Entanglement in S states of two-electron quantum dots with Coulomb impurities at the center

We study a system of two Coulombically interacting electrons in an external harmonic potential in the presence of an on-centre Coulomb impurity. Detailed results for the dependencies of the reduced von Neumann entropy on the control parameters of the system are provided for both the ground state and the triplet S states with the lowest energy. Among other features, it is found that in the weak confinement regime the entanglement is strongly affected by the presence of an acceptor impurity.     

CW DFB RT diode laser-based sensor for trace-gas detection of ethane using a novel compact multipass gas absorption cell

The development of a continuous wave, thermoelectrically cooled (TEC), distributed feedback diode laser-based spectroscopic trace-gas sensor for ultra-sensitive and selective ethane (C₂H₆) concentration measurements is reported. The sensor platform used tunable diode laser absorption spectroscopy (TDLAS) and wavelength modulation spectroscopy as the detection technique. TDLAS was performed using an ultra-compact 57.6 m effective optical path length innovative spherical multipass cell capable of 459 passes between two mirrors separated by 12.5 cm and optimized for the 2.5–4 μm range TEC mercury–cadmium–telluride detector. For an interference-free C₂H₆ absorption line located at 2,976.8 cm^?1, a 1σ minimum detection limit of 740 pptv with a 1 s lock-in amplifier time constant was achieved.     

Cu(II)-imprinted styrene-divinylbenzene beads as a new sorbent for flow injection-flame atomic absorption determination of copper

The paper reports preparation and analytical features of a new Cu(II)-imprinted polymer, based on salen-OMe ligand 2,2′-[ethane-1,2-diylbis(nitrilo(E)methylylidene)]bis(6-allyl-4-methoxyphenol) and styrene-divinylbenzene matrix, as well as its application to on-line preconcentration and flame atomic absorption determination of copper. Sorbent beads (average diameter of 60-80 µm) were obtained using suspension polymerization technique and employed as a column filling. Copper sorption was the most effective at pH 6.8, whereas the highest elution effectiveness was observed when 0.5% HNO₃ was applied. The sorbent exhibited good long-term stability and acid resistance. Enrichment factor (EF) of 12 was found for 60 s loading time and loading flow rate of 4 mL min^− 1. EF value may be further increased by expanding the loading time and/or flow rate. Batch sorbent capacity in optimal pH conditions was found to be 0.16 mmol g^− 1 (9.55 mg g^− 1) of a dry polymer. Calcium(II) turned out to be the only significant interferent. Cadmium(II), silver(I), nickel(II), zinc(II) in concentrations lower than about 1 mg L^− 1 did not disturb copper(II) preconcentration. Different calibration methods such as: set of standards method (SSM), standard addition method (SAM) and combinatory calibration method (CCM) were employed for copper(II) determination in tap water, spring mineral water and certified reference material. Analysis of EU-H-3 reference material confirmed good accuracy of the proposed method. Relative standard deviation (RSD) was 3.2 for standard addition method and 2.8% for set of standard calibration method. Detection limit for sample consumption 16 mL was 1.03 and 1.07 µgL^-1 respectively.     

LIF excitation spectra for S0 → S1 transition of deuterated anthranilic acid COOD, ND2 in supersonic-jet expansion

Laser induced fluorescence (LIF) excitation spectrum for the S₀ → S₁ transition of anthranilic acid molecules deuterated in the substituent groups (COOD, ND₂) was investigated. Analysis of the LIF spectrum allowed for the assignment of the six most prominent fundamental in-plane modes of frequencies up to ca. . The experimental results show good correlation with the frequency changes upon deuteration computed with CIS (CI-Singles) and TD-DFT for the S₁ state. Deuteration induced red-shifts of the identified fundamental bands are used for examination of the alternative assignments proposed in earlier studies. Potential energy distributions (PED) and overlaps of the in-plane normal modes with frequencies below indicate that the correspondence of the respective vibrations of the deuterated and non-deuterated molecule is very good. A blue-shift of the 00 transition due to the isotopic substitution, is equal to . This relatively large value is caused primarily by a significant decrease of the N-H stretching frequency associated with the increase of strength of the intramolecular hydrogen bond upon the electronic excitation. The deuteration shift of the 00 band was interpreted in terms of the differences of the zero point energy (ZPE) between the S₀ and S₁ electronic states, computed with DFT and TD-DFT methods, respectively.     

The impact of a carbon nanotube on the cholesterol domain localized on a protein surface

The influence of a single walled carbon nanotube on the structure of a cholesterol cluster (domain) developed over the surface of the endothelial protein 1LQV has been investigated using the classical molecular dynamics (MD) simulation technique. We have observed a substantial impact of carbon nanotube on the arrangement of the cholesterol domain. The carbon nanotube can drag out cholesterol molecules, remarkably reducing the volume of the domain that settles down on the protein.     

Surface tension and density of liquid Sn-Cu alloys

The surface tension and density of Sn-Cu liquid alloys were measured with the sessile drop method, in a broad range of temperature. Total of seven compositions were investigated in the range from 0.018 to 0.5 mole fraction of Cu. With increasing concentration of Cu, both density and the surface tension are increased. With increasing temperature the density decreases linearly for all of the compositions. The surface tension exhibits similar behavior for most of the compositions, except for the alloy of 0.5 mole fractions of Cu, in which case the increase of the surface tension is observed. The obtained results are compared with existing literature data and Butler model calculations, and a relatively good agreement is observed.     

A new mesogenic fluorene derivative: 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene

The title compound, 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene, is a new mesogenic compound containing the fluorene moiety. It exhibits a monotropic nematic liquid crystalline behaviour, with isotropisation temperature of 53°C. The compound is also polymorphic in the solid state, with one crystal phase melting at 103°C and another one melting at 71°C. The crystal and molecular structure of the high melting solid phase have been determined from single crystal X-ray diffraction analysis. Crystals are monoclinic, with cell dimensions a = 16.649(6) Å, b = 8.305(3) Å, c = 24.598(7) Å, β = 111.60(2)?, space group P2₁/c and four molecules in the unit cell. Refinement leads to R = 0.0558. The two terminal alkyl chains and one phenyl ring are disordered over two split positions. The imbricated molecular packing observed in the solid state seems to resemble that of the nematic phase that is formed upon cooling the melt.     

Cube-like complexes,Steinhaus’ chains and the Poincaré–Miranda theorem

We discuss combinatorial results allowing to prove a new, more general version of the Poincaré–Miranda fixed point theorem. The main tool is the Steinhaus’ chain property.