Use of thermodynamic chemical potential diagrams (µCaO, µCO2) to understand the weathering of cement by a slightly carbonated water

Cement is a ubiquitous material that may suffer hazardous weathering. The chemical weathering of cement in natural environment is mostly characterized by the leaching of CaO and the addition of CO2. The different weathering zones that develop at the expense of the cement may be predicted by the help of chemical potential phase diagrams; these diagrams simulate the behaviour of systems open to some chemical elements. Some components have a so-called inert status, that is to say the system is closed for these components, their amount in the system remains constant; some other components have a mobile status, that is to say these components can be exchanged with the outside of the system, their amount can vary from one sample zone to another. The mobile components are represented in the model by their chemical potentials (linked to their concentrations) that are variable in the external environment. The main features of the weathering of a cement system open to CaO and CO2 are predicted in a phase diagram with µCaO et µCO2 as diagram axes. From core to rim, one observes the disappearance of portlandite, ettringite and calcium monosulfoaluminate, the precipitation of calcite and amorphous silica, the modification of the composition of the CSH minerals (hydrated calcium silicates) that see a decrease of their c/s ratio (CaO/SiO2) from the core to the rim of the sample. For the CSH minerals, we have separated their continuous solid solution into three compositions defined by different CaO/SiO2 ratios and called phases 1, 2 and 3: CaO = 0.8, 1.1, 1.8 respectively for one mole of SiO2 knowing that H2O varies in the three compositions.

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Partitioning of Cesium in Phases Produced by Grouted Waste Injection

MRS Proceedings ◽

10.1557/proc-26-521 ◽

1983 ◽

Vol 26 ◽

Author(s):

D. P. Stinton ◽

E. W. Mcdaniel ◽

H. O. Weerent

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Optical Microscopy ◽

X Ray Diffraction ◽

X Ray ◽

Stable Cesium ◽

The Core ◽

Calcium Silicates ◽

Hydrated Calcium ◽

Scanning Electron

ABSTRACTPhases present in injected grouts were characterized by use of optical microscopy, scanning electron microscopy, x-ray diffraction, and β-γ autoradiography. A laboratoryproduced sample containing 1 wt % stable cesium and an actual grout sheet obtained by core drilling were examined. The phases present in these samples were identified, and cesium was found to be absorbed almost entirely by illite clay agglomerates. These clay agglomerates were tightly bound within the grout structure by hydrated calcium silicates. The β-γ autoradiography of the core-drilled sample verified that cesium and other radionuclides were trapped within the 20-year-old grout and had not migrated into trapped shale fragments.

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Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

Sustainability ◽

10.3390/su13042295 ◽

2021 ◽

Vol 13 (4) ◽

pp. 2295

Author(s):

Hailong Liu ◽

Jiuye Zhao ◽

Yu Wang ◽

Nangai Yi ◽

Chunyi Cui

Keyword(s):

Soft Soil ◽

Hydration Product ◽

X Ray Diffraction ◽

Calcium Sulfoaluminate Cement ◽

Strength Performance ◽

X Ray ◽

Calcium Sulfoaluminate ◽

Stabilized Soil ◽

Calcium Silicates ◽

Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

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More on complex Sachdev-Ye-Kitaev eternal wormholes

Journal of High Energy Physics ◽

10.1007/jhep03(2021)087 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Pengfei Zhang

Keyword(s):

Black Hole ◽

Ground State ◽

Effective Action ◽

Chemical Potential ◽

Specific Charge ◽

Zero Temperature ◽

Small Coupling ◽

Chemical Potentials ◽

Quench Dynamics ◽

Two Sides

Abstract In this work, we study a generalization of the coupled Sachdev-Ye-Kitaev (SYK) model with U(1) charge conservations. The model contains two copies of the complex SYK model at different chemical potentials, coupled by a direct hopping term. In the zero-temperature and small coupling limit with small averaged chemical potential, the ground state is an eternal wormhole connecting two sides, with a specific charge Q = 0, which is equivalent to a thermofield double state. We derive the conformal Green’s functions and determine corresponding IR parameters. At higher chemical potential, the system transit into the black hole phase. We further derive the Schwarzian effective action and study its quench dynamics. Finally, we compare numerical results with the analytical predictions.

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Smart optical cross dipole nanoantenna with multibeam pattern

Scientific Reports ◽

10.1038/s41598-021-84495-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seyyed Mohammad Mehdi Moshiri ◽

Najmeh Nozhat

Keyword(s):

Radiation Pattern ◽

Chemical Potential ◽

Monolayer Graphene ◽

Absorption Characteristic ◽

Radiation Beam ◽

Directional Radiation ◽

Chemical Potentials ◽

Different Types ◽

Absorption Power ◽

Maximum Directivity

AbstractIn this paper, an optical smart multibeam cross dipole nano-antenna has been proposed by combining the absorption characteristic of graphene and applying different arrangements of directors. By introducing a cross dipole nano-antenna with two V-shaped coupled elements, the maximum directivity of 8.79 dBi has been obtained for unidirectional radiation pattern. Also, by applying various arrangements of circular sectors as director, different types of radiation pattern such as bi- and quad-directional have been attained with directivities of 8.63 and 8.42 dBi, respectively, at the wavelength of 1550 nm. The maximum absorption power of graphene can be tuned by choosing an appropriate chemical potential. Therefore, the radiation beam of the proposed multibeam cross dipole nano-antenna has been controlled dynamically by applying a monolayer graphene. By choosing a suitable chemical potential of graphene for each arm of the suggested cross dipole nano-antenna without the director, the unidirectional radiation pattern shifts ± 13° at the wavelength of 1550 nm. Also, for the multibeam nano-antenna with different arrangements of directors, the bi- and quad-directional radiation patterns have been smartly modified to uni- and bi-directional ones with the directivities of 10.1 and 9.54 dBi, respectively. It is because of the graphene performance as an absorptive or transparent element for different chemical potentials. This feature helps us to create a multipath wireless link with the capability to control the accessibility of each receiver.

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Tunable Coupled-Resonator-Induced Transparency in a Photonic Crystal System Based on a Multilayer-Insulator Graphene Stack

Materials ◽

10.3390/ma11102042 ◽

2018 ◽

Vol 11 (10) ◽

pp. 2042 ◽

Cited By ~ 1

Author(s):

Hanqing Liu ◽

Jianfeng Tan ◽

Peiguo Liu ◽

Li-an Bian ◽

Song Zha

Keyword(s):

Photonic Crystal ◽

Optical Sensors ◽

Chemical Potential ◽

Structural Parameters ◽

Multilayer Graphene ◽

Crystal System ◽

Chemical Potentials ◽

Nonlinear Devices ◽

Induced Transparency ◽

Coupled Resonator

We achieve the effective modulation of coupled-resonator-induced transparency (CRIT) in a photonic crystal system which consists of photonic crystal waveguide (PCW), defect cavities, and a multilayer graphene-insulator stack (MGIS). Simulation results show that the wavelength of transparency window can be effectively tuned through varying the chemical potential of graphene in MGIS. The peak value of the CRIT effect is closely related to the structural parameters of our proposed system. Tunable Multipeak CRIT is also realized in the four-resonator-coupled photonic crystal system by modulating the chemical potentials of MGISs in different cavity units. This system paves a novel way toward multichannel-selective filters, optical sensors, and nonlinear devices.

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Formation of hydrated calcium silicates at elevated temperatures and pressures

Journal of Research of the National Bureau of Standards ◽

10.6028/jres.021.034 ◽

1938 ◽

Vol 21 (5) ◽

pp. 617 ◽

Cited By ~ 36

Author(s):

Einar P. Flint ◽

Howard F. McMurdie ◽

Lansing S. Wells

Keyword(s):

Elevated Temperatures ◽

Calcium Silicates ◽

Hydrated Calcium

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Environmental Scanning Electron Microscopy Technique to Identify Asbestos Phases Inside Ferruginous Bodies

Microscopy and Microanalysis ◽

10.1017/s1431927612014390 ◽

2013 ◽

Vol 19 (2) ◽

pp. 420-424 ◽

Cited By ~ 5

Author(s):

Alessandro Croce ◽

Maya Musa ◽

Mario Allegrina ◽

Paolo Trivero ◽

Caterina Rinaudo

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Chemical Elements ◽

Environmental Scanning Electron Microscopy ◽

Environmental Scanning ◽

Thin Sections ◽

The Core ◽

Microscopy Technique ◽

Ferruginous Bodies ◽

Scanning Electron

AbstractFerruginous bodies observed in lungs of patients affected by mesothelioma, asbestosis, and pulmonary carcinoma are important to relate the illness to exposure, environmental or occupational, to asbestos. Identification of the inorganic phase constituting the core of the ferruginous bodies, formed around asbestos but also around phases different from asbestos, is essential for legal purposes. Environmental scanning electron microscopy/energy dispersive spectroscopy was used to identify the fibrous mineral phase in the core of ferruginous bodies observed directly in thin sections of tissue, without digestion of the biological matrix. Spectra were taken with sequential analyses along a line crossing the core of the ferruginous bodies. By comparing the spectra taken near to and far from the core, the chemical elements that make up the core could be identified.

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Temperature and equilibrium

Statistical Mechanics: Entropy, Order Parameters, and Complexity ◽

10.1093/oso/9780198865247.003.0003 ◽

2021 ◽

pp. 49-78

Author(s):

James P. Sethna

Keyword(s):

Statistical Mechanics ◽

Chemical Potential ◽

Density Fluctuations ◽

High Dimensional ◽

High Dimensions ◽

Chemical Potentials ◽

The World ◽

Particle Velocities ◽

The Cost ◽

Taste And Smell

Statistical mechanics explains the comprehensible behavior of microscopically complex systems by using the weird geometry of high-dimensional spaces, and by relying only on the known conserved quantity: the energy. Particle velocities and density fluctuations are determined by the geometry of spheres and cubes in dimensions with twenty three digits. Temperature, pressure, and chemical potential are defined and derived in terms of the volume of the high-dimensional energy shell, as quantified by the entropy. In particular, temperature is the inverse of the cost of buying energy from the rest of the world, and entropy is the currency being paid. Exercises discuss the weird geometry of high dimensions, how taste and smell measure chemical potentials, equilibrium fluctuations, and classic thermodynamic relations.

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“Fast” Plasmons Propagating in Graphene Plasmonic Waveguides with Negative Index Metamaterial Claddings

Nanomaterials ◽

10.3390/nano10091637 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1637

Author(s):

Zeyang Zhao ◽

Shaojian Su ◽

Hengjie Zhou ◽

Weibin Qiu ◽

Pingping Qiu ◽

...

Keyword(s):

Group Velocity ◽

Integrated Circuit ◽

Negative Refraction ◽

Chemical Potential ◽

Refraction Index ◽

Monolayer Graphene ◽

Plasmonic Waveguides ◽

Chemical Potential Difference ◽

Positive Group ◽

The Core

We propose the monolayer graphene plasmonic waveguide (MGPW), which is composed of graphene core sandwiched by two graphene metamaterial (GMM) claddings and investigate the properties of plasmonic modes propagating in the waveguide. The effective refraction index of the GMMs claddings takes negative (or positive) at the vicinity of the Dirac-like point in the band structure. We show that when the effective refraction index of the GMMs is positive, the plasmons travel forward in the MGPW with a positive group velocity (vg > 0, vp > 0). In contrast—for the negative refraction index GMM claddings—a negative group velocity of the fundamental mode (vg < 0, vp > 0) appears in the proposed waveguide structure when the core is sufficiently narrow. A forbidden band appears between the negative and positive group velocity regions, which is enhanced gradually as the width of the core increases. On the other hand, one can overcome this limitation and even make the forbidden band disappear by increasing the chemical potential difference between the nanodisks and the ambient graphene of the GMM claddings. The proposed structure offers a novel scheme of on-chip electromagnetic field and may find significant applications in the future high density plasmonic integrated circuit technique.

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