Boosted hydrogen evolution activity from Sr doped ZnO/CNTs nanocomposite as visible light driven photocatalyst

CNTs were decorated onto Sr doped ZnO nanoparticles to construct an efficient photocatalyst via a facile sol-gel method. The as-fabricated Sr doped ZnO/CNTs with recyclability exhibits Sr and CNTs content dependent hydrogen evolution activit under visible light illumination. The Sr doped ZnO/CNTs photocatalyst shows the highest hydrogen evolution rate of 2732.2 μmolh^?1g^?1, which is 33.7 and 2.83 times higher than pure ZnO and Sr doped ZnO photocatalysts, respectively. The improved hydrogen evolution activity of Sr doped ZnO/CNTs is primarily assigned to high surface area, Sr doping and construction of heterojunction, which can extend the light absorption, decrease the optical band gap and improve the charge separation. Moreover, the underlying photocatalytic mechanism is proposed on the basis of Mott-Schottky study and explains the interfacial charge transfer process from ZnO to CNTs and Sr. This work open new strategies to synthesize CNTs based nanocomposite for hydrogen evolution.     

Silicon Mitigates Drought Stress in Wheat (Triticum aestivum L.) Through Improving Photosynthetic Pigments,Biochemical and Yield Characters

Silicon - Feeling prone to stress differs with plant production stage, water scarcity near commencement of grain filling phase has a significant reduced grain yield through fewer endosperm and sink...     

Hydrogen production employing Cu(BDC) metal–organic framework support in methanol steam reforming process within monolithic micro-reactors

Cu(BDC) metal–organic framework (MOF) was used as a support for the copper (Cu) catalyst applied in the methanol steam reforming (MSR) process at low temperatures (130–250 °C) with a feed WHSV = 9.2 h^?1 within the monolithic reactor. Also, the effects of diverse promoters were examined on the catalytic activities of the Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts. Results showed that the Ce/Sm–Cu(BDC) supports exhibited highest activities, lowest reduction temperatures and largest specific surface areas, which caused highest distributions of the active copper metal nanoparticles on the supports. The reactor tests displayed that the activities of Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts followed the order X = Ce > Sm > Y > La > Pr > Cu(BDC) > Zn > Gd. The highest activities of Ce and Sm containing catalysts were attributed to the presence of CeO₂ and Sm₂O₃ caused the oxygen vacancies on the catalyst surface which had positive effects on the methanol reforming process. The time-on-stream stability tests showed the highest resistance of the Cu/Ce–Cu(BDC) catalyst to the carbon formation during 32 h. Consequently, the Cu/Ce–Cu(BDC) with the highest stability, methanol conversion and carbon monoxide selectivity could be used in practical industrial applications.     

Feasibility of Ni/Ti and Ni/GF cathodes in microbial electrolysis cells for hydrogen production from fermentation effluent: A step toward real application

The low cost, low over-potential loss, good catalytic properties for hydrogen evolution reaction (HER), high corrosion stability, commercially available, and could be applied in pH-neutral solution and ambient temperature are important properties for the cathode materials when it is applied in microbial electrolysis cell (MEC) technology. This study has two-pronged objectives: the first is to investigate the feasibility of titanium (Ti) and graphite felt (GF) coated with nickel (Ni), and the second is to generate hydrogen from the fermentation effluent (FE). The electrodeposition (ED) method was used to deposit Ni catalyst onto Ti (Ni/Ti) and GF (Ni/GF) surfaces. The scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used to characterize the cathode morphology and element composition. The catalytic properties of Ni/Ti and Ni/GF could be evaluated using the linear sweep voltammetry tests. The maximum volumetric H₂ production rates of MEC using Ni/Ti and Ni/GF cathodes were obtained at 0.39 ± 0.01 and 0.33 ± 0.03 m³ H₂ m⁻³ d⁻¹ respectively. The Ni/Ti and Ni/GF cathodes could be used as alternative cathodes while producing hydrogen from FE.     

Stretchable Composite Acoustic Transducer for Wearable Monitoring of Vital Signs

A highly flexible, stretchable, and mechanically robust low‐cost soft composite consisting of silicone polymers and water (or hydrogels) is reported. When combined with conventional acoustic transducers, the materials reported enable high performance real‐time monitoring of heart and respiratory patterns over layers of clothing (or furry skin of animals) without the need for direct contact with the skin. The approach enables an entirely new method of fabrication that involves encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. The system proposed outperforms commercial, metal‐based stethoscopes for the auscultation of the heart when worn over clothing and is less susceptible to motion artefacts. The system both with human and furry animal subjects (i.e., dogs), primarily focusing on monitoring the heart, is tested; however, initial results on monitoring breathing are also presented. This work is especially important because it is the first demonstration of a stretchable sensor that is suitable for use with furry animals and does not require shaving of the animal for data acquisition.     

A deep learning approach with Bayesian optimization and ensemble classifiers for detecting denial of service attacks

Detecting malicious behavior is important for preventing security threats in a computer network. Denial of Service (DoS) is among the popular cyber attacks targeted at web sites of high‐profile organizations and can potentially have high economic and time costs. In this paper, several machine learning methods including ensemble models and autoencoder‐based deep learning classifiers are compared and tuned using Bayesian optimization. The autoencoder framework enables to extract new features by mapping the original input to a new space. The methods are trained and tested both for binary and multi‐class classification on Digiturk and Labris datasets, which were introduced recently for detecting various types of DDoS attacks. The best performing methods are found to be ensembles though deep learning classifiers achieved comparable level of accuracy.     

Fixed frequency sliding mode control of renewable energy resources in DC micro grid

The rising cost of fossil fuels, their high depleting rate and issues regarding environmental pollution have brought the attention of the researchers towards renewable energy technologies. Different renewable energy resources like wind turbines, fuel cells and solar cells are connected to DC micro grid through controllable power electronic converters. In presence of these diverse generation units, robust controllers are required to ensure good power quality and to regulate grid voltage. This paper presents a sliding mode control based methodology to address the above mentioned challenges. The proposed technique keeps the switching frequency constant so that electromagnetic compatibility (EMC) issues can be solved with conventional filter design. Parallel operation of converter in DC micro gird is considered. Chattering reduction and power quality improvement by harmonic cancellation is proposed. A scaled down hardware for unregulated 11.5 V to 17.5 V input and 24V output is designed and tested. The experimental results show good performance of the controller under different loads and uncertain input voltage conditions. Moreover, the results show the robustness of the closed loop system to sudden variations in load conditions. Furthermore, a significant improvement in power quality is achieved by harmonic cancellation of chattering in the output of the converters.     

Exploration of Advanced Electrode Materials for Approaching High‐Performance Nickel‐Based Superbatteries

The surging interest in high performance, low‐cost, and safe energy storage devices has spurred tremendous research efforts in the development of advanced electrode active materials. Herein, the in situ growth of zinc–iron layered double hydroxide (Zn–Fe LDH) on graphene aerogel (GA) substrates through a facile, one‐pot hydrothermal method is reported. The strong interaction and efficient electronic coupling between LDH and graphene substantially improve interfacial charge transport properties of the resulting nanocomposite and provide more available redox active sites for faradaic reactions. An LDH–GA||Ni(OH)₂ device is also fabricated that results in greatly enhanced specific capacity (187 mAh g^?1 at 0.1 A g^?1), outstanding specific energy (147 Wh kg^?1), excellent specific power (16.7 kW kg^?1), along with 88% capacity retention after >10 000 cycles. This approach is further extended to Ni–MH and Ni–Cd batteries to demonstrate the feasibility of compositing with graphene for boosting the energy storage performance of other well‐known Ni‐based batteries. In contrast to conventional Ni‐based batteries, the nearly flat voltage plateau followed by a sloping potential profile of the integrated supercapacitor–battery enables it to be discharged down to 0 V without being damaged. These findings provide new prospects for the design of high‐performance and affordable superbatteries based on earth‐abundant elements.     

Preparation of Au nanoparticles by Q switched laser ablation and their application in 4-nitrophenol reduction

Clean Technologies and Environmental Policy - This work reports the fabrication of Au nanoparticles (NPs) by laser ablation of a gold metal plate immersed in water in the absence of stabilizing...