Displaying publications 221 - 240 of 10666 in total

Abstract:
Sort:
  1. Antioxidants from tropical herbs
    Razab R, Abdul-Aziz A
    Nat Prod Commun, 2010 Mar;5(3):441-5.
    PMID: 20420325
    Plants that contain high amounts of polyphenolic compounds are potential candidates for natural antioxidant sources. Studies are on going in the search for new sources of antioxidants. Not much data are available on the antioxidant capacity of tropical herbs. With this in mind, 19 commonly consumed Malaysian herbs were analyzed for their polyphenolic content and antioxidant activities. A majority of these plants have never been studied before with regards to their polyphenolic content and antioxidant activities. The shoots of Anacardium occidentale, the shoots and fruits of Barringtonia racemosa, Pithecellobium jiringa and Parkia speciosa had high polyphenolic contents (> 150 microg gallic acid equivalents/mg dried plant) and antioxidant activities when measured using the ferric reducing antioxidant power (FRAP) (>1.2 mM) and Trolox equivalent antioxidant capacity (TEAC) assays (>2.4 mM). A strong correlation was observed between the two antioxidant assays (FRAP vs TEAC) implying that the plants could both scavenge free radicals and reduce oxidants. There was also a strong correlation between the antioxidant activities and polyphenolic content suggesting the observed antioxidant activities were contributed mainly by the polyphenolics in the plants.
    Matched MeSH terms: Antioxidants/chemistry*; Ferric Compounds/chemistry; Flavonoids/chemistry*; Fruit/chemistry; Phenols/chemistry*; Plants/chemistry*; Sulfonic Acids/chemistry; Free Radical Scavengers/chemistry; Oxidants/chemistry; Plant Shoots/chemistry; Reducing Agents/chemistry; Benzothiazoles/chemistry
  2. Fulltext Alpha-Mangostin-Rich Extracts from Mangosteen Pericarp: Optimization of Green Extraction Protocol and Evaluation of Biological Activity
    Ghasemzadeh A, Jaafar HZE, Baghdadi A, Tayebi-Meigooni A
    Molecules, 2018 Jul 25;23(8).
    PMID: 30044450 DOI: 10.3390/molecules23081852
    Since α-mangostin in mangosteen fruits was reported to be the main compound able to provide natural antioxidants, the microwave-assisted extraction process to obtain high-quality α-mangostin from mangosteen pericarp (Garcinia mangostana L.) was optimized using a central composite design and response surface methodology. The parameters examined included extraction time, microwave power, and solvent percentage. The antioxidant and antimicrobial activity of optimized and non-optimized extracts was evaluated. Ethyl acetate as a green solvent exhibited the highest concentration of α-mangostin, followed by dichloromethane, ethanol, and water. The highest α-mangostin concentration in mangosteen pericarp of 121.01 mg/g dry matter (DM) was predicted at 3.16 min, 189.20 W, and 72.40% (v/v). The verification of experimental results under these optimized conditions showed that the α-mangostin value for the mangosteen pericarp was 120.68 mg/g DM. The predicted models were successfully developed to extract α-mangostin from the mangosteen pericarp. No significant differences were observed between the predicted and the experimental α-mangostin values, indicating that the developed models are accurate. The analysis of the extracts for secondary metabolites showed that the total phenolic content (TPC) and total flavonoid content (TFC) increased significantly in the optimized extracts (OE) compared to the non-optimized extracts (NOE). Additionally, trans-ferulic acid and catechin were abundant among the compounds identified. In addition, the optimized extract of mangosteen pericarp with its higher α-mangostin and secondary metabolite concentrations exhibited higher antioxidant activities with half maximal inhibitory concentration (IC50) values of 20.64 µg/mL compared to those of the NOE (28.50 µg/mL). The OE exhibited the highest antibacterial activity, particularly against Gram-positive bacteria. In this study, the microwave-assisted extraction process of α-mangostin from mangosteen pericarp was successfully optimized, indicating the accuracy of the models developed, which will be usable in a larger-scale extraction process.
    Matched MeSH terms: Anti-Bacterial Agents/chemistry*; Antioxidants/chemistry*; Catechin/chemistry; Coumaric Acids/chemistry; Flavonoids/chemistry; Fruit/chemistry; Phenols/chemistry; Plant Extracts/chemistry*; Garcinia mangostana/chemistry*; Xanthones/chemistry*; Green Chemistry Technology/methods*
  3. Fulltext Characterization and in vitro drug release studies of a natural polysaccharide Terminalia catappa gum (Badam gum)
    Meka VS, Nali SR, Songa AS, Kolapalli VR
    AAPS PharmSciTech, 2012 Dec;13(4):1451-64.
    PMID: 23090110 DOI: 10.1208/s12249-012-9873-5
    The main objective of the present study is the physicochemical characterization of naturally available Terminalia catappa gum (Badam gum [BG]) as a novel pharmaceutical excipient and its suitability in the development of gastroretentive floating drug delivery systems (GRFDDS) to retard the drug for 12 h when the dosage form is exposed to gastrointestinal fluids in the gastric environment. As BG was being explored for the first time for its pharmaceutical application, physicochemical, microbiological, rheological, and stability studies were carried out on this gum. In the present investigation, the physicochemical properties, such as micromeritic, rheological, melting point, moisture content, pH, swelling index, water absorption, and volatile acidity, were evaluated. The gum was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), powder X-ray diffraction studies (PXRD), and Fourier transform infrared spectroscopy (FTIR). Gastroretentive floating tablets of BG were prepared with the model drug propranolol HCl by direct compression methods. The prepared tablets were evaluated for all their physicochemical properties, in vitro buoyancy, in vitro drug release, and rate order kinetics. PBG 04 was selected as an optimized formulation based on its 12-h drug release and good buoyancy characteristics. The optimized formulation was characterized with FTIR, DSC, and PXRD studies, and no interaction between the drug and BG was found. Thus, the study confirmed that BG might be used in the gastroretentive drug delivery system as a release-retarding polymer.
    Matched MeSH terms: Chemistry, Pharmaceutical/methods; Excipients/chemistry*; Gastrointestinal Agents/chemistry; Gingiva/chemistry*; Polymers/chemistry; Polysaccharides/chemistry*; Powders/chemistry; Propranolol/chemistry; Tablets/chemistry; Water/chemistry; Terminalia/chemistry*
  4. Effect of Room Temperature Ionic Liquid on the Formation of the Complex Oxalate-Sodium Morin-5-Sulfonate-Aluminium(III): Application to the Fluorescence Determination of Oxalate Ion
    Nizar SA, Mohd Suah FB
    J Fluoresc, 2016 Jul;26(4):1167-71.
    PMID: 27286697 DOI: 10.1007/s10895-016-1845-9
    The effect of room temperature ionic liquid (RTIL) on the formation of the fluorescence ternary complex oxalate-sodium morin-5-sulfonate (NaMSA)-Aluminium(III) has been studied. In weakly acidic medium and in the presence of RTIL, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), total complex formation is achieved as compared with the formation of the binary complex of NaMSA-Aluminium(III). The fluorescence characteristics of the system allowed the establishment of a very sensitive method for the spectrofluorimetric determination of oxalate ion. The ternary complex formed its highest fluorescence signal at 513 nm and excitation at 420 nm. In these conditions, the method produces a detection limit of 0.57 ng mL(-1). The procedure has been satisfactorily applied to the determination of oxalate ion in a vegetal tissue (spinach leaves).
    Matched MeSH terms: Aluminum/chemistry*; Flavonoids/chemistry*; Oxalates/chemistry*; Sulfonic Acids/chemistry*; Ionic Liquids/chemistry*
  5. Characterization of un-plasticized and propylene carbonate plasticized carboxymethyl cellulose doped ammonium chloride solid biopolymer electrolytes
    Ahmad NH, Isa MIN
    Carbohydr Polym, 2016 Feb 10;137:426-432.
    PMID: 26686147 DOI: 10.1016/j.carbpol.2015.10.092
    Two solid biopolymer electrolytes (SBEs) systems of carboxymethyl cellulose doped ammonium chloride (CMC-AC) and propylene carbonate plasticized (CMC-AC-PC) were prepared via solution casting technique. The ionic conductivity of SBEs were analyzed using electrical impedance spectroscopy (EIS) in the frequency range of 50 Hz-1 MHz at ambient temperature (303K). The highest ionic conductivity of CMC-AC SBE is 1.43 × 10(-3)S/cm for 16 wt.% of AC while the highest conductivity of plasticized SBE system is 1.01 × 10(-2)S/cm when added with 8 wt.% of PC. TGA/DSC showed that the addition of PC had increased the decomposition temperature compared of CMC-AC SBE. Fourier transform infrared (FTIR) spectra showed the occurrence of complexation between the SBE components and it is proved successfully executed by Gaussian software. X-ray diffraction (XRD) indicated that amorphous nature of SBEs. It is believed that the PC is one of the most promising plasticizer to enhance the ionic conductivity and performance for SBE system.
    Matched MeSH terms: Ammonium Chloride/chemistry*; Biopolymers/chemistry*; Carboxymethylcellulose Sodium/chemistry*; Electrolytes/chemistry*; Propane/chemistry
  6. Synthesis and characterization of Co3O4 ultra-nanosheets and Co3O4 ultra-nanosheet-Ni(OH)2 as non-enzymatic electrochemical sensors for glucose detection
    Mahmoudian MR, Basirun WJ, Woi PM, Sookhakian M, Yousefi R, Ghadimi H, et al.
    Mater Sci Eng C Mater Biol Appl, 2016 Feb;59:500-508.
    PMID: 26652401 DOI: 10.1016/j.msec.2015.10.055
    The present study examines the synthesis of Co3O4 ultra-nanosheets (Co3O4 UNSs) and Co3O4 ultra-nanosheet-Ni(OH)2 (Co3O4 UNS-Ni(OH)2) via solvothermal process and their application as non-enzymatic electrochemical sensors for glucose detection. X-ray diffraction and transmission electron microscopy results confirmed the Co3O4 UNS deposition on Ni(OH)2 surface. The presence of Co3O4 UNSs on Ni (OH) 2 surface improved the sensitivity of glucose detection, from the increase of glucose oxidation peak current at the Co3O4 UNS-Ni(OH)2/glassy carbon electrode (current density: 2000μA·cm(-2)), compared to the Co3O4 UNSs. These results confirmed that Ni(OH)2 on glassy carbon electrode is a sensitive material for glucose detection, moreover the Co3O4 UNSs can increase the interaction and detection of glucose due to their high surface area. The estimated limit of detection (S/N=3) and limit of quantification (S/N=10) of the linear segment (5-40μM) are 1.08μM and 3.60μM respectively. The reproducibility experiments confirmed the feasibility of Co3O4 UNS-Ni(OH)2 for the quantitative detection of certain concentration ranges of glucose.
    Matched MeSH terms: Cobalt/chemistry*; Hydroxides/chemistry*; Nickel/chemistry*; Oxides/chemistry*; Nanostructures/chemistry*
  7. Fulltext A novel aqueous micellar two-phase system composed of surfactant and sorbitol for purification of pectinase enzyme from Psidium guajava and recycling phase components
    Amid M, Murshid FS, Manap MY, Hussin M
    Biomed Res Int, 2015;2015:815413.
    PMID: 25756051 DOI: 10.1155/2015/815413
    A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme.
    Matched MeSH terms: Polygalacturonase/chemistry*; Sorbitol/chemistry*; Surface-Active Agents/chemistry*; Water/chemistry*; Psidium/chemistry*
  8. Characterization and solubility study of norfloxacin-polyethylene glycol, polyvinylpyrrolidone and carbopol 974p solid dispersions
    Gorajana A, Kit WW, Dua K
    Recent Pat Drug Deliv Formul, 2015;9(2):167-82.
    PMID: 25714525
    OBJECTIVE: Norfloxacin has a low aqueous solubility which leads to poor dissolution. Keeping this fact in mind the purpose of the present study is to formulate and evaluate norfloxacin solid dispersion.

    METHODS: Solid dispersions were prepared using hydrophilic carriers like polyethylene glycol (PEG) 4000, polyvinylpyrrolidone (PVP) k30 and carbopol 974pNF (CP) in various ratios using solvent evaporation technique. These formulations were evaluated using solubility studies, dissolution studies; Fourier transmitted infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetery (DSC). The influence of polymer type and drug to polymer ratio on the solubility and dissolution rate of norfloxacin was also evaluated.

    RESULTS: FTIR analysis showed no interaction of all three polymers with norfloxacin. The results from XRD and DSC analyses of the solid dispersion preparations showed that norfloxacin existsin its amorphous form. Among the Norfloxacin: PEG solid dispersions, Norfloxacin: PEG 1:14 ratio showed the highest dissolution rate at pH 6.8. For norfloxacin: PVP solid dispersions, norfloxacin: PVP 1:10 ratio showed the highest dissolution rate at pH 6.8. For Norfloxacin: CP solid dispersions, norfloxacin: P 1:2 ratio showed the highest dissolution rate at pH 6.8.

    CONCLUSION: The solid dispersion of norfloxacin with polyethylene glycol (PEG) 4000, polyvinylpyrrolidone (PVP) k30 and carbopol 974p NF (CP), lends an ample credence for better therapeutic efficacy.

    Matched MeSH terms: Acrylates/chemistry*; Chemistry, Pharmaceutical; Norfloxacin/chemistry*; Polyethylene Glycols/chemistry*; Povidone/chemistry*
  9. A review: potential usage of cellulose nanofibers (CNF) for enzyme immobilization via covalent interactions
    Sulaiman S, Mokhtar MN, Naim MN, Baharuddin AS, Sulaiman A
    Appl Biochem Biotechnol, 2015 Feb;175(4):1817-42.
    PMID: 25427594 DOI: 10.1007/s12010-014-1417-x
    Nanobiocatalysis is a new frontier of emerging nanosized material support in enzyme immobilization application. This paper is about a comprehensive review on cellulose nanofibers (CNF), including their structure, surface modification, chemical coupling for enzyme immobilization, and potential applications. The CNF surface consists of mainly -OH functional group that can be directly interacted weakly with enzyme, and its binding can be improved by surface modification and interaction of chemical coupling that forms a strong and stable covalent immobilization of enzyme. The knowledge of covalent interaction for enzyme immobilization is important to provide more efficient interaction between CNF support and enzyme molecule. Enzyme immobilization onto CNF is having potential for improving enzymatic performance and production yield, as well as contributing toward green technology and sustainable sources.
    Matched MeSH terms: Cellulose/chemistry*; Cross-Linking Reagents/chemistry; Enzymes, Immobilized/chemistry*; Green Chemistry Technology; Nanofibers/chemistry*
  10. Processing and analysis of chitosan nanocomposites reinforced with chitin whiskers and tannic acid as a crosslinker
    Rubentheren V, Ward TA, Chee CY, Tang CK
    Carbohydr Polym, 2015 Jan 22;115:379-87.
    PMID: 25439908 DOI: 10.1016/j.carbpol.2014.09.007
    Chitosan film reinforced with nano-sized chitin whiskers and crosslinked using tannic acid was synthesized by the casting-vaporation method. The mechanical and physicochemical properties of several film samples (consisting of different ratio of chitin and tannic acid) were compared with neat chitosan. Tensile tests show that the addition of chitin improves the nanocomposite films mechanical properties up to 137% compared to neat chitosan, but this is slightly degraded when tannic acid is introduced. However, tannic acid and chitin whisker content greatly reduced moisture content by 294% and water solubility by 13%. Transmission electron microscopy (TEM) and Fourier-transform-infrared spectroscopy (FTIR) were used to investigate the morphology and molecular interaction of film. X-ray diffraction results indicated that the samples with chitin whiskers had a more rigid structure. The addition of tannic acid changed the structure into an anhydrous crystalline conformation when compared to neat chitosan film.
    Matched MeSH terms: Chitin/chemistry*; Tannins/chemistry*; Water/chemistry; Chitosan/chemistry*; Nanocomposites/chemistry*
  11. Characterization of bovine serum albumin partitioning behaviors in polymer-salt aqueous two-phase systems
    Chow YH, Yap YJ, Tan CP, Anuar MS, Tejo BA, Show PL, et al.
    J Biosci Bioeng, 2015 Jul;120(1):85-90.
    PMID: 25553974 DOI: 10.1016/j.jbiosc.2014.11.021
    In this paper, a linear relationship is proposed relating the natural logarithm of partition coefficient, ln K for protein partitioning in poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS) to the square of tie-line length (TLL(2)). This relationship provides good fits (r(2) > 0.98) to the partition of bovine serum albumin (BSA) in PEG (1450 g/mol, 2000 g/mol, 3350 g/mol, and 4000 g/mol)-phosphate ATPS with TLL of 25.0-50.0% (w/w) at pH 7.0. Results also showed that the plot of ln K against pH for BSA partitioning in the ATPS containing 33.0% (w/w) PEG1450 and 8.0% (w/w) phosphate with varied working pH between 6.0 and 9.0 exhibited a linear relationship which is in good agreement (r(2) = 0.94) with the proposed relationship, ln K = α' pH + β'. These results suggested that both the relationships proposed could be applied to correlate and elucidate the partition behavior of biomolecules in the polymer-salt ATPS. The influence of other system parameters on the partition behavior of BSA was also investigated. An optimum BSA yield of 90.80% in the top phase and K of 2.40 was achieved in an ATPS constituted with 33.0% (w/w) PEG 1450 and 8.0% (w/w) phosphate in the presence of 8.5% (w/w) sodium chloride (NaCl) at pH 9.0 for 0.3% (w/w) BSA load.
    Matched MeSH terms: Phosphates/chemistry; Polyethylene Glycols/chemistry*; Serum Albumin, Bovine/chemistry*; Sodium Chloride/chemistry*; Water/chemistry*
  12. Fulltext Synthesis of silver nanoparticles dispersed in various aqueous media using laser ablation
    Tajdidzadeh M, Azmi BZ, Yunus WM, Talib ZA, Sadrolhosseini AR, Karimzadeh K, et al.
    ScientificWorldJournal, 2014;2014:324921.
    PMID: 25295298 DOI: 10.1155/2014/324921
    The particle size, morphology, and stability of Ag-NPs were investigated in the present study. A Q-Switched Nd: YAG pulsed laser (λ = 532 nm, 360 mJ/pulse) was used for ablation of a pure Ag plate for 30 min to prepare Ag-NPs in the organic compound such as ethylene glycol (EG) and biopolymer such as chitosan. The media (EG, chitosan) permitted the making of NPs with well dispersed and average size of Ag-NPs in EG is about 22 nm and in chitosan is about 10 nm in spherical form. Particle size, morphology, and stability of NPs were compared with distilled water as a reference. The stability of the samples was studied by measuring UV-visible absorption spectra of samples after one month. The result indicated that the formation efficiency of NPs in chitosan was higher than other media and NPs in chitosan solution were more stable than other media during one month storage. This method for synthesis of silver NPs could be as a green method due to its environmentally friendly nature.
    Matched MeSH terms: Silver/chemistry*; Water/chemistry*; Metal Nanoparticles/chemistry*; Green Chemistry Technology/methods*
  13. Fulltext Effect of zirconium oxide nanofiller and dibutyl phthalate plasticizer on ionic conductivity and optical properties of solid polymer electrolyte
    Yasin SM, Ibrahim S, Johan MR
    ScientificWorldJournal, 2014;2014:547076.
    PMID: 25133244 DOI: 10.1155/2014/547076
    New solid polymer electrolytes (SPE) based on poly(ethylene oxide) (PEO) doped with lithium trifluoromethanesulfonate (LiCF3SO3), dibutyl phthalate (DBP) plasticizer, and zirconium oxide (ZrO2) nanoparticles were prepared by solution-casting technique. The conductivity was enhanced by addition of dibutyl phthalate (DBP) plasticizer and ZrO2 nanofiller with maximum conductivity (1.38 × 10(-4) Scm(-1)). The absorption edge and band gap values showed decreases upon addition of LiSO3CF3, DBP, and ZrO2 due to the formation of localized states in the SPE and the degree of disorder in the films increased.
    Matched MeSH terms: Dibutyl Phthalate/chemistry*; Ions/chemistry; Polyethylene Glycols/chemistry*; Zirconium/chemistry*; Nanoparticles/chemistry*
  14. Fulltext Rubus fruticosus L.: constituents, biological activities and health related uses
    Zia-Ul-Haq M, Riaz M, De Feo V, Jaafar HZ, Moga M
    Molecules, 2014 Jul 28;19(8):10998-1029.
    PMID: 25072202 DOI: 10.3390/molecules190810998
    Rubus fruticosus L. is a shrub famous for its fruit called blackberry fruit or more commonly blackberry. The fruit has medicinal, cosmetic and nutritive value. It is a concentrated source of valuable nutrients, as well as bioactive constituents of therapeutic interest highlighting its importance as a functional food. Besides use as a fresh fruit, it is also used as ingredient in cooked dishes, salads and bakery products like jams, snacks, desserts, and fruit preserves. R. fruticosus contains vitamins, steroids and lipids in seed oil and minerals, flavonoids, glycosides, terpenes, acids and tannins in aerial parts that possess diverse pharmacological activities such as antioxidant, anti-carcinogenic, anti-inflammatory, antimicrobial anti-diabetic, anti-diarrheal, and antiviral. Various agrogeoclimatological factors like cultivar, environmental conditions of the area, agronomic practices employed, harvest time, post-harvest storage and processing techniques all influence the nutritional composition of blackberry fruit. This review focuses on the nutrients and chemical constituents as well as medicinal properties of different parts of R. fruticosus. Various cultivars and their physicochemical characteristics, polyphenolic content and ascorbic acid content are also discussed. The information in the present work will serve as baseline data and may lead to new biomedical applications of R. fruticosus as functional food.
    Matched MeSH terms: Fruit/chemistry; Plant Extracts/chemistry*; Plants, Medicinal/chemistry; Phytochemicals/chemistry; Rubus/chemistry*
  15. Robust enzymatic hydrolysis of Formiline-pretreated oil palm empty fruit bunches (EFB) for efficient conversion of polysaccharide to sugars and ethanol
    Cui X, Zhao X, Zeng J, Loh SK, Choo YM, Liu D
    Bioresour Technol, 2014 Aug;166:584-91.
    PMID: 24956030 DOI: 10.1016/j.biortech.2014.05.102
    Oil palm empty fruit bunch (EFB) was pretreated by Formiline process to overcome biomass recalcitrance and obtain hemicellulosic syrup and lignin. Higher formic acid concentration led to more lignin removal but also higher degree of cellulose formylation. Cellulose digestibility could be well recovered after deformylation with a small amount of lime. After digested by enzyme loading of 15 FPU+10 CBU/g solid for 48 h, the polysaccharide conversion could be over 90%. Simultaneous saccharification and fermentation (SSF) results demonstrated that ethanol concentration reached 83.6 g/L with approximate 85% of theoretic yield when performed at an initial dry solid consistency of 20%. A mass balance showed that via Formiline pretreatment 0.166 kg of ethanol could be produced from 1 kg of dry EFB with co-production of 0.14 kg of high-purity lignin and 5.26 kg hemicellulosic syrup containing 2.8% xylose. Formiline pretreatment thus can be employed as an entry for biorefining of EFB.
    Matched MeSH terms: Ethanol/chemistry*; Formates/chemistry*; Lignin/chemistry; Polysaccharides/chemistry*; Arecaceae/chemistry*
  16. Fulltext Effects of surfactants on the properties of mortar containing styrene/methacrylate superplasticizer
    Negim el-S, Kozhamzharova L, Khatib J, Bekbayeva L, Williams C
    ScientificWorldJournal, 2014;2014:942978.
    PMID: 24955426 DOI: 10.1155/2014/942978
    The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA.
    Matched MeSH terms: Epoxy Compounds/chemistry; Methacrylates/chemistry*; Polymers/chemistry; Surface-Active Agents/chemistry*; Styrene/chemistry*
  17. Functionalized fullerene (C₆₀) as a potential nanomediator in the fabrication of highly sensitive biosensors
    Afreen S, Muthoosamy K, Manickam S, Hashim U
    Biosens Bioelectron, 2015 Jan 15;63:354-364.
    PMID: 25125029 DOI: 10.1016/j.bios.2014.07.044
    Designing a biosensor for versatile biomedical applications is a sophisticated task and how dedicatedly functionalized fullerene (C60) can perform on this stage is a challenge for today and tomorrow's nanoscience and nanotechnology. Since the invention of biosensor, many ideas and methods have been invested to upgrade the functionality of biosensors. Due to special physicochemical characteristics, the novel carbon material "fullerene" adds a new dimension to the construction of highly sensitive biosensors. The prominent aspects of fullerene explain its outstanding performance in biosensing devices as a mediator, e.g. fullerene in organic solvents exhibits five stages of reversible oxidation/reduction, and hence fullerene can work either as an electrophile or nucleophile. Fullerene is stable and its spherical structure produces an angle strain which allows it to undergo characteristic reactions of addition to double bonds (hybridization which turns from sp(2) to sp(3)). Research activities are being conducted worldwide to invent a variety of methods of fullerene functionalization with a purpose of incorporating it effectively in biosensor devices. The different types of functionalization methods include modification of fullerene into water soluble derivatives and conjugation with enzymes and/or other biomolecules, e.g. urease, glucose oxidase, hemoglobin, myoglobin (Mb), conjugation with metals e.g. gold (Au), chitosan (CS), ferrocene (Fc), etc. to enhance the sensitivity of biosensors. The state-of-the-art research on fullerene functionalization and its application in sensor devices has proven that fullerene can be implemented successfully in preparing biosensors to detect glucose level in blood serum, urea level in urine solution, hemoglobin, immunoglobulin, glutathione in real sample for pathological purpose, to identify doping abuse, to analyze pharmaceutical preparation and even to detect cancer and tumor cells at an earlier stage. Employing fullerene-metal matrix for the detection of tumor and cancer cells is also possible by the inclusion of fullerene in single-walled carbon nanotubes (SWCNTs) known as peapods as well as in double-walled carbon nanotubes (DWCNTs), to augment the effectiveness of biosensors. This review discusses various approaches that have been reported for functionalizing fullerene (C60) derivatives and their application in different types of biosensor fabrication.
    Matched MeSH terms: Ferrous Compounds/chemistry; Fullerenes/chemistry*; Nanotubes, Carbon/chemistry; Chitosan/chemistry; Metal Nanoparticles/chemistry
  18. Topological characterization of a bacterial cellulose-acrylic acid polymeric matrix
    Halib N, Mohd Amin MC, Ahmad I, Abrami M, Fiorentino S, Farra R, et al.
    Eur J Pharm Sci, 2014 Oct 1;62:326-33.
    PMID: 24932712 DOI: 10.1016/j.ejps.2014.06.004
    This paper focuses on the micro- and nano-topological organization of a hydrogel, constituted by a mixture of bacterial cellulose and acrylic acid, and intended for biomedical applications. The presence of acrylic acid promotes the formation of two interpenetrated continuous phases: the primary "pores phase" (PP) containing only water and the secondary "polymeric network phase" (PNP) constituted by the polymeric network swollen by the water. Low field Nuclear Magnetic Resonance (LF NMR), rheology, Scanning Electron Microscopy (SEM) and release tests were used to determine the characteristics of the two phases. In particular, we found that this system is a strong hydrogel constituted by 81% (v/v) of PP phase the remaining part being occupied by the PNP phase. Pores diameters span in the range 10-100 μm, the majority of them (85%) falling in the range 30-90 μm. The high PP phase tortuosity indicates that big pores are not directly connected to each other, but their connection is realized by a series of interconnected small pores that rend the drug path tortuous. The PNP is characterized by a polymer volume fraction around 0.73 while mesh size is around 3 nm. The theoretical interpretation of the experimental data coming from the techniques panel adopted, yielded to the micro- and nano-organization of our hydrogel.
    Matched MeSH terms: Acrylates/chemistry*; Cellulose/chemistry*; Polymers/chemistry*; Theophylline/chemistry; Hydrogels/chemistry*
  19. Properties of polylactic acid composites reinforced with oil palm biomass microcrystalline cellulose
    Haafiz MK, Hassan A, Zakaria Z, Inuwa IM, Islam MS, Jawaid M
    Carbohydr Polym, 2013 Oct 15;98(1):139-45.
    PMID: 23987327 DOI: 10.1016/j.carbpol.2013.05.069
    In this work, polylactic acid (PLA) composites filled with microcrystalline cellulose (MCC) from oil palm biomass were successfully prepared through solution casting. Fourier transform infrared (FT-IR) spectroscopy indicates that there are no significant changes in the peak positions, suggesting that incorporation of MCC in PLA did not result in any significant change in chemical structure of PLA. Thermogravimetric analysis was conducted on the samples. The T50 decomposition temperature improved with addition of MCC, showing increase in thermal stability of the composites. The synthesized composites were characterized in terms of tensile properties. The Young's modulus increased by about 30%, while the tensile strength and elongation at break for composites decreased with addition of MCC. Scanning electron microscopy (SEM) of the composites fractured surface shows that the MCC remained as aggregates of crystalline cellulose. Atomic force microscopy (AFM) topographic image of the composite surfaces show clustering of MCC with uneven distribution.
    Matched MeSH terms: Cellulose/chemistry*; Fruit/chemistry; Polymers/chemistry*; Lactic Acid/chemistry*; Arecaceae/chemistry*
  20. Fulltext Effects of using pozzolan and Portland cement in the treatment of dispersive clay
    Vakili AH, Selamat MR, Moayedi H
    ScientificWorldJournal, 2013;2013:547615.
    PMID: 23864828 DOI: 10.1155/2013/547615
    Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.
    Matched MeSH terms: Adhesives/chemistry*; Aluminum Silicates/chemistry*; Calcium Carbonate/chemistry*; Calcium Hydroxide/chemistry*; Excipients/chemistry*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links