Intensity Of Absorption Peak Research Articles

Effect of SWEEPS and PIPS techniques on dye extrusion in photodynamic therapy procedure after root canal preparation

AimThe aim of this study is to measure and compare the amount of apical extrusion of the methylene blue as photosensitizer using Laser-activated irrigation(LAI) techniques (SWEEPS, PIPS) and photodynamic therapy (PDT). Materials and methods40 single-rooted premolar teeth were selected and their root canals were cleaned and prepared. The photosensitizer, Methylene blue (MB), was used as dye which applied inside the root canals and the access cavities. Then the teeth were randomly allocated to 4 groups. Different techniques (SWEEPS, PIPS, PDT) were used in 3 groups. One group received no activation. Data related to the concentration of the extruded methylene blue was measured using ultraviolet and visible (UV–Vis) absorption spectroscopy. Absorption peak intensity of MB in the wavelength of 668 nm was considered as the concentration index according to Beer Lambert law. Taking into account the normal distribution of this data, one-way ANOVA analysis was used to evaluate the effects of the independent variables on the amount of apical extrusion of the irrigant. ResultsBased on the results of ANOVA analysis, there was no significant difference between the amounts of apical extrusion of MB between different groups (p = 0.628) ConclusionUsing SWEEPS and PIPS techniques, despite diffusion of the photosensitizer, didn't lead to any difference in the amount of apical extrusion. Therefore, these LAI techniques can be used safely for root canal irrigation.

Energy spectrum and light absorption of arsenene quantum dots

As a close relative of phosphorene, puckered arsenene is stable and has been demonstrated experimentally as a promising two-dimensional semiconductor material. By means of a multi-orbital tight-binding model, we investigate theoretically the energy spectrum and magneto-optical properties of circular and rectangular arsenene quantum dots (AQDs). The tight-binding parameters are obtained by reproducing accurately the electron energy bands of puckered arsenene from the first-principle calculation. For both AQDs, the density of states (DOS), probability distribution and inverse participation ratio (IPR) of eigenstates, and optical absorption spectrum are calculated numerically. It is found that edge states of AQDs fill up the bulk band gap of puckered arsenene and are only localized near the armchair edges of AQDs. These features differ greatly from those in quantum dots made of graphene or phosphorene. The band edges of arsenene monolayer can be located roughly from the IPR and DOS spectrum. The light absorptivity of both AQDs under zero magnetic field depends strongly on the polarization direction of incident light. The position and intensity of absorption peaks can be tuned by the shape of quantum dots and the applied magnetic field. The anisotropy ratio of light absorption can be reduced by one order of magnitude under a magnetic field of tens of Tesla.

Influence and mechanism of the vertical distribution of Cu, Cd, and Pbat a simulated sediment-water interface covered by degradable microplastics.

Currently research on microplastics in the environment focuses on non-degradable microplastics with little attention to research on degradable microplastics. This study involved a 400-day experiment in a simulated lake environment of three degradable microplastics, poly(ε-caprolactone) (PCL), polybutylene succinate (PBS), and poly(butylene adipate terephthalate) (PBAT) at the sediment water interface. Results showed that (1) for the three microplastics, Cd concentration showed a large change from 0 to 20mm in the water above the sediment interface; the adsorption of Cd, Pb, and Cu in a diffusive gradients thin film (DGT) device are the highest in PBAT micro plastic, followed by PCL and then PBS. (2) Diffuse flux (J) of the three degradable microplastics indicated that Cu, Cd, and Pb in the sediments come from the overlying water that was added to the simulation experiment. (3) Fourier transform infra-red spectroscopy (FTIR) for investigating the adsorption capacity of Cu, Cd, and Pb in the three degradable microplastics showed the absorption peak intensity increased and widened, and some adsorption sites changed. (4) Correlation analysis showed that the factors which most influenced diffusion flux for both water and sediments are oxidation-reduction potential (ORP), followed by organic matter (OM), pH, and electrical conductivity (EC).

Review on Performance of Asphalt and Asphalt Mixture with Waste Cooking Oil

To make full use of the regenerative value of waste cooking oil, and to solve the environmental pollution and food security issues caused by waste cooking oil, waste cooking oil was suggested for use in asphalt. Waste cooking oil was used to adjust the performance of virgin and aged asphalt. This review article summarizes research progress on the performance of asphalt and asphalt mixture with waste cooking oil. The results showed that a moderate dosage of waste cooking oil will improved the low-temperature performance and construction workability of petroleum asphalt and aged asphalt. The mixing and compaction temperature of asphalt mixture with waste cooking oil are reduced by up to 15 °C. The rutting resistance and fatigue resistance of modified asphalt and modified asphalt mixture with waste cooking oil are damaged. After the addition of waste cooking oil in aged asphalt, the high-temperature performance and shear rheologic property of aged asphalt will be recovered. The regeneration effect of waste cooking oil on aged asphalt and aged asphalt mixture is close to that of a traditional regeneration agent, and the partial performance of asphalt or asphalt mixture with waste cooking oil is better. There is no chemical reaction between waste cooking oil and asphalt, but the asphalt component and absorption peak intensity of partial functional groups are changed. The light components content of asphalt binder is usually increased. Further research regarding the engineering application of asphalt mixture with waste cooking oil should be conducted. The method for improving the performance of asphalt and asphalt mixture with waste cooking oil will be mainly researched.

Enhanced photocatalytic degradation of 4-nitrophenol using polyacrylamide assisted Ce-doped YMnO3 nanoparticles

This research article mainly reports on the precise structural, optical, and photocatalytic properties of cerium (Ce)-substituted yttrium manganite (YMnO3) nanoparticles synthesized by the polyacrylamide gel method. The characteristics of YMnO3 were investigated by the substitution of Ce into the Y site at various molar percentages. The Raman and X-ray diffraction (XRD) analyses confirmed the pure phase of hexagonal YMnO3, supported by the Rietveld refinement. The microstructural studies indicate inhomogeneous and irregular particle distribution. The X-ray photoelectron spectroscopy (XPS) results show the presence of two ionic states of Mn and Ce along with Y3+ state and oxygen vacancies. Extensive optical exploration using photoluminescence (PL) spectroscopy and UV–Vis–NIR analysis indicates that the intensity of absorption peak increases in the visible region, while the bandgap decreases from 1.42 to 1.30 eV with the Ce ion doping (5 mol%–15 mol%). Photocatalytic properties of the polycrystalline nanoparticles were investigated by degradation of the pollutant 4-nitrophenol. The process of amplified photocatalysis process was elucidated by the lowered bandgap and rate of charge carrier recombination. It can be conjugated from this study that the synthesized nanoparticles may be employed as highly efficient (92.8%) visible light-triggered photocatalysts in a variety of real-world applications.

Effects of different rapid cooling temperatures and annealing on functional properties of starch straws after thermoplastic extrusion

To improve the performance of starch straws in rapidly cooling and annealing procedure of thermoplastic extrusion, control straw was prepared through slowly cooling at 25 °C, and starch straw was prepared through regulating different rapid cooling temperatures including 20 °C, 5 °C, −10 °C and −20 °C. The results indicated that control straw exhibited a homogeneous state, while starch straws treated by rapid cooling displayed like a wash-board structure. Compared to control straw, the ratio of the absorption peak intensity of 1047 and 1022 cm−1 increased from 1.050 to 1.455 as cooling temperatures decreased from 25 °C to −20 °C, indicating short-range order of the double helix structure significantly enhanced. The relative crystallinities of starch straws increased from 12.01 % to 16.58 %. The maximum bending force value (60.92 N) of starch straws cooled at −20 °C was significantly higher than that (46.14 N) of control straw. Conversely, the modulus of elasticity in bending values (4.21–16.43 N/cm) of rapid cooling-treated straws were significantly lower than that (48.42 N/cm) of control straw. Water absorption of rapid cooling-treated straws were lower than that of control straw, indicating the hydrophobicity property of starch straws significantly improved.

Theoretical investigation on the functional group modulation of UV-Vis absorption profiles of triphenylamine derivatives.

Understanding the functional group modulation of electronic structure and excitation is pivotal to the design of organic small molecules (OSMs) for photoelectric applications. In this study, we employed density functional theory (DFT) and time-dependent DFT (TDDFT) calculations to explore the unique absorption character of four triphenylamine photosensitizers. The various conformations were investigated given the multiple single bonds in the compounds, and the resemblance in the electronic structure of different conformations is affirmed because the coplanarity and consequent long-range conjugation is maintained regardless of the orientation of the flexible blocks. Six functionals were evaluated, and MN15 was found to successfully reproduce the intense secondary absorption peak for the double 3,4-ethylenedioxythiophene (EDOT) modified sensitizer over B3LYP, PBE0, M062X, CAM-B3LYP, and ωB97XD. The introduction of EDOT gives rise to a new excited state S4, which is a local excitation constrained in the EDOT substituent triphenylamine block. This new excited state S4, in combination with inherent S2 and S3 derived from prototype molecule TPA-Pyc, jointly contributes to the hump of the secondary absorption peak of ETE-Pyc and finally affects the light-harvesting ability of the dye-sensitized TiO2 photoanode. The current findings provide guidance toward the rational design of OSMs with good light-harvest ability.

In situ Ga K-edge XANES study of Ga-exchanged zeolites at high temperatures under different atmospheres including vacuum, CO, and pressurized H2

In situ Ga K-edge XANES analysis of Ga-exchanged zeolite was performed under actual operating temperatures and different atmospheres. The main absorption peak intensity was responsible for the presence or absence of a hydride source in the gas phase.

Graphene-Au nanosphere composite arrays and their enhanced SERS performance

The effective regulation of the absorption properties of Au nanosphere arrays, as well as effective enhancement of its SERS performance, are of great significance for its applications in the field of optical sensing. In this paper, the polyol synthesis method was used to fabricate monolayer and bilayer periodic Au nanosphere arrays, onto which monolayer graphene was coated, and the optical properties of the obtained composite structures were investigated. The results showed that the coverage of graphene enhances the absorption peak intensities of the monolayer and bilayer Au nanoarrays by up to 32.92%, and the resonance peaks were red-shifted by up to 17 nm. The Raman signals of graphene-covered monolayer and bilayer Au nanosphere composite arrays are 180 and 280 times stronger than that of pristine graphene, due to the combination of chemical enhancement and electromagnetic enhancement. And the detection sensitivity of R6G molecules by graphene-bilayer Au nanosphere composite arrays is 10−6 M. In addition, the staggered stacking of bilayer Au nanosphere arrays can provide more plasmonic hotspots, resulting in higher Raman intensity of the substrate. These results will pave the way for the fabrication of highly efficient SERS substrates by providing various promising candidates.

First-principles Calculations of the Electronic Structure and Optical Properties of Graphene-like InxAl1-xN Monolayers

This paper employs the Heyd-Scuseria-Ernzerhof (HSE) function to research electronic structures of monolayer InxAl1-xN with different compositions (x = 0, 0.25, 0.5, 0.75, 1) based on the first-principles, and the optical properties of single-layer InxAl1-xN are calculated by Generalized Gradient Approximation-Perdew Burke Ernzerhof (GGA-PBE) function. The influence of the electronic structure on the properties has been analyzed. Then the influence of doping quantity on the characteristics has been summarized, which also indicates the trend of the complex dielectric function and absorption spectrum. The calculation results show that with the increase of x, the static dielectric constant increases, the electron transition ability increases, and the absorption peak intensity in the light absorption spectrum increases. It can conclude that the InxAl1-xN compound can theoretically achieve the adjustable Eg and photoelectric performance with x, which will apply in making various optoelectronic devices, including solar cells and sensors.

Synthesis of Self-Assembled Single Atomic Layer Gold Crystals-Goldene.

We report, for the first time, a technique to synthesize free-standing, one-atom thick 2D gold crystals (namely, goldene) and self-assembled 2D periodic arrays of goldene. High-resolution transmission electron microscopy (HRTEM) imaging of goldene revealed herringbone and honeycomb lattices, which are primarily gold surface features due to its reconstruction. Imaging of these surface-only features by a nonsurface characterization technique such as HRTEM is an unequivocal proof of the absence of three-dimensionality in goldene. Atomic force microscopy confirmed 1-2 Å thickness of goldene. High-resolution X-ray photoelectron spectroscopy (HR-XPS), selective area electron diffraction, and energy-dispersive X-ray spectroscopy confirmed the chemical identity of goldene. We discovered the phenomenon of electric field-induced self-assembly of goldene supracrystals with a herringbone structure and developed an electric field printing (e-print) technique for goldene arrays. Goldene showed a semiconductor response with a knee voltage of ∼3.2 V, and I/V spectroscopy revealed periodic room temperature Coulomb blockade oscillations. These observations are consistent with the theoretical calculations reported in the literature predicting enhanced Coulombic interactions between gold valence electrons and the nucleus in stable 2D gold. Goldene exhibited multiple, intense, and well-resolved optical absorption peaks and several fine bands across the UV-vis region, and we calculated its optical band gap to be 3.59 eV. Magnetic force microscopy measurements of goldene periodic arrays showed a ∼5 mV peak amplitude confirming its ferromagnetism. Optical and magnetic properties of goldene are consistent with those reported in the literature for 2D planar gold clusters with less than 12 atoms.

Rheological Properties and Microstructural Analysis of Asphalt Binder Doped with Anti-Stripping Agent after Aging

In order to comprehensively explore the long-term durability of asphalt mixed with an anti-stripping agent, laboratory tests were carried out on base asphalt, SBS modified asphalt and base asphalt mixed with an anti-stripping agent after long-term aging. The rheological properties, chemical composition and microscopic morphology of the three asphalts before and after aging were compared and analyzed from macroscopic and microscopic angles. The results show that the modulus of asphalt is more affected by temperature than aging, and the anti-aging ability of the asphalt with the anti-stripping agent is better than that of base asphalt and slightly worse than that of SBS modified asphalt. The change in the absorption peak intensity before and after the aging of asphalt with the anti-stripping agent is the same as those of the base asphalt and SBS modified asphalt at 2920 cm−1 and 2850 cm−1, while the opposite pattern is observed in other four places. The honeycomb structures of the base asphalt and SBS modified asphalt became longer and the number of peaks increased slightly after aging. However, the asphalt surface with the anti-stripping agent had no obvious honeycomb structures before aging, and there were obvious honeycomb structures after aging, the number of which was between those of the base asphalt and SBS modified asphalt after aging; moreover, the lengths of honeycomb structures were still significantly smaller than those of the base asphalt after aging. This study investigated the performance changes of the anti-stripping-agent asphalt before and after long-term aging at multiple scales and compared the asphalt mixed with the anti-stripping agent with base asphalt and SBS modified asphalt to fully evaluate its long-term durability.

Structural and visible fluorescence traits of Dy3+ ion activated Lu1.5Y1.5Al5O12 phosphors

In the current work, a series of Lu1.5Y1.5Al5O12 (LuYAG) phosphors doped with different Dy3+ ion concentrations (0.5, 1, 2, 3, 4, and 5 at% in nominal) have been synthesized by high-temperature solid-phase approach and characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, transmission electron microscopy, optical absorption, emission, and decay lifetimes. The shape and position of Dy3+ ion absorption peaks were consistent in all samples, and the absorption peak intensity increased with enhancing Dy3+ concentration. Under λexci. = 448 nm, 4F9/2 → 6H15/2, 13/2, 11/2, 9/2 emission transitions have been identified in which the 4F9/2 → 6H13/2 transition possesses the highest intensity. Luminescence decay times were evaluated for Dy3+: 4F9/2 level. Relying on the absorption and luminescence spectra, along with fluorescence decay patterns, the optimal doping concentration of 1 at% was identified. The energy transfer process between Dy–Dy ions was discussed and utilized to explain the concentration quenching phenomenon. Notably, 1 at% Dy: LuYAG could be used as a potential candidate for commercial yellow phosphors.

Improvement of ilmenite flotation via the benzohydroxamic acid synergistic mechanical activation

In this paper, the effect of the benzohydroxamic acid (BHA) synergistic mechanical activation on ilmenite flotation was systematically investigated. Flotation results revealed that the flotation recovery of ilmenite significantly increased with the addition of BHA before grinding as compared to the conventional process flow. Similar trend was observed in the flotation test of artificial mixed mineral. The addition of BHA to the mill has little effect on the size distribution of ilmenite, but it can increase the content of crystal surface (104) with the lowest surface energy of ilmenite. The results of Fourier-transform infrared spectroscopy (FT-IR) analysis showed that the addition of BHA before grinding resulted in improving the intensity and kinds of characteristic absorption peaks of BHA on the ilmenite surface. The addition of BHA to the mill effectively facilitated the interaction between ilmenite and BHA. Besides, the result of flotation kinetics demonstrated that the flotation kinetics of ilmenite could be well evaluated with the first-order kinetic model. And the flotation kinetic constant was improved by adding BHA before grinding, which was conducive and beneficial for enhancing the ilmenite flotation.

Fabrication and Characterization of Chicken- and Bovine-Derived Chondroitin Sulfate/Sodium Alginate Hybrid Hydrogels.

The physicochemical properties and microstructure of hybrid hydrogels prepared using sodium alginate (SA) and chondroitin sulfate (CS) extracted from two animal sources were investigated. SA-based hybrid hydrogels were prepared by mixing chicken- and bovine-derived CS (CCS and BCS, respectively) with SA at 1/3 and 2/3 (w/w) ratios. The results indicated that the evaporation water loss rate of the hybrid hydrogels increased significantly upon the addition of CS, whereas CCS/SA (2/3) easily absorbed moisture from the environment. The thermal stability of the BCS/SA (1/3) hybrid hydrogel was higher than that of CCS/SA (1/3) hybrid hydrogel, whereas the hardness and adhesiveness of the CCS/SA (1/3) hybrid hydrogel were lower and higher, respectively, than those of the BCS/SA (1/3) hybrid hydrogel. Low-field nuclear magnetic resonance experiments demonstrated that the immobilized water content of the CCS/SA (1/3) hybrid hydrogel was higher than that of the BCS/SA (1/3) hybrid hydrogel. FTIR showed that S=O characteristic absorption peak intensity of BCS/SA (2/3) was obviously higher, suggesting that BCS possessed more sulfuric acid groups than CCS. SEM showed that the hybrid hydrogels containing CCS have more compact porous microstructure and better interfacial compatibility compared to BCS.

Detection of glutathione in dairy products based on surface-enhanced infrared absorption spectroscopy of silver nanoparticles.

In this paper, silver nanoparticles (AgNPs) were prepared as enhanced substrates for the detection of glutathione in dairy products by polyol reduction of silver nitrate. The infrared spectra were collected and analyzed by surface-enhanced infrared absorption spectroscopy (SEIRA) method of transmission mode using a cell of calcium fluoride window sheet immobilization solution for the study. The disappearance of the thiol (–SH) absorption peak in the infrared spectrum, and the shift of its characteristic absorption peak when glutathione was bound to AgNPs solvate indicated the Ag–S bond interaction and the aggregation of AgNPS. AgNPs accumulate to form “hot spots”, resulting in enhanced electromagnetic fields and thus enhanced infrared signals of glutathione. The intensity of the characteristic absorption peak at 1,654 cm−1 (carbonyl C=O bond stretching) was used for the quantitative analysis of glutathione. After optimizing the conditions, glutathione content in pretreated pure milk and pure ewe's milk was determined using AgNPs in combination with SEIRA. Good linearity was obtained in the range of 0.02–0.12 mg/mL with correlation coefficients (R2) of 0.9879 and 0.9833, respectively, and LOD of 0.02 mg/mL with average spiked recoveries of 101.3 and 92.5%, respectively. The results show that the method can be used for accurate determination of glutathione content in common dairy products.

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability.

The atmospheric dust has a great negative impact on the societal harmonious development that starves for an efficient dust suppressant. This paper proposes a novel AES/polyacrylamide strengthen foam (APSF) to improve the dust trapping effectiveness. The APSF structure property and dust suppression capacity are studied and evaluated through the molecular dynamics simulation and experimental tests. The results express that APSF exhibits the stronger structure stability, superior water retention, and slower drainage performance than the traditional water-based foam (WBF). APSF dynamic simulation is studied by the relative concentration, radial distribution function, head group orientation, and mean square displacement. Research shows that APSF introduces water to thicken the hydration layer. The interaction strength between water and surfactant head groups is enhanced by 22.62 and 31.37% in the first and second hydrated water shells. APSF improves the sodium fatty alcohol ether sulfate (AES) orientation and weakens the diffusion of water molecules, which favors the foam stability. APSF exerts a better wettability on the coal dust through the wet settlement and contact angle tests. The APSF liquid film thickness reduces to 58.05 from 64.80 μm that is 3.14 times of WBF according to the foam liquid film decay experiment. Fourier transform infrared (FTIR) spectroscopy analysis indicates that there is an evident reinforcement on the coal surface absorption peak intensity of hydroxyl- and oxygen-containing functional groups treated by APSF. FTIR results are further determined by energy-dispersion spectrum analysis.

Research on chemical resistance characteristics of water-immersed coal with different metamorphic degrees

In order to reduce the risk of spontaneous combustion of coal left after long-term flooding in the goaf of the mine, in this paper, the inhibitory properties of different inhibitors on two kinds of water-immersed coals with different metamorphic degrees were studied in depth. The experiment selected Pingzhuang brown coal and Shaqu coking coal as research objects. The raw coal and water-immersed coal samples were compared and analyzed by thermogravimetric experiment method and Fourier transform infrared spectroscopy experiment method. The study showed that the activation temperature of brown coal and coking coal decreased by 7.91 and 2.25 °C respectively, and the activation energy decreased by 43.18 kJ/mol and 20.58 kJ/mol respectively. The natural tendency of coal was enhanced after water immersion, and water immersion had a greater impact on low-metamorphic brown coal. After adding four kinds of inhibitors, MgCl2, TEMPO, TPPI and PA to the two water-immersed coals, it was found that TPPI could significantly reduce the heat release rate of water-immersed brown coal, and the reduction value was 10.49 W/mg. The dry cracking temperature of water-immersed brown coal increased by 11.75 °C, and PA greatly increased the combustion activation energy of water-immersed coking coal by 25.77 kJ/mol. Meanwhile, it was found from the microscopic active groups that TTPI increased the content of water-immersed brown coal ether bonds by 4.84%. The absorption peak intensity of oxygen-containing functional groups such as C=O was significantly weakened. Similarly, PA also produced a large number of stable ethers in water-immersed coking coal, whose content increased by 5.21%, and the hydroxyl content decreased most significantly. The decomposition of TPPI into phosphoric acid after heating can inhibit the growth of active groups such as a large number of oxygen-containing functional groups in the water-immersed brown coal, thereby reducing the risk of spontaneous combustion. As a metal chelator, PA can reduce the catalytic effect of metal ions in water-immersed coking coal with fewer active groups, and inhibit coal spontaneous combustion by generating stable metal complexes to increase activation energy. This indicated that TTPI had the best inhibitory effect on water-immersed brown coal, while PA was more suitable for water-immersed coking coal.

First-principle calculation of electronic structure and optical properties of (P, Ga, P–Ga) doped graphene

Abstract First-principle calculations are used to study the electronic structures, electronic and optical properties of pure, phosphorus-doped, aluminum-doped, and phosphorus and aluminum co-doped graphene. The gap between the conduction band and valence band of intrinsic graphene is zero. However, when graphene is doped with P, Ga, and P–Ga, the gap in energy will be opened and to a different extent. In the three different doping results, the gap values between the conduction and valence bands of P, Ga, and P–Ga graphene are 0.11, 0.35, and 0.39 eV, respectively. When graphene is doped with P–Ga, more electrons (1.40 e) will be gained by carbon atoms compared to P-doped graphene (0.61 e), while fewer electrons (1.49 e) will be transferred to carbon atoms compared to Ga-doped graphene (1.75 e). After doping with P, Ga, and P–Ga, the overall intensity of the graphene absorption peak is weakened and more pronounced relative to the low-frequency peaks. This result can fully demonstrate that the band gap of the doped graphene system can be better tuned by adding phosphorus and gallium atoms.

A Simple Cortisol Biosensor Based on AuNPs-DNA Aptamer Conjugate

Cortisol plays a key role in maintaining human life, regulating body material metabolism, promoting the development of secondary sexual characteristics and ensuring human normal biological function. We have studied an AuNPs-DNA conjugate aptamer biosensor. 20 nm AuNPs were prepared by seed method, and cortisol aptamer were bonded to the surface of gold nanoparticles by Au-S bond. When DNA aptamer binds to cortisol, the intensity of UV-Vis absorption peak of AuNPs decreases. The biosensor can quantitatively detect cortisol at the nanomolar level. The detection range of the biosensor is 1-1000 nM. In addition, the biosensor does not recognize cortisol related compounds, indicating its high selectivity.