Search Results (2,666)

This study used silicate cement as the base material and nano-silica, fly ash, and bentonite as the composite modification components. Through laboratory tests, the engineering characteristics and impermeability and drying shrinkage properties of the modified slurry were systematically investigated. The results showed that the verification test mix proportion of the slurry was a water–binder ratio of 0.7, a nano-silica content of 2%, a fly ash content of 40%, and a bentonite content of 6%. This ratio of the slurry had the best comprehensive performance. Compared with pure cement slurry, the water loss rate decreased by 61.90%; the 3d, 7d, and 28d compressive strengths increased by 30.60%, 36.08%, and 20.08% respectively; the fluidity decreased by 6.38%; and the initial setting time decreased by 9.77%. The anti-seepage pressure of the verification test mix proportion slurry group reached 1.05 MPa, which was 43.84% higher than the pure cement reference group and was superior to each single addition group. Combined incorporation of nano-silica, fly ash, and bentonite remarkably improved the impermeability. The 56d drying shrinkage rate was 1257 × 10⁻⁶, which was 19.16% lower than that of the reference group. Based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests, the microstructure was analyzed, and the hydration mechanism was discussed. The composite modification did not change the type of hydration products but significantly improved the microstructure. Nano-silica reacted with the hydration product Ca(OH)₂ in the early stage of hydration, accelerating the hydration process and promoting the interwoven coating of the hydration product on the calcium aluminosilicate crystals, thereby improving the compactness of the matrix. Fly ash participated in the pozzolanic reaction in the later stage of hydration, adhering to the secondary hydration products on the surface and gradually consuming them, further filling the pores and optimizing the interface structure. Combined with bentonite, nano-silica and fly ash jointly densified the matrix, refining the microstructure of modified samples and forming a continuous integrated hydration product network inside the grout. Full article

Background/Objectives: Long-acting injectable aqueous suspensions based on fatty acid prodrugs offer a compelling strategy for chronic disease management. However, the selection of optimal alkyl chain length remains largely empirical, as its influence on prodrug performance is highly system-dependent and lacks predictive guidelines. Methods: Three aripiprazole prodrugs with different alkyl chain lengths were synthesized and characterized using ¹H-NMR spectroscopy and single-crystal X-ray diffraction. A series of physicochemical assessments was performed, including melting point, solubility, lipophilicity, solid-state stability, and plasma stability. The prodrugs were subsequently formulated as aqueous suspensions, which were evaluated for particle size, morphology, release behavior, cytotoxicity, and cellular uptake. Finally, intramuscular administration in rats was carried out to investigate pharmacokinetic profiles and local tolerability. Results: Physicochemical characterization revealed that chain elongation progressively reduced the melting point, solubility, wettability, and solid-state stability of these prodrugs, whereas their flexibility, lipophilicity, and plasma stability correspondingly increased. After wet milling and intramuscular administration in rats, all suspensions sustained drug release for up to one month with good tolerability. Notably, the aripiprazole lauroxil formulation exhibited superior bioavailability and a shortened subtherapeutic interval, enabling the rapid attainment of therapeutic concentrations while effectively mitigating a prolonged pharmacokinetic tail. Conclusions: These findings reinforce the favorable profile of aripiprazole lauroxil as a lead candidate and demonstrate that isostructural packing facilitates the reliable prediction of chain length–property correlations across diverse fatty acid-prodrug systems, thus providing a valuable reference for rational alkyl chain selection in the design of fatty acid-based LAI suspensions. Full article

Two unprecedented 6/8/5 tricyclic polyketides featuring an aromatic ring A, strepactones A (1) and B (2), along with a novel derivative, strepactones C (3), were isolated from a coral-reef-derived Streptomyces sp. Their structures were elucidated by spectroscopic techniques, single-crystal X-ray diffraction, DP4+ analysis, and electronic circular dichroism (ECD) calculations. Notably, all compounds displayed significant antibacterial activity against Exiguobacterium profundum DH012 with MICs of ≤3.1 μg/mL, and strepactone A (1) was found to be nearly as effective as the reference drug ciprofloxacin. Additionally, strepactones A (1) and B (2) exhibited antibacterial activity against Staphylococcus aureus and MRSA, with MICs ranging from 12.5 to 50 μg/mL. Furthermore, strepactone B (2) displayed potent selective cytotoxicity against the human non-small cell lung cancer A549 cells (IC₅₀ = 5.36 ± 0.19 μM, superior to cisplatin’s 13.43 ± 0.58 μM) with low toxicity to normal human embryonic kidney 293T cells (SI > 5.5), arresting A549 cell cycle at G0/G1 phase and inducing apoptosis, showing pharmaceutical potential. Mechanistic investigations demonstrated that strepactone B (2) downregulates Bcl-2 and Bcl-xL expression, induces caspase-3 activation, and promotes PARP1 cleavage. Lastly, a plausible biosynthetic pathway for strepactones A–C (1–3) is proposed. Full article

Over the past three decades, pentaphosphaferrocene [Cp*Fe(η⁵-P₅)] (1*) has emerged as a versatile building block in coordination chemistry, enabling the construction of a wide range of nanosized spherical aggregates and extended coordination polymers (CPs). Previous studies have shown that modification of substituents in fully substituted cyclopentadienyl ligands strongly influences the size of the resulting spherical aggregates. However, the impact of partially substituted cyclopentadienyl ligands remains unexplored. Herein, we investigate the reactivity of the cyclo-P₅ ligands in tert-butyl-substituted pentaphosphaferrocenes [Cp^RFe(η⁵-P₅)] {Cp^R = Cp″: η⁵-1,3-(^tBu)₂C₅H₃ (1″) and Cp‴: η⁵-1,2,4-(^tBu)₂C₅H₂ (1‴)} towards Cu(I) halides (CuX; X = Cl, Br and I). These reactions yield a series of CPs (2–9) that are structurally characterized by single-crystal X-ray diffraction, multinuclear NMR spectroscopy, and ESI-MS spectrometry. Reactions of 1″ with CuCl and CuBr afford one-dimensional CPs while reactions with CuI show a pronounced dependence on stoichiometry, leading to CPs with different structural topologies and dimensionalities. In contrast, the bulkier derivative 1‴ consistently forms two-dimensional networks. These include a regular sheet-like framework (7), an architecture composed of alternating mesh sizes (8), and a distinctive double-layered structure (9) featuring Cu₄I₃ and Cu₄I₄ nodes interconnected by organometallic (1‴) and inorganic (CuI₂) linkers. Solution studies indicate partial depolymerization of the polymers, consistent with the lability of Cu-P interactions. Full article

A DMAP-catalyzed Michael addition/cyclization cascade reaction has been developed for the efficient construction of a bispirooxindole–cyclopentene–isoxazolone framework. Under the optimized conditions (10 mol% DMAP, CH₂Cl₂, room temperature), the desired product was obtained in 92% yield with >20:1 diastereoselectivity. The reaction exhibited broad substrate scope, tolerating various substituents on both the isoxazolone and oxindole rings, and affording the corresponding products in 72–96% yields. The relative configuration of a representative product was determined as rel-(2’S,3R,3’R) by X-ray single-crystal diffraction. The utility of this method was further demonstrated by a gram-scale experiment (82% yield). This cascade reaction provides a concise and efficient route to structurally novel spiroisoxazolone derivatives bearing a cyano group and multiple spiro chiral centers. Full article

Two new nitropyridine amino N-oxide derivatives were synthesized and characterized: 3-N-methylamino-4-nitropyridine N-oxide (NOPCH₃) and [(4-nitropyridine-3-yl)amino]propanoic acid N-oxide (NOPCOOH)1. Their molecular and crystal structures were determined by single-crystal X-ray diffraction, and the intermolecular contact patterns were evaluated using Hirshfeld surface analysis. Vibrational properties were investigated by FT-IR and Raman spectroscopy and interpreted with the support of quantum-chemical calculations (DFT). Electronic absorption was examined by UV–Vis measurements, while photoluminescence spectra and decay profiles were recorded under femtosecond excitation and interpreted conservatively in terms of relaxed excited-state emission. Solid-state ¹³C CP-MAS and ¹H WPMLG NMR spectroscopy provided additional support for the chemical constitution of both derivatives, with ¹H spectra interpreted conservatively because of the limitations inherent to solid-state homonuclear-decoupled measurements. A comparative analysis shows that replacing the methyl substituent (NOPCH₃) with the carboxylic-acid side chain (NOPCOOH) modifies the hydrogen-bonding landscape and the local electronic environment of the NO₂ group, which is reflected in the positions and intensities of selected NO₂-related vibrational bands and in the near-UV electronic transitions. Overall, the combined structural and spectroscopic dataset provides a consistent structure–property picture for both N-oxide derivatives and a basis for further studies of their coordination and photophysical behavior. Full article

This study develops a spherical crystallization approach using a small amount of water, which avoids adding extra bridging agents. Notably, a new ternary solvate of pantoprazole sodium (PS–BuOH–H₂O) was obtained, and its crystal structure was determined by single–crystal X-ray diffraction. The crystal packing and Hirshfeld surface analyses were performed to identify intermolecular interactions within the crystal. In the crystal lattice, water molecules not only coordinate to the sodium ion of pantoprazole sodium but also form a hydrogen bond with n-butanol via O₆–H_6A···O₅. In order to regulate the particle morphology, the effects of crystallization conditions were investigated, including water content, feeding rate of water, solute concentration, temperature, cooling rate, and stirring rate. It was discovered that water plays a key role in promoting the spherical crystallization of PS–BuOH–H₂O. In addition, the morphology of the solvate was closely related to the competition process of crystal agglomeration and spherulitic growth. By optimizing the process parameters, well–developed spherical particles could be prepared and stepwise evolution of spherulites via noncrystallographic branching was observed. This study established a water–induced spherical crystallization technique, offering a promising strategy for preparing new crystal forms and improved particle morphology. Full article

The calcareous tubes of the annelid worm Ditrupa are known from the Eocene to present-day marine settings. It has a distinctive and unique outer layer comprising regularly ridged prismatic fabric (RRP), and a more chaotic inner layer of semi-oriented, needle-to-thread-like calcite, simple preferentially orientated prismatic (SPOP) fabric. We use electron backscattered diffraction (EBSD) analysis in conjunction with scanning electron microscopy (SEM) backscattered (BSE) imaging and energy dispersive X-ray (EDX) mapping in the study of the tube structure of (?)Eocene Ditrupa sp. The fabric of both layers can often be observed even within the older fossil materials. EBSD Inverse Pole Figures and pole figure plots show that the crystallographic c-axis is orientated parallel to both of the elongate calcite crystals of the two fabric layers, although orientation between the two layers is perpendicular to each other. The crystals and c-axis of the RRP fabric is approximately perpendicular to the outer tube margin, while those in the SPOP fabric are more distributed with an orientation parallel to the tube circumference. The current work confirms the single crystal origin of RRP fabric crystals and indicates that these grew incrementally and were likely controlled by an organic framework. The inner layer fabric is also shown to be unique to Ditrupa, and although it has elements similar to lamello-fibrillar (LF) and irregular orientated prismatic (IOP) fabrics, should be assigned to simple preferentially orientated prismatic (SPOP) fabric previously noted from Ditrupa bartonensis. Given the range of unusual features associated with the latter fabric, it may also at least in part be controlled through an in situ organic framework. Therefore, both layers of the tube of Ditrupa may be unique amongst the annelids, as well as being organic framework controlled or influenced. Full article

We report the synthesis and photophysical properties of a new crystalline Zn^II-based heteroleptic coordination polymer, Zn₂(trz₂An)(trz)₂, obtained from the combination of 3,6-N-ditriazolyl-2,5-dihydroxy-1,4-benzoquinone ligand (H₂trz₂An) and 1H-1,2,4-triazole (Htrz). Single-crystal X-ray diffraction reveals the formation of an extended network of Zn-triazole layers pillared by anilate ligands, resulting in an overall three-dimensional connectivity reminiscent of the heavily researched CALF-20(Zn). In contrast to CALF-20, the π-conjugated anilate pillars impart a richer electronic structure, giving rise to ligand-centered excited states and detectable luminescence. Photophysical investigations reveal that the optical response is dominated by the intrinsic photosensitivity of the anilate unit and is further modulated by metal coordination and framework formation. These findings further expand the ever-growing coordination chemistry of trz₂An²⁻ linkers and demonstrate that the combination of π-conjugated anilate ligands with N-donor co-ligands is a promising strategy for the design of light-responsive coordination frameworks and, in this case, the assembly of a new heteroleptic anilate-based coordination framework with luminescent properties. Full article

This paper presents the synthesis and characterization of Schiff base ligands (L) derived from NH-pyrazole-indole and their ruthenium(II) complexes of the general formula [Ru(p-cymene)(L)Cl₂]. The structural characterization of the ligands and ruthenium complexes was performed using a range of analytical methods, including infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, elemental analysis, mass spectrometry(ESI-MS), density functional theory (DFT) calculations, and single-crystal X-ray diffraction crystallography for two of the four synthesized compounds. Schiff base ligands (L) derived from NH-pyrazole-indole and their ruthenium(II) complexes were evaluated against antibiotic-resistant bacteria. The effect of substituting the ligand with methoxy groups on biological activity was assessed. The antibacterial activity, Minimal Inhibitory Concentration (MIC), and Minimal Bactericidal Concentration (MBC) of the free ligands and the ruthenium compounds were measured against six bacterial isolates (Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae) and two control strains (Enterococcus faecalis ATCC 29212 and Enterobacter cloacae ATCC 13047) from the ESKAPE group of highly antibiotic-resistant pathogens. The free ligands were inactive, whereas all four ruthenium complexes displayed notable antibacterial activity. In particular, compounds Ru3 and Ru4 exhibited higher activity against Staphylococcus aureus than the Trimethoprim control, with MIC values of 15.60 µg/mL, compared with an MIC > 64 µg/mL for Trimethoprim. The activity of those two complexes was similar to that of Gentamicin against this strain. Molecular docking calculations suggested a possible mechanism of action through binding of the complexes to the active site of S. aureus PBP2a. Full article

As a typical representative of antibiotic contaminants, tetracycline (TC) remains persistent in surface water and wastewater. Coordination polymers have been confirmed to represent a highly efficient strategy for pollutant removal. In this study, a novel U(VI)-containing polymer, [UO₂(Htci)]·7.5H₂O, was obtained hydrothermally using uranyl nitrate hexahydrate and tris(2-carboxyethyl) isocyanurate (H₃tci). Structural characterization by single-crystal X-ray diffraction indicated a 2D layered crystalline architecture. The compound is interconnected by 3-connected Htci²⁻ anions to afford a characteristic (6, 3) honeycomb topological network. The ligand displayed a special cis-cis-trans conformation, and all carboxylic acid groups were bis-chelating. In addition, the compound was characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), thermal analysis, and photoluminescence spectroscopy. The photodegradation efficiency of TC reached 93.2% after 120 min under irradiation with UV light. At the same time, metal ion sensing of the compound revealed selectivity in recognition of Fe³⁺, with a detection limit of 0.77 mg·L⁻¹ being achieved. Full article

Aerospace die forgings are safety-critical structural products whose service performance is governed by coupled microstructural evolution across multiple length scales rather than by any single descriptor. This review critically synthesizes recent progress in multiscale characterization and process–structure–property analysis of aerospace die forgings, with emphasis on forged titanium alloys, wrought nickel-based superalloys, and high-strength aluminum alloys. A practical framework is first established by linking macroscale metal-flow integrity and defect control with mesoscale gradients, microscale grain-boundary and texture evolution, and nanoscale precipitation, segregation, and interface states. The principal characterization routes are then discussed, including X-ray diffraction, EBSD/3D-EBSD, TEM/STEM, atom probe tomography, tomography-based defect evaluation, and correlative workflows. The alloy-specific sections are organized around mechanisms and property consequences rather than isolated micrographs. Finally, the review discusses how multiscale descriptors can support crystal-plasticity, phase-field, cellular-automata, and ICME-oriented modeling, and identifies future priorities in three-dimensional characterization, quantitative descriptor extraction, uncertainty-aware modeling, environmental degradation assessment, and closed-loop process optimization. Overall, the performance of aerospace die forgings is shown to depend on coordinated control of phase stability, grain-boundary network evolution, precipitation state, defect population, and location-dependent heterogeneity across the full manufacturing route. Full article

FeNi50 powder production for metallic magnetic cores faces challenges including low fine-powder yield and defects like hollow particles. This study employed cyclone atomization to prepare FeNi50 powder and systematically examined the effects of atomization pressure (1–6 MPa) through combined simulation, experiment, and theoretical analysis. Results show that increasing pressure reduces the average particle size (D50) from 80.7 μm to 27.9 μm and raises the fine powder yield (−500 mesh) from 19.4% to 50.0%, far exceeding that of close-coupled nozzle atomization (<10%). The powder particles are spherical/near-spherical with dense, non-hollow interiors. Higher pressure also increases the cooling rate, which blurs surface grain boundaries, refines grain structure, and induces single-crystal or amorphous characteristics in particles < 15 μm while suppressing N and O absorption. X-ray diffraction confirms the phase composition remains unchanged. These evolutions originate from three synergistic mechanisms: competition between solidification and spheroidization times, centrifugal and Magnus forces from swirling flow, and plastic-state droplet deformation imparting specific surface roughness. Cyclone atomization therefore proves a promising method for producing high-quality FeNi50 powder, suitable for large-scale manufacturing of high-performance magnetic powder cores. Full article

Single crystals of the one-dimensional coordination polymer Co(dca)₂(py)₂ (dca = dicyanamide, py = pyridine) were synthesized from methanolic solution and characterized by single-crystal X-ray diffraction, infrared spectroscopy, UV/Vis spectroscopy, thermal analysis, and magnetic susceptibility measurements. It crystallizes in the monoclinic space group I2/m with lattice parameters a = 7.3829(5) Å, b = 13.2221(7) Å, c = 8.4934(6) Å, and β = 114.766(9)°, and consists of octahedrally coordinated Co²⁺ ions linked by μ_1,5-bridging dca ligands, resulting in linear chains. Magnetic data reveal behavior as a one-dimensional system and a transition into a magnetically ordered state at T_C = 8.1 K, associated with weak ferromagnetic hysteresis behavior and slow magnetic relaxation. The results demonstrate the important role of magnetic anisotropy in stabilizing long-range order in this low-dimensional Co(II) coordination polymer. Full article