Production Of Crystals Research Articles

Structural, Chemical and Magnetic Characterization of Quartz Sand from Cluj Area, Romania for Future Beneficiation in the Glass Industry.

For use in crystal glass production, quartz sand must contain less than 0.09% iron. If the sand contains more than 0.09% Fe, the iron must be removed. In the present study, quartz sand from tailings ponds near the Cluj area of Romania is analyzed for potential use in the glass industry, after magnetic separation. The particle size distribution of raw sand was determined, and mineralogical analyses was realized. Using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), morphology and elemental distribution maps on the particle was performed. The evolution of the iron content versus the particle size was analyzed. Using X-ray diffraction, the phases occurring in the sand were investigated in relation to the particle size. Magnetic separation with two magnets, having different energy, was performed for identifying the phases attached to the magnetic particles. Magnetic hysteresis measurements evidenced complex and multiple iron phase behavior.

Prediction of the Layer Growth Rate in Static Melt Crystallization

The crystal layer growth rate is governed by the heat transfer in a layer melt crystallization process and is essential to the separation efficiency. Herein, a numerical model was proposed to predict the solid–liquid (S-L) interface temperature and the growth rate of the crystal layer. The heat transfer equation was taken as the governing equation, combining crystal layer growth kinetics, mass balance, and heat balance in the model which were solved using the finite volume method. The calculation results provided details of temperature distribution in the crystal layer, temperature of the moving S-L interface, and the layer growth rate. The simulated results were validated by experiments using P-xylene as the model substance. Finally, the crystal layer growth rate was found to be very sensitive to the seeding supercooling, especially at the early stage right after seeding. The proper seeding supercooling could be optimized by this model according to both the optimized crystal layer growth rate and productivity.

Calcium isotope ratio in kidney stones: preliminary exploration of mechanism from the geochemical perspective.

Stable calcium (Ca) isotope ratios are sensitive and radiation-free biomarkers in monitoring biological processes in human bodies. Recently, the Ca isotope ratios of bone, blood, and urine have been widely reported to study bone mineral balance. However, as a pure Ca crystallization product, there is no report on the Ca isotope ratios of kidney stones, even though the prevalence of kidney stones is currently on the rise. Here, we measured Ca isotope data of 21 kidney stone samples collected in Beijing, China. The δ44/42CaNIST 915a values ranged from 0.25‰ to 2.85‰ for calcium oxalate, and from 0.38‰ to 3.00‰ and 0.61‰ to 0.69‰ for carbonate apatite and uric acid, respectively. Kidney stones have heavier Ca isotope ratios than bone or blood, which is probably because complexed Ca contains more heavy Ca isotopes than free Ca2+. Ca isotope evidence suggests that magnesium (Mg) affects kidney stone formation, as the δ44/42CaNIST 915a value is inversely correlated with the Ca/Mg ratio. This study provides important preliminary reference values on the Ca isotopic composition of kidney stones and proposes a factor influencing Ca isotope fractionation in biological processes for future research.

Numerical and experimental investigation of the thermal behavior and microstructure of wire arc additive manufactured 316L stainless steel straight wall part

The heat transfer behavior during wire arc additive manufacturing is closely related to the dimensional accuracy and performance of the formed part. To investigate the thermal behavior of stainless steel 316L straight wall part fabricated by the wire arc additive manufacturing process, a three-dimensional transient finite element model is established based on the double elliptic heat source model. At the same time, the temperature measurement experiment on the characteristic position of the substrate is carried out. The thermal cycle curve obtained by the finite element model is in good agreement with the measured result. By analyzing the simulation results, the finite element model established can effectively reveal the thermal behaviors such as melting, solidification, heat accumulation and remelting during the forming process of the straight wall part. In addition, the solidification parameters obtained by the model are correlated with the microstructure. High G/R induces the production of cellular crystals and columnar dendrites, on the contrary, the formation of equiaxial crystals, which provide guidance for the prediction of the morphology of the microstructure.

The explosive-effusive transition within the Miocene Fataga suite, Gran Canaria

Many volcanoes show transitions between explosive and effusive eruptive styles both through the history of the volcano as a whole and occasionally within the course of a single eruption. These differing eruptive styles have vastly different implications for hazard assessments in surrounding regions and so understanding such changes is important. Here, we investigate the intercalated lavas and ignimbrites of the Miocene Fataga Group on the island of Gran Canaria, Spain. Ignimbrites reflect the products of explosive events from the Tejeda caldera, while lavas found within the pyroclastic succession were erupted from extra-caldera sources some 5–10 km from the caldera margin. The ignimbrites exhibit textural complexity containing both crystal-poor juvenile pyroclasts and late-erupted crystal-rich juvenile clasts interpreted to reflect interaction between cumulates and recharge magmas. The lavas meanwhile are almost phenocryst-free, with the exception of few large (cm-scale), unzoned sanidine crystals. Despite their textural differences, the lavas are geochemically similar (in terms of bulk rock and feldspar compositions) to the crystal-poor juveniles in the ignimbrites. Oxygen and lead isotopic compositions of the lavas and surrounding ignimbrites reveal that the magmas shared a deeper source and that petrographic variability is imprinted upon the magmas at shallow levels. We interpret the lavas as originating from peripheral magmatic pockets, on the edges of the main caldera-feeding reservoir. These peripheral magma chambers felt the effects of recharge only as slight thermal fluctuations that fostered the production of the large sanidine crystals. Our findings highlight the potential for storage of magmas aside from the main magmatic system that may represent an underappreciated hazard at volcanoes worldwide.

Growth mechanism of carbonated tricalcium silicate (C3S) under the high concentration of CO2: A novel research for CCUS wells

Under the engineering background of the carbon dioxide capture and geological storage technology (CCUS) cementing project, an experiment on the generation of cement single-phase tricalcium silicate CO2 carbonization products were carried out. Combining the phase diffraction pattern data and the thermogravimetric experiment, a relative crystallinity algorithm is proposed, which combines the quantitative results of the carbonized products with the relative crystallinity (RCP) results of each component. The growth and development mechanism of tricalcium silicate carbide crystal products under high temperature, high pressure and high concentration CO2 environment is deduced. The experimental results show that under the conditions of early gas phase carbonization, the carbonization rate of C3S first increases and then decreases as the carbonized crystal product grows. Under the conditions of early liquid phase carbonization, the carbonization rate of C3S first decreases and then increases with the generation and fragmentation of the hydration barrier layer. It provides a research basis and a new perspective for the subsequent analysis of the changes in the microstructure of the cement paste in the carbonization process under the CCUS engineering background.

Influence of phenolic compounds on color formation at different stages of the VHP sugar manufacturing process

Phenolic compounds are natural dyes contained in sugarcane juice and represent an important parameter in industrial processing, as they significantly affect the color formation of raw sugar. This study investigated the relationship between color formation and phenolic compounds during a Very High Polarization (VHP) sugar manufacturing process, in which the RB92579 genotype represents about 50% of the processed sugarcane. The products evaluated during the industrial processing of sugarcane were: raw juice, mixed juice, lime-treated juice, clarified juice, syrup, massecuite, and VHP sugar. The polyphenols catechin (CAT), chlorogenic acid (CGA), caffeic acid (CAF), vanillin (VAN), syringaldehyde (SYR), p-coumaric acid (p-COU), coumarin (CUM), and rutin (RUT) were quantified by high-performance liquid chromatography (HPLC). The highest concentrations of CGA and SYR were obtained from the sucrose crystallization product (massecuite), similarly to the parameters of color, total phenols and the total polyphenol content. CGA was the predominant polyphenol in the samples of clarified juice, syrup, massecuite and VHP sugar, with the latter presenting concentrations above 50%. The presence of phenolic compounds provided different indices of color during the production process. In this context, chlorogenic acid (CGA) was the compound that presented the most expressive results, contributing significantly to the formation of color in sugarcane processing products, which is a fact that has not yet been reported in the literature. The color of the VHP sugar crystals also had a positive relationship with the concentration of phenolics, with greater evidence for CGA.

Study on Thermodynamics and Kinetics of Cephalexin Enzymatic Hydrolysis and Its Process Development to Prepare 7-ADCA

Cephalosporin enzymatic hydrolysis technology is a green technology for recovering 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) from cephalosporin mother liquor. Solubility is critical for the production and purification of 7-ADCA. In this paper, the solubility of 7-ADCA and phenylglycine was measured. Solubility-temperature correlation model and solubility-pH correlation model were investigated, and Akaike information criterion (AIC) analysis was performed. The kinetic parameters of the enzymatic hydrolysis reaction of cephalexin, cefradine, and cefadroxil were determined, and the reaction rates under different substrate concentrations were measured, and the Lineweaver–Burk double-reciprocal equation was used to draw a graph. The Michaelis constants Km/(mg/mL) were 73.98, 583.84, 38.66, Vmax/(mg/mL·min) 4.20, 16.00, 1.96, respectively. The experimental results show that amphoteric compounds and buffers can prompt the reaction, low concentration of methanol promotes the reaction, while high concentration of methanol inhibits the reaction, and ethanol, isopropanol, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), ethylene glycol (EG), 1,4-dioxane all have different degrees of inhibition on the reaction speed. Finally, based on thermodynamic and kinetic studies, a process technology for the preparation of 7-ADCA by hydrolysis catalyzed of cephalexin was developed. It was confirmed that the proposed process route of preferential removal of phenylglycine by elution and/or cooling crystallization was reasonable and effective. The 7-ADCA crystal products obtained by crystallization were characterized by PXRD, thermal analysis, infrared, electron microscope, and high-performance liquid chromatography (HPLC).

Crystallization of SrAl12O19 Nanocrystals from Amorphous Submicrometer Particles.

Advanced instrumentation and modern analysis tools such as transmission electron microscopy (TEM) have led to phenomenal progress in understanding crystallization, in particular from solution, which is a prerequisite for the design-based preparation of a target crystal. Nevertheless, little has been understood about the crystallization pathway under high-temperature annealing (HTA) conditions. Metal oxide crystals are prominent materials that are usually obtained via HTA. Despite the widespread application of hydro-/solvothermal methods on the laboratory scale, HTA is the preferred method in many industries for the mass production of metal oxide crystals. However, poor control over the morphology and grain sizes of these crystals under extreme HTA conditions limits their applications. Here, applying ex-situ TEM, the transformation of a single amorphous spherical submicrometer precursor particle of SrAl12O19 (SA6) at 1150 °C toward a nanosized thermodynamically favored hexagonal crystal is explored. It is illustrated in real space, step by step, how both kinetic and thermodynamic factors contribute to this faceting and morphology evolution. These results demonstrate a nonclassical nucleation and growth process consisting of densification, crystallite domain formation, oriented attachment, surface nucleation, 2-dimensional (2D) growth, and surface diffusion of the atoms to eventually result in the formation of a hexagonal platelet crystal. The TEM images further delineate a parent crystal driving the crystal lattice and morphological orientation of a network of interconnected platelets.

The Evolving Chronology of Moon Formation

Defining the age of the Moon has proven to be an elusive task because it requires reliably dating lunar samples using radiometric isotopic systems that record fractionation of parent and daughter elements during events that are petrologically associated with planet formation. Crystallization of the magma ocean is the only event that unambiguously meets this criterion because it probably occurred within tens of millions of years of Moon formation. There are three dateable crystallization products of the magma ocean: mafic mantle cumulates, felsic crustal cumulates, and late-stage crystallization products known as urKREEP (uniform residuum K, rare earth elements, and P). Although ages for these materials in the literature span 200 million years, there is a preponderance of reliable ages around 4.35 billion years recorded in all three lunar rock types. This age is also observed in many secondary crustal rocks, indicating that they were produced contemporaneously (within uncertainty of the ages), possibly during crystallization and overturn of the magma ocean. ▪The duration of planet formation is key information in understanding the mechanisms by which the terrestrial planets formed.▪Ages of the oldest lunar rocks range widely, reflecting either the duration of Moon formation or disturbed ages caused by impact metamorphism.▪Ages determined for compositionally distinct crust and mantle materials produced by lunar magma ocean differentiation cluster near 4.35 Gyr.▪The repeated occurrence of 4.35 Gyr ages implies that Moon formation occurred late in Solar System history, likely by giant impact into Earth.

Bimodal distribution of amphibole-melt apparent dihedral angles in the product of the early crystallization of hydrous basaltic melts

• Amp-Melt-Amp apparent dihedral angle distribution shows bimodality. • Bimodality becomes obvious after annealing for more than 1 h at 0.6 GPa and 970 °C. • Median-standard deviation evolution obeys no longer a unidirectional change. • The high anisotropy of amphibole is the main cause of the bimodality. The dihedral angle of mineral-melt is a very important parameter for further understanding the textural evolution of magma crystallization. In this study, we have investigated the amphibole-melt dihedral angle distribution of four previous experimental samples at 0.6 GPa and 970 °C with annealing time of 1 h, 10 h, 60 h, and 100 h, as well as two additional experiments with annealing time of 5 h and 30 h. In this experiment, we have achieved the assemblage of amphibole + granodioritic melt ± traces of other minerals in the process of melt crystallization under the above experimental conditions. The apparent dihedral angles of amphibole-melt of the experimental products were obtained by randomly measuring the dihedral angles in the backscattered images. The results indicate that the apparent dihedral angle presents a gradually obvious bimodal distribution with the increasing annealing time. The high anisotropy of amphibole is believed to be the main cause of the bimodal characteristics of the apparent dihedral angle distribution. Consequently, two Gauss functions are used to fit one distribution. As the annealing time increases, the median-standard deviation relationships of the apparent dihedral angle for these two Gauss functions show great differences. Therefore, our experiments proved that in the amphibole-melt system, the median-standard deviation with the growth of textural equilibrium in the early crystallization is no longer a unidirectional change. Furthermore, combining the results of this study and the previous work, whether the dihedral angle distribution in the early crystallization is unimodal or bimodal may have great relationship with the anisotropy of minerals.

Simulation of flow field in silicon single-crystal growth using physics-informed neural network with spatial information

Melt convection plays a crucial role in the growth of silicon single crystals. In particular, melt flow transfers mass and heat, and it may strongly affect the crystal growth conditions. Understanding and controlling convection remains a significant challenge in industrial crystal production. Currently, numerical methods such as the finite element method and the finite volume method are mainly used to simulate melt convection in the crystal growth process. However, these methods are not suitable for most applications with real-time requirements. Physics-informed neural networks (PINNs) have the advantages of fast calculation and wide application. They provide a new concept for the numerical solutions of nonlinear partial differential equations (PDEs). This paper proposes a PINN with spatial information to solve the silicon melt flow model, which does not depend on any simulation data. As the network depth (number of layers) increases, the derivative information in the PDE loss becomes weak, which reduces the expression of the original features in the loss function. Therefore, this study introduces spatial information into the hidden layer of the network, thereby enhancing the correlation between the network and the original input and improving the expression ability of the network. Specifically, silicon melt flow models under three rotating conditions are considered. Compared with other methods, the proposed algorithm can accurately capture regions with complex local morphology. The experimental results reveal the flow characteristics of the silicon melt and confirm the effectiveness of the proposed algorithm. All codes and data attached to this manuscript are publicly available on the following websites: https://github.com/callmedrcom/SIPINN.

Correlations between olivine composition and groundmass mineralogy in Sierra Leone kimberlites provide constraints on craton-specific melt-lithosphere interactions

Sierra Leone contains two Jurassic-aged diamondiferous kimberlite clusters, namely Koidu and Tongo-Tonguma (hereafter referred to as Tongo), consisting of eruptive pipes and NE-SW trending dikes. In this study, a combination of detailed petrography, and phlogopite, spinel, and olivine compositions in hypabyssal samples is presented to classify and constrain the petrogenesis of these kimberlites. Both the Koidu and Tongo rocks are predominantly macrocrystic and highly micaceous with phlogopite abundances, normalised to olivine-free, of 36–65 vol% in the groundmass. These phlogopite contents are comparable to those of some cratonic lamproites and significantly higher than any other kimberlites. Other groundmass minerals include spinel, perovskite, and apatite set in a base of carbonate and serpentine. Phlogopite and spinel have similar compositions in the Koidu and Tongo samples, displaying evolutionary trends consistent with those observed in worldwide kimberlites. Olivine macrocrysts and microcrysts display complex zoning with distinct cores, internal zones, and rims. The core compositions display a range in Mg# (81–95) and are interpreted to be derived from the disaggregation of lithospheric mantle xenoliths and proto-kimberlite related megacrysts. The Tongo olivine rims, interpreted to be primary magmatic crystallisation products, have similar compositions from various locations within the cluster whereas the Koidu samples display a range in rim compositions (Mg# 87–89) from different locations within the cluster. The average Koidu rim compositions display a strong positive correlation with the average core compositions, consistent with the trend formed by kimberlites worldwide and indicative of a strong control by melt-lithosphere interaction on melt compositions. Previously, it has been shown that the Mg# of olivine rim's negatively correlates with the abundance of groundmass phlogopite (± oxide minerals) in kimberlites. However, the Koidu and Tongo kimberlites are exceptionally phlogopite-rich given their olivine Mg#, fall outside of the worldwide kimberlite array and have olivine compositions and phlogopite abundances like some cratonic lamproites. This leads us to suggest that Koidu and Tongo represent a rare style of highly micaceous kimberlite magmatism, not previously reported in other cratonic regions, and are genetically linked to the assimilation of K 2 O-rich, metasomatic mantle lithologies. We further suggest that the K 2 O content, reflected by groundmass phlogopite abundances, of worldwide kimberlite and cratonic lamproite parent magmas ascending to the surface may be related to assimilation of craton-specific styles of metasomatic lithologies in the SCLM. • Unique highly micaceous kimberlites from Sierra Leone. • Olivine compositions constraining melt-SCLM interactions. • Craton-specific melt-SCLM assimilation and K2O enrichment.

KOH-assisted aqueous synthesis of ZIF-67 with high-yield and its derived cobalt selenide/carbon composites for high-performance Li-ion batteries

To solve the environmental pollution and low yield during the sythesis of zeolitic imidazolate frameworks (ZIFs) and their derived materials, a KOH-assisted aqueous strategy is proposed to synthesize cobalt zeolitic imidazolate framework (ZIF-67) polyhedrons, which are used as precursors to prepare cobalt selenide/carbon composites with different crystal phases (Co0.85Se, CoSe2). When evaluated as anode material for lithium ion batteries, Co0.85Se/C composites deliver a reversible capacity of 758.7 mA·h·g−1 with a capacity retention rate of 90.5% at 1.0 A·g−1 after 500 cycles, and the superior rate capability is 620 mA·h·g−1 at 2.0 A·g−1. The addition of KOH accelerates the production of ZIF-67 crystals by boosting deprotonation of dimethylimidazole, resulting in rapid growth and structures transition from two-dimensional to three-dimensional of ZIF-67 in aqueous solution, which greatly promotes the application of MOFs in the field of energy storage and conversion.

Optimizing the Mechanical Performance and Microstructure of Alkali-Activated Soda Residue-Slag Composite Cementing Materials by Various Curing Methods

Aiming to promote further the application of alkali-activated soda residue-ground granulated blast furnace slag (SR-GGBS) cementing materials, this study explored the optimal curing method for enhancing mechanical performance. The optimal curing method was determined based on the development of compressive strengths at different curing periods and microstructural examination by XRD, FTIR, SEM, and TG-DTG. The results show that the strength of cementing materials after room-temperature (RT) dry curing was the poorest, with the slow development of mechanical performance. The 7d and 28d compressive strengths were only 14.62 and 20.99 MPa, respectively. Compared with the values after RT dry curing, the samples’ 7d and 28d compressive strengths after RT water curing, standard curing, and RT sealed curing were enhanced by 16.35%/24.06%, 30.98%/23.77%, and 38.24%/37.97%, respectively. High-temperature (HT) curing can significantly improve the early strength of the prepared cementing materials. Curing at 60 °C for 12 h was the optimal HT curing method. Curing at 60 °C for 12 h enhanced the 3d strength by 100.84% compared with standard curing. This is because HT curing promoted the decomposition and aggregation of GGBS, and more C-A-S-H gel and crystal hydration products, including ettringite and calcium chloroaluminate hydrate, were produced and filled the inner pores, thereby enhancing both the overall compactness and mechanical performance. However, curing at too high temperatures for too long can reduce the material’s overall mechanical performance. After excess HT curing, many shrinkage cracks were produced in the sample. Different thermal expansion coefficients of different materials led to a decline in strength. The present study can provide a theoretical foundation for extensive engineering applications of alkali-activated SR-GGBS composite cementing materials.

Gel-mediated chemo-mechanical control of calcium carbonate crystal formation

The production of synthetic crystals with controlled shapes and properties is an enticing prospect, yet, the production of such materials is an ongoing challenge. Here, we present a strategy for chemo-mechanically directing the growth of crystals with non-equilibrium structures using a custom-designed double-diffusion cell. We combine chemical additives (e.g., Mg2+ ions) and mechanical confinement (e.g., hydrogel networks) to modulate the growth of calcium carbonate crystals. Specifically, the combination of Mg2+ ions with a strong agarose gel results in calcitic structures, at the gel-glass slide interface, with distinct fried egg-like morphologies and radial or Maltese-cross extinction patterns. In contrast, precipitation with only Mg2+ or agarose results in aragonite spherulites or squished calcite rhombohedra, respectively. Raman spectroscopy and energy dispersive spectroscopy of the “fried eggs” reveals that they are composed of Mg-calcite, which becomes less disordered over time, and the “egg whites” make this transition before the “yolks”. We propose that the “fried eggs” form due to a spherulitic growth process molded by the crystallization-induced delamination of the gel away from the glass slide at the gel-glass interface. In support of the importance of the gel-glass interface, the “fried eggs” do not form when the glass slide is treated with a hydrophobic silane, suppressing heterogeneous nucleation and weakening the interfacial adhesion between the gel and glass, making it easier for the gel to delaminate, thus reducing the confinement effect. As such, this work highlights the important chemo-mechanical role that gel environments can play in crystal formation.

Breakage Assessment of Lath-Like Crystals in a Novel Laboratory-Scale Agitated Filter Bed Dryer

Agitated filter bed dryer is often the equipment of choice in the pharmaceutical industry for the isolation of potent active pharmaceutical ingredients (API) from the mother liquor and subsequent drying through intermittent agitation. The use of an impeller to promote homogeneous drying could lead to undesirable size reduction of the crystal product due to shear deformation induced by the impeller blades during agitation, potentially causing off-specification product and further downstream processing issues. An evaluation of the breakage propensity of crystals during the initial development stage is therefore critical. A new versatile scale-down agitated filter bed dryer (AFBD) has been developed for this purpose. Carbamazepine dihydrate crystals that are prone to breakage have been used as model particles. The extent of particle breakage as a function of impeller rotational speed, size of clearance between the impeller and containing walls and base, and solvent content has been evaluated. A transition of breakage behaviour is observed, where carbamazepine dihydrate crystals undergo fragmentation first along the crystallographic plane [00l]. As the crystals become smaller and more equant, the breakage pattern switches to chipping. Unbound solvent content has a strong influence on the breakage, as particles break more readily at high solvent contents. The laboratory-scale instrument developed here provides a tool for comparative assessment of the propensity of particle attrition under agitated filter bed drying conditions.

Effects of various curing methods on the compressive strength and microstructure of blast furnace slag-fly ash-based cementitious material activated by alkaline solid wastes

The large-scale stacking of alkaline industrial solid wastes such as soda residue (SR) and calcium carbide residue (CCR) has caused serious environmental problems. Therefore, a new type of cementitious material was developed in our previous study by using SR-CCR synergistically activated blast furnace slag (BFS)-fly ash (FA), which abbreviated as SCBF. This paper further studied the effects of various curing methods on the compressive strength and microstructure of SCBF, which was expected to provide guidance for its application in the field of non-reinforced products such as baking-free brick. The results show that the optimal curing scheme was heat curing at 75 °C for 12 h. The optimal scheme significantly promoted an early hydration reaction and provided the 3d/28d strength values of 16.4/24.7 MPa, exceeding those of room-temperature (RT) sealed curing and water curing by 154/24.5 % and 264/31 %, respectively. Besides, the optimal scheme accelerated the formation of CSH gel, Hydrotalcite (6MgO·Al2O3·CO2·12H2O), Hydrocalumite (3CaO·Al2O3·CaCl2·10H2O), and other crystal products, as well as increased the consolidation rate of chlorine ion from 37.9 % (in RT sealed curing) to 64.3 %. These hydration products were evenly distributed, effectively filling the pores and reducing the macroporosity from 9.30 (in RT sealed curing) to 1.54 %, thus improving the early and later-age strength. Too high curing temperature (exceeding 75 ℃) or prolong heat curing period (exceeding 12 h) would cause microstructure deterioration, significantly increase the number of macropores and microcracks in the matrix, ultimately leading to strength retrogression.

人体生物矿化与病态结晶研究进展

<p indent="0mm">In the chemical industry, crystallization is an indispensable unit operation in the separation of the solid-liquid phase and a ubiquitous method to manufacture high-value crystal products. In nature, crystallization resulting in mineralization is a more general phenomenon in organisms. Modern crystallization technology is gradually expanding into the field of biomolecular engineering. However, biomineralization, in which organisms form tissues with biological functions by controlling the precipitation and crystallization of inorganic nanocrystals in organic matrices, is a dynamic, complex process that accompanies the organism throughout its life. But, when abnormal fluctuations occur in the body’s internal chemical environment, pathological mineralization occurs, resulting in the precipitation of inorganic or organic salt crystals which are aberrant crystallizations, a process known as pathological crystallization, causing disease and endangering human health, such as kidney stones, gall stones, malaria, and gout. Compared to the conventional crystallization from solution in chemical engineering which contains crystal nucleation, growth, and aggregation, biomineralization involves many microscopic and macroscopic processes such as ion/molecular assembly into nuclei, crystal-liquid interface mass transfer, and particle aggregation, which strongly couples with the physiological environment. The limitation of conventional crystallization hinders the advancement in understanding the mechanism of the ion/molecular crystallization process and the regulation of complex environments <italic>in vivo</italic>, resulting in the blindness of the screening and development of drugs for the treatment and prevention of such diseases. The study of biomineralization is a frontier research field and their discoveries in pathological crystallization are supposed to promote the development of clinical medicine. Based on the latest research in crystal engineering and crystallography, we take the common pathological mineralization-induced diseases (malaria, kidney stones, atherosclerosis, gall stones, gout) as examples, and select recent representative and significant findings from the perspective of understanding the mechanism of the crystallization process. The mechanisms of inorganic and organic crystal crystallization processes related to these diseases are reviewed, focusing on the molecular mechanisms of crystal nucleation, growth, agglomeration, and adhesion at diverse scales during different stages of the disease. The mechanisms of the crystallization inhibitors (molecules that inhibit the nucleation, growth, aggregation, or agglomeration process of pathological crystal) are also reviewed. The aim of the research on the crystallization and inhibition mechanisms is to build up guidelines for the screening and designing of effective inhibitors. Based on these findings, researchers have successfully designed many potent molecules that hold promise as a novel therapeutic modality. At the end of the review, the key research challenges and future directions in pathological mineralization are given. To meet the practical needs of clinical drug development, pathological mineralization researchers still face many challenges in understanding the mechanism of the crystallization process, screening drugs, establishing platforms and models, and building guidelines for medical advancement. Due to the complex environments <italic>in vivo</italic>, it is difficult to understand the mechanism of crystallization under the interaction between multiple ions/molecules and drugs, where molecular recognition plays important role in specific binding to crystal surface sites. The research on crystallization mechanism aims to screen potential pathological crystal inhibitors. Because considerable studies are based on <italic>in vitro</italic> experiments, more attention should be paid to the building platforms and models that can mimic human environments and use molecular design tools to selectively inhibit the crystallization process, which is believed to be the most potent strategy to find the specific drug for the biomineralization-induced disease. Finally, it is necessary to establish scientific and efficient guidelines for medicine development and provide effective therapeutic and preventive measures for biomineralization-induced diseases.

A Mechanistic Investigation of Electrochemical Ozone Production Using Nickel and Antimony Doped Tin Oxide in Non-Aqueous Electrolytes

Electrochemical water splitting to produce hydrogen has attracted great interest as an environmentally-friendly renewable fuel. While cathodic hydrogen evolution (HER) is a relatively fast process that produces a valuable chemical, the anodic oxygen evolution reaction (OER) is a slow process that adds little to no economic value to water splitting.1,2 Generating a high-performance oxidizer such as ozone instead of oxygen could make water splitting more economically feasible because of the added value of ozone. However, electrochemical ozone production (EOP) catalysts are typically hindered by low current efficiencies, poor selectivity, low stability, and high energy demands, which limit the industrial application of this reaction.3,4 Further improvements in catalyst performance could be achieved by better understanding the mechanism of ozone production. Nickel and antimony doped tin oxide (Ni/Sb-SnO2, NATO) is currently reported to have the highest EOP current efficiency at room temperature. However, the mechanism of EOP on NATO electrodes has not yet been established. A primary complication when studying the mechanism of EOP using NATO electrocatalysts in water is that oxygen atoms in the ozone molecule can originate from sources other than water, such as dissolved molecular oxygen or the electrocatalyst oxide lattice.1,5,6 In this work, lattice oxygen participation in EOP is investigated by replacing water with acetonitrile, a polar aprotic solvent without oxygen atoms. Our results show that ozone can be generated in acetonitrile in similar quantities as aqueous conditions.2 These quantities are inconsistent with a 6-electron process based on calculated current efficiencies. Furthermore, the addition of small quantities of water is shown to have a negative impact on ozone generation. The origin of this impact is thought to not be mechanistic in nature. Instead, we suggest that adding water to the mixture leads to the generation of hydroxide ions which act as ozone scavengers.To our knowledge, this is the first report of electrochemical ozone production in a non-aqueous solvent. Future work will more conclusively determine the origin of oxygen atoms using isotopic labeling. Furthermore, the ability of nonaqueous solvents to stabilize reactive oxygen species and impact selectivity will be investigated. Utilizing the knowledge gained by studying ozone generation in nonaqueous solvents, it might be possible to design a better EOP system which could enhance the applicability of this reaction.(1) Lees, C. M.; Lansing, J. L.; Morelly, S. L.; Lee, S. E.; Tang, M. H. Ni- and Sb-Doped SnO2 Electrocatalysts with High Current Efficiency for Ozone Production via Electrodeposited Nanostructures. J. Electrochem. Soc. 2018, 165 (16), E833. https://doi.org/10.1149/2.0051816jes.(2) James L. Lansinga±, Lingyan Zhaob, Tana Siboonruanga, N. Harsha Attanayakea, Angela B. Leob, Peter Fatourosb, So Min Parkc, Kenneth R. Grahamc, John A. Keithb, Maureen Tang*a. Gd-Ni-Sb-SnO2 Electrocatalysts for Active and Selective Ozone Production.(3) Christensen, P. A.; Attidekou, P. S.; Egdell, R. G.; Maneelok, S.; Manning, D. A. C.; Palgrave, R. Identification of the Mechanism of Electrocatalytic Ozone Generation on Ni/Sb-SnO 2. J. Phys. Chem. C 2017, 121 (2), 1188–1199. https://doi.org/10.1021/acs.jpcc.6b10521.(4) Wang, Y.-H.; Chen, Q.-Y. Anodic Materials for Electrocatalytic Ozone Generation. Int. J. Electrochem. 2013, 2013, 1–7. https://doi.org/10.1155/2013/128248.(5) Jiang, W.; Wang, S.; Liu, J.; Zheng, H.; Gu, Y.; Li, W.; Shi, H.; Li, S.; Zhong, X.; Wang, J. Lattice Oxygen of PbO 2 Induces Crystal Facet Dependent Electrochemical Ozone Production. J. Mater. Chem. A 2021, 9 (14), 9010–9017. https://doi.org/10.1039/D0TA12277G.(6) Feng, J.; Johnson, D. C.; Lowery, S. N.; Carey, J. J. Electrocatalysis of Anodic Oxygen‐Transfer Reactions: Evolution of Ozone. J. Electrochem. Soc. 1994, 141 (10), 2708–2711. https://doi.org/10.1149/1.2059184.