Influence of 15NH4+-application on gross N turnover rates in soil

2003 ◽  
Vol 35 (4) ◽  
pp. 603-606 ◽  
Author(s):  
J Luxhøi
Keyword(s):  
Turnover Rates ◽  
N Turnover ◽  
Gross N Turnover

Elevated CO2 and O3 modify N turnover rates, but not N2O emissions in a soybean agroecosystem

2012 ◽  
Vol 51 ◽  
pp. 104-114 ◽  
Author(s):  
Charlotte Decock ◽  
Haegeun Chung ◽  
Rodney Venterea ◽  
Sharon B. Gray ◽  
Andrew D.B. Leakey ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
N2o Emissions ◽  
Turnover Rates ◽  
N Turnover ◽  
Elevated Co2 And O3

scholarly journals Quantification of the recycling of microbial nitrogen in the rumen using a mechanistic model of rumen fermentation processes

1998 ◽  
Vol 130 (1) ◽  
pp. 81-94 ◽  
Author(s):  
J. DIJKSTRA ◽  
J. FRANCE ◽  
S. TAMMINGA
Keyword(s):  
Dry Matter ◽  
Mechanistic Model ◽  
Rumen Fermentation ◽  
Turnover Rates ◽  
Microbial Protein ◽  
Maize Silage ◽  
Fermentation Processes ◽  
N Turnover ◽  
Maize Grain ◽  
Microbial N

The effects of dietary variations on microbial N turnover and recycling related to protozoal activities in the rumen were examined using a previously described model of rumen fermentation processes. Simulations were performed with diets containing variable proportions of concentrate (between 0 and 1 kg/kg diet dry matter) at a rate of daily dry matter intake (DMI) by cattle of between 5·3 and 21·0 kg/day. The roughages examined were hay, fresh grass and maize silage, and the concentrate supplements included molasses, barley, maize grain, untreated and formaldehyde-treated soyabean meal. The simulated fractional turnover rate of microbial N varied between 0·416 and 1·556/day, and simulated microbial N recycling ranged from 34·9 to 76·2% of gross microbial N synthesis. High turnover rates and recycling were observed particularly for diets containing maize silage as roughage and molasses and maize grain as concentrate supplements. Increased DMI generally resulted in reduced turnover rates with high-roughage diets, but increased turnover rates with high-concentrate diets. These responses of microbial N turnover and recycling were related to substrate availability and the substrate preferences of protozoa and, consequently, protozoal activities in the rumen. The large impact of recycling on the amount of organic matter required per unit of microbial protein washed out of the rumen was demonstrated. Thus, by quantification of the interactions between microbial populations in the rumen, the model can help to interpret the differences in microbial N recycling observed in the experiments and provide an improved understanding of the efficiency of microbial protein synthesis.

Colloidal systems in soils

1994 ◽  
Vol 52 ◽  
pp. 64-65
Author(s):  
J. Thieme ◽  
J. Niemeyer ◽  
P. Guttman
Keyword(s):  
Clay Minerals ◽  
Polymeric Materials ◽  
Spatial Arrangement ◽  
High Specific Surface Area ◽  
Turnover Rates ◽  
Colloidal Systems ◽  
Chemical Conditions ◽  
Aggregation Phenomena ◽  
Iron And Manganese ◽  
Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

Turnover and Distribution of 131Iodine-Labelled Human Fibrinogen

1964 ◽  
Vol 11 (02) ◽  
pp. 404-422 ◽  
Author(s):  
Annemarie Amris ◽  
C. J Amris
Keyword(s):  
Body Weight ◽  
Cancer Patient ◽  
Distribution Ratio ◽  
Half Life ◽  
Fibrinolytic Activity ◽  
The Other ◽  
Turnover Rates ◽  
Human Fibrinogen ◽  
Coagulation Defects ◽  
Fractional Turnover

Summary14 patients (5 diabetics with arteriosclerotic complications, 4 patients with thrombo-embolic disease, 4 with cirrhosis, coagulation defects and increased fibrinolytic activity, and 1 cancer patient) and 3 control patients were subjected to turnover studies with 13iodine labelled human fibrinogen.Half-life times in the control patients were found to be 4 days, the fractional turnover rates 19–23 per cent, of intravascular fibrinogen per day, and the absolute turnover 0.02 to 0.06 gm per day per kg. body weight. The other patient’s half-life times and turnover rates varied considerably from 0.9–5.5 days, 13–160 per cent, per day of intravascular fibrinogen and 0.02–0.4 gm per day per kg. body weight respectively.As fibrinogen unlike other proteins subjected to turnover studies, is converted to fibrin, it is not possible to measure the true intra-extravascular distribution ratio of fibrinogen. But intravascular fibrinogen could be approximated to constitute 68–99 per cent, of the total fibrinogen. There is justification in believing that fibrinogen is degradated through a continuous coagulation in equilibrium with fibrinolysis, and that the organism contains a greater mass of fibrin, the “fibrin pool”. Considerations of the turnover mechanism can however only be hypothetical.

Is Professional Commitment The Reason For Turnover Intentions of IT Professionals?

2019 ◽  
Vol 5 (1) ◽  
pp. 124
Author(s):  
Mohamed Buhari Mufitha ◽  
Su Teng Lee ◽  
Chen Chen Yong
Keyword(s):  
Job Satisfaction ◽  
Structural Equation ◽  
Turnover Intentions ◽  
Equation Model ◽  
Professional Commitment ◽  
Turnover Rates ◽  
It Professionals ◽  
Professional Advancement ◽  
Software Engineers ◽  
Job Satisfactions

Compared to others, professionals share distinguish workplace characteristics: one such is the high commitment to the professions over to working organizations. Information Technology (IT) professionals demonstrate higher turnover rates compared to others: their commitments to the profession has been suspected as a source of turnover. Considering their job satisfactions the present study aimed to investigate the influence of professional commitment on IT professionals’ turnover intentions. Data were collected from a sample of software engineers from Sri Lank using a survey questionnaire. The results of the structural equation model analysis concluded that professional commitment weakens IT professionals’ turnover intentions, which is partially mediated by job satisfaction. Professional commitment stimulates IT professionals’ job satisfaction. The findings challenge the presumption that IT professionals leave their organizations due to high commitments to the profession. Few factors were identified as significant in their job satisfactions: supervision, co-workers and work design. Pay and promotions were the least influencing job satisfaction factors. Managers may employ few strategies in their retention strategies: facilitate professional advancement needs within organizations, closely monitor supervision activities occurs and provide challenging and meaningful jobs. The study contributes to the turnover literature through empirical evidence on the influence of professional commitment on knowledge workers’ turnover intentions.

Revisiting Glycerol Esterification with Acetic Acid over Amberlyst-35 via Statistically Designed Experiments: Overcoming Transport Limitations

2019 ◽  
Author(s):  
Víctor Gabriel Baldovino Medrano ◽  
Karen V. Caballero ◽  
Hernando Guerrero-Amaya
Keyword(s):  
Acetic Acid ◽  
Active Sites ◽  
Batch Reactor ◽  
Catalyst Particle ◽  
Experimental Designs ◽  
Particle Sizes ◽  
Turnover Rates ◽  
Designed Experiments ◽  
Different Temperatures ◽  
Glycerol Esterification

Turnover rates for glycerol esterification with acetic acid over Amberlyst-35 were measured under different temperatures, reactants and active sites concentrations, and catalyst particle sizes. Data were collected in a batch reactor. Experiments were done following a sequence of factorial experimental designs.

Sign in / Sign up

Export Citation Format

Share Document