Resonance-enhanced multiphoton ionization spectroscopy on the B′2Σ+ and B2Π states of NS

Resonance-enhanced multiphoton ionization （REMPI） spectra of N^32S and N^34S have been recorded in the range of 35700-40200 cm^-1. The radical was generated by a pulsed dc discharge of a mixture of SF6 and N2 under a supersonic free jet condition. All the 16 observed bands of N^32S radicals have been assigned, among which 12 bands belong to three transition progressions （v′=0-4, 0）, （v′=1-4, 1） and （v′=2-4, 2） from the X^2П ground state to the B′^2∑^＋ upper state and the rest correspond to （9, 0）, （10, 0）, （11, 0） and （12, 0） bands of B^2П-X^2П transition, respectively. Analysis of the rotationally resolved spectra yields exhaustive spectroscopic constants of both the X^2П ground state and the B′^2∑^＋ excited state. The electronic transition bands of the isotopic molecule N^34S have been rotationally analyzed for the first time and the rotational constants of the ground and upper states have been determined simultaneously.     

Formation, structure and properties of GeCn± and Ge2Cn± binary clusters

The binary cluster ions Ge₂C_n⁺/Ge₂C_n^- and GeC_n⁺ have been produced by laser ablation. The parity effect is present in the negative ions Ge₂C_n^-, though it is not very prominent. While the experiments tell that the parity effect is totally not shown in the positive ions Ge₂C_n⁺. An extensive theoretical investigation on GeCn/GeC_n⁺/GeC_n^-(n=1-10) and Ge₂Cn/Ge₂C_n⁺/Ge₂C_n^-(n=1-9) has been carried out by density functional theory at B3LPY level. The calculation shows that the low-lying states of GeC_n/GeC_n⁺/GeC_n^-(n=1-10) and Ge₂C_n/Ge₂C_n⁺/Ge₂C_n^-(n=1-9) are linear structure with germanium atoms locating at terminals respectively. The electronic distributions, ionization potential (IP_ad), elec-tron affinity (EA) and increasing bonding energy reveal that the parity effect of neutral species is much stronger than that of ions, which is attributed to the valence π-electrons. It is explained that the differences between experiments and cal-culations are due to the kinetic factor in the formation of Ge₂C_n^±.     

嗜麦芽黄单胞菌催化生产α－熊果苷的菌种选育

利用硫酸二乙酯和紫外线对嗜麦芽黄单胞菌（Xanthomonas maltophilia ）复合诱变，初筛和复筛后，得到了转化率高且遗传性能稳定的α－熊果苷生产菌株BT-112。该菌株在以蔗糖为碳源、发酵液初始pH为7.5，温度为28℃，摇床转速为150r/min及发酵时间为48h的条件下,对苯二酚转化为α－熊果苷的转化率可达93.2％，比出发菌株转化率（73.0％）提高了27.7%。纯化产物经NMR鉴定，与标准品对比，确定为α－熊果苷。     

Synthesis and performance of Ca-α/β-SiAlON composites from tailings

Ca-α/β-SiAlON composites were prepared using Ca-α/β-SiAlON powder synthesized from gold ore tailings, which contained abundant Si and Al elements as the major raw materials together with minor additives, through a pressure-less sintering method. The influences of sintering temperature on the phase composition and microstructure of the composites were analyzed. The scanning electron microscopy images of the composites show the interlacing of grains with elongated columnar, short columnar and plate-like morphologies. The composites sintered at 1520℃ for 6 h have a flexural strength of 352 MPa, Vickers hardness of 11.2 GPa, and fracture toughness of 4.8 MPa·m1/2. The relative content of each phase in the products is I(Ca-α-SiAlON):I(β-SiAlON):I(Fe₃Si) = 23:74:3, where I_i stands for the diffraction peak intensity of phase i.     

Phase equilibria, diffusion growth and diffusivities in Ni-Al-Pt system using Pt/β -NiAl diffusion couples

The phase equilibria,diffusion growth and diffusivities in the Ni-Al-Pt system at 1 150,1 200 and 1 250℃were studied using Pt/β-NiAl diffusion couples.Based on the measured concentration profiles coupled with the local equilibrium hypothesis,the tie-lines between neighboring phases were determined.Two intermediate phases,Pt_3Al andα-NiPt(Al),are found to develop between the Pt andβ-NiAl couples.The thicknesses of Pt_3Al andα-NiPt(Al) layers varies linearly with the square of annealing time, indicating th...     

Microstructure investigation and multicolor upconversion in Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho) ions doped α-Sialon

Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)-α-sialon ceramics were fabricated by hot press sintering technique.Their microstructure and luminescent properties were studied by XRD,EDS,HRTEM and photoluminescence measurements.The results showed that the sintered ceramics consisted ofα-Sialon with a trace amount ofβ-Sialon phase.The frequency upconversion and downconversion properties of Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)-α-Sialon ceramics were investigated under 980 nm low-power excitation.The different concentrations of Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)produced multicolor emissions characteristics of each Ln~(3+)ion as a result of the energy transfer from Yb~(3+)to Er~(3+),Tm~(3+)and Ho~(3+)ions.The EDS spectra measurements and mappings showed that the Ln~(3+)ions were well incorporated in theα-Sialon matrix.Temporal evolution of the emission decay behavior has been investigated to understand the energy transfer mechanism.     

Effect of Aβ1-40 on membrane permeability and intracellular free Ca2+ of nerve cells

The effects of soluble and fibrillar Aβ1-40 on membrane permeability and intracellular free Ca^2 of nerve cells were investigated by the laser confocal microscopy. Results indicate that: i) Effects of soluble and fibrillar Aβ1-40 on cell membrane permeability are both concentration-dependent. Soluble Aβ1-40 increases membrane permeability only at concentration of 3μmol/L, while the toxic effect of fibrillar Aβ1-40 is much stronger, its evident effect begins from 1μmol/L. When its concentration rose to 3μmol/L, not only the membrane permeability increased, but also the nuclear membrane broke seriously, ii) Both soluble and fibrillar Aβ1-40 at high concentrations increased the intracellular free Ca^2 , and the increased amplitudes are concentration-dependent. However, the fibrillar one induces the increase of intracellular Ca^2 much quicker and synchronously.These results indicate that some correlation exists between the neurotoxicity of high concentration soluble and fibrillar Aβ1-40 and the change of physico-chemical properties and intracellular Ca ion imbalance.     

高电荷态离子40Arq+与Au表面作用产生的X射线谱

利用光谱技术研究了高电荷态离子⁴⁰Ar^q+(q= 16, 17, 18)离子入射金属Au表面产生的X射线谱. 分析结果表明, Ar的Kα-X射线是离子在与固体表面相互作用过程中在固体表面之下形成的空心原子发射的. 当电子组态为1s²的高电荷态Ar¹⁶⁺离子在金属表面中性化过程中, 存在着多电子激发过程使Ar¹⁶⁺的K壳层电子激发产生空穴, 进而级联退激发射 Ar 的 Kα特征 X 射线. 入射离子的Kα-X射线产额与其最初的电子组态有关, 靶原子的X射线产额与入射离子的动能有关.     

T2分子X1Σg+,B1Σu+和C1Πu态的势能函数

 使用SAC/SAC-CI和D95++^**,6-311++g^**及cc-PVTZ基组,分别对T₂分子的基态X¹Σ_g⁺+、第2激发态B¹Σ_u⁺和第3简并激发态C¹Π_u的平衡结构和谐振频率进行优化计算.对所有计算结果进行比较,得出cc-PVTZ基组为最优基组.运用cc-PVTZ基组和SAC方法对基态X¹Σ_g⁺+,SAC-CI方法对激发态B¹Σ_u⁺和Cu 进行单点能扫描计算,并用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由得到的势能函数计算了与X¹Σ_g⁺+,B¹Σ_u⁺和C¹Π_u态相对应的光谱常数,结果与实验数据吻合.     

S 100A8 mediates the activation of P65/HLA- B/S 100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinogenesis

S100 calcium binding protein A8 （S100A8）, a possible novel member of NF-kappa B signal pathway in laryngeal squamous cell carcinoma （LSCC）, interacts with human leukocyte antigen B （HLA-B） which carries an NF-kappa B binding site within the enhancer A. The objective of this study was to explore the molecular mechanism of S100A8 in laryngeal carcinogenesis. RT-PCR, Western blotting and immunohistochemistry staining were applied to evaluate the expression levels of IKKα, P65, REL-B, S100A8, APAF-1 and BCL-2 genes. The signal transduction passway in which S100A8 might participate was explored by RNA interference. Flow cytometry, TUNEL assay and cell invasion in vitro were used to detect the biological behavior of Hep2 cells induced by S100A8 gene. Our results showed that high expression of S100A8 was related to tumorigenesis in LSCC and negatively correlated with the degree of differentiation, indicating that S100A8 gene could inhibit apoptosis and promote metastasis in LSCC. Additionally, the suppression of S100A8 by RNA interference down-regulated BCL-2 but not APAF-1, P65 and IKKα, while, the suppression of P65 could significantly down-regulate the expression of S100A8 gene. In conclusion, S100A8 plays an important role in P65/HLA-B/S100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinoma.     

S100A8 mediates the activation of P65/HLA-B/S100A8/BCL-2/Caspase-9 (-3) pathway in laryngeal carcinogenesis

S100 calcium binding protein A8 (S100A8),a possible novel member of NF-kappa B signal pathway in laryngeal squamous cell carcinoma (LSCC),interacts with human leukocyte antigen B (HLA-B) which carries an NF-kappa B binding site within the enhancer A. The objective of this study was to explore the molecular mechanism of S100A8 in laryngeal carcinogenesis. RT-PCR,Western blotting and immuno-histochemistry staining were applied to evaluate the expression levels of IKKα,P65,REL-B,S100A8,APAF-1 and BCL-2 genes. The signal transduction passway in which S100A8 might participate was explored by RNA interference. Flow cytometry,TUNEL assay and cell invasion in vitro were used to detect the biological behavior of Hep2 cells induced by S100A8 gene. Our results showed that high expression of S100A8 was related to tumorigenesis in LSCC and negatively correlated with the degree of differentiation,indicating that S100A8 gene could inhibit apoptosis and promote metastasis in LSCC. Additionally,the suppression of S100A8 by RNA interference down-regulated BCL-2 but not APAF-1,P65 and IKKα,while,the suppression of P65 could significantly down-regulate the expression of S100A8 gene. In conclusion,S100A8 plays an important role in P65/HLA-B/S100A8/BCL-2/Caspase-9 (-3) pathway in laryngeal carcinoma.     

Mutagenesis of Ser24 of Cytochrome b559 α Subunit Affects PSII Acitivies in Chlamydomonas reinhardtii

In order to study the functions of cytochrome b559 (Cyt b559) in photosystem two (PSII) activity, mutant S24F of Chlamydomonas reinhardtii was constructed using site directed mutagenesis, in which Serine24 (Ser24) locating downstream of Histidine23 (His23) in α subunit of Cyt b559 was replaced by Phenylalanine (Phe). Physiological and biochemical analysis showed that mutant S24F could be grown photoautotrophically or photoheterotrophically. However, their growth rate was slower either on HSM or TAP medium than that of the control; Analysis of PSII activity revealed that its oxygen evolution was about 71% of wild type (WT); The Photochemical efficiency of PSII (Fv/Fm) of S24F was reduced 0.23 compared with WT; S24F was more sensitive to strong light irradiance than the wild type; Furthermore, SDS-PAGE and Western-blotting analysis indicated that the expression levels of α subunit of Cyt b559, LHCII and PsbO of S24F were a little less than those of the wild type. Overall, these data suggests that Ser24 plays a significant role in making Cyt b559 structure maintain PSII complex activity of oxygen evolution although it is not directly bound to heme group.     

Theoretical calculation of the finishing rolling elongation in alloying non-quenched and tempered steel

The finishing rolling elongation δ of the alloying non-quenched and tempered steel is calculated with the covalent electron number n_A of the strongest bond of the alloying phases and the interface electron density difference Δ_ρ of the phase interfaces. The calculations show that the elongation δ^α-Fe of the matrix α-Fe decreases with rolling refinement, the elongation δ^α-Fe-C-M of solid solution phases (M denotes alloying element) is inversely proportional to the covalent electron number n^α-Fe-C-M_A of the strongest bond, the elongation decrement Δ^{δα-Fe/α-Fe-C-M} caused by interface strengthening is directly proportional to the interface electron density difference Δρ^{α-Fe/α-Fe-C-M}, but the elongation decrements Δδ^α-Fe/MC^C₁ and Δδ^α-Fe/MC^C₂ caused by dispersion strengthening and precipitation strengthening respectively are directly proportional to the ratio of the electron density difference Δρ^α-Fe/MC^C₁ and Δρ^α-Fe/MC^C₂ of the strengthening interfaces to Δρ^{α-Fe/α-Fe-C} of the basic interface α-Fe/α-Fe-C. Therefore, the finishing rolling elongation of the alloying non-quenched and tempered steel is considered to be subtracting all the elongation decrements of solution strengthening, interface strengthening, dispersion strengthening and precipitation strengthening from the elongation of the refined α-Fe matrix. The calculation formulas in this paper are integrated with the proposed ones of σ_S, σ_b and of α_K delivered in another paper, the finishing rolling mechanical properties can be achieved and the calculated results agree well with the measured ones.     

Na(THF)2(μ2-η5-Cp)(η5,η5,η1-Cp3Yb)(THF)]n: The synthesis and X-ray structure of an anionic organolanthanidepolymer formed via self-assembly

Cp2Yb·2THF reacts with CpNa in 1：1 molar ratio in THF at 40℃ for 2 h, and the in situ generated anionic divalent complex NaYbCp3（THF）n reacts further with an excess of CpH at 40℃ for 48h, after work-up, affording the trivalent anionic ytterbium complex[Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF）]n：（1） by oxidation reaction of Cp2Yb with CpH. Crystal structure determination reveals that complex 1 has one-dimension polymeric chains of distinct Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF） units, which were formed by the coordination of the bridging Cp ligand with Cp3Yb＇THF and Na（THF）2 in η^5,η^5 mode via self-assembly.     

Crystal structures of catalytic and regulatory subunits of rat protein kinase CK2

Protein kinase CK2 consists of two catalytic subunits (CK2α) and two regulatory subunits (CK2β). Here, we report the crystal structures of rat CK2α mutant (rCK2α-△C, 1—335) and CK2β (rCK2β). The overall topology of rCK2α-△C and rCK2β are very similar to the human enzyme, although large structural differences could be observed in the N-terminal domain of rCK2α-△C. Our reported structure of rCK2α-△C is in the close conformation state while the counterpart hCK2α is in the open conformation state, indi- cating ...     

直流脉冲放电产生SO分子束:A'3→X3∑-跃迁

采用直流脉冲高压对SO₂/He(配比1:99,总压强3.0×10⁵Pa)混合气体放电产生SO超声分子束,SO自由基由电离其前体SO₂再解离而形成．发射光谱中350~500 nm波长范围的电子振动谱标识为SO(A'³→X³∑^-)跃迁,通过对实验谱线拟合,获得了该跃迁的带源ν₀₀ = 29524(8) cm^-1,SO(A'³Δ)的光谱常数ω'_e = 742(6) cm^-1, ω'_eχ'_e = 5.9(2.0) cm^-1, 以及基电子态的光谱常数ω'_e = 1165(5) cm-1, ω'_eχ'_e = 6.4(0.5) cm^_-1.     

Deformation and damage behaviors of as-cast TiAl-Nb alloy during creep

By means of creep properties measurement and microstructure observation,the deformation and damage behavior of an as-cast TiAl-Nb alloy during creep at temperature near 750°C were investigated.The results showed that the microstructure of the alloy consisted of lamellarγ/α_2 phase,and the boundaries consisted ofγphase located in between lamellarγ/α_2 phases with different orientations.In the latter stage of creep,the dislocation networks appeared in the interfaces of lamellarγ/α_2 phases due to the coarsening of them,which made the coherent interface transforming into the semi-coherent one for reducing its adhesive strength.The deformation mechanism of the alloy during creep was twinning and dislocations slipping within lamellarγ/α_2 phases.In the later period of creep,significant amount of dislocations plied up in the interfaces of lamellarγ/α_2 phases,which may cause the stress concentration to promote the initiation and propagation of the cracks along the lamellarγ/α_2interfaces perpendicular to the stress axis.Wherein,some cracks on the various cross-sections were connected by tearing edge along the direction of maximum shear stress,up to the creep fracture,which is considered to be the damage and fracture mechanism of alloy during creep at 750°C.     

Effect of high magnetic field on the crystallization of Nd_2Fe_(14)B/α-Fe nanocomposite magnets

Effect of high magnetic field on the crystallization of Nd_2Fe_(14)B/α-Fe nanocomposite magnets     

The role of isotropic and anisotropic Hubbard corrections for the magnetic ordering and absolute band alignment of hematite α-Fe_2O_3(0001)surfaces

An isotropic (+U) and anisotropic [+(U-J)] corrected Density Functional Theory study for bulk hematite (α-Fe_2O_3) was carried out,and several competing terminations of its (0001) surface modeled via slabs of increasing thickness from twelve to thirty-six Fe-layers.In spite of small quantitative differences,the use of either U or (U-J)corrections showed not to qualitatively affect the results of the simulations both for bulkα-Fe_2O_3 and the lowestenergyα-Fe_2O_3(0001) surface studied,regardless of the thickness of the slab used.The energy favored antiferromagnetic ordering of bulkα-Fe_2O_3 was preserved in the relaxed slabs,with the largest surface-induced effects limited to the outermost three Fe-layers in the slabs.Mixed O-and Fe-terminations were found to be energetically favored and insulating.Conversely,fully O-or Fe-terminated surfaces were calculated to be energetically disfavored and metallic.Finally,the role of Fe-or O-termination for the semiconducting or metallic nature as well as absolute band alignment ofα-Fe_2O_3 (0001) surfaces was analyzed and discussed with respect to the challenges in enhancing the activity ofα-Fe_2O_3 samples as photo-electrode for water splitting.