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Measurements of the relative changes Δλ/λ of the electron capture rate is a direct experimental way to determine the changes Δρ(0) of electron density on the nucleus ρ(0), which are necessary for the determination of the Mössbauer isomer shift calibration constants. In this paper we present our results obtained using various chemical compounds with ¹²⁵I isotope. Fitting the results to the theoretical model, we find the parameters, and using a genetic algorithm we solve the so-called "ill-posed"problem. The calculated Δλ/λ values compared with KIO₃ are ( − 2.9 ± 0.3)·10⁻⁴ for Na₃H₂IO₆, ( − 1.6 ± 0.1)·10⁻⁴ for KIO₄, ( − 1.4 ± 0.6)·10⁻⁴ for CsI.

We describe the entropy evolution of an isolated thermodynamical system, consisting of an ideal gas contained in an adiabatic cylinder partitioned by a movable frictionless adiabatic piston, and show that, under appropriate initial conditions, the entropy can decrease. This remarkable exception to the second law of thermodynamics (which we show not to contradict Boltzmann H-theorem) would actually take place over an extremely long, in practice unobservable, time for an ordinary macroscopic system. However, there is a range of physical parameters, pertaining to mesoscopic systems, where the decrease can occur on a realistic time scale.

Stimulated by recent experimental results, we simulate "temperature"-cycling experiments in a model for the compaction of granular media. We report on the existence of two types of memory effects: short-term dependence on the history of the sample, and long-term memory for highly compact (aged) systems. A natural interpretation of these results is provided by the analysis of the density heterogeneities.

We study an atmospheric corona discharge on plants and trees, because these discharges can be connected with sterilization and stimulation of biological objects and with the transfer of electrical charge to the Earth. It is shown that the form of current-voltage characteristics depends on the type of plant or tree. We report the measurement of characteristics on coniferous trees -spruce and pine, and analyse results for single-needle and multineedle system of electrodes. The differences can depend on the composition of the surrounding atmosphere, different ionization mechanism and phenological phases of the trees.

An electromagnetic speed-meter made of a three-dimensional frame is proposed, which allows measuring speeds independently of any external reference. The device is constituted by three orthogonal light beams and uses the motion-induced aberration of light or Bradley aberration. The frame is formed by three orthogonal beams which stand for the three axes. On the top of each axis arm of the frame a diode laser is fixed whose divergent beam impinges on a convergent lens which focalizes the light on an optoelectronic position detector of high resolution, placed on the base of each arm. The shift of each beam spot due to aberration of light is recorded, from which the motion of the frame is derived. Furthermore, if it is settled on a spacecraft its motion can be controlled in a way to record no aberration shift on any axis, indicating that the spacecraft is then at rest in the cosmic space. Since the referential frame does not use any external reference, it can be taken as a universal frame from which absolute speeds can be defined.

The potential between two D0-branes at rest is calculated to be linear. Also the potential between two fast decaying D0-branes is found to be in agreement with phenomenological heavy-quark potentials.

We investigate the aggregation number and size distributions for inter-molecular clusters of amphiphilic diblock and triblock copolymers in poor solvent at very low concentrations. Diblocks and triblocks with hydrophilic ends are shown to possess narrow distributions corresponding to formation of monodispersed mesoglobules. Diblocks with hydrophobic ends are found to produce inter-cluster multimers due to bridging by the hydrophilic middle blocks, resulting in polydisperse distributions. Implications of these observations for the preparation of monodispersed nanoparticles and, potentially, for the understanding of the quaternary structure of proteins are discussed.

Granular material is vibro-fluidized in N = 2 and N = 3 connected compartments, respectively. For sufficiently strong shaking the granular gas is equi-partitioned, but if the shaking intensity is lowered, the gas clusters in one compartment. The phase transition towards the clustered state is of 2nd order for N = 2 and of 1st order for N = 3. In particular, the latter is hysteretic. The experimental findings are accounted for within a dynamical model that has exactly the above properties.

The mechanism and kinetics of a shear-induced formation of multi-lamellar vesicles in a lyotropic lamellar phase of C₁₀E₃ (Triethyleneglycol-decylether) was investigated by rheology and time-resolved small-angle neutron and light scattering (SANS, SALS). Starting from a well-defined, macroscopically oriented lamellar phase, the transition occurs in two steps. First, there is a formation of an intermediate structure oriented in the flow direction which scatters only perpendicular to the flow. This is compatible with long, multi-lamellar cylinders (tubuli). Comparing results from three different shear rates shows that the formation of this intermediate structure is strain controlled. As shear is continued, multilamellar vesicles are formed.

In this paper, it is shown that a configuration-modulated system described by the Frenkel-Kontorova model can be locked at an incommensurate phase when the quantum zero-point energy is taken into account. It is also found that the specific heat for an incommensurate phase shows a different parameter dependence in the sliding phase and pinning phase. These findings provide a possible way for experimentalists to verify the phase transition by breaking of analyticity.

We present a numerical study of magnetic phases of the 2D electron gas near freezing. The calculations are performed by diffusion Monte Carlo in the fixed-node approximation. At variance with the 3D case we find no evidence for the stability of a partially polarized phase. With plane wave nodes in the trial function, the polarization transition takes place at r_s = 20, whereas the best available estimates locate Wigner crystallization around r_s = 35. Using an improved nodal structure, featuring optimized backflow correlations, we confirm the existence of a stability range for the polarized phase, although somewhat shrunk, at densities achievable nowadays in 2-dimensional hole gases in semiconductor heterostructures. The spin susceptibility of the unpolarized phase at the magnetic transition is approximately 30 times the Pauli susceptibility.

CeIrIn₅ is a member of a new family of heavy-fermion compounds and has a Sommerfeld specific-heat coefficient of 720 mJ/molK². It exhibits a bulk, thermodynamic transition to a superconducting state at T_c = 0.40 K, below which the specific heat decreases as T² to a small residual T-linear value. Surprisingly, the electrical resistivity drops below instrumental resolution at a much higher temperature T₀ = 1.2 K. These behaviors are highly reproducible and field-dependent studies indicate that T₀ and T_c arise from the same underlying electronic structure. The layered crystal structure of CeIrIn₅ suggests a possible analogy to the cuprates in which spin/charge pair correlations develop well above T_c.

The magnetic-field-induced magnetic and electrical transition from antiferromagnetic nonmetal phase to paramagnetic metal phase takes place below a temperature of 270 K. Meanwhile, a large magnetoresistance ( − 1530%) in NiS was observed under a magnetic field of 4 T at a temperature of 268 K, which is due to the field-induced nonmetal-metal transition.

It is shown that in cermets, with metal percolating clusters in a dielectric host, the metal plasmon modes can strongly couple to the dielectric vibrational modes, optical phonons. In metal-dielectric percolation composites, the plasmon modes are capable of strong accumulation of the electromagnetic energy in small nanometer-sized areas, "hot spots". The local fields in the hot spots can be very large, leading to enhanced absorption by optical phonons of the dielectric. In our experiments, strongly enhanced absorption by the coupled plasmon-phonon modes has been observed in Au − Al₂O₃ percolation composites.

Using as a model the Hubbard Hamiltonian, we determine various basic properties of electron- and hole-doped cuprate superconductors for a spin-fluctuation-induced pairing mechanism. We find for both hole- and electron-doped cuprates d_{x² − y²} symmetry for the superconducting order parameter. We find a narrow doping range of superconductivity for electron-doped superconductors like Nd_{2 − x}Ce_xCuO₄ and Pr_{2 − x}Ce_xCuO₄. The superconducting transition temperatures T_c(x) for various electron doping concentrations x are calculated to be much smaller than for hole-doped cuprates due to the different energy dispersion and a flat band well below the Fermi level for electron-doped superconductors. Lattice disorder may sensitively distort the symmetry d_{x² − y²} via electron-phonon interaction. We present a general discussion of the symmetry of the order parameter which should apply also to other spin-fluctuation-induced superconductors. Furthermore, we show how our theory may also explain the neutron scattering data.

Giant diamagnetism, with values to − 1.4·10⁻² emu/g, was observed from 4.2 K to 310 K in selenides of monoclinic NiAs structure prepared with stoichiometries FeSe·uCr₂Se₃, u = 0.1 to 1.0. A positive component due to magnetic order of the spins was present from 4.2 K to about 65 K-150 K, depending on the sample. The magnetic order was minimized by doping with As_0.3Ge_0.3. Another sample doped with Ga and Ge gave a decrease in the slope of negative susceptibility vsT(K) starting at 220 K and thus an increase in the range of diamagnetism to well over ambient temperature.

Using the ¹¹⁹Sn Mössbauer effect, the critical magnetic behavior of a single-crystal (110) Cr sample doped with ∼ 0.1 at% ¹¹⁹Sn was investigated in the vicinity of the Néel temperature, T_N. The transition from a paramagnetic to an antiferromagnetic state was found to have a double character: it is continuous and has a hysteresis of ΔT_N ≈ 1.3 K. The latter feature has been observed for the first time. The critical exponent β of the average hf field was found to be a continuous function of the reduced temperature, t, ranging between β ≈ 0.3 for t ≈ 10⁻³ and β ≈ 0.57 for t ≈ ×10⁻².

Iron films, grown on Cu(110) surfaces, are very rough when prepared under normal growth conditions. When Fe is deposited at room temperature, Stranski-Krastanov growth is observed, i.e. three-dimensional (3D) islands form. Here it is shown that a smooth 5 ML thick Fe film can be grown on the Cu(110) surface by depositing the film at low temperature (T < 125 K) and subsequently anneal the film to 240 K. Since the thermodynamically stable state of the film is the state where the film has a rough surface, as found after deposition at room temperature, the smooth surface obtained by annealing after low-temperature deposition has to be considered as metastable. Long-time stability of the smooth film, i.e. for periods of several hours, was found at 140 K and below. Keeping the film at a temperature of 240 K or above results in the formation of large 3D islands as evidenced by the formation of (111) facets. The mechanism on which the preparation of the smooth film is based is discussed in terms of a competition between smoothening of the outermost surface layer and nucleation and growth of holes in the film which leads to the formation of 3D islands.

Interfaces in Fe(xML)/V(yML) multilayers have been examined. Two pairs of samples each with definite x and y were prepared using the same deposition process and the same elemental variations with the ⁵⁷Fe probe layers interfoliated between completed V and Fe (natural abundance) layers. The only difference was the deposition ordering. The superlattice structures were analyzed by X-ray diffraction and ⁵⁷Fe Conversion Electron Mössbauer Spectroscopy at room temperature and at 10 K. The ⁵⁷Fe magnetic hyperfine field distribution for the pairs is found to be significantly different, irrespectively of the values of x, and y and can be interpreted as due to the Fe layer being smoother than the V one. The magnetic moments derived for the interface layer as well as for the subsequent atomic layer are significantly lower than the calculated values.

The mechanism of the dielectric response in Ca_βSr_{1 − β}TiO₃ is explained according to the transverse-field Ising model. The impurity-polarized cluster induces the appearance of ferroelectric domain states. The random field leads to the diffusion of the dielectric response. Our model is in good agreement with the experimental result.

Polarised Raman spectroscopy is performed in a randomly distributed single-wall carbon tube (SWNT) sample at the scale of an individual single-wall nanotube. A detailed analysis in the radial-breathing mode (RBM) domain is presented. Selection of either a single tiny rope of SWNTs or of a single SWNT results from the conjugated high spatial selection of confocal microscopy, surface-enhanced Raman spectroscopy (SERS) and sample dilution. The drastic modifications observed in the low-frequency Raman spectra as a function of the polarisation configuration confirm the theoretical results.