Publications by authors named "Frederick Meyer"

16 Publications

  • Page 1 of 1

Quantitative Kinetic Model of CO Absorption in Aqueous Tertiary Amine Solvents.

J Chem Inf Model 2021 Mar 12. Epub 2021 Mar 12.

TOTAL SE, Total Exploration Production, Liquefied Natural Gas - Acid Gas Entity, CCUS R&D Program, 2 Place Jean Milier, 92078 Paris, France.

Aqueous tertiary amine solutions are increasingly used in industrial CO capture operations because they are more energy-efficient than primary or secondary amines and demonstrate higher CO absorption capacity. Yet, tertiary amine solutions have a significant drawback in that they tend to have lower CO absorption rates. To identify tertiary amines that absorb CO faster, it would be efficacious to have a quantitative and predictive model of the rate-controlling processes. Despite numerous attempts to date, this goal has been elusive. The present computational approach achieves this goal by focusing on the reaction of CO with OH forming HCO. The performance of the resulting model is demonstrated for a consistent experimental data set of the absorption rates of CO for 24 different aqueous tertiary amine solvents. The key to the new model's success is the manner in which the free energy barrier for the reaction of CO with OH is evaluated from the differences among the solvation free energies of CO, OH, and HCO, while the p of the amines controls the concentration of OH. These solvation energies are obtained from molecular dynamics simulations. The experimental value of the free energy of reaction of CO with pure water is combined with information about measured rates of absorption of CO in an aqueous amine solvent in order to calibrate the absorption rate model. This model achieves a relative accuracy better than 0.1 kJ mol for the free energies of activation for CO absorption in aqueous amine solutions and 0.07 g L min for the absorption rate of CO. Such high accuracies are necessary to predict the correct experimental ranking of CO absorption rates, thus providing a quantitative approach of practical interest.
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http://dx.doi.org/10.1021/acs.jcim.0c01386DOI Listing
March 2021

Kinetics of viscoelasticity in the electric double layer following steps in the electrode potential studied by a fast electrochemical quartz crystal microbalance (EQCM).

Analyst 2021 Apr 5;146(7):2160-2171. Epub 2021 Feb 5.

Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany.

Changes in the viscoelasticity of the electric double layer following steps in electrode potential were studied with an electrochemical quartz crystal microbalance (EQCM). The overtone scaling was the same as in gravimetry (-Δf/n≈ const with Δf the frequency shift and n the overtone order). Changes in half-bandwidth were smaller than changes in frequency. This Sauerbrey-type behaviour can be explained with either adsorption/desorption or with changes of the (Newtonian) viscosity of the diffuse double layer. While the QCM data alone cannot distinguish between these two processes, independent information supports the explanation in terms of double layer viscosity. Firstly, the magnitudes of the frequency response correlated with the expected changes of the viscosity-density product in the diffuse double layer. With regard to viscosity, these expectations are based on the viscosity B-coefficients as employed in the Jones-Dole equation. Expected changes in density were estimated from the densities of the respective salts. Secondly, the explanation in terms of liquid-like response matches the kinetic data. The response times of frequency and bandwidth were similar to the response times of the charge as determined with electrochemical impedance spectroscopy (EIS). Rearrangements in the Helmholtz layer should have been slower, given this layer's rigidity. Kinetic information obtained with a QCM can aid the understanding of processes at the electrode-electrolyte interface.
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http://dx.doi.org/10.1039/d0an01965hDOI Listing
April 2021

A Quartz Crystal Microbalance, Which Tracks Four Overtones in Parallel with a Time Resolution of 10 Milliseconds: Application to Inkjet Printing.

Sensors (Basel) 2020 Oct 20;20(20). Epub 2020 Oct 20.

Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany.

A quartz crystal microbalance (QCM) is described, which simultaneously determines resonance frequency and bandwidth on four different overtones. The time resolution is 10 milliseconds. This fast, multi-overtone QCM is based on multi-frequency lockin amplification. Synchronous interrogation of overtones is needed, when the sample changes quickly and when information on the sample is to be extracted from the comparison between overtones. The application example is thermal inkjet-printing. At impact, the resonance frequencies change over a time shorter than 10 milliseconds. There is a further increase in the contact area, evidenced by an increasing common prefactor to the shifts in frequency, Δ, and half-bandwidth, ΔΓ. The ratio ΔΓ/(-Δ), which quantifies the energy dissipated per time and unit area, decreases with time. Often, there is a fast initial decrease, lasting for about 100 milliseconds, followed by a slower decrease, persisting over the entire drying time (a few seconds). Fitting the overtone dependence of Δ() and ΔΓ() with power laws, one finds power-law exponents of about 1/2, characteristic of semi-infinite Newtonian liquids. The power-law exponents corresponding to Δ() slightly increase with time. The decrease of ΔΓ/(-Δ) and the increase of the exponents are explained by evaporation and formation of a solid film at the resonator surface.
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http://dx.doi.org/10.3390/s20205915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589769PMC
October 2020

Compressional-Wave Effects in the Operation of a Quartz Crystal Microbalance in Liquids:Dependence on Overtone Order.

Sensors (Basel) 2020 Apr 29;20(9). Epub 2020 Apr 29.

Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany, (F.M.).

The operation of the quartz crystal microbalance (QCM) in liquids is plagued by small flexural admixtures to the thickness-shear deformation. The resonator surface moves not only in the transverse direction, but also along the surface normal, thereby emitting compressional waves into the liquid. Using a simple analytical model and laser Doppler vibrometry, we show that the flexural admixtures are stronger on the fundamental mode than on the overtones. The normal amplitude of motion amounts to about 1% of the transverse motion on the fundamental mode. This ratio drops by a factor of two on the overtones. A similar dependence on overtone order is observed in experiments, where the resonator is immersed in a liquid and faces an opposite planar wall, the distance of which varies. Standing compressional waves occur at certain distances. The amplitudes of these are smaller on the overtones than on the fundamental mode. The findings can be rationalized with the tensor form of the small-load approximation.
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http://dx.doi.org/10.3390/s20092535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249204PMC
April 2020

Fast pH-mediated changes of the viscosity of protein solutions studied with a voltage-modulated quartz crystal microbalance.

Biointerphases 2020 03 24;15(2):021004. Epub 2020 Mar 24.

Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany.

An electrochemical quartz crystal microbalance is described, which achieves a time resolution down to 100 μs. Accumulation and averaging over a few hours bring the noise down to about 30 mHz. The application examples are pH-driven viscosity changes in albumin solutions. The pH was switched with the electrode potential. The characteristic response time is in the millisecond range. The focus is on experimental aspects as well as advantages and limitations of the technique.
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http://dx.doi.org/10.1116/1.5140619DOI Listing
March 2020

An ultrafast quartz crystal microbalance based on a frequency comb approach delivers sub-millisecond time resolution.

Rev Sci Instrum 2019 Nov;90(11):115108

Advanced Wave Sensors S.L., Calle Algepsers 24-1, 46988 Paterna, Valencia, Spain.

Quartz crystal microbalance with dissipation monitoring (QCMD) is a simple and versatile sensing technique with applications in a wide variety of academic and industrial fields, most notably electrochemistry, biophysics, quality control, and environmental monitoring. QCMD is limited by a relatively poor time resolution, which is of the order of seconds with conventional instrument designs at the noise level usually required. In this work, we present a design of an ultrafast QCMD with submillisecond time resolution. It is based on a frequency comb approach applied to a high-fundamental-frequency (HFF) resonator through a multifrequency lock-in amplifier. The combination allows us to reach data acquisition rates >10 kHz. We illustrate the method using a toy model of a glass sphere dropped on the resonator surfaces, bare or coated with liposomes, in liquid. We discuss some interesting features of the results obtained with the dropped spheres, such as bending of the HFF resonators due to the impact, sphere bouncing (or the absence of it), and contact aging.
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http://dx.doi.org/10.1063/1.5115979DOI Listing
November 2019

Commentary on "the influence of patient insurance status on access to outpatient orthopedic care for flexor tendon lacerations".

J Hand Surg Am 2014 Mar;39(3):534

Department of Orthopaedic Surgery, University of South Alabama, Mobile, AL.

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http://dx.doi.org/10.1016/j.jhsa.2013.11.028DOI Listing
March 2014

Understanding the phase behavior of coarse-grained model lipid bilayers through computational calorimetry.

J Phys Chem B 2012 Feb 25;116(5):1551-69. Epub 2012 Jan 25.

Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

We study the phase behavior of saturated lipids as a function of temperature and tail length for two coarse-grained models: the soft-repulsive model typically employed with dissipative particle dynamics (DPD) and the MARTINI model. We characterize the simulated transitions through changes in structural properties, and we introduce a computational method to monitor changes in enthalpy, as is done experimentally with differential scanning calorimetry. The lipid system experimentally presents four different bilayer phases - subgel, gel, ripple, and fluid - and the DPD model describes all of these phases structurally while MARTINI describes a single order-disorder transition between the gel and the fluid phases. Given both models' varying degrees of success in displaying accurate structural and thermodynamic signatures, there is an overall satisfying extent of agreement for the coarse-grained models. We also study the lipid dynamics displayed by these models for the various phases, discussing this dynamics with relation to fidelity to experiment and computational efficiency.
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http://dx.doi.org/10.1021/jp207837vDOI Listing
February 2012

Spirituality within the patient-surgeon relationship.

J Surg Educ 2011 Jan-Feb;68(1):36-43. Epub 2010 Nov 5.

Department of General Surgery, College of Medicine and Medical Center, University of South Alabama, Mobile, Alabama, USA.

Objective: To assess the attitudes of general and orthopaedic surgical outpatients regarding inquiry into their religious beliefs, spiritual practices, and personal faith.

Design: Prospective, voluntary, self-administered, and anonymously-completed questionnaire, regarding religious beliefs, spiritual practices, and personal faith, March-August, 2009.

Setting: General and orthopaedic surgical outpatient settings, Health Services Foundation, College of Medicine, University of South Alabama, a tertiary care academic medical center in Mobile, Alabama.

Participants: All patients referred for evaluation and management of general and orthopaedic surgical conditions, pre- and postoperatively, were approached.

Methodology: The questionnaire solicited data regarding patient: (1) demographics; (2) religious beliefs, spiritual practices, and personal faith; and (3) opinions regarding inquiry into those subjects by their surgeon. The latter opinions were stratified on a 5-point Likert scale ranging from "strongly disagree" to "strongly agree." Statistical analysis was conducted using software JMP(®) 8 Statistical Discovery Software (S.A.S. Institute Inc., Cary, North Carolina) and a 5% probability level was used to determine significance of results.

Results: Eighty-three percent (83%) of respondents agreed or strongly agreed that surgeons should be aware of their patients' religiosity and spirituality; 63% concurred that surgeons should take a spiritual history; and 64% indicated that their trust in their surgeon would increase if they did so. Nevertheless, 17%, 37%, and 36% disagreed or strongly disagreed with those perspectives, respectively.

Conclusions: By inference to the best explanation of the results, we would argue that religiosity and spirituality are inherent perspectives of patient-surgeon relationships. Consequently, those perspectives are germane to the therapeutic milieu. Therefore, discerning each patient's perspective in those regards is warranted in the context of an integrative and holistic patient-surgeon relationship, the intent of which is to restore a patient to health and well-being.
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http://dx.doi.org/10.1016/j.jsurg.2010.08.007DOI Listing
June 2011

Molecular simulation of the effect of cholesterol on lipid-mediated protein-protein interactions.

Biophys J 2010 Dec;99(11):3629-38

Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA.

Experiments and molecular simulations have shown that the hydrophobic mismatch between proteins and membranes contributes significantly to lipid-mediated protein-protein interactions. In this article, we discuss the effect of cholesterol on lipid-mediated protein-protein interactions as function of hydrophobic mismatch, protein diameter and protein cluster size, lipid tail length, and temperature. To do so, we study a mesoscopic model of a hydrated bilayer containing lipids and cholesterol in which proteins are embedded, with a hybrid dissipative particle dynamics-Monte Carlo method. We propose a mechanism by which cholesterol affects protein interactions: protein-induced, cholesterol-enriched, or cholesterol-depleted lipid shells surrounding the proteins affect the lipid-mediated protein-protein interactions. Our calculations of the potential of mean force between proteins and protein clusters show that the addition of cholesterol dramatically reduces repulsive lipid-mediated interactions between proteins (protein clusters) with positive mismatch, but does not affect attractive interactions between proteins with negative mismatch. Cholesterol has only a modest effect on the repulsive interactions between proteins with different mismatch.
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http://dx.doi.org/10.1016/j.bpj.2010.09.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2998597PMC
December 2010

Molecular simulation of the DMPC-cholesterol phase diagram.

J Phys Chem B 2010 Aug;114(32):10451-61

Department of Chemical Engineering, University of California, Berkeley, 101B Gilman Hall, Berkeley, California 94720-1462, USA.

In this paper, we present a coarse-grained model of a hydrated saturated phospholipid bilayer (dimyristoylphosphatidylcholine, DMPC) containing cholesterol that we study using a hybrid dissipative particle dynamics-Monte Carlo method. This approach allows us to reach the time and length scales necessary to study structural and mechanical properties of the bilayer at various temperatures and cholesterol concentrations. The properties studied are the area per lipid, condensation, bilayer thickness, tail order parameters, bending modulus, and area compressibility. Our model quantitatively reproduces most of the experimental effects of cholesterol on these properties and reproduces the main features of the experimental phase and structure diagrams. We also present all-atom simulation results of the system and use these results to further validate the structure of our coarse-grained bilayer. On the basis of the changes in structural properties, we propose a temperature-composition structure diagram, which we compare with the experimental phase and structure diagrams. Attention is paid to the reliability and interpretation of the model and simulation method and of the different experimental techniques. The lateral organization of cholesterol in the bilayer is discussed.
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http://dx.doi.org/10.1021/jp103903sDOI Listing
August 2010

Towards an understanding of membrane-mediated protein-protein interactions.

Faraday Discuss 2010 ;144:359-67; discussion 445-81

Centre Européen de Calcul Atomique et Moléculaire, 46 Allée d'Italie, 69364 Lyon, France.

We propose a computational framework to study the lipid-mediated clustering of integral membrane proteins. Our method employs a hierarchical approach. The potential of mean force (PMF) of two interacting proteins is computed under a coarse-grained 3-D model that successfully describes the structural properties of reconstituted lipid bilayers of dymiristoylphophatidylcholine (DMPC) molecules. Subsequently, a 2-D model is adopted, where proteins represented as self-avoiding disks interact through the previously computed PMF, which is modified to take into account three body corrections. The aggregation of the proteins is extensively studied under the condition of negative hydrophobic mismatch: the formation of clusters with increasing size agrees with previous computational and experimental findings.
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http://dx.doi.org/10.1039/b902190fDOI Listing
March 2010

Comment on "Cluster formation of transmembrane proteins due to hydrophobic mismatching".

Phys Rev Lett 2009 May 29;102(21):219801; author reply 219802. Epub 2009 May 29.

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http://dx.doi.org/10.1103/PhysRevLett.102.219801DOI Listing
May 2009

Effect of cholesterol on the structure of a phospholipid bilayer.

Proc Natl Acad Sci U S A 2009 Mar 18;106(10):3654-8. Epub 2009 Feb 18.

Centre Européen de Calcul Atomique et Moléculaire, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.

Cholesterol plays an important role in regulating the properties of phospholipid membranes. To obtain a detailed understanding of the lipid-cholesterol interactions, we have developed a mesoscopic water-lipid-cholesterol model. In this model, we take into account the hydrophobic-hydrophilic interactions and the structure of the molecules. We compute the phase diagram of dimyristoylphosphatidylcholine-cholesterol by using dissipative particle dynamics and show that our model predicts many of the different phases that have been observed experimentally. In quantitative agreement with experimental data our model also shows the condensation effect; upon the addition of cholesterol, the area per lipid decreases more than one would expect from ideal mixing. Our calculations show that this effect is maximal close to the main-phase transition temperature, the lowest temperature for which the membrane is in the liquid phase, and is directly related to the increase of this main-phase transition temperature upon addition of cholesterol. We demonstrate that no condensation is observed if we slightly change the structure of the cholesterol molecule by adding an extra hydrophilic head group or if we decrease the size of the hydrophobic part of cholesterol.
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http://dx.doi.org/10.1073/pnas.0809959106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2656135PMC
March 2009

Molecular simulations of lipid-mediated protein-protein interactions.

Biophys J 2008 Aug 16;95(4):1851-65. Epub 2008 May 16.

Centre Européen de Calcul Atomique et Moléculaire, Ecole Normale Supérieure, Lyon, France.

Recent experimental results revealed that lipid-mediated interactions due to hydrophobic forces may be important in determining the protein topology after insertion in the membrane, in regulating the protein activity, in protein aggregation and in signal transduction. To gain insight into the lipid-mediated interactions between two intrinsic membrane proteins, we developed a mesoscopic model of a lipid bilayer with embedded proteins, which we studied with dissipative particle dynamics. Our calculations of the potential of mean force between transmembrane proteins show that hydrophobic forces drive long-range protein-protein interactions and that the nature of these interactions depends on the length of the protein hydrophobic segment, on the three-dimensional structure of the protein and on the properties of the lipid bilayer. To understand the nature of the computed potentials of mean force, the concept of hydrophilic shielding is introduced. The observed protein interactions are interpreted as resulting from the dynamic reorganization of the system to maintain an optimal hydrophilic shielding of the protein and lipid hydrophobic parts, within the constraint of the flexibility of the components. Our results could lead to a better understanding of several membrane processes in which protein interactions are involved.
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http://dx.doi.org/10.1529/biophysj.107.124164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2483748PMC
August 2008

Bilateral peroneal nerve palsy following emergent stabilization of a pelvic ring injury.

J Orthop Trauma 2003 Jan;17(1):67-70

Department of Orthopaedic Surgery, Denver Health Medical Center, University of Colorado Health Sciences Center, 777 Bannock Street, Denver, CO 80204, USA.

External noninvasive compressive devices are becoming popular for emergent stabilization of pelvic ring disruptions. The ease of application utilizing available materials such as sheets, the noninvasive nature of such measures, and perceived absence of complications has made this a popular stabilization modality. The authors report a case of bilateral peroneal nerve palsy related to the use of external compressive wraps in a patient with pelvic ring injury.
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http://dx.doi.org/10.1097/00005131-200301000-00012DOI Listing
January 2003