Comment on ACP-2017-658 “Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis”

2017 ◽  
Author(s):  
Anonymous
Keyword(s):  
Growth Rate ◽  
Time Dependent ◽  
Growth Mechanisms ◽  
Nanoparticle Growth ◽  
Rate Analysis ◽  
Dependent Growth

scholarly journals Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

2017 ◽  
Author(s):  
Lukas Pichelstorfer ◽  
Dominik Stolzenburg ◽  
John Ortega ◽  
Thomas Karl ◽  
Harri Kokkola ◽  
...  
Keyword(s):  
Growth Rates ◽  
Particle Formation ◽  
Cloud Microphysics ◽  
Growth Mechanisms ◽  
Nanoparticle Growth ◽  
Rate Analysis ◽  
Cloud Properties ◽  
General Dynamics ◽  
Dependent Growth ◽  
Physical And Chemical

Abstract. Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

scholarly journals Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

2018 ◽  
Vol 18 (2) ◽  
pp. 1307-1323 ◽  
Author(s):  
Lukas Pichelstorfer ◽  
Dominik Stolzenburg ◽  
John Ortega ◽  
Thomas Karl ◽  
Harri Kokkola ◽  
...  
Keyword(s):  
Growth Rates ◽  
Particle Formation ◽  
Cloud Microphysics ◽  
Growth Mechanisms ◽  
Nanoparticle Growth ◽  
Rate Analysis ◽  
Cloud Properties ◽  
General Dynamics ◽  
Dependent Growth ◽  
Physical And Chemical

Abstract. Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

scholarly journals Inferring time-dependent population growth rates in cell cultures undergoing adaptation

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
H. Jonathan G. Lindström ◽  
Ran Friedman
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Growth Rates ◽  
Time Dependent ◽  
Cell Counting ◽  
Suspension Cells ◽  
Population Growth Rates ◽  
Cell Counts ◽  
Dependent Growth ◽  
Using Data

Abstract Background The population growth rate is an important characteristic of any cell culture. During sustained experiments, the growth rate may vary due to competition or adaptation. For instance, in presence of a toxin or a drug, an increasing growth rate indicates that the cells adapt and become resistant. Consequently, time-dependent growth rates are fundamental to follow on the adaptation of cells to a changing evolutionary landscape. However, as there are no tools to calculate the time-dependent growth rate directly by cell counting, it is common to use only end point measurements of growth rather than tracking the growth rate continuously. Results We present a computer program for inferring the growth rate over time in suspension cells using nothing but cell counts, which can be measured non-destructively. The program was tested on simulated and experimental data. Changes were observed in the initial and absolute growth rates, betraying resistance and adaptation. Conclusions For experiments where adaptation is expected to occur over a longer time, our method provides a means of tracking growth rates using data that is normally collected anyhow for monitoring purposes. The program and its documentation are freely available at https://github.com/Sandalmoth/ratrack under the permissive zlib license.

Experimental observation of viscoelastic fluid–structure interactions

2017 ◽  
Vol 813 ◽  
Author(s):  
Anita A. Dey ◽  
Yahya Modarres-Sadeghi ◽  
Jonathan P. Rothstein
Keyword(s):  
Flow Instability ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Flexible Structure ◽  
Fluid Inertia ◽  
Fluid Structure Interactions ◽  
Periodic Oscillations ◽  
Fluid Structure ◽  
Dependent Growth ◽  
First Time

It is well known that when a flexible or flexibly mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices. Here, we show for the first time that fluid–structure interactions can also be observed when the fluid is viscoelastic. For viscoelastic fluids, a flexible structure can become unstable in the absence of fluid inertia, at infinitesimal Reynolds numbers, due to the onset of a purely elastic flow instability. Nonlinear periodic oscillations of the flexible structure are observed and found to be coupled to the time-dependent growth and decay of viscoelastic stresses in the wake of the structure.

scholarly journals Time-dependent growth of crystalline Au0-nanoparticles in cyanobacteria as self-reproducing bioreactors: 2.Anabaena cylindrica

2016 ◽  
Vol 7 ◽  
pp. 312-327 ◽  
Author(s):  
Liz M Rösken ◽  
Felix Cappel ◽  
Susanne Körsten ◽  
Christian B Fischer ◽  
Andreas Schönleber ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Production Method ◽  
Wide Distribution ◽  
Time Dependent ◽  
Anabaena Cylindrica ◽  
Vegetative Cells ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Dependent Growth ◽  
Average Size

Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability as an extremely environmentally friendly production method in the last few years, even though the separation of the nanoparticles is challenging. Biosynthesis, summing up biosorption and bioreduction of diluted metal ions to zero valent metals, is especially ecofriendly, when the bioreactor itself is harmless and needs no further harmful reagents. The cyanobacteriumAnabaena cylindrica(SAG 1403.2) is able to form crystalline Au0-nanoparticles from Au3+ions and does not release toxic anatoxin-a. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and laser-induced breakdown spectroscopy (LIBS) are applied to monitor the time-dependent development of gold nanoparticles for up to 40 hours. Some vegetative cells (VC) are filled with nanoparticles within minutes, while the extracellular polymeric substances (EPS) of vegetative cells and the heterocyst polysaccharide layer (HEP) are the regions, where the first nanoparticles are detected on most other cells. The uptake of gold starts immediately after incubation and within four hours the average size remains constant around 10 nm. Analyzing the TEM images with an image processing program reveals a wide distribution for the diameter of the nanoparticles at all times and in all regions of the cyanobacteria. Finally, the nanoparticle concentration in vegetative cells ofAnabaena cylindricais about 50% higher than in heterocysts (HC). These nanoparticles are found to be located along the thylakoid membranes.

Consistent patterns of maturity and density-dependent growth among populations of walleye (Sander vitreus): application of the growing degree-day metric

2010 ◽  
Vol 67 (7) ◽  
pp. 1057-1067 ◽  
Author(s):  
Paul A. Venturelli ◽  
Nigel P. Lester ◽  
Terry R. Marshall ◽  
Brian J. Shuter
Keyword(s):  
Growth Rate ◽  
Explanatory Power ◽  
Management Strategies ◽  
Fold Increase ◽  
Fish Growth ◽  
Growing Degree Days ◽  
Sander Vitreus ◽  
Degree Days ◽  
Regional Management ◽  
Dependent Growth

Growing degree-days (GDD, °C·days) are an index of ambient thermal energy that relates directly to an ectotherm’s cumulative metabolism but is rarely used to describe growth and development in fish. We applied GDD to length and maturity data from 416 populations of walleye ( Sander vitreus ) from Ontario and Quebec, Canada (mean annual GDD = 1200 to 2300 °C·days). On average, males matured after they had experienced 6900 °C·days and reached 350 mm total length (L) (n = 77 populations), and females matured after 10 000 °C·days and at 450 mm L (n = 70). Across 143 populations, GDD accounted for up to 96% of the variation in the length of immature walleye but also revealed a twofold difference in growth rate that was indicative of variation in food availability. When applied to data from eight populations in which walleye abundances have changed dramatically over time, GDD revealed a 1.3-fold increase in immature growth rate when abundance was low compared with when it was high. Our results both demonstrate the explanatory power of GDD with respect to fish growth and maturity and inform the development of regional management strategies for walleye.

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