A multicompartmental model to describe marker excretion patterns in ruminant faeces

1. A multicornpartmental model, which assumes first-order kinetics, is proposed to describe digesta flow along the gastrointestinal tract of ruminants.2. Solution of the model yields a multiplicative equation, containing a single-exponential term and a double-exponential term, for describing faecal outflow rate.3. The logarithmic transformation of the equation was fitted to eighty-two excretion curves obtained after the administration of marker into the rumen of cattle and sheep, and compared with other published models.4. It was found to be superior to the other models in that it fitted all the data sets successfully.

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Zinc(II) and copper(II) complexes with pheophytin and mesoporphyrin and their stability to UV-B irradiation: Vis spectroscopy studies

Journal of the Serbian Chemical Society ◽

10.2298/jsc110310175z ◽

2012 ◽

Vol 77 (2) ◽

pp. 187-199 ◽

Cited By ~ 6

Author(s):

Jelena Zvezdanovic ◽

Dejan Markovic ◽

Sanja Milenkovic

Keyword(s):

Heavy Metal ◽

The Other ◽

First Order ◽

Absorbance Spectroscopy ◽

First Order Kinetics ◽

Porphyrin Derivatives ◽

Vis Spectroscopy ◽

Photochemical Decomposition ◽

Spectroscopy Studies ◽

The One

Stability of Zn(II) and Cu(II) complexes of porphyrin derivatives (pheophytin and mesoporphyrin) to UV-B -irradiation has been studied by absorbance spectroscopy in 95% ethanol. The chosen porphyrins as well as their heavy metal complexes undergo photochemical decomposition obeying first-order kinetics. In general, pheophytin is more stable than mesoporphyrin to UV-B irradiation. On the other hand, stability of Zn(II)-complex is smaller than Cu(II)-complex both for pheophytin and mesoporphyrin; however while Cu(II)-complex with pheophytin is more stable than the one with mesoporphyrin, with Zn(II)-complex the situation is vice versa.

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Thermal reactions of mesityl oxide

Australian Journal of Chemistry ◽

10.1071/ch9710955 ◽

1971 ◽

Vol 24 (5) ◽

pp. 955 ◽

Cited By ~ 4

Author(s):

NJ Daly ◽

MF Gilligan

Keyword(s):

Carbon Monoxide ◽

Methyl Bromide ◽

Hydrogen Bromide ◽

The Other ◽

Mesityl Oxide ◽

Thermal Reactions ◽

First Order ◽

First Order Kinetics

Mesityl oxide (4-methylpent-3-en-2-one) thermally decomposes in the range 412-490� give methylbutenes, carbon monoxide, isobutene, and methane as major products. The initial 20% of reaction follows first- order kinetics and is described by the equation k1 = 1014.22exp(-63240/RT) s-1. A Rice-Herzfeld chain is proposed. Addition of hydrogen bromide leads to two reactions, one producing isobutene, carbon monoxide, and methyl bromide, and the other leading to polymerization. Likely steps in the polymerization are proposed.

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Quantitative analysis of proton-linked transport system. β-Galactoside exit in Escherichia coli

Biochemical Journal ◽

10.1042/bj1880467 ◽

1980 ◽

Vol 188 (2) ◽

pp. 467-473 ◽

Cited By ~ 19

Author(s):

I R Booth ◽

W A Hamilton

Keyword(s):

Escherichia Coli ◽

Quantitative Analysis ◽

Transport System ◽

Rate Constants ◽

The Other ◽

First Order ◽

First Order Kinetics ◽

Solute Accumulation ◽

External Ph

The exit of lactose and thiomethyl-beta-D-galactoside from Escherichia coli ML308-225 has been studied to determine the role of carrier-dependent (zero-trans efflux) and carrier-independent (leak) processes. On the basis of its sensitivity to p-chloromercuribenzene sulphonate the exit of lactose was found to be almost wholly mediated by the carrier. Consistent with this conclusion was the finding that the rate of exit of this sugar was dependent on the external pH, being considerably slower at acid pH. On the other hand exit of thiomethyl-beta-D-galactoside was found to be composed of both carrier-dependent and carrier-independent processes. Both processes exhibited first-order kinetics with the rate constants for zero-trans efflux and leak being 0.137 min-1 and 0.079 min-1, respectively. The relevance of these findings for out earlier proposal for the methods of attenuation of solute accumulation is discussed [Booth, Mitchell & Hamilton (1979) Biochem. J. 182, 687–696].

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Comparison Of Empirical Models For Estimating The Mineralization Potential Of Soil Nitrogen

JOURNAL OF ADVANCES IN AGRICULTURE ◽

10.24297/jaa.v7i4.6485 ◽

2017 ◽

Vol 7 (4) ◽

pp. 1189-1202

Author(s):

Zoubeir Bensid

Keyword(s):

Nitrogen Mineralization ◽

Goodness Of Fit ◽

Empirical Models ◽

The Other ◽

Kinetics Model ◽

Strong Positive Correlation ◽

Mineralization Process ◽

First Order ◽

First Order Kinetics ◽

Significant Difference

Modeling is an attempt to describe a natural event mathematically. The modeling of N mineralization process has a dual interest, agronomical and ecological. The objective of this study is to evaluate several mathematical models to describe the nitrogen mineralization process of soil samples. These samples were collected from 34 sites spatially distributed in the semi-arid region of El-Madher (the Aures area, north-east of Algeria). Using an auger, the systematic surveys have been carried out and composite samples of soils were collected in the field, and subjected to physical and chemical analyzes. In order to track the kinetic organic nitrogen mineralization, similar samples were collected and taken into cool boxes have been incubated in laboratory, sieved (2 mm) and stored at 4°C before use and then incubated at 28°C for 56 weeks. To facilate comparison, all results have been statistically analyzed, by nonlinear regression and analysis of variance method. Four empirical models were tested to fitt the value found experimentally. The linear kinetics model Nm=k t Ni, the single first-order kinetics model (MI) Nm = Ni e-kt + No (1 - e-kt), the double first-order and the exponential kinetics model (MII) Nm=Ni e-kt + No (1 - e-kt) + e-ht and the hyperbolic kinetics model (MH) Nm=NoH.t/(Tc+t) Ni were used to simulate the cumulative mineralized N (NH4+-N and NO3- -N) in the laboratory incubation. In order to test the performance and robustness of the different models three goodness of fit (coefficient of determination R2, Root Mean Square RMS and Mean Relative Error RMSE) were used. Moreover, the parameters obtained by the different models determined the predictions of nitrogen mineralization. The best results were obtained using the double first-order and exponential kinetics model. The results showed no significant difference between nitrogen mineralized for 56 weeks and nitrogen predicted by various models. However, the N predicted by the MII appears to be the best compared to other models. Indeed, the overestimation of nitrogen potentially mineralizable (N0) obtained by this model was relatively lower than other models. This has been confirmed by the study of multiple correlations between net mineral nitrogen and nitrogen predicted by each model. Thus, the results obtained showed a strong positive correlation between mineralized nitrogen values and those of nitrogen predicted by the different models. The correlation coefficients values indicate the folowing order MII (r = 0.878)> MI (r = 0.748)> MH (r = 0.709). The MII model has, therefore, highlighted that two pools of organic matter that mineralize simultaneously were detected in soil. One pool is stable and the other one is labile. One pool evolves with first-order kinetics and the other with exponential kinetics.

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Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽

10.32964/tj17.03.167 ◽

2018 ◽

Vol 17 (03) ◽

pp. 167-178 ◽

Cited By ~ 2

Author(s):

Xin Tong ◽

Jiao Li ◽

Jun Ma ◽

Xiaoquan Chen ◽

Wenhao Shen

Keyword(s):

Degradation Rate ◽

Southern China ◽

Catalytic Degradation ◽

Pulp And Paper ◽

Gaseous Pollutants ◽

Pulp And Paper Mills ◽

Paper Mills ◽

Initial Concentration ◽

First Order ◽

First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

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Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200529123151 ◽

2020 ◽

Vol 16 ◽

Author(s):

M. Alarjah

Keyword(s):

Half Life ◽

Hplc Method ◽

Hydrolysis Rate ◽

First Order ◽

First Order Kinetics ◽

Rp Hplc ◽

Pharmacokinetic Properties ◽

Pseudo First Order ◽

Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

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Thematic Maps for the Variation of Bearing Capacity of Soil Using SPTs and MATLAB

Geosciences ◽

10.3390/geosciences10090329 ◽

2020 ◽

Vol 10 (9) ◽

pp. 329

Author(s):

Mahdi O. Karkush ◽

Mahmood D. Ahmed ◽

Ammar Abdul-Hassan Sheikha ◽

Ayad Al-Rumaithi

Keyword(s):

Bearing Capacity ◽

Mean Squared Error ◽

Ground Level ◽

The Other ◽

Thematic Maps ◽

First Order ◽

Squared Error ◽

Order Polynomial ◽

Interpolation Polynomials ◽

Penetration Tests

The current study involves placing 135 boreholes drilled to a depth of 10 m below the existing ground level. Three standard penetration tests (SPT) are performed at depths of 1.5, 6, and 9.5 m for each borehole. To produce thematic maps with coordinates and depths for the bearing capacity variation of the soil, a numerical analysis was conducted using MATLAB software. Despite several-order interpolation polynomials being used to estimate the bearing capacity of soil, the first-order polynomial was the best among the other trials due to its simplicity and fast calculations. Additionally, the root mean squared error (RMSE) was almost the same for the all of the tried models. The results of the study can be summarized by the production of thematic maps showing the variation of the bearing capacity of the soil over the whole area of Al-Basrah city correlated with several depths. The bearing capacity of soil obtained from the suggested first-order polynomial matches well with those calculated from the results of SPTs with a deviation of ±30% at a 95% confidence interval.

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Using historical data to facilitate clinical prevention trials in Alzheimer disease? An analysis of longitudinal MCI (mild cognitive impairment) data sets

Alzheimer s Research & Therapy ◽

10.1186/s13195-021-00832-5 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Manfred Berres ◽

Andreas U. Monsch ◽

René Spiegel

Keyword(s):

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Cognitive Performance ◽

Placebo Treatment ◽

Drug Trial ◽

The Other ◽

Data Sets ◽

Control Groups ◽

Community Needs ◽

Clinical Prevention

Abstract Background The Placebo Group Simulation Approach (PGSA) aims at partially replacing randomized placebo-controlled trials (RPCTs), making use of data from historical control groups in order to decrease the needed number of study participants exposed to lengthy placebo treatment. PGSA algorithms to create virtual control groups were originally derived from mild cognitive impairment (MCI) data of the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. To produce more generalizable algorithms, we aimed to compile five different MCI databases in a heuristic manner to create a “standard control algorithm” for use in future clinical trials. Methods We compared data from two North American cohort studies (n=395 and 4328, respectively), one company-sponsored international clinical drug trial (n=831) and two convenience patient samples, one from Germany (n=726), and one from Switzerland (n=1558). Results Despite differences between the five MCI samples regarding inclusion and exclusion criteria, their baseline demographic and cognitive performance data varied less than expected. However, the five samples differed markedly with regard to their subsequent cognitive performance and clinical development: (1) MCI patients from the drug trial did not deteriorate on verbal fluency over 3 years, whereas patients in the other samples did; (2) relatively few patients from the drug trial progressed from MCI to dementia (about 10% after 4 years), in contrast to the other four samples with progression rates over 30%. Conclusion Conventional MCI criteria were insufficient to allow for the creation of well-defined and internationally comparable samples of MCI patients. More recently published criteria for MCI or “MCI due to AD” are unlikely to remedy this situation. The Alzheimer scientific community needs to agree on a standard set of neuropsychological tests including appropriate selection criteria to make MCI a scientifically more useful concept. Patient data from different sources would then be comparable, and the scientific merits of algorithm-based study designs such as the PGSA could be properly assessed.

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