Decrease In Peak Intensity Research Articles

Green Synthesis and Characterization of Silver Nanoparticles (AgNPs) and L-cysteine-capped AgNPs with Foeniculum vulgare seed extract for Colorimetric Hg2+ Detection

In this study, silver nanoparticles (AgNPs) and L-cysteine-capped AgNPs were synthesized separately using Foeniculum vulgare seed extract as the reducing agent and L-cysteine as the capping agent, which were characterized by ultraviolet–visible spectrophotometer (UV–vis), Fourier Transform Infrared spectrophotometer (FT-IR), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). The utilization of the synthesized nanomaterials as colorimetric sensors for the detection of Hg2+ ions was also investigated. In this context, it was determined that L-cysteine-capped AgNPs exhibited better performance in the colorimetric Hg2+ detection in regards to sensitivity, selectivity, and applicability in real samples. It was observed that the colorimetric detection method was based on the disappearance of the brown color of the nanomaterial-contained colloidal solution and thus the decrease in the LSPR peak intensity. The method of the colorimetric Hg2+ detection with L-cysteine-capped AgNPs showed the good regression coefficient with the minimum detection limit of 0.36 μM in the linear Hg2+ concentration range of 1.0-10 μM, which indicated the competitive results compared to the latest reported colorimetric sensors in the literature. According to the obtained results, it has been concluded that the studied method enables to detection of Hg2+ ions colorimetrically via L-cysteine-capped AgNPs in a sensitive, selective, applicable in real samples, cheap, and easy way.

Emerging CeO2/Bi24O31Cl10/Bi3O4Cl ternary-hetero-assembly nanophotocatalyst for superior sunlight-irradiated photo-elimination of quinolone antibiotics: Microwave combustion-assisted sono-induced-hydrothermal synthesis

This study aimed to introduce emerging CeO2/Bi24O31Cl10/Bi3O4Cl ternary-hetero-assembly nanophotocatalysts through the fabrication process of microwave combustion-assisted sono-induced-hydrothermal (MCSH). Various characterization techniques were conducted to determine the properties of the resulting nanophotocatalysts synthesized at different weighted ratios. The CeO2/Bi24O31Cl10/Bi3O4Cl-MCSH nanophotocatalyst which weighted ratio of CeO2 to Bi24O31Cl10/Bi3O4Cl is 3:1 showed a broad absorption range in the sunlight region and demonstrated tremendous performance in the removal of emerging contaminants such as norfloxacin (NOR) (87.6%), levofloxacin (70.2%), ofloxacin (66.2%) and ciprofloxacin-HCl (57.9%) after 180 min irradiation. In contrast, the CeO2/Bi24O31Cl10/Bi3O4Cl (3:1)-MCH sample, without ultrasound irradiation nanophotocatalyst, showed lower photocatalytic destruction such as norfloxacin 77.3%. As a result, it can be said that the presence of ultrasonic energy has led to particle size reduction and increased dispersion, resulting in a decrease in peak intensity based on XRD analysis. The DRS analysis showed that the optimal nanocomposite exhibited two distinct absorption edges at 415.6 and 487.8 nm, indicating that the desired composite had indeed been formed as well as the TEM signifies a consistent and evenly dispersed distribution of CeO2 particles and Bi24O31Cl10/Bi3O4Cl plates of nanomaterial's prepared with ultrasound energy. The BET-BJH of surface characteristics and pore distribution indicates that the pores' dimensions in the CeO2-MC, CeO2/Bi24O31Cl10/Bi3O4Cl (3:1)-MCH, CeO2/Bi24O31Cl10/Bi3O4Cl (3:1)-MCSH, and Bi24O31Cl10/Bi3O4Cl -MC samples span meso to macro. The average pore sizes for these nano-sized photocatalysts are approximately 21.4, 23.8, 22.1, and 5.4 nm, correspondingly. The remarkable efficiency and reusable nature of the CeO2/Bi24O31Cl10/Bi3O4Cl (3:1)-MCSH nanophotocatalyst could be assigned to its well-balanced phases and the use of the sonication during its preparation.

A sensing platform for ascorbic acid based on the spatial confinement of covalent organic frameworks

Essential to many activities in our bodies, ascorbic acid is a small molecule essential to human health and physiological processes. In this study, a covalent organic framework called TpNda-COF was synthesized, which is composed of Tp (triformylephloroglucinol) and Nda (1, 5-napthalenediamine). This framework acts as a mimic enzyme and displays excellent oxidase-like activity when stimulated with purple light (at = 405 nm). It catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzydine (TMB) by generating O2− free radicals in the presence of oxygen. The resulting oxTMB shows a characteristic absorption peak at 652 nm. The biomimetic catalysis efficiency is significantly improved due to spatial restriction. By introducing ascorbic acid (AA) in the system, the blue oxTMB is reduced to colorless TMB. The decrease in absorption peak intensity can be quantitatively measured using a UV–Vis spectrophotometer, enabling the detection of AA. The sensing platform demonstrates excellent selectivity and sensitivity. It has a wide linear detection range from 5 μM to 50 μM, with a low detection limit of 1.44 μM. Advantages such as the easy control of light, high stability and efficient oxidation are provided by the TpNda-COF mimic oxidase. This innovative method presents a promising and cost-effective approach for rapid detection of ascorbic acid, with potential applications across various fields.

First-principles study of NO adsorption on S vacancy of MoS2 monolayer

Based on first-principles study in this research, a single-layer two-dimensional MoS2 model with intrinsic and a MoS2 with S-site vacancy defects (MoS2-V) were constructed. The adsorption behaviors of NO on the surface of the two models are calculated, and the electronic properties, adsorption energy, and optical properties of the adsorption systems are studied and analyzed. The results of placing NO in different positions of MoS2 show that the adsorption effect is related to the orientation of NO. The adsorption energy of the optimal model for NO adsorbed on intrinsic MoS2 is 0.009 eV, and the adsorption energy on MoS2-V is − 0.304 eV. The forbidden band gap of both adsorption systems are significantly reduced. After NO was adsorbed onto intrinsic MoS2, the forbidden band gap changed from 1.729 eV to 0.235 eV. When NO was adsorbed onto MoS2-V, the forbidden band gap changed from 0.938 eV to 0.201 eV. The band gap change caused by the S vacancy defect leads to the reduction of the electron hopping chance between energy levels. The electron density difference diagrams show that MoS2-V has a stronger adsorption effect on the NO. The total and partial density of states (DOS) of the NO adsorption system shifts to the lower energy region. The dielectric function diagram of the MoS2-V adsorption system is shifted to the low-energy region, and the peak intensity decrease. The reflective index of the MoS2-V adsorb NO system is higher than that of the intrinsic MoS2 in the 0 eV＜E < 1 eV range, indicating that the MoS2-V material enhances the absorption of electromagnetic waves in low-frequency region. The reflective index tends toward zero in the high energy region of these two adsorption systems, indicating they all have strongly absorption of electromagnetic waves in high-frequency region. It is predicted that this material may be applied as a usable adsorption material or developed as a new type of gas material for early warning.

Oxygen Vacancy Ordering and Molten Salt Corrosion Behavior of ZnO-Doped CeYSZ for Solid Oxide Membranes.

Although 4Ce4YSZ has high corrosion resistance, it faces challenges concerning its sinterability and ionic conductivity. Therefore, we studied destabilization behavior caused by corrosion and oxygen vacancy ordering according to ZnO doping. Powders of (4Ce4YSZ)1-x(ZnO)x (x = 0.5, 1, 2, 4 mol%) were synthesized using the sol-gel method. With the addition of ZnO, the cubic phase increased, and secondary phases were not observed. The (111) peak showed a higher angle shift in ZnO-doped 4Ce4YSZ compared to 4Ce4YSZ, and TEM-SAED revealed a reduction in the spacing of the (011)t plane, suggesting lattice contraction due to the substitution of the smaller Zn2+ (60 Å) for Zr4+ (84 Å) in the lattice. The local atomic structure analysis was conducted using EXAFS to investigate the oxygen vacancy ordering behavior. Zr K-edge Fourier transform data revealed a decrease in the Zr-O1 peak intensity with an increasing amount of ZnO doping, indicating an increase in oxygen vacancies. The Zr-O1 peak position shifted to the right, leading to an increase in the Zr-O1 interatomic distance. In the Y K-edge Fourier transform data, the Y-O1 peak intensity did not decrease, and there was little variation in the Y-O1 interatomic distance. These results suggest that the oxygen vacancies formed due to ZnO doping are located in the neighboring oxygen shell of Zn, rather than in the neighboring oxygen shells of Y and Zr. Impedance measurements were conducted to measure the conductivity, and as the amount of ZnO doping increased, the total conductivity increased, while the activation energy decreased. The increase in oxygen vacancies by ZnO doping contributed to the enhancement of conductivity, and it is considered that these created oxygen vacancies did not interact with Zn2+ and did not form defect associations. Fluoride-based molten salts were introduced to the specimens to assess the corrosion behavior in a molten salt environment. Yttrium depletion layers (YDLs) were formed on the surfaces of all specimens due to the leaching of yttrium. However, Ce remained relatively stable at the interface according to EDS line scans, suggesting a reduction in the phase transformation (cubic, tetragonal to monoclinic) typically associated with yttrium leaching in YSZ.

Understanding the effect of Mn2+ on Yb3+/Er3+ co-doped NaYF4 upconversion and obtaining the optimal combination of these tridoping

In this work, we investigated in detail the upconversion properties of several types of nanoparticles, including NaYF4:5%Yb3+/30%Mn2+, NaYF4:40%Mn2+/x%Yb3+ (x% = 1, 5, 10, 20, 30, and 40), NaYF4:2%Er3+/x%Mn2+ (x% = 20, 30, 40, 50, 60, and 70), NaYF4:40%Mn2+/x%Er3+ (x% = 1, 2, 5, and 10), and NaYF4:40%Mn2+/1%Yb3+/x%Er3+ (x% = 0, 2, 5, and 10). We studied their upconversion emission under 980 nm excitation in both pulsed and continuous wave modes at different synthesis temperatures. The nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. The doping of Yb3+ and Mn2+ ions resulted in the nanoparticles assuming cubic and hexagonal crystal structures. The emission intensity increased (106.4 (a.u.*103) to 334.4(a.u.*103)) with increasing synthesis temperature from 120 to 140 °C, while a sharp decrease was observed when the synthesis temperature was increased to 200 °C. The gradual decrease in peak intensity with increasing Mn2+ concentration from 20 to 70% was attributed to energy transfer from Mn2+ to Yb3+. In NaYF4:Mn2+/Yb3+/Er3+ UCNPs, increasing the Er3+ concentration from 0 to 10% led to the disappearance of the blue, orange, and green emission bands. The intense upconversion luminescence pattern with high spatial resolution indicates excellent potential for applications in displays, biological sensors, photodetectors, and solar energy converters.

Spectral analysis of beam-combining-systems based on laser array with smile effect

The smile effect in semiconductor laser arrays can cause spectral deterioration in spectral beam combining (SBC) systems. We analyze this effect using position error and pointing deviation and propose a coupled-cavity resonance model based on the external-cavity optical feedback and the multibeam interference theory to study locked spectra. Our results indicate that the central emitter exhibits excellent spectral purity, and the edge emitters show side peaks and a decrease in peak intensity. With the increase in the position error and pointing deviation, the emitters experience an obvious spectral shift and an expansion of the spectral width. Pointing deviation has a greater impact on wavelength locking and array spectral width than position errors. Increasing the focal length and incident angle can reduce shifts and spectral width. Furthermore, adopting a grating with a large line density can also decrease its center wavelength shift and compress the spectral width of the combined beam.

Thermochemical modification of beech wood with ammonium hydroxide

Four variants of the thermochemical modification were conducted on beech wood at a temperature of 130 °C, employing NH4OH concentrations of 5% or 10% for durations of either 12 or 24 h. The weight% gain (WPG) and bulking coefficient (BC) were initially calculated. Subsequently, the wood’s degree of discoloration was assessed using the CIELAB-colour-system. Chemical structure alterations were determined through Fourier transform infrared spectroscopy (FTIR), while the compressive strength of the wood parallel to the grain was measured. As the NH4OH concentration increased and the treatment duration extended, the samples displayed simultaneous weight increase and volume reduction. The ΔE* values of the samples ranged from 19.33 to 21.09 units, indicating significant color alteration. FTIR analysis revealed differences between the spectra of the unmodified control sample and the NH4OH-treated samples. The modification reduced in hydroxyl and carboxyl groups within the main and side chains of hemicelluloses. Additionally, a decrease in the absorption peak intensity of the unconjugated carbonyl group at 1740 cm− 1 indicated a relative reduction in hemicellulose content. Compressive strength tests showed that the thermochemical modification improved the modulus of elasticity, increasing it from 10,898 MPa (in the control sample) to a range of 11,663 − 13,390 MPa. Similarly, the compressive strength increased from 77.10 MPa to 81.56-107.19 MPa. Interestingly, this improvement was more pronounced with higher concentrations of NH4OH and prolonged modification durations.

Transmission Characteristics and Spatial Coherence of Partially Coherent Light-Emitting Diode Array in the Ocean

Underwater LED light sources are commonly implemented in array configurations with a wide-angle field of view, primarily catering to high-speed communication within a few meters. To increase transmission distance and mitigate oceanic turbulence effects, this paper focuses on the spatial coherence analysis of narrow-beam partially coherent light-emitting diode (PCLED) arrays, examining their average light intensity distribution, beam width, and spatial coherence during oceanic transmission. Based on the extended Huygens–Fresnel integral, the optical field models and spatial characteristics of the radial PCLED array are derived under oceanic conditions, considering parameters such as water attenuation coefficient, kinetic energy dissipation rate, temperature dissipation rate, temperature-to-salinity ratio, as well as the radial filling factor and the sub-beam spatial coherence length of the light source at different transmission distances. The simulations show that, as the spatial coherence length of the sub-beam decreases from hundreds to a few micrometers, the combining distance of the beam arrays also decreases. This reduction in coherence results in the average light intensity distribution degrading into a Gaussian-like distribution, with a significant five-fold decrease in peak intensity. Furthermore, the width of the array spreads, starting from distances of 7 m and 0 m, respectively. The radial PCLED beam array, with its sub-beam spatial coherence length inside micrometers, possesses inherent characteristics that suppress turbulence effects and has future extensive possibilities in the ocean.

Effects of different plant proteins on the quality and characteristics of heat induced egg white protein gel under freezing conditions

Eggs white is rich in protein, whose gel property is one of the most important functional characteristics during processing. The purpose of this study was to reveal the effect of different plant proteins (2% (w/w), 2.5% (w/w), 3% (w/w)) on the quality of heat induced egg white protein (EWP) gel after freezing. Gels were prepared by adding 2.5% soy protein isolates (SPI) or pea protein isolates (PPI), and then were frozen for 14 days. Compared with the control group (EWP without adding any plant proteins), the hardness, chewiness and gumminess of SPI-EWP gel were increased by 58.23%, 71.11% and 66.35%, respectively, which was better than PPI-EWP. The thawing loss rate of SPI-EWP and PPI-EWP gel decreased by 16.8% and 13.0%, respectively, and the centrifugal loss rate decreased by 13.2% and 11.8%, respectively. The addition of plant proteins resulted in a decrease in the proton signal intensity of the T23 peak. Hydrogen proton imaging and rheology results showed that water content of gels added with plant proteins after freezing was higher than control group and showed better viscoelasticity (SPI was better than PPI). The results of intermolecular forces indicated that with the increase of plant protein, the ionic bonds decreased, the contribution of disulfide bonds significantly increased (p < 0.05). Fourier Transform Infrared Spectroscopy (FTIR) indicated that the α-helix content decreased, β-sheet increased. In brief, this study provides valuable reference for the development and application of plant protein to improve the quality of egg white protein in food industry.

Electrochemical Determination of 17-β-Estradiol Using a Glassy Carbon Electrode Modified with α-Fe2O3 Nanoparticles Supported on Carbon Nanotubes.

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)-denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L-1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0-100.0 nmol L-1 and a low limit of detection of 4.4 nmol L-1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis.

Improve physical properties of zirconium doped strontium sulphide for optoelectronic purpose

The electrochemical deposition was used to synthesize zirconium-doped strontium sulphide materials at varying dopant concentrations of 0.01 to 0.03 mol. The surface micrograph of the zirconium doped films is well structured on the surface of the FTO used for the synthesis without any crack or lattice strain. The spectrum is polycrystalline with a cubic structure and a prominent peak at (111) orientation for SrS film. At the introduction of the zirconium dopant 0.01 mol, the peak intensity increases with a prominent peak at (211) which indicate acceptance of zirconium dopant in the precursor and as the dopant concentration rises the peak intensity decreases which depicts that a higher concentration of zirconium reduces the peak intensity of the films. The Williamson-Hall plot's slope increases as the dopant concentration increases. The materials exhibit a thickness increase of 121.32 to 126.13 nm and a decrease in film resistivity from 1.12 × 109 to 1.32 × 109 O.m, which further led to an increase in conductivity from 7.57 × 108 to 8.26 × 108 S/m. The bandgap energy of SrS is 1.50 eV while SrS-doped zirconium is 1.35 eV–2.52 eV.

Interfacial bond characterization of epoxy adhesives to aluminum alloy and carbon fiber-reinforced polyamide by vibrational spectroscopy

Vibrational spectroscopic technique has been utilized to investigate interfacial bonding chemistry of two epoxy adhesive products, XP0012 and XP5005F, on plasma-treated AA6061 and carbon fiber-reinforced polyamide 66 (CFRP-PA66) surfaces. The change in vibrational peak ratios was measured by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy to deduce bonding mechanisms. Both adhesives showed strong crosslinking polymerization of hydroxyl- and amine-initiated epoxy ring opening on AA6061 surface, but on CFRP surface XP0012 formed a simple amide linkage by the reaction of surface hydroxyl groups and nitrile groups of curing agent, and XP5005F formed a crosslinked network by hydroxyl-initiated epoxy ring opening polymerization. The different interfacial bonding formation of two adhesives on CFRP-PA66 surface is attributed to additive effect. Addition of additives to epoxy adhesives (XP5005F) changed the interfacial bonding mechanism on CFRP-PA66 surface, rather forming hydroxyl-initiated epoxy opening crosslinking polymerization than a simple amide bond formation (XP0012). The interfacial bonding chemistry was also proved by addition of bisphenol A (BA) to a simplified model diglycidyl ether of bisphenol A/dicyandiamide (DGEBA/DICY) epoxy system. When BA was added to the model DGEBA/DICY system, epoxy ring gradually decreased on CFRP-PA66 surface, while without BA, DGEBA/DICY showed only decrease in a nitrile peak intensity in ATR-FTIR. The foregoing different types of interfacial chemical bonds at the adhesive/CFRP-PA66 interfaces can affect the lap shear behavior of the joint.

Structural Analysis of Cu+ and Cu2+ Ions in Zeolite as a Nanoreactor with Antibacterial Applications.

In this work, we report the structural analysis of Cu+ and Cu2+ ions in zeolite as a nanoreactor with antibacterial applications. A simple one-step process was implemented to obtain Cu ions in zeolite A (ZA4) by controlling the temperature in the solutions to guarantee the ions' stability. Samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy, showing the characteristic zeolite elements as well as the characteristic bands with slight modifications in the chemical environment of the zeolite nanoreactor attributed to Cu ions by FT-IR spectroscopy. In addition, a shift of the characteristic peaks of ZA4 in X-ray diffraction was observed as well as a decrease in relative peak intensity. On the other hand, the antibacterial activity of Cu ions in the zeolite nanoreactor was evaluated.

After the sun: a nanoscale comparison of the surface chemical composition of UV and soil weathered plastics

Once emitted into the environment, macro- (MaP), micro- (MP) and nanoplastics (NP) are exposed to environmental weathering. Yet, the effects of biogeochemical weathering factors occurring in the soil environment are unknown. As the transport, fate, and toxicity of MP and NP depend directly on their surface properties, it is crucial to characterize their transformation in soils to better predict their impact and interactions in this environment. Here, we used scanning transmission x-ray micro spectroscopy to characterize depth profiles of the surface alteration of environmental plastic debris retrieved from soil samples. Controlled weathering experiments in soil and with UV radiation were also performed to investigate the individual effect of these weathering factors on polymer surface alteration. The results revealed a weathered surface on a depth varying between 1 µm and 100 nm in PS, PET and PP environmental plastic fragments naturally weathered in soil. Moreover, the initial step of surface fragmentation was observed on a PS fragment, providing an insight on the factors and processes leading to the release of MP and NP in soils. The comparison of environmental, soil incubated (for 1 year) and UV weathered samples showed that the treatments led to different surface chemical modifications. While the environmental samples showed evidence of alteration involving oxidation processes, the UV weathered samples did not reveal oxidation signs at the surface but only decrease in peak intensities (indicating decrease of the number of chemical C bonds). After a one-year incubation of samples in soil no clear aging effects were observed, indicating that the aging of polymers can be slow in soils.

Charge transfer and X-ray absorption investigations in aluminium and copper co-doped zinc oxide nanostructure for perovskite solar cell electrodes

This study explores influence of charge transfer and X-ray absorption characteristics in aluminum (Al) and copper (Cu) co-doped zinc oxide (ZnO) nanostructures for perovskite solar cell electrodes. Sol-gel technique was employed to synthesize the nanostructures, and their optical and morphological properties were investigated. X-ray diffraction (XRD) analysis confirmed high crystallinity and also single-phase composition of all the samples, particularly up to 5% Al co-doping. Field emission scanning electron microscopy (FESEM) exhibited the formation of pseudo-hexagonal wurtzite nanostructure and the transition to nanorods at 5% Al co-doping. Diffuse reflectance spectroscopy indicated a reduction in the optical band gap of co-doped zinc oxide from 3.11 to 2.9 eV with increasing Al doping. Photoluminescence spectra (PL) exhibited a decrease in peak intensity, suggesting enhanced conductivity in ZnO, also confirmed from I-V measurements. Near-edge X-ray absorption fine structure (NEXAFS) analysis depicts that charge transfer from Al to oxygen (O) species enhanced the photosensing properties of the nanostructure, which was supported by FESEM micrographs and PL spectra. Furthermore, the study discovered that 5% Al co-doping significantly reduced the density of emission defects (deep-level) in Cu–ZnO nanostructure. These findings highlight the potential of Cu and Al co-doped ZnO materials for perovskite solar cell electrodes, as their improved optical and morphological properties resulting from charge transfer could enhance device performance. The investigation of charge transfer and X-ray absorption characteristics provides valuable insights into the underlying mechanisms and behaviors of the co-doped ZnO nanostructures. However, further research is required to delve into the intricate hybridization resulting from charge transfer and explore the broader impact of co-doping on other properties of the nanostructures, enabling a comprehensive understanding of their potential applications in perovskite solar cells.

Evaluation of control of additive concentration in gradient analysis of supercritical fluid chromatography-coupled to tandem mass spectrometry

Mobile phase additives are used to improve retention behavior in chromatography. In supercritical fluid chromatography (SFC), for which supercritical fluid carbon dioxide (SF-CO2) is used as the main mobile phase, additives can only be added into the modifier. For that reason, when gradient analysis is performed by changing the modifier ratio to SF-CO2, the additive concentration in the mobile phase increases in parallel with the modifier ratio. In a preliminary study performed using the conventional SFC system, ammonium acetate was necessary to improve the peak shape of a polar steroid, dehydroepiandrosterone sulfate (DHEA-S), while the peak intensity of a non-polar steroid, progesterone, decreased by 78% compared to that in the absence of the additive in mobile phase when gradient elution was performed. Since ammonium acetate had both favorable and unfavorable effects on sensitive and simultaneous analysis of these two steroid compounds, a compromise between these effects had to be sought. A three-pump configuration of SFC was developed by adding a pump unit to SFC instrument, which enabled control of the additive concentration independently of the modifier ratio, for the purpose of investigating the additive effect in detail using both steroids as model compounds. The putative cause of the decrease in peak intensity of progesterone was excessively elevated additive concentration in gradient analysis. When the additive concentration in the mobile phase was controlled to ensure that it did not increase during gradient analysis, the peak intensities of progesterone, cortisol, corticosterone, and testosterone were 55%, 40%, 25%, and 17% higher than when the additive concentration was not controlled, respectively. On the other hand, the peak intensity of DHEA-S was almost identical between the conditions, with an increase of 2% with three-pump instrument. The three-pump configuration showed the potential to solve problems relating to the use of modifier additives by keeping their concentration constant in gradient SFC analysis.

Study on structural properties of swift heavy ion induced damage in Al2O3

Polycrystalline α-Al2O3 is irradiated using 100 MeV Au ion, with fluences range extended from 1 × 1012 to 1 × 1014 ions/cm2. The objective of this work is to study the impact of swift heavy ion (SHI) on structural and morphological properties of α-Al2O3 and confirm the predicted results with the help of thermal spike (TS) model. XRD result reveals that there is a decrease in peak intensities with an increase in ion fluence. The reduction of peak intensity indicates the increased disorder or defect formation in α-Al2O3 due to SHI irradiation. Further, PL results also corroborated with the XRD outcome. Information on damage formation and molten track radius is extracted from the XRD data, and the molten track radius is obtained to be ∼2.42 ± 0.13 nm. Morphological changes due to SHI irradiation are studied using FESEM and AFM techniques and reveal the increase of surface roughness with the SHI fluences. Furthermore, the radius of latent track formation and radiation-induced lattice temperature spike are estimated for SHI irradiated Al2O3 using three cases; elastic TS model (only Sn), inelastic TS model (only Se), and unified TS model (Sn + Se). The numerically calculated latent track considering the combined contribution of Sn and Se in the unified TS model is around 2.6 nm, which is in good agreement with the experimental determination. The present study investigates the overall performance of structural properties of Al2O3 for SHI irradiation and explains the radiation tolerance of ceramic for corresponding ion fluence.

Removal of epigenetic repressive mark on inflammatory genes in fat liver.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. The detailed epigenomic changes during fat accumulation in liver are not clear yet. Here, we performed ChIP-Seq analysis in the liver tissues of high-fat diet and regular chow diet mice and investigated the dynamic landscapes of H3K27ac and H3K9me3 marks on chromatin. We find that the activated typical enhancers marked with H3K27ac are enriched on lipid metabolic pathways in fat liver; however, super enhancers do not change much. The regions covered with H3K9me3 repressive mark seem to undergo great changes, and its peak number and intensity both decrease in fat liver. The enhancers located in lost H3K9me3 regions are enriched in lipid metabolism and inflammatory pathways; and motif analysis shows that they are potential targets for transcription factors involved in metabolic and inflammatory processes. Our study has revealed that H3K9me3 may play an important role during the pathogenesis of NAFLD through regulating the accessibility of enhancers.

Intensity-dependent mass search for improving metabolite database matches in chemical isotope labeling LC-QTOF-MS-based metabolomics

Liquid chromatography mass spectrometry (LC-MS) has been increasingly used for metabolome analysis. One of the critical steps in the LC-MS metabolome analysis workflow is related to metabolite identification. Among the measured parameters, peak mass is commonly used to search against a database for potential metabolite matches. Higher accuracy mass measurement allows the use of a narrower mass tolerance window for mass search. While various types of mass analyzers can routinely measure a peak mass with an error of less than a few ppm, mass measurement accuracy is not uniform for peaks with different intensities, particularly for quadrupole time-of-flight (QTOF) MS. Herein we present a simple and convenient method to determine the relation between peak intensity and mass error in LC-QTOF-MS-based metabolome analysis, followed by intensity-dependent mass search (IDMS) of a database for metabolite matches. This method is based on running a series of sodium formate mass calibrants, as part of the standard operating procedure (SOP) in LC-MS data acquisition, and then curve-fitting the measured mass errors and peak intensities. We show that, in two different quadrupole time-of-flight (QTOF) mass analyzers, mass accuracy is generally reduced as peak intensity decreases, which is independent of m/z values in the range commonly used for metabolite detection (e.g., m/z < 1000). We demonstrate the improvement in metabolite matches using IDMS in the analyses of dansyl labeled standards and human urine samples. We have implemented the IDMS method in the freely available MCID database at www.mycompoundid.org, which is composed of 8021 known human endogenous metabolites and their predicted metabolic products (375,809 compounds from one metabolic reaction and 10,583,901 compounds from two reactions).