Search Results (1,852)

The rapid development of high-power-density semiconductor devices has rendered conventional thermal management techniques inadequate for handling their extreme heat fluxes. This manuscript presents and implements an embedded microchannel cooling solution for such devices. By directly integrating micropillar arrays within the near-junction region of the substrate, efficient forced convection and flow boiling mechanisms are achieved. Finite element analysis was first employed to conduct thermo–fluid–structure simulations of micropillar arrays with different geometries. Subsequently, based on our simulation results, a complete multilayer microstructure fabrication process was developed and integrated, including critical steps such as deep reactive ion etching (DRIE), surface hydrophilic/hydrophobic functionalization, and gold–stannum (Au-Sn) eutectic bonding. Finally, an experimental test platform was established to systematically evaluate the thermal performance of the fabricated devices under heat fluxes of up to 1200 W/cm². Our experimental results demonstrate that this solution effectively maintains the device operating temperature at 46.7 °C, achieving a mere 27.9 K temperature rise and exhibiting exceptional thermal management capabilities. This manuscript provides a feasible, efficient technical pathway for addressing extreme heat dissipation challenges in next-generation electronic devices, while offering notable references in structural design, micro/nanofabrication, and experimental validation for related fields. Full article

Polysaccharides and phenols are commonly co-localized in various plant-derived foods, including highland barley (Hordeum vulgare L. var. nudum Hook. f.). The interactions between these compounds can influence multiple characteristics of food products, including their physicochemical properties and functional performance, such as bioavailability, stability, and digestibility, which may support promising application of the phenol and polysaccharide complex in health food industry. In this study, two complexes with potential existence in highland barley, such as β-glucan-ferulic acid (GF) and β-glucan-quercetin (GQ), were prepared using the equilibrium dialysis method in vitro. FTIR and SEM results showed that ferulic acid and quercetin formed complexes with β-glucan separately, with covalent and non-covalent bonds and a dense morphological structure. The pH value, reaction temperature, and concentration of phosphate buffer solution (PBS) were confirmed to have an impact on the formation and yield of the complex. Through the test of the response surface, it was found that the optimum conditions for GF and (GQ) preparations were a pH of 6.5 (6), a PBS buffer concentration of 0.08 mol/L (0.3 mol/L), and a temperature of 8 °C (20 °C). Through in vitro assays, GF and GQ were found to possess good antioxidant activity, with a greater scavenging effect of DPPH, ABTS, and hydroxyl radical than the individual phenolic acids and glucans, as well as their physical mixtures. Taking GF as an example, the DPPH radical scavenging capacity ranked as GF (71.74%) > ferulic acid (49.50%) > PGF (44.43%) > β-glucan (43.84%). Similar trends were observed for ABTS radical scavenging (GF: 54.56%; ferulic acid: 44.37%; PGF: 44.95%; β-glucan: 36.42%) and hydroxyl radical elimination (GF: 39.16%; ferulic acid: 33.06%; PGF: 35.51%; β-glucan: 35.47%). In conclusion, the convenient preparation method and excellent antioxidant effect of the phenol–polysaccharide complexes from highland barley provide new opportunities for industrial-scale production, development, and design of healthy food based on these complexes. Full article

Fungal lytic polysaccharide monooxygenases (LPMOs) have revolutionized the field of biomass degradation by introducing an oxidative mechanism that complements traditional hydrolytic enzymes. These copper-dependent enzymes catalyze the cleavage of glycosidic bonds in recalcitrant polysaccharides such as cellulose, hemicellulose, and chitin, through the activation of molecular oxygen (O₂) or hydrogen peroxide (H₂O₂). Their catalytic versatility is intricately modulated by structural features, including the histidine brace active site, surface-binding loops, and, in some cases, appended carbohydrate-binding modules (CBMs). The oxidation pattern, whether at the C1, C4, or both positions, is dictated by subtle variations in loop architecture, amino acid microenvironments, and substrate interactions. LPMOs are embedded in a highly synergistic fungal enzymatic system, working alongside cellulases, hemicellulases, lignin-modifying enzymes, and oxidoreductases to enable efficient lignocellulose decomposition. Industrial applications of fungal LPMOs are rapidly expanding, with key roles in second-generation biofuels, biorefineries, textile processing, food and feed industries, and the development of sustainable biomaterials. Recent advances in genome mining, protein engineering, and heterologous expression are accelerating the discovery of novel LPMOs with improved functionalities. Understanding the balance between O₂- and H₂O₂-driven mechanisms remains critical for optimizing their catalytic efficiency while mitigating oxidative inactivation. As the demand for sustainable biotechnological solutions grows, this narrative review highlights how fungal LPMOs function as indispensable biocatalysts for the future of the Circular Bioeconomy and green industrial processes. Full article

This study aimed to evaluate the effect of replacing chalk with fly ash in a two-component polyurethane (2C PU) adhesive on its physicochemical, mechanical, and environmental properties, as a practical application of circular economy principles. Six adhesive formulations were prepared, each containing a chalk-to-fly ash ratio as a filler. The study evaluated rheological, mechanical, thermal, and environmental parameters. Mechanical tests confirmed cohesive failure within the bonded material, indicating that the bond strength at the adhesive–substrate interface exceeded the internal strength of the substrate. The highest contaminant elution levels recorded were 0.62 mg/kg for molybdenum and 0.20 mg/kg for selenium, which represent only 6.2% and 40% of the regulatory limits, respectively. Dissolved organic carbon (DOC) and total dissolved solids (TDS) did not exceed 340 mg/kg and 4260 mg/kg, respectively. GC-MS analysis did not reveal the presence of prominent volatile organic compound emissions. Initial screening suggests possible compatibility with low-emission certification schemes (e.g., A+, AgBB, EMICODE^®), though confirmation requires further quantitative testing. The results demonstrate that fly ash can be an effective substitute for chalk in polyurethane adhesives, ensuring environmental compliance and maintaining functional performance while supporting the principles of the circular economy. Full article

In this study, three new terphenyl-substituted NPN ligands bearing pyridyl groups, two phosphonites and one diaminophosphine, were synthesized and fully characterized. Their coordination chemistry with copper(I) was investigated using CuBr and [Cu(NCMe)₄]PF₆ as metal precursors, affording six mononuclear Cu(I) complexes, which were characterized using NMR spectroscopy and, in selected cases, single-crystal X-ray diffraction (SCXRD) analysis. The NPN ligands adopt a κ³-coordination mode, stabilizing the copper centers in distorted tetrahedral geometries. The catalytic performance of these complexes in the S-arylation of thiols with aryl iodides was evaluated. Under optimized conditions, complexes 2a and 2b exhibited excellent activity and broad substrate scope, tolerating both electron-donating and electron-withdrawing groups, as well as sterically hindered and heteroaryl substrates. The methodology also proved effective for aliphatic thiols and demonstrated high chemoselectivity in the presence of potentially reactive functional groups. In contrast, aryl bromides and chlorides were poorly reactive under the same conditions. These findings highlight the potential of well-defined Cu(I)–NPN complexes as efficient and versatile precatalysts for C–S bond formation. Full article

Theranostic agents enable the simultaneous diagnosis and treatment of diseases, and they are particularly useful in fluorescent imaging and cancer therapies. In this study, carbon quantum dots were synthesized via a microwave-assisted method using citric acid and bovine serum albumin (BSA) as precursors. The resulting CQDs exhibited spherical morphology, an average size of 4 nm, and an amorphous graphitic structure. FT-IR characterization revealed the presence of amide bonds and oxygenated functional groups. At the same time, optical analysis showed excitation at 320 nm and emission between 360 and 400 nm, with fluorescent stability maintained for one month. Furthermore, the CQDs demonstrated good thermal stability and photothermal efficiency, reaching temperatures above 41 °C within 15 min under NIR irradiation, with a mass loss of less than 1%. Their stability was evaluated in media with different pH levels, simulating physiological and tumor environments. While their behavior was affected under acidic conditions, their excellent photothermal conversion capacity and overall stability in triple-distilled water positioned them as promising candidates for theranostic applications in cancer, effectively combining diagnostic imaging and thermal therapy. Full article

In this study, we report the development of a novel magnetized coal fly ash-supported nano-silver composite (AgNPs/MCFA) for dual-functional applications in wastewater treatment: the efficient degradation of methyl orange (MO) dye and broad-spectrum antibacterial activity. The composite was synthesized via a facile impregnation–reduction–sintering route, utilizing sodium citrate as both a reducing and stabilizing agent. The AgNPs/MCFA composite was systematically characterized through multiple analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results confirmed the uniform dispersion of AgNPs (average size: 13.97 nm) on the MCFA matrix, where the formation of chemical bonds (Ag-O-Si) contributed to the enhanced stability of the material. Under optimized conditions (0.5 g·L⁻¹ AgNO₃, 250 °C sintering temperature, and 2 h sintering time), AgNPs/MCFA exhibited an exceptional catalytic performance, achieving 99.89% MO degradation within 15 min (pseudo-first-order rate constant k_a = 0.3133 min⁻¹) in the presence of NaBH₄. The composite also demonstrated potent antibacterial efficacy against Escherichia coli (MIC = 0.5 mg·mL⁻¹) and Staphylococcus aureus (MIC = 2 mg·mL⁻¹), attributed to membrane disruption, intracellular content leakage, and reactive oxygen species generation. Remarkably, AgNPs/MCFA retained >90% catalytic and antibacterial efficiency after five reuse cycles, enabled by its magnetic recoverability. By repurposing industrial waste (coal fly ash) as a low-cost carrier, this work provides a sustainable strategy to mitigate nanoparticle aggregation and environmental risks while enhancing multifunctional performance in water remediation. Full article

The valence-shell electronic state spectroscopy of β-butyrolactone (CH₃CHCH₂CO₂) is comprehensively investigated by employing experimental and theoretical methods. We report a novel vacuum ultraviolet (VUV) absorption spectrum in the photon wavelength range from 115 to 320 nm (3.9–10.8 eV), together with ab initio quantum chemical calculations at the time-dependent density functional (TD-DFT) level of theory. The dominant electronic excitations are assigned to mixed valence-Rydberg and Rydberg transitions. The fine structure in the CH₃CHCH₂CO₂ photoabsorption spectrum has been assigned to C=O stretching, $v_7^{\prime }\left(a\right)$, CH₂ wagging, $v_{14}^{\prime }\left(a\right)$, C–O stretching, $v_{22}^{\prime }\left(a\right)$, and C=O bending, $v_{26}^{\prime }\left(a\right)$ modes. Photolysis lifetimes in the Earth’s atmosphere from 0 km up to 50 km altitude have been estimated, showing to be a non-relevant sink mechanism compared to reactions with the ^•OH radical. The nuclear dynamics along the C=O and C–C–C coordinates have been investigated at the TD-DFT level of theory, where, upon electronic excitation, the potential energy curves show important carbonyl bond breaking and ring opening, respectively. Within such an intricate molecular landscape, the higher-lying excited electronic states may keep their original Rydberg character or may undergo Rydberg-to-valence conversion, with vibronic coupling as an important mechanism contributing to the spectrum. Full article

This study investigates the effect of the surface functionalization of tungsten disulfide (WS₂) nanoparticles with aminoacetic acid (glycine) on the structure, curing behavior, and mechanical performance of epoxy nanocomposites. Aminoacetic acid, as a non-toxic, bio-based modifier, enables a sustainable approach to producing more efficient nanofillers. Functionalization, as confirmed by FTIR, EDS, and XRD analyses, led to elevated surface polarity and greater chemical affinity between WS₂ and the epoxy matrix, thereby promoting uniform nanoparticle dispersion. The strengthened interfacial bonding resulted in a notable decrease in the curing onset temperature—from 51 °C (for pristine WS₂) to 43 °C—accompanied by an increase in polymerization enthalpy from 566 J/g to 639 J/g, which reflects more extensive crosslinking. The SEM examination of fracture surfaces revealed tortuous crack paths and localized plastic deformation zones, indicating superior fracture resistance. Mechanical testing showed marked improvements in flexural and tensile strength, modulus, and impact toughness at the optimal WS₂ loading of 0.5 phr and a 7.5 wt% aminoacetic acid concentration. The surface-modified WS₂ nanoparticles, which perform dual functions, not only reinforce interfacial adhesion and structural uniformity but also accelerate the curing process through chemical interaction with epoxy groups. These findings support the development of high-performance, environmentally sustainable epoxy nanocomposites utilizing amino acid-modified 2D nanofillers. Full article

Background/Objectives: A nanostructured membrane of polycaprolactone (a synthetic polymer) was synthesized using an electrospinning technique aiming to enhance its hydrophilicity and rate of degradation by surface modification via aminolysis. Since polycaprolactone nanofibrous films are naturally hydrophobic and with slow degradation, which restricts their use in biological systems, amino groups were added to the fiber surface using the aminolysis technique, greatly increasing the wettability of the membranes. Methods: Polycaprolactone nanofibrous membranes were synthesized via the electrospinning technique and surface modification by aminolysis. Trypsin, pepsin, and pancreatin were conjugated onto the aminolyzed PNF surface to further strengthen biocompatibility by enhancing the hydrophilicity, porosity, and biodegradation rate. SEM, FTIR, EDX, and liquid displacement method were performed to investigate proteolytic efficiency and morphological and physical characteristics such as hydrophilicity, porosity, and degradation rates. Results: Enzyme activity tests, which showed a zone of clearance, validated the successful enzyme conjugation and stability over a wide range of pH and temperatures. Scanning electron microscopy (SEM) confirms the smooth morphology of nanofibers with diameters ranging from 150 to 950 nm. Fourier transform infrared spectroscopy (FTIR) revealed the presence of O–H, C–O, C=O, C–N, C–H, and O–H functional groups. Energy-dispersive X-ray (EDX) elemental analysis indicates the presence of carbon, oxygen, and nitrogen atoms owing to the presence of peptide and amide bonds. The liquid displacement technique and contact angle proved that Pepsin-PNFs possess notably increased porosity (88.50% ± 0.31%) and hydrophilicity (57.6° ± 2.3 (L), 57.9° ± 2.5 (R)), respectively. Pancreatin-PNFs demonstrated enhanced enzyme activity and degradation rate on day 28 (34.61%). Conclusions: These enzyme-conjugated PNFs thus show improvements in physicochemical properties, making them ideal candidates for various biomedical applications. Future studies must aim for optimization of enzyme conjugation and in vitro and in vivo performance to investigate the versatility of these scaffolds. Full article

Our work introduces a facile and efficient metal-free [3+3] annulation approach for the synthesis of polysubstituted pyridines via the reaction between β-enaminonitriles and β,β-dichloromethyl peroxides. This strategy operates under mild conditions, demonstrating broad substrate scope and excellent functional group tolerance. Mechanistic investigations suggest that the reaction proceeds through a Kornblum–De La Mare rearrangement followed by S_NV-type C-Cl bond cleavage and intramolecular cyclization/condensation. By circumventing the need for transition metal catalysts or radical initiators, our method offers practical utility in organic synthesis and provides a new avenue for the rapid construction of complex pyridine scaffolds. Full article

Inspired by the active site of methane monooxygenase, we designed a Cu₂O cluster anchored in the six-membered nitrogen cavity of a C₂N monolayer (Cu₂O@C₂N) as a stable and efficient enzyme-like catalyst. Density functional theory (DFT) calculations reveal that the bridged Cu-O-Cu structure within C₂N exhibits strong electronic coupling, which is favorable for methanol formation. Two competing mechanisms—the concerted and radical-rebound pathways—were systematically investigated, with the former being energetically preferred due to lower energy barriers and more stable intermediate states. Furthermore, strain engineering was employed to tune the geometric and electronic structure of the Cu-O-Cu site. Biaxial strain modulates the Cu-O-Cu bond angle, adsorption properties, and d-band center alignment, thereby selectively enhancing the concerted pathway. A volcano-like trend was observed between the applied strain and the methanol formation barrier, with 1% tensile strain yielding the overall energy barrier to methanol formation (ΔG_overall) as low as 1.31 eV. N₂O effectively regenerated the active site and demonstrated strain-responsive kinetics. The electronic descriptor Δε (ε_d − ε_p) captured the structure–activity relationship, confirming the role of strain in regulating catalytic performance. This work highlights the synergy between geometric confinement and mechanical modulation, offering a rational design strategy for advanced C1 activation catalysts. Full article

Balancing the energy and stability of energetic materials is a challenging task in their development. Salt formation is a promising strategy for seeking high-energy, low-sensitivity materials. In this study, the modification of anions facilitates the enhancement of density and oxygen balance in amino-functionalized N-heterocycle systems. The results of single-crystal X-ray diffraction and theoretical analysis suggest that DATOP possesses intense hydrogen bonding networks in its crystal structure. The ideal structure of DATOP (ρ = 1.954 g·cm⁻³, D = 8624 m·s⁻¹, P = 34.4 GPa) gives rise to higher detonation properties compared to DATOC (ρ = 1.717 g·cm⁻³, D = 5984 m·s⁻¹, P = 12.4 GPa). In particular, the thermal stability of DATOP (T_d = 273 °C) is superior to DATOC (T_d = 154 °C). DATOP also maintains comparable mechanical sensitivities to DATOC. These fascinating results reveal that the strategy of salt formation shows excellent potential for balancing energy and stability in energetic materials. Full article

Cold environments challenge the structural and functional integrity of membrane proteins, requiring specialized adaptations to maintain activity under low thermal energy. Here, we investigate the molecular basis of cold tolerance in the peptide transporter PepT1 from the Antarctic icefish (Chionodraco hamatus, ChPepT1) using molecular dynamics simulations, binding free energy calculations (MM/GBSA), and dynamic network analysis. We compare ChPepT1 to its human ortholog (hPepT1), a non-cold-adapted variant, to reveal key features enabling psychrophilic function. Our simulations show that ChPepT1 displays enhanced global flexibility, particularly in domains adjacent to the substrate-binding site and the C-terminal domain (CTD). While hPepT1 loses substrate binding affinity as temperature increases, ChPepT1 maintains stable peptide interactions across a broad thermal range. This thermodynamic buffering results from temperature-sensitive rearrangement of hydrogen bond networks and more dynamic lipid interactions. Importantly, we identify a temperature-responsive segment (TRS, residues 660–670) within the proximal CTD that undergoes an α-helix to coil transition, modulating long-range coupling with transmembrane helices. Dynamic cross-correlation analyses further suggest that ChPepT1, unlike hPepT1, reorganizes its interdomain communication in response to temperature shifts. Our findings suggest that cold tolerance in ChPepT1 arises from a combination of structural flexibility, resilient substrate binding, and temperature-sensitive interdomain dynamics. These results provide new mechanistic insight into thermal adaptation in membrane transporters and offer a framework for engineering proteins with enhanced functionality in extreme environments. Full article

The rapid recombination of photoinduced charge carriers in semiconductors remains a significant challenge for their practical application in photocatalysis. This study presents the design of a step-scheme (S-scheme) heterojunction composed of carbon nitride (g-C₃N₄) and nickel-based metal–organic framework (Ni-MOF) to achieve enhanced charge separation. The establishment of an S-scheme charge transfer configuration at the interface of the Ni-MOF/g-C₃N₄ heterostructure plays a pivotal role in enabling efficient charge carrier separation, and hence, high CO₂ photoreduction efficiency with a CO evolution rate of 1014.6 µmol g⁻¹ h⁻¹ and selectivity of 95% under simulated solar illumination. CO evolution represents an approximately 3.7-fold enhancement compared to pristine Ni-MOF. Density functional theory (DFT) calculations, supported by in situ irradiated X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) experimental results, confirmed the establishment of a well-defined and strongly bonded interface, which improves the charge transfer and separation following the S-scheme mechanism. This study sheds light on MOF-based S-scheme heterojunctions as fruitful and selective alternatives for practical CO₂ photoreduction. Full article