Monoolein cubic phases containing hydrogen peroxide

Monoolein (MO) cubic phases were prepared by hydrating MO using distilled water or 12 wt.% H₂O₂ solution so that the content of aqueous phase in the cubic phase is 30 wt.%. The thermal transition of the isotropic cubic phase to reversed hexagonal phase was observed on a polarizing photomicroscope and the transition temperature was found to be around 65 °C on a differential scanning calorimeter (DSC). Small-angle X-ray scattering (SAXS) patterns indicated the cubic phases had diamond surfaces. The cubic phase released H₂O₂ into an aqueous phase in a saturation manner so that approx. 50% of total loaded H₂O₂ release in the first 10 h and thereafter relatively slow was observed over 40 h. The cubic phase was stable at 45 °C for 56 days before it broke down into an oily phase and an aqueous phase in 70 days. According to ¹H NMR spectrum, glycerol moiety and ---CH₂=CH₂--- of the oily phase were detected less in number than those of intact MO. Therefore, the hydrolysis and the oxidation of MO would be responsible for the breakdown of the cubic phase. The tensile adhesive forces of the cubic phases were higher than a skin-adhesive patch prepared using polyacrylate. The cubic phase containing H₂O₂ could be used as a topical disinfected gel for a wounded skin.     

Removal of copper from aqueous solution by aminated and protonated mesoporous aluminas: kinetics and equilibrium

A novel adsorbent, aminated and protonated mesoporous alumina, was prepared and employed for the removal of copper from aqueous solution at concentrations between 5 and 30 mg/l, in batch equilibrium experiments, in order to determine its adsorption properties. The removal of copper by the adsorbents increases with increasing adsorbent dosages. The adsorption mechanism is assumed to be an ion exchange between copper and the hydrogen ions present on the surface of the mesoporous alumina. The adsorbent was characterized by XRD, TEM, SEM, and BET methods. The sorption data have been analyzed and fitted to linearized adsorption isotherm of the Freundlich, Langmuir, and Redlich-Peterson models. The batch sorption kinetics have been tested for first-order, pseudo-first-order, and pseudo-second-order kinetic reaction models. The rate constants of adsorption for all these kinetic models have been calculated. Results also showed that the intraparticle diffusion of Cu(II) on the mesoporous catalyst was the main rate-limiting step.     

Effect of polycarbonate structure and reduction time on graphene oxide dispersion

Polycarbonate (PC)/graphene oxide (GO) composites with different GO reduction time and PC types were prepared by using a twin screw extruder at 260 °C after solution mixing with chloroform. The chemical reaction degree of PC/GO composites with GO reduction time was confirmed by C–H stretching peak at 3000 cm ^?1, and the chemical reaction degree decreased with GO reduction time. The slope for storage (G′) versus loss (G″) modulus plot decreases with an increase in heterogeneous property of the polymer melts. So we can check the GO dispersion of the PC/GO composites using by the slop for G′–G″ plot. According to the G′–G″ slopes for PC/GO composite with GO reduction time, GO was well dispersed within PC matrix when the reduction time decreased. It was re‐confirmed by atomic force microscope (AFM) results. Based on the degradation temperature by Thermogravimetric analysis, G′–G″ slopes, and surface roughness by AFM, the branched PC was better than linear PC for the GO dispersion within PC matrix. The fact was also confirmed by tensile test results that the Young's modulus increased with the improvement of GO dispersion. Copyright © 2015 John Wiley & Sons, Ltd.     

Flavonoid glycosides from Chromolaena odorata leaves and their in vitro cytotoxic activity

Two new flavonoid glycosides, (1, 2), and eleven known compounds, (3-13), were isolated from from a 70% EtOH extract of the leaves of Chromolaena odorata (Asteraceae). Their structures were elucidated by 1D and 2D NMR spectroscopic interpretation as well as by chemical studies. The newly isolated compounds were tested in vitro for their cytotoxic activities against the LLC and HL-60 cancer cell lines. Compound 1 showed cytotoxicity against LLC and HL-60 cancer cell lines with IC(50) values of 28.2 and 11.6 μM, respectively. Compound 2 exhibited significant cytotoxic activity in the inhibition of HL-60 cancer cell lines with IC(50) value of 10.8 μM.     

Kinetically blocked stable heptazethrene and octazethrene: closed-shell or open-shell in the ground state?

Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ((2))) were determined for HZ-TIPS (σ((2))(max) = 920 GM at 1250 nm) and OZ-TIPS (σ((2))(max) = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.     

Single bubble growth in saturated pool boiling on a constant wall temperature surface

Nucleate pool boiling experiments with constant wall temperatures were performed using R11 and R113 for saturated pool boiling conditions. A microscale heater array and Wheatstone bridge circuits were used to maintain a constant wall temperature condition and to obtain measurements with high temporal and spatial resolution. Accurate heat flow rate data were obtained from microscale heater array by controlling the surface conditions at a high temporal resolution. Images of the bubble growth were captured using a high-speed CCD camera synchronized with the heat flow rate measurements. The geometry of the bubble was obtained from the images. In the asymptotic growth region, the bubble showed a growth rate that was proportional to t^1/5, which was slower than the growth rate proposed in previous analytical analyses. The bubble growth behavior was analyzed using a new dimensionless parameter to permit comparisons with previous results at the same scale. The comparisons showed good agreement in the asymptotic growth region. A non-dimensional correlation for the bubble radius that can predict the bubble growth and the heat flow rate simultaneously, was suggested. The required heat flow rate for the volume change of the observed bubble was estimated to be larger than the instantaneous heat flow rate measured from the wall. Heat, other than the instantaneous heat supplied from the wall, is estimated to be transferred through the interface between bubble and liquid, even with saturated pool conditions. This phenomenon under a saturated pool condition needs to be analyzed and the data from this study can supply the good experimental data with the precise boundary condition (constant wall temperature).     

Absorption of surface plasmons in a metal-cladding layer-air structure in the terahertz frequency range

The effect of a thin dielectric cladding layer of a metal on the absorption of surface plasmons (SPs) in the terahertz frequency range is studied experimentally and numerically. It is found that, as the radiation wavelength increases, the attenuation of SPs caused by the cladding layer can increase by a factor of ～10⁴ as compared to the absorption of SPs propagating along the unperturbed metal-air interface. Data obtained in experiments with germanium-cladded aluminum specimens using radiation from a terahertz free-electron laser (v = 90 cm^?1) confirm that application of a dielectric cladding on the metal surface causes the SP absorption to increase.     

Robust parameter design in resource-constrained environments: An investigation of trade-offs between costs and precision within variable processes

Engineers and scientists often identify robust parameter design as one of the most important process and quality improvement methods. Focused on statistical modeling and numerical optimization strategies, most researchers typically assume a process with reasonably small variability. Realistically, however, industrial processes often exhibit larger variability, particularly in mass production lines. In such cases, many of the modeling assumptions behind the robust parameter design models available in the literature do not hold. Accordingly, the results and recommendations provided to decision makers could generate suboptimal modifications to processes and products. As manufacturers seek improved methods for ensuring quality in resource-constrained environments, experimenters should examine trade-offs to achieve the levels of precision that best support their decision making. In contrast to previous research, this paper proposes a trade-off analysis between the cost of replication and the desired precision of generated solutions. We consider several techniques in the early stages of experimental design, using Monte Carlo simulation as a tool, for revealing potential options to the decision maker. This is perhaps the first study to show the avenue which may lead to more effective robust parameter design models with the optimal combination of cost constraints and desired precision of solutions.     

Reduction of charge trapping in HfO2 film on a Ge substrate by trimethylaluminum pretreatment

Trimethylaluminum pretreatment prior to HfO₂ deposition is introduced for native oxide reduction. It is identified that the trimethylaluminum pretreatment could effectively reduce native oxide, which is transformed to an aluminum oxide interfacial layer. Formation of the thin aluminum oxide layer suppresses Ge diffusion into HfO₂, reducing hysteresis in the ca‐ pacitance–voltage curve. Moreover, the device reliability of the trimethylaluminum pretreated sample is improved in a constant current stress test. This work indicates that trimethylaluminum pretreatment is an effective in‐situ method for the gate dielectric stack formation to reduce charge trapping in the HfO₂ film on a Ge substrate. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)