To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The earliest colonisation of oceanic islands by Homo sapiens occurred ~50 000–30 000 years ago in the Western Pacific, yet how this was achieved remains a matter of debate. With a focus on East Asia, the research presented here tests the hypothesis that bamboo rafts were used for these early maritime migrations. The authors review the evidence for Palaeolithic seafaring in East Asia as the context for an experimental archaeology project to build two bamboo watercraft. Sea trials demonstrate the unsuitability of bamboo, at least in East Asia, indicating that more sophisticated and durable vessels would have been required to traverse the Kuroshio Current.
Consumption of a high-fat diet increases fat accumulation and may further lead to inflammation and hepatic injuries. The aim of the study was to investigate the effects of Camellia oleifera seed extract (CSE) on nonalcoholic fatty liver disease (NAFLD). After a 16-week NAFLD-inducing period, rats were assigned to experimental groups fed an NAFLD diet with or without CSE. At the end of the study, we found that consuming CSE decreased the abdominal fat weight and hepatic fat accumulation and modulated circulating adipokine levels. We also found that CSE groups had lower hepatic cytochrome P450 (CYP) 2E1 and transforming growth factor (TGF)-β protein expressions. In addition, we found that CSE consumption may have affected the gut microbiota and reduced toll-like receptor (TLR)-4, myeloid differentiation primary response gene 88 (MyD88), toll/Interleukin-1 receptor domain-containing adaptor inducing interferon-β (TRIF) expression, and proinflammatory cytokine concentrations in the liver. Our results suggest that CSE may alleviate the progression of NAFLD in rats with diet-induced steatosis through reducing fat accumulation and improving lipid metabolism and hepatic inflammation.
Conventional alloy design based on a single primary element has reached its limits in terms of performance optimization. An alloy design strategy with multi-principal elements has recently been uncovered to overcome this bottleneck. Multicomponent alloys, generally referred to as high-entropy alloys (HEAs), exhibit many promising properties, especially outstanding mechanical performance at cryogenic, ambient, and elevated temperatures. In this article, we focus on precipitation-hardened HEAs, which are potential candidates for next-generation structural materials, especially at high temperatures. The key issues involved include precipitation behaviors, phase stability, and phase control, all of which provide useful guidelines for further development of high-temperature materials with superior performance. In particular, we address the formation of cellular γ′ precipitates at grain boundaries, which is closely related to the embrittlement of HEAs at intermediate temperatures. Critical issues and design strategies in developing HEAs for high-temperature applications are also discussed.
Understanding changes in chemistry, microstructure, and physical properties during synthesis, processing, testing, and even service is vital for materials design and performance. Compared to traditional postmortem material characterization tools, in situ crystallographic characterization can provide considerable data and information on evolution of chemistry, dislocations, twinning, texture, and strains when a material is under external stimuli. Neutrons especially are able to probe material bulk properties and behaviors in extreme environments, thanks to their deep penetrating power and unique sensitivity to differentiate elements from lightweight to transition-metal atoms. In this article, we introduce and describe a diffractometer named VULCAN, which is located at Oak Ridge National Laboratory. This represents a powerful tool to understand materials properties and behaviors under complex environments, in particular, at high temperatures.
Metallic glasses have attractive properties, but since the glassy state is inherently metastable, they are not normally considered for applications at elevated temperatures. Yet, studies have shown that multicomponent and pseudo high-entropy (PHE) compositions can confer useful heat resistance. The formation, thermal stability, and mechanical and chemical properties of multicomponent Fe-(Cr, Mo)- and Zr-based bulk metallic glasses (BMGs) are reviewed to assess their potential as heat-resistant structural materials. The composition Fe43Cr16Mo16C15B10 is castable and fully glassy with rod diameters up to 2.7 mm. Glassy coatings of this material with low porosity, good mechanical properties, and good corrosion resistance can be produced by high-velocity spray coating. The compositions Zr55–65Al7.5–10(TM1,TM2)27.5–35 (TM1 = Fe, Co, Ni, TM2 = Cu, Pd, Ag, Au) yield PHE BMGs, in which a stable cluster-like glassy phase without crystalline precipitates is formed by annealing at temperatures well above the first calorimetric transformation. It is suggested that proliferation of alloy components is an effective method to synthesize metastable metallic materials that retain high strength at elevated temperatures.
Tougher, lighter, and more formable and machinable metals for broader ranges of applications at higher temperatures are needed now more than ever. High-performance computing, high-resolution microscopy, and advanced spectroscopy methods, including neutrons and synchrotron x-rays, together with advances in metallurgy and metal mixology, reveal the potential of multicomponent advanced metals, such as multicomponent bulk metallic glasses and advanced high-entropy alloys. The development of new experimental approaches relates bulk properties and voxel-associated optimized properties throughout structures with high resolution. The correlations from in situ measurements greatly improve crystal plasticity-based models. This issue of MRS Bulletin overviews recent progress in the field, and this article highlights the importance of these new perspectives. The latest progress and directions in the science and technology for prospective high-temperature metals for structural applications are reported.