Search Results (1,441)

In this study, semi-interpenetrating polymer network (semi-IPN) hydrogels based on methacrylated dextran and native inulin were designed as biodegradable carriers for the colon-specific delivery of uracil as a model antitumor compound. The hydrogels were synthesized via free-radical polymerization, using diethylene glycol diacrylate (DEGDA) as a crosslinking agent at varying concentrations (5, 7.5, and 10 wt%), and their structural, thermal, and biological properties were systematically evaluated. Fourier transform infrared spectroscopy (FTIR) confirmed successful crosslinking and physical incorporation of uracil through hydrogen bonding. Concurrently, differential scanning calorimetry (DSC) revealed an increase in glass transition temperature (T_g) with increasing crosslinking density (149, 153, and 156 °C, respectively). Swelling studies demonstrated relaxation-controlled, first-order swelling kinetics under physiological conditions (pH 7.4, 37 °C) and high gel fraction values (84.75, 91.34, and 94.90%, respectively), indicating stable network formation. SEM analysis revealed that the hydrogel morphology strongly depended on crosslinking density and drug incorporation, with increasing crosslinker content leading to a more compact and wrinkled structure. Uracil loading further modified the microstructure, promoting the formation of discrete crystalline domains within the semi-IPN hydrogels, indicative of physical drug entrapment. All formulations exhibited high encapsulation efficiencies (>86%), which increased with increasing crosslinker content, consistent with the observed gel fraction values. Simulated in vitro gastrointestinal digestion showed negligible drug release under gastric conditions and controlled release in the intestinal phase, primarily governed by crosslinking density. Antimicrobial assessment against Escherichia coli and Staphylococcus epidermidis, used as an initial or indirect indicator of cytotoxic potential, revealed no inhibitory activity, suggesting low biological reactivity at the screening level. Overall, the results indicate that DEGDA-crosslinked dextran/inulin semi-interpenetrating (semi-IPN) hydrogels represent promising carriers for colon-targeted antitumor drug delivery. Full article

This study proposes a circular economy strategy to recover phenolic compounds by valorizing shrimp shell waste into a chitosan biosorbent (CH-B). Its adsorption efficiency was evaluated compared to commercial activated carbon (AC) and synthetic XAD-4 resin. Kinetic analysis revealed that while both pseudo-first-order (PFO) and pseudo-second-order (PSO) models exhibited high correlations (R²$\ge$ 0.96), both CH-B and XAD-4 resin were best described by the PFO model. This aligns with diffusion-controlled processes consistent with the porous and physical nature of these adsorbents. In contrast, AC followed the PSO model. Isotherm modeling indicated that CH-B and AC fit the Temkin model, reflecting heterogeneous surfaces, whereas XAD-4 followed the Langmuir model (monolayer adsorption). Notably, CH-B exhibited a maximum adsorption capacity (q_m) of 229.2 mg/g, significantly outperforming XAD-4 (104.8 mg/g) and AC (90.2 mg/g). Thermodynamic and kinetic modeling confirmed that the adsorption mechanism was governed by a combination of electrostatic interactions, π–π stacking, and hydrogen bonding between the hydroxyl/amine groups of chitosan and phenolic compounds. Optimization using Box–Behnken design for CH-B showed optimal acidic pH and moderate temperature but non-significant effect of CH-B dose in the experimental domain. Optimisation results showed unexpected high removal efficiency at low CH-B dosages. A tentative explanation may be adsorbent aggre-gation, which needs to be confirmed by further experimental evidence. Full article

We present a rapid, energy-efficient, and ecofriendly route for the synthesis of alkaline earth titanate perovskites—CaTiO₃, SrTiO₃, and BaTiO₃—using an affordable, commercially available CO₂ laser engraver, commonly found in makerspaces and small-scale workshops. The method involves direct laser irradiation of compacted pellets composed of low-cost, abundant, and non-toxic precursors: TiO₂ and alkaline earth carbonates (CaCO₃, SrCO₃, BaCO₃). CaTiO₃ and BaTiO₃ were synthesized with phase purities exceeding 97%, eliminating the need for conventional high-temperature furnaces or prolonged thermal treatments. X-ray diffraction (XRD) coupled with Rietveld refinement confirmed the formation of orthorhombic CaTiO₃ (Pbnm), cubic SrTiO₃ (Pm3⁻m), and tetragonal BaTiO₃ (P4mm). Raman spectroscopy independently corroborated the perovskite structures, revealing vibrational fingerprints consistent with the expected crystal symmetries and Ti–O bonding environments. All samples contained only small amounts of unreacted anatase TiO₂, while BaTiO₃ exhibited a partially amorphous fraction, attributed to the sluggish crystallization kinetics of the Ba–Ti system and the rapid quenching inherent to laser processing. Transmission electron microscopy (TEM) revealed nanoparticles with average sizes of 50–150 nm, indicative of localized melting followed by ultrafast solidification. This solvent-free, low-energy, and highly accessible approach, enabled by widely available desktop laser systems, demonstrates exceptional simplicity, scalability, and sustainability. It offers a compelling alternative to conventional ceramic processing, with broad potential for the fabrication of functional oxides in applications ranging from electronics to photocatalysis. Full article

A TiAlCrSiNbY coating was fabricated on γ-TiAl alloy by arc ion plating. The coating exhibits a dense, crack-free microstructure with a thickness of 5 ± 0.5 μm and strong interfacial bonding with the substrate. The characteristic power law correlations between mass gain and oxidation time were obtained for the uncoated and the coated samples at 850 °C with rate exponents of 2.38 and 2.14, respectively. After oxidation at 850 °C for 200 h, a continuous and dense oxide layer primarily composed of α-Al₂O₃ with a low oxidation reaction rate was formed, and the mass gain of the coated sample was 1/9 times that of the uncoated sample. Additionally, the addition of Cr and Nb in the TiAlCrSiNbY coating can increase the activity of Al and promoted the formation of stable and dense Al₂O₃ oxide films, the presence of a strong high-temperature stability Ti₅Si₃ phase inhibited the affinity of Ti and O, which maintained structural integrity and enhanced high-temperature oxidation resistance. Full article

Liquid gallium (Ga) enables low-temperature transient liquid phase bonding (TLPB), but optimizing microstructure and joint performance remains challenging. Here, we developed a copper (Cu)-powder/liquid-Ga composite paste for Cu/Cu interconnects and systematically studied the effects on the interconnect joint performance of Cu powder particle size (Cu_PS, 10–20, 20–30 and 30–40 μm) and Cu mass fraction (Cu_MF, 10–30 wt%). The microstructure, electrical conductivity, and shear strength of the joint were evaluated, followed by an assessment of bonding temperature, pressure, and time. Under bonding conditions of 220 °C, 5 MPa and 720 min, a dense intermetallic compound (IMC) microstructure predominantly composed of Cu₉Ga₄ and CuGa₂ was formed, yielding an electrical conductivity of approximately 1.1 × 10⁷  S·m⁻¹ and a shear strength of 52.2 MPa, thereby achieving a synergistic optimization of electrical and mechanical properties; even under rapid bonding conditions of 220 °C, 5 MPa and 1 min, the joint still attained a shear strength of 39.2 MPa, demonstrating the potential of this process for high-efficiency, short-time interconnection applications. These results show that adjusting the composite paste formulation and dosage enables Cu–Ga TLPB joints that combine high conductivity with robust mechanical integrity for advanced packaging. Full article

Taking advantage of the ionic size and mass disorder as component design criteria, three novel high-entropy rare-earth zirconate ceramics, including (Sm_0.2Gd_0.2Dy_0.2Er_0.2Tm_0.2)₂Zr₂O₇, (Gd_0.2Dy_0.2Ho_0.2Er_0.2Tm_0.2)₂Zr₂O₇ and (Gd_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₂Zr₂O₇, with single-phase fluorite structure were successfully synthesized. All compositions exhibited enhanced mechanical properties, with Vickers hardness and fracture toughness increasing as the grain size decreased. (Gd_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₂Zr₂O₇ demonstrated superior mechanical performance, achieving values of 11.41 ± 0.40 GPa and 1.78 ± 0.12 MPa·m^1/2, respectively. The thermal expansion coefficients at 1000 °C ranged from 10.80 × 10⁻⁶ K⁻¹ to 11.39 × 10⁻⁶ K⁻¹, which is proportional to the average ionic bond length. Notably, (Sm_0.2Gd_0.2Dy_0.2Er_0.2Tm_0.2)₂Zr₂O₇ exhibited low room-temperature thermal conductivity (1.58 W·m⁻¹·K⁻¹) due to pronounced size and mass disorder, without compromising structural stiffness. These findings highlight the potential of high-entropy design for advanced thermal barrier coatings. Full article

High-temperature proton exchange membrane systems (HT-PEM) based on polybenzimidazole (PBI) membranes are a promising technology offering significant advantages over their low-temperature counterparts. A key challenge limiting its long-term durability is the leaching of phosphoric acid (PA) from the membrane during operation. This work introduces, for the first time, the strategy of modifying polybenzimidazole (PBI) membranes with amino-functionalized porous aromatic frameworks (PAF-20-NH₂) to fundamentally enhance their PA retention and operational stability, a critical challenge for high-temperature PEM technologies. We propose that the synergistic combination of the framework’s nanoscale porosity and the specific interaction of its amino groups create an unprecedented network for acid immobilization via reinforced hydrogen bonding. A comprehensive study of the membranes’ physicochemical and structural properties reveals that PAF-20-NH₂ modification results in a significant and quantitatively demonstrated improvement in acid retention capacity, directly translating into a notable increase in proton conductivity compared to both pristine PBI and membranes modified with the non-functionalized PAF-20. These findings establish a new, highly effective pathway for the rational design of next-generation high-performance PBI-based membranes. Full article

Sintered nano-silver is widely investigated as a die-attach material for next-generation power electronic modules due to its high thermal conductivity, favorable electrical performance, and stability at elevated temperatures. However, how bonding pressure and joint thickness jointly affect densification, interfacial diffusion, and mechanical reliability has not been systematically clarified, especially under the low-pressure conditions required for large-area SiC and GaN devices. In this work, nano-silver lap-shear joints with three bond-line thicknesses (50, 70, and 100 μm) were fabricated under two applied pressures (1.0 and 1.5 MPa) using a controlled sintering fixture. Shear testing and cross-sectional SEM were employed to evaluate the relationships between microstructural evolution and joint integrity. When the bonding pressure was increased from 1.0 to 1.5 MPa, more effective particle rearrangement and reduced pore connectivity were observed, together with improved metallurgical bonding at the Ag–Au interface, leading to a strength increase from 15.3 to 28.2 MPa. Although thicker joints exhibited slightly higher bulk relative density due to greater heat retention and accelerated local sintering, this densification advantage did not lead to improved mechanical performance. Instead, the lower strength of thicker joints is attributed to a narrower Ag–Au interdiffusion region, which limited the formation of continuous load-bearing paths at the interface. Fractographic analyses confirmed that failure occurred predominantly by interfacial delamination rather than cohesive fracture, indicating that the reliability of the joints under low-pressure sintering is governed by the quality of interfacial bonding rather than by overall densification. The experimental results show that, under low-pressure sintering conditions (1.0–1.5 MPa), variations in bonding pressure and bond-line thickness lead to distinct effects on joint performance, with the extent of Ag–Au interfacial interaction playing a key role in determining the mechanical robustness of the joints. Full article

As urbanization and extreme weather conditions intensify, the comprehensive performance requirements for building waterproofing systems are becoming more demanding. Single-layer waterproof membranes often struggle to meet usage requirements in complex environments, leading to the gradual rise of composite waterproof systems. This paper selects three different types of waterproof membranes, ultra-thin reinforced self-adhesive polymer-modified bitumen waterproof membrane, polymer self-adhesive waterproof membrane, and polymer-modified bitumen root penetration-resistant waterproof membrane, and conducts a systematic study on their compatibility and durability. Through tensile performance, low-temperature flexibility, and peel compatibility tests, combined with thermal oxidative aging experiments at different aging times, the mechanical behavior, low-temperature adaptability, and interfacial bonding characteristics of the membranes were analyzed. The results show that the three membranes differ significantly in tensile performance. The root penetration-resistant membrane has the highest strength but is more brittle, the polymer self-adhesive membrane has lower strength but better stability, and the ultra-thin reinforced membrane performs better initially but lacks durability. In terms of low-temperature flexibility, the root penetration-resistant membrane demonstrates superior crack resistance and aging resistance. These divergent aging responses are closely related to differences in reinforcement structure, polymer modification, and the thermal–oxidative sensitivity of the bituminous adhesive layers. Peel compatibility tests show that the peel strength of the composite membranes of the ultra-thin reinforced and polymer self-adhesive membranes is significantly improved, indicating a good synergistic effect and compatibility. Overall, different waterproof membranes exhibit distinct compatibility mechanisms and aging patterns in composite applications, providing a scientific basis for the design and optimization of composite waterproof systems. Full article

Waterproofing systems frequently experience performance degradation during long-term service due to material aging and structural deformation, thereby necessitating localized repair interventions. The bonding interface between newly applied and existing membrane materials is a critical determinant of repair effectiveness. In this study, the aging-dependent repair performance of three representative waterproof membrane systems was systematically investigated using peel strength testing, low-temperature flexibility assessment, and interfacial morphology analysis under thermal–oxidative aging for 2, 5, 14, and 28 days. The results demonstrate that the homogeneous repair system based on ultra-thin reinforced self-adhesive polymer-modified bituminous membranes exhibits superior overall performance, maintaining the highest peel strength with only minor degradation even after 28 days of accelerated aging. In contrast, the polymeric butyl self-adhesive membrane subjected to homogeneous repair exhibited rapid adhesion degradation after 14 days, whereas the heterogeneous repair system showed improved stability during intermediate aging stages. Low-temperature flexibility testing further revealed that root-resistant bituminous membranes exhibited a slower aging rate, with a cracking temperature increase of 7 °C after 28 days, compared to a 10 °C increase observed for ultra-thin self-adhesive membranes. These quantitative findings provide clear guidance for the selection of appropriate repair membrane systems under varying aging conditions in waterproofing engineering, particularly for maintenance and rehabilitation applications. Full article

The curing temperature is one of the key factors determining the strength of cement paste backfill (CPB). This study investigates the effects of low curing temperatures (5, 10, 15, and 20 °C) on the hydration performance and hydration products of CPB and analyzes their impact on the macroscopic mechanical properties. The experimental results show that when the curing temperature of CPB is low, the reaction activity of cement clinkers such as C₂S and C₃S decreases, and the number of cement particles participating in the hydration reaction resulting in a reduced quantity of hydration products in CPB. At the same time, low-temperature inhibits the polymerization and connection of silicate chains, and short silicate chains remain stable under low temperature conditions, resulting in a decrease in the polymerization degree of CPB. As the curing temperature increases, CPB gradually transitions to brittle behavior, and the cohesion of CPB shows a linear increase trend, while the internal friction angle shows an exponential increase trend. When the curing temperature is low, there are often one or several cracks around the tailing particles, and these weak bonding surfaces lead to a decrease in the strength of CPB. The results of this study will contribute to a better understanding of the hydration behavior of CPB in low curing temperatures. Full article

This study utilized a dynamic cross-linking algorithm to formulate a chemical cross-linked hydrogel model of poly(N-isopropylacrylamide) (PNIPAM) with N, N’-methylenebisacrylamide (BIS). Molecular dynamics (MD) simulations were conducted to investigate the temperature sensitivity and ibuprofen release mechanism of this hydrogel under varying cross-linking degrees and water contents. The low critical solution temperature (LCST) of the hydrogel was determined based on changes in solvent-accessible surface area (SASA) and hydrogen bond count. The LCST was found to be between 300 and 310 K. As the temperature increased, both SASA and hydrogen bond counts generally exhibited a gradual decrease. However, near the LCST, polymer chain collapse temporarily exposed the hydrophilic groups of the PNIPAM, forming hydrophilic regions that increased the contact area with water. This led to a transient increase in SASA (8% higher than that before 300 K) and hydrogen bond counts (6.25% higher than that at 290 K). Concurrently, Young’s modulus of the PNIPAM hydrogel was found to decrease with increasing water content (from 3.11 GPa to 2.59 GPa, representing a 16.7% decrease when water content increased from 0% to 50% for 80% cross-linking degree) and increase with rising cross-linking density (from 2.02 GPa to 2.94 GPa, representing a 45.5% increase when the cross-linking degree increased from 0% to 80% for 20% water content). These findings indicate that enhancing cross-linking density is an effective strategy for improving the hydrogel’s mechanical properties. A PNIPAM–ibuprofen delivery model was constructed and molecular dynamics (MD) simulations were conducted, revealing temperature dependence release behavior. Below the LCST, the PNIPAM hydrogel remains in a highly swollen state (PNIPAM single-chain radius of gyration, Rg = 0.64 nm at 290 K), with ibuprofen molecules adsorbed within the PNIPAM polymer chain network. Conversely, above the LCST, PNIPAM undergoes phase separation (Rg decreases to 0.56 nm at 320 K, representing a 12.5% decrease), resulting in volume contraction (cavity volume reduced by 35%) and disruption of the hydrogen bond network. This process results in the release of ibuprofen molecules, accompanied by an increase in their diffusion coefficient from 1.3817 × 10⁻⁹ (280 K) to 4.2847 × 10⁻⁹ m²/s (320 K). Concurrently, the interaction energy with PNIPAM experiences a decline, from −126.72 kcal/mol to −108.69 kcal/mol. The findings of this study provide insights into the optimization of the structural stability of ibuprofen delivery carriers. Full article

In bare-die integration based on low-temperature co-fired ceramic (LTCC) multilayer interconnects, broadband signal transmission is often limited by impedance mismatch, parasitic effects introduced by gold-wire bonding, and discontinuities in interlayer transitions. These issues collectively form major bottlenecks for achieving low-loss and wideband interconnections in high-frequency LTCC modules. To address these challenges, this paper proposes a multi-layer collaborative optimization framework for LTCC bare-die interconnects operating from 1 to 20 GHz. The proposed framework jointly considers impedance matching, bonding parameter optimization, and interlayer transition enhancement to achieve broadband and high-performance signal transmission. First, two T-type microstrip matching networks are designed based on the complex input impedance of the bare die, and their parameters are optimized using ADS (an integrated circuit design software, version 2020). Second, a microstrip–gold-wire bond–bare-die interconnect model is established to analyze bonding-induced parasitic effects, revealing that a bond center spacing of 0.12 mm provides optimal high-frequency performance. Third, for the stripline–via–microstrip transition, a coaxial-like via structure combined with a square defected ground structure (DGS) is introduced to improve impedance continuity and electromagnetic field confinement. Full-path cascaded simulations demonstrate that the proposed interconnect achieves a return loss better than −23.1 dB and an insertion loss below 0.45 dB across the 1–20 GHz frequency range. Compared with conventional LTCC interconnect structures, the proposed method improves return loss by more than 7 dB and reduces insertion loss by approximately 0.12 dB. The results confirm the effectiveness of the proposed collaborative optimization strategy and provide reusable design guidelines for broadband bare-die integration in high-frequency LTCC multilayer modules. Full article

Improving the hydrophilicity and tissue adhesion of polymers remains a significant challenge in tissue engineering and is often addressed by introducing functional groups that enhance polymer–tissue interactions. In this field, L-cysteine (Cys) and N-acetyl-L-cysteine (NAC) are particularly interesting due to their functional carboxyl and amine groups, which are prone to hydrogen bonding. Following this trend, this study (i) investigated the feasibility of grafting Cys or NAC onto the linear oligoitaconates via thio-Michael addition and (ii) examined the influence of amino acid incorporation on the material’s physicochemical properties. NMR-based calculations confirmed nearly 100% addition efficiency for Cys and a slightly lower, but still high, efficiency for NAC. FT-IR spectra confirmed thiol-based addition, as signal from the Cys/NAC S–H stretching vibrations was not observed in the adduct’s spectra. The obtained adducts showed thermal stability up to 200 °C and glass transition temperatures below −20 °C. They were soluble in common organic solvents, except for Cys adducts with oligo(propylene itaconate) and oligo(hexylene itaconate), which were water-soluble only. Due to the low molecular weight (below 1000 g/mol) of oligoitaconates, their adducts cannot serve as standalone scaffold components. However, they showed potential for use as modifiers for high-molecular-weight polylactide or poly(ɛ-caprolactone)-based scaffolds. Full article

Iridium pyridine diimine (PDI) complexes provide a versatile platform for highly reactive Ir–nitrido species with pronounced multiple-bond character, capable of activating H–H, C–H, Si–H, and even C–C bonds. Building on this chemistry, we extended our studies to a system with a terminal Ir–S bond, starting from our recently reported PDI–Ir–SH complex, which exhibits partial multiple-bond character. Upon addition of the 2,4,6-tri-tert-butylphenoxy radical, the corresponding phenol and a tentative Ir–S• radical intermediate are formed at ambient temperature. DFT and LNO-CCSD(T) calculations consistently reveal a low barrier for this process, with the spin density localized primarily on sulfur, accounting for subsequent S–S coupling reactions. Instead of the anticipated dimeric disulfido Ir–S₂–Ir complex formed along a least-motion pathway, a trisulfido Ir–S₃–Ir species was obtained, and characterized by NMR spectroscopy, X-ray crystallography and mass spectrometry. The formation mechanism of the trisulfido complex was further elucidated by DFT calculations. Remarkably, the sulfur-bridge formation is thermally reversible, regenerating the monomeric sulfanido Ir–SH complex. The origin of the hydrogen atom was investigated using H₂, D₂, and deuterated solvents. Full article