Three-dimensional,gas phase fuel cell with a laccase biocathode

A fuel cell using an enzymatic biocathode operating in a gas phase mode is reported. The electrode was prepared using a three-dimensional conductive electrode matrix. An enzyme solution containing laccase and a mediator was distributed into a hydrophilic matrix of carbon felt fibers creating a porous gas-flowing electrode. A Pt-based gas diffusion electrode served as the anode. A maximum power density of 9.4 W m⁻² (2.9 kW m⁻³) was obtained with 15 U of enzyme cm⁻², with hydrogen as the fuel. Power density was found to be a function of the enzyme loading, air flow rate, volume of the liquid phase and the humidity of the air stream. The ability to use methanol and ethanol as vapors in gas phase was also shown. The introduction of three-dimensionality into the electrode architecture and operation of the fuel cell in a gas phase mode to supply the fuel and the oxidant demonstrates an avenue for improving the power density of EFCs.     

Performance of diesel engine with biodiesel at varying compression ratio and ignition timing

The performance of Ricardo E6 engine using biodiesel obtained from mahua oil (B100) and its blend with high speed diesel (HSD) at varying compression ratio (CR), injection timing (IT) and engine loading (L) has been presented in this paper. The brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT) increased, whereas brake thermal efficiency (BTE) decreased with increase in the proportion of biodiesel in the blends at all compression ratios (18:1-20:1) and injection timings (35-45° before TDC) tested. However, a reverse trend for these parameters was observed with increase in the CR and advancement of IT. The BSFC of B100 and its blends with high speed diesel reduced, whereas BTE and EGT increased with the increase in L for the range of CR and IT tested. The differences of BTEs between HSD and B100 were also not statistically significant at engine settings of ‘CR20IT40’ and ‘CR20IT45’. Thus, even B100 could be used on the Ricardo engine at these settings without affecting the performance obtained using HSD.     

Development of surface engineered mesoporous alumina nanoparticles: drug release aspects and cytotoxicity assessment

The present investigation deals with successful synthesis and surface functionalisation of mesoporous alumina (MeAl) nanoparticles by simplified sol–gel method using cetyl trimethyl ammonium bromide (CTAB) and pluronic as a template. Surface functionalisation of MeAl was performed to determine the selectivity of surface groups for coupling with model drug molecule. Repaglinide a BCS class II drug was loaded as a model drug on synthesised MeAl nanoparticle and studied for its sustained release capability. The synthesised and repaglinide loaded MeAl nanoparticles were characterised by Fourier transform infrared Spectroscopy, X‐ray diffraction, field emission scanning electron microscopy with EDAX, Transmission electron microscopy and differential scanning calorimetric. Results from the dissolution study confirmed the sustained release behaviour of the nanparticles which was up to 24 h. The cell viability assay demonstrated that 0.2 to 1 mg/ml concentration of MeAl was significantly less cytotoxic to the Chinese Hamster Ovary (CHO) cells. The authors’ experimental studies suggest that MeAl can be used as drug carrier and have a potential to increase the stability, loading efficiency and patient compliance for poorly water‐soluble drugs such as repaglinide.Inspec keywords: mesoporous materials, nanoparticles, nanomedicine, alumina, surface chemistry, cellular biophysics, toxicology, sol‐gel processing, Fourier transform infrared spectra, field emission electron microscopy, X‐ray chemical analysis, transmission electron microscopy, drug delivery systemsOther keywords: surface engineered mesoporous alumina nanoparticles, drug release aspects, cytotoxicity assessment, surface functionalisation, sol–gel method, cetyl trimethyl ammonium bromide, CTAB, pluronic, MeAl, model drug molecule, repaglinide, BCS class II drug, Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy, EDAX, transmission electron microscopy, differential scanning calorimetry, cell viability assay, Chinese Hamster Ovary cells, drug carrier, poorly water‐soluble drugs, Al₂ O₃      

Sustainable procurement performance of large enterprises across supply chain tiers and geographic regions

Sustainable procurement is steering today’s supply chains towards responsible business practices. This research aims to examine the trend in the sustainability performance of large enterprises for supplier selection across supply chain tiers and geographic locations. Secondary data on 83 global, large enterprises discussing sustainable procurement practices are analysed using hierarchical multiple regression analysis. Dynamic capabilities view and stakeholder theory are utilised to develop the hypotheses. The results show that sustainable procurement performance for large enterprises varies across supply chain tiers and increases in the direction of the end customer. Due to standardisation of regulations and dynamic capabilities of global, large enterprises, no significant difference is observed across geographic regions.     

Tool wear and machining performance of cBN–TiN coated carbide inserts and PCBN compact inserts in turning AISI 4340 hardened steel

PCBN is the dominant tool material for hard turning applications due to its high hardness, high wear resistance, and high thermal stability. However, the inflexibility of fabricating PCBN inserts with complex tool geometries and the prohibitive cost of PCBN inserts are some of the concerns in furthering the implementation of CBN based materials for hard turning. In this paper, we present the results of a thorough investigation of cBN plus TiN (cBN–TiN) composite-coated, commercial grade, carbide inserts (CNMA 432, WC–Co (6% Co)) for hard turning applications in an effort to address these concerns. The effect of cutting speed and feed rate on tool wear (tool life), surface roughness, and cutting forces of the cBN–TiN coated carbide inserts was experimented and analyzed using analysis of variance (ANOVA) technique, and the cutting conditions for their maximum tool life were evaluated. The tool wear, surface roughness, and cutting forces of the cBN–TiN coated and commercially available PCBN tipped inserts were compared under similar cutting conditions. Both flank wear and crater wear were observed. The flank wear is mainly due to abrasive actions of the martensite present in the hardened AISI 4340 alloy. The crater wear of the cBN–TiN coated inserts is less than that of the PCBN inserts because of the lubricity of TiN capping layer on the cBN–TiN coating. The coated CNMA 432 inserts produce a good surface finish (<1.6 μm) and yield a tool life of about 18 min per cutting edge. In addition, cost analysis based on total machining cost per part was performed for the comparison of the economic viability between the cBN–TiN coated and PCBN inserts.     

Binary quantum-inspired gravitational search algorithm-based multi-criteria scheduling for multi-processor computing systems

A quantum-inspired hybrid scheduling technique is proposed for multi-processor computing systems. The proposed algorithm is a hybridization of principles of quantum mechanics (QM) and a nature-inspired intelligence, gravitational search algorithm (GSA). The principles of QM such as quantum bit, superposition and rotation gate help to design an efficient agent representation as well as intense exploration capability of GSA enhances toward better converging rate. The fitness function is designed with the aim to minimize makespan, adequate balancing of loads and proper utilization of the deployed resources during the evaluation of agents. Several standard benchmarks as well as synthetic data sets are used to analyze and validate the work. The performance improvement of the proposed algorithm is compared with recently designed algorithms like quantum genetic algorithm, particle swarm optimization-based multi-criteria scheduling, Improved-GA, GSA and Cloudy-GSA. The significance of the algorithm is tested using a hypothesis analysis of variance.

     

Reaction mechanism for the free-edge oxidation of soot by O2

The reaction pathways for the oxidation by O₂ of polycyclic aromatic hydrocarbons present in soot particles are investigated using density functional theory at B3LYP/6-311++G(d,p) level of theory. For this, pyrene radical (4-pyrenyl) is chosen as the model molecule, as most soot models present in the literature employ the reactions involving the conversion of 4-pyrenyl to 4-phenanthryl by O₂ and OH to account for soot oxidation. Several routes for the formation of CO and CO₂ are proposed. The addition of O₂ on a radical site to form a peroxyl radical is found to be barrierless and exothermic with reaction energy of 188 kJ/mol. For the oxidation reaction to proceed further, three pathways are suggested, each of which involve the activation energies of 104, 167 and 115 kJ/mol relative to the peroxyl radical. The effect of the presence of H atom on a carbon atom neighboring the radical site on the energetics of carbon oxidation is assessed. Those intermediate species formed during oxidation with seven-membered rings or with a phenolic group are found to be highly stable. The rate constants evaluated using transition state theory in the temperature range of 300–3000 K for the reactions involved in the mechanism are provided.     

Corrosion behaviour of Mg-Cu and Mg-Mo composites in 3.5% NaCl

The corrosion behaviour of pure magnesium, Mg-Cu (0.3, 0.6, and 1 vol.%) and Mg-Mo (0.1, 0.3, and 0.6 vol.%) composites has been studied in 3.5% NaCl solution by weight loss and polarisation methods. Corrosion rates determined by weight loss method were considerably higher than that determined by polarisation method. The corrosion rate increased with increasing volume fraction of reinforcement in Mg-Cu and Mg-Mo composites. At the same volume fraction of reinforcement, molybdenum reinforced composite corroded faster than copper reinforced composite. The galvanic current density between Mg-Cu and Mg-Mo couples has been experimentally measured using zero resistance ammeter technique. The experimentally observed galvanic current densities were in close agreement with those obtained using mixed potential theory analysis. SEM observation of corroded samples confirmed microgalvanic activity at the matrix/reinforcement interfaces. The poor corrosion resistance of composites has been attributed to microgalvanic effects between the matrix and reinforcements and inferior quality of surface films.