Equilibrium and kinetics of biosorption of cadmium(II) and copper(II) ions by wheat straw.

Biosorption equilibrium and kinetics of Cd(2+) and Cu(2+) ions on wheat straw, Triticum aestivum, in an aqueous system were investigated. Among the models tested, namely the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, the biosorption equilibrium for both Cd(2+) and Cu(2+) was best described by the Langmuir model. The Langmuir biosorption capacity for Cd(2+) was about 27% higher than that for Cu(2+). It was also found that biosorption of Cd(2+) and Cu(2+) by wheat straw followed second-order kinetics. The equilibrium amount of metal ions adsorbed onto the wheat straw increased with increasing of pH from 4.0 to 7.0, and the effect was more pronounced for Cd(2+) than for Cu(2+). The equilibrium adsorbed amount also increased with the initial concentration of the metal ions, as expected. On the other hand, an increase of temperature from 25 to 30 degrees C only enhanced the biosorption of Cd(2+) and Cu(2+) slightly. The apparent temperature independence and the strong pH dependence of the amount of metal ions adsorbed along with moderate mean free energies of biosorption (between 8.0 and 12.9 kJ mol(-1)) altogether indicate that biosorption of Cd(2+) and Cu(2+) by wheat straw might follow a chemisorption mechanism.

Chromosomal mapping of 18S-28S rRNA genes and 10 cDNA clones of human chromosome 1 in the musk shrew (Suncus murinus).

The direct R-banding fluorescence in situ hybridization (FISH) method was used to map 18S-28S ribosomal RNA genes and 10 human cDNA clones on the chromosomes of the musk shrew (Suncus murinus). The chromosomal locations of 18S-28S ribosomal RNA genes were examined in the five laboratory lines and wild animals captured in the Philippines and Vietnam, and the genes were found on chromosomes 5, 6, 9, and 13 with geographic variation. The comparative mapping of 10 cDNA clones of human chromosome 1 demonstrated that human chromosome 1 consisted of at least three segments homologous to Suncus chromosomes (chromosomes 7, 10, and 14). This approach with the direct R-banding FISH method is useful for constructing comparative maps between human and insectivore species and for explicating the process of chromosomal rearrangements during the evolution of mammals.

A Robertsonian translocation, rob(2;28), found in Vietnamese cattle.

A new Robertsonian translocation, rob(2;28), was discovered in a local population of the Vietnamese Cattle. The animal (2n = 59, XY) was found by Q- and R-banding to be a heterozygous carrier of a centric fusion translocation involving chromosomes 2 and 28. FISH analysis using a bovine satellite I DNA probe demonstrated that the centromeric heterochromatin block of the rob(2;28) chromosome become much smaller than its ancestors suggesting a monocentric nature of this centric fusion. This is the first report identifying a Robertsonian translocation in Southeast Asian cattle by karyotyping of banded chromosomes.

[Does room air humidification prevent respiratory diseases in winter? An epidemiologic study on 1321 office workers]. / L'humidification de l'air des locaux prévientelle les maladies respiratories pendant l'hiver? Une étude épidémiologique parmi 1321 employés de bureau.

An epidemiological study was carried out from January 15th to March 31st 1976 among 1321 clerical workers of the Administration of the Canton of Geneva. This study was intended to determine whether indoor humidification during winter prevents respiratory infections. The results obtained show that air-conditioning, in spite of an average relative humidity (RH) of 52%, has an unfavourable influence on respiratory infections which are significantly more numerous among people working in air-conditioned offices. Humidifiers did not have a significant influence on the incidence of respiratory diseases, but the trifling difference of average air humidity between offices equipped with humidifiers (RH:33%) and offices without humidifier (RH:30%) shows that these appliances, as at present commonly used, are inefficient. After a review of the literature on the subject, the authors reach the conclusion that no convincing evidence supports the theory of the effectiveness of indoor humidification in the prevention of respiratory diseases.