New method for the 3D Ising model

A simple, general and practically exact method is developed for the equilibrium properties of the macroscopic physical systems with translational symmetry. Applied to the Ising model in two and three dimension, a modest calculation gives the spontaneous magnetization and the specific heat to less than 1% error

The heat capacity of nitrogen chain in grooves of single-walled carbon nanotube bundles

The heat capacity of bundles of closed-cap single-walled carbon nanotubes with one-dimensional chains of nitrogen molecules adsorbed in the grooves has been first experimentally studied at temperatures from 2 to 40 K using an adiabatic calorimeter. The contribution of nitrogen CN₂ to the total heat capacity has been separated. In the region 28 K the behavior of the curve CN₂(T) is qualitatively similar to the theoretical prediction of the phonon heat capacity of 1D chains of Kr atoms localized in the grooves of SWNT bundles. Below 3 K the de-pendence CN₂(Т) is linear. Above 8 K the dependence CN₂(Т) becomes steeper in comparison with the case of Kr atoms. This behavior of the heat capacity CN₂(Т) is due to the contribution of the rotational degrees of free-dom of the N₂ molecules

Phase transitions in solid Kr–CH₄ solutions and rotational excitations in phase II

The heat capacity CP of solid Kr–n CH₄ solutions with the CH₄ concentrations n = 0.82, 0.86, 0.90 as well as solutions with n = 0.90, 0.95 doped with 0.002 O₂ impurity has been investigated under equilibrium vapor pressure over the interval 1–24 K. The (T,n)-phase diagram was refined and the region of two-phase states was determined for Kr–n CH₄ solid solutions. The contribution of the rotational subsystem, Crot, to the heat capacity of the solutions has been separated. Analysis of Crot(T) at T < 3 K made it possible to estimate the effective conversion times τ and the energy gaps E₁ and E₂ between the tunnel levels of the A-, T- and A-, E-nuclear-spin species of CH₄ molecules in the orientationally ordered subsystem, and to determine the effective energy gaps E₁ between the lowest levels of the A- and T- species. The relations τ(n) and E₁(n) stem from changes of the effective potential field caused as the replacement of CH₄ molecules by Kr atoms at sites of the ordered sublattices. The effective gaps EL between a group of tunnel levels of the ground-state libration state and the nearest group of excited levels of the libration state of the ordered CH₄ molecules in the solutions with n = 0.90 (EL = 52 K) and 0.95 (EL = 55 K) has been estimated

The effect of n-H₂ impurity on the heat capacity of solid Ne

The alloy of Ne - 5.1%n-H₂ was investigated calorimetrically under equilibrium vapor pressure in an interval of 0.9–25 K. The magnitudes and the temperatures dependencies of the heat capacity Cso₁(T) of the alloy at T = 11–20 K are strongly dependent on the conditions of sample preparation. The temperatures dependencies of the Cso₁(T) of the sample prepared in a calorimeter by direct condensation of a gas mixture at T = 15 K exhibit a smeared maximum near the triple point temperature of hydrogen and a phase transition at T = 17.1 K. The detected features of Cso₁(T) indicate that the preparation of the solid Ne – n-H₂ from a gas phase leads to the formation of a nonequilibrium long-living phase Ne with large H₂ concentrations and a small portion of H₂ inclusions with low Ne concentrations. The phase transition is caused by decompositions of this phase. The phase dose not recover on cooling the sample after the phase transition. It is found that the rate of the ortho-para conversion of the H₂ molecules in the solid Ne – n-H₂ solutions higher than that of solid H₂

The specific heat and the radial thermal expansion of bundles of single-walled carbon nanotubes

The specific heat at constant pressure C(T) of bundles of single-walled carbon nanotubes (SWNTs) closed at their ends has been investigated in a temperature interval of 2–120 K. It is found that the curve C(T) has features near 5, 36, 80, and 100 K. The experimental results on the C(T) and the radial thermal expansion coefficient αR(T) of bundles of SWNTs oriented perpendicular to the sample axis have been compared. It is found that the curves C(T) and αR(T) exhibit a similar temperature behavior at T > 10 K. The temperature dependence of the Grüneisen coefficient γ(T) has been calculated. The curve γ(T) also has a feature near 36 K. Above 36 K the Grüneisen coefficient is practically independent of temperature (γ ≈ 4). Below 36 K γ(T) decreases monotonically with lowering temperature and becomes negative at T < 6 K

Le pluralisme politique à l’épreuve de la vie privée : entre normes et pratiques

L’espace des relations interpersonnelles et privées, en tant qu’espace de politisation et d’expression des choix politiques, est peu connu. C’est à une meilleure connaissance du « citoyen privé » et de la « politisation intime » que cet article veut contribuer, en étudiant les ressemblances et les divergences idéologiques au sein du cercle des proches. Présentant les résultats d’une enquête quantitative et représentative de la population française inédite, « Famille, amour et politique », réalisée par le CEVIPOF, il examine la filiation, la conjugalité, et l’amitié et montre les interactions et les transactions qui opèrent entre le système des normes et le système des affects des individus. La famille apparaît plus hétérogame politiquement tandis que le couple et le cercle des amis sont plus homogames. Toutefois, c’est le niveau de politisation des individus qui est en dernière instance le plus déterminant. Une affiliation politique affirmée, et tout particulièrement à gauche, ainsi qu’un intérêt marqué pour la politique, renforcent toujours l’homogamie politique au sein du cercle des proches, dans les principes comme dans les faits. Plus largement, l’article ouvre une réflexion sur l’espace de la vie privée en tant que terrain d’expérience des conditions de la pluralité démocratique.Little is known of the role played by private interpersonal relationships in politicization and the expression of political choices. This article aims to improve our understanding of “private citizens” and “personal politicization” through a study of ideological similarities and divergences within family and friendship circles. The analysis, based on findings from an unprecedented quantitative representative French population survey by the CEVIPOF (Center for the study of French political life) entitled “Famille, amour et politique” [Family, love and politics], examines filiation, conjugality and friendship, showing the interactions and transactions that take place between the system of norms and the system of individual feelings. Families appear more heterogamous politically, while couples and friendship circles are more homogamous. However, individuals’ level of politicization is ultimately the most determinant factor. Having a strong political affiliation, particularly on the left of the political spectrum, and a strong interest in politics always strengthens intra-circle political homogamy in terms of both principles and actions. At a more general level, the article reflects on the sphere of private life as a field for the development of conditions of democratic pluralism

A simple low-temperature adiabatic calorimeter for small samples

A simple adiabatic calorimeter has been made to investigate the heat capacity of small samples (≤ 1 cm³) of carbon nanomaterials in the temperature range from 1 to 300 K. It makes possible: i) short-time mounting of a sample; ii) doping of samples with gases directly in the calorimeter; iii) short-time cooling of a sample down to helium temperatures. The adiabatic calorimeter is suitable to place into a helium vessel of a portable Dewar or a helium cryostat. The heat capacity of the fullerit sample has been measured in the temperature range from 1 to 30 K

Experimental low-temperature heat capacity of one-dimensional xenon adsorbate chains in the grooves of carbon c-SWNT bundles

The experimental studies of the heat capacity of 1D chains of xenon atoms adsorbed in the outer grooves of bundles of closed single-walled carbon nanotubes CXe have been first made at temperature range 2–30 K with the adiabatic calorimeter. The experimental data CXe have been compared with theory [A. Šiber, Phys. Rev. B 66, 235414 (2002)]. The experimental and theoretical heat capacity curves are close below 8 K. Above 8 K the experimental curve CXe (T) exceeds the theoretical one and excess capacity CXe (T) increases monotonously with temperature. We assume that the CXe (T) caused mainly by the increase of the distance between the neighboring xenon atoms in the chain with increasing temperature