Displaying publications 61 - 80 of 164 in total

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  1. Fulltext Contact angle and surface free energy of PVC and Eudragit RS 100 in binary mixture study
    Mohd Cairul Iqbal Mohd Amin, Fell, J.T.
    Jurnal Sains Kesihatan Malaysia, 2006;4(1):1-8.
    MyJurnal
    Polyvinyl chloride (PVC) and ammonio methacrylate copolymer (Eudragit RS 100) were used as models in binary mixture tablets of direct compression study. Eudragit RS 100 is a copolymer synthesized from acrylic and methacrylic acid esters with a low content of quaternary ammonium groups. Combination of PVC and Eudragit RS 100 of different polarities and knowing the surface free energy values allow the possibility of predicting the tensile strength of the tablets. Specimens of 500 mg in the form of thin plates (25 mm x 12.5 mm), were made by compressing each powder at 20 000 MP a compression pressure using a special punch and die set. A Howden Universal Testing Machine was used to compress the powder. Contact angle measurements of the samples were carried out using a Wilhelmy balance, ran by a Cahn Dynamic Contact Angle Machine while different test liquids media such as water, glycerol, formamide and PEG 200 were used in the study. The surface free energy values of the solid materials were calculated using Wu's equation. The results showed large differences between the advancing and receding contact angle values for both materials when tested with glycerol: PVC (0) and PVC (0,) were 93.2 and 65.24 while Eudragit RS 100 (0) and Eudragit RS 100 (0) were 94.56 and 68.18 respectively. The surface free energy values for PVC using PEG 200-glycerol liquid pair were Is: 38.01, ysci: 33.42, ysP: 4.59 and for Eudragit RS 100 using formamide-glycerol liquid pair were ys: 75.03, yd: 51.66, ysP : 23.37, respectively. The results showed harder solid material like Eudragit RS 100 had higher surface free energy compared to elastic material like PVC.
    Matched MeSH terms: Glycerol
  2. Fulltext Bioconversion of glycerol for bioethanol production using isolated Escherichia coli ss1
    Suhaimi SN, Phang LY, Maeda T, Abd-Aziz S, Wakisaka M, Shirai Y, et al.
    Braz J Microbiol, 2012 Apr;43(2):506-16.
    PMID: 24031858 DOI: 10.1590/S1517-83822012000200011
    Bioconverting glycerol into various valuable products is one of glycerol's promising applications due to its high availability at low cost and the existence of many glycerol-utilizing microorganisms. Bioethanol and biohydrogen, which are types of renewable fuels, are two examples of bioconverted products. The objectives of this study were to evaluate ethanol production from different media by local microorganism isolates and compare the ethanol fermentation profile of the selected strains to use of glucose or glycerol as sole carbon sources. The ethanol fermentations by six isolates were evaluated after a preliminary screening process. Strain named SS1 produced the highest ethanol yield of 1.0 mol: 1.0 mol glycerol and was identified as Escherichia coli SS1 Also, this isolated strain showed a higher affinity to glycerol than glucose for bioethanol production.
    Matched MeSH terms: Glycerol
  3. Effect of plasticizer type and concentration on physical properties of biodegradable films based on sugar palm (arenga pinnata) starch for food packaging
    Sanyang ML, Sapuan SM, Jawaid M, Ishak MR, Sahari J
    J Food Sci Technol, 2016 Jan;53(1):326-36.
    PMID: 26787952 DOI: 10.1007/s13197-015-2009-7
    In this study, sugar palm starch (SPS) films were developed using glycerol (G), sorbitol (S) or their combination (GS) as plasticizers at the ratio of 15, 30 and 45 (wt)% using casting technique. The addition of plasticizers to SPS film-forming solutions helped to overcome the brittle and fragile nature of unplasticized SPS films. Increased plasticizer concentration resulted to an increase in film thickness, moisture content and solubility. On the contrary, density and water absorption of plasticized films decreased with increasing plasticizer concentration. Raising the plasticizer content from 15 to 45 % showed less effect on the moisture content and water absorption of S-plasticized films. Films containing glycerol and glycerol-sorbitol plasticizer (G, and GS) demonstrated higher moisture content, solubility and water absorption capacity compared to S-plasticized films. The results obtained in this study showed that plasticizer type and concentration significantly improves film properties and enhances their suitability for food packaging applications.
    Matched MeSH terms: Glycerol
  4. Unusual poly(3-hydroxyalkanoate) (PHA) biosynthesis behavior of Pseudomonas putida Bet001 and Delftia tsuruhatensis Bet002 isolated from palm oil mill effluent
    Razaif-Mazinah MRM, Anis SNS, Harun HI, Rashid KA, Annuar MSM
    Biotechnol Appl Biochem, 2017 Mar;64(2):259-269.
    PMID: 26800648 DOI: 10.1002/bab.1482
    Pseudomonas putida Bet001 and Delftia tsuruhatensis Bet002, isolated from palm oil mill effluent, accumulated poly(3-hydroxyalkanoates) (PHAs) when grown on aliphatic fatty acids, sugars, and glycerol. The substrates were supplied at 20:1 C/N mole ratio. Among C-even n-alkanoic acids, myristic acid gave the highest PHA content 26 and 28 wt% in P. putida and D. tsuruhatensis, respectively. Among C-odd n-alkanoic acids, undecanoic gave the highest PHA content at 40 wt% in P. putida and 46 wt% in D. tsuruhatensis on pentadecanoic acid. Sugar and glycerol gave <10 wt% of PHA content for both bacteria. Interestingly, D. tsuruhatensis accumulated both short- and medium-chain length PHA when supplied with n-alkanoic acids ranging from octanoic to lauric, sucrose, and glycerol with 3-hydroxybutyrate as the major monomer unit. In P. putida, the major hydroxyalkanoates unit was 3-hydroxyoctanoate and 3-hydroxydecanoate when grown on C-even acids. Conversely, 3-hydroxyheptanoate, 3-hydrxoynonanoate, and 3-hydroxyundecanoate were accumulated with C-odd acids. Weight-averaged molecular weight (Mw ) was in the range of 53-81 kDa and 107-415 kDa for P. putida and D. tsuruhatensis, respectively. Calorimetric analyses indicated that both bacteria synthesized semicrystalline polymer with good thermal stability with degradation temperature (Td ) ranging from 178 to 282 °C.
    Matched MeSH terms: Glycerol
  5. Fulltext One-Step Partially Purified Lipases (ScLipA and ScLipB) from Schizophyllum commune UTARA1 Obtained via Solid State Fermentation and Their Applications
    Kam YC, Woo KK, Ong LGA
    Molecules, 2017 Dec 08;22(12).
    PMID: 29292721 DOI: 10.3390/molecules22122106
    Lipases with unique characteristics are of value in industrial applications, especially those targeting cost-effectiveness and less downstream processes. The aims of this research were to: (i) optimize the fermentation parameters via solid state fermentation (SSF); and (ii) study the performance in hydrolysis and esterification processes of the one-step partially purified Schizophyllum commune UTARA1 lipases. Lipase was produced by cultivating S. commune UTARA1 on sugarcane bagasse (SB) with used cooking oil (UCO) via SSF and its production was optimized using Design-Expert® 7.0.0. Fractions 30% (ScLipA) and 70% (ScLipB) which contained high lipase activity were obtained by stepwise (NH₄)₂SO₄ precipitation. Crude fish oil, coconut oil and butter were used to investigate the lipase hydrolysis capabilities by a free glycerol assay. Results showed that ScLipA has affinities for long, medium and short chain triglycerides, as all the oils investigated were degraded, whereas ScLipB has affinities for long chain triglycerides as it only degrades crude fish oil. During esterification, ScLipA was able to synthesize trilaurin and triacetin. Conversely, ScLipB was specific towards the formation of 2-mono-olein and triacetin. From the results obtained, it was determined that ScLipA and ScLipB are sn-2 regioselective lipases. Hence, the one-step partial purification strategy proved to be feasible for partial purification of S. commune UTARA1 lipases that has potential use in industrial applications.
    Matched MeSH terms: Glycerol/chemistry
  6. Fulltext Histological and mechanical evaluation of antifreeze peptide (Afp1m) cryopreserved skin grafts post transplantation in a rat model
    Ibrahim SM, Kareem OH, Saffanah KM, Adamu AA, Khan MS, Rahman MBA, et al.
    Cryobiology, 2018 06;82:27-36.
    PMID: 29679551 DOI: 10.1016/j.cryobiol.2018.04.012
    The objective of this study was to evaluate the use of Afp1m as a cryopreservative agent for skin by examining the transplanted skin histological architecture and mechanical properties following subzero cryopreservation. Thirty four (34) rats with an average weight of 208 ± 31 g (mean ± SD), were used. Twenty four (n = 24) rats were equally divided into four groups: (i) immediate non-cryopreserved skin autografts (onto same site), (ii) immediate non-cryopreserved skin autografts (onto different sites), (iii) skin autografts cryopreserved with glycerol for 72 h and (iv) skin autografts cryopreserved with Afp1m for 72 h at -4 °C. Rounded shaped full-thickness 1.5-2.5 cm in diameter skin was excised from backs of rats for the autograft transplantation. Non-cryopreserved or cryopreserved auto skin graft were positioned onto the wound defects and stitched. Non-transplanted cryopreserved and non-cryopreserved skin strips from other ten rats (n = 10) were allowed for comparative biomechanical test. All skin grafts were subjected to histological and mechanical examinations at the end of day 21. Histological results revealed that tissue architecture especially the epidermal integrity and dermal-epidermal junction of the Afp1m cryopreserved skin grafts exhibited better histological appearance, good preservation of tissue architecture and structural integrity than glycerolized skin. However, there was no significant difference among these groups in other histological criteria. There were no significant differences among the 4 groups in skin graft mechanical properties namely maximum load. In conclusion, Afp1m were found to be able to preserve the microstructure as well as the viability and function of the skin destined for skin transplantation when was kept at -4 °C for 72 h.
    Matched MeSH terms: Glycerol/pharmacology*
  7. Development of a PVS2 droplet-vitrification cryopreservation technique for Aranda Broga Blue orchid protocorm-like bodies (PLBs)
    Ping KS, Poobathy RR, Zakaria R, Subramaniam S
    Cryo Letters, 2018 5 8;38(4):290-298.
    PMID: 29734430
    　　BACKGROUND: Conservation of commercially important ornamental plants is important to maintain its unique beauty to cater the market demands.

    OBJECTIVE: The main objective is to develop an efficient cryopreservation technique for Aranda Broga Blue orchid PLBs using droplet-vitrification method.

    MATERIALS AND METHODS: Several critical factors in cryopreservation were accessed such as preculture concentrations and durations, choice of vitrification solutions, two-step or three-step vitrification, growth recovery medium and PVS2 exposure duration.

    RESULTS: The best growth regeneration percentage (5%) was obtained when 3-4mm PLBs were precultured in 0.2M sucrose for 3 days, followed by osmoprotection for 20 minutes, dehydration in PVS2 for 20 minutes at 0 degree C, LN storage, thawed and unloading for 20 minutes, and growth regeneration in VW10 medium. PLBs were found to be very sensitive to osmotic stress imposed by high molecular weight cryoprotectant such as sucrose and glycerol. Osmotic potential of growth recovery medium is one of the main factors that affect growth recovery in cryopreserved PLBs.

    CONCLUSION: Current report showed possibilities in cryopreserving Aranda Broga Blue PLBs using droplet-vitrification technique. However, further improvement of growth recovery can be done by focussing on approaches that facilitate sufficient water removal from PLBs without causing severe osmotic injuries to the plant cells.

    Matched MeSH terms: Glycerol/pharmacology
  8. Effect of disaccharide-polyol systems on the thermal stability of freeze-dried Mycobacterium bovis
    Tan YZ, Chong YQ, Khong E, Liew YK, Chieng N
    Int J Pharm, 2019 Jul 20;566:400-409.
    PMID: 31136777 DOI: 10.1016/j.ijpharm.2019.05.063
    Live attenuated Mycobacterium bovis (M. bovis), marketed as Bacille Calmette-Guérin is the only FDA-approved vaccine against tuberculosis. The prerequisite of cold chain storage between 2 and 8 °C hinders the global vaccination effort. The study aims to investigate the effect of trehalose, sucrose and glycerol combinations in enhancing the stability of M. bovis. The bacilli were formulated in various ratios of trehalose-glycerol, sucrose-glycerol, trehalose-sucrose-glycerol systems (test samples) and sodium glutamate (control), freeze-dried and stored for 28 days at 4 °C, 25 °C and 37 °C. Bacteria viability at pre-, post-freeze-drying and after storage were quantified by its density in colony-forming unit per milliliter (CFU/mL) as obtained through the pour plate method. Formulations were characterized using differential scanning calorimetry. Structural collapsed cakes were found on all freeze-dried formulations because of the low Tg'. Comparing between binary and ternary formulations, trehalose-sucrose-glycerol was found to be a superior lyoprotectant. Upon storage, the viability of bacteria in disaccharide-polyol formulations was highest when stored at 4 °C followed by 25 °C. The lowest viability was found after storage at 37 °C. While the ternary disaccharide-polyol system may be used as a thermoprotectant up to 25 °C, sodium glutamate has a superior thermoprotective effect at temperature above 25 °C.
    Matched MeSH terms: Glycerol/administration & dosage*
  9. Improved lovastatin production by inhibiting (+)-geodin biosynthesis in Aspergillus terreus
    Hasan H, Abd Rahim MH, Campbell L, Carter D, Abbas A, Montoya A
    N Biotechnol, 2019 Sep 25;52:19-24.
    PMID: 30995533 DOI: 10.1016/j.nbt.2019.04.003
    Lovastatin is widely prescribed to reduce elevated levels of cholesterol and prevent heart-related diseases. Cultivation of Aspergillus terreus (ATCC 20542) with carbohydrates or low-value feedstocks such as glycerol produces lovastatin as a secondary metabolite and (+)-geodin as a by-product. An A. terreus mutant strain was developed (gedCΔ) with a disrupted (+)-geodin biosynthesis pathway. The gedCΔ mutant was created by inserting the antibiotic marker hygromycin B (hyg) within the gedC gene that encodes emodin anthrone polyketide synthase (PKS), a primary gene responsible for initiating (+)-geodin biosynthesis. The effects of emodin anthrone PKS gene disruption on (+)-geodin and lovastatin biosynthesis and the production of the precursors acetyl-CoA and malonyl-CoA were investigated with cultures based on glycerol alone and in combination with lactose. The gedCΔ strain showed improved lovastatin production, particularly when cultivated on the glycerol-lactose mixture, increasing lovastatin production by 80% (113 mg/L) while simultaneously inhibiting (+)-geodin biosynthesis compared to the wild-type strain. This study thus shows that suppression of the (+)-geodin pathway increases lovastatin yield and demonstrates a practical approach of manipulating carbon flux by modulating enzyme activity.
    Matched MeSH terms: Glycerol/metabolism
  10. Utilization of waste fish oil and glycerol as carbon sources for polyhydroxyalkanoate production by Salinivibrio sp. M318
    Van Thuoc D, My DN, Loan TT, Sudesh K
    Int J Biol Macromol, 2019 Dec 01;141:885-892.
    PMID: 31513855 DOI: 10.1016/j.ijbiomac.2019.09.063
    A moderately halophilic bacterium isolated from fermenting shrimp paste, Salinivibrio sp. M318 was found capable of using fish sauce and mixtures of waste fish oil and glycerol as nitrogen and carbon sources, respectively, for poly(3-hydroxybutyrate) (PHB) production. A cell dry weight (CDW) of up to 10 g/L and PHB content of 51.7 wt% were obtained after 48 h of cultivation in flask experiment. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] was synthesized when 1,4-butanediol, γ-butyrolactone, or sodium 4-hydroxybutyrate was added as precursors to the culture medium. The biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was achieved by supplying precursors such as sodium valerate, sodium propionate, and sodium heptanoate. Salinivibrio sp. M318 was able to accumulate the above mentioned PHAs during the growth phase. High CDW of 69.1 g/L and PHB content of 51.5 wt% were obtained by strain Salinivibrio sp. M318 after 78 h of cultivation in fed-batch culture. The results demonstrate Salinivibrio sp. M318 to be a promising wild-type bacterium for the production of PHA from aquaculture residues.
    Matched MeSH terms: Glycerol/chemistry*
  11. Fulltext The Study of Electrical and Electrochemical Properties of Magnesium Ion Conducting CS: PVA Based Polymer Blend Electrolytes: Role of Lattice Energy of Magnesium Salts on EDLC Performance
    Aziz SB, Brza MA, Hamsan EMADMH, Hadi JM, Kadir MFZ, Abdulwahid RT
    Molecules, 2020 Oct 01;25(19).
    PMID: 33019618 DOI: 10.3390/molecules25194503
    Plasticized magnesium ion conducting polymer blend electrolytes based on chitosan (CS): polyvinyl alcohol (PVA) was synthesized with a casting technique. The source of ions is magnesium triflate Mg(CF3SO3)2, and glycerol was used as a plasticizer. The electrical and electrochemical characteristics were examined. The outcome from X-ray diffraction (XRD) examination illustrates that the electrolyte with highest conductivity exhibits the minimum degree of crystallinity. The study of the dielectric relaxation has shown that the peak appearance obeys the non-Debye type of relaxation process. An enhancement in conductivity of ions of the electrolyte system was achieved by insertion of glycerol. The total conductivity is essentially ascribed to ions instead of electrons. The maximum DC ionic conductivity was measured to be 1.016 × 10-5 S cm-1 when 42 wt.% of plasticizer was added. Potential stability of the highest conducting electrolyte was found to be 2.4 V. The cyclic voltammetry (CV) response shows the behavior of the capacitor is non-Faradaic where no redox peaks appear. The shape of the CV response and EDLC specific capacitance are influenced by the scan rate. The specific capacitance values were 7.41 F/g and 32.69 F/g at 100 mV/s and 10 mV/s, respectively. Finally, the electrolyte with maximum conductivity value is obtained and used as electrodes separator in the electrochemical double-layer capacitor (EDLC) applications. The role of lattice energy of magnesium salts in energy storage performance is discussed in detail.
    Matched MeSH terms: Glycerol/chemistry
  12. Response surface methodology optimization of polyhydroxyalkanoate production by Burkholderia cepacia BPT1213 using waste glycerol from palm oil-based biodiesel production
    Mohd Zain NF, Paramasivam M, Tan JS, Lim V, Lee CK
    Biotechnol Prog, 2021 01;37(1):e3077.
    PMID: 32894656 DOI: 10.1002/btpr.3077
    The feasibility of using waste glycerol from the biodiesel industry for biosynthesis of polyhydroxyalkanoate (PHA) by Burkholderia cepacia BPT1213 was evaluated. Culture conditions were optimized by growing B. cepacia BPT1213 in mineral salt medium supplemented with 2% waste glycerol in a 2.5 L bioreactor. Response surface methodology was used to determine the influence of aeration rate (0.6-1.8 vvm), agitation speed (100-300 rpm), and cultivation period (48-72 hr) on PHA production. The optimum conditions for the growth and PHA accumulation were 1.5 vvm, 300 rpm, and 72 hr, with predicted values of 5.08 g/L cell dry weight (CDW), 66.07% PHA content, and 3.35 g/L total PHA concentration. Using these conditions, the experimental system produced 5.63 g/L of CDW with 64.00% wt/wt PHA content, which is threefold higher PHA concentration (3.60 g/L) compared to the non-optimized conditions. The melting temperature (Tm ) of purified PHA was 173.45 ± 1.05°C. In conclusion, the statistical approach was significantly increased the PHA production using waste glycerol as the sole carbon source.
    Matched MeSH terms: Glycerol/chemistry*
  13. Cryopreservation of Citrus madurensis zygotic embryonic axes by vitrification: importance of pregrowth and preculture conditions
    Cho EG, Hor YL, Kim HH, Rao VR, Engelmann F
    Cryo Letters, 2001 Nov-Dec;22(6):391-6.
    PMID: 11788881
    The role of pregrowth and preculture treatments in terms of both medium composition and exposure duration on survival of embryonic axes of Citrus madurensis after cryopreservation using the vitrification procedure was investigated. The optimal pregrowth treatment for excised embryonic axes was a 3-day treatment with 0.1M sucrose. Preculture was also essential in increasing survival after cryopreservation. Among the various media and treatment durations evaluated, a 24h-preculture of embryonic axes on medium with 0.3M sucrose and 0.5M glycerol was found to be optimal. Using these pregrowth and preculture conditions followed by treatment at 25 degrees C for 20 min each with a loading solution (0.4M sucrose + 2.0M glycerol) and then the PVS2 vitrification solution, direct immersion in liquid nitrogen, rapid rewarming, unloading in a 1.2M sucrose solution for 20 min and transfer of embryonic axes on recovery medium, 82.5% survival and regrowth without intermediary callus formation were obtained with C. madurensis embryonic axes.
    Matched MeSH terms: Glycerol/pharmacology
  14. Liquid chromatographic detection of Dowtherm A contamination in oleochemicals and edible oils
    Moh FM, Tang TS
    J AOAC Int, 1999 8 13;82(4):893-6.
    PMID: 10444829
    A rapid and direct liquid chromatographic (LC) technique is described for the determination of a eutectic mixture of diphenyl oxide and biphenyl such as Dowtherm A thermal heating fluid (THF) in oleochemicals and palm olein. Analysis is performed with an RP-18 column with fluorescence detection (excitation at 247 nm and emission at 310 nm). The isocratic mobile phase (1.0 mL/min) consists of methanol and water (90 + 10, v/v). A linear calibration model (correlation coefficient = 0.9999) was developed directly from used Dowtherm A THF with the biphenyl peak (4.70 min) as a marker. Average recoveries from spiked glycerin, fatty alcohol mixture, methyl ester mixture, fatty acids, and palm olein were 90.9-108.7%, with a detection limit of 0.1 microgram/mL. The technique requires no prior sample cleanup nor extraction steps and is good for quality assurance purposes.
    Matched MeSH terms: Glycerol/analysis
  15. Enhanced removal of lead from contaminated soil by polyol-based deep eutectic solvents and saponin
    Mukhopadhyay S, Mukherjee S, Hayyan A, Hayyan M, Hashim MA, Sen Gupta B
    J Contam Hydrol, 2016 Nov;194:17-23.
    PMID: 27697607 DOI: 10.1016/j.jconhyd.2016.09.007
    Deep eutectic solvents (DESs) are a class of green solvents analogous to ionic liquids, but less costly and easier to prepare. The objective of this study is to remove lead (Pb) from a contaminated soil by using polyol based DESs mixed with a natural surfactant saponin for the first time. The DESs used in this study were prepared by mixing a quaternary ammonium salt choline chloride with polyols e.g. glycerol and ethylene glycol. A natural surfactant saponin obtained from soapnut fruit pericarp, was mixed with DESs to boost their efficiency. The DESs on their own did not perform satisfactory due to higher pH; however, they improved the performance of soapnut by up to 100%. Pb removal from contaminated soil using mixture of 40% DES-Gly and 1% saponin and mixture of 10% DES-Gly and 2% saponin were above 72% XRD and SEM studies did not detect any major corrosion in the soil texture. The environmental friendliness of both DESs and saponin and their affordable costs merit thorough investigation of their potential as soil washing agents.
    Matched MeSH terms: Glycerol/chemistry
  16. Fulltext Choline Chloride-urea Deep Eutectic Mixture Water for the Synthesis of an Amphiphilic Compound of Glyceryl Monocaffeate
    Gonawan FN, Bakar PNMA, Kamaruddin AH
    J Oleo Sci, 2021 Oct 05;70(10):1437-1445.
    PMID: 34497176 DOI: 10.5650/jos.ess21010
    The Lipase-catalyzed synthesis of glyceryl monocaffeate (GMC) in choline chloride-urea of natural deep eutectic solvent (NADES) media is reported to provide amphiphilic character to caffeic acid (CA). The modification of CA into GMC could potentially increase its solubility and widen the application of CA's biological activities in water and oil-based systems. The high conversion was achieved when the reaction was carried out with the addition of more than 20 %v/v water, at a high molar ratio of glycerol and 40°C. It was found that the lipase-catalyzed transesterification of ethyl caffeate (EC) and glycerol in choline chloride-urea of DES media obeyed ping-pong bi-bi mechanism with Vmax = 10.9 mmol.min-1, KmEC = 126.5 mmol and KmGly = 1842.7 mmol.
    Matched MeSH terms: Glycerol/chemical synthesis*
  17. Synthesis of oxygenated fuel additives via the solventless etherification of glycerol
    Ayoub M, Khayoon MS, Abdullah AZ
    Bioresour Technol, 2012 May;112:308-12.
    PMID: 22437049 DOI: 10.1016/j.biortech.2012.02.103
    The synthesis of oxygenated fuel additives via solvent freebase-catalyzed etherification of glycerol is reported. The products of glycerol etherification arediglycerol (DG) and triglycerol (TG) with DG being the favorable one. The catalytic activity of different homogeneous alkali catalysts (LiOH, NaOH, KOH and Na(2)CO(3)) was investigated during the glycerol etherification process. LiOH exhibited an excellent catalytic activity during this reaction, indicated by the complete glycerol conversion with a corresponding selectivity of 33% toward DG. The best reaction conditions were a reaction temperature of 240°C, a catalyst/glycerol mass ratio of 0.02 and a reaction time of 6h. The influences of various reaction variables such as nature of the catalyst, catalyst loading, reaction time and reaction temperature on glycerol etherification were elucidated. Industrially, the findings attained in this study might contribute towards promoting the biodiesel industry through utilization of its by-products.
    Matched MeSH terms: Glycerol/chemistry*
  18. Fulltext Optimization of sunflower oil transesterification process using sodium methoxide
    KoohiKamali S, Tan CP, Ling TC
    ScientificWorldJournal, 2012;2012:475027.
    PMID: 22593688 DOI: 10.1100/2012/475027
    In this study, the methanolysis process of sunflower oil was investigated to get high methyl esters (biodiesel) content using sodium methoxide. To reach to the best process conditions, central composite design (CCD) through response surface methodology (RSM) was employed. The optimal conditions predicted were the reaction time of 60 min, an excess stoichiometric amount of alcohol to oil ratio of 25%w/w and the catalyst content of 0.5%w/w, which lead to the highest methyl ester content (100%w/w). The methyl ester content of the mixture from gas chromatography analysis (GC) was compared to that of optimum point. Results, confirmed that there was no significant difference between the fatty acid methyl ester content of sunflower oil produced under the optimized condition and the experimental value (P ≥ 0.05). Furthermore, some fuel specifications of the resultant biodiesel were tested according to American standards for testing of materials (ASTM) methods. The outcome showed that the methyl ester mixture produced from the optimized condition met nearly most of the important biodiesel specifications recommended in ASTM D 6751 requirements. Thus, the sunflower oil methyl esters resulted from this study could be a suitable alternative for petrol diesels.
    Matched MeSH terms: Glycerol/metabolism
  19. Fulltext Improved photodynamic efficacy of Zn(II) phthalocyanines via glycerol substitution
    Chin Y, Lim SH, Zorlu Y, Ahsen V, Kiew LV, Chung LY, et al.
    PLoS One, 2014;9(5):e97894.
    PMID: 24840576 DOI: 10.1371/journal.pone.0097894
    Phthalocyanines are excellent photosensitizers for photodynamic therapy as they have strong absorbance in the near infra-red region which is most relevant for in vivo activation in deeper tissular regions. However, most phthalocyanines present two major challenges, ie, a strong tendency to aggregate and low water-solubility, limiting their effective usage clinically. In the present study, we evaluated the potential enhancement capability of glycerol substitution on the photodynamic properties of zinc (II) phthalocyanines (ZnPc). Three glycerol substituted ZnPc, 1-3, (tetra peripherally, tetra non-peripherally and mono iodinated tri non-peripherally respectively) were evaluated in terms of their spectroscopic properties, rate of singlet oxygen generation, partition coefficient (log P), intracellular uptake, photo-induced cytotoxicity and vascular occlusion efficiency. Tetrasulfonated ZnPc (ZnPcS4) was included as a reference compound. Here, we showed that 1-3 exhibited 10-100 nm red-shifted absorption peaks with higher molar absorptivity, and at least two-fold greater singlet oxygen generation rates compared to ZnPcS4. Meanwhile, phthalocyanines 1 and 2 showed more hydrophilic log P values than 3 consistent with the number of glycerol attachments but 3 was most readily taken up by cells compared to the rest. Both phthalocyanines 2 and 3 exhibited potent phototoxicity against MCF-7, HCT-116 and HSC-2 cancer cell-lines with IC50 ranging 2.8-3.2 µM and 0.04-0.06 µM respectively, while 1 and ZnPcS4 (up to 100 µM) failed to yield determinable IC50 values. In terms of vascular occlusion efficiency, phthalocyanine 3 showed better effects than 2 by causing total occlusion of vessels with diameter <70 µm of the chorioallantoic membrane. Meanwhile, no detectable vascular occlusion was observed for ZnPcS4 with treatment under similar experimental conditions. These findings provide evidence that glycerol substitution, in particular in structures 2 and 3, is able to improve the photodynamic properties of ZnPc.
    Matched MeSH terms: Glycerol/chemistry*
  20. Scanning electron microscopic assessment on surface morphology of preserved human amniotic membrane after gamma sterilisation
    Ab Hamid SS, Zahari NK, Yusof N, Hassan A
    Cell Tissue Bank, 2014 Mar;15(1):15-24.
    PMID: 23187886 DOI: 10.1007/s10561-012-9353-x
    Human amniotic membrane that has been processed and sterilised by gamma irradiation is widely used as a biological dressing in surgical applications. The morphological structure of human amniotic membrane was studied under scanning electron microscopy (SEM) to assess effects of gamma radiation on human amniotic membrane following different preservation methods. The amniotic membrane was preserved by either air drying or submerged in glycerol before gamma irradiated at 15, 25 and 35 kGy. Fresh human amniotic membrane, neither preserved nor irradiated was used as the control. The surface morphology of glycerol preserved amnion was found comparable to the fresh amniotic membrane. The cells of the glycerol preserved was beautifully arranged, homogonous in size and tended to round up. The cell structure in the air dried preserved amnion seemed to be flattened and dehydrated. The effects of dehydration on intercellular channels and the microvilli on the cell surface were clearly seen at higher magnifications (10,000×). SEM revealed that the changes of the cell morphology of the glycerol preserved amnion were visible at 35 kGy while the air dried already changed at 25 kGy. Glycerol preservation method is recommended for human amniotic membrane as the cell morphological structure is maintained and radiation doses lower than 25 kGy for sterilization did not affect the appearance of the preserved amnion.
    Matched MeSH terms: Glycerol/pharmacology
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