Dinitrosyl iron complexes: From molecular electrocatalysts to electrodeposited‐film electrodes for hydrogen evolution reaction

Clean and large‐scale production of hydrogen via water splitting triggered by active, robust, and low‐cost electrocatalysts is a promising and sustainable strategy for energy conversion and storage. In this study, a series of four‐coordinated chelating amine‐bound {Fe(NO)₂}¹⁰ dinitrosyl iron complexes (DNICs) [(L)Fe(NO)₂] were synthesized to investigate how the electronic structure of [Fe(NO)₂] unit of DNICs was tailored to promote the electrocatalytic hydrogen evolution reaction (HER) triggered by the homogeneous DNICs' molecular catalysts and the heterogeneous DNIC‐derived electrodeposited‐film electrodes. The electrochemical studies demonstrate that HER onset potentials of those DNICs in neutral sodium sulfate aqueous solution are dependent on their IR ν_(NO) stretching frequencies, indicating that the electron‐rich [Fe(NO)₂] core modulated by the synergistic cooperation of the electron‐donating ability and steric effect of methyl‐/hydrogen‐substituted diamine‐coordinated ligands, presumably, benefits the formation of metal‐hydride intermediate to reduce the required onset potential. In contrast with homogeneous catalyst retaining its molecular integrity during the catalytic HER process, it is noticed that DNICs [(L)Fe(NO)₂] act as the precursor of the active heterogeneous HER catalyst during the electrocatalytic HER process. It is presumed that the intermolecular hydrogen‐bonding interactions among DNICs [(L)Fe(NO)₂] may control the particle sizes of DNIC‐derived electrodeposited film to modulate HER efficiency.     

Preparation and luminescence properties of Y2(WO4)3: Eu3+

A red-emitting Y₂(WO₄)₃: Eu³⁺ phosphor (orthorhombic high temperature phase, anhydride) is prepared by two different methods: the firing of mixtures of constituent oxides and that of precipitates from aqueous solutions. After optimizing preparation conditions, the cathodoluminescence brightness reaches 56% that of Y₂O₂S: Eu³⁺, a commercial red phosphor for color TV. Formation of a high temperature phase below the reported transition temperature is noted in the fired precipitates. This phase occurrence is shown to depend on the treatment of the precipitates to be fired. Reflection difference measurement of Eu-doped and undoped samples assigns an excitation band of about 245 nm to the Eu-O charge transfer band. Different by-products in the two preparation methods are identified by measuring emission spectra under selective excitation. Reversible hydration-dehydration of the phosphor is demonstrated by successively measuring photoluminescence first in vacuum and then in air at various temperatures. No deterioration of luminescence efficiency is observed after repeating this reversible structural change.     

Nanoscale deformation measurement by using the hybrid method of gray-level and holographic interferometry

This study extends the use of holographic interferometry to measure the nanoscale out-of-plane displacement with high surface resolution. It is noted that if the deformation is less than half of the optical wavelength, it is hard to find an obvious fringe pattern. Under such a situation, in general, the phase shift method is used. However, it needs to take more than 3 images for phase shifting and phase reconstruction In this paper, a more simple hybrid method of gray-level and holographic interferometry is used to extract fringe skeletons, in which it just needs to take one or two images for the normal deformation measurement directly, even if there exists no obvious fringe pattern. The displacement field with high surface resolution can also be obtained. The proposed method yielded a theoretical precision of 0.15 nm for out-of-plane displacement with a monochromatic CCD camera of 10-bit gray scale (1024 gray scales) sensitivity and microscale surface resolution for millimeter scale object with 640×480 pixels image resolution by an He–Ne LASER (632.8 nm wavelength) light source. The gray-level method is proposed to calculate the non-obvious interferometry fringe by traditional holographic interferometry hologram, and the result showed that this method works for this purpose.     

A refined cellular automaton model to rectify impractical vehicular movement behavior

When implementing cellular automata (CA) into a traffic simulation, one common defect yet to be rectified is the abrupt deceleration when vehicles encounter stationary obstacles or traffic jams. To be more in line with real world vehicular movement, this paper proposes a piecewise-linear movement to replace the conventional particle-hopping movement adopted in most previous CA models. Upon this adjustment and coupled with refined cell system, a new CA model is developed using the rationale of Forbes’ et al. car-following concept. The proposed CA model is validated on a two-lane freeway mainline context. It shows that this model can fix the unrealistic deceleration behaviors, and thus can reflect genuine driver behavior in the real world. The model is also capable of revealing Kerner’s three-phase traffic patterns and phase transitions among them. Furthermore, the proposed CA model is applied to simulate a highway work zone wherein traffic efficiency (maximum flow rates) and safety (speed deviations) impacted by various control schemes are tested.     

1.3 m m InGaAsN/ GaAs Lasers Grown by MOCVD Using TBAs and DMHy Sources

We have demonstrated InGaAsN/ GaAs single quantum well (SQW) lasers grown by MOCVD using TBAs and DMHy sources. For un-buffer-strained InGaAsN/ GaAs system, our SQW lasers of 1.3 m m range is among the best in terms of transparency and threshold current density.     

Cellular automaton simulations for mixed traffic with erratic motorcycles’ behaviours

Modeling mixed traffic composed of motorcycles can be a challenging issue because many erratic motorcyclists may not follow the lane disciplines, particularly when traffic is congested. Based upon the refined cellular automaton (CA) model recently developed by the authors [L.W. Lan, Y.C. Chiou, Z.S. Lin, C.C. Hsu, Physica A 388 (2009) 3917-3930], this paper further proposed a sophisticated CA model to elucidate the erratic motorcycle behaviours in mixed traffic contexts. In addition to the conventional moving forward and lane-change rules, the sophisticated CA model also explicated the lateral drift behaviour for cars moving in the same lane, the lateral drift behaviour for motorcycles breaking into two moving cars, and the transverse crossing behaviour for motorcycles through the gap between two stationary cars in the same lane. Fundamental diagrams and space-time trajectories for vehicles with various car-motorcycle mixed ratios are demonstrated.     

Measurements of long-term changes in atmospheric OCS (carbonyl sulfide) from infrared solar observations

Multi-decade atmospheric OCS (carbonyl sulfide) infrared measurements have been analyzed with the goal of quantifying long-term changes and evaluating the consistency of the infrared atmospheric OCS remote-sensing measurement record. Solar-viewing grating spectrometer measurements recorded in April 1951 at the Jungfraujoch station (46.5°N latitude, 8.0°E longitude, 3.58 km altitude) show evidence for absorption by lines of the strong ν₃ band of OCS at 2062 cm⁻¹. The observation predates the earliest previously reported OCS atmosphere remote-sensing measurement by two decades. More recent infrared ground-based measurements of OCS have been obtained primarily with high-resolution solar-viewing Fourier transform spectrometers (FTSs). Long-term trends derived from this record span more than two decades and show OCS columns that have remained constant or have decreased slightly with time since the Mt. Pinatubo eruption, though retrievals assuming different versions of public spectroscopic databases have been impacted by OCS ν₃ band line intensity differences of ∼10%. The lower stratospheric OCS trend has been inferred assuming spectroscopic parameters from the high-resolution transmission (HITRAN) 2004 database. Volume mixing ratio (VMR) profiles measured near 30°N latitude with high-resolution solar-viewing FTSs operating in the solar occultation mode over a 22 years time span were combined. Atmospheric Trace MOlecucle Spectroscopy (ATMOS) version 3 FTS measurements in 1985 and 1994 were used with Atmospheric Chemistry Experiment (ACE) measurements during 2004-2007. Trends were calculated by referencing the measured OCS VMRs to those of the long-lived constituent N₂O to account for variations in the dynamic history of the sampled airmasses. Means and 1-sigma standard deviations of VMRs (in ppbv, or 10⁻⁹ per unit air volume) averaged over 30-100 hPa from measurements at 25-35°N latitude are 0.334±0.089 ppbv from 1985 (ATMOS Spacelab 3 measurements), 0.297±0.094 ppbv from 1994 ATLAS 3 measurements, 0.326±0.074 ppbv from ACE 2004 measurements, 0.305±0.096 ppbv from ACE 2005 measurements, 0.328±0.074 from ACE 2006 measurements, and 0.305±0.090 ppbv from ACE measurements through August 2007. Assuming these parameters, we conclude that there has been no statistically significant trend in lower stratospheric OCS over the measurement time span. We discuss past measurement sets, quantify the impact of changes in infrared spectroscopic parameters on atmospheric retrievals and trend measurements, and discuss OCS spectroscopic uncertainties of the current ν₃ band parameters in public atmospheric databases.     

Performance of a wavelength-tunable erbium-doped fiber laser using a Sagnac interferometer

We experimentally demonstrate a wavelength-tunable erbium-doped fiber laser that is composed of a ring cavity and a single-mode fiber Sagnac interferometer in a new and simple arrangement. We find that the fiber laser output wavelength is tunable by adjusting the filter effect of the Sagnac fiber loop through a fiber polarization controller set there. The quasi-single-wavelength continuously tunable laser outputs could be achieved within some wavelength range. The multi-wavelength laser outputs could also be observed under some appropriate settings of the polarization controller. A theoretical demonstration of the wavelength tunability about the transmission-type Sagnac loop filter has also been achieved using the Jones calculus theory.     

Focusing and waveguiding of Lamb waves in micro-fabricated piezoelectric phononic plates

This paper presents results on the numerical and experimental studies of focusing and waveguiding of the lowest anti-symmetric Lamb wave in micro-fabricated piezoelectric phononic plates. The phononic structure was based on an AT-cut quartz plate and consisted of a gradient-index phononic crystal (GRIN PC) lens and a linear phononic plate waveguide. The band structures of the square-latticed AT-cut quartz phononic crystal plates with different filling ratios were analyzed using the finite element method. The design of a GRIN PC plate lens which is attached with a linear phononic plate waveguide is proposed. In designing the waveguide, propagation modes in square-latticed PC plates with different waveguide widths were studied and the results were served for the experimental design. In the micro-fabrication, deep reactive ion etching (Deep-RIE) process with a laboratory-made etcher was utilized to fabricate both the GRIN PC plate lens and the linear phononic waveguide on an 80 μm thick AT-cut quartz plate. Interdigital transducers were fabricated directly on the quartz plate to generate the lowest anti-symmetric Lamb waves. A vibro-meter was used to detect the wave fields and the measured results on the focusing and waveguiding of the piezoelectric GRIN PC lens and waveguide are in good accordance with the numerical predictions. The results of this study may serve as a basis for developing an active micro plate lens and related devices.     

Lead Tetraacetate Oxidation on Caryachine,A Phenolic Pavine

Lead tetraacetate oxidation on caryachine, a pavine alkaloid possessing a phenolic group at the position para to the N-methine, in dichloromethane yielded four products — 10-acetoxy-O-acetyl-caryachine, 10-acetoxycaryachine, 7-acetoxy-O-acetylcaryachine and (6S, 11R, 12R)-11-acetoxy-O-acetyl-caryachine. The reaction took place via adoption of an acetoxy group at a position majorly ortho to the phenolic group, but very minorly at the desired benzylic position para to the phenolic group.