A New Mussel‐Inspired Polydopamine Sensitizer for Dye‐Sensitized Solar Cells: Controlled Synthesis and Charge Transfer

The efficient electron injection by direct dye‐to‐TiO₂ charge transfer and strong adhesion of mussel‐inspired synthetic polydopamine (PDA) dyes with TiO₂ electrode is demonstrated. Spontaneous self‐polymerization of dopamine using dip‐coating (DC) and cyclic voltammetry (CV) in basic buffer solution were applied to TiO₂ layers under a nitrogen atmosphere, which offers a facile and reliable synthetic pathway to make the PDA dyes, PDA‐DC and PDA‐CV, with conformal surface and perform an efficient dye‐to‐TiO₂ charge transfer. Both synthetic methods led to excellent photovoltaic results and the PDA‐DC dye exhibited larger current density and efficiency values than those in the PDA‐CV dye. Under simulated AM 1.5 G solar light (100 mW cm^?2), a PDA‐DC dye exhibited a short circuit current density of 5.50 mW cm^?2, corresponding to an overall power conversion efficiency of 1.2 %, which is almost 10 times that of the dopamine dye‐sensitized solar cell. The PDA dyes showed strong adhesion with the nanocrystalline TiO₂ electrodes and the interface engineering of a dye‐adsorbed TiO₂ surface through the control of the coating methods, reaction times and solution concentration maximized the overall conversion efficiency, resulting in a remarkably high efficiency.     

Self-assembled, pH-sensitive retinoate nanostructures ionically complexed with PEG-grafted cationic polyelectrolytes

All-trans-retinoic acids (ATRA) are ionically complexed with cationic polyelectrolytes containing tertiary amines and self-assembled into nanoscale colloidal structures. Poly(2-(dimethylamino)ethyl methacrylate) grafted with polyethylene glycol, poly(DMAEMA-g-PEG), is used as a double hydrophilic, cationic polyelectrolyte. The polyion/ATRA complexes are formed by adding ATRA in dimethyl sulfoxide into aqueous solution of poly(DMAEMA-g-PEG). This complexation effectively suppresses the formation of undesirable drug crystallites and produces stable colloidal nanostructures having a hydrodynamic diameter of about 15?nm at a neutral pH. However, as the pH decreases below about 6, they undergo dramatic structural change into large aggregates of about 250?nm in diameter presumably due to the dissociation of ATRA from the polyelectrolyte. We expect that this pH-sensitive response of the polyion/ATRA complexes is useful for intracellular translocation at a neutral pH followed by the endosomal escape of ATRA in an acidic condition.     

Digital selective growth of ZnO nanowire arrays from inkjet-printed nanoparticle seeds on a flexible substrate

In this article, we introduce fully digital selective ZnO nanowire array growth on inkjet-printed seed patterning. Through proper natural convection suppression during hydrothermal growth, successful ZnO nanowire local growth can be achieved. Without any need for photolithographic processing or stamp preparation, the nanowire growth location can be easily modified when the inkjet printing process is integrated with a CAD (computer-aided design) system to allow a high degree of freedom when the design needs to be changed. The current proposed process is very fast, low-cost, environmentally benign, and low-temperature. Therefore, it can be applied to a flexible plastic substrate and scaled up for larger substrates for mass production or roll-to-roll processing.     

Supercapacitive properties of electrodeposited RuO2 electrode in acrylic gel polymer electrolytes

Hydrous ruthenium oxide (RuO₂) is prepared by electrodeposition on a platinum substrate and its supercapacitive properties are characterized adopting acrylic gel polymer electrolytes, such as poly(acrylic acid) (PAA), potassium polyacrylate (PAAK), and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The electrodeposited hydrous RuO₂ exhibits an amorphous compact stratified morphology with a higher loading (0.15 mg cm^?2) than that of a previous report, and shows broad redox peaks on both cathodic and anodic scans in the cyclic voltammetry. In particular, the RuO₂ electrode for supercapacitor adopting the PAMPS electrolyte shows the highest specific capacitance of 642 F g^?1 at 20 mV s^?1. This is due to the efficient utilization of active RuO₂ species and greater proton accommodation toward the negative oxygen sites of PAMPS's side chain. In addition, it is possible to improve sustainability against high-rate current with the RuO₂ electrode with the PAMPS electrolyte, due to the crosslinks of the gel electrolyte, which support the mechanical strength.     

An Ascending Chain Condition on Wedderburn Radicals

In this note we study the properties of Amitsur's example for Wedderburn radicals, introducing the concept of W _n -reduced rings. The theories of commutative ring and reduced ring are generalized to W _n -reduced rings. We characterize the W _n -reduced property and study properties of W _n -reduced rings. It is shown that the classes of semi-commutative rings, W _n -reduced rings, and 2-primal rings are in a strictly increasing order. We extend the class of W _n -reduced rings, observing various kinds of extensions containing classical quotient rings, polynomial rings, and power series rings.

Communicated by M. Ferrero.     

QCD Chiral Restoration at Finite T Under the Magnetic Field

We investigate the chiral restoration at finite temperature (T) under the strong external magnetic field ${{\bf B}=B_{0}\hat{z}}$ of the SU(2) light-flavor QCD matter. We employ the instanton-liquid QCD vacuum configuration accompanied with the linear Schwinger method for inducing the magnetic field. The Harrington–Shepard caloron solution is used to modify the instanton parameters, i.e. the average instanton size ${(\bar{\rho})}$ and inter-instanton distance ${(\bar{R})}$ , as functions of T. In addition, we include the meson-loop corrections as the large-N _c corrections because they are critical for reproducing the universal chiral restoration pattern. We present the numerical results for the constituent-quark mass as well as chiral condensate which signal the spontaneous breakdown of chiral-symmetry (SBχS), as functions of T and B. Besides we find that the changes for the F _π and m _π due to the magnetic field is relatively small, in comparison to those caused by the finite T effect.     

Analysis of a Discrete-Time Finite-Capacity Single-Server Queue with Markovian-Arrival Process and Random-Bulk-Service: D-MAP/G Y /1/M

In this article, we consider a single-server, finite-capacity queue with random bulk service rule where customers arrive according to a discrete-time Markovian arrival process (D-MAP). The model is denoted by D-MAP/G ^Y /1/M where server capacity (bulk size for service) is determined by a random variable Y at the starting point of services. A simple analysis of this model is given using the embedded Markov chain technique and the concept of the mean sojourn time of the phase of underlying Markov chain of D-MAP. A complete solution to the distribution of the number of customers in the D-MAP/G ^Y /1/M queue, some computational results, and performance measures such as the average number of customers in the queue and the loss probability are presented.     

Outer semicontinuity of subdifferential and normal cone mappings

In finite dimensions, the outer semicontinuity of a set-valued mapping is equivalent to the closedness of its graph. In this article, we study the outer semicontinuity of set-valued mappings in connection with their convexifications and linearizations in finite and infinite dimensions. The results are specified to the case where the mappings involved are given by subdifferentials of extended real-valued functions or normal cones to sets. Our developments are important for applications to second-order calculus in variational analysis in which the outer semicontinuity plays a crucial role.