Aqua(nitrilo­triacetato)­(1,10‐phenanthroline)iron(III) monohydrate: a seven‐coordinate iron(III) complex

Reaction of 1,10‐phenanthroline (phen) with iron trichloride in the presence of sodium nitrilo­tri­acetate (NTA) resulted in the formation of red crystals of the title complex, [Fe(C₆H₆NO₆)(C₁₂H₈N₂)(H₂O)]·H₂O. The Fe atom has a distorted capped trigonal prismatic coordination comprised of one tetradentate NTA, one bidentate phen molecule and a water mol­ecule. Intermolecular O—H?O hydrogen bonds link the mol­ecules into infinite chains. The chains are crosslinked by hydrogen bonds involving the solvent water mol­ecule, leading to an infinite ladder packing mode.     

Numerical investigation of the effect of heat shield shape on the oxygen impurity distribution at the crystal–melt interface during the process of Czochralski silicon crystal growth

In this study, a numerical simulation is performed to investigate the effect of the shape of the heat shield on the oxygen concentration in the melt. The results show that the oxygen concentration in the melt can be significantly decreased by increasing the speed of the argon gas near the crucible wall. This can be achieved by enlarging the horizontal length of the heat shield. The oxygen concentration at the melt–crystal interface varies with the length of the crystal growth. In the initial stage, there is a significant decrease in the oxygen concentration as the growth length increases. There is also a significant reduction in the emission of oxygen from the crucible wall due to the lower melt depth and crucible temperature. The transportation of oxygen impurity towards the melt–crystal interface is suppressed by the vortex motion in the melt. When the crystal exceeds a certain length, the oxygen concentration in the melt–crystal interface starts to increase with increasing crystal length, due to the drop in vortex motion in the melt.     

CO oxidation of bare and TiO2-coated NiO-Ni(OH)2 nanoparticles

CO oxidation reactivity of bare and TiO₂-coated nanoparticles consisting of both NiO and Ni(OH)₂ surfaces was studied. For the deposition of TiO₂, atomic layer deposition was used, and formation of three-dimensional domains of TiO₂ on NiO-Ni(OH)₂ could be identified. Based on the data of X-ray Photoelectron Spectroscopy, we suggest that upon TiO₂ deposition only Ni(OH)₂ was remained on the surface, whereas NiO surface disappeared. Both CO adsorption and CO oxidation took place on NiO-Ni(OH)₂ surfaces under our experimental conditions. CO adsorption was almost completely suppressed after TiO₂ deposition, whereas CO oxidation activity was maintained to large extent. It is proposed that bare NiO cannot be active for CO oxidation, and can only uptake CO under our experimental condition, whereas hydroxylated surface of NiO can be active for CO oxidation.     

Adaptive cyclically dominating game on co-evolving networks: numerical and analytic results

A co-evolving and adaptive Rock (R)–Paper (P)–Scissors (S) game (ARPS) in which an agent uses one of three cyclically dominating strategies is proposed and studied numerically and analytically. An agent takes adaptive actions to achieve a neighborhood to his advantage by rewiring a dissatisfying link with a probability p or switching strategy with a probability 1 - p. Numerical results revealed two phases in the steady state. An active phase for p < p _c has one connected network of agents using different strategies who are continually interacting and taking adaptive actions. A frozen phase for p > p _c has three separate clusters of agents using only R, P, and S, respectively with terminated adaptive actions. A mean-field theory based on the link densities in co-evolving network is formulated and the trinomial closure scheme is applied to obtain analytical solutions. The analytic results agree with simulation results on ARPS well. In addition, the different probabilities of winning, losing, and drawing a game among the agents are identified as the origin of the small discrepancy between analytic and simulation results. As a result of the adaptive actions, agents of higher degrees are often those being taken advantage of. Agents with a smaller (larger) degree than the mean degree have a higher (smaller) probability of winning than losing. The results are informative for future attempts on formulating more accurate theories.     

Role of multivalent cations in the self-assembly of phospholipid-DNA complexes

In view of efficient and nontoxic delivery of genes to cells, complexes made of phospholipids (noncationic) and DNA are assembled through the mediation of multivalent cations. The association of lipids with DNA is explained through the charge reversal of lipid headgroups by specific adsorption of cations. The ion binding is quantified by the Gouy-Chapman-Stern theory which provides a good estimate for the minimal concentration of cations required to produce complexes. Coarse-grained Monte Carlo calculations support X-ray diffraction experiments in the sense that lipids form inverted micelles around hexagonally arranged DNA rods, with cations in between to maintain the cohesion. The complexes are more cohesive in terms of total free energy as the cation valence increases. The presented methodology may help develop predictive models for biomolecular self-assembled systems.     

Scalable and Systolic Architecture for Computing Double Exponentiation Over GF(2 m )

Double-exponentiation is a crucial arithmetic operation for many cryptographic protocols. Several efficient double-exponentiation algorithms based on systolic architecture have been proposed. However, systolic architectures require large circuit space, thus increasing the cost of the protocol. This would be a drawback when designing circuits in systems requiring low cost and low power consumption. However, some cost savings can be attained by compromising speed, as in portable devices and many embedded systems. This study proposes a scalable and systolic AB ² and a scalable and systolic A × B, which are the core circuit modules of double-exponentiation. A scalable and systolic double-exponentiation can thus be obtained based on the proposed scalable AB ² and A × B architecture. Embedded system engineers may specify a target double-exponentiation with appropriate scaling systolic circuits. The proposed circuit has lower circuit space/cost and low time/propagation than other circuits.     

The preparation and properties of neutral diamide ionophores for group IIa metal cations

The preparation of a series of neutral ligands featuring ether and N-methyl-N-carbethoxypentylamide groups is described. These ligands as well as related ones bearing other diamide groups are shown to selectively chelate Group IIA cations by picrate extraction from water to methylene chloride. The changes in UV absorption of aromatic rings and amide groups in the ligands upon titration with metal salts in methanol allow the estimation of the stoichiometry of complexation and the ordering of cation binding. The observed selectivity sequences of cation extraction and binding are briefly discussed. Preliminary proton and ¹³C NMR studies on the effect of addition of Group IIA cation salts to several of the ligands in methanol suggest that most of the complexation occurs at the central ether and amide groups. ¹³C NMR T₁ changes by the Inversion Recovery Fourier Transform method are in agreement with the cation-induced shift data.     

Effects of Na‐sulfopropyl groups on the mechanical properties and morphology of polystyrene‐co‐methacrylate ionomers

The dynamic mechanical properties and morphology of poly(styrene‐co?3‐sulfopropyl sodium‐methacrylate) SSPMANa ionomers were investigated. It was found the increasing rate of ionic moduli of the SSPMANa ionomer was very low, and the cluster T_g of the ionomers remained more or less constant with increasing ion content. A well‐developed SAXS peak was seen for low ion content SSPMANa ionomers and the peak position changed slightly with ion content. Thus, it was suggested that the presence of the alkyl ester side chains made the ion pairs form multiplets more easily at their prevalent distances, and the small‐agglomerated multiplets were dispersed in the polymer matrix relatively evenly. The interpretation of ionic moduli using a number of theories implied that the multiplets and clusters acted as effective crosslinks and filler particles, respectively, and the size and shape of the clusters were irregular. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1043–1053     

Incident-angle-dependent reflectance in distributed Bragg reflectors fabricated from ZnO/MgO multilayer films

We present the incident-angle-dependent reflectance spectra of the 10-period ZnO/MgO multilayer films deposited on Si by sputtering technique. As increasing the incident angle, the resonant wavelength and bandwidth of the measured reflectance spectra exhibit redshift and narrower, respectively. The theoretical curves using transfer matrix method taken account of transverse electric (TE) and transverse magnetic (TM) polarizations are calculated to well describe the variations in the behavior of the experimental spectra. The simulated TE- and TM-reflection band at different angles can evaluate the bandwidth of the resonance band and provide valuable parameters to design an omnidirectional-reflection band in selected multilayer structure.     

Branching features of photonic bandgaps in Fibonacci dielectric heterostructures

We propose branching features of photonic band gaps in one-dimension Fibonacci dielectric heterostructures with arbitrary generation orders and thicknesses based on the gap map diagram, which is determined by the band edge formalism to avoid numerical instability. We find that the gap map diagram can be divided by the half-wave lines into several regions, each of which has similar gap pattern. The branching rules including the existence condition and the frequency range of each major gap as well as the number of all minor gaps in each region for systems with arbitrary thicknesses and generations are proposed. The number of major gaps in each region for the Fibonacci systems equals two rather than one for traditional binary layers. Moreover, the conditions of maximum gapwidth for the Fibonacci systems are not near the quarter wavelength, although the ones for traditional binary layers are at the quarter wavelength.