Effective isolation of magnesium lithospermate B and its inhibition of aldose reductase and fibronectin on mesangial cell line

We developed an effective isolation method of magnesium lithospermate B from Salviae miltiorrhizae Radix and found for the first time that magnesium lithospermate B shows strong in vitro inhibition (IC50=0.04 microM) of aldose reductase (AR), 2.5 times than that of clinically used epalrestat (IC50=0.1 microM) and accumulation of fibronectin dose dependently.     

Stimulated Raman scattering in natural crystals of fluorapatite,Ca5(PO4)3F

Hexagonal Ca₅(PO₄)₃F, known as natural crystal fluorapatite and oldest host‐crystal for Ln³⁺‐lasant ions, is presented as a Raman‐active material. High‐order Raman‐induced χ⁽³⁾‐nonlinear processes are discovered in natural crystals of fluorapatite under picosecond pumping at 1.064 μm and 0.532 μm wavelength. A multitude of Stokes and anti‐Stokes components is generated in the ultraviolet, visible and near‐infrared spectral region by stimulated Raman scattering (SRS) and Raman four‐wave mixing (FWHM), resulting in a frequency comb with a width of 520 THz. The spectral lines are identified and attributed to the ν₁(A_g) vibration mode of the tetrahedral [PO₄] units which is related to a Raman shift of ω_SRS ≈ 965 cm⁻¹. The first Stokes steady‐state Raman gain coefficient in the near‐infrared spectral range is estimated to be >0.38 cm·GW⁻¹. Finally, a short review of SRS‐promoting vibration modes and observed χ⁽³⁾‐ nonlinear interactions in all known SRS‐active natural crystals (minerals) is given.

     

Operation of a Raman laser in bulk silicon

A Raman laser based on a bulk silicon single crystal with 1.127 μm emission wavelength is demonstrated. The Si crystal with 30 mm length was placed into an external cavity and pumped by a Q-switched Nd:YAG master oscillator power amplifier system. Strong defocusing of the pump and Raman laser beam by free carriers was compensated by an intracavity lens. Raman laser operation with a pulse duration of 2.5 ns was identified by a Raman laser threshold significantly lower than the single-pass stimulated Raman-scattering threshold. Linear absorption losses of the 1.06415 μm pump radiation are strongly reduced by cooling the Si crystal to a temperature of 10 K.     

Identification of 2D-gel proteins: a comparison of MALDI/TOF peptide mass mapping to mu LC-ESI tandem mass spectrometry

A comparative analysis of protein identification for a total of 162 protein spots separated by two-dimensional gel electrophoresis from two fully sequenced archaea, Methanococcus jannaschii and Pyrococcus furiosus, using MALDI-TOF peptide mass mapping (PMM) and mu LC-MS/MS is presented. 100% of the gel spots analyzed were successfully matched to the predicted proteins in the two corresponding open reading frame databases by mu LC-MS/MS while 97% of them were identified by MALDI-TOF PMM. The high success rate from the PMM resulted from sample desalting/concentrating with ZipTip(C18) and optimization of several PMM search parameters including a 25 ppm average mass tolerance and the application of two different protein molecular weight search windows. By using this strategy, low-molecular weight (<23 kDa) proteins could be identified unambiguously with less than 5 peptide matches. Nine percent of spots were identified as containing multiple proteins. By using mu LC-MS/MS, 50% of the spots analyzed were identified as containing multiple proteins. mu LC-MS/MS demonstrated better protein sequence coverage than MALDI-TOF PMM over the entire mass range of proteins identified. MALDI-TOF and PMM produced unique peptide molecular weight matches that were not identified by mu LC-MS/MS. By incorporating amino acid sequence modifications into database searches, combined sequence coverage obtained from these two complimentary ionization methods exceeded 50% for approximately 70% of the 162 spots analyzed. This improved sequence coverage in combination with enzymatic digestions of different specificity is proposed as a method for analysis of post-translational modification from 2D-gel separated proteins.     

Cerussite,PbCO3 – a new Stimulated Raman Scattering (SRS)‐active crystal with high‐order Stokes and anti‐Stokes lasing

Orthorhombic PbCO₃, known as natural crystal cerussite, is presented as a new Stimulated Raman Scattering (SRS)‐active crystal. With picosecond laser pumping high‐order Raman‐induced χ⁽³⁾ generation is observed. All registered Stokes and anti‐Stokes sidebands in the visible and near‐IR are identified and attributed to the SRS‐promoting phonon mode A_1g of the carbonate group, with ω_SRS ≈ 1054 cm⁻¹. The first Stokes steady‐state Raman gain coefficient in the visible spectral range is estimated as well to a value not less than 4.6 cm·GW⁻¹.     

Orthorhombic YAlO3 – a novel many‐phonon SRS‐active crystal

In single crystals of orthorhombic YAlO₃, widely known as a host‐matrix for Ln³⁺‐lasant ions, many‐phonon stimulated Raman scattering interactions as well as different manifestations of cascaded and cross‐cascaded nonlinear χ⁽³⁾↔χ⁽³⁾ processes are initiated by picosecond laser pulses. The scientific and applicative potential of YAlO₃ crystals is considerably expanded by the demonstration of its SRS properties. In particular, the studies revealed the manifestation of eight χ⁽³⁾‐active vibrational modes. The corresponding Stokes and anti‐Stokes lines have been assigned and the steady‐state Raman gain coefficients related to the strongest phonon mode have been estimated. In addition, a short review presents the stimulated emission channels of its Ln³⁺‐ions together with some χ⁽³⁾‐nonlinear laser properties of crystals belonging to the binary Y₂O₃‐Al₂O₃ system.     

双核茂金属催化剂的合成、表征与应用

使用桥连配体锂盐与MCl₄络合, 合成了4个不同结构的双核茂金属化合物[μ,μ-(CH₂)₃]{[C(H)·(η⁵-C₅H₄)(η⁵-C₁₃H₈)](MCl₂)}₂[M=Zr or Ti](4, 5)和[μ,μ-(CH₂)₃]{[C(H)(η⁵-C₅H₄)(η⁵-C₉H₆)]·(MCl₂)}₂[M=Zr or Ti](6, 7), 配体和化合物都经过核磁氢谱(¹H NMR)、 碳谱(¹³C NMR)、 红外光谱(IR)及元素分析等表征, 确认了化学结构. 以甲基铝氧烷(MAO)为助催化剂, 化合物4~7为催化剂催化丙烯聚合, 考察了聚合温度、 乙烯压力、 铝钛或铝锆比对催化剂活性及聚合物分子量的影响. 结果表明, 多亚甲基桥连双核茂金属是高活性乙烯和丙烯聚合催化剂, 乙烯聚合活性最高达到7.5× 10⁶ g PE/(mol Zr·h)(化合物6), 丙烯聚合活性达 10 × 10⁵ g sPP/(mol Zr·h)(化合物4). 所得间规聚丙烯(sPP)的间规度指数(SI, r) 达到90%. 在同样条件下, 双核化合物的催化活性、 聚合物分子量M_w(> 100000)以及分子量分布(MWD>2.5)均比相应的单核化合物高(M_w<70000, MWD≤2), 表明该体系中存在较强的核效应.     

茂金属催化乙酸与丁醇酯化反应

以二茂铁、二茂钛、二茂锆和取代茂锆为催化剂用于催化酯化合成乙酸丁酯, 探讨了不同茂金属、反应时间和催化剂用量对反应性能的影响. 结果表明, 低含量的茂金属就可高效催化酯化反应. 当催化剂为二茂钛, 其含量为 0.049%(摩尔比)时, 反应 30 min 产物乙酸丁酯的分离收率达到 90%, 纯度达到 98%. 以 400 目不同温度活化的硅胶为载体, 考察了负载二茂锆催化剂的性能. 当硅胶在 400 ℃ 焙烧 4.0 h, 负载二茂锆催化剂用量为 Zr/丁醇 = 0.487% (摩尔比), 反应后乙酸丁酯收率为 90.6%, TOF = 318 h-1. 该反应的产物后处理不需要用水洗涤, 无废水排出, 催化剂易回收利用, 是一个绿色的反应过程.     

Trigonal prismatic vs octahedral coordination geometry: syntheses and structural characterization of hexakis(arylthiolato) zirconate complexes

Treating [Li(tmeda)]2[Zr(CH3)6] with aryl thiols, HSC6H4-4-R, in a 1:6 stoichiometry in diethyl ether affords excellent yields of [Li(tmeda)]2[Zr(SC6H4-4-R)6], where R = CH3 (1(2-)) or OCH3 (2(2-)) and tmeda denotes N,N,N',N'-tetramethylethylenediamine. These complexes are air-sensitive canary-yellow solids, soluble in hexane, diethyl ether, THF, and acetonitrile, that form yellow single crystals of [Li(tmeda)](2)1 (diethyl ether solution) or [Li(THF)3](2)2 (THF solution) from saturated solutions at -20 degrees C. Both complexes were characterized by X-ray crystallography and consist of a zirconium atom coordinated solely by the sulfur atoms of six aryl thiolate ligands in a nonoctahedral geometry. In each structure the lithium cation coordinates to the three sulfur atoms on the triangular faces of the S6 pseudotrigonal prism. These lithium-sulfur interactions appear to play a role in determining the coordination geometry about the metal center by orienting the sulfur lone pairs of electrons slightly out of the plane defined by the S3 triangular face and tilted away from the zirconium atoms. A likely consequence is the positioning of the sulfur lone pairs of electrons away from orthogonality with the zirconium-sulfur vector, and hence, they are poorly arranged to pi-interact with zirconium. Complex 1(2-) with a twist angle of ca. 9.18 degrees (trigonal prism, 0 degree; octahedron, 60 degrees) agrees with the interpretations of computational studies on d degree complexes, which suggest that a nearly trigonal prismatic geometry is favored when the interaction between metal and ligand is primarily through sigma-bonds. The intrinsically weak pi-donor thiolate ligand is probably converted to a primarily sigma-bonding system by the lithium-sulfur interaction. On the other hand complex 2(2-) with a twist angle of ca. 30.38 degrees is trigonally twisted to the midpoint of the trigonal prismatic-to-octahedral reaction coordinate. In complex 2(2-) the 4-OCH3 group is an electron donor by resonance effects that possibly may lead to the movement away from the expected trigonal prismatic geometry due to either pi-interactions or electrostatics repulsion.     

High‐order Stokes and anti‐Stokes Raman generation in monoisotopic CVD 12C‐diamond

We determined, for the first time, the room temperature phonon energy related to the F_2g vibration mode (ω_SRS(12C) ～ 1333.2 cm^–1) in a mono‐crystalline single‐isotope CVD ¹²C‐diamond crystal by means of stimulated Raman scattering (SRS) spectroscopy. Picosecond one‐micron excitation using a Nd³⁺:Y₃Al₅O₁₂‐laser generates a nearly two‐octave spanning SRS frequency comb (～12000 cm^–1) consisting of higher‐order Stokes and anti‐Stokes components. The spacing of the spectral lines was found to differ by Δω_SRS ～ 0.9 cm^–1 from the comb spacing (ω_SRS(natC) ～ 1332.3 cm^–1) when pumping a conventional CVD diamond crystal with a natural composition of the two stable carbon isotopes ¹²C (98.93%) and ¹³C (1.07%). (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)