This paper describer moving slice septa forreducing scattered and random events in multi-ring positron emission tomographr (PET) and a new simple method of threedimensional (30) image reconstruction which is useful when the maximum axial acceptance angle of coincidence is not 100 large. The moving septa considered are linear and sinusoidal piston motions of parallel septa, axis wobbling o f parallel septa and rotation of spiral septa. The proposed reconstruction algorithm is basically a filtered(iu) backprojection(-iu) method. The low frequency image is reconstructed using direct (and cross) plane coincidence as in the conventional way, and the high frequency image is reconstructed using all projection data through high-pass filtering. The two images are superimposed in such a waythatthe final frequencyresponseis normal.Theaxialcrasstalkiseffectivelyeliminated by Gaussian high-pass filtering with negligible increase in statistical noise, and i t is possible to include most o f the oblique coincidence events in the reconstruction in a single pass. Simulation studies with a maximum axial acceptance angle of 1 7 . 6 degrees ( + l o ring difference) show satisfactory results.
Synthesis and Pharmacological Properties of 4-Methyl-1-(methylsulfinylmethyl)-7-thiabicyclo[3.3.1]non-3-en-2-one 7-Oxide. -Title compound (V) is obtained by a multicomponent reaction of propanone, formaldehyde, methanethiol, and sodium sulfide, and following oxidation of the resulting thiabicycle (IV). Compound (V) exhibits antiinflammatory and antiarrhythmic activities. -(ULENDEEVA, A. D.; NIKITINA, T. S.; BAEVA, L. A.; SPIRIKHIN, L. V.; KARACHURINA, L. T.; KHISAMUTDINOVA, R. Y.; MAKARA, N. S.; ZARUDII, F. S.; LYAPINA, N. K.; Khim.-Farm. Zh. 38 (2004) 12, 15-17; Inst. org. khim. Ufim. nauchn. tsentra Ross. Akad. nauk, Ufa, Russia; Russ.) -Klein 23-173
Some representatives of the class of sulfur-containing organic compounds, including derivatives of sulfones [1], dialkyldisulfides [2], and 3-thiabicyclohexanecarboxylic acid [3], were reported to possess anti-inflammatory activity. Biological activity is also inherent in 1,2,5-thiadiazole and its condensed derivatives, which act upon central nervous system and influence tissue metabolism [4].In continuation of our investigations into new bicyclic bis-sulfoxides, we have synthesized 4-methyl-1-(methylsulfinylmethyl)-7-thiabicyclo[3.3.1]non-3-en-2-one-7-oxide (I) and studied the anti-inflammatory and antiarrhythmic properties of this compound.The synthesis I was conducted according to the scheme depicted below. In the first step, we obtained 4-methyl-1-(methylthiomethyl)-7-thiabicyclo[3.3.1]non-3-en-2-one (II) via alkylthiomethylation of propanone with a mixture of formaldehyde, methylmercaptan, and sodium sulfide in an alkaline medium [5]. In the second step, compound II was oxidized in a 28 -30% aqueous hydrogen peroxide solution at 20°C, and the target compound I was obtained with a yield of 95%.The purity and the proposed structures of the synthesized compounds were confirmed by the results of elemental analyses and by the data of IR, 1 H NMR, and 13 C NMR spectroscopy (Tables 1 and 2). The IR spectra of compounds I and II exhibit absorption bands at 1656, 1618, 1624, and 1654 cm -1 characteristic of the stretching vibrations of the C=O and C=C bonds [6].In the 13 C NMR spectrum of compound I, the signals from carbon atoms C 6 (48.43 and 48.54 ppm), C 8 (56.75 and 56.06 ppm), C 11 (62.62 and 61.52 ppm), and C 13 (36.08 and 35.79 ppm) are shifted toward lower fields as compared to the analogous signals in the spectrum of compound II (Table 2). In addition, almost all signals in the 13 C NMR spectrum of compound I are doubled, which is indicative of the existence of two isomers. The spectra were assigned separately to each isomer. The appearance of a diastereomer pair is related to the presence of a chiral carbon atoms C 1 and a pyramidal sulfoxide sulfur atom in the aliphatic substituent, which make possible the formation of two d-diastereomers with R*R* and R*S* centers [7].The 1 H C NMR spectrum of compound I displays clearly distinguished signals due to the greater isomer and shows the signals from diastereotopic protons at C 11 in the form of two doublets with a geminal spin -spin coupling constant of 13.3 Hz and a relative chemical shift Dd = 0.61 ppm. For the second diastereomer, this difference is below 0.29 ppm. Based on the published data [7], the diastereomer with a greater difference of the chemical shifts is identified as the erythro isomer (Ia), while the component with a smaller Dd value is identified as the threo isomer (Ib). Both isomers are 659
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