Evaluation of beta-lactoglobulin as a stationary phase in high-performance liquid chromatography and as a buffer additive in capillary electrophoresis: observation of a surprising lack of stereoselectivity

Recently, cDNAs encoding brain-specific transmembrane-type protein tyrosine phosphatases (PTPs) with single catalytic domain have been cloned. These include PC12-PTP, PCPTP1, PTPBR7, and PTP-SL, whose cytoplasmic domains had high similarity to STEP, a brain-specific nontransmembrane-type PTP. Based on the high similarity and expression pattern, PCPTP1 seems to be identical with PC12-PTP1 and to be the rat homologue of murine PTPBR7. Here, we report the molecular cloning and expression profile of PCPTP1-Ce, a variant of PCPTP1. Both PCPTP1 mRNA and PCPTP1-Ce mRNA seem to be derived from a single common region gene. Nucleotide and deduced amino acid sequence comparison between PCPTP1-Ce and PCPTP1 revealed that the predicted protein product of PCPTP1-Ce is identical with that translated from the third initiation methionine of the longest ORF of PCPTP1, and that these two clones differ in the 5'-untranslated sequences. Northern blot analyses with specific probes for PCPTP1 and PCPTP1-Ce confirmed our previous observation that PCPTP1-Ce mRNA was almost exclusively expressed in the cerebellum, whereas PCPTP1 was widely expressed in various brain regions dissected including cerebellum. In situ hybridization study demonstrated that PCPTP1-Ce mRNA was exclusively expressed in Purkinje cells of the cerebellum. In contrast, PCPTP1 mRNA was predominantly expressed in granule cells and less in Purkinje cells. Moreover, immunohistochemical analysis using an affinity-purified polyclonal antibody raised against the cytoplasmic region of PCPTP1/PCPTP1-Ce demonstrated that Purkinje cells were strongly immunostained, whereas granule cells were stained only faintly in the cerebellum. These observations clearly demonstrated that PCPTP1-Ce mRNA and its protein products are expressed in Purkinje cells and suggest that PCPTP1-Ce may play an important role in Purkinje cell function in the rat cerebellum.     

Structure and Magnetic Properties of Sm2Fe17Nx Sintering Magnets Prepared by Spark Plasma Sintering

Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated. As a result, the density of the magnet is obviously improved with the increase of sintering pressure, but the coercivity drops since Sm2Fe17Nx has decomposed into SmN, α-Fe and N2. When sintering temperature was only above 200 ℃ under 1 GPa sintering pressure, the coercivity even begins to decrease, which indicates that high pressure promotes the decomposition of the Sm2Fe17Nx at lower temperature. The decomposition is also proved by the decrease of nitrogen and increase of α-Fe in the magnets.     

The influence of pressure on crystallisation of amorphous Zr70Cu30 alloy—I. Crystallisation temperature and the crystallisation phases

The pressure dependence of the crystallisation temperature of amorphous Zr₇₀Cu₃₀ alloy and the variation of its crystallisation phases under high pressure annealing were investigated by electrical resistivity measurement and X-ray diffraction method. The results show that pressurising generally raises the crystalisation temperature, but slightly decreases it at the early stage of compression. Evident changes in crystallisation phase in the alloy were also observed under high pressure annealing. At atmosphere pressure, the crystallisation products are CuZr₂ with a modicum of α-Zr, while at a pressure of 2 GPa, the alloy crystallises into a mixture consisting of CuZr₂, Cu₁₀Zr₇ and an appreciable amount of α-Zr. The origin of these observations is discussed.     

Classification of ballas and carbonado synthetic polycrystalline diamonds

The structure of diamond polycrystals synthesized at different pressures is studied. The direction of crystallite growth in the polycrystals depends on the pressure. On that basis, polycrystalline diamonds may be classified. In the synthesis of polycrystalline diamonds from isotropic graphite, ballas crystals are formed at 6.0–6.5 GPa, carbonado crystals at 11.0–12.0 GPa, and polycrystals of intermediate type at 7.5–9.0 GPa.     

Electron back-scattering diffraction preliminary analysis of heterogeneous nuclei in magnesium alloy during solidification process under GPa high pressure

The effective heterogeneous nuclei in Mg-7.92 Zn-1.70 Y alloy during solidification process under high pressure was investigated by EBSD. It is found that the orientation relationship between Mg matrix and MgY phase, [111]_(MgY)//[1210]_(α-Mg) and(101)_(MgY)//(0001)_(α-Mg), exists between Mg matrix and MgY phase.The MgY phase is the potential heterogeneous nuclei substrate for a-Mg solidified under high pressure. It is calculated by Bramfitt mode that the mismatch between Mg matrix and MgY phase is greater than 12% under atmospheric pressure. When solidified under high pressure of 4 GPa, the solidification pressure can increase the number of the α-Mg nucleus by reducing the size of the nucleus, decreasing interfacial energy of MgY/a-Mg, and changing the wettability between MgY phase and α-Mg from non-wetting under atmospheric pressure to wetting under high pressure. The MgY phase becomes a powerful heterogeneous nuclei for α-Mg crystal. Increasing the number of valid heterogeneous nuclei substrate increases nucleus number and refines the grain of the alloy.     

高压热处理诱导工业纯铁马氏体相变

 为了研究高压下马氏体组织形态特征及高压淬火马氏体相变机制,利用CS-1V型六面顶高压设备、在3、4和5 GPa高压下对工业纯铁进行热处理,利用SEM、EBSD等分析手段研究了高压淬火对工业纯铁马氏体组织形态及力学性能的影响。结果表明,GPa级高压下奥氏体化后,工业纯铁以6 ℃/s冷却速率就能淬火获得马氏体。3 GPa下,工业纯铁淬火马氏体呈现典型的低碳马氏体组织形貌;4 GPa下,其板条马氏体形成过程与典型的片状马氏体类似,先形成的板条束贯穿整个奥氏体晶粒并将其分割,后形成的板条束尺寸大小受限;5 GPa下,以协作方式通过母相转变为马氏体的“协作方阵”数量多、尺寸小、整齐性高,并多呈“梯形”生长。5 GPa下淬火工业纯铁的力学性能接近常压下淬火的0.2%C钢水平,硬度达415HV,屈服强度达700 MPa。     

Microstructure and compression deformation behavior in the quasicrystalreinforced Mg-8Zn-1Y alloy solidified under super-high pressure

The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of ■-Mg and quasicrystal I-Mg3Zn6 Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase(quasicrystal I-Mg3Zn6Y) was transformed from continuous network(ambient pressure) to long island(high pressure) and finally to granular(super-high pressure) with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.     

Investigation into high-pressure behavior of MnTiO3: X-ray diffraction and Raman spectroscopy with diamond anvil cells

The structural stability of manganese titanate MnTi03 at high pressure was investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. Ilmenite-type MnTiO3 is stable at least to 26.6 GPa, and lithium niobate type MnTi03 reversibly transforms at room temperature to perovskite at 2.0 GPa. Bulk moduli (K300) of ilmenite, lithium niobate and perovskite are 174(4) GPa, 179 (8) GPa, and 208(5) GPa, respectively (at fixed first pressure derivative K'＝4). The Gruneisen parameter y has been estimated to be 1.28 for ilmenite and 1.75 for perovskite. In ilmenite phase, Ti06 octahedra become more regular with increasing pressure. In perovskite phase structural distortion increases with pressure increase.     

Room temperature compressive properties and strengthening mechanism of Mg_(96.17)Zn_(3.15)Y_(0.50)Zr_(0.18) alloy solidified under high pressure

The microstructures of Mg_(96.17)Zn_(3.15)Y_(0.50)Zr_(0.18) alloys solidified under 2-6 GPa high pressure were investigated by employing SEM(EDS) and TEM.The strengthening mechanism of experimental alloy solidified under high pressure is also discussed by analyzing the compressive properties and compression fracture morphology.The results show that the microstructure of experimental alloy becomes significantly fine-grained with increasing GPa level high pressure during solidification process,and the secondary dendrite arm spacing reduces from 40 μm at atmospheric pressure to 10 μm at 6 GPa pressure.The morphology of the second phases changes from the net structure by the lamellar-type eutectic structure at atmospheric pressure to discontinuous thin rods or particles at 6 GPa pressure.Besides,the solid solubility of Zn in the Mg matrix is improved with the increase of the solidification pressure.Compared with atmospheric-pressure solidification,high-pressure solidification can improve the strength of the experimental alloy.The compressive stre ngth is improved from 263 to 437 MPa at 6 GPa.The fracture mechanism of the experimental alloy changes from cleavage fracture at atmospheric pressure to quasi-cleavage fracture at high pressure.The main mechanism of the strength improvement of the experimental alloy includes the grain refinement strengthening caused by the refinement of the solidification microstructure,the second phase strengthening caused by the improvement of the morphology and distribution of the second phases,and solid solution strengthening caused by the increase of the solid solubility of Zn in the Mg matrix.     

Raman and luminescence studies on phase transition of EuNbO4 under high pressure

Raman and luminescence studies on the phase transition of europium orthoniobates(EuNbO4) under high pressure were performed. The pressure dependent Raman spectra revealed that an irreversible phase transition from monoclinic phase to M'-fergusonite phase of EuNbO4 occurred at 7.3 GPa, and the two phases coexisted over a pressure range from 7.3 to 13.7 GPa. An obvious discontinuity on luminescence intensity ratio between 5D0 →7F2 and 5D0→7F1 transitions was observed with increasing pressure, indicating also that a phase transition occurred at 7.3 GPa, which was in agreement with the high pressure Raman spectra data. Meanwhile, the Raman and luminescence spectra in the temperature range of 20–300 K showed the structure stability at low temperatures.     

Structure and properties of superfine-grained iron compacted out of ultradisperse powder

The surface of the ultra-disperse iron powder particles was oxidized being in contact with the air. The powder was compacted under pressure plus torsion straining. The oxide film was found to dissolve during intensive deformation under pressure. A high degree of cold working of the resulting system FeO results in the formation of a fairly high-disperse structure during annealing. A spontaneous decay of the oversaturated solid solution at 600°C and the resulting microduplex structure comprised of the α-Fe grains sized 300 nm and FeO particles sized 200 nm leads to substantial strengthening of the alloy. The sample hardness reaches 4.7 GPa, which is higher than the hardness of original torsion strained samples.     

钠在320GPa高压下的电子结构和光学性质的第一性原理研究

利用基于密度泛函理论（DFT）的广义梯度近似（GGA）研究了320GPa高压下钠的电子结构和光学性质．给出了其沿布里渊区高对称轴的能带结构、态密度（DOS）和分态密度（PDOS）。并计算了介电函数ε（ω）,反射率R（ω）,能量损失函数L（ω）,光吸收系数I（ω）,光导率σ（ω）,折射率n（ω）,以及消光系数k（ω）,用以讨论高压下钠的光学性质。     

Low elastic modulus Ti–17Nb processed by powder injection moulding and post-sintering heat treatments

Abstract

Ti–Nb alloys are attractive as biomaterials because of their excellent combination of low elastic modulus, high strength, corrosion resistance and enhanced biocompatibility. The effect of a post-sintering quenching treatment on the microstructure and mechanical properties of powder injection moulded Ti–17Nb has been investigated. Tensile test specimens were produced using a feedstock based on blended elemental powders, some of which were solution-treated in the β phase field and water quenched. Both as-sintered and quenched alloys had densities 95·5% of theoretical. The as-sintered material showed an α?β structure, whereas after quenching a fully martensitic α″ structure was obtained. The modulus of elasticity of the water-quenched alloy (～45 GPa) was about 40% lower than that of the as-sintered alloy (～76 GPa).     

A technique for obtaining shock-wave parameters using wave superposition in low-carbon steel

A novel experimental set-up for obtaining shock-wave superposition is described. Detonation is simultaneously initiated at the two opposite sides of an explosive layer placed directly in contact with a steel block. It was possible to take advantage of thea (bcc) → ε (hcp) →α (bcc) transformation occurring in iron at approximately 13 GPa in a unique fashion. The pressure of the two converging pulses is approximately 13 GPa, resulting in little or no transformation. However, in the region of superposition of the two waves the pressure is much higher.Post explosionem observation of the microstructure allowed an easy identification of the region of superposition, because of the profuse transformation “debris”. Events conducted for three thicknesses of the explosive layers allowed conclusions to be drawn about the changes of rarefaction and attenuation rates. The interactions occurring between the waves due to simultaneous superposition and transformation are thought to be responsible for internal spalling. Formerly with the Department of Metallurgical Engineering, South Dakota School of Mines and Technology     

Formation of Polycrystalline Boron Carbide B4C with Elevated Fracture Toughness

We have studied the processes of formation of high-density polycrystalline boron carbide B₄C during sintering under high pressure (5.5 GPa) and at high temperature (2200 K). Study of the structure by transmission electron microscopy showed that under the indicated conditions for sintering B₄C powders with original particle size range 2–80 µm, processes of primary recrystallization occur, as a result of which interlayers of nanodispersed grains (10–50 nm) are formed in the near-surface regions of the original coarse grains. The microhardness of such material is 41 GPa, and the fracture toughness is 7.2 MPa · m^1/2.__________Translated from Poroshkovaya Metallurgiya, Nos. 1–2(441), pp. 90–101, January–February, 2005.     

纳米AlN粉末的低温热压

研究了纳米AlN陶瓷在1 500~1 700℃的低温热压行为和力学性能.热压温度为1 600℃时,产物是β-AlN和β-Al2O3两相共存;当温度提高至1 700℃后,热压过程中出现由β-AlN到α-AlN相的转变.随着热压温度的提高,断裂形式由沿晶断裂逐渐向穿晶断裂转变,致密度逐渐提高,晶粒尺寸长大;当热压温度达到1 700℃时,相对密度为97.3%,晶粒平均直径为850nm,硬度值为15.54GPa,断裂韧度为3.5 MPa·m1/2.     

Photoluminescence study of SiO₂ coated Eu³⁺:Y₂O₃ core-shells under high pressure

Uniform core-shell Eu3+:Y2O3/SiO2 spheres were synthesized via precipitation and the Stber method.The structural transition of core-shell Eu3+:Y2O3/SiO2 was studied by using high pressure photoluminescence spectra.With pressure increasing,the emission intensities of 5D0→7F0,1,2 transitions of Eu3+ ions decreased and the transition lines showed a red shift.The relative luminescence intensity ratio of 5D0→7F2 to 5D0→7F1 transitions decreased with increasing pressure,indicating lowering asymmetry around Eu3+ ions.During compression,structural transformation for cores in the present core-shell Eu3+:Y2O3/SiO2 sample from cubic to monoclinic took place at 7.5 GPa,and then the monoclinic structure turned into hexagonal above 15.2 GPa.After the pressure was released,the hexagonal structure transformed back to monoclinic and the monoclinic structure was kept stable to ambient pressure.     

La-Ce共掺杂制备La3+-Ce3+/ZnO及其对亚甲基蓝的光催化降解

采用溶胶凝胶法制备了La-Ce共掺杂的La3+-Ce3+/ZnO光催化剂,同时用同种方法制备了ZnO、La3+/ZnO和Ce3+/ZnO以作对比.通过X射线衍射仪、透射电镜、紫外可见分光光度计,比表面及孔隙度分析仪等对制备的光催化剂进行了表征.以亚甲基蓝为模型污染物对所制备的光催化剂的光催化特性进行了评价.结果表明,所制备的La3+-Ce3+/ZnO光催化剂基本呈长方柱状,尺寸平均为57.3 nm,La-Ce共掺杂提高了ZnO的结晶度,促进了晶粒的长大.根据光催化实验结果,La-Ce共掺杂能够显著提高ZnO的光催化活性.在光催化降解500 mL的10 mg·L-1亚甲基蓝实验中,La3+-Ce3+/ZnO光催化剂对亚甲基蓝的降解率达93.7%,比纯ZnO、La3+-ZnO和Ce3+-ZnO分别提高了21.4%、19.2%和9.3%.      

Compton scattering studies and electronic properties of cerium

Experimental electron momentum density of γ-Ce was measured at an intermediate resolution (0.38 a.u.) using 20 Ci 137Cs Compton spectrometer. The experiment was compared with the first ever theoretical Compton profiles computed using spin polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method within atomic sphere approximation; and linear combination of atomic orbitals (LCAO) within generalised gradient approximation (GGA) and recently developed second order generalised gradient approximation (SOGGA). It was seen that the Compton profile derived from LCAO with GGA and SOGGA schemes gave a reasonable agreement with the experimental Compton line shape. Theoretical anisotropies in Compton profiles derived along [100], [110] and [111] directions were explained in terms of degenerate states in the energy bands.     

高耐热性金刚石复合材料的高压合成及其物相研究

如何提高金刚石等超硬材料的耐热性对其应用具有着重要意义.本文报道了在高温高压(HPHT,5～6 GPa,1 620～1 720 K,3～5 min)烧结条件下块体金刚石复合材料(D-cBN-B4C-Co-Al-Si)的合成和表征工作.实验结果表明,在烧结样品中存在金刚石,cBN,B_4C,B_xSiC,AlCo,AlN等物相.值得注意的是,合成样品的初始氧化温度为1520 K,其值远远高于金刚石,cBN和B_4C的初始氧化温度.高热稳定性归因于在烧结过程中形成B—C、C—Si共价键和B_xSiC固溶体.该项研究获得的成果有助于制备具有耐高温的复合超硬材料.