Improving products of anaerobic sludge digestion by microaeration.

Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. Recently, microaeration has been proved to be a relatively simple and highly efficient biological method of sulfide removal in the anaerobic digestion of biosolids, but little attention has been paid to comparing the quality of digested sludge and sludge liquor in the anaerobic and microaerobic digestion and that is why this paper primarily deals with this area of research. The results of the long-term monitoring of digested sludge quality and sludge liquor quality in the anaerobic and microaerobic digesters suggest that products of both technologies are comparable. However, there are several parameters in which the 'microaerobic' products have a significantly better quality such as: sulfide (68% lower) and soluble chemical oxygen demand (COD) (33% lower) concentrations in the sludge liquor and the lower foaming potential of the digested sludge.

IR laser photodeposition of a-Fe/Si films developing nanograins of ferrisilicate, iron disilicide and rare hexagonal iron upon annealing.

IR laser-induced gas-phase photolysis of Fe(CO)(5)-SiH(4) mixtures occurs as SiH(4)-photosensitized decomposition of Fe(CO)(5) is accelerated by products of this decomposition and it results in deposition of amorphous Si/Fe nanocomposite films. Analyses of the deposited and subsequently annealed solid films were made by FTIR, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and electron microscopy. The deposited films are amorphous, contain crystalline nanostructures of iron silicide FeSi(2) and undergo atmospheric oxidation in topmost layers to iron oxide and hydrogenated silicon oxide. Upon annealing they develop nanocrystalline structures of ferrisilicate, Fe(1.6)SiO(4), carbon-encaged iron disilicide, FeSi(2), and very rare hexagonal (high-pressure) Fe surviving at ambient conditions. The mechanism of formation of these nanostructures is discussed in terms of gas-phase and solid-phase reactions.

Comparison of microbial activity in anaerobic and microaerobic digesters.

Microaerobic alternative of anaerobic digestion offers many advantages especially when sulfide concentration in the digester is high. For better understanding of the microaerobic technology more detailed characterization of biomass activity is needed. Two equal digesters were operated under the same condition except of microaeration in one of them. During long term operation of anaerobic and microaerobic digesters the sludge quality and the biomass activity was monitored. The activity of sulfide oxidizing bacteria of microaerobic biomass was significantly higher in comparison with anaerobic biomass. The activity of sulfate reducing bacteria was comparable. The activity of methanogenic bacteria activity depended on sulfide concentration more than on microaeration. The extent of foaming problems was lower in the microaerobic than in the anaerobic digester.

[Thymosin fraction 5. Preclinical study]. / Thymosin frakce 5. Preklinická studie.

Thymosin fraction 5 from the Research Institute for Pharmacy and Biochemistry possessed the immunomodulatory activity in performed tests. The activity is manifested mostly by the induction of the maturation and the differentiation of T cell precursors, which are released from thymus to secondary lymphoid organs. Thymosin fraction 5 causes the expression of the surface membrane markers Thy-1.2, Lyt-2 and L3T4 on the immature T lymphocytes as well. The induced cells are immunocompetent and able to exert the complete functional activity. In the intact mice thymosin fraction 5 had not pronounced effect on the functional potency of mature immunocompetent cells, but in MTA influenced mice its stimulatory effect on the proliferative response to mitogens and on the antibody production against the T-dependent antigen was demonstrated. Thymosin fraction 5 influenced positively not only the components of the specific immunity, but also the functional activity of peritoneal macrophages. The toxicity of thymosin fraction 5 was in the battery of tests in vitro and in vivo very low and therefore it can be considered to be harmless for the clinical practice.

Effect of ascorbic acid prophylaxis on the frequency of chromosome aberrations, urine mutagenicity and nucleolus test in workers occupationally exposed to cytostatic drugs.

The genetic risk of workers occupationally exposed to a series of newly developed cytostatic drugs and the presumed antimutagenic potential of ascorbic acid (AA) were studied in a group of 38 chemical laboratory personnel examined for chromosome aberrations in lymphocytes, urine mutagenicity and nucleolar RNA activity before and after a 6-month prophylactic administration of AA at daily doses of 1 g for 5 days a week. Chromosome aberration tests revealed elevated aberrant cell (AB.C) rates both prior to and after AA supplementation (3.9% and 3.65% of AB.C., respectively). These values were significantly higher than those found in 18 non-exposed matching controls (1.05% of AB.C.). Tests for mutagenic activity in the urine of drug-exposed workers revealed 64% positive urine samples prior to vitaminization and 60% positive urine specimens after it; positive urine samples in the group of controls accounted for 21% of samples. In the nucleolus test, numbers of inactivated micronuclei in the exposed were initially higher than those of controls (33.4% versus 24.3%), but dropped to 20.5% after AA supplementation. These findings show that AA prophylaxis alone cannot substantially reduce the hazards associated with exposure to anti-cancer drugs.

The effects of transfer factor in adjuvant diseases in rats.

The improvement of the course of adjuvant arthritis by thymosin led us to use the transfer factor (biological active fraction of the homogenate of human tonsillar leukocytes) in this reported experiment. Transfer factor administered in the amount 200 micrograms (analogy of 10' leukocytes) 3 times a week was able to completely prevent the development of adjuvant arthritis. In the period of maximum development of adjuvant arthritis, symptoms were observed in control rats not treated with transfer factor (on day 21 after complete Freund adjuvants application) while in the transfer factor treated rats, swelling of the paws was not demonstrated and the mobility was the same as in that of the healthy ones. Signs of bone lesions were not present in these animals as well. Transfer factor has only a weak effect on interferon production in vivo.

A further study on the number of silver stained granules of active nucleolus organizer regions in mitotic Yoshida and Zajdela rat experimental tumor cells.

Yoshida ascitic sarcoma and Zajdela ascitic hepatoma were investigated in Norway rats to provide more information on active nucleolus organizer regions (NORs) represented by silver stained granules (SSGs). Diploid Yoshida sarcoma cells were characterized by the presence of 6 (3 doublets) of SSGs in the metaphase and 3 + 3 SSGs in future daughter nuclei in the anaphase or telophase. In contrast Zajdela hepatoma cells (frequently hypoploid) possessed 6 SSGs less frequently in the metaphase and the number of anaphasic or telophasic cells with 3 SSGs in future daughter nuclei was also reduced. The number of SSGs in future nuclei of anaphasic or telophasic Yoshida sarcoma cells was usually the same, i.e. such anaphases or telophases were symetric. In Zajdela hepatoma cells the number of symetric anaphases and telophases was substantially reduced in favor of asymetric anaphases or telophases which contained different number of SSGs in future nuclei.