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111.
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113.
K. Suchanek M. Suchanek A. Nikiel T. Pałasz M. Abboud A. Sinatra P.-J. Nacher G. Tastevin Z. Olejniczak T. Dohnalik 《The European physical journal. Special topics》2007,144(1):67-74
An accurate optical method to measure the nuclear
polarization of 3He atoms in the 11S ground state is
described. The absorption of a weak, probe laser beam is used to
measure the relative populations of two hyperfine sublevels of the
23S metastable state that are not addressed by the pumping
laser beam. Since a common spin temperature between the ground and
metastable states is established by metastable exchange
collisions, the nuclear polarization can be derived from these
absorption measurements. The method is highly sensitive, robust,
and can be used to monitor the dynamics of optical pumping and
relaxation processes without interfering with them. It was
successfully implemented and tested in the 0.45–2.0 T magnetic
field range at the 3He gas pressure up to 67 mbar. 相似文献
114.
We prove that the small scale structures of the stochastically forced Navier–Stokes equations approach those of the naturally associated Ornstein–Uhlenbeck process as the scales get smaller. Precisely, we prove that the rescaled kth spatial Fourier mode converges weakly on path space to an associated Ornstein–Uhlenbeck process as |k| . In addition, we prove that the Navier–Stokes equations and the naturally associated Ornstein–Uhlenbeck process induce equivalent transition densities if the viscosity is replaced with hyper-viscosity. This gives a simple proof of unique ergodicity for the hyperviscous Navier–Stokes system. We show how different strengthened hyperviscosity produce varying levels of equivalence. 相似文献
115.
116.
Katritzky AR Scriven EF Majumder S Akhmedova RG Vakulenko AV Akhmedov NG Murugan R Abboud KA 《Organic & biomolecular chemistry》2005,3(3):538-541
Nitration of pyridines 1a-o with nitric acid in trifluoroacetic anhydride, gave the corresponding 3-nitropyridines 6a-n in yields of 10-83%. 相似文献
117.
Two new ferrocene derivatives, 7-ferrocenyl-2,4,6-heptatrienal (1) and 7-ferrocenyl-2,4,6-heptatrienol (2), were synthesized and characterized. These two compounds possess a rigid triene chain conjugated to one of the cyclopentadienyl rings of the ferrocene residue, and as a result, they exhibit very stiff structures. The electronic absorption and electrochemical properties of these compounds were utilized to investigate their host-guest binding interactions with the receptors alpha-cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD) in aqueous solution. From electronic absorption measurements binding constants in the range 790-12900 M(-)(1) were obtained; beta-CD formed more stable complexes than alpha-CD with both guests. Electrochemical measurements suggest some degree of site selectivity in the complexation processes, with beta-CD binding preferentially to the ferrocene moiety while alpha-CD interacts with the unsaturated chain. 相似文献
118.
119.
Orugunty RS Wright DL Battiste MA Helmich RJ Abboud K 《The Journal of organic chemistry》2004,69(2):406-416
It has been known for several decades that a highly functionalized family of tetrahalobicyclo[3.2.1]octadienes are readily available through the cycloaddition of furan or cyclopentadiene with either tetrachloro- or tetrabromocyclopropene. However, the application of these highly functionalized building blocks in synthesis has remained relatively unexplored in relation to their better-known counterparts derived through oxyallyl cation additions. As a first step toward utilizing these highly versatile intermediates in synthesis, a study of the addition of various nucleophiles to the halogenated nucleus has been conducted. It has been found that these halogenated systems are amenable to a wide range of functionalizations in high yields and with good selectivities. 相似文献
120.
The isolation and identification of the first examples of anhydrous lanthanide chloride tetraphenylporphyrin complexes have been described. The purple complexes were generated by the reaction of dilithiotetraphenylporphyrin bis(dimethoxyethane) with lanthanide trichloride tris(tetrahydrofuran) salts to yield the products in up to 85% yield. The crystal structures for the holmium and ytterbium complexes are also presented. 相似文献