Sr Values Research Articles

Experimental investigation on WEDG machining parameters for tungsten carbide

ABSTRACT This research evaluates the performance of machining tungsten carbide utilizing the wire electric discharge grinding (WEDG) technique. A central composite design based on response surface methodology (RSM) was employed to analyze how various WEDG machining parameters affect the outcome responses material removal rate (MRR), and surface finish (SR). The novelty of this research lies in utilizing the hybrid micromachining WEDG process to machine tungsten carbide rods and in applying the preference-based TLBO method with different weight combinations to obtain optimal solutions. Multiple optimal solutions were derived, enabling decision-makers to select machining parameters that balance SR and MRR. For equal weightage, optimal values of MRR and SR were found to be 5.2647 mm3/min and 2.4541 μm, respectively, at SS = 480.741 rpm, I = 4.4313 A, Toff = 1.297 μs, and Wf = 5.7502 m/min. The TLBO algorithm demonstrated high efficiency and accuracy, with confirmation experiments yielding satisfactory results.

Performance Characteristics of the Quantitative Method for Staphylococcus aureus in Food Products Correspond to ISO 16140-3: 2021

Staphylococcus aureus is a pathogenic bacterium that poses significant health risks when present in food products. High levels of Staphylococcus aureus in food can indicate poor hygiene and handling practices during food production, processing, or storage. In order to maintain food safety and quality, verification of the quantitative method of Staphylococcus aureus is very important. Method verification represents a crucial stage in guaranteeing that all employed procedures conform to the necessary criteria for dependable and precise data. Following the guidelines established in ISO 16140-3:2021, method verification is accomplished through the calculation of the Intralaboratory Reproducibility Standard Deviation (SIR) for implementation validation and the eBias value for verifying the suitability of the method for assessing specific food items. This research was conducted with the objective of confirming the ISO 6888-1:2021 as the designated reference method for quantifying Staphylococcus aureus in food products. For the purpose of confirming the implementation of the method, Cheese was utilized as the test food item. In the context of verifying the method's applicability to different food products, a range of items including condensed milk, margarine, baby porridge, cassava chips and ready-to-eat sausage were examined as challenging foods. Every chosen food item was artificially contaminated with Staphylococcus aureus WDCM 00034. The SIR value obtained was 0.04 ≤ 2× 0.11 (the lowest mean of SR value from ISO 6888-1:2021) which indicated that the National Quality Control Laboratory of Drug and Food (NQCLDF), Indonesian FDA was able to implement the method very well. In addition, the eBias value for all types of food tested was below 0.5log10, which showed that the quantitative method for coagulase-positive Staphylococci (Staphylococcus aureus and other types) could be applied in the NQCLDF laboratory for the extensive scope of food.

Remarkable Near-Infrared Temperature Sensing Properties of Y3Ga5O12:Cr3+ and Y3Ga5O12:Cr3+/Yb3+ Nanotubes Fabricated via a Single-Needle Electrospinning Technique.

For the first time, nanotubes of Y3Ga5O12:Cr3+ (referred to as YGO:Cr3+) and Y3Ga5O12:Cr3+/Yb3+ (referred to as YGO:Cr3+/Yb3+) were produced via a single-needle electrospinning method. The nanotubes of YGO:Cr3+ and YGO:Cr3+/Yb3+ have outer diameters between 190 and 210 nm, whereas the inner diameter ranges between 70 and 80 nm, and the wall thickness ranges from 50 to 60 nm. The temperature sensitivity of YGO:0.02Cr3+ nanotubes was examined by studying how the Cr3+ lifetime changes with temperature. In the temperature range of 303 to 723 K, the peak values of Sa and Sr were 0.274 and 0.0067 K-1, respectively. Temperature sensing properties of YGO:0.02Cr3+/yYb3+ (y = 0.01, 0.02, and 0.05) nanotubes were evaluated via the FIR technique utilizing nonthermally coupled energy levels. The I970/I708 in the YGO:0.05Cr3+/0.01Yb3+ nanotubes displayed a maximal Sr value of 0.013 K-1 at 633 K, which exceeds that of other Cr3+-doped NIR phosphors previously reported and is promising for high-temperature measurements.

Comparison of YAG:Nd3+-Yb3+ nanothermometers synthesized by Pechini and solvothermal methods

Luminescence intensity ratio-based nanothermometry is a widely studied thermal sensing technique in the literature. Regarding biological purposes, it is essential to have thermal probes that are efficient in this type of environment. Thermal bioprobes demand highly crystallized nanocrystals, commonly smaller than 100 nm, with luminescence emissions in the near-infrared range that are not significantly absorbed by biological tissues. Several nanomaterials that have been studied for nanothermometry do not meet the requirements for this type of applications. Accordingly, researches are needed to develop suitable and reliable nanothermometers for thermal sensing. Therefore, our goal was to investigate the impact of Nd3+-Yb3+ co-doping on the thermometric performance of YAG matrix, a promising crystal because it presents a host structure favoring the insertion of lanthanide ions, which provide its luminescent features. In order to achieve this purpose, we first synthesized YAG:Nd3+-Yb3+ nanocrystals through a generic route - called modified Pechini method - to screen their thermal properties. Our results show that YAG:Nd3+-Yb3+ nanocrystals have the potential to work in vivo environments. The nanothermometers investigated here are excited in the first biological window (BW-I) at 805 nm with luminescence emissions within the BW-II, at 1030.5 and 1064 nm. By co-doping the YAG matrix with different Nd3+-Yb3+ concentrations, we studied the energy transfer process between the dopant ions and their impact on thermometry efficiency. By the efficient coupling of the Nd3+-Yb3+ pair, we improved the Sr value by a factor of 3 of YAG compounds up to 0.6 %.K−1. We then synthesized YAG:Nd3+-Yb3+ nanocrystals using a second type of synthesis, by solvothermal means, in order to obtain individual nanocrystals, well dispersed in aqueous solutions, and to adapt their morphology and size for biological purposes. Therefore, we compared the structural and luminescence properties and thermometry efficiencies of YAG:Nd3+-Yb3+ nanocrystals obtained through two distinct processes and showed that the nanothermometry properties are not affected by the synthesis method.

Composite Granitic Plutonism in the Southern Part of the Wadi Hodein Shear Zone, South Eastern Desert, Egypt: Implications for Neoproterozoic Dioritic and Highly Evolved Magma Mingling during Volcanic Arc Assembly

The Abu Farayed Granite (AFG), located in the southeastern desert of Egypt, was intruded during the early to late stages of Pan-African orogeny that prevailed within the Arabian–Nubian Shield. The AFG intrudes an association of gneisses, island arc volcano–sedimentary rocks, and serpentinite masses. Field observations, supported by remote sensing and geochemical data, reveal a composite granitic intrusion that is differentiated into two magmatic phases. The early granitic phase comprises weakly deformed subduction-related calc–alkaline rocks ranging from diorite to tonalite, while the later encloses undeformed granodiorite and granite. Landsat-8 (OLI) remote sensing data have shown to be highly effective in discriminating among the different varieties of granites present in the area. Furthermore, the data have provided important insights into the structural characteristics of the AFG region. Specifically, the data indicate the presence of major tectonic trends with ENE–WSW and NW–SE directions transecting the AFG area. Geochemically, the AFG generally has a calc–alkaline metaluminous affinity with relatively high values of Cs, Rb, K, Sr, Nd, and Hf but low contents of Nb, Ta, P, and Y. The early magmatic phase has lower alkalis and REEs, while the later phases have higher alkalis and REEs with distinctly negative Eu anomalies. The AFG is structurally controlled, forming a N–S arch, which may be due to the influence of the wadi Hodein major shear zone. The diorite and tonalite are believed to have been originally derived from subduction-related magmatism during regional compression. This began with the dehydration of the descending oceanic crust with differential melting of the metasomatized mantle wedge. Magma ascent was long enough to react with the thickened crust and therefore suffered fractional crystallization and assimilation (AFC) to produce the calc–alkaline diorite–tonalite association. The granodiorite and granites were produced due to partial melting, assimilation, and fractionation of lower crustal rocks (mainly diorite–tonalite of the early stage) after subduction and arc volcanism during a late orogenic relaxation–rebound event associated with uplift transitioning to extension.

Up-conversion luminescence and multimodal temperature sensing behaviors in the visible and infrared region of Er3+ and (Er3+, Yb3+) ions in Ca3Ta2Ga3O12 phosphors

Ca3Ta2Ga3O12 - CTGG ceramic phosphors doped with xEr3+ ions, x = (0.1, 1, 3, 5, 7, and 9 at.%) and (5Er, yYb), y = (0.1, 1, 3, 5, and 7 at.%) were investigated. The emission spectra of Er3+ ions were measured under 973 nm and 1550 nm excitations and the optimal concentrations of Er3+ and (Er3+, Yb3+) ions allowing to obtain the maximum emission intensities in the visible range were determined to be 5Er and (5Er, 5Yb), respectively. The best results in terms of correlated color temperature (CCT) and color purity (CRI) were obtained under λex = 973 nm. High values of CCT (between 5000 K and 6000 K) and CRI (in the range of 80 - 92) parameters indicate their potential as efficient materials for white light-emitting diode devices. The temperature dependence of Er3+ luminescence in 5Er:CTGG and (5Er, 5Yb):CTGG samples was investigated by the luminescence intensity ratio for different thermally coupled (TCLs) and non-thermally coupled (NTCLs) levels and the fluorescence lifetime. The highest value of the relative thermal sensitivity parameter (Sr) for 5Er:CTGG sample, Sr = 1.41 % K-1 at 325 K, was obtained from TCLs (2H11/2/4S3/2) under λex = 973 nm. For (5Er, 5Yb):CTGG sample, the highest values of Sr were obtained as follows: Sr = 1.77 % K-1 at 325 K from TCLs (2H11/2/4S3/2), Sr = 1.19 % K-1 at 150 K from TCLs (4I13/2(2)/4I13/2(3)), and Sr = 0.62 % K−1 at 450 K from 4S3/2 lifetime, under λex = 973 nm, and Sr = 1.23 % K-1 at 325 K from TCLs (2H11/2/4S3/2) and Sr = 1.21 % K-1 at 325 K from NTCLs (2H11/2/4F9/2) under λex = 1550 nm. These results indicate that 5Er:CTGG and (5Er, 5Yb):CTGG ceramic phosphors have high potential for applications in the field of optical temperature sensors.

Preparation, upconversion/downshifting emissions, temperature sensing, and thermochromic properties of one-dimensional Y2Zr2O7:Er3+/Yb3+ tube-in-tube nanostructures via single-nozzle electrospinning

One-dimensional (1D) Y2Zr2O7:Er/Yb tube-in-tube nanostructures were prepared via a simple electrospinning technique with a single nozzle. The diameter of the outer tube of the Y2Zr2O7:Er/Yb tube-in-tube nanostructures is 190–170 nm, the thickness of the outer wall is 22–20 nm, the diameter of the inner tube is 120–100 nm, and the wall thickness of the inner tube is 17–14 nm. The optical properties of the Y2Zr2O7:Er/Yb tube-in-tube nanostructures, including the up-conversion and downshifting luminescence spectra, temperature sensitivity, and thermochromic properties, were studied in detail. Under 980 nm excitation, two weak green emissions at 528 nm and 550 nm, as well as a strong red emission at 650 nm of Er ions, are presented. When excited at 378 nm, the Er ions exhibit strong green emission at 545 nm, two weak red emission peaks at 650 and 680 nm, and near-infrared emission peaks at 1400–1600 nm. With increasing environmental temperature, the luminescence color of the 1D Y2Zr2O7:Er/Yb tube-in-tube nanostructures exhibited a transition from “orange→yellow→ green” when excited at 980 nm. For the 1D Y2Zr2O7:xEr/yYb tube-in-tube nanostructures (x = 0.01, 0.02, 0.03; y = 0.05, 0.10, 0.15), the maximum values of Sr are 2.3 % K−1 under 980 nm excitation and 2.1%K−1 under 378 nm excitation within the temperature range of 303–723 K. This work develops integrated multifunctional optical materials and provides an alternative approach for the fabrication of nanoscale smart platforms, advanced displays, and applications in information security.

Assessing pre-season workload variation in professional rugby union players by comparing three acute:Chronic workload ratio models based on playing positions

Quantifying the pre-season workload of professional Rugby Union players, in relation to their respective positions not only provides crucial insights into their physical demands and training needs but also underscores the significance of the acute:chronic workload ratio (ACWR) in assessing workload. However, given the diversity in ACWR calculation methods, their applicability requires further exploration. As a result, this study aims to analyze the workload depending on the player's positions and to compare three ACWR calculation methods. Fifty-seven players were categorized into five groups based on their playing positions: tight five (T5), third-row (3R), number nine (N9), center, and third line defense (3L). The coupled and uncoupled rolling averages (RA), as well as the exponentially weighted moving average ACWR method, were employed to compute measures derived from GPS data. Changes throughout the pre-season were assessed using the one-way and two-way analysis of variance. The results revealed that N9 covered significantly greater distances and exhibited higher player load compared to T5 and 3L [p < 0.05, effect size (ES) = 0.16–0.68]. Additionally, 3L players displayed the highest workload across various measures, including counts of accelerations and decelerations (>2.5 m s−2), accelerations (>2.5 m s−2), acceleration distance (>2 m s−2), high-speed running (>15 km h−1), very high-speed running (>21 km h−1, VSHR), sprint running (>25 km h−1, SR) distance. When using coupled RA ACWR method, centers exposed significantly greater values to T5 (p < 0.05, ES = 0.8) and 3R (p < 0.05, ES = 0.83). Moreover, centers exhibited greater (p < 0.05, ES = 0.67–0.91) uncoupled RA ACWR values for VHSR and SR than T5 and 3R. When comparing the three ACWR methods, although significant differences emerged in some specific cases, the ES were all small (0–0.56). In light of these findings, training should be customized to the characteristics of players in different playing positions and the three ACWR calculation methods can be considered as equally effective approaches.

Structure-Dopant Concentration Relations in Europium-Doped Yttrium Molybdate and Peak-Sharpening for Luminescence Temperature Sensing.

A set of Eu3+-doped molybdates, Y2-xEuxMo3O12 (x = 0.04; 0.16; 0.2; 0.4; 0.8; 1; 1.6; 2), was synthesized using a solid-state technique and their properties studied as a function of Eu3+ concentration. X-ray diffraction showed that the replacement of Y3+ with larger Eu3+ resulted in a transformation from orthorhombic (low doping concentrations) through tetragonal (high doping concentrations), reaching monoclinic structure for full replacement in Eu2Mo3O12. The intensity of typical Eu3+ red emission slightly increases in the orthorhombic structure then rises significantly with dopant concentration and has the highest value for the tetragonal Y2Mo3O12:80mol% Eu3+. Further, the complete substitution of Y3+ with Eu3+ in the case of monoclinic Eu2Mo3O12 leads to decreased emission intensity. Lifetime follows a similar trend; it is lower in the orthorhombic structure, reaching slightly higher values for the tetragonal structure and showing a strong decrease for monoclinic Eu2Mo3O12. Temperature-sensing properties of the sample with the highest red Eu3+ emission, Y2Mo3O12:80mol% Eu3+, were analyzed by the luminescence intensity ratio method. For the first time, the peak-sharpening algorithm was employed to separate overlapping peaks in luminescence thermometry, in contrast to the peak deconvolution method. The Sr (relative sensitivity) value of 2.8 % K-1 was obtained at room temperature.

Radionuclide Solid:liquid partitioning in an aged, reducing-grout wasteform recovered from a disposal facility

The Saltstone Disposal Facility on the Savannah River Site in South Carolina disposes of Low-Level Waste in a reducing-grout waste form. Reducing grout is presently being evaluated as a subsurface disposal waste form at several other locations in the United States, as well as in Europe and Asia. The objective of this study was to collect core samples directly from the Saltstone Disposal Facility and measure desorption distribution coefficients (Kd; radionuclide concentration ratio of saltstone:liquid; (Bq/kg)/Bq/L)) and desorption apparent solubility values (ksp; radionuclide aqueous concentration (moles/L)). An important attribute of this study was that these tests were conducted with actual aged, grout waste form materials, not small-volume simulants prepared in a laboratory. The reducing grout is comprised of blast furnace slag, Class F fly ash, ordinary portland cement, and a radioactive salt waste solution generated during nuclear processing. The grout sample used in this study underwent hydrolyzation in the disposal facility for 30 months prior to measuring radionuclide leaching. Leaching experiments were conducted either in an inert (no oxygen) atmosphere to simulate conditions within the saltstone monolith prior to aging (becoming oxidized) or they were exposed to atmosphere conditions to simulate conditions of an aged saltstone. Importantly, these experiments were designed not to be diffusion limited, that is, the saltstone was ground finely and the suspensions were under constant agitation during the equilibration period. Under oxidized conditions, measured Tc Kd values were 10 mL/g, which was appreciably greater than the historical best-estimate value of 0.8 mL/g. This difference is likely the result of a fraction of the Tc remaining in the less soluble Tc(IV) form, even after extensive oxidation during the experiment. Under oxidized and reducing conditions, the measured Ba and Sr (both divalent alkaline earth metals) Kd value were more than an order of magnitude greater than historical best-estimate values of 100 mL/g. The unexpectedly high Ba and Sr Kd values were attributed to these radionuclides having sufficient time to age (form strong bonds) in the sulfur-rich saltstone sample. Apparent ksp values under reducing conditions were 10−9 mol/L Tc and 10−13 mol/L Pu, consistent with values measured with surrogate materials. Measured apparent Ba, Sr, and Th ksp values were significantly greater than historical best-estimates. The implications of the generally greater Kd values and lower ksp values in these measurements is that these cementitious waste forms have greater radionuclide retention than was previously estimated based on laboratory studies using surrogate materials. This work represents the first leaching study performed with an actual aged, reducing-grout sample and as such provides an important comparison to studies conducted with surrogate materials, and provides high pedigree data for other programs around the world evaluating reducing grouts as a wasteform for subsurface nuclear waste disposal.

Up-conversion luminescence and temperature sensing properties of Ho3+-, Tm3+-, and Yb3+-codoped Bi2WO6 materials in a water environment

A series of x%Ho3+, 5 %Tm3+, y%Yb3+:Bi2WO6 (x = 0, 0.5, 1, 3, 5; y = 0.5, 1, 3) luminescent materials was prepared using a high-temperature solid-phase method. The microstructure, up-conversion luminescence, and temperature sensing properties of the synthesized powders were analyzed. X-ray diffraction patterns revealed that doping with Ho3+, Tm3+, and Yb3+ ions at certain concentrations did not affect the orthorhombic crystal structure of the Bi2WO6 host. Scanning electron microscopy revealed that the morphology of the sample consisted of lumpy particles with a particle size range of 1–5 µm and agglomeration. SEM mapping and energy-dispersive X-ray spectroscopy analyses revealed that each element was relatively uniformly distributed on the particle surface. Under 980 nm excitation (380 mW), the strongest luminescence of the sample was obtained when both Ho3+ and Yb3+ doping concentrations were 1 %. Compared with the luminescence of the 5 %Tm3+ and 1 %Yb3+:Bi2WO6 sample, with increasing Ho3+ concentrations, the luminescence intensity of Tm3+ was first enhanced and subsequently weakened, whereas the luminescence of Ho3+ was significantly weakened, which indicates the positive energy transfer from Ho3+ → Tm3+. At 980 nm (80–380 mW), for the 1 %Ho3+, 5 %Tm3+, and 1 %Yb3+:Bi2WO6 sample, the 538 nm, 545 nm, 660 nm, and 804 nm emission peaks originated from the two-photon absorption. FIR660 nm/804 nm, FIR545 nm/804 nm, and FIR538 nm/804 nm were used to characterize the temperature and corresponded to temperature sensitivities Sr of 0.0046 K−1, 0.022 K−1 and 0.024 K−1 at 573 K, respectively. At 498 K, the minimum temperature resolution δT values were 0.03384 K, 0.03203 K and 0.04373 K. When the temperature increased from 298 K to 573 K, the powder sample luminescence gradually shifted from the yellow-green region to the red region. The results of environmental discoloration and thermochromic performance tests indicate that this sample has potential application in optical anti-counterfeiting. FIR804 nm /660 nm and FIR804 nm /538 nm were obtained for the 40 NTU turbidity suspension under identical excitation conditions. At 298 K, for the 40 NTU turbidity sample, the maximum Sr values were 0.0197 K−1 and 0.0405 K−1; at 340 K, the minimum temperature resolutions δT values were 0.54037 K and 0.66237 K. When the temperature decreased from 340 K to 298 K, the luminescence of the 40 NTU suspension samples gradually shifted from the yellow region to the green region.

Parametric study to implement a water-weakening process in UDEC

Despite the prevalence and validity of the universal distinct element code (UDEC) in simulations in geotechnics domain, water-weakening process of rock models remains elusive. Prior research has made positive contributions to a presupposed link between modelling parameters and saturation degree, Sr. Nevertheless, this effort presents inaccurate results and limited implications owing to the misleading interpretation, that is, devoid of the basic logic in UDEC that modelling parameters should be calibrated by tested macroscopic properties in contrast to a presupposed relation with Sr. To fill this gap, a new methodology is proposed by coupling a computationally efficient parametric study with the simulation of water-weakening mechanisms. More specifically, tested macroscopic properties with different Sr values are input into parametric relations to acquire initial modelling parameters that are sequentially calibrated and modulated until simulations are in line with geomechanical tests. Illustrative example reveals that numerical water-weakening effects on macroscopic properties, mechanical behaviours, and failure configurations are highly consistent with tested ones with noticeable computational expediency, implying the feasibility and simplicity of this methodology. Furthermore, with compatibility across various numerical models, the proposed methodology substantially extends the applicability of UDEC in simulating water-weakening geotechnical problems.

Highly sensitive dual-mode temperature measurement utilizing completely opposite thermal quenching luminescence

In recent years, phosphors have been used in the field of temperature sensing, which has aroused great interest because of its advantages of quick response, high sensitivity and high accuracy. However, exploring optical thermometers with ultra-high sensitivity remains a challenge. In this work, we have designed and synthesized Sm3+ and Mn4+ co-doped La3Mg2NbO9 phosphor for temperature sensing for the first time by utilizing the anomalous thermal quenching property of Sm3+ ions and the sensitive thermal quenching property of Mn4+ ions. Furthermore, the structure, elemental distribution, morphology and optical characteristics of La3Mg2NbO9:Sm3+,Mn4+ were studied in detail. Benefiting from the different responses of the Sm3+ and Mn4+ ions to temperature, the fluorescence intensity ratios of Sm3+ to Mn4+ in La3Mg2NbO9 samples show excellent optical thermometry performance in the range of 303–463 K. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) values of La3Mg2NbO9:Sm3+,Mn4+ sample reach as high as 0.117 K-1 (@463 K) and 4.48 % K−1 (@303 K), respectively. Furthermore, the maximum of Sa is 0.385 K−1 (@463 K) and the maximum of Sr is 4.54 % K−1 (@303 K) based on the fluorescence lifetime temperature measurement method. The temperature cyclotron curve of the sample proves that the sample has excellent stability and repeatability in temperature measurement. These results demonstrate that the designed La3Mg2NbO9:Sm3+,Mn4+ phosphor is promising for the field of non-contact optical temperature thermometry.

“Dynamics of chromophoric dissolved organic matter in the Atlantic Ocean: unravelling province-dependent relationships, optical complexity, and environmental influences”

We report on the spatial distributions and optical characteristics of chromophoric dissolved organic matter (CDOM) in the sea surface microlayer (SML), subsurface seawater (SSW), and water column profiles down to 500 m across a range of Atlantic Ocean biogeochemical provinces during two cruises of the UK Atlantic Meridional Transect program (AMT24 and AMT25). We measured the CDOM absorption coefficient at 300 nm, aCDOM(300), and determined CDOM spectral slopes across two UV wavelength ranges: S1 (275-295 nm) and S2 (350-400 nm). We used spectral slope ratios (SR: S1/S2) to infer CDOM source characteristics and transformation history. During both cruises, SML aCDOM(300) was highest in the Northern Hemisphere, particularly in the North Atlantic Drift Region (NADR). CDOM was always enriched in the SML, with enrichment factors (SML aCDOM(300) / SSW aCDOM(300)) ranging from 1.03 to 2.00, reflecting preferential accumulation of CDOM in the SML. We also found a significant inverse correlation between aCDOM(300) and S1 in both the SML (Spearman’s rank correlation coefficient, r2 = -0.75, p &amp;lt; 0.001, n = 114) and water column profiles (r2 = -0.74, p &amp;lt; 0.001, n = 845). Biogeochemical province-dependent variations in the relationships between CDOM and chlorophyll a were also observed. In high-latitude regions, elevated aCDOM(300) and low SR values indicated a dominance of terrestrially-derived CDOM, whereas oligotrophic subtropical areas showed lower aCDOM(300) and higher SR values, suggestive of aged, refractory, and photodegraded biologically-derived CDOM. Taken together, these findings reveal a complexity of drivers affecting CDOM distributions and spectral properties, which may limit the use of CDOM in predictive relationships in the oceans. However, the potential use of chlorophyll a as a CDOM proxy may prove most successful in open ocean regions devoid of terrestrial inputs, where biological production predominates.

Energy transfer and a novel SBR thermometry of SrY2O4:Sm3+/Eu3+ phosphor based on redshift of charge transfer band edge

In this study, a solid-state reaction was employed to synthesize SrY2O4: Sm3+, SrY2O4: Eu3+ and SrY2O4: Sm3+/Eu3+ phosphors. An intriguing redshift phenomenon from charge transfer band (CTB) edge was investigated for single-band ratiometric (SBR) thermometry applications. The phosphors synthesized exhibited an orthogonal CaFe2O4 structure with Pnam (62) space group. The Y3+ sites from host lattice were most likely to be replaced by Sm3+/Eu3+ ions. The sample of SrY2O4: 0.03 Sm3+/0.3Eu3+ showed a large degree of agglomeration with elongated particles, having an average size of approximately 4 μm. The energy bandgap decreased due to increased surface imperfections, resulting in enhanced defect level concentration. The dipole-dipole interaction could be used to explain energy transfer (ET) of Sm3+-Sm3+ and Sm3+-Eu3+. Furthermore, the energy transfer (ET) efficiency of Sm3+→Eu3+ in Sr2YO4 reached 77.7 %. The sample exhibited a good thermal stability (90.956 %@423 K) with Ea of 0.31 eV, which was an important parameter for broadening thermometry range. A thermometry strategy utilized this redshift phenomenon from CTB edge with anti-thermal quenching behavior and other peaks or bands with thermal quenching was therefore proposed. The high Sr value of 1.533 % K−1@298 K provides a great potential for optical thermometry application, contributing significantly to the advancement of single band ratiometric thermometry technologies.

Distribution, Source, and Contamination of Heavy Metals in Coastal Sediments of Jeddah, Red Sea, Saudi Arabia.

The study investigates heavy metal (HM) contamination in coastal sediments of Jeddah along Red Sea coast, analyzing spatial distribution and sources. 24 samples underwent (ICP-AES) for Fe, Al, Mn, Ni, Pb, Zn, Cu, Cr, Co, Sr, V, and As. HM averages followed Fe ˃ Al ˃ Sr ˃ Mn ˃ Zn ˃ V ˃ Cu ˃ Ni ˃ Cr ˃ As ˃ Co ˃ Pb. Contamination indices revealed severe Sr enrichment, minor As and Co enrichment, and no enrichment for other HMs. Sediment quality guidelines suggest Ni, Cu, Zn, and As risks to benthic communities at some sites, while Cr and Pb pose minimal risk. Multivariate analysis indicates natural sources for Fe, Al, Mn, Ni, Zn, Cu, Cr, Co, and V, and anthropogenic sources for Sr, As, and Pb, linked to agriculture, industry, and urbanization. Increased Sr values may stem from seawater acidification impacting calcitic corals and molluscs.

Comparison of Inter-atomic Pair Potential Curves of different GEAM iterated values for Sr and Ir

In this study, the inter-atomic pair potential curve of Sr and Ir are compared with the potential curve of Rose et al. (1984) using the values predicted in our earlier study (The surface energy calculation for fcc metals with negative Cauchy’s discrepancy using the GEAM), utilizing an EAM model developed by Oni-Ojo et al. (2007) that ha demonstrated efficacy in predicting the low index surface energies of Sr and Ir, both of which have negative Cauchy’s discrepancy.

UČINKI TELOVADBE NA GIBLJIVOST IN MOČ PRI OTROCIH

The aim of this study was to examine the effects of gymnastics training on flexibility and strength parameters of gymnasts. A total of 48 boys aged 5-7 years participated in this study voluntarily. Participants were randomly assigned to two groups (Experimental group n=24; age, height, weight and BMI 6.21±1.10 years, 114.18±19.98 cm, 22.38±4.09 kg, 15.85±1.59 kg/m², respectively; Control group n=24; age, height, weight and BMI (6.87±0.74 years, 114.18±19.98 cm, 22.38±4.09 kg, 15.90±2.72 kg/m², respectively). Standing Long Jump test (SLJ), Bent Arm Hang (BAH), Sit Ups in 30seconds Cruch (SUC), Sit and Reach Flexibility Test (SRF) and Static Flexibility (SF) tests were applied to the experimental and control groups. The training was applied to the experimental group three days a week for 12 weeks, each time for the duration of 90 minutes. A two-way Repeated Measure ANOVA (2×2) was used to test for interactions and main effects for time (pre-test vs. post-test) and group (experimental vs. control) on the dependent physical performance variables. Results showed that there was a statistically significant difference in the TSC and SR values of the experimental group from pre to post-tests (p&lt;0.01, d=0.95, p&lt;0.01, d=0.75, respectively). There were no significant differences in other parameters. According to post-test group difference results, experimental group participants performed better than those in the control group in terms of BAH, SUC, SLJ and SRF values (p&lt;0.02, d=0.780; p&lt;0.04, d=0.614; p&lt;0.00, d=2.11 respectively). As a conclusion, gymnastic training program significantly improved strength and flexibility of gymnasts aged 5-7 years.

Synthesis, luminescent and thermometric properties of the Tb3+ doped Gd2TeO6 phosphor

Gadolinium tellurate phosphor Gd2TeO6 pure and Tb3+ doped were successfully synthesised by solid-state reaction. The crystal structure and photoluminescence properties were characterised by X-ray powder diffraction (XRD) and fluorescence spectroscopy. The influence of Tb3+ concentration on the behaviour of the relative emission intensity and chromaticity coordinates were systematically investigated as a function of energy excitation and temperature. From the Tb3+ emission spectra the CIE (x,y) values and G/B = I(5D4 → 7F5)/I(5D4 → 7F6) ratio were calculated. While the G/B ratio is found temperature independent for all samples, the CIE runs from reddish to greenish region. The thermometric properties are also determined and a good relative thermal sensitivity Sr value 0.98 %K−1 was obtained. The investigation results show that these phosphors could be potentially interesting for use in white light-emitting devices as well as noncontact temperature sensors.

Lie scaling transformations for the analysis of MHD flow with radiation, Soret, and Dufour effects as well as viscous dissipation across a convective surface during triple diffusion

The dynamics of an incompressible, triple-diffusive medium flowing across a linearly stretched surface are examined in this study, taking into account the effects of radiation, viscous dissipation, magnetohydrodynamics (MHD), and the Boussinesq approximation. The work uses simulations to investigate how the combined effects of Soret (thermal-diffusion) and Dufour (diffusion-thermo) phenomena interact with MHD restrictions. Using the Lie-group transformation approach, the goal is to find symmetry reductions in the governing partial differential equations. The method of Runge-Kutta shooting is used to solve the modified system of equations. To show the effects of key factors, such as the buoyancy ratio and magnetic field parameters, a visual analysis is performed. The results show that for both fluid flow scenarios, a rise in the magnetic field parameter causes a drop in the velocity profile, with velocity gradients decreasing by a good percentage. Similar to this, changes in the buoyancy ratio factors cause notable adjustments to the distributions of salt concentrations. When the magnetic parameter varies, the Nusselt number decreases approximately 14.29 %. While interesting behavior is depicted in triple diffusion scenarios, the Nusselt number increase approximately 9.52%. when values of soret effect Sr varies, the percentage of Sherwood number Shr in double diffusion decreases by 40% whereas in triple diffusion the Sherwood number increase interestingly about 33.33%. The precision and dependability of the conclusions are verified by contrasting the simulation results with previously published research.