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The six chapters that follow this one are case studies. Each investigates an articulation of sustainable development using the five-step method developed in Chapters 3 and 4 Chapter 3 Chapter 4. The topics are • Biopolymers to replace oil-based plastics • Wind farms as a source of renewable energy • Electric cars as the future for clean personal transport • Lighting – incandescent, fluorescent, LED • Solar PV for low-carbon power • Bamboo as a sustainable building material They are designed for project-based teaching. Each ends with suggestions for related projects.

Despite wide applications of noble metal-based catalysts in 5-hydroxymethylfurfural (HMF) oxidation, promoting the catalytic performance at low loading amounts still remains a significant challenge. Herein, a series of metal oxide modified MOx-Au/TiO2 (M = Fe, Co, Ni) catalysts with low Au loading amount of 0.5 wt% were synthesized. Addition of transition metal oxides promotes electron transfer and generation of the Auδ−–Ov–Ti3+ interface. A combination study reveals that the dual-active site (Auδ−-Ov-Ti3+) governs the catalytic performance of the rate-determining step, namely hydroxyl group oxidation. Auδ− site facilitates chemisorption and activation of O2 molecules. At the same time, Ov-Ti3+ site acts as the role of “killing two birds with one stone”: enhancing adsorption of both reactants, accelerating the activation and dissociation of H2O, and facilitating activation of the adsorbed O2. Besides, superoxide radicals instead of base is the active oxygen species during the rate-determining step. On this basis, a FDCA yield of 71.2% was achieved under base-free conditions, complying with the “green chemistry” principle. This work provides a new strategy for the transition metal oxides modification of Au-based catalysts, which would be constructive for the rational design of other heterogeneous catalysts.

Soils containing organic matter exhibit low shear strength and high compressibility. Lime stabilisation has been shown to improve the engineering properties of clayey soils. An attempt was made to study the effect of organic matter (starch and peat) on the shear strength of lime-stabilised clayey soils subjected to longer curing periods (up to 180 days). Most studies have reported the strength behaviour of lime-stabilised organic soils up to 60 days. Vane shear tests were carried out on artificially prepared organic soil mixtures treated with 6% lime after different curing periods (0, 7, 30, 60, 90 and 180 days). The results indicate that the improving effect of lime is deteriorated in the presence of organic matter as the curing period increases. It was observed that, for lime-stabilised clayey soils containing organic matter, the strength seemed to increase up to 30 days, after which it ceased. The strength reduction in lime-stabilised clayey soils containing organic matter depended on the pH and functional groups present in the soil. Fourier transform infrared spectroscopy of cured samples was also carried out to examine the microstructural changes responsible for the strength change in lime-stabilised clayey soils.

Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys. However, it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity. Herein, a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium, which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating. The multiscale microstructures with nanoscale stacks and microscale spheres on the surface, as well as the through-thickness stearates, lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.

New-type magnesium alloy with prominent solubility and mechanical property lays foundation for preparing fracturing part in petroleum extraction. Herein, Mg-xZn-Zr-SiC alloy is prepared with casting strategy. Electrochemical and compression tests are conducted to assess the feasibility as decomposable material. Morphology, composition, phase and distribution are characterized to investigate decomposition mechanism. Results indicate that floccule, substrate component and reticulate secondary phase are formed on as-prepared surface. Sample also acts out enhanced compression strength to maintain pressure and guarantee stability in dissolution process. Furthermore, as decomposition time and zinc content increase, couple corrosion intensifies, resulting in gradually enhanced decomposition rate. Rapid sample decomposition is mainly due to basal anode dissolution, micro particle exfoliation and poor decomposition resistance of corroding product. Such work shows profound significance in preparing new-type accessible alloy to ensure rapid dissolution of fracturing part and guarantee stable compression strength in oil-gas reservoir exploitation.

Gypsum is regarded as an environmentally friendly binding material and is widely used to enhance the engineering properties of soft fine-grained soils. However, the time-dependent strength and deformation characteristics of fine-grained soils stabilised with gypsum have not yet been thoroughly investigated and rational evaluation of these characteristics will assist in the formulation of cost-effective and reliable design approaches. In this study, the time-dependent mechanical behaviours of gypsum-mixed fine-grained soil (GMFS) specimens were investigated under unconfined monotonic loading conditions, considering ageing periods of 3–90 days and five different loading rates (LR = 0.0005–1.0%/min). The results revealed that the unconfined compressive strength and stiffness of the GMFS specimens initially decreased with ageing and finally became stable after 14 days and 28 days of ageing for water/gypsum ratios of 1.30 and 1.60, respectively. Furthermore, the strength and stiffness of the GMFS specimens increased with an increase in LR.

Direct conversion of syngas to aromatics (STA) over oxide-zeolite composite catalysts is promising as an alternative method for aromatics production. However, the structural effect of the oxide component in composite catalysts is still ambiguous. Herein, we investigate the size effect by selecting ZnCr2O4 spinel, as a probe oxide, mixing with H-ZSM-5 zeolite as a composite catalyst for STA reaction. The CO conversion, aromatics selectivity and space-time yield (STY) of aromatics are all significantly improved with the crystal size of ZnCr2O4 oxide decreases, which can mainly attribute to the higher oxygen vacancy concentration and thus the rapid generation of more C1 oxygenated intermediate species. Based on the understanding of the size–performance relationship, ZnCr2O4-400 with a smaller size mixing with H-ZSM-5 can achieve 32.6% CO conversion with 76% aromatics selectivity. The STY of aromatics reaches as high as 4.79 mmol gcat−1 h−1, which outperforms the previously reported some typical catalysts. This study elucidates the importance of regulating the size of oxide to design more efficient oxide-zeolite composite catalysts for conversion of syngas to value-added chemicals.

Aluminum (Al) powder is widely used in solid propellants. In particular, nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al. However, the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder, which greatly limits its application. Hence, this paper used iron, a component of solid propellant, to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder. SEM, TEM, EDS, XRD, XPS, and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes. The results show that Fe was uniformly coated on the surface of Al powder. There was no reaction between Fe and Al, and Fe/Al composite fuels had a larger specific surface area than pure Al, which could better improve the reactivity of pure Al. Besides, the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored. The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder. Especially, the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder. Hence, Fe/Al composite fuels are expected to be widely used in solid propellants.

Mg alloys are considered the most promising engineering materials because of their unique properties. However, the uncontrolled corrosion rate of these alloys limits their applications. Therefore, in this study, a micro-arc oxidation layer was used as a transition layer to “directly” grow a zinc-based metal-organic framework (MOF) composite coating on the surface of a Mg alloy (AZ91D). Herein, the two zeolitic imidazolate framework (ZIF-8) coatings with different morphologies were separately prepared by homologous metal oxide induction and a one-step in-situ growth method. The superhydrophobic composite coating showed strong hydrophobicity and self-cleaning properties, which could prevent the penetration of water and corrosive ions (Cl−) into the surface of AZ91D. Electrochemical tests demonstrated that the super-hydrophobic composite coatings greatly enhanced the corrosion resistance of AZ91D, and the corrosion current density decreased from 10−5 to 10−9 A/cm2. These results indicate that the ZIF-8 coatings are beneficial for improving the hydrophobicity and enhancing the corrosion resistance of Mg alloys. Therefore, MOF composite coatings provide a new strategy that can be used to prepare multifunctional anticorrosion coatings on metal substrates.

The local deformation behavior and dynamic recrystallization of a shock compressed Mg-1 Zn alloy was investigated through EBSD and TEM. Since dislocation slipping and twinning were locally suppressed during high strain-rate deformation, a more flexible kinking deformation was activated to adjusted local orientation and facilitate slipping and twinning within the kinks. Meanwhile, due to the slow heat dissipation that resulted in a local temperature elevating, the kink bands were evolved into deformation bands with recrystallized nano-grains. Such a finding provides a new perspective for kinking-facilitated nanocrystallization in Mg alloys and other anisotropic metallic materials.

In-situ incorporation of layered double hydroxides (LDH) nanocontainers into plasma electrolytic oxidation (PEO) coatings on AZ91 Mg alloy has been achieved in the present study. Fumarate was selected as Mg corrosion inhibitor for exchange and intercalation into the nanocontainers, which were subsequently incorporated into the coating. It was found that the thickness and compactness of the coatings were increased in the presence of LDH nanocontainers. The corrosion protection performance of the blank PEO, LDH containing PEO and inhibitor loaded coatings was evaluated by means of polarization test and electrochemical impedance spectroscopy (EIS). The degradation process and corrosion resistance of PEO coating were found to be greatly affected by the loaded inhibitor and nanocontainers by means of ion-exchange when corrosion occurs, leading to enhanced and stable corrosion resistance of the substrate.

Due to its superior self-assembly properties and vast functionalization pos-sibilities DNA has long been one of the most promising candidates forfabrication of nanoscale electrical components using molecular buildingblocks. There exist already many demonstrations on optical devices based onorganizing metallic nanoparticles (NP) via DNA self-assembly, but despite thepromises only few DNA based electrical devices or studies have been realizedso far. Here we study the gold NP conjugated and metallized DNA TX-tile-structure, which we recently showed to exhibit the room temperature Coulombblockade, the pre-requisition for a single electron transistor. The properties ofthe obtained Coulomb blockade are further characterized via the differentialconductance measurements at temperatures ranging from 4.2 K to 10.2 K.The results show sharp blockade plateaus with varying threshold voltages,which yields further evidence of a gating effect by background charges. Thisstrongly indicates that the DNA-NP assembly functions as a single electrontransistor. Also, the additional growth of gold NPs and electrodes via chemicalgold deposition process, needed to achieve the Coulomb blockade, is studiedhere in more details, yielding more insight to the process, and thus helping torealize better control of it.

Statement of problem: Changing the internal design of a metal framework may decrease the manufacturing time, the weight of the restoration, and the amount of alloy powder used, as well as simplify the fabrication process. Purpose: The purpose of this in vitro study was to evaluate the effect of framework internal design changes on the mechanical properties of cobalt-chromium (Co-Cr) specimens manufactured by using direct metal laser sintering (DMLS). Material and methods: Dumbbell-shaped test specimens were designed as per the International Organization for Standardization (ISO) 22674(E) standard by using a 3-dimensional software program. A total of 70 dumbbell-shaped specimens were prepared by using Co-Cr alloy powder and DMLS (n=10). The control group specimens were solid with the internal completely filled. For the test groups, the internal design of the dumbbell-shaped specimens was modified. Leaving the outer shell thickness of the specimens at 0.5 mm for all test groups, 6 different internal designs were created, and the specimens were weighed. The tensile strength test was used to evaluate the mean peak strength, elastic modulus, and percentage elongation of the specimens. One-way ANOVA followed by the Dunnett T3 test was used for statistical analysis (α=.05). Results: A statistically significant difference was found among the groups in terms of bar weight and peak strength (P.05). Conclusions: Decreasing the weight of the frameworks by changing the internal design of the specimens also decreased the peak strength. However, it did not affect the elastic modulus or the percentage of elongation.

The chip study can be the simile to the biopsy in the machining process, as it exposes physical phenomena that are generated in the machining process (heat transfer, hardening, phase changes, heat treatments, etc.). These physical phenomena are directly influenced by the cutting parameters applied to the process (feed, cutting speed, and depth). A chip analysis procedure is proposed to estimate some of the physical phenomena generated in the micro-end-milling in a conventional CNC machine on 7075 aluminium and Ti-6Al-4 V titanium alloys. The procedure is composed of hardness tests, metallography, scanning electron microscopy (SEM), and infrared thermography. A softened chip is observed in the Ti-6Al-4 V titanium a hardened one in 7075 aluminium alloy. The chip approach evaluation evidences a great variation regarded to thermal characteristics between micro-machining and meso-machining focused on the scale of the removed layer thickness.

This study analyses the effectiveness of the biopolymer xanthan gum (XG) to improve the mechanical properties of silty sand. The study focuses on the effects of the curing time and the content of XG on the unconfined and confined behaviour of soil treated with this biopolymer. The study was carried out with specimens cured under high-humidity conditions, through the comparison of the unconfined compressive strength (UCS), stiffness, compressibility and vertical yield stress of non-stabilised and biostabilised specimens, obtained from UCS and oedometer tests. Additionally, the pH value and results of scanning electron microscopy (SEM)/ energy-dispersive X-ray analysis (EDX) tests are presented and discussed. The biostabilisation of this soil with XG induces a more ductile stress–strain behaviour, a moderate increase in UCS and stiffness, and in the increase of the one-dimensional compressibility, with a greater effect for higher XG contents. The SEM/EDX tests show that the biopolymer induces a random biopolymer network in the biostabilised specimens that is related to the strengthening obtained.

Selective hydrogenation of phenol to cyclohexanone is intriguing in chemical industry. Though a few catalysts with promising performances have been developed in recent years, the basic principle for catalyst design is still missing owing to the unclear catalytic mechanism. This work tries to unravel the mechanism of phenol hydrogenation and the reasons causing the selectivity discrepancy on noble metal catalysts under mild conditions. Results show that different reaction pathways always firstly converge to the formation of cyclohexanone under mild conditions. The selectivity discrepancy mainly depends on the activity for cyclohexanone sequential hydrogenation, in which two factors are found to be responsible, i.e. the hydrogenation energy barrier and the competitive chemisorption between phenol and cyclohexanone, if the specific co-catalyzing effect of H2O on Ru is not considered. Based on the above results, a quantitative descriptor, Eb(one/pl)/Ea, in which Ea can be further correlated to the d band center of the noble metal catalyst, is proposed by the first time to roughly evaluate and predict the selectivity to cyclohexanone for catalyst screening.

Environmentally friendly materials are being explored as alternatives to lime and cement binders in ground improvement. Biological treatment methods are environmentally friendly as they rely on the natural activity of ubiquitous microbes to produce extracellular polymeric saccharides (EPS) and calcite cements. EPS extruded by microbes exhibit strong adhesion from growth of fibrous bridges and bonds between surfaces. In situ polysaccharide secretion in soils to improve their engineering properties has not been examined. In this study, pulverised dried cattle manure (CM) are is used for in situ EPS production in a synthetic soft soil specimen. The indigenous facultative anaerobes and aerobes in animal waste produce negatively charged EPS molecules in the soil specimen. Bridging of sand particles and embedment of CM fibres in kaolinite aggregates caused an immediate increase in unconfined compressive strength (UCS) of the stabilised specimen. EPS cementation improved soil strength by filling pores and engulfing kaolinite aggregates into bonded mass. Fibre reinforcement and bio-stabilisation by CM increased the UCS of the soil by 740%. Replacing C-intensive lime/cement binders by CM as a stabilising agent has the potential to prevent release of 1 t of carbon dioxide to the atmosphere per tonne of lime/cement consumed.

RE-containing magnesium alloys were prepared via molten-salt-mediated magnesiothermic reduction by using RE2O3 (RE=Y, Nd and Gd) and Mg metal as raw materials. The thermomechanical analysis of the magnesiothermic reduction reactions in molten salt was investigated. Then the molten-salt-mediated magnesiothermic reduction process was studied from three different perspectives. After that, the RE-containing magnesium alloy was characterized by using chemical analysis, XRD analysis and SEM analysis. The magnesiothermic reduction was a liquid-liquid reaction with relatively weak driving force. During the melting process and the magnesiothermic reduction process, magnesium metal and the obtained alloy went up and down as a whole in molten salt, which improved the process safety without introducing chloride inclusions. Meanwhile, the hydrolysis of the RECl3-containing molten salt occurred at elevated temperature, which severely impeded the magnesiothermic reduction process. After the magnesiothermic reduction at 750 °C for 2.0 h, the content of RE and the common impurity elements in the obtained RE-containing alloy met the both requirements of the commercial WE43A and WE43B.

The inconsistencies regarding the fundamental correlation between Gd content and slip (twinning) activities of Mg alloys appeal further investigations. However, the traditional slip dislocations analysis by TEM is time-consuming, and that by SEM/EBSD cannot recognize the partial slip modes. These urge a more efficient and comprehensive approach to easily distinguish all potential slip modes occurred concurrently in alloy matrix. Here we report a modified lattice rotation analysis that can distinguish all slip systems and provide statistical results for slip activities in Mg alloy matrix. Using this method, the high ductility of Mg-Gd alloy ascribed to the enhanced non-basal slips, cross-slip, and postponed twinning activities by Gd addition is quantitatively clarified.

The compatibility problems become main concern in the utilization of biodiesel especially regarding to degradation and corrosion. The present study is conducted to describe the corrosion behaviour that occurs in steel tanks after contact with palm-based biodiesel for a period of 7 months. The storage tank used is respectively made of galvanised steel (GS), carbon steel (CS) and stainless steel (SS). It is performed in vertical cylinders with a floating-roof model. In every 30 days of storage time, the profile changes in the wall, roof and base surface of each tank were observed. The oil fuel properties were monitored in the parameter of viscosity, acid numbers, water content and oil colour. The topographic profiles on the surface of the walls and bottom of each tank wetted by biodiesel were examined over three zones inside the tanks using an endoscope imager. The main results of this study indicate that the tank steel with different protective layers exhibits different types of corrosion. The corrosion was localized in SS tanks but generalized in GS and CS tanks. The oil contamination in SS tanks was relatively lower than that in CS and GS tanks. The type of corrosion performed differently in different zones on the inside of the tank. The potential for leaks is greater at the base than on the walls and roof of the storage tank.

This paper introduces an algorithmic approach to the analysis of bifurcation of limit cycles from the centers of nonlinear continuous differential systems via the averaging method. We develop three algorithms to implement the averaging method. The first algorithm allows one to transform the considered differential systems to the normal form of averaging. Here, we restricted the unperturbed term of the normal form of averaging to be identically zero. The second algorithm is used to derive the computational formulae of the averaged functions at any order. The third algorithm is based on the first two algorithms and determines the exact expressions of the averaged functions for the considered differential systems. The proposed approach is implemented in Maple and its effectiveness is shown by several examples. Moreover, we report some incorrect results in published papers on the averaging method.

Ultrasonic treatment has great contributions on modifying the morphology, dimension and distribution of constituent phases during solidification, which serve as dominate factors influencing the hydrogen storage performance of Mg-based alloys. In this research, ultrasonic treatment is utilized as a novel method to enhance the de-/hydriding properties of Mg-2Ni (at.%) alloy. Due to ultrasonic treatment, the microstructure of as-cast alloy is significantly refined and homogenized. Ascribing to the increased eutectic boundaries and shortened distance inside α-Mg for hydrogen atoms diffusion, the hydrogen uptake capacities and isothermal de-/hydriding rates improve effectively, especially at lower temperature. The peak desorption temperature reduces from 392.99 °C to 345.56 °C, and the dehydriding activation energy decreases from 101.93 kJ mol−1 to 88.65 kJ mol−1. Weakened hysteresis of plateau pressures and slightly optimized thermodynamics are determined from the pressure-composition isotherms. Owing to the refined primary Mg, a larger amount of hydrogen with the higher hydriding proportion is absorbed in the first stage when hydrides nucleate in eutectic region and grow on primary Mg periphery subsequently before MgH2 colonies impinging, resulting in the enhancement of hydrogenation rates and capacities.

To overcome the limitation in formability at room temperature, manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements. The rare-earth magnesium alloys behave differently from the conventional alloys, especially with respect to their coupled anisotropic and strain rate sensitive behavior. In the current work, such behavior of the rare-earth Mg alloy ZEK100 sheet at room temperature is investigated with the aid of the elastic viscoplastic self-consistent polycrystal plasticity model. Different strain rate sensitivities (SRSs) for various deformation modes are employed by the model to simulate the strain rate sensitive behaviors under different loading directions and loading rates. Good agreement between the experiments and simulations reveals the importance and necessity of using different SRSs for each deformation mode in hexagonal close-packed metals. Furthermore, the relative activities of each deformation mode and the texture evolution during different loadings are discussed. The anisotropic and strain rate sensitive behavior is ascribed to the various operating deformation modes with different SRSs during loading along different directions.

The initial micro-galvanic corrosion behavior of Mg‒30wt%Ca alloy only containing Mg2Ca and α-Mg was studied by immersion testing in a 0.9% NaCl solution at 37oC. The quasi-in situ SEM and TEM results show that Mg2Ca corroded easier than α-Mg, indicating that Mg2Ca acted as an anode. The work function (Φ) for Mg2Ca calculated by first-principles is significantly lower compared to that for α-Mg. The Volta potential measured by a scanning Kelvin probe force microscope reveals that the Mg2Ca had a relatively low Volta potential (ψ) value. The lower Φ and ψ values for Mg2Ca indicate a lower electrochemical nobility, which is consistent with the experimental phenomenon.

In this research, a novel Ni-Co-metallic glass composite was fabricated and the effect of the co-deposition of Ni60Cr10Ta10P16B4 amorphous metallic glass powder (MGP) on the morphology and electrocatalytic properties of Ni–Co coatings was evaluated. The process was initiated by producing Ni60Cr10Ta10P16B4 via mechanical alloying of elemental powders using a planetary ball mill. Then, Ni–Co nanocomposite coatings were deposited on a copper substrate by the addition of different amounts of MGP via the electrodeposition method in a Watts bath. Then, the microstructure and chemical composition of the deposits were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) successively. The electrocatalytic performance of the coatings was evaluated in a methanol-containing alkaline (1 M NaOH) solution through cyclic voltammetry (CV). The enhancement of the electrocatalytic activity of Ni–Co coating through the co-deposition of MGP was observed. It was also concluded that the electrocatalytic properties of composite coatings are optimized when 7.5 g L−1 of MGP is added to the electroplating bath. Moreover, MGP was demonstrated to have altered the microstructure and the content of Co besides enhancing the roughness and specific surface of coatings.

The effects of addition of minor amount of (0.5 wt.%) antimony (Sb) or gadolinium (Gd) and combined addition of Sb and Gd (0.5 wt.%, respectively) on the hot tearing susceptibility (HTS) of Mg-5Al-3Ca alloy were investigated experimentally using a “T-shaped” hot tearing measuring system. Various solidification parameters of the alloys were measured and calculated through thermal analysis experiments. The microstructure, grain size, and morphology of the crack zone were characterized by scanning electron microscopy and electron backscatter diffraction, and the crystal phases of the alloys were analyzed by X-ray diffraction and energy-dispersive X-ray spectroscopy. The results showed that the addition of 0.5 wt.% Gd resulted in the increase in the vulnerable temperature range (Tv) and reduced the eutectic structure content that could participate in feeding, thereby improving the HTS of the alloy. However, addition of 0.5 wt.% Sb or combined addition of Gd and Sb (0.5 wt.%, respectively) to the Mg-5Al-3Ca alloy shortened the Tv and improved the skeleton strength of the alloy, thereby reducing HTS. Moreover, significantly refined structure of Mg-5Al-3Ca-0.5Gd-0.5Sb alloy improved the feeding ability of the eutectic structure, thus the alloy exhibited the lowest HTS.

Cold metal transfer arc additive manufacturing technique was used to produce 5356 aluminum alloy by adding refining agents to solve the problems of coarse grains and poor performance. Metallic powd...

The effects of pre-existing {10–12} extension twins on the precipitation behavior of an extruded AZ80 material during aging and on its mechanical properties after peak aging are investigated. The material containing {10–12} twins—which are formed by compression before aging (twinned material)—has a finer grain size and higher dislocation density than the extruded material. Although the peak hardnesses of the twinned and extruded materials are almost the same, the time to reach the peak hardness is considerably shorter in the former material than in the latter (4 h and 24 h, respectively). In the twinned material, the high dislocation density of the {10–12} twins promotes continuous precipitation, which results in the formation of numerous fine Mg17Al12 precipitates within the twins in the early stage of aging. The formation of these continuous precipitates reduces the driving force for discontinuous precipitation, which consequently suppresses the formation and growth of coarse Mg17Al12 precipitates at the grain boundaries. Despite its shorter peak-aging time, the 4 h-peak-aged twinned material shows higher tensile strength and elongation than the 24 h-peak-aged extruded material. These higher mechanical properties of the former material are attributed primarily to the presence of more abundant fine continuous precipitates, which are effective in strengthening the material, and less abundant coarse discontinuous precipitates, which can act as crack initiation sites. These results demonstrate that the introduction of {10–12} twins into wrought Mg–Al-based alloys can accelerate the Mg17Al12 precipitation kinetics considerably and improve the strength and ductility of the peak-aged alloys simultaneously.

Mg-1.0Al-1.0Ca-0.4Mn (AXM1104, wt.%) low alloy was extruded at 200 °C with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized (DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength (TYS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure (EL) was increased from 5.0% to 17.6%. The TYS, ultimate tensile strength (UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively, exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TYS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed.

Superplasticiser (SP) is widely used in foam concrete industry to improve rheological properties since compaction and vibration adversely affect the stability of foam bubbles. This study aims to investigate the effect of polycarboxylate SP contents on the properties of foam concrete. Different water-cement ratios (w/c) were used, and the SP added to the mixture to adjust the spreadability. The density of 1500 kg/m3 was chosen for the production of foam concrete for semi-structural applications. Fresh, mechanical, transport and microstructure properties were analysed in this study. The results of this study showed that the content of w/c and SP had a significant impact on the performance of the foam concrete. Increasing the SP content enhanced the foam concrete’s mechanical and transport properties, but the best behaviour was through the use of 1.35% of SP. Smaller pore diameter, better pore distribution and higher portlandite peak intensity were achieved through the use of the SP. Overall, the superior behaviour of the foam concrete was achieved by the use of 1.35% polycarboxylate SP.

This paper describes a statistical and mathematical approach to optimize the mechanical properties of a wood plastic composite with Polyethylene Terephthalate (PET) as polymeric matrix. Wood plastic composite are materials that consist of a primary continuous polymer phase, where a secondary filler dispersed phase is embedded, the filler generally is wood fibers or sawdust. The slack variable approach in mixture experiments, consist in selecting a component of the mixture as slack variable, to subsequently design and analyze the experiment in terms of the remaining components. With the experimental design information three slack variable model were fit. Using response surface graphs, we show how different compositions modify the mechanical properties of wood plastic composite. Besides, by the desirability function, the optimal formulation of the compound that simultaneously maximizing the mechanical properties of wood plastic composite, was obtained. Finally, the components proportions that provides the best tensile, flexural and compression strength are presented.

Recently, functional molecules such as Polydopamine (PDA), Hyaluronic Acid (HA) and heparin have been widely studied in the field of surface modification of magnesium (Mg) alloy stents for better degradation behavior and biocompatibility, but their further application is limited by undesirable anticoagulant function, uncontrollable degradation and easy bleeding, respectively. Regarding to this consideration, a magnesium Fluoride/Polydopamine/Sulphonated hyaluronic acid (MgF2/PDA/S-HA) composite coating was successfully prepared by applying S-HA with sulfur content of 9.71 wt% on the surface of ZE21B alloy in this study. The results showed that the composite coating with a unique mesh structure not only inherited the anticoagulant effect of sulfonic acid group and the excellent cyto-compatibility of S-HA with high sulfur content, but also significantly improved the corrosion performance of ZE21B alloy. These results indicate a great application potential of the composite coating in the field of cardiovascular biomaterials.

Fragments and blast waves generated by explosions pose a serious threat to protective structures. Experiments have shown that the single ballistic resistance or blast resistance of the steel plate improves significantly after coating polyurea. However, the dynamic response and structural design for the polyurea-coated structure under the combined fragments and blast loading are still lacking. In this paper, the impact resistance of polyurea-coated steel plate under complex dynamic loading is analyzed and designed for improving comprehensive ballistic and blast resistance using the newly established computational evaluating model. Firstly, according to the thickness and placement effects of the coating on the ballistic and blast resistance, the steel-core sandwich plates are designed, which are proved to own outstanding comprehensive ballistic and blast resistance. Besides, the distribution diagram of ballistic and blast resistance for different polyurea-coated steel plates is given to guide the design of protective structures applying in different explosion scenarios. Furthermore, the dynamic response of designed plates under two scenarios with combined fragments and blast loading is studied. The results show that the synergistic effect of the combined loading is significant. It reduces both the ballistic and blast resistance of the polyurea-coated steel plate and causes a more severe failure than the sum of the failures induced by the individual fragments and blast impact. Besides, the acting sequence of the fragments and blast affects the structural protective performance heavily. It is found that the first loading inducing structural large deformation or damage generally is dominant. In the scenario of fragments penetrating firstly, the excellent unit-thickness ballistic performance of the structural front part is strongly needed for improving the comprehensive ballistic and blast resistance. The analysis of dynamic response and structural design for the polyurea-coated steel plate in this paper will be helpful for designing lightweight protection structures with excellent comprehensive ballistic and blast resistance.

The unconventional machining processes are popular in machining the difficult to cut type complex contour/ profile. The key parameters are to be machined with care as they directly affects the function and non key dimensions are machined with other than consideration of functional aspect, like design, passage. That means accuracy is less important in those dimensions but finish is to be good. So the machining of engineering materials does not always require optimizing parameters based on multiple responses. This investigation focuses on the sensitiveness of Wire EDM of 12X18H10T - Stainless Steel and identifying the parameters contribution and establish mathematical model to predict values without trial. An austenitic alloy 12X18H10T - Stainless Steel exhibits its inherent mechanical properties even when it expose to extremely high temperature. Ithas potential application in aerospace engine components manufacturing. This investigation utilized the Taguchi L9 experiential Design with factors of Pulse off Time, Wire Tension, Pulse on Time, and Wire Feed Rate. This study aims to examine Maximize the rate of machining with Taguchi approach in the process of Wire EDM of 12X18H10T - Stainless Steel and establish a mathematical model to predict the highly influencing parameter(s) for desired rate of machining.

Adsorption dynamics of ethane in two granular fixed beds and structured fixed beds with microfibrous composites was studied. 5A zeolite membrane 5A/PSSF (paper-like sintered stainless steel fiber) and microfibrous entrapped activated carbon composites were prepared by wet layup papermaking/sintering technique and in-situ hydrothermal method. Microfibrous composites were characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption/desorption. Structured fixed beds were designed by filling granular adsorbents (5A zeolite or activated carbon) and microfibrous composites at the inlet and outlet of the beds, respectively. Effects of flow rate, bed height and structure on the breakthrough curves were investigated. The length of unused bed (LUB) was determined, and Yoon–Nelson model was used to fit the breakthrough curves. The experimental results showed ethane was effectively adsorbed on the granular adsorbents and microfibrous composites. Both composites could decrease the LUB values and enhance bed utilization. All breakthrough curves fitted well to Yoon–Nelson model, with correlation coefficient exceeding 0.89. The adsorption rate of ethane could be improved in the structured fixed beds, which showed an enhanced mass transfer efficiency for ethane adsorption. LUB values of structured fixed beds with 5A/PSSF composites were larger, the bed utilization values were lower, and the adsorption rate constants were higher than those with MEAC composites under the same conditions.

Chitosan (CS) is a natural and biopolymer that are suitable biomedical properties such as; biocompatibility, non-toxicity, biodegradability and bioactive polymer that’s reason with a very large application (fabrication of biomedical scaffolds, implants). Some of the biocompatible thermoplastic polymers (PLA, PEEK, PLGA, PE, PP, PMMA, PET and etc.) are most widely used in biomedical field as per their properties from last two decades. Poly-vinyl chloride (PVC) thermoplastic polymer are most widely used in medical field but there are some limitations of their uses. For enhancement of PVC thermoplastic polymers properties sometimes add some bioactive and biocompatible fillers or other bioactive thermoplastic polymers. In this review paper try to link and discussed about the possible reinforcement CS in PVC thermoplastic polymer for biomedical applications.

Nowadays, renewable source materials play a significant part in creating lightweight structural materials. In this work, Azadirachta indica (Neem Gum) was taken as natural filler material in epoxy matrix with different volume fraction. The hand lay-up method was used. The mechanical properties such as tensile, flexural and impact tests were found for five different specimens. The effect of natural filler on the mechanical properties was observed and found that 40% addition of neem powder produces better mechanical strength in tensile, flexural and impact strength.

Surface water bodies are getting contaminated day by day. Pollutants like 2-Chloropyridine (a class of halogenated pyridine derivative which are widely used in pharmaceutical and agrochemical sector) is detected in surface water bodies. It is toxic and carcinogenic. One of the reason of its presence in water bodies can be attributed to effluents from sewage treatment and industrial waste treatment plants, which may be due to inefficient conventional treatment technologies. Use of Advanced Oxidation technologies like Fenton’s oxidation has proven to be a promising alternative to degrade these recalcitrant and non-biodegradable compounds. The Present study accesses the applicability of laterite soil as a source of iron catalyst in Fenton’s oxidation process to degrade2-chloropyridine (2-CP) at various concentrations. Parameters like pH, dosage of laterite iron, hydrogen peroxide are optimized. Effect of initial concentration of the target compound on degradation kinetics is also investigated. Up to 75% degradation was achieved in a total reaction time period of 10hrs corresponding to Laterite iron: H2O2 ratio of 1:50 at a pH of 3 for a sample containing 2-CP compound at 10 mg/L. Use of iron in Fenton’s oxidation process harnessed from the laterite soil can be a suitable alternative to treat polluted water bodies contaminated with pharmaceutical halopyridine compounds.

In the current research wear behaviour of nano B4C particles with Al2214 alloy composites were studied. Al2214 alloy with 2 to 6 varying weight percentages of nano B4C particles composites were developed using stir cast route. Further, these developed composites were evaluated for the microstructural studies using SEM and EDS. The wear behaviour of Al2214 alloy and Al2214 with 2, 4 and 6 wt% of nano B4C composites were analysed using pin-on-disc wear apparatus. The dry wear tests were conducted at various loads and sliding speeds with 2500 m sliding distance as a constant parameter. The microstructural explanations revealed the thorough circulation of nano particles in the Al2214 alloy matrix, further the boron carbide particles were confirmed in the composites in the form of boron and carbon components. The Al2214 alloy with nano B4C composites displayed the greater wear resistance properties. The applied load and speed were impacted the wear of as cast alloy and its composites. Various wear mechanisms were identified by using SEM images of wear surfaces.

Organic fertilizers have been used since the dawn of mankind to improve soil fertility and promote crop growth. However, the process of preparing organic fertilizers for use in agricultural activities is a labour-intensive and time-consuming procedure. Thus, in order to reduce labour costs and improve the efficiency of organic fertilizer preparation, automated organic fertilizer mixers were developed. For this research work, an improved organic fertilizer mixer based on the Internet of Things (IoT) technology capable of monitoring the status of fertilizer production remotely and providing updates and alerts to workers was developed. The aim of this work was to further reduce labour workload and costs, thus increasing efficiency of the organic fertilizer mixing process. In order to accommodate the IoT monitoring system, several modifications and design changes were carried out on the prototype of an automated organic fertilizer mixer. Tests conducted on the prototype unit showed that it performs as required. The IoT monitoring system successfully captures and uploads information on the weight of agricultural waste mixture in the storage drum to the IoT platform. This information can then be used to alert workers on when to add more agricultural waste material to the mixture or remove the processed organic fertilizer. Furthermore, an overall operational cost comparison of different organic fertilizer production methods showed that the automated organic fertilizer prototype provides operational cost savings of over 5 times when compared to current automated systems. Future work includes further automation to the agricultural waste filling and organic fertilizer removal process.

Nowadays, environmental sustainability is the responsible of engineering community for which the usage of waste or recycling is essential towards ecological sustainability, for which green materials are considered widely in all sectors. Because of the significance of characteristic filler supported composites in the advancement of lightweight materials, this research exploration centers around utilizing biodegradable garbage such as used tea dust powder reduces the impact of environmental pollution. In this study, effect of organic residue, tea dust is effectively recycled/utilized for fabricating polymer composite to find its suitability in engineering applications. Epoxy polymer is considered as matrix material and different volume fractions of used tea dust powders (10, 20, 30, 40, 50, and 60 vol%) are used as reinforcement. Hand-layup approach is adopted for fabricating the polymer composite and the samples are tested for their mechanical properties viz., impact, flexural and tensile strength. Based on the mechanical strength the best combination is found to be 40% vol. in epoxy matrix; higher addition than 40% reduces the strength due to lower bonding between the powders and matrix.

In this technical world, the properties and internal structure of materials renders a vital part in building up of the components for various specific purposes and improvise their efficiencies in a better way. The combination of copper with other metals is always an interesting one. In this, brass of grade BS90 is an alloy of zinc added with copper and it is lustrous in nature. The amount of zinc that is mixed with copper can be varied to develop different categories of brass with different melting temperatures that develops distinct electrical and mechanical potency. In the process of better understanding of the powder metallurgy technique and analyzing and improvising the properties of brass, this research is carried out. Primarily, this process is carried out based on the powder metallurgy technique. The prime intention of this investigation is to develop and process the specimens under predetermined conditions of powder metallurgy and then their mechanical hardness and the microstructure are to be characterized. The secondary objective is to analyze these characteristic values and compare them relatively to the specified conditions.

Carbon Nanotube Aluminum metal grid composites are viewed as most encouraging composite materials nearby Aerospace, Automotive, Naval and other assembling applications. The momentum research work is made to comprehend the impact of carbon nanotube (CNT) inclusion on the Hardness and Wear trademark conduct of Al6061-CNT combination. The CNT particles of 500 nm size is executed as the fortifications in the Al6061 compound medium. Nano composites amalgamated by powder metallurgy strategy arranged by 1, 1.5 and 2 wt% in the Al6061 amalgam medium. Examples were considered for microstructural portrayal utilizing filtering electron magnifying lens (SEM) and energy dispersive spectroscope (EDS). Wear and Hardness strength were evaluated according to ASTM norms. Checking electron miniature pictures found the unvarying spreading of CNT in Al6061 amalgam. Further, Wear and Hardness strength of the establishment medium Al6061 compound is improved with the gathering of CNT.

The expansive soil has serious impact due to its unstable volumetric behaviour when it undergoes seasonal variations. In order to utilise the problematic expansive soil for any kind of work it needs to alter the behaviour of soil by stabilisation using addition of admixtures. From the economical point of view using industrial waste materials is the cost-effective technique. In this work the selection of industrial waste materials which comes from tile manufacturing such as Tile Waste Powder (TWP) and Foundry Sand (FS) outcome of metal casting industries as an admixture. The Tiles Waste Powder has the nature to improve the compaction behaviour of expansive soil because of its high lime content and Foundry sand are used to develop the strength behaviour of problematic soil due to the presence rich silica content. In this paper, untreated soil got treated using the different proportions such as 5,10, 15,20 and 25% of Tile waste powder and their corresponding the compaction and strength characteristics of the soil sample were determined under different curing periods. Also the tests have been conducted for optimum percentage of tile waste mixed along with varying percentage of Foundry Sand (4, 6, 8, 10 and 12%) in soil sample. The results was obtained from the standard proctor test, UCC and CBR test and it further analysis shows that the increasing the proportion of TWP rises the peak strength of the treated soil up to 20% for the maximum 28 days curing. Also, from the result analysis for the combination of FS and TWP by optimum percentage of Tiles Waste Powder (20%) with 12% of Foundry sand shows the increment in the strength characteristics of soil. The TWP and Foundry Sand can be effectively used in stabilization works in order to utilise the waste by effective minimization of disposal problems.

In the current exploration an impact of 44 µm estimated B4C support expansion on the mechanical conduct of Al2618 combination has been contemplated. The Al2618 compound metal composites with 2, 4, 6 and 8 changing weight rates of B4C were created by stircast strategy. The orchestrated 44 µm estimated B4C particles built up Al2618 combination composites were exposed to microstructural considers, mechanical properties testing. Microstructural portrayals of acquired examples were completed by SEM microscopy and EDS spectrums. The B4C particles were uniformly disseminated and existences of these particles were affirmed by the EDS patterns. The hardness and tensile qualities of metal composites have been upgraded with the expansion of B4C support. There was decline in the ductility of the Al2618 compound after the joining of the support. Different crack and failure systems were seen in the Al2618-B4C composites utilizing SEM.

For a graph G and a set Z of four distinct vertices of G, a diamond on Z is a subgraph of G such that, for some labeling Z = { v 1 , v 2 , v 3 , v 4 } , there are three internally disjoint paths P 1 , P 2 , P 3 with end vertices v 1 , v 2 with v 3 , v 4 on P 1 , P 2 , respectively. Therefore, this yields a K 4 − -subdivision with branch vertices on Z. We characterize graphs G that contain no diamond on a prescribed set Z of four vertices, under the assumption that for every v ∈ Z there are three paths of G from v to Z − { v } , mutually disjoint except for v. Moreover, we can find two “different” such subdivisions, if one exists. Our proof is based on Mader's S-paths theorem.

Due to demands of high strength and light-weight materials such as Al 6063 aluminum alloy in industrial and aerospace application, it is necessary to choose machining operations by which the materials should be less affected. The present work shows how effectively the responses (HAZ, MRR and circularity) of fiber laser engraving (which is a non-traditional machining operation) varied with the input process parameters (power, scan speed, frequency and fill spacing). On the basis of Taguchi’s L16 orthogonal matrix and S/N ratio analysis, the optimum input parameter combinations were found out for each response individually. Finally, the improvement S/N ratio for closeness coefficient index (CCi) of the above responses was determined to be 3.83 dB by using TOPSIS.

Can tax regimes shape the incentives of governments to engage in armed conflict? India’s Maoist belt contains a large share of the country’s most valuable mineral deposits. Indian mining royalties benefit the States, but they are set by the central government. States are largely responsible for counter-insurgency operations within their territory. Therefore, the royalty regime could shape the incentive of states to support counter-insurgency efforts. This paper exploits the introduction of a 10% ad valorem tax on iron ore that was responsible for a 10-fold increase in royalty collections by the affected State governments. In a panel of district-level violence outcomes between 2007 and 2013, we find that the royalty hike was followed by a significant intensification of violence in districts with iron ore deposits compared to other areas. We also show that the higher royalty rates are followed by an increase in illegal mining activity, suggesting that the control of mineral resources underpins the observed intensification in violence.

The study is aimed to utilize the silica fume coated plastic waste in the concrete in place of uncoated plastic waste. The main aim of the study is to evaluate the effect on fresh and mechanical properties of concrete after coating the plastic waste with mineral admixture i.e silica fume. The study of utilization of different kinds of plastics forms in concrete has been carried out earlier as well. The major concern is the bonding between concrete mix and the plastic by which the strength could not be attained as desired as per the grade. The present investigation is an endeavor to enhance the bonding characteristics of waste PET fibers with concrete mix by coating them with mineral admixture such as silica fumes by utilizing epoxy resins as an adhesive. The examination was done by utilizing waste PET fibers in aspect ratio AR 25 (50 mm נ2 mm), AR 50 (100 mm נ2 mm) and AR 75(150 mm/2 mm) and consolidate them as bond weight in separate interims of 3%, 6%, 9% and 12%. The modern and mechanical qualities of concrete mix investigated with incorporation of silica fume coated waste PET fibers and ordinary waste PET fibers were contemplated.

The population explosion and exponential increase in energy demand of the world have created enormous stress on finite fossil fuels and posed a threat to the environment. The sustainable Bio-Electrochemical Systems which include Microbial Fuel Cells (MFC), Microbial Electrolysis Cells (MEC) etc. can generate energy from waste. The present study has intended to utilize Sewage sludge (SS), Compost leachate (CL), and Mess Food waste (FW) as an organic substrate in an Integrated Bio-Electrochemical system to evaluate the bioelectricity generation potential in dual-chambered H type MFCs, then utilization of digestate from MFCs for Bio-hydrogen production in MECs. The maximum open-circuit voltages of 595 mV, 505 mV, and 690 mV were recorded in SS, CL, and FW fed MFC respectively, and their corresponding peak power densities of 1.8 ± 0.1 W/m2, 1.3 ± 0.1 W/m2 and 2.4 ± 0.1 W/m2 respectively were generated. The COD removal of 62.37%, 66.8%, and 50.19% were achieved for MFC fed with SS, CL, and FW respectively. The digestate fed MECs had further shown COD removal of 55.26%, 64.40% and 46.61% of the digestate in the "MFC turned MEC" system. The corresponding volumes of gas produced per gram of COD removal were reported as 23.8, 18.1 and 55.1 for SS, CL and FW respectively. The overall COD removal by bio-electrochemical system (BES) of 83.25%, 88.23 % and 73.41% for SS, CL and FW were achieved. The higher OCV of 690 mV and 55.1 mL of bio-hydrogen per gram of the COD removed has suggested the suitability of the FW for Integrated Biochemical system. . The comparative higher performance of FW as feeds has established itself as a potent choice for bio-electricity and bio-hydrogen production.