Influence of γ-ray-induced effects on dielectric dispersion of CuO-doped calcium fluoroborophosphate glass system

γ-Ray-induced dielectric dispersion in CaF₂–B₂O₃–P₂O₅ glasses doped with different concentrations of CuO was investigated. The glass samples were exposed to γ-rays with dose varying within the range 0–10 kGy. The dielectric dispersion and spectroscopic properties were measured before and after γ-ray treatment. Additionally, thermoluminescence studies were performed on post-irradiated glass samples. The results of dielectric properties and dielectric breakdown strength indicated a substantial increase in the insulating strength of CuO containing glasses due to γ-ray irradiation. The analysis of these results together with UV-vis optical absorption, IR spectra, and thermoluminescence studies have indicated a gradual increase in the concentration of mono-valent copper ions due to γ-ray treatment of the glass network. The additional studies have confirmed that these Cu⁺ ions occupy network-forming positions, increase the polymerization of the borophosphate glass network, and facilitates for the increase of insulating strength of the titled glass.     

Inclusion Complexation and Dissolution Properties of Nimesulide and Meloxicam–hydroxypropyl-β-cyclodextrin Binary Systems

The purpose of the work is physicochemical characterization of nimesulide (NI) and meloxicam (ME)–hydroxypropyl-β-cyclodextrin (HP-β-CD) binary systems both in solution and solid states and to improve the pharmaceutical properties of NI and ME via inclusion complexation with HP-β-CD. Binary systems of NI and ME with HP-β-CD have been characterized both in solution and solid state by different physicochemical methods. Three types of drug–HP-β-CD binary systems, namely physical mixtures (PM), kneaded systems (KS) and co evaporated systems (CS) in 1:1 and 1:2 molar ratios (1:1 and 1:2 M) were prepared. Phase solubility and ¹H-NMR spectroscopic studies in solution state revealed 1:1 M complexation of NI and ME with HP-β-CD. A partial inclusion of NI with HP-β-CD at both molar ratios of kneaded and co evaporated systems and a true inclusion of ME with HP-β-CD at both molar ratios of co evaporated systems in solid state was confirmed by differential scanning calorimetry (DSC), powder X-ray diffractometry (powder X-RD) and scanning electron microscopy (SEM) studies. Dissolution properties of NI and ME–HP-β-CD binary systems were superior when compared to corresponding pure drugs. The aqueous solubility and dissolution properties of NI and ME can be improved by inclusion complexation with HP-β-CD. Author for correspondence: E-mail: nbnaid2@E-mail.uky.edu     

Highly enantioselective Henry reaction catalyzed by a new chiral C2-symmetric N,N′-bis(isobornyl)ethylenediamine–copper complex

A new chiral C₂-symmetric N,N′-bis(isobornyl)ethylenediamine–copper complex is found to be an efficient catalyst in the enantioselective Henry reaction between nitromethane and various aldehydes to provide β-hydroxy nitroalkanes with high chemical yield (up to 95%) and high enantiomeric excess (up to 90%).     

Nonlinear Dynamic Stability of Normal and Arthritic Greyhounds

In this paper the dynamic stability of greyhound gait was analyzed within the framework of nonlinear dynamics theory. A video based motion analysis system was utilized to obtain the kinematic data of the hindlimb joints of greyhounds at trot. Phase plane portraits and first return maps for the coxofemoral, femorotibial, and the tarsal joints were calculated from averaged kinematic data for each dog. The analysis was based on the assumption that the steady state dog locomotion could be represented as a nonlinear periodic system. Using the Floquet theory, the dynamic stability of gait was quantified by computing the characteristic multipliers from experimental data. A stability index based on multipliers was used for comparison between normal and arthritic dogs. Phase plane portraits and first return maps of the dogs with transient synovitis were compared with the averaged portraits of the normal dogs. It was observed that the coxofemoral angle exhibited the maximum difference while the femorotibial and the tarsal joints showed little or no difference from those of the normals. Comparison of the Floquet multipliers indicated that the dogs with synovitis had a less stable gait than that of the normal dogs.     

Biocatalytic Self‐Assembly of Supramolecular Charge‐Transfer Nanostructures Based on n‐Type Semiconductor‐Appended Peptides

The reversible in situ formation of a self‐assembly building block (naphthalenediimide (NDI)–dipeptide conjugate) by enzymatic condensation of NDI‐functionalized tyrosine ( NDI‐Y ) and phenylalanine‐amide ( F‐NH₂ ) to form NDI‐YF‐NH₂ is described. This coupled biocatalytic condensation/assembly approach is thermodynamically driven and gives rise to nanostructures with optimized supramolecular interactions as evidenced by substantial aggregation induced emission upon assembly. Furthermore, in the presence of di‐hydroxy/alkoxy naphthalene donors, efficient charge‐transfer complexes are produced. The dynamic formation of NDI‐YF‐NH₂ and electronic and H‐bonding interactions are analyzed and characterized by different methods. Microscopy (TEM and AFM) and rheology are used to characterize the formed nanostructures. Dynamic nanostructures, whose formation and function are driven by free‐energy minimization, are inherently self‐healing and provide opportunities for the development of aqueous adaptive nanotechnology.     

Charge and Spin Transport in an Organic Molecular Square

Understanding electronic communication among multiple chromophoric and redox units requires construction of well‐defined molecular architectures. Herein, we report the modular synthesis of a shape‐persistent chiral organic square composed of four naphthalene‐1,8:4,5‐bis(dicarboximide) (NDI) sides and four trans‐1,2‐cyclohexanediamine corners. Single crystal X‐ray diffraction reveals some distortion of the cyclohexane chair conformation in the solid state. Analysis of the packing of the molecular squares reveals the formation of highly ordered, one‐dimensional tubular superstructures, held together by means of multiple [C H⋅⋅⋅OC] hydrogen‐bonding interactions. Steady‐state and time‐resolved electronic spectroscopies show strong excited‐state interactions in both the singlet and triplet manifolds. Electron paramagnetic resonance (EPR) and electron‐nuclear double resonance (ENDOR) spectroscopies on the monoreduced state reveal electron sharing between all four NDI subunits comprising the molecular square.