| 571. |
- Horsefield, Rob, 1977, et al.
(författare)
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High-resolution x-ray structure of human aquaporin 5
- 2008
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 105:36, s. 13327-13332
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Tidskriftsartikel (refereegranskat)abstract
- Human aquaporin 5 (HsAQP5)facilitates the transport of water across plasma membranes and has been identified within cells of the stomach, duodenum, pancreas, airways, lungs, salivary glands, sweat glands, eyes, lacrimal glands, and the inner ear. AQP5, like AQP2, is subject to posttranslational regulation by phosphorylation, at which point it is trafficked between intracellular storage compartments and the plasma membrane. Details concerning the molecular mechanism of membrane trafficking are unknown. Here we report the x-ray structure of HsAQP5 to 2.0-angstrom resolution and highlight structural similarities and differences relative to other eukaryotic aquaporins. A lipid occludes the putative central pore, preventing the passage of gas or ions through the center of the tetramer. Multiple consensus phosphorylation sites are observed in the structure and their potential regulatory role is discussed. We postulate that a change in the conformation of the C terminus may arise from the phosphorylation of AQP5 and thereby signal trafficking.
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| 572. |
- Hoseiny, Seyyed Mohammad Hamed, 1980, et al.
(författare)
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The influence of microstructure and mechanical properties on the machinability of martensitic and bainitic prehardened mould steels
- 2013
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Ingår i: International Journal of Materials Research. - : Walter de Gruyter GmbH. - 1862-5282 .- 2195-8556. ; 104:8, s. 748-761
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Tidskriftsartikel (refereegranskat)abstract
- The machinability of two prehardened mould steels, one continuously-cooled and one quenched and tempered, is compared in terms of cutting temperature, cutting force and tool life. Both materials have a hardness of similar to 40 HRC which is a typical hardness for prehardened mould steels. The results of machinability tests are related to mechanical properties and microstructural features, and the material removal rate is estimated for the materials. The continuously-cooled steel with bainitic structure shows higher machinability and possesses superior impact toughness and ductility compared to the quenched and tempered steel with martensitic structure. These properties are very important for plastic mould steels. The continuously-cooled bainitic steel also has the advantage of not requiring any costly quenching and tempering processes in connection with its production.
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| 573. |
- Hosseini, Mohammad, et al.
(författare)
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High-resolution impact assessment of climate change on building energy performance considering extreme weather events and microclimate – Investigating variations in indoor thermal comfort and degree-days
- 2022
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Ingår i: Sustainable Cities and Society. - : Elsevier BV. - 2210-6707. ; 78
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and urbanization are two major challenges when planning for sustainable energy transition in cities. The common approach for energy demand estimation is using only typical meso-scale weather data in building energy models (BEMs), which underestimates the impacts of extreme climate and microclimate variations. To quantify the impacts of such underestimation on assessing the future energy performance of buildings, this study simulates a high spatiotemporal resolution BEM for two representative residential buildings located in a 600 × 600 m2 urban area in Southeast Sweden while accounting for both climate change and microclimate. Future climate data are synthesized using 13 future climate scenarios over 2010-2099, divided into three 30-year periods, and microclimate data are generated considering the urban morphology of the area. It is revealed that microclimate can cause 17% rise in cooling degree-day (CDD) and 7% reduction in heating degree-day (HDD) on average compared to mesoclimate. Considering typical weather conditions, CDD increases by 45% and HDD decreases by 8% from one 30-year period to another. Differences can become much larger during extreme weather conditions. For example, CDD can increase by 500% in an extreme warm July compared to a typical one. Results also indicate that annual cooling demand becomes four and five times bigger than 2010-2039 in 2040-2069 and 2070-2099, respectively. The daily peak cooling load can increase up to 25% in an extreme warm day when accounting for microclimate. In the absence of cooling systems during extreme warm days, the indoor temperature stays above 26°C continuously over a week and reaches above 29.2°C. Moreover, the annual overheating hours can increase up to 140% in the future. These all indicate that not accounting for influencing climate variations can result in maladaptation or insufficient adaptation of urban areas to climate change.
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| 574. |
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| 575. |
- Hoyer, S., et al.
(författare)
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Characterization of the HD 108236 system with CHEOPS and TESS Confirmation of a fifth transiting planet
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 668
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Tidskriftsartikel (refereegranskat)abstract
- Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 Ro˙). Aims. We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. Methods. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets' physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD 108236 to search for the presence of transit timing variations. Results. We derived improved values for the radius and mass of the host star (R∗ = 0.876 ± 0.007 R0 and M∗ = 0.867-0.046+0.047M). We confirm the presence of the fifth transiting planet f in a 29.54 d orbit. Thus, the HD 108236 system consists of five planets of Rb = 1.587±0.028, Rc = 2.122±0.025, Rd = 2.629 ± 0.031, Re = 3.008 ± 0.032, and Rf = 1.89 ± 0.04 [Ro˙]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. Conclusions. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9 d orbital period, as previously suggested. Further monitoring of the transits, particularly for planets b and f, would confirm the presence of the observed transit time variations. HD 108236 thus becomes a key multi-planetary system for the study of formation and evolution processes. The reported precise results on the planetary radii - together with a profuse RV monitoring - will allow for an accurate characterization of the internal structure of these planets.
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| 576. |
- Hsing, T. L., et al.
(författare)
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Remembering Ross Leadbetter: some personal recollections
- 2023
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Ingår i: Extremes. - 1386-1999 .- 1572-915X. ; In Press
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Ross Leadbetter had had a broad and deep influence on the development of probabilistic and statistical theory of extreme values and on the application of extreme-value methods. He has been an inspiration and a friend for many of us. This editorial collects thirteen personal recollections of Ross and his work. An account of his career and some of his work can be found in the IMS Obituary “Ross Leadbetter 1931–2022”.
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| 577. |
- Hu, Enyi, et al.
(författare)
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Junction and energy band on novel semiconductor-based fuel cells
- 2021
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 24:3
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Forskningsöversikt (refereegranskat)abstract
- Fuel cells are highly efficient and green power sources. The typical membrane electrode assembly is necessary for common electrochemical devices. Recent research and development in solid oxide fuel cells have opened up many new opportunities based on the semiconductor or its heterostructure materials. Semiconductor-based fuel cells (SBFCs) realize the fuel cell functionality in a much more straightforward way. This work aims to discuss new strategies and scientific principles of SBFCs by reviewing various novel junction types/interfaces, i.e., bulk and planar p-n junction, Schottky junction, and n-i type interface contact. New designing methodologies of SBFCs from energy band/alignment and built-in electric field (BIEF), which block the internal electronic transport while assisting interfacial superionic transport and subsequently enhance device performance, are comprehensively reviewed. This work highlights the recent advances of SBFCs and provides new methodology and understanding with significant importance for both fundamental and applied R&D on new-generation fuel cell materials and technologies.
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| 578. |
- Huang, Liming, 1993, et al.
(författare)
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Using water vapour and N2 isotherms to unveil effects of SCMs on nanopores and evaluate hydration degree
- 2023
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 164:February 2023
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Tidskriftsartikel (refereegranskat)abstract
- Nanopores are critical for the durability of cement-based materials, but the refinement of these pores by SCMs is yet to have a clear understanding. This paper studied effects of the water–binder ratio, SCMs and the drying on the distribution of nanopores using water vapour and N2 sorption isotherms. Results show that data of water vapour sorption can be used for a practical evaluation of the hydration degree of SCMs with thermodynamic simulation. Fly ash increases the volume of large gel and capillary pores. It lowers the difference between the sorption of water vapour and N2. Slag evidently refines the nanopores by increasing the volume of ink-bottle gel pores with an interlayer-size neck. A higher w/b produces more large pores to reduce the effect of drying. Removal of water induces contraction of interlayer and reduces gel pores volume, which causes large difference between sorption of water vapour and N2.
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| 579. |
- Huang, Zhe, 1986, et al.
(författare)
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Characterization and application of forced cooling channels for traction motors in HEVs
- 2012
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Ingår i: 2012 20th International Conference on Electrical Machines, ICEM 2012; Marseille; France; 2 September 2012 through 5 September 2012. - 9781467301428 ; , s. 1212-1218, s. 1212-1218
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Konferensbidrag (refereegranskat)abstract
- This paper presents the characterization of forced cooling channels with three different shapes which are applied in traction motors mounted in Hybrid Vehicles (HEVs) or Zero Emission Vehicles (ZEVs). Generally, there are two different positions of forced cooling channels in electric motors. One way is by drilling holes or cutting cooling channels inside the housing, which is called indirect cooling approach. The other way is to cut the cooling channels at the edges of housing or/and stator back to form direct cooling channels, where the coolant is in direct contact with the hot stator back. In both cases, choosing suitable shapes of cooling channels are necessary. In this paper, both heat transfer coefficient hf and pump power Wpump are calculated. The dimensional parameters are easily understood and also used for further thermal analysis of the completed machine by either Finite Element Analysis (FEA) or lumped parameter approaches. In addition, the dimensionless parameters Nusselt number Nu and Darcy friction factor f are evaluated with the aim to understand the characterizations for different channels. These parameters are easily used for further cooling channels optimization. In the end, the thermal analyses for a stator segment with three different shaped channels are carried on by applying the calculated results from Computational Fluid Dynamics (CFD) simulations.
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| 580. |
- Huijser, Annemarie, et al.
(författare)
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UV-Dissipation Mechanisms in the Eumelanin Building Block DHICA
- 2010
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Ingår i: ChemPhysChem. - : Wiley. - 1439-7641 .- 1439-4235. ; 11:11, s. 2424-2431
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Tidskriftsartikel (refereegranskat)abstract
- The UV-dissipative mechanisms of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and the 4,7-dideutero derivative (DHICA-d(2)) in buffered H2O or D2O have been characterized by using ultrafast time-resolved fluorescence spectroscopy. Excitation of the carboxylate anion form, the dominating state at neutral pH, leads to dual fluorescence. The band peaking at lambda = 378 nm is caused by emission from the excited initial geometry. The second band around lambda = 450 nm is owed to a complex formed between the monoanion and specific buffer components. In the absence of complex formation, the mono-anion solely decays non-radiatively or by emission with a lifetime of about 2.1 ns. Excitation of the neutral carboxylic acid state, which dominates at acidic pH, leads to a weak emission around lambda = 427 nm with a short lifetime of 240 ps. This emission originates from the zwitterionic state, formed upon excitation of the neutral state by sub-ps excited-state intramolecular proton transfer (ESIPT) between the carboxylic acid group and the indole nitrogen. Future studies will unravel whether this also occurs in larger building blocks and ESIPT is a built-in photoprotective mechanism in epidermal eumelanin.
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