2D sodium titanate nanosheet encapsulated Ag2O-TiO2 p-n heterojunction photocatalyst: Improving photocatalytic activity by the enhanced adsorption capacity

In a photocatalytic reaction, maintaining the high efficiency of photocatalyst under a low concentration of pollutants is a key challenge. In this work, a new 2D sodium titanate nanosheet encapsulated Ag₂O-TiO₂ (2D NTO/Ag₂O-TiO₂) p-n heterojunction photocatalyst is proposed to deal with this dilemma. Through a simple plasma electrolytic oxidation (PEO) treatment and ion exchange treatment, a classic Ag₂O-TiO₂ p-n heterojunction structure is prepared and used as the photoelectric conversion unit in the photocatalyst. Then, through a subsequent hydrothermal treatment, a 2D NTO film that serves as the adsorption unit in the photocatalyst can be produced on the surface of the Ag₂O-TiO₂ p-n heterojunction layer. Finally, the desired 2D NTO/Ag₂O-TiO₂ structure is formed. The photocatalyst exhibits superior photocatalytic performance including high degradation rate as well as excellent catalytic stability and durability by combining the high sunlight utilization efficiency and high photoelectric utilization efficiency of the Ag₂O-TiO₂ p-n heterojunction and the outstanding adsorption performance of the 2D NTO film. Therefore, the problem of photocatalytic slow kinetics under low pollutants concentration is perfectly solved. This work provides a new strategy for the structural design of high-performance photocatalysts.     

Design and eco-technoeconomic analyses of SOFC/GT hybrid systems accounting for long-term degradation effects

This study compares two SOFC/GT (solid oxide fuel cell with gas turbine) hybrid systems to that of two standalone SOFC systems via eco-technoeconomic analyses that account for long-term degradation effects. Four cases were examined: 1) standalone SOFC plant without a steam bottoming cycle; 2) standalone SOFC plant with a steam bottoming cycle; 3) SOFC/GT hybrid plant without a steam bottoming cycle; and 4) SOFC/GT with a steam bottoming cycle. This study employed a real-time 1D SOFC model with an empirical degradation calculation integrated with steady-state balance-of-plant models. Simulations used Matlab Simulink R2017a, Aspen Plus V10, and Python 3.7.4 with a pseudo steady-state approach. The results showed that, with some trade-offs, the SOFC/GT hybrid plant with the steam bottoming cycle is the best option, with an overall efficiency of 44.6% _LHV, an LCOE (levelized cost of electricity) of $US 77/MWh, and a CCA (cost of CO₂ avoided) of -$US 49.3/tonneCO₂e. The sensitivity analysis also indicated that SOFC/GT hybrid plants were less sensitive to SOFC price compared to standalone SOFC plants. The sensitivity analysis indicated that using a larger gas turbine and replacing the SOFC stack less frequently was the better design choice for the SOFC/GT hybrid plant.     

Inflammation in the Human Periodontium Induces Downregulation of the α1- and β1-Subunits of the sGC in Cementoclasts

Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the α₁- and β₁-subunits. Inflammation of the periodontium induces the resorption of cementum by cementoclasts and the resorption of the alveolar bone by osteoclasts, which can lead to tooth loss. As the presence of sGC in cementoclasts is unknown, we investigated the α₁- and β₁-subunits of sGC in cementoclasts of healthy and inflamed human periodontium using double immunostaining for CD68 and cathepsin K and compared the findings with those of osteoclasts from the same sections. In comparison to cementoclasts in the healthy periodontium, cementoclasts under inflammatory conditions showed a decreased staining intensity for both α₁- and β₁-subunits of sGC, indicating reduced protein expression of these subunits. Therefore, pharmacological activation of sGC in inflamed periodontal tissues in an NO- and heme-independent manner could be considered as a new treatment strategy to inhibit cementum resorption.     

Multiple-loss-enhanced NiOx@carbon spheres/reduced graphene oxide-based composite for tuneable elimination of electromagnetic signals

In this work, a novel graphene-based ternary composite NiO_x@CS/reduced graphene oxide (rGO) consisting of magnetic nanoparticles (NiO_x) and porous carbon spheres (CS) were successfully synthesised through facile hydrothermal and high-temperature sintering approaches. Owing to the ternary structure, the dielectric and magnetic capacity of the composite was improved. Further, the synergistic effect of two loss mechanisms improves the absorption efficiency of electromagnetic waves. The maximum reflection loss of NiO_x@CS/rGO-20 wt% was ?69.3 dB at 7.2 GHz and the absorption bandwidth with reflection loss below ?10 dB was 4.04 GHz (6.36–10.4 GHz). Hence, the NiO_x@CS/rGO ternary composite with a combination of dielectric and magnetic loss-facilitated absorption provides a new design paradigm for tuneable elimination of electromagnetic signals.     

Facile and scalable synthesis of uniform MgO/Carbon Black nano-admixture for microstructural and mechanical property improvement of magnesia-carbon refractory bricks

Facile and scalable synthesis method of MgO/Carbon Black nano-admixture as an additive for MgO/C refractory bricks has been developed via simple precipitation method. The main idea of the present work lies on the precipitation of magnesium hydroxide in well dispersed/stabilized carbon black nanoparticle suspension resulting in Mg(OH)₂/CB nano-admixture preparation. Furthermore, applying such colloidal suspension of CBs prevent the sever agglomeration of Mg-containing precipitate and make simple precipitation method as a reliable synthesis method of nano-structured MgO. Finally, different analytical methods including X-ray diffractometer, Scanning electron microscopy, Cold crushing strength and physical properties measurement have been utilized to study the effect of such nano-admixture on the microstructural and mechanical properties of typical MgO/C refractory bricks.     

Subtle gate oxide defect elimination to improve the reliability of a 32M-bit SRAM product

Tiny defects may escape from in-line defect scan and pass WAT (Wafer Acceptance Test), CP (Chip Probing), FT (Final Test) and SLT (System Level Test). Chips with such kind of defects will cause reliability problem and impact revenue significantly. It is important to catch the defects and derive the prevention strategy earlier in the technology development stage. In this paper, we investigate an SRAM with tiny defects which passed in-line defect scan, WAT, CP and FT but failed in HTOL (High Temperature Operation Life) test, one of the product reliability qualification items. FA (Failure Analysis) reveals gate oxide missing defect is the root cause. The goal is to pass reliability qualification and release product into production on schedule. The failure mechanism, optimization of gate oxide process, enhancement of defect scan and testing methodology will be introduced. Experiment results show very good HTOL performance by the combination of process and testing optimization.     

Thermal stability of devices with molybdenum oxide doped organic semiconductors

We demonstrate the thermal stability of transition-metal-oxide (molybdenum oxide; MoO₃)-doped organic semiconductors. Impedance spectroscopy analysis indicated that thermal deformation of the intrinsic 1,4-bis[N-(1-naphthyl)-N′-phenylamino]-4,4′-diamine (NPB) layer is facilitated when the MoO₃-doped NPB layer is deposited on the intrinsic NPB layer. The resistance of the intrinsic NPB layer is reduced from 300 kΩ to 3 kΩ after thermal annealing at 100 °C for 30 min. Temperature-dependent conductance/angular frequency–frequency (G/w-f-T) analysis revealed that the doping efficiency of MoO₃, which is represented by the activation energy (E_a), is reduced after the annealing process.     

Heterogeneous Reactor Modeling of an Industrial Multitubular Packed‐Bed Ethylene Oxide Reactor

The one‐dimensional heterogeneous model of an industrial multitubular packed‐bed ethylene oxide (EO) reactor was developed using the equation‐oriented platform Aspen Custom Modeler. Reactor operation was optimized in terms of maximized EO production and selectivity and enhanced safety related to the presence of oxygen in the EO reactor. Good agreement was found between the model results during validation against the available information under identical operating conditions. The model predicts the behavior of the EO reaction and demonstrates the extent of catalyst utilization with product distribution, product yield, by‐product formation, temperature and concentration profiles, over time and along the length of the reactor or catalyst bed. The model sensitivity studies compute the optimum feed flow, oxygen concentration, feed pressure, etc. and suggest the best operational philosophy.     

Annealing effects on the optical and morphological properties of ZnO nanorods on AZO substrate by using aqueous solution method at low temperature

Vertically aligned ZnO nanorods (NRs) on aluminum-doped zinc oxide (AZO) substrates were fabricated by a single-step aqueous solution method at low temperature. In order to optimize optical quality, the effects of annealing on optical and structural properties were investigated by scanning electron microscopy, X-ray diffraction, photoluminescence (PL), and Raman spectroscopy. We found that the annealing temperature strongly affects both the near-band-edge (NBE) and visible (defect-related) emissions. The best characteristics have been obtained by employing annealing at 400°C in air for 2 h, bringing about a sharp and intense NBE emission. The defect-related recombinations were also suppressed effectively. However, the enhancement decreases with higher annealing temperature and prolonged annealing. PL study indicates that the NBE emission is dominated by radiative recombination associated with hydrogen donors. Thus, the enhancement of NBE is due to the activation of radiative recombinations associated with hydrogen donors. On the other hand, the reduction of visible emission is mainly attributed to the annihilation of OH groups. Our results provide insight to comprehend annealing effects and an effective way to improve optical properties of low-temperature-grown ZnO NRs for future facile device applications.