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231.
In the cosmic ray experiments deep underground in the Kolar Gold Mines, a special class of events has been observed, at present
6 in number, characterised by several, (in general 3), charged particles arising from a vertex, either in air or in the thin
material of the detectors, with large opening angles; the vertex is at a distance of around 70–100 cms from the rock wall.
The most plausible interpretation of these events is that they are due to the decay of new, massive and long-lived particles
produced in neutrino collisions inside rock, or through hitherto unknown processes. 相似文献
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Acid catalyzed condensation of resorcinol or 2-methylresorcinol with 2 equiv. of an acetoxymethylpyrrole gave bis(pyrrolylmethyl)benzene derivatives in moderate yields; these afforded a series of novel aromatic benziporphyrins using the MacDonald "3 + 1" methodology. 相似文献
238.
Colloidally dispersed niobate nanosheets with the thickness of 1.8 nm and controlled mean lateral sizes of 0.15-7.8 mum were prepared and their liquid crystallinity was examined. The nanosheet colloids with different lateral sizes were obtained by exfoliation of single crystals of layered niobate K4Nb6O17 and subsequent ultrasonication. Naked-eye and microscope observations of the nanosheet colloids between crossed polarizers revealed liquid crystallinity of the sols characterized by birefringence as functions of the lateral sizes and concentration of the nanosheets. The nanosheet colloids with smaller lateral sizes (0.15-1.9 mum) varied from isotropic to biphasic (isotropic + liquid crystalline), and finally to fully liquid crystalline states as the colloid concentration increased. The phase transition concentrations (from isotropic to biphasic and biphasic to liquid crystalline) decreased with increasing aspect ratio (lateral-to-thickness ratio) of the nanosheets, almost in accordance with the prediction by Onsager theory, indicating that the liquid crystallinity is explained basically by excluded-volume effect between the nanosheets. On the other hand, the colloids with larger lateral sizes (6.2 and 7.8 mum) stably kept liquid crystalline state even at very low concentration (5.1 x 10-6 in volume fraction), which was much lower than that expected from the theory. 相似文献
239.
Preparation and synthetic applications of 2-halotryptamines: synthesis of elacomine and isoelacomine
The preparation of 2-halotryptamines from tryptamine is described. New stereoselective intramolecular iminium ion spirocyclization methodology for the construction of spiro[pyrrolidine-3,3'-oxindoles] is outlined in synthetic studies of elacomine (1) and isoelacomine (2). [reaction: see text] 相似文献
240.
A flow type microbial biosensor for direct measurement of trichloroethylene (TCE) was developed. The unique features of this novel microbial sensor were the use of the TCE degrading bacterium Pseudomonas aeruginosa JI104, the electrical detection of the chloride ion released by microbial degradation, and flow cell made of glass. Glass cell was used in order to suppress adsorption of TCE and made a closed reaction cell. Vaporization of TCE during the measurement was prevented using closed flow cell. The performance of the sensor was evaluated from following aspects; such as pH of the carrier solution, amount of the immobilized microbe, flow rate and injection volume. The sensor signals were linearly proportional to the concentration of TCE in the range from 0.03 to 2 mgl(-1), which is suitable for the determination of suspected samples to be drinkable water or not. The sensor performance was checked on the real sample, and this system showed good response in ground water, indicating its applicability for the on line monitoring at TCE contaminated areas or hazardous sites. 相似文献