| 1. |
- Ibis, Fatma, et al.
(författare)
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Nucleation kinetics of calcium oxalate monohydrate as a function of pH, magnesium, and osteopontin concentration quantified with droplet microfluidics
- 2021
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 15:6
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Tidskriftsartikel (refereegranskat)abstract
- A droplet-based microfluidic platform is presented to study the nucleation kinetics of calcium oxalate monohydrate (COM), the most common constituent of kidney stones, while carefully monitoring the pseudo-polymorphic transitions. The precipitation kinetics of COM is studied as a function of supersaturation and pH as well as in the presence of inhibitors of stone formation, magnesium ions (Mg2+), and osteopontin (OPN). We rationalize the trends observed in the measured nucleation rates leveraging a solution chemistry model validated using isothermal solubility measurements. In equimolar calcium and oxalate ion concentrations with different buffer solutions, dramatically slower kinetics is observed at pH 6.0 compared to pHs 3.6 and 8.6. The addition of both Mg2+ and OPN to the solution slows down kinetics appreciably. Interestingly, complete nucleation inhibition is observed at significantly lower OPN, namely, 3.2 x 10(-8) M, than Mg2+ concentrations, 0.875 x 10(-4) M. The observed inhibition effect of OPN emphasizes the often-overlooked role of macromolecules on COM nucleation due to their low concentration presence in urine. Moreover, analysis of growth rates calculated from observed lag times suggests that inhibition in the presence of Mg2+ cannot be explained solely on altered supersaturation. The presented study highlights the potential of microfluidics in overcoming a major challenge in nephrolithiasis research, the overwhelming physiochemical complexity of urine.
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| 2. |
- Ibis, Fatma, et al.
(författare)
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Role of Hyaluronic Acid on the Nucleation Kinetics of Calcium Oxalate Hydrates in Artificial Urine Quantified with Droplet Microfluidics
- 2022
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 22:6, s. 3834-3844
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Tidskriftsartikel (refereegranskat)abstract
- The increasing prevalence of urolithiasis in industrialized societies triggered considerable interest in how various species found in urine regulate the nucleation and growth of common kidney stone constituents such as calcium oxalate (CaOx). Yet, the role macromolecules play in kidney stone formation is often overlooked due to their low concentration in urine. In this study, we investigate the nucleation kinetics of CaOx in artificial urine with droplet-based microfluidic induction time measurements at varying concentrations of oxalate and hyaluronic acid (HA), a polysaccharide commonly found in urine. The formation of two pseudo-polymorphic forms of calcium oxalate crystals, calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), are carefully monitored using polarized light microscopy in induction time experiments. COM and COD nucleated concomitantly in artificial urine yet with distinct kinetics. Our results indicate that higher oxalate concentrations favor the formation of COD, the metastable form, over COM, the most stable form. Moreover, COD is also the fastest nucleating form in droplets under studied conditions. Furthermore, increasing the concentration of HA at fixed calcium and oxalate concentrations favored the nucleation of COM. We observed that in droplets where COM nucleated first, COD was not formed within the experimental time scale. However, in the droplets where COD appeared first, COM crystals were also observed later. We hope our findings shed light on the role macromolecules such as HA plays in dictating the pseudo-polymorphic form of CaOx and guide next generation treatments.
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| 3. |
- Korede, Vikram, et al.
(författare)
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Design and Validation of a Droplet-based Microfluidic System To Study Non-Photochemical Laser-Induced Nucleation of Potassium Chloride Solutions
- 2023
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 23:8, s. 6067-6080
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Tidskriftsartikel (refereegranskat)abstract
- Non-photochemicallaser-induced nucleation (NPLIN) hasemergedas a promising primary nucleation control technique offering spatiotemporalcontrol over crystallization with potential for polymorph control.So far, NPLIN was mostly investigated in milliliter vials, throughlaborious manual counting of the crystallized vials by visual inspection.Microfluidics represents an alternative to acquiring automated andstatistically reliable data. Thus we designed a droplet-based microfluidicplatform capable of identifying the droplets with crystals emergingupon Nd:YAG laser irradiation using the deep learning method. In ourexperiments, we used supersaturated solutions of KCl in water, andthe effect of laser intensity, wavelength (1064, 532, and 355 nm),solution supersaturation (S), solution filtration,and intentional doping with nanoparticles on the nucleation probabilityis quantified and compared to control cooling crystallization experiments.Ability of dielectric polarization and the nanoparticle heating mechanismsproposed for NPLIN to explain the acquired results is tested. Solutionswith lower supersaturation (S = 1.05) exhibit significantlyhigher NPLIN probabilities than those in the control experiments forall laser wavelengths above a threshold intensity (50 MW/cm(2)). At higher supersaturation studied (S = 1.10),irradiation was already effective at lower laser intensities (10 MW/cm(2)). No significant wavelength effect was observed besides irradiationwith 355 nm light at higher laser intensities (& GE;50 MW/cm(2)). Solution filtration and intentional doping experimentsshowed that nanoimpurities might play a significant role in explainingNPLIN phenomena. Thearticle describes a droplet-based microfluidic setupto study NPLIN with the droplets containing crystals identified usingthe deep-learning method. Experimental parameters such as solutionsupersaturation, laser wavelength, laser intensity, solution filtration,and intentional doping of nanoparticles are studied using supersaturatedaqueous KCl solutions to quantify its influence on nucleation kineticsand draw parallels to the proposed underlying NPLIN mechanisms inthe literature.
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| 4. |
- Michelin, Simone, et al.
(författare)
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Kinetics of ultrasound-assisted enzymatic biodiesel production from Macauba coconut oil
- 2015
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Ingår i: Renewable energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0960-1481 .- 1879-0682. ; 76, s. 388-393
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Tidskriftsartikel (refereegranskat)abstract
- This work reports the production of fatty acid ethyl esters (FAEE) by means of Macauba (Acrocomia aculeata) coconut oil (MCO) solvent-free enzymatic transesterification reactions using a commercial immobilized lipase (Novozym 435) under the influence of ultrasound irradiation. An experimental design was used to evaluate the effects of temperature (40-70 degrees C), enzyme (5-20 wt%) concentration, oil to ethanol molar ratio (1:3-1:10) and output irradiation power (40-70% of the maximum supply value) on the reaction yield. Besides, a kinetic study varying the enzyme concentration was also carried out. Results show that ultrasound-assisted lipase-catalyzed transesterification of MCO with ethanol in solvent-free system might be a potential alternative route to conventional alkali-catalyzed and/or traditional enzymatic methods, as reaction yields around 70 wt% were obtained at mild irradiation power supply (similar to 132 W), and temperature (65 degrees C) in a short reaction time, 30 min. Reutilization of enzyme showed that it may be advantageously employed up to 5 reuse cycles. (C) 2014 Elsevier Ltd. All rights reserved.
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| 5. |
- Korede, Vikram, et al.
(författare)
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Effect of Laser-Exposed Volume and Irradiation Position on Nonphotochemical Laser-Induced Nucleation of Potassium Chloride Solutions
- 2023
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 23:11, s. 8163-8172
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we study the influences of the laser-exposed volume and the irradiation position on the nonphotochemical laser-induced nucleation (NPLIN) of supersaturated potassium chloride solutions in water. The effect of the exposed volume on the NPLIN probability was studied by exposing distinct milliliter-scale volumes of aqueous potassium chloride solutions stored in vials at two different supersaturations (1.034 and 1.050) and laser intensities (10 and 23 MW/cm2). Higher NPLIN probabilities were observed with increasing laser-exposed volume as well as with increasing supersaturation and laser intensity. The measured NPLIN probabilities at different exposed volumes are questioned in the context of the dielectric polarization mechanism and classical nucleation theory. No significant change in the NPLIN probability was observed when samples were irradiated at the bottom, top, or middle of the vial. However, a significant increase in the nucleation probability was observed upon irradiation through the solution meniscus. We discuss these results in terms of mechanisms proposed for NPLIN.
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| 6. |
- Penha, Frederico M., et al.
(författare)
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In Situ Observation of Epitaxial Growth during Evaporative Simultaneous Crystallization from Aqueous Electrolytes in Droplets
- 2021
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Ingår i: Crystals. - : MDPI AG. - 2073-4352. ; 11:9, s. 1122-1122
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Tidskriftsartikel (refereegranskat)abstract
- In this study, crystallization phenomena were investigated by real-time in situ observation of seeded droplets under evaporation using a self-developed hot-stage platform. Ternary solutions at eutonic conditions at 25 °C were investigated for the following systems: NaCl–KCl–H2O, NaCl–CaSO4–H2O, and NaCl–Na2SO4–H2O. Evidence of epitaxial growth was found for aqueous NaCl–KCl and aqueous NaCl–Na2SO4. Sodium chloride nucleated and grew epitaxially upon the other substrates in a larger proportion compared with the inverse. This observation could be related to the higher solubility, and consequently higher residual supersaturation of NaCl regarding the other components. Hopper-like NaCl crystals developed in almost all systems. The results may help devise strategies to control particle morphologies and purity in industrial crystallization from complex systems.
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| 7. |
- Penha, Frederico Marques, et al.
(författare)
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Strategies to control product characteristics in simultaneous crystallization of NaCl and KCl from aqueous solution : seeding with NaCl and KCl
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry. - 1466-8033. ; 22:44, s. 7590-7600
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Tidskriftsartikel (refereegranskat)abstract
- In this work we developed an approach for the simultaneous crystallization of NaCl and KCl from their aqueous solution by concomitantly seeding both salts. Experiments were designed based on the ternary system phase diagram. The mother liquor concentration was chosen near the eutonic condition at its boiling temperature. The seeds for each compound had different sizes but the amounts were calculated to provide nearly equal surface areas for each material. Elementary phenomena were assessed and the chemical composition in different particle size ranges within the products was analysed. Despite the presence of seeds from each component in the suspension under crystallization, the formation of mixed composition polycrystalline particles was observed. A seeding protocol involving much larger KCl than NaCl seeds resulted in an easily separable product with two distinct populations. In general, segregation of the salts through the size ranges followed the trend induced by seeding, highlighting the possibility of retrieving relatively pure solid fractions of each salt.
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| 8. |
- Arend, Giordana Demaman, et al.
(författare)
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Is nanofiltration an efficient technology to recover and stabilize phenolic compounds from guava (Psidium guajava) leaves extract?
- 2022
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Ingår i: Food Bioscience. - : Elsevier BV. - 2212-4292 .- 2212-4306. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- Guava leaves (Psidium guajava) are popularly known due to their effects antidiabetic, antihypertensive, anti-inflammatory, antidiarrheal, and functional properties. Processes for the concentration of these extracts are necessary since their pharmacological effects are dose-dependent. In this work, guava leaves aqueous extract (GE) concentration was carried out in nanofiltration (NF) equipment. Process performance was evaluated in terms of permeate flux, flux decline modeling, and extract quality (compounds characterization, total phenolic content and antioxidant activity). NF allowed an increase in phenolic compounds next to 20-times, retention coefficients of total phenolic compounds (99%) and enhanced antioxidant capacity (an increase of 4 and 9-fold for ABTS and DPPH, respectively) compared to the initial GE. Forty-two phenolic compounds were identified, being catechin (594.56 mg mL-1) and vescalagin (295.39 mg mL-1) the main compounds. All phenolics pre-sented a significant increase (p < 0.05) after the concentration suggesting that NF is efficient for the recovery and concentration of bioactive compounds and poses as an alternative to obtain functional products and improve added value in agro-industrial residues.
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| 9. |
- dos Santos Garruti, Deborah, et al.
(författare)
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Volatile profile and sensory quality of new varieties of Capsicum chinense pepper
- 2013
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Ingår i: Ciência e tecnologia de alimentos. - Campinas : Sociedade Brasileira de Ciencia e Tecnologia de Alimentos. - 1678-457X. ; 33, s. 102-108
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to compare the sensory quality and the volatile compound profile of new varieties of Capsicum chinense pepper (CNPH 4080 a strain of ‘Cumari-do-Pará’ and BRS Seriema) with a known commercial variety (Biquinho). Volatiles were isolated from the headspace of fresh fruit by SPME and identified by GC-MS. Pickled peppers were produced for sensory evaluation. Aroma descriptors were evaluated by Check-All-That-Apply (CATA) method, and the frequency data were submitted to Correspondence Analysis. Flavor acceptance was assessed by hedonic scale and analyzed by ANOVA. BRS Seriema showed the richest volatile profile, with 55 identified compounds, and up to 40% were compounds with sweet aroma notes. CNPH 4080 showed similar volatile profile to that of Biquinho pepper, but it had higher amounts of pepper-like and green-note compounds. The samples did not differ in terms of flavor acceptance, but they showed differences in aroma quality confirming the differences found in the volatile profiles. The C. chinense varieties developed by Embrapa proved to be more aromatic than Biquinho variety, and were well accepted by the judges.
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| 10. |
- Korede, Vikram, et al.
(författare)
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A Review of Laser-Induced Crystallization from Solution
- 2023
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 23:5, s. 3873-3916
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Forskningsöversikt (refereegranskat)abstract
- Crystallization abounds in nature and industrial practice. A plethora of indispensable products ranging from agrochemicals and pharmaceuticals to battery materials are produced in crystalline form in industrial practice. Yet, our control over the crystallization process across scales, from molecular to macroscopic, is far from complete. This bottleneck not only hinders our ability to engineer the properties of crystalline products essential for maintaining our quality of life but also hampers progress toward a sustainable circular economy in resource recovery. In recent years, approaches leveraging light fields have emerged as promising alternatives to manipulate crystallization. In this review article, we classify laser-induced crystallization approaches where light-material interactions are utilized to influence crystallization phenomena according to proposed underlying mechanisms and experimental setups. We discuss nonphotochemical laser-induced nucleation, high-intensity laser-induced nucleation, laser trapping-induced crystallization, and indirect methods in detail. Throughout the review, we highlight connections among these separately evolving subfields to encourage the interdisciplinary exchange of ideas.
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| 11. |
- Penha, Frederico Marques, et al.
(författare)
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Simultaneous Crystallization of NaCl and KCl from Aqueous Solution : Elementary Phenomena and Product Characterization
- 2018
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 18:3, s. 1645-1656
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Tidskriftsartikel (refereegranskat)abstract
- The main elementary processes were identified during simultaneous crystallization of NaCl and KCl from aqueous solutions by the batchwise evaporative method using NaCl seeds. In the early stages of the batch operation, when only NaCl crystallizes, the main elementary processes are molecular crystal growth, agglomeration, and secondary nucleation. When the eutonic condition is exceeded, a KCl primary nucleation event takes place in solution. Subsequently, part of the resulting KCl particles agglomerate with the NaCl particles. Besides, epitaxial growth of KCI upon NaCl crystals takes place. Consequently, the product is comprised of mixed composition polycrystalline particles and single crystals of each salt. The elementary phenomena just described were sensitive to crystallization conditions such as evaporation rate, seed size, and seed content, suggesting the possibility of controlling the morphological features of the particulate product as well as the chemical composition of its size fractions. Such knowledge is important in the context of wastewater treatment, where the particulate product should be suitable either for disposal as a residue or for further processing in easily separable size fractions for exploitation of valuable components.
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| 12. |
- Penha, Frederico Marques, et al.
(författare)
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Strategies To Control Product Characteristics in Simultaneous Crystallization of NaCl and KCl from Aqueous Solution : Seeding with KCl
- 2019
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 19:2, s. 1257-1267
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Tidskriftsartikel (refereegranskat)abstract
- To meet contemporary industry needs, saline wastewater treatment with zero liquid discharge goals is gaining increasing attention. In this context, evaporative crystallization has been applied to simultaneously remove all dissolved compounds as a solid residue. By conducting simultaneous crystallization in a way that the components crystallize as single particles, their downstream separation as products is made simple, so that no solid waste is generated. We have recently identified the main phenomena that control particle morphology for batchwise simultaneous crystallization in the NaCl-KCl-H2O model system seeded with NaCl. In this work, a process strategy is proposed, wherein crystallization elementary phenomena are tuned by seeding with KCl particles. Formation of multicomponent particles was inhibited with a small seed surface area, because the epitaxial growth of NaCl upon the KCl seeds was hampered. By a proper choice of seeding policy, the product may be classified into large particles rich in KCl (purity higher than 90 wt %) and smaller particles rich in NaCl (similar to 75 wt %). Secondary nucleation and epitaxial growth of NaCl on KCl were the main hindrances to the formation of pure populations of each compound.
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| 13. |
- Rezzadori, Katia, et al.
(författare)
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Impact of Organic Solvents on Physicochemical Properties of Nanofiltration and Reverse-Osmosis Membranes
- 2019
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Ingår i: Chemical Engineering & Technology. - : WILEY-V C H VERLAG GMBH. - 0930-7516 .- 1521-4125. ; 42:12, SI, s. 2700-2708
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Tidskriftsartikel (refereegranskat)abstract
- Polymeric membranes subjected to the permeation of n-hexane were characterized and the influence of pretreatment with ethanol on the properties of the membranes was studied to assess membrane performance and stability. The results suggest that the selectivity of the membrane depends not only on the pore size, but also to a great extent on the interaction between solvent and polymer. An increase in membrane roughness and contact angle was observed for all membranes after pretreatment with ethanol and n-hexane permeation. Moreover, the surface free energy decreased after solvents exposure, indicating an increase in membrane surface hydrophobicity and polymer swelling. The studied membranes show feasibility of use for the recovery of solvents, if suitable process parameters are selected.
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