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Lewis R. Blackburn Shi-Kuan Sun Laura J. Gardner Ewan R. Maddrell Martin C. Stennett Claire L. Corkhill Neil C. Hyatt 《Journal of the American Ceramic Society》2021,104(7):2937-2951
A series of zirconolite ceramics with composition CaZr1-xThxTi2O7 (Δx = 0.10) were reactively sintered at 1350°C for 20 h, in air (0 ≤ x ≤ 0.60) and 5% H2/N2 (0 ≤ x ≤ 0.40). A sample with composition corresponding to x = 0.20 was also produced by hot isostatic pressing (HIP) at 1300°C and 100 MPa for 4 hours. Th4+ immobilization was most readily achieved under oxidizing conditions, with Th4+ preferentially incorporated within a pyrochlore-structured phase in the range 0.10 ≤ x ≤ 0.50, yet formation of the zirconolite-4M polytype was not observed. We report the novel synthesis of single-phase pyrochlore with nominal composition CaZr0.40Th0.60Ti2O7 when targeting x = 0.60. Th4+ incorporation under reducing conditions produced a secondary Th-bearing perovskite, comprising 24.2 ± 0.6 wt% of the phase assemblage when targeting x = 0.40, alongside 8.8 ± 0.3 wt% undigested ThO2. Under reducing conditions, powder XRD data were consistent with zirconolite adopting the 3T polytype structure. The sample produced by HIP presented a nonequilibrium phase assemblage, yielding a major phase of zirconolite-2M alongside accessory Th4+-bearing phases ThTi2O6, ThO2, and perovskite. These data highlight the efficacy of Th4+ as a Pu4+ surrogate, with implications for the formation of Zr-stabilized Th-pyrochlore phases as matrices for waste with elevated Th4+ content. 相似文献
3.
Aram Ismail Elizabeth Lewis Birgitta Sjdin Bengt Mannervik 《International journal of molecular sciences》2021,22(8)
Glutathione transferases (GSTs) form a family of detoxication enzymes instrumental in the inactivation and elimination of electrophilic mutagenic and carcinogenic compounds. The Pi class GST P1-1 is present in most tissues and is commonly overexpressed in neoplastic cells. GST P1-1 in the dog, Canis lupus familiaris, has merits as a marker for tumors and as a target for enzyme-activated prodrugs. We produced the canine enzyme CluGST P1-1 by heterologous bacterial expression and verified its cross-reactivity with antihuman-GST P1-1 antibodies. The catalytic activity with alternative substrates of biological significance was determined, and the most active substrate found was benzyl isothiocyanate. Among established GST inhibitors, Cibacron Blue showed positive cooperativity with an IC50 value of 43 nM. Dog GST P1-1 catalyzes activation of the prodrug Telcyta, but the activity is significantly lower than that of the human homolog. 相似文献
4.
Purushothama Chippar Swaraj D. Lewis Sudhir Rai Amit Sircar 《International Journal of Hydrogen Energy》2018,43(16):8007-8017
In this paper, a three-dimensional model for hydrogen absorption in a metal alloy has been developed, validated against the experimental data in the literature, and then applied to a novel design for a hydrogen storage unit. The proposed design is similar to the fuel cell stack, but here the Membrane Electrode Assembly (MEA) has been replaced by a metal hydride (MH) reactor placed between the flow-field plates. These are stacked together to achieve the required amount of hydrogen storage. The flow-field plates have channels engraved on one side for hydrogen supply and on the other, for coolant/heating medium. It is known that the effectiveness of a hydrogen storage unit is directly related to its heat transfer area, and therefore, the choice of its geometry is very important. The larger the size, the more the resistance to heat transfer. Although, the internal tubular heat exchangers have proven to be effective in heat transfer, they pose severe challenges such as cooling/heating medium leakage due to tube erosion, stresses generated, etc. and they displace the active metal hydride from the tank. The present stacked MH reactor configuration helps to overcome these challenges by stacking small MH reactors together and there is no chance of the cooling/heating medium leaking into the metal hydride. Numerical simulations were performed to investigate the effect of coolant flow rate and percentage of flow-field plate rib area exposed to the MH reactor on temperature evolution and the amount of hydrogen stored. Further, a detailed study was carried out to understand the effect of compartmentalization of the MH reactor on temperature distribution. The results revealed that compartmentalization substantially helps to uniformly distribute the temperature in the metal bed, which is very important to maintain uniform utilization of the metal powder. Consequently, the uniform metal powder density for repeated absorption-desorption cycles without significant loss of its hydrogen storage capabilities. 相似文献
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Drawing on and developing Kingdon’s multiple streams analysis, this article examines the development of one aspect of the UK’s low cost home ownership programme: shared ownership. We demonstrate how key human and non-human policy entrepreneurs were able to set the agenda from 1973–1983 in favour of shared ownership; they neutralized the alternatives, while retaining some of their instruments; and solved a number of early problems by bringing key players into the programme. Our data-sets include a range of archival material and elite interviews. The policy entrepreneurs included John Stanley (who was the housing minister in the First Thatcher government), the National Federation of Housing Associations, and the Building Societies Association. Our development of the multiple streams analysis is to argue that documents, including the lease, act as policy entrepreneurs in their own right. The lease was central to the development of shared ownership and its transformation into a model lease enrolled other organizations, most critically the building societies. 相似文献
7.
Farnaz Adib Yaghmaie Kristian Hengster Movric Frank L. Lewis Rong Su 《国际强度与非线性控制杂志
》2019,29(10):2995-3013
》2019,29(10):2995-3013
Differential graphical games have been introduced in the literature to solve state synchronization problem for linear homogeneous agents. When the agents are heterogeneous, the previous notion of graphical games cannot be used anymore and a new definition is required. In this paper, we define a novel concept of differential graphical games for linear heterogeneous agents subject to external unmodeled disturbances, which contain the previously introduced graphical game for homogeneous agents as a special case. Using our new formulation, we can solve both the output regulation and H∞ output regulation problems. Our graphical game framework yields coupled Hamilton‐Jacobi‐Bellman equations, which are, in general, impossible to solve analytically. Therefore, we propose a new actor‐critic algorithm to solve these coupled equations numerically in real time. Moreover, we find an explicit upper bound for the overall ‐gain of the output synchronization error with respect to disturbance. We demonstrate our developments by a simulation example. 相似文献
8.
An increasing fraction of volatile organic compounds (VOC) emissions come from the domestic use of solvents, contained within myriad commonplace consumer products. Emission rates are often poorly characterized and depend significantly on individual behavior and specific product formulation and usage. Time-concentration profiles of volatile organic compounds (VOCs) arising from the use of a representative selection of personal care products (PCPs) during showering are generated, and person-to-person variability in emissions calculated. A panel of 18 participants used a standardized set of products, dosages, and application times during showering in a controlled indoor bathroom setting. Proton transfer mass spectrometry was used to measure the in-room VOC evolution of limonene (representing the sum of monoterpenes), benzyl alcohol, and ethanol. The release of VOCs had reproducible patterns between users, but noticeable variations in absolute peak concentrations, despite identical amounts of material being used. The amounts of VOC emitted to air for one showering activity were as follows: limonene (1.77 mg ± 42%), benzyl alcohol (1.07 mg ± 41%), and ethanol (0.33 mg ± 78%). Real-world emissions to air were between 1.3 and 11 times lower than bottom-up estimates based on dynamic headspace measurements of product emissions rates, likely a result of PCPs being washed away before VOC evaporation could occur. 相似文献
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Amber M. Yeoman Marvin Shaw Nicola Carslaw Tim Murrells Neil Passant Alastair C. Lewis 《Indoor air》2020,30(3):459-472
Volatile organic compounds (VOCs) emitted from personal care products (PCPs) can affect indoor air quality and outdoor air quality when ventilated. In this paper, we determine a set of simplified VOC species profiles and emission rates for a range of non-aerosol PCPs. These have been constructed from individual vapor analysis from 36 products available in the UK, using equilibrium headspace analysis with selected-ion flow-tube mass spectrometry (SIFT-MS). A simplified speciation profile is created based on the observations, comprising four alcohols, two cyclic volatile siloxanes, and monoterpenes (grouped as limonene). Estimates are made for individual unit-of-activity VOC emissions for dose-usage of shampoos, shower gel, conditioner, liquid foundation, and moisturizer. We use these values as inputs to the INdoor air Detailed Chemical Model (INDCM) and compare results against real-world case-study experimental data. Activity-based emissions are then scaled based on plausible usage patterns to estimate the potential scale of annual per-person emissions for each product type (eg, 2 g limonene person−1 yr−1 from shower gels). Annual emissions from non-aerosol PCPs for the UK are then calculated (decamethylcyclopentasiloxane 0.25 ktonne yr−1 and limonene 0.15 ktonne yr−1) and these compared with the UK National Atmospheric Emissions Inventory estimates for non-aerosol cosmetics and toiletries. 相似文献