Search Results (765)

Quercetin, a natural polyphenolic flavonoid with antioxidant and anti-allergic properties, is extensively found in foods and holds significant importance for human health. In this study, a simple switch-off fluorescent sensor based on copper nanoclusters (Cu NCs) was proposed for the sensitive determination of quercetin. Glutathione acted as the reducing and protective agent in the synthesized process of Cu NCs via a facile, green one-pot method. As anticipated, the glutathione-capped Cu NCs (GSH-Cu NCs) exhibited favorable water solubility and ultrasmall size. The fluorescence property of GSH-Cu NCs was further enhanced with Al³⁺ ion through the aggregation-induced emission effect. When quercetin was present in the sample solution, the system exhibited effective fluorescence quenching, which was attributed to the internal filter effect. The GSH-Cu NCs/Al³⁺-based fluorescent sensor showed a good linear relationship to quercetin in the concentration range from 0.1 to 60 μM. A detection limit of 24 nM was obtained. Moreover, the constructed sensor was employed for the successful determination of quercetin in tea samples. Full article

Electrochromic devices (ECDs) capable of modulating both visible color and infrared (IR) emissivity are promising for applications in smart thermal camouflage and multifunctional displays. However, conventional transmissive ECDs suffer from limited IR modulation due to the low IR transmittance of transparent electrodes. Here, we report a reflection-type electrochromic zinc-ion battery (HWEC-ZIB) using a self-doped polyaniline nanorod film (SP(ANI-MA)) as the active layer. By positioning the active material at the device surface, this structure avoids interference from transparent electrodes and enables broadband and efficient IR emissivity tuning. To prevent electrolyte-induced IR absorption, a thermal lamination encapsulation method is employed. The optimized device achieves emissivity modulation ranges of 0.28 (3–5 μm) and 0.19 (8–14 μm), delivering excellent thermal camouflage performance. It also exhibits a visible color change from earthy yellow to deep green, suitable for various natural environments. In addition, the HWEC-ZIB shows a high areal capacity of 72.15 mAh cm⁻² at 0.1 mA cm⁻² and maintains 80% capacity after 5000 cycles, demonstrating outstanding electrochemical stability. This work offers a versatile device platform integrating IR stealth, visual camouflage, and energy storage, providing a promising solution for next-generation adaptive camouflage and defense-oriented electronics. Full article

We describe the output characteristics of a compact, passively Q-switched, diode-end-pumped (Er/Yb):Glass laser operating in a multi-pulse burst mode. Such operation enables much higher optical efficiency and larger output of total energy than possible with conventional solitary pulse emissions. The laser generated a 15-pulse burst of pulses at 1.5 μm with a combined energy of 5.8 mJ. Measurements of pulse energies, spatial mode characteristics, output beam divergence, and impact of thermal effects in the (Er/Yb):Glass are described. These results are compared to predictions of a numerical simulation using a finite-difference beam propagation method (FD-BPM) that incorporates thermal effects caused by distributed local heating in the glass. We show good agreement between the measured and simulated laser output characteristics. Full article

Cemented carbides are among the primary materials for tools and wear parts. Today, energy prices and carbon emissions have become key concerns worldwide. Cemented carbides consist of tungsten carbide combined with a binder, typically cobalt, nickel, or more recently, various high-entropy alloys. Producing tungsten carbide involves reducing tungsten oxide, followed by carburization of tungsten at 1400 °C under a hydrogen atmosphere. The tungsten carbide produced is then mixed with the binder, milled to achieve the desired particle size, and granulated to ensure proper flow for pressing and shaping. This study aims to bypass the tungsten carburizing step by mixing tungsten, carbon, and cobalt; shaping the mixture; and then applying reactive sintering, which will convert tungsten into carbide and consolidate the parts. The mixtures were prepared by planetary ball milling for 10 h under different conditions. Tests demonstrated that tungsten carburization successfully occurs during sintering at 1450 °C for 1 h. The samples exhibit a typical cemented carbide microstructure, characterized by prismatic grains with an average size of 0.32 μm. Densification reached 92%, hardness is approximately 1800 HV30, and toughness is 10.9 ± 1.15 MPa·m^1/2. Full article

Measuring the emissivity of an infrared radiant sample with high accuracy is important. Previous studies reported on the multi- or two-temperature calibration methods, which used a reference blackbody (or blackbodies) to eliminate the background radiation, and assumed that the background radiation was independent of temperature. However, in practical measurements, this assumption does not hold. To solve the above problems, this study proposes a modified two-temperature calibration method and facility. The two temperature points are set in a certain small interval based on the proposed calculation method; based on the indication of the approximation that the emissivities of the sample and the background radiations remain the same at these two temperatures, the emissivities can be calculated with measurement signals at these two temperatures, and a reference blackbody is not needed. An experimental facility was built up and three samples with emissivities around 0.100, 0.500, and 0.900 were measured in (8~14) μm. The relative expanded uncertainties were 9.6%, 4.0%, and 1.5% at 60 °C, respectively, and 8.8%, 5.8%, and 1.2% at 85 °C (k = 2), respectively. The experimental results showed consistency with the results obtained using other methods, indicating the effectiveness of the developed method. The developed method might be suitable for samples whose emissivities are temperature insensitive. Full article

This study investigates the effect of surface oxide control on the phosphatability of ultra-high-strength steel (UHSS) for automotive applications. Surface oxides were manipulated by adjusting the dew point to −50 °C and 0 °C during the annealing process, and the corresponding changes in phosphating behavior were examined. The surface characteristics of the samples were analyzed using X-ray photoelectron spectroscopy (XPS) and field-emission transmission electron microscopy (FE-TEM), while the phosphatability of the samples was evaluated through electrochemical measurements. The sample annealed at a dew point of −50 °C formed continuous Si and Mn oxide films (~10 nm), which significantly suppressed the phosphatability. In contrast, when annealed at 0 °C, internal oxidation occurred along the grain boundaries to a depth of about 3 μm, resulting in the formation of discontinuous Si and Mn oxides on the surface, which greatly enhanced phosphatability. This difference was also supported by OCP measurements: the −50 °C specimen showed a gradual increase in potential, whereas the 0 °C specimen rapidly reached −0.59 V and then stabilized. The findings of this study demonstrate that optimizing the annealing atmosphere provides an effective approach to enhance the phosphating performance of UHSS without the need for additional surface treatments. Full article

Conventional ultraviolet microplasma sources typically lack a back-reflection structure, resulting in radiative power loss from the backside. To enhance the emission efficiency of ultraviolet microplasma devices around 220 nm, we propose a multilayer reflective coating composed of alternating high- and low-refractive-index layers of Al₂O₃ and SiO₂, within a V-shaped groove. Key structural parameters, including the number of alternating film layer pairs, groove width, and light source position, are investigated to show their effects on ultraviolet reflection characteristics. The results show that reducing the groove width greatly enhances light reflection. When the groove width is 6.5 μm, the device exhibits a reflection efficiency of 47.82% and power enhancement of 91.66%, representing improvements of 2.5-fold and 4.2-fold, respectively, compared to non-optimized cases. Device performance is also influenced by the offset of the light source, which is more sensitive along the horizontal direction. This study provides a practical solution for developing high-efficiency ultraviolet emission devices. Full article

Nitrogen-doped carbon dots (NCDs) exhibiting superior fluorescence characteristics were synthesized employing o-phenylenediamine and 2-methylimidazole as precursors. The synthesized NCDs exhibited yellow photoluminescence with an excitation/emission maxima of 410/554 nm with a quantum yield of 28.41%. The presence of pyridinic N, pyrrolic N, graphitic N, and amino N functionalities on the NCDs’ surface provided strong evidence for the successful nitrogen doping of the carbon dots. Upon exposure to hydrogen peroxide (H₂O₂), the NCDs exhibited a significant reduction in fluorescence intensity, which could be restored by the addition of ascorbic acid (AA), demonstrating a quantitative relationship between ascorbic acid and fluorescence efficiency. A novel fluorescence “off–on” system utilizing these NCDs was developed for the quantification of AA. The sensing mechanism relies on H₂O₂-induced fluorescence quenching via the selective oxidation of the NCDs’ surface, followed by fluorescence restoration upon AA addition due to the reduction in surface defects. Meanwhile, further experiments confirmed that the quenching mechanism was static quenching. The NCDs demonstrated a limit of detection (LOD) of 0.605 μM for AA detection. The use of NCDs for AA sensing was validated through the analysis of commercially available beverages. This study aimed to establish a simplified method for ascorbic acid detection. The experimental findings indicated that the developed technique exhibited high accuracy in quantifying ascorbic acid. These findings suggest that the developed NCDs possess considerable potential as a multifunctional sensing tool for various analytical applications. Full article

The shortage of freshwater resources has become the core bottleneck of global sustainable development. Traditional freshwater harvesting technologies are restricted by geographical conditions and environmental limitations, making them increasingly difficult to satisfy the growing water demand. In this study, based on the synergistic coupling mechanism of photothermal conversion and radiative cooling, a solar auto-tracking assisted selective solar absorber and radiative cooling all-weather freshwater harvesting device was innovatively developed. The prepared selective solar absorber achieved a high absorptivity of 0.91 in the solar spectrum (0.3–2.5 μm) and maintained a low emissivity of 0.12 in the mid-infrared range (2.5–20 μm), significantly enhancing the photothermal conversion efficiency. The radiative cooling film demonstrated an average cooling effect of 7.62 °C during typical daytime hours (12:00–13:00) and 7.03 °C at night (22:00–23:00), providing a stable low-temperature environment for water vapor condensation. The experimental results showed that the experimental group equipped with the solar auto-tracking system collected 0.79 kg m⁻² of freshwater in 24 h, representing a 23.4% increase compared to the control group without the solar auto-tracking system. By combining theoretical analysis with experimental validation, this study presents technical and economic advantages for emergency water and island freshwater supply, offering an innovative solution to mitigate the global freshwater crisis. Full article

Background: Soft liners offer a cushioning effect that aids in the healing of inflamed mucosa and allocates the relevant load in the support area of prostheses, enhancing their fit and stability. This study looks at how strontium-infused phosphate bioactive glass affects a heat-cured acrylic-based soft liner, focusing on the surface hardness and the surface roughness of the material. Methods: One hundred soft liner specimens were produced, with fifty specimens being designated for surface hardness testing and fifty specimens for surface roughness testing. PBG*Sr was incorporated into the soft liner at the concentrations of 1 wt.%, 3 wt.%, 5 wt.%, and 7 wt.%. Surface hardness and surface roughness were evaluated with a digital durometer for Shore A hardness and a profilometer, respectively. Fourier transform infrared spectroscopy analysis and field emission scanning electron microscopy were employed. Results: The Shapiro–Wilk test demonstrated that the data adhered to a normal distribution, as the p-values were not statistically significant. Subsequently, for statistical analyses following the one-way ANOVA, Dunnett’s T3 post hoc test was employed for surface hardness, while Tukey’s post hoc test was used for surface roughness. The lowest hardness value was documented in the 7 wt.% subgroup (29.040 ± 0.070), followed by the 5 wt.% subgroup (30.97 ± 0.231), and the control (40.880 ± 0.473) had the highest hardness mean value. The 7 wt.% subgroup displayed the lowest value of Ra recorded, 0.489 ± 0.077 μm, while the control subgroup showed the highest, 1.994 ± 0.168 μm. FTIR analysis suggested that the domination of physical interactions according to the analyses with the FESEM led to improved surface morphology for the 7 wt.% PBG*Sr specimens. Conclusions: The 7 wt.% PBG*Sr specimens exhibited the lowest surface hardness, suitable for soft lining material, and improved the surface morphology of acrylic soft liners compared with the control and other concentrations. Full article

In open-pit mines, substantial amounts of dust are generated at various stages. Due to the long duration, repeated mechanical disturbance, and large volume of material handled during the shoveling and loading of blasting piles, this stage is recognized as one of the primary contributors to overall dust emissions in open-pit mining operations. The objective of this study is to investigate the spatial dispersion characteristics of dust at blasting piles and evaluate the influence of wind direction on dust migration and escape behavior. This study uses a full-scale numerical model to analyze the airflow and dust migration characteristics at blasting piles under different wind directions. Simulation results show that dust particles of different sizes exhibit distinct dispersion patterns: large particles settle near the source, medium particles migrate a moderate distance, and fine particles (PM2.5 and PM10) travel further and are more likely to escape from the pit. The leeward slope and pit bottom are identified as critical zones of dust accumulation and escape. Under both dump-side and stope-side wind conditions, respirable dust (d < 5 μm) accounts for more than 50% of the escaped particles, posing potential health risks to workers. These findings establish a scientific basis for targeted dust suppression strategies, supporting safer and more sustainable mine site management. Full article

Developing resource-efficient technologies for producing ceramic materials with specific properties and performance characteristics is one of the most important tasks in modern materials science. As natural resources face depletion, the use of anthropogenic wastes, including fly ash from coal combustion, for the development of new compositions and the production of ceramics with an improved microstructure is of particular significance. The use of PM₁₀ fly ash microspheres in ceramic production will help to reduce particulate matter emissions. In this study, fine narrow fractions of PM₁₀ microspheres were successfully separated from coal fly ash using aerodynamic and magnetic separation. Glass–ceramic materials with a homogeneous microstructure, an open porosity of 0.4–37%, a compressive strength of 5–159 MPa, and acid resistance of up to 99.9% were obtained using narrow fractions. The materials obtained are promising for application as highly porous ceramics, effective microfiltration membranes, and fine-structured technical ceramics, which can be used in installations operating in aggressive media and/or at high temperatures. The ceramic membranes were characterised by high liquid permeability values up to 1194 L·m⁻²·h⁻¹·bar⁻¹. Filtration tests showed that the retention coefficient for dispersed microsilica particles with d_av = 1.9 μm is 0.99. Full article

The SPICAV IR spectrometer aboard the Venus Express orbiter measured spectra of the 1.1 and 1.18 μm atmospheric transparency windows at the Venus night side in 2006–2014. The long-term measurements encompassed the major part of the Venus globe, including polar latitudes. For the first time, the H₂O volume mixing ratio in the deep Venus atmosphere at about 10–16 km has been retrieved for the entire SPICAV IR dataset using a radiative transfer model with multiple scattering. The retrieved H₂O volume mixing ratio is found to be sensitive to different approximations of the H₂O and CO₂ absorption lines’ far wings and assumed surface emissivity. The global average of the H₂O abundance retrieved for different parameters ranges from 23.6 ± 1.0 ppmv to 27.7 ± 1.2 ppmv. The obtained values are consistent with recent studies of water vapor below the cloud layer, showing the H₂O mixing ratio below 30 ppmv. Within the considered dataset, the zonal mean of the H₂O mixing ratio does not vary significantly from 60° S to 75° N, except for a 2 ppmv decrease noted at high latitudes. The H₂O local time distribution is also uniform. The 8-year observation period revealed no significant long-term trends or periodicities. Full article

This study reports a novel MAX phase material, Mo₂TiAlC₂, as a passively mode-locking (PML) saturable absorber (SA) for a Tm:YAP laser operating in the 2 μm wavelength range. The systematic characterization of its nonlinear optical properties was quantitatively analyzed using I-scan methodology, demonstrating a significant modulation depth of 3.5%, which indicated strong nonlinear optical activity. Within the realm of optimal cavity conditions, a remarkable performance by the PML configuration can be discerned. A stable pulsed emission was manifested at 1937 nm, wherein an average output power reaching 620 mW was achieved. A pulse temporal span of 989.5 ps was acquired with a corresponding repetition frequency of 103.1 MHz, indicating robust mode-locked synchronization. Notably, the beam quality factors (M²) along the orthogonal spatial axes were observed with values measuring 1.12 and 1.18, respectively, indicating propagation characteristics close to those of diffraction-limited beams. Full article

Spectrally selective emitters (SSEs) have attracted considerable attention, because of radiative cooling, which could dissipate the heat from earth to outer space through the atmospheric window without any energy input. Intrinsically inorganic SSEs have significant advantages to other SSEs, such as the low fabrication cost due to the extremely simple structures and long life span under solar exposure. However, few inorganic materials can act as intrinsic SSEs due to the limited emissions in the atmospheric window. Here, we propose a strategy to design intrinsic SSEs by complementing the IR-active phonons in atmospheric window with anion groups. Accordingly, we demonstrate borates containing both [BO₃]³⁻ and [BO₄]⁵⁻ units can exhibit high emissivity within the whole atmospheric window, because the IR-active phonons of [BO₃]³⁻ units usually locate around 8 and 13 μm, while those of [BO₄]⁵⁻ units distribute in 9~11 μm. Furthermore, K₃B₆O₁₀Cl and BaAlBO₄ are selected as two examples to display their near-unity emissivity (>95%) within the whole atmospheric window experimentally. These results not only offer a new strategy for the design of intrinsic SSEs, but also endow wide band-gap borates containing both [BO₃]³⁻ and [BO₄]⁵⁻ units with great potential applications for radiative cooling. Full article