Dielectric Spectroscopy Analysis of Liquid Crystals Recovered from End-of-Life Liquid Crystal Displays

In the present work, the dielectric properties of recycled liquid crystals (LCs) (non-purified, purified, and doped with diamond nanoparticles at 0.05, 0.1, and 0.2 wt%) were investigated. The studied LC mixtures were obtained from industrial recycling of end-of-life LC displays presenting mainly nematic phases. Dielectric measurements were carried out at room temperature on a frequency range from 0.1 to 10⁶ Hz using an impedance analyzer. The amplitude of the oscillating voltage was fixed at 1 V using cells with homogeneous and homeotropic alignments. Results show that the dielectric anisotropy of all purified samples presents positive values and decreases after the addition of diamond nanoparticles to the LC mixtures. DC conductivity values were obtained by applying the universal law of dielectric response proposed by Jonscher. In addition, conductivity of the doped LC mixtures is lower than that of the undoped and non-purified LC.     

Effect of the Ethanol/BTC Ratio on the Methane Uptake of Mechanochemically Synthesized MOF-199

We report on a detailed textural analysis of mechanochemically synthesized MOF-199 including N₂ adsorption-desorption and CO₂ adsorption isotherms data at 77 K and 273 K (up to atmospheric pressure), respectively, and CH₄ adsorption data at 298 K (up to 35 bar). We used the isotherm adsorption data to determine the micropore volume of the MOF-199 structures, to establish their methane uptake capacity and to understand how these properties depended on the Ethanol/BTC ratio used during the synthesis. The maximum methane uptake capacity for our specimens was recorded at 130 v/v at 35 bars. These results open an avenue for a better understanding of alternative manufacturing processes of MOF structures for gas storage applications.     

Incorporation of β-Alanine in Cu(II) ATCUN Peptide Complexes Increases ROS Levels,DNA Cleavage and Antiproliferative Activity**

Redox-active Cu(II) complexes are able to form reactive oxygen species (ROS) in the presence of oxygen and reducing agents. Recently, Faller et al. reported that ROS generation by Cu(II) ATCUN complexes is not as high as assumed for decades. High complex stability results in silencing of the Cu(II)/Cu(I) redox cycle and therefore leads to low ROS generation. In this work, we demonstrate that an exchange of the α-amino acid Gly with the β-amino acid β-Ala at position 2 (Gly2→β-Ala2) of the ATCUN motif reinstates ROS production (^•OH and H₂O₂). Potentiometry, cyclic voltammetry, EPR spectroscopy and DFT simulations were utilized to explain the increased ROS generation of these β-Ala2-containing ATCUN complexes. We also observed enhanced oxidative cleavage activity towards plasmid DNA for β-Ala2 compared to the Gly2 complexes. Modifications with positively charged Lys residues increased the DNA affinity through electrostatic interactions as determined by UV/VIS, fluorescence, and CD spectroscopy, and consequently led to a further increase in nuclease activity. A similar trend was observed regarding the cytotoxic activity of the complexes against several human cancer cell lines where β-Ala2 peptide complexes had lower IC₅₀ values compared to Gly2. The higher cytotoxicity could be attributed to an increased cellular uptake as determined by ICP-MS measurements.     

Desorption/ionization efficiencies of triacylglycerols and phospholipids via EASI‐MS

Knowledge of the major effects governing desorption/ionization efficiency is required for the development and application of ambient mass spectrometry. Although all triacylglycerols (TAG) have the same favorable protonation and cationization sites, their desorption/ionization efficiencies can vary dramatically during easy ambient sonic‐spray ionization because of structural differences in the carbon chain. To quantify this somewhat surprising and drastic effect, we have performed a systematic investigation of desorption/ionization efficiencies as a function of unsaturation and length for TAG as well as for diacylglycerols, monoacylglycerols and several phospholipids (PL). Affinities for Na⁺ as a function of unsaturation level have also been assayed via comprehensive metadynamics calculations to understand the influence of this phenomenon on the ionization efficiency. The results suggest that dipole–dipole interactions within a carbon chain tuned by unsaturation sites govern ionization efficiency of TAG and PL. Copyright © 2014 John Wiley & Sons, Ltd.     

Abrupt Convergence and Escape Behavior for Birth and Death Chains

We link two phenomena concerning the asymptotical behavior of stochastic processes: (i) abrupt convergence or cut-off phenomenon, and (ii) the escape behavior usually associated to exit from metastability. The former is characterized by convergence at asymptotically deterministic times, while the convergence times for the latter are exponentially distributed. We compare and study both phenomena for discrete-time birth-and-death chains on ℤ with drift towards zero. In particular, this includes energy-driven evolutions with energy functions in the form of a single well. Under suitable drift hypotheses, we show that there is both an abrupt convergence towards zero and escape behavior in the other direction. Furthermore, as the evolutions are reversible, the law of the final escape trajectory coincides with the time reverse of the law of cut-off paths. Thus, for evolutions defined by one-dimensional energy wells with sufficiently steep walls, cut-off and escape behavior are related by time inversion.     

Halometallates of 1-methyl-4,4-dimercapto-piperidinium. Evidence of strong hydrogen bonds with participating thiol groups

Chlorometallates of transition and B subgroup elements are readily prepared and precipitated by reaction of the corresponding metallic salts with 1-methyl-4,4-dimercaptopiperidinium chloride. These chlorometallates investigated were [ZnCl₄]^2?, [CdCl₃]^?, [CoCl₄]^2?, [CuCl₅]^3? and [FeCl₄]^2?. Strong SH … Cl interactions, but not NH … Cl, have been evidenced by IR spectroscopy in the zinc, cadmium and cobalt complexes. The SH and NH absorptions are observed at ? 2480 cm^?1 and 3060 cm^?1, respectively. Partial deuteration of the [ZnCl₄]^2? complex with d₁-methanol, shifted these IR signals to 1800 and 2260 cm^?1, clearly evidencing a X-hydrogen type of bond. The SH … Cl interaction is smaller in the [FeCl₄]^2? complex, and practically nonexistent in the [CuCl₅^3? complex.     

Effectiveness of Photodynamic Therapy in Elimination of HPV‐16 and HPV‐18 Associated with CIN I in Mexican Women

This study aimed to determine the effectiveness of photodynamic therapy (PDT), using δ‐aminolevulinic acid (5‐ALA), in the elimination of premalignant cervical lesions in Mexican patients with human papillomavirus (HPV) infection and/or cervical intraepithelial neoplasia (CIN). Thirty women diagnosed with CIN I and/or positive for HPV participated in the study. Topical 6% 5‐ALA in gel form was applied to the uterine cervix; after 4 h, the lesion area was irradiated with a light dose of 200 J cm^?2 at 635 nm. This procedure was performed three times at 48‐h intervals. Clinical follow‐up was performed at 3, 6, and 12 months after the initial PDT administration, by colposcopy, cervical cytology, histopathological analysis, polymerase chain reaction, and hybrid capture. Of HPV‐infected patients without evidence of CIN I, 80% cleared the infection, while HPV associated with CIN I was eliminated in 83% of patients (P < 0.05). At 12 months, CIN I had regressed in 57% of patients, although this response was not statistically significant. PDT using 6% 5‐ALA is concluded to be effective in eliminating HPV infection associated or not with CIN I.     

Experimental opto-digital synthesis of encrypted sub-samples of an image to improve its decoded quality

We develop an experimental protocol to visualize decrypted images that otherwise would have been barely recognizable, while keeping the standard security levels. This image deterioration is partly due to the natural speckle noise as well as the practical limitations arising from the optical elements composing the setup. This protocol is based on an optical image synthesis with digital holography using enlarged sub-samples of an entire image together with a multiplexing technique. We implement the process using a Mach-Zehnder interferometer with a joint transform correlator encrypting architecture. As a result, we get smaller speckle patterns on the final assembled image and a spatial frequency enhancement with respect to the decoded image obtained with the conventional procedures.     

Kinetics of the plasmon optical response of Au nanoparticles/TiO<Subscript>2</Subscript> catalyst under O<Subscript>2</Subscript> and H<Subscript>2</Subscript> followed by differential diffuse reflectance spectroscopy

The changes in the optical properties of Au/TiO₂ powder catalyst, prepared by the deposition-precipitation method, are measured in the visible range by use of a home-made diffuse differential reflectance spectrometer, when the ambient atmosphere is switched between H₂ and O₂. Two main features are observed: (i) a short wavelength one, located between 400 and 600 nm, is shown to be related to the modifications of the plasmon resonance of the 3-dimensional metallic gold particles with mean size around 4 nm, induced by the exposure to oxygen or by its removal; (ii) a second feature, observed at long wavelengths between 600 and 1100 nm, is extremely sensitive to the exposure to oxygen. This optical feature could be due to the presence in the catalyst, either of Au⁰ clusters of several tens atoms, which are expected to display molecular-like transitions in this optical range, or to specific sites of the Au particles (edge atoms or peripheral atoms at the interface with the TiO₂ support), which could be highly reactive to oxygen.     

Vibrational energies and thermal expansion of layered compounds: MgCl2

Full dynamic free energy minimisation is used to study the stability of different polymorphs of MgCl₂, with a new set of interionic potentials derived from ab initio calculations using density functional theory. The calculated difference in free energies between the - and β-phases is extremely small: the vibrational contribution reverses the relative ordering of these two structures obtained in the static limit. We predict the thermal expansion of both forms is highly anisotropic and that, unusually, above ≈60 K the expansion is larger parallel than perpendicular to the layers.