Cold water (cp = 4180 J/kg K) leading to a shower enters a thin-walled double-pi
ID: 1009698 • Letter: C
Question
Cold water (cp = 4180 J/kg K) leading to a shower enters a thin-walled double-pipe counter-flow heat exchanger at 15degree C at a rate of 1.25 kg/s and is heated to 45 degree C by hot water (cp = 4190 J/kg K) that enters at 100 degree C at a rate of 3 kg/s. If the overall heat transfer coefficient is 880 W/m2 K, use the LMTD method to find; The rate of heat transfer in the heat exchanger The outlet temperature of the hot water The log mean temperature difference The surface area of the heat exchanger -5 65 kj 40.7 kJ 35.1 kJ ¦ -46 3 k.lExplanation / Answer
The influence of zinc, iron, cobalt, and manganese on submerged cultures of Fusarium moniliforme NRRL 13616 was assessed by measuring dry weight accumulation, fusarin C biosynthesis, and ammonia assimilation. Shake flask cultures were grown in a nitrogen-limited defined medium supplemented with various combinations of metal ions according to partial-factorial experimental designs. Zinc (26 to 3,200 ppb (26 to 3,200 ng/ml)) inhibited fusarin C biosynthesis, increased dry weight accumulation, and increased ammonia assimilation. Carbohydrate was found to be the principal component of the increased dry weight in zinc-supplemented cultures. Zinc-deficient cultures synthesized more lipid and lipidlike compounds, such as fusarin C, than did zinc-supplemented cultures. Microscopic examination showed that zinc-deficient hyphae contained numerous lipid globules which were not present in zinc-supplemented cultures. Addition of zinc (3,200 ppb) to 2- and 4-day-old cultures inhibited further fusarin C biosynthesis but did not stimulate additional dry weight accumulation. Iron (10.0 ppm) and cobalt (9.0 ppm) did not affect fusarin C biosynthesis or dry weight accumulation. Manganese (5.1 ppm) did not affect dry weight accumulation but did increase fusarin C biosynthesis in the absence of zinc. Maximum fusarin C levels, 32.3 {mu}g/mg (dry weight), were produced when cultures were supplied manganese, whereas minimum fusarin C levels, 0.07 {mu}g/mg (dry weight), were produced when zinc, iron, cobalt, and manganese were supplied.
Role of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium in carcinogenesis.
PubMed Central
Kazantzis, G
1981-01-01
The possible carcinogenicity of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium is reviewed, taking into account epidemiological data, the results of animal experimental studies, data on mutagenic effects and on other in vitro test systems. Of the great variety of occupations where exposure to one of these metals may occur, only haematite mining has been clearly shown to involve an increased human cancer risk. While the possibility that haematite might in some way act as a carcinogen has to be taken into consideration it is more likely that other carcinogens are responsible. Certain platinum coordination complexes are used in cancer chemotherapy, are mutagenic, and likely to be carcinogenic. Cobalt, its oxide and sulfide, certain lead salts, one organomanganese, and one organotitanium compound have been shown to have a limited carcinogenic effect in experimental animal studies, and except for titanium appear to be mutagenic. Certain mercury compounds are mutagenic but none have been shown to be carcinogenic. The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenium may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man. Epidemiological