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.     

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).     

Conductive particulate films fabricated by electrospray deposition of candle soot suspensions with acid treatment

The electrical properties of carbon-based materials have attracted significant interest due to their wide range of potential applications. This study investigated the effect of nitric acid treatment on the electrical conductivity of candle soot particle films. Electrospray deposition was used to deposit the candle soot dispersion on a solid substrate. The electrical conductivity of the films increased as the concentration of nitric acid increased, with the highest conductivity of 27.65 S cm⁻¹ observed in the film treated with 5 M nitric acid. The increase in conductivity was attributed to the enhancement of interparticle bonding between soot particles after acid treatment. Functional groups such as carboxylic or nitro groups were observed in the films by Fourier transform infrared (FTIR) spectroscopy. Raman spectroscopy showed a broadening of the D bands, suggesting a defect in the crystalline structure due to the formation of functional groups on the soot structure. These results suggest that nitric acid treatment can be used to improve the electrical conductivity of candle soot particle films.     

Fuzzy expert system for troubleshooting of the deodorizer unit in a palm oil refining plant

In this paper, a troubleshooting technique is developed to provide a sequence of necessary actions during deodorizer unit failure in a palm oil refinery. This paper introduces a fuzzy expert system that incorporates the knowledge of experienced plant workers in dealing with the complex problems of the palm oil deodorizer. The presented methodology uses both qualitative and quantitative data. Qualitative data are collected from several interview sessions with the technical staff in a palm oil refinery. Quantitative data are gathered from various sources, such as control and monitoring systems. The qualitative data are analyzed to discover the possible pattern of faults in the deodorizer failure. This tool can diagnose possible faults and provide a sequence of necessary actions when deodorizer failure occurs. The obtained results show the developed deodorizer troubleshooting tool is useful to guide plant workers/operators in diagnosing the possible faults and abnormalities during the troubleshooting process, as well as to provide field training for inexperienced staff.     

A Metaheuristic Technique for Cluster-Based Feature Selection of DNA Methylation Data for Cancer

Epigenetics is the study of phenotypic variations that do not alter DNA sequences. Cancer epigenetics has grown rapidly over the past few years as epigenetic alterations exist in all human cancers. One of these alterations is DNA methylation; an epigenetic process that regulates gene expression and often occurs at tumor suppressor gene loci in cancer. Therefore, studying this methylation process may shed light on different gene functions that cannot otherwise be interpreted using the changes that occur in DNA sequences. Currently, microarray technologies; such as Illumina Infinium BeadChip assays; are used to study DNA methylation at an extremely large number of varying loci. At each DNA methylation site, a beta value (β) is used to reflect the methylation intensity. Therefore, clustering this data from various types of cancers may lead to the discovery of large partitions that can help objectively classify different types of cancers as well as identify the relevant loci without user bias. This study proposed a Nested Big Data Clustering Genetic Algorithm (NBDC-GA); a novel evolutionary metaheuristic technique that can perform cluster-based feature selection based on the DNA methylation sites. The efficacy of the NBDC-GA was tested using real-world data sets retrieved from The Cancer Genome Atlas (TCGA); a cancer genomics program created by the National Cancer Institute (NCI) and the National Human Genome Research Institute. The performance of the NBDC-GA was then compared with that of a recently developed metaheuristic Immuno-Genetic Algorithm (IGA) that was tested using the same data sets. The NBDC-GA outperformed the IGA in terms of convergence performance. Furthermore, the NBDC-GA produced a more robust clustering configuration while simultaneously decreasing the dimensionality of features to a maximum of 67% and of 94.5% for individual cancer type and collective cancer, respectively. The proposed NBDC-GA was also able to identify two chromosomes with highly contrasting DNA methylations activities that were previously linked to cancer.     

Palladium-cerium-hydrogen solid solutions—I. Thermodynamic properties

Solubility isobars in the temperature range 625–1250 K have been measured at an H₂-pressure of 1.01 × 10⁵Nm⁻² for solutions of H in Pd-Ce matrixes containing up to 12at.% Ce. The partial enthalpies of the H-atoms at any temperature exhibit minima as a function of Ce-concentration. The ternary solid solutions have been analyzed by a cell model in which the cells (interstitial sites) encompass two coordination shells of lattice atoms. This model is shown to be consistent with the enthalpy behavior measured, i.e. with the generation of trapping sites by the inclusion of Ce-atoms into the Pd-lattice.     

Enhanced photooxidative desulphurization of dibenzothiophene over fibrous silica tantalum: Influence of metal-disturbance electronic band structure

Fibrous silica tantalum (FSTa) and a series of metal oxides (silver oxide (AgO), copper oxide (CuO) and zinc oxide (ZnO)) supported on FSTa were prepared by hydrothermal and electrochemical method, respectively. X-ray diffraction, nitrogen adsorption-desorption analyses, Fourier-transform infrared, ultraviolet–visible diffuse reflectance spectroscopy, and photoluminescence were used to characterize the catalysts. The catalyst activity towards on photocatalytic oxidative desulfurization (PODS) of 100 mg L^?1 dibenzothiophene (DBT) was ranked in the following order: FSTa (3.03 × 10^?3 mM min^?1) > Zn/FSTa (2.65 × 10^?3 mM min^?1) > Cu/FSTa (2.33 × 10^?3 mM min^?1) > Ag/FSTa (1.46 × 10^?3 mM min^?1) under visible light irradiation for 150 min. This result demonstrated that the addition of metal oxides lowered the efficiency of PODS of DBT, most probably due to the unfit energy level of the photocatalyst towards redox potentials of superoxide anion radical (?O₂^?) and hydroxyl radical (?OH). Nevertheless, among the metal oxides loaded FSTa, Zn/FSTa showed a higher desulfurization rate, which likely due to its higher valence band energy (E_VB = 3.12 eV) than the redox potential of the H₂O/?OH (+2.4 eV vs. NHE), which allowed the production of ·OH for oxidation of DBT into dibenzothiophene sulfone (DBTO₂). In parallel, the hole at the VB of ZnO can also directly oxidize DBT to DBTO_2, as confirmed by the scavenger experiment. A kinetics study using Langmuir–Hinshelwood model illustrated that the photodegradation over Zn/FSTa followed the pseudo-first-order, and adsorption was the rate-limiting step. These findings are believed to aid in the rational design of high-performance photocatalysts for various photocatalytic applications, especially the removal of sulphur-containing compounds from fuel oils.     

Effect of hydrogen flow rate on the synthesis of carbon nanofiber using microwave-assisted chemical vapour deposition with ferrocene as a catalyst

Carbon nanostructure materials are becoming of considerable commercial importance, with interest growing rapidly over the decade since the discovery of carbon nanofibers. In this study, a new novel method is introduced to synthesize the carbon nanofibers by gas-phase, where a single-stage microwave-assisted chemical vapour deposition approach is used with ferrocene as a catalyst and acetylene and hydrogen as precursor gases. Hydrogen flow rate plays a significant role in the formation of carbon nanofibers, as being the carrier and reactant gas in the floating catalyst method. The effect of process parameters such as microwave power, radiation time and gas ratio of C₂H₂/H₂ was investigated statistically. The carbon nanofibers were characterized using scanning and transmission electron microscopy and thermogravimetric analysis. The analysis revealed that the optimized conditions for carbon nanofibers production were microwave power (1000 W), radiation time (35 min) and acetylene/hydrogen ratio (0.8). The field emission scanning electron microscope and transmission electron microscope analyses revealed that the vertical alignment of carbon nanofibers has tens of microns long with a uniform diameter ranging from 115 to 131 nm. High purity of 93% and a high yield of 12 g of CNFs were obtained. These outcomes indicate that identifying the optimal values for process parameters is important for synthesizing high quality and high CNF yield.     

Experimental analysis of photovoltaic thermal system assisted with nanofluids for efficient electrical performance and hydrogen production through electrolysis

In this study the influence of the nanofluid in the photovoltaic thermal system (PVT) has been examined experimentally. The nanoparticles zinc oxide (ZnO) dispersed in the base fluid water at the concentration of 0.25 %wt. A series of experimental tests were conducted between 9:00 A.M. to 16:00 P.M. ZnO nanofluids passed through the PVT panel at various mass flow rates. To increase the thermal efficiency and performance of the PVT, instead of using plain water, nanofluids were introduced. The parameters such as output power, surface temperature, fluid outlet temperature, thermal efficiency, and electrical efficiency were examined at the different mass flow rates such as 0.008 kg/s, 0.010 kg/s, and 0.012 kg/s. Added to above, the proposed photovoltaic thermal system was also assisted in producing hydrogen by electrolysis process. Polymer electrolyte membrane (PEM) has been used to generate the hydrogen via electrolysis. With the use of nanofluids, the electrical efficiency and thermal efficiency were increased owing to the reduction in the cell temperature. Introduction of the nanofluids at the optimal mass flow rate helps the panel to produce higher electrical output. The hydrogen yield rate was also increased by the use of nanofluids. Among the different mass flow rate, 0.012 kg/s reported maximum thermal efficiency of 33.4% with the hydrogen production rate of 17.4 ml/min. Based on the extensive observed results procured, photovoltaic thermal systems can be a promising candidate for the production of hydrogen using PEM electrolyzer.