Fossil fuel substitutes are being developed to combat the ecological impact and rapid exhaustion of petroleum-based products. Being the most abundant polymer on Earth, cellulose-based products are ...renewable and sustainable. Cellulose nanocrystals (CNCs) are derived from cellulosic-based materials, have good physicochemical properties, and can be used to produce numerous products. CNC synthesis and their applications have been extensively studied; however, they remain limited to laboratory-scale as several challenges hinder its commercial-scale production. Herein, the suitability of nanocrystalline isolation methods, including chemical, enzymatic, ionic liquids, and deep eutectic solvents, for mass production is evaluated. Poor re-dispersion of CNCs is a major challenge that hinders its utilization in many applications. Hence, surface chemistry modification of CNCs have also been reviewed. It has been concluded that the CNC isolation method and surface modification technique significantly impacts its cost, morphology, and physicochemical properties. This review paper presents the challenges often faced in the conversion of bench-scale studies into commercial production of nanocrystalline cellulose. Hence, this paper gives all the necessary information on the important aspects of raw material selection, nanocellulose isolation process selection, and suitable surface modification method together in a single review article. Readers will be able to identify the possible research gaps for future research studies.
Particulate Matter (PM) emissions from gasoline direct injection (GDI) engines, particularly Particle Number (PN) emissions, have been studied intensively in both academia and industry because of the ...adverse effects of ultrafine PM emissions on human health and other environmental concerns. GDI engines are known to emit a higher number of PN emissions (on an engine-out basis) than Port Fuel Injection (PFI) engines, due to the reduced mixture homogeneity in GDI engines. Euro 6 emission standards have been introduced in Europe (and similarly in China) to limit PN emissions from GDI engines. This article summarises the current state of research in GDI PN emissions (engine-out) including a discussion of PN formation, and the characteristics of PN emissions from GDI engines. The effect of key GDI engine operating parameters is analysed, including air-fuel ratio, ignition and injection timing, injection pressure, and EGR; in addition the effect of fuel composition on particulate emissions is explored, including the effect of oxygenate components such as ethanol.
IN713LC is a Ni-based superalloy with extensive uses in the aerospace industry. However, fabricating IN713LC components using additive manufacturing technologies such as laser powder bed fusion ...(LPBF) is extremely challenging due to its high composition of alloying elements (e.g., Al and Ti), which increase its susceptibility to cracking. Accordingly, the present study conducts an experimental investigation into the LPBF processing parameters (i.e., laser power and scanning speed) which enable the fabrication of LPBF IN713LC parts with a high relative density and minimal cracking. The effects of heat treatment on the microstructure and mechanical properties of the as-built parts are then examined. The results show that IN713LC is prone to the two micro-cracking mechanisms, namely solidification cracking due to the formation of low-melting-point elements at the grain boundaries and ductility dip cracking (DDC) as a result of grain boundary sliding. However, given an appropriate selection of the LPBF processing conditions, as-built IN713LC components with an average yield strength of 800 MPa, an ultimate tensile strength of 998 MPa, and ultimate elongation of 12.5% at room temperature are better than those of as-cast IN713LC specimens. Notably, the solid solution heat treatment process yields a significant improvement in the yield strength compared to that of the as-built sample. Moreover, all the mechanical properties of the sample processed by solid solution heat treatment are comparable to those of the as-cast IN713LC sample.
•A non weldable alloy IN713LC is successfully printed using the LPBF process with low power laser.•With appropriate selection of the LPBF processing conditions,mechanical properties of IN713LC are superior than casting.•Effect of heat treatment on mechanical properties and microstructure is observed.•The results show IN713-LC have two micro-cracking mechanisms, namely solidification cracking and ductility dip cracking.
In recent years, industrial wireless sensor networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, ...process control, feedback systems, and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment, and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper, a detailed discussion on design objectives, challenges, and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines, and possible hazards in industrial atmosphere are discussed. This paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. This paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs.
The mechanical properties of selective laser melting (SLM) components are fundamentally dependent on their microstructure. Accordingly, the present study proposes an integrated simulation framework ...consisting of a three-dimensional (3D) finite element model and a cellular automaton model for predicting the epitaxial grain growth mode in the single-track SLM processing of IN718. The laser beam scattering effect, melt surface evolution, powder volume shrinkage, bulk heterogeneous nucleation, epitaxial growth, and initial microstructure of the substrate are considered. The simulation results show that during single-track SLM processing, coarse epitaxial grains are formed at the melt–substrate interface, while fine grains grow at the melt–powder interface with a density determined by the intensity of the heat input. During the solidification stage, the epitaxial grains and bulk nucleated grains grow toward the top surface of the melt pool along the temperature gradient vectors. The rate of the epitaxial grain growth varies as a function of the orientation and size of the partially melted grains at the melt–substrate boundary, the melt pool size, and the temperature gradient. This is observed that by increasing heat input from 250 J/m to 500 J/m, the average grain size increases by ~20%. In addition, the average grain size reduces by 17% when the initial substrate grain size decreases by 50%. In general, the results show that the microstructure of the processed IN718 alloy can be controlled by adjusting the heat input, preheating conditions, and initial substrate grain size.
An integrated simulation framework consisting of the 3D finite element method and 3D cellular automaton method is presented for simulating the multi-track and multi-layer selective laser melting ...(SLM) process. The framework takes account of all the major multi-physics phenomena in the SLM process, including the initial grain structure, the growth kinetics, the laser scanning strategy, the laser-powder and laser-matter interactions, the melt flow, and the powder-to-liquid-to-solid transformations. The feasibility of the proposed framework is demonstrated by simulating the evolution of the epitaxy grain structure of Inconel 718 (IN718) during a 15-layer SLM process performed using a bi-directional 67° rotation scanning strategy and various SLM process parameters. The simulation results are found to be in good agreement with the experimental observations obtained in the present study and in the literature. In particular, a strong (001) texture is observed in the final component, which indicates that the grains with a preferred orientation win the competitive epitaxy grain growth process. In addition, the size and shape of the IN718 grains are governed primarily by the cooling rate, where the cooling rate is determined in turn by the SLM parameters and the build height. Overall, the results show that the proposed framework provides an accurate approach for predicting the final microstructures of SLM components, and therefore, it can play an important role in optimizing the SLM processing parameters in such a way as to produce components with the desired mechanical properties.
Date palm and cashew shell wastes are abundant byproducts of the agriculture industry in the UAE, but they are often underutilized and not adequately managed, resulting in environmental problems. For ...the first time, co-pyrolysis of these wastes was studied to investigate their physicochemical properties, synergistic interaction, thermal degradation behavior, and estimate kinetic and thermodynamic parameters using thermogravimetric analysis with non-isothermal heating rates from 20 to 800 °C and a heating rate of 10 °C/min. The Coats and Redfern method, utilizing twenty-one solid-state reaction mechanisms, was used to perform analyses. The three diffusion models showed the best linear regression with the experimental thermogravimetric data. Co-pyrolysis of cashew shells with date seeds significantly lowered the activation energy (Ea) and produced stable biochar, providing an opportunity to obtain pyrolysis products at better energy efficiency. The estimated Ea for 100% date seeds, 100% cashew shells, and their blend (50:50) were 109, 124, and 113 kJ/mol, respectively. The thermodynamic parameters (ΔH, ΔG, and ΔS) indicated that the pyrolysis process was endothermic but not spontaneous. The novelty of this work lies in investigating the potential of utilizing two underutilized wastes together to produce pyrolysis products. This study is essential for advancing co-pyrolysis of date seeds and cashew shell wastes, optimizing product yields, and understanding their pyrolysis behavior towards experimental pyrolysis.
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Thermally conducting and highly compliant composites were developed by dispersing graphite nanoplatelets (GNPs) into a silicone matrix by mechanical mixing. X-ray diffraction (XRD) indicates that the ...average thickness of the GNPs decreased from 60 to 35
nm during mechanical mixing. XRD-texture analysis demonstrated that GNP/silicone composites at 8
wt.% GNPs have a higher degree of basal plane alignment than at 20
wt.%. Differential scanning calorimetry showed that GNPs raised the curing temperature of silicone with no significant effect on the glass transition temperature. The thermal conductivity of the 20
wt.% composites reached 1.909
W/m.K, an 11-fold increase over silicone suggesting an improved dispersion compared to similar composites prepared by dual asymmetric centrifuge mixing. The percolation threshold for electrical conductivity of the composites was at ∼15
wt.%. The compressive modulus of the composite increased to twice that of silicone at 20
wt.%. The corresponding strength decreased by a factor of two compared to silicone and this can be attributed to the weak bonding at the GNP-silicone interface. Overall, these GNP/silicone composites, with a high thermal conductivity, low electrical conductivity and compliant nature are promising materials for use as thermal pads for thick gap filling thermal interface applications.
A key player in driving cellular immunity, IFN-γ is capable of orchestrating numerous protective functions to heighten immune responses in infections and cancers. It can exhibit its immunomodulatory ...effects by enhancing antigen processing and presentation, increasing leukocyte trafficking, inducing an anti-viral state, boosting the anti-microbial functions and affecting cellular proliferation and apoptosis. A complex interplay between immune cell activity and IFN-γ through coordinated integration of signals from other pathways involving cytokines and Pattern Recognition Receptors (PRRs) such as Interleukin (IL)-4, TNF-α, Lipopolysaccharide (LPS), Type-I Interferons (IFNS) etc. leads to initiation of a cascade of pro-inflammatory responses. Microarray data has unraveled numerous genes whose transcriptional regulation is influenced by IFN-γ. Consequently, IFN-γ stimulated cells display altered expression of many such target genes which mediate its downstream effector functions. The importance of IFN-γ is further reinforced by the fact that mice possessing disruptions in the IFN-γ gene or its receptor develop extreme susceptibility to infectious diseases and rapidly succumb to them. In this review, we attempt to elucidate the biological functions and physiological importance of this versatile cytokine. The functional implications of its biological activity in several infectious diseases and autoimmune pathologies are also discussed. As a counter strategy, many virulent pathogenic species have devised ways to thwart IFN-γ endowed immune-protection. Thus, IFN-γ mediated host-pathogen interactions are critical for our understanding of disease mechanisms and these aspects also manifest enormous therapeutic importance for the annulment of various infections and autoimmune conditions.
A good knowledge of the reaction kinetics of n-butylcyclohexane, a widely used surrogate component for jet fuels and diesel, is crucial for understanding the combustion chemistry of practical fuels. ...This paper proposes a detailed kinetic model consisting of 1802 species and 7246 reactions to describe from low to high temperature chemistry of n-butylcyclohexane. The autoignition and oxidation of this fuel were investigated over a wide range of conditions. Ignition delay times were measured at 10, 15 and 20 bar for equivalence ratios of 1 and 1.5 under highly diluted conditions in a heated rapid compression machine. Oxidation experiments were performed in a flow reactor for equivalence ratios of 1 and 1.5 over the temperature range of 650–1075 K at 1 atm. Several oxidation products were identified and their mole fraction profiles were measured as a function of temperature. The model was evaluated with respect to the new experimental data. Additionally, the model was compared to experimental data in the literature, including ignition delay times in both rapid compression machine and shock tube, speciation profiles in jet-stirred reactor. Good agreement was achieved with all the data. Reaction flux analyses and sensitivity analyses were performed in order to provide insight into the combustion kinetics of n-butylcyclohexane. The present model can be used to construct the kinetic models for surrogates of jet fuels or diesel, as well as to work as the starting mechanism for the development of kinetic models of larger alkylcyclohexane and bicyclic cyclohexane fuels.
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