Sc Site Research Articles

Assessing the sensing performance of Janus transition metal dichalcogenides (ScSSe, TiSSe and ZrSSe) for oxygen-containing toxic gas molecules such as CO, NO, NO2 and SO2

In this study, the adsorption behavior and sensing capabilities of oxygen-containing gas molecules (CO, NO, NO2, SO2) on Janus ScSSe, TiSSe, and ZrSSe nanosheets have been investigated by using Density Functional Theory (DFT). In order to find the most stable site, two sites (S site and Se site) of the nanosheets have been chosen for gas adsorption. The adsorption energy, charge transfer, work function, and electronic properties have been examined to understand the adsorption behavior. The results show chemisorption for CO, NO, and NO2 gas molecules on ScSSe, at the Sc site with energy −1.52, −1.61 and −1.41 eV respectively. Unlike ScSSe, both TiSSe and ZrSSe show weak physisorption with energy ranges from −0.09 to −0.29 eV, and −0.07 to −0.22 eV respectively. Band structures and Density of States (DOS) indicate the metallic behavior of the nanosheets. Furthermore, the recovery times for CO, NO, and NO2 gas molecules on ScSSe have also been calculated and found that in second range. In the work function calculation, the reduction of work function has been observed after adsorption of CO, NO and NO2 on the ScSSe. Therefore, Janus ScSSe stands out as a promising candidate for detecting CO, NO, and NO2 gas molecules.

Central venous catheter-related infection: does insertion site still matter? A French multicentric cohort study.

We aim to evaluate the association between central venous catheter (CVC) insertion site and microbiological CVC complications in a nationwide cohort. This study was conducted using the healthcare-associated infection surveillance cohort "REA-REZO" involving 193 intensive care units (ICUs). All CVC inserted and removed during the same ICU stay between January 1st 2018 and December 31st 2022 were eligible but only those whose tips were sent for microbiological analysis were included. Primary objective was to describe CVC insertion sites and subsequent catheter-related bloodstream infection (CRBSI). Out of 126,997 CVCs, 71,314 were not sent for tip culture, and only 55,663 CVCs were included, (30,548 in internal jugular [IJ], 14,423 in femoral and 10,692 in subclavian [SC] sites). The incidence of CRBSI was 0.7 [0.6-0.8] in the IJ site, 0.7 [0.6-0.9] in the femoral site, and 0.6 [0.4-0.7] CRBSI per 1000 CVC days in the SC site (p = 0.248). The multivariable Poisson regression model showed no differences of CRBSI incidence rates between the three insertion sites. Microorganisms observed in CRBSI were coagulase-negative Staphylococci (27.9%), Enterobacterales (27.5%), non-fermenting Gram-negative Bacilli (10.4%), Candida sp. (16.9%), and Staphylococcus aureus (16.9%). Low CRBSI incidence rates were reported. CRBSI incidences rates were similar in the three insertion sites. Uncertainty remains due to potential selection bias since many CVCs had to be excluded.

Robustaflavone as a novel scaffold for inhibitors of native and auto-proteolysed human neutrophil elastase

ABSTRACT Human neutrophil elastase (HNE) plays a key role in initiating inflammation in the cardiopulmonary and systemic contexts. Pathological auto-proteolysed two-chain (tc) HNE exhibits reduced binding affinity with inhibitors. Using AutoDock Vina v1.2.0, 66 flavonoid inhibitors, sivelestat and alvelestat were docked with single-chain (sc) HNE and tcHNE. Schrodinger PHASE v13.4.132 was used to generate a 3D-QSAR model. Molecular dynamics (MD) simulations were conducted with AMBER v18. The 3D-QSAR model for flavonoids with scHNE showed r 2 = 0.95 and q 2 = 0.91. High-activity compounds had hydrophobic A/A2 and C/C2 rings in the S1 subsite, with hydrogen bond donors at C5 and C7 positions of the A/A2 ring, and the C4’ position of the B/B1 ring. All flavonoids except robustaflavone occupied the S1’-S2’ subsites of tcHNE with decreased AutoDock binding affinities. During MD simulations, robustaflavone remained highly stable with both HNE forms. Principal Component Analysis suggested that robustaflavone binding induced structural stability in both HNE forms. Cluster analysis and free energy landscape plots showed that robustaflavone remained within the sc and tcHNE binding site throughout the 100 ns MD simulation. The robustaflavone scaffold likely inhibits both tcHNE and scHNE. It is potentially superior to sivelestat and alvelestat and can aid in developing therapeutics targeting both forms of HNE.

New Phases in the Sc−Mn−Si and Sc−Mn−Al−Si Systems Through Molten Indium Flux Synthesis

New Phases in the Sc−Mn−Si and Sc−Mn−Al−Si Systems Through Molten Indium Flux Synthesis

The germanides ScTGe2 (T = Fe, Co, Ru, Rh) – crystal chemistry, 45Sc solid-state NMR and 57Fe Mössbauer spectroscopy

Abstract The TiMnSi2-type (space group Pbam) germanides ScTGe2 (T = Fe, Co, Ru, Rh) were synthesized from the elements by arc-melting. Single crystals were grown by annealing sequences of the arc-melted buttons in an induction furnace. The structures of ScFeGe2, ScRuGe2 and ScRhGe2 were refined from single-crystal X-ray diffraction data. In ScRuGe2, the ruthenium atoms have distorted octahedral germanium coordination (242–268 pm Ru–Ge). Three trans-face-sharing octahedra form a sub-unit which is condensed via common edges in c direction and connected via common corners with four adjacent blocks, forming a three-dimensional [RuGe2 type] substructure. The two crystallographically independent scandium sites have coordination numbers 15 (Sc1@Ge8Ru4Sc3) and 17 (Sc2@Ge7Ru6Sc4). Electronic band structure calculations for ScCoGe2 and ScRuGe2 show a net charge transfer from the scandium to the transition metal and germanium atoms, leading to a description with polyanionic networks Sc δ+[TGe2]δ−. The two crystallographically independent Sc sites are easily distinguishable by 45Sc magic-angle spinning (MAS)-NMR spectroscopy. Isotropic chemical shift values and nuclear electric quadrupolar interaction parameters were deduced from an analysis of the triple-quantum (TQ)-MAS NMR spectra. The electric field gradient parameters deduced from these experiments are in good agreement with quantum-chemical calculations using the Wien2k code. Likewise, the two crystallographically independent iron sites in ScFeGe2 could be discriminated in the 57Fe Mößbauer spectra through their isomer shifts and quadrupole splitting parameters: δ = 0.369(1) mm s−1 and ∆E Q = 0.232(2) mm s−1 for Fe1 and δ = 0.375(2) mm s−1 and ∆E Q = 0.435(4) mm s−1 for Fe2 (data at T = 78 K).

Chemical bonding effects in Sc compounds studied using X-ray absorption and X-ray photoelectron spectroscopies.

Advances on understanding the nature of the chemical bonding and electron correlation effects during the X-ray absorption process in ionic-covalent metal complexes has been achieved for most of the transition elements, except for scandium, due to the lack of a systematic series of spectroscopic reference spectra and the shortage of standard crystallographic data on scandium compounds. To close the gap, the chemical bonding effects in eight Sc compounds are studied using X-ray absorption spectroscopy (XAS) at Sc K and L2,3 absorption edges and X-ray photoelectron spectroscopy (XPS). Indeed, the fine structure of the XAS Sc K edge reflects the chemical sp3-like bond formed between scandium and the ligand while the L2,3 edge and the pre-edge features of the K-edge provide a direct insight into the crystal field parameters at the Sc site in the coordination compound. The XPS data provide the information on binding energies of the core electrons involved in the electron transitions caused by the absorption of high energy X-rays. XAS and XPS complement each other by accessing the information on Sc structure on bulk and the surface. Herein, comprehensive information on the electronic structure of well-known crystalline materials based on Sc is given with spectroscopic fingerprints X-ray data. This will help to predict the formation of chemical bonds in the unknown components via the systematic evaluation of the available spectroscopic fingerprints.

Pure and Sc-doped diopside (CaMgSi2O6) vibrational spectra: modelling and experiments.

We investigated the structure of pure and Sc-doped synthetic diopside (a monoclinic single-chain silicate nominally CaMgSi2O6); in Sc-doped diopside, Sc3+ substitutes Mg2+ in the structure and, to achieve charge balance, vacancies form at the expense of Ca2+. We compared the structure obtained from ab initio modelling techniques at the density functional theory (DFT) level with the structure solved by employing single crystal X-ray diffraction. Furthermore, we compared IR and Raman spectroscopy experiments with vibrational density of states (VDOS) calculated from the Fourier transform of the velocity autocorrelation function obtained using ab initio (DFT) molecular dynamics simulations. In this framework, we developed a computational tool to assign the vibrational mode associated with a specific frequency. This method consists of projecting velocities along a specific set of internal coordinates such as stretching or bending, in cases involving defects or vacancies, to calculate a partial VDOS (pVDOS) that takes into account only the vibrations associated with selected internal modes, aiding the interpretation of the total VDOS and the experimental spectra in a relevant way. The computed data were validated with the experiments and we observed that doping the diopside structure with Sc produces peak broadening and the occurrence of new peaks in the Raman spectra and that site vacancies are associated with the nearby Sc site. The present work constitutes an interesting starting point to exploit the calculated VDOS/pVDOS to characterize experimental vibrational spectra of complex systems containing local vacancies, substitutions or defects as the Sc-doped diopside.

ScFeSb3S7: Synthesis and characterization of a new mixed-metal sulfide

Mixed transition metal chalcogenides are pursued for various semiconducting applications. Herein, we report a new mixed transition metal containing quaternary chalcogenide, ScFeSb3S7, which has been prepared by a high-temperature reaction of elements at 1173 K. A single-crystal X-ray diffraction study shows that the monoclinic ScFeSb3S7 structure (space group: C2/m) is disordered with a mixed Sc and Sb site. The lattice parameters of the structure are a = 12.439(5) Å, b = 3.7938(13) Å, c = 11.604(4) Å, β = 106.095(10)°, and Z = 2. The seven unique crystallographic sites of the structure are occupied, which include Fe1, Sb1, mixed Sc1/Sb2, and four S sites. Each of the Fe1 and Sc1/Sb2 atoms is coordinated with six neighboring sulfur atoms in an octahedral fashion, whereas the Sb1 atom occupies the center of a distorted square pyramidal geometry of the S atoms. The (Sc1/Sb2)S6, FeS6, and SbS5 units are the primary building blocks of the ScFeSb3S7 structure. Both resistivity and optical absorption [Eg = 1.5(1) eV] studies confirm that the ScFeSb3S7 is a semiconductor. A thermal conductivity (ktot) study shows that the polycrystalline sample is a poor thermal conductor with an ultralow ktot value of ∼0.30 W/mK at 773 K. DFT studies also indicate the semiconducting nature of the ScFeSb3S7. The COHP analyses suggest stronger bonding interactions between Sb and S than the Sc/Fe with the S atoms.

Uncovering the kinetics of Li-rich clusters and monodisperse core–shell Al3(Zr, Sc) structures in Al–Li–Cu alloys

The size distribution and structural evolution of the precipitates are critical to the mechanical properties of heat treatable alloys. In Al alloys, many studies have reported that monodisperse core–shell Al3Li/Al3(Zr, Sc) structures in a Li-rich environment promote formation of δ′-Al3Li, T1-Al2CuLi, and θ′-Al2Cu precipitates. However, without quantitative measurements of the precipitate size distribution and tracking their crystal structure evolution, the kinetics of Li-rich clusters and excessive Li diffusion into monodisperse core–shell Al3(Zr, Sc) structures in Al alloys to prevent Li-cluster coarsening is still unknown. In this work, in-situ small angle neutron scattering (SANS) has been adopted to track the evolution of δ′-Al3Li precipitates. Upon quenching, Li-rich clusters remain at a smaller size and higher number density. Once aging starts, nucleation of δ′-Al3Li precipitates on top of Al3(Zr, Sc) is at the expense of dissolution of those Li-rich clusters below the critical size. From density functional theory (DFT) calculations, it has been found the δ′-Al3Li precipitate nucleation barrier on top of Al3(Zr, Sc) is negligible, as well as the nucleation barrier of θ′-Al2Cu on top of Al3(Zr, Sc) is much lower relative to that on α-Al. Besides, the substitutional energy for Li to replace Zr and Sc sites in Al3(Zr, Sc) is favorable. Combining SANS with high-resolution transmission electron microscopy (HRTEM), the effects of Al3(Zr, Sc) cores on preventing δ′-Al3Li size from coarsening by absorbing Li to form Al3(Li, Zr, Sc) have been uncovered. Simultaneously, the contributions of Al3(Li, Sc, Zr) particles and δ′-Al3Li to the strength has been quantified. This work opens a new engineering approach of precise control of precipitating kinetics at the presence of monodisperse precursors for industrially relevant structural materials.

Co-segregation effect of Si and Zr at Al/L12–Al3Sc interface

Reducing the usage of Sc element, as well as improving the thermal stability of nano-precipitate L12–Al3Sc are critical in expanding the application field of Al–Sc based alloys. Previous experiments showed that the impurity Si plays a leading role in accelerating the precipitation and strengthening the thermal stability of Al–Sc-Zr alloy, but the micro mechanism of these effects are not be given at atomic and electron scale. Herein, we performed a first-principles calculations to focus on the segregation behaviors of Si and Zr at Al (001)/L12-Al3Sc (001) interface. The results show that the ahead segregated Si atom, which prefers to occupy the Al site of Al3Sc precipitate side, contributes to induce Zr substituting the Sc atom that is the nearest neighbor of Si rather than the Sc site in Al matrix side. A quantitative calculation suggests that the reduction of Sc usage can at least reach 12 % as the concentration of added Si in Al bulk is about 0.06 %.

Cation defects succeed in triggering super stability of narrow-band blue-emitting phosphors Ca3Sc2Si3O12: Bi3+ for backlighting display application

High-performance white light-emitting diodes (WLEDs) used for backlighting display applications require innovative and thermally stable narrow-band emission phosphors, particularly non-rare-earth Bi3+-activated phosphors. In this study, we demonstrate a defect-engineering strategy to create novel anti-thermal quenching phosphors Ca3Sc2Si3O12: xBi3+ (CSSO: xBi3+). Through structure refinement of CSSO: 0.06Bi3+ phosphor, we found that Bi occupies both Ca and Sc sites in the CSSO lattice. Direct visualization of atomic-resolution TEM and thermoluminescence spectra confirmed the formation of point defects due to the non-equivalent substitution of Ca2+ for Bi3+. Fluorescent-decay analysis revealed that two luminescence sites contribute to the blue-emitting of CSSO:Bi3+ phosphors. CSSO: 0.06Bi3+ phosphor exhibits outstanding thermal stability, with an integrated emission intensity of 103.6% at 423 K compared to that at 298 K. However, the addition of Li or Na as charge compensators reduced cationic defects, leading to a decrease in thermal stability. We believe that VCa″ defects are primarily responsible for the anti-thermal quenching behavior of CSSO: xBi3+ phosphors. An optimized CSSO: 0.06Bi3+ phosphor-based WLED displays a high color rendering index (CRI) of 90 and a wide color gamut (90% National Television System Committee (NTSC) standard), indicating its potential for use in industrial applications as a backlighting display.

Pollutant concentrations and exposure variability in four urban microenvironments of London

We compared various pollutant concentrations (PM1, PM2.5, PM10, PNC, BC) at four different urban microenvironments (MEs) in London (Indoor, IN; Traffic Intersection, TI; Park, PK; and Street Canyon, SC). The physico-chemical characteristics of particles were analysed, and the respiratory deposition doses (RDD) were estimated. Field measurements were conducted over a period of 121 days. The mean PM2.5 (PNC) concentrations were found to be 9.47 ± 7.05 (16366 ± 11815), 8.09 ± 4.57 (10951 ± 6445), 5.11 ± 2.96 (7717 ± 4576), 3.88 ± 3.06 (5672 ± 2934) μg m−3 (# cm−3) at TI, SC, PK and IN, respectively. PM2.5, PM10 and PNC exhibited a trend of TI > SC > PK > IN; higher concentrations for PM1 and BC were observed at IN than PK due to the emissions from printers, producing a trend of TI > SC > IN > PK. We observed 12%–30% higher fine PM concentrations at TI and SC sites during morning peak (07:00–09:30) than the evening peak hours (16:00–19:00); while IN showed a smaller variation in fine PM concentrations compared with outdoor TI, PK and SC sites owing to their prevalence in the IN for a longer time. Fine and ultrafine PM containing potentially toxic trace transition metals including Fe, Ti, Cr, Mn, Al and Mg were detected by high resolution electron microscopy at all sites. There was a similar relative abundance of different elements at the TI, IN and PK sites, which suggests a transport of PM between MEs. RDD for PM1 was highest (2.45 ± 2.27 μg h−1) at TI for females during running; PM2.5 and PM10 were highest at SC (11.23 ± 6.34 and 37.17 ± 20.82 μg h−1, respectively). The results show that the RDD variation between MEs does not follow the PM concentration trend. RDD at PK was found to be 39%–53% lower than TI and SC during running for all the PM fractions. Overall, the study findings show the air quality variation at different MEs and reveals the exposure inequalities around the city, which enable the management of personal exposure by selecting appropriate MEs for different activities.

Application of Probabilistic Seismic Hazard Assessment to Understand the Earthquake Hazard in Attock City, Pakistan: A Step towards Linking Hazards and Sustainability

Within the last three decades, twelve major earthquakes (Mw > 6.0) have jolted Pakistan and contributed to a heavy death toll and an economic loss of billions of dollars, which is immense for any underdeveloped country. Despite the generalized description of seismic hazards in various regions of Pakistan, densely populated cities still require a detailed and integrated vulnerability analysis to overcome the impact of a significant earthquake. This study aims to integrate seismic hazard assessment schemes to understand the vulnerability of Attock city against an earthquake. It initially evaluates the threat from an earthquake due to tectonic activity in the region, splits the region (about 200 km radius) into six seismic zones and uses area source parameters. The ground motion prediction equations compatible with the study area’s seismotectonic environment are also used in this study. Peak horizontal ground acceleration (PGA) and 5% damped spectral acceleration are critical features of ground motions. The site classification is carried within Attock city, indicating the presence of SB (foundation condition with Vs30 = 760 m/s), SC (foundation condition with Vs30 = 400 m/s) and SD (foundation condition with Vs30 = 300 m/s). The peak ground accelerations for a return period of 475 years at the SB, SC and SD sites are estimated as 0.23 g, 0.28 g and 0.30 g, respectively. Uniform hazard spectra are obtained for each site classification at three return periods (475, 975 and 2475 years). Another possible threat can be the local site conditions of the study area, as Attock city exists on the unlithified sediments of upper Pleistocene to Recent alluvial deposits. That is why microtremor recordings are conducted at 20 sites within Attock city to understand the fundamental frequency (f0), horizontal to vertical spectral amplitude (A0) and Kg parameter, a seismic vulnerability index. The values of f0 are found between 0.6 and 9 Hz and A0 is observed between 2.1 and 5 Hz, whereas the Kg is estimated between 0.24 and 20 Hz. Despite evidence of the seismic vulnerability of Attock city, the current building designs and infrastructure development are not synchronized with the uniform hazard response spectra and the soil amplification, thus enhancing the exposure of the study area to disaster during a major earthquake. This study will be instrumental in pre-disaster mitigation strategies for urban planners and policymakers.

Optoelectronic and magnetic properties of transition metals-adsorbed GeC monolayer

The optoelectronic and magnetic behaviors of GeC monolayer after transition metals (TMs) adsorption have been systematically discussed using density functional theory. The calculated data illustrates that the optimal adsorption sites of Sc-, Ti-, V-, Cr-, Mn-, Fe-, and Co-GeC systems are all located at [Formula: see text] site, while the Ni- and Cu-GeC systems are situated in [Formula: see text] site. The band structures of Ti-, Fe-, and Ni-GeC systems still remain nonmagnetic semiconductors, while the Sc-, Cr-, and Cu-GeC systems exhibit magnetic semiconductor behaviors, and the band gaps are 0.11 eV (Sc), 0.30 eV (Cr), and 0.57 eV (Cu), respectively. In particular, V- and Mn-GeC systems exhibit half-metallic characteristics, and Co-GeC system exhibits magnetic metal characteristics. And the magnetic moments of Sc-, V-, Cr-, Mn-, Co-, and Cu-GeC structures have been obtained to be 0.08, 1.00, 2.00, 1.00, 0.04, and 1.00 [Formula: see text], respectively. Furthermore, the charge transfer was exhibited between the GeC and TM. Especially, the work function of GeC can decrease greatly after TM adsorption, among them, the work function of Sc-GeC is 37.9% lower than that of GeC. Consequently, it indicates the usefulness of the TM-GeC system for the fabrication of spintronic and nanoelectronic devices.

Ultra-broadband of up to 200 nm near-infrared phosphors based on one-site occupation strategy for multipurpose applications in light-emitting diodes

Portable near-infrared (NIR) lighting source stimulates great efforts to exploit NIR phosphor-converted LEDs (pc-LEDs) that push the rapid development of broadband NIR-emitting phosphors. Although Cr3+-activated NIR phosphors designed by multisites occupation strategy show significant potential in emission bandwidth, poor spectral stability caused by different thermal quenching behaviors is a brake on practical application due to different local structure around Cr centers. One-site-based NIR phosphors seem to be an effective method to solve aforementioned problem. Herein, we report a type of new ultra-broadband one-site-based NIR-emitting phosphors NaSc1-xP2O7:xCr3+ (NSP:xCr3+) with emission at 910 nm and full width at half maximum (FWHM) of up to ∼200 nm. Their FWHM value exceeds all one-site-based Cr3+-activated phosphors and some multiple-sites ones. Structural analysis and low-temperature spectra demonstrate that such impressive broadband NIR emission originates from Cr3+ occupying at single octahedral Sc site. At 425 K, integrated emission intensity of NSP:0.04Cr3+ phosphor maintains 53.8% of room temperature. A NIR pc-LED prototype is fabricated by using NSP:0.04Cr3+ phosphor with a blue LED chip, and its multipurpose applications in non-destructive detection, night vision and analysis of foodstuff are demonstrated. These findings indicate that broadband NSP:0.04Cr3+ NIR phosphor enabled by one-site occupation strategy has potential prospect for multipurpose NIR pc-LEDs applications.

Mechanistic Modeling of the Effect of Recombinant Human Hyaluronidase (rHuPH20) on Subcutaneous Delivery of Cetuximab in Rats.

To evaluate the duration of effect of rHuPH20 on SC absorption of cetuximab and to develop a mechanistic pharmacokinetic model linking the kinetics of rHuPH20 action with hyaluronan (HA) homeostasis and absorption of cetuximab from the SC space. Serum pharmacokinetics of cetuximab was evaluated after IV and SC dosing at 0.4 and 10mg/kg (control groups). In testgroups,SC cetuximab was administered simultaneously with rHuPH20 (Co-Injection) or 12h after injection of rHuPH20 (Pre-Injection). Mechanistic pharmacokinetic model was developed to simultaneously capture cetuximab kinetics in all groups. Administration of rHuPH20 resulted in a faster absorption of cetuximab; the difference between co-injection and pre-injection groups appeared to be dependent on the dose level. The model combined three major components: kinetics of rHuPH20 at SC site; HA homeostasis and its disruption by rHuPH20; and cetuximab systemic disposition and the effect of HA disruption on cetuximab SC absorption. The model provided good description of experimental data obtained in this study and collected previously. Proposed model can serve as a potential translational framework for capturing the effect of rHuPH20 across multiple preclinical species and inhuman studies and can be used for optimization of SC delivery of biotherapeutics.

Temperature quenching of Cr3+ in ASc(Si1-xGex)2O6 (A=Li/Na) solid solutions

Blue absorbing near infrared (NIR) emitting phosphors are a promising class of materials for phosphor converted NIR LEDs, which can be used in compact NIR spectrometers. Preferably, these phosphors have a broad emission spectrum and show negligible luminescence quenching at LED operating temperatures (100 °C). Here, we investigated ASc(Si1-xGex)2O6 (A = Li/Na, x = 0,0.2,0.4,0.6,0.8,1) solid solutions doped with Cr3+ to tune and optimize the emission maximum and bandwidth to cover the full 700–1100 nm range. With increasing Ge content an emission redshift was observed, along with emission band broadening at intermediate Ge/Si ratio, which is explained by disorder around Cr3+ in the second coordination sphere (mixed Si/Ge). Temperature dependent emission spectra and luminescence decay curves were measured between 90 K and 670 K to determine the quenching temperature TQ. With increasing Ge content TQ drops from 550 K to below 400 K. Interestingly, Cr3+ emission in the highly symmetric site in LiScSi2O6 shows a strongly temperature dependent lifetime before thermal quenching sets in. DFT calculations on LiScSi2O6 indicate that asymmetric vibrations at the Sc site are involved and calculated phonon energies were confirmed by measuring FTIR. Our study indicates that a solid solution is a promising way to increase the emission bandwidth. However, with increasing Ge content TQ decreases. An optimum Ge-content in LiSc(Si1-xGex)2O6:Cr3+ is x = 0.2–0.4 as it redshifts the NIR band maximum close to 900 nm and offers a FWHM bandwidth around 180 nm, while keeping the thermal quenching temperature high enough for application in NIR-LEDs.

Extreme precipitation-based vulnerability assessment of road-crossing drainage structures in forested watersheds using an integrated environmental modeling approach

The goal of this study is to develop geospatial-hydrology models incorporating design rainfall intensities and land morphologic features to identify erosion hazards and vulnerability risks to road culverts/stream crossings in three watersheds at USDA Forest Service long-term experimental forests: i) Coweeta Hydrologic Laboratory, NC, ii) Santee Experimental Forest, SC, and iii) Alum Creek Experimental Forest, AR. These models developed in an ArcGIS ModelBuilder platform were: i) Streambank Erosion Vulnerability Assessment (SBEVA) and ii) Modified Revised Universal Soil Loss Equation (MODIFIED-RUSLE) for potential erosion and streambank vulnerability estimation. The SBEVA model, developed using a Delphi-based weighted-probability scale, and MODIFIED-RUSLE were integrated to identify locations of culverts/stream-crossings morphologically vulnerable to erosion and scouring, which were ground-truthed for the SC site only. As the MODIFIED-RUSLE model does not assess streambank erosion, its integration with the SBEVA helps to develop a better decision-support tool for relevant agencies for safeguarding these road culverts/stream crossings.

The Diel and Seasonal Heterogeneity of Carbonate Chemistry and Dissolved Oxygen in Three Types of Macroalgal Habitats

As concerns about ocean acidification continue to grow, the importance of macroalgal communities in buffering coastal seawater biogeochemistry through their metabolisms is gaining more attention. However, studies on diel and seasonal fluctuations in seawater chemistry within these communities are still rare. Here, we characterized the spatial and temporal heterogeneity in diel and seasonal dynamics of seawater carbonate chemistry and dissolved oxygen (DO) in three types of macroalgal habitats (UAM: ulvoid algal mat dominated, TAM: turf algal mat dominated, and SC: Sargassum horneri and coralline algae dominated). Our results show that diel fluctuations in carbonate parameters and DO varied significantly among habitat types and seasons due to differences in their biological metabolisms (photosynthesis and calcification) and each site’s hydrological characteristics. Specifically, carbonate parameters were most affected by biological metabolisms at the SC site, and by environmental variables at the UAM site. Also, we demonstrate that macroalgal communities reduced ocean acidification conditions when ocean temperatures supported photosynthesis and thereby the absorption of dissolved inorganic carbon. However, once temperatures exceeded the optimum ranges for macroalgae, respiration within these communities exceeded photosynthesis and increased CO2 concentrations, thereby exacerbating ocean acidification conditions. We conclude that the seawater carbonate chemistry is strongly influenced by the metabolisms of the dominant macroalgae within these different habitat types, which may, in turn, alter their buffering capacity against ocean acidification.

Eu2+ Doping Concentration-Induced Site-Selective Occupation and Photoluminescence Tuning in KSrScSi2O7:Eu2+ Phosphor.

Regulation of Eu2+ dopants in different cation sites of solid-state materials is of great significance for designing multicolor phosphors for light-emitting diodes (LEDs). Herein, we report the selective occupation of Eu2+ for multiple cationic sites in KSrScSi2O7, and the tunable photoluminescence from blue to cyan is realized through Eu2+ doping concentration-dependent crystal-site engineering. Eu2+ preferably occupies the K and Sr sites in KSrScSi2O7 at a low doping concentration, resulting in a 440 nm blue emission. As the Eu2+ concentration increases, a new Eu2+ substitution pathway is triggered, that is, Eu2+ enters the Sc site, leading to the red-shifted emission spectra from 440 to 485 nm. The doping mechanism and photoluminescence properties are corroborated by structural analysis, optical spectroscopy study, and density functional theory calculations. The optical properties of the as-fabricated white LEDs are studied, which demonstrates that these phosphors can be applied to full-spectrum phosphor-converted LEDs. This study provides a new design strategy to guide the development of multicolor Eu2+-doped oxide phosphors for lighting applications.