Catalytic mechanism of TiO2 quantum dots on the de/re-hydrogenation characteristics of magnesium hydride

In the present study, the catalyst anatase titanium dioxide (TiO₂) quantum dots (QDs) of size ∼ (2.50–4.00)nm was successfully synthesized by the hydrothermal method. The formation of TiO₂: QDs has been established by UV–Vis spectroscopy and confirmed by transmission electron microscopy. Here, we report the catalytic action of TiO₂:QDs on de/re-hydrogenation properties of magnesium hydride (MgH₂/Mg). By catalyzing MgH₂ through this catalyst, the onset desorption temperature of MgH₂ gets reduced significantly from ∼360 °C (for ball-milled MgH₂) to ∼260 °C. Moreover, the Mg-TiO₂: QDs sample absorbed a significant amount of hydrogen up to ∼6.10 wt% in just 77sec at 280 °C. Improved rehydrogenation kinetics has been found even at lower temperatures by absorbing ∼5.30 wt% in 74 s at 225 °C and ∼5.0 wt% of hydrogen in 30 min at 100 °C. Based on structural,.microstructural, and XPS investigations, a feasible mechanism for improved hydrogen sorption and cyclic stability in MgH₂ catalyzed with TiO₂:QDs has been explained and discussed. To our knowledge, no studies have been carried out on the sorption of hydrogen in MgH₂ catalyzed by TiO₂:QDs.     

Recent progress on MXenes and MOFs hybrids: Structure,synthetic strategies and catalytic water splitting

The 2D MXenes (carbides, nitrides, carbonitrides) is an emerging class of atomic layered nanomaterials that calls for intensive investigation. The tunable structures, large-surface to volume ratio, high electrical conductivity, rich surface chemistries, hydrophilicity and large redox active sites are some vital features which makes MXenes the suitable catalyst for water splitting. However, MXenes suffers from the key limitation of agglomeration, reduced long term stability and recyclability. The coupling of MXenes with metal organic frameworks (MOFs) is an effective strategy owing to the high surface area, porosity, diverse functionalities, pore-confinement effect, and tunable coordination space of MOFs provides a preferential environment for hosting MXene to prevent its agglomeration. The review aims to showcase the synergistic effects of MXenes and MOFs hybrids by exploiting the inherent features of both frameworks for water splitting application. Herein, the electronic, structural and optical properties of MXenes and MOFs frameworks are elaborated. A detailed discussion on the synthetic strategies of MXenes and MOFs hybrids explains the importance of etching technique. Lastly, variant future challenges have been highlighted to better understand the present research and progression of MXenes and MOFs hybrids.     

Highly efficient catalytic derived synthesis process of carbon aerogel for hydrogen storage application

For the present work, resorcinol-formaldehyde (R–F) aerogels were synthesized through both acid (nitric acid) and base (sodium carbonate) catalyzed sol-gel process followed by supercritical drying (SCD) as well as ambient pressure drying (APD). RF aerogels were carbonized at high temperatures to form carbon aerogels. The effect of the catalyst type and drying methods on the final characteristics were studied in detail. Microstructural and textural characteristics were evaluated through XRD, SEM, BET, RAMAN, FTIR, and TEM techniques. It was found that the combination of base catalysis and SCD delivered a higher micropore density and more uniform pore distribution. The CAs prepared under such conditions displayed a hydrogen uptake of 0.80 wt% at room temperature and 2.85 wt% at liquid nitrogen temperature (77 K).     

Superior-catalytic performance of Ni–Co layered double hydroxide nanosheets for the reduction of p-nitrophenol

Ni–Co layered double-hydroxides (LDHs), with their lamellar morphology, and higher number of active sites, ensure efficient charge transfer. This makes them extremely useful for catalytic applications. The reported bimetallic LDH can acts as an efficient catalyst for hydrogenation of p-nitrophenol, a toxic and carcinogenic pollutant commonly found in industrial wastewater. In addition to showing the high performance of the catalyst, its facile synthesis protocol is also established. The catalytic performance at higher temperatures is also discussed in details. The obtained results are further extended to explore the advantage of Ni–Co LDH as an electrocatalyst for hydrogen evolution reaction (HER). Thus, these materials are shown to have large-scale industrial use.     

Enhanced bio-methane and bio-hydrogen production using banana plant waste and sewage sludge through anaerobic co-digestion

The yield of bio-methane and bio-hydrogen was enhanced by co-digesting banana plant waste (BPW) and sewage sludge (SS). In stage 1, acclimatisation of the inoculum SS is performed in a continuous stirred tank reactor (CSTR), and its various parameters are analyzed daily. In stage 2, six different BPW to SS ratios is optimized and incubated in manual methane potential test setup (MMPTS) for 40 days. The highest bio-methane and bio-hydrogen yields were observed from R4 (60% BPW and 40% SS). In stage 3, the best-achieved ratio of BPW and SS are then treated with different doses of NaOH as an alkaline pre-treatment. The highest bio-methane was achieved from dose 2 (0.75 mol NaOH) as 620.8 NmL/day. The study shows that the co-digestion of the BWP with SS has promising potential for enhanced bio-methane and bio-hydrogen production.     

Developing a UX KPI based on the user experience questionnaire

Decisions in Companies are made typically by using a number of entirely different key figures. A user experience key figure is one of many important key figures that represents one aspect of the success of the company or its products. What we aim in this article is to present to those responsible for a product a method of how a user experience key performance indicator (UX KPI) can be developed using a UX questionnaire. We have developed a UX KPI for use in organizations based on the User Experience Questionnaire (UEQ). To achieve this, we added six questions to the UEQ to measure the importance of the UEQ scales. Based on the UEQ scales and the scores given for importance, we then developed a User Experience Questionnaire KPI (UEQ KPI). In a first study with 882 participants, we calculated and discussed the UEQ KPI using Amazon and Skype. The results show that the six supplementary questions could be answered independently of the UEQ itself. In our opinion, the extension can be implemented without any problems. The resulting UEQ KPI can be used for communication within an organization as a key performance indicator.     

An educational tool for enhanced mobile e-Learning for technical higher education using mobile devices for augmented reality

In all dimensions of education and all subjects, Smartphones have turned out to be broadly acknowledged technology. It plays an essential task in advanced online education systems. Because of smart devices' effortlessness and extension property, it is getting to be mandatory for portable applications. This paper analyses the research on Smart Devices (SD) to incorporate visual simulation into e-learning. The researchers created an Augmented Reality (AR) platform for e-learners to expand the coursebook with graphics and virtual multimedia applications. This paper recommends a Mobile e-Learning (MeL) application termed “MeL app". The advanced MeL app methods have been tested using Mann-Whitney ‘U' Test in the lecture hall using real-time learners. The proposed MeL app planned to create the learning practice easier, focusing on e-learner's requirements by encouraging e-learners and instructor relationships to maintain communicative development-based e-learning for Technical Higher Education (THE). Software engineering learners assess this proposed framework in THE. Future work in this investigation incorporates new highlights, testing the device in extreme situations, evaluating the instructive perspectives utilizing more significant and increasingly various understudy and beginner inhabitants, and at last, extending the application space.     

Development of coded-cooperation based multi-relay system for cognitive radio using mathematical modeling and its performance analysis

Coded cooperation is a cooperative relaying technique which is bandwidth efficient and can provide better connectivity when used with cognitive radio. Earlier cognitive radio is implemented with cooperative schemes like decode and forward, amplify and forward, compress and forward, etc., which gives moderate spectrum efficiency and diversity with reduced fading problem of wireless communication. But these techniques are not bandwidth efficient so need huge bandwidth for transmission. In this paper, we have developed a mathematical model of new coded-cooperation based multi-relay system for cognitive radio and its outage probability is analytically derived for underlay mode. The performance analysis of proposed system is carried out in terms of interference temperature constraint, channel gain, number of relays through outage probability for single and multilink relays at the primary node for Rayleigh channel. The proposed system shows that the cognitive radio with coded cooperation outperforms the already existing techniques in terms of diversity, bandwidth, spectrum utilization efficiency and improve the communication quality. In addition, the theoretical analysis of the outage probability is validated by asymptotic analysis.     

Privacy preserving security using biometrics in cloud computing

Cloud computing and the efficient storage provide new paradigms and approaches designed at efficiently utilization of resources through computation and many alternatives to guarantee the privacy preservation of individual user. It also ensures the integrity of stored cloud data, and processing of stored data in the various data centers. However, to provide better protection and management of sensitive information (data) are big challenge to maintain the confidentiality and integrity of data in the cloud computation. Thus, there is an urgent need for storing and processing the data in the cloud environment without any information leakage. The sensitive data require the storing and processing mechanism and techniques to assurance the privacy preservation of individual user, to maintain the data integrity, and preserve confidentiality. Face recognition has recently achieved advancements in the unobtrusive recognition of individuals to maintain the privacy-preservation in the cloud computing. This paper emphasizes on cloud security and privacy issues and provides the solution using biometric face recognition. We propose a biometrics face recognition approach for security and privacy preservation of cloud users during their access to cloud resources. The proposed approach has three steps: (1) acquisition of face images (2) preprocessing and extraction of facial feature (3) recognition of individual using encrypted biometric feature. The experimental results establish that our proposed recognition approach can ensure the privacy and security of biometrics data.

     

Two stage image de-noising by SVD on large scale heterogeneous anisotropic diffused image data

Multimedia Tools and Applications - De-noising of images along with the edge enhancement has always been a challenging task in large scale heterogeneous image data. This paper presents a two stage...