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A model is proposed for describing the line shape of absorption and dispersion signals from which a recorded signal of nuclear magnetic resonance (NMR) is formed in a weak field. The expediency of using spectral analysis to determine the contributions of absorption and dispersion signals to the recorded NMR signal has been substantiated using a modulation technique. A new method is proposed for determining these contributions. The research results are presented.

If a person comes into contact with pathogens on public facilities, there is a threat of contact (skin/wound) infections. More urgently, there are also reports about COVID-19 coronavirus contact infection, which once again reminds that contact infection is a very easily overlooked disease exposure route. Herein, we propose an innovative implantation strategy to fabricate a multi-walled carbon nanotube/polyvinyl alcohol (MWCNT/PVA, MCP) interpenetrating interface to achieve flexibility, anti-damage, and non-contact sensing electronic skin (E-skin). Interestingly, the MCP E-skin had a fascinating non-contact sensing function, which can respond to the finger approaching 0–20 mm through the spatial weak field. This non-contact sensing can be applied urgently to human-machine interactions in public facilities to block pathogen. The scratches of the fruit knife did not damage the MCP E-skin, and can resist chemical corrosion after hydrophobic treatment. In addition, the MCP E-skin was developed to real-time monitor the respiratory and cough for exercise detection and disease diagnosis. Notably, the MCP E-skin has great potential for emergency applications in times of infectious disease pandemics. Electronic Supplementary Material Supplementary material (fabrication of MCP E-skin, laser confocal tomography, parameter optimization, mechanical property characterization, finite element simulation, sensing mechanism, signal processing) is available in the online version of this article at 10.1007/s12274-021-3831-z.

We study numerically the thermodynamic properties of the spin nematic phases in a magnetic field in the spin-1 bilinear-biquadratic model. When the field is applied, the phase transition temperature once goes up and then decreases rapidly toward zero, which is detected by the peak-shift in the specific heat. The underlying mechanism of the reentrant behavior is the entropic effect. In a weak field the high temperature paramagnetic phase rapidly loses its entropy while the ferroquadrupolar nematic phase remains robust by modifying the shape of the ferroquadrupolar moment. This feature serves as a fingerprint of generic ferroquadrupolar phases, while it is not observed for the case of antiferroquadrupoles., 6 pages, 4 figures + supplemental material

We study the dissipative conductivity $\sigma_1$ of a dirty superconductor with a finite Dynes parameter $\Gamma$ under a dc-biased weak time-dependent field. The Usadel equation for the current-carrying state is solved to calculate the pair potential, penetration depth, supercurrent density, and quasiparticle spectrum. It is shown that, while the depairing current density $j_d$ for $\Gamma=0$ is coincident with the Kupriyanov-Lukichev theory, a finite $\Gamma$ decreases the superfluid density, resulting in a reduction of $j_d$. The broadening of the peaks of the quasiparticle density of states induced by a combination of a finite $\Gamma$ and a dc bias can reduce $\sigma_1$ below that for the ideal dirty BCS superconductor with $\Gamma=0$, while subgap states at Fermi level proportional to $\Gamma$ results in a residual conductivity at $T\to 0$. We find the optimum combination of $\Gamma$ and the dc bias to minimize $\sigma_1$ by scanning all $\Gamma$ and all currents up to $j_d$. By using the results, it is possible to improve $j_d$ and reduce electromagnetic dissipation in various superconducting quantum devices., Comment: 9 pages, 8 figures

Temperature-dependent magnetization was measured for CuCr2–x Sb x Sе4 solid solutions in the range 300–5 K in a weak field (50 Oe) and a strong field (10 kOe) and in an ac magnetic field having a frequency of 100–10000 Hz and an amplitude of Н = 1 Oe. The type and character of magnetic transitions under investigation in the system were determined, and its magnetic phase diagram was constructed.

Magnetic bioseparation is an important area of biotechnology. Various techniques are used with a wide range of possible applications in bioscience research. Magnetic micro- or nanospheres can be functionalized with appropriate ligands, such as antibodies, with a high affinity to the target, like cells, bacteria or DNA/RNA. In order to realize magnets with efficient separation capabilities, it is important to have a strong force FM acting on the magnetic bodies. FM is proportional to the product of the magnetic field and the field gradient. Many permanent magnets on the market have large magnetic fields, but relatively weak field gradients. GIAMAG magnets have unique and patented designs that produce both very large magnetic fields and high field gradients, resulting in the most forceful magnetic separators available on the market. © 2017. This is the authors' manuscript to the article. The final authenticated version is available online at: http://dx.doi.org/10.1557/adv.2017.113

We study the behaviour of a superconductor in a weak static gravitational field for temperatures slightly greater than its transition temperature (fluctuation regime). Making use of the time-dependent Ginzburg-Landau equations, we find a possible short time alteration of the static gravitational field in the vicinity of the superconductor, providing also a qualitative behaviour in the weak field condition. Finally, we compare the behaviour of various superconducting materials, investigating which parameters could enhance the gravitational field alteration., Comment: 14 pages, 3 figures

It is found analytically that the equilibrium shape of a charged drop in a uniform electrostatic field in calculations of the first order of smallness for the size of stationary deformation can be considered to be spheroidal, and its eccentricity depends on the charge size and on the intensity of an external electrostatic field. On the threshold of losing stability in relation to the superposition of its own and polarizing charges, the square of the equilibrium eccentricity of a strongly charged drop in a weak field is up to 0.34, and the square equilibrium eccentricity of a weakly charged drop in a strong field is up to 0.78 (in terms of opportunity to realize instability).

Molecular dynamic simulations are performed for the dynamic spreading of a nanosized water droplet subject to a parallel electric field. The results show that the droplet spreads asymmetrically in a weak field but symmetrically in a strong field. The initial conditions affect the dynamic spreading behavior but not the final equilibrium shapes.

We investigate the absorptive–dispersive properties of a weak field in a coupled semiconductor double-quantum-dot nanostructure. It is found that the enhanced index of refraction without absorption can be easily controlled via adjusting properly the corresponding parameters of the system. Our scheme opens the possibility to control index of refraction without absorption in a coupled semiconductor double-quantum-dot nanostructure.

The article substantiates the necessity of developing a theoretical model to study the influence of non-stationary processes on the shape of the recorded NMR signal in a weak magnetic field. Therefore, comparison of different ways of solving Bloch’s equations to describe the shape of the recorded NMR signals using a modulation technique is carried out. Moreover, mathematical models have been developed to describe the shape of the NMR signal, considering the peculiarities of its registration using modulation techniques in a weak field. Finally, the results of calculations, obtained by proposed methods, are compared with experimental data.

The magnetoconductivity, which is the correction to the diagonal conductivity proportional to the second power of magnetic-field strength, is calculated in bilayer graphene in the presence of scatt...

The magnetoconductivity proportional to B2 with B the strength of applied magnetic field is calculated in monolayer graphene in a self-consistent Born approximation for scatterers with long-range p...

We investigated the absorptive–dispersive property of a weak field in a four-level inverted-Y quantum well system. We find that the cycling field and relative phase of the applied fields can affect the absorptive–dispersive property of a weak field dramatically, which can be used to manipulate efficiently the ultrahigh index of refraction without absorption. Our study is much more practical than its atomic counterpart due to its flexible design and controllable quantum-interference effect. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state optical communication

In 2012 Coey proposed a theory on the mechanism of magnetic water treatment based on the gradient of the applied field rather than its absolute strength. We tested this theory by measuring the effect of very weak field magnets (≤ 10 G) containing strong magnetic inhomogeneities (ΔB = 770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)) on tap water samples by the use of electric impedance spectroscopy (EIS) and laser scattering. Our results show an increased formation of nm-sized prenucleation clusters (dynamically ordered liquid like oxyanion polymers or “DOLLOPs”) due to the exposure to the magnetic field and thus are consistent with Coey’s theory which is therefore also applicable to very weak magnetic fields as long as they contain strong gradients.

We propose and analyze a novel scheme to realize the large Kerr nonlinearity via electromagnetically induced transparency (EIT) in molecular magnets. This scheme uses two magnetic fields to induce spin coherence. We obtain the analytical expressions of linear susceptibility, self-Kerr, cross-Kerr susceptibility, phase shift and absorption coefficients. Last, we investigate the nonlinear dynamics of the weak field, and show that the dark and bright microwave soliton can form in the magnetic medium.

By recourse to information-theory tools, we study aspects of the dynamics of the interaction between a single trapped ion with a laser field. Despite its simplicity the model we use exhibits a broad range of intricate physical effects that are clearly detected by information quantifiers like Wherl’s entropy and Fisher’s measure. In particular, a sensible dynamical difference between single vs. multi-photon processes is detected.

The formula of weak-field magnetoconductivity Δσ(B) proportional to B2, with B the strength of a magnetic field, is derived for systems corresponding to monolayer and bilayer graphenes. It is repre...

The weak field approximation (WFA) is a conceptually simple and computationally light method for inferring the magnetic field strength and its orientation in the Sun's atmosphere. In this work we study the validity and limitations of this tool when applied to full Stokes Ca II 8542 A profiles to extract information about the chromospheric magnetic field. We find that the range of validity of the WFA depends, amongst other things, on the component of the magnetic field that one is trying to infer. The retrieval of line-of-sight component of the chromospheric magnetic field from the core of the spectral line is reliable for field strengths up to ~1200 G, even when moderate velocity gradients are present. The horizontal component, on the other hand, is suitably derived using the wing-core boundary of the spectral line, but typically yields systematic errors of >10%. The effects of scattering polarization further compound the problem by rendering the transverse field inference problematic in quiet Sun areas, and for observing geometries within 30 degrees of the limb. Magneto-optical effects disproportionately challenge the determination of the magnetic field azimuth in the transverse plane, leading to errors of ~10 degrees. Typical noise levels of 10d-3 relative to the continuum intensity preclude the accurate retrieval of the transverse field strength and its azimuth below a threshold of a few hundred gauss. Striving for a noise level of 10d-4 significantly improves the diagnostic capability of the WFA with this spectral line, at which point the magnetic field inference becomes limited by systematic errors., Published in ApJ

The question on the calculation of certain effective characteristics of a nonlinear composite expressed in terms of integrals of the solution of a cellular problem is considered. The problem for the case of weak nonlinearities or weak fields has been investigated. Calculations of the effective characteristics of the composite have been made.

The EPR spin Hamiltonian parameters of transition ion active centres in frozen aqueous solutions of proteins are distributed as a reflection of distributions in spacial conformations. This phenomenon is generally referred to with the generic term ‘g-strain’, however, its manifestation is not limited to a distribution in the g-values. The equivalent name ‘D-strain’ applies to the situation common for biological half-integer high-spin systems whose powder EPR shape is predominantly modified through the distributive effects in the second-order terms of the spin–spin interaction Hamiltonian. A simple, one-parameter model is developed to account for D-strain, and this forms the basis for an efficient and practical numerical analysis procedure for D-strained spectra in the weak field limit. Analysis of S = 5/2, 7/2, and 9/2 protein examples is used to illustrate the drastic modification of relative intensities and widths and the occurrence of extra turning points in these spectra as a consequence of D-strain.

We calculate the thermal Hall conductivity of YBa2Cu3O6.99 by using Kubo formula approach. The longitudinal thermal conductivity, Kxx,is calculated and then by the relation between Kxx and Kxy the thermal Hall conductivity is evaluated. Our results show an increase in the thermal Hall conductivity with the applied field at low temperatures and weak field, i.e. Kxy ∼ T √H. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The influence of magnetic field and microwave irradiation on dynamical phase separation in submicron Bi2Sr2CaCu2O8+x bridges has been studied. Strong effect on the shape and metastable character of the step-like I-V characteristics are found. Under a weak field H < 2 Oe and low level microwave irradiation the step-like structure of the I-V characteristics smears out and disappears completely. The average frequency of switching between metastable states grows by 5 orders under increase of magnetic field by only 1 Oe. This behavior is explained in terms of the model of dynamical vortex lines.

The mechanism of field-trap effect under conditions of boiling of dielectric liquids in a nonuniform electric field is discussed, which was experimentally observed in [1, 2]. According to the data of [1, 2], an external electric field initiates the process of boiling up of liquid, with the growth of vapor bubbles to the departure size occurs mainly in regions with low values of electric field (in field traps). This phenomenon is attributed to the effect made on the vapor bubbles by electric forces directed in opposition to the field square gradient. In view of this, the bubbles arising in the region of strong field move to the region of weak field where they grow to the departure size to provide for an increase in local heat transfer. Such a mechanism is observed in the cited experiments [1, 2] in the boiling of liquid nitrogen at a flat conducting surface with single projections leading to a local nonuniformity of electric field on a heated surface.

Thermally induced coarsening of the chemically ordered domains in Pb(Mg1/3Ta2/3)O-3 (PMT) ceramics promotes the studying of dielectric behavior of the 1: 1 B-cations ordered PMN-style complex perovskites. In this work, PMT ceramics with different degrees of chemical order were prepared, and their dielectric, and ferroelectric properties of disordered and ordered ceramics were studied as a function of temperature, frequency, and electrical field. It was found that the weak field relaxor nature is insensitive to the chemical order, whereas some non-linear behaviors showed ordering-degree dependence at the low temperature range. (c) 2005 Elsevier Ltd. All rights reserved.

The aim of present work was to investigate the influence of magnetic fields exposure on neurite outgrowth in PC12 cells. The neurite number per cell, length of neurites and directions of neurite growth with respect to the direction of the magnetic field were analyzed after exposure to 50 Hz electromagnetic field for 96 h. A promotion was observed under a weak field (0.23 mT), as the average number of neurites per cell increased to 2.38±0.06 compared to 1.91±0.07 neurites/cell of the control dishes, while inhibition and directional outgrowth was evident under a relatively stronger field (1.32 mT). Our work shows that biological systems can be very sensitive to the strength of electromagnetic field.

The photo-generated time-of-flight electron mobility measurements in 2,5-dibenzthiazolyl thiophene show weak field dependent high electron mobility, typically of the order of 1.21 × 10 -4 cm 2 /Vs at 2.5 x 10 5 V/cm, which is two orders of magnitude higher than that of Alq 3 complex.

Temperature hysteresis of the cholesteric pitch in planar cholesteric layers was observed in [1,2]. A similar hysteresis of the cholesteric pitch in planar layers has to take place in the applied electric (magnetic) field. The restriction on the sample characteristics and strength of the surface anchoring potential are found which ensure defectless mechanism of the pitch field and temperature variations (jumps in the pitch value). The equations describing temperature and field pitch variations are presented and analysed. For weak field an universal character of the pitch variations, similar to those for the temperature variations and dependent on the value of some parameter only, is revealed. In the frame of Rapini model anchoring potential the field and temperature dependencies of the pitch variations and the hysteresis in the pitch jumps for specific values of the mentioned parameter are calculated. Transmission optical spectra of the layer for normal incidence of light are calculated at the points of p...

We have applied the Foldy-Wouthuysen transformation to spin-1 particles interacting with a non- uniform electromagnetic field. This allowed us to simultaneously confirm that the Pomeransky-Khriplovich- Sen'kov theory is valid and that the interaction of spin 1-particles with a weak field is properly described by the Corben-Schwinger equation. We analyzed the possibilities for experimentally testing theoretical conclusions by observing spin oscillations for the planar channeling of particles or nuclei in straight crystals. By carrying out such experiments, we can also detect the spin oscillations produced by electromagnetic interaction and mea- sure the quadrupole moments of short-lived nuclei. © 2003 MAIK "Nauka/Interperiodica".

We measured the transverse magnetoresistivity of the mixed valence compound $\alpha$-YbAlB$_4$. Two configurations were used where current was applied along [110] direction for both and magnetic field was applied along [-110] and $c$-axis. We found the transverse magnetoresistivity is highly anisotropic. In the weak field below 1 T, it is consistent with stronger $c$-$f$ hybridization in the $ab$ plane which was suggested from the previous zero field resistivity measurements. At the higher field above 3 T, we observed a negative transverse magnetoresistivity for the field applied along the $c$-axis. The temperature dependences of the resistivity measured at several different fields suggest the suppression of the heavy fermion behavior at the characteristic field of $\sim 5.5$ T., Comment: 6pages, 4 figures

Low-temperature thermal conductivity measurements were performed on single crystals of $\mathrm{TlNi}{}_{2}\mathrm{Se}{}_{2}$, a nickel chalcogenide heavy-electron superconductor with ${T}_{c}\ensuremath{\simeq}3.7$ K. In zero field, the residual electronic contribution at $T\ensuremath{\rightarrow}0$ K (${\ensuremath{\kappa}}_{0}/T$) was well separated from the total thermal conductivity, which is less than 0.45% of its normal-state value. Such a tiny residual ${\ensuremath{\kappa}}_{0}/T$ is unlikely contributed by the nodal quasiparticles. The nodeless gap structure is supported by the very weak field dependence of ${\ensuremath{\kappa}}_{0}(H)/T$ in low magnetic fields. In the whole field range, ${\ensuremath{\kappa}}_{0}(H)/T$ exhibits an $\mathsf{S}$-shaped curve, as in the case of nickel pnictides $\mathrm{BaNi}{}_{2}\mathrm{As}{}_{2}$ and $\mathrm{SrNi}{}_{2}\mathrm{P}{}_{2}$. This common feature of nickel-based superconductors can be explained by multiple nodeless superconducting gaps.

The instability of plane surface of a liquid metal in an electric field is shown to arise in arbitrarily weak field, as distinct from the well-known Tonks–Frenkel instability which takes place only in sufficiently high field. Only an account for the atomic structure of the metal leads to finite strength of the critical field which provokes the instability; however, even in this case the critical field occurs essentially less than the Tonks–Frenkel field.

We present here a sketch of some numerical results offered by a micromagnetism code based on the resolution of the Landau–Lifchitz equation. We have computed equilibrium configurations and dynamic susceptibilities to a weak field for magnetic materials with non-uniform magnetization and finite size and shape: cubic particles, finite-sized films with stripe domains and platelets with in-plane magnetocrystalline anisotropy. The obtained results have been compared with analytical models and experimental results. Some non-trivial effects have been pointed out (like surface modes) and fine details can be disclosed by susceptibility maps.

Monte Carlo simulations were performed to examine the dc magnetron discharge that creates anomalous erosion at the boundary of the curved and straight sections of a rectangular magnetron. In order to examine the cause of anomalous erosion, we performed a series of simulations describing the strong and weak field regions without the curved section. The erosion profiles were calculated under differing magnetic field distributions. We found that anomalous erosion occurs under a magnetic field of more than 200 G. We also found that the cause of anomalous erosion is the weak magnetic field at the curved section as compared to that at the straight section. We confirmed that anomalous erosion does not occur in the case of a rectangular magnetron having a uniform magnetic field. In order to avoid anomalous erosion, the uniformity of the magnetic field has to be within 10% where the vertical component of the magnetic field at the target surface is zero.

The effect of pressure on the luminescence spectrum of the weak field system Cr3+ : LiTaO3 is presented. By using pressure to induce a low to high crystal field strength transition, we demonstrate the ability of pressure to identify distinct dopant bonding environments in luminescent materials.

A large number of epidemiological and experimental studies suggest that prolonged (>100 s) weak 50-60-Hz electric and magnetic field (EMF) exposures may cause biological effects(NIEHS Working Group, NIH, 1998; Bersani, 1999). We show, however, that for typical temperature sensitivities of biochemical processes, realistic temperature variations during long exposures raise the threshold exposure by two to three orders of magnitude over a fundamental value, independent of the biophysical coupling mechanism. Temperature variations have been omitted in previous theoretical analyses of possible weak field effects, particularly stochastic resonance (Bezrukov and Vodyanoy 1997a. Nature. 385:319-321; Astumian et al., 1997 Nature. 338:632-633; Bezrukov and Vodyanoy, 1997b. Nature. 338:663; Dykman and McClintock, 1998. Nature. 391:344; McClintock, 1998;. Gammaitoni et al., 1998. Rev. Mod. Phys. 70:223-287). Although sensory systems usually respond to much shorter (approximately 1 s) exposures and can approach fundamental limits (Bialek, 1987 Annu. Rev. Biophys. Biophys. Chem. 16:455-468; Adair et al, 1998. Chaos. 8:576-587), our results significantly decrease the plausibility of effects for nonsensory biological systems due to prolonged, weak-field exposures.

A weak field DNP study of 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-hydroxy-TEMPO), 4-amino-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-amino-TEMPO), and 2, 2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) free radicals invarious solvents was performed at 1.53 mT using a doubleresonance spectrometer. pi transitions, in which the RF fieldhas a component perpendicular to the static magnetic fieldB0, and final sigma transitions, in which the RF field has a component parallel to B0, were recorded. In order to observe thefinal sigma transitions a new probe head was designed. The final sigma transitions were obtained at the frequencies expected from theoretical calculations. However, the results obtained for the observed enhancements deviated from the values expectedtheoretically.

The weak field dielectric aging behaviours of lead magnesium niobate (Pb[Mg1/3Nb2/3]O3) ceramics have been extensively investigated. In this paper, however, we focused on the dielectric aging of a Mg and Mn doped PMN ceramic under various alternating current (ac) fields. It is found that the strong ac fields generally suppress the aging rate, particularly at low measurement frequencies.

A domain wall model is proposed for relaxor ferroelectrics typified by Pb(Mg1/3Nb2/3. Under a large applied field or a large internal field, domain walls move over a long distance by overcoming localized barriers. This movement is responsible for the hysteresis loop and depolarization at temperatures below T max. The activation volumes obtained by analyzing the coercive field dependence on temperature and frequency suggest that the barriers encountered by the domain walls are of the size of 1000 unit cells, and they increase as the relaxor becomes more like a normal ferroelectric. Since polarization is usually incomplete in relaxors even under a large polarizing field, depolarization readily occurs without the need of nucleating new domains. Domain walls are also responsible for permittivity peaks at high temperature under a weak field. However, without a strong field, domain walls are partially pinned by barriers and can only oscillate within the unpolarized regions between barriers. The mobilit...

Introduction Migratory birds travel spectacular distances each year, navigating and orienting by a variety of means, most of which are poorly understood. Among these is a remarkable ability to perceive the intensity and direction of the Earth's magnetic field (Mouritsen and Ritz, 2005; Wiltschko and Wiltschko, 2006; Johnsen and Lohmann, 2008). Biologically credible mechanisms for the detection of such a weak field (25–65 μT) are scarce, and in recent years just two proposals have emerged as front-runners. One, essentially classical, centers on clusters of magnetic iron-containing particles in the upper beak, which appear to act as a magnetometer for determining geographical position (Kirschvink and Gould, 1981; Kirschvink et al. , 2001; Fleissner et al. , 2007; Solov'yov and Greiner, 2007; Walker, 2008; Solov'yov and Greiner, 2009a, b; Falkenberg et al. , 2010). The other relies on the quantum spin dynamics of transient photoinduced radical pairs (Schulten et al. , 1978; Schulten, 1982; Schulten and Windemuth, 1986; Ritz et al. , 2000b; Cintolesi et al. , 2003; Moller et al. , 2004; Mouritsen et al. , 2004; Heyers et al. , 2007; Liedvogel et al. , 2007b, a; Solov'yov et al. , 2007; Feenders et al. , 2008; Maeda et al. , 2008; Solov'yov and Schulten, 2009; Ritz et al. , 2009; Rodgers and Hore, 2009; Zapka et al. , 2009). Originally suggested by Schulten in 1978 (Schulten et al. , 1978) as the basis of the avian magnetic compass sensor, this mechanism gained support from the subsequent observation that the compass is light dependent (Wiltschko et al. , 1993) (for a review see e.g. (Wiltschko et al. , 2010)).

We develop a quantum-mechanical approach to the photoassociation phenomenon in a sample of cold atoms initially at thermal equilibrium with temperature T. We calculate the rate of formation of molecules in the weak field regime using a perturbative approach. Analytical expressions are obtained for the overlap between the initial and final molecular wavefunctions, and are shown to agree with numerical calculations. The photoassociation rate is found to decrease with increasing atomic mass m, from Li to Cs. Also considered is the heating of the atomic sample through spontaneous photodissociation.

Two formulas are obtained for the weak-field Hall conductivity based on different configurations of a magnetic field in the long-wavelength limit: \(\sigma _{xy}^{(x)}\) and \(\sigma _{xy}^{(y)}\) ...

The many-electron weak-field asymptotic theory of tunneling ionization including the first-order correction terms in the asymptotic expansion of the ionization rate in field strength was highlighted in our recent fast track communication (Trinh et al 2015 J. Phys. B: At. Mol. Opt. Phys. 48 061003) by demonstrating its performance for two-electron atoms. Here we present a thorough derivation of the first-order terms omitted in the previous publication and provide additional numerical illustrations of the theory.

Bi1.7Pb0.3Sr2Ca2Cu3O10-y samples prepared by the glass precursor route were examined. A.c. susceptibility properties were studied and compared to those of samples obtained by the solid-state route. The interconnected lattice of 2223 needle-like grains in a matrix of strontium, calcium, and copper small and globular precipitates of irregular shape leads to an interesting behaviour of the critical current density as a function of d.c. field: there is high intergrain Jc and weak field dependence (Jc > 105 A/cm2 at 77 K and 0 T), in contrast to Jc values and field dependence of classical solid-state route samples. It can thus be claimed (unambiguously now) that the intricate superconducting grain boundary structure acts as the ingredient for improved pinning at low d.c. field at least in such systems.

The preparation of thick films of the NdBa 2 Cu 3 O y (Nd-123) phase by using partial-melting techniques (PMT) of powders deposited on MgO substrates by drying alcoholic suspensions is reported. The effects of the starting composition and processing conditions (temperature and annealing time) on the superconducting properties of the Nd 1+ x Ba 2 Cu 3 O y (0.0≤ x ≤0.50) system were investigated. An improvement of the quality of the films in the NdBaCuO system, as far as the microstructure and magnetic properties are concerned, was observed in the samples with nonstoichiometric starting compositions; the growth of the Nd-123 phase with tetragonal symmetry was detected for x = 0.5. The magnetization measurements, performed on samples annealed in O 2 , showed a T c as high as 91.5 K and a weak field dependence due to the effectiveness of the pinning centers.

It has been shown that coherence effects have a marked influence in the spontaneous emission spectrum of a three-level -type atom driven by weak coherent and incoherent fields. Phase dependent evolution of interference effects leading to spectral narrowing, generation of spectral hole and dark line are exhibited in the present scheme when the atom does not interact with the incoherent fields. The basic mechanism underlying this scheme seems to be appropriate for a phaseonium. Apart from phase-coherence introduced in the system the phenomenon of line narrowing, in the presence of weak incoherent pumping, can be achieved in a different way as a consequence of two competitive resonant effects: sharp non-Lorentzian and symmetric Fano-like-resonance contributions to the line shape. In both the situations, the evolution of narrow structures in the line shape can be achieved even when the emission is influenced by the dephasing of Raman coherence.

We have undertaken a study of the propagation of carriers in one-dimensional (1D) aperiodic systems within the tight-binding scheme under the action of electric fields. We have concentrated on the Fibonacci (F) and Thue-Morse (TM) lattices, which are of great practical importance since these structures can be fabricated thanks to recent technological advances. We show that superdiffusion takes place for both lattices in the field-free case. The mean-square displacement (MSD) follows the law 〈${\mathit{n}}^{2}$〉\ensuremath{\propto}${\mathit{t}}^{\mathrm{\ensuremath{\alpha}}}$ with \ensuremath{\alpha}=1.55 for the F lattice and \ensuremath{\alpha}=1.65 for the TM lattice. When the field is included, the particle localizes, i.e., the MSD is bound, even for weak field intensities.