| 1. |
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| 2. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 3. |
- Chen, Jinhan, et al.
(författare)
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The effect of hot isostatic pressing on thermal conductivity of additively manufactured pure tungsten
- 2020
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Ingår i: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 87
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Tidskriftsartikel (refereegranskat)abstract
- The crack-healing behaviors and microstructure evolution of pure tungsten produced by laser powder bed fusion (LPBF) were studied and compared before and after post hot isostatic pressing (post-HIP) treatment. An average thermal conductivity of 133 W.m(-1).K-1 at room temperature (RT) was obtained after HIP, which was 16% higher than that of as-built sample (115 W.m(-1).K-1). Although the HIP process had little effect on density, it resulted in a large grain size of > 300 mu m accompanied by a decrease in dislocation density and crack healing, which led to a substantial improvement of thermal conductivity of pure tungsten. The positive correlation between relative density and thermal conductivity of as-built tungsten was reported.
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| 4. |
- Li, Kailun, et al.
(författare)
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Crack suppression in additively manufactured tungsten by introducing secondary-phase nanoparticles into the matrix
- 2019
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Ingår i: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 79, s. 158-163
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Tidskriftsartikel (refereegranskat)abstract
- In this study, an effective strategy was developed to suppress cracking by introducing secondary-phase ZrC nanoparticles into a tungsten (W) matrix. Pure W and W-0.5wt%ZrC bulks were additively manufactured via the laser powder bed fusion (LPBF) technique, and their cracking behaviour was compared. It was observed that the crack density of W-ZrC was reduced by 88.7% compared with that of pure W. The grains in W-ZrC were obviously refined compared with the grains in pure W, which significantly increased the cracking resistance. In addition, ZrC diminished the oxygen impurities, further increasing the cracking resistance. This study provides a promising strategy for the additive manufacturing of high-quality W by introducing secondary-phase nanoparticles into the metal matrix.
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| 5. |
- Liu, Xihe, et al.
(författare)
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Morphological Development of Sub-Grain Cellular/Bands Microstructures in Selective Laser Melting
- 2019
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Ingår i: Materials. - : MDPI AG. - 1996-1944 .- 1996-1944. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, single-layer and bulk 316 L selective laser melting (SLM) experiments were conducted, fine submicron-scale geometric symmetrical cellular (hexagonal, pentagonal and square), elongated cellular and bands solidification morphologies were found in the laser-melt top surface. Meanwhile, morphological developed sub-grain patterns with quasi-hexagonal cellular, elongated cellular and bands structures (size similar to 1 m) coexisting inside one single macro-solidified grain were also identified. This demonstrated the transitions from quasi-hexagonal-cells to elongated cells/bands, and transitions reverse, occurred in the whole bulk under some circumstances during SLM. Based on the experimental realities, these morphologies are formed by the local convection and Benard instabilities in front of the solid/liquid interface (so-called mushy zones) affected by intricate temperature and surface tension gradients. Quasi-hexagonal cellular convective fields are then superimposed on macro-grain solidification to form the sub-grain patterns and micro-segregations. This explanation seems reasonable and is unifying as it can be expanded to other eutectic alloys with face center cubic (FCC) prevenient phase prepared by SLM, e.g., the Al-Si and Co-Cr-Mo systems.
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| 6. |
- Ma, Jing, et al.
(författare)
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Suppressing pore-boundary separation during spark plasma sintering of tungsten
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438:1-3, s. 199-203
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Tidskriftsartikel (refereegranskat)abstract
- A tungsten powder with bimodal particle size distribution is consolidated by spark plasma sintering (SPS). Effects are made for understanding the densification and grain growth mechanisms and their relations to the SPS processing parameters. By holding the sample at an intermediate temperature, i.e., 1200 degrees C for 5 min, where the densification is enhanced by particle close packing, the pore-boundary separation that yields the formation of entrapped pores inside individual grains at final stage of sintering is suppressed. This optimization of the SPS process is beneficial for preparing fine grained bulk tungsten with homogeneous microstructure from the powders produced in industrial-scale. The prepared tungsten with minimized porosity appears a potential candidate for plasma-facing materials in the divertor region in the International Thermonuclear Experimental Reactor (ITER).
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| 7. |
- Ma, Shengyuan, et al.
(författare)
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Comparison of the time-dependent characteristics between particle mass and particle number emissions during oil heating and emission mitigation strategies
- 2023
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 242
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Tidskriftsartikel (refereegranskat)abstract
- It is important to understand the cooking particles emitted over time to mitigate cooking pollution, but current control strategies fail to consider both particle mass and number emissions. Therefore, this study was designed to compare the differences in time-dependent characteristics of particle mass and number emissions and to propose comprehensive mitigation strategies that consider both characteristics. For this purpose, the effects of various factors on both emissions were analyzed, and time-dependent emission rate models were developed. The time-dependent models obtained were statistically significant (P < 0.001), with most R2 values greater than 0.90. The masses and numbers of particles emitted often varied in the opposite direction. During the smoking stage, corn oil exhibited low particle mass emissions while its particle number emission rate (TERn) reached 109#/s. However, at higher temperatures (T > TDM), the percentage difference in TERn with increasing oil volume decreased from 7.1% to 3.5%, while that in PM2.5 emission rate with decreasing oil volume was almost more than 25%. This indicated that the increased oil volumes were more effective in reducing the particle masses emitted from corn oil than in increasing the numbers of particles emitted, and similar conclusions were also drawn for decreasing oil surface area. Overall, oils exhibiting lower particle mass emissions and lower cooking temperatures were recommended for cooking. Lower oil volumes and larger pans should be used at relatively lower temperatures (T < TDM) primarily to mitigate particle number emissions, while higher oil volumes and smaller pans should be used at higher temperatures to control particle mass emissions.
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| 8. |
- Ma, Shengyuan, et al.
(författare)
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Indoor thermal environment in a rural dwelling heated by air-source heat pump air-conditioner
- 2022
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Ingår i: Sustainable Energy Technologies and Assessments. - : Elsevier BV. - 2213-1388 .- 2213-1396. ; 51
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Tidskriftsartikel (refereegranskat)abstract
- Air-source heat pumps (ASHP) are increasingly used to improve space heating. However, few relevant studies have focused on the rural residential buildings that use ASHP air-conditioners for heating conditions. Therefore, this paper presents experiments and numerical simulations to analyse the impact of ASHP air-conditioners on the indoor thermal environment of a rural dwelling during heating seasons. In this study, the influences of different air-supply parameters (temperature, angle and velocity of air supply) and the position of the ASHP airconditioner on the local thermal comfort were evaluated. The influence weights of both the above factors and their interaction were obtained. The simulation results showed that the temperature differences between the head and foot region (Delta Th-f) in most cases exceeded 3.0celcius, demonstrating the thermal comfort in the rural dwelling was more unacceptable than the urban buildings. Moreover, the results of orthogonal design indicated that air-supply velocity had the most significant impact on the Delta Th-f values, followed by the air-supply temperature, air-supply angle and installation height. Reducing any air-supply parameter or enhancing the installation height might improve the thermal comfort performance. This research can provide practical strategies for improving the indoor thermal environment of rural dwellings, and guide the design of ASHP air-conditioning systems.
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| 9. |
- Olsén, Jon, 1983-, et al.
(författare)
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Tailoring hierarchical structures in selective laser melted materials
- 2017
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Ingår i: IOP Conference Series. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- With selective laser melting the potential to manufacture a wide variety of geometries from different materials has presented itself. Interest in this technology keeps growing every year, and with that growth a deeper understanding of the process and resulting materials is urgently needed. In this paper we present a short overview of the structural elements that appear during selective laser melting, and explain how to tailor them to achieve specific structures and material properties. Melt-pools, texture and grains, subgrain cells, and inclusions are the elements discussed herein, and tailoring of these elements can have effects on density, and corrosion resistance, as well as mechanical properties in general.
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| 10. |
- Wang, Dianzheng, et al.
(författare)
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Cracking in laser additively manufactured W : Initiation mechanism and a suppression approach by alloying
- 2019
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 162, s. 384-393
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Tidskriftsartikel (refereegranskat)abstract
- Cracking represents the main challenge for exploiting tungsten in additive manufacturing. In this study, laser powder-bed-fusion technique was applied to additively manufacture tungsten. In the built bulks, the grain boundaries were found to be rich in nanoscale gas pores. On the basis of that, a nanopore segregation induced cracking initiation mechanism was proposed. In order to control cracks, W-6wt.%Ta alloy was produced and the cracking suppression mechanism was investigated. The W-6Ta alloy is characterized by a submicron intragranular cellular structure, which composed large amount of interlocked dislocations as revealed by transmission electron microscopy. Owing to the cellular structure, the nanopores were trapped inside grains, which can reduce the cracking possibility. Moreover, the W-Ta alloy possesses higher strength (by 17%) and higher energy dissipation rate (by 52%) than pure tungsten, which both are beneficial for crack reduction.
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