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  • 1.
    Agarwal, Parminder
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Effect of polymeric additives on calcium carbonate crystallization as monitored by nephelometry2004Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 4, nr 3, s. 479-483Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of polymaleimide polymers on calcium carbonate crystallization was studied using nephelometry. Induction time and percent growth inhibition were determined for polymeric additives from the nephelometric data. The polymaleimide synthesized by KOH-initiated polymerization exhibited the greatest growth inhibition and longest nucleation time among the polymers investigated. Raman spectroscopy was used to determine the calcium carbonate polymorph formed in the presence of these polymeric additives.

  • 2.
    Agarwal, Parminder
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    In situ monitoring of calcium carbonate polymorphs during batch crystallization in the presence of polymeric additives using Raman spectroscopy2003Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 3, nr 6, s. 941-946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polycarboxylic acids are well-known to affect calcium carbonate crystallization. Agarwal et al. (Ind. Eng. Chem. Res. 2003, in press) reported previously the synthesis of polymaleimide by a variety of techniques and initiators. In the present work, the effect of these polymers on calcium carbonate crystallization was studied by a variety of techniques. Crystallization experiments were carried out in a 1-L LABMAX automated batch reactor, and the concentration of calcium in solution was determined in real time. Raman spectroscopy was used to determine the relative amount of various calcium carbonate polymorphs as the crystallization occurred. However, Raman spectroscopy is a scattering technique, which may make it surface selective, and therefore results from solids may not be representative of bulk of sample. X-ray diffraction (XRD) was used to compare the results obtained by Raman spectroscopy. Peak intensity ratios were used for both Raman spectroscopy and XRD for calibration and measurement purposes. The results obtained by these two techniques for final percent vaterite for calcium carbonate crystallization in the presence of polymeric additives were in agreement within 2%. Therefore, use of Raman spectroscopy for in situ measurement of polymorph composition during calcium carbonate crystallization appears accurate. Scanning electron microscopy (SEM) data were useful in understanding the crystal morphology and to determine crystal size.

  • 3. Alhalaweh, Amjad
    et al.
    Ali, Hassan
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Effects of polymer and surfactant on the dissolution and transformation profiles of cocrystals in aqueous media2014Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, nr 2, s. 643-648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Capturing solubility advantages of cocrystals is of great interest, and thus to understand the mechanism by which different excipients could maintain the supersaturation generated by cocrystals at the course of absorption in aqueous media is essential. To achieve this aim, the impact of different excipients on dissolution behavior of indomethacin-saccharin (IND-SAC) were monitored by measuring the concentrations of cocrystal components in the absence and presence of various concentration of excipients by HPLC, and solid phases were analyzed by differential scanning calorimetry after each experiment and the potential of Raman spectroscopy for monitoring phase transformations in situ was tested. No dissolution advantage was offered by cocrystals in the absence of any solution additive. The polymer and surfactant used in the study increased the solubility of IND but not SAC. This differential solubilization effect is believed to have stabilized the cocrystals for a relevant period for the absorption to take place. This could be attributed to either decreased gap between supersaturation and saturation of the drug or drug interaction with the additives. Understanding the effects of excipients type and concentration on the transformation profile is vital for designing enabling formulations for cocrystals. The eutectic constant may be useful in selecting excipients for stabilizing cocrystals.

  • 4.
    Alhalaweh, Amjad
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    George, Sumod
    Boström, Dan
    Department of Energy Technology and Thermal Process Chemistry, Umea University.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    1:1 and 2:1 urea-succinic acid cocrystals: structural diversity, solution chemistry, and thermodynamic stability2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 11, s. 4847-4855Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to study the crystal structures of 1:1 and 2:1 urea-succinic acid (U-SA) cocrystals and to investigate the role of solution chemistry in the formation and stability of different stoichiometric cocrystals. The structural diversity of other urea-dicarboxylic acid cocrystals is also discussed. The 1:1 U-SA cocrystal was stabilized by an acid-amide heterosynthon while acid-amide heterosynthons and amide-amide homosynthons stabilized the 2:1 cocrystals. The hydrogen bonding motifs in 1:1 and 2:1 U-SA cocrystals were consistent with other urea-dicarboxylic acid systems with similar stoichiometries. The 1:1 cocrystals were transformed to 2:1 cocrystals upon slurrying in various solvents at 25 °C. The phase solubility diagram was used to define the stability regions of different solid phases in 2-propanol at 25 °C. While no phase stability region for 1:1 cocrystal could be found, the stable regions for the 2:1 cocrystals and their pure components were defined by eutectic points. The solubility of the 2:1 cocrystals was dependent on the concentration of the ligand in the solution and explained by the solubility product and 1:1 solution complexation. The mathematical models predicting the solubility of the 2:1 cocrystals were evaluated and found to fit the experimental data

  • 5.
    Alhalaweh, Amjad
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Sokolowski, Anders
    Department of Pharmaceutical Chemistry, Uppsala University.
    Rodriguez-Hornedo, Nair
    Department of Pharmaceutical Sciences, University of Michigan.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Solubility behavior and solution chemistry of indomethacin cocrystals in organic solvents2011Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 11, nr 9, s. 3923-3929Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of this study was to investigate the solubility behavior and solution chemistry of indomethacin-saccharin (IND-SAC) cocrystals in organic media. We also evaluated previously proposed models of cocrystal solubility in organic solvents. In addition, the solubility behavior of IND-SAC cocrystals was compared with that of indomethacin-nicotinamide (IND-NIC) cocrystals using the eutectic constant approach. Phase solubility diagrams of IND-SAC cocrystals in various solvents were generated and the transition concentrations, at which drug and cocrystals are in equilibrium with the solvents, were determined. The solubility of IND-SAC cocrystals was explained by the solubility product and solution complexation. The tested models were found to fit the experimental data and to adequately explain the solubility behavior of the cocrystals. The solution complexation of IND and SAC is negligible in ethyl acetate and low in methanol and ethanol. The IND-NIC cocrystals were more soluble than the IND-SAC cocrystals in all the solvents studied. The eutectic constants predicted both the solubility and the stability of the cocrystals. Understanding the solubility behavior and solution chemistry of cocrystals has important implications for the screening, scale-up, and formulation development of this solid form. Further, the determination of eutectic constants is a simple and resource sparing means of obtaining key information on cocrystal stability and solution behavior

  • 6.
    Alhalaweh, Amjad
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Formation of cocrystals from stoichiometric solutions of incongruently saturating systems by spray drying2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 8, s. 3302-3305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spray drying is a well established technique for material processing and scale-up. This study investigated the formation of pharmaceutical cocrystals by spray drying. The cocrystal formation mechanisms in spray-drying and solution methods, based on triangular phase diagrams, are discussed. The solvent evaporation of stoichiometric solutions of incongruently saturating cocrystals resulted in a mixture of phases, as dictated by the thermodynamic phase diagram. In contrast, spray drying of similar solutions of incongruently saturating systems generated pure cocrystals. It is thus suggested that the formation of cocrystals by spray drying could be kinetically controlled and/or mediated by the glassy state of the material.

  • 7.
    Basavoju, Srinivas
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Pharmaceutical cocrystal and salts of norfloxacin2006Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 6, nr 12, s. 2699-2708Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate the structural and pharmaceutical properties of norfloxacin (a poorly soluble antibacterial drug), its cocrystal, and salts. Norfloxacin in the anhydrous form (form A, 1) was crystallized. It was cocrystallized with isonicotinamide (2), and organic salts were prepared with succinic acid, malonic acid, and maleic acid (3-5, respectively). These phases were characterized by differential scanning calorimetry (DSC), infrared (IR) and Raman spectroscopy, and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction data were obtained, and crystal structures were solved. The apparent solubility of these phases was determined. Robust O-H⋯O, O-H⋯O-, O-H⋯N, N-H⋯O, N+-H-O -, and N-H⋯N interactions were present in all these structures. Quinolone moieties in these structures stack with π⋯π interactions and form channels to include CHCl3 or H2O. Herein we report a new cocrystal and salts of norfloxacin with improved aqueous solubility

  • 8.
    Berglund, Kris
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Falcon, Javier A
    Departments of Chemistry, Chemical Engineering & Materials Science and Agricultural Engineering, Michigan State University, East Lansing, Michigan.
    In situ monitoring of antisolvent addition crystallization with principal components analysis of Raman spectra2004Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 4, nr 3, s. 457-463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of progesterone. Raman spectral features of the solute and the antisolvent were subjected to principal components analysis (PCA) to attempt to obtain information that is not readily apparent from the raw spectral data. For the system utilized, PCA was able to distinguish spectral features from the solute in solution, the solute crystals, and the antisolvent. Furthermore, PCA was capable of detecting subtle changes in the spectral data (as the addition of antisolvent progressed) that could be used as a warning for the onset of crystallization. The current study demonstrates the advantages that can be gained by combining PCA with Raman spectroscopy for monitoring crystallizations in situ.

  • 9.
    Bradley, Jonathan P.
    et al.
    Department of Physics, Warwick University, Coventry.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Brown, Steven P.
    Department of Physics, Warwick University, Coventry.
    Probing intermolecular crystal packing in gamma-indomethacin by high-resolution 1H solid-state NMR spectroscopy2011Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 11, nr 8, s. 3463-3471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An NMR crystallography approach that combines experimental solid-state magic-angle-spinning (MAS) NMR with calculation is applied to the gamma polymorph of the pharmaceutical molecule, indomethacin. First-principles calculations (GIPAW) for the full crystal structure and an isolated molecule show changes in the (1)H chemical shift for specific aliphatic and aromatic protons of over -1 ppm that are due to intermolecular CH-pi interactions. For the OH proton, (1)H double-quantum (DQ) CRAMPS (combined rotation and multiple-pulse spectroscopy) spectra reveal intermolecular H-H proximities to the OH proton of the carboxylic acid dimer as well as to specific aromatic CH protons. The enhanced resolution in (1)H DQ-(13)C spectra, recorded at 850 MHz, enables separate (1)H DQ build-up curves (as a function of the DQ recoupling time) to be extracted for the aromatic CH protons. Supported by eight-spin density-matrix simulations, it is shown how the relative maximum intensities and rates of build-up provide quantitative insight into intramolecular and intermolecular H-H proximities that characterize the crystal packing

  • 10.
    Chattoraj, Sayantan
    et al.
    Pharmaceutical Materials Science & Engineering Laboratory, Department of Pharmaceutics, University of Minnesota.
    Shi, Limin
    Pharmaceutical Materials Science & Engineering Laboratory, Department of Pharmaceutics, University of Minnesota.
    Chen, Miles
    Pharmaceutical Materials Science & Engineering Laboratory, Department of Pharmaceutics, University of Minnesota.
    Alhalaweh, Amjad
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Sun, Changquan Calvin
    Pharmaceutical Materials Science & Engineering Laboratory, Department of Pharmaceutics, University of Minnesota.
    Origin of Deteriorated Crystal Plasticity and Compaction Properties of a 1:1 Cocrystal between Piroxicam and Saccharin2014Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, nr 8, s. 3864-3874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 1:1 cocrystal between piroxicam and saccharin exhibits significantly deteriorated powder compaction properties compared to both coformers. The molecular origin of this effect is revealed by a systematic investigation of crystal mechanical properties, probed with nanoindentation, and crystal structure analysis. The order of bulk powder tabletability of the three materials is identical to that of single crystal plasticity (saccharin > piroxicam > cocrystal). The lowest plasticity of the cocrystal is confirmed by its highest crystal hardness and the highest yield strength. The low plasticity of the cocrystal is attributed to structural packing features that discourage plastic deformation. This work demonstrates that cocrystallization, even though it may be useful to improve pharmaceutically relevant properties, must be carefully evaluated to avoid unexpected problems in formulation and drug product manufacturing due to compromised mechanical properties.

  • 11.
    Falcon, Javier A.
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Monitoring of antisolvent addition crystallization with Raman spectroscopy2003Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 3, nr 6, s. 947-952Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of cortisone acetate. Raman spectral features of the solvent, the antisolvent, and the solute were monitored to measure the relative concentration of the components. Different rates of antisolvent addition were monitored and the resulting solid-state form was characterized using Raman spectroscopy and DSC. Raman spectroscopy was used to monitor dehydration during storage of the product crystals. The current study demonstrates the advantages of using Raman spectroscopy to monitor the solution phase during crystallization and simultaneously monitoring the solid-state form.

  • 12.
    Feng, Lili
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    ATR-FTIR for determining optimal cooling curves for batch crystallization of succinic acid2002Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, nr 5, s. 449-452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The temperature profile applied during batch cooling crystallization affects the supersaturation level, which in turn affects the crystal size distribution. It is possible, in principle, to calculate the optimal cooling profile; however, the nucleation and growth kinetics are rarely known to the degree of accuracy necessary for this calculation. The current study demonstrates an alternative approach to determination of the optimal cooling profile without any prior knowledge of kinetic data or subsequent modeling. An attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometer was used to monitor the supersaturation level during batch cooling crystallization. The ATR-FTIR was interfaced to a LABMAX automatic reactor system that was used in a feedback mode to control the cooling rate so that the supersaturation level remained close to the solubility throughout the cooling process. The resulting temperature profile corresponds to the optimal operating conditions for the maximum in the mean crystal size.

  • 13.
    Fornasari, Luca
    et al.
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    Mazzaro, Raffaello
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. CNR-IMM, Area della Ricerca di Bologna, Bologna, Italy.
    Boanini, Elisa
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    d’Agostino, Simone
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    Bergamini, Giacomo
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    Grepioni, Fabrizia
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    Braga, Dario
    Dipartimento di Chimica “Giacomo Ciamician”, Università; di Bologna, Bologna, Italy.
    Self-Assembly and Exfoliation of a Molecular Solid Based on Cooperative B-N and Hydrogen Bonds2018Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 18, nr 12, s. 7259-7263Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein we report that 4-pyridinylboronic acid (1) in the solid state self-assembles into tetrameric macrocycles via B-N bond formation. The tetramers are linked via O-H···O bonds resulting in a material that can be exfoliated via sonication to give thinner sheets as we demonstrate via Fourier transform infrared spectroscopy, transmission electron microscopy, selected area electron diffraction, and atomic force microscopy experiments. For comparison, the structure of the related compound 4-(pyridin-4-yl) phenylboronic acid (2) is also discussed

  • 14. George, Sumod
    et al.
    Goldberg, Israel
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Self-assembly of supramolecular porphyrin arrays by hydrogen bonding: New Structures and Reflections2006Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 6, nr 3, s. 755-762Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study relates to the self-assembly of the free-base 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP), six-coordinate manganese-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin with molecules of water or methanol as axial ligands [MnIII(H2O)2-TCPP or MnIII(CH3OH)2-TCPP, respectively], and manganese chloride-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin [MnIII(Cl)-TOHPP] into multiporphyrin hydrogen-bonding "polymers". In the first case, the porphyrin units hydrogen bond directly to each other through their carboxylic acid functions. The two-dimensional (2D) square-grid polymeric arrays thus formed are sustained by characteristic intermolecular cyclic dimeric (COOH)2 hydrogen-bond synthons between a given porphyrin unit and four other neighboring species along the equatorial directions. They stack tightly one on top of the other in an offset manner along the normal direction, yielding channeled lattice architecture. In an aqueous basic environment insertion of MnIII into the porphyrin core involves deprotonation of one of the carboxylic groups, to balance the charge, and attraction of two water molecules as axial ligands. The MnIII(H2O)2-TCPP units hydrogen bond, however, directly to one another through their carboxylic/carboxylate functions in the equatorial plane in a catemeric (rather than cyclic dimeric) manner. The 2D networks that form in this case are interconnected in the normal direction by additional hydrogen bonds through the axial water ligands, yielding a three-dimensional (3D) hydrogen-bonding architecture. In a methanolic solution of H3PO4, the methanol molecules replace water as axial ligands to the metal ion. The phosphate anions balance the extra positive charge of the trivalent metal, and they act also as effective bridges between adjacent MnIII(CH3OH)2-TCPP moieties by interacting as proton acceptors with the peripheral carboxylic functions of four different porphyrins. This affords open square-grid-type layers with alternating porphyrin and phosphate components. The 2D arrays stack in an offset manner, interconnecting to one another through hydrogen bonds involving the methanol axial ligands. The Mn(Cl)-TOHPP building blocks arrange in a unique tetragonal structure around axes of 4-fold rotation and self-assemble through multiple O-HCl- attractions between neighboring units into a single-framework hydrogen-bonding polymer. The directional asymmetry introduced to them by the Cl-axial ligand, which is amplified by the preferred hydrogen-bonding scheme, induces the formation of a noncentrosymmetric crystal structure. The nanoporous nature of TCPP-based multiporphyrin assemblies and the chirality of the Mn(Cl)-TOHPP structure are highlighted.

  • 15. George, Sumod
    et al.
    Lipstman, Sophia
    Tel Aviv UniVersity, School of Chemistry, Sackler Faculty of Exact Sciences.
    Goldberg, Israel
    Tel Aviv UniVersity, School of Chemistry, Sackler.
    Porphyrin supramolecular solids assembled with the aid of lanthanide ions2006Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 6, nr 12, s. 2651-2654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reactions of free-base tetra(4-carboxyphenyl)porphyrin with lanthanide ions as Pr3+, Dy3+, and Nd3+ led to open metal-organic framework solids sustained by polynuclear metal-carboxylate clusters. Their three-dimensional structures are characterized by channel voids accessible to other guest components (e.g., water, small organics). Crystalline solids obtained by the hydrothermal synthesis with Dy3+ and Nd3+ reagents reveal remarkable stability and represent the first example of hybrid porphyrin-lanthanide single framework architectures.

  • 16.
    Llinas, Antonio
    et al.
    R&D AstraZeneca, Respiratory, Inflammation and Autoimmune iMed.
    Barbas, Rafael
    Unitat de Polimorfisme i Calorimetria and Unitat de Difracció de Raigs X, Centres Científics i Tecnològics, Universitat de Barcelona.
    Font-Bardia, Merce
    Unitat de Polimorfisme i Calorimetria and Unitat de Difracció de Raigs X, Centres Científics i Tecnològics, Universitat de Barcelona.
    Quayle, Michael J.
    R&D AstraZeneca, Global Medicines Development, Pharmaceutical Development.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Prohens, Rafel
    Unitat de Polimorfisme i Calorimetria and Unitat de Difracció de Raigs X, Centres Científics i Tecnològics, Universitat de Barcelona.
    Two New Polymorphic Cocrystals of Zafirlukast: Preparation, Crystal Structure, and Stability Relations2015Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 15, nr 8, s. 4162-4169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new cocrystals of zafirlukast with piperazine, existing in five different solid forms, have been discovered during a cocrystal screening. The crystal structure of one of these form has been determined by single crystal X-ray diffraction, and the stability landscape of the crystalline forms of the new cocrystal has been studied. In the present article, we extend the knowledge about the solid state of this important pharmaceutical drug for the treatment of asthma by reporting the crystal structures of two new solvates (acetonitrile and butanol) and the elusive anhydrous Form X, which have been solved by single crystal X-ray diffraction

  • 17.
    Lou, Benyong
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Boström, Dan
    Umeå university.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Polymorph control of Felodipine form II in an attempted cocrystallization2009Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 9, nr 3, s. 1254-1257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The metastable form II of racemic felodipine was obtained in an attempted cocrystallization with isonicotinamide. Its low temperature crystal structure was characterized by a 1D hydrogen-bonded chain consisting of four independent felodipine molecules.

  • 18.
    Marivel, Samipillai
    et al.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry.
    Shimpi, Manishkumar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Pedireddi, V.R.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry.
    Novel Supramolecular Assemblies of Coordination Polymers of Zn(II) and Bis(4-nitrophenyl)phosphoric Acid with Some Aza-Donor Compounds2007Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, nr 9, s. 1791-1796Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supramolecular assemblies of coordination polymers of Zn(II) and bis(4-nitrophenyl)phosphoric acid, BNPP, with aza-donor compounds, 4,4¢-bipyridine (bpy), 1,2-bis(4-pyridyl)ethane (bpyea), 1,2-bis(4-pyridyl)ethene (bpyee), and 1,3-bis(4-pyridyl)-propane (bpypa), have been reported. All the compounds are quite similar in the three-dimensional packing, irrespective of the varied dimensions of aza-donor molecules. All four compounds were synthesized by treating BNPP with corresponding aza-donor molecules in the presence of MeOH and water as the solvents. The structures were characterized by single-crystal X-ray diffraction.

  • 19.
    Padrela, Luis
    et al.
    Department of Chemical and Biological Engineering, Instituto Superior Técnico, Lisboa.
    Rodrigues, Miguel A.
    Department of Chemical and Biological Engineering, Instituto Superior Técnico, Lisboa, Department of Chemical Engineering and Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa.
    Tiago, João
    Department of Chemical Engineering and Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Matos, Henrique A.
    Department of Chemical and Biological Engineering, Instituto Superior Técnico, Lisboa, Department of Chemical Engineering and Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa.
    Azevedo, Edmundo Gomes de
    Department of Chemical Engineering and Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Department of Chemical and Biological Engineering, Instituto Superior Técnico, Lisboa.
    Insight into the Mechanisms of Cocrystallization of Pharmaceuticals in Supercritical Solvents2015Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 15, nr 7, s. 3175-3181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon dioxide has been extensively used as a green solvent medium for the crystallization of active pharmaceutical ingredients (APIs) by replacing harmful organic solvents. This work explores the mechanisms underlying a novel recrystallization method-cocrystallization with supercritical solvent (CSS)-which enables APIs cocrystallization by suspending powders in pure CO2. Six well-known APIs that form cocrystals with saccharin (SAC) were processed by CSS, namely, theophylline (TPL), indomethacin (IND), carbamazepine (CBZ), caffeine (CAF), sulfamethazine (SFZ), and acetylsalicylic acid (ASA). Pure cocrystals were obtained for TPL, IND, and CBZ (with SAC) after 2 h of CSS processing. Convection was revealed to be a determining parameter for successful cocrystallization with high-yield levels. TPL-SAC was selected as a model system to study the cocrystallization kinetics in the gas, supercritical, and liquid phases under different conditions of pressure (8-20 MPa), temperature (30 to 70 degrees C), and convection regimes. The solubility of each substance in CO2 was measured at the selected working conditions. TPL-SAC showed a cocrystallization rate of 2.9% min(-1), two times higher than that of IND-SAC, due to the higher solubility of TPL in CO2. The cocrystallization kinetics was also improved by increasing the CO2 density, showing that cocrystallization was limited by the dissolution of cocrystal formers. Overall, the CSS process has a potential for scale-up as a novel, simple, solvent-free batch process whenever the cocrystal phase is formed in the CO2 media.

  • 20.
    Reddy, L. Sreenivas
    et al.
    University of Hyderabad, School of Chemistry.
    Basavoju, Srinivas
    Vangala, Venu R.
    University of Hyderabad, School of Chemistry.
    Nangia, Ashwin
    University of Hyderabad, School of Chemistry.
    Hydrogen bonding in crystal structures of N,N'-Bis(3-pyridyl)urea: why is the N-H···O tape synthon absent in diaryl ureas with electron-withdrawing groups?2006Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 6, nr 1, s. 161-173Artikkel i tidsskrift (Fagfellevurdert)
  • 21.
    Reddy, L. Sreenivas
    et al.
    University of Hyderabad, School of Chemistry.
    Chandran, Sreekanth K
    University of Hyderabad, School of Chemistry.
    George, Sumod
    Babu, N. Jagadeesh
    University of Hyderabad, School of Chemistry.
    Nangia, Ashwini
    University of Hyderabad, School of Chemistry.
    Crystal Structures of N-Aryl-N′-4-Nitrophenyl Ureas: Molecular Conformation and Weak Interactions Direct the Strong Hydrogen Bond Synthon2007Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, nr 12, s. 2675-2690Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrogen bond competition was studied in 21 X-ray crystal structures of N-X-phenyl-N′-p-nitrophenyl urea compounds (X = H, F, Cl, Br, I, CN, C≡CH, CONH2, COCH3, OH, Me). These structures are classified into two families depending on the hydrogen bond pattern: urea tape structures contain the well-known α-network assembled via N-HO hydrogen bonds; however, in nonurea tape structures the N-H donors hydrogen bond with NO2 groups or solvent O acceptor atoms. Surprisingly, the urea CO hardly accepts strong H bonds in nonurea type structures sustained by ureanitro and ureasolvent synthons. The carbonyl group accepts intra- and intermolecular C-HO interactions. The molecular conformation and H bonding motifs are different in the two categories of structures: the phenyl rings are twisted out of the urea plane in the tape motif, but they are coplanar in the nonurea category. Even though hydrogen bond synthon energy and urea carbonyl acceptor strength favor the N-HO tape structure, the dominant pattern in electron-withdrawing aryl urea crystal structures is the ureanitro/ureasolvent synthon and persistence of intramolecular C-HO interactions. Remarkably, the presence of functional groups that can promote specific C-IO or C-HO interactions with the interfering NO2 group, for example, when X = I, C≡CH, NMe2, and Me, steers crystallization toward the N-HO urea tape structure, and now the diaryl urea molecule adopts the metastable, twisted conformation. Molecular conformer energy calculations and difference nuclear Overhauser enhancement NMR experiments show that the planar, trans-trans-N,N′-diphenyl urea conformation is more stable than the N-Ph twisted rotamer. However, the urea CO is a better hydrogen bond acceptor in the twisted conformer compared to the planar one, based on electrostatic surface potential (ESP) charges. These diaryl ureas together with previously reported crystal structures provide a global structural model to understand how functional groups, molecular conformation, hydrogen bonding, and crystal packing are closely related and influence each other in subtle yet definitive ways. Our strategy simultaneously exploits weak, soft intermolecular interactions and strong, hard hydrogen bonds [supramolecular hard and soft acid-base (HSAB) principle] in the crystal engineering of multifunctional molecules.

  • 22.
    Schwartz, Albert M.
    et al.
    Michigan State University.
    Berglund, Kris
    Comparison of supersaturation profiles employed on lysozyme crystallization from a hanging drop2001Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 1, nr 1, s. 81-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy combined with a partial least-squares regression model was used as a monitor of lysozyme concentration during crystallization in a hanging-drop experiment in real time. Raman spectral features of the buffer and protein were employed to build the regression model. The use of fiber optic technology coupled with Raman spectroscopy, which is ideal for use with aqueous solutions, results in a powerful, noninvasive probe of the changing environment within the solution. Monitoring the concentration changes of the lysozyme within the hanging drop permits a measurement of the level of supersaturation of the system and provides for the potential of dynamic control of the crystallization process. Previously, hanging-drop experiments have been monitored in real time. These experiments have given insight into the changing environment of the hanging drop as the lysozyme within the hanging drop concentrates and nucleates and as crystal growth continues. Upon alteration of the ionic strength of the reservoir, the number, size, and quality of the resultant crystals has been affected. This investigation compares the resultant supersaturation of the lysozyme crystallization within the hanging drop by employing various reservoir conditions. These conditions include a constant ionic strength reservoir, a step change in reservoir ionic strength, and a differential change in reservoir ionic strength.

  • 23.
    Shimpi, Manishkumar R.
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Al-Hayali, Amani
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Cavanagh, Katie L.
    Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor.
    Rodríguez- Hornedo, Nair
    Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor.
    Velaga, Sitaram P.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Tadalafil-malonic acid cocrystal: Physicochemical characterization, pH-solubility and supersaturation studies2018Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 18, nr 8, s. 4378-4387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to enhance the solubility and dissolution of a poorly water-soluble drug, tadalafil (TDF), by cocrystal formation with malonic acid (MOA), to characterize the cocrystal structure, and to quantify the cocrystal solution behavior. The crystal structure revealed a 1:1 stoichiometry wherein the TDF molecules form a double layered structure through N–H…O=C interactions linked to a catemeric chain of MOA molecules via O-H…O hydrogen bonds. Cocrystal solubility advantage (SA defined as Scocrystal/Sdrug) or supersaturation index was determined from eutectic point measurements to be 102 to 129 in the pH range of 1 to 3. Cocrystal dissolution generated supersaturation levels (Cmax/Sdrug) of 30 in buffer and 120 in the presence of a nucleation inhibitor, HPMC. The amorphous form of TDF generated supersaturation 3 times lower than cocrystal in buffer, and not significantly different from cocrystal in the presence of HPMC. Thus, supersaturation index is a valuable metric for assessing the risk of cocrystal conversion during kinetic studies and for predicting conditions when the usage of a precipitation inhibitor may significantly increase cocrystal exposure levels.

  • 24.
    Shimpi, Manishkumar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Seethalekshmi, Nanappan
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry, National Chemical Laboratory, Pune.
    Pedireddi, V.R.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry, National Chemical Laboratory, Pune.
    Supramolecular architecture in some 4-halophenylboronic acids2007Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, nr 10, s. 1958-1963Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crystal structures of 4-chloro- and 4-bromophenylboronic acids (1 and 2) and hydrates of 2 and 4-iodophenylboronic acid in two different forms (2a, 3a, and 3b), which were characterized by single-crystal X-ray diffraction methods, are reported. In structures I and 2, -B(OH)2 forms a syn-anti conformation, but it exists in syn-syn as well as anti-anti conformations in the hydrated structures 2a, 3a, and 3b. In all the structures, the molecules are held together by O-H center dot center dot center dot O interactions formed by -B(OH)2 groups. The C-H center dot center dot center dot X (X = Cl, Br, and I) interactions play an important role in crystal packing. In 2, Br center dot center dot center dot Br interactions are also observed. Interestingly, all the three hydrates form similar types of three-dimensional structures with the formation of channels, which are occupied by water molecules. The two hydrates of 4-iodophenylboronic acid (3a and 3b) are distinguishable on the basis of O center dot center dot center dot O short contacts, with an identical host lattice of the boronic acid.

  • 25.
    Shimpi, Manishkumar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Pharmaceutical Crystal Engineering Using Ionic Liquid Anion–Solute Interactions2017Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 17, nr 4, s. 1729-1734Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main purpose of this work was to investigate the potential of ionic liquids (ILs) in crystal engineering. We have employed ILs with different combinations of cations and anions to study their role in directing crystal structure formation of a nicotinamide (NIC) and oxalic acid (OXA) system. A new crystal form of NIC–OXA salt (2:1) was identified and characterized using standard solid state tools such as powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Raman and infrared spectroscopy. The crystal structure of the 2:1 salt was elucidated using single-crystal X-ray diffraction. The NIC–OXA 2:1 salt form revealed a two-dimensional layered structure, while the known 1:1 salt had a perpendicular “tape-like” structure. The 2:1 salt form could only be crystallized from the ILs possessing hydrogen bond acceptor functionality. We demonstrated that specific ILs could be selected as solvents for altering the solid-state structure of organic and inorganic materials.

  • 26.
    Talwelkarshimpi, Mayura
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Giri, Lopamudra
    Solid State & Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar.
    Pedireddi, Venkateswara R.
    Solid State & Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar.
    Some hydrated molecular complexes of 4-cyanophenylboronic acid: Significance of water in the structure stabilization by theoretical investigation2017Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 17, nr 12, s. 6247-6254Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular complexes 1a – 1c, of 4-cyanophenylboronic acid, 1, with N-donor compounds, 4,4'-bipyridine (a), 1,2-bis(4-pyridyl)ethene (b) and melamine (c), respectively, have been prepared, in the form of single crystals, by slow solvent evaporation method. Three-dimensional structures of all the complexes have been determined by X-ray diffraction technique. All the complexes 1a – 1c were noted to be crystallized as hydrates. Variations in the patterns of intermolecular interactions amongst the complexes and also the geometrical features of 1 have been analysed comparing with the features found in the native structure of 1 by determining its crystal structure also. -B(OH)2 moiety in the native form of 1 and also in the molecular complexes, 1a – 1c, adopts syn - anti conformation. Further, calculations were performed, using DFT-D3 method, to rationalize the propensity of formation of hydrate structures and to deliberate the observed structural features with respect to the strength of the intermolecular interactions, for instance, hydrogen bonds.

  • 27.
    Tamagawa, Rosana E.
    et al.
    Campinas State University.
    Miranda, Everson A.
    Campinas State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Simultaneous monitoring of protein and (NH4)(2)SO4 concentrations in aprotinin hanging-drop crystallization using Raman spectroscopy2002Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, nr 6, s. 511-514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study the use of fiber optic Raman spectroscopy for the in situ monitoring of aprotinin supersaturation in a hanging-drop crystallization is described. The crystallizing agent, (NH4)2SO4, is Raman active, which allows monitoring of the salt concentration in the drop during the whole hanging-drop crystallization process in addition to monitoring of the aprotinin concentration. Through the continuous measuring of protein and salt concentrations, supersaturation in the drop solution was measured in real time. Moreover, through the monitoring of protein and salt concentrations, the cocrystallization of aprotinin and (NH4)2SO4 was observed.

  • 28.
    Tamagawa, Rosana
    et al.
    Campinas State University.
    Miranda, Everson
    Michigan State University.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Raman spectroscopic monitoring and control of aprotinin supersaturation in hanging-drop crystallization2002Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, nr 4, s. 263-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber optic Raman spectroscopy is used for in situ monitoring of supersaturation during the hanging-drop crystallization of aprotinin. Schwartz and Berglund (1999) previously demonstrated this technique for lysozyme crystallization and showed it combines two critical elements for protein crystallization studies: real-time monitoring/control of supersaturation and small amounts of sample. Experiments were carried out using 10 L of protein solution. A partial-least-squares (PLS) calibration based on Raman spectra of standard solutions allowed an accurate measurement of aprotinin in a range of 2-100 mg/mL with a standard error of 0.54 mg/mL determined by a leave-one-out cross validation. A 10× microscope attached to a Raman fiber optic probe allowed the monitoring of the hanging-drop liquid phase in a noninvasive and real-time mode. Aprotinin solubility determined by measuring the protein concentration of drop solution at equilibrium decreased with increase in NaCl concentration. By continuously collecting Raman spectra of the liquid phase in the drop, the protein concentration was monitored in real time during the whole process. Control of supersaturation by manipulating the evaporation rate of the drop solution allowed the optimization of the process, leading to an increase in the resulting crystal size.

  • 29.
    Vomiero, Alberto
    et al.
    CNR-INFM SENSOR Laboratory.
    Bianchi, Sebastiano
    CNR-INFM SENSOR Laboratory.
    Comini, Elisabetta
    CNR-INFM SENSOR Laboratory.
    Faglia, Guido
    CNR-INFM SENSOR Laboratory.
    Ferroni, Matteo
    CNR-INFM SENSOR Laboratory.
    Sberveglieri, Giorgio
    CNR-INFM SENSOR Laboratory.
    Controlled growth and sensing properties of in2O3 nanowires2007Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, nr 12, s. 2500-2504Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single-crystalline nanowires of indium oxide were produced under controlled conditions via condensation from the vapor phase. Seeding of the substrate through dispersion of metallic indium nanoparticles was proven effective in promoting a nanowire nucleation driven by the vapor-solid process. Nanowires with as small an average lateral dimension as 110 nm were produced, allowing the exploitation of size reduction effects on the electrical properties and the response to gases. Preparation and microstructural and electrical characterization of nanowires are presented, and the peculiarities of these innovative structures for the development of nanodevices are highlighted. © 2007 American Chemical Society.

  • 30.
    Vomiero, Alberto
    et al.
    INFM-CNR Sensor Lab and Department of Chemistry and Physics for Engineering and Materials, University of Brescia.
    Ferroni, Matteo
    INFM-CNR Sensor Lab.
    Comini, Elisabetta
    INFM-CNR Sensor Lab.
    Faglia, Guido
    INFM-CNR Sensor Lab.
    Sberveglieri, Giorgio
    INFM-CNR Sensor Lab.
    Insight into the formation mechanism of one-dimensional indium oxide wires2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 1, s. 140-145Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Controlled growth of oxide nanowires is an emerging research field with many applications in, for example, electronics, energy production and storage, security, and life science. A great number of theoretical and experimental studies have been carried out on the model of growth of semiconducting nanowires, while the systematic analysis of oxide nanowires is still missing. We have examined the morphological and structural features Of In2O 3nanowires grown on single crystal substrate, catalyzed by gold clusters, to investigate the basic growth mechanisms of oxide nanowires. These nanowires exhibit a bodycentered cubic structure and grow along the [100] vector of the cubic crystalline cell, thus being an ideal system for modeling nanowire nucleation and growth, without any preferential direction due to cell anisotropy. Bare vapor-solid (VS) or vapor-liquid-solid (VLS), which are the commonly accepted growth mechanisms, cannot account for the complete description of oxide nanowire growth. The experimental findings can be satisfactorily explained under the hypothesis of concurrent direct VS and catalyst-mediated VLS mechanisms during nanowire growth, with the formation of high-index lateral faces which regulates longitudinal elongation at high temperature, according to the periodic bond chain (PBC) theory. 2009 American Chemical Socieiy.

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