Asymmetric leakage in (Ba,Sr)TiO3 nanoparticle/parylene‐C composite capacitors

Nanoparticle polymer composite capacitors have been examined for some time as a route to high performance, printable capacitors. One approach to creating these composites is to use a particle film together with vapor deposited polymers, which can yield high performance, but also forms a structurally asymmetric device. The performance of a nanoparticle (Ba, Sr)TiO₃ (BST)/parylene‐C composite capacitor is compared to that of a nanoparticle BST capacitor without the polymer layer under both directions of bias. The composite device shows a five orders of magnitude improvement in the leakage current under positive bias of the bottom electrode relative to the pure‐particle device, and four orders of magnitude improvement when the top electrode is positively biased. The voltage tolerance of the device is also improved and asymmetric (44 V vs. 28 V in bottom and top positive bias, respectively). This study demonstrates the advantage of this class of composite device construction, but also shows that proper application of the device bias in this type of asymmetrical system can yield an additional benefit. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Copper (II)-Surfactant Complex and Its Nano Analog as Potential Antitumor Agents

The in vitro anticancer activity of copper cetyl trimethyl ammonium bromide (Cu-CTAB)-loaded cyclodextrin nanoparticles on Ehrlich ascites carcinoma (EAC), colon cancer cells (HCT 116), liver cancer cells (HepG-2), breast cancer cells (MCF-7), and cervix cancer cells (Hela) was investigated using MTT due assay. Cyclodextrin nanoparticles loaded with Cu-CTAB exerted in vitro anticancer activity against the previous human cancer cell lines comparable to the activity of free non-entrapped in nanoparticles macro-particle Cu-CTAB. The nano analog was synthesized by physical loading using grinding with ball mill. The ratio between Cu-CTAB and cyclodextrin oligosaccharide was 1 Cu-CTAB: 3 cyclodextrin. The particle size of the nano derivative was determined using the transmitted electron microscope (TEM).     

Synthesis and Preliminary Demulsification Efficiency Evaluation of New Demulsifiers Based on Fatty Oils

Three raw fatty oils were used as precursors for demulsifiers. The hydrolyzed form of each oil was adducted with maleic anhydride then modified by esterification with polyethylene glycols or ethyleneoxide-propyleneoxide block copolymers. The demulsfication efficiency, coalescence rate, some surface active, thermodynamic properties, and partition coefficient of a selected demulsifier were investigated. The best demulsifier shows 100% demulsification after 19 minutes at 300 ppm. A correlation between demulsification efficiency and rheological properties of the investigated demulsifier was investigated. Also, emulsification kinetics were followed by microscopic photography. A mechanism following coalescence and flocculation of water droplets is proposed.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS VI1–5: Utility of Lawesson's Reagent for Synthesis of Thiaphosphorine,Thioxanthene, and Thiaphosphole Derivatives

Arylidene malonate derivatives 2a–c reacted with Lawesson's reagent (1) LR in equimolar ratio to yield the oxathiaphosphorine derivatives 3a–c. The behaviour of LR towards cyclic ketones was also examined and yielded the thioxanthene derivatives 5a,b. On the other hand, arylidene pyrazolone 8 reacted with LR to give the phosphole 10. Aminobenzenethiophene 11 reacted with LR under reflux to produce the corresponding thiazaphosphorine 12.     

Application of circular dichroism spectroscopy in the study of mixed-valence asymmetric ruthenium polypyridyl complexes

Circular dichroism (CD) spectroelectrochemistry is used to determine the extent of singly occupied molecular orbital delocalization in mixed-valence multinuclear complexes, specifically the mixed-valence Ru(II)Ru(III) states of the four diastereoisomers of [(Ru(bpy)(2))(2)(bpt)](3+) [1; bpy = 2,2'-bipyridyl and bpt = 3,5-bis(pyrid-2'-yl)-1,2,4-triazolato anion]. The complex was found to be stable to thermal racemization in the three oxidation states, but photoracemization in the Ru(II)Ru(II) state was observed.     

Biodegradable Nanoparticles Loaded with Levodopa and Curcumin for Treatment of Parkinson’s Disease

Background: Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. Levodopa (L-DOPA) remains the gold-standard drug available for treating PD. Curcumin has many pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anti-amyloid, and antitumor properties. Copolymers composed of Poly (ethylene oxide) (PEO) and biodegradable polyesters such as Poly (ε-caprolactone) (PCL) can self-assemble into nanoparticles (NPs). This study describes the development of NH₂–PEO–PCL diblock copolymer positively charged and modified by adding glutathione (GSH) on the outer surface, resulting in a synergistic delivery of L-DOPA curcumin that would be able to pass the blood–brain barrier. Methods: The NH₂–PEO–PCL NPs suspensions were prepared by using a nanoprecipitation and solvent displacement method and coated with GSH. NPs were submitted to characterization assays. In order to ensure the bioavailability, Vero and PC12 cells were treated with various concentrations of the loaded and unloaded NPs to observe cytotoxicity. Results: NPs have successfully loaded L-DOPA and curcumin and were stable after freeze-drying, indicating advancing into in vitro toxicity testing. Vero and PC12 cells that were treated up to 72 h with various concentrations of L-DOPA and curcumin-loaded NP maintained high viability percentage, indicating that the NPs are biocompatible. Conclusions: NPs consisting of NH₂–PEO–PCL were characterized as potential formulations for brain delivery of L-DOPA and curcumin. The results also indicate that the developed biodegradable nanomicelles that were blood compatible presented low cytotoxicity.     

Efficient Synthesis of 2-Aminopyridine Derivatives: Antibacterial Activity Assessment and Molecular Docking Studies

A new and suitable multicomponent one-pot reaction was developed for the synthesis of 2-amino-3-cyanopyridine derivatives. Background: This synthesis was demonstrated by the efficient and easy access to a variety of substituted 2-aminopyridines using enaminones as key precursors under solvent-free conditions. Methods: A range of spectroscopic techniques was used to determine and confirm the chemical structures (FTIR, ¹H NMR, ¹³C NMR). The antimicrobial potency of synthesized compounds (2a–d) was tested using disk diffusion assays, and the Minimum Inhibitory Concentration (MIC) for the active compounds was determined against a panel of microorganisms, including Gram-positive and Gram-negative bacteria and yeasts. Moreover, a docking analysis was conducted by Molecular Operating Environment (MOE) software to provide supplementary information about the potential, as well as an ADME-T prediction to describe the pharmacokinetic properties of the best compound and its toxicity. Results: The results of the antimicrobial activity indicated that compound 2c showed the highest activity against Gram-positive bacteria, particularly S. aureus and B. subtilis whose MIC values were 0.039 ± 0.000 µg·mL⁻¹. The results of the theoretical study of compound 2c were in line with the experimental data and exhibited excellent antibacterial potential. Conclusions: On the basis of the obtained results, compound 2c can be used as an antibacterial agent model with high antibacterial potency.     

Double Hook Perylene Diimide as a New Receptor for PAHs: An Experimental and Theoretical Study

In a one-step reaction, we prepared a dibenzylamine perylene diimide derivative (PDI). Its double hook structure allows for self-association with a constant of K_d ∼10⁸ M⁻¹ determined by fluorescence. We confirmed its ability to bind PAHs using UV/Vis, fluorescence, and ¹H NMR titrations in CHCl₃. The complex formation signature in UV/vis is a new band at 567 nm. The calculated binding constants (K_a∼10⁴ M⁻¹) follow the trend pyrene>perylene>phenanthrene>naphthalene>anthracene. Theoretical modeling of these systems using DFT ωB97X-D/6-311G(d,p) proved helpful in rationalizing the complex formation and the observed association trend. The distinctive signal in UV/vis is due to a charge transfer in the complex from orbitals in the guest to the host. SAPT(DFT) confirmed that the driving forces in the complex formation are exchange and dispersion (π–π interactions). Still, the recognition ability depends on the electrostatic component of the interaction, a minor fraction.     

Evidence of polyphenols nitrosation by computer aided ESR spectroscopy

Polyphenols play an important role as model systems in transition metal derivatives for the preparation of macromolecular systems. Among the metal ions ironnitrosyl coordination chemistry has received much attention in the past because of its important role in inorganic and biological processes. In the case of Fe(I)(NO)₂ complexes with polyphenols ligands in solution, difficulties in the interpretation of the ESR spectra arise from complicated patterns due to simultaneous presence of different nitrogen nuclei directly bound to the metal ion or due to the presence of equilibria between species under slow exchange conditions. In order to overcome these difficulties the investigations reported here were carried out using computer simulation of ESR spectra combined with selective isotopic substitution of ¹⁴NO with ¹⁵NO. Resorcinol displays an unexpected nine lines ESR pattern at g=2.018 which can be explained only by considering more than two nitrogen atoms interacting with the unpaired electron delocalized over the metal complex.