scholarly journals On the Oxidation-Reduction Potential of Tissue Fluid of the Rice Plant : II. Redox Potential as Influenced by Light Intensity and water Temperature III. Changes in the Redox-Potential of the Leaf by the Growing Stages of the Plant IV. Varietal Differences in Redox-Potential of the Leaf

1955 ◽  
Vol 23 (3) ◽  
pp. 187-191
Author(s):  
Isamu BABA ◽  
Katsumi INADA
Keyword(s):  
Light Intensity ◽  
Redox Potential ◽  
Water Temperature ◽  
Rice Plant ◽  
Reduction Potential ◽  
Tissue Fluid ◽  
Varietal Differences ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

Development of polymer lab-on-a-chip (LOC) for oxidation-reduction potential (ORP) measurement

2011 ◽  
Vol 63 (10) ◽  
pp. 2309-2315 ◽  
Author(s):  
A. Jang ◽  
K. K. Lee ◽  
P. L. Bishop ◽  
I. S. Kim ◽  
C. H. Ahn
Keyword(s):  
Redox Potential ◽  
Self Assembly ◽  
Reduction Potential ◽  
Lab On A Chip ◽  
Feed Solution ◽  
Water Shortage ◽  
Rapid Methods ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Ro Membrane

Reverse osmosis (RO) desalination has been recognized as a promising method to solve the water shortage problem. Nevertheless, since it is energy intensive and has many problems associated with biofouling/fouling of RO membranes in RO plants, its commercial acceptance is still slow. Especially, as high levels of oxidizing agents negatively affect RO membrane efficiency and life span. So, there is a need to develop sensitive, selective, portable and rapid methods to determine oxidation-reduction potential (ORP) in feed solution. For developing a polymer ORP lab-on-a- chip (LOC), a microchannel patterned on a polymer substrate was successfully filled with 800 nm diameter silica beads using self-assembly bead packing technology. The measured ORPs using the three kinds of redox potential solutions were typically slightly lower than those of the nominal redox potential. But, all of the measurements should be deemed acceptable. The ORP LOC has also a much shorter response time than the conventional potentiometric sensor.

Changes in oxidation-reduction potential during milk fermentation by wild lactic acid bacteria

2016 ◽  
Vol 83 (3) ◽  
pp. 387-394 ◽  
Author(s):  
Stefano Morandi ◽  
Tiziana Silvetti ◽  
Alberto Tamburini ◽  
Milena Brasca
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Redox Potential ◽  
Reduction Potential ◽  
Reducing Power ◽  
Streptococcus Thermophilus ◽  
Reduction Activity ◽  
Oxidation Reduction ◽  
Milk Fermentation ◽  
Oxidation Reduction Potential

Oxidation-reduction potential (Eh) is a fundamental physicochemical property of lactic acid bacteria that determines the microenvironment during the cheese manufacture and ripening. For this reason the Eh is of growing interest in dairy research and the dairy industry. The objective of the study was to perform a comprehensive study on the reduction activity of wild lactic acid bacteria strains collected in different periods (from 1960 to 2012) from Italian dairy products. A total of 709 strains belonging to Lactococcus lactis, Enterococcus durans, E. faecium, E. faecalis and Streptococcus thermophilus species were studied for their reduction activity in milk. Kinetics of milk reduction were characterised by the minimum redox potential (Eh7) and time of reaching Eh7 (tmin), the maximum difference between two measures (Δmax) and the time at which these maximum differences occurred (t*). Broad diversity in kinetic parameters was observed at both species and strain levels. E. faecalis and L. lactis resulted to be the most reducing species, while S. thermophilus was characterised by the lowest reducing power while the greatest heterogeneity was pointed out among E. durans and E. faecium strains. Considering the period of collection (1960–2012) we observed that the more recently isolated strains generally showed less reducing activity. This trend was particularly evident for the species E. durans, E. faecium and L. lactis while an opposite trend was observed in E. faecalis species. Data reported in this research provide new information for a deeper understanding of redox potential changes during milk fermentation due to bacterial growth. Gain knowledge of the redox potential of the LAB cultures could allow a better control and standardisation of cheesemaking process.

The Effect of Oxidation-Reduction Potential on the Biotransformations of Chlorinated Hydrocarbons

1992 ◽  
Vol 26 (1-2) ◽  
pp. 159-168 ◽  
Author(s):  
R.-A. Doong ◽  
S.-C. Wu
Keyword(s):  
Redox Potential ◽  
Reductive Dechlorination ◽  
Reduction Potential ◽  
Chlorinated Hydrocarbons ◽  
Viable Count ◽  
Redox Potentials ◽  
Strong Electron ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Primary Substrate

Two batch experiments with acetate as the primary substrate and different combinations of chlorinated hydrocarbons as the secondary substrate were carried out to evaluate the effect of the redox potential of the environment on the biotransformations of chlorinated hydrocarbons. In both single and mixed contaminant(s) systems, biotransformations of 100 µg/L of tetrachloroethylene (PCE) and carbon tetrachloride (CT) were observed, but that of 1,1,1-trichloroethane(1,1,1-TCA) was not observed within 108 days. Chlorinated hydrocarbons acted as electron traps and scavenged the electrons when they underwent reductive dechlorination. Adequate activity of free available electrons is necessary for chlorinated hydrocarbons to undergo reductive dechlorination. The environment with low redox potential has relatively strong electron activity and therefore facilitates the biotransformation of the chlorinated hydrocarbons more readily. Disappearance of 17 to 62 % and 22 to 99.9 % of the original concentration of PCE and CT were observed when the redox potentials of the microcosms were ranged from 225 to -263 mV and 188 to -263 mV, respectively. The viable count of microorganisms determined by the epifluorescence technique showed that higher concentration of primary substrate produced more biomass than lower concentration of primary substrate did, but the DNA content of the microbes was not a good biochemical indicator for the biotransformability of the chlorinated hydrocarbons. It is concluded that oxidation-reduction potential is the major factor controlling the biotransformation efficiencies of chlorinated hydrocarbons. In the case of in-situ biorestoration, proper control of redox potential of the environment will give a good result of remediation of the groundwater contaminated with chlorinated hydrocarbons.

scholarly journals Measurement of Redox Potential in Nanoecotoxicological Investigations

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ratna Tantra ◽  
Alex Cackett ◽  
Roger Peck ◽  
Dipak Gohil ◽  
Jacqueline Snowden
Keyword(s):  
Redox Potential ◽  
Reduction Potential ◽  
Redox Potentials ◽  
Dissolved Oxygen Concentration ◽  
Liquid Media ◽  
Pt Electrode ◽  
Potential Value ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Value Contribution

Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO2)) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

scholarly journals In situ measurements of oxidation–reduction potential and hydrogen peroxide concentration as tools for revealing LPMO inactivation during enzymatic saccharification of cellulose

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Adnan Kadić ◽  
Anikó Várnai ◽  
Vincent G. H. Eijsink ◽  
Svein Jarle Horn ◽  
Gunnar Lidén
Keyword(s):  
Reduction Potential ◽  
Enzymatic Saccharification ◽  
The State ◽  
Enzyme Inactivation ◽  
Ex Situ ◽  
Process Economics ◽  
Complete Inactivation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

Abstract Background Biochemical conversion of lignocellulosic biomass to simple sugars at commercial scale is hampered by the high cost of saccharifying enzymes. Lytic polysaccharide monooxygenases (LPMOs) may hold the key to overcome economic barriers. Recent studies have shown that controlled activation of LPMOs by a continuous H2O2 supply can boost saccharification yields, while overdosing H2O2 may lead to enzyme inactivation and reduce overall sugar yields. While following LPMO action by ex situ analysis of LPMO products confirms enzyme inactivation, currently no preventive measures are available to intervene before complete inactivation. Results Here, we carried out enzymatic saccharification of the model cellulose Avicel with an LPMO-containing enzyme preparation (Cellic CTec3) and H2O2 feed at 1 L bioreactor scale and followed the oxidation–reduction potential and H2O2 concentration in situ with corresponding electrode probes. The rate of oxidation of the reductant as well as the estimation of the amount of H2O2 consumed by LPMOs indicate that, in addition to oxidative depolymerization of cellulose, LPMOs consume H2O2 in a futile non-catalytic cycle, and that inactivation of LPMOs happens gradually and starts long before the accumulation of LPMO-generated oxidative products comes to a halt. Conclusion Our results indicate that, in this model system, the collapse of the LPMO-catalyzed reaction may be predicted by the rate of oxidation of the reductant, the accumulation of H2O2 in the reactor or, indirectly, by a clear increase in the oxidation–reduction potential. Being able to monitor the state of the LPMO activity in situ may help maximizing the benefit of LPMO action during saccharification. Overcoming enzyme inactivation could allow improving overall saccharification yields beyond the state of the art while lowering LPMO and, potentially, cellulase loads, both of which would have beneficial consequences on process economics.

Sign in / Sign up

Export Citation Format

Share Document