Redox-Controlled Ammonium Storage and Overturn in Ediacaran Oceans

As a key nutrient, nitrogen can limit primary productivity and carbon cycle dynamics, but also evolutionary progress. Given strong redox-dependency of its molecular speciation, environmental conditions can control nitrogen localization and bioavailability. This particularly applies to periods in Earth history with strong and frequent redox fluctuations, such as the Neoproterozoic. We here report on chlorophyll-derived porphyrins and maleimides in Ediacaran sediments from Oman. Exceptionally light δ15N values (< –10‰) in maleimides derived from anoxygenic phototrophs point towards ammonium assimilation at the chemocline, whereas the isotopic offset between kerogens and chlorophyll-derivatives indicates a variable regime of cyanobacterial and eukaryotic primary production in surface waters. Biomarker and maleimide mass balance considerations imply shallow euxinia during the terminal Ediacaran and a stronger contribution of anoxygenic phototrophs to primary productivity, possibly as a consequence of nutrient ‘lockup’ in a large anoxic ammonium reservoir. Synchronous δ13C and δ15N anomalies at the Ediacaran–Cambrian boundary may reflect one in a series of overturn events, mixing ammonium and isotopically-light DIC into oxic surface waters. By modulating access to nitrogen, environmental redox conditions may have periodically affected Ediacaran primary productivity, carbon cycle perturbations, and possibly played a role in the timing of the metazoan radiation across the terminal Ediacaran and early Cambrian.

THE INFLUENCE OF THE AGENDA ON THE PRODUCTIVITY OF COWS OF DIFFERENT LACTATIONS UNDER DIFFERENT KEEPING REGIMES

It was found that during lactation the milking of cows in the experimental groups at the constant regime were at the level of 4639 kg of milk, which is more than at the variable regime by 159.8 kg or 3.57%. As a result, the cost of feed in the variable mode of the day per 1 kg of milk was 1.38 feed units, and at constant - 1.10 feed units, which is less than 0.28 feed units or 20.3%. The constant daily routine reduced labor costs in milk production by 9.7%, and by 1 quintal of milk - 34.2%. It is presented that it is inexpedient to violate the daily routine, which leads to the loss of marketable milk by more than 3.6%.

Modeling of air flow in industrial rooms

The article is devoted to the air distribution in a room by swirl and laying air jets. Dynamic parameters of air flow that is created due to swirl and laying air jets at their leakage in a room has been determined. The mathematical model of air supply with swirl and laying air jets in the industrial rooms is improved. Simulation of air flow is performed due to CFD FLUENT (Ansys FLUENT). Solution of the equation by using k-ε model of turbulence is presented. Dynamic parameters of air flow that is created due to swirl and laying air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulence air flow in the room are presented. The results of theoretical researches of influence of dynamic microclimate to the human organism are presented.

Modelling of air flow supply in a room at variable regime by using both K - E and spalart – allmaras turbulent model

The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Сalculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it’s possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.