Shifts in Biodegradation Kinetics of the Herbicides MCPP and 2,4-D at Low Concentrations in Aerobic Aquifer Materials

2003 ◽  
Vol 37 (14) ◽  
pp. 3095-3103 ◽  
Author(s):  
Lars Toräng ◽  
Niels Nyholm ◽  
Hans-Jørgen Albrechtsen
Keyword(s):  
Biodegradation Kinetics ◽  
Low Concentrations ◽  
Kinetics Of

scholarly journals Determining Biodegradation Kinetics of Hydrocarbons at Low Concentrations: Covering 5 and 9 Orders of Magnitude ofKowandKaw

2018 ◽  
Vol 52 (4) ◽  
pp. 2143-2151 ◽  
Author(s):  
Heidi Birch ◽  
Rikke Hammershøj ◽  
Philipp Mayer
Keyword(s):  
Biodegradation Kinetics ◽  
Low Concentrations ◽  
Kinetics Of

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

scholarly journals New Trimethoprim-Like Molecules: Bacteriological Evaluation and Insights into Their Action

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 709
Author(s):  
Marta Jorba ◽  
Marina Pedrola ◽  
Ouldouz Ghashghaei ◽  
Rocío Herráez ◽  
Lluis Campos-Vicens ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Efflux Pump ◽  
Synergistic Effects ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Detailed Characterization ◽  
Low Concentrations ◽  
Pump Activity ◽  
Bacteriological Evaluation ◽  
Kinetics Of

This work reports a detailed characterization of the antimicrobial profile of two trimethoprim-like molecules (compounds 1a and 1b) identified in previous studies. Both molecules displayed remarkable antimicrobial activity, particularly when combined with sulfamethoxazole. In disk diffusion assays on Petri dishes, compounds 1a and 1b showed synergistic effects with colistin. Specifically, in combinations with low concentrations of colistin, very large increases in the activities of compounds 1a and 1b were determined, as demonstrated by alterations in the kinetics of bacterial growth despite only slight changes in the fractional inhibitory concentration index. The effect of colistin may be to increase the rate of antibiotic entry while reducing efflux pump activity. Compounds 1a and 1b were susceptible to extrusion by efflux pumps, whereas the inhibitor phenylalanine arginyl β-naphthylamide (PAβN) exerted effects similar to those of colistin. The interactions between the target enzyme (dihydrofolate reductase), the coenzyme nicotinamide adenine dinucleotide phosphate (NADPH), and the studied molecules were explored using enzymology tools and computational chemistry. A model based on docking results is reported.

Biodegradation Kinetics of 17α-Ethinylestradiol in Activated Sludge Treatment Processes

2015 ◽  
Vol 32 (7) ◽  
pp. 637-646 ◽  
Author(s):  
Mariko J. Lust ◽  
Ryan M. Ziels ◽  
Stuart E. Strand ◽  
Heidi L. Gough ◽  
H. David Stensel
Keyword(s):  
Activated Sludge ◽  
Biodegradation Kinetics ◽  
Sludge Treatment ◽  
Treatment Processes ◽  
Kinetics Of

Determination of Biodegradation Kinetics of Bacterial Storage Organic Substrates Through Electrolytic Respirometry

2000 ◽  
Vol 21 (10) ◽  
pp. 1111-1118 ◽  
Author(s):  
P. Cañizares ◽  
A. De Lucas ◽  
L. Rodríguez ◽  
J. Villaseñor
Keyword(s):  
Organic Substrates ◽  
Biodegradation Kinetics ◽  
Kinetics Of

scholarly journals Enhanced Adsorption of Methanol by Oxidised Nutshell Carbon

2000 ◽  
Vol 18 (3) ◽  
pp. 261-266 ◽  
Author(s):  
Alan Bailey ◽  
Mike Williams ◽  
Lyndsay Dunne ◽  
Lynne Beames
Keyword(s):  
Nitric Acid ◽  
Water Adsorption ◽  
Opposite Effect ◽  
Kinetics Of Adsorption ◽  
Dry Air ◽  
Low Concentrations ◽  
Methanol Vapour ◽  
Adsorption Reduction ◽  
Enhanced Adsorption ◽  
Kinetics Of

A nutshell charcoal was oxidised and reduced and the effect of the treatments on the water adsorption isotherms and methanol vapour penetration noted. Oxidation with 6 M nitric acid increased the penetration times for methanol vapour in dry air, not by just raising the dynamic capacity at low concentrations but also by improving the kinetics of adsorption. Reduction caused the opposite effect. The improvement in the adsorption kinetics is thought to be due to surface diffusion on to the oxidised surface of the transport pores.

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