Sulfur Lines Research Articles

Updated System of S i Levels Using Fourier Transform Infrared Spectroscopy in the Range from 800 to 11,000 cm−1

In this study we report on high-precision laboratory measurements of transition wavenumbers for 172 atomic sulfur lines in the infrared region 800–11,000 cm−1 using Fourier transform spectroscopy techniques. Our analysis includes 96 lines that have not been previously measured in the laboratory. We also correct several sulfur energy-level measurements reported in earlier studies. These refined measurements are important for a range of scientific disciplines, such as astrophysics, atmospheric chemistry, and combustion plasma physics. We have used the combined list of all observed lines to derive a refined set of sulfur energy levels. For about half of all nonautoionizing levels, the uncertainties have been reduced by a factor between 2 and 23. From the newly measured nonpenetrating (high-l) Rydberg levels we have also obtained the first ionization energy of the S atom, IE = 83,559.170(11) cm−1, which is more accurate than the currently recommended value by 2 orders of magnitude. Our analysis has led to a significantly more accurate result than the earlier set of Ritz wavelengths with observed intensities reduced to a common uniform scale and an extended list of recommended transition probabilities.

Theoretical Strong-line Metallicity Diagnostics for the JWST Era

The ratios of strong rest-frame optical emission lines are the dominant indicators of metallicities in high-redshift galaxies. Since typical strong-line-based metallicity indicators are calibrated on auroral lines at z = 0, their applicability for galaxies in the distant Universe is unclear. In this paper, we make use of mock emission-line data from cosmological simulations to investigate the calibration of rest-frame optical emission lines as metallicity indicators at high redshift. Our model, which couples the simba cosmological galaxy formation simulation with cloudy photoionization calculations, includes contributions from H ii regions, post-asymptotic-giant-branch stars, and diffuse ionized gas (DIG). We find mild redshift evolution in the 12 indicators that we study, which implies that the dominant physical properties that evolve in our simulations do have a discernible impact on the metallicity calibrations at high redshifts. When comparing our calibrations with high-redshift auroral line observations from the James Webb Space Telescope, we find a slight offset between our model results and the observations and find that a higher ionization parameter at high redshifts can be one of the possible explanations. We explore the physics that drives the shapes of strong-line metallicity relationships and propose calibrations for hitherto unexplored low-metallicity regimes. Finally, we study the contribution of DIG to total line fluxes. We find that the contribution of DIG increases with metallicity at z ∼ 0 for singly ionized oxygen and sulfur lines and can be as high as 70%, making it crucial to include their contribution when modeling nebular emission.

A conclusive non-detection of magnetic field in the Am star o Peg with high-precision near-infrared spectroscopy

The A-type metallic-line (Am) stars are typically considered to be non-magnetic or to possess very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature; most commonly for the bright hot Am star Several studies claim to have detected 1--2 kG field of unknown topology in this object, possibly indicating a new process of magnetic-field generation in intermediate-mass stars. In this study, we revisit the evidence of a strong magnetic field in using new high-resolution spectropolarimetric observations and advanced spectral fitting techniques. We estimated the mean magnetic field strength in from the high-precision CRyogenic InfraRed Echelle Spectrograph $) measurement of near-infrared (NIR) sulphur lines. We modelled this observation with a polarised radiative transfer code, including treatment of the departures from local thermodynamic equilibrium. In addition, we used the least-squares deconvolution multi-line technique to derive longitudinal field measurements from archival optical spectropolarimetric observations of this star. Our analysis of the NIR S i lines reveals no evidence of Zeeman broadening, ruling out magnetic field with a strength exceeding 260 G. This null result is compatible with the relative intensification of Fe ii lines in the optical spectrum, taking into account blending and uncertain atomic parameters of the relevant diagnostic transitions. Longitudinal field measurements on three different nights also yield null results with a precision of 2 G. This study refutes the claims of kG-strength dipolar or tangled magnetic field in This star therefore appears to be non-magnetic, with surface magnetic field characteristics no different from those of other Am stars.

EMPRESS. XIV. Strong High-ionization Lines of Young Galaxies at z = 0–8: Ionizing Spectra Consistent with the Intermediate-mass Black Holes with M BH ∼ 103–106 M ⊙

We present ionizing spectra estimated at 13.6–100 eV for 10 dwarf galaxies with strong high-ionization lines of He ii λ4686 and [Ne v] λ3426 ([Ne iv] λ2424) at z = 0 (z = 8) that are identified in our Keck/LRIS spectroscopy and the literature (the JWST Early Release Observations program). With the flux ratios of these high-ionization lines and >10 low-ionization lines of hydrogen, helium, oxygen, neon, and sulfur, we determine ionizing spectra consisting of stellar and nonthermal power-law radiation by photoionization modeling with free parameters of nebular properties, including metallicity and ionization parameter, canceling out abundance ratio differences. We find that all of the observed flux ratios are well reproduced by the photoionization models with the power-law index α EUV of α EUV ∼ (–1) − 0 and the luminosity L EUV of L EUV ∼ 1040–1042 erg s−1 at ∼55–100 eV for six galaxies, while four galaxies include large systematics in α EUV caused by stellar radiation contamination. We then compare α EUV and L EUV of these six galaxies with those predicted by the black hole (BH) accretion disk models and find that α EUV and L EUV are similar to those of the intermediate-mass BHs (IMBHs) in BH accretion disk models, albeit with possibilities of the other scenarios. Confirming these results with a known IMBH having a mass M BH of M BH = 105.75 M ⊙, we find that four local galaxies and one z = 7.665 galaxy have ionizing spectra consistent with those of IMBHs with M BH ∼ 103–105 M ⊙.

Chemical abundances and deviations from the solar S/O ratio in the gas-phase interstellar medium of galaxies based on infrared emission lines

Context. The infrared (IR) range is extremely useful in the context of chemical abundance studies of the gas-phase interstellar medium (ISM) due to the large variety of ionic species traced in this regime, the negligible effects from dust attenuation or temperature stratification, and the amount of data that has been and will be released in the coming years. Aims. Taking advantage of available IR emission lines, we analysed the chemical content of the gas-phase ISM in a sample of 131 star-forming galaxies (SFGs) and 73 active galactic nuclei (AGNs). In particular, we derived the chemical content via their total oxygen abundance in combination with nitrogen and sulphur abundances, and with the ionisation parameter. Methods. We used a new version of the code HII-CHI-MISTRY-IR v3.1, which allowed us to estimate log(N/O), 12+log(O/H), log(U) and, for the first time, 12+log(S/H) from IR emission lines, which can be applied to both SFGs and AGNs. We tested whether the estimates from this new version, which only considers sulphur lines for the derivation of sulphur abundances, are compatible with previous studies. Results. While most of the SFGs and AGNs show solar log(N/O) abundances, we find a large spread in the log(S/O) relative abundances. Specifically, we find extremely low log(S/O) values (1/10 solar) in some SFGs and AGNs with solar-like oxygen abundances. This result warns against the use of optical and IR sulphur emission lines to estimate oxygen abundances when no prior estimation of log(S/O) is provided.

Conversion of an industrial LIBS system to double-pulse operation to improve sulphur detection in rubber-based parts

The detection of sulphur as an elementary component of the crosslinking system of rubber compounds is difficult in LIBS single-pulse operation due to the usually low concentration and the poor response behavior of the analyte. However, reliable proof of the distribution quality of sulphur in the compound is a decisive quality criterion for the homogeneity of the crosslinking density achievable during vulcanization, which is important for the uniform performance of an elastomeric article, especially under dynamic load.Therefore a commercially available industrial LIBS system, (1064 nm Nd:YAG solid state laser, 100 mJ, 20 Hz) is extended with a 266 nm laser (Nd:YAG solid state laser, 60 mJ, 20 Hz) to combine an UV-based initial excitation (for ablation efficiency) followed by an IR-pulse (to realize highest plasma heating) to improve sulphur detection in rubber based compounds and parts. Optimization of the system parameters are investigated to improve the ablation efficiency and to increase the measured signal intensity/signal-to-noise-ratio of the analyte. The VUV sulphur lines at 180.658, 181.956, and 182.561 nm and the NIR sulphur lines at 921.298, 922.823, and 923.751 nm are under investigation.

Emission lines due to ionizing radiation from a compact object in the remnant of Supernova 1987A.

The nearby Supernova 1987A was accompanied by a burst of neutrino emission, which indicates that a compact object (a neutron star or black hole) was formed in the explosion. There has been no direct observation of this compact object. In this work, we observe the supernova remnant with JWST spectroscopy, finding narrow infrared emission lines of argon and sulfur. The line emission is spatially unresolved and blueshifted in velocity relative to the supernova rest frame. We interpret the lines as gas illuminated by a source of ionizing photons located close to the center of the expanding ejecta. Photoionization models show that the line ratios are consistent with ionization by a cooling neutron star or a pulsar wind nebula. The velocity shift could be evidence for a neutron star natal kick.

Graphene-Based Electrochemical Sensing Platform for Rapid and Selective Ferulic Acid Quantification

Due to the multitude of physiological functions, ferulic acid (FA) has a wide range of applications in the food, cosmetic, and pharmaceutical industries. Thus, the development of rapid, sensitive, and selective detection tools for its assay is of great interest. This study reports a new electroanalytical approach for the quantification of ferulic acid in commercial pharmaceutical samples using a sulphur-doped graphene-based electrochemical sensing platform. The few-layer graphene material (exf-SGR) was prepared by the electrochemical oxidation of graphite, at a low applied bias (5 V), in an inorganic salt mixture of Na2S2O3/(NH4)2SO4 (0.3 M each). According to the morpho-structural characterization of the material, it appears to have a high heteroatom doping degree, as proved by the presence of sulphur lines in the XRD pattern, and the C/S ratio was determined by XPS investigations to be 11.57. The electrochemical performances of a glassy carbon electrode modified with the exf-SGR toward FA detection were tested by cyclic voltammetry in both standard laboratory solutions and real sample analysis. The developed modified electrode showed a low limit of detection (30.3 nM) and excellent stability and reproducibility, proving its potential applicability as a viable solution in FA qualitative and quantitative analysis.

Sulfur‐Tuned Advanced Carbons of Novel Properties and Scalable Productivity

AbstractSulfur‐tuned advanced carbons (STACs) with high mass loadings of sulfur are synthesized using an environmentally benign and scalable steam‐assisted sulfur insertion (SASI) method. While steam provides the pressure necessary to promote deep and rapid sulfur insertion into a carbon porous structure, a strong affinity between melted sulfur and carbon excludes water from pore penetration. The resulting STACs exhibit sulfur mass loadings up to 85% and the electrical conductivity of the carbon framework is largely preserved. The sulfur penetration can be tuned to fill specific pore sizes, enabling pore‐size‐dependent allocation of sulfur and controllable porosity, while sulfur lines the carbon pore surfaces. A significant amount of sulfur is in the monoclinic γ phase. To demonstrate their energy and environmental applications, the STACs are used as cathode materials in rechargeable aluminum‐sulfur batteries and as adsorption materials for spilled oil removal.

3D printed cortical bone mimic-material for medical physics

Treatment and diagnosis in Nuclear Medicine and Radiotherapy require simulators able to mimic the human body to pre-assess the radiation behavior of new techniques and radiopharmaceuticals. Development of such simulators requires materials to behave similarly to the body tissues and with more real shapes to obtain more reliable results. XCT-A and XCT-B are new 3D printing materials that simulate cortical bone behavior. CT results confirm bone-like attenuation. X-ray fluorescence reveals the preeminent presence of Barium, Calcium, and Sulfur, and Raman spectral lines are similar to ABS material.

How transient effects can change the inferred plasma temperatures when using K-shell sulfur line ratios in a time dependent iron sulfide plasma

This paper describes how the steady state atomic kinetics approximation can underestimate the electron temperature determined from K-shell lines in ps-time-scale transient plasmas. In particular, we model the temperature determination of solid FeS targets used in opacity experiments at the Orion laser facility from the ratio of sulfur He-α to Ly-α lines. Such experiments use short-pulse lasers to heat a thin microdot of FeS buried in a plastic target to temperatures of more than 1 keV and densities of approximately 1–2 g/cm3. Using atomic kinetics calculations based on a temperature history from a radiation hydrodynamic simulation of the target evolution, the peak temperature inferred from the sulfur line ratios is 1.29 keV at 3.1 ps as compared with the input peak temperature of 1.41 keV at 2.0 ps. There is a time lag of 1.2 ps at the peak, and an overall 0.5 ps time lag in the temporal history of the temperature as the plasma cools over the next 10 ps.

Sulfur Line Vacancies in MoS2 for Catalytic Hydrogen Evolution Reaction

Defects in transition metal dichalcogenides play important roles in the field of the catalytic hydrogen evolution reaction (HER). However, the use of defective MoS2 as HER catalysts remains controversial because the types of defects are various, including zero-dimensional point defects, one-dimensional linear defects, and two-dimensional plane defects. Recently, novel structures of linear defects have drawn more and more attention, and it is necessary to explore their unique properties. This review focuses on the formation mechanism, fabrication method, accurate atomic structure, and catalytic hydrogen evolution mechanism of sulfur line vacancies in MoS2 as electrocatalysts. The structure–activity relationship between line defects and catalytic performance is discussed in detail. This will provide a route for the design of excellent catalysts by engineering line defects.

Chemical Composition and Toxicity of PM10 and PM0.1 Samples near Open-Pit Mines and Coal Power Stations.

Particulate matter (PM) <10 μm in size represents an extremely heterogeneous and variable group of objects that can penetrate the human respiratory tract. The present study aimed to isolate samples of coarse and ultrafine PM at some distance from polluting industries (1–1.5 km from the border of open-cast mines). PM was collected from snow samples which allowed the accumulation of a relatively large amount of ultrafine particles (UFPs) (50–60 mg) from five objects: three open-cast mines, coal power plants, and control territories. The chemical composition of PM was examined using absorption spectroscopy, luminescence spectroscopy, high-performance liquid chromatography, X-ray diffraction (XRD), and X-ray fluorescence (XRF) analyses of solid particle material samples. Toxicity was assessed in human MRC-5 lung fibroblasts after 6 h of in vitro exposure to PM samples. The absorption spectra of all the samples contained a wide non-elementary absorption band with a maximum of 270 nm. This band is usually associated with the absorption of dissolved organic matter (DOM). The X-ray fluorescence spectra of all the studied samples showed intense lines of calcium and potassium and less intense lines of silicon, sulfur, chlorine, and titanium. The proliferation of MRC-5 cells that were exposed to PM0.1 samples was significantly (p < 0.01) lower than that of MRC-5 cells exposed to PM10 at the same concentration, except for PM samples obtained from the control point. PM0.1 samples—even those that were collected from control territories—showed increased genotoxicity (micronucleus, ‰) compared to PM10. The study findings suggest that UFPs deserve special attention as a biological agent, distinct from larger PMs.

In-situ detection of sulfur in the atmosphere via laser-induced breakdown spectroscopy and single particle aerosol mass spectrometry technology

The combustion of sulfur-containing minerals is one of the primary causes of various atmospheric and water pollution issues, including sulfuric acid rain. Considering that sulfur is particularly susceptible to oxidation in the air, the direct detection of sulfur via laser-induced breakdown spectroscopy (LIBS) has presented a major challenge. In this work, CS2 was used as a sample evaporated and atomized into the air. A new experimental device that combines the LIBS system with the single particle aerosol mass spectrometry (SPAMS) system was adopted for the direct detection of sulfur in the atmosphere. Under the optimal experimental conditions, the characteristic spectral lines of sulfur were observed and recorded in the LIBS spectra. Additionally, in the LIBS spectrum, CN molecular bands were observed, and the vibration and rotation temperature of the CN molecules in the experiment were obtained through software simulation. While the SPAMS system generates the real-time composition of a single CS2 aerosol particle, the isotope information of sulfur can also be distinguished simultaneously. Sulfur isotopes are widely used as tracers in chemistry, agricultural science, and environmental science research. Finally, the LIBS and SPAMS experiment systems can perform the direct in-situ detection of sulfur in the air and provide its isotope information.

Atomic emission detector with gas chromatographic separation and cryogenic pre-concentration (CryoTrap–GC–AED) for atmospheric trace gas measurements

Abstract. A gas detection system has been developed, characterized, and deployed for pressurized gas-phase sample analyses and near-real-time online measurements. It consists of a cryogenic pre-concentrator (CryoTrap), a gas chromatograph (GC), and a new high-resolution atomic emission detector (AED III HR). Here the CryoTrap–GC–AED instrumental setup is presented, and the performance for iodine (1635 ± 135 counts I atom−1 pptv−1), sulfur (409 ± 57 counts S atom−1 pptv−1), carbon (636 ± 69 counts C atom−1 pptv−1), bromine (9.1 ± 1.8 counts Br atom−1 pptv−1), and nitrogen (28 ± 2 counts N atom−1 pptv−1) emission lines is reported and discussed. The limits of detection (LODs) are in the low parts per trillion by volume range (0.5–9.7 pptv), and the signal is linear to at least 4 orders of magnitude, which makes it a suitable method for diverse volatile organic compound (VOC) measurements in the atmosphere, even in remote unpolluted regions. The new system was utilized in a field study in a boreal forest at Hyytiälä, Finland, in late summer 2016, which made monoterpene measurements possible among other VOCs. Furthermore, pressurized global whole-air samples, collected on board the Lufthansa Airbus A340-600 IAGOS–CARIBIC aircraft in the upper troposphere and lower stratosphere region, were measured with the new setup, providing data for many VOCs, including the long-lived organosulfur compound carbonyl sulfide.

Reconciling escape fractions and observed line emission in Lyman-continuum-leaking galaxies

Context. Finding and elucidating the properties of Lyman-continuum(LyC)-emitting galaxies is an important step in improving our understanding of cosmic reionization. Aims. Although the z ∼ 0.3 − 0.4 LyC emitters found recently show strong optical emission lines, no consistent quantitative photoionization model taking into account the escape of ionizing photons and inhomogenous interstellar medium (ISM) geometry of these galaxies has yet been constructed. Furthermore, it is unclear to what extent these emission lines can be used to distinguish LyC emitters. Methods. To address these questions we construct one- and two-zone photoionization models accounting for the observed LyC escape, which we compare to the observed emission line measurements. The main diagnostics used include lines of [O III], [O II], and [O I] plus sulfur lines ([S II], [S III]) and a nitrogen line ([N II]), which probe regions of different ionization in the ISM. Results. We find that single (one-zone) density-bounded photoionization models cannot reproduce the emission lines of the LyC leakers, as pointed out by earlier studies, because they systematically underpredict the lines of species of low ionization potential, such as [O I] and [S II]. Introducing a two-zone model, with differing ionization parameter and a variable covering fraction and where one of the zones is density-bounded, we show that the observed emission line ratios of the LyC emitters are well reproduced. Furthermore, our model yields LyC escape fractions, which are in fair agreement with the observations and independent measurements. The [O I] λ6300 excess, which is observed in some LyC leakers, can be naturally explained in this model, for example by emission from low-ionization and low-filling-factor gas. LyC emitters with a high escape fraction (fesc ≳ 38%) are deficient both in [O I] λ6300 and in [S II] λλ6716,6731. We also confirm that a [S II] λλ6716,6731 deficiency can be used to select LyC emitter candidates, as suggested earlier. Finally, we find indications for a possible dichotomy in terms of escape mechanisms for LyC photons between galaxies with relatively low (fesc ≲ 10%) and higher escape fractions. Conclusions. We conclude that two-zone photoionization models are sufficient and required to explain the observed emission line properties of z ∼ 0.3 − 0.4 LyC emitters. This is in agreement with UV absorption line studies, which also show the co-existence of regions with high hydrogen column density (i.e., no escape of ionizing photons) and density-bounded or very low column density regions responsible for the observed escape of LyC radiation. These simple but consistent models provide a first step towards the use of optical emission lines and their ratios as quantitative diagnostics of LyC escape from galaxies.

Effects of sulfur line vacancy defects on the electronic and optical properties of armchair MoS2 nanoribbon

Abstract Based on the density functional theory (DFT) calculations, we study the electronic and optical properties of armchair MoS2 nanoribbons (AMoS2NR) with single and double sulfur line vacancy defects in two different directions, i.e. parallel to the length (longitudinal) and width (transversal) of the structure. The formation energy calculations show that the structures with longitudinal vacancies are easier to create than the transversal ones. Investigating the band structures, it is observed that all the line defects proposed in this study decrease the band gap of the AMoS2NR. In fact, the band gap of 0.68 eV in perfect nanoribbon reduces to the lowest value of 0.11 eV in transversal double vacancy structure (T-DV). Analysis of the total and projected density of states (TDOS and PDOS) of the perfect and proposed defective structures indicates that in the defective structures the contribution of central atoms becomes more dominant especially in the case of the T-DV structure which has the most number of non-terminated bonds. In order to investigate the optical properties of the perfect and defective AMoS2NR, we present the real and imaginary parts of dielectric function, absorption coefficient and reflectance spectra for two different polarizations of light, along and perpendicular to the nanoribbon. The results show that all the structures in this study are anisotropic with respect to the type of polarization in the energies below 12 eV and are isotropic above it. It is also depicted that the light polarized along the nanoribbon has higher absorption in the energies below 3 eV. In addition, we show that the proposed line defects cause redshifts in the first peaks of the optical spectra which provides a tunable optical characteristic that can extend the application of AMoS2NR in a wide frequency range especially IR and visible.

Spectral analysis of UV-spectrum elements in steel using portable optical emission spectrometers

Optical emission spectroscopy is used to determine the mass fraction of elements such as carbon, silicon, manganese, phosphorus, sulfur, chromium, nickel, copper, aluminum, molybdenum, vanadium, titanium, arsenic, tin, boron, calcium, etc. Most of the analytical lines of the analyzed elements are located in the visible light spectrum, but the analytical lines of carbon, phosphorus and sulfur are located in the ultraviolet radiation spectrum.Ultraviolet radiation (UV radiation) is electromagnetic radiation that occupies the spectral range between visible and x ray radiation. The wavelengths of UV radiation are in the range from 10 to 400 nm. The area of UV radiation is divided into: near from 400 to 200 nm; far from 380 to 200 nm; vacuum from 200 to 10 nm.Structural particularities of the structure of the optical system of stationary spectrometers allow determining the mass fraction of chemical elements, including phosphorus and sulfur, with sufficient accuracy and reliability. This article discusses the possibility of determining the mass fractions of phosphorus and sulfur, the analytical lines of which lie in the area of ultraviolet radiation, using portable optical emission spectrometers.

Theoretical ISM Pressure and Electron Density Diagnostics for Local and High-redshift Galaxies

Abstract We derive new self-consistent theoretical UV, optical, and IR diagnostics for the interstellar medium (ISM) pressure and electron density in the ionized nebulae of star-forming galaxies. Our UV diagnostics utilize the intercombination, forbidden, and resonance lines of silicon, carbon, aluminum, neon, and nitrogen. We also calibrate the optical and IR forbidden lines of oxygen, argon, nitrogen, and sulfur. We show that line ratios used as ISM pressure diagnostics depend on the gas-phase metallicity with a residual dependence on the ionization parameter of the gas. In addition, the traditional electron density diagnostic [S ii] λ6731/[S ii] λ6717 is strongly dependent on the gas-phase metallicity. We show how different emission-line ratios are produced in different ionization zones in our theoretical nebulae. The [S ii] and [O ii] ratios are produced in different zones and should not be used interchangeably to measure the electron density of the gas unless the electron temperature is known to be constant. We review the temperature and density distributions observed within H ii regions and discuss the implications of these distributions on measuring the electron density of the gas. Many H ii regions contain radial variations in density. We suggest that the ISM pressure is a more meaningful quantity to measure in H ii regions or galaxies. Specific combinations of line ratios can cover the full range of ISM pressures (4 &lt; log(P/k) &lt; 9). As H ii regions become resolved at increasingly high redshift through the next generation of telescopes, we anticipate that these diagnostics will be important for understanding the conditions around the young, hot stars from the early universe to the present day.

DETERIORATION OF CONCRETE SULFUR STORAGE TANK UNDER ACIDIC VAPOR ATTACK

Sulfur storage tanks are integral parts of refineries and gas plants. During the gas sweetening process, liquid sulfur is separated in the sulfur recovery units and is stored in underground reinforced concrete tanks in liquid phase by steam-generated temperatures of 315 °F. Roof of the sulfur pit is about 300 – 400 mm thick reinforced concrete structure with two layers of reinforcement. Inside the sulfur pit, the ceiling and walls are subjected to high temperatures and highly corrosive acidic vapors above liquid sulfur line which leads to severe deterioration of concrete and corrosion of reinforcement in the roof slab. This paper presents the NDT based investigations of the roof slab of the tank using the Ground Penetrating Radar (GPR) in a typical sulfur pit with 30 years in service. GPR survey is compared with ultrasonic pulse echo and half-cell potential measurements on the slab. Compressive strength and petrographic examination of selected concrete cores and SEM/EDS and XRD tests on powder samples, from inside the pit are presented.