A novel tetracyclic ring system. 10H-tetrazolo[5′,1′:3,4][1,2,4]triazino[5,6-b]indole

The reaction of 3-hydrazino-1,2,4-triazino[5,6-b]indole with nitrous acid affords a novel tetracyclic ring system: 10H-tetrazolo[5′,1′:3,4][1,2,4]triazino[5,6-b]indole. The mode of cyclization has been discussed.     

A mild conversion of phenylpropropnoid into rare phenylbutanoids: (E)-4-(2,4,5-trimethoxyphenyl)but-1,3-diene and (E)-4-(2,4,5-trimethozypheny)but-1-ene occuring in Zingiber cassumunar

(E)-4-(2',4',5'-trimethoxyphenyl)but-1,3-diene (4) and (E)-4-(2',4',5'-trimethoxyphenyl)but-1-ene (6), bioactive phenylbutanoids of Zingiber cassumunar, were synthesized exclusively with trans geometry. Treatment of methylmagnesium iodide with (E)-2',4',5'-trimethoxycinnamaldehyde (2), an oxidized product of abundantly available toxic (Z)-phenylpropanoid (1) of Acorus calamus, gave (E)-4-(2',4',5'-trimethoxyphenyl)but-3-en-2-ol (3) which upon dehydration with copper sulphate/silica gel under microwave irradiation for 3 min afforded 4 in 58% yield. Further, catalytic hydrogenation of 4 with 10% Pd/C afforded 4-(2',4',5'-trimethoxyphenyl)butane (5) which upon dehydrogenation with DDQ/SiO2 afforded hypolipidemic 6 in 54% yield.     

Piperaceae alkaloids: Part IV. Structure and Synthesis of Cyclostachine A,Cyclostachine B and Cyclopiperstachine

Three new alkaloids designated as cyclostachine A (2), cyclostachine B (7) and cyclopiperstachine (10) have been isolated from Piper trichostachyon C. DC. Their structures have been derived on the basis of spectral and degradative studies and confirmed by synthesis. The ¹H- and ¹³C-NMR. spectra of these compounds are discussed.     

Frequency-domain fluorescence spectroscopy, a new method for the resolution of complex fluorescence emission

The fluorescence emission from complex chemical and biological samples can be resolved by measuring the frequency-response of the emission, which is now possible from 1 to 2000 MHz. The frequency-response allows determination of the components in a mixture, construction of time-resolved emission spectra, and measurement of the dynamic and hydrodynamic properties of biological macromolecules. The instrumentation is relatively simple, and data acquisition times can be short. At present, this method may be superior to direct measurements of time-resolved fluorescence emission.     

Detection of fallout155Eu and207Bi in a210Pb-dated lake sediment core

Low-energy -ray spectrometry is used to detect fallout¹⁵⁵Eu and²⁰⁷Bi in a²¹⁰Pb-dated sediment core from McKay Lake, Ottawa, Canada. Unlike²⁰⁷Bi which is detected only in two core sections deposited in the mid 1970's,¹⁵⁵Eu is consistently detectable to mid 1960's. A comparison of corresponding¹³⁷Cs and¹⁵⁵Eu inventories in the sediment core indicates that fallout¹⁵⁵Eu derives primarily from the thermal neutron fission of²³⁵U. The derived flux of unsupported²¹⁰Pb at the sediment/water interface is in agreement with previously estimated flux of atmospheric²¹⁰Pb in the Great Lakes region.     

Natural radioactivity distribution in geological matrices around Kaiga environment

Summary The activity and absorbed dose rate of the naturally occurring radionuclides, viz. ²³⁸U, ²³² Th and ⁴⁰K were determined in soil and rock samples collected around Kaiga site. The mean activity levels (Kaiga soil) of naturally occurring ²³² Th are comparable with that in worldwide soil, while concentrations of ²³⁸U and ⁴⁰K are lower than those in worldwide soil. The absorbed dose rate in outdoor air ranged 20-58 nGy ^. h^-1 with a mean of 33.3 nGy ^. h^-1, which is below the world average of 60 nGy ^. h^-1. The total effective dose rate in outdoor air for soils ranged 25.6-74.4 mSv ^. y^-1 with a mean of 43.0 mSv ^. y^-1. The estimated dose rate at Kaiga is comparable with that estimated at Kakrapar and Rawatbhata and much less than that estimated at coastal sites of India.     

Studies in spiroheterocycles. Part XVII. synthesis of novel fluorine containing spiro[indole-pyranobenzopyran] and spiro[indenopyran-indole] derivatives

An elegant one-step synthesis of two novel spiro ring systems viz: spiro[3H-indole-3,4′-(2′-amino-3′-carbonitrile-[4′H]-pyrano[3,2-c]benzopyran)]-2,5′(1H)-dione8 and spiro[(2-amino-3-carbonitrile-indeno[1,2-b]pyran)-4(5H)>3′-[3H]indole]-2′,5(1′H)-diones in 80–85% yields is described. The spiro heterocycles were prepared by the reactions of fluorine containing 3-dicyanomethylene-2H-indol-2-ones with 4-hydroxy-2H-1-benzopyran-2-one and 1H-indene-1,3(2H)-dione respectively. The synthesized compounds have been characterized on the basis of elemental analyses, ir, pmr, ¹⁹F nmr and mass spectral data.     

Determination of organophosphate pesticides at a carbon nanotube/organophosphorus hydrolase electrochemical biosensor

An amperometric biosensor for oganophosphorus (OP) pesticides based on a carbon nanotube (CNT)-modified transducer and an organophosphorus hydrolase (OPH) biocatalyst is described. A bilayer approach with the OPH layer atop of the CNT film was used for preparing the CNT/OPH biosensor. The CNT layer leads to a greatly improved anodic detection of the enzymatically generated p-nitrophenol product, including higher sensitivity and stability. The sensor performance was optimized with respect to the surface modification and operating conditions. Under the optimal conditions the biosensor was used to measure as low as 0.15 μM paraoxon and 0.8 μM methyl parathion with sensitivities of 25 and 6 nA/μM, respectively.