Low voltage and high transmittance transflective blue-phase liquid crystal display with opposite polar electrodes

A single-cell-gap transflective polymer-stabilised blue-phase liquid crystal display with opposite polar pixel electrodes on an etched substrate is proposed. In the proposed structure, the space between common electrodes is adopted as transmissive region, and the space above the common electrode is adopted as reflective region. By optimising the electrode parameters of the transmissive and reflective regions, well-matched voltage-dependent transmittance and reflectance curves can be obtained. In addition, the device has good performances of low operating voltage (~3.2 V), high optical efficiency and a wide viewing angle.     

Application of response surface methodology for optimization of the stability of asphaltene particles in crude oil by TiO2/SiO2 nanofluids under static and dynamic conditions

In this work, the onset of asphaltene flocculation for an Iranian crude oil by titration of samples with heptane in the presence and absence of the TiO₂/SiO₂ nanofluids was obtained by Near-IR spectroscopy. Nanoparticles and nanocomposites were characterized by BET, FESEM, EDX, XRD, and XRF analysis. Modeling and optimization of inhibition of asphaltene flocculation process by TiO₂/SiO₂ nanofluids were conducted by response surface methodology (RSM). Under optimum conditions (nanocomposite composition = 0.04 wt% (80%TiO₂:20%SiO₂), salinity = 4.01 wt%, and pH = 3.42), the onset point increased. For nanofluids stability analysis, the optimum nanofluid was compared with the two other nanofluids (SiO₂ and TiO₂) by visual observation method. The results indicated that high stability and surface area of the 80%TiO₂ nanocomposites increase asphaltene adsorption on the particles surface that subsequently increases the onset point. In addition, the optimum nanofluid performance on the carbonate rocks was evaluated by contact angle and core flooding experiments. The 80% TiO₂ nanofluid changed the wettability of carbonate rocks from strongly oil-wet to strongly water-wet condition and also decreased the residual oil saturation and enhanced the oil recovery with an increase in the recovery factor of about 15%.     

A Sterically Constrained Tricyclic PC3 Phosphine: Coordination Behavior and Insertion of Chalcogen Atoms into P−C Bonds

A tricyclic phosphine has been generated that has a rigid molecular backbone with the P atoms exclusively bound to C(sp²) atoms as well as a very large Tolman angle and buried volume. It is an interesting new ligand in coordination chemistry (Au, Pd complexes) and shows unusual insertion reactions into its endocyclic P?C bonds facilitated by its inherent molecular strain.     

Spectroscopic Characterization of a Lead–Lead Dioxide Automobile Battery

Here we combine small angle neutron scattering measurements (SANS) with X-ray diffraction analysis (XRD) and infrared spectroscopy (IR) measurements to obtain information about nanoparticles formed in a series of lead-lead dioxide samples mixed with various CuO concentrations. New vitreous systems with the xCuO???(100?x)[4PbO₂???Pb] composition where x?=?0, 30, and 70?mol% CuO were prepared by the melt-quenching method using CuO mixed in suitable proportion with the active electrodes of a disassembled car battery as the starting materials. The X-ray diffraction patterns permit the identification of the metallic Pb phase and the presence of oxidic nanoparticles of the lead and copper ions. By doping with higher CuO contents, the SANS curves have a concave shape indicating inhomogeneities and tendency of phase separation due to formation of nanoparticles of the lead and copper ions in recycled host matrix. The studied samples can be considered as polydispersed systems. The matrix is the solvent and the soluble phase is formed from the oxidic lead and/or copper particles with sizes smaller than 69?Å dispersed either inside the host matrix grains or between the host matrix grains. The formation of the nanoparticles in the host matrix and the knowledge of the type of nanoparticles have a decisive role in applications for the construction of essential components of the automobile batteries.     

Subgroups of Classical Groups Generated by Transvections or Siegel Transvections I: Embedding in Linear Groups

We are concerned with finite-dimensional classical groups over arbitrary commutative fields. In an orthogonal group a Siegel transvection, that is, an element centralizing l for some totally singular 2-dimensional subspace l, plays the same role as a transvection in the linear, symplectic or unitary groups. The Main Theorem of this paper describes the possible embeddings of classical groups in classical groups such that (Siegel) transvections act as (Siegel) transvections.     

Polar and Hydrogen-Bonding Effects of Alcohols on the Emission Spectrum of Styrene–Triethylamine System

The emission spectra of styrene (ST)–triethylamine (TEA) systems were measured under steady-state illumination conditions in some tetrahydrofuran (THF)–protic solvent mixtures. The fluorescence spectrum of the ST–TEA system in THF consists of two bands (band A at 304 nm (fluorescence of ST) and band B at 460 nm (emission from an exciplex)). The intensity of band A increased and that of band B decreased with increasing amounts of protic solvents in THF–protic solvent mixtures. The increase in the intensity of band A was explained by the decrease in the concentration of free amine owing to the hydrogen-bonding interaction (or protonation) between TEA and protic solvents. The decrease in the intensity of band B was considered to be caused by the decrease in the concentration of free amine upon the addition of protic solvents and the enhanced conversion of the exciplex to an ion pair with increasing solvent polarity. The polar effect was expressed as a function of the relative permittivity of the solution.     

TLC Determination of Aliphatic Polyamines on Calcium Sulfate Layers

Biogenic polyamines are sensitive markers for various diseases including cancer. Polyamines are difficult to analyze by chromatography due to their high polarity and water-solubility so that derivatization is an essential step for their chromatographic analysis. Earlier studies have shown the efficacy of calcium sulfate (CaSO₄) as a TLC coating material for the separation of polar compounds. The aim of this study was to explore the potential of CaSO₄ for the analysis of aliphatic polyamines without derivatization. The TLC of six polyamines (ornithine, citrulline, putrescine, cadaverine, spermidine and spermine) was carried out on CaSO₄ and silica gel plates using 11 different mobile phases. The results showed that CaSO₄ is superior to silica for the separation of underivatized polyamines. The development time of the CaSO₄ plates was also about one-third shorter as compared to silica. Methanol was the only solvent to produce differential R _F values for the polyamines studied. Ornithine (R _F , 0–2) and citrulline (R _F , 1–3) were separated from cadaverine (R _F , 0.93), spermine (R _F , 0.85) and spermidine (R _F , 0.85). For quantitative analysis, the polyamines were eluted from the coating material scratched from the plate and the absorbance of the supernatant was measured at 550 nm. The limits of detection (LOD) and quantification (LOQ) were found to be 0.75 and 1.88 μg, respectively. The procedure was applied to the quantitative separation of polyamines in spiked human urine samples (12.5–50 μg). This is probably the first study reporting a TLC method for the separation of underivatized polyamines.     

A novel method to introduce durable hydrophilicity onto hydrophobic polymer surface by plasma treatment

We have examined a novel method to fabricate a durable hydrophilic surface of hydrophobic polymeric materials modified by plasma treatment. The method involves a trapping of maleic anhydride-containing polymer onto poly(ethylene naphthalate) (PEN) by a plasma-induced crosslinking reaction of PEN followed by hydrolysis of maleic anhydride moiety to generate hydrophilic carboxyl groups on the PEN surface. In fact, the PEN film surface thus treated has shown an effective stability of wettability based on the water contact angle measurement.     

A ToF‐SIMS investigation of a buried polymer/polymer interface exposed by ultra‐low‐angle microtomy

The interfacial region of a model multilayer coating system on an aluminium substrate has been investigated by high‐resolution time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Employing ultra‐low‐angle microtomy (ULAM), the interface between a poly(vinylidene difluoride) (PVdF)‐based topcoat and a poly(urethane) (PU)‐based primer ‘buried’ >20 µm below the PVdF topcoat's air/coating surface was exposed. Imaging ToF‐SIMS and subsequent post‐processing extraction of mass spectra of the ULAM‐exposed interface region and of the PVdF topcoat and PU primer bulks indicates that the material composition of the polymer/polymer interface region is substantially different to that of the bulk PVdF and PU coatings. Analysis of the negative ion mass spectra obtained from the PVdF/PU interface reveals the presence of a methacrylate‐based component or additive at the interface region. Reviewing the topcoat and primer coating formulations reveals that the PVdF topcoat formulation contains methyl methacrylate (MMA)–ethyl acrylate (EA) acrylic co‐polymer components. Negative ion ToF‐SIMS analysis of an acrylic co‐polymer confirms that it is these components that are observed at the PVdF/PU interface. Post‐processing extraction of ToF‐SIMS images based on the major ions of the MMA–EA co‐polymers reveals that these components are observed in high concentration at the extremities of the PVdF coating, i.e. at the polymer/polymer interface, but are also observed to be distributed evenly throughout the bulk of the PVdF topcoat. These findings confirm that a fraction of the MMA–EA acrylic co‐polymers in the formulation segregate to the topcoat/primer interface where they enhance the adhesive properties exhibited by the PVdF topcoat towards the underlying PU primer substrate. Copyright © 2004 John Wiley & Sons, Ltd.     

Liquid chromatography-mass spectrometry and strategies for trace-level analysis of polar organic pollutants

Liquid chromatography–mass spectrometry using atmospheric pressure ionization (LC–API-MS) has drastically changed the analytical methods used to detect polar pollutants in water. The present status of application of this technique to organic water constituents is reviewed. The selection of the appropriate LC conditions, whether reversed-phase liquid chromatography, ion-pair chromatography, capillary electrophoresis or ion chromatography, and of the most sensitive ionization mode, electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), depends upon the polarity and acidity of the analytes. Strongly acidic compounds such as aromatic sulfonates, sulfonated dyes, haloacetic acids, linear alkylbenzene sulfonates, aliphatic sulfonates and sulfates and complexing agents, weakly acidic compounds such as carboxylates and phenols, neutral compound classes, namely alkylphenol ethoxylates, alcohol ethoxylates and polycyclic aromatic hydrocarbons and the basic toxins, quaternary ammonium compounds and organometallic compounds are considered. The selection of the mass spectrometer depends upon the analytical task: triple-quadrupole mass spectrometers are highly suited for sensitive quantitation and for qualitative analyses, ion traps are especially suited for structure elucidation, whereas time-of-flight mass spectrometers and quadrupole time-of-flight mass spectrometers with their higher mass resolution are ideal for the determination of molecular formulas of unknown compounds and for screening purposes. While large steps have already been made, future efforts with respect to water analysis may be directed at fine-tuning the methodical arsenal for increased sensitivity and selectivity and to extend LC–MS application to transformation products.