Technical study for SPECT of the head using slant hole collimator

The performance of a 160 keV slant hole collimator (160 keV SH) was compared with that of a 140 keV high resolution collimator (140 keV HR) for SPECT imaging of the head using 99mTc. The minimum radius of revolution was reduced from about 23 cm to 13 cm using 160 keV SH. Relative sensitivity of the 160 keV SH was 108% of that of the 140 keV HR. Compared with SPECT using 140 keV HR, 160 keV SH SPECT yielded approximately a 15% increase in resolution. The 160 keV SH SPECT images of phantom were superior in resolution and contrast to that of 140 keV HR SPECT. We concluded that high quality SPECT images of the head can be obtained from rotating gamma cameras equipped with slant hole collimators.     

Steroidal oligoglycosides from Solanum nigrum

Two new steroidal saponins, named nigrumnins I and II, together with two known saponins were obtained from the whole plant of Solanum nigrum L. On the basis of spectroscopic analysis (1H-NMR, 13C-NMR, 1H-1H COSY, TOCSY, HMQC, HMBC and FAB-MS), nigrumnin I was established as (25R)-5alpha-spirostan-3beta-ol 3-O-betaD-xylopyranosyl-(1-->3)-[alpha-L-arabinopyranosyl-(1 -->2)]-beta-D- glucopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl(1-->2)]-beta-D- galactopyranoside (1), and nigrumnin II was elucidated as (25R)-3beta,17alpha-dihydroxy-5alpha-spirostan-1 2-one 3-O-beta-D-xylopyranosyl-(1-->3)-[alpha-L-arabinopyranosyl-(1--> 2)]-beta-D-glucopyranosyl-(1-->4)-[alpha-L-rhamnopyra- nosyl-(1-->2)l-beta-D-galactopyranoside (2).     

Cobalt-catalyzed Heck-type reaction of alkyl halides with styrenes

A cobalt complex, CoCl2[1,6-bis(diphenylphosphino)hexane], catalyzes an alkylation reaction of styrenes in the presence of Me3SiCH2MgCl in ether to yield beta-alkylstyrenes. A variety of alkyl halides including alkyl chlorides can be employed as an alkyl source. A radical mechanism is strongly suggested for this alkylation reaction.     

Bestimmung von Stickstoff in Sojabohnenmehl und Rapssamenkuchen

Ohne Zusammenfassung     

Acid-catalyzed reaction of pyrazolo[1,5-a]pyridines with aldehydes: Formation of bis(pyrazolo[1,5-a]pyrid-3-yl)methane

Reaction of pyrazolo[1,5-a]pyridines with aldehydes in the presence of trifluoroacetic acid gave bis[pyrazolo[1,5-a]pyrid-3-yl)methanes in high yields.     

Experimental and theoretical study on gas-phase ion/molecule reactions of silver trimer cation, Ag3+, with 12-crown-4

The reaction mechanisms of silver trimer cation, Ag3+, with 12-crown-4 (12C4) were studied experimentally and theoretically. Using a cylindrical ion trap time-of-flight mass spectrometer, gas-phase ion/molecule reactions of Ag3+ with 12C4 were observed. Metal-ligand complexes of [Ag(12C4)]+, [Ag3(12C4)]+ and [Ag3(12C4)2]+, and of [Ag(12C4)2]+ and [Ag3(12C4)3]+, were observed as the reaction intermediates and terminal products, respectively. The formations of the [Ag12C4]+ and [Ag(12C4)2]+ complexes indicated that the neutral dimer (Ag2) had been eliminated from the trimer cation. From the results of ab initio calculations at the HF/LanL2DZ level of theory and the experiments, it is suggested that three 12C4 molecules can attach to Ag3+ through consecutive reactions and that neutral Ag2 can be easily eliminated from [Ag3(12C4)]+.     

Synthesis of a Pentacene‐Type Silaborin via Double Dehydrogenative Cyclization of 1,4‐Diboryl‐2,5‐disilylbenzene

A new pentacene‐type silaborin, in which three benzene rings are bridged by silicon and boron atoms, has been synthesized and characterized by using NMR spectroscopy and X‐ray crystallographic analysis. The precursor, 1,4‐bis(dimesitylboryl)‐2,5‐bis(phenylsilyl)benzene ( 4 ), was prepared by stepwise introduction of a silyl group and a boryl group to a benzene ring starting from 1,4‐dibromobenzene. Double cyclization of 4 proceeds by a H‐Mes exchange and a B‐H/C‐H dehydrogenative condensation to afford pentacene‐type silaborin 5 . X‐ray crystal structure analysis reveals that 5 adopts a bent structure rather than a planar one. UV/Vis spectra and DFT calculations for 5 reveal a lowering of the LUMO energy level compared with corresponding anthracene‐type 3 .