Collisional damping affects the relationship between ion mass and effective cyclotron frequency in Fourier transform mass spectrometry. The exact mass calibration equation(m/z=A/f+(mneutral/m^^+mneutral)k+B/f(f+(mneutral/m^^+mneutralk))was therefore derived from the characteristic equation of system model, force=m(dv/dt)=qE-qv×B0-ξv,a frictional damping force), in which k is amended by the shift of observed frequency of matrix ion or other known ion in external calibration. The mass obtained by the amended calibration equation is therefore immune to collisional damping and space-charge effects on mass accuracy. The relative errors of ion mass measured were all less than 2×10^-6. 相似文献
?I chose chemistry as a career because it gives me the opportunity to discover and make new things every day. When I wake up I use Skype to catch up with my son Stepan (who is currently finishing his PhD at MSU), since this time of day is the best compromise for our busy schedules given the 10 hour time‐zone difference between Colorado and Moscow…?.“ This and more about Olga V. Boltalina can be found on page 2827.
Bi? O chemistry : A direct regioselective route to bismuth bis(amino)naphthalene compounds, incorporating Bi? O and Bi? C bonds is described, in which an amide precursor is treated with aldehydes, ketones, alkenes, and alkynes, leading to insertion into the Bi? NMe2 bond.
Specific losses of water are observed from the molecular anions of monoximes of α-diketones. Labelling studies, kinetic energy release values and the +E spectra of ions have been used to aid in the elucidation of the fragmentation pathways. It is proposed that the majority of ions have α-keto nitrile structures. 相似文献
Flash photolysis of 2,4,6-trinitrotoluene solutions (TNT) indicates a photochemically induced isomerization leading to the aci-quinoid isomer with an absorption maximum at 460 nm in nonpolar solvents, or the conjugate base of the aci-quinoid isomer with absorption maxima at 500, 540, and 630 nm in polar solvents. Both species, the quinoid isomer and the conjugate base, have transient existence and their identification was based on detailed spectroscopic and kinetic studies presented here. The magnitude of the negative charge on the transient conjugate base was determined with salt effect experiments and found to be equal to unity. 相似文献
Summary: The copolymerization of ethylene and 1,7‐octadiene (OD) was investigated with a constrained‐geometry catalyst. The 13C NMR spectrum of the copolymer indicated cyclization insertion of the OD unit in the penultimate position after a single ethylene insertion step. This unique insertion mode of OD forms a 1,5‐disubstituted cyclononane unit in the main chain of polyethylene.
Copolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst. 相似文献
Summary: The relatively high degree of crystallinity of a new thermoplastic polyimide (PI) makes it a favorable matrix candidate for fiber reinforced composites. This advantage is the result of the ability of the matrix to recrystallize during the composite manufacturing process. In this study we examine the potential nucleating effect of carbon nanotubes on a thermoplastic PI. In addition to their inherent mechanical contribution, the carbon nanotubes help recover a significant proportion of the original crystallinity.
Scanning electron micrograph of the spherulitic structure of a recrystallized carbon nanotube/polyimide film. 相似文献
This study reports the first PEO‐coated polymer nanoparticles synthesis by miniemulsion polymerization of nano‐emulsions prepared by the low‐energy emulsification method called EIP. The surfactant used was Brij 98, a PEO based non ionic commercial surfactant. The partial phase diagram of the system water/Brij 98/styrene was first determined. The Emulsion Inversion Point technique was then used on the water/Brij 98/styrene system to the formation of styrene‐in‐water nano‐emulsions. After miniemulsion polymerization, particle sizes as low as 36 nm were obtained. To the best of our knowledge, this method had not been used for polymerizable system up to now.
The kinetics of chlorine transfer from CH2Cl2, CHCl3, CCl4, and CCl3CN to the triethylsilyl radical was studied in the liquid phase by a competitive method. Br abstraction from 1-bromopentane was used as a reference. The following Arrhenius parameters were determined: where the error limits are two standard deviations (2σ). Based on these results, the observed reactivity trends in the chlorine transfer reactions of Et3Si radicals appear to primarily reflect the variation in entropy of activation rather than in activation energies. 相似文献
Crosslinked products of the form: and have been formed from the interfacial condensation of phosphorus diacid halides with poly(vinyl alcohol). Product yield and amounts of phosphorus reactant included in the product increases as the amount of base increases. Product stability in aqueous systems decreases in the order neutral > base > acid. 相似文献
In the presence of a variety of inorganic salts, p-vinylbenzamide underwent vinyl-type polymerization by anionic initiators to form the polystyrene derivative, whereas in dimethyl sulfoxide as solvent the aromatic polyamide was always obtained through a proton-transfer mechanism regardless of the presence of the salts. In the presence of of the salts, acrylamide is generally polymerized to the polyamide through a proton transfer reaction. 相似文献