Thermal Agitation Energy Research Articles

Large-Size Honeycomb-Shaped and Iris-Like Liquid Crystal Elastomer Actuators

Large-Size Honeycomb-Shaped and Iris-Like Liquid Crystal Elastomer Actuators

Magnetic properties and large cryogenic low-field magnetocaloric effect of HoCo2 nanoparticles without core/shell structure

The HoCo(2) nanoparticles are found to be stable in air without any shell protection. The HoCo(2) nanoparticles display superparamagnetic properties between their blocking temperature of 40 K and Curie temperature of 78 K. The magnetic-entropy change increases with decreasing temperature at a certain magnetic-field change, which is ascribed to the competition between the Zeeman energy and thermal-agitation energy at low temperatures. A large magnetic-entropy change of 19.4 J kg(-1) K(-1) was found at 7.5 K in an applied-field change from 1 to 7 T, while 6.1 J kg(-1) K(-1) was achieved in a low field change of 1 T. HoCo(2) nanoparticles are useful for application of magnetic refrigeration at low temperatures.

Planck–Benzinger thermal work function: Monoclonal antibody–DNA duplex binding interactions

AbstractWe have reexamined the van't Hoff plots and delineation of thermodynamic data of the monoclonal antibodies of Jel 274 and Jel 241 binding to DNA duplex at high ionic strength using fluorescein‐labeled oligonucleotide titration with increasing concentrations of the antibody as reported by Tanha and Lee (Nucleic Acid Res, 1997, 25, 1442). To compare the thermodynamic parameters from data over the experimental temperature range of 277–312.5 K, the binding constant from van't Hoff plots is used to evaluate ΔGo(T) from 0 to 400 K using our general linear T3 model, ΔGo(T) = α +βT2+γT3. The limited information provided by the van't Hoff plots and their extensions is not sufficient to describe the variations in the Gibbs free energy change as a function of temperature and other thermodynamic functions observed in these and other biological interactions. Rather, it is necessary to determine a number of thermodynamic parameters, including the heat of reaction, (Th), (Tm), and (TCp), and the thermal set point, (TS), all of which can be precisely assessed using our general linear T3 model. To date, no experimental measurement offers this degree of accuracy. In evaluating the thermodynamic parameters in the binding interaction of monoclonal IgG Jel 241–d[AT]20DNA duplex, it is apparent that at a high NaCl concentration, the range of the compensatory temperatures, (Th) = 155 K and (Tm) = 450 K, is much broader than observed in any other sample, whereas the thermal set points, (TS) = 330 K, is 20–30 K higher. The inherent chemical bond energy ΔHo(T0) is much lower in this sample. The values of thermal agitation energy (heat capacity integrals) are of similar magnitude for all the samples tested. It appears that increasing the NaCl concentration to 130 mM will greatly enhance the binding interaction between the monoclonal antibody and DNA duplex. It is not clear, however, from the limited data available, whether the binding interaction is sequence specific, although logic would suggest it is. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

Uniform delivery of silicon nanoparticles on device quality substrates using spin coating from isopropyl alcohol colloids

Silicon nanoparticles, of predominately 2.9 nm in size, in isopropyl alcohol are spin coated directly on device quality silicon-dioxide layers across 150 mm substrates. Atomic force microscopy (AFM) is used to image the nanoparticle distributions and low levels of agglomeration with apparently regular internanoparticle distances are observed. AFM depth profiling of the nanoparticle size is in agreement with independent high resolution transmission electron microscopy measurements. Hartree–Fock based atomistic simulations confirm the possible formation of Si nanoparticle/isopropanol complexes with a calculated electrostatic binding energy of 30 meV, which is slightly larger than the room temperature thermal agitation energy. The low levels of agglomeration can be explained in terms of such complexes that may regulate the internanoparticle and nanoparticle-solvent interactions.

Adsorption–desorption phenomenon and the kinetic equation at interfaces in liquid crystalline systems

The adsorption–desorption phenomenon in a sample having the shape of a slab is investigated by using a particular form for the kinetic equation at the limiting surfaces. A closed solution for the time evolution of the ion density in a nematic liquid crystal sample submitted to an external field is obtained in the limit in which the effective field coincides with the external field. In this framework it is shown that the intrinsic time connected with the presence of the electric field is proportional to the drift time. The constant of proportionality is of the order of the ratio between the thermal agitation energy and the electrostatic energy. In a similar manner, the time evolution of the bulk and surface densities, in the case of neutral particles, is also determined in a closed form by means of a simple expression. A microscopic model giving rise to a kinetic equation, similar to the one used in the analysis, is presented. We propose a statistical interpretation of the adsorption–desorption phenomenon in the framework of Maxwell–Boltzmann statistics, in which the relationship between the phenomenological parameters, entering into the kinetic equation at the boundary surfaces, with the microscopic model is derived. The analysis is suitable for the description of the adsorption phenomena of neutral particles (dyes) as well as charged particles (ions) in nematic liquid crystals.

Intrinsic characteristic times in the drift-diffusion problem

The redistribution of impurities in a sample in the shape of a slab filled with an isotropic liquid submitted to an external field is considered. The case in which the impurities are ions dissolved in the liquid, and the external field is an electric field is also investigated. It is shown that the intrinsic time connected with the presence of the electric field is proportional to the drift time. The constant of proportionality is of the order of the ratio between the thermal agitation energy and the electrostatic energy. A closed solution for the time evolution of the density of particles is obtained. The importance of the effect on real situations is investigated. The possible application of these results to nematic samples submitted to an external electric field is discussed.

Planck–Benzinger thermal work function in biological systems

AbstractThe Planck–Benzinger methodology provides a means of determining the innate temperature‐invariant enthalpy and thermal agitation energy, or the heat capacity integrals, ∫ ΔCp°(T)dT, and allows precise determination of 〈TCp〉, 〈Th〉, 〈Ts〉, and 〈Tm〉. It is a method for evaluating [ΔH − ΔH°(T0)], the heat of reaction for biological molecules at room temperature. The results imply that the negative Gibbs free energy change minimum at a well‐defined stable temperature, 〈Ts〉, where the bound unavailable energy TΔS° = 0, has its origin in the sequence‐specific hydrophobic interactions. Each case confirms the existence of a thermodynamic molecular switch wherein a change of sign in ΔCp°(T)reaction leads to true negative minimum in the Gibbs free energy change of reaction and, hence, a maximum in the related equilibrium constant, Keq. At this temperature, 〈TS〉, ΔH°(TS)(−) = ΔG°(TS)(−)min, the maximum work can be accomplished in biological systems. Application of the Planck–Benzinger methodology to biological systems has demonstrated a basic rule for life processes, in that there is a lower cutoff point, 〈Th〉, where entropy is favorable but enthalpy is unfavorable, that is, ΔH°(Th)(+) = TΔS°(Th)(+), and an upper cutoff, 〈Tm〉, above which enthalpy is favorable but entropy unfavorable, that is, ΔH°(Tm)(−) = TΔS°(Tm)(−). Only between these two limits, that is, where ΔG°(T) = 0, is the net chemical driving force favorable for such biological processes as protein folding; protein–protein, protein–nucleic acid or protein‐membrane interactions; and protein–self‐assembly. Indeed, all interacting biological systems examined using the Planck–Benzinger methodology have shown such a thermodynamic switch at the molecular level, suggesting that its existence may be universal. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004

Temperature dependence of the magnetic rotation process of kaolinite microcrystals containing paramagnetic impurity ions dispersed in liquid medium

Temperature dependencies of magnetic rotation were measured in micron-sized silicates dispersed in ethanol for two different samples of kaolinite. Magnetic rotation proceeded by balance between thermal agitation energy and magnetic anisotropy energy. Measurements were performed between 195 and 343 K. The field intensity required to achieve magnetic alignment of microcrystals increases with temperature, because of the temperature dependence of paramagnetic anisotropy, and the temperature dependence of thermal agitation energy. The results indicate that the values of magnetic anisotropy of nonmagnetic materials might partially derive from the paramagnetic moments, which derive from paramagnetic impurity ions. The present experiment provides a technical basis for determining the precise values of diamagnetic anisotropy (Δχ)DIA from minerals which have a concentration of paramagnetic ions and do not form a single crystal large enough to allow bulk Δχ measurements. The values of (Δχ)DIA can be obtained by extrapolating the Δχ–T relations, which follow the Curie law, to the temperature limits.

Short wavelength fluctuation effects on the magnetization in type I and low-κ typeII superconductors

The effects on the magnetization of fluctuating Cooper pairs created above thesuperconducting transition by thermal agitation energy (the so-calledfluctuation-induced diamagnetism, FD) have been measured in a clean type Isuperconductor (Pb) and in a clean low Ginzburg–Landau parameter (κ)type II superconductor (Nb). These experiments extend the earliermeasurements of Gollub, Beasley and Tinkham to both the high reducedtemperature region (ε ≡ ln (T/TC0) ≳ 0.1)and the high reduced magnetic field region (h ≡ H/HC2 (0) ≳ 0.1).Our data show that in spite of FD being deeply affected in bothsuperconductors by the presence of non-local electrodynamic effects,the superconducting fluctuations sharply vanish when ε orhbecome of the order of 0.5 and, respectively, 1. This short-wavelengthbehaviour at high reduced temperatures of the superconducting fluctuations issimilar to that previously observed at high reduced temperatures in dirtylow-TC superconductorsand in high-TCcuprates, where the non-local effects are unobservable. These last results suggestthat in the short wavelength regime the superconducting fluctuations in cleanlow-TCsuperconductors are still dominated by the uncertainty principle,which imposes a limit to the shrinkage, when εincreases, of the superconducting wavefunction. This may also be the case when h → 1,although the presence of strong non-local effects in these clean and low-κsuperconductors may also deeply affect their high field behaviour.

Magneto-rotation experiments of micron-sized particles dispersed in a diffused gas medium oriented to reproduce the dust alignment in the interstellar region

The magneto-rotations were detected for graphite single-crystal grains dispersed in the diffused gas media for the first time in the pressure range between 300 Pa to 10 5 Pa at a temperature, T = 293 K. Full alignment wasachieved at a field intensity of 14 mT for the graphite crystal of 3 x 10 - 1 2 grms in weight at 300 Pa. The results were consistent with the Langevin theory, in which the balance between field-induced anisotropy energy and the thermal agitation energy were assumed to drive the process. The achieved experimental procedure provides a technical basis to reproduce the magnetic alignment in the diffused and low temperature condition of the star-formation region, considering that the contemporary experiments on magneto-rotation are performed on particles suspended in the liquid media. The experiments at low temperatures below 160 K can be performed only in the gas medium. The field intensity to achieve magnetic alignment is expected to be considerably small at molecular cloud temperature, due to the decrease of thermal agitation energy and due to the temperature dependence of the paramagnetic anisotropy following the Curie-Weiss law.

Laterally attached liquid-crystalline polymers as stationary phases. Effect of temperature in RP HPLC and comparison with a commercial C18 stationary phase

Specific side-on-fixed liquid-crystalline polymers (SOLCP) have been synthesized for use in silica-modified stationary phases in high-performance liquid chromatography (HPLC). The mesogenic side group of the SOLCP is composed of three benzoate-type phenyl rings with terminal alkoxy chains and is laterally linked to a polysiloxane backbone via an alkyl ester spacer arm. The dependence of the logarithm of the retention factor on the reciprocal temperature showed that the liquid-crystalline anisotropic order was conserved in the small pores (200 A diameter) of the silica gel. The first-order nematic-isotropic transition is lost and probably becomes second-order. Adsorption enthalpies for the liquid-crystalline stationary phases have been measurement for three polycyclic aromatic hydrocarbon isomers (ortho-terphenyl, triphenylene, and chrysene) and compared with those for a commercial C18 phase. The adsorption enthalpies never exceeded 30 kJ mol−1, i.e. ten times the thermal agitation energy,RT. They were always less on the SOLCP stationary phase than on the C18 column, emphasizing the more rigid structure of the liquid crystalline phase and its mechanism based upon adsorption. Better separation of steroids, pesticides and amino acids were obtained with the LCP-coated silica than the commercial bonded C18 column. Four small peptides were successfully separated by using pure water as mobile phase.

Beyond the Planck–Benzinger thermal work function: New insights into the role of molecular switches in biology

AbstractThe Planck‐Benzinger methodology provides a means of determining the innate temperature‐invariant enthalpy, ΔH°(T0), thermal agitation energy, or the heat capacity integrals ∫ΔCp°(T)dT, and allows precise determination of 〈TCp〉, 〈Th〉, 〈Ts〉, and 〈Tm〉. It is a method for evaluating [ΔH − ΔH°(T0)], the heat of reaction for biologic molecules at room temperature, and provides for a better understanding of cooperative thermodynamic compensation. The Planck‐Benzinger methodology demonstrates that macromolecular interactions will always exhibit a negative value of the Gibbs free energy change at a well‐defined temperature. It can be used for determination of the thermodynamic molecular switch, where there is a change of sign in ΔCp°(T)reaction which determines the behavior patterns of the Gibbs free energy change. equation image All interacting biologic systems that we have thus far examined using the Planck‐Benzinger approach point to the universality of this thermodynamic switch. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002

Magnetorotation Experiment of Diamagnetic Single-Crystal Grains Suspended in a Gas Medium for Examining Dust Alignment in the Interstellar Region

The magnetic alignment of diamagnetic grains suspended in a gas medium is observed for the first time on micron-sized single crystals of graphite by the use of a system newly developed for this purpose. Previously magnetic alignment was studied on grains suspended in a liquid medium. The field of full orientation H s at T =293 K was as small as 140 G when the crystal size was 3.5 µm in diameter and 1.0 µm in thickness. It was examined experimentally that the alignment in the gas medium depends on the balance between the thermal agitation energy and the diamagnetic anisotropy energy induced in the particle. This experiment is necessary in order to examine the grain alignment of the interstellar region, which is the basis to observe the interstellar magnetic field. The experiment is necessary also to determine the diamagnetic anisotropy for various inorganic materials through high-temperature measurements.

Thermodynamic molecular switch in micelles

It is well known that essentially all macromolecular interactions function over a well-defined temperature range. The Gibbs free energy change, Δ G °( T), for macromolecular interaction shows a complicated behavior, wherein Δ G °( T) changes from positive to negative, then reaches a negative value of maximum magnitude (favorable), and finally becomes positive as temperature increases. This communication demonstrates that the critical factor is a temperature-dependent Δ C p °( T) (specific heat capacity change) of reaction, which is positive at low temperature but switches to a negative value at a temperature well below the ambient range. This thermodynamic molecular switch determines the behavior patterns of the Gibbs free energy change, and hence a change in the equilibrium constant, K eq, and/or spontaneity. The subsequent, mathematically predictable changes in Δ H °( T), Δ S °( T), Δ W °( T) and Δ G °( T) give rise to the classically observed behavior patterns in biological systems. This communication will also demonstrate the existence of a thermodynamic molecular switch in both nonionic surfactants, (OPE) i where i=1, 3, 8, and 10 and ionic n-DTAB surfactants in H 2O, D 2O, 3 M urea and 2 M dioxane, over the experimental temperature range of 285–360 K, based on Chun's development of the Planck–Benzinger methodology (P.W. Chun, Int. J. Quantum Chem.: Quantum Biol. Symp. 15 (1988) 247; P.W. Chun, Manual for Computer-Aided Analysis of Biochemical Processes with Florida 1-2-4, University of Florida copyright reserved, 1991; P.W. Chun, J. Phys. Chem. 86 (1994) 6851; P.W. Chun, J. Biol. Chem., 270 (1995) 13925; P.W. Chun, J. Phys. Chem. 100 ( ̄ 1996) 7283; P.W. Chun, in: 212th National American Chemistry Society Meeting, Orlando, Fla, American Chemical Society, Biophysical Chemistry, poster 283, 1996; P.W. Chun, J. Phys. Chem. B 101 (1997) 7835; P.W. Chun, Methods in Enzymology, vol. 295, 1998, pp. 12, 227; P.W. Chun, Int. J. Quantum Chem.: Quantum Biol. Symp., 75 (1999) 1027; P.W. Chun, Int. J. Quantum Chem.: Quantum Biol. Symp. (2000); P.W. Chun, Biophysical J., 75 (2000) 416; P.W. Chun, Cell Biochem. Biophys. (2000)). In the case of micellar size distribution, the change in inherent chemical bond energy, ΔH °( T 0), in micellar interaction is small. In contrast, the thermal agitation energy (heat capacity integrals), is much larger and roughly the same over a broad size distribution. This qualitative trend differs markedly from results seen for biochemical interactions, yet the underlying mathematical interpretation is the same.

Thermodynamic molecular switch in sequence‐specific hydrophobic interactions

AbstractThis communication will demonstrate the existence of a thermodynamic molecular switch in the pairwise, sequence‐specific hydrophobic interaction of Ile–Ile, Leu–Ile, Val–Leu, or Ala–Leu over the temperature range of 273–333 K reported by Nemethy and Scheraga in 1962. Based on Chun's development of the Planck–Benzinger methodology, the change in inherent chemical bond energy at 0 K, ΔH°(T0), is 3.0 kcal mol−1 for Ile–Ile, 2.4 for Leu–Ile, 1.8 for Val–Leu, and 1.2 kcal mol−1 for Ala–Leu. The value of ΔH°(T0) decreases as the length of the hydrophobic side chain decreases. It is clear that the strength and stability of the hydrophobic interaction is determined by the packing density of the side chains, with Ala–Leu being the most stable. At 〈Tm〉, the thermal agitation energy, \documentclass{article}\pagestyle{empty}\begin{document}$\int^{T}_{0}\Delta Cp^{\circ}(T)\,dT$\end{document}, is about five times greater than ΔH°(T0) in each case. Additionally, the thermal agitation energy for the same series, evaluated at 〈Tm〉, decreases in the same order, that is, as the length of the side chain decreases. This pairwise, sequence‐specific hydrophobic interaction is highly similar in its thermodynamic behavior to that of other biological systems, except that the negative Gibbs free energy change minimum at 〈Ts〉 occurs at a considerably higher temperature, 355 K compared to about 300 K. The melting temperature, 〈Tm〉, is also high, 470 K compared to 343 K in a biological system. The implication is that the negative Gibbs free energy minimum at a well‐defined 〈Ts〉 has it origin in the hydrophobic interactions, which are highly dependent on details of molecular structure. In addition to the four specific dipeptide interactions described, we have shown in our unpublished work the existence of a thermodynamic molecular switch in the interactions of 32 dipeptides wherein a change of sign in ΔCp°(T)reaction leads to a true negative minimum in the Gibbs free energy of reaction, and hence, a maximum in the related Keq. Indeed, all interacting biological systems that we have thus far examined using the Planck–Benzinger approach point to the universality of thermodynamic molecular switches. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001

Uncovering the innate thermodynamic quantities in protein unfolding

The “cold denaturation” phenomenon is analyzed using an extension of the Planck-Benzinger thermal work function. For small molecules, reaction enthalpies are often obtained around room temperature, such that ΔH=ΔHo(To)+∫ ΔC po dT, and the heat of reaction is estimated in terms of the innate temperature-invariant enthalpy (inherent chemical bond energy), ΔHo(To). Cottrell (The Strength of Chemical Bonds; Academic Press; New York, London, 1958; Chapter 3; pp. 21–46; Chapter 4; pp. 47–70) pointed out 40 years ago that ΔH and ΔHo(T0) differ only by 1% in small molecules, but in 1971 Benzinger [Nature (London) 1971, 220, 100–103] made the crucial observation that this difference is large in biological macromolecules due to the large magnitude of the heat capacity integrals (thermal agitation energy). In the other words, for small molecules, [ΔH−ΔHo(T0)] is a correction of only a few percent, whereas for biological macromolecules, the heat capacity integrals can be large, from 10% up to 50% of the total heat of reaction. In the case of T4 phage lysozyme, the thermal unfolding of wild type and mutant [W138, W138Y, and 3W(128, 138, 158)3Y] forms have heat capacity integrals that are some 10 times greater than the innate temperature-invariant enthalpy. In cases of protein unfolding such as the phage T4 phage lysozyme mutants, no thermodynamic molecular switch, unique to biological systems, is observed. It is apparent that use of the Planck-Benzinger thermal work function to evaluate the innate temperature-invariant enthalpy can be tremendously helpful in differentiating between native wild-type and closely-related mutant forms of protein. Therefore, this thermodynamic application should be essential to any future studies involving the site-directed, mutagenic approach to an examination of structure-function problems in proteins. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 1027–1042, 1999

Frequency-dependent ionic conductivity in (Ag 2S) x(GeS 2) 1 − x glasses

Following the theoretical model of the polarization conductivity of ionically conducting glasses, based on the notion of ionic “free-volume” fluctuations, a new procedure is envisaged to explain the experimental results. This procedure allows us to ascribe a precise physical significance to experimentally determined parameters. On the basis of (Ag 2S) x (GeS 2) 1 − x glasses, we have demonstrated, without ambiguity, that the polarization conductivity dependence on temperature and frequency could be expressed as A( T) ω s( ω, T) . It is found experimentally that s is a function of temperature T and frequency ω. This result is interpreted theoretically by using the notions of thermal agitation energy and the “bound-charge” concept usually used to describe the polarization phenomena.

Diamagnetic anisotropy of sheetsilicates

The diamagnetic properties of sheetsilicates are studied by measuring the magnetic orientation of micron-sized crystals. In the case of synthetic phlogopite with the average diameter of 0.65 μm and the thickness of 0.2 μm, the alignment of the grains is achieved in the magnetic field below 35 kOe. The planes of the platy single-crystal grains were alignned parallel to the field when the alignment was achieved. The alignment of the grains is realized because the field-induced anisotropic energy, caused by the diamagnetic anisotropy in the mineral's crystal structure, exceeds thermal agitation energy in the applied field. By analyzing the field dependence of grain alignment, the diamagnetic anisotropy per formula unit, Δχ, of sheetsilicate mineral is estimated even if a large single crystal is not provided. The field-induced anisotropic energy is proportional to NΔχ where N is the number of molecules in the grain.

Dielectric energy of orientation in dead and living cells of Schizosaccharomyces pombe. Fitting of experimental results to a theoretical model

Using the experimental data obtained with killed cells of Schizosaccharomyces pombe (1), we have formulated a theoretical model that is able to predict cell orientation for microorganisms with ellipsoidal or cylindrical shapes as a function of the frequency of the electric field and of the conductivity of the external medium. In this model, comparison of the difference in potential energy for both orientations parallel-perpendicular with the thermal agitation energy allows one to interpret the intervals where these orientations occur. The model implies that the conductivity of the cytoplasm is slightly higher than that of the external medium. This assumption is easy to understand taking into account that not all the intracytoplasmic material is released to the exterior during cell death.

A new method of producing the magnetic refrigerant suitable for the ericsson magnetic refrigeration

A layer structural complex magnetic refrigerant, which is suitable for the Ericsson cycle, satisfying the Carnot principle, has been investigated. Above ∼ 15 K, since the thermal agitation energy and the lattice entropy increase considerably, the ferromagnetic material has to be used for the refrigerant in the magnetic refrigeration. However, the variation of the magnetic entropy of the ferromagnets is not appropriate to the Ericsson cycle in which the entropy difference ΔS J between two kinds of the isomagnetic field processes should be constant in the refrigeration range. In order to make the refrigerant having constant ΔS J mentioned above, we made the layer structural sintered material composed of four kinds of ferromagnets, ErAl 2.2 , HoAl 2.2 , (Dy 0.5 Ho 0.5 )Al 2.2 and DyAl 2.2 , and investigated its entropy experimentally. As the result, it is verified that the layer structural magnetic material is one of the most promising refrigerant for the Ericsson cycle.