Search Results (26,917)

Nucleation and growth during the crystallization process are crucial steps that determine the crystal structure, size, morphology, and purity. A thorough understanding of these mechanisms is essential for producing crystalline products with consistent properties. This study investigates the solubility of tacrolimus (FK506) in an ethanol–water system (1:1, v/v) and examines its crystallization kinetics using batch crystallization experiments. Initially, the solubility of FK506 was measured, and classical nucleation theory was employed to analyze the induction period to determine interfacial free energy () and other nucleation parameters, including the critical nucleus radius (), critical free energy (), and the molecular count of the critical nucleus (). Crystallization kinetics under seeded conditions were also measured, and the parameters of the kinetic model were analyzed to understand the effects of process states such as temperature on the crystallization process. The results suggested that increasing temperature and supersaturation promotes nucleation. The surface entropy factor () indicates that the tacrolimus crystal growth mechanism is a two-dimensional nucleation growth. The growth process follows the particle size-independent growth law proposed by McCabe. The estimated kinetic parameters reveal the effects of supersaturation, temperature, and suspension density on the nucleation and growth rates. Full article

Three nickel, copper, and zinc complexes with dicarboxylic acids (3,3′-dithiodipropionic acid (H₂dtdp) and fumaric acid (H₂fu)) and N-donor ligands (1,10-phenanthroline (phen), N′–methyldipropylenetriamine (mdpta), and N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdien)) were synthesized. These complexes were characterized using elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Interestingly, [Ni(dtdp)(phen)(H₂O)₃]∙0.5H₂O (1) is a mononuclear complex, where the dtdp dianion employs only one carboxylate group for coordination to the central nickel atom. [(ClO₄)(mdpta)Cu(μ-dtdp)Cu(mdpta)(H₂O)](ClO₄) (2) is a dinuclear copper complex with a dtdp bridge and different coordination on the copper center. [{Zn(pmdien)(H₂O)}₂(μ-fu)](ClO₄)₂ (3) is a symmetric dimer with a bridging fumarate ligand. These coordination compounds were tested for their antibacterial activities on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacteria strains. All the complexes show moderate activities on the mentioned strains. Full article

In this paper, a kind of metastructure–photonic crystal (MPC) with multi-frequency asymmetric absorption–transmission properties is proposed. It is composed of various dielectric layers arranged in a periodically tilting pattern. When electromagnetic waves (EMWs) enter from the opposite direction, MPC shows an obvious asymmetry. EMWs are absorbed at 13.71 GHz, 14.37 GHz, and 17.10 GHz in forward incidence, with maximum absorptions of 0.919, 0.917, and 0.956, respectively. In the case of backward incidence, transmission above 0.877 is achieved. Additionally, the MPC is utilized for refractive index (RI) sensing, allowing for wide RI range detection. The refractive index unit is denoted as RIU. The RI detection range is 1.4~3.0, with the corresponding absorption peak variation range being 17.054~17.194 GHz, and a sensitivity of 86 MHz/RIU. By adjusting the number of MPC cycles and tilt angle, the sensing performance and operating frequency band can be tailored to meet various operational requirements. This MPC-based RI sensor is simple to fabricate and has the potential to be used in the development of high-performance and compact sensing devices. Full article

The synthesis and characterization of low-melting-point insensitive energetic materials are crucial due to their increasing applications in melt–cast explosives. In this work, a furazan-derived energetic compound, 3,4-bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF), exhibiting insensitive and high-energy characteristics, is rationally designed and synthesized. The structure of DAeTF is characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elemental analysis, mass spectrometry, and single-crystal X-ray diffraction. The thermal properties of DAeTF are investigated using differential scanning calorimetry, in situ FTIR spectroscopy and thermogravimetric-differential scanning calorimetry–Fourier transform infrared–mass spectrometry and thermal decomposition mechanism was elucidated in combination with bond energy calculations. The detonation performance of DAeTF is predicted by the EXPLO5 program. The results indicate that DAeTF has thermal stability (T_d = 251.7 °C), high energy level (D = 7270 m/s) and significant insensitivity (IS = 60 J). Additionally, its relatively low melting point (T_m = 60.5 °C) facilitates processing and loading. These characteristics indicate that DAeTF is a promising candidate as an insensitive melt–cast explosive in future applications. Full article

The Changbai volcano, a globally recognized hotspot of volcanic activity, has garnered significant attention due to its persistent seismicity and ongoing magma activity. The volcano’s discontinuities and magma dynamics have raised concerns about the likelihood of future eruptions, which would likely result in substantial ecological, climatic, and economic impacts. Consequently, a comprehensive understanding of the Changbai volcanic system is essential for mitigating the risks associated with volcanic activity. In recent years, the P-wave coda autocorrelation method has gained popularity in lithosphere exploration as a reliable technique for detecting reflection coefficients. Additionally, the Common Reflection Point stacking approach has been employed to superimpose reflection signals in a spatial grid, enabling continuous observation of reflection coefficients in the study area. However, the accuracy of this approach is heavily reliant on better spatial data coverage. To better understand the internal dynamics of the Changbai volcano, we applied this approach to a densely packed short-period seismic array with an average station spacing of less than 1 km. Our results were constrained using waveform data of reflection coefficients and Moho dip angles. Our findings revealed a discontinuity in the Moho, which may indicate a conduit for mantle magma entering the crust. Furthermore, we identified two low-velocity anomalies within the crust, likely representing a magma chamber comprising molten and crystallized magma. Notably, our results also provided a clear definition of the lithosphere–asthenosphere boundary. Full article

Our study aimed to elucidate the mechanisms behind the interaction between calcium oxalate (CaOx) crystals and renal tubular epithelial cells through transcriptome sequencing analysis. HK-2 cells were stimulated with or without CaOx monohydrate crystals and subjected to RNA-seq to assess the effects of CaOx crystals on gene expression changes, key pathways, and molecular players during this interaction. A total of 629 differentially expressed genes (DEGs) were identified between the control group and experimental group, with 491 genes up-regulated and 138 down-regulated. Functional enrichment analysis indicated that the DEGs were significantly associated with endoplasmic reticulum stress (ERS) and unfolded protein response. To validate our findings, we compared our results with the public dataset GSE73680 and confirmed the increased expression of two ERS-related DEGs, CHAC1 and FGF21, in renal papillary tissues from patients with CaOx stones. Collectively, these findings suggest that ERS plays a crucial role in the crystal–cell interaction and highlight the potential for developing therapeutic strategies aimed at reducing CaOx stone formation by targeting ERS-related molecules and pathways. Full article

Mining in the Russian Far East has been developing for more than 100 years, resulting in the formation of mining technogenic systems that negatively affect all components of the environment. The purpose of this paper is to develop and present an ecological and geochemical model of supergene processes in tinsulfide and polymetallic ore mining systems. This paper presents, for the first time, the results of long-term field observations (more than 50 years): studies of numerous secondary minerals (more than 80) identified in mine workings and tailings, their natural associations, as well as the sequence, zonality, and stages of mineral formation as well as the characteristics of hydrochemical samples of river waters, contaminated by acid mine drainage (30 years of observations). Experimental modeling of sulfide oxidation was carried out under laboratory conditions (electrochemical method) and using Selektor software, which made it possible to study the process of acid mine drainage formation and to show the metal ions and ionic complexes composition, to establish Eh-pH parameters of crystallization for 52 secondary minerals, associations of primary and secondary minerals. The influence of water components on the formation of slurry and drainage in different time periods (dry, heavy rainfall, and snowmelt) is shown, and their mixing at the geochemical barrier “acid mine drainage—surface natural waters” is described. Experimental results are verified with numerous in-situ observations and mineralogical studies. The work allowed for the presentation of an environmental–geochemical model of ecosphere pollution, which describes not only the negative impact of sulfide-bearing systems of Russian Far East mining districts but locations all over the world. Full article

Current liquid crystal (LC) lenses cannot achieve lossless arbitrary movement of the optical axis without mechanical movement. This article designs a novel bottom electrode through simulation and optimization, which forms a special LC lens with an Archimedean spiral electrode, realizing a 3D LC wedge and an arbitrarily movable LC lens. When only the bottom electrode is controlled, it achieves a maximum beam steering angle of 0.164°, which is nearly an order of magnitude larger than the current design. When the top and bottom electrodes are controlled jointly, a 0.164° movement of the lens optical axis is achieved. With focal length varies, the movement of the optical axis ranges from zero to infinity, and the lens surface remains unchanged during movement. The focus can move in a 3D conical area. When the thickness of the LC layer is 30 μm, the fastest response time reaches only 0.635 s, much faster than now. Full article

Uninterrupted breakthroughs in the room temperature piezoelectric properties of KNN-based piezoceramics have been witnessed over the past two decades; however, poor temperature stability presents a major challenge for KNN-based piezoelectric ceramics in their effort to replace their lead-based counterparts. Herein, to enhance temperature stability in KNN-based ceramics while preserving the high piezoelectric response, multilayer composite ceramics were fabricated using textured thick films with distinct polymorphic phase transition temperatures. The results demonstrated that the composite ceramics exhibited both outstanding piezoelectric performance (d₃₃~467 ± 16 pC/N; S~0.17% at 40 kV/cm) and excellent temperature stability with d₃₃ and strain variations of 9.1% and 2.9%, respectively, over a broad temperature range of 25–180 °C. This superior piezoelectric temperature stability is attributed to the inter-inhibitive piezoelectric fluctuations between the component layers, the diffused phase transition, and the stable phase structure with a rising temperature, as well as the permanent contribution of crystal orientation to piezoelectric performance over the studied temperature range. This novel strategy, which addresses the piezoelectric and strain temperature sensitivity while maintaining high performance, is well-positioned to advance the commercial application of KNN-based lead-free piezoelectric ceramics. Full article

Drying experiments with varying air temperature and humidity were conducted to investigate the influence of the drying process on the crystallization of thin sucrose films. For the first time, the effects of the nucleation onset, nucleation rate, and growth rate were investigated in situ and their differentiated influence on product crystallinity could be assessed. The growth rate was not influenced by air humidity but showed a strong dependence on temperature. It increased with drying temperature; however, at high temperatures, growth was inhibited when the water content falls below a critical level. Noticeable differences in nucleation behavior could be observed with regard to air humidity. Dry air led to crystallization onsets at lower levels of supersaturation, while moderately humid air retarded it. At higher temperatures, nucleation onset commenced at lower water contents but at a constant supersaturation level. The nucleation rate doubled in experiments with moderately humid air (15% RH), while an elevated drying temperature showed generally lower nucleation rates. The observed differences in the nucleation onset and rate could be explained by the film-internal concentration profile, which is strongly influenced by drying parameters. The insights therefore provide a differentiated understanding of the formation of the physical state and how it can be influenced during convective drying. Full article

Poly(p-dioxanone) (PPDO) is crystallized with amorphous poly(p-vinyl phenol) (PVPh) and tannic acid (TA) as co-diluents to regulate and induce dendritic-ringed PPDO spherulites, with spoke- or sector-bands, aiming for convenience of analyses on interior lamellar assembly. Morphologies and interior lamellar arrangement leading to the peculiar rings on individual dendrites are evaluated by using polarized-light microscopy (PLM) and scanning electron microscope (SEM). Combinatory microbeam small-/wide-angle X-ray scattering (SAXS/WAXS) analyses further confirm the unique assembly patterns in periodic cycles. Alternate gratings are packed with periodic ridges composed of feather-like branches and the valley is featured with some embossed textures. The periodic gratings in the ringed spokes resemble those in nature’s structured coloration and are proven to display light-interference iridescence. Full article

This study investigates the impact of kaolin and boehmite alumina binders on the synthesis, catalytic properties, and attrition resistance of a La_0.7Sr_0.3FeO₃ (LSF) perovskite catalyst designed for the chemical looping partial oxidation (CLPO) of methane to produce synthesis gas sustainably. The as-synthesized and used catalysts with varying kaolin and boehmite alumina contents (KB_(x,y)/LSF) were scrutinized by a variety of characterization methods, including XRD, FE-SEM/EDS, BET, TPD-NH₃, and TPD-O₂ techniques. The catalytic activity of the synthesized samples was tested at 800 to 900 °C in a fixed-bed reactor producing syngas through the CLPO process over the consecutive redox cycles. Additionally, the attrition resistance of the fresh and used catalyst samples was examined in a jet cup apparatus to assess their durability against the stresses induced by thermal shocks or changes in the crystal lattice caused by chemical reactions. The characterization results showed the pure perovskite crystal structure of KB_(x,y)/LSF catalysts demonstrating adequate oxygen adsorption capacity, effective coke mitigation capability, robust thermal stability, and resilience to agglomeration during repetitive redox cycles. Among the tested catalysts, KB_(25,15)/LSF was identified as the superior sample, as it could consistently produce syngas with a suitable H₂:CO molar ratio varying from 2 to 3 within ten redox cycles at 900 °C, with CH₄ conversion and CO selectivity values up to 64% and 87%, respectively. The synthesized catalysts demonstrated a logarithmic attrition pattern in the jet cup tests at room temperature, featuring high attrition resistance after the erosion of particle shape irregularities or weakly bound particles. Moreover, the KB_(25,15)/LSF catalyst used at 900 °C showed great resistance in the attrition test, warranting its endurance in the face of extraordinarily harsh conditions in fluidized bed reactors employed for the CLPO process. Full article

The chemical investigation of the South China Sea soft coral Sinularia densa has resulted in the isolation of seven new terpenoids, including two new meroterpenoids, namely sinudenoids F–G (1–2), and five new cembranes, namely sinudenoids H–L (3–7). Their structures and absolute configurations were elucidated based on extensive analyses of spectroscopic data, single-crystal X-ray diffraction, comparison with the literature data, and quantum chemical calculations. Among them, sinudenoid F (1) and sinudenoid G (2) are rare meroterpenoids featuring a methyl benzoate core. Sinudenoid H (3) possesses a rare carbon skeleton of 8, 19-bisnorfuranocembrenolide, which is the second reported compound with this skeleton. In a bioassay, sinudenoid H (3) exhibited better anti-inflammatory activity compared to the positive control indomethacin at 20 µM in CuSO₄-treated transgenic fluorescent zebrafish. Moreover, sinudenoid J (5) and sinudenoid L (7) exhibited moderate anti-thrombotic activity in arachidonic acid (AA)-induced thrombotic zebrafish at 20 µM. Full article

The hydrothermal synthesis of CuO/NiO composites was conducted using banana fruit biomass waste. In this study, X-ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy were used to investigate the crystalline properties, shape structure, and functional group characterization of CuO/NiO composites. The typical morphology of the prepared materials consisted of irregular nanoparticles arranged into clusters of less than 200 nanometers in size. In spite of this, the CuO/NiO composites showed monoclinic CuO and cubic NiO phases and were therefore successfully synthesized. It was observed that rotten banana fruit juice had a significant impact on the particle size and crystal quality of CuO/NiO composites. This was due to the presence of capping, reducing, and stabilizing agents in banana fruit juice. Under alkaline conditions, the CuO/NiO composites were found to be highly electro catalytically active toward the oxidation of urea. Sample 2, which was prepared by adding 1.2 g of CuO decorated with NiO, showed a linear increase in urea detection ranging from 0.1 mM to 17 mM, with a limit of detection of 0.004 mM. Furthermore, sample 2 of the CuO/NiO composite demonstrated exceptional stability, selectivity, and reproducibility. Consequently, sample 2 of CuO/NiO could effectively detect urea in spinach, lotus root, milk, and curd. The improved performance of sample 2 of the CuO/NiO composite can be attributed to its favorable surface properties, which contain enriched active sites and a rapid charge transfer rate. Full article

In this work, the influences of La₂O₃ addition on the connectivity of the glass network, phase compositions and microstructural evolution of weld slag were investigated through Raman spectrum, X-ray powder diffraction (XRPD), SEM and EBSD technologies. All experimental results indicated that La₂O₃ addition could modify the whole glass network’s connectivity and short-ordered units. According to the Raman spectrum, only 1 wt.% La₂O₃ addition resulted in the occurrence of a unique linking mode of Si-O and Al-O tetrahedrons that was assigned to feldspar phases (albite or anorthite). Further XRPD examination showed that the primary phases were albite and anorthite, which agreed with the Raman results. Moreover, enhanced linkage between Si-O and Al-O tetrahedrons needs a large amount Na⁺ to achieve electric neutrality. This repaired the connectivity of the slag network due to the lack of Na⁺. Additionally, the solubility of La₂O₃ in the slag matrix was limited to about 3 wt.%. Adding further La₂O₃ to this weld slag, the existence form of La₂O₃ retained its original status. Thus, La₂O₃ addition that exceeded 3 wt.% had little effect on the slag connectivity besides providing a phase interface. In conclusion, La₂O₃ addition in weld slag could promote the hardness and the formation of feldspar phases. Feldspar is an extremely fragile silicon aluminate crystal. The factors mentioned above caused the detachability to be enhanced when adding La₂O₃. Full article