Operations on logic functions and variables through sign Haar spectra

A non-linear transform, called “sign Haar transform” has recently been introduced. The transform is unique and converts binary/ternary vectors into ternary spectral domain. Recursive definitions for the calculation of sign Haar transform are developed. Essential properties of logic functions and variables in the spectral domain of a quantized transform based on Haar functions are presented. Sign Haar transform has the smallest computational cost of all the quantized transforms. The properties of logic functions are listed for two different codings of incompletely specified functions.     

Experimental study of the natural organic matters effect on the power generation of reverse electrodialysis

In this paper, the effect of natural organic matters (NOMs), which are typically present in river and seawater, on the power generation of reverse electrodialysis was studied. Bovine serum albumin, humic acid, and sodium alginate were used as models of NOMs. A NOM model was added to concentrated salt water, diluted salt water, and/or both of them. Power density was used to measure the resulted power generation. Fourier transform infrared spectroscopy and scanning electron microscope were used to characterize the presence of NOMs on the membrane surfaces. The effect of NOMs on the generated power density was clearly observed. This effect was influenced by the NOM's type, the NOMs concentration, and the compartment in which NOMs are added. Fourier transform infrared spectroscopy and scanning electron microscope data confirmed that NOMs are deposited on both anion and cation exchange membrane surfaces. While all NOMs added to concentrated salt water did not influence the generated power density, different power density behavior was resulted from the different NOMs added to diluted salt water, where NOMs could increase or decrease or remain the generated power density. Thus, besides NOM's type, the salt concentration is very critical to determine the effect of NOMs on the generated power density. Copyright © 2017 John Wiley & Sons, Ltd.     

Enhanced photocatalytic hydrogen production of noble-metal free Ni-doped Zn(O,S) in ethanol solution

High efficient hydrogen evolved Ni-doped Zn(O,S) photocatalyst with different Ni amounts had been successfully synthesized with a simple method at low temperature. Our Ni-doped Zn(O,S) catalyst reached the highest hydrogen generation rate of 14,800 μmol g^?1 h^?1 or 0.92 mmol g^?1 h^?1 W^?1 corresponding to apparent quantum yield 31.5%, which was 2.3 times higher compared to the TiO₂/Pt used as a control in this work. It was found that a small amount of Ni doped into Zn(O,S) nanoparticles could increase the optical absorbance, lower the charge transfer resistance, accordingly decrease the electron-hole recombination rate, and significantly enhance the photocatalytic hydrogen evolution reaction (HER). The as-prepared catalyst has the characteristics of low cost, low power consumption for activating the catalytic HER, abundant and environmental friendly constituents, and low surface oxygen bonding for forming oxygen vacancies. The photocatalytic performance of Ni-doped Zn(O,S) was demonstrated with a proposed kinetic mechanism in this paper.     

Facile synthesis of cobalt-doped (Zn,Ni)(O,S) as an efficient photocatalyst for hydrogen production

Cobalt-doped (Zn,Ni)(O,S) or Co-(Zn,Ni)(O,S) was facilely synthesized at low temperature below 100 °C with different cobalt precursor contents for photocatalytic hydrogen production. The X-ray pattern and elemental mapping proved that cobalt was successfully doped into zinc sites in the (Zn,Ni)(O,S) host lattice. We found the incorporation with a small amount of cobalt into (ZnNi)(O,S) enhanced its photo activity for hydrogen production. The best hydrogen production was achieved for 2.5% Co-(ZnNi)(O,S) with a rate of 8,527 μmol/g·h during a span of 5 h in a 20% (v/v) ethanol/water solution. Based on the results of optical characterizations, the enhancement of hydrogen production was caused by the slow electron-hole recombination and the low charge transfer resistance. A different photocatalytic kinetic mechanism for hydrogen generation from the conventional one with the simultaneous formation of hydrogen and oxygen gases is proposed, based upon the activated surface oxygen anion to initiate or trigger the key reaction of oxidation for water splitting to proceed. Our strategy in preparing catalyst at low process temperature and in doping to activate catalyst is for weakening the lattice oxygen bonding on the catalyst surface in order to firstly initiate the oxidation reaction and the formation of oxygen vacancies. These freshly formed oxygen vacancies play a critical role to trap the water and weaken its OH bonding to form hydrogen gas through the reduction reaction.     

Indium oxysulfide nanosheet photocatalyst for the hexavalent chromium detoxification and hydrogen evolution reaction

Indium oxysulfide nanosheet (In₂(O,S)₃ NS) had been successfully synthesized by a solution-based process at 90 °C. To further study some properties of photocatalyst, the 90 °C-prepared In₂(O,S)₃ NS was annealed at 350, 400, and 450 °C in air for 2 h. It was found that the nanosheet structure at 90 °C changed to nanoparticle at higher temperature. All the as-prepared and annealed photocatalysts were carefully characterized and examined toward photocatalytic hexavalent chromium (Cr(VI)) reduction. Among the photocatalysts, 90 °C-prepared In₂(O,S)₃ NS exhibited the greatest photocatalytic reduction of Cr(VI) without using any hole scavenger reagent under 150 W visible light illumination. After the Ag deposition on In₂(O,S)₃ NS, the photocatalyst could produce nearly 400 μmol/g hydrogen gas in ethanol solution under 150 W Xe-lamp irradiation for 5 h. The great performance of 90 °C-prepared In₂(O,S)₃ NS was due to the high surface area of nanosheet morphology and the formation of solid solution which significantly increased the visible light absorbance. The photocatalytic activities and their mechanisms of 90 °C-prepared In₂(O,S)₃ NS were evaluated and elaborated in this work.     

Plasma-induced quantum well intermixing for monolithic photonic integration

Plasma-induced quantum well intermixing (QWI) has been developed for tuning the bandgap of III-V compound semiconductor materials using an inductively coupled plasma system at the postgrowth level. In this paper, we present the capability of the technique for a high-density photonic integration process, which offers three aspects of investigation: 1) universality to a wide range of III-V compound material systems covering the wavelength range from 700 to 1600 nm; 2) spatial resolution of the process; and 3) single-step multiple bandgap creation. To verify the monolithic integration capability, a simple photonic integrated chip has been fabricated using Ar plasma-induced QWI in the form of a two-section extended cavity laser diode, where an active laser is integrated with an intermixed low-loss waveguide.     

Selective Oxidation and Sub-surface Phase Transformations in Chromium-bearing Austenitic Steels

A series of Fe–15Cr–(2–3)Mo–(0.7–2.5)C (compositions in weight percent) steels was oxidised at 850°C and P_{O_2} = 5.8 × 10^–20 atm, where iron oxide is unstable. All grew external Cr₂O₃ scales according to parabolic kinetics. Depletion of chromium from alloy subsurface regions led to dissolution of chromium-rich carbides if the original alloy carbon level was less than 1.2%. Simultaneous decarburisation caused a transformation of the original austenitic or austenoferritic structure into single-phase ferrite, stabilised by the molybdenum. Diffusion analysis of the concentration profiles within this transformed zone led to satisfactory agreement with the known diffusion coefficient for chromium in ferrite. At high carbon levels, decarburisation was slow, resulting in low chromium concentrations at the internal alloy–carbide interfaces. In these cases, the carbide dissolution did not proceed and chromia scaling rates were slowed.     

High Throughput Screening for the Design and Optimization of Chromatographic Processes: Assessment of Model Parameter Determination from High Throughput Compatible Data

Chromatographic processes can be optimized in various ways, and the two most prominent approaches are based either on statistical data analysis or on experimentally validated simulation models. Both strategies rely heavily on experimental data, the generation of which usually imposes a significant bottleneck on rational process design. The latter approach is followed in this work, and the utilizability of high throughput compatible experiments for the determination of model parameters which are required for in silico process optimization, is assessed. The unknown parameter values are estimated from batch uptake experiments on a robotic platform and from dynamic breakthrough experiments with miniaturized chromatographic columns. The identified model is then validated with respect to process optimization by comparison of model predictions with experimental data from a preparative scale column. In this study, a strong cation exchanger Toyopearl SP‐650M and lysozyme solved in phosphate buffer (pH 7), is used as the test system. The utilization of data from miniaturized and high throughput compatible experiments is shown to yield sufficiently accurate results, and minimizes efforts and costs for both parameter estimation and model validation.