Influence of manufacturing variables on the characteristics and effectiveness of chitosan products. II. Coagulation of activated sludge suspensions

Chitosan samples manufactured under different conditions were compared for effectiveness of coagulating an activated sludge suspension grown on vegetable canning wastes. Computer analysis of data from Buchner funnel filterability tests resulted in quadratic polynomial equations describing the response curves for volume of filtrate versus dosage, expressed as g/liter chitosan/100 g sludge suspended solids (SSS). The quotient of the filtrate volume and dosage at the inflection points of the equations obtained for 10 test samples and 1 commercial chitosan sample were compared to evaluate the response (effectiveness) per unit amount for each chitosan product. The product made by a standard procedure (deproteinated with 3% NaOH at 100°C for 1 hr, demineralized with 1N HCL at ambient temperature for 30 min, and deacetylated with 50% NaOH at 145–150°C under N₂ for 5 or 15 min) gave the best performance as a coagulating agent for this activated sludge system. Other products, including the commercial preparation, required higher dosages to achieve the same effectiveness. Products deacetylated in the presence of sir rather than nitrogen decreased waste treatment effectiveness, which approximated the trends of reduced viscosity and molecular-weight distribution. The products containing minerals were less effective than products from which minerals had been removed prior to deacetylation, but they were more effective than the enzyme treated sample and the commercial product. In general, although chitosan products obtained after 15 min deacetylation were more effective than those receiving 5 min deacetylation, effectiveness did not correlate linearly with viscosity and molecular-weight distribution trends. However, chitosan products deacetylated for 15 min did show that the higher-molecular-weight products (0.65–1.1 × 10⁶) were more effective coagulating agents for activated sludge than the manufactured product having the lowest molecular weight (0.47 × 10⁶) and the commercial reference sample (0.56 × 10⁶). Thus, higher values for molecular weight were predictive of greater effectiveness for coagulation of activated sludge suspensions.     

A hydrogen-deuterium exchange study of the amide protons of polymyxin B by nuclear-magnetic-resonance spectroscopy.

1. Proton magnetic resonance spectra at 270 MHz of polymyxin B, a cationic oligopeptide antibiotic, show the influence of the inorganic counteranion present in solution. 2. Hydrogen-deuterium exchange rates for the amide protons are of two types, depending on whether the anion is monovalent or polyvalent. Polyvalent anions catalyse the acid-catalysed reaction more than the monovalent anions. 3. The structure in solution was monitored using the proton signals of the amides, the phenylalanine aromatic protons, and the leucine methyl and gamma-CH protons in several polymyxin salts. The temperature coefficients of the chemical shifts of the N-H protons are used to identify two beta turns in the cyclic ring of polymyxin B. The variation in chemical shift of the N-H protons, the aromatic protons and the leucine protons are correlated with anionic size and electronegativity.     

Epilithic periphyton and detritus studies in a subalpine stream

The accumulation of epilithic periphyton in Ward Creek, a permanent stream within the Lake Tahoe basin, California, was measured weekly at three stations from July through September, 1972. Subsamples were analyzed for total carbon and adenosine triposphate content. The mean total carbon content at three stations over the period of investigation was 0.508 ± 0.263 mg carbon cm^–2. Live biomass, as estimated from ATP measurements, averaged 0.121 ± 0.115 mg carbon cm 2. It was estimated that approximately 76% of the organic carbon accumulating on rock substrates was present as detritus. Scanning electron microscopy of rock substrates suggested that much of this detrital accumulation may consist of diatom stalk materials.This work was supported by a grant from the National Science Foundation/RANN GI-22. C. R. Goldman, Principal Investigator.     

Growth of astrocytoma cells in the presence of prostaglandin E1: effect on the regulation of cyclic AMP metabolism.

Human astrocytoma cells (1321N1) in culture respond to pharmacological concentrations of prostaglandins and catecholamines with a marked increase in the accumulation of cyclic AMP. However, growth of 1321N1 cells in the presence of low concentrations (0.003 to 0.1 muM) of prostaglandin E1 (PGE1) results in a marked reduction in the responsiveness of the cells-even to concentrations of PGE1 that normally stimulate maximal accumulation of cyclic AMP. Occasionally, a partial reduction in the responsiveness to catecholamines was observed in cells grown in the presence of PGE1. When it occurred this effect could be correlated with an increase in the cyclic AMP-degradation capacity of the cells. This loss of responsiveness to catecholamines could be completely reversed by 1-methyl-3-isobutylxanthine, a potent inhibitor of phosphodiesterase activity in 1321N1 cells. The consistently observed and more profound desensitization to the effects of PGE1 could not be correlated with an increase in cyclic AM-degradative capacity. Accordingly, 1-methyl-3-isobutylxanthine was only minimally effective in reversing desensitization to PGE1. It is concluded that the inability of 1321N1 cells grown in the presence of PGE1 to accumulate cyclic AMP upon subsequent challenge with PGE1 is primarily due to a selective desensitization of the PGE1-activated adenylate cyclase.     

Effect of 3,4-toluenediamine on output from in situ rat Brunner's glands pouches.

Duodenal and gastric glandular mucosal damage have been observed 24 hr following single subcutaneous doses of 3,4-TDA in fed, unrestrained rats. 3,4-TDA significantly reduced secretion from in situ Brunner's glands pouches in pentobarbital anesthetized rats. The reduction in volume output with a definitely duodenal ulcerogenic dose of this compound was more than twice that observed with a minimally ulcerogenic dose, suggesting a correlation between the duodenal ulcerogenic and duodenal anti-secretory activities of this compound. The animal model described in this communication should facilitate experimentation to establish the inhibitory effect of compounds on the output of protective fluids from the proximal duodenum.     

Localization of a parasite encoded protein to erythrocyte cytoplasmic vesicles of Plasmodium falciparum-infected cells

Intracellular development of the malarial parasite results in substantial modifications of the membrane and cytoskeleton of the erythrocyte host cell. Two related Plasmodium falciparum-encoded proteins of 50 kDa and 43 kDa (Pf 50/43), identified by reactivity with a single mAb, were demonstrated to be localized to the erythrocyte cytoplasm of parasite-infected cells. Immunofluorescence and immunoelectron microscopy using mAb.7E11 demonstrated the Pf 50/43 is localized in the membrane of the vesicles in the erythrocyte cytoplasm, vesicles which correspond to Maurer's clefts. Solubility properties of the proteins suggest they are integral membrane proteins. By immunofluorescence, Pf 50/43 is shown to colocalize with actin which has a highly modified organization in the infected erythrocyte. Pf 50/43 is located exclusively in the vesicles, is not transported to the erythrocyte membrane or secreted. It is proposed the vesicles may play a role in transport of molecules across the erythrocyte cytoplasm, between the parasite and the external erythrocyte plasma membrane.     

A new precursor for organo-osmium complexes

The use of potassium osmate, K₂[OsO₂(OH)₄], as a precursor for some cyclopentadienyl-osmium complexes is described. The X-ray structures of OsBr(PPh₃)₂Cp, OsCl(dppe)Cp and OsX(dppe)Cp^∗ (X = Cl, Br) are reported.     

Correction to: Microhabitats of sharknose goby (Elacatinus evelynae) cleaning stations and their links with cleaning behaviour

Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02111-z