Impact of flow rate on lactate uptake and gluconeogenesis in glucagon-stimulated perfused livers

2006 ◽  
Vol 290 (1) ◽  
pp. E185-E191 ◽  
Author(s):  
Ken D. Sumida ◽  
Jerry H. Urdiales ◽  
Casey M. Donovan
Keyword(s):  
Flow Rate ◽  
Dominant Role ◽  
Bicarbonate Buffer ◽  
Flow Rates ◽  
Exponential Decline ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
Lactate Uptake ◽  
The Impact ◽  
Bovine Erythrocytes

The impact of reduced hepatic flow on lactate uptake and gluconeogenesis was examined in isolated glucagon-stimulated perfused livers from 24-h-fasted rats. After surgical isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit (KH) bicarbonate buffer, fresh bovine erythrocytes (hematocrit ∼20%), and no added substrate. After this “washout” period, steady-state perfusions were initiated with a second reservoir containing the KH buffer, bovine erythrocytes, [U-14C]lactate (10,000 dpm/ml), lactate (2.5 mM), and glucagon (250 μg/ml). Perfusion flow rate was adjusted to one of five rates (i.e., 1.8, 2.7, 3.9, 7.4, and 11.0 ml·min−1·100 g body wt−1). After the perfusion, the liver was dissected out and weighed so as to establish the actual flow rate per gram of liver. The resulting flow rates ranged from 0.52 to 4.03 ml·min−1·g liver−1. As a function of flow rate, lactate uptake rose in a hyperbolic fashion to an apparent plateau of 2.34 μmol·min−1·g liver−1. Fractional extraction (FX) of lactate from the perfusate demonstrated an exponential decline with increased flow rates ( r = 0.97). At flow rates above 1.0 ml·min−1·g liver−1, adjustments in FX compensated for changes in lactate delivery, resulting in steady rates of lactate uptake and gluconeogenesis. Below 1.0·min−1·g liver−1 the increased FX was unable to compensate for the decline in lactate delivery and lactate uptake declined rapidly. Gluconeogenesis demonstrated similar kinetics to lactate uptake, reflecting its dominant role among pathways for lactate removal under the current conditions.

A New Method for Performance Measurement of PPV Fans for Fire Fighting Under Realistic Conditions

2020 ◽  
Author(s):  
Michael Steppert ◽  
Philipp Epple ◽  
Michael Steber ◽  
Stefan Gast
Keyword(s):  
Design Process ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Navier Stokes ◽  
Analytical Relation ◽  
Positive Pressure ◽  
Flow Rates ◽  
Free Jet ◽  
Actual Flow Rate ◽  
Coefficient Of Discharge

Abstract PPV Fans (Positive Pressure Ventilation Fans) are used in firefighting to remove smoke from a burning building, so that fire fighters can have a clear view inside the house and injured people do not have to breathe toxic smoke. This can be done by placing a PPV fan in a distance of about two meters in front of a door of the burning building. On another, carefully chosen position in the building, e. g. a window, a door or at the roof an opening has to be created, where the smoke can leave the building. The same volumetric flow rate of gas that is blown into the building by the PPV fan has to leave the building at a chosen opening. Because the gas entering the building is air and the gas leaving the building is a mixture of smoke and air, the smoke concentration in the building can be reduced. To test the performance of such PPV fans, a test building with a door in the first floor and a window in the 3rd floor has been built. To measure the volumetric flow rate of the smoke and air mixture through the window in the 3rd floor that is leaving the building, a flow meter nozzle was designed. The design process was done using the commercial Navier Stokes solver Star CCM+, where three nozzle designs, such as a nozzle with constant velocity increase, a quarter circle nozzle and a non-curved nozzle were investigated for different volumetric flow rates. Also, a rounding at the window, where the nozzle is placed, was investigated to prevent flow detachment and shock losses at the inlet of the nozzle. The volumetric flow rate through the nozzle can be calculated, by measuring the pressure at the nozzle wall (before the contraction) and applying Bernoulli’s law, the continuity equation and assuming atmospheric pressure at the free jet flow at the end of the nozzle. The so calculated volumetric flow rate was compared with the actual flow rate, given by the numerical CFD simulations. With these values, the nozzle specific coefficient of discharge for several volumetric flow rates has been calculated and a function fitting was done to get obtain analytical relation between pressure and volumetric flow rate. The detailed design process of the three nozzles, the numerical results of the CFD studies and the determination of the nozzle specific coefficients of discharge are shown and discussed in detail in this work.

Addressing the siphoning effect in new shunt designs by decoupling the activation pressure and the pressure gradient across the valve

2013 ◽  
Vol 11 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Tobias A. Mattei ◽  
Martin Morris ◽  
Kathleen Nowak ◽  
Daniel Smith ◽  
Jeremy Yee ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Fluid Velocity ◽  
Component System ◽  
The Past ◽  
Benchmark Tests ◽  
Final Design ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
Labview Program

Object Although several improvements have been observed in the past few years in shunt technology, currently available systems still present several associated problems. Among these, overdrainage along with its complications remains one of the great challenges for new shunt designs. To address the so-called siphoning effect, the authors provide a practical example of how it is possible to decouple the activation pressure and the pressure gradient across the valve through a 3–key component system. In this new shunt design, the flow is expected to depend only on the intracranial pressure and not on the pressure gradient across the valve, thus avoiding the so-called siphoning effect. Methods The authors used computer models to theoretically evaluate the mechanical variables involved in the operation of the newly designed valve, such as the fluid's Reynolds number, proximal pressure, distal pressure, pressure gradient, actual flow rate, and expected flow rate. After fabrication of the first superscaled model, the authors performed benchmark tests to analyze the performance of the new shunt prototype, and the obtained data were compared with the results predicted by the previous mathematical models. Results The final design of the new paddle wheel valve with the 3–key component antisiphoning system was tested in the hydrodynamics laboratory to prove that the siphoning effect did not occur. According to the calculations obtained using the LabVIEW program during the experiments, each time the distal pressure decreased without an increase in the proximal pressure (despite the range of the pressure gradient), the pin blocked the spinning of the paddle wheels, and the calculated fluid velocity through the system tended to zero. Such a situation was significantly different from the expected flow rate for such a pressure gradient in a siphoning situation without the new antisiphon system. Conclusions The design of this new prototype with a 3–key component antisiphoning system demonstrated that it is possible to decouple the activation pressure and the pressure gradient across the valve, avoiding the siphoning effect. Although further developments are necessary to provide a model compatible to clinical use, the authors believe that this new prototype illustrates the possibility of successfully addressing the siphoning effect by using a simple 3–key component system that is able to decouple the activation pressure and the pressure gradient across the valve by using a separate pressure chamber. It is expected that such proof of concept may significantly contribute to future shunt designs attempting to address the problem of overdrainage due to the siphoning effect.

Experimental Study of the Influence of Roughness Change in a Piping on the Flow Measurement

2009 ◽  
Author(s):  
Yoshihisa Nishi ◽  
Yuzuru Eguchi ◽  
Takashi Nishihara ◽  
Izumi Kinoshita ◽  
Fumio Inada ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Flow Rate ◽  
Circular Cross Section ◽  
Ultrasonic Flowmeter ◽  
Bias Error ◽  
High Precision Measurement ◽  
Roughness Change ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
The Difference

In measurement of an ultrasonic flowmeter, the flow rate in piping is obtained using some measurement signals along the “chord” of the circular cross section of the piping. As for the “Chordal type ultrasonic flowmeter”, the flow rate is obtained by four (or eight) “chords”. The wall roughness influences the velocity profile. To evaluate the influences of roughness change on the measurement using four velocity points, a water test was performed. The Reynolds (Re) number of the test ranges from 4×105 to 3×106. It was suggested that high precision measurement in the range of high Re number can be expected in the smooth pipe. In the wall where sand of 0.1mm diameter was pasted, no difference in the velocity profile with the smooth wall was observed. A change in the velocity profiles appeared in the rough surface pipe where sands of 0.6mm and 0.2mm diameter has been pasted. Bias error (ESL) was used to estimate the uncertainty of the flow rate measurements using four velocity points. The difference of each ESL value based on the influence of roughness tended to diminish as the Re number increased. And the Re number dependency of ESL is small, especially in the high Re number side. It suggests that an actual flow rate test for the high Re number to confirm the influence of roughness would not be necessary.

scholarly journals Indirect estimation of the production rate of wells with low flow rate

2021 ◽  
Vol 2094 (5) ◽  
pp. 052004
Author(s):  
S V Svetlakova ◽  
A N Krasnov ◽  
M Yu Prakhova
Keyword(s):  
Flow Rate ◽  
Low Flow ◽  
Regression Equations ◽  
Flow Meters ◽  
Sucker Rod ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
Equipment State ◽  
Pumping Equipment ◽  
Pumping Units

Abstract The problem of measuring the flow rate of wells with low production rates is relevant for many oil fields. Conventional flow meters are not suitable for such cases, and installing an additional flow meter for each well is impractical. At the same time, wells with sucker-rod pumping units (the majority of wells) are outfitted with dynamographs for continuous diagnostics of the pumping equipment state. Dynamograms allow determining the theoretical flow rate of the well easily, however, a mathematical model is required to estimate the actual flow rate. For the correction of flow rate obtained from dynamograms, the authors of this study propose using models based on regression equations that link the calculated valueswith the measurements made by a reference instrument. The results of the experiments have confirmed the eligibility of this approach.

Effect of Formula Type and Preparation on International Dysphagia Diet Standardisation Initiative Thickness Level and Milk Flow Rates From Bottle Teats

2021 ◽  
Vol 30 (1) ◽  
pp. 260-265
Author(s):  
Britt F. Pados ◽  
Victoria Feaster
Keyword(s):  
Gastroesophageal Reflux ◽  
Infant Formula ◽  
Flow Rate ◽  
Infant Formulas ◽  
Testing Methods ◽  
Flow Rates ◽  
Milk Flow ◽  
Thin Liquids ◽  
The Impact ◽  
Formula Type

Purpose The purpose of this study was to evaluate the effect of infant formula type and preparation (i.e., ready-to-feed vs. powder) on International Dysphagia Diet Standardisation Initiative (IDDSI) thickness level and milk flow rates from bottle teats/nipples. Method The ready-to-feed and powder formulations of the following products were tested for IDDSI thickness level, using IDDSI guidelines, and for milk flow rate, using established flow testing methods: Similac Advance, Similac For Spit-Up, Enfamil Infant, and Enfamil A.R. Analysis of variance was used to compare flow rates among formula types/preparations. Results Enfamil A.R. ready-to-feed was classified as IDDSI “slightly thick.” All other formula types/preparations were found to be IDDSI “thin” liquids. The standard infant formulas (Similac Advance and Enfamil Infant) had comparable flow rates to each other, regardless of preparation (ready-to-feed and powder). The gastroesophageal reflux–specific formulas (Similac For Spit-Up and Enfamil A.R.) had slower flow rates than the standard formulas; within this category, there were significant differences in flow rates between ready-to-feed and powder. Enfamil A.R. powder had the slowest flow rate, but was the most variable. Conclusion For infants with difficulty coordinating sucking, swallowing, and breathing, clinicians and parents should consider the impact that changes to infant formula type and preparation may have on the infant's ability to safely feed.

Assessment of the impact of water parameters on the flow rate of ceramic pot filters in a long-term experiment

2015 ◽  
Vol 15 (6) ◽  
pp. 1425-1432 ◽  
Author(s):  
C. Salvinelli ◽  
A. C. Elmore
Keyword(s):  
Flow Rate ◽  
Water Production ◽  
Premature Failure ◽  
Initial Flow ◽  
Flow Rates ◽  
Treated Water ◽  
Long Term Study ◽  
The Impact ◽  
The Relationship

Poor water quality is a major contributing factor to disease in developing countries. Silver-coated ceramic pot filters (CPFs) are a relatively common form of household water treatment system (HWTS) representing an effective and sustainable technology for poor communities. Water production seems to be the major limiting factor of the CPF's lifetime and sustainability since low flow rates do not produce an adequate daily volume of treated water. This paper describes a long-term study of CPF flow rates under controlled conditions using three different water sources. The relationship between water characteristics and flow rate was assessed with the intent of identifying the principal parameters that impact CPF water production. The study concluded that turbidity seems to be the principal indicator in determining CPF lifetime in terms of quantity of treated water. There is no evidence that biological activity also contributes to premature failure of CPFs and the data did not indicate that chemical precipitation is responsible for the filter clogging. Manufacturers commonly conduct initial flow rate tests using clear water as a measure of quality assurance. However, the relationship between initial flow rate and average flow rate during the lifetime of the CPF should be further studied.

scholarly journals The effect of reduction of perfusion rate on lactate and oxygen uptake, glucose output and energy supply in the isolated perfused liver of starved rats

1979 ◽  
Vol 184 (3) ◽  
pp. 635-642 ◽  
Author(s):  
R A Iles ◽  
P G Baron ◽  
R D Cohen
Keyword(s):  
Oxygen Uptake ◽  
Flow Rate ◽  
Mean Value ◽  
Normal Flow ◽  
Perfusion Rate ◽  
Flow Rates ◽  
Perfusate Flow ◽  
Intrinsic Capacity ◽  
Lactate Uptake ◽  
Glucose Output

1. Lactate and O2 uptake and glucose output were studied in isolated livers from starved rats at perfusate flow rates varying from 100 to 7% of “normal” (11.25-0.75 ml/min per 100 g body wt.). 2. With moderate diminution of flow rate, lactate and oxygen uptake fell more slowly than would be expected if uptake purely depended on substrate supply. 3. Use of a mathematical model suggests that the intrinsic capacity of the liver for lactate uptake is unaffected until the flow rate falls below 25% of “normal”. 4. Some lactate uptake was always observed even at 7% of the “normal” flow rate. 5. At flow rates below 33% of the “normal”, lactate was increasingly metabolized by pathways other than gluconeogenesis, which became a progressively less important consumer of available O2. 6. ATP content decreased with diminution of flow rate, but substantially less markedly than did lactate uptake and glucose output. 7. Intracellular pH fell from a mean value of 7.25 at “normal” flow rate to 7.03 at 7% of the “normal” flow rate.

Experimental Study on Discharge Coefficients of Windward Window in Buildings with Wind-Driven Cross Ventilation

2014 ◽  
Vol 1008-1009 ◽  
pp. 1061-1067
Author(s):  
Qiao Ning Wang ◽  
Yan Ling Guan ◽  
Qi Hai Liao
Keyword(s):  
Flow Rate ◽  
Natural Ventilation ◽  
Discharge Coefficient ◽  
Static Pressure ◽  
Flow Rates ◽  
Discharge Coefficients ◽  
Window Opening ◽  
Static Pressure Difference ◽  
Window Area ◽  
The Impact

Focus on the prediction of flow rates in buildings under natural ventilation, the investigation conducted a series of model rooms with cross ventilation. The impact of window-wall ratios, windows configurations as well as corresponding flow rates was investigated. The object of this investigation is to analyze characteristics of windward window opening discharge coefficient by measuring static pressure difference and the flow rate through windows. The conclusion are as follows: For large openings, the discharge coefficient of windward window opening increases as the window-wall ratio grows up; With windward window-wall ratio of 44.4% and 11.1%, the discharge coefficient of windward openings is almost irrelevant to flow rate and less affected by leeward window area; However, with windward window-wall ratio of 2.78%, the discharge coefficient increases slightly as flow rate rises, and the larger the area of leeward opening is, the smaller the discharge coefficient of windward opening becomes.

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