Effect of Hydrophobicity and Salt on the Temperature Responsiveness of Polymeric Micelles Consisting of Hydrophobic and Sulfobetaine Chains

The effect of the hydrophobicity of the core part and salt on the temperature responsiveness of polymeric micelles composed of sulfobetaine and hydrophobic blocks was investigated. Poly­(sulfopropyl dimethylammonium propylacrylamide) (PSPP) was used as the sulfobetaine; poly­(2-ethylhexyl acrylate) (PEHA), poly­(n-butyl acrylate) (PnBA), poly­(ethyl acrylate) (PEA), or poly­(n-hexyl acrylate) (PnHA) was used as the hydrophobic polymer. Measurement of the transmittance revealed that the transition temperature of the sulfobetaine homopolymer could be controlled by adjusting the concentration, the degree of polymerization (DP), and the concentration of the added salt. The effect of the anionic species of the added salt due to the chemical structural properties of the sulfobetaine chain was consistent with the order of ionic species with strong structural destruction in the Hofmeister series. The temperature response and micelle formation behavior of the polymeric micelles according to the hydrophobicity of the core part and the preparation method were examined by static light scattering (SLS), fluorescence measurement with pyrene, dynamic light scattering (DLS), transmittance, and atomic force microscopy (AFM). Micelles that had EHA (solubility in water was 0.01 g/100 mL) as the core and did not show temperature responsiveness expressed temperature responsiveness at a lower hydrophobicity (solubility of nBA in water was 0.14 g/100 mL). nBA-b-SPP did not show temperature responsiveness due to the block ratio. However, when micelles were prepared by dialysis, smaller and more stable micelles could be formed in an equilibrium state, and temperature responsiveness was observed. Their transition temperature can be controlled by adjusting the ratio of the sulfobetaine blocks, the hydrophobicity of the core part, the concentration of the polymer aqueous solution, and the concentration of the added salt. Furthermore, like the sulfobetaine homopolymer, the effect depended on the anionic species of the added salt

Effects of Porphyrin Substituents and Adsorption Conditions on Photovoltaic Properties of Porphyrin-Sensitized TiO₂ Cells

A series of meso-tetraphenylzincporphyrins have been prepared to examine the effects of the porphyrin substituents and adsorption conditions on photovoltaic properties of the porphyrin-sensitized TiO2 cells. The cell performance strongly depended on the linking bridge between the porphyrin core and the TiO2 surface, the bulkiness around the porphyrin core, and the immersing solvents and times for the porphyrin adsorption. In particular, the high cell performance of the porphyrin-sensitized TiO2 cells was achieved when protic solvent (i.e., methanol) and short immersing time (0.5−1 h) were used for the conditions of the dye adsorption on TiO2, which is in sharp contrast with Ru dye-sensitized TiO2 cells. The highest cell performance was obtained with 5-(4-carboxyphenyl)-10,15,20-tris(2,4,6-trimethylphenyl)porphyrinatozinc(II) as a sensitizer and methanol as an immersing solvent with an immersing time of 1 h: a maximal incident photon-to-current efficiency of 76%, a short circuit photocurrent density of 9.4 mA cm−2, an open-circuit voltage of 0.76 V, a fill factor of 0.64, and a power conversion efficiency of 4.6% under standard AM 1.5 sunlight. These results will provide basic and valuable information on the development of dye-sensitized solar cells exhibiting a high performance

Quinoxaline-Fused Porphyrins for Dye-Sensitized Solar Cells

5,10,15,20-Tetrakis(2,4,6-trimethylphenyl)-6‘-carboxyquinoxalino[2,3-β]porphyrinatozinc (II) (ZnQMA) and 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)-6‘,7‘-dicarboxyquinoxalino[2,3-β]porphyrinatozinc (II) (ZnQDA) have been synthesized to evaluate the effects of β,β‘-carboxyquinoxalino moieties on the structure and optical, electrochemical, and photovoltaic properties of the porphyrins. Both ZnQMA and ZnQDA exhibited broadened and red-shifted light absorption in UV−visible absorption spectra compared with 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)porphyrinatozinc (II) (ZnP). ZnQMA and ZnQDA also showed decrease in the highest occupied molecular orbital−lowest unoccupied molecular orbital (HOMO−LUMO) gap due to the extension of the porphyrin π-system. From the results of 1H NMR spectroscopy and DFT calculations, ZnQMA and ZnQDA were found to adopt saddle and planar structures, respectively. ZnQMA-sensitized TiO2 solar cell with TiO2 nanoparticles (P25) revealed the power conversion efficiency (η) of 5.2%, whereas ZnQDA-sensitized cell showed η = 4.0%. The superior performance of the ZnQMA-sensitized solar cell to the ZnQDA-sensitized one is originated from both the more favorable electron injection and charge collection efficiency

Offspring survival and body weight

Offspring survival and body weigh

Naphthyl-Fused π-Elongated Porphyrins for Dye-Sensitized TiO₂ Cells

Novel unsymmetrically π-elongated porphyrins, in which the naphthyl moiety is fused to the porphyrin core at the naphthyl bridge with a carboxyl group (fused-Zn-1) or at the opposite side of the phenyl bridge with a carboxyl group (fused-Zn-2), have been synthesized to improve the light-harvesting abilities in porphyrin-sensitized solar cells. As the results of π-elongation with low symmetry, Soret and Q bands of fused-Zn-1 and fused-Zn-2 were red-shifted and broadened, and the intensity of Q-band relative to that of Soret band was enhanced. The fused-Zn-1 and fused-Zn-2-sensitized TiO2 solar cells showed the power conversion efficiencies (η) of 4.1% and 1.1%, respectively, under standard AM 1.5 conditions. The η value of the fused-Zn-1 cell was improved by 50% compared to the reference cell using unfused porphyrin (Zn-1). The fused-Zn-1-sensitized cell revealed high IPCE (incident photon-to-current efficiency) values of up to 55%, extending the response of photocurrent generation close to 800 nm. Thus, the improved photocurrent generation of the fused-Zn-1-sensitized cell relative to the Zn-1-sensitized reference cell is responsible for the remarkable difference in the η values. The η value of the fused-Zn-2 cell was much lower than that of the fused-Zn-1 cell. DFT calculations disclosed that there are significant electron densities on the carboxyl group in the LUMO of fused-Zn-1, whereas there are little electron densities on the carboxyl group in the LUMO of fused-Zn-2. Accordingly, the larger electronic coupling between the porphyrin and the TiO2 surface in the fused-Zn-1-sensitized cell may be responsible for the high cell performance, due to the efficient electron injection from the porphyrin excited singlet state to the conduction band of the TiO2 electrodes. To further improve the cell performance, 5-(4-carboxylphenyl)-10,15,20-tetrakis-(2,4,6-trimethylphenyl)porphyrinatozinc(II) (Zn-3), possessing different light-harvesting properties, was coadsorbed with fused-Zn-1 onto an TiO2 electrode. Under the optimized conditions, the cosensitized cell yielded maximal IPCE value of 86%, short circuit photocurrent density of 11.7 mA cm−2, open-circuit voltage of 0.67 V, fill factor of 0.64, and η of 5.0% under standard AM 1.5 conditions

Effects of 5-Membered Heteroaromatic Spacers on Structures of Porphyrin Films and Photovoltaic Properties of Porphyrin-Sensitized TiO₂ Cells

Novel 5-(5-carboxy-2-thienyl)-10,15,20-tris(2,4,6-trimethylphenyl)-porphyrinatozinc(II) (Zn5S), 5-(5-carboxy-2-furyl)-10,15,20-tris(2,4,6-trimethylphenyl)porphyrinatozinc(II) (Zn5O), and 5-(4-carboxy-2-thienyl)-10,15,20-tris(2,4,6-trimethylphenyl)porphyrinatozinc(II) (Zn4S) were synthesized to evaluate the spacer effects on the structures of the porphyrin films and the photovoltaic properties of the porphyrin-sensitized TiO2 solar cells. Each of the porphyrins showed different adsorption behavior and saturated coverage on the TiO2 surface and photovoltaic properties depending on the identity of heteroatoms in the bridge and the position of carboxylic acid. Specifically, Zn5S-sensitized TiO2 cell displayed larger, maximum incident photon-to-current efficiency of 65% and maximum power conversion efficiency of 3.1% than Zn5O-sensitized TiO2 cell by ∼20% and ∼40%, respectively. We interpret that these results are stemmed from ancillary electron-transfer pathway through specific interaction between a sulfur atom in the bridge of Zn5S and the TiO2 surface. Optical spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, density functional theory calculations, and photovoltaic measurements under standard AM 1.5 conditions were employed to support our proposal

Solvent-free Preparation of Electrochemical Capacitor Electrodes Using Metal-free Redox Organic Compounds

A metal-free redox organic compound, 2,5-dichloro-1,4-benzoquinone (DCBQ), was finely dispersed over the porous carbon substrate, Ketjen Black (KB), by a solvent-free method in only one step. By using this method, DCBQ was loaded inside the pores of KB with as much as ca. 60 wt % in the sample without any agglomeration. This high loading along with high dispersion can be attained due to the absence of solvent. Since this procedure is free from organic solvents it is also free from solvent removal, at which organic compounds tend to agglomerate as the concentration of organic compounds increases, and the concomitant purification process. The electrochemical behaviors of the resulting composite materials were evaluated, and it was found that the volumetric capacitance, which correlated with the capacitance per unit mass of KB, increased with the loading amount of DCBQ, with high power density and long cycle lifetime. The resulting volumetric capacitances reached 4.7 times higher than those of KB and exhibited high rate capability up to 5 A g^–1, along with excellent cycle lifetime up to 10 000 cycles. These results indicate the superiority of the pseudocapacitance induced inside the pores of porous carbon substrates by quinone derivatives over the electric double layer capacitance in gaining both high power and high energy densities

Comparison of Electrode Structures and Photovoltaic Properties of Porphyrin-Sensitized Solar Cells with TiO₂ and Nb, Ge, Zr-Added TiO₂ Composite Electrodes

Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol−gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) 2 (1.2%) 2 (2.0%) 2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 μm in MeOH for 1 h

P21 Deficiency Delays Regeneration of Skeletal Muscular Tissue

<div><p>The potential relationship between cell cycle checkpoint control and tissue regeneration has been indicated. Despite considerable research being focused on the relationship between p21 and myogenesis, p21 function in skeletal muscle regeneration remains unclear. To clarify this, muscle injury model was recreated by intramuscular injection of bupivacaine hydrochloride in the soleus of p21 knockout (KO) mice and wild type (WT) mice. The mice were sacrificed at 3, 14, and 28 days post-operation. The results of hematoxylin-eosin staining and immunofluorescence of muscle membrane indicated that muscle regeneration was delayed in p21 KO mice. <i>Cyclin D1</i> mRNA expression and both Ki-67 and PCNA immunohistochemistry suggested that p21 deficiency increased cell cycle and muscle cell proliferation. F4/80 immunohistochemistry also suggested the increase of immune response in p21 KO mice. On the other hand, both the mRNA expression and western blot analysis of <i>MyoD</i>, <i>myogenin</i>, and <i>Pax7</i> indicated that muscular differentiation was delayed in p21KO mice. Considering these results, we confirmed that muscle injury causes an increase in cell proliferation. However, muscle differentiation in p21 KO mice was inhibited due to the low expression of muscular synthesis genes, leading to a delay in the muscular regeneration. Thus, we conclude that p21 plays an important role in the <i>in vivo</i> healing process in muscular injury.</p></div