Laminar and blazed type holographic gratings for a versatile soft x-ray spectrograph attached to an electron microscope and their evaluation in the 50-200 eV range

Laminar and blazed type holographic varied-line-spacing spherical gratings for use in a versatile soft x-ray flat-field spectrograph attached to an electron microscope are designed, fabricated, and evaluated. The absolute diffraction efficiencies of laminar (or blazed) master and replica gratings at 86.00° incidence evaluated by synchrotron radiation show over 5% (or 8%) in the 50-200 eV range with the maxima of 22% (or 26%-27%). Also the resolving power evaluated by a laser produced plasma source is in excess of 700 at the energy near the K emission spectrum of lithium (~55 eV) for all gratings. Moreover, the K emission spectrum of metallic Li with high spectral resolution is successfully observed with the spectrograph attached to a transmission electron microscope.     

On-chip molecular communication: analysis and design

We consider a confined space molecular communication system, where molecules or information carrying particles are used to transfer information on a microfluidic chip. Considering that information-carrying particles can follow two main propagation schemes: passive transport, and active transport, it is not clear which achieves a better information transmission rate. Motivated by this problem, we compare and analyze both propagation schemes by deriving a set of analytical and mathematical tools to measure the achievable information rates of the on-chip molecular communication systems employing passive to active transport. We also use this toolbox to optimize design parameters such as the shape of the transmission area, to increase the information rate. Furthermore, the effect of separation distance between the transmitter and the receiver on information rate is examined under both propagation schemes, and a guidepost to design an optimal molecular communication setup and protocol is presented.     

Glancing angle deposition of copper iodide nanocrystals for efficient organic photovoltaics

We report a simple method to achieve efficient nanostructured organic photovoltaics via patterning copper iodide (CuI) nanocrystals on indium tin oxide by glancing angle deposition. The strong interfacial interaction between zinc phthalocyanine (ZnPc) and CuI leads to the formation of nanopillar arrays with lying-down molecular order, which greatly improve light absorption and surface roughness for exciton dissociation. Optimized ZnPc/C(60) bilayer cell has a power conversion efficiency of 4.0 ± 0.1%, which is about 3-fold larger than that of conventional planar cell.     

The so-called alkali-carbonate reaction (ACR) — Its mineralogical and geochemical details, with special reference to ASR

Typical examples of so-called alkali-carbonate reaction (ACR) in the Canadian field concretes in Ontario, CSA concrete prism, RILEM concrete microbars and RILEM mortar bar containing Pittsburg aggregate, were examined petrographically based on polarizing microscopy, SEM observation and quantitative SEM-EDS analysis of the reaction products. It was revealed that ASR gel was the main product responsible for the crack formation in concretes, and that this gel had a common nature to that in the typical ASR. That is, ASR gel presented distinctive compositional trend lines, passing from low-Ca ASR gel at [Ca/Si] = 1/2-1/6, [Ca]/[Na + K] = 1.0 to the “convergent point” with [Ca/Si] = 1.3-1.8, [Ca]/[Na + K] = 100 at which chemical equilibrium is attained with CSH gel. The so-called ACR is a combination of deleteriously expansive alkali-silica reaction (ASR) of cryptocrystalline quartz, and harmless dedolomitization which produces brucite and carbonate halo. In laboratory specimens, fine dolomitic aggregate undergoes dedolomitization, and brucite and ASR gel react to form non-expansive Mg-silicate gel on the dolomite crystals. This explains why the mortar bar produces smaller expansion than the concrete microbar, and why the reaction products are so minute that they escape attention by optical microscopy. As a crystalline counterpart, mountainite is a candidate for low-Ca ASR gel, while sepiolite is one for Mg-silicate gel. Concealed ASR was detected in ACR-affected field concretes undergoing ingress of deicing salt which formed Friedel's salt and Cl-doped CSH gel. Compositions of ASR products, methods of sample preparation and analysis for correct identification of ACR, and artifacts were critically reviewed.     

Structural optimization of gas diffusion electrodes loaded with LaMnO3 electrocatalysts

In this study, gas diffusion electrodes (GDEs) with two catalyst layers were fabricated and tested for their electrode performance for oxygen reduction in an alkaline solution. The LaMnO₃/carbon black catalyst layers were fabricated using a reverse micelle method to finely disperse the LaMnO₃ particles onto the carbon matrices, for which commercial Ketjen Black (KB) (1270 m² g⁻¹) and Vulcan XC-72R (VX) (254 m² g⁻¹) were used. The three-layer-structured GDE with the two LaMnO₃/KB and LaMnO₃/VX catalyst layers exhibited a superior oxygen reduction activity when compared to that of a conventional GDE with only one LaMnO₃/KB catalyst layer. Pore size distribution and gas permeability measurements revealed that the LaMnO₃/VX layer was more porous and had higher gas permeability than the LaMnO₃/KB layer. These results suggest that the intermediate layer of LaMnO₃/VX can efficiently supply oxygen to reaction sites dispersed in the LaMnO₃/KB and LaMnO₃/VX catalyst layers, which consequently leads to an improvement in the electrode performance.     

Effects of processing additives on nanoscale phase separation,crystallization and photovoltaic performance of solar cells based on mesogenic phthalocyanine

A study on the effects of processing additives on the nanoscale phase separation, crystallization, and photovoltaic performance of bulk heterojunction (BHJ) thin films made of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH₂) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) via spin-casting for photovoltaic applications is reported. By incorporating various solvents as processing additives to a volume of a few percent, the separation of donor and acceptor phases in C6PcH₂:PCBM thin films, which discussed by taking the photoluminescence quenching, Davydov splitting at the Q-band of the absorbance spectra and the surface nanomorphology into consideration, is improved, and the crystallinity of the discotic C6PcH₂ molecules with hexagonal structures is reinforced. Photovoltaic cells with the optimum phase-separated BHJ materials and high crystallinity of the discotic C6PcH₂ molecules are demonstrated to have a power conversion efficiency of 4.2%.     

LSPIV implementation for environmental flow in various laboratory and field cases

Large-Scale Particle Image Velocimetry (LSPIV) is an extension of a quantitative imaging technique to measure water surface velocities using simple and inexpensive equipment. This paper describes the implementation of imaged-based LSPIV in eight different environmental flow and hydraulic engineering applications for the investigation of complex configurations with and without sediment transport (bed and suspended loads). These applications include the investigation of sedimentation in shallow reservoirs, run-of-river hydropower plants, side weirs used to control bank overflow, flow fields in different spillway configurations with and without Piano Key Weir (PKW), oil spills with flexible and rigid barriers, groin fields, river confluence, and sediment flushing in reservoirs. The paper summarises some special problems encountered in such study cases. The selection and adjustments of the parameters to solve them properly were examined. The potential of LSPIV to measure surface flow velocities in the context of river and dam engineering projects is shown. Despite significant variations of natural and artificial illuminations and seeding tracers in the laboratory, field, wind, and water surface elevation, LSPIV was applied successfully to obtain velocity measurements. LSPIV has proven to be a reliable, flexible, and inexpensive flow diagnostic tool that can be employed successfully in many engineering applications.     

Amorphous In–Ga–Zn–O thin‐film transistors prepared by magnetron sputtering using Kr and Xe instead of Ar

Heavier noble gases Kr and Xe instead of the lighter Ar during the magnetron‐sputtering deposition of amorphous indium–gallium–zinc oxide films are introduced in fabricating their thin‐film transistors (TFTs). Heavy noble gases can reduce damage to film induced by ion bombardment during the sputtering depositions. Higher field‐effect mobility with better gate bias stability can be obtained in the heavier‐noble‐gas sputtered TFTs. Raman spectroscopic analysis and X‐ray reflectometry respectively suggest that the disordered structure in the film is suppressed, and the film becomes denser by introducing heavy noble gases, corresponding to the improvement of TFT performance.     

Anodic electrode reaction of p-type silicon in 1-ethyl-3-methylimidazolium fluorohydrogenate room-temperature ionic liquid

The anodic electrode behavior for a p-type silicon single crystal electrode ((1 0 0), ρ = 0.01-0.02 Ω cm, boron doped) was examined in the 1-ethyl-3-methylimidazolium fluorohydrogenate, EtMeIm(FH)_2.3F, room-temperature ionic liquid (RTIL). The electrochemical behavior was very similar to that in conventional HF aqueous solution. After the anodic electrode reaction, the Si electrode was uniformly covered with a mesoporous Si layer having a pore size of ∼25 nm. The mesoporous layer did not exhibit a photoluminescence spectrum in the visible region due to the lack of Si-H termination. However, after chemical treatment with an ethanolic HF solution, a subset of the porous Si samples showed a very weak photoluminescence.     

Photocatalytic activities of AgSbO3 under visible light irradiation

A novel visible light sensitive photocatalyst, AgSbO₃ was prepared by a conventional solid-state reaction method. This oxide belonging to a cubic-pyrochlore structure can absorb visible light with wavelength up to about 480 nm. From the band structure calculation, we found that the top of the valence band consists of the hybridized Ag 4d and O 2p orbitals and the bottom of the conduction band mainly consists of the Ag 5s and the Sb 5s orbitals. Photocatalytic activities were evaluated using O₂ evolution from an aqueous silver nitrate solution and decomposition of gaseous 2-propanol under visible light irradiation. We found that AgSbO₃ shows a higher O₂ evolution activity than WO₃ and 2-propanol can be mineralized by the AgSbO₃ photocatalysis under visible light irradiation.