Search Results (16)

The study of crystalline nanosized phosphors KYF₄:Eu³⁺ was carried out for the first time in a range of europium concentrations. The particles were obtained by a modified hydrothermal method. The formation of two different cubic phases (α-KY₃F₁₀ and KYF₄) was detected depending on the ratio of reagents under synthesis conditions. The sizes and shapes of the synthesized particles were determined. For obtained particles, excitation and emission spectra were recorded, luminescence lifetimes and quantum yields were determined, and the mechanism of concentration quenching in these concentration series was disclosed. Full article

This review delves into the forefront of upconversion luminescence (UCL) research, focusing on KY₃F₁₀-based compounds, particularly their cubic α-phase. These materials are renowned for their exceptional luminescent properties and structural stability, making them prime candidates for advanced photonic applications. The synthesis methods and structural characteristics of the existing works in the literature are meticulously analyzed alongside the transformative effects of various doping strategies on UCL efficiency. Incorporating rare earth (RE) sensitizer ions such as Yb³⁺, along with activator ions like Er³⁺, Ho³⁺, Nd³⁺, or Tm³⁺, researchers have achieved remarkable enhancements in emission intensity and spectral control. Recent and past breakthroughs in understanding the local structure and phase transitions of single-, double-, and triple-RE³⁺-doped KY₃F₁₀ nanocrystals are highlighted, revealing their pivotal role in fine-tuning luminescent properties. Furthermore, the review underscores the untapped potential of lesser-known crystal structures, such as the metastable δ-phase of KY₃F₁₀, which offers promising avenues for future exploration. By presenting a comprehensive analysis and proposing innovative research directions, this review aims to inspire continued advancements in the field of upconversion materials, unlocking new potentials in photonic technologies. Full article

The quality of rice, evaluated using multiple quality-related traits, is the main determinant of its market competitiveness. In this study, two japonica rice varieties with significant differences in quality-related traits were used as parents to construct two populations, BC₃F₂ and BC₃F_2:3, with Kongyu131 (KY131) as the recurrent parent. A genetic linkage map was constructed using the BC₃F₂ population based on 151 pairs of SSR/InDel polymorphic markers selected between the parents. Grain-shape-related traits (grain length GL, grain width GW, and length-to-width ratio LWR), chalkiness-related traits (white-core rate WCR, white-belly rate WBR, white-back rate BR, and chalkiness rate CR), and amylose content (AC) were investigated in the two populations in 2017 and 2018. Except for BR and CR, the traits showed similar characteristics with a normal distribution in both populations. Genetic linkage analysis was conducted for these quality-related traits, and a total of 37 QTLs were detected in the two populations. Further validation was performed on the newly identified QTLs with larger effects, and three grain shape QTLs and four chalkiness QTLs were successfully validated in different environments. One repeatedly validated QTL, qWCR3, was selected for fine mapping and was successfully narrowed down to a 100 kb region in which only two genes, LOC_0s03g45210 and LOC_0s03g45320, exhibited sequence variations between the parents. Furthermore, the variation of LOC_Os03g45210 leads to a frameshift mutation and premature protein termination. The results of this study provide a theoretical basis for positional cloning of the qWCR3 gene, thus offering new genetic resources for rice quality improvement. Full article

Combe-Grenal site (Southwest France) was excavated by F. Bordes between 1953 and 1965. He found several human remains in Mousterian levels 60, 39, 35 and especially 25, corresponding to MIS 4 (~75–70/60 ky BP) and with Quina Mousterian lithics. One of the fossils found in level 25 is Combe-Grenal IV, consisting of a fragment of the left corpus of a juvenile mandible. This fragment displays initial juvenile periodontitis, and the two preserved teeth (LLP4 and LLM1) show moderate attrition and dental calculus. The SEM tartar analysis demonstrates the presence of cocci and filamentous types of bacteria, the former being more prevalent. This result is quite different from those obtained for the two adult Neanderthals Kebara 2 and Subalyuk 1, where more filamentous bacteria appear, especially in the Subalyuk 1 sample from Central Europe. These findings agree with the available biomedical data on periodontitis and tartar development in extant individuals, despite the different environmental conditions and diets documented by numerous archeological, taphonomical and geological data available on Neanderthals and present-day populations. New metagenomic analyses are extending this information, and despite the inherent difficulties, they will open important perspectives in studying this ancient human pathology. Full article

Highly efficient quantum cutting KY(CO₃)₂:Tb³⁺ phosphors excited by ultraviolet B (UVB) and ultraviolet C (UVC) were investigated. The structural and spectroscopic properties were characterized by XRD analysis and fluorescence spectrophotometry, respectively. The results showed that the monoclinic crystal structure of KY(CO₃)₂:Tb³⁺ remained in the Tb³⁺ doping range of 0~100%. In the excitation spectrum, two intense excitation peaks were observed in the ultraviolet range. Under the excitation of 283 nm, the maximum quantum efficiency of KY(CO₃)₂:0.7Tb³⁺ could reach 119%. However, the most efficient quantum cutting occurred at the ⁵K₈ excited state in the cross-relaxation of ⁵K₈ + ⁷F₆⁵D₄ + ⁵D₄. The Tb³⁺ content could be selected arbitrarily in the KY(CO₃)₂ host without any concentration quenching. Optimal quantum cutting concentrations of Tb³⁺ in KY(CO₃)₂ were 0.7 and 0.3 for the excitation of UVB and UVC, respectively. UVB-excited phosphors are more popular with high transparency in products such as glass or resin. A quick response code was fabricated by resin to show the hidden information clearly. Therefore, the highly efficient phosphor could be a candidate material for the application in information identification technology. Full article

At present, magnesium master alloys with such rare earth metals (REM) as yttrium are used in the production of alloys of magnesium and aluminum. These alloys especially the system Mg-6Zn-1Y-0,5Zr are commonly used in the aircraft and automotive industries. The article is devoted to the exploration of the synthesis process features for ternary magnesium master alloys with yttrium and zinc. The authors used X-ray fluorescence analysis (XRF), differential thermal analysis (DTA), and X-ray spectral analysis (XRD). Optical microscopy was used to conduct microstructural studies. The thermal effects that occur during metallothermic reactions of yttrium reduction from the YF₃-NaCl-KCl-CaCl₂ salt mixture with a melt of magnesium and zinc were investigated, and the temperatures of these effects were determined. It has been confirmed that the metallothermic reaction of yttrium reduction proceeds from the precursors of the composition: Na_1.5Y_2.5F₉, NaYF₄, Na₅Y₉F₃₂, and KY₇F₂₂, and starts at a temperature of 471 °C. The results of experimental studies of the process of metallothermic reduction of yttrium from the salt mixture YF₃-NaCl-KCl-CaCl₂ are presented in detail. These experiments were carried out in a pit furnace at temperatures ranging from 650 to 700 °C, and it was found that, at a synthesis temperature of 700 °C, the yttrium yield is up to 99.1–99.8%. The paper establishes rational technological regimes for the synthesis (temperature 700 °C, exposure for 25 min, the ratio of chlorides to yttrium fluoride 6:1, periodic stirring of the molten metal) at which the yttrium yield reaches up to 99.8%. The structure of the master alloy samples obtained during the experiments was studied. That structure can be distinguished by a uniform distribution of ternary intermetallic compounds (Mg₃YZn₆) in the bulk of the double magnesium–zinc eutectic. Studies have been carried out on testing the obtained ternary master alloy as an alloying material in the production of alloys of the Mg-6Zn-1Y-0.5Zr system, while the digestibility of yttrium ranged from 91 to 95%. Full article

Summer maize crop development, yield, and water use characteristics under water deficit conditions at different growth stages were investigated in this study using different irrigation regime treatments at the seedling (S), jointing (J), tasseling (T), and grain filling stages (F) in 2018 and 2019 in China. Ten different irrigation treatments were set, including three-irrigation application intervals (JTFi, STFi, SJFi, SJTi), two-irrigation applications (STi, JTi, JFi), and single-irrigation applications (Ti, Ji). These were compared to the control treatment (CK), which had sufficient irrigation provided at four intervals (SJTFi). The results showed that compared to CK, a water deficit at the seedling and jointing stages had a greater effect on plant height, whereas a water deficit at the tasseling and filling stages had a greater effect on the leaf area index, and a continuous water deficit had an effect on the stem diameter of summer maize. Limitations in terms of the growth and development of summer maize increased with less frequent irrigation. As irrigation decreased, the grain yield decreased, and the water use efficiency increased, and a water deficit at the tasseling stage had the greatest effect on the yield and water use efficiency. The JTFi treatment was the optimal irrigation regime with a yield decline, and its water consumption was reduced by 16.9% (p < 0.05) on average. However, compared to CK, the water use efficiency of the JTFi treatment increased by 17.3% (p < 0.05). Moreover, the JTFi treatment had the smallest maize yield response factor value (K_y) of 0.16, and its comprehensive score was the second highest after CK. Full article

Urinary tract infection (UTI) develops after a pathogen adheres to the inner lining of the urinary tract. Cases of UTIs are predominantly caused by several Gram-negative bacteria and account for high morbidity in the clinical and community settings. Of greater concern are the strains carrying antimicrobial resistance (AMR)-conferring genes. The gravity of a UTI is also determined by a spectrum of other virulence factors. This study represents a pilot project to investigate the burden of AMR among uropathogens in East Africa. We examined bacterial samples isolated in 2017–2018 from in- and out-patients in Kenya (KY) and Uganda (UG) that presented with clinical symptoms of UTI. We reconstructed the evolutionary history of the strains, investigated their population structure, and performed comparative analysis their pangenome contents. We found 55 Escherichia coli and 19 Klebsiella pneumoniae strains confirmed uropathogenic following screening for the prevalence of UTI virulence genes including fimH, iutA, feoA/B/C, mrkD, and foc. We identified 18 different sequence types in E. coli population while all K. pneumoniae strains belong to ST11. The most prevalent E. coli sequence types were ST131 (26%), ST335/1193 (10%), and ST10 (6%). Diverse plasmid types were observed in both collections such as Incompatibility (IncF/IncH/IncQ1/IncX4) and Col groups. Pangenome analysis of each set revealed a total of 2862 and 3464 genes comprised the core genome of E. coli and K. pneumoniae population, respectively. Among these are acquired AMR determinants including fluoroquinolone resistance-conferring genes aac(3)-Ib-cr and other significant genes: aad, tet, sul1, sul2, and cat, which are associated with aminoglycoside, tetracycline, sulfonamide, and chloramphenicol resistance, respectively. Accessory genomes of both species collections were detected several β-lactamase genes, bla_CTX-M, bla_TEM and bla_OXA, or bla_NDM. Overall, 93% are multi-drug resistant in the E. coli collection while 100% of the K. pneumoniae strains contained genes that are associated with resistance to three or more antibiotic classes. Our findings illustrate the abundant acquired resistome and virulome repertoire in uropathogenic E. coli and K. pneumoniae, which are mainly disseminated via clonal and horizontal transfer, circulating in the East African region. We further demonstrate here that routine genomic surveillance is necessary for high-resolution bacterial epidemiology of these important AMR pathogens. Full article

ADAMTS13 (A Disintegrin and Metalloprotease with Thrombospondin type 1 repeats, member 13) cleaves von Willebrand Factor (VWF) multimers to limit the prothrombotic function of VWF. The deficiency of ADAMTS13 causes a lethal thrombotic microvascular disease, thrombotic thrombocytopenic purpura (TTP). ADAMTS13 circulates in a “closed” conformation with the distal domain associating the Spacer domain to avoid off-target proteolysis or recognition by auto-antibodies. However, the interactions of the distal TSP8 domain and the Spacer domain remain elusive. Here, we constructed the TSP8-Spacer complex by a combination of homology modelling and flexible docking. Molecular dynamics simulation was applied to map the binding sites on the TSP8 or Spacer domain. The results predicted that R1075, D1090, R1095, and C1130 on the TSP8 domain were key residues that interacted with the Spacer domain. R1075 and R1095 bound exosite-4 tightly, D1090 formed multiple hydrogen bonds and salt bridges with exosite-3, and C1130 interacted with both exosite-3 and exosite-4. Specific mutations of exosite-3 (R568K/F592Y/R660K/Y661F/Y665F) or the four key residues (R1075A/D1090A/R1095A/C1130A) impaired the binding of the TSP8 domain to the Spacer domain. These results shed new light on the understanding of the auto-inhibition of ADAMTS13. Full article

Fluid flow modeling of naturally fractured reservoirs remains a challenge because of the complex nature of fracture systems controlled by various chemical and physical phenomena. A discrete fracture network (DFN) model represents an approach to capturing the relationship of fractures in a fracture system. Topology represents the connectivity aspect of the fracture planes, which have a fundamental role in flow simulation in geomaterials involving fractures and the rock matrix. Therefore, one of the most-used methods to treat fractured reservoirs is the double porosity-double permeability model. This approach requires the shape factor calculation, a key parameter used to determine the effects of coupled fracture-matrix fluid flow on the mass transfer between different domains. This paper presents a numerical investigation that aimed to evaluate the impact of fracture topology on the shape factor and equivalent permeability through hydraulic connectivity (f). This study was based on numerical simulations of flow performed in discrete fracture network (DFN) models embedded in finite element meshes (FEM). Modeled cases represent four hypothetical examples of fractured media and three real scenarios extracted from a Brazilian pre-salt carbonate reservoir model. We have compared the results of the numerical simulations with data obtained using Oda’s analytical model and Oda’s correction approach, considering the hydraulic connectivity f. The simulations showed that the equivalent permeability and the shape factor are strongly influenced by the hydraulic connectivity (f) in synthetic scenarios for X and Y-node topological patterns, which showed the higher value for f (0.81) and more expressive values for upscaled permeability (kx-node = 0.1151 and ky-node = 0.1153) and shape factor (25.6 and 14.5), respectively. We have shown that the analytical methods are not efficient for estimating the equivalent permeability of the fractured medium, including when these methods were corrected using topological aspects. Full article

Background: There are numerous studies assessing the morphological structure of the foot, but there is a notable scarcity of those focused on juxtaposing various longitudinal arch indices with foot loading paradigm. The present study aimed to determine the overall reliability, diagnostic accuracy of respective variables, and their correlation with the foot loading paradigm. Methods: The study group consisted of 336 children, aged 10–15 years (girls 49.1% and boys 50.9%). The morphological structure of the plantar part of the foot in static conditions was assessed with the aid of a 2D podoscan. Individual foot loading paradigm in static conditions was assessed making use of the FreeMed platform. Results: Staheli (SI), Chippaux–Smirak (CSI), and Sztriter–Godunow (KY) indices were strongly correlated with each other (ρ > 0.84, p < 0.001). Own research corroborated an increased pressure of hollow feet, as assessed by the SI, CSI, and KY indices, on the forefoot and the hindfoot, foot zones B, E, F; these correlations being statistically significant. The results yielded by the present study also indicate an increased pressure on the metatarsal, and foot zones C, D of the flat feet. Conclusions: Flatfootedness is not believed to be a common deformity among children and adolescents. The SI, CSI, and KY indices were found to be strongly correlated, as well as proved reliable in assessing the foot’s longitudinal arch. Full article

Cubic KR₃F₁₀ (R = Y, Tb) single crystals have been successfully grown using the Bridgman technique. Growth of crystals of this type is complicated due to the hygroscopicity of potassium fluoride and melt overheating. The solution to the problem of oxygen-incorporated impurities has been demonstrated through the utilization of potassium hydrofluoride as a precursor. In this study, the crystal quality, structure features, and optical, thermal and electrophysical properties of KR₃F₁₀ were examined. Data on the temperature dependences of conductivity properties of KTb₃F₁₀ crystals were obtained for the first time. These crystals indicated thermal conductivity equal to 1.54 ± 0.05 Wm⁻¹K⁻¹ at room temperature caused by strong phonon scattering in the Tb-based crystal lattice. Ionic conductivities of KY₃F₁₀ and KTb₃F₁₀ single crystals were 4.9 × 10⁻⁸ and 1.2 × 10⁻¹⁰ S/cm at 500 K, respectively, and the observed difference was determined by the activation enthalpy of F⁻ ion migration. Comparison of the physical properties of the grown KR₃F₁₀ crystals with the closest crystalline analog from the family of Na_0.5−xR_0.5+xF_2+2x (R = Tb, Y) cubic solid solutions is reported. Full article

During four consecutive growing seasons (2014–2018), field experiments were conducted in the North China to determine winter wheat production function. The field experiments were carried out using winter wheat subjected to four N levels (N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀) and three irrigation levels (I_f, I_0.8f, and I_0.6f). The main aims were to characterize winter wheat productivity, drought response factor K_y, and the winter wheat grain yield production functions in relation to water supply under the different N fertilizer levels. The amount of water supply (rain + irrigation) were 326–434, 333–441, 384–492, and 332–440 mm in 2014–2015, 2015–2016, 2016–2017, and 2017–2018 growing seasons, respectively. Similarly, the values of ET_a (including the contribution from soil water storage) were 413–466, 384–468, 401–466, and 417–467 mm in 2014–2015, 2015–2016, 2016–2017, and 2017–2018, respectively. ET_a increased as the amount of irrigation increased. The average values of I_f, I_0.8f, and I_0.6f over the four growing seasons were 459–465, 432–446, and 404–413 mm, respectively. For the same amount of irrigation, there was only small difference in ET_a among different nitrogen levels; for the three irrigation levels, the values of ET_a in N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀ ranged from 384 to 466, 384 to 466, 385 to 467, and 407 to 468 mm, respectively. Water productivity values ranged from 1.69 to 2.50 kg m⁻³ for (rain + irrigation) and 1.45 to 2.05 kg·m⁻³ for ET_a. The K_y linearly decreased with the increase in nitrogen amount, and the values of r were greater than 0.92. The values of K_y for winter wheat in N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀ were 1.54, 1.41, 1.28, and 1.25, respectively. The mean value of K_y for winter wheat over the three irrigation levels and the four nitrogen levels was 1.37 (r = 0.95). In summary, to gain higher grain yield and WUE, optimal combination of N fertilizer of 180–240 kg·ha⁻¹ and irrigation quota of 36–45 mm per irrigation should be applied for winter wheat with drip fertigation in the North China Plain. Full article

Fusarium head blight (FHB) of wheat (Triticum aestivum L.) results in discolored Fusarium damaged kernels (FDK) contaminated with deoxynivalenol (DON). DON accumulation, a primary measure of FHB resistance, can be used as a basis for selection, but testing each genotype in several genetically variable populations is expensive and time-consuming. Therefore, FHB resistance breeding decisions are routinely based on in-field phenotypic evaluation. However, using an optical sorter as an alternative to in-field evaluation, mass selection (MS) for FHB resistance can be quickly performed post-harvest. The objective of this study was to utilize an optical seed sorter to select breeding lines with enhanced FHB resistance (lower DON and FDK values). Three hundred F₄ derived breeding lines were grown in an inoculated disease nursery over several years in Lexington, KY. Grain from each breeding line was sorted using an optical seed sorter calibrated to reject scabby (discolored) seed. The accepted (non-scabby) seed was used to plant subsequent generations. DON and kernel damage traits were lowered each cycle of line selection with the optical sorter. Our findings suggest that optically sorting grain may be an effective breeding strategy for lowering DON accumulation and limiting kernel damage associated with FHB. Full article

Advances in enzyme stabilization and immobilization make the use of enzymes for industrial applications increasingly feasible. The lactoperoxidase (LPO) system is a naturally occurring enzyme system with known antimicrobial activity. Stabilized LPO and glucose oxidase (GOx) enzymes were combined with glucose, potassium iodide, and ammonium thiocyanate to create an anti-fungal formulation, which inhibited in-vitro growth of the plant pathogenic oomycete Pythium ultimum, and the plant pathogenic fungi Fusarium graminearum and Rhizoctonia solani. Pythium ultimum was more sensitive than F. graminearum and R. solani, and was killed at LPO and GOx concentrations of 20 nM and 26 nM, respectively. Rhizoctonia solani and F. graminearum were 70% to 80% inhibited by LPO and GOx concentrations of 242 nM and 315 nM, respectively. The enzyme system was tested for compatibility with five commercial fungicides as co-treatments. The majority of enzyme + fungicide co-treatments resulted in additive activity. Synergism ranging from 7% to 36% above the expected additive activity was observed when P. ultimum was exposed to the enzyme system combined with Daconil^® (active ingredient (AI): chlorothalonil 29.6%, GardenTech, Lexington, KY, USA), tea tree oil, and mancozeb at select fungicide concentrations. Antagonism was observed when the enzyme system was combined with Tilt^® (AI: propiconazole 41.8%, Syngenta, Basel, Switzerland) at one fungicide concentration, resulting in activity 24% below the expected additive activity at that concentration. Full article