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  • 1
    Electronic Resource
    Electronic Resource
    Sun photometry using photodiode open circuit voltage measurements (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4087-4090 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple technique is explored in which the open circuit voltage of a photodiode is measured using a simple digital multimeter to monitor the solar irradiance and atmospheric optical depths in three spectral bands. The advantage of this technique is that the photometer only consists of an optical interference filter, photodiode, and a measuring digital multimeter, while the electronics circuitry otherwise needed in a conventional photometer is avoided. This makes the system very simple, cost effective, and versatile for even nonprofessionals to handle. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145353
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  • 2
    Electronic Resource
    Electronic Resource
    Corrosion inhibition by aerobic biofilms on SAE 1018 steel (1997)
    Springer
    Applied microbiology and biotechnology 47 (1997), S. 62-68 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Carbon steel (SAE 1018) samples were exposed to complex liquid media containing either the aerobic bacterium Pseudomonas fragi or the facultative anaerobe Escherichia coli DH5α. Compared to sterile controls, mass loss was consistently 2- to 10-fold lower in the presence of these bacteria which produce a protective biofilm. Increasing the temperature from 23 °C to 30 °C resulted in a 2- to 5-fold decrease in corrosion inhibition with P. fragi whereas the same shift in temperature resulted in a 2-fold increase in corrosion inhibition with E. coli DH5α. Corrosion observed with non-biofilm-forming Streptomyces lividans TK24 was similar to that observed in sterile media. A dead biofilm, generated in situ by adding kanamycin to an established biofilm, did not protect the metal (corrosion rates were comparable to those in the sterile control), and mass loss in cell-free, spent Luria-Bertani (LB) medium was similar to that in sterile medium. Confocal laser scanning microscopy analysis confirmed the presence of a biofilm consisting of live and dead cells embedded in a sparse glycocalyx matrix. Mass-loss measurements were consistent with microscopic observations of the metal surface after 2 weeks of exposure, indicating that uniform corrosion occurred. The biofilm was also able to withstand mild agitation (60 rpm), provided that sufficient time was given for its development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050889
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  • 3
    Electronic Resource
    Electronic Resource
    Axenic aerobic biofilms inhibit corrosion of copper and aluminum (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 787-790 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The corrosion behavior of unalloyed copper and aluminum alloy 2024 in modified Baar's medium has been studied with continuous reactors using electrochemical impedance spectroscopy. An axenic aerobic biofilm of either Pseudomonas fragi K or Bacillus brevis 18 was able to lessen corrosion as evidenced by a consistent 20-fold increase in the low-frequency impedance value of copper as well as by a consistent four- to seven-fold increase in the polarization resistance of aluminum 2024 after six days exposure compared to sterile controls. This is the first report of axenic aerobic biofilms inhibiting generalized corrosion of copper and aluminum. Addition of the representative sulfate-reducing bacterium (SRB) Desulfovibrio vulgaris (to simulate consortia corrosion behavior) to either the P. fragi K or B. brevis 18 protective biofilm on copper increased the corrosion to that of the sterile control unless antibiotic (ampicillin) was added to inhibit the growth of SRB in the biofilm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051592
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  • 4
    Electronic Resource
    Electronic Resource
    Axenic aerobic biofilms inhibit corrosion of SAE 1018 steel through oxygen depletion (1997)
    Springer
    Applied microbiology and biotechnology 48 (1997), S. 11-17 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Corrosion inhibition of SAE 1018 steel by pure-culture biofilms of Pseudomonas fragi and Escheri-chia coli DH5α has been evaluated in complex Luria-Bertani medium, seawater-mimicking medium, and modified Baar's medium at 30 °C. In batch cultures, both bacteria inhibited corrosion three to six fold compared to sterile controls, and the corrosion was comparable to that observed in anaerobic sterile media. To corroborate this result, a continuous reactor and electrochemical impedance spectroscopy were used to show that both P. fragi K and E. coli DH5α decreased the corrosion rate by 4- to 40-fold as compared to sterile controls; this matched the decrease in corrosion found with sterile medium in the absence of oxygen and with E. coli DH5α grown anaerobically. In addition, the requirement for live respiring cells was demonstrated by the increase in the corrosion rate that was observed upon killing the P. fragi K biofilm in continuous cultures, and it was shown that fermentation products do not cause an increase in corrosion. Hence, pure-culture biofilms inhibit corrosion of SAE 1018 steel by depleting oxygen at the metal surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051007
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  • 5
    Electronic Resource
    Electronic Resource
    Inhibiting sulfate-reducing bacteria in biofilms on steel with antimicrobial peptides generated in situ (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 267-275 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In batch and continuous fermentations, the reduction in corrosion of SAE 1018 mild steel and 304 stainless steel caused by inhibition of the reference sulfate-reducing bacterium (SRB) Desulfovibrio vulgaris by a protective, antimicrobial-producing Bacillus brevis biofilm was investigated. The presence of D. vulgaris produced a thick black precipitate on mild steel and a higher corrosion rate in batch cultures than that seen in a mono-culture of non-antimicrobial-producing Pseudomonas fragi K upon the addition of SRB to the aerobic P. fragi K biofilm. In continuous reactors, the polarization resistance R p decreased for stainless steel and increased for mild steel upon the addition of SRB to a P. fragi K biofilm. Addition of either 200 μg/ml ampicillin, chloramphenicol, or ammonium molybdate to batch and continuous reactors after SRB had colonized the metal was ineffective in killing SRB, as inferred from the lack of change in both R p and the impedance spectra. However, when ampicillin was added prior to SRB colonization, the growth of SRB was completely inhibited on stainless steel in continuous reactors. Prior addition of ampicillin was only able to delay the growth of SRB on mild steel in continuous reactors. External addition of the purified peptide antimicrobial agent gramicidin S prior to the addition of SRB also inhibited the growth of SRB on stainless steel in continuous reactors, and the SRB were also inhibited on stainless steel in both batch and continuous reactors by producing gramicidin S in situ in a protective biofilm when the gramicidin-S-overproducing strain Bacillus brevis 18 was used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051520
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  • 6
    Electronic Resource
    Electronic Resource
    Cyclic voltammetric studies of certain industrially potential iron chelate catalysts (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 56-60 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Cyclic voltammetry of iron-EDTA and iron-DETPA, in different supporting electrolytes showed electrochemical reversibility in ammonium citrate at pH 8.0, while quasi-reversible nature was noticed with iron-NTA. The absence of electroactive peaks when adding a polyhydric alcohol such as mannitol (providing greater stability to the chelate in alkaline pH) or a tertiary amine such as triethanolamine (as an organic buffer) to the supporting electrolyte enabled the use of CV for quantitative analysis of iron in a complex matrix containing these ingredients. The decrease in the diffusion coefficient of Fe(III)-chelate with an increase in the organic buffer suggested the need for limiting the concentration of the amine in order to obtain efficient mass transport while providing better pH control, when such a solution is required for the oxidation of the sulfide/hydrosulfide ion to elemental sulfur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050110
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  • 7
    Electronic Resource
    Electronic Resource
    Importance of biofilm formation for corrosion inhibition of SAE 1018 steel by axenic aerobic biofilms (1997)
    Springer
    Journal of industrial microbiology and biotechnology 18 (1997), S. 396-401 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: biofilms; corrosion inhibition; confocal scanning laser microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To investigate if corrosion inhibition by aerobic biofilms is a general phenomenon, carbon steel (SAE 1018) coupons were exposed to a complex liquid medium (Luria–Bertani) and seawater-mimicking medium (VNSS) containing fifteen different pure-culture bacterial suspensions representing seven genera. Compared to sterile controls, the mass loss in the presence of these bacteria (which are capable of developing a biofilm to various degrees) decreased by 2- to 15-fold. The extent of corrosion inhibition in LB medium depended on the nature of the biofilm: an increased proportion of live cells, observed with confocal scanning laser microscopy (CSLM) and image analysis, decreased corrosion. Corrosion inhibition in LB medium was greatest with Pseudomonas putida (good biofilm formation), while metal coupons exposed to Streptomyces lividans in LB medium (poor biofilm formation) corroded in a manner similar to the sterile controls. Pseudomonas mendocina KR1 reduced corrosion the most in VNSS. It appears that only a small layer of active, respiring cells is required to inhibit corrosion, and the corrosion inhibition observed is due to the attached biofilm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900396
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  • 8
    Electronic Resource
    Electronic Resource
    Inhibiting sulfate-reducing bacteria in biofilms by expressing the antimicrobial peptides indolicidin and bactenecin (1999)
    Springer
    Journal of industrial microbiology and biotechnology 22 (1999), S. 167-175 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: engineered biofilms; biocorrosion; sulfate-reducing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To identify novel, less-toxic compounds capable of inhibiting sulfate-reducing bacteria (SRB), Desulfovibrio vulgaris and Desulfovibrio gigas in suspension cultures were exposed to several antimicrobial peptides. The bacterial peptide antimicrobials gramicidin S, gramicidin D, and polymyxin B as well as the cationic peptides indolicidin and bactenecin from bovine neutrophils decreased the viability of both SRB by 90% after a 1-h exposure at concentrations of 25–100 μg ml−1. To reduce corrosion by inhibiting SRB in biofilms, the genes for indolicidin and bactenecin were expressed in Bacillus subtilisBE1500 and B. subtilis WB600 under the control of the constitutive alkaline protease (apr) promoter, and the antimicrobials were secreted into the culture medium using the apr signal sequence. Bactenecin was also synthesized and expressed as a fusion to the pro-region of barnase from Bacillus amyloliquefaciens. Concentrated culture supernatants of B. subtilis BE1500 expressing bactenecin at 3 μg ml−1 decreased the viability of Escherichia coli BK6 by 90% and the reference SRB D. vulgaris by 83% in suspension cultures. B. subtilis BE1500 and B. subtilis WB600 expressing bactenecin in biofilms also inhibited the SRB-induced corrosion of 304 stainless steel six to 12-fold in continuous reactors as evidenced by the lack of change in the impedance spectra (resistance polarization) upon addition of SRB and by the reduction in hydrogen sulfide and iron sulfide in batch fermentations with mild steel. A 36-fold decrease in the population of D. vulgaris in a B. subtilis BE1500 biofilm expressing bactenecin was also observed. This is the first report of an antimicrobial produced in a biofilm for in vivo applications and represents the first application of a beneficial, genetically-engineered biofilm for combating corrosion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900627
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  • 9
    Electronic Resource
    Electronic Resource
    High-pressure Raman study of SrMoO4 up to 37 GPa and pressure-induced phase transitions (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 451-455 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pressure-induced phase changes in SrMoO4 were investigated by high-pressure Raman spectroscopy in a diamond anvil cell. The scheelite-type SrMoO4 transforms in to a monoclinic lattice near 13 GPa and retains this structure up to 37 GPa, the limit of pressure tested. There is no pressure-induced amorphization in this simple molybdate up to this pressure, as in the case of structurally complex molybdate systems. The optical absorption characteristics of SrMoO4 change considerably with pressure, the sample turning progressively deep orange-brown with increase in pressure. This change is connected with the lowering of the d-state of molybdenum in the MoO4 ion with increase in pressure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250260609
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