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1.
The use of surfactants as additives was demonstrated for the first time in capillary isoelectric focusing (CIEF) to dynamically modify the surfaces of bare fused silica capillaries. These surfactants were zwitterionic sulfobetaines: dodecyldimethyl (3-sulfopropyl) ammonium hydroxide (C12N3SO3), hexadecyldimethyl (3-sulfopropyl) ammonium hydroxide (C16N3SO3) and coco (amidopropyl)hydroxyldimethylsulfobetaine (Rewoteric AM CAS U). They were added directly to the protein-ampholyte mixture, and remained in the capillary during isoelectric focusing and mobilization. The C16N3SO3 and CAS U coatings were shown effective in CEF. Separation of seven IEF protein standards was obtained, with significantly improved resolution compared to that from an uncoated silica capillary. The effect of these surfactants on the electroosmotic flow (EOF) in CIEF was determined. CAS U was effective in suppressing the EOF at neutral and alkaline pH conditions, C16N3SO3 was effective in suppressing EOF at acidic and neutral pH conditions. C12N3SO3 however had little effect on the EOF. The pH gradients formed inside these surfactant coated capillaries were recta-linear at pH 6 to 9 (R2 approximately equal to 0.99). Reproducibility of migration time and peak area was determined. For all three coatings, the migration time standard deviations were less than 1.6 min, and the relative standard deviations of area were below 10%. The protein recovery in the CAS U-modified capillary was quantitative or near-quantitative for five of the seven proteins studied. 相似文献
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3.
John F. Blount Glenna D. Gray Karnail S. Atwal Thomas Y.R. Tsai Karel Wiesner 《Tetrahedron letters》1980,21(46):4413-4416
The α,β-unsaturated ketone yields with allene the photocycloadduct predicted by our empirical photoaddition rule and the byproduct 7. The formation of this material may be rationalized by the sequence → → → → . The isomeric ketone is unreactive under the same conditions, since α addition is prohibited by the rule and β addition is severely blocked. 相似文献
4.
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
5.
The aim of this brief report is to study the behaviour of sheath structure in a multi-component plasma with dust-neutral collisions.
The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential
and sheath width are calculated for collisionally dominated sheath. Comparison of collisionless and collisionally dominated
sheath are made. 相似文献
6.
A facile synthesis of cyanoguanidines from corresponding thioureas is reported using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (water soluble carbodiimide). 相似文献
7.
2-Methyl-6-chloro-10:11-thiopegene-9:4-one, 2:7-dimethyl-10:11-thiopegene-9:4-one and the corresponding methylene bases have been synthesized. These methylene thiopegans furnish corresponding isomeric 2-methyl derivatives on acid treatment. 2-Bromomethyl-7-methyl-10:11-thiopega-2:9-diene-4-one has been condensed with piperidine and diethylamine to incorporate the therapeutically important basic moiety in these compounds. New routes to the synthesis of various substituted 2-methyl-10:11-thiopegans and 2-bromomethyl-10:11-thiopega-2:9-diene-4-ones have been developed with a view to improve their yields. 相似文献
8.
Analysis of a TE011 mode composite sapphire-rutile dielectric resonator has been carried out to study the temperature variation of resonance
frequency, close to the Cs atomic clock hyperfine frequency of 9.192 GHz. The complementary behavior of dielectric permittivity
with temperature of the composite has been exploited to obtain the desired turning point in the resonant frequency. The frequency
of the composite structure is found to be independent of the shield diameter beyond four times the puck diameter. 相似文献
9.
Explicit expressions have been derived for the volume dependence of electron-phonon coupling strength (λ) and the Coulomb pseudopotential (μ*) considering the variation of Fermi momentum (κ
F) and Debye temperature (θ
D) with volume. Ashcroft’s model pseudopotential and RPA form of dielectric screening have been used for obtaining pressure
dependence of transition temperature (T
C) and the logarithmic volume derivative (Φ) of the effective interaction strength (N
0
V) for metallic glass superconductor Mg70Zn30. It has been observed that T
C of the metallic glass Mg70Zn30 decreases rapidly with increase of pressure and the superconducting phase disappears at about 30% decrease of volume, for
which the μ* curve shows a minimum and an elbow is formed in the Φ graph. 相似文献
10.
Unsaturated dicarbonyl compounds which are useful in conjugate cyclization processes are synthesized by a route which makes use of a sequential isomerization and Claisen rearrangement of the allyl ether of a substituted allyl alcohol. 相似文献