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- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Research review (peer-reviewed)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, Fu qiang, et al.
(author)
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Pressure analysis on two-step high pressure reducing system for hydrogen fuel cell electric vehicle
- 2017
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In: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 42:16, s. 11541-11552
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Journal article (peer-reviewed)abstract
- Hydrogen fuel cell electric vehicle (FCEV) can achieve zero exhaust emission and zero pollution. In order to make FCEV reach a farther travel distance, greater demands are put on its pressure reducing system. In this paper, a two-step high pressure reducing system for FCEV is proposed. The system is made up of two parts, a new high multi-stage pressure reducing valve (HMSPRV) and a multi-stage muffler. As a new system, its feasibility has to be verified. Since the valve opening condition has a great effect on hydrogen flow, pressure reduction and energy consumption, different valve opening conditions are taken as the research point. The flow field analysis of the new HMSPRV is conducted on three aspects: pressure field, velocity field and energy consumption. It can be found that both the pressure reducing and velocity increasing gradients mainly reflect at those throttling components for all valve openings. For energy consumption, in the comprehensive study of flow vortexes and turbulent dissipation rate, it can be found that the larger of the valve opening, the larger of energy consumption. Then, a thermo-fluid-solid coupling analysis is conducted on the new HMSPRV, and it is concluded that the new system meets strength requirement. Furthermore, as the second step of the high pressure reducing system, the flow and pressure fields of multi-stage muffler are investigated. The five-stage muffler is exactly designed to complete the whole pressure reducing process. This study can provide technological support for achieving pressure regulation in the hydrogen transport system of FCEV when facing complex conditions, and it can also benefit the further research work on energy saving and multi-stage flow of pressure reducing devices.
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| 4. |
- Chen, Fu qiang, et al.
(author)
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Thermo-mechanical stress and fatigue damage analysis on multi-stage high pressure reducing valve
- 2017
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In: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549. ; 110, s. 753-767
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Journal article (peer-reviewed)abstract
- A multi-stage high pressure reducing valve (MSHPRV) is proposed. It can achieve a multi-stage pressure reducing way. Valve failure mainly occurs under high pressure and high temperature conditions, thus it is necessary to investigate the strength of MSHPRV under those complex conditions. In this paper, the mathematical model of MSHPRV is established and Computational Fluid Dynamics (CFD) method is employed to simulate its flow fields and thermo-mechanical stress. Next, the stress of MSHPRV under different opening time and the fatigue damage of MSHPRV under different valve openings are studied. Finally, two changes are provided on geometry of MSHPRV and the geometrical factors are optimized. The results show that, the radial direction from inner wall to outer wall is the main heat transfer direction for valve body. At opening time 50 s, the working condition of MSHPRV is dangerous condition. Meanwhile, the maximum value of thermal stress is 487 MPa, which is located at the upper end face of valve chamber region B3. There is a lag effect of stress distribution with respect to temperature distribution. The combined stress of valve body is composed of thermal stress and mechanical stress, in which thermal stress holds the dominant position. Moreover, with the increasing of valve opening, the fatigue damage of valve body increases correspondingly. It can be concluded that MSHPRV can cope with complex conditions like high pressure and high temperature. In the optimization design of MSHPRV, it can be found that the best strength of MSHPRV is achieved with such geometrical factors as angle 15, diameter 4 mm and 2 stage plates. Besides, radian design as the improved structure is recommended. This work can benefit the further research work on the regulation performance and safe operation of high pressure reducing valve.
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| 5. |
- Chen, Fu qiang, et al.
(author)
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Turbulent compressible flow analysis on multi-stage high pressure reducing valve
- 2018
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In: Flow Measurement and Instrumentation. - : Elsevier BV. - 0955-5986. ; 61, s. 26-37
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Journal article (peer-reviewed)abstract
- Pressure reducing valve plays an important role in thermodynamic systems. Under extreme operating conditions, greater demands are requested on pressure reducing systems. In this paper, a novel multi-stage high pressure reducing valve (MSHPRV) is proposed, which can achieve multi-stage pressure reducing processes, improve the flow characteristics and deal with complex conditions. Here, the effects of different structural parameters on turbulent compressible flow inside MSHPRV are numerically investigated to achieve low valve noise and energy consumption. Mach number is taken as the parameter to reflect the fluid compressibility. Higher Mach number can cause serious aerodynamic noise and large amount of energy consumption. Based on this, transmission loss of MSHPRV is also studied to achieve better noise control performances. Meanwhile, larger turbulent dissipation rate means larger degree of energy consumption, so it is with the exergy loss. Thus, numerical models with different valve openings, perforated plate diameters, chamfer radii of perforated plates, pressure ratios and stages of perforated plates are established, and the effects of these structural parameters on the compressible turbulent flow and energy consumption of MSHPRV are investigated. Results show that different structural parameters have significant impacts on compressible turbulent flow and energy consumption performance in MSHPRV. The best noise control and least energy consumption of MSHPRV is achieved with such parameters as pressure ratio 7, perforated plate diameter 4 mm and 4 stage plates. This work can benefit the further research work on energy saving and multi-stage design of pressure reducing devices.
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| 6. |
- Qian, Jin yuan, et al.
(author)
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Flow rate analysis of compressible superheated steam through pressure reducing valves
- 2017
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In: Energy. - : Elsevier BV. - 0360-5442. ; 135, s. 650-658
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Journal article (peer-reviewed)abstract
- Steam flow is the main form for energy transfer in power plants, process industries, etc. The flow rate of the steam relates to the energy transfer amount directly. Pressure reducing valves are used for flow rate control of the compressible superheated steam in these piping systems. In this paper, a pressure reducing valve with a novel valve core is proposed. In order to analyze the internal flow characteristics of the compressible superheated steam and the flow rate adjustment performance of the proposed pressure reducing valve, a numerical model of DN80 pressure reducing valve is established. Then, the flow characteristics inside are studied numerically. Meanwhile, the flow rate adjustment performance is also carried out experimentally. Compared with the numerical and experimental results, it shows an agreement and both of them are similar to linear flow rate. Furthermore, a fitting equation for the flow rate prediction is carried out for the engineering applications under different working conditions.
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