Production Of Crystals Research Articles

The Role of Urinary Modulators in the Development of Infectious Kidney Stones.

Introduction: The pathogenesis of infectious kidney stones is poorly understood. Bacteria have been implicated in promoting infectious stones via urease production; however, there is mounting evidence indicating the relationship is more complex. The aim of our study was to characterize suspected biotic and abiotic extrinsic factors that may modulate the formation of infectious stones. Materials and Methods: A high-throughput experimental model with Griffith's artificial urine was used to test a wide variety of urinary modulators and cytoplasmic enzymes present in crude cell-free extracts (CFEs) from bacterial strains to investigate how they impact struvite and calcium (Ca) phosphate crystal production. Crystal formation was evaluated with spectrophotometry and growth curve analysis. Light microscopy and scanning electron microscopy/X-ray diffraction was used for crystal structure and composition identification. Results: The acidic urinary modulators used in this study prevented crystal formation, whereas osteopontin had a significant inhibitory effect. Addition of CFEs from Proteus mirabilis 175A and 177A resulted in Ca phosphate and struvite crystals. Of interest, Klebsiella pneumoniae and Klebsiella oxytoca produced crystals including Ca phosphate and Ca oxalate, respectively. Pseudomonas aeruginosa had no urease production detected and produced Ca phosphate crystals. Discussion: Urinary modulators can have a wide variety of effects on infectious stone formation and the role of pH is important but does not guarantee robust crystal formation. Bacterial strains can produce Ca oxalate, Ca phosphate, and struvite stones with and without urease activity. Conclusion: Various urinary modulators appear to influence the process and are worthy of further evaluation as a potential therapeutic strategy to prevent infection-related urinary stone formation. Stones formed from urinary tract infections may be a result of multiple encoded metabolic pathways and discovering these would improve our understanding of the stone-bacterial relationship.

Efficient crystallization process of dodecanedioic acid by a pneumatically agitated crystallizer

Dodecanedioic acid (DC12) is mainly prepared via microbial synthesis in industrial production, however, the refined products have many drawbacks, such as low purity, poor crystal size distribution (CSD), and heavily agglomerated character, to name a few. Therefore, the refining process is a crucial step in DC12 preparation by microbial production. In this study, a novel pneumatically agitated crystallizer for DC12 refinery by gassing crystallization was developed. A batch cooling crystallization process was developed, providing the final crystal in 82.0% yield and purity increment to 99.20% at the end of crystallization process. Optimized conditions were determined as the initial supersaturation ratio of 300:3000 (g/mL) and gassing air flow rate of 4 L/min with solution preparation temperature of 85 °C. The crystal products with significantly better morphology characteristics than the starting crude feedstocks, including crystal uniformity and color brightness, were harvested. These obtained results indicated that the pneumatically agitated crystallizer-based crystallization process without any mechanical agitation was a robust and economically feasible technique. To our knowledge, this is also the first DC12 crystallization process with sole gassing agitation for unseeded batch cooling crystallization.

Crystallization of Coccolith Calcite at Different Life‐Cycle Phases Exhibits Distinct Degrees of Cellular Confinement

Coccolithophores are a group of unicellular marine algae that shape global geochemical cycles via the production of calcium carbonate crystals. Interestingly, different life‐cycle phases of the same coccolithophore species produce very different calcitic scales, called coccoliths. In the widely studied diploid phase, the crystals have anisotropic and complex morphologies, while haploid cells produce coccoliths consisting solely of calcite crystals with simple rhombohedral morphology. Understanding how these two life‐cycle phases control crystallization is a highly sought‐after goal, yet, haploid phase crystallization has rarely been studied, and the process by which they form is unknown. Herein, advanced electron microscopy is employed to elucidate the cellular architecture of the calcification process in haploid cells. The results show that in contrast to diploid‐phase calcification, the coccolith‐forming vesicle of haploid‐phase cells is voluminous. In this solution‐like environment, the crystals nucleate and grow asynchronously in a process that resembles calcite growth in bulk solution, leading to the simple morphologies of the crystals. The two distinct mineralization regimes of coccolithophore life‐cycle phases suggest that cellular architecture, and specifically confinement of the crystallization process, is a pivotal determinant of biomineral morphology and assembly.

Separation, purification, and crystallization of 1,5-pentanediamine hydrochloride from fermentation broth by cation resin.

1,5-Pentanediamine hydrochloride (PDAH) was an important raw material for the preparation of bio-based pentamethylene diisocyanate (PDI). PDI has shown excellent properties in the application of adhesives and thermosetting polyurethane. In this study, PDAH was recovered from 1,5-pentanediamine (PDA) fermentation broth using a cation exchange resin and purified by crystallization. D152 was selected as the most suitable resin for purifying PDAH. The effects of solution pH, initial temperature, concentration of PDA, and adsorption time were studied by the static adsorption method. The equilibrium adsorption data were well fitted to Langmiur, Freundlich, and Temkin-Pyzhev adsorption isotherms. The adsorption free energy, enthalpy, and entropy were calculated. The experimental data were well described by the pseudo first-order kinetics model. The dynamic experiment in the fixed bed column showed that under optimal conditions, the adsorption capacity reached 96.45mgg-1, and the recovery proportion of the effective section reached 80.16%. In addition, the crystallization of the PDAH solution obtained by elution proved that the crystal product quality of resin eluting solution was highest. Thus, our research will contribute to the industrial scale-up of the separation of PDAH.

New synthetic [LREE (LREE = La, Ce, Pr, Sm), Pb]-phosphate phases

Abstract Search for inexpensive and efficient methods of critical raw materials recovery is of great importance across the world due to growing demand for green technologies. Formation and detailed characterization of new Pb- and Light Rare Earth Elements (LREE)-containing phosphates, compared to already described Pb- or LREE-containing phosphates, was described in this work. These phases were precipitated at experimental conditions similar to these used in a newly proposed coprecipitation route for REE recovery from aqueous solutions. The formation of La, Ce, Pr and Sm phosphates from aqueous solutions proceeded differently in the presence of Pb than in its absence. No rhabdophane group minerals, (REE,Ca,Th)(PO4)·nH2O were formed, which were the product of crystallization in the absence of Pb, as evidenced by the PXRD analysis of the control LREE phosphates. Instead, a new, distinct phase was formed, which is neither a ‘phosphoschultenite’, PbHPO4, with La, Ce, Pr or Sm substitution nor a rhabdophane with Pb substitution. This showed that PbHPO4 structure did not accept isomorphic substitutions of LREE elements and rhabdophane structures are reluctant to accept Pb substitutions. At the same time, the formation of a hitherto unknown crystalline phase was found to be a mixed (LREE,Pb)-phosphate. A lower pH caused higher crystallinity of phases, as confirmed by SEM and PXRD. FTIR spectroscopy showed the hydrous nature of the obtained phases, which was additionally confirmed by thermal analysis. Decreasing pH of the reaction solution resulted in a higher crystalline water content. Moreover, La-bearing phases contained more chemically bound water than other phases. A combined EDS analysis and ICP-OES led to the chemical composition of new Pb phases with La, Ce, Pr and Sm that can be expressed as La2Pb3(PO4)4·3.5H2O, Ce2Pb3(PO4)4·3.3H2O, Pr2Pb3(PO4)4·3.1H2O and Sm2Pb3(PO4)4·3.3H2O, respectively. These results give a better understanding of potential novel recovery pathways of REE from phosphate mineral sources or wastes.

Corrosion behavior of Ni62Nb33Zr5 bulk metallic glasses after annealing and cryogenic treatments

The microstructural evolution and corrosion behavior of Ni62Nb33Zr5 bulk metallic glasses (BMGs) after annealing treatment (AT) at different crystallization temperatures and cryogenic treatment (CT) at −100 ℃ are experimentally investigated. Appropriate AT and CT can both improve the thermal stability and comprehensive corrosion resistance of as-cast BMG in 3.5 wt.% NaCl solution. The annealed and cryo-treated BMGs exhibit one more finite diffusion layer loop in the electrical equivalent circuit than the as-cast BMG, indicating the complexity of the corrosion behavior. Superior corrosion resistance is obtained in the cryo-treated BMG because the high degree of amorphization caused by CT reduces the structural inhomogeneity. Lower Cd and higher Rd values are obtained for the cryo-treated BMG, revealing the formation of a more stable passive film. Among the annealed BMGs, the fully crystallized sample exhibits a higher anti-corrosion performance owing to the existence of Nb-rich oxides in the crystallization products. The passive film is found to be composed mainly of Nb2O5 and ZrO2, demonstrating that Nb and Zr are conducive to reacting with oxygen to form a passive film. Based on the goal of maintaining a fully amorphous phase, appropriate CT causing structural homogeneity of the BMG is a simple and effective means to improve the comprehensive corrosion resistance.

Two‐Stage Hybrid Optimization Algorithm for Silicon Single Crystal Batch Scheduling Problem under Fuzzy Processing Time

Considering the widely existing processing time uncertainty in the real‐world production process, this paper constructs a fuzzy mathematical model for the silicon single crystal production batch scheduling problem to minimize the maximum completion time. In this paper, a two‐stage hybrid optimization algorithm (TSHOA) is proposed for solving the scheduling model. Firstly, the improved differential evolution algorithm (IDE) is used to solve the order quantity allocation problem of silicon single crystal with different sizes to obtain the quantity of silicon single crystal rods with different sizes produced by different types of single crystal furnaces. Secondly, the variable neighborhood search (VNS) algorithm is adopted to optimize the order quantity sequencingof batch production processes. Finally, simulations and comparisons demonstrate the feasibility of the model and the effectiveness of TSHOA.

Agronomic Performance and Productivity of Plant-Cane Sugarcane Under The Application of Various Dosage of Biofertilizer and Inorganic Fertilizer

Fertilization is one of the essential interventions in sugarcane cultivation. This research aimed to investigate solid biofertilizer (BF) effectiveness in various doses and combination with inorganic fertilizer (IF) on sugarcane agronomic performance and productivity so that the best dose combination of the two types of fertilizer on sugarcane can be observed. The field experiment was executed in the pattern-B sugarcane planting season/rainy season (October 2020) until the milled sugarcane harvest age at Afdeling Kaliputih, Kendenglembu, PT Perkebunan Nusantara XII, Banyuwangi, East Java, Indonesia. The experiment was performed with a randomized block design with three replicates. The treatment was a combination of doses of BF and IF, i.e., 1) without any fertilization; 2) 0% IF + 500 kg ha-1 BF; 3) 0% IF + 1,000 kg ha-1 BF; 4) 100% IF + 0 kg ha-1 BF; 5) 75% IF + 1,000 kg ha-1 BF; 6) 75% IF + 500 kg ha-1 BF; 7) 50% IF + 1,000 kg ha-1 BF; 8) 50% IF + 500 kg ha-1 BF; 9) 25% IF + 1,000 kg ha-1 BF; and 10) 25% IF + 500 kg ha-1 BF. Observed parameters were: 1) Seed germination (SG) percentage at 1 month after planting (MAP); 2) the number of stalks and tillers/clumps at 3 and 6 MAP; 3) Stalk height at 3, 6, and 11 MAP; 4) Stalk diameter at 6 and 11 MAP; 5) Sugarcane productivity, commercial cane sugar (CCS), and sugar crystal productivity at 12 MAP; and 6) Relative Agronomic Effectiveness (RAE). Results showed no significant difference among all the treatments in sugarcane SG percentage. Applying mixed BF and IF did not significantly affect the number of tiller/clumps, the number of stalks, stalk height, and stalk diameter of sugarcane at 6 and 11 MAP compared to the treatments of 100% IF. Among all the treatments, the highest sugarcane productivity, commercial cane sugar, and sugar crystal productivity were at the treatment 25% IF + 1,000 kg BF (135 ton ha-1), 50% IF + 500 kg BF (9.23%), and 75% IF + 500 kg BF (11.8 ton ha-1), respectively.

Получение серии кристаллов LiNbO3 : Er : Zn различного состава и исследование их оптических и пьезоэлектрических характеристик

New technological approaches to the production of lithium niobate single crystals of double doping LiNbO3 : Er : Zn have been developed. The studies of the optical quality and acoustic characteristics of LiNbO3 : Er : Zn single crystals have been carried out.

Carbon Nanotubes Decorated with Coordination Polymers for Fluorescence Detection of Heavy-Metal Ions and Nitroaromatic Chemicals.

Herein, [Nd(NO3)3(H2pzdca)] n (MA-1) was synthesized from a reaction of 2,3-pyrazinedicarboxylic acid [H2Pzdca] as an organic linker with salt of Nd(III) under solvothermal conditions. The detailed structural analysis for crystals was performed utilizing single-crystal X-ray diffraction (SCXRD). After that, the neodymium-based coordination polymer (MA-1) crystal was directly generated upon the surface of functionalized carbon nanotubes (F-CNTs) through bonds or affinity between F-CNTs and MA-1 via the solvothermal approach. Meanwhile, the existence of F-CNTs does not affect the production of MA-1 crystals. FT-IR, PXRD, SEM, TEM, and SCXRD studies were used to characterize the crystalline material, MA-1 and MA-1@CNT. To investigate the MA-1@CNT sensing properties, Pb(II), As(III), Cr(VI), and nitrobenzene (NB) were utilized as analytes. It is worth mentioning that MA-1@CNT developed as a susceptible sensor exhibits a fluorescence "turn-on" response for Pb(II) and As(III) ions, while a fluorescence "turn-off" response in the case of Cr(VI) and NB with significantly low limit of detection (LOD) values of 15.9 for Pb(II), 16.0 for As(III), 76.9 for Cr(VI), and 21.1 nM for NB, which are comparable with the lowest LOD available in the literature. Furthermore, MA-1@CNT could be conveniently regenerated and reused for at least three cycles by simply filtering and washing with water several times. The sensing mechanism is ascribed to the inner filter effect owing to the overlap between the emission and/or excitation bands of MA-1@CNT with the absorption bands of Cr(VI) and NB. In contrast, the fluorescence enhancement in the case of Pb(II) and As(III) could be correlated to the chelation-enhanced fluorescence phenomenon. These results indicate that MA-1@CNT is an ideal sensor for Pb(II), As(III), Cr(VI), and NB recognition.

Design of micro-jet plasma system: a novel nanoparticles manufacturing method in atmospheric pressure

Micro jet atmospheric (MPJ) plasma was first utilized to create nano-sized crystals. Nanosized particles may have advantageous characteristics such as better internal quality and dissolving rates of the product compared to traditional crystalline goods. A nebulizer system sprays an aerosol solution into plasma by use of a carrier gas in a cold plasma crystal (argon). The plasma warms and loads the droplets causing solvent and columbic fission evaporation, and then the nucleation and crystal formation start within the limited volume given by the tiny drops. This produces nano-sized crystals. MPJ was used to establish the operating parameters for producing nano-sized ZnSe material crystals using electron microscope transmitting and X-ray powder diffraction tests as well as sensitivity testing have been carried out. Sensitivity tests showed lower friction sensitivity for the nano-scale product, suggesting a better internal quality of the crystal product.

Origin of heavy rare earth elements in highly fractionated peraluminous granites

Rare earth elements (REEs + Y) play an important role in modern industry. Heavy REEs (HREEs) are particularly critical because of their relative scarcity in nature. Global HREE resources are predominantly present in granitoid weathering crusts in southern China. Although it is well known that REEs are generally enriched in alkaline rocks, in contrast, the parental granitoids in most Chinese HREE deposits are peraluminous. Here, we examined different REE mineral compositions, distribution patterns, and Nd isotope ratios of the granitoid complex in Zudong, South China, whose weathering crusts form the largest HREE deposits globally. The complex is composed of granodiorite, biotite-muscovite, and muscovite alkali-feldspar granites, whose REE patterns change from HREE depletion to enrichment relative to light REEs (LREEs) with increasing negative Eu anomalies. They are not fractional crystallization products from the same parental melts owing to the different zircon U-Pb ages (∼191, ∼169, and ∼154 Ma for granodiorite, biotite-muscovite, and muscovite granites, respectively). However, magmatic zircons from the three types of granitoids show consistent initial Hf isotope compositions [εHf(t) = 3.4 to 8.6], indicating they evolved from the same sources. The granodiorite contains primary LREE minerals with low εNd(t) values (−13.8 to −10.1), decoupled from high zircon Hf isotopes. This indicates a garnet-containing basement source resulted in Lu (HREE) remaining preferentially in the garnet phase, with Hf entering the melt. This contradicts the high HREE concentration recorded in the biotite-muscovite and muscovite granites, which contain abundant HREE minerals associated with muscovite, fluorite, and recrystallized quartz. The whole-rocks and their secondary REE minerals show variable and higher initial Nd isotope ratios [εNd(t) = −3.7 to 2.9 and −11.4 to −7.1 for biotite-muscovite and muscovite granites, respectively] than the early granodiorites and their primary REE minerals, indicating minimal 143Nd was derived from radioactive decay of 147Sm in the basement and wall rocks. This constrained the contribution of external REE-, volatile-rich liquids, which drove the segregation of highly evolved silicate melts from the magma chamber. This increased volatile saturation and fluid exsolution, which may have mobilized the HREEs and metasomatized the granites during their emplacement. Therefore, we infer that external fluid metasomatism appears to be crucial for the HREE enrichment in highly fractionated peraluminous granites.

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).