Effects of pH on ex-situ biomethanation with hydrogenotrophic methanogens under thermophilic and extreme-thermophilic conditions

2020 ◽  
Author(s):  
Lurui Chen ◽  
Shiyun Du ◽  
Li Xie
Keyword(s):  
Ex Situ ◽  
Thermophilic Conditions ◽  
Effects Of Ph ◽  
Hydrogenotrophic Methanogens

Surface-Enhanced Raman Detection of Aqueous Cyanide

1994 ◽  
Vol 48 (8) ◽  
pp. 1007-1010 ◽  
Author(s):  
Robert D. Shelton ◽  
John W. Haas ◽  
Eric A. Wachter
Keyword(s):  
Limit Of Detection ◽  
Direct Detection ◽  
Ex Situ ◽  
Cyanide Ion ◽  
Oxidation Reduction ◽  
Reduction Cycle ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Effects Of Ph ◽  
Background Ions

Cyanide ion (CN−) has been the subject of numerous studies probing the mechanisms underlying the surface-enhanced Raman scattering (SERS) phenomenon. This work examines various aspects critical to application of SERS for direct detection of trace cyanide in groundwater and in wastewater streams. A new method for direct quantitation of cyanide in aqueous electrolyte has been developed that uses an ex situ oxidation-reduction cycle to precondition a planar silver electrode. Cyanide ion can be detected in 0.1 M KCl with a linear response between 100 ppm and 10 ppb. The estimated limit of detection is approximately 8 ppb. The effects of pH, electrolyte level, and two common background ions, nitrate (NO3−) and sulfate (SO42–), have been characterized. Cyanide response was found to be sensitive to pH, with optimal performance observed at neutral to basic pH. Electrolyte concentrations of 0.001 M reduced response to cyanide by a factor of five, while levels above 0.1 M had no significant effect. The addition of 10-ppm sulfate ion decreased response approximately 40%, while the presence of nitrate ion at concentrations up to 100 ppm had a negligible effect on SERS response. These results suggest that cyanide ion can be detected directly in high-ionic-strength aqueous solutions, such as groundwater.

Performance and microbial communities of a batch anaerobic reactor treating liquid and high-solid sludge at thermophilic conditions

RSC Advances ◽  
2016 ◽  
Vol 6 (101) ◽  
pp. 99524-99531 ◽  
Author(s):  
Dongling Zhang ◽  
Haiping Yuan ◽  
Bao Yu ◽  
Xiaohu Dai ◽  
Xiaoting Huang ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Utilization Efficiency ◽  
Anaerobic Reactor ◽  
High Solid ◽  
Thermophilic Conditions ◽  
Hydrogenotrophic Methanogens

HS-AD with TS of 20% achieved similar reactor utilization efficiency as that in L-AD, and enriched hydrogenotrophic methanogensMethanoculleus.

scholarly journals Microbial Resource Management for Ex Situ Biomethanation of Hydrogen at Alkaline pH

2020 ◽  
Vol 8 (4) ◽  
pp. 614 ◽  
Author(s):  
Washington Logroño ◽  
Denny Popp ◽  
Sabine Kleinsteuber ◽  
Heike Sträuber ◽  
Hauke Harms ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Methanogenic Archaea ◽  
Amplicon Sequencing ◽  
Reducing Agent ◽  
Ex Situ ◽  
Media Composition ◽  
The Media ◽  
Promising Solution ◽  
Microbial Resource Management ◽  
Hydrogenotrophic Methanogens

Biomethanation is a promising solution to convert H2 (produced from surplus electricity) and CO2 to CH4 by using hydrogenotrophic methanogens. In ex situ biomethanation with mixed cultures, homoacetogens and methanogens compete for H2/CO2. We enriched a hydrogenotrophic microbiota on CO2 and H2 as sole carbon and energy sources, respectively, to investigate these competing reactions. The microbial community structure and dynamics of bacteria and methanogenic archaea were evaluated through 16S rRNA and mcrA gene amplicon sequencing, respectively. Hydrogenotrophic methanogens and homoacetogens were enriched, as acetate was concomitantly produced alongside CH4. By controlling the media composition, especially changing the reducing agent, the formation of acetate was lowered and grid quality CH4 (≥97%) was obtained. Formate was identified as an intermediate that was produced and consumed during the bioprocess. Stirring intensities ≥ 1000 rpm were detrimental, probably due to shear force stress. The predominating methanogens belonged to the genera Methanobacterium and Methanoculleus. The bacterial community was dominated by Lutispora. The methanogenic community was stable, whereas the bacterial community was more dynamic. Our results suggest that hydrogenotrophic communities can be steered towards the selective production of CH4 from H2/CO2 by adapting the media composition, the reducing agent and the stirring intensity.

scholarly journals Microbial resource management for ex situ biomethanation of hydrogen at alkaline pH

2020 ◽  
Author(s):  
Washington Logroño ◽  
Denny Popp ◽  
Sabine Kleinsteuber ◽  
Heike Sträuber ◽  
Hauke Harms ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Methanogenic Archaea ◽  
Amplicon Sequencing ◽  
Reducing Agent ◽  
Ex Situ ◽  
Media Composition ◽  
The Media ◽  
Promising Solution ◽  
Microbial Resource Management ◽  
Hydrogenotrophic Methanogens

AbstractBiomethanation is a promising solution to convert H2 produced from surplus electricity and CO2 to CH4 by using hydrogenotrophic methanogens. In ex situ biomethanation with mixed cultures, homoacetogens and methanogens compete for H2/CO2. We enriched a hydrogenotrophic microbiota on CO2 and H2 as sole carbon and energy sources, respectively, to investigate these competing reactions. Microbial community structure and dynamics of bacteria and methanogenic archaea were evaluated through 16S rRNA and mcrA gene amplicon sequencing, respectively. Hydrogenotrophic methanogens and homoacetogens were enriched as acetate was concomitantly produced along with CH4. By controlling the media composition, especially changing the reducing agent, the formation of acetate was lowered and grid quality CH4 (≥ 97%) was obtained. Formate was identified as an intermediate that was produced and consumed during the bioprocess. Stirring intensities ≥1000 rpm were detrimental, probably due to shear force stress. The predominating methanogens belonged to the genera Methanobacterium and Methanoculleus. The bacterial community was dominated by Lutispora. The methanogenic community was stable, whereas the bacterial community was more dynamic. Our results suggest that hydrogenotrophic communities can be steered towards selective production of CH4 from H2/CO2 by adapting the media composition, the reducing agent and the stirring intensity.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Interfacial properties of GaSb/InAs superlattices

1993 ◽  
Vol 51 ◽  
pp. 826-827
Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Molecular Beam ◽  
Infrared Detector ◽  
Interfacial Properties ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Short Period ◽  
High Optical Absorption

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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