Fouling and corrosion in an open recirculating cooling system

The paper discusses the problem of fouling and corrosion in the Service Water System of a nuclear reactor employing an open recirculating cooling system. Field and laboratory experiments were carried out using carbon steel as test material. The studies included corrosion rate measurements, corrosion product characterisation (using XRD, EDAX and IRAS), and the effects of addition of biocide (chlorine) and corrosion inhibitor (polyphosphates) on the bacterial population of the cooling water. The fouling films which developed on metal and glass coupons as well as debris collected from within the cooling system were chemically characterised. The results indicated the prevalence of microbiologically induced corrosion (MIC) within the system. The findings are discussed in the light of the information available on MIC of cooling water systems.     

Furanoheliangolides and other compounds from Calea hymenolepis

Calea hymenolepis afforded in addition to known compounds two new furanoheliangolides, one being a Diels-Alder adduct with myrcene, a p-hydroxyacetophenone derivative and two dimeric ones, again being formal Diels-Alder adducts. The structures were elucidated by highfield ¹H NMR spectroscopy.     

Effects of high temperature and low pH on photosystem 2 photochemistry in spinach thylakoid membranes

The effects of temperature (25–45 °C) and pH (7.5–5.5) on photosystem (PS) 2 was studied in spinach (Spinacia oleracea L.) thylakoid membranes using chlorophyll a fluorescence induction kinetics. In high temperature and low pH treated thylakoid membranes a decline in the variable to maximum fluorescence ratio (F_v/F_m) and PS 2 electron transport rate were observed. More stacking in thylakoid membranes, studied by digitonin fractionation method, was observed at low pH, while the degree of unstacking increased under high temperature conditions. We conclude that the change in pH does not significantly affect the donor/acceptor side of PS 2 while high temperature does. Fluorescence emission spectra at 77 K indicated that low pH is associated with energy redistribution between the two photosystems while high temperature induced changes do not involve energy re-distribution. We suggest that both, high temperature and low pH, show an inhibitory effect on PS 2 but their mechanisms of action are different.     

Histochemical demonstration of certain testicular enzymes of the Indian desert gerbil Meriones hurrianae jerdon and their response to unilateral cryptorchidism

Summary Active male gerbils were rendered unilaterally cryptorchid and the enzymatic changes were studied after 48, 60 and 100 days. The histochemical observations revealed inhibition of alkaline phosphatase, acid phosphatase, 5-nucleotidase, adenosine-tri-phosphatase and succinic dehydrogenase activities in the germinal elements of the seminiferous tubules. The non-specific esterase and succinic dehydrogenase activities increased in the Leydig cells to certain extent. The sudanophilic lipids increased in the Sertoli cells and the interstitial cells. An attempt has been made to approach the intricate problem of the spermatogenesis in order to understand the sequence of certain enzymatic activities in the gerbil testis in which spermatogenesis is suppressed when one of the testes is lodged inside the abdominal cavity.     

Degradation of soil humus by the fairy ring mushroom

Summary Except when cultures were well aerated by shaking,Marasmius oreades (Bolt.) Fr., the fairy ring mushroom, was able to utilize, in pure culture studies, fractions of humus from sources as divergent as the A horizon of a chernozemic soil and the Bh horizon of a Podzol. The importance of this ability to soil infestation was discussed and it was suggested that improved soil aeration be studied as a control measure. Contribution No.316.     

Micropropagation of <Emphasis Type="Italic">Uraria picta</Emphasis> through adventitious bud regeneration and antimicrobial activity of callus

Uraria picta is extensively used in the Asian traditional systems of medicine. Overexploitation of the species for preparation of the drug Dashmula has led to the plant becoming rare and endemic. In the present investigation, an efficient micropropagation protocol has developed from leaf-derived callus of U. picta. Among the various concentrations of cytokinins (6-benzyladenine—BA; kinetin—Kin; and thidiazuron—TDZ) used, a significantly higher number of shoots per culture (58.8 ± 0.8) was observed on Murashige and Skoog (MS) medium fortified with 4.44 μM BA. The shoot regeneration frequency was sustained upon transfer to the same fresh medium at 4-wk intervals over a period of 2 yr. The medium containing various concentrations of auxins (α-napthalene acetic acid (NAA) or indole-3-acetic acid (IAA)) showed callus interspersed root formation; however, MS basal medium containing 3% sucrose revealed direct root induction from in vitro raised shoots. The acclimatized in vitro grown plants showed almost 98% survival upon transfer to soil in earthen pots and grown ex vitro. Randomly amplified polymorphic DNA analysis of 25 arbitrarily selected regenerants and mother plants revealed 100% uniformity and true-to-type nature of the regenerants. Methanolic extracts of callus showed strong antibacterial activity against pathogenic bacteria as compared to leaf and root extracts of in vitro raised plants and wild plants, suggesting the presence of higher concentrations of active chemical constituents (isoflavanoids) in callus cultures of U. picta.