ISSN:0268-2575    

DOI:10.1002/jctb.280490402

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

Abstract4‐Nitroso‐1‐phenyl‐3‐methyl‐5‐aminopyrazole (1) was condensed with ethylcyanoacetate (2), malononitrile (4a) and 2‐cyanomethylbenzimidazole (4b) to yield 6‐hydroxy‐5‐cyano, 6‐amino‐5‐cyano and 6‐amino‐5‐(benzimidazol‐2‐yl)‐3‐methylpyrazolo [3,4‐b]pyrazines3, 5aand5b, respectively. 5‐Cyano‐6‐chloro derivative6obtained from3was converted to 3‐aminopyrazolo[4′,3′:5,6]pyrazino[2,3‐c]pyrazoles8aand8bby the treatment with hydrazin hydrate (7a) and phenylhydrazine (7b), respectively. Compound5awas treated with formamide (9a), urea (9b) and thiourea (9c) to give 4‐aminopyrazolo[4′,3′:5,6]pyrazino[2′3′‐d]pyrimidines10a–10c.With refluxing acetic anhydride compounds8a, 8band10agave corresponding acetamido derivatives8c, 8dand10d.Compound5awas treated with ethylorthoformate (11), acetic anhydride (12) or benzoylchloride (13) to give fused benzimidazopyrazolo[4′,3′:5,6]pyrazino[2′,3′‐d]pyrimidines, viz., benzimidazol[1,2‐c]pyrazolo[4,3‐g]pteridines (14a–14c). Some of the compounds8, 10and

ISSN:0268-2575    

DOI:10.1002/jctb.280490403

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractGreasy wool has a very considerable propensity towards self‐heating, and two quantities relevant to such self‐heating—activation energy of oxidation and thermal diffusivity—have been measured for four samples of ‘as‐received’ greasy wool. For comparison, the same quantities for two cellulosic fibre materials—raw cotton and kapok—a

ISSN:0268-2575    

DOI:10.1002/jctb.280490404

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0268-2575    

DOI:10.1002/jctb.280490405

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractFour kinds of bioreactor were evaluated for thorium removal by fungal biomass. Static‐bed or stirred‐bed bioreactors did not give satisfactory thorium removal probably because of poor mixing. An air‐lift bioreactor removed approximately 90–95% of the thorium supplied over extended time periods and exhibited a well‐defined breakthrough point after biosorbent saturation. The air‐lift bioreactor promoted efficient circulation and effective contact between the thorium solution and the mycelial pellets. Of several fungal species tested, Rhizopus arrhizusandAspergillus niger were the most effective biosorbents with loading capacities of 0.5 and 0.6 mmol g−1respectively (116 and 138 mg g−1) at an inflow thorium concentration of 3 mmol dm−3. The efficiency of thorium biosorption by A. niger was markedly reduced in the presence of other inorganic solutes while thorium biosorption by R. arrhizus was relatively unaffected. Air‐lift bioreactors containing R. arrhizus biomass could effectively remove thorium from acidic solution (1 mol dm−3HNO3) over a wide range of initial thorium concentrations (0.1–3 mmol dm−3). The biotechnological application and significance of these results are discussed in the wider context of fungal bio

ISSN:0268-2575    

DOI:10.1002/jctb.280490406

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractMany microfungi contain chitin/chitosan as an integral part of the cell wall structure. The binding of toxic and heavy metal ions by chitosan or partly deacetylated chitin is a direct consequence of the base strength of the primary amine group and is most effective for those metals that form complexes with ammonia. Of the microfungi studied, hyphae from Mucor mucedoandRhizomucor miehei, after treatment with hydroxide to expose the chitin/chitosan, were found to be most effective in the capture of metal ions. Chemically treated mycelia have so far been shown to bind silver, zinc, lead, copper, nickel, cobalt, cadmium, iron and chromium, with the efficiency of metal‐ion binding apparently being inversely proportional to the valency state of the metal ions to be bound.Wet‐laid papers produced from mixed slurries of treated mycelia and various conventional paper‐making and textile fibres have exceptionally good tensile‐ and bursting‐strength properties, particularly in the wet state. Papers containing 1 g treated mycelia removed up to 90% of various metal ions in solution (50 cm3, 7–5 mmol dm−3) with flow rates of 0.5 cm3cm−2min−1. However, the total metal‐ion binding capacities of single‐thickness microfungal papers are limited under constant flow conditions. The total volume flowing through the system before metal‐ion breakthrough occurs increases in direct proportion to the number of sheets of microfungal paper but the concomitant reduction in flow rates becomes a limiting factor. Mycelia‐containing structures that allow efficient metal‐ion binding at commercially acceptable flow rates are c

ISSN:0268-2575    

DOI:10.1002/jctb.280490407

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractMicroorganisms can be used to remove toxic heavy metals from liquid industrial wastes. In addition to the chemical toxicity of many of the latter, the production of long‐lived nuclides from nuclear power programmes has introduced additional radiotoxicological hazards. Associated problems of the presence of contaminating, non‐metal co‐pollutants and the presentation of dilute, high‐volume wastes have received little attention.Traditional biotechnological waste treatments have relied either on the use of non‐living biomass (‘biosorption’) or on the accumulation of metals by living cells with the associated problems of metal toxicity effects and the requirements for cell viability or growth. Identification of an enzymically‐mediated metal accumulation step can permit decoupling of cell growth from metal accumulation. Using pre‐grown biomass immobilized in a flow‐through filter (‘bioreactor’) the metal‐accumulative bioprocess can be described accurately applying traditional Michaelis—Menten kinetics. The effect of copollutants can be then quantified in order to run the bioreacto

ISSN:0268-2575    

DOI:10.1002/jctb.280490408

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper gives an overview of the feasibility of the application of biotechnology to nuclear waste treatment. The contents are based on a report which PA Technology carried out for the Department of the Environment (DoE Reference: DoE/RW/88.008 Sector No 2.3).Many living and dead organisms accumulate heavy metals and radionuclides. The controlled use of this phenomenon forms the basis for the application of biotechnology to the removal of radionuclides from nuclear waste streams. Indeed, biotechnology offers a series of new opportunities for removal of radionuclides from dilute aqueous process effluents. Such technology is already used for heavy metal removal on a commercial basis and could be optimised for radionuclide removal.An overview of biotechnology areas, namely the use of biopolymers and biosorption using biomass applicable to the removal of radionuclides from industrial nuclear effluents is given. The potential of biomagnetic separation technology, genetic engineering and monoclonal antibody technology is also to be examined. The most appropriate technologies to develop for radionuclide removal in the short term appear to be those based on biosorption of radionuclides by biomass and the use of modified and unmodified biopolymers in the medium term.

ISSN:0268-2575    

DOI:10.1002/jctb.280490409

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractChitosan is a natural polycationic polymer which possesses valuable properties as a metal recovering and water purifying agent. Applications are—waste water treatment for heavy metal and radio isotope removal and valuable metal recovery,—potable water purification for reduction of unwanted metals,—agriculture—controlled release of trace metals essential to plant growth,—food—complex binding of iron in precooked food to reduce ‘warmed‐over flavour’.The interactions of metals with chitosan are complex, probably simultaneously dominated by adsorption, ion‐exchange and chelation. To study this it is of utmost importance to work with well characterized chitosans. This has been a problem as available characterizing methodology is limited.Degree of polymerization and deacetylation and the distribution of acetyl groups along the polymer chain is of crucial importance for chitosan metal interacting characteristics. Making chemical derivatives is a way to alter the metal interacting characteristics of chitosan.Chitosan possesses general coagulant/flocculant characteristics towards bio‐m

ISSN:0268-2575    

DOI:10.1002/jctb.280490410

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0268-2575    

DOI:10.1002/jctb.280490411

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY