Search Results (503)

Using disposable screen-printed electrodes faces major challenges when attempting to monitor a continuous process, especially in systems where there is pronounced adsorption, fouling, degradation, or in cases of irreversible electrochemical reactions. Methylene Blue (MB) exhibits some therapeutic properties and is commonly used as a redox reporter in DNA sensors, but is also considered a toxic pollutant in aquatic systems. MB demonstrates strong adsorption to carbon materials, which prevents its electroanalytical determination in multiple measurements with a single electrode. Our work details direct electrochemical determination of MB with only the native carbon screen-printed working electrode as sensing material and optimization of the analytical method. In batch mode, we significantly improved sensitivity and interelectrode reproducibility by introducing a prepolarization step, but successive measurements in lower concentrations were not feasible due to strong adsorption. A fully customizable, modular flow cell was 3D printed to allow in operando replacement of the planar screen-printed three-electrode system after measurement during continuous flow. As confirmed by mechanical properties testing, the rigid polyacrylate upper section of the flow cell provides structural stability, combined with a flexible TPU lower section which enables effortless sensor hot swapping and effective sealing during flow. With an optimized hot swapping flow detection method, MB was detected via square wave voltammetry with a sensitivity of 65.59 µA/µM and a calculated LOD of 7.75 nM, which outperforms similar systems from the literature. We envisage this approach can be integrated into low-cost continuous environmental monitoring systems or in-line quality control, especially in flow chemistry synthesis. Full article

This paper presents results from statistical tests on random parameters of strength properties of steel used to manufacture corrugated webs for SIN plate girders, depending on the place of specimen cut-out, that is, from the flat section or ridge of the wave. The tests were performed on specimens collected from 12 randomly selected corrugated sheets with thicknesses of 2, 2.5 and 3 mm, provided by the manufacturer of SIN beams. The analysis was used to select variation coefficients of yield strength V_Re = D(R_e)/E(R_e) and partial coefficients of yield strength γ_m for steel in flat and arched parts of the web. Metallographic and Vickers hardness tests were performed. Values of deformations and residual stresses were determined. The close correlation between the influence of the web plate shape and the strength parameters along the web curvature was demonstrated. Analysis of the initiation points of stability loss (IPLS points) revealed that the initiation of stability loss occurs in the area of the flat web sections. In addition to the influence of geometry, the influence of the change in yield strength, as identified in this paper, can be observed. Consideration of random features of yield strength and web thickness can lead to modifications in designing and calculating structures made of SIN girders. Full article

To investigate the cyclic behavior of FRP-reinforced steel fiber reinforced concrete (SFRC) composite walls, this paper proposes a section-based finite spring calculation method (FSCM) to reliably predict the cyclic response of such walls under seismic loads. The proposed model accounts for the bond-slip effect of FRP bars and the confining action of transverse reinforcement in the boundary elements. Numerical calculations were conducted on six composite wall specimens with varying longitudinal bar types, fiber volume fractions, concrete strengths, and axial compression ratios. The results indicate that the established calculation method efficiently characterizes the “pinching” effect induced by the linear-elastic properties of FRP bars, and the obtained hysteretic curves are in good agreement with experimental data. Furthermore, the model accurately predicts the load-bearing capacity and residual displacements of the FRP-reinforced SFRC composite walls. Specifically, the average error of peak load calculation for all specimens ranges from −3.36% to 7.36%, and the predicted residual displacements correlate well with the experimental data. These findings demonstrate the applicability of the proposed model for key seismic performance indicators and provide a reliable basis for the research and engineering application of FRP-reinforced SFRC composite walls. Full article

In the present paper, the Kantorovich modification of the Schurer type of $(\lambda ,q)$-Bernstein operators, which are associated by the shape parameter $-1\le \lambda \le 1$ and the Bézier basis function, is presented. Using Korovkin’s theorem, we establish several local and global approximation properties. Lastly, we calculate the convergence properties for the functions that belong to Peetre’s K-functional and Lipschitz maximum by using the classical modulus of continuity and second-order modulus of continuity. In the last section, graphical and numerical analysis are studied. Full article

Donkey milk has been increasingly studied in recent years and has been proposed to be a functional food. However, its components undergo changes during lactation, including its lipid profile and redox-related properties. This study analyzed the fatty acid composition, antioxidant parameters, and redox-modulating properties of donkey milk from the Bulgarian local donkey breed at three lactation stages (0–30, 31–60, and 61–90 days postpartum). Milk samples from 40 clinically healthy donkeys were grouped by days postpartum. A cross-sectional design with three lactation stage groups was used; one-way ANOVA tested group differences with Tukey’s post hoc test, and associations with days postpartum were evaluated using regression models. Fatty acid methyl esters were analyzed by GC-FID, and the atherogenic (AI) and thrombogenic (TI) indices were calculated. Antioxidant enzymes (SOD, CAT, and GPx-1), GSH, MDA, TAC, and EPR-based redox markers (DPPH, Asc•, ROS, NO•, TEMPOL, and 5-MSL) were analyzed. During lactation, monounsaturated fatty acids decreased (approximately 32% in the first month to ~30% by the third month), while AI increased from ~1.9 to ~2.2, and TI increased to ~2.5. SOD and GPx-1 activities increased with advancing lactation, while total antioxidant capacity decreased (213.4 to 199.7 µmol). DPPH radical scavenging activity remained stable during lactation. EPR-detected ROS and NO• values increased with advancing lactation stage, while thiol-bound 5-MSL decreased, suggesting a shift in the balance between oxidative challenge and antioxidant defense during lactation. Regression modeling confirmed a significant effect of lactation period on multiple compositional and redox-related parameters. Therefore, the stage of lactation should be taken into account when interpreting the biological value, redox stability, and potential functional properties of milk, as well as when developing milk management and yield strategies. Full article

After a shear-type strongly braced steel frame suffers from non-sway buckling, the effective length factor for columns in a non-sway frame should be selected for stability calculations, and the P-δ effect should be considered for second-order analysis. However, an unreasonable design may result if the shear-type bracing cannot be accurately and practically designed to meet the strong bracing requirements. In this paper, an analytical method for the critical bracing design of shear-type strongly braced steel frames is proposed. First, the relationship between the shear-type bracing stiffness and buckling load of structures is analyzed, and then the calculation formula for the story critical bracing stiffness is derived based on the critical bracing stiffness of the separation column. Furthermore, the relationship between the cross-sectional properties of the shear-type brace members and the critical bracing lateral stiffness is established. Based on this, a direct calculation formula for the critical brace area of shear-type strongly braced steel frames is derived. This formula can determine whether a shear-type braced steel frame will experience sidesway or non-sway buckling, thereby providing a basis for selecting the appropriate approach for calculating the column effective length factor and second-order effects. Full article

Accurate intraoperative differentiation between malignant and benign breast tissues, particularly the assessment of lymph node status and tumor margins, is critical for surgical decision-making and prognosis. Traditional histopathological methods, such as frozen section analysis, are time-consuming and labor-intensive. Magnetic Particle Imaging (MPI) is a novel, radiation-free modality that senses the microenvironmental properties of tissues through the dynamic response of magnetic tracers. In this study, we propose a diagnostic method utilizing the higher-order harmonic response of magnetic nanoparticles. Various ex vivo breast tissue samples were immersed in Synomag-50 nanoparticles. Using a custom-built MPI spectrometer (5 kHz excitation, 9 mT amplitude) operating in spectroscopic mode, we implemented a rapid acquisition protocol in which each sample was measured 10 times, with 0.1 s per cycle. We analyzed the magnetic response spectrum and calculated the ratio of the third to the fifth harmonic ($H_3/H_5$). Histological analysis confirmed the effective infiltration of MNPs into the interstitial spaces. The repeated measurement data demonstrated high stability. A distinct stepwise increase in harmonic ratios was observed from normal tissue to tumor-adjacent tissue and finally to malignant tumors. Specifically, malignant samples showed ratios that generally exceeded 2.2, whereas benign samples remained below 2.0. These preliminary findings suggest that the harmonic ratio could serve as a sensitive biomarker reflecting the microenvironmental constraints associated with malignancy. This study validates the feasibility of utilizing MPI signal harmonics as a quantitative metric with rapid signal acquisition capabilities for differentiating benign and malignant lymph nodes. Full article

Background/Objectives: Diabetes is major metabolic disorder and rapidly increasing public health problem globally. The greatest way to reduce diabetic complications is adequate knowledge about the condition. Hence, the primary objectives of this study were to evaluate the psychometric properties of the Simplified Diabetes Knowledge Test—Arabic version (SDKT-A) among Iraqi insulin-dependent diabetic patients. Additionally, the secondary objectives were to assess the associated independent variables and the risk of atherosclerosis and cardiovascular risk event by using atherogenic indices and lipid ratios with the SDKT-A. Methods: A cross-sectional, descriptive study was conducted in primary healthcare clinics. The SDKT was translated into Arabic using forward–backward translation, reconciliation, and pilot testing. Thereafter, psychometric properties of the SDKT-A were evaluated depending on different criteria. Atherogenic indices of Castelli risk indices I and II (CRI-I and II), triglyceride/HDL ratio, non-HDL-C ratio, atherogenic coefficient (AC), and triglyceride–total cholesterol–body weight index (TCBI) were calculated using specific formulas. Results: The SDKT-A questionnaire showed acceptable readability and validity. Cronbach’s alpha test (95% confidence interval) was 0.662 (0.59–0.73). The Pearson correlation coefficient of reliability for test–retest was found to be 0.659. The item difficulty index for most items was between 0.237 and 0.877. The point biserial correlation values ranged from 0.028 to 0.535 with Ferguson’s sigma value equal to 0.962. The content validation results showed a significant content validity ratio (CVR) value for most of the questions, ranging from 0.8 to 1. The content validity index (CVI) value for SDKT-A was found to be 0.98, which showed good agreement between experts. In addition, the exploratory factor analysis with promax rotation identified four domains for the final 20 items of the SDKT-A that explained 41.83% of the scale total variance. The mean score of the SDKT-A was 11.09 ± 3.40. The total score of the SDKT-A was positively and significantly correlated with education level (r = 0.322, p < 0.01). In addition, the total scores of the SDKT-A were negatively and significantly correlated with glycemic control, age, CRI-I, CRI-II, triglyceride/HDL ratio, AC, non-HDL-C ratio, and TCBI. Furthermore, the glycemic control (HbA1c) was positively and significantly correlated with the preventive measures factor (r = 0.175, p < 0.05), and were negatively and significantly correlated with the lifestyle and modification factor (r = −0.169, p < 0.05), diet and monitoring factor (r = −0.158, p < 0.05), and awareness factor (r = −0.149, p < 0.05). Conclusions: This study showed acceptable psychometric properties for the SDKT-A, with low levels of knowledge of diabetic disease in the sample population. Finally, comprehensive and interactive educational programs regarding lifestyle and modification, diet, and monitoring and awareness in primary healthcare centers in Iraq are warranted. Full article

Jiangsu Province is home to the largest area of coastal tidal flat wetlands in China. Impacted by climate change, human activities and other factors, the physicochemical properties and ecological functions of coastal sediments at specific sites have undergone significant changes. Grain size is a key indicator reflecting the physicochemical properties of sediments. However, our current understanding of the grain size distribution characteristics of coastal sediments in Jiangsu and their environmental impacts remains relatively limited. In this study, coastal sediment samples from Jiangsu were systematically collected. The proportion of different components was analyzed, and grain size parameters including mean grain size, kurtosis and sorting coefficient were calculated. Our results showed that the coastal sediments in Jiangsu were dominated by silt, accounting for an average of as high as 85.5%; in comparison, the contents of clay and sand were relatively low, with average proportions of 12.2% and 2.3%, respectively. Among the three coastal cities in Jiangsu, Yancheng exhibited the highest silt content in sediments, but the lowest proportions of sand and clay. Grain size data analysis of the monitoring sections indicates that all three coastal cities in Jiangsu are facing varying degrees of marine erosion. Among them, Lianyungang exhibits a greater extent of marine erosion, whereas specific sites in Yancheng and Nantong are more severely impacted by this process. Analysis of the relationship between grain size and element migration indicated that Nantong, with the highest clay content, has stronger carbon sequestration and pollutant interception capabilities. The results obtained through this large-scale systematic analysis of the grain size of coastal sediments in Jiangsu provide important insights into marine erosion dynamics and support for tidal flat conservation efforts in Jiangsu Province. Full article

The circular economy represents a significant opportunity to enhance the mechanical properties of bituminous mixtures, thereby contributing to sustainable development. This research compares the behaviour of traditional bituminous mixtures with sustainable ones that reuse recycled materials, industrial waste products, or additives that improve mechanical or rheological properties. The methodology employed comprised the acquisition of fatigue resistance laws from 4-point bending tests on prismatic specimens. This facilitated the analytical determination of the number of axles of 13 tons that the section of pavement with sustainable material can support for comparison with the axles supported in the conventional mix. The findings corroborate the utilization of sustainable bituminous mixtures in pavement sections, employing the maximum circularity criterion. The fatigue laws calculated must permit the use of different calculation methods or other applications in green infrastructures, such as cycling lanes or pedestrian areas. On sections with an AADT of between 800 and 25 HV/day, all of the analyzed bituminous mixtures with sustainable materials prolong the service life of the road. There were increases in service life of between 25.5% and 6.6%, respectively, which satisfactorily achieved an increase in pavement service life based on the criterion of maximum circularity. Full article

Given the scarcity of specific instruments to assess parental education in pediatric physiotherapy, this study developed the Parental Education in Physiotherapy Scale (Spanish acronym, EPF) and calculated its preliminary psychometric properties, acceptability, and feasibility. A cross-sectional instrumental study was conducted: the EPF was designed based on a specifications matrix and validated by expert judges in two phases. Then it was administered digitally to 63 physiotherapists experienced in treating children under six years of age. They rated it on a 4-point Likert response scale, and qualitative observations on its clarity, usefulness, and acceptability were collected. The validation showed adequate content validity (I-CVI ≥ 0.86; 31/32 items had I-CVI = 1.00) and high inter-judge agreement (global W = 0.659; p < 0.001). In the pilot study, exploratory factor analysis identified three factors (Collaboration, Capacity-Building, and Reflection) that explained 59% of the variance. After refining it, the final version comprised 18 items, showing high internal consistency (ordinal α = 0.944, ω = 0.934). Acceptability was high (100% found it useful; 98.4% said it facilitated reflection; 95.2% found it clear). Overall, the EPF provides preliminary evidence of validity, internal consistency, acceptability, and feasibility, although larger samples and additional analyses are required for its consolidation. Full article

This work provides the first systematic survey of the two–photon properties of 97 natural 9,10–anthraquinones from plants and fungi. A comprehensive computational dataset of two–photon absorption properties calculated using RI–CC2/aug–cc–pVDZ is presented. Single degenerate photon energies required for two–photon excitation span 491.6–1007.9 nm across the five lowest singlet states, with all S₀→S₁ transitions falling within the biological therapeutic window. Remarkably, S₃ state exhibits systematically enhanced TPA efficiency, with 60% of compounds surpassing 1 GM and achieving a mean cross–section of 29.9 GM–substantially higher than S₁ (mean: 7.5 GM). Three compounds demonstrate exceptional performance: cynodontin (73.6 GM, S₂), dermocybin (68.7 GM, S₄), and morindone (50.7 GM, S₃). Orbital analysis reveals that these excitations possess high configurational purity and diagnostics validating the single–reference treatment. The observed spatial separation between hole and particle NTOs, combined with extreme transition dipole anisotropy along the molecular long axis, indicates dipolar charge–transfer enhancement. Comprehensive structure–property analysis establishes that strategic modification may maximise TPA cross–sections. Comparison with aqueous–phase calculations for three compounds reveals non–systematic solvent–induced redistributions of TPA activity across excited states, indicating that gas–phase outcomes serve primarily as internal benchmarks and intrinsic descriptors of structure–property relationships rather than quantitative predictors of photoactivity. Full article

Some cast metallic alloys for ultra-high-temperature structural applications can have better mechanical properties compared with Ni-based superalloys. Research on the directional solidification (DS) of such alloys is limited. The production of DS components of these alloys with “tailor-made” microstructures in different parts of the component has not been considered. This paper attempts to address these issues. A bar of the RCCA/RM(Nb)IC with nominal composition 3.5Al–4Crc6Ge–1Hf–5Mo–36Nb–22Si–1.5Sn–20Ti–1W (at.%) was directionally grown using OFZ processing, where the growth rate R increased from 1.2 to 6 and then to 15 cm/h. The paper studies how the macrosegregation of the elements affected the microstructure in different parts of the bar. It was shown that the synergy of macrosegregation and growth rate produced microstructures from the edge to the centre of the OFZ bar and along the length of the OFZ bar that differed in type and chemical composition as R increased. Contamination with oxygen was confined to the “root” of the part of the bar that was grown with R = 1.2 cm/h. The concentrations of elements in the bar were related (a) to each of the parameters VEC, Δχ, and δ for different sections, (i) across the thickness and (ii) along the length of the bar, or to each other for different sections of the bar, and demonstrated the synergy and entanglement of processing, parameters, and elements. In the centre of the bar, the phases were the Nb_ss and Nb₅Si₃ for all R values. In the bar, the silicide formed with Nb/(Ti + Hf) less or greater than one. There was synergy of solutes in the solid solution and the silicide for all R values, and synergy and entanglement of the two phases. Owing to the synergy and entanglement of processing, parameters, elements, and phases, properties would “emerge” in each part of the bar. The creep and oxidation properties of the bar were calculated as guided by the alloy design methodology NICE. It was suggested that, in principle, a component based on a metallic UHTM with “functionally graded” composition, microstructure and properties could be directionally grown. Full article

A novel dual-face hot-roll inlaying technique was developed to fabricate a Ag/Cu through-layered composite for use in melt elements for fuse production, including two stages of grooving in a Cu strip followed by separate inlaying of Ag strips at the same positions on the opposite surfaces. The microstructure was characterized using field emission scanning electron microscopy (FE-SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and selective area electron diffraction (SAED). The Ag/Cu interfaces are flat and well bonded, with an elemental interdiffusion layer of less than 2 μm. The same textural components—copper, brass, and S-type components—were identified in both the Ag and Cu layers. However, no well-matched crystal orientation relationship between Ag and Cu was detected at the interface. Moreover, tensile properties and electrical resistance were measured to evaluate the bonding strength and conductivity of the interface. It was found that Ag/Cu bonding strength surpassed the tensile strength of Ag, i.e., 260 MPa. While the total elongation is less than 1%, the Ag layer exhibits excellent plasticity, with a section shrinkage over 90%. Compared with the calculated resistivity with a series circuit model, the tested value of the composite sample, including six Ag/Cu interfaces, increased by only 6.6%, indicating good conductivity of the Ag/Cu interface. Therefore, the obtained composite is a promising candidate for the fabrication of melt elements. Full article

Currently, unreinforced steel fiber-reinforced concrete (USFRC) has not been widely adopted in underground engineering within China. However, extensive research has demonstrated that incorporating steel fibers can effectively enhance the mechanical properties of concrete, such as tensile strength, shear strength, residual flexural tensile strength, and also improve its durability. This study, based on the Qiandong experimental section of Dalian Metro Line 4, aims to investigate the failure modes, bearing capacity, and calculation methods for reinforced concrete (RC) and USFRC lining segment joints under compression-bending loading. The objective is to provide a reference for the application of USFRC lining segments in domestic underground engineering. The main conclusions are as follows: (1) The primary failure mode of RC segment joints is large-area crushing of concrete on the outer curved surface, with tensile crack widths on the inner curved surface less than 0.20 mm. The failure mode of USFRC segment joints is characterized by a 2.50 mm wide tensile crack below the loading point. (2) The bolt strain at failure for RC segment joints is approximately twice that of USFRC joints, with both reaching the yield strength and entering the plastic deformation stage. The bolt stress versus bending moment curve exhibits two distinct growth stages. USFRC can effectively control bolt deformation and stress, thereby enhancing bearing capacity. (3) The joint rotation angle versus bending moment curve follows a bilinear model. Under identical bending moments, the rotation angle of RC segment joints is significantly larger than that of USFRC joints. In the two stages, the rotational stiffness of USFRC joints is 367.13% and 763.82% of that of RC joints, respectively. (4) Bolts do not influence the bearing capacity of the segment joints. Existing calculation models in current design codes can accurately predict the ultimate bearing capacity of both RC and USFRC segment joints, demonstrating high prediction accuracy. Full article