A Fluorescence Study of New Angular Polycyclic Blue Light-Emitting pyrazolo[3,4-<Emphasis Type="Italic">h</Emphasis>][1,6]naphthyridine and their Interaction with Bovine Serum Albumin (BSA)

The blue light-emitting pyrazolo[3,4-h][1,6]naphthyridines has been synthesized by Friedländer condensation of 4-amino-3-(4-phenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbaldehyde (o-aminoaldehyde) 1 with different cyclic ketones and 1,3-diketones. The synthesized angular polycyclic naphthyridine derivatives were studied for Semi-empirical, thermal, UV–vis and fluorescence spectroscopic properties on binding with bovin serum albumin (BSA). These fluorescence properties together with the neutral, hydrophobic nature of these compounds make these fluorophores good fluorescence probe for studying the micropolarity of proteins like BSA and in general the ligand-protein interactions. All of them displays bright absorption at 394 nm &; emission in visible region (491 nm). Quantum yields of all synthesized compounds were calculated.     

Thin ferroelectric Nd-doped BiFeO<Subscript>3</Subscript> films with orthorhombic structure

X-ray diffraction and Raman spectroscopy of epitaxial Nd-doped bismuth ferrite films on MgO substrates reveal their orthorhombic symmetry Fmm2 (a = 7.914 Å, b = 7.913 Å, and c = 7.937 Å).     

Structural transformations of K<Subscript>3</Subscript>H(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> crystals with variations in temperature

Single crystals of the K₃H(SO₄)₂ compound are investigated using X-ray diffraction on Xcalibur S and Bruker diffractometers. The structure of the low-temperature monoclinic phase is refined (space group C2/c, z = 4, a = 14.698(1) Å, b = 5.683(1) Å, c = 9.783(1) Å, β = 103.01(1)°, T = 293 K, Bruker diffractometer), the structural phase transition is revealed, and the structure of the high-temperature trigonal phase is determined (space group R \(\bar 3\) m, z = 3, a = 5.73(1) Å,c = 21.51(1) Å,T = 458 K, Xcalibur diffractometer).     

Thiourea-doped ammonium dihydrogen phosphate: A single crystal neutron diffraction investigation

Thiourea-doped ammonium dihydrogen phosphate (TADP) exhibits nonlinear optical property and the second harmonic generation efficiency of these crystals is three times that of pure ammonium dihydrogen phosphate (ADP) crystal. In this context, the study of structural distortion in the thiourea-doped ADP crystal is significant, hence single neutron diffraction investigations were undertaken. The final R-factors are: R[F ² > 2σ(F ²)] = 0.11, Goodness of fit(S) = 1.15. Though the dopant could not be located from the difference Fourier map, the cell parameters (a = b = 7.531(3) A, c = 7.544(5) Å) were found to be significantly greater than that of pure ADP at RT (a = b = 7.502(1) Å, c = 7.546(1) Å). This indicates that the dopant concentration in the crystals is small but enough to bring changes in the overall average structure.     

Study on the Interaction between Florasulam and Bovine Serum Albumin

In this paper, the interaction between florasulam (FU, 2′,6′,8-trifluoro-5-methoxy [Kragh-Hansen U, Molecular aspects of ligand binding to serum albumin. Pharmacol Rev 33(1):17–53 1981; Carter DC and Ho JX, Structure of serum albumin. Adv Protein Chem 45:153–203 1994; He XM, and Carter DC, Atomic structure and chemistry of human serum albumin. Nature 358(6383):209–215 1992] triazolo [1,5-c]pyrimidine-2-sulfonanilide) and bovine serum albumin (BSA) was investigated by fluorescence, ultraviolet absorption (UV) and Far-UV circular dichroism (CD) spectrometries. A strong fluorescence quenching was observed and the quenching mechanism was considered as static quenching. The binding constant of FU with BSA at 299 and 309 K were obtained as 1.5?×?10⁴ and 7.1?×?10³ l mol^?1, respectively. There was one binding site between FU and BSA. The thermodynamic parameters enthalpy change (ΔH) and entropy change (ΔS) were calculated as ?57.89 kJ mol^?1 and ?113.6 J mol^?1 K^?1, respectively, which indicated that the acting force between FU and BSA was mainly hydrogen bond and Van der Waals force. According to the Förster non-radiation energy transfer theory, the average binding distance between donor (BSA) and acceptor (FU) was obtained (r?=?1.59 nm). The investigations of the UV/Vis and CD spectra of the system showed that the conformation of BSA was changed in presence of FU.     

Study of the heavy-fermion compound CeRu<Subscript>2</Subscript>Si<Subscript>2</Subscript> by the small-angle neutron scattering method

In order to directly observe neutron scattering by heavy fermion quasiparticles at low temperatures, a CeRu₂Si₂ single crystal has been studied by the small-angle neutron scattering method. In the experiment, neutron scattering is observed at T = 0.85 K for momentum transfers q ≤ 0.04 Å^?1, which is treated as the orbital component of magnetic scattering by heavy fermion quasiparticles. It has been found that the application of a magnetic field H = 1 T leads to both an increase in the observed scattering and its anisotropy with respect to the field direction. Moreover, measurements in the magnetic field reveal additional scattering for q > 0.04 Å^?1, which is well described by a Lorentzian and is interpreted as neutron magnetic scattering by spin-density fluctuations with a correlation radius R_c ≈ 30 Å.     

A new crystalline HMX polymorph: ɛ-HMX

A new crystalline HMX polymorph, ?-HMX, was obtained. ?-HMX crystals were studied by X-ray structure analysis, optical microscopy, and differential scanning calorimetry. Their space group is P2₁/c. The unit cell parameters are a = 21.799(3) Å, b = 10.913(2) Å, c = 10.819(2) Å, and β = 97.43(2)°, V = 2552.15 ų, Z = 4. ?-HMX molecules are not equivalent in crystals and have chair conformations. The heat of the polymorphic transition of ?-HMX into the δ-polymorph was measured. The transition occurred with the intermediate formation of β-HMX. The dependence between the heats of polymorphic transitions and the densities of crystals of various HMX polymorphs was demonstrated. The character of this dependence was to a substantial extent determined by the type of HMX molecule conformation.     

Synthesis,Crystal Structure and Luminescent Properties of Some Zn(II) Schiff Base Complexes: Experimental and Computational Study

A series of Zn(II)-Schiff bases I, II and III complexes were synthesized by reaction of o-phenylenediamine with 3-methylsalicylaldehyde, 4-methylsalicylaldehyde and 5-methylsalicylaldehyde. These complexes were characterized using FT-IR, UV-Vis, Diffuse reflectance UV-Vis, elemental analysis and conductivity. Complex III was characterized by XRD single crystal, which crystallizes in the triclinic system, space group P-1, with lattice parameters a?=?9.5444(2) Å, b?=?11.9407(2) Å, c?=?21.1732(3) Å, V?=?2390.24(7) ų, D _c ?=?1.408 Mg m^?3, Z?=?4, F(000)?=?1050, GOF?=?0.981, R1?=?0.0502, wR2?=?0.1205. Luminescence property of these complexes was investigated in DMF solution and in the solid state. Computational study of the electronic properties of complex III showed good agreement with the experimental data.     

Synthesis,growth and characterization of L-proline dimercuricchloride single crystals for frequency conversion applications

A semi-organic nonlinear optical L-proline dimercuricchloride (LPDMC) material has been synthesized. LPDMC single crystals were grown from aqueous solution by a slow cooling method. Good quality single crystals of size 19×6×3 mm³ have been grown over a period of 3 weeks. The grown crystals have been subjected to single crystal X-ray diffraction analysis to determine the cell parameters. The title compound crystallizes in the triclinic system with a noncentrosymmetric space group P1 and with unit-cell parameters a=7.2742(4) Å, b=9.4472(5) Å, c=10.4767(6) Å, α=108.621(3)^°, β=107.260(2)^°, γ=97.353(2)^° and volume=631.51(6) Å³. Optical and dielectric properties of the crystals have been studied. The thermal stability of the crystals was determined by thermogravimetric analysis/differential thermal analysis. The second harmonic generation efficiency of the crystals was obtained by the classical powder technique using a Nd:YAG laser and it is found to be 2.5 times that of potassium dihydrogen phosphate.     

Dependence of structure factor and correlation energy on the width of electron wires

The structure factor and correlation energy of a quantum wire of thickness b ? a _B are studied in random phase approximation (RPA) and for the less investigated region r _s < 1. Using the single-loop approximation, analytical expressions of the structure factor are obtained. The exact expressions for the exchange energy are also derived for a cylindrical and harmonic wire. The correlation energy in RPA is found to be represented by ? _c (b, r _s ) = α(r _s )/b + β(r _s ) ln(b) + η(r _s ), for small b and high densities. For a pragmatic width of the wire, the correlation energy is in agreement with the quantum Monte Carlo simulation data.     

Structure and electrophysical properties of ferrocobaltites <Emphasis Type="Italic">Ln</Emphasis>BaFeCoO<Subscript>5 + δ</Subscript> (<Emphasis Type="Italic">Ln</Emphasis> = Tb,Dy, Ho,Y)

The ferrocobaltites LnBaFeCoO^{5 + δ} (Ln = Tb, Dy, Ho, Y) have been synthesized, and the parameters of their crystal structure have been determined. The thermal expansion, electrical resistivity ρ, and thermopower S of the synthesized compounds have been investigated in air at temperatures in the range from 300 to 1100 K. The compounds have a tetragonal structure (symmetry space group P4/mmm) with the unit cell parameters a = 3.9000 Å and c = 7.5922 Å (Ln = Tb, δ = 0.31), a = 3.8973 Å and c = 7.5679 Å (Ln = Dy, δ = 0.34), a = 3.8970 Å and c = 7.5507 Å (Ln = Ho, δ = 0.28), and a = 3.9029 Å and c = 7.5538 Å (Ln = Y, δ = 0.25). The ferrocobaltites under investigation are p-type semiconductors, and their electrical resistivity ρ and thermopower S decrease in the sequence Tb → Ho → Y → Dy (at room temperature). The linear thermal expansion coefficient of the LnBaFeCoO^{5 + δ} phases in the vicinity of the temperatures ranging from 465 to 535 K increases from (1.15?1.23) × 10^?5 to (1.73?1.93) × 10^?5 K^?1. The parameters of charge transfer in these ferrocobaltites have been determined. It has been found that an increase in the temperature leads to an increase in the excitation energy of charge carriers and a decrease in the activation energy of charge carrier transfer.     

Study of ferromagnetic correlations caused by impurities in nonmagnetic materials by the method of small-angle scattering of polarized neutrons

The possibility of the study of ferromagnetic correlations caused by d-metal impurities in nonmagnetic matrices is discussed. The polarization and magnetic-nuclear interference obtained by analyzing the small-angle scattering of polarized neutrons in a CuZn(20) alloy with Ni impurity (1 at %) are reported. It has been shown that Ni is clustered in the CuZn matrix with the characteristic correlation radius in the range 100 Å < R _c < 5000 Å depending on the thermal processing of the samples. The cross correlation function determining magnetic-nuclear interference is satisfactorily approximated by the exponential exp(?r/R _c), where r is the distance. It has been found that the nonmagnetic matrix CuZn(20) with an almost uniform distribution of 1% Ni impurity has metamagnetic properties in the field H ≈ 0.5 T at room temperature.     

Structure,microstructure, and thermopower of highest manganese silicide crystals grown from zinc solution-melt

MnSi_1.71–1.75 single crystals are grown using the combination of solidification from solution-melt and the Bridgman crystal growth technique. The single crystals represent tetrahedral bipyramids and correspond to the highest manganese silicide (HMS) modification with lattice parameters a = b = 5.52(1) Å and c = 65.7(8) Å. The thermopower measured between the parallel faces of these single crystals is anomalously high for plain HMS (180–190 μV/K).     

A quantum-topological analysis of short (strong) H bonds in three-dimensional periodic crystals

The characteristics of the critical electron density points of the O-H···A fragment (A = O or N) in molecular crystals with short H bonds were analyzed in terms of the Bader quantum-topological theory of molecular structure. The wave functions (B3LYP/6-31G** approximation) of the ground state of 26 three-dimensional periodic crystals with experimentally determined structures were used. Intermediate-type interactions separating the limiting cases of covalent and closed shell-type interactions were found to be characterized by the following geometric parameters: 2.45 Å ≤ D(O···O) ≤ 2.6 Å, 1.35 Å ≤ d(H···O) ≤ 1.65 Å, and 1.0 Å ≤ d(O-H) ≤ 1.10 Å. Such interactions are observed in molecular crystals with the O-H···A fragment and high bridge proton mobility. Differences between H···O and H···N interactions were quantitatively characterized by the dependence of ρ _b on d(H···A), where A = O or N. The dependence parameter values were shown to be determined by the nature of the A atom that forms the H bond. The influence of the crystalline environment on systems with strong H bonds manifested itself by changes in the position of the bridge proton. The d(O-H)/d(H···O) ratio was, however, the same for gas-phase complexes and molecular crystals with weakly bent O-H···O fragments (∠O-H···O > 160°).     

On rational functions of first-class complexity

It is proved that, for every rational function of two variables P(x, y) of analytic complexity one, there is either a representation of the form f(a(x) + b(y)) or a representation of the form f(a(x)b(y)), where f(x), a(x), b(x) are nonconstant rational functions of a single variable. Here, if P(x, y) is a polynomial, then f(x), a(x), and b(x) are nonconstant polynomials of a single variable.     

Nitroaniline Isomers Interaction with Bovine Serum Albumin and Toxicological Implications

The interactions of 2-nitroaniline (2-NA), 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA) with bovine serum albumin (BSA) have been investigated by means of fluorescence spectrometry, synchronous fluorescence spectrometry and UV absorption spectrometry under the simulative physiological conditions. Association constants (K _A ) were estimated by the remarkable static quenching effect of 2-NA, 3-NA and 4-NA to the intrinsic fluorescence of BSA, and thermodynamic parameters such as enthalpy change (ΔH) and entropy change (ΔS) were calculated according to van’t Hoff equation. The results show that hydrophobic force plays a main role in the interaction of nitroanilines to BSA, nitroanilines have high affinity to BSA and the affinity order is as follows: 4-NA?>?2-NA?>?3-NA. On the basis of this study, it is found that percents of the binding of nitroanilines to BSA are almost no relative to the concentrations of nitroanilines, and correlation between K _A and logK _ow is disclosed. In the meantime, relationships between the combination of nitroanilines with BSA and toxicological implications were also discussed. In addition, synchronous fluorescence method was used to study the interaction mechanisms between nitroanilines and BSA, and energy transfer distances from BSA to nitroanilines were estimated based on the Förster’s non-radiation energy transfer theory. The results suggest that the binding site for nitroanilines on BSA is close to the sub-domain IIA where Trp 214 is located.     

Effect of desiccant on the performance of green organic light-emitting device

A green organic light-emitting diodes (OLED) with a multilayer structure of indium-tin oxide (ITO)/copper-phthalocyanine (CuPc) (200Å)/N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (α-NPD) (600Å)/N′- diphenyl-N,N′-tris(8-hydroxyquinoline) aluminium (Alq₃) (400Å):10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7- tetrahydro-1H,5H,11H-(l)benzopyropyrano(6,7,8-i, j)quinolizin-11-one (C545T) (2%)/Alq₃ (200Å)/LiF (10Å)/Al (1000Å) was prepared via vacuum thermal evaporation. To reduce the impact of water vapor and oxygen on the device, we encapsulated it with a kind of specific and efficient desiccant, called DESIPASTE, under the protection of high-purity nitrogen. By analyzing a series of optical characteristics of OLEDs, the results showed that this desiccant can improve the brightness about 500 and 250 cd/m² at same driving voltage and current density, respectively. The electroluminescent (EL) spectra were hardly affected except a very weak blue shift of broadband emission peak. It turns out that encapsulation with DESIPASTE is a simple and efficient way to improve the performance of OLED.     

Probing the sign-changeable interaction between dark energy and dark matter with current observations

We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling b by the form b(a) = b_0 a + b_e(1-a), where at the earlytime the coupling is given by a constant b_e and today the coupling is described by another constant b_0. We explore six specific models with(i) Q = b(a)H_0ρ_0,(ii) Q = b(a)H_0ρ_(de),(iii) Q = b(a)H_0ρ_c,(iv) Q = b(a)Hρ_0,(v) Q = b(a)Hρ_(de), and(vi) Q = b(a)Hρ_c.The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements,and the Hubble constant direct measurement. We find that, for all the models, we have b_0 0 and b_e 0 at around the 1σ level,and b_0 and b_e are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the 1σ level, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.     

Structural and electronic properties of solid naphthalene under pressure: density functional calculations

The pressure effect on the geometrical and electronic structures of crystallinenaphthalene is calculated up to 30 GPa by performing density functional calculations. Thelattice parameters a, b, and c, decrease by 1.77 Å (–20.4%), 0.85 Å (–14.1%),and 0.91 Å (–8.2%), respectively, while the monoclinic angle β increasesby 3.95° in this pressureregion. At the highest pressure of 30 GPa the unit cell volume decreases by 62.7%. Thedetailed analysis of the molecular arrangement within crystal structure reveals that themolecular motion becomes more and more localized, and hints towards the evolution ofintermolecular interaction with pressure. Moreover, the electronic structure ofnaphthalene under high pressure is also discussed. A pressure induced decrease of the bandgap is observed.     

Synthesis and electrical conductivity of a new Ag<Subscript>6</Subscript>SnS<Subscript>4</Subscript>Br<Subscript>2</Subscript> superionic compound

The conditions of synthesizing a new Ag₆SnS₄Br₂ compound were studied. The crystallographic parameters of the unit cell were determined as follows: space group Pnma, a=6.67050(10) Å, b=7.82095(9) Å, c=23.1404(3) Å, and Z=4. The total electrical conductivity and its ionic component were measured by a dc probe method in the temperature range 210–380 K. Kinks in the conductivity curve and the differential thermogram of heating the alloy were revealed at 235 K. It was concluded that the mass and charge transfers in the compacted Ag₆SnS₄Br₂ alloy powder have an intragrain character.