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101.
102.
Rabindra N. Roy Lakshmi N. Roy Shahaf Ashkenazi Joshua T. Wollen Craig D. Dunseth Michael S. Fuge Jared L. Durden Chandra N. Roy Hannah M. Hughes Brett T. Morris Kevin L. Cline 《Journal of solution chemistry》2009,38(4):449-458
The values of the second dissociation constant, pK
2, of N-(2-hydroxyethyl) piperazine-N′-2-ethanesulfonic acid (HEPES) have been reported at twelve temperatures over the temperature range 5 to 55 °C, including
37 °C. This paper reports the results for the pa
H of eight isotonic saline buffer solutions with an I=0.16 mol⋅kg−1 including compositions: (a) HEPES (0.01 mol⋅kg−1) + NaHEPES (0.01 mol⋅kg−1) + NaCl (0.15 mol⋅kg−1); (b) HEPES (0.02 mol⋅kg−1) + NaHEPES (0.02 mol⋅kg−1) + NaCl (0.14 mol⋅kg−1); (c) HEPES (0.03 mol⋅kg−1) + NaHEPES (0.03 mol⋅kg−1) + NaCl (0.13 mol⋅kg−1); (d) HEPES (0.04 mol⋅kg−1) + NaHEPES (0.04 mol⋅kg−1) + NaCl (0.12 mol⋅kg−1); (e) HEPES (0.05 mol⋅kg−1) + NaHEPES (0.05 mol⋅kg−1) + NaCl (0.11 mol⋅kg−1); (f) HEPES (0.06 mol⋅kg−1) + NaHEPES (0.06 mol⋅kg−1) + NaCl (0.10 mol⋅kg−1); (g) HEPES (0.07 mol⋅kg−1) + NaHEPES (0.07 mol⋅kg−1) + NaCl (0.09 mol⋅kg−1); and (h) HEPES (0.08 mol⋅kg−1) + NaHEPES (0.08 mol⋅kg−1) + NaCl (0.08 mol⋅kg−1). Conventional pa
H values, for all eight buffer solutions from 5 to 55 °C, have been calculated. The operational pH values with liquid junction
corrections, at 25 and 37 °C have been determined based on the NBS/NIST standard between the physiological phosphate standard
and four buffer solutions. These are recommended as pH standards for physiological fluids in the range of pH = 7.3 to 7.5
at I=0.16 mol⋅kg−1. 相似文献
103.
Croley TR Hughes RJ Hao C Metcalfe CD March RE 《Rapid communications in mass spectrometry : RCM》2000,14(23):2154-2157
While developing a liquid chromatography/tandem mass spectrometry method for the analysis of the flavonoid quercitin, it was observed that quercetin (3,3',4',5,7-pentahydroxyflavone) exhibited clustering in both the positive and negative ion mode. Two series of positive ion clusters were observed; the first series corresponds to singly charged [2M + Na](+) at m/z 627.2 to [13M + Na](+) at m/z 3947.5, while the second series corresponds to doubly charged [7M + 2Na](2+) at m/z 1080.4 to [25M + 2Na](2+) at m/z 3798.5. In the negative ion mode, the behavior of quercetin parallels that of apigenin (4',5,7-trihydroxyflavone) in that [M + NO(3)](-), [2M + NO(3)](-), and [3M + NO(3)](-) were observed at m/z 364.1, 666.0, and 968.9, respectively; in addition, quercitin clusters with chloride ions ([2M + Cl](-) at m/z 638.9 and [3M + Cl](-) at m/z 940. 9) were observed. The results of tandem mass spectrometric examination of several cluster ions are reported. 相似文献
104.
Pennington DA Clegg W Coles SJ Harrington RW Hursthouse MB Hughes DL Light ME Schormann M Bochmann M Lancaster SJ 《Dalton transactions (Cambridge, England : 2003)》2005,(3):561-571
The silyl ethers 3-But-2-(OSiMe3)C6H3CH=NR (2a-e) have been prepared by deprotonation of the known iminophenols (1a-e) and treatment with SiClMe3 (a, R = C6H5; b, R = 2,6-Pri2C6H3; c, R = 2,4,6-Me3C6H2; d, R = 2-C6H5C6H4; e, R = C6F5). 2a-c react with TiCl4 in hydrocarbon solvents to give the binuclear complexes [Ti{3-But-2-(O)C6H3CH=N(R)}Cl(mu-Cl3)TiCl3] (3a-c). The pentafluorophenyl species 2e reacts with TiCl4 to give the known complex Ti{3-But-2-(O)C6H3CH=N(R)}2Cl2. The mononuclear five-coordinate complex, Ti{3-But-2-(O)C6H3CH=N(2,4,6-Me3C6H2)}Cl3 (4c), was isolated after repeated recrystallisation of 3c. Performing the dehalosilylation reaction in the presence of tetrahydrofuran yields the octahedral, mononuclear complexes Ti{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (5a-e). The reaction with ZrCl4(THF)2 proceeds similarly to give complexes Zr{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (6b-e). The crystal structures of 3b, 4c, 5a, 5c, 5e, 6b, 6d, 6e and the salicylaldehyde titanium complex Ti{3-But-2-(O)C6H3CH=O}Cl3(THF) (7) have been determined. Activation of complexes 5a-e and 6b-e with MAO in an ethene saturated toluene solution gives polyethylene with at best high activity depending on the imine substituent. 相似文献
105.
[reaction: see text] Enantioselectivity of the cyclization of 1 varies at different stages in the reaction. X-ray crystallography has shown that 1 exists as enantiomerically pure (M) and (P) chiral helical structures defined by the relative orientations of the arene, amide, and alkene. The relative rates of interconversion of the rotamers of 1 have been established, leading to mechanistic proposals to account for the variation of ee based on kinetic resolution effects. 相似文献
106.
It is shown from SCF-MO studies using localised orbitals that the angles between the lone-pairs in H2O and H2S are 115° and 127°, in agreement with the qualitative predictions of the Sidgwick-Powell theory. 相似文献
107.
Chemometric techniques have been applied to FTIR and DSC data to correlate polymer composition. Since structural differences
in the polymers with only hydrocarbon structure, often cause subtle changes in spectra, the ability of chemometric techniques
is required to discern these differences. FTIR spectra and thermal fractionation using DSC were measured for 28 types of polyethylenes
(PE) varying in chain branching type, content and distribution. Unsupervised clustering methods such as principal component
analysis (PCA) and supervised discriminant analysis were used to classify the PEs according to their structural class. The
DSC data was the more successful in both classifying PEs according to their class.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
108.
109.
Colan E. Hughes 《Progress in Nuclear Magnetic Resonance Spectroscopy》2004,45(3-4):301-313
110.