Search Results (577)

To investigate the effect of microalloying on hydrogen embrittlement resistance of hot-stamped steels with strength levels of 1.8 GPa and above, six composition schemes were designed based on conventional 34MnB5 steel, including three routes, namely Nb, V, and Nb–V. U-bend constant-strain bending tests and slow strain rate tensile (SSRT) tests were conducted on quenched specimens for each scheme. Results indicated that the Nb-containing compositions exhibited superior hydrogen embrittlement resistance. The mechanism by which microalloying refines the martensitic microstructure of 34MnB5 in the quenched state and enhances its resistance to hydrogen embrittlement was studied in detail. It was found that Nb exhibits stronger effects than V in refining and homogenizing the martensite structure. The fundamental reasons for Nb’s enhanced ability to pin austenite grain boundaries at high temperatures—leading to better microstructural refinement and homogenization—are its higher temperature range for second-phase precipitation, greater driving force for grain boundary diffusion, lower austenite grain boundary diffusion coefficient, and weaker tendency for high-temperature coarsening of precipitates. The microstructural refinement and homogenization induced by Nb addition are more pronounced than those achieved by combined additions of Nb and V. Furthermore, within the concentration range of 0–0.1%, the amount of Nb is positively correlated with the degree of microstructural refinement and homogenization. By reducing martensite lath size through microalloying, multiple microstructural modifications occur: decreased density of geometrically necessary dislocations (GNDs) in the matrix, significant increase in interface density—especially a higher proportion of high-angle grain boundaries—reduced number of Σ3 special harmful grain boundaries, weakened matrix texture intensity, fewer twin martensites, and smaller twin martensite sizes. These factors collectively contribute significantly to the improved hydrogen embrittlement resistance of Nb-containing steels. Full article

Sulfur dioxide (SO₂) is a preservative used in the production of fermented beverages for its antimicrobial and reducing properties. However, its effect on the oxidation–reduction potential (ORP, redox potential) during alcoholic fermentation of apple cider has never been recorded. In this study, freshly pressed apple juice was fermented with a 30 mg/L free SO₂ addition (RED) and without an SO₂ addition (CON) prior to alcoholic fermentation. Fermentation kinetics, ORP, basic chemistry, organic acids, nitrogenous compounds, free and total SO₂, glutathione (GSH), phenolics, and volatiles were monitored during alcoholic fermentation and at racking. Additionally, sensory analysis was conducted after bottling. Sulfur dioxide had no effect on fermentation kinetics, nitrogen utilization, ethanol yield, or the volatile composition of the apple ciders at racking. The ORP (vs. Ag/AgCl reference electrode) reached maximum values of 310 mV in CON and 218 mV in RED before alcoholic fermentation, and minimum values of −94 mV and −136 mV, respectively, near peak alcoholic fermentation. Mean ORP values during alcoholic fermentation were −29 mV in CON and −47 mV in RED. No statistical differences were found between the ORP of CON and RED using net area under the curve (AUC) of the ORP relative to Y = 0 mV, nor in the GSH chemistry of the ciders. The addition of SO₂ inhibited malolactic fermentation (MLF) during alcoholic fermentation. As a result, higher concentrations of malic acid and lower concentrations of lactic acid were observed in RED than in CON at racking. Sulfur dioxide additions preserved monomeric, dimeric, and increased the pool of sulfonated flavan-3-ols, likely due to PPO inhibition during the prefermentative phase and reactive oxygen species (ROS) quenching. The sensory composition of the ciders was affected whereby CON showed higher banana aroma and RED trended towards reduction aromas. Overall, SO₂ additions before alcoholic fermentation of apple cider preserved phenolics, inhibited MLF, and increased reduction aroma with no clear effect on fermentation kinetics and ORP, highlighting trade-offs between the impact of SO₂ additions on the chemical and sensory attributes of apple cider. Full article

With the growing interest in pandan-based products, bitterness and astringency associated with flavonoids may limit their sensory acceptance. This study investigated the interactions and taste-modulating effects of two milk proteins, β-casein (β-CN) and β-lactoglobulin (β-LG), with two representative bitter flavonoids, catechin (C) and naringin (NAR), in aqueous model systems. Fluorescence spectroscopy showed that both flavonoids produced concentration-dependent quenching of the milk proteins. β-CN exhibited more pronounced interaction-related spectroscopic responses than β-LG, which may be associated with its flexible and intrinsically disordered structure. Molecular docking predicted hydrogen-bonding and hydrophobic interactions in all four protein–flavonoid systems, with catechin and naringin interacting mainly with the internal hydrophobic cavity of β-LG and surface-exposed regions of the β-CN model. Circular dichroism and Fourier-transform infrared spectroscopy indicated ligand-dependent structural changes. For β-LG, catechin slightly decreased the estimated antiparallel and total β-sheet fractions, whereas naringin produced a modest increase. For β-CN, catechin produced a more apparent redistribution between the estimated α-helix and β-sheet fractions, while naringin caused comparatively smaller changes. Electronic tongue measurements showed that the addition of the milk proteins reduced the bitterness- and astringency-related sensor responses of catechin and naringin. Under the tested conditions, β-CN produced greater attenuation of these responses than β-LG, while the umami-related response remained comparatively high. These findings support the potential application of milk proteins as taste-modulating components in flavonoid-containing dairy formulations, although validation in real food matrices is required. Full article

A series of novel heterometallic rare-earth chloroterephthalate metal–organic frameworks with the general formula (Tb_xGd_1−x)₂(Cl-1,4-bdc)₃·5H₂O (x = 0–1) were synthesized via direct precipitation from aqueous solutions. The structural and photophysical properties of these compounds were studied in detail. All compounds exhibit bright luminescence upon UV excitation into the ligand absorption band due to an efficient antenna effect. The photoluminescence quantum yield shows a non-monotonic dependence on the concentration of the terbium ion with a maximum value of 71% achieved for the compound containing equal molar fractions of the lanthanide ions. The (Tb_0.5Gd_0.5)₂(Cl-1,4-bdc)₃·5H₂O sample was evaluatedfor its utility in both qualitative and quantitative analysis of selected metal ions and in latent fingerprint development. It was shown to enable the detection of Cr(III), Fe(III), and Cu(II) ions through luminescence quenching, with the emission intensity being concentration-dependent. This behaviour highlights the compound’s potential as a basis for analytical protocols and materials aimed at the quantitative determination of these metal ions. Full article

Foam cell formation of macrophages is a core pathological event in the progression of atherosclerosis. Investigating the changes in active molecules during macrophage foaming is critical for the early warning and mechanistic research of atherosclerosis. Superoxide anion (O₂^•−) and nitric oxide (NO) are two typical representatives of these active species; evaluating the fluctuations of O₂^•− and NO during macrophage foaming is vital for understanding the early diagnosis and pathological mechanisms of atherosclerosis. Herein, we report a fluorescent probe for the detection of O₂^•− and NO concentration changes based on the quenching effect of the urea bond and trifluoromethanesulfonate group on the fluorophore. MB-ROS features favorable sensitivity, selectivity and biocompatibility, enabling imaging of O₂^•− and NO fluctuations in macrophages. It was further validated in ox-LDL-stimulated foam cell models to visually track abnormal ROS/RNS changes during foam formation. This work offers a reliable chemical imaging tool to uncover redox imbalance underlying early atherosclerotic macrophage foaming. Full article

This study aimed to develop unique heat-resistant polymers with very high-intensity blue photoluminescence (PL), particularly by maximizing the PL efficiencies (Φ_PL) of fluorophore-incorporated polyimides (PIs) while maintaining their PL color. A bifunctional amide-linked fluorophore (HTA-BAPA) was synthesized from a hydrogenated trimellitic anhydride (HTA) derivative and 9,10-bis(4-aminophenyl)anthracene (BAPA) to covalently incorporate into the main chains of PIs. The dependence of the Φ_PL on the HTA-BAPA content was investigated using a wholly cycloaliphatic PI matrix, derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) with 4,4′-methylenebis(cyclohexylamine) (MBCHA), without charge-transfer (CT) interactions, which mask the desired PL. The Φ_PL in the PI precursor film significantly decreased after thermal imidization while maintaining the PL spectral profile (spectral shape and position = PL color). This is likely related to low-level (two-molecular) fluorophore aggregation during thermal imidization, which is responsible for concentration quenching (CQ). Then, the effect of the chemical imidization process (Route-C) on Φ_PL was investigated. Route-C provided PI films via a simple solution coating and drying process without thermal imidization. However, when CBDA/MBCHA was used as the PI matrix, gelation/precipitation occurred during chemical imidization, which inhibited subsequent solution casting. To solve this problem, an alternative cycloaliphatic tetracarboxylic dianhydride, derived from the HTA derivative and 4,4′-biphenol (44′BP), was used to combine with 2,2′-bis(trifluoromethyl)benzidine. This matrix PI exhibited Route-C compatibility, excellent solubility, and high heat resistance (T_g = 263 °C), while maintaining a CT-inhibiting function. The PI cast film incorporating HTA-BAPA (2 mol%) exhibited a highly intense blue PL with an exceedingly high Φ_PL of 0.68 (68%) and a color coordinate, CIE (x = 0.151, y = 0.074), corresponding to deep-blue PL. The impact of casting solvent type on the Φ_PL was also investigated. A clear correlation between the boiling points (T_b) of the casting solvents and Φ_PL of the resulting PI cast films was observed, where Φ_PL monotonically increased with decreasing T_b. These results probably suggest that faster evaporation (solidification) related to the lower T_b during the first soft-drying step at 60 °C kinetically overcame the two-molecular fluorophore aggregation responsible for CQ. Solution casting from tetrahydrofuran (with the lowest T_b) afforded a maximum Φ_PL of 0.84 (84%). Thus, unique polymeric materials with excellent solubility, high T_g, relatively high thermal stability and acceptable film ductility along with highly intense pure-blue PL were obtained, broadening the scope of photoluminescent PI applications, such as heat-resistant fluorescent QR codes. Full article

High-purity quartz is a critical raw material for high-tech industries such as semiconductors and photovoltaics, yet its purity is severely constrained by gas–liquid inclusions within quartz crystals that are difficult to eliminate. The calcination–water quenching process is a key pretreatment step for removing inclusions and achieving deep purification, but its underlying mechanisms and the influence of process parameters on removal efficiency remain insufficiently understood. In this study, systematic calcination–water quenching experiments at different temperature gradients (500 °C, 700 °C, 900 °C, and 1100 °C) were conducted on high-purity quartz samples from Inner Mongolia and Angola. Comprehensive analytical techniques, including X-ray diffraction (XRD), major and trace element analyses, and polarizing microscopy, were employed to investigate the microstructural evolution, inclusion morphology, impurity element concentration changes, and phase transformation behavior before and after treatment. With increasing temperature, the quartz samples exhibited pronounced whitening and pulverization, accompanied by a significant reduction in the number of internal linear inclusions. Elemental analysis revealed that calcination–water quenching effectively removed certain alkali metals, alkaline-earth metals, and iron impurities, with 900 °C identified as the optimal calcination temperature; moreover, the sand-sized samples consistently showed better impurity removal efficiency than the lump-sized counterparts. XRD analysis was used to verify the phase transformation of quartz during calcination. Excessive temperatures (e.g., 1100 °C) led to a rebound in the content of some impurity elements. The calcination–water quenching process promotes inclusion decrepitation, exposure, and subsequent removal through the combined effects of volumetric strain induced by quartz phase transitions, thermal pressurization of inclusions, and thermal-shock stress from water quenching. This study establishes the optimal process window (hold at 900 °C for 2 h, sand-sized morphology) for the specific ore samples, elucidates the multi-factor synergistic mechanism of inclusion rupture, and provides both experimental and theoretical bases for the industrial purification of high-purity quartz. Full article

Garnet-structured compounds have long been recognized as versatile host platforms for luminescent phosphors, owing to their robust chemical stability and highly tunable cationic sublattices. Conventional aluminate and gallate garnets, however, generally face intrinsic limitations, including severe concentration quenching at high dopant levels, relatively high phonon energy, and unsatisfactory efficiency for long-wavelength near-infrared (NIR) emission. In recent years, sodium-based germanate garnets, constructed by introducing aliovalent Na⁺ into dodecahedral sites combined with Ge⁴⁺ substitution in tetrahedral frameworks, have emerged as a promising branch of garnet phosphors. The aliovalent Na+ incorporation brings unique structural effects, including energy migration blocking, coordination environment distortion, and defect level modulation, which endow the materials with advantages in mitigating concentration quenching, boosting energy transfer efficiency, and enhancing thermal stability. This review systematically summarizes the crystal structure classification and luminescence fundamentals of sodium-based germanate garnet systems, and introduces mainstream synthesis techniques represented by the high-temperature solid-state method. Focusing on representative host systems, the luminescence characteristics and energy transfer mechanisms of both rare earth- and transition metal-doped systems are elaborated in detail, followed by a summary of four representative performance regulation strategies: cationic disorder engineering, crystal field engineering, defect engineering and dual-site cooperative regulation. The multifunctional applications of these materials in white light-emitting diodes, plant growth lighting, fluorescence temperature sensing, NIR imaging, and information encryption are also presented. Finally, existing challenges and future research perspectives are proposed to provide guidance for the development of high-performance garnet phosphors. Full article

This study investigated twelve gem-quality color-change fluorite specimens exhibiting a purple–blue gradient from Nova Era, Brazil, using colorimetry, Raman spectroscopy, UV-Vis spectroscopy, photoluminescence spectroscopy, EDXRF, and DiamondView imaging to explore the relationship between color depth and coloration mechanism. Raman spectroscopy further revealed enhanced defect-related peaks in dark samples, indicating cumulative irradiation-induced lattice damage. EDXRF analysis revealed that the radioactive element Th was detected exclusively in dark samples, with the darkest specimen reaching 0.184 wt.% Th, confirming that long-term Th-induced irradiation is the primary driver of color deepening. In UV-Vis spectra, the ~583 nm plasmon resonance absorption band of calcium colloids progressively red-shifted and broadened with increasing color depth, indicating elevated colloid concentrations and enhanced aggregation that directly intensify body color. DiamondView fluorescence weakened with deepening color, attributed to the quenching effect of calcium colloids. Photoluminescence spectra showed that the Eu²⁺ emission peak intensified in dark samples, while the broad 700–900 nm emission band systematically blue-shifted, reflecting differential responses of luminescence centers to radiation damage. This study provides non-destructive spectroscopic criteria for the fluorite color-change mechanism without relying on micro-area compositional analysis, establishing an analytical paradigm linking color gradients with spectral characteristics. Full article

Amplex Red is a widely used fluorogenic probe for hydrogen peroxide (H₂O₂) detection. In the presence of horseradish peroxidase (HRP), it reacts with H₂O₂ to form fluorescent resorufin. However, during high-voltage electric pulse treatment, fluorescence readouts may be influenced not only by H₂O₂ generation but also by the medium composition, pulse conditions, pH-dependent effects, and metal ions released as a result of electrode corrosion. In this study, we examined how medium composition and selected metal ions relevant to electroporation conditions, such as Fe²⁺, Fe³⁺, Al³⁺, and Cr⁶⁺, affect the Amplex Red/HRP/H₂O₂ fluorescence signal. Fluorescence intensity differed markedly among media, with the highest signal in phosphate-buffered saline (PBS, ~34,000 a.u.), followed by HB1 buffer (~19,000 a.u.), cell culture medium (~9000 a.u.), and distilled water (~4100 a.u.). To model ion-mediated interference, metal ions were added directly to the assay mixture. All tested ions reduced fluorescence in a concentration-dependent manner. At 0.4 µM H₂O₂, Fe²⁺ reduced fluorescence by up to 92%, Fe³⁺ by 60%, Al³⁺ by 35%, and Cr⁶⁺ by 40%. At 10 µM H₂O₂, the quenching effect was reduced but remained evident. In addition, the fluorescence readout showed strong dependence on medium composition and its pH, further demonstrating its vulnerability to the chemical environment. These findings show that the Amplex Red assay is highly sensitive to the assay environment and metal-ion interference. Therefore, it should not be used as a standalone, interference-free measure of H₂O₂ in electroporation-related experiments without appropriate validation controls. Full article

The rising prevalence of Drug-Facilitated Sexual Assault (DFSA) underscores the urgent need for rapid, sensitive, and selective analytical tools. Among the most concerning substances are γ-hydroxybutyric acid (GHB) and its precursor γ-butyrolactone (GBL), both of which pose significant forensic challenges due to their rapid metabolism and narrow detection windows. While detection methods for GHB have advanced, the monitoring of GBL remains less explored. This study reports the extended application of a fluorescein-based chemosensor previously validated for GHB for the selective detection of GBL in aqueous media and synthetic saliva. The probe operates via fluorescence quenching proportional to GBL concentration, achieving detection limits well below toxicological thresholds. Mechanistic investigations reveal that the recognition process is driven by an acid–base equilibrium and the reversible opening of the fluorescein lactone ring, with the 2-aminonaphthoxazole moiety playing a pivotal role. The sensor exhibits high selectivity against common DFSA-related interferents. Furthermore, the system was integrated into a portable lateral flow assay coupled with a smartphone-based readout, providing a cost-effective and user-friendly platform. Meeting the WHO “ASSURED” criteria, this methodology represents a promising tool for forensic, clinical, and preventive applications against chemical submission. Full article

The objective of this research is the development of a copper-based optical sensor for the detection of ovarian cancer marker CA 125 synthesized using low-temperature plasma. Optical materials produced with metals show unique advantages due to their ability to interact with light. There are different methods currently used for the synthesis of optical materials that can be associated with longer processing times and low material yield. The novelty of this study is the development of copper-based optical material (CuPy) using low-temperature plasma and subsequent modification for the detection of CA 125. Introduction: Plasma consists of a mixture of fully and partially ionized gas. It comprises diverse, highly energized species of atoms, ions, electrons, excited molecules, and charged species. These energized species are used to create new materials, for surface modifications, and in medical applications. Plasma can create a controlled environment for the creation of novel materials. Using low-temperature plasma, it will be possible to have precise control of the chemical composition and structure due to the creation of excited molecules, ions, and free radicals. Method: The CuPy material was synthesized using radio-frequency-assisted low-temperature plasma. Prior to synthesis, the plasma chamber was cleaned using radio frequency (RF) plasma without any reagents or gases. RF plasma was used for the synthesis of CuPy for 10 min and subsequent hydrogen plasma (50 sccm) for another 10 min. Two types of products were extracted from the chamber (one in water and another in methanol). These two products were analyzed using UV–visible absorbance spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The methanol extracted samples were further modified with CA 125 antibody. Zeta potential measurements were performed to confirm the binding of the CA 125 antibody to the sensor. The sensing efficacy of the sensor towards CA 125 antigen was monitored using fluorescence spectroscopy. Results: The absorbance spectrum of methanol extracted CuPy shows absorbances around 251 nm, 282 nm, and 339 nm. The extracted product exhibited a red edge excitation emission in the visible region. The elemental composition and oxidation state of the sample were evaluated using XPS. CA 125 antibody conjugation with CuPy was confirmed using UV–visible absorbance spectroscopy, fluorescence spectroscopy, and FTIR spectroscopy. The antibody binding resulted in the fluorescence shifts towards higher wavelengths with an increase in the emission intensity compared with CuPy. Zeta potential measurements also confirmed the binding of the CA 125 antibody to the sensor. Different concentrations of CA 125 antigen resulted in the quenching of fluorescence. This change in the fluorescence intensity was used for the detection of CA 125. Conclusions: A copper-based optical material was developed using low-temperature plasma, and it was found to be effective for the detection of CA 125 ovarian cancer marker. Full article

The sustainable isolation of nonamphiphilic phytochemicals remains a formidable challenge in biochemical engineering. In this study, a highly efficient and solvent free foam fractionation process was developed for recovering rosmarinic acid from botanical extracts. By systematically screening diverse biological surfactants, whey soy protein emerged as an exceptionally robust dual functional frother and nanoscale collector. Response surface methodology optimized the operational parameters to 850 mg/L protein concentration, pH 2.5, and a gas flow rate of 470 mL/min, yielding an outstanding target recovery of 93.08 percent alongside an enrichment ratio of 1.81. This macroscopic separation superiority was comprehensively elucidated at the molecular level through multiple spectroscopic techniques and computational modeling. Results confirmed a spontaneous static quenching complexation driven by synergistic noncovalent forces, predominantly hydrogen bonding, van der Waals interactions, π-stacking, and salt bridges. These interactions induced targeted conformational unfolding within the protein backbone, exposing hydrophobic domains that drastically elevated the thermodynamic affinity for the ascending gas–liquid interface. Furthermore, the concentrated product exhibited an antioxidant capacity enhancement exceeding 3.6 times compared to the crude extract, a result attributed to selective enrichment combined with the structural shielding effect provided by the protein macromolecule. Ultimately, this work provides critical mechanistic insights and establishes a scalable technological framework for the green purification of highly valuable botanical compounds. Full article

The luminescence efficiency of Mn²⁺-doped metal halides is often limited by concentration quenching caused by Mn-Mn interactions. In this work, the alkaline-earth cadmium chloride BaCd₂Cl₆·6H₂O:Mn²⁺ was synthesized via a mechanical grinding method. The three-dimensional network framework of this compound effectively isolates Mn²⁺ ions with a Mn-Mn separation of 4.87 Å, thereby suppressing concentration quenching. Under 254 nm ultraviolet excitation, the sample exhibits efficient orange emission centered at 588 nm with a photoluminescence quantum yield (PLQY) as high as 98%. Temperature-dependent photoluminescence studies reveal that the optimal emission temperature of this system is 320 K, demonstrating good thermal stability. This work achieves, for the first time, near-unity Mn²⁺ luminescence efficiency in a Ba-site alkaline-earth cadmium halide system, demonstrating that alkaline-earth-site confinement provides an effective strategy for achieving highly efficient Mn-doped halide luminescence. Full article

Drought increasingly threatens terrestrial vegetation, whereas current syntheses remain disproportionately focused on seed plants. Ferns and mosses provide a useful contrast because they represent distinct hydration strategies among early-diverging land plants. We compiled 3272 paired observations from 46 drought experiments covering 35 fern species and 41 moss species to compare responses in water status, photosynthesis, chlorophyll fluorescence, oxidative stress, osmotic adjustment, abscisic acid, and growth. Drought reduced physiological performance in both groups, but mosses showed a greater mean decline than ferns. Ferns maintained stable maximum quantum yield and increased nonphotochemical quenching despite reduced pigment content and carbon assimilation, suggesting stronger photoprotective regulation. In contrast, mosses showed coordinated declines in maximum fluorescence, effective PSII yield, and maximum quantum yield, together with elevated minimum fluorescence, indicating direct PSII impairment. Oxidative damage, osmolyte accumulation, and growth suppression were also stronger in mosses. Within ferns, drought sensitivity was concentrated in epiphytic species, especially obligate, canopy, tank-forming, and xerophytic groups. Fern responses were partly explained by provenance climate, drought duration, and specific leaf area. Overall, within the species and experimental conditions represented in the current dataset, ferns largely maintain photochemical stability through photoregulation, whereas mosses shift more rapidly toward PSII impairment, oxidative injury, and growth suppression, highlighting vulnerable components of moisture-dependent ecosystems under intensifying drought. Full article