490 research outputs found
Synthesis of Na-Doped Lithium Metatitanate and Its Absorption for Carbon Dioxide
Na-doped lithium metatitanate (Na-doped Li2TiO3) absorbent was doped with Na2CO3 and lithium metatitanate (Li2TiO3) was prepared by a solid-state reaction method from mixture of TiO2 and Li2CO3. The Na-doped lithium metatitanate was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and surface area. Carbon dioxide absorption on Na-doped lithium metatitanate was investigated using TG-DTA. The results reveal an increase of the CO2 absorption capacity of the Na-doped materials with respect to pure Li2TiO3. XRD patterns of the doped samples suggest a limited substitution of Li by Na atoms within the Li2TiO3 structure. The results of experimental and modeling work were summarized to better understand the relationship between the sorbent microstructure and carbon dioxide absorption kinetics
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Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions
The behavior of individual nanocrystals during superlattice phase transitions can profoundly affect the structural perfection and electronic properties of the resulting superlattices. However, details of nanocrystal morphological changes during superlattice phase transitions are largely unknown due to the lack of direct observation. Here, we report the dynamic deformability of PbSe semiconductor nanocrystals during superlattice phase transitions that are driven by ligand displacement. Real-time high-resolution imaging with liquid-phase transmission electron microscopy reveals that following ligand removal, the individual PbSe nanocrystals experience drastic directional shape deformation when the spacing between nanocrystals reaches 2 to 4 nm. The deformation can be completely recovered when two nanocrystals move apart or it can be retained when they attach. The large deformation, which is responsible for the structural defects in the epitaxially fused nanocrystal superlattice, may arise from internanocrystal dipole-dipole interactions
Strategies for Prioritizing Needs for Accelerated Construction after Hazard Events
There is a need for rapid and responsive infrastructure repair and construction after natural disaster events such as hurricanes, wildfires, and tornadoes. These natural disasters often shut down basic infrastructure systems, as experienced recently in several Region 6 states as well as in other states around the country. Accelerated construction practices are often used in these situations to speed up the traditional, and often slow, project delivery process. However, after a natural disaster, several and different types of transportation infrastructure components are in need of inspection, rehabilitation or reconstruction, and transportation agencies are challenged with the task of prioritizing these accelerated projects. This study conducted an extensive literature review of current accelerated methods, infrastructure prioritization practices, and institutional barriers. Interviews with professionals from the transportation industry, including both private and public services, were conducted. Significant input from the railroad industry was used to compare private and public transportation systems responses after disasters. The results of this survey were used to quantify the importance of the accelerate methods and prioritization criteria, and which are the barriers to implement a prioritization model. Lastly, a decision support tool for prioritizing needs for accelerated construction after disaster events, specifically hurricanes and flooding, which commonly affect Region 6, was developed using the data collected
Strict Intuitionistic Fuzzy Distance/Similarity Measures Based on Jensen-Shannon Divergence
Being a pair of dual concepts, the normalized distance and similarity
measures are very important tools for decision-making and pattern recognition
under intuitionistic fuzzy sets framework. To be more effective for
decision-making and pattern recognition applications, a good normalized
distance measure should ensure that its dual similarity measure satisfies the
axiomatic definition. In this paper, we first construct some examples to
illustrate that the dual similarity measures of two nonlinear distance measures
introduced in [A distance measure for intuitionistic fuzzy sets and its
application to pattern classification problems, \emph{IEEE Trans. Syst., Man,
Cybern., Syst.}, vol.~51, no.~6, pp. 3980--3992, 2021] and [Intuitionistic
fuzzy sets: spherical representation and distances, \emph{Int. J. Intell.
Syst.}, vol.~24, no.~4, pp. 399--420, 2009] do not meet the axiomatic
definition of intuitionistic fuzzy similarity measure. We show that (1) they
cannot effectively distinguish some intuitionistic fuzzy values (IFVs) with
obvious size relationship; (2) except for the endpoints, there exist infinitely
many pairs of IFVs, where the maximum distance 1 can be achieved under these
two distances; leading to counter-intuitive results. To overcome these
drawbacks, we introduce the concepts of strict intuitionistic fuzzy distance
measure (SIFDisM) and strict intuitionistic fuzzy similarity measure (SIFSimM),
and propose an improved intuitionistic fuzzy distance measure based on
Jensen-Shannon divergence. We prove that (1) it is a SIFDisM; (2) its dual
similarity measure is a SIFSimM; (3) its induced entropy is an intuitionistic
fuzzy entropy. Comparative analysis and numerical examples demonstrate that our
proposed distance measure is completely superior to the existing ones
Mass Spectrometric Study of Acoustically Levitated Droplet Illuminates Molecular-Level Mechanism of Photodynamic Therapy for Cancer involving Lipid Oxidation
Even though the general mechanism of photodynamic cancer therapy is known, the details and consequences of the reactions between the photosensitizerâgenerated singlet oxygen and substrate molecules remain elusive at the molecular level. Using temoporfin as the photosensitizer, here we combine fieldâinduced droplet ionization mass spectrometry and acoustic levitation techniques to study the âwallâlessâ oxidation reactions of 18:1 cardiolipin and 1âpalmitoylâ2âoleoylâsnâglyceroâ3âphosphoâ(1â˛âracâglycerol) (POPG) mediated by singlet oxygen at the airâwater interface of levitated water droplets. For both cardiolipin and POPG, every unsaturated oleyl chain is oxidized to an allyl hydroperoxide, which surprisingly is immune to further oxidation. This is attributed to the increased hydrophilicity of the oxidized chain, which attracts it toward the water phase, thereby increasing membrane permeability and eventually triggering cell death
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