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1.
E.Ann Hallinan Clifford R. DornWilliam M. Moore Gina M. JeromePamela T. Manning Barnett S. Pitzele 《Tetrahedron letters》2003,44(39):7345-7347
Described is a method of introducing trifluoroalkyl groups at C-6 of lysine. This chemistry has the potential to introduce a variety of functionality at C-6 of lysine. 相似文献
2.
Transport of surface-modified iron nanoparticle in porous media and application to arsenic(III) remediation 总被引:1,自引:0,他引:1
Sushil Raj Kanel Dhriti Nepal Bruce Manning Heechul Choi 《Journal of nanoparticle research》2007,9(5):725-735
The surface-modified iron nanoparticles (S-INP) were synthesized, characterized and tested for the remediation of arsenite
(As(III)), a well known toxic groundwater contaminant of concern. The S-INP material was fully dispersed in the aqueous phase
with a particle size distribution of 2–10 nm estimated from high-resolution transmission electron microscopy (HR-TEM). X-ray
photoelectron spectroscopy (XPS) revealed that an Fe(III) oxide surface film was present on S-INP in addition to the bulk
zero-valent Fe0 oxidation state. Transport of S-INP through porous media packed in 10 cm length column showed particle breakthroughs of 22.1,
47.4 and 60 pore volumes in glass beads, unbaked sand, and baked sand, respectively. Un-modified INP was immobile and aggregated
on porous media surfaces in the column inlet area. Results using S-INP pretreated 10 cm sand-packed columns containing ∼2 g
of S-INP showed that 100 % of As(III) was removed from influent solutions (flow rate 1.8 mL min−1) containing 0.2, 0.5 and 1.0 mg L−1 As(III) for 9, 7 and 4 days providing 23.3, 20.7 and 10.4 L of arsenic free water, respectively. In addition, it was found
that 100% of As(III) in 0.5 mg/L solution (flow rate 1.8 mL min−1) was removed by S-INP pretreated 50 cm sand packed column containing 12 g of S-INP for more than 2.5 months providing 194.4
L of arsenic free water. Field emission scanning electron microscopy (FE-SEM) showed S-INP had transformed to elongated, rod-like
shaped corrosion product particles after reaction with As(III) in the presence of sand. These results suggest that S-INP has
great potential to be used as a mobile, injectable reactive material for in-situ sandy groundwater aquifer treatment of As(III). 相似文献
3.
4.
Yannick Ortin Paul O'Donohue Helge Müller-Bunz Anthony R. Manning 《Journal of organometallic chemistry》2004,689(9):1657-1664
Treatment of the aldehyde (η4-C4Ph4)Co(η5-C5H4-CHO) (4b) with tert-butyllithium or phenyllithium yields the secondary alcohols (η4-C4Ph4)Co(η5-C5H4-CH(R)OH), where R=tert-butyl (5) or phenyl (6). Protonation of 5 and 6 at −80 °C furnishes the deep purple, cobalt-stabilized cations, 7 and 8, respectively, both of which exhibit restricted rotation about the external C5H4-CHR+ linkage on the NMR time-scale. These data indicate a minimum value for the barrier to rotation of 15 kcal mol−1, but it is certainly much higher, indicating a considerable degree of C-C double bond character. X-ray crystal structures of 4b, 5 and also of the ketone (η4-C4Ph4)Co(η5-C5H4-C(O)CH3 (4a) are reported. The secondary alcohol 5 exhibits disorder in the solid state because of the presence of diastereomers as a consequence of the stereogenic center at the α-carbon and the clockwise or anticlockwise propeller orientations of the tetraphenylcyclobutadiene ligand. 相似文献
5.
Manning GS 《Journal of the American Chemical Society》2003,125(49):15087-15092
X-ray diffraction structures of the nucleosome core particle along with a variety of experiments are consistent with the idea that an important source of the free energy holding DNA to the superhelical ramp on the histone octamer surface is obtained from a relatively small amount of electrostatic neutralization of the DNA phosphate charge by positively charged histone groups, especially arginine residues. Here we present a theoretical analysis of a simple model that emphasizes the competition between the high degree of bending of the stiff DNA molecule required for its tight curvature on the histone octamer and the neutralization of the DNA phosphate charge by basic histone residues. Our calculation accounts for the strong influence of condensed counterions on the electrostatic interactions. We find that the minimum amount of free energy required to bend DNA into axial conformity with the superhelical ramp at physiological salt concentration can be provided by a scant 6% neutralization of the phosphate charge, in close correspondence to the stoichiometric neutralization of phosphate charge by the arginine side chain that intrudes into the inward-facing minor groove of each DNA double helical turn. 相似文献
6.
Howard C. Haas Monis J. Manning Martin H. Mach 《Journal of polymer science. Part A, Polymer chemistry》1970,8(7):1725-1730
Differential thermal analysis has been used to study the fusion of aqueous thermally reversible gels of gelatin and polyacrylylglycinamide (PAG). In the case of gelatin gels, endotherms close to the melting point are readily observed and these are sometimes preceeded by a small exothermic heat of gel reorganization. Calculations are presented to show that breaking of the gelatin gel network requires only a small fraction of the observed endothermic heat of fusion and that most of the heat is required for melting larger crystallites within gelatin aggregates and for perhaps a helix → coil transition. Failure to observe endotherms by DTA over the known temperature range of fusion of PAG gels is consistent with prior measurements and conclusions. The noncrystallinity of PAG gels and soluble aggregates together with a heat of crosslinking of only ?5 to ?10 kcal/mole of crosslinks places the heat of fusion of PAG gels outside the lower limits of DTA sensitivity. 相似文献
7.
The geometries of ten isomers of dimethyl cyclohexane were determined by ab initio gradient geometry refinement with the 4-21G basis set. It is found that many intramolecular interactions are clearly manifested by correlated structural trends, and that they are consistent with strain energies calculated by employing previously defined ab initio group equivalents. Specifically, non-bonded interactions are found between two adjacent methyl groups in some of the forms, and between axial methyl groups and adjacent axial C? H bonds in others. Unperturbed axial C? H and C? C bonds are consistently longer than equatorial bonds. In general, C? H bonds which are involved in non-bonded repulsive interactions are shortened, i.e., strengthened, and the corresponding H? C? C angles are large, compared to non-interacting parameters. 相似文献
8.
-A spectrophotometric method has been developed which is applicable to the determination of extremely small quantities of osmium. Osmium is oxidised to the octovalent state, then added to an acidic aqueous solution containing 1:5-diphenylcarbohydrazide (DPC). After heating the aqueous solution to 65°, the osmium-DPC complex is extracted with chloroform. A molar absorbancy index of about 150,000 is obtained. From 7 to 25 μg of osmium can be determined with a coefficient of variation of 6%. It was established that FeIII, CuII, RuIII and AuIII seriously interfere in the determination of osmium by this method, while CrVI, NiII, MoVI, IrIII and chloride interfere only when present in relatively high concentrations. 相似文献
9.
M.J. Boylan J. Bellerby Josephine Newman A.R. Manning 《Journal of organometallic chemistry》1973,47(2):C33-C35
Whereas Co2(CO)8 and RNC (R= Me, Et, and Cy) react to give mixtures of [(RNC)5Co] [Co(CO)4] and the covalent, carbonyl-bridged [(RNC)mCo2(CO)8?m] derivatives (m = 1–3), [(π-dienyl)Fe(CO)2]2 give only [(π-dienyl)2Fe2(CO)4?n(CNR)n] complexes (dienyl = C5H5, MeC5H4 and C9H7; n = 1–2) that exist in solution as mixtures of cis- and trans-CO- and RNC-bridged tautomers with the μ-RNC species decreasing in importance as the bulk of R increases. 相似文献
10.
Anthony Manning 《Bulletin of the Brazilian Mathematical Society》1992,22(2):157-177
The trouble with Newton's method for finding the roots of a complex polynomial is knowing where to start the iteration. In this paper we apply the theory of rational maps and some estimates based on distortion theorems for univalent functions to find lower bounds, depending only on the degreed, for the size of regions from which the iteration will certainly converge to a root. We can also bound the number of iterations required and we give a method that works for every polynomial and takes at most some constant timesd
2(logd)2 log(d
3/) iterations to find one root to within an accuracy of . 相似文献