Fabrication of nanofibers through a unique morphological transformation of poly(lactic acid) particles in water

Poly(lactic acid) (PLA) particles dispersed in water were transformed into nanofibers by simply heating above the glass transition temperatures of the hydrated PLAs.     

Hamiltonian cycles in bipartite quadrangulations on the torus

In this article, we shall prove that every bipartite quadrangulation G on the torus admits a simple closed curve visiting each face and each vertex of G exactly once but crossing no edge. As an application, we conclude that the radial graph of any bipartite quadrangulation on the torus has a hamiltonian cycle. Copyright © 2011 Wiley Periodicals, Inc. J Graph Theory 69:143‐151, 2012     

Extracorporeal cardiac shock wave therapy for ischemic heart disease

Prognosis of severe ischemic heart disease with no indication of percutaneous coronary intervention or coronary artery bypass grafting still remains poor. Extracorporeal shock wave therapy was introduced for medical therapy more than 20 years ago to break up kidney stones. We have demonstrated that extracorporeal cardiac shock wave therapy at a low level of ~10% of energy density that used for urinary lithotripsy treatment, effectively induces coronary angiogenesis and improves myocardial ischemia in a porcine model of chronic myocardial ischemia in vivo. On the basis of the promising results in animal studies, we have recently developed a new, non-invasive angiogenic therapy with low-energy shock waves for ischemic heart disease. Our extracorporeal cardiac shock wave therapy improved symptoms and myocardial ischemia in patients with severe coronary artery disease. These beneficial effects of the shock wave therapy persisted for at least 12 months. Importantly, no procedural complications or adverse effects were noted. These results indicate that our extracorporeal cardiac shock wave therapy is an effective and non-invasive treatment for ischemic heart disease. To further confirm the usefulness and safety of our SW therapy, we are currently conducting the second clinical trial in a randomized and placebo-controlled manner.      

Ferroelectric Coordination Polymers Self‐Assembled from Mesogenic Zinc(II) Porphyrin and Dipolar Bridging Ligands

A new class of ferroelectric coordination‐based polymers has been developed by the self‐assembly of lipophilic zinc porphyrin ( ZnP ) and ditopic bridging ligands. The ligands contain dipolar benzothiadiazole or fluorobenzene units, which are axially coordinated to ZnP with the dipole moments oriented perpendicular to the coordination axes. The coordination‐based polymers show ferroelectric characteristics in the liquid crystalline state, as revealed by distinctive hysteresis in the polarization–electric field (P–E) loops and inversion current peaks in current–voltage (I–V) loops. The observed ferroelectric properties are explainable by flip–flop rotation of the dipolar axle ligands induced by the applied electric field, as demonstrated by the positive‐up–negative‐down (PUND) measurements. The present system provides a new operating principle in supramolecular ferroelectrics.     

Pharmacological activities of synthetic human cholecystokinin-33 of which tyrosine was sulfated by arylsulfotransferase

The pharmacological activities of synthetic human CCK-33, in which a tyrosine molecule was sulfated by arylsulfotransferase, were investigated in the rat and the guinea-pig. The activities were compared with those of non-sulfated CCK-33 (CCK-33NS), CCK-8 and CCK-4. CCK-33 was about 100 fold more potent than non-sulfated CCK-33(CCK-33NS) but was about 20 fold less potent than CCK-8 in the contraction of the isolated gallbladder of the guinea-pig. In rat pancreatic secretion, intravenous CCK-33 and CCK-8 showed almost the same activity. The potency of each was about 1000 fold more than the individual potency of CCK-33NS, non-sulfated CCK-8 (CCK-8NS) and CCK4. There were no significant differences in gastric acid stimulatory activities among CCK-33, CCK-8, CCK-4, but the activities of CCK-33NS and CCK-8NS were less than those of CCK-33 and CCK-8, respectively. CCK-33 and CCK-8 produced a reduction in the intake of powder chow in doses of 10(-8) and 3 x 10(-8) mol/kg i.p., but CCK-33NS, CCK-8NS and CCK-4 did not. In conclusion, the activities of synthetic human CCK-33 are almost the same as those of CCK-8 on exocrine pancreatic secretion, gastric acid secretion and food intake, but less than CCK-8 on isolated gallbladder contraction.     

Evaluation of photoinduced changes in stability constants for metal-ion complexes of crowned spirobenzopyran derivatives by electrospray ionization mass spectrometry

The photoinduced changes of metal-ion complexing ability of crowned spirobenzopyran derivatives were studied by using electrospray ionization mass spectrometry (ESI-MS). Stability constants for the complexation with various metal ions in methanol under visible-irradiation conditions were determined for the first time by ESI-MS. It was found that the stability constants of crowned bis(spirobenzopyran) derivatives with metal ions are decreased dramatically by visible irradiation due to the disappearance of powerful ionic interaction between phenolate anion(s) of the merocyanine form of their spirobenzopyran moiety and a metal ion bound to their crown ether moiety, and the decrease in the stability constants is more pronounced for the multivalent metal-ion complexes. A theoretical consideration was also made to attain reliable values of stability complexes for metal-ion complexes of crown compounds.     

Electronic and vibrational surface-enhanced Raman scattering: from atomically defined Au(111) and (100) to roughened Au

In surface-enhanced Raman spectra, vibrational peaks are superimposed on a background continuum, which is known as one major experimental anomaly. This is problematic in assessing vibrational information especially in the low Raman-shift region below 200 cm⁻¹, where the background signals dominate. Herein, we present a rigorous comparison of normal Raman and surface-enhanced Raman spectra for atomically defined surfaces of Au(111) or Au(100) with and without molecular adsorbates. It is clearly shown that the origin of the background continuum is well explained by a local field enhancement of electronic Raman scattering in the conduction band of Au. In the low Raman-shift region, electronic Raman scattering gains additional intensity, probably due to a relaxation in the conservation of momentum rule through momentum transfer from surface roughness. Based on the mechanism for generation of the spectral background, we also present a practical method to extract electronic and vibrational information at the metal/dielectric interface from the measured raw spectra by reducing the thermal factor, the scattering efficiency factor and the Purcell factor over wide ranges in both the Stokes and the anti-Stokes branches. This method enables us not only to analyse concealed vibrational features in the low Raman-shift region but also to estimate more reliable local temperatures from surface-enhanced Raman spectra.

Both electronic and vibrational information at the metal/dielectric interface were explicitly extracted from surface-enhanced Raman spectra.     

Densities and Viscosities of Tris(acetylacetonato)cobalt(III) Complex Solutions in Various Solvents

The densities and the viscosities of tris(acetylacetonato)cobalt(III) solutions in acetonitrile, dichloromethane, chloroform, tetrachloromethane, benzene, toluene, ethylbenzene, and p-xylene were measured in the dilute concentration regions at several temperatures ranging from 278 to 313 K under ambient pressure. The partial molar volumes of the solvents and solute were calculated. They are independent of concentration and increase slightly as the temperature increases. The viscosity A- and B-coefficients of the Jones-Dole equation were obtained. The A-coefficients were found to be zero within experimental error. The B-coefficients are positive and decrease as the temperature increases. Thermodynamic quantities of activation for viscous flow were calculated on the basis of Eyring’s viscosity equation. From the quantities obtained in this study, along with some information from the literature, it is suggested that structure-making interactions occur between the segments of the complex and the solvent molecules. These interactions include electrostatic interactions between the local charge on the complex and the dipole moment of the solvent in solutions of acetonitrile and dichloromethane, interlocking packing interactions along C ₃-axis of the complex with solvent in solutions of chloroform and tetrachloromethane, and π-electron interactions between the chelate ring of the complex and the solvent in solutions of benzene, toluene, ethylbenzene, and p-xylene.     

Study on the Indirect Electrochemical Detection of Ammonium Ion with In Situ Electrogenerated Hypobromous Acid

The electrochemical oxidation of bromide in the presence of ammonium ion (NH ) was studied by cyclic voltammetry and UV‐vis spectroscopy. The experimental results suggested that the anodically generated bromine (Br₂) would be hydrolyzed to hypobromous acid (HBrO) at the pH range of 5–7 and was further disproportionate to hypobromite anion (BrO^?) when pH was larger than 7. Both HBrO and BrO^? were confirmed to be participated in the following homogeneous chemical reaction with the coexisted ammonium ion. However, HBrO is electroactive whereas BrO^‐ is electroinactive at carbon electrode. Based upon the reaction of HBrO with NH , an indirect electrochemical method was proposed for determination of NH with dual‐electrode configuration in phosphate buffer solution (pH 7), where HBrO was produced at a generator electrode and the excess HBrO was subsequently detected at a collector electrode after a reaction with NH in a batch solution or in a micro flow injection analytical (micro‐FIA) system by using an interdigitated array (IDA) Pt microelectrode and a carbon film ring‐disk electrode (CFRDE), respectively. The decreasing of reduction current at the collector electrode was proportional to the concentration NH in both systems, with the detection limit below 3.0 μM. This approach shows the advantage of highly selectivity even in presence of a large amount of coexisted cations, and was successfully applied for the determination of NH in environmental water samples.