pH‐Responsive Relaxometric Behaviour of Coordination Polymer Nanoparticles Made of a Stable Macrocyclic Gadolinium Chelate

Lanthanide‐containing nanoscale particles have been widely explored for various biomedical purposes, however, they are often prone to metal leaching. Here we have created a new coordination polymer (CP) by applying, for the first time, a stable Gd^III chelate as building block in order to prevent any fortuitous release of free lanthanide(III) ion. The use of the Gd‐DOTA‐4AmP complex as a design element in the CP allows not only for enhanced relaxometric properties (maximum r₁=16.4 mm ^?1 s^?1 at 10 MHz), but also for a pH responsiveness (Δr₁=108 % between pH 4 and 6.5), beyond the values obtained for the low molecular weight Gd‐DOTA‐4AmP itself. The CP can be miniaturised to the nanoscale to form colloids that are stable in physiological saline solution and in cell culture media and does not show cytotoxicity.     

Ferroelectric properties of a nonequilibrium electron gas

We show that a quasi-two-dimensional electron gas in a strong, attracting electric fieldE _x acquires ferroelectric properties. At certain temperatures, a transverse electric fieldE _y can arise spontaneously via a nonequilibrium phase transition. The Curie temperature is determined by|E _x |. Volgogradskii State Teachers University, Platan Scientific Research Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 72–79, April, 1998.     

Peculiarities of the phase behavior of liquid-crystal mixtures at the Cholesteric → Smectic (Ch → Sm) transition boundary

It is found that an interphase state, characterized by a large Bragg reflection coefficient, is formed in smectogenic cholesteric liquid-crystal mixtures at the Ch-Sm transition boundary. The interrelation between the mixture composition and the optical and spectral characteristics is studied. A possible structure of the interphase state is proposed.     

Vibrational spectra and structural dynamic models of halosubstituted formaldehyde

The DFT/B3LYP method with 6-31G*(**) basis sets has been used to analyze the vibrational spectra of halo-substituted formaldehyde in the anharmonic approximation. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 683–686, September–October, 2006.     

Ageing in granular aluminium insulating thin films

We present a new set of electrical field effect measurements on granular aluminium insulating thin films. We have explored how the conductance relaxations induced by gate voltage changes depend on the age of the system, namely the time elapsed since its quench at low temperature. A clear age dependence of the relaxations is seen, qualitatively similar to ageing effects seen in other well studied glassy systems such as spin glasses or polymers. We explain how our results differ from the previous ones obtained with different protocols in indium oxide and granular aluminium thin films. Our experimental findings bring new information on the dynamics of the system and put new constraints on the theoretical models that may explain slow conductance relaxations in disordered insulators.     

Observation of dynamical effects in diffuse neutron scattering by the three-crystal spectrometer method

Anomalous angular distributions of the diffuse elastic neutron scattering intensity, which indicate a dynamical character of the scattering near a reciprocal-lattice site, are discovered for low-dislocation-density Ge crystals. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 4, 237–240 (25 February 1996)     

Improving on the minimum risk equivariant estimator of a location parameter which is constrained to an interval or a half-interval

For location families with densitiesf ₀(x−θ), we study the problem of estimating θ for location invariant lossL(θ,d)=ρ(d−θ), and under a lower-bound constraint of the form θ≥a. We show, that for quite general (f ₀, ρ), the Bayes estimator δ _U with respect to a uniform prior on (a, ∞) is a minimax estimator which dominates the benchmark minimum risk equivariant (MRE) estimator. In extending some previous dominance results due to Katz and Farrell, we make use of Kubokawa'sIERD (Integral Expression of Risk Difference) method, and actually obtain classes of dominating estimators which include, and are characterized in terms of δ _U . Implications are also given and, finally, the above dominance phenomenon is studied and extended to an interval constraint of the form θ∈[a, b]. Research supported by NSERC of Canada.     

Extraction of current carriers by photons in a quantum well

The extraction of holes by photons in an infinitely deep semiconductor quantum well is studied. Both interzone and intersubzone optical transitions, which make separate contributions to this effect, are examined. In calculating the extraction current, it is assumed that the optical transition probability depends on the photon momentum only as a result of its appearance in the energy and momentum conservation laws. Fiz. Tverd. Tela (St. Petersburg) 40, 1710–1711 (September 1998)