Nanoparticle Formation and Coating Using Supercritical Fluids
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Colloidal Crystallization: Nucleation and Growth
Colloidal Crystallization: Nucleation and Growth Dave Weitz Harvard Urs Gasser Konstanz Andy Schofield Edinburgh Rebecca Christianson Harvard Peter Pusey Edinburgh Peter Schall Harvard Frans Spaepen Harvard Eric Weeks Emory John Crocker UPenn •Colloids as model systems – soft materials •Nucleation and growth of colloidal crystals •Defect growth in crystals •Binary Alloy Colloidal Crystals NSF, NASA http://www.deas.harvard.edu/projects/weitzlab EMU 6/7//04 Colloidal Crystals Colloids 1 nm - 10 µm solid particles in a solvent Ubiquitous ink, paint, milk, butter, mayonnaise, toothpaste, blood Suspensions can act like both liquid and solid Modify flow properties Control: Size, uniformity, interactions Colloidal Particles •Solid particles in fluid •Hard Spheres •Volume exclusion •Stability: •Short range repulsion •Sometimes a slight charge Colloid Particles are: •Big Slow •~ a ~ 1 micron • τ ~ a2/D ~ ms to sec •Can “see” them •Follow individual particle dynamics Model: Colloid Æ Atom Phase Behavior Colloids Atomic Liquids U U s s Hard Spheres Leonard-Jones Osmotic Pressure Attraction Centro-symmetric Centro-symmetric Thermalized: kBT Thermalized: kBT Gas Gas Liquid Density Liquid Solid Solid Phase behavior is similar Hard Sphere Phase Diagram Volume Fraction Controls Phase Behavior liquid - crystal liquid coexistence crystal 49% 54% 63% 74% φ maximum packing maximum packing φRCP≈0.63 φHCP=0.74 0 Increase φ => Decrease Temperature F = U - TS Entropy Drives Crystallization 0 Entropy => Free Volume F = U - TS Disordered: Ordered: •Higher configurational -
Entropy and the Tolman Parameter in Nucleation Theory
entropy Article Entropy and the Tolman Parameter in Nucleation Theory Jürn W. P. Schmelzer 1 , Alexander S. Abyzov 2 and Vladimir G. Baidakov 3,* 1 Institute of Physics, University of Rostock, Albert-Einstein-Strasse 23-25, 18059 Rostock, Germany 2 National Science Center Kharkov Institute of Physics and Technology, 61108 Kharkov, Ukraine 3 Institute of Thermal Physics, Ural Branch of the Russian Academy of Sciences, Amundsen Street 107a, 620016 Yekaterinburg, Russia * Correspondence: [email protected]; Tel.: +49-381-498-6889; Fax: +49-381-498-6882 Received: 23 May 2019; Accepted: 5 July 2019; Published: 9 July 2019 Abstract: Thermodynamic aspects of the theory of nucleation are commonly considered employing Gibbs’ theory of interfacial phenomena and its generalizations. Utilizing Gibbs’ theory, the bulk parameters of the critical clusters governing nucleation can be uniquely determined for any metastable state of the ambient phase. As a rule, they turn out in such treatment to be widely similar to the properties of the newly-evolving macroscopic phases. Consequently, the major tool to resolve problems concerning the accuracy of theoretical predictions of nucleation rates and related characteristics of the nucleation process consists of an approach with the introduction of the size or curvature dependence of the surface tension. In the description of crystallization, this quantity has been expressed frequently via changes of entropy (or enthalpy) in crystallization, i.e., via the latent heat of melting or crystallization. Such a correlation between the capillarity phenomena and entropy changes was originally advanced by Stefan considering condensation and evaporation. It is known in the application to crystal nucleation as the Skapski–Turnbull relation. -
Heterogeneous Nucleation of Water Vapor on Different Types of Black Carbon Particles
https://doi.org/10.5194/acp-2020-202 Preprint. Discussion started: 21 April 2020 c Author(s) 2020. CC BY 4.0 License. Heterogeneous nucleation of water vapor on different types of black carbon particles Ari Laaksonen1,2, Jussi Malila3, Athanasios Nenes4,5 5 1Finnish Meteorological Institute, 00101 Helsinki, Finland. 2Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland. 3Nano and Molecular Systems Research Unit, 90014 University of Oulu, Finland. 4Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil & Environmental Engineering, École 10 Polytechnique Federale de Lausanne, 1015, Lausanne, Switzerland 5 Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas (FORTH/ICE-HT), 26504, Patras, Greece Correspondence to: Ari Laaksonen ([email protected]) 15 Abstract: Heterogeneous nucleation of water vapor on insoluble particles affects cloud formation, precipitation, the hydrological cycle and climate. Despite its importance, heterogeneous nucleation remains a poorly understood phenomenon that relies heavily on empirical information for its quantitative description. Here, we examine heterogeneous nucleation of water vapor on and cloud drop activation of different types of soots, both pure black carbon particles, and black carbon particles mixed with secondary organic matter. We show that the recently developed adsorption nucleation theory 20 quantitatively predicts the nucleation of water and droplet formation upon particles of the various soot types. A surprising consequence of this new understanding is that, with sufficient adsorption site density, soot particles can activate into cloud droplets – even when completely lacking any soluble material. 1 https://doi.org/10.5194/acp-2020-202 Preprint. Discussion started: 21 April 2020 c Author(s) 2020. -
The Role of Latent Heat in Heterogeneous Ice Nucleation
EGU21-16164, updated on 02 Oct 2021 https://doi.org/10.5194/egusphere-egu21-16164 EGU General Assembly 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. The role of latent heat in heterogeneous ice nucleation Olli Pakarinen, Cintia Pulido Lamas, Golnaz Roudsari, Bernhard Reischl, and Hanna Vehkamäki University of Helsinki, INAR/Physics, University of Helsinki, Finland ([email protected]) Understanding the way in which ice forms is of great importance to many fields of science. Pure water droplets in the atmosphere can remain in the liquid phase to nearly -40º C. Crystallization of ice in the atmosphere therefore typically occurs in the presence of ice nucleating particles (INPs), such as mineral dust or organic particles, which trigger heterogeneous ice nucleation at clearly higher temperatures. The growth of ice is accompanied by a significant release of latent heat of fusion, which causes supercooled liquid droplets to freeze in two stages [Pruppacher and Klett, 1997]. We are studying these topics by utilizing the monatomic water model [Molinero and Moore, 2009] for unbiased molecular dynamics (MD) simulations, where different surfaces immersed in water are cooled below the melting point over tens of nanoseconds of simulation time and crystallization is followed. With a combination of finite difference calculations and novel moving-thermostat molecular dynamics simulations we show that the release of latent heat from ice growth has a noticeable effect on both the ice growth rate and the initial structure of the forming ice. However, latent heat is found not to be as critically important in controlling immersion nucleation as it is in vapor-to- liquid nucleation [Tanaka et al.2017]. -
Using Supercritical Fluid Technology As a Green Alternative During the Preparation of Drug Delivery Systems
pharmaceutics Review Using Supercritical Fluid Technology as a Green Alternative During the Preparation of Drug Delivery Systems Paroma Chakravarty 1, Amin Famili 2, Karthik Nagapudi 1 and Mohammad A. Al-Sayah 2,* 1 Small Molecule Pharmaceutics, Genentech, Inc. So. San Francisco, CA 94080, USA; [email protected] (P.C.); [email protected] (K.N.) 2 Small Molecule Analytical Chemistry, Genentech, Inc. So. San Francisco, CA 94080, USA; [email protected] * Correspondence: [email protected]; Tel.: +650-467-3810 Received: 3 October 2019; Accepted: 18 November 2019; Published: 25 November 2019 Abstract: Micro- and nano-carrier formulations have been developed as drug delivery systems for active pharmaceutical ingredients (APIs) that suffer from poor physico-chemical, pharmacokinetic, and pharmacodynamic properties. Encapsulating the APIs in such systems can help improve their stability by protecting them from harsh conditions such as light, oxygen, temperature, pH, enzymes, and others. Consequently, the API’s dissolution rate and bioavailability are tremendously improved. Conventional techniques used in the production of these drug carrier formulations have several drawbacks, including thermal and chemical stability of the APIs, excessive use of organic solvents, high residual solvent levels, difficult particle size control and distributions, drug loading-related challenges, and time and energy consumption. This review illustrates how supercritical fluid (SCF) technologies can be superior in controlling the morphology of API particles and in the production of drug carriers due to SCF’s non-toxic, inert, economical, and environmentally friendly properties. The SCF’s advantages, benefits, and various preparation methods are discussed. Drug carrier formulations discussed in this review include microparticles, nanoparticles, polymeric membranes, aerogels, microporous foams, solid lipid nanoparticles, and liposomes. -
Thermodynamics and Kinetics of Binary Nucleation in Ideal-Gas Mixtures
1 Thermodynamics and kinetics of binary nucleation in ideal-gas mixtures Nikolay V. Alekseechkin Akhiezer Institute for Theoretical Physics, National Science Centre “Kharkov Institute of Physics and Technology”, Akademicheskaya Street 1, Kharkov 61108, Ukraine Email: [email protected] Abstract . The nonisothermal single-component theory of droplet nucleation (Alekseechkin, 2014) is extended to binary case; the droplet volume V , composition x , and temperature T are the variables of the theory. An approach based on macroscopic kinetics (in contrast to the standard microscopic model of nucleation operating with the probabilities of monomer attachment and detachment) is developed for the droplet evolution and results in the derived droplet motion equations in the space (V , x,T) - equations for V& ≡ dV / dt , x& , and T& . The work W (V , x,T) of the droplet formation is calculated; it is obtained in the vicinity of the saddle point as a quadratic form with diagonal matrix. Also the problem of generalizing the single-component Kelvin equation for the equilibrium vapor pressure to binary case is solved; it is presented here as a problem of integrability of a Pfaffian equation. The equation for T& is shown to be the first law of thermodynamics for the droplet, which is a consequence of Onsager’s reciprocal relations and the linked-fluxes concept. As an example of ideal solution for demonstrative numerical calculations, the o-xylene-m-xylene system is employed. Both nonisothermal and enrichment effects are shown to exist; the mean steady-state overheat of droplets and their mean steady-state enrichment are calculated with the help of the 3D distribution function. -
A New Scaled-Variable-Reduced-Coordinate
A NEW SCALED-VARIABLE-REDUCED-COORDINATE FRAMEWORK FOR CORRELATION OF PURE FLUID SATURATION PROPERTIES By RONALD DAVID SHAVER Bachelor of Science Oklahoma State University Stillwater, Oklahoma 1988 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE May, 1990 -~-' . , ht~-, I':· \c,qc) a,s<~,-, 1-Jv~'-.J• 1 ('O(.:J.;;;;:; A NEW SCALED-VARIABLE-REDUCED-COORDINATE FRAMEWORK FOR CORRELATION OF PURE FLUID SATURATION PROPERTIES Thesis Approved: Thesis Adviser Dean of the Graduate College 1366750 PREFACE A new scaled-variable-reduced-coordinate framework for the correlation of pure fluid saturation properties was developed. Correlations valid over the entire saturation range from the triple point to the critical point were developed for correlation of vapor pressures, liquid densities and vapor densities of widely varying compounds. The correlations are consistent with scaling theories in the near-critical region, and compare favorably with the existing literature models. The three correlations were extended to generalized models to provide predictive capability with average absolute deviations within 1.5%. I wish to express my sincere appreciation to my adviser, Dr. K. A. M. Gasem, for his assistan~e and support during the course of this study. If it were not for his continued enthusiasm in his work and his ongoing interest in his stude~ts, much of this work would not have been completed. I would like to thank the members of my graduate committee, Dr. R. L. Robinson, Jr. and Dr. J. Wagner, for their time and their suggestions about this work. -
Spinodal Lines and Equations of State: a Review
10 l Nuclear Engineering and Design 95 (1986) 297-314 297 North-Holland, Amsterdam SPINODAL LINES AND EQUATIONS OF STATE: A REVIEW John H. LIENHARD, N, SHAMSUNDAR and PaulO, BINEY * Heat Transfer/ Phase-Change Laboratory, Mechanical Engineering Department, University of Houston, Houston, TX 77004, USA The importance of knowing superheated liquid properties, and of locating the liquid spinodal line, is discussed, The measurement and prediction of the spinodal line, and the limits of isentropic pressure undershoot, are reviewed, Means are presented for formulating equations of state and fundamental equations to predict superheated liquid properties and spinodal limits, It is shown how the temperature dependence of surface tension can be used to verify p - v - T equations of state, or how this dependence can be predicted if the equation of state is known. 1. Scope methods for making simplified predictions of property information, which can be applied to the full range of Today's technology, with its emphasis on miniaturiz fluids - water, mercury, nitrogen, etc. [3-5]; and predic ing and intensifying thennal processes, steadily de tions of the depressurizations that might occur in ther mands higher heat fluxes and poses greater dangers of mohydraulic accidents. (See e.g. refs. [6,7].) sending liquids beyond their boiling points into the metastable, or superheated, state. This state poses the threat of serious thermohydraulic explosions. Yet we 2. The spinodal limit of liquid superheat know little about its thermal properties, and cannot predict process behavior after a liquid becomes super heated. Some of the practical situations that require a 2.1. The role of the equation of state in defining the spinodal line knowledge the limits of liquid superheat, and the physi cal properties of superheated liquids, include: - Thennohydraulic explosions as might occur in nuclear Fig. -
About Nucleation
Nucleation • Nucleation: localized formation of a distinct thermodynamic phase. • Nucleation an occur in a gas, liquid or solid phase. Some examples of phases that may form via nucleation include: 1) in gas: Creation of liquid droplets in saturated vapor; 2) in liquid: formation of gaseous bubbles, crystals (e.g., ice formation from water), or glassy regions; 3) in solid: Nucleation of crystalline, amorphous, and even vacancy clusters in solid materials. Such solid state nucleation is important, for example, to the semiconductor industry. • Most nucleation processes are physical, rather than chemical. • Nucleation normally occurs at nucleation sites on surfaces contacting the liquid or vapor. Suspended particles or minute bubbles also provide nucleation sites. This is called heterogeneous nucleation (Lecture 12). • Nucleation without preferential nucleation sites is homogeneous nucleation (Lecture 10-11). Homogeneous nucleation occurs spontaneously and randomly, but it requires superheating or supercooling of the medium. Ref. wikipedia website Homogeneous Nucleation • Compared to the heterogeneous nucleation (which starts at nucleation sites on surfaces), Homogeneous nucleation occurs with much more difficulty in the interior of a uniform substance. The creation of a nucleus implies the formation of an interface at the boundaries of a new phase. • Liquids cooled below the maximum heterogeneous nucleation temperature (melting temperature), but which are above the homogeneous nucleation temperature (pure substance freezing temperature) are said to be supercooled. This is useful for making amorphous solids and other metastable structures, but can delay the progress of industrial chemical processes or produce undesirable effects in the context of casting. • Supercooling brings about supersaturation, the driving force for nucleation. Supersaturation occurs when the pressure in the newly formed solid is less than the vapor pressure, and brings about a change in free energy per unit volume, Gv, between the liquid and newly created solid phase. -
Nucleation and Condensation in Gas-Vapor Mixtures of Alkanes and Water
Nucleation and condensation in gas-vapor mixtures of alkanes and water Citation for published version (APA): Peeters, P. (2002). Nucleation and condensation in gas-vapor mixtures of alkanes and water. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR559332 DOI: 10.6100/IR559332 Document status and date: Published: 01/01/2002 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. -
LIQUEFIED NATURAL GAS RESEARCH at the NATIONAL BUREAU of STANDARDS
NBSIR 74-358 C^i) LIQUEFIED NATURAL GAS RESEARCH at the NATIONAL BUREAU OF STANDARDS PROGRESS REPORT FOR THE PERIOD JULY 1-DEC 31, 1973 D. B. Mann, Editor CRYOGENICS DIVISION • NBS-INSTiTUTE FOR BASIC STANDARDS • BOULDER, COLORADO NBSIR 74-358 LIQUEFIED NATURAL GAS RESEARCH at the NATIONAL BUREAU OF STANDARDS D. B. Mann, Editor Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80302 Progress Report for the Period July 1 - December 31, 1973 U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary NATIONAL BUREAU OF STANDARDS, Richard W Roberts Director Prepared for: American Gas Association 1515 Wilson Boulevard Arlington, Virginia 22209 LNG Density Project Steering Committee (in cooperation with the American Gas Association) Pipeline Research Committee (American Gas Association) Federal Power Commission Bureau of Natural Gas Washington, D. C. 20426 General Services Administration Motor Equipment Research & Technology Division Washington, D. C. 20406 U. S. Department of Commerce Maritime Administration Washington, D. C. 20235 U. S. Department of Commerce National Bureau of Standards Institute for Basic Standards Boulder, Colorado 80302 U. S. Department of Commerce National Bureau of Standards Office of Standard Reference Data Washington, D. C, 20234 ABSTRACT Fourteen cost centers supported by six other agency sponsors in addi- tion to NBS provide the basis for liquefied natural gas (LNG) research at NBS. This integrated progress report to be issued in January and July is designed to: 1) Provide all sponsoring agencies with a semi-annual and annual report on the activities of their individual programs, 2) Inform all sponsoring agencies on related research being conducted at the Cryogenics Division of NBS-IBS. -
Liquid Densities of Oxygen, Nitrogen, Argon and Parahydrogen 6
NATL INST OF STAND & TECH A111D7 231A72 NBS TECHNICAL NOTE 361(Revised) *+ •«, - *EAU O* Metric Supplement May 1974 U.S. DEPARTMENT OF COMMERCE /National Bureau of Standards Liquid Densities of Oxygen, Nitrogen, Argon and Parahydrogen NATIONAL BUREAU OF STANDARDS The National Bureau of Standards ' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Meas- urement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat