A convenient procedure for palladium catalyzed cyanation using a unique bidentate phosphorus ligand

A palladium complex bearing 1,2-diphenyl-3,4-diphosphinidenecyclobutene ligand (DPCB) has been used to facilitate the catalytic cyanation of aryl bromides. A series of substituted benzonitriles was prepared in good to high yields by the treatment of the corresponding aryl bromides with Zn(CN)₂ in N-methyl-2-pyrrolidone in the presence of 2-4 mol % catalyst at 100 °C for 16 h.     

New norditerpenoids with trypanocidal activity from Vitex trifolia

Trypanocidal constituents of the fruits of Vitex trifolia were investigated. Activity-guided isolation of the acetone extract resulted in the isolation of two new norditerpene aldehydes, 1 and 2, together with five known diterpenes: vitexifolin E (3), vitexifolin F (4), vitexilactone (5), 6-acetoxy-9-hydroxy-13(14)-labden-16,15-olide (6), and previtexilactone (7). In vitro minimum lethal concentrations of the isolated compounds against epimastigotes of Trypanosoma cruzi were 11 microM (1), 36 microM (2), 34 microM (3), 34 microM (4), 66 microM (5), 66 microM (6), and >265 microM (7).     

Catalytic applications of transition-metal complexes bearing diphosphinidenecyclobutenes (DPCB)

The preparation and characterization of sterically protected diphosphinidenecyclobutenes bearing two two-coordinate phosphorus atoms are described from the viewpoint of the development of a novel type of bidentate ligand for transition-metal complexes. They form complexes with group 6 metals such as chromium, molybdenum and tungsten, group 8 metals such as ruthenium, group 10 metals such as palladium and platinum, and group 11 metals such as copper and gold. Some of them can be used as catalysts for synthetic reactions such as cross-coupling of the Sonogashira type, Suzuki-Miyaura coupling, Ullmann coupling, Kosugi-Migita-Stille coupling, cyanation, polymerization of ethylene, dehydrogenative hydrosilylation of ketones, hydroamination of 1,3-butadienes, and direct alkylation or amination of allylic alcohols of Tsuji-Trost reactions.     

Relationship between supersaturation ratio and supply rate of solute in the growth process of monodisperse colloidal particles and application to AgBr systems

Supersaturation ratio, S, has been theoretically related to the supply rate of solute, Q, from growth rate and mass-balance equations in the quasi-steady state in the growth process of isotropic monodisperse particles. The derived equation, (S - 1) = (1/D + 1/kr)(Q/betaC(0)nr) + 2V(m)gamma/rRT, suggests a linear dependence of S on Q under constant n and r, where D is the diffusion coefficient, k is the rate constant for surface-reaction, C(0) is the solubility, n and r are the number and radius of growing particles, respectively, V(m) is the molar volume of particles, R is the gas constant, T is the absolute temperature, and beta is the shape factor defined by beta identical with (1/r(2)) dupsilon/dr, where upsilon is the volume of an individual particle. The equation was applied to the analysis of growth kinetics and determinations of critical supersaturation ratio in monodisperse AgBr particles in the controlled double-jet system with the assistance of a potentiometric supersaturation measurement. In both cubic and octahedral particles, growth rates were completely limited by diffusion and surface-reaction at pBr ( identical with -log[Br(-)]) 3.0 and 1.0, respectively, while the growths were intermediate of them at pBr 2.0 and 4.0. The growth parameters, DC(0) and kC(0), were experimentally determined. Also, critical supersaturation ratio was estimated as 1.28 as an average in the present study.     

Synthesis and coordination behavior of Cu(I) bis(phosphaethenyl)pyridine complexes

Cu(I) complexes bearing BPEP as a PNP-pincer type phosphaalkene ligand undergo effective bonding interactions with SbF(6)(-) and PF(6)(-) as non-coordinating anions to give [Cu(SbF(6))(BPEP)] and [Cu(2)(BPEP)(2)(μ-PF(6))](+), respectively [BPEP = 2,6-bis(1-phenyl-2-phosphaethenyl)pyridine]. NMR and theoretical studies indicate a reduced anionic charge of the μ-PF(6) ligand, which is induced by the strong π-accepting ability of BPEP.     

Thermodynamics for the Formation of Double‐Stranded DNA–Single‐Walled Carbon Nanotube Hybrids

For the first time, the thermodynamics are described for the formation of double‐stranded DNA (ds‐DNA)–single‐walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds‐DNAs d(A)₂₀–d(T)₂₀ and nuclear factor (NF)‐κB decoy. UV/Vis/near‐IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single‐stranded DNAs (ss‐DNAs), including d(A)₂₀ and d(T)₂₀, are also used for comparison. The d(A)₂₀–d(T)₂₀ shows a drastic change in its thermodynamic parameters around the melting temperature (T_m) of the DNA oligomer. No such T_m dependency was measured, owing to high T_m in the NF‐κB decoy DNA and no T_m in the ss‐DNA.     

Phase relationships and thermodynamic interactions in linear polyethylene–diluent systems

Phase equilibria between linear polyethylene and a number of organic diluents of varying type have been investigated. The diluents include aliphatic alcohols, alkyl phenols, aryl phenols, diphenyl derivatives, alkyl aryl ethers, esters, and ketones. It is found that n-octyl alcohol, n-decyl alcohol, n-lauryl alcohol, p-tert-amyl alcohol, p-octyl phenol, p-nonyl, phenol, diphenyl, diphenylmethane, diphenyl ether, benzyl phenyl ether, and anisole are Θ-solvents for linear polyethylene at temperatures between 120 and 200°C. Thermodynamic interactions are discussed in relation to the type of diluent.     

Strategies for ensuring that regenerative cardiomyocytes function properly and in cooperation with the host myocardium

In developed countries, in which people have nutrient-rich diets, convenient environments, and access to numerous medications, the disease paradigm has changed. Nowadays, heart failure is one of the major causes of death. In spite of this, the therapeutic efficacies of medications are generally unsatisfactory. Although whole heart transplantation is ideal for younger patients with heart failure, many patients are deemed to be unsuitable for this type of surgery due to complications and/or age. The need for therapeutic alternatives to heart transplantation is great. Regenerative therapy is a strong option. For this purpose, several cell sources have been investigated, including intrinsic adult stem or progenitor cells and extrinsic pluripotent stem cells. Most intrinsic stem cells seem to contribute to a regenerative environment via paracrine factors and/or angiogenesis, whereas extrinsic pluripotent stem cells are unlimited sources of cardiomyocytes. In this review, we summarize the various strategies for using regenerative cardiomyocytes including our recent progressions: non-genetic approaches for the purification of cardiomyocytes and efficient transplantation. We expect that use of intrinsic and extrinsic stem cells in combination will enhance therapeutic effectiveness.