Hydrogen sulfide gas detection by Au-decorated ZnO nanotube: a computational study and comparison to experimental observations

Based on the experimental reports, Au-decoration on the ZnO nanostructures dramatically increases the electronic sensitivity to H₂S gas. In the current study, we computationally scrutinized the mechanism of Au-decoration on a ZnO nanotube (ZON) and the influence on its sensing behavior toward H₂S gas. The intrinsic ZON weakly interacted with the H₂S gas with an adsorption energy of ?11.2 kcal/mol. The interaction showed no effect on the HOMO–LUMO gap and conductivity of ZON. The predicted response of intrinsic ZON toward H₂S gas is 6.3, which increases to 78.1 by the Au-decoration at 298 K. The corresponding experimental values are about 5.0 and 80.0, indicating excellent agreement with our findings. We showed that the Au atom catalyzes the reaction 3O₂?+?2H₂S?→?2SO₂?+?2H₂O. Our calculated energy barrier (at 298 K) is about 12.3 kcal/mol for this reaction. The gap and electrical conductance Au-ZON largely changed by this reaction are attributed to the electron donation and back-donation processes. The obtained recovery time is about 1.35 ms for desorption of generated gases from the surface of the Au-ZON sensor.     

Comparing photocatalytic activity consisting of Sb2S3 and Ag2S on the TiO2–SiO2/TiO2 nanotube arrays-support for improved visible-light-induced photocatalytic degradation of a binary mixture of basic blue 41 and basic red 46 dyes

In the present study, a TiO₂ nanotube (TNAs) supported Sb₂S₃–TiO₂–SiO₂ (STS/TNAs), and Ag₂S–TiO₂–SiO₂ (ATS/TNAs) hybrid novel photocatalysts were prepared and characterized by XRD, FT-IR, SEM-EDX, X-ray mapping and, DRS. EIS was employed, and an equivalent circuit model is proposed. Flat-band potential and free carrier concentration were determined by Mott–Schottky plots. The obtained catalysts were used in the photodegradation of a binary mixture of Basic Blue 41 (BB41) and Basic Red 46 (BR46) dyes. Compared with ATS/TNAs, STS/TNAs photocatalyst showed the highest apparent rate constant for BB41 dye, about two times higher, and BR41 dye more than 1.5 times. EIS results agreed with the photodegradation results, so the STS/TNAs system with higher charge transfer ability than the ATS/TNAs system showed the best photodegradation activity. The optimization effect of the amount of Sb₂S₃, TiO₂, and SiO₂ doped on the TNAs on the photocatalytic activity of the STS/TNAs was done using a central composite rotatable design (CCRD) based response surface methodology (RSM). Results have shown catalyst containing 12.2% Sb₂S₃ and 27.1% SiO₂/TNAs (S₃TS₃/TNAs) the best photodegradation activity was obtained. The GC-Mass analysis was done to detect the degradation intermediates formed during the photodegradation process.     

Improving the functional properties of fish gelatin by conjugation with the water-soluble fraction of bitter almond gum

Food Science and Biotechnology - Maillard-based conjugation may be a useful way of improving the functional properties of food biopolymers. In this study, covalent attachment of fish gelatin (FG)...     

Role of morphology in electrochemical hydrogen storage using binary DyFeO3-ZnO nanocomposites as electrode materials

Hydrogen storage technology is one of the most challenging issues due to the increasing demand for fossil fuel replacement and the reduction of greenhouse gas emissions. In the current paper, the main aim is one-step and eco-friendly preparation of DyFeO₃-ZnO nanocomposites using Barberry fruit extract as natural precursor (with the role of both fuel and capping agent) to compare with various conventional carboxylic acids. To further examine, the effect of different parameters like calcination temperature and the type of the chelating agent was scrutinized to acquire optimum shape, structure, morphology and size of the obtained products. This is the first effort on the investigation of the hydrogen storage capacity of DyFeO₃-ZnO nanocomposites in terms of role of morphology. The electrochemical hydrogen storage capacity of obtained DyFeO₃-ZnO nanocomposites was studied mediated by chronopotentiometry charge-discharge methods in KOH medium. The synthesis of nanocomposites in the presence of chemical or natural capping agent (carboxylic acids or Barberry fruit extract) led to different morphologies which affects to the electrochemical performance. As a result, the electrode which is provided by plate-like DyFeO₃-ZnO nanocomposites performed 600.11 mAh/g discharge capacity compared with other samples. Based on the obtained results, DyFeO₃-ZnO nanocomposites can be promising compounds to improve the electrochemical performance of hydrogen storage.     

The effect of measurement error on the performance of Mann-Whitney and Signed-Rank nonparametric control charts

Mann-Whitney and Signed-Rank control charts are two well-known nonparametric charts used for controlling the center of the process when the distribution of the process parameter is unknown or nonnormal. Considering the effect of measurement error on the performance of control charts, the mentioned effect with additive model is investigated on Mann-Whitney and Signed-Rank charts. Furthermore, a comparison is made between the two charts and a Shewhart-type $\overline{\mathrm{X}}$ chart (as a parametric one) in the presence of the error. To do so, a simulation program is used and average run length (ARL) of the charts are calculated under three distributions. The results for all three distributions show that the existence of measurement error weakens the performances of both nonparametric charts and larger values of the variance of the error will increase the effect. A numerical example is also discussed to show the effect on the performance of the charts. Multiple measurements is used as a way to decrease the effect of measurement error. Knowing the fact that it requires extra time and money, it can be used in real cases depending on the financial limitations of the user.     

Inter-cell interference in multi-tier heterogeneous cellular networks: modeling and constraints

Telecommunication Systems - Interference is the main source of capacity limitation in wireless networks. In some medium access technologies in cellular networks, such as OFDMA, the allocation of...     

An Adaptable and Scalable Generator of Distributed Massive MIMO Baseband Processing Systems

Journal of Signal Processing Systems - This paper presents an algorithm-adaptable, scalable, and platform-portable generator for massive multiple-input multiple-output (MIMO) baseband processing...     

A computer-aided diagnostic system for liver tumor detection using modified U-Net architecture

The Journal of Supercomputing - A multimedia-based medical decision-making system is an ultimate requirement in the medical imaging domain. In the healthcare sector, achieving quick and efficient...