Role of interfacial interactions on the anomalous swelling of polymer thin films in supercritical carbon dioxide

It has recently been shown that thin polymer films in the nanometer thickness range exhibit anomalous swelling maxima in supercritical CO₂ (Sc‐Co₂) in the vicinity of the critical point of CO₂. The adsorption isotherm of CO₂ on carbon black, silica surfaces, porous zeolites, and other surfaces, is known to exhibit anomalous maxima under similar CO₂ conditions. It is believed that because CO₂ possesses a low cohesive energy density, there would be an excess amount of CO₂ at the surfaces of these materials and hence the CO₂/polymer interface. This might cause excess CO₂ in the polymer films near the free surface, and hence the swelling anomaly. In addition, an excess of CO₂ would reside at the polymer/substrate and polymer/CO₂ interfaces for entropic reasons. These interfacial effects, as have been suggested, should account for an overall excess of CO₂ in a thin polymer film compared to the bulk, and would be responsible for the anomalous swelling. In this study, we use in situ spectroscopic ellipsometry to investigate the role of interfaces on the anomalous swelling of polymer thin films of varying initial thicknesses, h₀, exposed to Sc‐CO₂. We examined three homopolymers, poly(1,1′‐dihydroperflurooctyl methacrylate) (PFOMA), polystyrene (PS), poly(ethylene oxide) (PEO), that exhibit very different interactions with Sc‐CO₂, and the diblock copolymer of PS‐b‐PFOMA. We show that the anomalous swelling cannot be solely explained by the excess adsorption of CO₂ at interfaces. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1313–1324, 2007     

Implementation of an 8ch GbE Multiplexing Transponder

We report the implementation of a transponder to transmit eight channels of a Gigabit Ethernet signal transparently in an Optical Transport Network(OTN). This transponder is based on framing technologies for Ethernet over SDH over OTN. This framing structure offers an attractive option for carrying data traffic over the OTN.     

Inclusion and argument properties for certain subclasses of meromorphic functions associated with a family of multiplier transformations

Making use of a multiplier transformation, which is defined here by means of the Hadamard product (or convolution), the authors introduce some new subclasses of meromorphic functions and investigate their inclusion relationships and argument properties. Some integral-preserving properties in a given sector are also considered.     

Measurement of Reactive Hydroxyl Radical Species Inside the Biosolutions During Non-thermal Atmospheric Pressure Plasma Jet Bombardment onto the Solution

Non-thermal atmospheric pressure plasma jet could generate various kinds of radicals on biosolution surfaces as well as inside the biosolutions. The electron temperature and ion density for this non-thermal plasma jet have been measured to be about 0.8~1.0 eV and 1 × 10¹³ cm^?3 in this experiment, respectively, by atmospheric pressure collisional radiative model and ion collector current. In this context, the hydroxyl OH radical density inside the biosolutions has been also investigated experimentally by ultraviolet absorption spectroscopy when the Ar non-thermal plasma jet has been bombarded onto them. It is found that the emission and absorption profiles for the other reactive oxygen species such as NO (226 nm) and O₂*^? (245 nm) are shown to be very small inside the biosolution in comparison with those for the OH radical species. It is found that the densities of OH radical species inside the biosolutions are higher than those on the surface in this experiment. The densities of the OH radical species inside the deionized water, Dulbecco’s modified eagle medium, and phosphate buffered saline are measured to be about 2.1 × 10¹⁶, 1.1 × 10¹⁶, and 1.0 × 10¹⁶ cm^?3, respectively, at 2 mm downstream from the surface under optimized Ar gas flow of 200 sccm. It is also found that the critical hydroxyl OH radical density for the lung cancer H460 cells to experience an apoptosis is observed to be around 0.3 × 10¹⁶ cm^?3 under 1 min plasma exposure in this experiment.     

An X‐ray absorption spectroscopic study of carbon monoxide‐adsorbed Cu surface

Adsorption/interaction of Carbon monoxide (CO) on a catalytic surface is the key step in electrochemical conversion of CO2 for environmental consideration. Copper (Cu) is known to be the most efficient catalyst for this purpose. Thus, this paper investigates effects of CO adsorption on the electronic/atomic state of polycrystalline Cu surface by using x‐ray absorption spectroscopy (XAS). X‐ray absorption near‐edge structure (XANES) tells that the Cu K‐edge shift +0.2 eV on adsorbing CO. Extended x‐ray absorption fine structure (EXAFS) analysis informs that CO adsorption disturbs Cu surface, i.e. increase of Cu‐Cu bonding distance and decrease of the coordination number of the first nearest neighbor. Both the results of XANES and EXAFS imply decrease of d‐electron density of Cu on the adsorption. Demonstrated is that XAS is very useful in studying the surface phenomena of a catalyst but requires further efforts. Copyright © 2014 John Wiley & Sons, Ltd.     

Mpp7 controls regioselective Knoevenagel condensation during the biosynthesis of Monascus azaphilone pigments

Targeted inactivation of the mpp7 gene in the Monascus azaphilone pigment (MAzP) biosynthetic gene cluster resulted in the accumulation of monasfluol A (7) and B (8), of which the latter was a novel compound, and the abolition of the main MAzPs. It is thus proposed that 7 and 8 are the products of non-enzymatic Knoevenagel condensation followed by a reduction and that Mpp7 assists in regioselective Knoevenagel aldol condensation during MAzP biosynthesis.     

Thieno[2,3-a]carbazole-based donor–π–acceptor organic dyes for efficient dye-sensitized solar cells

New donor–π–acceptor organic dyes K-1 and K-2 containing thieno[2,3-a]carbazole as an electron donor were designed and synthesized for dye-sensitized solar cells (DSCs). Photophysical and electrochemical properties of K-dyes were investigated. DSCs based on K-dyes showed a high conversion efficiency of 6.6–6.7% with a J_sc of 12.40–12.49 mA cm⁻² and a V_oc of 0.70–0.71 V. The molecular geometry calculation indicated that the existence of thienocarbazole donor in K-dyes enhanced the molecular planarity compared to the carbazole analogue dye MK-3. As a result, DSCs based on K-dyes showed high IPCEs, perhaps due to efficient intramolecular charge transfer and electron injection from excited dye to TiO₂ conduction band.     

Theoretical Study of Xanthenone and Phenothiazine Derivatives for Blue TADF Emitter

Two novel thermally activated delayed fluorescence (TADF) materials (PTZ-XTN and 2PTZ-XTN), with phenothiazine (PTZ) as an electron donor and xanthenone derivatives (XTN) as electron acceptors, were designed and theoretically investigated as blue OLED emitters. We used density functional theory (DFT) and time dependent DFT (TD-DFT) calculations to determine the electron distribution of HOMO and LUMO and the energy of the lowest singlet (S₁) and the lowest triplet (T₁) excited states. The large dihedral angle between the electron donor and the electron acceptor imparted a small spatial overlap between HOMO and LUMO in all the materials. This charge separation of the HOMO and LUMO leads to a small energy gap between the S₁ state and T₁ state, thereby leading to TADF emission. Among the materials studied, PTZ-XTN has the most suitable properties for a blue TADF OLED emitter, even though 2PTZ-XTN has the smallest energy gap between the S₁ and T₁ states.     

Microwave Enhanced Knoevenagel Condensation of Malonic Acid on Basic Alumina

Abstract: An improved Knoevenagel condensation of malonic acid and aldehydes can be achieved by microwave irradiation over alumina. A number of diacids were prepared in good yields in very short reaction times.