Rapid Quantitative Profiling of N-Glycan by the Glycan-Labeling Method Using 3-Aminoquinoline/α-Cyano-4-hydroxycinnamic Acid

Protein glycosylation is a crucial phenomenon for understanding protein functions, since its patterns and degree are associated with many biological processes, such as intercellular signaling and immune response. We previously reported a novel glycan-labeling method using a 3-ainoquinoline/α-cyano-4-hydroxycinnamic acid (3-AQ/CHCA) liquid matrix for highly sensitive detection by matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS). In the present study, we examined the practicality of this method for qualitative and quantitative glycan profile analysis. We first investigated the reproducibility of the data for 16 N-glycans prepared from human epidermal growth factor receptor type 2 (HER2). All of the data obtained in intra-assays and interassays were highly correlated with statistical significance (R(2) > 0.9, p < 0.05). In addition, the HER2 glycosylation pattern differed significantly between different breast cancer cell lines SK-BR-3 and BT474 in a comparative analysis of profile data. Finally, the quantitative capability of this method was examined by using PA-labeled monosialylated N-glycan as an internal standard (IS). Using IS for AQ-labeled neutral and sialylated standard glycans, the ion peak intensity was highly linear (R(2) > 0.9) from 0.5 to 5000 fmol. Furthermore, using IS for HER2 N-glycans, all of the N-glycans were highly linear with their dilution factors (R(2) > 0.9). These results suggest that our developed AQ labeling method enabled rapid qualitative and quantitative analyses of glycans. This glycan analysis method should contribute to the field of biomarker discovery and biomedicine in applications such as quality control of biotechnology-based drugs.     

Preparation of Pd particles coated with mesoporous silica layers

Pre-formed polycrystalline Palladium aggregates (ca. 200 nm in diameter) were coated by thin mesoporous silica layers to form metal-mesoporous silica composite materials. To synthesize the composites, Pd aggregates were dispersed in an aqueous solution of C₁₆H₃₃N(CH₃)₃Br to which tetraethylorthosilicate (TEOS) was then added to give composite precipitates. The surfactant template in the precipitate was subsequently removed by extraction with an acetic acid/ethanol solvent. TEM images of the composite (containing as much as 65 wt% Pd) revealed that the Pd aggregates were fully surrounded by mesoporous silica layers (ca. 50 nm in thickness) having ordered pores that penetrate to large extent from the exterior to the surface of Pd aggregates. When the materials were used as catalysts for cinnamaldehyde hydrogenation in toluene, the reactant molecules were concentrated in the meso channels by a factor of ca. 3. Accordingly, the composites showed comparable or higher activity than that observed for neat Pd aggregates. This study highlights the preparation of unique metal-mesoporous silica composite materials by simple synthetic procedures and which are usable as active Pd catalysts.     

Photovoltaics Based on Hybridization of Effective Dye‐Sensitized Titanium Oxide and Hole‐Conductive Polymer P3HT

Here, the fabrication of quasi‐solid‐state TiO₂/dye/poly(3‐hexylthiophene) (P3HT) solar cells is reported, in which the dyes with oleophilic thienyl groups were employed and ionic liquid (IL), 1‐ethyl‐3‐methylimidazolium (EMIm) containing lithium bis(trifluromethanesulfone)amide (Li‐TFSI) and 4‐tert‐butylpyridine (t‐BP) are assembled with dyed TiO₂ surfaces. One of the devices gave a high conversion efficiency of up to 2.70% under 1 sun illumination. The excellent performance is ascribed to successful molecular self‐organization at interface of the dye molecules and P3HT, and to the efficient charge separation and diffusion acquired by introduction of the IL coupled with Li‐TFSI and t‐BP.     

Equilibrium and Kinetic Studies on Lithium Adsorption from Geothermal Water by λ-MnO2

The adsorption equilibria of lithium from geothermal water were investigated by using both powdery and granulated forms of λ-MnO₂ derived from spinel-type lithium manganese dioxide. Optimum amounts of adsorbents were 1.0 g adsorbent/L-geothermal water for powdery λ-MnO₂ and 6.0 g adsorbent/L-geothermal water for granulated λ-MnO₂. The adsorbents exhibited the promising adsorption capacities and their adsorption equilibria of lithium agreed well with the Langmuir adsorption isotherm model. The kinetic data of lithium adsorption have been evaluated using pseudo-first-order, pseudo-second-order kinetics models, as well as Elovich kinetic model. In addition, intra-particle diffusion model has been used for evaluating the kinetic data to evaluate the adsorption mechanism. The adsorption kinetic process was attributed to the gradual adsorption stage where intra-particle diffusion was found as the rate-controlling step.     

Control of turbulent channel flow over a backward‐facing step by suction or injection

Experiments have been performed for turbulent channel flow over a backward‐facing step. The backward‐facing step is controlled by equipping a slit at the bottom corner of the step. Low momentum fluids in the recirculation region are sucked or high momentum fluids are injected from the slit. The width of the slit is changed between 2, 3, and 5 mm, and the flow ratio is varied from 0.00 to 0.15. The wall static pressure and local heat transfer coefficient are measured behind the backward‐facing step. The wall shear stress is measured using a micro flow sensor. In addition, the velocity profiles and turbulent intensities are measured by a split hot film probe. It is found that the heat transfer and pressure drop characteristics are controlled by the flow ratio. When the suction flow ratio is 0.06, the highest performance is obtained. Enhancement of the heat transfer is related to the increase of turbulence intensity. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(8): 490–504, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20036     

PALLADIUM WITH TRIOCTYLMETHYLAMMONIUM CHLORIDE SOLVENT EXTRACTION OF PALLADIUM(II) WITH TRIOCTYLMETHYLAMMONIUM CHLORIDE

Equilibrium distribution of palladium(II) was investigated in the solvent extraction with tri-octylmethylammonium chloride (QC1) in toluene from hydrochloric acid solutions at 303 K. The title extracting reagent extracted hydrochloric acid as the species of the types, QC1(HC1) (_n(n= 1,2), according to the similar extraction reactions as observed in the extraction of organic acids such as acetic acid and phenol with high-molecular-weight amines in the previous works. From the concentration dependencies of the reactant species on the distribution ratio and from the result of loading test, it was elucidated that palladium(II) is extracted as a mononuclear ion pair complex of the type, Q⁺;[PdCl]₃ (HCl)] in the very high concentration region of hydrochloric acid. The equilibrium constant of the extraction reaction was evaluated.     

Effects of electrode materials on freezing of supercooled water in electric freeze control

In order to clarify effects of electric charge on freezing of supercooled water, experiments were carried out with various kinds of electrodes in supercooled water. Water sample was kept in a test tube and cooled down at a constant cooling rate. When the water sample was maintained under a supercooling state, an electric charge was applied to the water sample with a small electric current. The degree of supercooling was measured continuously. Then the degree of supercooling at freezing was determined. Six kinds of materials were used for electrodes. Those materials were Aluminum, Copper, Argentum, Aurum, Platinum and Carbon. It was found that the effects of electric charge were distinct according to the material used for electrodes. The degree of supercooling at freezing was the lowest in the case of Aluminum. On the other hand, the highest value of the degree of supercooling at freezing was obtained in the case of carbon. The reason for the difference in the degree of supercooling at freezing by six materials was discussed.     

Crystal Structure of an Archaeal Tyrosyl-tRNA Synthetase Bound to Photocaged L-Tyrosine and Its Potential Application to Time-Resolved X-ray Crystallography

Genetically encoded caged amino acids can be used to control the dynamics of protein activities and cellular localization in response to external cues. In the present study, we revealed the structural basis for the recognition of O-(2-nitrobenzyl)-L-tyrosine (oNBTyr) by its specific variant of Methanocaldococcus jannaschii tyrosyl-tRNA synthetase (oNBTyrRS), and then demonstrated its potential availability for time-resolved X-ray crystallography. The substrate-bound crystal structure of oNBTyrRS at a 2.79 Å resolution indicated that the replacement of tyrosine and leucine at positions 32 and 65 by glycine (Tyr32Gly and Leu65Gly, respectively) and Asp158Ser created sufficient space for entry of the bulky substitute into the amino acid binding pocket, while Glu in place of Leu162 formed a hydrogen bond with the nitro moiety of oNBTyr. We also produced an oNBTyr-containing lysozyme through a cell-free protein synthesis system derived from the Escherichia coli B95. ΔA strain with the UAG codon reassigned to the nonnatural amino acid. Another crystallographic study of the caged protein showed that the site-specifically incorporated oNBTyr was degraded to tyrosine by light irradiation of the crystals. Thus, cell-free protein synthesis of caged proteins with oNBTyr could facilitate time-resolved structural analysis of proteins, including medically important membrane proteins.