Browsing by Subject "THERMODYNAMICS"

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  • Muratore-Ginanneschi, Paolo; Schwieger, Kay (2017)
    We present a stylized model of controlled equilibration of a small system in a fluctuating environment. We derive the optimal control equations steering in finite-time the system between two equilibrium states. The corresponding thermodynamic transition is optimal in the sense that it occurs at minimum entropy if the set of admissible controls is restricted by certain bounds on the time derivatives of the protocols. We apply our equations to the engineered equilibration of an optical trap considered in a recent proof of principle experiment. We also analyze an elementary model of nucleation previously considered by Landauer to discuss the thermodynamic cost of one bit of information erasure. We expect our model to be a useful benchmark for experiment design as it exhibits the same integrability properties of well-known models of optimal mass transport by a compressible velocity field.
  • Häkkinen, Silja A. K.; McNeill, V. Faye; Riipinen, Ilona (2014)
  • Andersen, Jens O.; Brauner, Tomas; Hofmann, Christoph P.; Vuorinen, Aleksi (2014)
  • Aarts, Gert; Alton, Chris; Amato, Alessandro; Giudice, Pietro; Hands, Simon; Shuiierd, Jon-Ivar (2015)
  • Driver, Gordon W.; Sprakel, Lisette J. M.; Kilpelainen, Ilkka; Schuur, Boelo (2021)
    Isothermal titration calorimetry (ITC) experiments were performed for investigation of binary mixtures comprised of the Bronsted superbase DBN with hydrogen ethanoate (AcOH). The heat of mixing (H-E) profile was recorded at (343.15 +/- 0.1) K and fitted with a 5-parameter Redlich-Kister (RK) polynomial. RK fit parameters were subsequently used to quantify partial molar heats of mixing, x(i)H(i)(E), for each component i. ITC-based complexometric titration data for the binary mixtures were recorded separately in methyl isobutyl ketone (mibk) and dodecane, to investigate the energetics of non random clustering phenomena. Variable temperature H-1-NMR in combination with ATR-FTIR spectroscopic analyses were employed in parallel for elucidation and verification of liquid state ion speciation. These investigations reveal a strongly non ideal system, and indicate "superbase" character of DBN is preserved for specific compositions where stoichiometric ionic liquids (ILs) form. Available ion speciation has been found to include [DBN-H](+), [AcO] as well as mu 2 -hydrogen-bridged, hydrogen-bonded homoassociate anions, of the type [H(OAc)(2)], with double liquid salt formation characterising various compositions based on spectroscopic determinations. (C) 2021 The Authors. Published by Elsevier Ltd.
  • Yang, Yu; Cheng, Bin; Kourzeneva, Ekaterina; Semmler, Tido; Rontu, Laura; Lepparanta, Matti; Shirasawa, Kunio; Li, Zhijun (2013)
  • Mohr, Claudia; Thornton, Joel A.; Heitto, Arto; Lopez-Hilfiker, Felipe D.; Lutz, Anna; Riipinen, Ilona; Hong, Juan; Donahue, Neil M.; Hallquist, Mattias; Petaja, Tuukka; Kulmala, Markku; Yli-Juuti, Taina (2019)
    Particles formed in the atmosphere via nucleation provide about half the number of atmospheric cloud condensation nuclei, but in many locations, this process is limited by the growth of the newly formed particles. That growth is often via condensation of organic vapors. Identification of these vapors and their sources is thus fundamental for simulating changes to aerosol-cloud interactions, which are one of the most uncertain aspects of anthropogenic climate forcing. Here we present direct molecular-level observations of a distribution of organic vapors in a forested environment that can explain simultaneously observed atmospheric nanoparticle growth from 3 to 50 nm. Furthermore, the volatility distribution of these vapors is sufficient to explain nanoparticle growth without invoking particle-phase processes. The agreement between observed mass growth, and the growth predicted from the observed mass of condensing vapors in a forested environment thus represents an important step forward in the characterization of atmospheric particle growth.
  • Kohout, Tomas; Bucko, Michal; Rasmus, Kai; Leppäranta, Matti; Matero, Ilkka (2014)
    Non-invasive geophysical prospecting and a thermodynamic model were used to examine the structure, depth and lateral extent of the frozen core of a palsa near Lake Peerajärvi, in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a depth of ~0.6 m and extends to about 4 m depth. Its lateral extent is ~15 m x ~30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilized in studies of climate impact on Arctic wetlands.
  • Paajanen, Johanna; Lönnrot, Satu; Heikkilä, Mikko; Meinander, Kristoffer; Kemell, Marianna; Hatanpää, Timo; Ainassaari, Kaisu; Ritala, Mikko; Koivula, Risto (2019)
    Both stable and radioactive antimony are common industrial pollutants. For antimonate (Sb(v)) removal from industrial waste water, we synthesized submicron zirconium dioxide (ZrO2) fibers by electroblowing and calcination of the as-electroblown fibers. The fibers are amorphous after calcination at 300 and 400 degrees C and their average diameter is 720 nm. The fibers calcined at 500 to 800 degrees C have an average diameter of 570 nm and their crystal structure transforms from tetragonal to monoclinic at the highest calcination temperatures. We investigated Sb(v) adsorption capacity of the synthesized ZrO2 fibers as a function of pH, adsorption isotherm at pH 6 and adsorption kinetics at pH 7. The tetragonal ZrO2 fibers calcined at 500 degrees C exhibited the best potential for Sb(v) remediation with Sb(v) uptake of 10 mg g(-1) at pH 2 and a maximum Sb(v) uptake of 8.6 mg g(-1) in the adsorption isotherm experiment. They also reached 30% of 7 days' Sb(v) uptake in only a minute. The adsorption kinetics followed the Elovich model.
  • Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; Rubach, F.; Kleist, E.; Wildt, J.; Mentel, Th. F.; Carrasquillo, A. J.; Daumit, K. E.; Hunter, J. F.; Kroll, J. H.; Worsnop, D. R.; Thornton, J. A. (2015)
    We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO-HR-ToF-CIMS are highly correlated with, and explain at least 25-50% of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50% of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of lower volatility components into the detected higher volatility compounds.
  • Denicol, Gabriel S.; Molnár, Etele; Niemi, Harri; Rischke, Dirk H. (2019)
    We derive the equations of motion of relativistic, resistive, second-order dissipative magnetohydrodynamics from the Boltzmann-Vlasov equation using the method of moments. We thus extend our previous work [Phys. Rev. D 98, 076009 (2018)], where we only considered the nonresistive limit, to the case of finite electric conductivity. This requires keeping terms proportional to the electric field E-mu in the equations of motions and leads to new transport coefficients due to the coupling of the electric field to dissipative quantities. We also show that the Navier-Stokes limit of the charge-diffusion current corresponds to Ohm's law, while the coefficients of electrical conductivity and charge diffusion are related by a type of Wiedemann-Franz law.
  • Pyykkö, Pekka (2019)
    A simple formula is derived for the eutectic point of an A-B system in terms of the monomer melting points and melting enthalpies. This estimate is tested on several non-ionic or ionic systems, with or without common ions, including choline chloride/urea mixtures. The results are compared with the Schroder-van Laar equation.
  • Romatschke, Paul; Säppi, Matias (2019)
    In 2 + 1 dimensions, QED becomes exactly solvable for all values of the fermion charge e in the limit of many fermions N-f >> 1. We present results for the free energy density at finite temperature T to next-to-leading-order in large N-f. In the naive large N-f limit, we uncover an apparently UV-divergent contribution to the vacuum energy at order O(e(6)n(f)(3)), which we argue would become a finite contribution of order O(e(6)N(f)(4)) when resumming formally higher-order 1/N-f contributions. Still in the limit of large N-f, we find the finite-temperature free energy to be well-behaved for all values of the dimensionless coupling e(2)N(f)/T, and to be bounded from above by the free energy of Nf free fermions and bounded from below by non interacting QED3. We invite follow-up studies from finite-temperature lattice gauge theory at large but fixed N-f to test our results in the regime e(2)N(f)/T >> 1.