Preparation of donor-acceptor type organic dyes bearing various electron-withdrawing groups for dye-sensitized solar cell application

Novel donor-π-spacer-acceptor type organic dyes bearing various electron-withdrawing groups on their acceptor part were synthesized by Knoevenagel condensation with acetic acid silyl ester derivatives. Dye-sensitized solar cells with the new dyes present solar light-to-electricity conversion efficiency of 2.51-4.05%.     

Improvement of mass spectrometry analysis of glycoproteins by MALDI-MS using 3-aminoquinoline/α-cyano-4-hydroxycinnamic acid

Protein glycosylation analysis is important for elucidating protein function and molecular mechanisms in various biological processes. We previously developed a glycan analysis method using a 3-aminoquinoline/α-cyano-4-hydroxycinnamic acid liquid matrix (3-AQ/CHCA LM) and applied it to the quantitative glycan profiling of glycoproteins. However, information concerning glycosylation sites is lost; glycopeptide analysis is therefore required to identify the glycosylation sites in glycoproteins. Human epidermal growth factor receptor 2 (HER2) is a glycoprotein that plays a role in the regulation of cell proliferation, differentiation, and migration. Several reports have described the structure of HER2, but the structures of N-glycans attached to this protein remain to be fully elucidated. In this study, 3-AQ/CHCA LM was applied to tryptic digests of HER2 to reveal its N-glycosylation state and to evaluate the utility of this LM in characterizing glycopeptides. Peptide sequence coverage was considerably improved compared to analysis of HER2 using α-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic acid. Most of the peaks observed using only this LM were localized at the inner or outer regions of sample spots. Furthermore, five of the peptide peaks that were enriched within the inner region were confirmed to be glycosylated by MS/MS analysis. Three glycosylation sites were identified and their glycan structures were elucidated. The reduction in sample complexity by on-target separation allowed for higher sequence coverage, resulting in effective detection and characterization of glycopeptides. In conclusion, these results demonstrate that MS-based glycoprotein analysis using 3-AQ/CHCA is an effective method to identify glycosylation sites in proteins and to elucidate the glycan structures of glycoproteins in complex samples.     

Interaction between Dyes and Polyelectrolytes. XV. Effect of Mixed Dimer Formation on the Excitation Energy Transfer between Bound Dyes

The effect of polyanions on the formation of mixed dimers of methylene blue (MB) and trypaflavine (TF), MB and phenosafranine (PhS), and MB and pyronine G (PG) was investigated spectrophotometrically. The following polyanions were used: potassium poly(vinyl sulfate) (PVSK), potassium poly(styrenesulfonate) (PSSK), sodium poly(methacrylate) (PMANa), and sodium poly-(acrylate) (PAANa). The formation of mixed dimers was dependent on the kind of polyanion and polyanion-dye ratio. MB-photo-sensitized isomerization of cis-p-(phenylazo)-phenyltrimethyl-ammonium iodide (cis-PTA) to the trans-isomer was used advantageously to investigate the triplet excitation energy transfer between cationic dyes bound to polyanions. Although the efficiency of the excitation energy transfer between MB and cis-PTA was enhanced by the addition of polyanions, the formation of mixed dimer of MB with TF, PhS, or PG reduced the efficiency of the excitation energy transfer. Correlation with the formation of mixed dimer of MB with TF, PhS, or PG and the efficiency of the excitation energy transfer from MB to cis-PTA is discussed.     

Vinyl Polymerization by Metal Complexes. XV. Polymerization of Acrylonitrile Initiated by Imidazole-Copper(II) Complex

The polymerization of acrylonitrile initiated with the imidazole-copper (II) complexes was studied in dimethylsulfoxide solution. The ability of the complexes to initiate polymerization seems to depend on their anion. 2-Substituted imidazole-copper (II) complexes of the type, CuL₄X₂ (L = imidazole as ligand and X = anion), were also found to initiate vinyl polymerization. From the data of electronic spectra in dimethylsulfoxide solution, the initiation mechanism is discussed in terms of the formation of the active species by the interaction of the complex with monomer molecules.     

Holonomic gradient descent for the Fisher–Bingham distribution on the d-dimensional sphere

We propose an accelerated version of the holonomic gradient descent and apply it to calculating the maximum likelihood estimate (MLE) of the Fisher–Bingham distribution on a \(d\) -dimensional sphere. We derive a Pfaffian system (an integrable connection) and a series expansion associated with the normalizing constant with an error estimation. These enable us to solve some MLE problems up to dimension \(d=7\) with a specified accuracy.     

The holonomic rank of the Fisher–Bingham system of differential equations

The Fisher–Bingham system is a system of linear partial differential equations satisfied by the Fisher–Bingham integral for the n  -dimensional sphere Sⁿ$S^n$. The system is given in [4, Theorem 2] and it is shown that it is a holonomic system [1]. We show that the holonomic rank of the system is equal to 2n+2$2n+2$.     

Xylomexicanins E-H,new limonoids from Xylocarpus granatum

Four novel tetranortriterpenoids, xylomexicanins E–H (1–4), were isolated from the seeds of the Chinese mangrove, Xylocarpus granatum. Among them, xylomexicanin E (1) represents the first example of limonoid with azaspiro skeleton between B (pyrrolidine) and C rings, whose biosynthetic pathways were proposed. The structures were elucidated on the basis of one- and two-dimensional NMR (including ¹H, ¹³C NMR, DEPT, ¹H–¹H COSY, HSQC, HMBC, and NOESY) and confirmed by high-resolution mass spectrometry. Compound 2, the second example of a limonoid with a C-9–C-30 linkage, showed moderate activity against the A549 and RERF cell line with IC₅₀ value of 18.83 and 15.83 μM,     

Influence of Dye Content on the Conduction Band Edge of Titania in the Steam‐treated Dye‐dispersing Titania Electrodes

The titania and dye‐dispersing titania electrodes were prepared by a nitric acid‐catalyzed sol‐gel process. The dye‐dispersing titania contains the dye molecules dispersed on the surface of the individual nanosized titania particles. The photo‐cyclic voltammetry (Photo‐CV) and photoelectric measurements of the dye‐dispersing titania electrodes were conducted to clarify the factors changing the conduction band edge of the titania and the open‐circuit voltage (V_oc) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the titania of the dye‐dispersing titania. The conduction band edge of the titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye‐titania complex formation on the titania particle surface. The effect of the dye‐titania complex formation on the shift in the titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and titania through the carboxylate and quinone‐like groups of the dye. The shift in the titania conduction band edge corresponded to the change in the V_oc value.     

Facilitated Transport of Ions and Glucose by Amphotericin B Across Lipid Bilayers in the Presence or Absence of Cholesterol

The transport of ions and glucose across bilayer lipid membranes (BLM) facilitated by amphotericin B (AmB) is studied by use of planar BLMs and liposomal membranes. The transport characteristics change with time in the presence of cholesterol, while it is independent of time in the absence of cholesterol. The carrier‐type transport is observed immediately after the addition of AmB. In the presence of cholesterol, AmB forms a 1 : 1 complex with cholesterol and the channel is formed by aggregation of AmB‐cholesterol complexes. It is concluded that the number of the channels increases with time and that the carrier‐type transport decreases instead.     

Boron Clusters as Highly Stable Magnesium‐Battery Electrolytes

Boron clusters are proposed as a new concept for the design of magnesium‐battery electrolytes that are magnesium‐battery‐compatible, highly stable, and noncorrosive. A novel carborane‐based electrolyte incorporating an unprecedented magnesium‐centered complex anion is reported and shown to perform well as a magnesium‐battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium‐battery electrolytes is very high.