The adsorption behavior of hydrogen molecules on the calcium-decorated BC7 sheet has been investigated using first-principles calculations. Our calculations demonstrate that the van der Waals ...interactions are crucial for the hydrogen storage in the calcium-decorated BC7 sheet. We find that the average adsorption energy per hydrogen molecules decreases with the number of adsorbed hydrogen molecule increasing. When six hydrogen molecules adsorb, the average adsorption energy is 0.26 eV. In this case, the gravimetric density for hydrogen storage on two sides of calcium-decorated BC7 sheet is about 4.96 wt%. These features indicate that the calcium-decorated BC7 sheet has potential application in hydrogen storage.
•The vdW force plays a crucial role for the hydrogen storage on the Ca-decorated BC7.•We predict that the gravimetric density for the hydrogen storage is about 4.96 wt%.•The adsorption energy is strongly related with the charges on the metal cation.
The self-heating effect of a laboratory X-ray computed tomography (CT) scanner causes slight change in its imaging geometry, which induces translation and dilatation (i.e., artificial displacement ...and strain) in reconstructed volume images recorded at different times. To realize high-accuracy internal full-field deformation measurements using digital volume correlation (DVC), these artificial displacements and strains associated with unstable CT imaging must be eliminated. In this work, an effective and easily implemented reference sample compensation (RSC) method is proposed for
in-situ
systematic error correction in DVC. The proposed method utilizes a stationary reference sample, which is placed beside the test sample to record the artificial displacement fields caused by the self-heating effect of CT scanners. The detected displacement fields are then fitted by a parametric polynomial model, which is used to remove the unwanted artificial deformations in the test sample. Rescan tests of a stationary sample and real uniaxial compression tests performed on copper foam specimens demonstrate the accuracy, efficacy, and practicality of the presented RSC method.
•Flame temperature profiles were measured using traveling thermocouple technique.•The rate of heat release were estimated to characterize hydrogen influence.•Hydrogen addition causes decreases in ...both thicknesses of flame and reaction zone.•OH+H2⇔H+H2O is one of the most governing reaction to the early heat release.
This paper presented an experimental study on the measurements of premixed laminar methane/air flames with and without hydrogen addition. The premixed flames were stabilized on a McKenna flat fame burner at atmospheric pressure. The traveling thermocouple approach was used to measure the axial flame temperature profiles over ranges of equivalence ratios and hydrogen enriching ratios. The measured temperatures, corrected by considering radiation loss, were analyzed to estimate the rate of flame heat release, by solving the continuity equations of mass, energy, and species which were applied to a flat flame. Some of important flame properties, such as the peak temperature, the average temperature, the flame thickness, the thickness of reaction zone and combustion efficiency, were presented to characterize the effect of hydrogen enrichment on laminar flame propagation. It is shown that the presence of hydrogen in laminar flame can promote flame reaction to some extent. With an increase of hydrogen addition fraction in fuel, the peak rate of heat release and combustion efficiency show increases, while the average temperature gives decrease. The analysis of the heat release profiles suggested that hydrogen addition has significant effect on the early part of flame heat release profile. The flames enriched by hydrogen show linear approximations in the plots of the logarithmic heat release rate against the reciprocal of flame temperature. A modeling for one dimensional premixed laminar burner-stabilized flame had been implemented with GRI-Mech 3.0 detailed kinetic reaction mechanism, based on the measured temperature profiles of these premixed flames. And then an analysis on the heat release was performed for each reaction. It suggested that the reaction OH+H2⇔H+H2O gradually increases its contribution to the early heat release with the increase of hydrogen enrichment, which is due to the fact of hydrogen addition resulting in an increased concentration of radical H in flame. The promoted H formation accelerates the flame burning velocity, and then thins the thicknesses of flame and reaction zone to a great extent.
Iodine is a key component of the thyroid hormones, which are critical for healthy growth, development and metabolism. The UK population is now classified as mildly iodine-insufficient. Adequate ...levels of iodine during pregnancy are essential for fetal neurodevelopment, and mild iodine deficiency is linked to developmental impairments. In the absence of prophylaxis in the UK, awareness of nutritional recommendations during pregnancy would empower mothers to make the right dietary choices leading to adequate iodine intake. The present study aimed to: estimate mothers' dietary iodine intake in pregnancy (using a FFQ); assess awareness of the importance of iodine in pregnancy with an understanding of existing pregnancy dietary and lifestyle recommendations with relevance for iodine; examine the level of confidence in meeting adequate iodine intake. A cross-sectional survey was conducted and questionnaires were distributed between August 2011 and February 2012 on local (Glasgow) and national levels (online electronic questionnaire); 1026 women, UK-resident and pregnant or mother to a child aged up to 36 months participated in the study. While self-reported awareness about general nutritional recommendations during pregnancy was high (96 %), awareness of iodine-specific recommendations was very low (12 %), as well as the level of confidence of how to achieve adequate iodine intake (28 %). Median pregnancy iodine intake, without supplements, calculated from the FFQ, was 190 μg/d (interquartile range 144-256μg/d), which was lower than that of the WHO's recommended intake for pregnant women (250 μg/d). Current dietary recommendations in pregnancy, and their dissemination, are found not to equip women to meet the requirements for iodine intake.
Unconventional superconductors are often characterized by numerous competing and even intertwined orders in their phase diagrams. The fluctuations associated with these orders may provide the exotic ...pairing glue that underlies their high-temperature superconductivity. Helimagnet MnP, the first Mn-based superconductor under pressure, lacks high rotational symmetry. However, our resonant soft x-ray scattering experiment discovers novel helical orbital density wave (ODW) orders in MnP and reveals intertwined ordering phenomena. In particular, an ODW forms with half the period of the spin order and fully develops slightly above the spin ordering temperature, which resembles the behaviors of the nematic phase of the iron-based superconductors. Moreover, we find that their domains develop simultaneously, yet the spin order domains are larger than those of the ODW; and they cooperatively produce another ODW with1/3the period of the spin order. These observations provide a comprehensive picture of the intertwined orders in this three-dimensional, low-symmetry system and shed light on the understanding of its superconducting mechanism.
•Tungsten nitride compounds can act as a barrier against H diffusion in W first wall.•Tungsten nitride compounds play a role of H retention.•The nucleation of H bubble can't be formed inside the ...atomic vacancies.
Nitrogen gas seeding is considered as an effective strategy to reduce the edge plasma temperature. The tungsten nitride compounds, which could form on the top of tungsten (W) first wall due to nitrogen gas seeding, may act as a barrier to hinder the diffusion of hydrogen (H) from the tungsten nitride layer to W first wall. By performing first-principles calculations, we investigate the dissolution, diffusion and retention behaviors of H in W2N1, W1N1 and W2N3, respectively. It is found that a H atom prefers to dissolve in tungsten nitride compounds than in W crystal. Hence the compounds can act as a barrier against H diffusion to W first wall, and probably reducing the hydrogen retention in W first wall. All of these behaviors are essentially correlated with the formation of strong N-H bonding in the compounds once H atoms dissolve in them. Moreover, our calculations indcate that H atoms do not form hydrogen molecules even within a vacancy, but stay separately from each other due to the formation of strong N-H bonding. Our work not only proposes that tungsten nitride compounds can significantly reduce hydrogen retention in W first wall, but provides a fundamental insight in understanding the interactions of H with tungsten nitride compounds.
It is necessary to exclude the occurrence of significant waves in the inner water area of the port and at the berthing facilities when designing breakwaters. The article presents the results of the ...calculations of water movement in the harbor area. The most secure options for the location of the port entrance and its size for a given object were identified. The possibility of using the FLOW - 3D program to select planned and constructive solutions at the stage of the preliminary layout of the port water area is substantiated.
The adsorption equilibria of phenol and aniline on nonpolar polymer adsorbents (NDA-100, XAD-4, NDA-16 and NDA-1800) were investigated in single- and binary-solute adsorption systems at 313 K. The ...results showed that all the adsorption isotherms of phenol and aniline on these adsorbents can be well fitted by Freundlich and Langmuir equations, and the experimental uptake of phenol and aniline in all binary-component systems is obviously higher than predicted by the extended Langmuir model, arising presumably from the synergistic effect caused by the laterally acid–base interaction between the adsorbed phenol and aniline molecules. A new model (MELM) was developed to quantitatively describe the synergistic adsorption behavior of phenol/aniline equimolar mixtures in the binary-solute systems and showed a marked improvement in correlating the binary-solute adsorption of phenol and aniline by comparison with the widely used extended Langmuir model. The newly developed model confirms that the synergistic coefficient of one adsorbate is linearly correlated with the adsorbed amount of the other, and the larger average pore size of adsorbent results in the greater synergistic effect of phenol/aniline equimolar mixtures adsorption.
A new model (MELM) was developed to quantitatively describe the synergistic adsorption property of phenol/aniline equimolar mixtures in the binary-solute solution on porous polymer adsorbent surfaces.
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Biochar has attracted global attention because of its widespread application to improve soil quality and enhance soil productivity. Five types of biochar were prepared from peanut shells at 200–600°C ...by slow pyrolysis, and their physicochemical properties were investigated. Biochar was produced at 300 and 400°C, PBC300 and PBC400, respectively. The two forms of biochar were evaluated as soil amendments with an incubation and a pot experiment in a soil that had become acidified because of excessive use of nitrogen (N) fertilizers. The PBC300 and PBC400 additions significantly decreased the soil bulk density and increased the pH, cation exchange capacity (CEC) and soil organic matter (SOM) content. Both types of biochar significantly decreased NH4+‐N and NO3−‐N contents as a result of N immobilization, reduced nitrification because of the enhanced microbial activity (determined by the fluorescein diacetate method) and reduced the abundance of ammonia‐oxidizing bacteria (AOB). The growth of maize (Zea mays L.) was stimulated and, compared with the unamended soil, the biomass increased by 15.2–32.7% following the addition of PBC300 or PBC400. Maize root morphology (e.g. length and tips) and the properties of the rhizosphere soil (e.g. CEC and pH) were improved by the addition of biochar, leading to enhance N bioavailability by decreasing NAE (N accumulation efficiency) and increasing NUE (N utilization efficiency). In general, the ameliorating effects of PBC400 on the acidic soil were superior to those of PBC300. These results indicate that producing a specific type of biochar based on pyrolytic temperature might be an alternative strategy for selecting the most appropriate biochar for a specific soil.
Highlights
Biochar was selected for an acidic soil based on the pyrolytic temperature.
Biochar decreased the soil bulk density and increased the soil pH, CEC and SOM.
Biochar slowed nitrification by decreasing the abundance of ammonia‐oxidizing bacteria (AOB).
Adding biochar stimulated maize growth and improved N bioavailability.
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