Research and Engineering Practice in Nanofluids: Key Issues

2011 ◽  
Author(s):  
L. Q. Rick Wang
Keyword(s):  
System Performance ◽  
Wave Theory ◽  
Global Scale ◽  
Constructal Theory ◽  
Engineering Practice ◽  
Past Century ◽  
Heat Transfer Fluids ◽  
The Past ◽  
Nano Structures ◽  
Key Issues

Unlike the past century that was blessed with ever-abundant cheap oil, this century energy has been rated as the single most important issue facing humanity. A global-scale energy crisis looms ahead. Nanotechnology will figure centrally in providing technological solutions. Nanofluid technology, one of the enabling technologies of the nanotech revolution, holds the promise of significantly enhancing the thermal properties of fluids and thus providing high quality heat-transfer fluids of the future that are vital for solving the terawatt challenge facing us. Nanofluids, fluid suspensions of nanometer-sized structures, are research challenges of rare potential but daunting difficulty. The potential comes from both scientific and practical opportunities in many fields. The difficulty reflects the issues related to multiscales. Nanofluids involve at least four relevant scales: the molecular scale, the microscale, the macroscale and the system-scale, with the microscale as the additional one at which nano structures interact with the base fluids. By their very nature, research and engineering practice in nanofluids are to optimize the microscale physics (structures, properties and activities) for the best system performance via enhanced macroscale properties through manipulating microscale physics. Therefore, interest should focus on addressing questions like: (i) how to optimize microscale physics for the optimal system performance, (ii) what is the macroscale manifestation of microscale physics, and (iii) how to effectively manipulate at microscale. In this keynote lecture, we summarize our work of addressing these key issues with powerful microfluidic technology, thermal-wave theory and constructal theory by taking heat-conduction nanofluids as the example.

Coastal dune mobility over the past century: A global review

2020 ◽  
Vol 44 (6) ◽  
pp. 814-836 ◽  
Author(s):  
Jinjuan Gao ◽  
David M Kennedy ◽  
Teresa M Konlechner
Keyword(s):  
Human Activities ◽  
Vegetation Cover ◽  
Dominant Role ◽  
Coastal Dunes ◽  
Mediterranean Area ◽  
Global Scale ◽  
Coastal Dune ◽  
Sediment Supply ◽  
Past Century ◽  
The Past

The mobility of coastal dunes is characterised by bio-geomorphological responses related to change in boundary conditions, particularly sediment supply, wind and vegetation cover, as well as human activities. There remains uncertainty regarding the relative importance of these drivers on dune mobility at a global scale. In this study, trends and dominant drivers of coastal dune mobility are synthesised through the literature review focusing on shifts in dune mobility over the last century (1870–2018). In total, 176 individual dunes, with 55 dunes from the Europe-Mediterranean area, 23 from Africa, 30 from North America, 23 from South America, 20 from Oceania and 23 from Asia, are reviewed in this work. The results show that there is a worldwide trend of dune stabilisation, with 93% (164 out of 176) of the reviewed sites showing a loss of bare sand area due to an increase in vegetation cover and urbanisation expansion. Multiple factors have contributed to the stabilisation process, including (a) land-use change such as the change of traditional farming practises, coastal urbanisation and tourism development; (b) dune stabilisation projects; (c) sediment decline caused by the riverine and coastal constructions; and (d) change in climate (i.e. the decrease in windiness, and the increase in temperature and rainfall) and storms. Our results suggest human intervention played a dominant role in altering dune mobility for most dunes during the past century, while climate and storms are also important drivers, especially for dune sites with limited human activities.

Powder Processing of Refractory Metals and Alloys

1993 ◽  
Vol 322 ◽  
Author(s):  
Randall M. German
Keyword(s):  
Thermal Properties ◽  
Powder Processing ◽  
Refractory Metals ◽  
Metals And Alloys ◽  
Liquid Phase Sintering ◽  
Past Century ◽  
The Past ◽  
Good Shape ◽  
Growth Area ◽  
Key Issues

AbstractFor the past century the processing of refractory metals and alloys has been linked to powder metallurgy (P/M). A firm understanding of processing has been critical to attaining the desired performance levels. Although the consolidation science is in good shape, the availability of tailored powders with appropriate attributes is a limitation. This presentation reviews the key issues related to refractory metal and alloy processing, with particular emphasis on tungsten and its alloys. An exciting growth area is in liquid phase sintering microelectronic systems where the concern is with thermal properties, specifically for W-Cu and Mo-Cu.

Research and Engineering Practice in Nanofluids: Key Issues

2010 ◽  
Author(s):  
Liqiu Wang
Keyword(s):  
Research And Development ◽  
Effective Means ◽  
Volume Averaging ◽  
Constructal Theory ◽  
Future Research ◽  
Engineering Practice ◽  
Constructal Design ◽  
New Class ◽  
Key Issues ◽  
Phase Chemical

Nanofluids are a new class of fluids engineered by dispersing nanometer-size structures (particles, fibers, tubes, droplets) in base fluids. The very essence of nanofluids research and development is to enhance fluid macroscopic and megascale properties/performance such as thermal conductivity through manipulating microscopic physics (structures, properties and activities). Therefore, the success of nanofluid technology depends very much on how well we can address issues like effective means of microscale manipulation, interplays among physics at different scales, and optimization of microscale physics for the optimal megascale properties. In this poster we review methodologies available to effectively tackle these key but difficult problems and identify the future research needs as well. The reviewed techniques include nanofluids synthesis through liquid-phase chemical reactions in continuous-flow microfluidic microreactors, scaling-up by the volume averaging, and constructal design with the constructal theory. The identified areas of future research contain microfluidic nanofluids, thermal waves, and constructal nanofluids. While our focus is on heat-conduction nanofluids, the methodologies are equally valid for the other types of nanofluids. The review could serve as a coherent, inspiring and realistic plan for future research and development of nanofluid technology.

Beirut by Night

2015 ◽  
Vol 8 (2-3) ◽  
pp. 256-281 ◽  
Author(s):  
Gregory Buchakjian
Keyword(s):  
Civil War ◽  
Technological Development ◽  
Global Scale ◽  
Past Century ◽  
Public Spheres ◽  
Lebanese Civil War ◽  
The Past ◽  
Private And Public ◽  
Technological Developments ◽  
History Of

Over the past century, Beirut has acquired a reputation as the nightlife destination of choice in the region. Photography was and remains a privileged witness of the proverbial ‘Beirut nights’. In this essay I trace the history of the genre of nightlife photography in Beirut over the past century, from the grand ball era of the Mandate period to informal underground nightlife during the civil war and its aftermath; to the rise of the nightlife image-making industry in the 1990s and 2000s. I pay particular attention to the ways in which technological developments interplayed with historical and social contingencies in Lebanon—such as the Lebanese civil war and the disintegration of barriers between private and public spheres in the age of social media. Recast as art, digital nightlife photography is responsible for the erosion of ‘vulgarity’ as a social category under the twin pressures of neoliberalism and technological development; it also plays a major role in the contemporary branding of Beirut on a global scale.

The zoonotic potential of bat-borne coronaviruses

2020 ◽  
Vol 4 (4) ◽  
pp. 365-381
Author(s):  
Ny Anjara Fifi Ravelomanantsoa ◽  
Sarah Guth ◽  
Angelo Andrianiaina ◽  
Santino Andry ◽  
Anecia Gentles ◽  
...  
Keyword(s):  
Genetic Material ◽  
Field Research ◽  
Sympatric Species ◽  
Animal Origin ◽  
Mammalian Host ◽  
Past Century ◽  
The Past ◽  
Novel Host ◽  
Horseshoe Bat ◽  
Human Infections

Seven zoonoses — human infections of animal origin — have emerged from the Coronaviridae family in the past century, including three viruses responsible for significant human mortality (SARS-CoV, MERS-CoV, and SARS-CoV-2) in the past twenty years alone. These three viruses, in addition to two older CoV zoonoses (HCoV-229E and HCoV-NL63) are believed to be originally derived from wild bat reservoir species. We review the molecular biology of the bat-derived Alpha- and Betacoronavirus genera, highlighting features that contribute to their potential for cross-species emergence, including the use of well-conserved mammalian host cell machinery for cell entry and a unique capacity for adaptation to novel host environments after host switching. The adaptive capacity of coronaviruses largely results from their large genomes, which reduce the risk of deleterious mutational errors and facilitate range-expanding recombination events by offering heightened redundancy in essential genetic material. Large CoV genomes are made possible by the unique proofreading capacity encoded for their RNA-dependent polymerase. We find that bat-borne SARS-related coronaviruses in the subgenus Sarbecovirus, the source clade for SARS-CoV and SARS-CoV-2, present a particularly poignant pandemic threat, due to the extraordinary viral genetic diversity represented among several sympatric species of their horseshoe bat hosts. To date, Sarbecovirus surveillance has been almost entirely restricted to China. More vigorous field research efforts tracking the circulation of Sarbecoviruses specifically and Betacoronaviruses more generally is needed across a broader global range if we are to avoid future repeats of the COVID-19 pandemic.

PCSK9 inhibition for LDL lowering and beyond – implications for patients with peripheral artery disease

VASA ◽  
2018 ◽  
Vol 47 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Katrin Gebauer ◽  
Holger Reinecke
Keyword(s):  
Cardiovascular Risk ◽  
Risk Reduction ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Past Century ◽  
Pcsk9 Inhibitors ◽  
Cardiovascular Risk Reduction ◽  
Simultaneous Application ◽  
The Past ◽  
Pcsk9 Inhibition

Abstract. Low-density lipoprotein cholesterol (LDL-C) has been proven to be a causal factor of atherosclerosis and, along with other triggers like inflammation, the most frequent reason for peripheral arterial disease. Moreover, a linear correlation between LDL-C concentration and cardiovascular outcome in high-risk patients could be established during the past century. After the development of statins, numerous randomized trials have shown the superiority for LDL-C reduction and hence the decrease in cardiovascular outcomes including mortality. Over the past decades it became evident that more intense LDL-C lowering, by either the use of highly potent statin supplements or by additional cholesterol absorption inhibitor application, accounted for an even more profound cardiovascular risk reduction. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a serin protease with effect on the LDL receptor cycle leading to its degradation and therefore preventing continuing LDL-C clearance from the blood, is the target of a newly developed monoclonal antibody facilitating astounding LDL-C reduction far below to what has been set as target level by recent ESC/EAS guidelines in management of dyslipidaemias. Large randomized outcome trials including subjects with PAD so far have been able to prove significant and even more intense cardiovascular risk reduction via further LDL-C debasement on top of high-intensity statin medication. Another approach for LDL-C reduction is a silencing interfering RNA muting the translation of PCSK9 intracellularly. Moreover, PCSK9 concentrations are elevated in cells involved in plaque composition, so the potency of intracellular PCSK9 inhibition and therefore prevention or reversal of plaques may provide this mechanism of action on PCSK9 with additional beneficial effects on cells involved in plaque formation. Thus, simultaneous application of statins and PCSK9 inhibitors promise to reduce cardiovascular event burden by both LDL-C reduction and pleiotropic effects of both agents.

Archaeology in the Past Century

1901 ◽  
Vol 51 (1309supp) ◽  
pp. 20976-20977
Author(s):  
W. M. Flinders Petrje
Keyword(s):  
Past Century ◽  
The Past

Catholicism and Cosmopolitanism: the Confluence of Three Catholic Scholars and the Cosmopolitan Democrats on State Sovereignty and the Future of Global Governance

2016 ◽  
Vol 3 (2) ◽  
pp. 37-51
Author(s):  
Matthew Bagot
Keyword(s):  
Global Governance ◽  
State Sovereignty ◽  
Current Debate ◽  
Past Century ◽  
Jacques Maritain ◽  
The Past ◽  
Technological Advances ◽  
The Future ◽  
Cosmopolitan Democracy ◽  
Catholic Tradition

One of the central questions in international relations today is how we should conceive of state sovereignty. The notion of sovereignty—’supreme authority within a territory’, as Daniel Philpott defines it—emerged after the Treaty of Westphalia in 1648 as a result of which the late medieval crisis of pluralism was settled. But recent changes in the international order, such as technological advances that have spurred globalization and the emerging norm of the Responsibility to Protect, have cast the notion of sovereignty into an unclear light. The purpose of this paper is to contribute to the current debate regarding sovereignty by exploring two schools of thought on the matter: first, three Catholic scholars from the past century—Luigi Sturzo, Jacques Maritain, and John Courtney Murray, S.J.—taken as representative of Catholic tradition; second, a number of contemporary political theorists of cosmopolitan democracy. The paper argues that there is a confluence between the Catholic thinkers and the cosmopolitan democrats regarding their understanding of state sovereignty and that, taken together, the two schools have much to contribute not only to our current understanding of sovereignty, but also to the future of global governance.

Aftershocks

2017 ◽  
Author(s):  
Seva Gunitsky
Keyword(s):  
Twentieth Century ◽  
Regime Change ◽  
International System ◽  
Political Legitimacy ◽  
Great Powers ◽  
Past Century ◽  
The Past ◽  
Sudden Rise ◽  
The World ◽  
National Borders

Over the past century, democracy spread around the world in turbulent bursts of change, sweeping across national borders in dramatic cascades of revolution and reform. This book offers a new global-oriented explanation for this wavelike spread and retreat—not only of democracy but also of its twentieth-century rivals, fascism, and communism. The book argues that waves of regime change are driven by the aftermath of cataclysmic disruptions to the international system. These hegemonic shocks, marked by the sudden rise and fall of great powers, have been essential and often-neglected drivers of domestic transformations. Though rare and fleeting, they not only repeatedly alter the global hierarchy of powerful states but also create unique and powerful opportunities for sweeping national reforms—by triggering military impositions, swiftly changing the incentives of domestic actors, or transforming the basis of political legitimacy itself. As a result, the evolution of modern regimes cannot be fully understood without examining the consequences of clashes between great powers, which repeatedly—and often unsuccessfully—sought to cajole, inspire, and intimidate other states into joining their camps.

Variable oil and argumentative conflict in the Middle East

2020 ◽  
pp. 824
Author(s):  
Malik Daham Mata’ab
Keyword(s):  
Middle East ◽  
Past Century ◽  
Large Area ◽  
The Past ◽  
The World

Oil has formed since its discovery so far one of the main causes of global conflict, has occupied this energy map a large area of conflict the world over the past century, and certainly this matter will continue for the next period in our century..

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