UV Absorption Research Articles

AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy

We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multiwavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AGN STORM 2) Project. The campaign revealed an unexpected and transient obscuring outflow, never before seen in this source. Of our four XMM-Newton/NuSTAR epochs, one fortuitously taken during a bright X-ray state has strong narrow absorption lines in the high-resolution grating spectra. From these absorption features, we determine that the obscurer is in fact a multiphase ionized wind with an outflow velocity of ∼5200 km s−1, and for the first time find evidence for a lower ionization component with the same velocity observed in absorption features in the contemporaneous Hubble Space Telescope spectra. This indicates that the UV absorption troughs may be due to dense clumps embedded in diffuse, higher ionization gas responsible for the X-ray absorption lines of the same velocity. We observe variability in the shape of the absorption lines on timescales of hours, placing the variable component at roughly 1000 R g if attributed to transverse motion along the line of sight. This estimate aligns with independent UV measurements of the distance to the obscurer suggesting an accretion disk wind at the inner broad line region. We estimate that it takes roughly 200 days for the outflow to travel from the disk to our line of sight, consistent with the timescale of the outflow's column density variations throughout the campaign.

Features of the defect structure of a lithium-gradient nonlinear optical single crystal LiNbO3 and their manifestation in the Raman spectra

LiNbO3 crystal with a lithium composition gradient of Li/Nb = 0.8 wt%/cm (Li0.97..1.01Nb1.03..0.99O3) were obtained. A monotonic change in the edge of the UV absorption edge is observed when scanning the surface of the gradient crystal along the growth direction. Raman spectra from different areas of studied crystal were analyzed in a wide frequency range, which includes the region of fundamental vibrations of the crystal lattice (100–900 cm−1) and the region of overtone processes (900–3000 cm−1). A compositionally homogeneous, congruent LiNbO3 crystal was used as a comparison sample. It was found that in the spectra obtained from different parts of the gradient crystal, there is a significant scatter in the frequency values of the lines corresponding to the fundamental vibrations of the crystal lattice, but at the same time, the number of lines corresponding to the fundamental vibrations of the lattice for the gradient and compositionally homogeneous LiNbO3 crystals is the same. Moreover, in the spectrum of a gradient crystal in the region of overtone processes of fundamental vibrations, significantly more lines (35 lines) are observed than in the spectrum of compositionally homogeneous crystals (15 lines). The data obtained show that the state of the defect structure of compositionally homogeneous crystals and gradient LiNbO3 crystal is significantly different. The discovered differences between the defective structure of a gradient crystal and the defective structure of a compositionally homogeneous crystal may be the reason for compensation (damping) of distortions during nonlinear optical conversion of laser radiation by a gradient crystal due to the uneven temperature distribution along the length of the crystal. In compositionally homogeneous crystals, such temperature distortions significantly limit the efficiency of nonlinear optical conversion.

Preparation and characterization of a konjac glucomannan-based bio-nanocomposite film and its application in cherry tomato preservation

Strategies to overcome the limitations of konjac glucomannan (KGM) films, including their poor mechanical properties, low water resistance, and limited bioactivity, are being developed. In this study, fucoidan-chitosan nanoparticles encapsulating tea polyphenols (TP-FCNPs) were prepared using an electrostatic self-assembly method. Subsequently, a novel bio-nanocomposite film was prepared by incorporating TP-FCNPs as fillers into a KGM-based membrane. The microstructural, physical, and biological properties of the nanocomposite films were evaluated. Scanning electron microscopy (SEM) observations showed that in the KGM/TP-FCNPs containing 1–7% TP-FCNPs, the TP-FCNPs were uniformly distributed throughout the KGM film matrix. The highest tensile strength of KGM/TP-FCNPs films was 33.05 ± 1.57 MPa, which was 404.53% that of pure KGM film. Incorporating TP-FCNPs also significantly enhanced the UV absorption ability and antimicrobial and antioxidant activities of the bio-nanocomposite films, while reducing their transmittance. In addition, KGM/TP-FCNPs used as packaging effectively reduced fruit mass loss and firmness loss, inhibited microbial growth, and significantly prolonged fruit shelf-life on day 21 of the cherry tomato (Lycopersicon esculentum var. cerasiforme A. Gray) packaging trial. In conclusion, the KGM/TP-FCNPs bio-nanocomposite films exhibit satisfactory properties, and thus, show potential for applications in fruit preservation.

Intercomparison of fast airborne ozone instruments to measure eddy covariance fluxes: spatial variability in deposition at the ocean surface and evidence for cloud processing

Abstract. The air–sea exchange of ozone (O3) is controlled by chemistry involving halogens, dissolved organic carbon, and sulfur in the sea surface microlayer. Calculations also indicate faster ozone photolysis at aqueous surfaces, but the role of clouds as an ozone sink is currently not well established. Fast-response ozone sensors offer opportunities to measure eddy covariance (EC) ozone fluxes in the marine boundary layer. However, intercomparisons of fast airborne O3 sensors and EC O3 fluxes measured on aircraft have not been conducted before. In April 2022, the Technological Innovation Into Iodine and GV Environmental Research (TI3GER) field campaign deployed three fast ozone sensors (gas chemiluminescence and a combination of UV absorption with coumarin chemiluminescence detection, CID) together with a fast water vapor sensor and anemometer to study iodine chemistry in the troposphere and stratosphere over Colorado and over the Pacific Ocean near Hawaii and Alaska. Here, we present an instrument comparison between the NCAR Fast O3 instrument (FO3, gas-phase CID) and two KIT Fast AIRborne Ozone instruments (FAIRO, UV absorption and coumarin CID). The sensors have comparable precision < 0.4 % Hz−0.5 (0.15 ppbv Hz−0.5), and ozone volume mixing ratios (VMRs) generally agreed within 2 % over a wide range of environmental conditions: 10 < O3 < 1000 ppbv, below detection < NOx < 7 ppbv, and 2 ppmv < H2O < 4 % VMR. Both instrument designs are demonstrated to be suitable for EC flux measurements and were able to detect O3 fluxes with exchange velocities (defined as positive for upward) as slow as −0.010 ± 0.004 cm s−1, which is in the lower range of previously reported measurements. Additionally, we present two case studies. In one, the direction of ozone and water vapor fluxes was reversed (vO3 = +0.134 ± 0.005 cm s−1), suggesting that overhead evaporating clouds could be a strong ozone sink. Further work is needed to better understand the role of clouds as a possibly widespread sink of ozone in the remote marine boundary layer. In the second case study, vO3 values are negative (varying by a factor of 6–10 from −0.036 ± 0.006 to −0.003 ± 0.004 cm s−1), while the water vapor fluxes are consistently positive due to evaporation from the ocean surface and spatially homogeneous. This case study demonstrates that the processes governing ozone and water vapor fluxes can become decoupled and illustrates the need to elucidate possible drivers (physical, chemical, or biological) of the variability in ozone exchange velocities on fine spatial scales (∼ 20 km) over remote oceans.

Lignin‐Based Macromolecular Photoinitiator for Non‐Migration, Self‐Adhesive, and Water‐Resistant Eutectogels toward Underwater Reliable Communication

AbstractHydrophobic conductive gels have attracted much attention in underwater sensing as the soft robots and wearable sensors. Among the various methods for preparing conductive gels, UV‐initiated polymerization shows advantages of rapid curing and significant energy savings. However, traditional commonly used photoinitiators in UV‐initiated polymerization often migrate or diffuse within conductive gels, especially with prolonged use or underwater, posing potential environmental and health risks. Herein, a novel lignin‐based macromolecular photoinitiator (L‐BF) is first designed by incorporating benzoylformate into the lignin backbone, demonstrating excellent UV absorption, high radical initiation efficiency, and hydrophobicity. Subsequently, hydrophobic eutectogels (HEG) are prepared via UV‐initiated polymerization using L‐BF as photoinitiator. The HEG shows excellent mechanical properties (toughness of 5.67 MJ m−3 and strain of 941%) and scarcely L‐BF migration underwater. Moreover, the hydrophobic network of L‐BF endowed HEG with hydrophobicity (water contact angle exceeds 110°; swelling ratio is <5.8%), superior underwater adhesion (255 kPa), even maintained excellent sensing performance (gauge factor of 4.69), and long‐term reproducibility (20 000 cycles) in air and underwater. Validation confirms the potential of HEG as an effective wearable sensor for underwater posture monitoring and communication, advancing the use of lignin and low‐migration conductive gels in marine exploration.

A novel rhodamine B fluorescence probe for rapid identification of different amino acids by high efficiency fluorescence spectrum-mass spectrometry.

Rapid detection of amino acids plays an important role in the field of medical diagnosis. By combining Rhodamine B with triphenylamine, a novel double-response fluorescence probe (E)-4-((4-(((3',6'-bis(diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)imino)methyl)phenyl)(phenyl)amino)benzaldehyde (RBTPA) was prepared for rapid identification of different amino acids. Under daylight and 365 nm irradiation, it was found that the color change was most bright at pH = 3, and changed to dim at pH = 4. When pH = 3 and pH = 4, the photophysical properties of the two strong acids are very different. The maximum redshift of UV absorption light is 110nm, and the maximum fluorescence emission intensity is 4 times different. In order to further observe their binding structure analysis with different amino acids, qualitative analysis of each response structure was determined by mass spectrometry according to different molecular weights. The fluorescence probe RBTPA has two different isomers for recognition response in aldehyde group and imine group, respectively.

Use of indocyanine green-human serum albumin complexes in fluorescence image-guided laparoscopic anatomical liver resection: a case series study (with video)

BackgroundThis study aimed to investigate the feasibility and efficacy of near-infrared fluorescence-guided laparoscopic anatomical hepatectomy (LAH) using a novel indocyanine green (ICG)-human serum albumin complex (HSA) in patients with hepatocellular carcinoma.MethodsClinical data of hepatocellular carcinoma patients who underwent ICG-HSA fluorescence-guided LAH at our center from January 2024 to April 2024 were prospectively collected and analyzed. Ultraviolet absorption spectroscopy was used to test the absorption and stability of ICG-HSA complex solutions under different conditions. After determining the optimal ratio, the complex was administered intravenously during surgery to perform negative staining via Glissonean pedicle isolation. LAH was performed along the fluorescence-demarcated boundaries.ResultsThirty-one patients were included (24 men; mean age, 54.61 ± 13.54 years). The median maximum tumor diameter was 2.80 (interquartile range [IQR], 2.00–4.00) cm. S8 segmentectomy (22.6%) and right posterior segmentectomy (19.4%) were the most common resections performed. Successful fluorescence negative staining was achieved in all patients using ICG and HSA at a 1:6 molar ratio at room temperature. Mean operation time was 297.58 ± 85.53 min, Median intraoperative blood loss was 100.0 mL (IQR, 50.0–200.0). The median surgical margin distance was 0.90 cm (IQR, 0.40–1.50). The postoperative complication rate was 45.2% (35.5% Clavien–Dindo grade I and 9.7% grade II). The median length of hospital stay was 5.0 days (IQR, 4.0–5.0).ConclusionICG-HSA-assisted LAH is safe and feasible. Compared with free ICG, the novel ICG-HSA complex exhibits better optical properties and in vivo stability, which can improve the accuracy of intraoperative liver segment localization and optimize the anatomical dissection plane. It has the potential to become an ideal fluorescent imaging agent for anatomical hepatectomy.Graphical abstractA In vitro binding experiments of indocyanine green (ICG) and human serum albumin (HSA) suggested that a 1:6 molar ratio and a configuration temperature of 37°C were optimal. B During surgery, after extrahepatic Glissonean isolation of the liver pedicle planned for resection, the ICG-HSA complex was administered through a peripheral vein using an infusion pump. C ICG-HSA metabolism comprises three stages: intravascular, liver, and systemic clearance. D The actual intraoperative fluorescence imaging and guidance effects of ICG-HSA in laparoscopic fluorescence negative-staining right hemihepatectomy.

Effect of tea polyphenols on the formation of advanced glycation end products (AGEs), functional and structural properties of modified protein in Maillard reaction

To improve the solubility and processing properties of gluten protein, Maillard reaction at three temperatures (70 °C, 100 °C and 130 °C) was used to modified gluten, and the effect of tea polyphenols (TPs) on the functional and structural properties of Maillard reaction products (MRPs) were investigated. The results showed that higher temperature and TPs increased significantly (p < 0.05) the antioxidant activity of MRPs and the order was ABTS > TRC > DPPH, which maxima were 72.5%, 61.5% and 44.3%, respectively, when the TPs addition was 0.3 g/100 mL at 130 °C. After undergoing thermal treatment, significant increase of foamability and emulsifying stability was observed, while the foam stability and emulsifying activity decreased with the addition of TPs. TPs altered the maximum UV absorption value and caused a red-shift for MRPs. Additionally, the reduced fluorescence intensity indicated that TPs decreased the amount of Maillard reaction intermediates as well as AGEs. Furthermore, 0.3 g TP/100 mL significantly increased (p < 0.05) hydrophobicity with maximum of 48.6%, while β-sheet content decreased from 45.7% to 40.4% compared to the control. The Maillard reaction improved the processing properties of gluten protein, and TPs effectively inhibited the production of AGEs and 5-hydroxymethylfurfural.

Degradation of citrate and reduction of Cu(II) in wastewater containing Cu(II)-citrate complex by UV irradiation

Advanced oxidation coupled with precipitation was employed to remove organic ligands (L) and Cu(II) from wastewater containing the Cu(II)-L complex. In this strategy, more than 99 % of Cu(II) and L were effectively removed. Cu(II) eventually entered the copper-containing sludge and cannot be recovered. In this study, the UV irradiation-induced degradation of citrate and simultaneous reduction of Cu(II) without any reagent was proposed. It was found that 97.34 % of citrate was degraded, simultaneously, 99.09% of Cu(II) were removed and recovered as high-purity Cu(0) (purity = 99.79%). The identification of free radicals and intermediates showed that the degradation of citrate was a successive decarboxylation process. H• and CO2•- formed during the successive decarboxylation and these two free radicals reduced Cu(II) to Cu(0). The pH values significantly affected the removal of citrate and Cu(II), and the optimal pH was 5.0 due to the strongest UV absorption by Cu(II)-citrate at pH 5.0. Dissolved O2, CO32– and PO43- slightly inhibited the citrate and Cu(II) removal, and Cl-, Ca2+ and Mg2+ exhibited negligible effects. This study provides a promising strategy for the degradation of citrate and simultaneous recovery of heavy metals from wastewater.

Ballistic and delayed photodissociation channels in the B̃ 2A11 state of water studied with resonant inelastic x-ray scattering

Photodissociation is one of the most important photoinduced chemical reactions. It occurs when the potential energy curve along a chemical bond is repulsive in an excited state. Typically, “ballistic” ultrafast dissociation leads to the broadening of absorption resonances and the smearing out of vibrational fine-structure. We report on the photodissociation of H2O in the B̃ 2A11 electronic state, characterized by a |3a1−14a11〉 configuration, which can be reached via resonant inelastic x-ray scattering or direct ultraviolet absorption. In both cases the spectra show narrow vibrational resonances, in spite of the dissociative character of the state. We find that “delayed” dissociation pathways, caused by reflection of the nuclear wave packet, are responsible for this effect. In spite of the analogous topology of the potential energy surfaces of the core- and valence-excited states, the reflection of the wave packet takes place only in the latter. The two-dimensional wave packet of the O-H stretching coordinates becomes trapped in a “cavity” near the Franck-Condon region, resulting from a mismatch between the OH vibrational frequency in the cavity and the one at the dissociation limit. Published by the American Physical Society 2024

The Densities in Diffuse and Translucent Molecular Clouds: Estimates from Observations of C2 and from Three-dimensional Extinction Maps

Newly computed collisional rate coefficients for the excitation of C2 in collisions with H2, presented recently by Najar & Kalugina, are significantly larger than the values adopted previously in models for the excitation of the C2 molecule, a widely used probe of the interstellar gas density. With these new rate coefficients, we have modeled the C2 rotational distributions inferred from visible and ultraviolet absorption observations of electronic transitions of C2 toward a collection of 46 nearby background sources. The inferred gas densities in the foreground interstellar clouds responsible for the observed C2 absorption are a factor 4–7 smaller than those inferred previously, a direct reflection of the larger collisional rate coefficients computed by Najar & Kalugina. These lower-density estimates are generally in good agreement with the peak densities inferred from 3D extinction maps for the relevant sight lines. In cases where H3+ absorption has also been observed and used to estimate the cosmic-ray ionization rate (CRIR), our estimates of the latter will also decrease accordingly because the H3+ abundance is a function of the ratio of the CRIR to the gas density.

Diatom biosilica modified with Ce-Tb mixed oxide twinning nanoparticles and with polyphases quasi-crystalline Tb oxide nanoparticles

In this study, we developed a novel composite material by combining natural diatom biosilica with Ce-Tb mixed oxide and polyphase quasi-crystalline Tb oxide nanoparticles. Diatom biosilica, characterised by its highly ordered three-dimensional structure and excellent thermal, mechanical, and optical properties, serves as an ideal matrix for the synthesis of advanced functional materials. The composites were extensively characterised using techniques such as SEM, TEM, TGA, EDS, XRD, FTIR, and PL spectroscopy. The results indicate significant UV absorption (250–400 nm), strong visible photoluminescence (300–500 nm), and notable anti-Stokes emission (∼420 nm) under 800 nm excitation. Additionally, the composites exhibit remarkable thermal stability and hydrophobicity, making them promising candidates for applications in optoelectronic devices, photovoltaic systems, and high-resolution display technologies.

Synthesis and properties of the natural ultraviolet absorber gadusol in Komagataella phaffii

Gadusol, an efficient natural ultraviolet (UV) absorbing substance with antioxidant capacity, is ubiquitous in aquatic organisms such as microorganisms, algae, and fish eggs. In order to address issues such as its low natural extraction yield and environmental unfriendliness, we introduced the gadusol synthesis pathway from zebrafish into Komagataella phaffii and successfully constructed the recombinant strain capable of synthesizing gadusol. The xylose assimilation genes derived from Scheffersomyces stipitis were further introduced into the recombinant strain to increase the content of the key substrate sedoheptulose 7-phosphate (S7P). The results showed that the utilization of xylose was an effective strategy to increase the yield of gadusol. In the medium with only xylose as the substrate, the yield of gadusol reached 141.8 mg/L (32.3 mg/g dry cell weight, DCW), which was about 46 times of that in the medium with only glucose as the substrate. The product showed obvious absorption in the range of 275-305 nm, with the maximum absorption at 290 nm. Moreover, the product demonstrated antioxidant capacity. After reaction for 5 h, the ferric ion reducing antioxidant power (FRAP), 2, 2'-azino- bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rates changed by 90.83%, 25.50%, and 131.80%, respectively, which suggested that the product may be used as a long-acting antioxidant. This study demonstrated the great potential of K. phaffii as a chassis for the biosynthesis of natural UV absorbers. The biosynthesized gadusol has good UV absorption and antioxidant properties, which provides a theoretical basis for the industrial production and application of gadusol.

Biocompatibility and Haemocompatibility Assessments of RBC with Polymeric Coated Cardiac Stent.

The current investigation was conducted to evaluate the biocompatibility and hemocompatibility of polymeric-coated cardiac stents. Coronary stents are typically small wire mesh tubes that are used to open arteries that are obstructed over time as a result of the buildup of fat, cholesterol, or other materials. A 10 milliliter isolated blood red blood cell was obtained using the Prozeta cobalt chromium coronary stent, which had the following specifications: stent length = 18 mm, strut thickness = 0.065 mm, expansion range = 2.25 mm to 4.00 mm, and burst pressure = 6ATM. Using an R&amp;D coating equipment, polyethylene glycol (PEG) polymers were applied to the coronary stent. Assessments of the polymeric-coated cardiac stent’s biocompatibility and hemocompatibility were conducted using various evaluation criteria. CAD software has been used to help with the stent’s modeling. According to the supplied catalog, the strut’s thickness and width are calculated to be 0.065 mm and its length is 18 mm. The histology of RBC in an isolated sample (polymer coated on stent) found at 2000 Rx was examined using a motic microscope. Using a UV-visible spectrophotometer set to 414 wave length, a 10µg/ml solution of RBC in distilled water was scanned at 200–500 nm to measure the UV absorption maximum. The absorbance was found to be 0.8312 nm. An FTIR analysis of RBC reveals absorptions that include bending and stretching vibrations. Peak Position was discovered at wave numbers 3661.76, 1684.62, 1547.98, 1472.07, 1278.06, and 841.98. Using SEM the surface morphology of RBC was study and it was found the measurements 6.1, 4.2, 3.3, 3.2, 3.1, and 2.2 µm in diameter with standard error 0.548584. It has been determined that PEG-coated material demonstrated significant outcomes that resulted in coronary stent that was both biocompatible and hemocompatible of polymeric-coated cardiac stent, which is a step towards altering the treatment regimen.

Harnessing the synergistic power of lignin-Ecoflex blends for enhanced performance in food packaging

In this study, a two-step chemical modification method was applied to lignin, enabling the thermal blending of lignin and Ecoflex® (PBAT) to produce films for food packaging applications. In the first step, 90 % of phenolic and carboxylic acid groups were converted into aliphatic hydroxy groups via hydroxyethylation, and in the second step, the aliphatic hydroxy groups were esterified with cinnamic acid, introducing abundant phenyl rings as well as unsaturated groups to the polymer. The modified lignin possessed an aliphatic–aromatic structure, similar to Ecoflex®, thereby enhancing the potential miscibility between these two materials. Subsequent experiments revealed that adding 20 % of modified lignin into Ecoflex® film resulted in the most significant improvement in mechanical properties, tripling the stiffness and doubling the strength. The addition of 30 % of modified lignin showed the best outcomes in UV absorption, barrier properties against oxygen and water vapor, and anti-oxidation ability. A strawberry ripening test indicated that the Ecoflex® film containing 30 % of modified lignin extended the shelf-life of strawberries from 2 days to 7 days, with better performance than the results of polyethylene bags and pure Ecoflex® films.

Mechanical and optical properties of MgTa2O6 compounds: First principles study

In this study, we have explored the electronic, optical, and mechanical properties of MgTa2O6 compounds in both tetragonal and orthorhombic phases using the first principles based on density functional theory (DFT) methods. Considering that GGA underestimates the band gap of materials, the HSE06 hybrid functional is performed to get a more accurate result for the band structure and optical property calculations. The calculations indicate that the tetragonal and orthorhombic phases exhibit different optical characteristics, showcasing their potential as exceptional materials for UV absorption. In addition, we have thoroughly investigated the elastic properties of MgTa2O6 for these two phases, including the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio. The results indicate that the tetragonal phase has better volume deformation and shear deformation resistance, and the surface contours of Young's modulus for MgTa2O6 display anisotropy. And according to Pugh's criteria, the tetragonal phase has good ductile properties.

Characterizing biomolecular structure features through an innovative elliptical dichroism spectrometry for cancer detection

This research introduces a novel method for evaluating the structural features of biomolecules, utilizing our innovative Elliptical Dichroism (ED) spectrometer specifically designed for stereochemical analysis. By integrating ED spectrometry with autocorrelation (AC) analysis, we investigate the conformational characteristics of biological molecules such as amino acids, proteins, and extracellular vesicles (EVs) induced by elliptically polarized UV absorption. Our streamlined approach offers a cost-effective and portable solution with minimal sample consumption and supports multiple working modes to efficiently characterize biomolecular structures. The insight from this new approach demonstrates potential applications in using biomolecular characterization for cancer detection.

Silicon surface texturing via TBAB-SDS composite additives enhanced copper-assisted chemical etching

Uneven etching and low fabrication efficiency impede the large-scale applications of copper-assisted chemical etching (Cu-ACE) for texturing light-trapping structures on the surface of silicon wafers. To address this, a composite additive composed of tetrabutylammonium bromide (TBAB) and sodium dodecyl sulfate (SDS) was introduced into the Cu-ACE system. The results indicated that TBAB accelerated the etching rate and improved the texturing uniformity, while SDS enlarged the size of the formed structures and enhanced their ultraviolet light absorption efficiency. The prepared inverted pyramid structure reduced the reflectivity of the silicon wafer surface to 3.8 %, thus exhibiting efficient light-trapping capabilities. The etching evolution under various TBAB concentrations and different HF/H2O2 ratios was studied by characterizing the surface contact angle and copper deposition morphology. The results indicated that electrostatic attraction between TBAB and dangling bonds on the silicon wafer surface enhanced material transfer at the reaction interface and changed the electron distribution around dangling bonds, thus facilitating the catalytic metal attack on these bonds. The copper ion reactivity was decreased due to complexation between the dissociated alkyl sulfate ions of SDS and copper ions, which favored the deposition of larger copper nanoparticles during etching, thereby increasing the size of structures. This research offers valuable insights to enable the large-scale applications of Cu-ACE.

Assessing excimer far-UVC (222 nm) irradiation for advanced oxidation processes: Oxidants photochemistry and micropollutants degradation

The KrCl* excimer lamp (UV222) is a promising alternative of low-pressure mercury lamp (UV254) for UV-based advanced oxidation processes (UV-AOPs), because it is mercury-free and has high photon energy. But there lacks a comprehensive assessment of UV222-AOPs based on different radicals. Herein, the properties (e.g., oxidant decay and innate radical quantum yield), and micropollutant degradation, were comprehensively studied for representative oxidants (i.e., hydrogen peroxide, persulfate (PDS), monochloramine, and free active chlorine (FAC)) under UV222 irradiation. UV222 outperformed UV254 for the activation of oxidants with 2.6–14.4 times fluence-based kinetic constant (kF). The main reason of enhanced activation varied with oxidants: higher UV absorbance for H2O2, higher innate quantum yield for monochloramine and FAC, and both reasons for PDS. Overall, PDS was the optimum oxidant under UV222 for the degradation of 8 representative micropollutants because of effective promotion of radical formation, as confirmed by radical competitive kinetics and modeling simulations. In real water, UV222/PDS still show advantages than UV254/PDS in terms of micropollutant elimination efficacy (3.2–5.3 times) and energy consumption (33.9 %-57.6 % lower) though it was more inhibited by water constituents via competing for UV222 photons. This study fills gaps in photochemistry knowledge and will facilitate engineering practice of UV222-AOPs.

Growth, optical and thermal properties of YbxSm1-xCa4O(BO3)3 crystals

YbxSm1-xCOB (x = 0.1, 0.2) crystals were grown by the Bridgman method for the first time. The purpose of this paper is to evaluate the application prospect of Yb:SmCOB crystal in quasi-parametric chirped pulse amplification (QPCPA) and frequency-doubling laser. The phase structure, thermal properties and optical properties of Yb:SmCOB were studied, and the density of states of SmCOB crystal was calculated by first-principles. The effective segregation coefficient Keff of Yb0.1Sm0.9COB and Yb0.2Sm0.8COB crystals are 0.89 and 0.88, respectively. The thermal diffusivity and thermal conductivity of Yb:SmCOB decrease with increasing temperature. The specific heat increases with the increase of temperature and eventually tends to be constant. The specific heat of Yb:SmCOB crystal is greater than 0.70 J/(g·K) at room temperature. The transmittance of Yb:SmCOB crystal reaches 87 % in the range of 500 ∼ 900 nm. With the increase of Yb3+ doping concentration, the UV absorption cut-off edge is red shifted. The frequency doubling emission peak of Yb:SmCOB crystal at 490 nm was measured by 980 nm laser. Yb:SmCOB has the characteristics of high transmittance and high specific heat, and has application potential in laser frequency doubling and QPCPA.