Satish Bhagwanjee and Konrad Reinhart
The purpose of this paper is to outline the problem of sepsis and a global initiative to reduce the burden of this disease.
Abstract
Purpose
The purpose of this paper is to outline the problem of sepsis and a global initiative to reduce the burden of this disease.
Design/methodology/approach
This is a summary description of the strategy being applied by the Global Sepsis Alliance (GSA) and its partners to deal with sepsis.
Findings
The paper outlines the problem of sepsis, primary goals of the GSA, early indicators of the outcome from initiatives and proposes strategies for the future. The key initiative was WSD (World Sepsis Day), which succeeded in creating public and stakeholder awareness via the use of focused and informal meetings, use of the media and the internet.
Practical implications
Tackling the problem of sepsis requires a two pronged approach that creates public and stakeholder awareness that prompts action as well as focused research efforts that address the key clinical challenges in sepsis.
Social implications
The importance of community education and support for initiatives that change attitudes and behavior are highlighted.
Originality/value
The proposed initiatives for sepsis that have been implemented as outlined in this paper are novel for the field and have proven to be successful. On‐going supports for such initiatives are warranted.
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Fangyong Niu, Dongjiang Wu, Guangyi Ma, Siyu Zhou and Bi Zhang
The purpose of this paper is to investigate how a second-phase doping may affect Al2O3 ceramic parts deposited by additive manufacturing (AM) with a laser-engineered net shaping…
Abstract
Purpose
The purpose of this paper is to investigate how a second-phase doping may affect Al2O3 ceramic parts deposited by additive manufacturing (AM) with a laser-engineered net shaping system. Direct fabrication of engineering ceramic components by AM is a relatively new method for producing complex mechanical structures.
Design/methodology/approach
In this study, ZrO2 and Y2O3 powders are, respectively, doped into Al2O3 powders at the eutectic ratio as second phases to improve the quality of a deposited part. The deposited Al2O3, Al2O3/ZrO2 and Al2O3/YAG (yttrium aluminum garnet) parts are examined for their micro-structures and micro-hardness, as well as defects.
Findings
The experimental results show that doping of ZrO2 or Y2O3 as a second phase performs a significant role in suppressing cracks and in refining grains of the laser-deposited parts. The micro-hardness investigation reveals that the second-phase doping does not result in much hardness reduction in Al2O3 and the two eutectic ceramics are both harder than 1,500 Hv.
Originality/value
The study concludes that the second-phase doping of ZrO2 and Y2O3 is good for improving laser-deposited Al2O3 ceramic parts.
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Luigi Morfini, Fankai Meng, Margherita Beretta, Jozef Vleugels, Roberto Spina and Eleonora Ferraris
This study aims to investigate the performance of filament-based material extrusion additive manufacturing (MEX), combined with debinding and sintering, as a novel approach to…
Abstract
Purpose
This study aims to investigate the performance of filament-based material extrusion additive manufacturing (MEX), combined with debinding and sintering, as a novel approach to manufacturing ceramic components.
Design/methodology/approach
A commercial ZrO2 filament was selected and analysed by infra-red (IR) spectroscopy, rheology and thermo-gravimetry. The influence of the print parameters (layer thickness, flow rate multiplier, printing speed) and sintering cycle were investigated to define a suitable printing and sintering strategy. Biaxial flexure tests were applied on sintered discs realised with optimised printing strategies, and the results were analysed via Weibull statistics to evaluate the mechanical properties of printed components. The hardness and thermal conductivity of sintered components were also tested.
Findings
Layer thickness and flow rate multiplier of the printing process were proved to have significant effect on the density of as-printed parts. Optimised samples display a sintered density >99% of the theoretical density, 20% linear sintering shrinkage, a characteristic flexural strength of 871 MPa with a Weibull modulus of 4.9, a Vickers hardness of 12.90 ± 0.3 GPa and a thermal conductivity of 3.62 W/mK. Gyroids were printed for demonstration purposes.
Originality/value
To the best of the authors’ knowledge, this work is the first to apply biaxial flexure tests and Weibull statistics to additively manufactured MEX zirconia components, hence providing comparable results to other additive technologies. Moreover, fractography analysis builds the connection between printing defects and the fracture mechanism of bending. This study also provides guidelines for fabricating high-density zirconia components with MEX.
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Asif Ur Rehman, Pedro Navarrete-Segado, Metin U. Salamci, Christine Frances, Mallorie Tourbin and David Grossin
The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective…
Abstract
Purpose
The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective laser sintering (SLS), a dynamic three-dimensional computational model was developed to forecast thermal behavior of hydroxyapatite (HA) bioceramic.
Design/methodology/approach
AM has revolutionized automotive, biomedical and aerospace industries, among many others. AM provides design and geometric freedom, rapid product customization and manufacturing flexibility through its layer-by-layer technique. However, a very limited number of materials are printable because of rapid melting and solidification hysteresis. Melting-solidification dynamics in powder bed fusion are usually correlated with welding, often ignoring the intrinsic properties of the laser irradiation; unsurprisingly, the printable materials are mostly the well-known weldable materials.
Findings
The consolidation mechanism of HA was identified during its processing in a ceramic SLS device, then the effect of the laser energy density was studied to see how it affects the processing window. Premature sintering and sintering regimes were revealed and elaborated in detail. The full consolidation beyond sintering was also revealed along with its interaction to baseplate.
Originality/value
These findings provide important insight into the consolidation mechanism of HA ceramics, which will be the cornerstone for extending the range of materials in laser powder bed fusion of ceramics.
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Swee Leong Sing, Wai Yee Yeong, Florencia Edith Wiria, Bee Yen Tay, Ziqiang Zhao, Lin Zhao, Zhiling Tian and Shoufeng Yang
This paper aims to provide a review on the process of additive manufacturing of ceramic materials, focusing on partial and full melting of ceramic powder by a high-energy laser…
Abstract
Purpose
This paper aims to provide a review on the process of additive manufacturing of ceramic materials, focusing on partial and full melting of ceramic powder by a high-energy laser beam without the use of binders.
Design/methodology/approach
Selective laser sintering or melting (SLS/SLM) techniques are first introduced, followed by analysis of results from silica (SiO2), zirconia (ZrO2) and ceramic-reinforced metal matrix composites processed by direct laser sintering and melting.
Findings
At the current state of technology, it is still a challenge to fabricate dense ceramic components directly using SLS/SLM. Critical challenges encountered during direct laser melting of ceramic will be discussed, including deposition of ceramic powder layer, interaction between laser and powder particles, dynamic melting and consolidation mechanism of the process and the presence of residual stresses in ceramics processed via SLS/SLM.
Originality/value
Despite the challenges, SLS/SLM still has the potential in fabrication of ceramics. Additional research is needed to understand and establish the optimal interaction between the laser beam and ceramic powder bed for full density part fabrication. Looking into the future, other melting-based techniques for ceramic and composites are presented, along with their potential applications.
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Jie Chen, Yongqiang Yang, Shibiao Wu, Mingkang Zhang, Shuzhen Mai, Changhui Song and Di Wang
In this paper, the mechanical properties and corrosion resistance of CoCr alloy fabricated by selective laser melting (SLM) were studied, and the changes of performance after…
Abstract
Purpose
In this paper, the mechanical properties and corrosion resistance of CoCr alloy fabricated by selective laser melting (SLM) were studied, and the changes of performance after porcelain sintering process were also analysed. This study is to point out the relationship between the microstructure, mechanical properties and corrosion resistance of CoCr alloys prepared by SLM after porcelain sintering process. In addition, the biosafety of the sintered CoCr alloy was evaluated.
Design/methodology/approach
The microscopic feature changes of CoCr alloy samples after porcelain sintering process were observed by DMI 5000 M inverted metallographic microscope and Nova Nano430 FE-SEM. Moreover, phase identification and determination were conducted by X-ray diffraction (XRD) using Smartlab X-ray diffractometer. The Vickers microhardness was measured on the HVS-30 microhardness tester, and tensile tests were carried out on a CM3505 electronic universal testing machine. The corrosion resistance was tested by a classical three-point electrode system electrochemical method, then the ion precipitation was measured by using an atomic absorption spectrometer of Z2000 7JQ8024.
Findings
The XRD results indicate that the transition of γ phase (FCC) to e phase (HCP) occurs during the porcelain sintering processing of CoCr alloy. Moreover, the Vickers microhardness of the upper surface and the side surface of the CoCr alloy sample was improved by more than 36%. In addition, the ultimate strength of CoCr alloy via porcelain sintering treatment was increase to 1,395.3 ± 53.0 MPa compared to 1,282.7 ± 10.1 MPa of unprocessed CoCr alloy. However, the corrosion resistance of CoCr alloy samples decreases after porcelain sintering process.
Originality/value
There are few studies on the relationship of microstructure, mechanical properties and corrosion resistance of CoCr alloys prepared by SLM after porcelain sintering process. In this study, the microstructure, mechanical properties and corrosion resistance of CoCr alloy after porcelain sintering process were studied, and the biosafety of the alloy was evaluated. The research found that it is feasible to apply CoCr alloy fabricated by SLM to dental medicine after porcelain sintering process.
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Kai Zhang, Tingting Liu, Wenhe Liao, Changdong Zhang, Yishuai Yan and Daozhong Du
The purpose of this paper is to obtain high-performance ceramics and enrich additive manufacturing of ceramic parts. Also, a new manufacturing technique based on slurry by…
Abstract
Purpose
The purpose of this paper is to obtain high-performance ceramics and enrich additive manufacturing of ceramic parts. Also, a new manufacturing technique based on slurry by selective laser melting (SLM) was studied, which has some significant advantages compared to indirect selective laser sintering of ceramic powders.
Design/methodology/approach
To study the effect of laser parameters on the surface morphology and melting state of pure Al2O3 ceramics, laser power varied between 100 and 200 W and scan speed varied between 60 and 90 mm/s.
Findings
Experimental results show that Al2O3 slurry melts completely when the laser power is about 200 W and the scanning speed is 90 mm/s. Surface quality cannot be improved effectively by changing the scanning speed. However, surface quality improves when the laser power is 200∼205 W and energy density is 889∼911 J/mm3. Thermocapillary convection was observed during SLM. By changing the temperature gradient, streak convection and flowing Bénard cells were obtained during SLM of Al2O3 slurry.
Originality/value
It is feasible to produce slurry ceramic parts without binders through SLM. Increasing the laser power is the most effective way to fully melt the ceramics. Complex thermocapillary convection was observed during this new process; it may be used to produce crystals.
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Fangyong Niu, Dongjiang Wu, Yunfei Huang, Shuai Yan, Guangyi Ma, Chaojiang Li and Jun Ding
Direct additive manufacturing of ceramics (DAMC) is a highly promising ceramics preparation technology because of its simple process and rapid response capability, but the…
Abstract
Purpose
Direct additive manufacturing of ceramics (DAMC) is a highly promising ceramics preparation technology because of its simple process and rapid response capability, but the cracking issue prevents its industrial application. The purpose of this paper is to propose aluminum titanate (Al2TiO5) with low coefficient of thermal expansion (CTE) to suppress cracks during the DAMC.
Design/methodology/approach
Al2O3/Al2TiO5 (A/AT) composite ceramic samples with different compositions were in-situ synthesized from Al2O3/TiO2 (A/T) powder in a directed laser deposition (DLD) process. The relationship between the content of TiO2 and cracking characteristics of fabricated sample was discussed. Phase composition, microstructure and properties of the fabricated samples were also investigated.
Findings
The results of this paper show that the doping of TiO2 can obtain Al2TiO5 synthesized in situ by reaction with Al2O3 and effectively suppress cracks during DAMC. When the content of TiO2 reaches 30 wt.per cent, cracks hardly occur even under conditions of slow deposition. Crack-free structures such as vane, cone and pyramid were successfully prepared, with a maximum cross-sectional dimension of 30 mm and maximum length of 150 mm. A continuous matrix phase formed of the low CTE of Al2TiO5 is the major cause of crack suppression. The dispersed distribution of a-Al2O3 columnar dendrites has the effect of increasing the strength of the matrix. Under current process conditions, the prepared sample with 10 wt.per cent TiO2 has micro-hardness of 21.05 GPa and flexural strength of 170 MPa.
Originality/value
This paper provides a new method and inspiration for direct additive manufacturing of large-sized crack-free ceramics, which has the potential to promote practical application of the technology.
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Maria Aristizabal-Ramirez and Gustavo Canavire-Bacarreza
Development is a dynamic concept that pertains the evolution of human societies. Over the past few years policy makers, as well as academics, have incorporated a very important…
Abstract
Purpose
Development is a dynamic concept that pertains the evolution of human societies. Over the past few years policy makers, as well as academics, have incorporated a very important, yet sometimes neglected, component in the concept of development which is environmental costs and sustainability. One of the key aspects that affects sustainability is energetic consumption, therefore our aim is to determine if changes in oil, coal, and gas, prices during the period 2000–2010 influenced sustainable development.
Methodology/approach
We modified the Human Development Index (HDI) by adding energy consumption component, and propose what we call the Modified Human Sustainable Development Index (HSDI) which captures a broader definition of sustainable development. Then we employ econometric techniques to study the effects of changes in commodity prices on our index in the short run.
Findings
Our results show a nonlinear effect of commodity prices on our index, low and middle-income countries display a positive effect of prices on our HSDI, with smaller effects in the former ones, while high-income countries do not seem to exhibit a significant effect. While low and middle-income countries are typically commodity producers.
Middle-income countries are able to obtain larger benefits in terms of sustainable development due to a better institutional structure which constitutes an opportunity for them in the aftermath of the crisis.
Practical implications
Middle- and low-income countries should design policies that enable them to take advantage of the rises and protect their economies from the falls.
Originality/value
We address the problem of sustainable development and commodity prices in a post-crisi world, which was not reviewed in the literature. In addition we build a measurement of the Human Sustainable Development Index that considers energy consumption as one of its factors. Which is in line with previous results about energy consumption and the Human Development Index.
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In contrast to liberal, orthodox Marxist and structuralinterpretations which attribute government policy in capitalist societyto exogenous forces, the state regularly possesses a…
Abstract
In contrast to liberal, orthodox Marxist and structural interpretations which attribute government policy in capitalist society to exogenous forces, the state regularly possesses a significant area of autonomy within which decisions are effectively determined by the political‐administrative elite (PAE). The majority of the economic projects emanating therefrom can be categorized as either aggrandizing populist or economistic. Postulates the choice of orientation depends upon PAE interests. Concludes that a purely aggrandizing project can be expected only in an environment of decisive underdevelopment while a populist one is almost inevitably a temporary response to conjunctural factors; most common, both in the advanced capitalist countries and the majority of Third World countries is a strong predisposition to an economistic project.