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Research
Development of a High Pressure Automated Lag Time Apparatus (HP-ALTA) for Experimental Studies and Statistical Analyses of Nucleation and Growth of Gas Hydrates (download pdf)
Nobuo Maeda, Darrell Wells, Norman Becker, Patrick Hartley, Peter W. Wilson, A.D.J. Haymet, and Karen Kozielski
Review of Scientific Instruments #A110345R
ABSTRACT:
Nucleation in a supercooled or a supersaturated medium is a stochastic event, and hence statistical analyses are required for the understanding and prediction of such events. The development of reliable statistical methods for quantifying nucleation probability is highly desirable for applications where control of nucleation is required. The nucleation of gas hydrates in supercooled conditions is one such application. We describe the design and development of a High Pressure Automatic Lag Time Apparatus (HP-ALTA) for the statistical study of gas hydrate nucleation and growth at elevated gas pressures. The apparatus allows a small volume (≈ 150μl) of water to be cooled at a controlled rate in a pressurised gas atmosphere, and the temperature of gas hydrate nucleation, Tf , to be detected. The instrument then raises the sample temperature under controlled conditions to facilitate dissociation of the gas hydrate before repeating the cooling-nucleation cycle again. This process of forming and dissociating gas hydrates can be automatically repeated for a statistically significant (>100) number of nucleation events. The HP-ALTA can be operated in two modes, one for the detection of hydrate in the bulk of the sample, under a stirring action, and the other for the detection of the formation of hydrate films across the water-gas interface of a quiescent sample. The technique can be applied to the study of several parameters, such as gas pressure, cooling rate and gas composition, on the gas hydrate nucleation probability distribution for supercooled water samples.
P.W. Wilson, Katie E. Osterday, Aaron F. Heneghan, and A.D.J. Haymet
Journal of Biological Chemistry, first published September 13, 2010, DOI: 10.1074/jbc.M110.171983, 285, pp 34741-34745
ABSTRACT:  
This paper examines the effects antifreeze proteins (AFPs) have on the supercooling and ice nucleating abilities of aqueous solutions. Very little information on such nucleation currently exists. Using an automated lag time apparatus (ALTA) and a new analysis, we show several dilution series of Type 1 AFPs. Our results indicate that above a concentration of about 8 mg.ml-1 ice nucleation is enhanced rather than hindered. We discuss this unexpected result and present a new hypothesis outlining three components of polar fish blood that we believe affect its solution properties in certain situations.
P.W. Wilson and A.D.J. Haymet
Journal of Physical Chemistry, DOI: 10.1021/jp105001c, 114 (39), pp 12585-12588
ABSTRACT:
 Workman Reynolds freezing potentials have been measured across the interface between ice and dilute NaCl solutions as a function of ice growth rate for three salt concentrations. Growth rates of up to 40 μm.s-1 are used and it is found that the measured voltage peaks at rates of about ~25 μm.s-1. Our initial results indicate that the freezing potential can be used as a probe into various aspects of the DC electrical resistance of ice as a function of variables such as salt concentration.
Hydrate Formation and Re-formation in Nucleating THF/Water Mixtures Show No Evidence to Support a 'Memory' Effect
P.W. Wilson and A.D.J. Haymet
Chemical Engineering Journal, Available online 2 May 2010, ISSN 1385-8947, DOI: 10.1016/j.cej.2010.04.047
ABSTRACT:
 
There are many reports in the chemical engineering literature citing a
`memory' effect in association with nucleation of clathrate hydrates.
Some researchers appeal to this memory effect in order to explain the
apparent reduction in induction time for hydrates formed repetitively
from supercooled solutions. It is suggested that for various species of
clathrate in liquid-liquid or gas-liquid systems, such as THF/water,
CO2/water and hydrocarbon gas/water, the `memory' effect results from
water which is obtained from melted hydrates possessing a 'modified'
structure which allows easier hydrate re-formation. We provide here data
from several series of measurements of the stochastic nature of
THF-water hydrate formation using an automatic lag time apparatus. Our
data supports the existing molecular understanding of nucleation and
does not require any appeal to a memory effect. Keywords: Heterogeneous;
Nucleation; Clathrate; ALTA
The Effects of Electric Field on Ice Nucleation May Be Masked by the Inherent Stochastic Nature of Nucleation
P.W. Wilson, Katie Osterday, and A.D.J. Haymet
CryoLetters 2009 30, 2 (March) ISSN 0143-2044
ABSTRACT:
We use an automatic lag time apparatus to show that electric fields of 50,000 Volts per meter have no effect on the nucleation of supercooled water. Any previously perceived effect at similar, small magnitude, fields is likely due to the inherent stochastic nature of the liquid to solid transition.
Workman Reynolds Freezing Potential Measurements between Ice and Dilute Salt Solutions for Single Ice Crystal Faces
P.W. Wilson and A.D.J. Haymet
J. Phys Chem. B, 2008, 112 (37), pp 11750-11755
Publication Date (Web): August 23, 2008 (Article)
DOI: 10.1021/jp804047x
ABSTRACT:
Workman Reynolds freezing potentials have been measured for the first time across the interface between single crystals of ice 1h and dilute electrolyte solutions. The measured electric potential is a strictly non-equilibrium phenomenon, and is a function of concentration of salt, freezing rate, orientation of the ice crystal and time. When all these factors are controlled, the voltage is reproducible to the extent expected with ice growth experiments. Zero voltage is obtained with no growth or melting. For rapidly grown ice 1h basal plane in contact with a solution of 10-4 M NaCl the maximum voltage exceeds 30 Volts, and decreases to zero at both high and low salt concentrations. These single crystal experiments explain much of the data captured on this remarkable phenomenon since the year 1948.
Comment on “Workman−Reynolds Freezing Potential Measurements between Ice and Dilute Salt Solutions for Single Ice Crystal Faces”
P. W. Wilson and A. D. J. Haymet
J. Phys. Chem. B, 2008, 112 (47), p 15260
Publication Date (Web): October 29, 2008
DOI: 10.1021/jp807642s
ABSTRACT:
In 1948, Workman and Reynolds discovered that an electric charge separation occurs during freezing of slightly ionized water. Several workers have since shown that when very dilute solutions of particular salts such as NaCl, KCl, and NH4Cl freeze relatively rapidly, a strong but transient potential difference of up to several hundred volts is established between the solid and liquid phases. This electric charge separation is commonly referred to as the Workman-Reynolds effect, or freezing potential. We have recently repeated many of those measurements. Basically, we find with dilute aqueous solutions that measured voltages are sensitive to salt species, salt concentration, ice growth rate, ice crystal face, and the external load resistance of the measuring device. Here, we now report the markedly different effect which is seen when hydrates are grown.
Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008)
Vancouver, British Columbia, Canada, July 6-10, 2008
P.W. Wilson and A.D.J. Haymet, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA
ABSTRACT:
The statistics of liquid-to-crystal nucleation are measured for clathrate-forming mixtures of tetrahydrofuran and water using an automatic lag time apparatus (ALTA). We measure the nucleatio temperature where a single sample is repeatedly cooled, nucleated and thawed. This is done for a series of tetrahydrofuran concentrations and in several different sample tubes since the nucleation is heterogeneous and occurring on the tube wall. The measurements are also done at the same concentrations and tubes but with an added catalyst, a single crystal of silver iodide. We discuss the need for this type of measurement if the true nucleation temperature of the clathrate is to be found. Comparisons are also made with our high pressure data on real-world clathrate formers.
Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008)
Vancouver, British Columbia, CANADA, July 6-10, 2008
K. A. Kozielskski∗, N. C. Becker & P. G. Hartley, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Division of Molecular and Health Technologies, Bayview Avenue, Clayton, VIC 3169, Australia
P. W. Wilson & A. D. J. Haymet, Scripps Institution of Oceanography, 8602 La Jolla Shores Drive, CA 92037, USA
R. Gudimetla & A. L. Ballard, BP America Production Company, 501 West Lake Park Boulevard, Houston, TX 77079, USA
R. Kini, Chevron Energy Technology Company,1600 Smith St. Houston, Texas 77002, USA
ABSTRACT:
Nucleation is a stochastic process, most accurately represented by a probability distribution. Obtaining sufficient data to define this probability distribution is a laborious process. Here, we describe a novel instrument capable of the automated determination of hydrate nucleation probability under non-equilibrium conditions for a range of natural gas mixtures at pressures up to 10MPa. The instrument is based on the automated lag time apparatus (ALTA) which was developed to study the stochastic nature of nucleation in ambient pressure systems [1].We demonstrate that the probability distribution represents a robust and reproducible tool for the quantitative evaluation of hydrate formation risk under pseudo-realistic pressure conditions. We also describe use of the instrument to evaluate factors affecting nucleation, including pressure, cooling rate, impurities and chemical additives and conclude that it is an effective method for evaluating even subtle changes to the environment in which the hydrates are formed.
Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008)
Vancouver, British Columbia, CANADA, July 6-10, 2008
P.W. Wilson and A.D.J. Haymet, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA
K.A. Kozielski, P. Hartley & N.C. Becker, CSIRO Molecular & Health Technologies,Ian Wark Laboratory, Clayton, Victoria 3150, Australia.
ABSTRACT:
The liquid-to-crystal nucleation temperature is measured for clathrate-forming mixtures of tetrahydrofuran and water using both an automatic lag time apparatus (ALTA) and a ball screening apparatus. Our results are conclusive evidence that no so-called “memory effect” exists. Either the solid form melts fully or it does not. If it does not, then no supercooling is possible on the next cooling down of that sample, and if it does then the second cooling run and freezing on a sample is just as likely to have a colder nucleation temperature as a hotter one.
American Chemical Society Meeting,
Park City, Utah, June 15-18, 2008
New Measurements of the Workman-Reynolds Freezing Potential Between Ice and Dilute Salt Solutions, for Both Polycrystalline Ice and Single Ice Crystal Faces
P.W. Wilson and A.D.J. Haymet, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA
ABSTRACT:
We have measured the so-called Workman-Reynolds or Freezing Potential between polycrystalline ice and dilute salt solutions. We have also used single ice crystals with various faces as the ice / salt water boundary. These measurements are done as a function of concentration, freezing rate and salt species in order to fully understand the preferential exclusion of ions from ice. This concept is claimed to play a crucial role in many diverse phenomena including thunderstorms and the biology of cold tolerance and avoidance.
Biophysical Journal 2007; 93:1442-1451
Antifreeze Proteins at the Ice/Water Interface: Three Calculated Discriminating Properties for Orientation of Type I Proteins
ABSTRACT:
The number of hydrogen bond count, for example; and the sidechain
Antifreeze proteins (AFPs protect many plants and organisms from
freezing in low temperatures. Of the different AFPs, the most studied
AFP Type I from winter flounder is used in
the current computational studies to gain molecular insight into its
adsorption at the ice/water interface. Employing molecular dynamics
simulations, we calculate the free energy difference between the hydrophilic
and hydrophobic faces of the protein interacting with ice. Furthermore, we
identify three properties of Type I "antifreeze" proteins that discriminate
among these two orientations of the protein at the ice/water interface. The
three properties are: the "surface area" of the protein; a measure of the
interaction of the protein with neighboring water molecules as determined by
orientation angles of the threonine residues. All three discriminants are consistent with our free energy results which clearly show that the hydrophilic protein face orientations towards the ice/water interface, as
hypothesized from experimental and ice/vacuum simulations, is incorrect, while supporting the hydrophobic protein face orienting towards the interface. The adsorption free energy is calculated to be 2-3 kJ/mol.
Read full abstract
234th ACS National Meeting,
Boston, MA, August 19-23, 2007
Division of Computers in Chemistry
Ions at Water Interfaces
A.D.J. Haymet, Scripps Institution of Oceanography, UC San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0210, Fax: 858-453-0167, haymet@ucsd.edu, and Taras Bryk, Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine
ABSTRACT:
The behavior of ions and molecules at the ice/gas and ice/water interfaces is a fundamental process encountered in a range of physical and biological systems and has relevance to unsolved problems in atmospheric chemistry, for example charge separation at the ice/water interfaces known as Workman-Reynolds effect. Recent studies on the behavior of Na+ and Cl- ions at the ice/water interface question the inherent (or induced) electrostatic potential at ice/water interfaces. Others have reported very thorough calculations on the electrostatic potential for water/vapor interfaces. Our results on free energy profiles for Na+ and Cl- ions across the basal ice/water interface indicate that the ice/water interface can function as a capacitor. Similar profiles have been calculated for Na+ and Cl- at the basal ice surface / vacuum interface. For each solute ion at the ice surface, the minimum in the free energy profiles is located in the top surface liquid-like layers.
234th ACS National Meeting,
Boston, MA, August 19-23, 2007
Division of Computers in Chemistry
Molecular Dynamics Simulations of Antifreeze Proteins at a Lipid/Water Interface
E. J. Smith, Math, Science and Healthcare, Kingwood College, 20000 Kingwood Dr, Kingwood, TX 77339, erica.j.smith@nhmccd.edu, Pranav Dalal, Schrodinger, Inc, Jeffry D. Madura, Department of Chemistry and Biochemistry, Center for Computational Sciences, Duquesne University, and ADJ Haymet, Scripps Institution of Oceanography, UC San Diego
ABSTRACT:
Antifreeze proteins (AFP's), found in certain fish, insects and plants, allow the host organism to survive in lower than the equilibrium freezing point of their blood and/or internal fluids via suppression of ice crystal growth and the protection of cell membranes from cold-induced damage. Using molecular dynamics simulation techniques, a solvated dimyristolyphosphatidylcholine (DMPC) lipid bilayer containing an AFP type I at the lipid/water interface was constructed, simulated and characterized at several temperatures (310, 295, 288 and 260 K). Lipid structural characteristics were monitored and all results agreed well with other lipid bilayer simulation and experimental data. The simulations performed at 260 K showed (i) a distinct broadening of the lipid headgroup distribution in the pure system that was not observed in the system containing the AFP and (ii) that the phosphate-nitrogen (P-N) tilt angle decreased for the pure solvated system but remained the same for the system containing the AFP.
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