Thermodynamic Studies on the Interaction of Dioxopromethazine to β-Cyclodextrin and Bovine Serum Albumin

The interaction of dioxopromethazine (DOPM) with beta-cyclodextrin (beta-CD) and bovine serum albumin (BSA) were investigated by fluorescence quenching method. It was shown that DOPM has quite a strong ability to quench the fluorescence launching from BSA by reacting with it and forming a certain kind of new compound. The quenching and the energy transfer mechanisms were discussed, respectively. The binding constants and thermodynamic parameters at four different temperatures, the binding locality, and the binding power were obtained. The conformation of BSA was discussed by synchronous and three-dimensional fluorescence techniques. The inclusion reaction between beta-CD and DOPM was explored by both Lineweaver-Burk equation and Benesi-Hildebrand equation. The inclusion constants and the thermodynamic parameters at 297 and 307 K were figured out, respectively. The mechanism of inclusion reaction was speculated and the slow release characteristics of beta-CD to DOPM was attempted to explain at molecule level.     

Alteration of the Binding Strength of Dronedarone with Bovine Serum Albumin by β-Cyclodextrin: A Spectroscopic Study

We report the influence of β-cyclodextrin on the binding of the drug dronedarone with bovine serum albumin. The stoichiometry, the binding constant, and the mode of binding of the derivative with β-cyclodextrin are studied by UV–Visible absorption, fluorescence, and 2 Dimensional Rotating Frame Overhauser Effect Spectroscopy (2D ROESY NMR) spectroscopic techniques. The structure of the 1:1 inclusion complex is proposed. The binding of free dronedarone with bovine serum albumin and β-cyclodextrin-bound dronedarone are studied by fluorescence quenching and Förster resonance transfer. The decreased magnitude of the Stern–Volmer constant and the binding constant for the interaction of dronedarone with bovine serum albumin in the presence of β-cyclodextrin are articulated. The donor-to-acceptor distances in the presence and the absence of β-cyclodextrin are compared. The binding sites of the dronedarone with bovine serum albumin are reported by molecular modeling. Dronedarone binds to the sub-domain III of bovine serum albumin. The 3-(dibutylaminopropoxy)benzoyl moiety of dronedarone binds with bovine serum albumin. Encapsulation with β-cyclodextrin decreases the binding strength of dronedarone with bovine serum albumin.     

Solvent Effects on the Photophysical Properties of a Donor–acceptor Based Schiff Base

Journal of Fluorescence - In this work, a donor–acceptor substituted aromatic system ((E)-N-((E)-3-(4 (dimethylamino)phenyl) allylidene)-4-(trifluoromethyl) benzenamine (DPATB) has been...     

Displacement Reaction Using Ibuprofen in a Mixture of Bioactive Imidazole Derivative and Bovine Serum Albumin—a Fluorescence Quenching Study

The mutual interaction of imidazole derivative (PIPP) with bovine serum albumin (BSA) was investigated using photoluminescent studies. The fluorescence quenching mechanism of BSA by PIPP was analyzed and the binding constant was calculated. The binding distance between PIPP and BSA was obtained based on the theory of Forester’s non-radiation energy transfer. Displacement experiments were performed by using ibuprofen to identify PIPP binding site in BSA. The effect of some common ions on the binding constant between PIPP and BSA was also examined.     

Quenching of the Intrinsic Fluorescence of Human Serum Albumin by Trimethoxyphenylfluorone–Mo(VI) Complex

The interaction mechanism between trimethoxyphenylfluorone (TM‐PF)–molybdenum [Mo(VI)] complex and human serum albumin (HSA) has been investigated using fluorescence method. The binding constants were measured at different temperature. Based on the theory of Förster energy transfer, the binding distance and the energy transfer efficiency between TM‐PF–Mo(VI) complex and HSA were obtained. According to the thermodynamic parameters, the main sorts of binding force can be judged. The results indicate that HSA and TM‐PF–Mo(VI) complex have strong interactions. The mechanism of quenching belongs to static quenching, and the main sorts of binding force are van der Waals force and H‐bonding.     

Studies on the Interaction of Tricyclazole with β-cyclodextrin and human Serum Albumin by Spectroscopy

The interaction of tricyclazole (TCZ) with β-cyclodextrin (β-CD) and human serum albumin (HSA) were studied by fluorescence spectrum, UV-visible spectrum and second-order scattering technology. It was shown that TCZ has quite a strong ability to quench the fluorescence launching from HSA by reacting with it and forming a certain kind of new compound. The quenching and the energy transfer mechanisms were discussed, respectively. The binding constants and thermodynamic parameters at four different temperatures, the binding locality, and the binding power were obtained. The conformation of HSA was discussed by synchronous and three-dimensional fluorescence techniques. The inclusion reaction between β-CD and TCZ was explored by scattering method, the inclusion constants and the thermodynamic parameters at 297 K and 311 K were figured out, respectively. The mechanism of inclusion reaction was speculated and linkage among the toxicity of TCZ, the exterior environment and its concentration was attempted to explain on molecule level.     

Quantum-Gravity Thermodynamics, Incorporating the?Theory of Exactly Soluble Active Stochastic Processes, with Applications

A re-visitation of QFT is first cited, deriving the Feynman integral from the theory of active stochastic processes (Glueck and Hueffler, Phys. Lett. B. 659(1–2):447–451, 2008; Hueffel and Kelnhofer, Phys. Lett. B 588(1–2):145–150, 2004). We factor the lie group “generator” of the inverse wavefunction over an entropy-maximizing basis. Performing term-by-term Ito-integration leads us to an analytical, evaluable trajectory for a charged particle in an arbitrary field given a Maximum-Entropy distribution. We generalize this formula to many-body electrodynamics. In theory, it is capable of predicting plasma’s thermodynamic properties from ionic spectral data and thermodynamic and optical distributions. Blessed with the absence of certain limitations (e.g., renormalization) strongly present in competing formalisms and the incorporation of research related to many different phenomena, we outline a candidate quantum gravity theory based on these developments.     

Understanding the high temperature oxidation and ignition behaviour of two-phase Mg–Nd alloys and a comparison to single phase Mg–Nd

The oxidation kinetics and the mechanism of two-phase Mg–Nd alloys were investigated via isothermal heating experiments conducted in dry air at 500 °C for 12 h. The oxidation kinetic curves reveal improved oxidation resistance on neodymium (Nd)-containing alloys compared to pure Mg. A lower mass gain was detected at 2.5-%Nd than at 6-Nd%, which was related to the lower amount of intermetallic phase on the alloy surface. The intermetallic phase has a significant effect on the oxide growth stage. Nd₂O₃ formation on the intermetallic phases creates diffusion paths for oxygen to the metal/oxide interface, affecting both the oxidation kinetics and the oxidation resistance of the alloys. The formation of a Nd-depleted region at the subsurface due to extensive Nd oxidation at the oxide/intermetallic interface lowers the protective ability of the oxide scale. As increasing the Nd content of binary Mg–Nd alloys above 0.5 wt% shifts the alloys from single-phase region to two-phase region, it adversely affects the ignition resistance.     

On the Acid–Base State of the Surface of Semiconductor Components of the ZnSe–CdS System Exposed to Different Media

Using the methods of hydrolytic adsorption, mechanochemistry, and nonaqueous conductometric titration, the acid–base properties of the surfaces of binary semiconductors and solid solutions of the ZnSe?CdS system are studied. The nature of acid sites, and the extent, character, and mechanism of the surface (absorption) interaction are established. The interrelationships in the changes of the acid–base and bulk physical properties upon changing the chemical composition are determined, which make it possible to draw conclusions that are fundamentally important in scientific and practical aspects.     

Structural Changes in Human Serum Albumin According to the Data on the Phosphorescence Kinetics of a Luminescent Probe — Eosin

The influence of the human serum albumin (HSA) denaturation by a surface-active substance (sodium dodecyl sulfate (SDS)) on the phosphorescence of a luminescent probe (eosin) has been investigated. The dependences of the eosin-phosphorescence intensity on the SDS concentration were determined at different pH levels of an HSA solution. It has been shown that at SDS concentrations lower than the critical concentration necessary for micelle formation, the hydrophobic interactions of eosin with the protein influence the deactivation of the eosin triplet states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 660–663, September–October, 2005.     

Effect of zinc concentration on the structural,electrical and magnetic properties of mixed Mn–Zn and Ni–Zn ferrites synthesized by the citrate precursor technique

Mixed manganese-zinc and nickel-zinc ferrites of composition Mn_0.2Ni_0.8−xZn_xFe₂O₄ where x=0.4$x=0.4$, 0.5 and 0.6 have been synthesized by the citrate precursor technique. Decomposition of the precursor at temperatures as low as 500 °C gives the ferrite powder. The ferrites have been investigated for their electrical and magnetic properties such as saturation magnetization, initial permeability, Curie temperature, AC-resistivity and dielectric constant as a function of sintering temperature and zinc content. Structural properties such as lattice parameter, grain size and density are also studied. The mixed compositions exhibited higher saturation magnetizations at sintering temperatures as low as 1200 °C. While the Curie temperature decreased with zinc content, the permeability was found to increase. The AC-resistivity ranged from 10⁵–10⁷ Ω cm and decreased with zinc content and sintering temperature. The dielectric constants were lower than those normally reported for the Mn–Zn ferrites. Samples sintered at 1400 °C densified to about 94% of the theoretical density and the grain size was of the order of about 1.5 μm for the samples sintered at 1200 °C and increased subsequently with sintering temperature.     

Synthesis and Characterization of a Biologically Active Lanthanum(III)–Catechin Complex and DNA Binding Spectroscopic Studies

A lanthanum(III) complex of catechin has been synthesized and characterized by elemental analysis, molar conductance, UV-Vis spectra, infrared spectra, thermal analysis, and ¹H NMR. The complex behaves as a nonelectrolyte in methanol solvent. The spectral and thermal properties of the complex are examined. A thermogravimetric (TGA) study showed the hydrated nature of the complex. ¹H NMR spectra of the lanthanum and the catechin (CT) ligands measured in CD₃OD-d₄ also show metal ligand coordination. The lanthanum–catechin complex shows bright luminescence in methanol solution. The interaction of the complex with calf thymus DNA has been investigated by absorption and emission spectroscopic measurements. Experimental spectral results suggest CT–DNA binding with catechin complex via an intercalative mode.     

Synthesis,Redetermination and Molecular Conformation Analysis of the Structure of 2,2′-Diaminodiphenyl Disulfide

A new synthesis and the crystal structure of C₁₂H₁₂N₂S₂ have been described and redetermined. In order to optimize the geometry of the molecule, the semi empirical methods MNDO, AMI and PM3 were used. The conformation of the energy profile showed that the minimum energy conformation has the torsion angle θ [Cl-Sl-Sl′-Cl′] near 90°. The energy barrier at 0° attributed to the lone pair repulsion of sulphur atoms and interactions between NH…S and H(C6)…S non-bonded atoms.     

Detection of HSO4 − Ion Based on the Hydrolysis of Diketopyrrolopyrrole-derived Schiff Base with Chromogenic and Fluorogenic Dual Signals

A new diketopyrrolopyrrole-based Schiff base L was synthesized and its anion sensing behavior was explored. L showed exclusive response toward HSO₄ ^? ion and also distinguished HSO₄ ^? from other anions by color changes (from dark red to orange) and 21 fold fluorescence enhancement at 370 nm in aqueous solution (THF/H₂O?=?8/1, v/v). The sensing mechanism was suggested to proceed via a hydrolysis process. The results provided colorimetric and fluorimetric assays to selectively detect the presence of a HSO₄ ^? over a wide range of other interfering anions. The results could potentially be used as a dual colorimetric-fluorescent probe for monitoring HSO₄ ^? levels in physiological and environmental systems.     

Thermodynamics,phase transitions and Ruppeiner geometry for Einstein–dilaton–Lifshitz black holes in the presence of Maxwell and Born–Infeld electrodynamics

In this paper, we first obtain the higher-dimen-sional dilaton–Lifshitz black hole solutions in the presence of Born–Infeld (BI) electrodynamics. We find that there are two different solutions for the cases of \(z=n+1\) and \(z\ne n+1\) where z is the dynamical critical exponent and n is the number of spatial dimensions. Calculating the conserved and thermodynamical quantities, we show that the first law of thermodynamics is satisfied for both cases. Then we turn to the study of different phase transitions for our Lifshitz black holes. We start with the Hawking–Page phase transition and explore the effects of different parameters of our model on it for both linearly and BI charged cases. After that, we discuss the phase transitions inside the black holes. We present the improved Davies quantities and prove that the phase transition points shown by them are coincident with the Ruppeiner ones. We show that the zero temperature phase transitions are transitions in the radiance properties of black holes by using the Landau–Lifshitz theory of thermodynamic fluctuations. Next, we turn to the study of the Ruppeiner geometry (thermodynamic geometry) for our solutions. We investigate thermal stability, interaction type of possible black hole molecules and phase transitions of our solutions for linearly and BI charged cases separately. For the linearly charged case, we show that there are no phase transitions at finite temperature for the case \( z\ge 2\). For \(z<2\), it is found that the number of finite temperature phase transition points depends on the value of the black hole charge and there are not more than two. When we have two finite temperature phase transition points, there is no thermally stable black hole between these two points and we have discontinuous small/large black hole phase transitions. As expected, for small black holes, we observe finite magnitude for the Ruppeiner invariant, which shows the finite correlation between possible black hole molecules, while for large black holes, the correlation is very small. Finally, we study the Ruppeiner geometry and thermal stability of BI charged Lifshtiz black holes for different values of z. We observe that small black holes are thermally unstable in some situations. Also, the behavior of the correlation between possible black hole molecules for large black holes is the same as for the linearly charged case. In both the linearly and the BI charged cases, for some choices of the parameters, the black hole system behaves like a Van der Waals gas near the transition point.     

About the luminescence properties of YAG∶Nd,Ce and YAG∶Nd single crystals and their relation to laser properties

Laser excited luminescence studies of various YAGNd, Ce and YAG:Nd (with an excess of yttrium) single crystals together with a testing of laser properties of rods made from the same crystals have been investigated in this paper. It was observed that laser pulse energies increase with increasing halfwidths of the luminescence spectral bands. This dependence and other observations indicate that local structure changes or Nd³⁺ nonequivalent centres are present in the studied crystals. Various mechanisms leading to the formation of Nd³⁺ nonequivalent centres are discussed and it seems that the more probable mechanism is oxygen segregation and diffusion.     

A Preliminary Study of the Relationship between Lewis Acid–Base Parameters and Structure of Polymers

Acid–base theory is an important method to describe the interaction between materials. The inverse gas chromatography (IGC) technique can be used to measure the surface Lewis acid–base parameters of materials. Compared with the solubility parameter method, the merit of the IGC technique is that it can give the surface acid–base properties of many undissolvable materials, such as inorganic materials, metal‐oxides, and thermosetting polymers. In this paper, six polymers are chosen to discuss the rationality of their Lewis acid–base parameters from the molecular structure viewpoint. Compared with some small molecules, the values of these polymers are reasonable. However, endowing each group with a set of acid–base parameters is impossible at this stage because of the lack of sufficient data. Thus more characterization work is needed to develop the IGC method.     

Influence of manganese substitution and annealing temperature on the formation,microstructure and magnetic properties of Mn–Zn ferrites

The effects of annealing temperature and manganese substitution on the formation, microstructure and magnetic properties of Mn_xZn_1−xFe₂O₄ (with x varying from 0.3 to 0.9) through a solid-state method have been investigated. The correlation of the microstructure and the grain size with the magnetic properties of Mn–Zn ferrite powders was also reported. X-ray diffraction (XRD), a scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM) were utilized in order to study the effect of variation of manganese substitution and its impact on crystal structure, crystalline size, microstructure and magnetic properties of the ferrite powders formed. The XRD analysis showed that pure single phases of Mn–Zn ferrites were obtained by increasing the annealing temperature to 1200–1300 °C. Increasing the annealing temperature to ?1300 °C led to abnormal grain growth with inter-granular pores and this led to a decrease in the saturation magnetization. Moreover, an increase in the Mn²⁺ ion substitution up to x=0.8 increased the lattice parameter of the formed powders due to the high ionic radii of the Mn²⁺ ion. Mn–Zn ferrites phases were formed and the positions of peaks were shifted by substituting manganese. The average crystalline size was increased by increasing the annealing temperature and decreased by increasing the substitution by manganese up to 0.8. The average crystalline size was in the range 95–137.3 nm. The saturation magnetization of the Mn–Zn-substituted ferrite powders increased continuously with an increase in the Mn concentration up to 0.8 at annealing temperatures of 1200–1300 °C. Further increase of Mn substitution up to 0.9 led to a decrease of saturation magnetization. The saturation magnetization increased from 17.3 emu/g for the Mn_0.3Zn_0.7Fe₂O₄ phase particles produced to 59.08 emu/g for Mn_0.8Mn_0.2Fe₂O₄ particles.     

Influence of CuO and sintering temperature on the microstructure and magnetic properties of Mg–Cu–Zn ferrites

The synthesis of a series of Mg–Cu–Zn ferrites with the substitution of Cu for Mg has been obtained by solid-state reaction method. Microstuctural and structural analyses were carried out using a scanning electron microscope and X-ray diffraction (XRD), respectively. The lattice parameter is found to increase with increasing copper content. A remarkable densification is observed with the addition of Cu ions in the ferrites. Microstructural analyses indicate that CuO influences the microstructure of the ferrites by the formation of liquid phase during sintering. The grain size significantly increases with increasing copper content. Exaggerated grain growth is observed for the samples of x=0.25–0.35. The initial magnetic permeability (μ′) increases sharply with increasing concentration of Cu ions. This increase in μ′ is explained with the grain growth mechanism and enhanced densification of the ferrites. The resonance frequency of all the samples shifts toward the lower frequency as the permeability increases with Cu content. Sintering temperature T_s also affects the densification, grain growth and initial magnetic permeability of the samples.