converting from quantum master equations to time-evolution equation of the Wigner functions seems direct and concise. The entangled states are defined in the enlarged Fock space with a fictitious freedom.

Experimental and numerical investigation on pure aluminum by ECAP

The equal channel angular pressing(ECAP)experiments were carried out with industrial pure aluminum and an in-house mould.The comparison of material grain size before and after ECAP was performed by applying the technique of electron back scattered diffraction(EBSD).The results show that the grains in the material after ECAP are refined and the yield stress and ultimate strength are increased.In order to investigate the deformation mechanism during ECAP and the reason for driving grain size refinement,three-dimensional numerical simulations of the ECAP process were carried out.Based on the Lode parameter analysis, the deformation of the material sample is found very complicated,not just pure shear during extrusion through the angular channel. The simulation confirms that a strong strain gradient in the sample material is imposed by the ECAP.

Pure red cell aplasia caused by pegylated interferon-α-2a plus ribavirin in the treatment of chronic hepatitis C

Pure red cell aplasia (PRCA) is a rare hematological disorder which is characterized by severe anemia,reticulocytopenia and almost complete absence of erythroid precursors in bone marrow.The pathophysiology of PRCA may be congenital or acquired.To our knowledge,there is only one case report in the English literature of PRCA after pegylated interferon combination therapy for chronic hepatitis C.We report a second case of PRCA after pegylated interferon combination treatment for chronic hepatitis C.The diagnosis of PRCA was confirmed by the typical findings of bone marrow biopsy.The possible etiologies of our case are also discussed in this paper.

Shear deformation and grain refinement in pure Al by asymmetric rolling

Asymmetric rolling(ASR), as one of severe plastic deformation(SPD) methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymmetric rolling with pure aluminium as a model material. Effects of reduction ratio and mismatch ratio on the shear deformation were studied. With the observed shear deformation results, equivalent strain was calculated. For lager shear deformation, rolling equipment was modified to increase friction between specimen and the rollers. Consequently, extremely fine grains with size of 500 nm are obtained in pure aluminium. With improved asymmetric rolling, the ability of grain refinement of ASR is greatly improved.

Cosmic Dark Energy from ‘t Hooft’s Dimensional Regularization and Witten’s Topological Quantum Field Pure Gravity

We utilize two different theories to prove that cosmic dark energy density is the complimentary Legendre transformation of ordinary energy and vice versa as given by E(dark) = mc2 (21/22) and E(ordinary) = mc2/22. The first theory used is based on G ‘t Hooft’s remarkably simple renormalization procedure in which a neat mathematical maneuver is introduced via the dimensionality of our four dimensional spacetime. Thus, ‘t Hooft used instead of D = 4 and then took at the end of an intricate and subtle computation the limit to obtain the result while avoiding various problems including the pole singularity at D = 4. Here and in contradistinction to the classical form of dimensional and renormalization we set and do not take the limit where and is the theoretically and experimentally well established Hardy’s generic quantum entanglement. At the end we see that the dark energy density is simply the ratio of and the smooth disentangled D = 4, i.e. (dark) = (4 -k)/4 = 3.8196011/4 = 0.9549150275. Consequently where we have ignored the fine structure details by rounding 21 + k to 21 and 22 + k to 22 in a manner not that much different from of the original form of dimensional regularization theory. The result is subsequently validated by another equally ingenious approach due mainly to E. Witten and his school of topological quantum field theory. We notice that in that theory the local degrees of freedom are zero. Therefore, we are dealing essentially with pure gravity where are the degrees of freedom and is the corresponding dimension. The results and the conclusion of the paper are summarized in Figure 1-3, Table 1 and Flow Chart 1.

Structure of the Intermetallic Compound Ni_3Al Synthesized under Compression of the Powder Mixture of Pure Elements Part Ⅰ: Phase Composition and Microstructure of Main Phase

It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.

Structure of the Intermetallic Compound Ni_3Al Synthesized under Compression of the Powder Mixture of Pure Elements Part Ⅱ: Influence of Alloying by Boron on the Phase Composition and the Microstructure of Grains of the Main Phase

The Ni_3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni_3B phase has the size around 0.1μm and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the ofF-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concen- trations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with disloca- tions up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.

Pure Java Implementation of BSP

With the wide acceptance of the computing concept of cluster-based or cluster-of-clusters computing, network-based high performance computing is gaining increasing popularity among parallel computing community. Current parallel environments such as MPI (Message Passing Interface) or BSP (Bulk Synchronous Parallel) can not apply readily to heterogeneous computing platform. In order to exploit the maximum performance potential that a heterogeneous environment brings, we have made some experiments on implementing BSP in pure Java, a fully platform-independent language. The experimental results show that implementation of parallel libraries in Java is feasible and the performance is moderately acceptable. The paper describes our experiences in implementation of BSP in pure Java. Implementation and efficiency issues such as data transport, network communication, support thread, barrier synchronization and dynamic class loading mechanism are discussed in detail.

Cell Attachment of Periodontal Ligament Cells on Commercially Pure Titanium at the Early Stage

Summary: In order to study the character of periodontal ligament cells (PDLCs) attaching on commercially pure titanium (cpTi) by morphology and metrology on the early stage (24 h), 1×105/ml PDLCs in 2 ml culture medium were seeded on cpTi discs fixed in 24-well culture plates. Morphology of cell attachment was observed by contrast phase microscope, scanning electron microscope (SEM) and fluroscence microscopy. Cell adhesion was analyzed by MTT at 0.5, 1, 2, 4 h respectively. PDLCs could attach and spread on cpTi discs. SEM showed that PDLCs had pseudopod-like protuberance. PDLCs showed different attaching phases and reached saturation in cell number at 2 h. It was concluded that PDLCs had good biocompatibility with cpTi, and showed a regular and dynamic pattern in the process of attaching to cpTi.

Development and prospect of secondary refining technology for ultra pure ferritic stainless steel

Ultra pure ferritic stainless steel has more advantages in the performance than the ordinary ferritic stainless steel because of ultra low carbon and nitrogen content,such as corrosion resistance,toughness and weldability,etc.Such steel has therefore been applied in many fields,leading to the very rapid development over the past 40 years.This study focuses on the secondary refining process which is the most important step of the whole steelmaking process for the ultra pure ferritic stainless.Firstly,some difficulties of the secondary refining process are described,including the high purification in terms of both carbon and nitrogen contents, high efficient and stable control.Secondly,the development and progress of the secondary refining technology for ultra pure ferritic stainless is introduced in terms of the refining equipments,metallurgical process and assistant technologies.Finally,the prospect was made for the development of secondary refining process for ultra pure ferritic stainless in the future.

The surface treatment on oxide film of pure titanium Part 1. The effect of Anodic oxidation

目的：研究阳极氧化对纯钛种植材料氧化膜的影响。方法：5片直径9mm厚2mm的纯钛在升压速度为7～8v／min、电流密度≤10mA／cm。的条件下分别进行阳极氧化处理，（A）10v10min，（B）24v10min，（C）40v10min，（D）24v40min，（E）24v2h。用potentiostat仪检测以上样品在生理盐水和人造海水中的电化学行为。结果：以上样品的颜色呈：A蓝色，B淡黄色，C粉红色，D金黄色，E深黄色。随着电压的升高和作用时间的延长，2．55峰渐渐强化，2．34峰弱化。在生理盐水中，阳极氧化膜的开路电势稳定于0mV，而自然氧化膜则很快从一50上升到～40mV，极化电流比自然氧化膜的低100倍。在人造海水中，阳极氧化膜的开路电势稳定在-90mV，自然氧化膜则从-480mV快速上升到-310mV，且活化电流明显高于阳极氧化膜。结论：阳极氧化膜的颜色可能和膜的厚度有关，而颜色对种植体上的修复体有影响，因此，金黄色被选为理想的颜色。2．55和2．34峰的变化规律尚无法解释。阳极氧化膜的稳定性和耐腐蚀性远远高于自然氧化膜。因此，阳极氧化法是一种提高纯钛氧化膜耐腐蚀性的好方法。

A Probability Measure for Entanglement of Pure Two-Qubit Systems and a Useful Interpretation for Concurrence

A new probability measure for the quantification of entanglement of pure states is introduced.Numerical computations indicate that the derived measure is equal to concurrence,up to the precision of the computer program used.Hence it also provides a physical interpretation for concurrence.

Construction of Pure Mendelsohn Triple Systems

This paper determined the existence of λ-fold pure Mendelsohn triple system of order v satisfying λv(v-1)≡0 (mod 3) and v≥4λ+5, or v=2λ+2, and in the case of λ=4,5,6,which completely settled their existence.