Effect of aluminum on potassium uptake by red spruce seedlings

1985 ◽  
Vol 63 (6) ◽  
pp. 1099-1103 ◽  
Author(s):  
J. R. Cumming ◽  
R. T. Eckert ◽  
L. S. Evans
Keyword(s):  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Nonlinear Least Squares ◽  
Potassium Uptake ◽  
Red Spruce ◽  
Physiological Changes ◽  
Absorption Data ◽  
Aluminum Exposure ◽  
Initial Decrease ◽  
Seedling Roots

Potassium uptake by roots of intact red spruce seedlings exposed to 0, 1, and 4 mg∙L−1 Al3+ was determined using kinetic analysis. Uptake parameters Vmax and Km were estimated by nonlinear least-squares analysis of K+ absorption data fitted to a combined active and linear uptake model. Roots treated with 1 mg∙L−1 Al exhibited enhanced potassium uptake for up to 72 h of aluminum exposure. K+ uptake in the presence of 4 mg∙L−1 Al also increased but was influenced by the duration of exposure to Al in solution. Comparison of kinetic parameters revealed an increase in Vmax in roots treated with aluminum. Km in both 1 and 4 mg∙L−1 aluminum treatments varied consistently with duration of exposure, characterized by an initial decrease in apparent carrier-site affinity followed by Km values trending toward control levels. These changes are hypothesized to result from a combination of physical and physiological changes in red spruce seedling roots induced by Al3+ in solution.

Kinetics of potassium uptake in red spruce seedlings

1985 ◽  
Vol 63 (3) ◽  
pp. 512-516
Author(s):  
J. R. Cumming ◽  
R. T. Eckert ◽  
L. S. Evans
Keyword(s):  
Nonlinear Least Squares ◽  
Theoretical Models ◽  
Potassium Uptake ◽  
Red Spruce ◽  
Saturation Kinetics ◽  
Potassium Absorption ◽  
Parameter Values ◽  
Kinetics Of ◽  
Diffusive Component ◽  
Nutrient Solutions

Potassium uptake by roots of 3-week-old red spruce (Picea rubens Sarg.) seedlings was measured in nutrient solutions ranging in K+ concentration from 0.01 to 10.0 mM. Nonlinear least squares analysis was used to estimate uptake parameters Vmax and Km. Analyses of residuals generated by several theoretical models of ion uptake were undertaken to choose the best mechanistic uptake model. Potassium absorption by red spruce seedlings was characterized by Michaelis–Menten behavior from K+ solutions in the range 0.01 to 1.0 mM. Above 1.0 mM, accumulation of potassium was most readily accounted for by a linear diffusive component superimposed on saturation kinetics. Uptake parameter values of Vmax = 1.17 μmol K∙g fresh weight−1∙h−1 and Km = 0.083 mM were similar to those reported for other species. The culture of seedlings in full-strength nutrient solution did not reduce the ability to resolve these uptake parameters in short-term experiments.

scholarly journals Biomechanics of Gait during Pregnancy

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Marco Branco ◽  
Rita Santos-Rocha ◽  
Filomena Vieira
Keyword(s):  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Musculoskeletal System ◽  
Postpartum Period ◽  
Kinematic Analysis ◽  
Morphological Changes ◽  
Physiological Changes ◽  
Hormonal System ◽  
Biomechanical Changes

Introduction. During pregnancy women experience several changes in the body’s physiology, morphology, and hormonal system. These changes may affect the balance and body stability and can cause discomfort and pain. The adaptations of the musculoskeletal system due to morphological changes during pregnancy are not fully understood. Few studies clarify the biomechanical changes of gait that occur during pregnancy and in postpartum period.Purposes. The purpose of this review was to analyze the available evidence on the biomechanical adaptations of gait that occur throughout pregnancy and in postpartum period, specifically with regard to the temporal, spatial, kinematic, and kinetic parameters of gait.Methods. Three databases were searched and 9 studies with a follow-up design were retrieved for analysis.Results. Most studies performed temporal, spatial, and kinematic analysis. Only three studies performed kinetic analysis.Conclusion. The adaptation strategies to the anatomical and physiological changes throughout pregnancy are still unclear, particularly in a longitudinal perspective and regarding kinetic parameters.

Effect of interbreath fluctuations on characterizing exercise gas exchange kinetics

1987 ◽  
Vol 62 (5) ◽  
pp. 2003-2012 ◽  
Author(s):  
N. Lamarra ◽  
B. J. Whipp ◽  
S. A. Ward ◽  
K. Wasserman
Keyword(s):  
Gas Exchange ◽  
Least Squares ◽  
Kinetic Parameters ◽  
Nonlinear Least Squares ◽  
Cycle Ergometer ◽  
Gaussian Stochastic Process ◽  
Co2 Output ◽  
Nonsteady State ◽  
Exchange Kinetics ◽  
Gas Exchange Kinetics

Breathing has inherent irregularities that produce breath-to-breath fluctuations (“noise”) in pulmonary gas exchange. These impair the precision of characterizing nonsteady-state gas exchange kinetics during exercise. We quantified the effects of this noise on the confidence of estimating kinetic parameters of the underlying physiological responses and hence of model discrimination. Five subjects each performed eight transitions from 0 to 100 W on a cycle ergometer. Ventilation, CO2 output, and O2 uptake were computed breath by breath. The eight responses were interpolated uniformly, time aligned, and averaged for each subject; and the kinetic parameters of a first-order model (i.e., the time constant and time delay) were then estimated using three methods: linear least squares, nonlinear least squares, and maximum likelihood. The breath-by-breath noise approximated an uncorrelated Gaussian stochastic process, with a standard deviation that was largely independent of metabolic rate. An expression has therefore been derived for the number of square-wave repetitions required for a specified parameter confidence using methods b and c; method a being less appropriate for parameter estimation of noisy gas exchange kinetics.

scholarly journals An alternative approach to kinetic analysis of temperature-programmed reaction data

RSC Advances ◽  
2018 ◽  
Vol 8 (6) ◽  
pp. 3286-3295 ◽  
Author(s):  
A. S. Portnyagin ◽  
A. P. Golikov ◽  
V. A. Drozd ◽  
V. A. Avramenko
Keyword(s):  
Particle Size ◽  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Isothermal Reaction ◽  
Alternative Approach ◽  
Reaction Data ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

Presented method of kinetic analysis of non-isothermal reaction data provides precise kinetic parameters for different materials with different morphology and particle size.

scholarly journals A new laser-based and ultra-portable gas sensor for indoor and outdoor formaldehyde (HCHO) monitoring

2019 ◽  
Vol 12 (11) ◽  
pp. 6079-6089 ◽  
Author(s):  
Joshua D. Shutter ◽  
Norton T. Allen ◽  
Thomas F. Hanisco ◽  
Glenn M. Wolfe ◽  
Jason M. St. Clair ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Limit Of Detection ◽  
Nonlinear Least Squares ◽  
Ambient Air ◽  
Post Processing ◽  
Absorption Data ◽  
Mixing Ratios ◽  
Outdoor Environments ◽  
Indoor And Outdoor Environments ◽  
Indoor And Outdoor

Abstract. In this work, a new commercially available, laser-based, and ultra-portable formaldehyde (HCHO) gas sensor is characterized, and its usefulness for monitoring HCHO mixing ratios in both indoor and outdoor environments is assessed. Stepped calibrations and intercomparison with well-established laser-induced fluorescence (LIF) instrumentation allow a performance evaluation of the absorption-based, mid-infrared HCHO sensor from Aeris Technologies, Inc. The Aeris sensor displays linear behavior (R2 > 0.940) when compared with LIF instruments from Harvard and NASA Goddard. A nonlinear least-squares fitting algorithm developed independently of the sensor's manufacturer to fit the sensor's raw absorption data during post-processing further improves instrument performance. The 3σ limit of detection (LOD) for 2, 15, and 60 min integration times are 2190, 690, and 420 pptv HCHO, respectively, for mixing ratios reported in real time, though the LOD improves to 1800, 570, and 300 pptv HCHO, respectively, during post-processing. Moreover, the accuracy of the sensor was found to be ± (10 % + 0.3) ppbv when compared against LIF instrumentation sampling ambient air. The aforementioned precision and level of accuracy are sufficient for most HCHO levels measured in indoor and outdoor environments. While the compact Aeris sensor is currently not a replacement for the most sensitive research-grade instrumentation available, its usefulness for monitoring HCHO is clearly demonstrated.

Kinetic Analysis on SiC Prepared by Carbothermic Method

2012 ◽  
Vol 550-553 ◽  
pp. 2745-2748
Author(s):  
Bin Hao ◽  
Jin Qiang Liu ◽  
Fu Wang
Keyword(s):  
Silicon Carbide ◽  
Reaction Time ◽  
Dynamic Analysis ◽  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Particle Diameter ◽  
Thermal Reduction ◽  
Different Temperatures ◽  
Time Required

Kinetic analysis of silicon carbide prepared by carbon-thermal reduction is introduced in this paper. Through the dynamic analysis, kinetic parameters of Si-C are calculated, and it is estimated that the time required reaction materials of different diameter completely converted to SiC at different temperatures. Reaction time is nearly 1 hour long when the reaction particle diameter is 1μm around 1900K.

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