Study on the interaction of La with bovine serum albumin at molecular level

The interaction of La³⁺ to bovine serum albumin (BSA) has been investigated mainly by fluorescence spectra, UV-vis absorption spectra, and circular dichroism (CD) under simulative physiological conditions. Fluorescence data revealed that the quenching mechanism of BSA by La³⁺ was a static quenching process and the binding constant is 1.75×10⁴ L mol⁻¹ and the number of binding sites is 1 at 289 K. The thermodynamic parameters (ΔH=−20.055 kJ mol⁻¹, ΔG=−23.474 kJ mol⁻¹, and ΔS=11.831 J mol⁻¹ K⁻¹) indicate that electrostatic effect between the protein and the La³⁺ is the main binding force. In addition, UV-vis, CD, and synchronous fluorescence results showed that the addition of La³⁺ changed the conformation of BSA.     

~ 1.2 μm near-infrared emission and gain anticipation in Ho doped heavy-metal gallate glasses

Ho³⁺-doped low-phonon-energy heavy-metal gallate glasses (LKBPBG) have been prepared and efficient 1.199 μm emission originating from the ⁵I₆ → ⁵I₈ radiative transition has been observed under 900 nm excitation. The spontaneous emission probability and the maximum stimulated emission cross-section were derived to be 294.31 s^− 1 and 3.46 × 10^− 21 cm², respectively. The ratio of quantum yields between ~ 1.2 and ~ 2.0 μm emissions was identified to be 16%, demonstrating that the ⁵I₆ → ⁵I₈ transition is favorable for optical amplification. The maximum gain coefficient of 1.84 dB/cm at 1.199 μm wavelength was anticipated in the ideal status. These results indicate that the Ho³⁺-doped LKBPBG glasses have a promising potential for the development of ~ 1.2 μm signal amplifier devices.     

Vibrational spectroscopy studies of a pressure-induced disproportionation reaction of LaH2

The pressure-induced disproportionation reaction of LaH₂ was investigated by infrared reflection and Raman measurements at ambient temperature. The relative reflection intensity in the 4000-6000 cm⁻¹ region began to decrease significantly at a pressure of about 12 GPa and fell to 10% of the initial value at 20 GPa. Absorption peaks, which appeared around 1200 and 700 cm⁻¹ at pressures above 14 GPa, were assigned to the hydrogen vibrations at the tetrahedral and octahedral sites of the fcc metal lattice, respectively. The peak frequencies measured in the 14-30 GPa range were similar to those observed in LaH₃. These infrared results indicated insulating LaH₃ precipitated from metallic LaH₂. Above 20 GPa, a Raman peak related to the hydrogen vibration in the octahedral sites appeared around 700 cm⁻¹, and was likely due to lattice distortion. The disproportionation reaction of LaH₂ into and solid solution LaH_x (x<1) was confirmed.     

Effect of cation doping on ionic and electronic properties for lanthanum silicate-based solid electrolytes

Electronic as well as ionic conducting properties for oxyapatite-type solid electrolytes based on lanthanum silicate, La_9.333 + xSi₆O_26 + 1.5x (LSO) were investigated in the oxygen-excess region (x > ca. 0.3). We have found that the oxygen excess-type LSO (OE-LSO), namely La₁₀Si₆O₂₇ on weighted basis, exhibited high conductivity, and substitution of the Si-site of LSO with some dopants (Mⁿ⁺) had a positive effect toward the conducting property. Furthermore, it was also found that addition of a very small amount of iron ions into the M-doped OE-LSO, La₁₀(Si_6-yMⁿ⁺_y)O_27-(2-0.5n)y, improved its conductivity. On the other hand, replacement of the La-site with various ions for La₁₀(Si_6-yMⁿ⁺_y)O_27-(2-0.5n)y did little to improve conductivity. The electronic transport numbers for Al-doped OE-LSO with Fe-addition, (1-α){La₁₀(Si_5.8Al_0.2)O_26.9}-α(FeO_γ), evaluated with the Hebb-Wagner polarization method were very low: i.e., 1.1 × 10^− 3 and 2.9 × 10^− 3 under P(O₂) = 1.1 × 10⁴ Pa at 1073 K for α = 0.00 and 0.005, respectively. Conductivity for each sample was unchanged under humidified atmosphere at 1073 K sustained for over 50 h, revealing that both compositions were chemically stable. It was concluded that 0.995{La₁₀(Si_5.8Al_0.2)O_26.9}-0.005(FeO_γ) is suitable for the fuel cell electrolytes because of its high and almost pure ionic conductivity, and its good chemical stability under humidified as well as reducing conditions.     

Synthesis and characterization of doped apatite-type lanthanum silicates for SOFC applications

A series of iron- and/or aluminium-doped apatite-type lanthanum silicates (ATLS) La_9.83Si_{6 ‐ x ‐ y}Al_xFe_yO_26 ± δ (x = 0, 0.25, 0.75, and 1.5, y = 0, 0.25, 0.75, and 1.5) were synthesized using the mechanochemical activation (MA), solid state reaction (SSR), Pechini (Pe) and sol-gel (SG) methods. The total conductivity of the prepared materials was measured under air in the temperature range 600-850 °C using 4-probe AC impedance spectroscopy. Its dependence on composition, synthesis method, sintering conditions and powder particle size was investigated. It was found that for electrolytes of the same composition, those prepared via mechanochemical activation exhibited the highest total specific conductivity, which was improved with increasing Al- and decreasing Fe-content. The highest conductivity value at 700 °C, equal to 2.04 × 10^− 2 S cm^− 1, was observed for the La_9.83Si₅Al_0.75Fe_0.25O_26 ± δ electrolyte. La_9.83Si_4.5Fe_1.5O_26 ± δ electrolyte samples synthesized using the Pechini method exhibited higher conductivity when sintered conventionally than when spark-plasma sintering (SPS) was used.     

Electrochemical Detection of Schistosoma Japonicum Antibody Using Biocatalytic Deposition

Abstract

An ultrasensitive electrochemical immunoassay based on biocatalytic deposition has been proposed for the detection of Schistosoma japonicum antibody (SjAb) in infected rabbit serum. Schistosoma japonicum antigen (SjAg) was immobilized on the gold electrode surface via glutaraldehyde crosslink and then incubated with infected rabbit serum containing SjAb; finally, the goat anti-rabbit IgG labeled with alkaline phosphatase was sandwiched to form the immunocomplex on the gold electrode surface. The alkaline phosphatase converted nonelectroactive substrate into the reducing agent and the latter, in turn, reduced metal ions to form electroactive metallic product on the electrode surface. Linear sweep voltammetry (LSV) was used to quantify the amount of the deposited silver and give the analytical signal for SjAb. Assay conditions such as the antigen concentration and enzymatic silver deposition time were optimized. The electrochemical immunosensor was able to realize a reliable determination of SjAb in the dilution range from 1:5000 to 1:100 with a detection limit of 1:6457 of dilution ratio. The feasibility of the proposed immunosensor for possible clinical applications was also investigated by analyzing real serum samples.     

LC–MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma

A simple, rapid and sensitive liquid chromatography–tandem mass spectroscopy (LC–MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB‐C₁₈ column (3.5 μm, 2.1 × 50 mm) with an isocratic mobile phase consisted of methanol–acetonitrile–10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple‐reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra‐day and inter‐day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

天然水中微量稀土元素镧的流动注射在线预浓集ICP光谱法测定

本文采用P507萃淋树脂为固定相,应用流动注射(FI)在线预浓集技术,建立了镧的ICP发射光谱分析方法,对天然水中的微量镧进行了测定,获得满意结果。     

H4PMo11Vo40杂多酸及其镧盐的合成与性质

本文提出主要用~(51)V NMR、CV并辅以IR、XRD、DTG、元素分析等作为有效地核查纯度和表征催化剂的手段。     

Complete dispersion analysis of single crystal neodymium gallate

A single crystal of neodymium gallate was investigated by FTIR-spectroscopy in the reststrahlen region between 100–1000 cm⁻¹. The three spectra of the crystal in principal orientations were analyzed by dispersion analysis and the dispersion parameters and the dielectric tensor function were obtained. This allows to properly characterize and quantitatively analyze films of this important substrate material by IR-optical methods.