Displaying publications 41 - 60 of 185 in total

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  1. Taylor PW, Arnet I, Fischer A, Simpson IN
    Obes Facts, 2010 Aug;3(4):231-7.
    PMID: 20823686 DOI: 10.1159/000319450
    OBJECTIVE: To compare the pharmaceutical quality of Xenical (chemically produced orlistat) with nine generic products, each produced by fermentation processes.

    METHODS: Xenical 120 mg capsules (Roche, Basel, Switzerland) were used as reference material. Generic products were from India, Malaysia, Argentina, Philippines, Uruguay, and Taiwan. Colour, melting temperature, crystalline form, particle size, capsule fill mass, active pharmaceutical ingredient content, amount of impurities, and dissolution were compared. Standard physical and chemical laboratory tests were those developed by Roche for Xenical.

    RESULTS: All nine generic products failed the Xenical specifications in four or more tests, and two generic products failed in seven tests. A failure common to all generic products was the amount of impurities present, mostly due to different by-products, including side-chain homologues not present in Xenical. Some impurities were unidentified. Two generic products tested failed the dissolution test, one product formed a capsule-shaped agglomerate on storage and resulted in poor (=15%) dissolution. Six generic products were powder formulations.

    CONCLUSIONS: All tested generic orlistat products were pharmaceutically inferior to Xenical. The high levels of impurities in generic orlistat products are a major safety and tolerability concern.

    Matched MeSH terms: Crystallization
  2. Al-Hada NM, Saion E, Talib ZA, Shaari AH
    Polymers (Basel), 2016 Apr 08;8(4).
    PMID: 30979222 DOI: 10.3390/polym8040113
    Cadmium oxide semiconductor nanoparticles were produced using a water based mixture, incorporating cadmium nitrates, polyvinyl pyrrolidone (PVP), and calcination temperature. An X-ray diffraction (XRD) evaluation was conducted to determine the degree of crystallization of the semiconductor nanoparticles. In addition, scanning electron microscopy (SEM) was conducted to identify the morphological features of the nanoparticles. The typical particle sizes and particle dispersal were analyzed via the use of transmission electron microscopy (TEM). The findings provided further support for the XRD outcomes. To determine the composition phase, Fourier transform infrared spectroscopy (FT-IR) was conducted, as it indicated the existence of not only metal oxide ionic band in the selection of samples, but also the efficient removal of organic compounds following calcinations. The optical characteristics were demonstrated, so as to analyze the energy band gap via the use of a UV⁻Vis spectrophotometer. A reduced particle size resulted in diminution of the intensity of photoluminescence, was demonstrated by PL spectra. Plus, the magnetic characteristics were examined using an electron spin resonance (ESR) spectroscopy, which affirmed the existence of unpaired electrons.
    Matched MeSH terms: Crystallization
  3. Rahmat RA, Humphries MA, Austin JJ, Linacre AMT, Self P
    Int J Legal Med, 2021 Sep;135(5):2045-2053.
    PMID: 33655354 DOI: 10.1007/s00414-021-02538-7
    This study presents a novel tool to predict temperature-exposure of incinerated pig teeth as a proxy for understanding impacts of fire on human teeth. Previous studies on the estimation of temperature-exposure of skeletal elements have been limited to that of heat-exposed bone. This predictive tool was developed using a multinomial regression model of colourimetric and hydroxyapatite crystal size variables using data obtained from unheated pig teeth and teeth incinerated at 300 °C, 600 °C, 800 °C and 1000 °C. An additional variable based on the observed appearance of the tooth was included in the tool. This enables the tooth to be classified as definitely burnt (600 °C-1000 °C) or uncertain (27 °C/300 °C). As a result, the model predicting the temperature-exposure of the incinerated teeth had an accuracy of 95%. This tool is a holistic, robust and reliable approach to estimate temperature of heat-exposed pig teeth, with high accuracy, and may act as a valuable proxy to estimate heat exposure for human teeth in forensic casework.
    Matched MeSH terms: Crystallization
  4. 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
  5. Syafiq U, Ataollahi N, Maggio RD, Scardi P
    Molecules, 2019 Sep 23;24(19).
    PMID: 31547625 DOI: 10.3390/molecules24193454
    Cu2ZnSnS4 (CZTS) ink was synthesized from metal chloride precursors, sulfur, and oleylamine (OLA), as a ligand by a simple and low-cost hot-injection method. Thin films of CZTS were then prepared by spin coating, followed by thermal annealing. The effects of the fabrication parameters, such as ink concentration, spinning rate, and thermal treatment temperatures on the morphology and structural, optical, and electrical properties of the films were investigated. As expected, very thin films, for which the level of transmittance and band-gap values increase, can be obtained either by reducing the concentration of the inks or by increasing the rate of spinning. Moreover, the thermal treatment affects the phase formation and crystallinity of the film, as well as the electrical conductivity, which decreases at a higher temperature.
    Matched MeSH terms: Crystallization
  6. Kamarudin NH, Rahman RN, Ali MS, Leow TC, Basri M, Salleh AB
    Mol Biotechnol, 2014 Aug;56(8):747-57.
    PMID: 24771007 DOI: 10.1007/s12033-014-9753-1
    Terminal moieties of most proteins are long known to be disordered and flexible. To unravel the functional role of these regions on the structural stability and biochemical properties of AT2 lipase, four C-terminal end residues, (Ile-Thr-Arg-Lys) which formed a flexible, short tail-like random-coil segment were targeted for mutation. Swapping of the tail-like region had resulted in an improved crystallizability and anti-aggregation property along with a slight shift of the thermostability profile. The lipolytic activity of mutant (M386) retained by 43 % compared to its wild-type with 18 % of the remaining activity at 45 °C. In silico analysis conducted at 25 and 45 °C was found to be in accordance to the experimental findings in which the RMSD values of M386 were more stable throughout the total trajectory in comparison to its wild-type. Terminal moieties were also observed to exhibit large movement and flexibility as denoted by high RMSF values at both dynamics. Variation in organic solvent stability property was detected in M386 where the lipolytic activity was stimulated in the presence of 25 % (v/v) of DMSO, isopropanol, and diethyl ether. This may be worth due to changes in the surface charge residues at the mutation point which probably involve in protein-solvent interaction.
    Matched MeSH terms: Crystallization
  7. 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*
  8. Khusaini MS, Rahman RN, Mohamad Ali MS, Leow TC, Basri M, Salleh AB
    PMID: 21393852 DOI: 10.1107/S1744309111002028
    An organic solvent-tolerant lipase from Bacillus sp. strain 42 was crystallized using the capillary-tube method. The purpose of studying this enzyme was in order to better understand its folding and to characterize its properties in organic solvents. By initially solving its structure in the native state, further studies on protein-solvent interactions could be performed. X-ray data were collected at 2.0 Å resolution using an in-house diffractometer. The estimated crystal dimensions were 0.09×0.19×0.08 mm. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a=117.41, b=80.85, c=99.44 Å, β=96.40°.
    Matched MeSH terms: Crystallization
  9. 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
  10. Edith, Odeigah, Janius, Rimfiel B., Robiah Yunus
    MyJurnal
    Biodiesel is an attractive renewable energy source, which is suitable as a substitute to the non-renewablepetroleum diesel. However, it is plagued by its relatively bad cold flow behaviour. In this review, the factorsaffecting the cold flow of biodiesel, vis-à-vis the contradicting requirement of good cold flow and good ignitionproperties, are discussed. Fuel filter plugging, and crystallization of biodiesel are considered, together with thecold flow properties such as Pour Point (PP), Cloud Point (CP), Cold Filter Plugging Point (CFPP) and LowTemperature Filterability Test (LTFT). In addition, various methods used to improve the cold flow of biodieselare also presented, with a special emphasis laid on the effects of these methods in reducing the Cloud Point.Strategies to improve cold flow, and yet maintaining the good ignition quality of biodiesel, are also proposed.As far as the cold flow of biodiesel is concerned, desirable attributes of its esters are short, unsaturated andbranched carbon chains. However, these desirable attributes present opposing properties in terms of ignitionquality and oxidation stability. This is because esters with short, unsaturated and branched carbon chainspossess very good cold flow but poor ignition quality and oxidation stability. The target is therefore to producebiodiesel with good cold flow, sufficient ignition quality, and good oxidation stability. This target proves tobe quite difficult and is a major problem in biodiesel research. New frontiers in this research might be thedesign of the new cold flow improvers that is similar to those used in the petroleum diesel but is tailored forbiodiesel. Genetic modifications of the existing feedstock are also desirable but the food uses of this particularfeedstock should always be taken into consideration.
    Matched MeSH terms: Crystallization
  11. Lou Z, Xu Y, Xiang K, Su N, Qin L, Li X, et al.
    FEBS J, 2006 Oct;273(19):4538-47.
    PMID: 16972940
    The Nipah and Hendra viruses are highly pathogenic paramyxoviruses that recently emerged from flying foxes to cause serious disease outbreaks in humans and livestock in Australia, Malaysia, Singapore and Bangladesh. Their unique genetic constitution, high virulence and wide host range set them apart from other paramyxoviruses. These characteristics have led to their classification into the new genus Henpavirus within the family Paramyxoviridae and to their designation as Biosafety Level 4 pathogens. The fusion protein, an enveloped glycoprotein essential for viral entry, belongs to the family of class I fusion proteins and is characterized by the presence of two heptad repeat (HR) regions, HR1 and HR2. These two regions associate to form a fusion-active hairpin conformation that juxtaposes the viral and cellular membranes to facilitate membrane fusion and enable subsequent viral entry. The Hendra and Nipah virus fusion core proteins were crystallized and their structures determined to 2.2 A resolution. The Nipah and Hendra fusion core structures are six-helix bundles with three HR2 helices packed against the hydrophobic grooves on the surface of a central coiled coil formed by three parallel HR1 helices in an oblique antiparallel manner. Because of the high level of conservation in core regions, it is proposed that the Nipah and Hendra virus fusion cores can provide a model for membrane fusion in all paramyxoviruses. The relatively deep grooves on the surface of the central coiled coil represent a good target site for drug discovery strategies aimed at inhibiting viral entry by blocking hairpin formation.
    Matched MeSH terms: Crystallization
  12. Marikkar JM, Rana S
    J Oleo Sci, 2014;63(9):867-73.
    PMID: 25174673
    A study was conducted to detect and quantify lard stearin (LS) content in canola oil (CaO) using differential scanning calorimetry (DSC). Authentic samples of CaO were obtained from a reliable supplier and the adulterant LS were obtained through a fractional crystallization procedure as reported previously. Pure CaO samples spiked with LS in levels ranging from 5 to 15% (w/w) were analyzed using DSC to obtain their cooling and heating profiles. The results showed that samples contaminated with LS at 5% (w/w) level can be detected using characteristic contaminant peaks appearing in the higher temperature regions (0 to 70°C) of the cooling and heating curves. Pearson correlation analysis of LS content against individual DSC parameters of the adulterant peak namely peak temperature, peak area, peak onset temperature indicated that there were strong correlations between these with the LS content of the CaO admixtures. When these three parameters were engaged as variables in the execution of the stepwise regression procedure, predictive models for determination of LS content in CaO were obtained. The predictive models obtained with single DSC parameter had relatively lower coefficient of determination (R(2) value) and higher standard error than the models obtained using two DSC parameters in combination. This study concluded that the predictive models obtained with peak area and peak onset temperature of the adulteration peak would be more accurate for prediction of LS content in CaO based on the highest coefficient of determination (R(2) value) and smallest standard error.
    Matched MeSH terms: Crystallization
  13. Natasha AN, Sopyan I, Mel M, Ramesh S
    Med J Malaysia, 2008 Jul;63 Suppl A:85-6.
    PMID: 19024996
    The effect of Manganese (Mn) addition on the Vickers hardness and relative density of nanocrystalline hydroxyapatite (HA) dense bodies were studied. The starting Mn doped HA powders was synthesized via sol-gel method with Mn concentration varies from 2 mol% up to 15 mol% Mn. The Mn doped HA disc samples were prepared by uniaxial pressing at 200MPa and subsequently sintered at 1300 degrees C. Characterization was carried out where appropriate to determine the phases present, bulk density, Vickers hardness of the various content of Mn doped HA dense bodies. The addition of Mn was observed to influence the color appearance of the powders and dense bodies as well. Higher Mn concentration resulted in dark grey powders. It was also found that the hardness and relative density of the material increased as the Mn content increased and influenced by the crystallinity of the prepared Mn doped HA powders.
    Matched MeSH terms: Crystallization
  14. Mohamad Aris SN, Thean Chor AL, Mohamad Ali MS, Basri M, Salleh AB, Raja Abd Rahman RN
    Biomed Res Int, 2014;2014:904381.
    PMID: 24516857 DOI: 10.1155/2014/904381
    Three-dimensional structure of thermostable lipase is much sought after nowadays as it is important for industrial application mainly found in the food, detergent, and pharmaceutical sectors. Crystallization utilizing the counter diffusion method in space was performed with the aim to obtain high resolution diffracting crystals with better internal order to improve the accuracy of the structure. Thermostable T1 lipase enzyme has been crystallized in laboratory on earth and also under microgravity condition aboard Progress spacecraft to the ISS in collaboration with JAXA (Japanese Aerospace Exploration Agency). This study is conducted with the aims of improving crystal packing and structure resolution. The diffraction data set for ground grown crystal was collected to 1.3 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a = 117.40 Å, b = 80.95 Å, and c = 99.81 Å, whereas the diffraction data set for space grown crystal was collected to 1.1 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a = 117.31 Å, b = 80.85 Å, and c = 99.81 Å. The major difference between the two crystal growth systems is the lack of convection and sedimentation in microgravity environment resulted in the growth of much higher quality crystals of T1 lipase.
    Matched MeSH terms: Crystallization
  15. Sopyan I, Rosli A, Raihana MF
    Med J Malaysia, 2008 Jul;63 Suppl A:81-2.
    PMID: 19024994
    A novel hydrothermal process has been developed various hydroxyapatite(HA) powder. The HA powder was investigated in different calcination temperatures over the range of 200 degrees C-800 degrees C. TG/DTA and XRD analysis revealed that at temperatures of 700-800 degrees C the decomposition processes and phase changes took place. It is due to the appearance of TCP phase substituting the HA phase. FESEM observation showed that the produced hydroxyapatite powder was extraordinarily fine with nanosize primary particles and almost evenly spherical in shaped. Its high purity proved that the powder fulfills medical requirement.
    Matched MeSH terms: Crystallization
  16. Ishak SNH, Aris SNAM, Halim KBA, Ali MSM, Leow TC, Kamarudin NHA, et al.
    Molecules, 2017 Sep 25;22(10).
    PMID: 28946656 DOI: 10.3390/molecules22101574
    Less sedimentation and convection in a microgravity environment has become a well-suited condition for growing high quality protein crystals. Thermostable T1 lipase derived from bacterium Geobacilluszalihae has been crystallized using the counter diffusion method under space and earth conditions. Preliminary study using YASARA molecular modeling structure program for both structures showed differences in number of hydrogen bond, ionic interaction, and conformation. The space-grown crystal structure contains more hydrogen bonds as compared with the earth-grown crystal structure. A molecular dynamics simulation study was used to provide insight on the fluctuations and conformational changes of both T1 lipase structures. The analysis of root mean square deviation (RMSD), radius of gyration, and root mean square fluctuation (RMSF) showed that space-grown structure is more stable than the earth-grown structure. Space-structure also showed more hydrogen bonds and ion interactions compared to the earth-grown structure. Further analysis also revealed that the space-grown structure has long-lived interactions, hence it is considered as the more stable structure. This study provides the conformational dynamics of T1 lipase crystal structure grown in space and earth condition.
    Matched MeSH terms: Crystallization
  17. Muhammad N, Man Z, Bustam MA, Mutalib MI, Wilfred CD, Rafiq S
    Appl Biochem Biotechnol, 2011 Oct;165(3-4):998-1009.
    PMID: 21720837 DOI: 10.1007/s12010-011-9315-y
    In the present work, the dissolution of bamboo biomass was tested using a number of ionic liquids synthesized in laboratory. It was observed that one of the synthesized amino acid-based ionic liquids, namely 1-ethyl-3-methylimidazolium glycinate, was capable of dissolving the biomass completely. The dissolved biomass was then regenerated using a reconstitute solvent (acetone/water) and was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results were compared to preconditioned bamboo biomass. The regenerated biomass was found to have a more homogenous macrostructure, which indicates that the crystalline form and structure of its cellulose has changed from type Ι to type ΙΙ during the dissolution and regeneration process.
    Matched MeSH terms: Crystallization
  18. Chia TS, Quah CK
    Acta Crystallogr B Struct Sci Cryst Eng Mater, 2017 Apr 01;73(Pt 2):285-295.
    PMID: 28362293 DOI: 10.1107/S2052520616019405
    Isonicotinamide-4-methoxybenzoic acid co-crystal (1), C6H6N2O·C8H8O3, is formed through slow evaporation from methanol solution and it undergoes a first-order isosymmetry (monoclinic I2/a ↔ monoclinic I2/a) structural phase transition at Tc= 142.5 (5) K, which has been confirmed by an abrupt jump of crystallographic interaxial angle β from variable-temperature single-crystal XRD and small heat hysteresis (6.25 K) in differential scanning calorimetry measurement. The three-dimensional X-ray crystal structures of (1) at the low-temperature phase (LTP) (100, 140 and 142 K) and the high-temperature phase (HTP) (143, 150, 200, 250 and 300 K) were solved and refined as a simple non-disordered model with final R[F2> 2σ(F2)] ≃ 0.05. The asymmetric unit of (1) consists of crystallographically independent 4-methoxybenzoic acid (A) and isonicotinamide (B) molecules in both enantiotropic phases. Molecule A adopts a `near-hydroxyl' conformation in which the hydroxyl and methoxy groups are positioned on the same side. Both `near-hydroxyl' and `near-carbonyl' molecular conformations possess minimum conformational energies with an energy difference of
    Matched MeSH terms: Crystallization
  19. Liu Y, Lee WJ, Tan CP, Lai OM, Wang Y, Qiu C
    Food Chem, 2022 Mar 15;372:131305.
    PMID: 34653777 DOI: 10.1016/j.foodchem.2021.131305
    High internal phase emulsions (HIPEs) show promising application in food and cosmetic industries. In this work, diacylglycerol (DAG) was applied to fabricate water-in-oil (W/O) HIPEs. DAG-based emulsion can hold 60% water and the emulsion rigidity increased with water content, indicating the water droplets acted as "active fillers". Stable HIPE with 80% water fraction was formed through the combination of 6 wt% DAG with 1 wt% polyglycerol polyricinoleate (PGPR). The addition of 1 w% kappa (κ)-carrageenan and 0.5 M NaCl greatly reduced the droplet size and enhanced emulsion rigidity, and the interfacial tension of the internal phase was reduced. Benefiting from the Pickering crystals-stabilized interface by DAG as revealed by the microscopy and enhanced elastic modulus of emulsions with the gelation agents, the HIPEs demonstrated good retaining ability for anthocyanin and β-carotene. This study provides insights for the development of W/O HIPEs to fabricate low-calories margarines, spread or cosmetic creams.
    Matched MeSH terms: Crystallization
  20. Li Z, Ying Lee Y, Wang Y, Qiu C
    Food Chem, 2023 Nov 30;427:136696.
    PMID: 37392626 DOI: 10.1016/j.foodchem.2023.136696
    Diacylglycerols (DAG) of varying chain lengths were synthesized and the acyl migrated samples with different 1,3-DAG/1,2-DAG ratios were obtained. The crystallization profile and surface adsorption differed depending on DAG structure. C12 and C14 DAGs formed small platelet- and needle-like crystals at the oil-air interface which can better reduce surface tension and pack in an ordered lamellar structure in oil. The acyl migrated DAGs with higher ratios of 1,2-DAG showed reduced crystal size and lower oil-air interfacial activity. C14 and C12 DAG oleogels exhibited higher elasticity and whipping ability with crystal shells surrounding bubbles, whereas C16 and C18 DAG oleogels had low elasticity and limited whipping ability due to the formation of aggregated needle-like crystals and loose gel network. Thus, acyl chain length dramatically influences the gelation and foaming behaviors of DAGs whereas the isomers exert little influence. This study provides basis for applying DAG of different structures in food products.
    Matched MeSH terms: Crystallization
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