Direct analysis of plant and animal tissue samples by laser electrospray mass spectrometry (LEMS) was investigated using low-energy, femtosecond duration laser vaporization at wavelengths of 800 and 1042 nm followed by nanospray postionization. Low-energy (<50 μJ), fiber-based 1042 nm LEMS (F-LEMS) allowed interrogation of the molecular species in fresh flower petal and leaf samples using 435 fs, 10 Hz bursts of 20 pulses from a Ytterbium-doped fiber laser and revealed comparable results to high energy (75–1120 μJ), 45 fs, 800 nm Ti:Sapphire-based LEMS (Ti:Sapphire-LEMS) measurements. Anthocyanins, sugars, and other metabolites were successfully detected and revealed the anticipated metabolite profile for the petal and leaf samples. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample using Ti:Sapphire-LEMS without the application of matrix. These lipid features were suppressed in both the fiber-based and Ti:Sapphire-based LEMS measurements when the brain sample was prepared using the optimal cutting temperature compounds that are commonly used in animal tissue cryosections.
This paper is concerned with two-person games of perfect information and no chance moves in which play may possibly never terminate. The slow join is a way of playing several such games simultaneously, so as to form a single compound game. Our analysis of the slow join is accomplished by extending the notion of the suspense function from games which satisfy the stopping condition to the onside of games which may continue indefinitely. The remoteness function is also employed in the analysis. 相似文献
RecentlyÚlehla [1980] gave a complete analysis of an impartial two-person combinatorial game called Hackendot which was invented by von Neumann. In this note we consider a partizan (or unimpartial) variation of Hackendot. Úlehla's analysis uses the Sprague-Grundy theory for disjunctive sums of impartial games. Our analysis employs Conway's theory for disjunctive sums of partizan games, two certain “biased” ways of “adding” dyadic rationals, and the usual addition of numbers. 相似文献
This paper reports calculations of the rate of isomerization of HCN - HCN based on the theory of Gary and Rice as extended by Zhao and Rice. The major task is to determine the effect of intramolecular energy transfer on the prediction of the rate of isomerization. Both the full three-dimensional (3D) system and the reduced two-dimensional (2D) system obtained from freezing CN bond at 1.159 A are analyzed to check the validity of the freezing bond approximation. Meanwhile, RRKM rates are calculated to test RRKM choice of the transition state by comparing to Gary-Rice three-state model. The comparison shows that the rates from 2D model and 3D model are differing up to 20% with 2D rates consistently larger. The intramolecular energy transfer modifies the isomerization rate for HCN system up to 30% that is modestly small by the expectation. The isomerization rate predicted from RRKM theory is greater than those of Gary-Rice three-state model theory up to 65%, and it overstimates the rates under all consider 相似文献
Highly functionalized gamma-lactams are key intermediates for the synthesis of numerous biologically significant natural products. We herein described the synthesis of various chiral gamma-lactams via intramolecular C-H insertion of alpha-diazo-alpha-(phenylsulfonyl)acetamides derived from alpha-amino acids, which possess various functional groups. The cyclizations were highly regio- and stereoselective to afford chiral gamma-lactam motifs in high yields. 相似文献