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Rational Solutions (rational + solution)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

Limiting Financial Disincentives in Live Organ Donation: A Rational Solution to the Kidney Shortage

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2006
R. S. Gaston
Availability of kidney transplantation is limited by an inadequate supply of organs, with no apparent remedy on the immediate horizon and increasing reliance on living donors (LDs). While some have advocated financial remuneration to stimulate donation, the National Organ Transplant Act (NOTA) of 1984 expressly forbids the offer of ,valuable consideration.' However, recent developments indicate some fluidity in the definition of valuable consideration while evolving international standards highlight deficiencies (particularly regarding long-term care and follow-up) in the current American system. Recognizing that substantial financial and physical disincentives exist for LDs, we propose a policy change that offers the potential to enhance organ availability as well as address concerns regarding long-term care. Donors assume much greater risk than is widely acknowledged, risk that can be approximated for the purpose of determining appropriate compensation. Our proposal offsets donor risk via a package of specific benefits (life insurance, health insurance and a small amount of cash) to minimize hazard and ensure donor interests are protected after as well as before nephrectomy. It will fund medical follow-up and enable data collection so that long-term risk can be accurately assessed. The proposal should be cost effective with only a small increase in the number of LDs, and the net benefit will become greater if removal of disincentives stimulates even further growth. As importantly, by directly linking compensation to risk, we believe it preserves the essence of kidney donation as a gift, consistent with NOTA and implementable in the United States without altering current legal statutes. [source]

Application of New Organic Fuels in the Direct MgAl2O4 Combustion Synthesis

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2008
Robert Iano
Abstract The paper presents a new version of MgAl2O4 solution-combustion synthesis, based on the individual reactivity of Mg(NO3)2 and Al(NO3)3 with respect to various fuels. Beside the traditionally used fuels (urea, glycine, ,-alanine), new organic reducing agents [monoethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane and triethylenetetramine] have also been used. The study of the individual reactivities of Mg(NO3)2 and Al(NO3)3 with respect to each of the previously mentioned fuels suggested that there is a predilection of the two metal nitrates for certain fuels: urea is the optimum fuel for Al(NO3)3, whereas monoethanolamine represents the most suitable fuel for Mg(NO3)2. It has been shown by X-ray diffraction and thermal analysis that the use of a single fuel in the MgAl2O4 low-temperature combustion synthesis leads to the formation of an amorphous powder. In this case, the formation of pure crystalline MgAl2O4 requires a subsequent thermal treatment at 900 °C with 1 h soaking time. On the other hand, the use of fuel mixtures containing urea and monoethanolamine or urea and ,-alanine proved to be the rational solution for the direct formation of MgAl2O4. It has been shown that, by using the above-mentioned fuel mixtures, one can obtain pure nanocrystalline MgAl2O4 straight from the combustion reaction, no additional calcination being necessary. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Selenium Derivatization of Nucleic Acids for X-Ray Crystal-Structure and Function Studies

CHEMISTRY & BIODIVERSITY, Issue 4 2010
Jia Sheng
Abstract It is estimated that over two thirds of all new crystal structures of proteins are determined via the protein selenium derivatization (selenomethionine (Se-Met) strategy). This selenium derivatization strategy via MAD (multi-wavelength anomalous dispersion) phasing has revolutionized protein X-ray crystallography. Through our pioneer research, similarly, Se has also been successfully incorporated into nucleic acids to facilitate the X-ray crystal-structure and function studies of nucleic acids. Currently, Se has been stably introduced into nucleic acids by replacing nucleotide O-atom at the positions 2,, 4,, 5,, and in nucleobases and non-bridging phosphates. The Se derivatization of nucleic acids can be achieved through solid-phase chemical synthesis and enzymatic methods, and the Se-derivatized nucleic acids (SeNA) can be easily purified by HPLC, FPLC, and gel electrophoresis to obtain high purity. It has also been demonstrated that the Se derivatization of nucleic acids facilitates the phase determination via MAD phasing without significant perturbation. A growing number of structures of DNAs, RNAs, and protein,nucleic acid complexes have been determined by the Se derivatization and MAD phasing. Furthermore, it was observed that the Se derivatization can facilitate crystallization, especially when it is introduced to the 2,-position. In addition, this novel derivatization strategy has many advantages over the conventional halogen derivatization, such as more choices of the modification sites via the atom-specific substitution of the nucleotide O-atom, better stability under X-ray radiation, and structure isomorphism. Therefore, our Se-derivatization strategy has great potentials to provide rational solutions for both phase determination and high-quality crystal growth in nucleic-acid crystallography. Moreover, the Se derivatization generates the nucleic acids with many new properties and creates a new paradigm of nucleic acids. This review summarizes the recent developments of the atomic site-specific Se derivatization of nucleic acids for structure determination and function study. Several applications of this Se-derivatization strategy in nucleic acid and protein research are also described in this review. [source]

Singular fiber of the Mumford system and rational solutions to the KdV hierarchy

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 4 2010
Rei Inoue
We study the singular isolevel manifold Mg(0) of the genus g Mumford system associated to the spectral curve y2 = x2g + 1. We show that Mg(0) is stratified by g + 1 open subvarieties of additive algebraic groups of dimension 0, 1, ,, g, and we give an explicit description of Mg(0) in terms of the compactification of the generalized Jacobian. As a consequence, we obtain an effective algorithm to compute rational solutions to the genus g Mumford system, which is closely related to rational solutions of the KdV hierarchy. © 2009 Wiley Periodicals, Inc. [source]