110 research outputs found
FACILE ENANTIOSELECTIVE PALLADIUM CATALYSED TRANSFER HYDROGENATION OF α-METHYLCINNAMIC ACID IN THE PRESENCE OF OPTICAL PURE ORGANIC ACIDS
An efficient and enantioselective method for catalytic transfer hydrogenation of the C=C double bond of α-methylcinnamic acid with the aid of chiral organic acids as the hydrogen donors and palladium(II) chloride as the catalyst is reported. Enantiomeric excess was assayed using optical rotation measurements. The best stereoselectivity was achieved when L-(+)-tartaric acid was used as the hydrogen donor and acetonitrile as the solvent.
KEYWORDS: Enantioselective, Chiral, α-Methylcinnamic acid, Transfer hydrogenation, Palladium(II) chloride
Bull. Chem. Soc. Ethiop. 2007, 21(3), 457-460
Exact ground-state correlation functions of the one-dimensional strongly correlated electron models with the resonating-valence-bond ground state
We investigate the one-dimensional strongly correlated electron models which
have the resonating-valence-bond state as the exact ground state. The
correlation functions are evaluated exactly using the transfer matrix method
for the geometric representations of the valence-bond states. In this method,
we only treat matrices with small dimensions. This enables us to give
analytical results. It is shown that the correlation functions decay
exponentially with distance. The result suggests that there is a finite
excitation gap, and that the ground state is insulating. Since the
corresponding non-interacting systems may be insulating or metallic, we can say
that the gap originates from strong correlation. The persistent currents of the
present models are also investigated and found to be exactly vanishing.Comment: 59 pages, REVTeX 3.0, Figures are available on reques
Engineering kidneys from simple cell suspensions:an exercise in self-organization
Increasing numbers of people approaching and living with end-stage renal disease and failure of the supply of transplantable kidneys to keep pace has created an urgent need for alternative sources of new organs. One possibility is tissue engineering of new organs from stem cells. Adult kidneys are arguably too large and anatomically complex for direct construction, but engineering immature kidneys, transplanting them, and allowing them to mature within the host may be more feasible. In this review, we describe a technique that begins with a suspension of renogenic stem cells and promotes these cells’ self-organization into organ rudiments very similar to foetal kidneys, with a collecting duct tree, nephrons, corticomedullary zonation and extended loops of Henle. The engineered rudiments vascularize when transplanted to appropriate vessel-rich sites in bird eggs or adult animals, and show preliminary evidence for physiological function. We hope that this approach might one day be the basis of a clinically useful technique for renal replacement therapy
Inheritance of susceptibility to congenital deformity: metabolic clues provided by experiments with teratogenic agents.
Physiological Studies on Congenital Deformity Analysis of Action of Radiation and Radiomimetic Treatments. Technical Progress Report.
Differentiation of intrinsic and maternal factors governing intrauterine survival of mammalian young.
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