Dichromate oxidation is a simple technique that is often Ilsed to estimate the energy content of eggs in studies of marine invertebrate life histories (1). We used this method to measure the energy contents af the eggs of 12 species of marine annelids. In combinati on with measures of egg ash­ free dry weight (AFDW), these data yielded estimates of AFDW-specific energy density that were mostly ...

The 3+2 cycloaddition reaction of 1-(4-phenylphenacyl)-1,10-phenanthrolinium ylide 4 with activated alkynes gave pyrrolo[1,2- 4a][1,10]phenanthrolines 6a-d. The "one pot" synthesis of 6a,b,d from 4, activated alkenes, Et(3)N and tetrakis-pyridine cobalt (II) dichromate (TPCD) is described. The helical chirality of pyrrolophenanthrolines 6b-d was put in evidence by NMR spectroscopy.

To each weighted graph F, two invariants, a polynomial Pf(x,y, z) and the signature rj(r), are defined. The various partial degress of Pr(x,y, z) and c(T) are expressed in terms of maximal spanning graphs of T. Furthermore, one unexpected property of Tutte's dichromate is proved. These results are applied to knots or links in S3 .

Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the ke...

Abstract Chemical oxygen demand (COD) is one of the critical environmental parameters in determining organic matter water matrices. The conventional dichromate method employs hazardous reagents and heat reflux. In order to reduce waste, several alternative methods have been proposed replace dichromate. photoelectrochemical COD (PeCOD) has become a promising for being less time-consuming, enviro...

BACKGROUND Exposure to chromium during electroplating is a recognised though poorly characterised cause of occupational asthma. The first series of such patients referred to a specialist occupational lung disease clinic is reported. METHODS The diagnosis of occupational asthma was made from a history of asthma with rest day improvement and confirmed by specific bronchial provocation testing w...