Home About us Contact
|
Home About us Contact | ||
|
|
||
Methyl Cellulose (methyl + cellulose)
Selected AbstractsFractionation of Methyl Cellulose According to Polarity , a Tool to Differentiate First and Second Order Heterogeneity of the Substituent DistributionMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2006Roland Adden Abstract Summary: A set of four MCs (DS 1.80,1.95) has been analyzed with regard to their substituent pattern in the glucosyl units and along the polymer chain. The average heterogeneity of methylation observed for the entire material was analyzed in more detail after fractionation according to polarity. All fractions obtained were analyzed with respect to their DS, monomer composition and deviation from a random distribution of these monomers in the polymer chains. By this approach, heterogeneity of first and second order could be differentiated. While for three of the MCs only a minor DS-gradient over the material was observed, a more pronounced heterogeneity of first order was obtained for MC 4. ESI mass spectrum of the undissolved residue of MC 2 after deuteromethylation and partial hydrolysis; DP 2 and 3 are shown in detail. Signals are assigned according to the number of CH3 -groups. [source] Sample preparation effects in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry of partially depolymerised methyl celluloseRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2003Dane Momcilovic Methyl cellulose (MC) was partially depolymerised and the oligomers thus obtained were studied by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The depolymerisation was either enzymatic or acidic. Fractions of enzymatically depolymerised MC were collected from size-exclusion chromatography and subjected to a sample preparation investigation. Several MALDI matrices and solvents were evaluated. The results showed that the solvent choice had a significant effect on the measured degree of substitution (DS). Aprotic solvents produced higher DS values, which was most likely due to poor solubility of species with low DS. The obtained signal intensity, however, did not correlate with the solubility but seemed to be more dependent on certain matrix/solvent combinations. All the matrices attempted produced mass spectra with sufficient signal intensity for accurate peak area calculation. The choice of matrix did not have any significant effect on the measured DS. Sample spots obtained from organic solvents had a more homogeneous distribution of the analyte and smaller crystals than those obtained from water. This increased both the reproducibility and peak resolution and in addition the analysis time was shorter. DS measurements were performed on two acidically depolymerised MCs with different nominal DS values. It was easy to distinguish between the two MCs, and the measured DS values agreed well with the values supplied by the manufacturers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Physical properties of biopolymers containing natamycin and rosemary extractINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2009Hasan Türe Summary Antifungal biopolymers were prepared by incorporating natamycin (NA) and NA + rosemary extract (RE) into wheat gluten (WG) and methyl cellulose (MC) films. Interaction between antimicrobial agents and biopolymers was determined with mid-infrared spectroscopy and scanning electron microscopy (SEM). Water vapour permeability and mechanical properties of these films were also measured. Mid-infrared spectroscopy did not indicate any interaction. SEM observations showed that NA crystallises at high concentrations in biopolymers. There were no significant changes in water vapour permeabilities of biopolymers containing active agents at P < 0.05. While NA incorporation did not result in any changes in mechanical properties of WG films a reduction in tensile strength was observed for MC films containing high concentration of NA. In general, active agent incorporation into WG and MC films did not result in any considerable changes in their physical properties that could affect their application. [source] The performance of a methyl cellulose-treated coating during the frying of a poultry productINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2005Mohamad Y. Maskat Summary The performance of coatings treated with a range of methyl cellulose (MC) concentrations during the frying of coated chicken breasts was investigated. Chicken breasts were immersed in 0, 1 and 2.5% MC solution and then coated with a commercial coating mix. The coated chicken breasts were then fried at an initial temperature of 190 °C. Parameters measured included coating pickup, coating loss, cooked yield and frying loss. Results showed a significant increase in coating pickup with the use of 1 and 2.5% MC, which may have been due to the higher viscosity and binding ability of the MC layer. The use of 2.5% MC produced lower coating loss and frying loss and also a higher cooked yield. [source] Structure and mechanical properties of cellulose derivatives/soy protein isolate blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ziyan Zhou Abstract Biodegradable and biocompatible composites based on soy protein isolate (SPI) and various cellulose derivatives have been prepared, and the dependence of structures and mechanical properties on the content and species of cellulose derivatives for the composites were investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and tensile test. The selected cellulose derivatives, such as methyl cellulose (MC), hydroxyethyl cellulose (HEC), and hydroxypropyl cellulose, were miscible with SPI when the content of cellulose derivatives was low, and then the isolated crystalline domains, shown as the structures of network and great aggregate, formed with an increase of cellulose derivative content. The miscible blends could produce the higher strength, and even result in the simultaneous enhancement of strength and elongation for the HEC/SPI and MC/SPI blends. Meanwhile, the moderate content of great MC domains also reinforced the materials. However, the damage of original ordered structure in SPI gave the decreased modulus. Since all the components, i.e., cellulose derivatives and soy protein, are biocompatible, the resultant composites are not only used as environment-friendly material, but the biomedical application can be expected, especially for the tissue engineering scaffold. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Antifibrotic effects of tetrandrine on hepatic stellate cells and rats with liver fibrosisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 1 2007Yi-Chao Hsu Abstract Background:, Anti-inflammation strategies are one of the proposed therapeutic approaches to hepatic fibrosis. Tetrandrine (C38H42O8N2, molecular weight: 622; Tet), an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to exert anti-inflammatory activity in pulmonary diseases. The purpose of the present study was to investigate the in vitro and in vivo effects of Tet on hepatic fibrosis. Methods:, A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with transforming growth factor-,1 (TGF-,1) or tumor necrosis factor-, (TNF-,). The inhibitory effects of Tet on the nuclear factor ,B (NF,B) signaling cascade and molecular markers including intercellular adhesion molecule-1 (ICAM-1) and ,-smooth muscle actin (,-SMA) secretion were assessed. Fibrosis was induced by dimethylnitrosamine (DMN) administration in rats for 4 weeks. Fibrotic rats were randomly assigned to one of the four groups: vehicle (0.7% carboxyl methyl cellulose, CMC), Tet (1 mg/kg), Tet (5 mg/kg), or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting after 1 week of DMN administration. At the end of the study, liver tissues were scored for fibrosis and analyzed for molecular markers of fibrosis. Results:, Tetrandrine (0.5,5.0 µmol/L) concentration-dependently inhibited NF,B transcriptional activity induced by TNF-,, including I,B, phosphorylation and mRNA expressions of ICAM-1 in HSC-T6 cells. In addition, Tet also inhibited TGF-,1-induced ,-SMA secretion and collagen deposition in HSC-T6 cells. Fibrosis scores of livers from DMN-treated rats with high-dose Tet (1.3 ± 0.3) were significantly reduced in comparison with DMN-treated rats receiving saline (2.0 ± 0.2). Hepatic collagen content of DMN rats was significantly reduced by either Tet or silymarin treatment. Double-staining results showed that ,-SMA- and NF,B-positive cells were decreased in the fibrotic livers by Tet and silymarin treatment. In addition, mRNA expression of ICAM-1, ,-SMA, and TGF-,1 was attenuated by Tet treatment. Moreover, levels of plasma aspartate aminotransferase and alanine aminotransferase activities were reduced by Tet and silymarin treatment. Conclusion:, Tetrandrine exerts antifibrotic effects in both HSC-T6 cells and in rats with DMN-induced fibrosis. [source] Sumatriptan succinate transdermal delivery systems for the treatment of migraineJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2008C. Balaguer-Fernández Abstract We have successfully obtained sumatriptan transdermal systems with different polymer compositions: methyl cellulose (MC), polyvinyl pyrrolidone (PVP) and a polyvinyl pyrrolidone (PVP)-polyvinyl alcohol (PVA) mixture. The systems contained 1,2-propilenglycol (MC) or sorbitol as a plasticizer (PVP and PVP-PVA), methacrylate copolymer as an adhesive agent, and an occlusive liner. Azone® (5%, w/w) was incorporated into all the systems as a percutaneous enhancer. Transdermal systems are thin, transparent and non-adhesive when in a dry state. The permeation of sumatriptan succinate across pig ear skin was studied using the systems prepared. The formulation with MC polymer produced a statistically significant increment with respect to the PVP and PVP-PVA formulations (p,<,0.05). Azone® incorporation into the systems produced an increment in the sumatriptan flux values of all three transdermal systems with respect to those of the controls (p,<,0.05). In addition, the application of iontophoresis to the wet methyl cellulose-Azone® formulation produced a much higher increase of sumatriptan transdermal flux. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2102,2109, 2008 [source] Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy studyJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2005P. M. Fechner Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose ether films were described by time-dependent contact angle measurements. Changes in molecular structure of the raw materials, gels and films caused by water contact were studied using Raman spectroscopy. Differences between the substitution types and changes due to the gel or film formation were observed. An environmental scanning electron microscopy (ESEM) technique was used to distinguish the morphological behaviour of the cellulose ether films in contact with water. Based on in-situ ESEM experiments, the swelling and drying behaviour of the various stages of cellulose ether films (film-hydrated film-dried film) were quantified by using image analysis. [source] Preparation of Porous Ca10(PO4)6(OH)2 and ,-Ca3(PO4)2 BioceramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2000N. Özgür Engin Submicrometer-sized, pure calcium hydroxyapatite (HA, (Ca10(PO4)6(OH)2)) and ,-tricalcium phosphate (,-TCP, Ca3(PO4)2) bioceramic powders, that have been synthesized via chemical precipitation techniques, were used in the preparation of aqueous slurries that contained methyl cellulose to manufacture porous (70%,95% porosity) HA or ,-TCP ceramics. The pore sizes in HA bioceramics of this study were 200,400 ,m, whereas those of ,-TCP bioceramics were 100,300 ,m. The pore morphology and total porosity of the HA and ,-TCP samples were investigated via scanning electron microscopy, water absorption, and computerized tomography. [source] Cationic Dye,sensitized Degradation of Sodium Hyaluronate Through Photoinduced Electron Transfer in the Upper Excited State,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2001Masanobu Kojima ABSTRACT The formation of ground-state complexes of methylene blue (MB) and thionine (TN) with sodium hyaluronate (NaHA) was clearly observed by means of absorption spectra in aqueous solution. Irradiation of the complexes using 313 nm light caused significant degradation of NaHA under oxygen and argon. However, the use of visible light over 400 nm, which gives the lowest excited singlet state of the cationic dyes, caused no degradation. MB and TN were more efficient sensitizers for the degradation of NaHA than rose bengal (RB), although RB is a more efficient singlet oxygen (1O2) sensitizer than the cationic dyes. Under similar conditions the polysaccharides with carboxyl groups, such as alginic acid and polygalacturonic acid, also photodecomposed. However, the polysaccharides without carboxyl groups, such as pullulan and methyl cellulose, did not. The irradiation of the polysaccharides in the presence of powdered titanium dioxide as a photocatalyst to generate the hydroxyl radical (·OH) in aerated aqueous solution caused the fragmentation of all the polymers. It was confirmed that methyl viologen, an electron-accepting sensitizer, formed a charge-transfer complex with NaHA, the irradiation of which caused the efficient degradation of NaHA. In the presence of ,- and ,-cyclodextrins the MB- and TN-sensitized photodegradation of NaHA was markedly suppressed. This was probably due to the formation of the inclusion complexes comprising the cationic dyes and the cyclodextrins. On the basis of the results obtained we propose that the cationic dye,sensitized degradation of NaHA involves a photoinduced electron-transfer process between the upper excited dyes and the ground-state NaHA and that ·OH and 1O2 do not participate in the degradation. [source] Pyrolysis mass spectrometry for distinguishing potential hoax materials from bioterror agents,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2006Jon G. Wilkes Pyrolysis mass spectrometry (PyMS) was investigated as a rapid tool to distinguish potential bioterror hoax materials from samples containing pathogenic bacteria. A pyrolysis time-of-flight (TOF) mass spectrometer equipped with an alternative ionization technique, metastable atom bombardment (MAB), was used to produce sample spectra. These spectra were analyzed by principal component and discriminant analysis for pattern recognition. Materials investigated were two strains of Vibrio parahaemolyticus, one of which produced the tdh toxin, two Salmonella enterica serotypes, a biological mosquito control product containing spores of Bacillus thuringiensis, and several white to off-white powders (which could be used as hoax materials), such as flour, corn starch, methyl cellulose, and xanthan gum. PyMS distinguished bacterial samples from hoax materials. Furthermore, pattern analysis differentiated Vibrios from Salmonellae, Salmonella enterica Anatum from S. enterica Heidelberg, and the two V. parahaemolyticus strains from each other. The B. thuringiensis mixture was distinguished from other bacteria and powders, suggesting that PyMS with pattern recognition may differentiate samples containing pathogens, including Bacillus spp., from nonbiological agents and that it can be a rapid method for detection of bacteria. MS data acquisition took only 7 min for each sample. Published in 2006 by John Wiley & Sons, Ltd. [source] Sample preparation effects in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry of partially depolymerised methyl celluloseRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2003Dane Momcilovic Methyl cellulose (MC) was partially depolymerised and the oligomers thus obtained were studied by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The depolymerisation was either enzymatic or acidic. Fractions of enzymatically depolymerised MC were collected from size-exclusion chromatography and subjected to a sample preparation investigation. Several MALDI matrices and solvents were evaluated. The results showed that the solvent choice had a significant effect on the measured degree of substitution (DS). Aprotic solvents produced higher DS values, which was most likely due to poor solubility of species with low DS. The obtained signal intensity, however, did not correlate with the solubility but seemed to be more dependent on certain matrix/solvent combinations. All the matrices attempted produced mass spectra with sufficient signal intensity for accurate peak area calculation. The choice of matrix did not have any significant effect on the measured DS. Sample spots obtained from organic solvents had a more homogeneous distribution of the analyte and smaller crystals than those obtained from water. This increased both the reproducibility and peak resolution and in addition the analysis time was shorter. DS measurements were performed on two acidically depolymerised MCs with different nominal DS values. It was easy to distinguish between the two MCs, and the measured DS values agreed well with the values supplied by the manufacturers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Energy Efficiency of Two-Phase Mixing in a Modified Bubble ColumnTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2007Subrata Kumar Majumder Abstract Energy efficiency for gas liquid mixing in a modified downflow bubble column reactor has been analyzed in this paper. Efficiencies of the different parts of the bubble column have been assessed on the basis of energy dissipation. Prediction of the energy dissipation coefficient as well as energy utilization efficiency due to gas-liquid mixing as a function of different physical, geometric and dynamic variables of the system has been done by correlation method. The distribution of energy utilization in the different zones of the column has also been analyzed. Experiments were carried out with air-water and air-aqueous solutions of carboxy methyl cellulose with different concentrations. Dans cet article on a analysé l'efficacité énergétique pour le mélange gaz-liquide dans un réacteur à colonne à bulles à écoulement descendant modifié. Les efficacités des différentes régions de la colonne à bulles ont été évaluées sur la base de la dissipation d'énergie. On a utilisé une méthode de corrélation pour prédire le coefficient de dissipation d'énergie ainsi que l'efficacité d'utilisation de l'énergie due au mélange gaz-liquide en fonction des différentes variables physiques, géométriques et dynamiques du système. La distribution de l'utilisation de l'énergie dans les différentes régions de la colonne a également été analysée. Des expériences ont été menées avec des solutions air-eau et air-solutions aqueuses de carboxyméthylcellulose à différentes concentrations. [source] Effect of unionized ammonia, viscosity and protozoan contamination on the enzyme activity of the rotifer Brachionus plicatilisAQUACULTURE RESEARCH, Issue 4 2000A B. De Araujo Substrates that are cleaved to yield fluorescent products can be used to quickly quantify enzyme activity in vivo with image analysis or in vitro with fluorometry. This study was carried out to determine whether enzyme activity in rotifers is useful for assessing the physiological condition of rotifers. Neonates of Brachionus plicatilis Müller hatched from cysts were exposed to a concentration series of unionized ammonia ranging from 0 to 9.8 p.p.m., increasing seawater viscosity relative to 1.17 to control sea water by the addition of methyl cellulose and the addition of the protozoan Euplotes sp. to a density of 40 mL,1. Rotifer glucosidase and esterase activities decreased with increasing unionized ammonia and viscosity respectively. Activities of glucosidase and phospholipase decreased with increasing protozoan contamination. There was a significant relationship between enzyme activities and rotifer population growth. In vivo activities of certain rotifer enzymes can therefore serve as biomarkers for the rapid assessment of environmental stressors in rotifer mass cultures. [source] Gas,liquid mass transfer in three-phase inverse fluidized bed reactor with Newtonian and non-Newtonian fluidsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010V. Sivasubramanian Abstract Liquid-phase volumetric mass transfer coefficients, kLa were determined in three-phase inverse fluidized beds of low-density polyethylene (LDPE) and polypropylene (PP) spheres fluidized by a countercurrent flow of air and Newtonian (water and glycerol solutions) or non-Newtonian liquids [carboxy methyl cellulose (CMC) solutions]. The effects of liquid and gas velocities, particle size, solid loading and addition of organic additives (glycerol and CMC) on the volumetric mass transfer coefficient, kLa were determined. The superficial liquid velocity had a weak effect on the mass transfer whereas the gas flow rate affected the mass transfer positively. kLa increased with increase in particle diameter and decreased with increase in initial bed height (solid loading). kLa decreased as the concentration of glycerol (viscosity) and CMC increased. Empirical correlations are presented to predict the gas,liquid volumetric mass transfer coefficient in terms of operating variables. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] An in vitro study of the antimicrobial activity of some endodontic medicaments against Enteroccus faecalis biofilmsAUSTRALIAN DENTAL JOURNAL, Issue 2 2010B Athanassiadis Abstract Background:, The in vitro antimicrobial activity of a series of endodontic medicaments and their bases against biofilms of Enterococcus faecalis was investigated. Methods:, The medicaments tested were Pulpdent paste, Ledermix paste, a 50:50 Ledermix and Pulpdent mixture, and a replica of Ledermix paste. Bases included methyl cellulose with water, polyethylene glycol (PEG), and PEG with zinc oxide, calcium chloride and the other components (inactives) that make up the Ledermix paste base. Biofilms grown on cellulose nitrate membrane filters were exposed to the medicaments for up to 5 days. The number of surviving colony forming units (CFU) was determined at days 1, 3 and 5. The results were expressed as a bacterial survival index (BSI) when compared to the unexposed control. Results:, Pulpdent produced the greatest reduction of BSI, followed by the 50:50 mixture of Pulpdent and Ledermix pastes. Ledermix paste, its replica and the individual bases showed no significant reductions in the BSI for E. faecalis. Conclusions:, Within the limitations of this laboratory study, calcium hydroxide containing preparations had greater potential for reducing the survival of E. faecalis in a biofilm environment. [source] | ||||||||||||||||