Displaying publications 1 - 20 of 181 in total

  1. Usman A, Razak IA, Chantrapromma S, Fun HK, Philip V, Sreekanth A, et al.
    Acta Crystallogr C, 2002 Nov;58(Pt 11):o652-4.
    PMID: 12415171
    The title compound, C(16)H(17)N(5)S, is in the thione form and crystallizes with two independent molecules in the asymmetric unit. In both molecules, the pentamethyleneimine five-membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C-N bond.
    Matched MeSH terms: Crystallization
  2. Chan SY, Toh SM, Khan NH, Chung YY, Cheah XZ
    Drug Dev Ind Pharm, 2016 Nov;42(11):1800-1812.
    PMID: 27049232
    Solution-mediated transformation has been cited as one of the main problems that deteriorate dissolution performances of solid dispersion (SD). This is mainly attributed by the recrystallization tendency of poorly soluble drug. Eventually, it will lead to extensive agglomeration which is a key process in reducing the dissolution performance of SD and offsets the true benefit of SD system. Here, a post-processing treatment is suggested in order to reduce the recrystallization tendency and hence bring forth the dissolution advantage of SD system.
    Matched MeSH terms: Crystallization
  3. Ali MS, Said ZS, Rahman RN, Chor AL, Basri M, Salleh AB
    Int J Mol Sci, 2013 Aug 28;14(9):17608-17.
    PMID: 23989606 DOI: 10.3390/ijms140917608
    Seeding is a versatile method for optimizing crystal growth. Coupling this technique with capillary counter diffusion crystallization enhances the size and diffraction quality of the crystals. In this article, crystals for organic solvent-tolerant recombinant elastase strain K were successfully produced through microseeding with capillary counter-diffusion crystallization. This technique improved the nucleation success rate with a low protein concentration (3.00 mg/mL). The crystal was grown in 1 M ammonium phosphate monobasic and 0.1 M sodium citrate tribasic dihydrate pH 5.6. The optimized crystal size was 1 × 0.1 × 0.05 mm³. Elastase strain K successfully diffracted up to 1.39 Å at SPring-8, Japan, using synchrotron radiation for preliminary data diffraction analysis. The space group was determined to be monoclinic space group P12(1)1 with unit cell parameters of a = 38.99 Ǻ, b = 90.173 Å and c = 40.60 Å.
    Matched MeSH terms: Crystallization/methods*
  4. Normah, I., Cheow, C.S., Chong, C.L.
    Diacylglycerol at 1 or 6% was added into refined bleached and deodorized palm oil (RBDPO) and crystallized from the melt in a thermally controlled water bath at 22°C for 90 min. Slurries were withdrawn after 5, 15, 30, 60 and 90 min of crystallization for solid fat content (SFC) and crystal morphology studies. Crystallization was also performed in a similar manner using a Labmax reactor connected to a FBRM detector to obtain the information on crystal count and size distribution during crystallization. SFC of the slurries increased with increase in crystallization time up to a certain level followed by a plateau. SFC of RBDPO added with DAG was also higher with the increase in percentage of DAG added and no induction time was observed to initiate crystallization in RBDPO added with DAG. The addition of DAG caused rapid crystallization of RBDPO as observed by enhance nucleation and larger crystal size with increase in the percentages of DAG added.
    Matched MeSH terms: Crystallization
  5. Toozandehjani, Meysam, Khamirul Amin Matori, Ostovan, Farhad, Sidek Abdul Aziz, Md Shuhazely Mamat, Oskoueian, Arshin
    Carbon nanotube reinforced aluminium matrix composites (Al-CNTs) have been widely used in aerospace and automotive industries where high quality and strength is required. The enhanced mechanical properties of Al-CNTs are closely related to processing technique due to challenges within production of these composite materials. In the current review, solid state processing techniques used for synthesizing Al-CNTs have been reviewed to provide an insight into the features and capabilities of each technique regarding the incorporation of CNT reinforcements. To conclude, the mechanical performance of Al-CNT composites is mainly decided by the capability of each technique in the dispersion of CNTs within the aluminum matrix.
    Matched MeSH terms: Crystallization
  6. Barrio JD, Liu J, Brady RA, Tan CSY, Chiodini S, Ricci M, et al.
    J Am Chem Soc, 2019 09 11;141(36):14021-14025.
    PMID: 31422657 DOI: 10.1021/jacs.9b07506
    The binding of imidazolium salts to cucurbit[8]uril, CB[8], triggers a stepwise self-assembly process with semiflexible polymer chains and crystalline nanostructures as early- and late-stage species, respectively. In such a process, which involves the crystallization of the host-guest complexes, the guest plays a critical role in directing self-assembly toward desirable morphologies. These include platelet-like aggregates and two-dimensional (2D) fibers, which, moreover, exhibit viscoelastic and lyotropic properties. Our observations provide a deeper understanding of the self-assembly of CB[8] complexes, with fundamental implications in the design of functional 2D systems and crystalline materials.
    Matched MeSH terms: Crystallization
  7. Tagg T, McAdam CJ, Robinson BH, Simpson J
    Acta Crystallogr E Crystallogr Commun, 2015 Jul 1;71(Pt 7):816-20.
    PMID: 26279875 DOI: 10.1107/S2056989015011494
    The title compound, C16H10, crystallizes with four unique mol-ecules, designated 1-4, in the asymmetric unit of the monoclinic unit cell. None of the mol-ecules is planar, with the benzene rings of mol-ecules 1-4 inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4)°, respectively. In the crystal, weak C-H⋯π(ring) interactions, augmented by even weaker C C-H⋯π(alkyne) contacts, generate a three-dimensional network structure with inter-linked columns of mol-ecules formed along the c-axis direction.
    Matched MeSH terms: Crystallization
  8. Chia TS, Kwong HC, Wong QA, Quah CK, Arafath MA
    Acta Crystallogr E Crystallogr Commun, 2019 Jan 01;75(Pt 1):8-11.
    PMID: 30713724 DOI: 10.1107/S2056989018016900
    A new polymorphic form of the title compound, C8H8O3, is described in the centrosymmetric monoclinic space group P21/c with Z' = 1 as compared to the first polymorph, which crystallizes with two conformers (Z' = 2) in the asymmetric unit in the same space group. In the crystal of the second polymorph, inversion dimers linked by O-H⋯O hydrogen bonds occur and these are linked into zigzag chains, propagating along the b-axis direction by C-H⋯O links. The crystal structure also features a weak π-π inter-action, with a centroid-to-centroid distance of 3.8018 (6) Å. The second polymorph of the title compound is less stable than the reported first polymorph, as indicated by its smaller calculated lattice energy.
    Matched MeSH terms: Crystallization
  9. Harrison WT, Plater MJ, Yin LJ
    Acta Crystallogr E Crystallogr Commun, 2016 Mar 1;72(Pt 3):407-11.
    PMID: 27006818 DOI: 10.1107/S2056989016002942
    The title compounds, C14H12O, (I), and C15H11BrO2, (II), were prepared and characterized as part of our studies of potential new photo-acid generators. In (I), which crystallizes in the ortho-rhom-bic space group Pca21, compared to P21/n for the previously known monoclinic polymorph [Cornella & Martin (2013 ▸). Org. Lett. 15, 6298-6301], the dihedral angle between the aromatic rings is 4.35 (6)° and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), mol-ecules are linked by O-H⋯π inter-actions involving both the major and minor -OH disorder components, generating [001] chains as part of the herringbone packing motif. The asymmetric unit of (II) contains two mol-ecules with similar conformations (weighted r.m.s. overlay fit = 0.183 Å). In the crystal of (II), both mol-ecules form carboxyl-ate inversion dimers linked by pairs of O-H⋯O hydrogen bonds, generating R 2 (2)(8) loops in each case. The dimers are linked by pairs of C-H⋯O hydrogen bonds to form [010] chains.
    Matched MeSH terms: Crystallization
  10. Ma L, Liu X, Soh AK, He L, Wu C, Ni Y
    Soft Matter, 2019 May 15.
    PMID: 31090782 DOI: 10.1039/c9sm00507b
    Topological defect nucleation and boundary branching in crystal growth on a curved surface are two typical elastic instabilities driven by curvature induced stress, and have usually been discussed separately in the past. In this work they are simultaneously considered during crystal growth on a sphere. Phase diagrams with respect to sphere radius, size, edge energy and stiffness of the crystal for the equilibrium crystal morphologies are achieved by theoretical analysis and validated by Brownian dynamics simulations. The simulation results further demonstrate the detail of morphological evolution governed by these two different stress relaxation modes. Topological defect nucleation and boundary branching not only compete with each other but also coexist in a range of combinations of factors. Clarification of the interaction mechanism provides a better understanding of various curved crystal morphologies for their potential applications.
    Matched MeSH terms: Crystallization
  11. Tarawneh MA, Sahrim Ahmad, Rozaidi Rasid, Yahya S, Shamsul Bahri A, Ehnoum S, et al.
    Sains Malaysiana, 2011;40:1179-1186.
    The effect of various multi-walled carbon nanotubes (MWNTs) on the tensile properties of thermoplastic natural rubber (TPNR) nanocomposite was investigated. The nanocomposite was prepared using melt blending method. MWNTs were added to improve the mechanical properties of MWNTs/TPNR composites in different compositions of 1, 3, 5, and 7 wt.%. The results showed that the mechanical properties of nanocomposites were affected significantly by the composition and the properties of MWNTs. SEM micrographs confirmed the homogenous dispersion of MWNTs in the TPNR matrix and promoted strong interfacial adhesion between MWNTs and the matrix which was improved mechanical properties significantly.
    Matched MeSH terms: Crystallization
  12. Hutagalung SD, Ying OL, Ahmad ZA
    PMID: 18276560 DOI: 10.1109/TUFFC.2007.582
    This paper presents the effects of calcination time and sintering temperature on the properties of CaCu(3)Ti(4)O(12). Electroceramic material of CaCu(3)Ti(4)O(12) was prepared using a modified mechanical alloying technique that covers several processes, which are preparation of raw material, mixing and ball milling for 5 hours, calcination, pellet forming and, sintering. The objective of this modified technique is to enable the calcination and sintering processes to be carried out at a shorter time and lower temperature. The x-ray diffraction (XRD) analysis result shows that a single-phase of CaCu(3)Ti(4)O(12) was completely formed by calcination at 750 degrees C for 12 hours. Meanwhile, the grain size of a sample sintered at 1050 degrees C for 24 hours is extremely large, in the range of 20-50 mum obtained from field emission scanning electron microscopy (FESEM) images. The dielectric constant value of 14,635 was obtained at 10 kHz by impedance (LCR) meter in the sintered sample at 1050 degrees C. However, the dielectric constant value of samples sintered at 900 and 950 degrees C is quite low, in the range of 52-119.
    Matched MeSH terms: Crystallization/methods*
  13. Goh CF, Moffat JG, Craig DQM, Hadgraft J, Lane ME
    Mol Pharm, 2019 01 07;16(1):359-370.
    PMID: 30525649 DOI: 10.1021/acs.molpharmaceut.8b01027
    Drug crystallization on and in the skin has been reported following application of topical or transdermal formulations. This study explored novel probe-based approaches including localized nanothermal analysis (nano-TA) and photothermal microspectroscopy (PTMS) to investigate and locate drug crystals in the stratum corneum (SC) of porcine skin following application of simple ibuprofen (IBU) formulations. We also conducted in vitro skin permeation studies and tape stripping. The detection of drug crystals in the SC on tape strips was confirmed using localized nano-TA, based on the melting temperature of IBU. The melting of IBU was also evident as indicated by a double transition and confirmed the presence of drug crystals in the SC. The single point scans of PTMS on the tape strips allowed collection of the photothermal FTIR spectra of IBU, confirming the existence of drug crystals in the skin. The combined methods also indicated that drug crystallized in the SC at a depth of ∼4-7 μm. Future studies will examine the potential of these techniques to probe crystallization of other commonly used actives in topical and transdermal formulations.
    Matched MeSH terms: Crystallization/methods*
  14. Yahya N, Al Habashi RM, Koziol K, Borkowski RD, Akhtar MN, Kashif M, et al.
    J Nanosci Nanotechnol, 2011 Mar;11(3):2652-6.
    PMID: 21449447
    Aluminum substituted yttrium iron garnet nano particles with compositional variation of Y(3.0-x) A1(x)Fe5O12, where x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 were prepared using sol gel technique. The X-ray diffraction results showed that the best garnet phase appeared when the sintering temperature was 800 degrees C. Nano-crystalline particles with high purity and sizes ranging from 20 to 100 nm were obtained. It was found that the aluminum substitution had resulted in a sharp fall of the d-spacing when x = 2, which we speculated is due to the preference of the aluminum atoms to the smaller tetrahedron and octahedron sites instead of the much larger dodecahedron site. High resolution transmission electron microscope (HRTEM) and electron diffraction (ED) patterns showed single crystal nanoparticles were obtained from this method. The magnetic measurement gave moderate values of initial permeability; the highest value of 5.3 was shown by sample Y3Fe5O12 at more than 100 MHz which was attributed to the morphology of the microstructure which appeared to be homogeneous. This had resulted in an easy movement of domain walls. The substitution of aluminum for yttrium is speculated to cause a cubic to rhombodedral structural change and had weakened the super-exchange interactions thus a fall of real permeability was observed. This might have created a strain in the sub-lattices and had subsequently caused a shift of resonance frequencies to more than 1.8 GHz when x > 0.5.
    Matched MeSH terms: Crystallization/methods
  15. Ab Latip R, Lee YY, Tang TK, Phuah ET, Lee CM, Tan CP, et al.
    PeerJ, 2013;1:e72.
    PMID: 23682348 DOI: 10.7717/peerj.72
    Fractionation which separates the olein (liquid) and stearin (solid) fractions of oil is used to modify the physicochemical properties of fats in order to extend its applications. Studies showed that the properties of fractionated end products can be affected by fractionation processing conditions. In the present study, dry fractionation of palm-based diacylglycerol (PDAG) was performed at different: cooling rates (0.05, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0°C/min), end-crystallisation temperatures (30, 35, 40, 45 and 50°C) and agitation speeds (30, 50, 70, 90 and 110 rpm) to determine the effect of these parameters on the properties and yield of the solid and liquid portions. To determine the physicochemical properties of olein and stearin fraction: Iodine value (IV), fatty acid composition (FAC), acylglycerol composition, slip melting point (SMP), solid fat content (SFC), thermal behaviour tests were carried out. Fractionation of PDAG fat changes the chemical composition of liquid and solid fractions. In terms of FAC, the major fatty acid in olein and stearin fractions were oleic (C18:1) and palmitic (C16:0) respectively. Acylglycerol composition showed that olein and stearin fractions is concentrated with TAG and DAG respectively. Crystallization temperature, cooling rate and agitation speed does not affect the IV, SFC, melting and cooling properties of the stearin fraction. The stearin fraction was only affected by cooling rate which changes its SMP. On the other hand, olein fraction was affected by crystallization temperature and cooling rate but not agitation speed which caused changes in IV, SMP, SFC, melting and crystallization behavior. Increase in both the crystallization temperature and cooling rate caused a reduction of IV, increment of the SFC, SMP, melting and crystallization behaviour of olein fraction and vice versa. The fractionated stearin part melted above 65°C while the olein melted at 40°C. SMP in olein fraction also reduced to a range of 26 to 44°C while SMP of stearin fractions increased to (60-62°C) compared to PDAG.
    Matched MeSH terms: Crystallization
  16. Shariff FM, Rahman RN, Ali MS, Chor AL, Basri M, Salleh AB
    PMID: 20516608 DOI: 10.1107/S174430911001482X
    Purified thermostable recombinant L2 lipase from Bacillus sp. L2 was crystallized by the counter-diffusion method using 20% PEG 6000, 50 mM MES pH 6.5 and 50 mM NaCl as precipitant. X-ray diffraction data were collected to 2.7 A resolution using an in-house Bruker X8 PROTEUM single-crystal diffractometer system. The crystal belonged to the primitive orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 87.44, b = 94.90, c = 126.46 A. The asymmetric unit contained one single molecule of protein, with a Matthews coefficient (V(M)) of 2.85 A(3) Da(-1) and a solvent content of 57%.
    Matched MeSH terms: Crystallization
  17. Ganesan K, Alias Y, Ng SW
    Acta Crystallogr C, 2008 Sep;64(Pt 9):o478-80.
    PMID: 18758014 DOI: 10.1107/S0108270108023111
    Crystallization of the ionic liquid 3,3'-dimethyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(tetrafluoroborate), C(16)H(20)N(4)(2+).2BF(4)(-), (I), from its solution in water has permitted the first single-crystal study of an imidazolium-based ionic liquid having a tetrafluoroborate ion as counter-ion. Despite the expectation that the anion would not participate in nonclassical hydrogen bonding, the ionic liquid features C-H...F hydrogen bonds. The dication lies about a center of inversion. The ionic liquid 3,3'-di-n-butyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(trifluoromethanesulfonate), C(22)H(32)N(4)(2+).2CF(3)SO(3)(-), (II), features both C-H...F and C-H...O hydrogen bonds.
    Matched MeSH terms: Crystallization
  18. Parlak C, Ramasami P, Kumar CS, Tursun M, Quah CK, Rhyman L, et al.
    PMID: 25974671 DOI: 10.1016/j.saa.2015.04.022
    A novel (2E)-1-(5-chlorothiophen-2-yl)-3-{4-[(E)-2-phenylethenyl]phenyl}prop-2-en-1-one [C21H15ClOS] compound has been synthesized and its structure has been characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the compound have been examined by means of HF, MP2, BP86, BLYP, BMK, B3LYP, B3PW91, B3P86 and M06-2X functionals. Reliable vibrational assignments and molecular orbitals have been investigated by the potential energy distribution and natural bonding orbital analyses, respectively. The compound crystallizes in the triclinic space group P-1 with the cis-trans-trans form. There is a good agreement between the experimentally determined structural parameters and vibrational frequencies of the compound and those predicted theoretically using the density functional theory with the BLYP and BP86 functionals.
    Matched MeSH terms: Crystallization
  19. Tong ML, Ye BH, Cai JW, Chen XM, Ng SW
    Inorg Chem, 1998 Jun 01;37(11):2645-2650.
    PMID: 11670398
    In the presence of guest 2,4'-bpy molecules or under acidic conditions, three compounds, [Cd(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (1), [Zn(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (2), and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)bpy) (3), were obtained from the reactions of the metal salts and 4,4'-bpy in an EtOH-H(2)O mixture. 1 has a 2-D square-grid network structure, crystallizing in the monoclinic space group P2/n, with a = 13.231(3) Å, b = 11.669(2) Å, c = 15.019(3) Å, beta = 112.82(3) degrees, Z = 2; 2 is isomorphous with 1, crystallizing in the monoclinic space group P2/n, with a = 13.150(3) Å, b = 11.368(2) Å, c = 14.745(3) Å, beta = 110.60(3) degrees, Z = 2. The square grids superpose on each other into a channel structure, in which each layer consists of two pairs of shared edges, perfectly square-planar with an M(II) ion and a 4,4'-bpy at each corner and side, respectively. The square cavity has dimensions of 11.669(2) x 11.788(2) and 11.368(2) x 11.488(2) Å for 1 and 2, respectively. Every two guest 2,4'-bpy molecules are clathrated in each hydrophobic host cavity and are further stabilized by pi-pi stacking and hydrogen bonding interactions. The NMR spectra clearly confirm that both 1 and 2 contain 4,4'-bpy and 2,4'-bpy molecules in a 1:1 ratio, which have stacking interaction with each other in the solution. 3 crystallizes in the orthorhombic space group Ibam, with a = 11.1283(5) Å, b = 15.5927(8) Å, c = 22.3178(11) Å, Z = 4. 3 is made up of two-dimensional square [Cu(4)(4,4'-bpy)(4)] grids, where the square cavity has dimensions of 11.13 x 11.16 Å. Each [4,4'-H(2)bpy](2+) cation is clathrated in a square cavity and stacks with one pair of opposite edges of the host square cavity in an offset fashion with the face-to-face distance of ca. 3.95 Å. Within each cavity, the [4,4'-H(2)bpy](2+) cation forms twin three-center hydrogen bonds with two pairs of ClO(4)(-) anions. The results suggest that the guest 2,4'-bpy molecules and protonated [4,4'-H(2)bpy](2+) cations present in the reaction systems serve as structure-directing templates in the formation of the crystal structures and exclude self-inclusion of the networks having larger square cavities.
    Matched MeSH terms: Crystallization
  20. Nur Fadzilah Basri, Fauziah Abdul Aziz, Mohd Omar, A.K., Nik Norulaini, A.R.
    The main purpose of this study was to analyzed and examined the cocoa butter samples from Sabah. This work presence the crystal phases present in cocoa butter sample thus proved the existence of polymorphs obtained from differential scanning calorimeter (DSC) analysis and confirmed by X-ray diffraction (XRD). The cocoa butter samples were extracted using a conventional method by Soxhlet Extraction method. Crystals were formed under controlled static and tempered conditions. Cocoa butter polymorphism demonstrates that it is the actual crystallization temperature, not the cooling rate that determines the polymorph that crystallizes.
    Matched MeSH terms: Crystallization
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