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1

Development of cellulose acetate propionate membrane for separation of ethanol and ethyl tert-butyl ether mixtures  

SciTech Connect

For pervaporation separation of ethanol and ethyl tert-butyl ether mixtures, a cellulose acetate propionate membrane was chosen as the experimental membrane because of its high selectivity and good mass fluxes. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the permeates depend on the ethanol concentration in the feed and the experimental temperature. With increases of the ethanol weight fraction in the feed and the temperature, the total and partial mass fluxes increased. With respect to the temperature, ethanol mass flux obeys the Arrhenius equation. The selectivity of this membrane decreases as the temperature and the ethanol concentration in the feed increase. This membrane shows special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase when temperature and the ethanol concentration in the feed are increasing. The ethanol concentration in the sorption solution is also influenced by the temperature and the mixture`s composition. When the temperature increases, the sorption selectivity of the membrane decreases.

Luo, G.S.; Niang, M.; Schaetzel, P. [Laboratoire D`Automatique et de Procedes, Caen (France)

1997-04-01

2

Conductive iron oxides accelerate thermophilic methanogenesis from acetate and propionate.  

PubMed

Anaerobic digester is one of the attractive technologies for treatment of organic wastes and wastewater, while continuous development and improvements on their stable operation with efficient organic removal are required. Particles of conductive iron oxides (e.g., magnetite) are known to facilitate microbial interspecies electron transfer (termed as electric syntrophy). Electric syntrophy has been reported to enhance methanogenic degradation of organic acids by mesophilic communities in soil and anaerobic digester. Here we investigated the effects of supplementation of conductive iron oxides (magnetite) on thermophilic methanogenic microbial communities derived from a thermophilic anaerobic digester. Supplementation of magnetite accelerated methanogenesis from acetate and propionate under thermophilic conditions, while supplementation of ferrihydrite also accelerated methanogenesis from propionate. Microbial community analysis revealed that supplementation of magnetite drastically changed bacterial populations in the methanogenic acetate-degrading cultures, in which Tepidoanaerobacter sp. and Coprothermobacter sp. dominated. These results suggest that supplementation of magnetite induce electric syntrophy between organic acid-oxidizing bacteria and methanogenic archaea and accelerate methanogenesis even under thermophilic conditions. Findings from this study would provide a possibility for the achievement of stably operating thermophilic anaerobic digestion systems with high efficiency for removal of organics and generation of CH4. PMID:25488041

Yamada, Chihaya; Kato, Souichiro; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

2014-12-01

3

Dioxouranium (VI) complexes with cellulose acetate  

Microsoft Academic Search

Dioxouranium [UO2(VI)] complexes with three degrees of substitution of cellulose acetate, prepared from viscose pulp (DS = 2.2, 2.45 and 2.86), have been synthesis and characterized. Degree of substitution (DS) is defined as the average number of CH groups substituted on each anhydrocellulose repeat unit. Probable structures of the cellulose acetate complexes were inferred from the elemental analysis data, conductance

Altaf H. Basta; Wafaa M. Hosny

1998-01-01

4

Formation of acetic acid from cellulosic substrates by Fusarium oxysporum  

Microsoft Academic Search

Four strains of Fusarium oxysporum and a strain of Monilia brunnae were screened for their ability to convert cellulosic substrates into ethanol\\/acetic acid. These strains were found to utilize cellulose and produce extracellular cellulases. However, only F. oxysporum 841 was found to convert glucose, xylose, and cellulose into ethanol and acetic acid as major end-products under microaerobic conditions. Acetic acid

P. K. R. Kumar; Ajay Singh; K. Schiigerl

1991-01-01

5

Effect of formic, acetic and propionic acid on preservation and aerobic deterioration of grass silage  

E-print Network

Effect of formic, acetic and propionic acid on preservation and aerobic deterioration of grass deterioration of low dry matter (DM) grass silage. For comparison untreated high DM grass silage was also grass was chopped and treated with equimolar amounts of formic acid (FA ; 3.3 g/kg), acetic acid (AA ; 4

Paris-Sud XI, Université de

6

Ammonia permeability of a cellulose acetate membrane  

Microsoft Academic Search

A mechanism is proposed for ammonia transport across a cellulose acetate membrane. The transport is shown to have a sorption\\u000a character, with the formation of hydrogen bonds between ammonia molecules and the polymer. Our experiments demonstrate that\\u000a the membrane can be regenerated in the course of gas separation. The ideal separation factors in the ammonia-nitrogen and\\u000a ammonia-hydrogen systems are determined.

I. V. Vorotyntsev; P. N. Drozdov; N. V. Karyakin

2006-01-01

7

Fed-batch fermentation with and without on-line extraction for propionic and acetic acid production by Propionibacterium acidipropionici  

Microsoft Academic Search

Fed-batch propionic and acetic acid fermentations were performed in semi-defined laboratory medium and in corn steep liquor withPropionibacterium acidipropionici strain P9. On average, over four experiments, 34.5 g\\/l propionic acid and 12.8 g\\/l acetic acid were obtained in about 146 h in laboratory medium with 79 g\\/l glucose added over five feeding periods. The highest concentration of propionic acid, 45

F. Ozadali; B. A. Glatz; C. E. Glatz

1996-01-01

8

New process for producing cellulose acetate from wood in concentrated acetic acid  

Microsoft Academic Search

To explore further potential applications of acetic acid pulp, an investigation was conducted to develop a direct method for producing cellulose acetate from wood in combination with atmospheric acetic acid pulping. The process consists of delignification, totally chlorine-free bleaching, and esterification, with the concentrated acetic acid aqueous solution being used as only solvent throughout the process. The acetic acid pulp

Hironori Sato; Yasumitsu Uraki; Takao Kishimoto; Yoshihiro Sano

2003-01-01

9

Methane production from rice straw pretreated by a mixture of acetic–propionic acid  

Microsoft Academic Search

Rice straw was treated with a mixed solution of acetic acid and propionic acid to enhance its biodegradability. The effect of acid concentration, pretreatment time, and the ratio of solid to liquid on the delignification performance of rice straw were investigated. It was found that the optimal conditions for hydrolysis were 0.75mol\\/L acid concentration, 2h pretreatment time and 1:20 solid

Rui Zhao; Zhenya Zhang; Ruiqin Zhang; Miao Li; Zhongfang Lei; Motoo Utsumi; Norio Sugiura

2010-01-01

10

The Importance of pH in the Regulation of Ruminal Acetate to Propionate Ratio and Methane Production In Vitro  

Microsoft Academic Search

Grain feeding often causes a decrease in ruminal pH, and experiments were conducted to define the role of pH in regulating the acetate to propionate ratio and production of CH4. Cows that were fed 90% concentrate had lower ruminal pH values (6.22 vs. 6.86), higher VFA concentrations (85 vs. 68 mM ), and lower acetate to propionate ratios (2.24 vs.

J. B. Russell

1998-01-01

11

Biodegradable cellulose acetate nanofiber fabrication via electrospinning.  

PubMed

Nanofiber manufacturing is one of the key advancements in nanotechnology today. Over the past few years, there has been a tremendous growth of research activities to explore electrospinning for nanofiber formation from a rich variety of materials. This quite simple and cost effective process operates on the principle that the solution is extracted under the action of a high electric field. Once the voltage is sufficiently high, a charged jet is ejected following a complicated looping trajectory. During its travel, the solvent evaporates leaving behind randomly oriented nanofibers accumulated on the collector. The combination of their nanoscale dimensionality, high surface area, porosity, flexibility and superior strength makes the electrospun fibers suitable for several value-added applications, such as filters, protecting clothes, high performance structures and biomedical devices. In this study biodegradable cellulose acetate (CA) nanofibrous membranes were produced using electrospinning. The device utilized consisted of a syringe equipped with a metal needle, a microdialysis pump, a high voltage supply and a collector. The morphology of the yielded fibers was determined using SEM. The effect of various parameters, including electric field strength, tip-to-collector distance, solution feed rate and composition on the morphological features of the electrospun fibers was examined. The optimum operating conditions for the production of uniform, non-beaded fibers with submicron diameter were also explored. The biodegradable CA nanofiber membranes are suitable as tissue engineering scaffolds and as reinforcements of biopolymer matrix composites in foils by ultrasonic welding methods. PMID:21133179

Christoforou, Theopisti; Doumanidis, Charalabos

2010-09-01

12

Fed-batch fermentation with and without on-line extraction for propionic and acetic acid production by Propionibacterium acidipropionici  

Microsoft Academic Search

Fed-batch propionic and acetic acid fermentations were performed in semi-defined laboratory medium and in corn steep liquor with Propionibacterium acidipropionici strain P9. On average, over four experiments, 34.5rg\\/l propionic acid and 12.8rg\\/l acetic acid were obtained in about 146rh in laboratory medium with 79rg\\/l glucose added over five feeding periods. The highest concentration of propionic acid, 45rg\\/l, was obtained when

F. Ozadali; B. A. Glatz; C. E. Glatz

1996-01-01

13

Atmospheric chemistry of two biodiesel model compounds: methyl propionate and ethyl acetate.  

PubMed

The atmospheric chemistry of two C(4)H(8)O(2) isomers (methyl propionate and ethyl acetate) was investigated. With relative rate techniques in 980 mbar of air at 293 K the following rate constants were determined: k(C(2)H(5)C(O)OCH(3) + Cl) = (1.57 ± 0.23) × 10(-11), k(C(2)H(5)C(O)OCH(3) + OH) = (9.25 ± 1.27) × 10(-13), k(CH(3)C(O)OC(2)H(5) + Cl) = (1.76 ± 0.22) × 10(-11), and k(CH(3)C(O)OC(2)H(5) + OH) = (1.54 ± 0.22) × 10(-12) cm(3) molecule(-1) s(-1). The chlorine atom initiated oxidation of methyl propionate in 930 mbar of N(2)/O(2) diluent (with, and without, NO(x)) gave methyl pyruvate, propionic acid, acetaldehyde, formic acid, and formaldehyde as products. In experiments conducted in N(2) diluent the formation of CH(3)CHClC(O)OCH(3) and CH(3)CCl(2)C(O)OCH(3) was observed. From the observed product yields we conclude that the branching ratios for reaction of chlorine atoms with the CH(3)-, -CH(2)-, and -OCH(3) groups are <49 ± 9%, 42 ± 7%, and >9 ± 2%, respectively. The chlorine atom initiated oxidation of ethyl acetate in N(2)/O(2) diluent gave acetic acid, acetic acid anhydride, acetic formic anhydride, formaldehyde, and, in the presence of NO(x), PAN. From the yield of these products we conclude that at least 41 ± 6% of the reaction of chlorine atoms with ethyl acetate occurs at the -CH(2)- group. The rate constants and branching ratios for reactions of OH radicals with methyl propionate and ethyl acetate were investigated theoretically using transition state theory. The stationary points along the oxidation pathways were optimized at the CCSD(T)/cc-pVTZ//BHandHLYP/aug-cc-pVTZ level of theory. The reaction of OH radicals with ethyl acetate was computed to occur essentially exclusively (?99%) at the -CH(2)- group. In contrast, both methyl groups and the -CH(2)- group contribute appreciably in the reaction of OH with methyl propionate. Decomposition via the ?-ester rearrangement (to give C(2)H(5)C(O)OH and a HCO radical) and reaction with O(2) (to give CH(3)CH(2)C(O)OC(O)H) are competing atmospheric fates of the alkoxy radical CH(3)CH(2)C(O)OCH(2)O. Chemical activation of CH(3)CH(2)C(O)OCH(2)O radicals formed in the reaction of the corresponding peroxy radical with NO favors the ?-ester rearrangement. PMID:21797203

Andersen, Vibeke F; Berhanu, Tesfaye A; Nilsson, Elna J K; Jørgensen, Solvejg; Nielsen, Ole John; Wallington, Timothy J; Johnson, Matthew S

2011-08-18

14

BIOCA - Biomass Streams to Produce Cellulose Acetate  

Microsoft Academic Search

Cellulose diacetate was produced from hemp fibers. Two main stages were required to produce the product; pulp producti on (delignification) by soda pulping and acetylation of the pulp to cellulose diacetate. Soda pulping of hemp fibers was carried out under various conditions of temperature and liquor concentration. From a consideration of the Kappa number of pulps obtained, it could be

I. Harrison; P. J. G. Huttenhuis; A. B. M. Heesink

15

Cellulose acetate as solid phase in ELISA for plague.  

PubMed

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 microg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates. PMID:10656712

Barbosa, A D; Barros, F S; Callou, E Q; Almeida, A M; Araujo, A M; Azevedo, W M; Carvalho, L B

2000-01-01

16

Cellulose membranes for reverse osmosis Part I. RO cellulose acetate membranes including a composite with polypropylene  

Microsoft Academic Search

With the aim of obtaining RO membranes for brackish water desalination from purified celluloses (cotton linters and bleached bagasse pulp), two reactions (heterogeneous and homogeneous) were applied for the synthesis of cellulose acetate (CA). The efficiency of the membranes was measured and compared with those prepared from purchased CA and prepared CA by acetylation of imported high-grade viscose wood pulp.

Houssni El-Saied; Altaf H. Basta; Barsoum N. Barsoum; Mohamed M. Elberry

2003-01-01

17

Dynamics of Microbial Community Structure of and Enhanced Biological Phosphorus Removal by Aerobic Granules Cultivated on Propionate or Acetate?  

PubMed Central

Aerobic granules are dense microbial aggregates with the potential to replace floccular sludge for the treatment of wastewaters. In bubble-column sequencing batch reactors, distinct microbial populations dominated propionate- and acetate-cultivated aerobic granules after 50 days of reactor operation when only carbon removal was detected. Propionate granules were dominated by Zoogloea (40%), Acidovorax, and Thiothrix, whereas acetate granules were mainly dominated by Thiothrix (60%). Thereafter, an exponential increase in enhanced biological phosphorus removal (EBPR) activity was observed in the propionate granules, but a linear and erratic increase was detected in the acetate ones. Besides Accumulibacter and Competibacter, other bacterial populations found in both granules were associated with Chloroflexus and Acidovorax. The EBPR activity in the propionate granules was high and stable, whereas EBPR in the acetate granules was erratic throughout the study and suffered from a deterioration period that could be readily reversed by inducing hydrolysis of polyphosphate in presumably saturated Accumulibacter cells. Using a new ppk1 gene-based dual terminal-restriction fragment length polymorphism (T-RFLP) approach revealed that Accumulibacter diversity was highest in the floccular sludge inoculum but that when granules were formed, propionate readily favored the dominance of Accumulibacter type IIA. In contrast, acetate granules exhibited transient shifts between type I and type II before the granules were dominated by Accumulibacter type IIA. However, ppk1 gene sequences from acetate granules clustered separately from those of propionate granules. Our data indicate that the mere presence of Accumulibacter is not enough to have consistently high EBPR but that the type of Accumulibacter determines the robustness of the phosphate removal process. PMID:21926195

Gonzalez-Gil, Graciela; Holliger, Christof

2011-01-01

18

Effects of propionate and methylmalonate on conversions of acetate, butyrate, and D(-)-3-hydroxybutyrate to fatty acids and carbon dioxide by mammary tissue slices of goats  

SciTech Connect

Incorporations of (1-carbon-14) acetate, (1-carbon-14) propionate, n-(1-carbon-14) butyrate, and D(-)-3-hydroxy(3-carbon-14) butyrate into individual milk fatty acids and their conversion to carbon dioxide were studied in vitro with caprine mammary tissue slices in the presence and absence of propionate and methylmalonate. Neither propionate nor methylmalonate affected incorporation of these substances into fatty acids. In a decreasing order butyrate, acetate, propionate, and D(-)-3-hydroxybutyrate were converted to carbon dioxide. Acetate had the highest incorporation rate into fatty acids followed by D(-)-3-hydroxybutyrate, butyrate, and propionate. Labeled propionate was incorporated mainly into odd-numbered fatty acids. Results do not support the theory that either propionate or its metabolite, methylmalonate, inhibit de novo synthesis of fatty acids in the mammary gland in relation to the etiology of low milk fat syndrome.

Emmanuel, B.; Kennelly, J.J.

1985-03-01

19

New approach for the production of cellulose acetate: acetylation of mechanical pulp with subsequent isolation of cellulose acetate by differential solubility  

Microsoft Academic Search

A heretofore uninvestigated approach to the production of cellulose acetate is the acetylation of mechanical pulp with subsequent isolation of the cellulose derivative by differential solubility. The mechanical pulp is produced by refining aspen wood chips in a disc-refiner. Two conventional acetylation techniques, the fibrous and solution process, are employed to acetylate all components of the pulp. The cellulose acetate

Barkalow

1987-01-01

20

Electrospun cellulose acetate-garnet nanocomposite magnetic fibers for bioseparations.  

PubMed

Cellulose acetate fibers with magnetic properties have recently attracted much attention because of their potential novel applications in biomedicine such as for cell and protein separations, magnetic resonance imaging contrast agents, and magnetic filters. In this work, as synthesized yttrium iron garnet and gadolinium substituted yttrium iron garnet nanoparticles have been used to generate magnetic filter paper. Garnet nanoparticles dispersed in cellulose acetate polymer solutions were electrospun as free-standing nonwoven fiber mats as well as on cellulose filter paper substrates resulting in magnetic filter papers. The magnetic fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and superconducting quantum interference device (SQUID) magnetic property measurements. The resulting magnetic polymer nanocomposites can be easily picked up by an external magnet from a liquid medium. Fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) was separated from solution by using the magnetic filter paper. PMID:24341636

Munaweera, Imalka; Aliev, Ali; Balkus, Kenneth J

2014-01-01

21

Characterization of a bioflocculant produced by Citrobacter sp. TKF04 from acetic and propionic acids.  

PubMed

A bacterial strain, TKF04, capable of producing a bioflocculant from acetic and/or propionic acids was isolated from a biofilm formed in inside a kitchen drain. It was identified as a Citrobacter based on its morphological and physiological characteristics and the partial sequences of its 16S rRNA. TKF04 produced the bioflocculant during the logarithmic phase of growth, and the optimum temperature and pH for the bioflocculant production were 30 degrees C and 7.2-10.0, respectively. It could utilize some organic acids and sugars for its growth as the sole carbon sources when yeast extract was supplemented; however, only acetate and propionate were found to be good substrates for the bioflocculant production. The crude bioflocculant could be recovered from the supernatant of the culture broth by ethanol precipitation and dialysis against deionized water. It was found to be effective for flocculation of a kaolin suspension, when added at a final concentration of 1-10 mg/l, over a wide range of pHs (2-8) and temperatures (approximately 3-95 degrees C), while the co-presence of cations (Na+, K+, Ca2+, Mg2+, Fe2+, Al3+ or Fe3+) did not enhance the flocculating activity. It could efficiently flocculate a variety of inorganic and organic suspended particles, including kaolin, diatomite, bentonite, activated carbon, soil and activated sludge. It contained glucosamine as the major component, and the molecular weight was estimated to be between 232 and 440 kDa by gel filtration. The observation that the flocculating activity was completely lost following chitinase treatment and its analysis with a Fourier transform infrared spectrometer suggested that the bioflocculant is a biopolymer structurally-similar to chitin or chitosan. PMID:16232696

Fujita, M; Ike, M; Tachibana, S; Kitada, G; Kim, S M; Inoue, Z

2000-01-01

22

Simultaneous saccharification and fermentation of cellulosic biomass to acetic acid.  

PubMed

A strain of Clostridium thermoaceticum (ATCC 49707) was evaluated for its homoacetate potential. This thermophilic anaerobe best produces acetate from glucose at pH 6.0 and 59 degrees C with a yield of 83% of theoretical. Enzyme hydrolysis of two substrates, a-cellulose and a pulp mill sludge, yielded 68% and 70% digestion, respectively. The optimum conditions for the simultaneous saccharification and fermentation (SSF) were substrate dependent: 55 degrees C, pH 6.0 for alpha-cellulose, and 55 degrees C, pH 5.5 for the pulp mill sludge. In the SSF with alpha-cellulose, the overall yield of acetate was strongly influenced by the enzyme loading. In a fed-batch operation of SSF with alpha-cellulose, an overall acetic acid yield of 60 wt% was obtained. Among the factors limiting the yields were incomplete digestion by the enzyme and the end-product inhibition. In the SSF of pulp mill sludge, inhibitors present in the sludge severely limited bacterial action. A large accumulation of glucose developed over the entire process, changing the intended SSF operation into a separate hydrolysis and fermentation operation. Despite a long lag phase of microbial growth, a terminal yield of 85% was obtained with this substrate. PMID:10849850

Borden, J R; Lee, Y Y; Yoon, H H

2000-01-01

23

Cellulose production and cellulose synthase gene detection in acetic acid bacteria.  

PubMed

The ability of acetic acid bacteria (AAB) to produce cellulose has gained much industrial interest due to the physical and chemical characteristics of bacterial cellulose. The production of cellulose occurs in the presence of oxygen and in a glucose-containing medium, but it can also occur during vinegar elaboration by the traditional method. The vinegar biofilm produced by AAB on the air-liquid interface is primarily composed of cellulose and maintains the cells in close contact with oxygen. In this study, we screened for the ability of AAB to produce cellulose using different carbon sources in the presence or absence of ethanol. The presence of cellulose in biofilms was confirmed using the fluorochrome Calcofluor by microscopy. Moreover, the process of biofilm formation was monitored under epifluorescence microscopy using the Live/Dead BacLight Kit. A total of 77 AAB strains belonging to 35 species of Acetobacter, Komagataeibacter, Gluconacetobacter, and Gluconobacter were analysed, and 30 strains were able to produce a cellulose biofilm in at least one condition. This cellulose production was correlated with the PCR amplification of the bcsA gene that encodes cellulose synthase. A total of eight degenerated primers were designed, resulting in one primer pair that was able to detect the presence of this gene in 27 AAB strains, 26 of which formed cellulose. PMID:25381910

Valera, Maria José; Torija, Maria Jesús; Mas, Albert; Mateo, Estibaliz

2014-11-11

24

Adsorption characteristics of cellulose acetate coated charcoals.  

PubMed

The permeability of cellulose triacetate membrane coated activated charcoal is enhanced by treatment with KOH. The adsorption data for creatinine in aqueous solution before and after deacetylation are given. In order to study the usefulness of hemoperfusion associated with dialysis for removal of uremic toxins, some experiments were performed on the adsorption by coated and deacetylated charcoal of molecules of various molecular weights (from 113 to 40,000). Although the adsorption capacity of uncoated charcoal was better, the coated material still shows good properties in the adsorption of glucagon (mol wt 3485). The results on in vitro experiments of vitamin B12 removal by coated charcoal cartridge and CDAK Model 3 dialyzer confirms the usefulness of adsorption technique toward medium molecular weight compounds. PMID:1176475

Denti, E; Luboz, M P; Tessore, V

1975-03-01

25

Simultaneous saccharification and fermentation of cellulosic biomass to acetic acid  

Microsoft Academic Search

Astrain of Clostridium thermoaceticum (ATCC 49707) was evaluated for its homoacetate potential. This thermophilic anaerobe best produces acetate from glucose at\\u000a pH 6.0 and 59°C with a yield of 83% of theoretical. Enzyme hydrolysis of two substrates, a-cellulose and a pulp mill sludge,\\u000a yielded 68% and 70% digestion, respectively. The optimum conditions for the simultaneous saccharification and fermentation\\u000a (SSF) were

Jacob R. Borden; Youn Y. Lee; Hyon-Hee Yoon

2000-01-01

26

Miscibility and dynamical properties of cellulose acetate/plasticizer systems.  

PubMed

Due to its biodegradability and renewability, a great interest has been devoted to investigating cellulose acetate in order to expand its potential applications. In addition, secondary cellulose acetate (CDA) could also be considered as a model system for strongly polar polymer system. The dynamical behavior of CDA is supposed to be governed by H-bonding and dipolar interaction network. Due to their high glass transition temperature, cellulose acetate-based systems are processed when blended with plasticizers. It is thus of utmost importance to study the miscibility and plasticizing effects of various molecules. We prepared CDA films via solvent casting method with diethyl phthalate as the plasticizer. Miscibility diagrams were established by calorimetry and thermo-mechanical (DMTA) experiments. Dynamical properties were analyzed by DMTA and broadband dielectric spectroscopy. We could identify the ?-relaxation of these CDA-plasticizer systems in the frequency range from 0.06Hz to 10(6)Hz, which allowed for describing the dynamics in the so-called Williams-Landel-Ferry/Vogel-Fulcher-Tammann regime. PMID:25458277

Bao, Cong Yu; Long, Didier R; Vergelati, Caroll

2015-02-13

27

Structure and Rotational Dynamics of Isoamyl Acetate and Methyl Propionate Studied by Microwave Spectroscopy  

NASA Astrophysics Data System (ADS)

The microwave spectra of a number of organic aliphatic esters have been recorded for the first time in the 3-26.5 GHz frequency range, using the molecular beam Fourier-transform microwave (MB-FTMW) spectrometer in Aachen, with an instrumental uncertainty of a few kHz for unblended lines. The combined use of ab initio quantum chemical calculations and spectral analysis allowed us to determine the spectroscopic parameters and potential barriers to internal rotation of the methyl groups for the lowest energy conformers. We will compare here the results from ab initio calculations and from two different hamiltonian methods (the XIAM and BELGI codes) for isoamyl acetate H3C-COO-(CH2)2-CH(CH3)2, an one-top internal rotor molecule with a C1 symmetry and for methyl propionate CH3CH2COOCH3 containing two inequivalent methyl tops (C3v), with different barrier heights. This study is part of a larger project which aims at determining the structures of the lowest energy conformers for a serie of organic esters and ketones which are of interest for flavour or perfume applications.

Stahl, W.; Nguyen, H. V. L.; Sutikdja, L. W.; Jelisavac, D.; Mouhib, H.; Kleiner, I.

2012-06-01

28

Amberlyst 15 as a new and reusable catalyst for the conversion of cellulose into cellulose acetate.  

PubMed

The acetylation of cellulose using sulfonated Amberlyst 15 as a new and reusable catalyst was investigated. Optimization of the acetylation process was carried out by variation in the amount of added catalyst, acetic acid, and acetic anhydride as well as the reaction conditions, which includes reaction time and reaction medium. Cellulose acetate, with a degree of substitution (DS) value of 2.38 and yield of 54.1%, was obtained under the optimized conditions and characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), and differential scanning calorimetry (DSC). The sulfonated polymer catalyst could be easily recovered by centrifugation after acetylation. Both the fresh and recovered catalysts were characterized by means of FTIR, TGA-DTG, DSC, and scanning electron microscopy (SEM), and the recovered catalyst could be successfully reused without further treatment. It was found that Amberlyst 15 possessed excellent catalytic stability, no significant changes in the DS values, and consistent yields of cellulose acetate observed over four reaction cycles. PMID:25129736

Fan, Guozhi; Liao, Chongjing; Fang, Tao; Luo, Shanshan; Song, Guangsen

2014-11-01

29

Journal of Membrane Science 205 (2002) 1121 Macrovoid pore formation in dry-cast cellulose acetate  

E-print Network

Journal of Membrane Science 205 (2002) 11­21 Macrovoid pore formation in dry-cast cellulose acetate of macrovoid (MV) pores formed during the dry-casting of cellulose acetate (CA)/acetone/water casting solutions were cast in low-gravity (low-g) (KC-135) and normal-gravity (1-g) (ground-based control) from CA

Shvartsman, Stanislav "Stas"

30

Dissolution control of mg by cellulose acetate-polyelectrolyte membranes.  

PubMed

Cellulose acetate (CA)-based membranes are used for Mg dissolution control: the permeability of the membrane is adjusted by additions of the polyelectrolyte, poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). Spin-coated films were characterized with FT-IR, and once exposed to an aqueous solution the film distends and starts acting as a membrane which controls the flow of ions and H2 gas. Electrochemical measurements (linear sweep voltammograms, open-circuit potential, and polarization) show that by altering the CA:PDMAEMA ratio the dissolution rate of Mg can be controlled. Such a control over Mg dissolution is crucial if Mg is to be considered as a viable, temporary biomedical implant material. Furthermore, the accumulation of corrosion products between the membrane and the sample diminishes the undesirable effects of high local pH and H2 formation which takes place during the corrosion process. PMID:25426707

Yliniemi, Kirsi; Wilson, Benjamin P; Singer, Ferdinand; Höhn, Sarah; Kontturi, Eero; Virtanen, Sannakaisa

2014-12-24

31

Inhibition of acetate and propionate assimilation by itaconate via propionyl-CoA carboxylase in isocitrate lyase-negative purple bacterium Rhodospirillum rubrum  

Microsoft Academic Search

Itaconate is known as a potent inhibitor of isocitrate lyase. Unexpectedly, itaconate was a strong inhibitor of acetate and propionate assimilation in isocitrate lyase-negative purple non-sulfur bacterium Rhodospirillum rubrum. It was shown that in cell extracts of R. rubrum itaconate inhibited propionyl-CoA carboxylase (PCC) activity. The participation of PCC in propionate assimilation in R. rubrum is well-documented, but the inhibition

Ivan A Berg; Ludmila V Filatova; Ruslan N Ivanovsky

2002-01-01

32

Effects of crystal orientation on cellulose nanocrystals-cellulose acetate nanocomposite fibers prepared by dry spinning.  

PubMed

This work presents the development of dry spun cellulose acetate (CA) fibers using cellulose nanocrystals (CNCs) as reinforcements. Increasing amounts of CNCs were dispersed into CA fibers in efforts to improve the tensile strength and elastic modulus of the fiber. A systematic characterization of dispersion of CNCs in the polymer fiber and their effect on the nanocomposites' mechanical properties is described. The birefringence, thermal properties, and degree of CNC orientation of the fibers are discussed. 2D X-ray diffraction was used to quantify the degree of CNC alignment within the fibers. It is shown that the CNC alignment directly correlates to the mechanical properties of the composite. Maximum improvements of 137% in tensile strength and 637% in elastic modulus were achieved. Empirical micromechanical models Halpin-Tsai equation and an orientation modified Cox model were used to predict the fiber performance and compared with experimental results. PMID:25226382

Chen, Si; Schueneman, Greg; Pipes, R Byron; Youngblood, Jeffrey; Moon, Robert J

2014-10-13

33

Methanogenesis in an Upflow Anaerobic Sludge Blanket Reactor at pH 6 on an Acetate-Propionate Mixture  

PubMed Central

High-rate anaerobic digestion can be applied in upflow anaerobic sludge blanket reactors for the treatment of various wastewaters. In upflow anaerobic sludge blanket reactors, sludge retention time is increased by a natural immobilization mechanism (viz. the formation of a granular type of sludge). When this sludge is cultivated on acid-containing wastewater, the granules mainly consist of an acetoclastic methanogen resembling Methanothrix soehngenii. This organism grows either in rods or in long filaments. Attempts to cultivate a stable sludge consisting predominantly of Methanosarcina sp. on an acetate-propionate mixture as substrate by lowering the pH from 7.5 during the start-up to approximately 6 failed. After 140 days of continuous operation of the reactor a filamentous organism resembling Methanothrix soehngenii prevailed in the sludge. The specific methanogenic activity of this sludge on acetate-propionate was optimal at pH 6.6 to 6.8 and 7.0 to 7.2, respectively. Images PMID:16346814

ten Brummeler, Erik; Pol, Look W. Hulshoff; Dolfing, Jan; Lettinga, Gatze; Zehnder, Alexander J. B.

1985-01-01

34

New approach for the production of cellulose acetate: acetylation of mechanical pulp with subsequent isolation of cellulose acetate by differential solubility  

SciTech Connect

A heretofore uninvestigated approach to the production of cellulose acetate is the acetylation of mechanical pulp with subsequent isolation of the cellulose derivative by differential solubility. The mechanical pulp is produced by refining aspen wood chips in a disc-refiner. Two conventional acetylation techniques, the fibrous and solution process, are employed to acetylate all components of the pulp. The cellulose acetate is isolated from the acetylated lignin and hemicellulose by dissolving in dichloromethane/methanol (9:1, v/v). The advantage of this new approach is that the high costs involved in using an extensively purified dissolving pulp are avoided. Both procedures yield a product that is about 84% cellulose acetate. The remaining acetylated components are lignin and hemicellulose. The average lignin content of the product from the solution process is 3.5% (1.5-4.7% range), and for the fibrous process it is 3.4% (1.2-5% range). The hemicellulose component averages 5.8% (2.5-9.1% range) for the solution process and 6.5% (3.0-8.7% range) for the fibrous process. The yield of cellulose acetate, based on the cellulose content of the original pulp and the product, is 75% for the solution process and 75-80% for the fibrous process. The cellulose acetate degree of polymerization (DP) is dependent on the sulfuric acid catalyst concentration, and on the reaction time in the case of the solution process. The product can be produced with a weight average DP from 1853 to 65 for the solution process, and 980 to 284 for the fibrous process. Applications for the product include lacquers, plastic films, and packaging.

Barkalow, D.G.

1987-01-01

35

Effect of cellulose whisker content on the properties of poly(ethylene-co-vinyl acetate)/cellulose composites.  

PubMed

The reinforcing effect of cellulose whiskers, produced from banana waste fibres, has been investigated using poly(ethylene-co-vinyl acetate) [EVA]/cellulose whisker composites. Cellulose whiskers, approximately 300 nm long and 30 nm wide, were obtained via a sulphuric acid hydrolysis method. The effects of the cellulose whisker loading on the thermal properties, mechanical properties and on the morphological features of the composites have been investigated. EVA copolymer with a vinyl acetate segment content of 40% has been used for composite fabrication. The developed composites showed superior thermal and mechanical properties relative to that of the EVA copolymer alone. Three theoretical models, namely the Halpin-Tsai model, the Kerner model and the Nicolais-Narkis model have been employed to provide a basis for the comparison of the results with the observations from the tensile investigations. PMID:23648041

Elanthikkal, Silviya; Gopalakrishnapanicker, Unnikrishnan; Varghese, Soney; Guthrie, James T; Francis, Tania

2013-06-20

36

The source of inoculum plays a defining role in the development of MEC microbial consortia fed with acetic and propionic acid mixtures.  

PubMed

Microbial electrolysis cells (MECs) can be used as a downstream process to dark fermentation to further capture electron in volatile fatty acids that remain after fermentation, improving this way the viability of the overall process. Acetic and propionic acid are common products of dark fermentation. The main objective of this work was to investigate the effect of different initial concentrations of a mixture of acetic and propionic acids on MECs microbial ecology and hydrogen production performance. To link microbial structure and function, we characterized the anode respiring biofilm communities using pyrosequencing and quantitative-PCR. The best hydrogen production rates (265mL/d/Lreactor) were obtained in the first block of experiments by MEC fed with 1500mg/L acetic acid and 250mg/L propionic acid. This reactor presents in the anode biofilm an even distribution of Proteobacteria, Firmicutes and Bacteroidetes and Arcobacter was the dominant genera. The above fact also correlated to the highest electron load among all the reactors. It was evidenced that although defined acetic and propionic acid concentrations fed affected the structure of the microbial consortia that developed at the anode, the initial inoculum played a major role in the development of MEC microbial consortia. PMID:24798298

Ruiz, Vianey; Ilhan, Zehra Esra; Kang, Dae-Wook; Krajmalnik-Brown, Rosa; Buitrón, Germán

2014-07-20

37

Photoluminescence of cellulose acetate and silica sphere composite  

NASA Astrophysics Data System (ADS)

Strong blue and green light emission has been observed from the cellulose acetate (CA) and silica sphere composite. Two different amounts of silica spheres were mixed in the CA solution to fabricate large area super-hydrophobic films. The silica spheres and CA solution ratios were 0.07:4.0 (SSCA-A) and 0.14:4.0 (SSCA-B). The milky color solution of SSCA-A and SSCA-B slowly turned to light yellow and red, respectively, with the time passed. The colors became intense yellow and red for the SSCA-A and SSCA-B, respectively, after 38 days. FTIR spectra show more absorption at 3478 cm-1 corresponding sbnd OH stretching vibration, at 2963 cm-1 caused by sbnd CH stretching vibration, at 1746 and 1713 cm-1 representing the Cdbnd O stretching vibration, and at 1100 cm-1 corresponding sbnd Rsbnd OH and Sisbnd Osbnd Si stretching vibration for CA and silica. Therefore, aged SSCA-A and SSCA-B have more sbnd OH, sbnd CH, sbnd Cdbnd O, and Sisbnd Osbnd Si groups than pure CA. UV-visible spectra show the absorption peaks at 410 nm for both SSCA-A and SSCA-B. Photoluminescence (PL) peaks were shifted toward longer wavelength with the increase of the excitation wavelength and became maximum at approximately 470 nm with excitation wavelength at 400 nm for the SSCA-A. There were two maximum luminescence peaks at 470 and 530 nm with the excitation wavelength at 400 and 470 nm, respectively, for the SSCA-B. The luminescence peak shift was due to the multiple emission center proved by the different excitation energy.

Kang, Kwang-Sun

2014-08-01

38

Influence of water on swelling and dissolution of cellulose in 1-ethyl-3-methylimidazolium acetate.  

PubMed

In this study the effect of residual coagulation medium (water) on cellulose dissolution in an ionic liquid is discussed. Solubility of dissolving grade pulp; HWP and SWP, and microcrystalline cellulose in binary solvents, mixtures of 1-ethyl-3-methyl-imidazolium acetate and water, was investigated by turbidity measurements, light microscopy, rheometry, and CP/MAS (13)C-NMR spectroscopy. The viscoelastic properties of the cellulose solutions imply that residual water affect the cellulose dissolution. However, it is not obvious that this always necessarily poses serious drawbacks for the solution properties or that the effects are as severe as previously believed. Turbidity measurements, viscosity data and crystallinity of the regenerated cellulose correlated well and an increased conversion to cellulose II was found at low water and cellulose contents with an apparent maximum of conversion at 2-5 wt% water. At high water content, above 10 wt%, dissolution and conversion was largely inhibited. PMID:24274528

Olsson, Carina; Idström, Alexander; Nordstierna, Lars; Westman, Gunnar

2014-01-01

39

Atomic Layer Deposition of Titania on Cellulose Acetate for Enhanced Hemostasis  

PubMed Central

TiO2 films may be used to alter the wettability and hemocompatibility of cellulose materials. In this study, pure and stoichiometric TiO2 films were grown using atomic layer deposition on both silicon and cellulose substrates. The films were grown with uniform thicknesses and with a growth rate in agreement with literature results. The TiO2 films were shown to profoundly alter the water contact angle values of cellulose depending upon processing characteristics. Higher rates of protein adsorption were noted on TiO2-coated cellulose acetate than on uncoated cellulose acetate. These results suggest that atomic layer deposition is an appropriate method for improving the biological properties of hemostatic agents and other blood-contacting biomaterials. PMID:21298806

Hyde, G. Kevin; Stewart, S. Michael; Scarel, Giovanna; Parsons, Gregory N.; Shih, Chun-Che; Shih, Chun-Ming; Lin, Shing-Jong; Su, Yea-Yang; Monteiro-Riviere, Nancy A.; Narayan, Roger J.

2012-01-01

40

Gluconacetobacter medellinensis sp. nov., cellulose- and non-cellulose-producing acetic acid bacteria isolated from vinegar.  

PubMed

The phylogenetic position of a cellulose-producing acetic acid bacterium, strain ID13488, isolated from commercially available Colombian homemade fruit vinegar, was investigated. Analyses using nearly complete 16S rRNA gene sequences, nearly complete 16S-23S rRNA gene internal transcribed spacer (ITS) sequences, as well as concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, allocated the micro-organism to the genus Gluconacetobacter, and more precisely to the Gluconacetobacter xylinus group. Moreover, the data suggested that the micro-organism belongs to a novel species in this genus, together with LMG 1693(T), a non-cellulose-producing strain isolated from vinegar by Kondo and previously classified as a strain of Gluconacetobacter xylinus. DNA-DNA hybridizations confirmed this finding, revealing a DNA-DNA relatedness value of 81?% between strains ID13488 and LMG 1693(T), and values <70?% between strain LMG 1693(T) and the type strains of the closest phylogenetic neighbours. Additionally, the classification of strains ID13488 and LMG 1693(T) into a single novel species was supported by amplified fragment length polymorphism (AFLP) and (GTG)5-PCR DNA fingerprinting data, as well as by phenotypic data. Strains ID13488 and LMG 1693(T) could be differentiated from closely related species of the genus Gluconacetobacter by their ability to produce 2- and 5-keto-d-gluconic acid from d-glucose, their ability to produce acid from sucrose, but not from 1-propanol, and their ability to grow on 3?% ethanol in the absence of acetic acid and on ethanol, d-ribose, d-xylose, sucrose, sorbitol, d-mannitol and d-gluconate as carbon sources. The DNA G+C content of strains ID13488 and LMG 1693(T) was 58.0 and 60.7 mol%, respectively. The major ubiquinone of LMG 1693(T) was Q-10. Taken together these data indicate that strains ID13488 and LMG 1693(T) represent a novel species of the genus Gluconacetobacter for which the name Gluconacetobacter medellinensis sp. nov. is proposed. The type strain is LMG 1693(T) (?=?NBRC 3288(T)?=?Kondo 51(T)). PMID:22729025

Castro, Cristina; Cleenwerck, Ilse; Trcek, Janja; Zuluaga, Robin; De Vos, Paul; Caro, Gloria; Aguirre, Ricardo; Putaux, Jean-Luc; Gañán, Piedad

2013-03-01

41

Effect of temperature change on the composition of the bacterial and archaeal community potentially involved in the turnover of acetate and propionate in methanogenic rice field soil.  

PubMed

The microbial community structure was investigated together with the path of methane production in Italian rice field soil incubated at moderate (35 degrees C) and high (45 degrees C) temperature using terminal restriction fragment length polymorphism and stable isotope fractionation. The structure of both the archaeal and bacterial communities differed at 35 degrees C compared with 45 degrees C, and acetoclastic and hydrogenotrophic methanogenesis dominated, respectively. Changing the incubation of the 45 degrees C soil to different temperatures (25, 30, 35, 40, 45, 50 degrees C) resulted in a dynamic change of both microbial community structure and stable isotope fractionation. In all treatments, acetate first accumulated and then decreased. Propionate was also transiently produced and consumed. It is noteworthy that acetate was also consumed at thermophilic conditions, although archaeal community composition and stable isotope fractionation indicated that acetoclastic methanogenesis did not operate. Instead, acetate must have been consumed by syntrophic acetate oxidizers. The transient accumulation and subsequent consumption of acetate at thermophilic conditions was specifically paralleled by terminal restriction fragments characteristic for clostridial cluster I, whereas those of clostridial clusters I and III, Acidaminococcaceae and Heliobacteraceae, paralleled the thermophilic turnover of both acetate and propionate. PMID:20491920

Noll, Matthias; Klose, Melanie; Conrad, Ralf

2010-08-01

42

Synthesis and characterization of cellulose acetate from rice husk: eco-friendly condition.  

PubMed

Cellulose acetate was synthesized from rice husk by using a simple, efficient, cost-effective and solvent-free method. Cellulose was isolated from rice husk (RH) using standard pretreatment method with dilute alkaline and acid solutions and bleaching with 2% H2O2. Cellulose acetate (CA) was synthesized successfully with the yield of 66% in presence of acetic anhydride and iodine as a catalyst in eco-friendly solvent-free conditions. The reaction parameters were standardized at 80 °C for 300 min and the optimum results were taken for further study. The extent of acetylation was evaluated from % yield and the degree of substitution (DS), which was determined by (1)H NMR and titrimetrically. The synthesized products were characterized with the help modern analytical techniques like FT-IR, (1)H NMR, XRD, etc. and the thermal behavior was evaluated by TGA and DSC thermograms. PMID:25129753

Das, Archana M; Ali, Abdul A; Hazarika, Manash P

2014-11-01

43

Preparation of magnetic nickel hollow fibers with a trilobe structure using cellulose acetate fibers as templates  

NASA Astrophysics Data System (ADS)

Nickel hollow fibers with trilobe shape in cross section and monolithic nickel structures composed of trilobe shaped nickel hollow fibrous networks were prepared by using cellulose acetate fibers from cigarette filters as the template. Magnetic ZSM-5/Ni hollow fibers were then fabricated by using the nickel-based hollow fibers as the support. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectrometer, and X-ray diffraction. The results indicate that nickel hollow fibers and ZSM-5/Ni hollow fibers retain the morphology of the cellulose acetate fibers, and the monolithic nickel structures can be prepared by pre-shaping the cellulose acetate fibers. The thickness of the nickel layer can be regulated by controlling the electroless plating times. The saturation magnetization and coercivity of the trilobe shaped nickel hollow fibers and ZSM-5/Ni hollow fibers are 27.78 and 21.59 emu/g and 78 and 61 Oe, respectively.

Zeng, Changfeng; Li, Ping; Zhang, Lixiong

2013-02-01

44

Evaluation of Pulps, Rayon Fibers, and Cellulose Acetate by GPC and Other Fractionation Methods  

Microsoft Academic Search

Chain length distribution of a broad spectrum of wood celluloses and cellulose derivatives was determined by gel permeation chromatography. Relative amounts of short and long chain-length species were characterized, and uniformity indices were calculated. Prefractionation was found to be a desirable approach to amplify low- and high-DP regions. This was accomplished using a 55\\/45 ethyl acetate\\/ethyl alcohol mixture to yield

W. J. Alexander; T. E. Muller

1971-01-01

45

Free-radical formation in cellulose-acetate-based dosimetric materials  

SciTech Connect

Free radicals are formed in the radiolysis of cellulose acetates at room temperature, which are products of deacetylation and the separation of hydrogen atoms in positions 1 and 2. The energy absorbed by the polymer matrix is effectively transferred to the solvent and dye molecules.

Bazhenov, A.N.; Karasev, A.L.; Bolduzev, Yu.A.; Zheleztsov, E.E.; Vannikov, A.V.

1987-05-01

46

Gaseous ammonia fluorescence probe based on cellulose acetate modified microstructured optical fiber  

Microsoft Academic Search

In this article, we report a novel fluorescent ammonia gas probe based on microstructured optical fiber (MOF) which is modified with eosin-doped cellulose acetate film. This probe was fabricated by liquid fluxion coating process. Polymer solution doped with eosin was directly inhaled into 18 array holes of MOF and then formed matrix film in them. The sensing properties of the

Lirong Peng; Xinghua Yang; Libo Yuan; Lili Wang; Enming Zhao; Fengjun Tian; Yanxin Liu

2011-01-01

47

A simple cellulose acetate membrane-based small lanes technique for protein electrophoresis.  

PubMed

Combining electrophoresis with a cellulose acetate membrane-based technique, we developed a simple and low-cost method, named cellulose acetate membrane-based small lanes (CASL), for protein electrophoresis. A home-made capillary plotter controlled by a 3D moving stage was used to create milli-to-micro channels by printing poly(dimethylsiloxane) on to a hydrophilic cellulose acetate membrane. In the hydrophilic channels, 5 nL protein mixture was separated on the basis of electro-migration under an electric field. Compared with polyacrylamide gel electrophoresis (PAGE), CASL resulted in higher protein signal intensity for separation of mixtures containing the same mass of protein. The platform was easily fabricated at low cost (approx. $0.005 for each 1-mm-wide channel), and separation of three protein mixtures was completed in 15 min. Both electrophoresis time and potential affected the separation. Rather than chromatographic separation, this method accomplished application of microchannel techniques for cellulose acetate membrane-based protein electrophoresis. It has potential in proteomic analysis, especially for rapid, low-cost, and low-volume sample analysis in clinical diagnosis. PMID:22752445

Na, Na; Liu, Tingting; Yang, Xiaojun; Sun, Binjie; Ouyang, Jenny; Ouyang, Jin

2012-08-01

48

Chelation and permeation of heavy metals using affinity membranes from cellulose acetate–chitosan blends  

Microsoft Academic Search

Affinity membranes have attracted the attention of membrane researchers especially in the field of wastewater treatment specifically in removing heavy metals by chelation from aqueous solutions. In the present work, several membranes are made from either cellulose di-acetate (CA) or CA together with chitosan (CS) solutions, the CS prepared in our lab from shrimp shells or from readymade shrimp or

M. M. Naim; H. E. M. Abdel Razek

2012-01-01

49

Chemical modification of cellulose acetate by N-(phenyl amino) maleimides: characterization and properties.  

PubMed

Cellulose acetate (CA) was modified using N-(phenyl amino) maleimides (R-APhM) where, RH or 4-NO2. The structure of the modified polymer was characterized by (13)C-NMR. The chemical modification is based on the reaction between the acetyl group of the glucopyranose ring in cellulose acetate and the proton of the amino group in N-(phenyl amino) maleimide molecule. The thermal gravimetry (TGA) was used to investigate the thermal stability of the modified polymeric samples. The modified cellulose acetate by 4-nitro (phenyl amino) maleimide (CA/4-NO2APhM) exhibits the highest thermal stability as compared to the N-(phenyl amino) maleimide (CA/APhM) and the unmodified CA. The crystallinity and morphology of the modified polymeric samples were investigated using X-ray diffraction (XRD) and emission scanning electron microscope (ESEM), respectively. The presence of N-(phenyl amino) maleimide moieties in the cellulose acetate matrix improved its mechanical property. Also, the organic nature of (R-APhM) moieties inside CA matrix reduced its wettability. PMID:24747379

Abdel-Naby, Abir S; Al-Ghamdi, Azza A

2014-07-01

50

Monitoring of cellulose depolymerization in 1-ethyl-3-methylimidazolium acetate by shear and elongational rheology.  

PubMed

The thermal stability of cellulose in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate, [emim]OAc was investigated. For this purpose, Eucalyptus urugrandis prehydrolysis kraft pulp was first dissolved in [emim]OAc by means of a vertical kneader and then stored at three different temperatures to study the time-depended behavior of the cellulose-[emim]OAc system. Cellulose depolymerization was assessed by characterizing the precipitated cellulose and the rheological behavior of the cellulose-[emim]OAc solutions. The results show decreases in the weight average molecular mass and in the shear viscosity at temperatures exceeding 60°C, which can be related to progressing degradation of cellulose in the IL upon storage at elevated temperature. The changes in behavior of the solutions under extensional stresses also attest the gradual depolymerization of cellulose. The degradation has been analyzed using appropriate kinetic models. Propyl gallate appeared to be an efficient stabilizer of the cellulose-[emim]OAc system during the dissolution step even though the mechanism has not been fully understood yet. PMID:25498646

Michud, Anne; Hummel, Michael; Haward, Simon; Sixta, Herbert

2015-03-01

51

Effects of injection of acetic acid and propionic acid for total phosphorus removal at high temperature in enhanced biological phosphorus removal process.  

PubMed

In summer, wastewater treatment plant total phosphorus (TP) removal efficiency is low in South Korea. The reason is because of high temperatures or significant fluctuation of inflow characteristics caused by frequent rainfall. Hence, this study tried to raise TP removal efficiency by injecting fixed external carbon sources in real sewage. Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) compete to occupy microorganisms at high temperature. Propionate is known to restrain GAOs. Thus, acetate and propionate were chosen as the external carbon source in this study to find out the suitable volume and ratio of carbon source which ensured the dominance of PAOs. An external carbon source was supplied in the anaerobic reactor of the biological phosphorus removal process at high temperature (above 25 °C). TP removal efficiency was improved by injecting an external carbon source compared to that without an external carbon source. Also, it remained relatively stable when injecting an external carbon source, despite the variation in temperature. TP removal efficiency was the highest when injecting acetate and propionate in the proportion of 2:1 (total concentration as chemical oxygen demand (COD) is 12 mg/L in influent). PMID:24845316

Ki, C Y; Kwon, K H; Kim, S W; Min, K S; Lee, T U; Park, D J

2014-01-01

52

Utilization of Vinegar for Isolation of Cellulose Producing Acetic Acid Bacteria  

NASA Astrophysics Data System (ADS)

Wastes of traditionally fermented Turkish vinegar were used in the isolation of cellulose producing acetic acid bacteria. Waste material was pre-enriched in Hestrin-Schramm medium and microorganisms were isolated by plating dilution series on HS agar plates The isolated strains were subjected to elaborate biochemical and physiological tests for identification. Test results were compared to those of reference strains Gluconacetobacter xylinus DSM 46604, Gluconacetobacter hansenii DSM 5602 and Gluconacetobacter liquefaciens DSM 5603. Seventeen strains, out of which only three were found to secrete the exopolysaccharide cellulose. The highest cellulose yield was recorded as 0.263±0.02 g cellulose L-1 for the strain AS14 which resembled Gluconacetobacter hansenii in terms of biochemical tests.

Aydin, Y. Andelib; Aksoy, Nuran Deveci

2010-06-01

53

Beneficial Effect of Acetic Acid on the Xylose Utilization and Bacterial Cellulose Production by Gluconacetobacter xylinus.  

PubMed

In this work, acetic acid was found as one promising substrate to improve xylose utilization by Gluconacetobacter xylinus CH001. Also, with the help of adding acetic acid into medium, the bacterial cellulose (BC) production by G. xylinus was increased significantly. In the medium containing 3 g l(-1) acetic acid, the optimal xylose concentration for BC production was 20 g l(-1). In the medium containing 20 g l(-1) xylose, the xylose utilization and BC production by G. xylinus were stimulated by acetic acid within certain concentration. The highest BC yield (1.35 ± 0.06 g l(-1)) was obtained in the medium containing 20 g l(-1) xylose and 3 g l(-1) acetic acid after 14 days. This value was 6.17-fold higher than the yield (0.21 ± 0.01 g l(-1)) in the medium only containing 20 g l(-1) xylose. The results analyzed by FE-SEM, FTIR, and XRD showed that acetic acid affected little on the microscopic morphology and physicochemical characteristics of BC. Base on the phenomenon observed, lignocellulosic acid hydrolysates (xylose and acetic acid are main carbon sources present in it) could be considered as one potential substrate for BC production. PMID:24891733

Yang, Xiao-Yan; Huang, Chao; Guo, Hai-Jun; Xiong, Lian; Luo, Jun; Wang, Bo; Chen, Xue-Fang; Lin, Xiao-Qing; Chen, Xin-De

2014-09-01

54

Performance of cellulose acetate butyrate membranes in hyperfiltration of sodium chloride and urea feed solution  

NASA Technical Reports Server (NTRS)

Cellulose acetate butyrate (CAB) membranes are shown to give high salt and urea rejection with water flux of about 3 gallons/sq ft per day at 600 psig. Membranes prepared from a formulation containing glyoxal show a significant increase in flux and decrease in salt and urea rejection with drying time. Zero drying time gives maximum urea and salt rejection and is therefore most suitable for hyperfiltration of sodium chloride and urea feed solution.

Wydeven, T.; Leban, M.

1973-01-01

55

Studies on pre-hump and main fractions of cellulose-2,5-acetate in acetone  

Microsoft Academic Search

Technical cellulose-2.5-acetates (CA 2.5) were characterized regarding their carbohydrate composition in comparison to the raw material. The association of the CA 2.5 samples in acetone was studied by size exclusion chromatography (SEC) using various acetone grades and styrene divinylbenzene copolymer columns. In HPLC grade acetone with and without addition of 1% water up to three different pre-humps eluted in front

Bodo Saake; Martin Zenker; Armin Stein; Jürgen Puls

2006-01-01

56

Cellulose acetate-coated ?-alumina ceramic composite tubular membranes for wastewater treatment  

Microsoft Academic Search

A novel method was developed to reduce the pore size of microporous ceramic tubular membranes by coating their inner surfaces using cellulose acetate solution forming a thin coating of ~35 ?m. Three tubular membrane configurations viz., 1-channel, 7-channel and 19-channel, hollow tubular having an identical pore size of 1.2 ?m and apparent porosity of 35 vol.% were tested for pollutants

S. K. Nataraj; S. Roy; M. B. Patil; M. N. Nadagouda; W. E. Rudzinski; T. M. Aminabhavi

2011-01-01

57

Development of polyion complex membranes based on cellulose acetate modified by oxygen plasma treatment for pervaporation  

Microsoft Academic Search

Cellulose acetate (CA) membrane was modified with ultra-thin polyion complex (PIC) layers, and the pervaporation performance for water–ethanol mixture was investigated. Introduction of oxygen-containing anionic groups onto the surface of the CA membrane was attempted by the oxygen plasma treatment, and was confirmed by the electron spectroscopy for chemical analysis (ESCA). The formation of an ultra-thin PIC layer on the

Samuel P Kusumocahyo; Toshiyuki Kanamori; Takashi Iwatsubo; Kimio Sumaru; Toshio Shinbo

2002-01-01

58

Synthesis and characterization of hydrogels from cellulose acetate by esterification crosslinking with EDTA dianhydride.  

PubMed

Hydrogels were prepared from cellulose acetate with a degree substitution (DS) 2.5 dissolved in dimethylformamide by esterification crosslinking with Ethylenediaminetetraacetic dianhydride (EDTAD) catalyzed by triethylamine. Subsequent conversion of the unreacted carboxyl groups to sodium carboxylates by the addition of aqueous NaHCO3 was performed to enhance the water affinity of the gels. The absorbency of the products was strongly dependent on the amount of EDTAD that was esterified to cellulose acetate, and the highest absorbency was observed for the hydrogel composed of approximately 0.36 molecules of EDTAD per repeat unit of cellulose acetate. The hydrogels were synthesized with different degrees of crosslinking and were analyzed by IR spectral (FTIR), near infrared (NIR), thermogravimetry analysis (TG and DTG), and crosslink density evaluation by Flory-Rehner theory. The hydrogels have synthesized with molar ratios EDTAD/OH groups: [1/1], [1/2], and [0.1/1]. The capacity for water absorbency was studied and compared with the water absorbency of the CA. PMID:25263890

Senna, André M; Novack, Kátia Monteiro; Botaro, Vagner R

2014-12-19

59

Water in polymer membranes. 4. Raman scattering from cellulose acetate films  

SciTech Connect

Raman scattering was observed from thin film optical waveguides of cellulose acetate exposed to water vapor from 0% to 100% relative humidity (RH), and from dilute solutions of water in methyl acetate. Spectra of cellulose acetate (CA398, 39.8% acetyl) at low RH and cellulose triacetate (CTA) at low and high RH are consistent with the presence of water monomers that are weakly hydrogen bonded to acetyl C=O groups. Differences between the spectra of water in CA398 and CTA at low RH are attributed to sequential hydrogen bonding involving OH groups in CA398. At high RH, CA398 and CTA (to a lesser extent) show bands attributed to water/water interactions that are similar to those found in sequentially hydrogen-bonded hydrates. CA398 films that are annealed at high temperatures exhibit decreased water/water interactions at high RH. Exposure of CA398 films to D/sub 2/O converts > 90% of all polymer OH groups to OD groups. This indicates that water is accessible to nearly all regions of the polymer containing OH groups. Annealing does not alter this accessibility but does reduce the total water content by roughly half, at 100% RH. Hydrogen-bonded C=O groups are associated with a band centered at 1731 cm/sup -1/ which increases in intensity with increasing water content in the film but does not shift in frequency. 38 references, 16 figures, 1 table.

Scherer, J.R.; Bailey, G.F.; Kint, S.; Young, R.; Malladi, D.P.; Bolton, B.

1985-01-17

60

Volumetric Investigations on Interactions of Acidic\\/Basic Amino Acids with Sodium Acetate, Sodium Propionate and Sodium Butyrate in Aqueous Solutions  

Microsoft Academic Search

The apparent molar volumes, V\\u000a \\u000a ?\\u000a , of L-aspartic acid, L-glutamic acid, L-lysine monohydrate and L-arginine in water and in aqueous (0.1, 0.25, 0.5 and 1.0)\\u000a mol?kg?1 sodium acetate and sodium propionate, and (0.1, 0.25 and 0.5) mol?kg?1 sodium butyrate solutions have been determined at 288.15, 298.15, 308.15 and 318.15 K from density measurements. The partial\\u000a molar volumes at infinite dilution, V\\u000a 2o, obtained

Tarlok S. Banipal; Kultar Singh; Parampaul K. Banipal

2007-01-01

61

Cellulose acetate hollow fiber ultrafiltration membranes made from CA\\/PVP 360 K\\/NMP\\/water  

Microsoft Academic Search

Hydrophilic hollow fiber ultrafiltration (UF) membranes have been prepared from a new dope solution containing cellulose acetate (CA)\\/poly(vinyl pyrrolidone) (PVP 360K)\\/N-methyl-2-pyrrolidone (NMP)\\/water with a mass ratio of 19.0\\/5.0\\/74.8\\/1.2 by using a dry-jet wet spinning process. The effect of air-gap length was studied. The as-spun fibers were post-treated by means of a hypochlorite solution of 200mgl?1 (200ppm) over different duration. The

Jian-Jun Qin; Ying Li; Leng-Siang Lee; Hsiaowan Lee

2003-01-01

62

Bio-composites based on cellulose acetate and kenaf fibers: Processing and properties  

NASA Astrophysics Data System (ADS)

Research on bio-composites is important because of its positive environmental impact. In this study, bio-composites based on plasticised cellulose acetate and kenaf fibers were prepared by solution casting and compression moulding methods. The fibers were chemically treated to remove lignin, hemicellulose and impurities. Mechanical, morphological and thermal properties of the bio-composites were studied. Introduction of chopped kenaf fibers increased the storage modulus. The flexural storage modulus of the composite was affected with the introduction of moisture. Moisture behaved similar to the effect of plasticiser, it reduced the modulus.

Pang, C.; Shanks, R. A.; Daver, F.

2014-05-01

63

Carboxymethyl Cellulose Acetate Butyrate: A Review of the Preparations, Properties, and Applications  

PubMed Central

Carboxymethyl cellulose acetate butyrate (CMCAB) has gained increasing importance in several fields, particularly in coating technologies and pharmaceutical research. CMCAB is synthesized by esterification of CMC sodium salt with acetic and butyric anhydrides. CMCAB mixed esters are relatively high molecular weight (MW) thermoplastic polymers with high glass transition temperatures (Tg). CMCAB ester is dispersible in water and soluble in a wide range of organic solvents, allowing varied opportunity to the solvent choice. It makes application of coatings more consistent and defect-free. Its ability to slow down the release rate of highly water-soluble compounds and to increase the dissolution of poorly soluble compounds makes CMCAB a unique and potentially valuable tool in pharmaceutical and amorphous solid dispersions (ASD) formulations.

Kamel, Samir; Salama, Ahmed; Sarhan, Hebat-Allah

2014-01-01

64

The role of cellulose acetate as a matrix for aggregation of pseudoisocyanine iodide: absorption and emission studies.  

PubMed

Films of pseudoisocyanine iodide in a cellulose acetate matrix were prepared by spin coating and characterized by UV/Vis absorption and fluorescence spectroscopies. The comparison with self-supported films of the same dye enabled analysing the role of the matrix in the aggregation of pseudoisocyanine iodide ([PIC]I). It was proved that cellulose acetate is a suitable support for [PIC]I J-aggregates, which form during spinning, as shown by a very sharp J-band in the absorption spectra. This indicates a perfect coherence between stacked monomers in the supported J-aggregates. It was possible to individualize the emission spectrum of [PIC]I J-aggregates in cellulose acetate, by decomposition of the steady-state fluorescence spectra of the films. The dependence on the excitation wavelength of the relative emission intensities of monomers and J-aggregates, for lambda(em) = 587 nm, lead to confirm that the latter species have an absorption maximum at approximately 500 nm in cellulose acetate. Finally, polarised absorption spectra of films obtained by the vertical spin coating technique showed that cellulose acetate allows a partial orientation of J-aggregates. PMID:11506031

Brito de Barros, R; Ilharco, L M

2001-08-01

65

Saccharification behavior of cellulose acetate during enzymatic processing for microbial ethanol production.  

PubMed

This study was conducted to realize the potential application of cellulose acetate to enzymatic processing, followed by microbial ethanol fermentation. To eliminate the effect of steric hindrance of acetyl groups on the action of cellulase, cellulose acetate was subjected to deacetylation in the presence of 1N sodium hydroxide and a mixture of methanol/acetone, yielding 88.8-98.6% at 5-20% substrate loadings during a 48h saccharification at 50°C. Ethanol fermentation using Saccharomyces cerevisiae attained a high yield of 92.3% from the initial glucose concentration of 44.2g/L; however, a low saccharification yield was obtained at 35°C, decreasing efficiency during simultaneous saccharification and fermentation (SSF). Presaccharification at 50°C prior to SSF without increasing the total process time attained the ethanol titers of 19.8g/L (5% substrate), 38.0g/L (10% substrate), 55.9g/L (15% substrate), and 70.9g/L (20% substrate), which show a 12.0-16.2% improvement in ethanol yield. PMID:24514162

Hama, Shinji; Nakano, Kohsuke; Onodera, Kaoru; Nakamura, Masashi; Noda, Hideo; Kondo, Akihiko

2014-04-01

66

Production and characterization of cornstarch/cellulose acetate/silver sulfadiazine extrudate matrices.  

PubMed

The production and evaluation of cornstarch/cellulose acetate/silver sulfadiazine extrudate matrices are reported herein. The matrices were melt extruded under nine different conditions, altering the temperature and the screw speed values. The surface morphology of the matrices was examined by scanning electron microscopy. The micrographs revealed the presence of non-melted silver sulfadiazine microparticles in the matrices extruded at lower temperature and screw speed values. The thermal properties were evaluated and the results for both the biopolymer and the drug indicated no thermal degradation during the melt extrusion process. The differential scanning analysis of the extrudate matrices showed a shift to lower temperatures for the silver sulfadiazine melting point compared with the non-extruded drug. The starch/cellulose acetate matrices containing silver sulfadiazine demonstrated significant inhibition of the growth of Pseudomonas aeruginosa and Staphylococcus aureus. In vivo inflammatory response tests showed that the extrudate matrices, with or without silver sulfadiazine, did not trigger chronic inflammatory processes. PMID:25280700

Zepon, Karine Modolon; Petronilho, Fabricia; Soldi, Valdir; Salmoria, Gean Vitor; Kanis, Luiz Alberto

2014-11-01

67

SEM study of the morphology of asymmetric cellulose acetate membranes produced from recycled agro-industrial residues: sugarcane bagasse and mango seeds  

Microsoft Academic Search

Cellulose, obtained both from sugarcane bagasse and mango seeds, was used for synthesizing cellulose acetate in order to produce\\u000a asymmetric membranes. These were compared to membranes of commercial cellulose acetate (Rhodia). All produced membranes were\\u000a asymmetric, characterized by the presence of a dense skin and a porous support. Differences regarding the morphology of the\\u000a surfaces as well as of the

Moacir Fernandes Ferreira Júnior; Elaine Angélica Ribeiro Mundim; Guimes Rodrigues Filho; Carla da Silva Meireles; Daniel Alves Cerqueira; Rosana Maria Nascimento de Assunção; Marcos Marcolin; Mara Zeni

2011-01-01

68

Dehydration of water/pyridine mixtures by pervaporation using cellulose acetate/ polyacrylonitrile blend membrane.  

PubMed

Cellulose acetate/ polyacrylonitrile (CA/PAN) membranes were prepared and used to separate pyridine / water mixtures by pervaporation. The membranes were characterized through SEM. The effects of feed concentration, operation temperature and downstream pressure on the separation performance were evaluated. Experimental results indicated the increase of operation temperature could raise the permeation flux and the separation factor, while increasing feed concentration and downstream pressure would raise the separation factor and decrease the permeation flux. Under the conditions that pyridine solution was 99 wt.%, operation temperature was 323 K and downstream pressure was 20 mmHg, the CA/PAN blend membrane showed its best separation performance that the permeation flux was 56.g.m-2 h-1 and the separation factor was 182. PMID:21866770

Lv, J H; Xiao, G M

2011-01-01

69

Ionic liquid assisted electrospun cellulose acetate fibers for aqueous removal of triclosan.  

PubMed

The cellulose acetate (CA) membrane prepared via electrospun was innovatively utilized as fiber-adsorbent for the separation of aqueous triclson (TCS). It was found that the presence of the room temperature ionic liquid (RTIL) in the precursor amplified electric force toward the CA-solution, thereby benefiting the formation of CA fibers. The as-spun CA fibers exhibit excellent adsorptive performance toward TCS, with fast adsorption kinetics, and the maximum adsorption capacity achieved to 797.7 mg g(-1), which established much better performance in contrast to conventional adsorbents. We proposed that the adsorption of TCS onto CA fibers was primarily facilitated by the hydrogen bonding between the abundant carbonyl, hydroxyl groups of CA surface, and the hydrogen atoms of phenol functional groups in TCS molecular. PMID:25595432

Zhang, Gong; Sun, Meng; Liu, Yang; Liu, Huijuan; Qu, Jiuhui; Li, Jinghong

2015-02-10

70

Pervaporation of water and ethanol using a cellulose acetate butyrate membrane  

SciTech Connect

Okada and Matsuura's transport equations for pervaporation give rise to three fundamental parameters, namely, interfacial saturation vapor pressure P*, liquid transport parameter A/[delta], and vapor transport parameter B/[delta]. The effects of the chemical nature of the membrane material and the upstream operating pressures of 101.3 and 303.9 kPa on the above parameters were investigated from the pervaporation data at laboratory temperature (24 C) for water and ethanol using a cellulose acetate butyrate membrane. The results show that the P. values are essentially unaffected by the upstream pressure, and that they are generally higher than the literature values of saturation vapor pressure at 24 C. Further, the values for A/[delta] and B/[delta] tend to increase with increased upstream pressure for both systems studied. These results are discussed.

Wu, W.S.; Lau, W.W.Y.; Rangaiah, G.P.; Sourirajan, S. (National Univ. of Singapore (Singapore). Dept. of Chemical Engineering)

1993-10-15

71

Structure and properties of hydroxyapatite/hydroxyethyl cellulose acetate composite films.  

PubMed

The main aim of this research work was to develop a new inorganic-organic film. Hydroxyapaptite (HAp) particles that represent the inorganic phase was mixed well with hydroxyethyl cellulose acetate (HECA), which representing the organic phase and then the inorganic-organic films were fabricated by evaporating of the solvent. The structure as well as the properties of the formed films were characterized using different analytical tools such as field emission scanning electron microscopy (FEG-SEM), thermo-gravimetric analysis (TGA), Fourier transform infra-red (FT-IR) spectroscopy. The obtained results revealed that, the HAp nanoparticles was well dispersed and well immobilized throughout the formed films. This can be attributed to the role of the nano- and micropores in the HECA substrate. In addition, a strong interaction occurred between HAp and HECA matrix. The results showed also good thermal stability and miscibility as well. PMID:25439882

Azzaoui, K; Mejdoubi, E; Lamhamdi, A; Zaoui, S; Berrabah, M; Elidrissi, A; Hammouti, B; Fouda, Moustafa M G; Al-Deyab, Salem S

2015-01-22

72

Fabrication of Tunable Submicro- or Nano-structured Polyethylene Materials form Immiscible Blends with Cellulose Acetate Butyrate  

Technology Transfer Automated Retrieval System (TEKTRAN)

Low density polyethylene (LDPE) was prepared into micro- or submicro-spheres or nanofibers via melt blending or extrusion of cellulose acetate butyrate (CAB)/LDPE immiscible blends and subsequent removal of the CAB matrix. The sizes of the PE spheres or fibers can be successfully controlled by varyi...

73

Preparation, characterization and release of amoxicillin from cellulose acetate and poly(vinyl pyrrolidone) coaxial electrospun fibrous membranes  

Microsoft Academic Search

Electrospinning is a method that has been used to prepare polymeric fibers, with diameters ranging from nanometers to a micrometer of polymers such as cellulose acetate (CA) and poly(vinyl pyrrolidone) (PVP), and to develop membranes with applications in microencapsulation, for controlled release of drugs and for chemical and biological sensors. This work shows the feasibility and optimal conditions for the

M. M. Castillo-Ortega; A. Nájera-Luna; D. E. Rodríguez-Félix; J. C. Encinas; F. Rodríguez-Félix; J. Romero; P. J. Herrera-Franco

2011-01-01

74

Synthesis and antiradical/antioxidant activities of caffeic acid phenethyl ester and its related propionic, acetic, and benzoic acid analogues.  

PubMed

Caffeic acid phenethyl ester (CAPE) is a bioactive component isolated from propolis. A series of CAPE analogues was synthesized and their antiradical/antioxidant effects analyzed. The effect of the presence of the double bond and of the conjugated system on the antioxidant effect is evaluated with the analogues obtained from 3-(3,4-dihydroxyphenyl) propanoic acid. Those obtained from 2-(3,4-dihydroxyphenyl) acetic acid and 3,4-dihydroxybenzoic acid allow the evaluation of the effect of the presence of two carbons between the carbonyl and aromatic system. PMID:23222926

LeBlanc, Luc M; Paré, Aurélie F; Jean-François, Jacques; Hébert, Martin J G; Surette, Marc E; Touaibia, Mohamed

2012-01-01

75

NMR characterization of cellulose acetate: Chemical shift assignments, substituent effects, and chemical shift additivity.  

PubMed

A series of cellulose acetates (CA) with degrees of substitution (DS) ranging from 2.92-0.92 dissolved in dimethylsulfoxide (DMSO)-d6 and cellulose dissolved in tetrabutylammonium fluoride (TBAF)/DMSO-d6 were investigated by two-dimensional NMR spectroscopy. The NMR spectroscopic analysis allowed the determination of the (1)H and (13)C NMR chemical shifts of the eight anhydroglucose units (AGUs) that contain CA: 2,3,6-tri-, 2,3-di-, 2,6-di-, 3,6-di-, 2-mono-, 3-mono-, 6-mono-, and unacetylated AGUs. A comparative analysis of the chemical shift data revealed the substituent effect of acetyl groups at the 2-, 3-, and 6-positions on the (1)H and (13)C nuclei in the same AGU. In addition, chemical shift additivity could be applied to the (1)H and (13)C chemical shifts of CA because the chemical shifts of the diacetylated and triacetylated AGUs could be almost completely explained by the acetyl substituent effects at the 2-, 3-, and 6-positions. PMID:25542112

Kono, Hiroyuki; Hashimoto, Hisaho; Shimizu, Yuuichi

2015-03-15

76

Rapid synthesis of cellulose esters by transesterification of cellulose with vinyl esters under the catalysis of NaOH or KOH in DMSO.  

PubMed

Traditionally, a long reaction time was required in the synthesis of cellulose esters (CEs). In this work, dimethyl sulfoxide (DMSO)/aqueous NaOH or KOH was introduced as an efficient reaction system for rapidly synthesizing CEs by transesterification. Surprisingly, cellulose could react with vinyl acetate, vinyl propionate, and vinyl butyrate and synthesized cellulose acetate, cellulose propionate, and cellulose butyrate with a high degree of substitution (2.14-2.34) in 5 min, which was in sharp contrast to hours of existing methods. The effects of solvents, catalysts, and esterifying agents on the synthesis of CEs were comparatively investigated to better understand this method. The structure and thermal properties of obtained CEs were characterized by Fourier transform infrared (FTIR) and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopies and differential scanning calorimetry. Results from these spectra confirmed the successful synthesis of these CEs. Furthermore, these CEs showed similar thermal properties compared to products obtained from other methods. PMID:23414423

Cao, Xuefei; Sun, Shaoni; Peng, Xinwen; Zhong, Linxin; Sun, Runcang; Jiang, Dan

2013-03-13

77

Cellulose acetate/hydroxyapatite/chitosan coatings for improved corrosion resistance and bioactivity.  

PubMed

Cellulose acetate (CA) nanofibers were deposited on stainless steel plates by electrospinning technique. The composite of hydroxyapatite (HAP) nanoparticles and chitosan (CHI) was coated subsequently by dip-coating. The structure and morphology of the obtained coatings were investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The stability of the coatings in physiological environment was studied using electrochemical polarization and impedance spectroscopy. The CA nanofibers were embedded in the HAP/CHI coating and the resulted composite film was densely packed and uniform on the substrate. The in vitro biomineralization study of the coated samples immersed in simulated body fluid (SBF) confirmed the formation ability of bone-like apatite layer on the surface of HAP-containing coatings. Furthermore, the coatings could provide corrosion resistance to the stainless steel substrate in SBF. The electrochemical results suggested that the incorporation of CA nanofibers could improve the corrosion resistance of the HAP/CHI coating. Thus, biocompatible CA/HAP/CHI coated metallic implants could be very useful in the long-term stability of the biomedical applications. PMID:25686946

Zhong, Zhenyu; Qin, Jinli; Ma, Jun

2015-04-01

78

Comparative evaluation of Chitosan, Cellulose Acetate, and Polyethersulfone Nanofiber Scaffolds for Neural Differentiation  

PubMed Central

Based on accumulating evidence that the 3D topography and the chemical features of a growth surface influence neuronal differentiation, we combined these two features by evaluating the cytotoxicity, proliferation, and differentiation of the rat PC12 line and human neural stem cells (hNSCs) on chitosan (CS), cellulose acetate (CA), and polyethersulfone (PES)-derived electrospun nanofibers that had similar diameters, centered in the 200 to 500 nm range. None of the nanofibrous materials were cytotoxic compared to 2D (e.g., flat surface) controls; however, proliferation generally was inhibited on the nanofibrous scaffolds although to a lesser extent on the polysaccharide-derived materials compared to PES. In an exception to the trend towards slower growth on the 3D substrates, hNSCs differentiated on the CS nanofibers proliferated faster than the 2D controls and both cell types showed enhanced indication of neuronal differentiation on the CS scaffolds. Together, these results demonstrate beneficial attributes of CS for neural tissue engineering when this polysaccharide is used in the context of the defined 3D topography found in electrospun nanofibers. PMID:24274534

Du, Jian; Tan, Elaine; Kim, Hyo Jun; Zhang, Allen; Bhattacharya, Rahul; Yarema, Kevin J

2013-01-01

79

Characterization of conducting cellulose acetate based polymer electrolytes doped with "green" ionic mixture.  

PubMed

Polymer electrolytes were developed by solution casting technique utilizing the materials of cellulose acetate (CA), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and deep eutectic solvent (DES). The DES is synthesized from the mixture of choline chloride and urea of 1:2 ratios. The increasing DES content well plasticizes the CA:LiTFSI:DES matrix and gradually improves the ionic conductivity and chemical integrity. The highest conducting sample was identified for the composition of CA:LiTFSI:DES (28 wt.%:12 wt.%:60 wt.%), which has the greatest ability to retain the room temperature ionic conductivity over the entire 30 days of storage time. The changes in FTIR cage peaks upon varying the DES content in CA:LiTFSI:DES prove the complexation. This complexation results in the collapse of CA matrix crystallinity, observed from the reduced intensity of XRD diffraction peaks. The DES-plasticized sample is found to be more heat-stable compared to pure CA. Nevertheless, the addition of DES diminishes the CA:LiTFSI matrix's heat-resistivity but at the minimum addition the thermal stability is enhanced. PMID:23044100

Ramesh, S; Shanti, R; Morris, Ezra

2013-01-01

80

Cyclodextrin-grafted electrospun cellulose acetate nanofibers via “Click” reaction for removal of phenanthrene  

NASA Astrophysics Data System (ADS)

Beta-cyclodextrin (?-CD) functionalized cellulose acetate (CA) nanofibers have been successfully prepared by combining electrospinning and “click” reaction. Initially, ?-CD and electrospun CA nanofibers were modified so as to be azide-?-CD and propargyl-terminated CA nanofibers, respectively. Then, “click” reaction was performed between modified CD molecules and CA nanofibers to obtain permanent grafting of CDs onto nanofibers surface. It was observed from the SEM image that, while CA nanofibers have smooth surface, there were some irregularities and roughness at nanofibers morphology after the modification. Yet, the fibrous structure was still protected. ATR-FTIR and XPS revealed that, CD molecules were successfully grafted onto surface of CA nanofibers. The adsorption capacity of ?-CD-functionalized CA (CA-CD) nanofibers was also determined by removing phenanthrene (polycyclic aromatic hydrocarbons, PAH) from its aqueous solution. Our results indicate that CA-CD nanofibers have potential to be used as molecular filters for the purpose of water purification and waste water treatment by integrating the high surface area of nanofibers with inclusion complexation property of CD molecules.

Celebioglu, Asli; Demirci, Serkan; Uyar, Tamer

2014-06-01

81

Antimicrobial electrospun nanofibers of cellulose acetate and polyester urethane composite for wound dressing.  

PubMed

In this study, a series of nanofibrous membranes were prepared from cellulose acetate (CA) and polyester urethane (PEU) using coelectrospinning or blend-electrospinning. The drug release, in vitro antimicrobial activity and in vivo wound healing performance of the nanofiber membranes were evaluated for use as wound dressings. To prevent common clinical infections, an antimicrobial agent, polyhexamethylene biguanide (PHMB) was incorporated into the electrospun fibers. The presence of CA in the nanofiber membrane improved its hydrophilicity and permeability to air and moisture. CA fibers became slightly swollen upon contacting with liquid phase. CA not only increased the liquid uptake but also created a moist environment for the wound, which accelerated wound recovery. PHMB release dynamics of the membranes was controlled by the structure and component ratios of the membranes. The lower ratio of CA: PEU helped to preserve the physical and thermal properties of the membranes, and also reduced the burst release effectively and slowed down diffusion of PHMB during in vitro tests. The controlled-diffusion membranes exerted long-term antimicrobial effect for wound healing. PMID:22692845

Liu, Xin; Lin, Tong; Gao, Yuan; Xu, Zhiguang; Huang, Chen; Yao, Gang; Jiang, Linlin; Tang, Yanwei; Wang, Xungai

2012-08-01

82

Preparation and characterization of nifedipine-loaded cellulose acetate butyrate based microspheres and their controlled release behavior  

Microsoft Academic Search

Eudragit L100\\/cellulose acetate butyrate blend microspheres were prepared by solvent evaporation technique using poly(vinyl\\u000a alcohol) as an emulsifying agent nifedipine (NFD) was successfully loaded into these microspheres. The effect of experimental\\u000a variables such as ratio of blend ratio on NFD encapsulation efficiency, release rate, size, and morphology of the microspheres\\u000a has been investigated. Scanning electron micrographs indicated the formation of

V. Ramesh Babu; K. S. V. Krishna Rao; Yong Ill Lee

2010-01-01

83

Cellulose acetate graft copolymers with nano-structured architectures: Application to the purification of bio-fuels by pervaporation  

Microsoft Academic Search

In Europe, ethyl tert-butyl ether (ETBE) is currently considered as one of the most promising bio-fuels when it is obtained from bio-ethanol. Nevertheless, its industrial synthesis process leads to an azeotropic mixture containing 20wt% of ethanol which has to be removed for fuel applications. In this work, new graft copolymers cellulose acetate-g-poly(methyl diethylene glycol methacrylate) are considered for the purification

M. Billy; A. Ranzani Da Costa; P. Lochon; R. Clément; M. Dresch; A. Jonquières

2010-01-01

84

Cellulose  

Technology Transfer Automated Retrieval System (TEKTRAN)

This article covers nomenclature, sources, preparation, uses, microcrystalline cellulose, structural chemistry, reactions, solvents, and liquid crystals. Cellulose for commercial purposes comes mostly from wood and cotton, whereas cellulose for research comes from bacteria, algae, and ramie (also a...

85

Preparation of fluoro derivative of cellulose acetate with (1,1,1,3,3,3)-hexafluoro-2-propanol by Mitsunobu reaction and its characterization  

Microsoft Academic Search

Novel ethers of cellulose acetate with (1,1,1,3,3,3)-hexafluoro-2-propanol (HFP) were prepared at an ambient condition using the Mitsunobu reaction. Reaction time was varied from 27h to 93h to identify the effect of the amount of fluorination. Based on energy dispersive X-ray spectroscopy analysis, the degree of substitution of HFP on the cellulose acetate was found to be 0.24 for 93h and

Amalraj John; Yi Chen; Hyun-U Ko; Jaehwan Kim

2011-01-01

86

Expression and characterization of a thermostable acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis involved in the degradation of insoluble cellulose acetate.  

PubMed

A thermostable acetylxylan esterase gene, TTE0866, which catalyzes the deacetylation of cellulose acetate, was cloned from the genome of Caldanaerobacter subterraneus subsp. tengcongensis. The pH and temperature optima were 8.0 and 60 °C. The esterase was inhibited by phenylmethylsulfonyl fluoride. A mixture of the esterase and cellulolytic enzymes efficiently degraded insoluble cellulose acetate with a higher degree of substitution. PMID:24317066

Moriyoshi, Kunihiko; Koma, Daisuke; Yamanaka, Hayato; Sakai, Kiyofumi; Ohmoto, Takashi

2013-01-01

87

Optimization of moisture content for wheat seedling germination in a cellulose acetate medium for a space flight experiment  

NASA Astrophysics Data System (ADS)

The Porous Tube Plant Nutrient Delivery System (PTPNDS), a hydrophilic, microporous ceramic tube hydroponic system designed for microgravity, will be tested in a middeck locker of the Space Shuttle. The flight experiment will focus on hardware operation and assess its ability to support seed germination and early seedling growth in microgravity. The water controlling system of the PTPNDS hardware has been successfully tested during the parabolic flight of the KC-135. One challenge to the development of the space flight experiment was to devise a method of holding seeds to the cylindrical porous tube. The seed-holder must provide water and air to be seed, absorb water from the porous tube, withstand sterilization, provide a clear path for shoots and roots to emerge, and be composed of flight qualified materials. In preparation for the flight experiment, a wheat seed-holder has been designed that utilizes a cellulose acetate plug to facilitate imbibition and to hold the wheat seeds in contact with the porous tube in the correct orientation during the vibration of launch and the microgravity environment of orbit. Germination and growth studies with wheat at a range of temperatures showed that optimal moisture was 78% (by weight) in the cellulose acetate seed holders. These and other design considerations are discussed.

Johnson, C. F.; Dreschel, T. W.; Brown, C. S.; Wheeler, R. M.

1996-01-01

88

Functional analysis of the carbohydrate-binding module of an esterase from Neisseria sicca SB involved in the degradation of cellulose acetate.  

PubMed

An esterase gene from Neisseria sicca SB encoding CaeA, which catalyzes the deacetylation of cellulose acetate, was cloned. CaeA contained a putative catalytic domain of carbohydrate esterase family 1 and a carbohydrate-binding module (CBM) family 2. We constructed two derivatives, with and without the CBM of CaeA. Binding assay indicated that the CBM of CaeA had an affinity for cellulose. PMID:20834142

Moriyoshi, Kunihiko; Koma, Daisuke; Yamanaka, Hayato; Ohmoto, Takashi; Sakai, Kiyofumi

2010-01-01

89

Dissolution enthalpies of cellulose in ionic liquids.  

PubMed

In this work, interactions between cellulose and ionic liquids were studied calorimetrically and by optical microscopy. Two novel ionic liquids (1,5-Diazabicyclo[4.3.0]non-5-enium propionate and N-methyl-1,5-diazabicyclo[4.3.0]non-5-enium dimethyl phosphate) and 1-ethyl-3-methylimidazolium acetate-water mixtures were used as solvents. Optical microscopy served in finding the extent of dissolution and identifying the dissolution pattern of the cellulose sample. Calorimetric studies identified a peak relating to dissolution of cellulose in solvent. The transition did, however, not indicate complete dissolution, but rather dissolution inside fibre or fibrils. This method was used to study differences between four cellulose samples with different pretreatment or origins. PMID:25256460

Parviainen, Helena; Parviainen, Arno; Virtanen, Tommi; Kilpeläinen, Ilkka; Ahvenainen, Patrik; Serimaa, Ritva; Grönqvist, Stina; Maloney, Thaddeus; Maunu, Sirkka Liisa

2014-11-26

90

Demystifying Hardy-Weinberg: Using Cellulose Acetate Electrophoresis of the Lap Locus to Study Population Genetics in White Campion (Silene latifolia)  

NSDL National Science Digital Library

This laboratory exercise could used as an introductory biology lab and/or an upper level course lab, with minor adjustments, covering ecology, evolution, population genetics and physiology. Population genetics is explored using seedlings from several population of the perennial herb white campion, (Silene latifolia), scientific method,cellulose acetate protein electrophoresis and the Hardy-Weinberg Equilibrium Theory.

Patricia A. Peroni (Davidson College;); David E. McCauley (Vanderbilt University;)

1999-01-01

91

Cellulose acetate beads induce release of interleukin-1 receptor antagonist, but not tumour necrosis factor-a or interleukin-1ß in human peripheral blood  

Microsoft Academic Search

Objective: Dramatic improvements in clinical symptoms of rheumatoid arthritis and ulcerative colitis were observed after patients received granulocyte and monocyte adsorptive apheresis with a column containing cellulose acetate (CA) beads as adsorptive carriers. This study was to investigate the effect of CA beads on the generation of anti-inflammatory and pro-inflammatory cytokines in human blood. Materials and Methods: We incubated human

Y. Takeda; K. Hiraishi; H. Takeda; N. Shiobara; H. Shibusawa; A. R. Saniabadi; M. Adachi; S. Kawata

2003-01-01

92

Formation of membranes by means of immersion precipitation : Part II. the mechanism of formation of membranes prepared from the system cellulose acetate-acetone-water  

Microsoft Academic Search

Using equations and boundary conditions derived in Part I1, calculations have been performed on the ternary diffusion processes that occur in a cellulose acetate (CA) -acetone casting solution immersed into a water bath. The necessary concentration-dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures. Calculations show that immersion of the polymer solution

A. J. Reuvers; C. A. Smolders

1987-01-01

93

Study the biocatalyzing effect and mechanism of cellulose acetate immobilized redox mediators technology (CE-RM) on nitrite denitrification.  

PubMed

The biocatalyzing effect of a novel cellulose acetate immobilized redox mediators technology (CE-RM) on nitrite denitrification process was studied with anthraquinone, 1,8-dichloroanthraquinone, 1,5-dichloroanthraquinone and 1,4,5,8-tetrachloroanthraquinone. The results showed that the immobilized 1,4,5,8-tetrachloroanthraquinone presented the best biocatalyzed effect which increased nitrite denitrification rate to 2.3-fold with 12 mmol/L 1,4,5,8-tetrachloroanthraquinone. The unequal biocatalyzing effect was due to the quantity and position of -Cl substituent in anthraquinone-structure. Moreover, the nitrite denitrification rate was increased with the oxidation reduction potential (ORP) values becoming more negative during the biocatalyzing process. The stabilized ORP value with 12 mmol/L immobilized 1,4,5,8-tetrachloroanthraquinone were 81 mV lower than the control. At the same time, the more OH(-) was produced with the higher nitrite removal rate achieved in the nitrite denitrification process. In addition, a positive linear correlation was found between the nitrite removal reaction constants k [gNO2(-)-N/(gVSS d)] and immobilized 1,4,5,8-tetrachloroanthraquinone concentration (C1,4,5,8-tetrachloroanthraquinone), which was k = 1.8443 C1,4,5,8-tetrachloroanthraquinone + 33.75(R(2) = 0.9411). The initial nitrite concentration of 179 mgNO2(-)-N/L resulted in the maximum nitrite removal rate, which was 6.526[gNO2(-)-N/(gVSS d)]. These results show that the application of cellulose acetate immobilized redox mediators (CE-RM) can be valuable for increasing nitrite denitrification rate. PMID:24179089

Li, Haibo; Guo, Jianbo; Lian, Jing; Xi, Zhenhua; Zhao, Lijun; Liu, Xiaoyu; Zhang, Chenxiao; Yang, Jingliang

2014-06-01

94

Diffusion of 1-Ethyl-3-methyl-imidazolium Acetate in Glucose, Cellobiose, and Cellulose Solutions  

PubMed Central

Solutions of glucose, cellobiose and microcrystalline cellulose in the ionic liquid 1-ethyl-3-methyl-imidazolium ([C2mim][OAc]) have been examined using pulsed-field gradient 1H NMR. Diffusion coefficients of the cation and anion across the temperature range 20–70 °C have been determined for a range of concentrations (0–15% w/w) of each carbohydrate in [C2mim][OAc]. These systems behave as an “ideal mixture” of free ions and ions that are associated with the carbohydrate molecules. The molar ratio of carbohydrate OH groups to ionic liquid molecules, ?, is the key parameter in determining the diffusion coefficients of the ions. Master curves for the diffusion coefficients of cation, anion and their activation energies are generated upon which all our data collapses when plotted against ?. Diffusion coefficients are found to follow an Arrhenius type behavior and the difference in translational activation energy between free and associated ions is determined to be 9.3 ± 0.9 kJ/mol. PMID:24405090

2014-01-01

95

FTIR Imaging Coupled with Multivariate Analysis for Study of Initial Diffusion of Different Solvents in Cellulose Acetate Butyrate Films  

SciTech Connect

Fourier transform infrared (FTIR) spectroscopic imaging was used to study the initial diffusion of different solvents in cellulose acetate butyrate (CAB) films containing different amounts of acetyl and butyryl substituents. Different solvents and solvent/non-solvent mixtures were also studied. The FTIR imaging system allowed acquisition of sequential images of the CAB films as solvent penetration proceeded without disturbing the system. The interface between the non-swollen polymer and the initial swelling front could be identified using multivariate data analysis tools. For a series of ketone solvents the initial diffusion coefficients and diffusion rates could be quantified and were found to be related to the polar and hydrogen interaction parameters in the Hansen solubility parameters of the solvents. For the solvent/non-solvent system the initial diffusion rate decreased less than linearly with the weight-percent of non-solvent present in the solution, which probably was due to the swelling characteristic of the non-solvent. For a given solvent, increasing the butyryl content of the CAB increased the initial diffusion rate. Increasing the butyryl content from 17 wt.% butyryl to 37 wt.% butyryl produced a considerably larger increase in initial diffusion rate compared to an increase in butyryl content from 37 wt.% to 50 wt.% butyryl.

Lindblad, M.S.; Keyes, B.; Gedvilas, L.; Kelley, S.S.

2008-01-01

96

Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane.  

PubMed

Conductive composite membrane-phytic acid (PA) doped polyaniline (PANI)/cellulose acetate (CA) (PANI-PA/CA) was prepared in a simple and environmental-friendly method, in which aniline was blended with CA/PA solution and polymerized before the phase conversion. The resultant composite membranes were characterized by SEM, EDX, FTIR-ATR, BET and electrical resistance measurements. When used as adsorbent for Hg(II) and Cr(VI) ions, the prepared composite membrane exhibits excellent adsorption capability. The adsorption of Hg(II) and Cr(VI) follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model, with the maximum adsorption capacity reaching 280.11 and 94.34 mg g(-1), respectively. The heavy metal loaded composite membrane can be regenerated and reused after treatment with acid or alkali solution, making it a promising and practical adsorbent for Hg(II) and Cr(VI) removal. Tests with river water were also carried out, indicating good performance and application. PMID:25127386

Li, Renjie; Liu, Lifen; Yang, Fenglin

2014-09-15

97

Mechanical and thermal properties of eco-friendly poly(propylene carbonate)/cellulose acetate butyrate blends.  

PubMed

The eco-friendly poly(propylene carbonate) (PPC)/cellulose acetate butyrate (CAB) blends were prepared by melt-blending in a batch mixer for the first time. PPC and CAB were partially miscible because of the drastically shifted glass transition temperatures of both PPC and CAB, which originated from the specific interactions between carbonyl groups and hydroxyl groups. The incorporation of CAB into PPC matrix enhanced not only tensile strength and modulus of PPC dramatically, but also improved heat resistance and thermal stability of PPC significantly. The tensile strength and the modulus of PPC/CAB=50/50 blend are 27.7 MPa and 1.24 GPa, which are 21 times and 28 times higher than those of the unmodified PPC, respectively. Moreover, the elongation at break of PPC/CAB=50/50 blend is as high as 117%. In addition, the obtained blends exhibited good transparency, which is very important for the package materials. The results in this work pave new possibility for the massive application of eco-friendly polymer materials. PMID:23399238

Xing, Chenyang; Wang, Hengti; Hu, Qiaoqiao; Xu, Fenfen; Cao, Xiaojun; You, Jichun; Li, Yongjin

2013-02-15

98

A simple fiber-optic humidity sensor based on extrinsic Fabry-Perot cavity constructed by cellulose acetate butyrate film  

NASA Astrophysics Data System (ADS)

A fiber-optic relative humidity sensor with an extrinsic micro Fabry-Perot cavity constructed with a thin layer of cellulose acetate butyrate coated on a fiber end is presented. Its operational principle is based on the relative-humidity-dependent wavelength shift of the interference fringes formed by Fresnel reflections from both interfaces of the thin film. Both the experimental and theoretical analyses are investigated in detail. The experimental data for relative humidity ranging from 8.8% to 88.1% are measured in the both humidification and dehumidification processes, which fits the linear equation very well with a value of R2 = 0.9946. As observed, it shows a high sensitivity of 0.307 nm/%RH with a high resolution of 0.06%. The time-dependent response of the sensor is estimated. The long term stability of the sensor is also addressed with high precision of ±0.03% over 100 min. The proposed relative humidity sensor has a simple, solid, and compact structure.

Xu, Wei; Huang, Wo-Bin; Huang, Xu-Guang; Yu, Chang-yuan

2013-12-01

99

A novel orientation technique for semi-rigid polymers. 1. Preparation of cross-linked cellulose acetate and hydroxypropylcellulose films having permanent anisotropy in the swollen state  

Microsoft Academic Search

It has been predicted that unusually good mechanical properties can be obtained by drying swollen networks of semi-rigid chains while they are in the deformed state, as described in several theoretical investigations [Macromolecules,23: 5335, 5341 (1990),24: 901 (1991)]. The present investigation involves the preparation of networks of this type from cellulose acetate (CA) and hydroxypropylcellulose (HPC), in order to test

Yong Yang; A. Kloczkowski; J. E. Mark; B. Erman; I. Bahar

1994-01-01

100

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis  

Microsoft Academic Search

Although cellulose acetates, CAs, are extensively employed there is scant information about the systematic dependence of their properties on their degree of substitution, DS; this is the subject of the present work. Nine CAs samples, DS from\\u000a 0.83 to 3.0 were synthesized; their films were prepared. The following solvatochromic probes have been employed in order to\\u000a determine the empirical polarity,

Ludmila C. Fidale; Constance Ißbrücker; Priscilla L. Silva; Camila M. Lucheti; Thomas Heinze; Omar A. El Seoud

2010-01-01

101

Investigation of unique interactions between cellulose acetate and ionic liquid [EMIM]SCN, and their influences on hollow fiber ultrafiltration membranes  

Microsoft Academic Search

This study investigates the molecular interactions between ionic liquid, 1-ethyl-3-methylimidazolium thiocyanate ([EMIM]SCN) and cellulose acetate (CA), employing not only experimental characterizations including FTIR and rheological tests, but also molecular dynamics simulations. Due to the electrostatic nature of ionic liquids, [EMIM]SCN interacts intensely with CA molecules through pronounced hydrogen bonding, Coulombic forces and van der Waals interactions, which play an important

Ding Yu Xing; Na Peng; Tai-Shung Chung

2011-01-01

102

Extrusion foaming of thermoplastic cellulose acetate from renewable resources using a two-component physical blowing agent system  

NASA Astrophysics Data System (ADS)

Thermoplastic cellulose acetate (CA) is a bio-based polymer with optical, mechanical and thermal properties comparable to those of polystyrene (PS). The substitution of the predominant petrol-based PS in applications like foamed food trays can lead to a more sustainable economic practice. However, CA is also suitable for more durable applications as the biodegradability rate can be controlled by adjusting the degree of substitutions. The extrusion foaming of CA still has to overcome certain challenges. CA is highly hydrophilic and can suffer from hydrolytic degradation if not dried properly. Therefore, the influence of residual moisture on the melt viscosity is rather high. Beyond, the surface quality of foam CA sheets is below those of PS due to the particular foaming behaviour. This paper presents results of a recent study on extrusion foamed CA, using a two-component physical blowing agent system compromising HFO 1234ze as blowing agent and organic solvents as co-propellant. Samples with different co-propellants are processed on a laboratory single screw extruder at IKV. Morphology and surface topography are investigated with respect to the blowing agent composition and the die pressure. In addition, relationships between foam density, foam morphology and the propellants are analysed. The choice of the co-propellant has a significant influence on melt-strength, foaming behaviour and the possible blow-up ratio of the sheet. Furthermore, a positive influence of the co-propellant on the surface quality can be observed. In addition, the focus is laid on the effect of external contact cooling of the foamed sheets after the die exit.

Hopmann, Ch.; Windeck, C.; Hendriks, S.; Zepnik, S.; Wodke, T.

2014-05-01

103

Development of theophylline floating microballoons using cellulose acetate butyrate and/or Eudragit RL 100 polymers with different permeability characteristics  

PubMed Central

The objective of the present investigation was to design a sustained release floating microcapsules of theophylline using two polymers of different permeability characteristics; Eudragit RL 100 (Eu RL) and cellulose acetate butyrate (CAB) using the oil-in-oil emulsion solvent evaporation method. Polymers were used separately and in combination to prepare different microcapsules. The effect of drug-polymer interaction was studied for each of the polymers and for their combination. Encapsulation efficiency, the yield, particle size, floating capability, morphology of microspheres, powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) were evaluated. The in vitro release studies were performed in PH 1.2 and 7.4. The optimized drug to polymer ratios was found to be 4:1 (F2) and 0.75:1 (F'2) with Eu RL and CAB, respectively. The best drug to polymer ratio in mix formulation was 4:1:1 (theophylline: Eu RL: CAB ratio). Production yield, loading efficiencies, and particle size of F2 and F’2 were found to be 59.14% and 45.39%, 73.93% and 95.87%, 372 and 273 micron, respectively. Microsphere prepared with CAB showed the best floating ability (80.3 ± 4.02% buoyancy) in 0.1 M HCl for over 12 h. The XRD and DSC showed that theophylline in the drug loaded microspheres was stable and in crystaline form. Microparticles prepared using blend of Eu RL and CAB polymers indicated more sustained pattern than the commercial tablet (P<0.05). Drug loaded floating microballoons prepared of combination of Eu RL and CAB with 1:1 ratio were found to be a suitable delivery system for sustained release delivery of theophylline which contained lower amount of polymer contents in the microspheres. PMID:21589766

Jelvehgari, M.; Maghsoodi, M.; Nemati, H.

2010-01-01

104

Influence of processing and curing conditions on beads coated with an aqueous dispersion of cellulose acetate phthalate.  

PubMed

The influence of fluidized-bed processing conditions, as well as curing parameters with and without humidity, on drug release from beads coated with cellulose acetate phthalate (CAP) aqueous dispersion was investigated. Theophylline beads prepared by extrusion-spheronization were coated with diethyl phthalate (DEP)-plasticized CAP dispersion (Aquacoat CPD) using a Strea-1 fluidized-bed coater. The parameters investigated were plasticizer level, outlet temperature, spray rate during coating application and fluidizing air velocities using a half-factorial design. The processing temperature during coating applications was identified as a critical factor among the variables investigated. The release rate significantly decreased when the beads were coated at 36 degrees C compared to those coated at 48 degrees C (P<0.01). Higher coating efficiencies and better coalescence of films were obtained at the lower coating temperature. Above the minimum film-formation temperature (MFFT), drug release in acid decreased as the coating temperature was decreased. Curing at 60 degrees C significantly reduced the drug release for beads coated at 32 degrees C, but had no significant effect on drug release for beads coated at temperatures above 36 degrees C. Curing at 50 degrees C in an atmosphere containing 75% RH (relative humidity), irreversibly converted poor film formation into better coalescence, and increased the mechanical toughness of films. Subsequent removal of the moisture absorbed from beads did not significantly alter the enteric profiles obtained through heat-humidity curing. The extent of coalescence via heat-humidity curing was dependent on the curing temperature, % humidity, curing time and coating temperature. The results demonstrated the importance of the selection of coating temperature for CAP-coated beads and the role of moisture on CAP film formation. Curing with humidity was found to be more effective than without. PMID:10799816

Williams, R O; Liu, J

2000-05-01

105

Cellulose acetate phthalate (CAP): an 'inactive' pharmaceutical excipient with antiviral activity in the mouse model of genital herpesvirus infection.  

PubMed

The spread of sexually transmitted infections caused by herpes simplex virus type 2 (HSV-2) has continued unabated. At least 20% of the United States population has been infected with HSV-2 and there is a high probability of further virus transmission by asymptomatic carriers. Given the absence of effective vaccines, this indicates the need to develop prophylactic measures such as topical microbicides that have antiviral activity. Recent studies indicate that cellulose acetate phthalate (CAP), an inactive pharmaceutical excipient commonly used in the production of enteric tablets and capsules, is a broad specificity microbicide against diverse sexually transmitted pathogens. When appropriately formulated in micronized form, it inactivates various viruses, including HSV-2, in vitro. Here we show that CAP inhibits HSV-2 infection in the mouse model of genital HSV-2 infection. Pretreatment with micronized CAP formulated in a glycerol-based cream with colloidal silicone dioxide significantly reduced the proportion of HSV-2-infected mice (10% virus shedding, 0-5% lesion development and 0% fatality for CAP as compared to 84% shedding, 63% lesion development and 63% fatality in saline-treated mice). These differences were significant (P < or = 0.0002 by the test of equality of two proportions). Virus titres in the minority of mice that developed infection were similar to those in untreated mice. HSV-2 infection was not inhibited by treatment with CAP formulated with other inactive ingredients (for example povidone plus crosprovidone) instead of silicone dioxide, presumably reflecting CAP complexation/inactivation. These data suggest that properly formulated, CAP may be an efficacious agent for preventing vaginal transmission of genital herpesvirus infections. PMID:10628808

Gyotoku, T; Aurelian, L; Neurath, A R

1999-11-01

106

Controlled porosity osmotic pump-based controlled release systems of pseudoephedrine. I. Cellulose acetate as a semipermeable membrane.  

PubMed

A controlled porosity osmotic pump-based drug delivery system has been described in this study. Unlike the elementary osmotic pump (EOP) which consists of an osmotic core with the drug surrounded by a semipermeable membrane drilled with a delivery orifice, controlled porosity of the membrane is accomplished by the use of different channeling agents in the coating. The usual dose of pseudoephedrine is 60 mg to be taken three or four times daily. It has a short plasma half life of 5-8 h. Hence, pseudoephedrine was chosen as a model drug with an aim to develop a controlled release system for a period of 12 h. Sodium bicarbonate was used as the osmogent. The effect of different ratios of drug:osmogent on the in-vitro release was studied. Cellulose acetate (CA) was used as the semipermeable membrane. Different channeling agents tried were diethylphthalate (DEP), dibutylphthalate (DBP), dibutylsebacate (DBS) and polyethyleneglycol 400 (PEG 400). The effect of polymer loading on in-vitro drug release was studied. It was found that drug release rate increased with the amount of osmogent due to the increased water uptake, and hence increased driving force for drug release. This could be retarded by the proper choice of channeling agent in order to achieve the desired zero order release profile. Also the lag time seen with tablets coated using diethylphthalate as channeling agent was reduced by using a hydrophilic plasticizer like polyethyleneglycol 400 in combination with diethylphthalate. This system was found to deliver pseudoephedrine at a zero order rate for 12 h. The effect of pH on drug release was also studied. The optimized formulations were subjected to stability studies as per ICH guidelines at different temperature and humidity conditions. PMID:12695059

Makhija, Sapna N; Vavia, Pradeep R

2003-04-14

107

Mechanical Properties and a Physical-Chemical Analysis of Acetate Yarns  

Microsoft Academic Search

Cellulose acetate used in the manufacture of acetate yarns is commonly obtained from cotton-linters or wood-pulp cellulose. Varying in the origin and in the manufacturer, cellulose acetate often differs in its processability. The paper belongs to the investigation the properties of acetate yarns manufactured of the cellulose acetate varied in its origin and manufactured by different suppliers. Mechanical properties (including

R. emaitaitien?; A. Vitkauskas

108

Fluorescence polarization of N-vinyl carbazole grafted on cellulose acetate film and its electron transfer reaction with 1,4-dicyanobenzene  

NASA Astrophysics Data System (ADS)

N-vinyl carbazole (VCZ) has been grafted on a cellulose acetate (CA) matrix by simultaneous irradiation technique using Co-60 ? rays. Two sets of experiments, fluorescence polarization measurements with a grafted VCZ (GVCZ) film and a photo-induced electron transfer (ET) reaction between GVCZ and 1,4-dicyanobenzene (DCB) in tetrahydrofuran (THF), have been performed. Polarization appears in the GVCZ film due to restricted rotational motion of the grafted VCZ on a CA film. ET and the formation of an exciplex between GVCZ and DCB have been observed by steady state and time-resolved fluorescence and laser flash photolysis studies. The dynamics of fluorescence quenching have been evaluated by applying the Stern-Volmer equation. Laser flash photolysis experiments have been able to identify the formation of DCB - at 430 nm due to ET from GVCZ to DCB, which adds a transient polyelectrolyte property to the system.

Aich, Sanjukta; Bhattacharyya, Amit; Basu, Samita

1997-10-01

109

Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid  

NASA Astrophysics Data System (ADS)

The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.

Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua

2014-03-01

110

Effect of cellulose acetate butyrate microencapsulated ammonium polyphosphate on the flame retardancy, mechanical, electrical, and thermal properties of intumescent flame-retardant ethylene-vinyl acetate copolymer/microencapsulated ammonium polyphosphate/polyamide-6 blends.  

PubMed

Ammonium polyphosphate (APP), a widely used intumescent flame retardant, has been microencapsulated by cellulose acetate butyrate with the aim of enhancing the water resistance of APP and the compatibility between the ethylene-vinyl acetate copolymer (EVA) matrix and APP. The structure of microencapsulated ammonium polyphosphate (MCAPP) was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and water contact angle (WCA). The flame retadancy and thermal stability were investigated by a limiting oxygen index (LOI) test, UL-94 test, cone calorimeter, and thermogravimetric analysis (TGA). The WCA results indicated that MCAPP has excellent water resistance and hydrophobicity. The results demonstrated that MCAPP enhanced interfacial adhesion, mechanical, electrical, and thermal stability of the EVA/MCAPP/polyamide-6 (PA-6) system. The microencapsulation not only imparted EVA/MCAPP/PA-6 with a higher LOI value and UL-94 rating but also could significantly improve the fire safety. Furthermore, the microencapsulated EVA/MCAPP/PA-6 composites can still pass the UL-94 V-0 rating after treatment with water for 3 days at 70 °C, indicating excellent water resistance. This investigation provides a promising formulation for the intumescent flame retardant EVA with excellent properties. PMID:21859130

Wang, Bibo; Tang, Qinbo; Hong, Ningning; Song, Lei; Wang, Lei; Shi, Yongqian; Hu, Yuan

2011-09-01

111

Dissolution of cellulose in 1-allyl-3-methylimizodalium carboxylates at room temperature: a structure-property relationship study.  

PubMed

The development of highly efficient cellulose solvents is imperative to the effective utilization of cellulose. In this work, ionic liquids (ILs) with the same 1-allyl-3-methylimidazolium cation ([Amim](+)) but different carboxylate anions, such as formate ([HCOO](-)), acetate ([CH3COO](-)), propionate ([CH3CH2COO](-)), butyrate ([CH3CH2CH2COO](-)), glycollate ([HOCH2COO](-)), lactate ([CH3CHOHCOO](-)) and benzoate ([C6H5COO](-)) were synthesized, and their thermal properties and viscosities were determined. Then these ILs were used to investigate the effect of anion structure on solubility of cellulose in the ILs. It was shown that the viscosity and cellulose solubility depended strongly on the anion structure of the ILs. For example, at 30 °C solubility of cellulose in [Amim][CH3CH2COO] was as high as 19.0%, whereas cellulose was not soluble in [Amim][HOCH2COO], [Amim][CH3CHOHCOO] and [Amim][C6H5COO]. In addition, solvatochromic UV/vis probe and (13)C NMR measurements were performed to demonstrate dissolution mechanism of cellulose in the ILs. The results suggested that although cations of the ILs have un-negligible contribution to the highly efficient dissolution of cellulose, hydrogen bonding interactions of anions of the ILs with cellulose is predominant. PMID:25498686

Zhang, Yajuan; Xu, Airong; Lu, Benlian; Li, Zhiyong; Wang, Jianji

2015-03-01

112

Cellulose Derivatives Derived From Pulp and Paper Mill Sludge  

Microsoft Academic Search

Cellulose derivatives were produced from the cellulose fraction of pulp and paper mill sludge. The raw primary sludge was reacted under conventional cellulose derivatization conditions and the modified cellulose was isolated, in most cases, by dissolution in a suitable solvent. The cellulose derivatives produced were cellulose nitrate, cellulose acetate, carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose. These compounds were characterized by Fourier transform

David G. Barkalow; Raymond A. Young

1985-01-01

113

Propionic Acid Production by a Propionic Acid-Tolerant Strain of Propionibacterium acidipropionici in Batch and Semicontinuous Fermentation †  

PubMed Central

A propionic acid-tolerant derivative of Propionibacterium acidipropionici P9 was obtained by serially transferring strain P9 through broth that contained increasing amounts of propionic acid. After 1 year of repeated transfers, a strain (designed P200910) capable of growth at higher propionic acid concentrations than P9 was obtained. An increase in the proportion of cellular straight-chain fatty acids and uncoupling of propionic acid production from growth were observed for strain P200910. Growth rate, sugar utilization, and acid production were monitored during batch and semicontinuous fermentations of semidefined medium and during batch fermentation of whey permeate for both strain P200910 and strain P9. The highest propionic acid concentration (47 g/liter) was produced by P200910 in a semicontinuous fermentation. Strain P200910 produced a higher ratio of propionic acid to acetic acid, utilized sugar more efficiently, and produced more propionic acid per gram of biomass than did its parent in all fermentations. PMID:16348561

Woskow, Steven A.; Glatz, Bonita A.

1991-01-01

114

Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode  

PubMed Central

In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10?5 M and 4 × 10?4 M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10?6 M. At the end of the 20th day, the biosensor still retained 50% of its initial activity. PMID:22315566

Alpat, ?enol; Telefoncu, Azmi

2010-01-01

115

Toxic metal ion separation by cellulose acetate/sulfonated poly(ether imide) blend membranes: effect of polymer composition and additive.  

PubMed

Toxic heavy metal ion removal from industrial effluents are gaining increased visibility owing to environmental concern and saving precious materials. In this work, an attempt has been made to remove the valuable metal ions using modified ultrafiltration (UF) blend membranes based on cellulose acetate (CA) and sulfonated poly(ether imide) (SPEI) were prepared in the presence and absence of additive, poly(ethylene glycol) 600 (PEG600) in various compositions. Prepared membranes were characterized in terms of pure water flux (PWF), water content and membrane hydraulic resistance. High flux UF membranes were obtained in the range of 15-25 wt% SPEI and 2.5-10 wt% PEG600 in the polymer blend. The molecular weight cut-off (MWCO) of the blend membranes were determined using protein separation studies found to vary from 20 to greater than 69 kDa. Surface morphology of the blend membranes were analysed with scanning electron microscopy. Studies were carried out to find the rejection and permeate flux of metal ions such as Cu(II), Ni(II), Zn(II) and Cd(II) using polyethyleneimine as the chelating ligand. On increasing the composition of SPEI and PEG600, the rejection of metal ions is decreasing while the permeate flux has an increasing trend. These effects are due to the increased pore formation in the CA/SPEI blend membranes because of the hydrophilic SPEI and polymeric additive PEG600. In general, it was found that CA/SPEI blend membranes displayed higher permeate flux and lower rejection compared to pure CA membranes. The extent of separation of metal ions depends on the affinity of metal ions to polyethyleneimine to form macromolecular complexes and the stability of the formed complexes. PMID:18191025

Nagendran, A; Vijayalakshmi, A; Arockiasamy, D Lawrence; Shobana, K H; Mohan, D

2008-07-15

116

Isolation and identification of residual chromophores in cellulosic materials  

Microsoft Academic Search

A general procedure was developed for the isolation of residual chromophores in or on cellulosic material, which were hitherto inaccessible to structure elucidation due to their extremely low content in the ppb concentration scale. It is applicable to cellulosic pulp, cellulosic fibers (viscose, Lyocell) and cellulose derivatives (acetate, carbonyl-labeled cellulose) as well. The chromophore identification comprises treatment of the cellulosic

Thomas Rosenau; Antje Potthast; Walter Milacher; Andreas Hofinger; Paul Kosma

2004-01-01

117

Determination of Odor Release in Hydrocolloid Model Systems Containing Original or Carboxylated Cellulose at Different pH Values Using Static Headspace Gas Chromatographic (SHS-GC) Analysis  

PubMed Central

Static headspace gas chromatographic (SHS-GC) analysis was performed to determine the release of 13 odorants in hydrocolloid model systems containing original or regio-selectively carboxylated cellulose at different pH values. The release of most odor compounds was decreased in the hydrocolloid solutions compared to control, with the amounts of 2-propanol, 3-methyl-1-butanol, and 2,3-butanedione released into the headspace being less than those of any other odor compound in the hydrocolloid model systems. However, there was no considerable difference between original cellulose-containing and carboxylated-cellulose containing systems in the release of most compounds, except for relatively long-chain esters such as ethyl caprylate and ethyl nonanoate. The release from the original and carboxylated cellulose solutions controlled to pH 10 was significantly higher than that from solutions adjusted to pH 4 and 7 in the case of some esters (ethyl acetate, methyl propionate, ethyl propionate, ethyl butyrate, butyl propionate, ethyl caproate) and alcohols (2-propanol, 3-methyl-1-butanol), in particular, ethyl butyrate and 3-methyl-1-butanol. In contrast, the release of 2,3-butanedione from both the original and carboxylated cellulose solutions was increased at pH 4 and 7 compared to that at pH 10 by about 70% and 130%, respectively. Our study demonstrated that the release of some odorants could be changed significantly by addition of both original and carboxylated cellulose in hydrocolloid model systems, but only minor effect was observed in pH of the solution. PMID:23447013

Lee, Sang Mi; Shin, Gil-Ok; Park, Kyung Min; Chang, Pahn-Shick; Kim, Young-Suk

2013-01-01

118

Application of chemical and thermal analysis methods for studying cellulose ester plastics.  

PubMed

Cellulose acetate, developed about 100 years ago as a versatile, semisynthetic plastic material, is used in a variety of applications and is perhaps best known as the basis of photographic film stock. Objects made wholly or partly from cellulose acetate are an important part of modern and contemporary cultural heritage, particularly in museum collections. Given the potential instability of the material, however, it is imperative to understand the aging mechanisms and deterioration pathways of cellulose ester plastics to mitigate decomposition and formulate guidelines for storage, exhibition, and conservation. One important aspect of this process is the ability to fully characterize the plastic, because variations in composition affect its aging properties and ultimate stability. In this Account, we assess the potential of a range of analytical techniques for plastics made from cellulose acetate, cellulose propionate, and cellulose butyrate. Comprehensive characterization of cellulose ester plastics is best achieved by applying several complementary analytical techniques. Fourier-transform IR (FTIR) and Raman spectroscopy provide rapid means for basic characterization of plastic objects, which can be useful for quick, noninvasive screening of museum collections with portable instruments. Pyrolysis GC/MS is capable of differentiating the main types of cellulose ester polymers but also permits a richly detailed compositional analysis of additives. Thermal analysis techniques provide a wealth of compositional information and thermal behavior. Thermogravimetry (TG) allows for quantitative analysis of thermally stable volatile additives, and weight-difference curves offer a novel means for assessing oxidative stability. The mechanical response to temperature, such as the glass transition, can be measured with dynamic mechanical analysis (DMA), but results from other thermal analysis techniques such as TG, differential scanning calorimetry (DSC), and dynamic load thermomechanical analysis (DLTMA) are often required to more accurately interpret the results. The analytical results from this study form the basis for in-depth studies of works of art fabricated from cellulose acetate. These objects, which are particularly at risk when stored in tightly sealed containers (as is often the case with photographic film), warrant particular attention for conservation given their susceptibility toward sudden onset of deterioration. PMID:20455567

Schilling, Michael; Bouchard, Michel; Khanjian, Herant; Learner, Tom; Phenix, Alan; Rivenc, Rachel

2010-06-15

119

Genetics Home Reference: Propionic acidemia  

MedlinePLUS

... Patients and Families Resources for Health Professionals What glossary definitions help with understanding propionic acidemia? acids ; aciduria ; ... many other terms in the Genetics Home Reference Glossary . See also Understanding Medical Terminology . References (6 links) ...

120

Cellulose Acetate Reverse Osmosis Membranes Made by Phase Inversion Method: Effects of a Shear Treatment Applied to the Casting Solution on the Membrane Structure and Performance  

Microsoft Academic Search

A mixture of equal parts of cellulose diacetate and cellulose triacetate was dissolved in dipropylene glycol and exposed to shear stresses of varying intensity on a three-roll calander. Asymmetric reverse osmosis membranes were prepared from these materials by the phase-inversion method. Reverse osmosis tests in a dead-end module provided membrane performance data. A structure analysis was performed by scanning electron

Mathias C. M. Nolte; Peter F. W. Simon; Myrna Aguiar del Toro; Karen Gerstandt; Wolfgang Calmano

2011-01-01

121

Dermatopharmacologic investigations of halobetasol propionate in comparison with clobetasol 17-propionate.  

PubMed

Both halobetasol propionate and clobetasol 17-propionate exerted very marked antiinflammatory, antiproliferative, and vasoconstrictive effects during evaluation in a range of dermatopharmacologic models. Halobetasol propionate was distinctly more potent than clobetasol 17-propionate in the ultraviolet-induced dermatitis inhibition assay in guinea pigs and in the rat model of oxazolone-induced late inflammatory reaction. Halobetasol propionate was slightly more potent than clobetasol 17-propionate in inhibiting croton oil-induced ear edema in rats and mice and in the mouse model of oxazolone-induced early inflammatory reaction. In the cotton-pellet granuloma assay in rats and the epidermal hyperplasia inhibition assay in guinea pigs, halobetasol propionate was distinctly superior to clobetasol 17-propionate. There was a trend in favor of halobetasol propionate in the cutaneous vasoconstriction assay performed in volunteers with ethanol solutions of halobetasol propionate and clobetasol 17-propionate. In a further vasoconstriction assay, performed with a 0.05% concentration of both halobetasol propionate and clobetasol 17-propionate in cream and ointment formulations, halobetasol propionate ointment yielded the highest blanching score. In a hypothalamic-pituitary-adrenal axis study in volunteers, effects of 0.05% halobetasol propionate ointment and 0.05% clobetasol 17-propionate ointment on serum cortisol levels were similar. The overall efficacy trends demonstrated in these dermatopharmacologic studies are in agreement with predictions made from corticosteroid structure and activity relationships and the results of two clinical trials comparing halobetasol propionate and clobetasol 17-propionate ointments in the treatment of plaque psoriasis. PMID:1757603

Yawalkar, S; Wiesenberg-Boettcher, I; Gibson, J R; Siskin, S B; Pignat, W

1991-12-01

122

Acceleration of cellulose degradation and shift of product via methanogenic co-culture of a cellulolytic bacterium with a hydrogenotrophic methanogen.  

PubMed

Although the effects of syntrophic relationships between bacteria and methanogens have been reported in some environments, those on cellulose decomposition using cellulolytic bacteria from methanogenic reactors have not yet been examined. The effects of syntrophic co-culture on the decomposition of a cellulosic material were investigated in a co-culture of Clostridium clariflavum strain CL-1 and the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain ?H and a single-culture of strain CL-1 under thermophilic conditions. In this study, strain CL-1 was newly isolated as a cellulolytic bacterium from a thermophilic methanogenic reactor used for degrading garbage slurry. The degradation efficiency and cell density of strain CL-1 were 2.9- and 2.7-fold higher in the co-culture than in the single-culture after 60 h of incubation, respectively. Acetate, lactate and ethanol were the primary products in both cultures, and the concentration of propionate was low. The content of acetate to total organic acids plus ethanol was 59.3% in the co-culture. However, the ratio decreased to 24.9% in the single-culture, although acetate was the primary product. Therefore, hydrogen scavenging by the hydrogenotrophic methanogen strain ?H could shift the metabolic pathway to the acetate production pathway in the co-culture. Increases in the cell density and the consequent acceleration of cellulose degradation in the co-culture would be caused by increases in adenosine 5'-triphosphate (ATP) levels, as the acetate production pathway includes ATP generation. Syntrophic cellulose decomposition by the cellulolytic bacteria and hydrogenotrophic methanogens would be the dominant reaction in the thermophilic methanogenic reactor degrading cellulosic materials. PMID:22652087

Sasaki, Daisuke; Morita, Masahiko; Sasaki, Kengo; Watanabe, Atsushi; Ohmura, Naoya

2012-10-01

123

ENVIRONMENT, HEALTH, AND BEHAVIOR Effects of High Zinc Diets Using Zinc Propionate on Molt Induction, Organs, and Postmolt Egg Production and Quality in Laying Hens  

Microsoft Academic Search

This study was conducted to determine the ability of an alternative salt form of 1% Zn, Zn propionate, to induce molt in 66-wk-old hens. The hens were ran- domly assigned to 4 treatment groups of 27 or 28 birds each: a) molted conventionally by feed withdrawal, b) 1% Zn as Zn acetate, c) 1% Zn as Zn propionate, or d)

S. Y. Park; S. G. Birkhold; L. F. Kubena; D. J. Nisbet; S. C. Ricke

124

Membrane filtration of Sudan orange G on a cellulose acetate membrane filter for separation-preconcentration and spectrophotometric determination in water, chili powder, chili sauce and tomato sauce samples.  

PubMed

A simple membrane filtration procedure for separation-enrichment of Sudan orange G is presented. The method is based on the adsorption of Sudan orange G on a cellulose acetate filter and its elution from the membrane with 10 mL of ethanol. Sudan orange G in the eluent was determined by UV-visible spectrophotometry at 388 nm. The effect of analytical conditions, including pH, flow rates and eluent, sample volume, type of membrane for quantitative preconcentration and separation of Sudan orange G were examined. The influences of matrix components on Sudan orange G recoveries were studied. The preconcentration factor was 125. The detection limit was 4.9 ?g L(-1). The relative standard deviation was 4.3%. The presented procedure was applied to chili powder, chili sauce, tomato sauce, powdered beverage and water samples. PMID:22617351

ALOthman, Zeid A; Unsal, Yunus E; Habila, Mohamed; Shabaka, Azza; Tuzen, Mustafa; Soylak, Mustafa

2012-08-01

125

Atmospheric chemistry of ethyl propionate.  

PubMed

Ethyl propionate is a model for fatty acid ethyl esters used as first-generation biodiesel. The atmospheric chemistry of ethyl propionate was investigated at 980 mbar total pressure. Relative rate measurements in 980 mbar N(2) at 293 ± 0.5 K were used to determine rate constants of k(C(2)H(5)C(O)OC(2)H(5) + Cl) = (3.11 ± 0.35) × 10(-11), k(CH(3)CHClC(O)OC(2)H(5) + Cl) = (7.43 ± 0.83) × 10(-12), and k(C(2)H(5)C(O)OC(2)H(5) + OH) = (2.14 ± 0.21) × 10(-12) cm(3) molecule(-1) s(-1). At 273-313 K, a negative Arrhenius activation energy of -3 kJ mol(-1) is observed.. The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar N(2) gave the following products (stoichiometric yields): ClCH(2)CH(2)C(O)OC(2)H(5) (0.204 ± 0.031), CH(3)CHClC(O)OC(2)H(5) (0.251 ± 0.040), and C(2)H(5)C(O)OCHClCH(3) (0.481 ± 0.088). The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar of N(2)/O(2) (with and without NO(x)) gave the following products: ethyl pyruvate (CH(3)C(O)C(O)OC(2)H(5)), propionic acid (C(2)H(5)C(O)OH), formaldehyde (HCHO), and, in the presence of NO(x), PAN (CH(3)C(O)OONO(2)). The lack of acetaldehyde as a product suggests that the CH(3)CH(O)C(O)OC(2)H(5) radical favors isomerization over decomposition. From the observed product yields, we conclude that H-abstraction by chlorine atoms from ethyl propionate occurs 20.4 ± 3.1%, 25.1 ± 4.0%, and 48.1 ± 8.8% from the CH(3)-, -CH(2)-, and -OCH(2)- groups, respectively. The rate constant and branching ratios for the reaction between ethyl propionate and the OH radical were investigated theoretically using quantum mechanical calculations and transition state theory. The stationary points along the reaction path were optimized using the CCSD(T)-F12/VDZ-F12//BH&HLYP/aug-cc-pVTZ level of theory; this model showed that OH radicals abstract hydrogen atoms primarily from the -OCH(2)- group (80%). PMID:22524192

Andersen, Vibeke F; Ørnsø, Kristian B; Jørgensen, Solvejg; Nielsen, Ole John; Johnson, Matthew S

2012-05-31

126

Comparison of radial immunodiffusion and alkaline cellulose acetate electrophoresis for quantitating elevated levels of fetal hemoglobin (HbF): application to evaluating patients with sickle cell disease treated with hydroxyurea.  

PubMed

Radial immunodiffusion (RID), alkaline cellulose acetate electrophoresis, and high-performance liquid chromatography (HPLC) were compared for quantitating the elevated (> 10%) level of fetal hemoglobin (HbF) found in the red blood cells of sickle cell disease patients undergoing treatment with hydroxyurea. HPLC- and electrophoresis-determined values were comparable. The RID-determined values were higher, in many cases twofold higher. False high HbF values would be misleading in assessing the effectiveness of hydroxyurea therapy in sickle cell disease patients. We subsequently initiated an examination of the variation in HbF values due to the use of different HbF radial immunodiffusion QUIPlates and different positions within a single plate in an attempt to determine the cause of these discrepancies. Within-run precision studies indicated that significantly different size precipitin rings were obtained depending upon which area of the plate the hemolysate containing antigen (HbF) was applied. A common feature associated with poor precision plates was a marked difference in degree of coloration of gel throughout the plate. Spuriously high HF concentrations were obtained with antigen (HbF) placed in wells located in the lighter colored gel area while antigen placed in wells in the darker colored area of the agarose gel bed were more in agreement with the electrophoretically determined HbF concentrations. The variation in HbF values was significantly greater in the diluted (HbF QUIPlate Diluent) samples than in the neat samples even on plates of uniform gel coloration. As a result of this study, we will continue to monitor high HbF levels by densitometry following alkaline cellulose acetate electrophoresis. PMID:10102137

Schultz, J C

1999-01-01

127

Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams  

SciTech Connect

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO{sub 2} balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength)

Rapp, F., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de; Schneider, A., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT (Germany); Elsner, P., E-mail: peter.elsner@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT, Germany and Karlsruhe Institute of Technology KIT (Germany)

2014-05-15

128

Properties of cellulose derivatives produced from radiation—Modified cellulose pulps  

Microsoft Academic Search

The aim of project was elaboration of radiation methods for properties modification of cellulose pulps using for derivatives production.The selected cellulose pulps were exposed to an electron beam with energy 10MeV in a linear accelerator. After irradiation pulps underwent the structural and physico-chemical investigations. The laboratory test for manufacturing carboxymethylocellulose (CMC), cellulose carbamate (CC) and cellulose acetate (CA) with cellulose

Edward Iller; Halina Stupinska; Pawel Starostka

2007-01-01

129

The wetting properties of grafted cellulose films  

Microsoft Academic Search

The dispersive component of the surface free energy, the nondispersive interaction, with polar liquids were determined for cellulose, cellulose acetate and cellulose grafted with alkyl ketene dimer (AKD). and were calculated in the dry state as well as the fully hydrated state by the two liquid contact angle method. was found to be independent of AKD coverage. I sw was

A. F. Toussaint; P. Luner

1993-01-01

130

Stable performance of anaerobic digestion in the presence of a high concentration of propionic acid  

Microsoft Academic Search

An automatically controlled, glucose-fed, anaerobic digester was deliberately inhibited by addition of phenol. To overcome the phenol inhibition the feed dilution rate was lowered in such a way that the methane yield from glucose was kept the same as that under normal conditions. The concentrations of acetic and butyric acids remained below 100 mg\\/l, however, propionic acid accumulated to 2750

Pratap C. Pullammanappallil; David P. Chynoweth; Gerasimos Lyberatos; Spyros A. Svoronos

2001-01-01

131

Propionate Production in the Rumen of Cows Fed Either a Control or High-Grain, Low-Fiber Diet  

Microsoft Academic Search

Rumen propionate production in cows fed either a control diet or a high-grain, low-fiber diet was measured by isotope dilu- tion ~echnique. The high-grain, low-fiber diet resulted in the characteristic decrease in milk fat per cent (50% reduction) and a decreased molar ratio of acetate :propio- hate. Propionate production on the two diets was 13.3 and 31.0 moles\\/day for the

D. E. Bauman; C. L. Davis; H. F. Bucholtz

1971-01-01

132

Acute Management of Propionic Acidemia  

PubMed Central

Propionic Acidemia or aciduria is an intoxication-type disorder of organic metabolism. Patients deteriorate in times of increased metabolic demand and subsequent catabolism. Metabolic decompensation can manifest with lethargy, vomiting, coma and death if not appropriately treated. On January 28-30, 2011 in Washington, D.C., Children's National Medical Center hosted a group of clinicians, scientists and parental group representatives to design recommendations for acute management of individuals with Propionic Acidemia. Although many of the recommendations are geared towards the previously undiagnosed neonate, the recommendations for a severely metabolically decompensated individual are applicable to any known patient as well. Initial management is critical for prevention of morbidity and mortality. The following manuscript provides recommendations for initial treatment and evaluation, a discussion of issues concerning transport to a metabolic center (if patient presents to a non-metabolic center), acceleration of management and preparation for discharge. PMID:22000903

Chapman, Kimberly A; Gropman, Andrea; MacLeod, Erin; Stagni, Kathy; Summar, Marshall L.; Ueda, Keiko; Mew, Nicholas Ah; Franks, Jill; Island, Eddie; Matern, Dietrich; Pena, Loren; Smith, Brittany; Sutton, V. Reid; Urv, Tiina; Venditti, Charles; Chakrapani, Anupam

2014-01-01

133

Propionate induces polymorphonuclear leukocyte activation and inhibits formylmethionyl-leucyl-phenylalanine-stimulated activation.  

PubMed Central

Short-chain carboxylic acids (SCCA) are metabolic by-products of bacterial pathogens which can alter cytoplasmic pH and inhibit a variety of polymorphonuclear leukocyte (PMN) motile functions. Since cytoskeletal F-actin alterations are central to PMN mobility, in this study we examined the effects of SCCA on cytoskeletal F-actin. Initially, we tested nine SCCA (formate, acetate, propionate, butyrate, valerate, caproate, lactate, succinate, and isobutyrate). We document here that while eight altered cytoplasmic pH, only six altered cytoskeletal F-actin. We then selected one SCCA that altered both F-actin and cytoplasmic pH (propionate) and one SCCA that altered only cytoplasmic pH (lactate) for further study. Propionate, but not lactate, caused an irregular cell shape and F-actin distribution. Furthermore, propionate, but not lactate, inhibited formylmethionyl-leucyl-phenylalanine (fMLP)-stimulated PMN polarization, F-actin localization, and cytoplasmic pH oscillation. Propionate-induced changes in cytoskeletal F-actin and cytoplasmic acidification were not affected by the fMLP receptor antagonist N-t-BOC-1-methionyl-1-leucyl-1-phenylalanine; however, alkalinization was affected. Pertussis toxin treatment completely inhibited propionate-induced changes in F-actin but had no effect on propionate-induced cytoplasmic pH oscillation. These results indicate that propionate (i) bypasses the fMLP receptor and G protein(s) to induce cytoplasmic pH oscillation, (ii) operates through G protein(s) to induce actin oscillation, cell shape changes (to irregular), and F-actin localization, and (iii) inhibits fMLP-stimulated cytoplasmic pH and actin oscillation, PMN polarization, and F-actin localization. Images PMID:1319407

Brunkhorst, B A; Kraus, E; Coppi, M; Budnick, M; Niederman, R

1992-01-01

134

40 CFR 721.8657 - Cerium, hydroxy oleate propionate complexes.  

Code of Federal Regulations, 2010 CFR

... Cerium, hydroxy oleate propionate complexes. 721.8657 Section 721.8657... Cerium, hydroxy oleate propionate complexes. (a) Chemical substance and significant...as Cerium, hydroxy oleate propionate complexes (PMN P-99-0026) is subject...

2010-07-01

135

Radiation-induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. IV. Studies on some physical properties and structural characterization by means of scanning electron microscopy. [Gamma radiation  

SciTech Connect

Binary mixtures of monomers, e.g., styrene and acrylamide in 1:1 methanol:water solution, were grafted onto cellulose acetate film by taking recourse to preirradiation grafting procedure. The surface modification of the films due to grafting was examined by means of scanning electron microscopy. The mechanical properties, e.g., tensile strength elongation at break, and elasticity as well as water vapor permeability of the grafted films, were investigated. In the case of ungrafted films or when acrylamide was grafted to a low extent, the film surfaces were smooth and hence were not modified to any significant extent. But when acrylamide was grated appreciably, or when styrene was grafted singly or in binary mixture with acrylamide, the surfaces were found to be covered with fibrils. The pattern of the surface modification also changes with the increase of the extent of grafting. The observed properties of the grafted films were explained on the basis of the electron microscopic results. 18 references, 7 figures, 2 tables.

Bhattacharyya, S.N.; Maldas, D.

1984-05-01

136

Solar photocatalytic gas-phase degradation of n-decane-a comparative study using cellulose acetate monoliths coated with P25 or sol-gel TiO2 films.  

PubMed

Cellulose acetate monoliths (CAM) were used as the substrate for the deposition of TiO2 films to produce honeycombed photoactive structures to fill a tubular photoreactor equipped with a compound parabolic collector. By using such a setup, an efficient single-pass gas-phase conversion was achieved in the degradation of n-decane, a model volatile organic compound. The CAM three-dimensional, gas-permeable transparent structure with a rugged surface enables a good adhesion of the catalytic coating. It also provides a rigid structure for packing the tubular photoreactor, and maximizing the illuminated catalyst surface. The efficiency of the photocatalytic oxidation (PCO) process on n-decane degradation was evaluated under different operating conditions, such as feeding concentration (73 and 146 ppm), gas stream flow rate (73, 150, and 300 mL min(-1)), relative humidity (3 and 25 %), and UV irradiance (18.9, 29.1, and 38.4 WUV m(-2)). The results show that n-decane degradation by neat photolysis is negligible, but mineralization efficiencies of 86 and 82 % were achieved with P25-CAM and SG-CAM, respectively, for parent pollutant conversions above 95 %, under steady-state conditions. A mass transfer model, considering the mass balance to the plug-flow packed photoreactor, and PCO reaction given by a Langmuir-Hinshelwood bimolecular non-competitive two types of sites equation, was able to predict well the PCO kinetics under steady-state conditions, considering all the operational parameters tested. Overall, the performance of P25-CAM was superior taking into account mineralization efficiency, cost of preparation, surface roughness, and robustness of the deposited film. PMID:24809494

Miranda, Sandra M; Lopes, Filipe V S; Rodrigues-Silva, Caio; Martins, Susana D S; Silva, Adrián M T; Faria, Joaquim L; Boaventura, Rui A R; Vilar, Vítor J P

2015-01-01

137

Wetting dynamics of alkyl ketene dimer on cellulosic model surfaces  

Microsoft Academic Search

The dynamic wetting of a commercial alkyl ketene dimer (AKD) wax was measured on model cellulosic surfaces. The variables investigated were temperature and the surface composition. The model surfaces consisted of cellulose and cellulose acetate films as well as glass. These surfaces are smooth by industrial standards but not on a molecular level. The objective of the study was to

Gil Garnier; Marylise Bertin; Miroslava Smrckova

1999-01-01

138

Engineering Propionibacterium freudenreichii subsp. shermanii for enhanced propionic acid fermentation: Effects of overexpressing propionyl-CoA:Succinate CoA transferase.  

PubMed

Propionibacterium freudenreichii subsp. shermanii naturally forms propionic acid as the main fermentation product with acetate and succinate as two major by-products. In this study, overexpressing the native propionyl-CoA:succinate CoA transferase (CoAT) in P. shermanii was investigated to evaluate its effects on propionic acid fermentation with glucose, glycerol, and their mixtures as carbon source. In general, the mutant produced more propionic acid, with up to 10% increase in yield (0.62 vs. 0.56g/g) and 46% increase in productivity (0.41 vs. 0.28g/Lh), depending on the fermentation conditions. The mutant also produced less acetate and succinate, with the ratios of propionate to acetate (P/A) and succinate (P/S) in the final product increased 50% and 23%, respectively, in the co-fermentation of glucose/glycerol. Metabolic flux analysis elucidated that CoAT overexpression diverted more carbon fluxes toward propionic acid, resulting in higher propionic acid purity and a preference for glycerol over glucose as carbon source. PMID:25447642

Wang, Zhongqiang; Ammar, Ehab M; Zhang, An; Wang, Liqun; Lin, Meng; Yang, Shang-Tian

2015-01-01

139

Propionic acid production in a plant fibrous-bed bioreactor with immobilized Propionibacterium freudenreichii CCTCC M207015.  

PubMed

A plant fibrous-bed bioreactor (PFB) was constructed for propionic acid production. Sugar cane bagasse was applied to the PFB as immobilizing material. Starting at a concentration of 80g/L of glucose, Propionibacterium freudenreichii CCTCC M207015 produced 41.20±2.03g/L of propionic acid at 108h in the PFB. The value was 21.07% higher than that produced by free cell fermentation. Intermittent and constant fed-batch fermentations were performed in the PFB to optimize the fermentation results. The highest propionic acid concentration obtained from constant fed-batch fermentation was 136.23±6.77g/L, which is 1.40 times higher than the highest concentration (97.00g/L) previously reported. Scanning electron microscopy analysis showed that cells exhibited striking changes in morphology after PFB domestication. Compared with free cell fermentation, the fluxes of propionic acid synthesis and the pentose phosphate pathway in PFB fermentation increased by 84.65% and 227.62%, respectively. On the other hand, a decrease in succinic and acetic acid fluxes was also observed. The metabolic flux distributions of the two PFB fed-batch fermentation strategies also demonstrated that constant fed-batch fermentation is a more beneficial method for the immobilized production of propionic acid. The relevant key enzyme activities and metabolic flux variations of the batch cultures showed good consistency. These results suggest that the PFB was effective in high-concentration propionic acid production. PMID:22982366

Chen, Fei; Feng, Xiaohai; Xu, Hong; Zhang, Dan; Ouyang, Pingkai

2012-12-15

140

Preparation of cellulose nanofibers with hydrophobic surface characteristics  

Microsoft Academic Search

The aim of this study was to develop cellulose nanofibers with hydrophobic surface characteristics using chemical modification.\\u000a Kenaf fibers were modified using acetic anhydride and cellulose nanofibers were isolated from the acetylated kenaf using mechanical\\u000a isolation methods. Fourier transform infrared spectroscopy (FTIR) indicated acetylation of the hydroxyl groups of cellulose.\\u000a The study of the dispersion demonstrated that acetylated cellulose nanofibers

Mehdi Jonoobi; Jalaluddin Harun; Aji P. Mathew; Mohd Zobir B. Hussein; Kristiina Oksman

2010-01-01

141

Metabolism of propionate by sheep liver  

PubMed Central

Experiments were conducted with aged nuclear-free homogenate of sheep liver and aged mitochondria in an attempt to measure both the extent of oxidation of propionate and the distribution of label from [2-14C]propionate in the products. With nuclear-free homogenate, propionate was 44% oxidized with the accumulation of succinate, fumarate, malate and some citrate. Recovery of 14C in these intermediates and respiratory carbon dioxide was only 33%, but additional label was detected in endogenous glutamate and aspartate. With washed mitochondria 30% oxidation of metabolized propionate occurred, and proportionately more citrate and malate accumulated. Recovery of 14C in dicarboxylic acids, citrate, ?-oxoglutarate, glutamate, aspartate and respiratory carbon dioxide was 91%. The specific activities of the products and the distribution of label in the carbon atoms of the dicarboxylic acids were consistent with the operation solely of the methylmalonate pathway together with limited oxidation of the succinate formed by the tricarboxylic acid cycle via pyruvate. In a final experiment with mitochondria the label consumed from [2-14C]propionate was entirely recovered in the intermediates of the tricarboxylic acid cycle, glutamate, aspartate, methylmalonate and respiratory carbon dioxide. PMID:6048786

Smith, R. M.; Osborne-White, W. S.; Russell, G. R.

1967-01-01

142

Metabolism of propionate by sheep liver. Oxidation of propionate by homogenates  

PubMed Central

1. The rate and stability to aging of the metabolism of propionate by sheep-liver slices and sucrose homogenates were examined. Aging for up to 20min. at 37° in the absence of added substrate had little effect with slices, whole homogenates or homogenates without the nuclear fraction. 2. Metabolism of propionate by sucrose homogenates was confined to the mitochondrial fraction, but the mitochondrial supernatant (microsomes plus cell sap) stimulated propionate removal. 3. The rate of propionate metabolism by liver slices was higher in a high potassium phosphate–bicarbonate medium [0·88(±s.e.m. 0·16)?mole/mg. of N/hr.] than in Krebs–Ringer bicarbonate medium [0·44(±s.e.m. 0·13)?mole/mg. of N/hr.]. 4. Metabolism of propionate by sucrose homogenates freed from nuclei was dependent on the presence of oxygen, carbon dioxide and ATP. Propionate removal was stimulated 250% by Mg2+ ions and 670% by cytochrome c. 5. In the complete medium 2·39(±s.e.m. 0·15)?moles of propionate were consumed/mg. of N/hr. 6. The ratio of oxygen consumption to propionate utilization was sufficient to account for the complete oxidation of half the propionate consumed. 7. The only products detected under these conditions were succinate, fumarate and malate. Propionate had no effect on the production of lactate from endogenous sources and did not itself give rise to lactate. 8. Methylmalonate did not accumulate when propionate was metabolized and was not oxidized. It was detected as an intermediate in the conversion of propionyl-CoA into succinate. The rate of this reaction sequence was adequate to account for the rate of propionate metabolism by sucrose homogenates or slices, provided that the rate of formation of propionyl-CoA was not limiting. 9. The methylmalonate pathway was predominantly a mitochondrial function. 10. The metabolism of propionate appeared to be dependent on active oxidative phosphorylation. PMID:14340092

Smith, R. M.; Osborne-White, W. S.

1965-01-01

143

In vitro fermentation of cellulose, beet pulp, citrus pulp, and citrus pectin using fecal inoculum from cats, dogs, horses, humans, and pigs and ruminal fluid from cattle.  

PubMed

We evaluated the influence of gastrointestinal tract microflora from several species on fiber fermentation characteristics in vitro. Selected fibrous substrates (cellulose, beet pulp, citrus pulp, and citrus pectin) were incubated for 6, 12, 24, and 48 h with ruminal fluid from cattle or feces from dogs, cats, pigs, horses, or humans. When data were pooled across all substrates and fermentation times, OM disappearance (29.4%) and acetate, propionate, butyrate, and total short-chain fatty acid (SCFA) production (1.09, .41, .12, and 1.61 mmol/g of OM, respectively) were lowest (P < .05), and lactate production (.23 mmol/g of OM) was greatest (P < .05) for horse fecal microflora compared with samples from the other species. The greatest (P < .05) acetate production resulted when substrates were fermented by cat fecal microflora (2.38 mmol/g of OM). The greatest (P < .05) propionate productions resulted from pig fecal and cattle ruminal microflora (.88 and .83 mmol/g of OM, respectively), and the greatest (P < .05) butyrate productions resulted from human and pig fecal microflora (.39 and .40 mmol/g of OM, respectively). Total SCFA production was greatest (P < .05) for cat fecal microflora (3.38 mmol/g of OM). When data were pooled across the species, substrate OM disappearance and SCFA production ranked from least to greatest in the following order: cellulose < beet pulp < citrus pulp < citrus pectin. The fermentability of different fibrous substrates by fecal or ruminal microflora from various species seems to be dependent not only on the fermentative activity of the microbial population but on other factors as well, perhaps lag time and rate of digesta passage. PMID:8655439

Sunvold, G D; Hussein, H S; Fahey, G C; Merchen, N R; Reinhart, G A

1995-12-01

144

21 CFR 522.842 - Estradiol benzoate and testosterone propionate.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Estradiol benzoate and testosterone propionate. 522...ANIMAL DRUGS § 522.842 Estradiol benzoate and testosterone propionate. (a...i) 20 milligrams (mg) estradiol benzoate and 200 mg testosterone...

2010-04-01

145

Comparison of physical properties of regenerated cellulose films fabricated with different cellulose feedstocks in ionic liquid.  

PubMed

With the serious "white pollution" resulted from the non-biodegradable plastic films, considerable attention has been directed toward the development of renewable and biodegradable cellulose-based film materials as substitutes of petroleum-derived materials. In this study, environmentally friendly cellulose films were successfully prepared using different celluloses (pine, cotton, bamboo, MCC) as raw materials and ionic liquid 1-ethyl-3-methylimidazolium acetate as a solvent. The SEM and AFM indicated that all cellulose films displayed a homogeneous and smooth surface. In addition, the FT-IR and XRD analysis showed the transition from cellulose I to II was occurred after the dissolution and regeneration process. Furthermore, the cellulose films prepared by cotton linters and pine possessed the most excellent thermal stability and mechanical properties, which were suggested by the highest onset temperature (285°C) and tensile stress (120MPa), respectively. Their excellent properties of regenerated cellulose films are promising for applications in food packaging and medical materials. PMID:25659673

Pang, JinHui; Wu, Miao; Zhang, QiaoHui; Tan, Xin; Xu, Feng; Zhang, XueMing; Sun, RunCang

2015-05-01

146

A proposed citramalate cycle for acetate assimilation in the purple non-sulfur bacterium Rhodospirillum rubrum  

Microsoft Academic Search

During phototrophic growth on acetate and CO2Rhodospirillum rubrum 2R contained malate synthase but lacked isocitrate lyase. Acetate assimilation by R. rubrum cells was stimulated by pyruvate, propionate glyoxylate, CO2 and H2. Acetate photoassimilation by R. rubrum cells in the presence of bicarbonate was accompanied by glyoxylate secretion, which increased after addition of fluoroacetate and decreased after addition of malonate. When

Ruslan N Ivanovsky; Elena N Krasilnikova; Ivan A Berg

1997-01-01

147

Interactions of alfalfa hay and sodium propionate on dairy calf performance and rumen development.  

PubMed

The objective of this experiment was to investigate the effects of different levels of alfalfa hay (AH) and sodium propionate (Pro) added to starter diets of Holstein calves on growth performance, rumen fermentation characteristics, and rumen development. Forty-two male Holstein calves (40±2kg of birth weight) were used in a complete randomized design with a 3×2 factorial arrangement of treatments. Dietary treatments were as follows: (1) control = concentrate only; (2) Pro = concentrate with 5% sodium propionate [dry matter (DM) basis]; (3) 5% AH = concentrate + 5% alfalfa hay (DM basis); (4) 5% AH + Pro = concentrate + 5% alfalfa hay + 5% sodium propionate (DM basis); (5) 10% AH = concentrate + 10% alfalfa hay (DM basis); and (6) 10% AH + Pro = concentrate + 10% alfalfa hay + 5% sodium propionate (DM basis). All calves were housed in individual pens bedded with sawdust until 10wk of age. They were given ad libitum access to water and starter throughout the experiment and were fed 2L of milk twice daily. Dry matter intake was recorded daily and body weight weekly. Calves from the control, 10% AH, and 10% AH + Pro treatments were euthanized after wk 10, and rumen wall samples were collected. Feeding of forage was found to increase overall dry matter intake, average daily gain, and final weight; supplementing sodium propionate had no effect on these parameters. Calves consuming forage had lower feed efficiency than those on the Pro diet. Rumen fluid in calves consuming forage had higher pH and greater concentrations of total volatile fatty acids and molar acetate. Morphometric parameters of the rumen wall substantiated the effect of AH supplementation, as plaque formation decreased macroscopically. Overall, the interaction between forage and sodium propionate did not affect calf performance parameters measured at the end of the experiment. Furthermore, inclusion of AH in starter diets positively enhanced the growth performance of male Holstein calves and influenced both the macroscopic and microscopic appearances of the rumen wall. These benefits, however, were small when only sodium propionate was offered. PMID:24508441

Beiranvand, H; Ghorbani, G R; Khorvash, M; Nabipour, A; Dehghan-Banadaky, M; Homayouni, A; Kargar, S

2014-04-01

148

Preparation and application of cellulose triacetate microspheres.  

PubMed

Cellulose triacetate was prepared via reacting of a mixture of acetic anhydride and acetic acid containing sulfuric acid as catalyst with ramie fiber obtained from a biomass of ramie. The cellulose triacetate with a degree of substitution (DS) 2.93 of the ramie fiber was obtained. The honeycomb-like cellulose triacetate microspheres with an average diameter of 14 microm were made from the cellulose triacetate solution. The optimum conditions for preparing the microspheres were determined as cellulose triacetate/dichloromethane ratio 1:7 (w/w), and 0.75% sodium dodecylsulfonate. The cellulose triacetate microspheres were characterized using FT-IR, NMR, XRD, and SEM. Application of the microspheres as an adsorbent for removing disperse dyes in water was investigated under the temperatures from 15 to 50 degrees C, pHs from 4 to 9, and the weight of cellulose triacetate microspheres from 0.03 to 0.09 g. The cellulose triacetate microspheres exhibited a 16.5mg/g capability to remove DR dye from water at 50 degrees C and pH 7. PMID:20060644

Fan, Xiushan; Liu, Zhao-Tie; Liu, Zhong-Wen

2010-05-15

149

Cellulose based bulk pH optomembranes  

Microsoft Academic Search

The paper presents an efficient technique for the preparation of pH-sensitive bulk optomembranes for fiber optic chemical sensors (FOCS). The method is based on the physical entrapment of the reagent molecules in the bulk of cellulose acetate membranes. The durable immobilization of a pH indicator is achieved by the addition of an appropriate ion-balance reagent to the cellulose matrix. The

Wojciech Wróblewski; Ewa Ro?niecka; Artur Dybko; Zbigniew Brzózka

1998-01-01

150

Low-cost propionate salt as road deicer: evaluation of cheese whey and other media constituents  

Microsoft Academic Search

Propionate and acetate salts are environmentally friendly, effective road deicer substitutes for widely used sodium chloride.\\u000a A low-cost medium, using raw cheese whey and hydrolyzed whey permeate\\/whey permeate powder as substrates, and corn-steep liquor\\u000a as a nutrient supplement, was studied for lactic acid production, replacing synthetic lactose and other high-cost nutrients.\\u000a A non-sterile stage-I fermentation process for improved lactate productivity

Praveen V. Vadlani; Alexander P. Mathews; Greg S. Karr

2008-01-01

151

Wetting mechanism of alkyl ketene dimers on cellulose films  

Microsoft Academic Search

The wetting mechanism of a commercial Alkyl ketene dimers (AKD) wax on smooth cellulose films was investigated by following the contact angle of sessile drops for differing periods of time ranging from 1s to 24h. The advancing and receding contact angles formed by droplets of AKD melt and water over other model surfaces such as glass, cellulose acetate films and

G. Garnier; J. Wright; L. Godbout; L. Yu

1998-01-01

152

Hydroxypropylation of cellulose as a pretreatment for enzymatic hydrolysis  

E-print Network

Dr. E. J. Soltes Cellulose derivatives such as carboxymethylcellulose and water soluble cellulose acetate have shown increased ability to be converted to reducing sugars, including glucose, compared to pure cellulose. Hydroxypropylcellulose (HPC... of substituted AHG. Fermentation of enzymatic hydrolyzates, obtained from HPC samples, confirmed that the presence of hydroxypropyl derivatives does not inhibit the production of ethyl alcohol. DEDICATION This thesis is dedicated to Kim, Ryan, and Holly...

Brix, Scott Tyson

2012-06-07

153

Desulfotomaculum thermobenzoicum subsp. thermosyntrophicum subsp. nov., a thermophilic, syntrophic, propionate-oxidizing, spore-forming bacterium.  

PubMed

From granular sludge from a laboratory-scale upflow anaerobic sludge bed reactor operated at 55 degrees C with a mixture of volatile fatty acids as feed, a novel anaerobic, moderately thermophilic, syntrophic, spore-forming bacterium, strain TPO, was enriched on propionate in co-culture with Methanobacterium thermoautotrophicum Z245. The axenic culture was obtained by using pyruvate as the sole source of carbon and energy. The cells were straight rods with pointed ends and became lens-shaped when sporulation started. The cells were slightly motile. The optimum growth temperature was 55 degrees C and growth was possible between 45 and 62 degrees C. The pH range for growth of strain TPO was 6-8, with an optimum at pH 7-7.5. Propionate was converted to acetate, CO2 and CH4 by a co-culture of strain TPO with Methanobacterium thermoautotrophicum Z245. In pure culture, strain TPO could grow fermentatively on benzoate, fumarate, H2/CO2, pyruvate and lactate. Sulphate could serve as inorganic electron acceptor when strain TPO was grown on propionate, lactate, pyruvate and H2/CO2. The G+C content was 53.7 mol%. Comparison of 16S rDNA sequences revealed that strain TPO is related to Desulfotomaculum thermobenzoicum (98%) and Desulfotomaculum thermoacetoxidans (98%). DNA-DNA hybridization revealed 88.2% reassociation between strain TPO and D. thermobenzoicum and 83.8% between strain TPO and D. thermoacetoxidans. However, both organisms differ physiologically from strain TPO and are not capable of syntrophic propionate oxidation. It is proposed that strain TPO should be classified as new subspecies of D. thermobenzoicum as D. thermobenzoicum subsp. thermosyntrophicum. PMID:11931147

Plugge, Caroline M; Balk, Melike; Stams, Alfons J M

2002-03-01

154

Shift of Propionate-Oxidizing Bacteria with HRT Decrease in an UASB Reactor Containing Propionate as a Sole Carbon Source.  

PubMed

Propionate is a main intermediate product, and its degradation is crucial for maintaining the efficiency and stability of an anaerobic reactor. However, there was little information about the effects of ecological factor on propionate-oxidizing bacteria. In current research, microbial community composition and quantitative analysis of some identified propionate-oxidizing bacteria with hydraulic retention time (HRT) decrease in an upflow anaerobic sludge blanket (UASB) reactor containing propionate as sole carbon source was investigated. The results showed that propionate-oxidizing bacteria from Syntrophobacter, Pelotomaculum, and Smithella were major functional bacteria in this UASB system. Most propionate-oxidizing bacteria in composition have not changed with HRT decrease. However, the number of previously identified propionate-oxidizing bacteria from these three genera exhibited significant shift. Under HRT 10 h condition, Pelotomaculum schinkii was dominant and its quantity was 1.2?×?10(4) 16S ribosomal RNA (rRNA) gene copies/ng DNA, occupying 56.2 % in total detectable propionate-oxidizing bacteria. HRT decrease from 10 h to 8 and 6 h stepwise resulted in P. schinkii, Syntrophobacter sulfatireducens and Smithella propionica becoming the main population. HRT decrease from 6 to 4 h did not markedly change the amount of propionate-oxidizing bacteria, but S. propionica dominated in the reactor. PMID:25261998

Ban, Qiaoying; Zhang, Liguo; Li, Jianzheng

2014-09-28

155

Effect of acetyl groups on enzymatic hydrolysis of cellulosic substrates  

Microsoft Academic Search

Evidence showed that acetyl groups introduced during acetic acid delignification was a primary cause of the poor enzymatic digestibility of acetic acid pulp. The inhi- bition by acetyl groups could be removed by saponifi- cation. Acetyl groups might inhibit the enzymes by interfering with the productive binding (hydrogen bonds) between cellulose and the catalytic domain of cellulases, by affecting the

Xuejun Pan; Neil Gilkes; Jack N. Saddler

2006-01-01

156

CELLULOSE SHAPES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent high resolution fiber diffraction studies of four forms of crystalline cellulose are reviewed. All have two-fold screw-axis symmetry, There is little difference among the various chain shapes in the crystal environment, except for the O6 position and the hydrogen bonding schemes. The parallel...

157

Bacterial production of short-chain organic acids and trehalose from levulinic acid: A potential cellulose-derived building block as a feedstock for microbial production.  

PubMed

Levulinic acid (LA) is a platform chemical derived from cellulosic biomass, and the expansion of LA utilization as a feedstock is important for production of a wide variety of chemicals. To investigate the potential of LA as a substrate for microbial conversion to chemicals, we isolated and identified LA-utilizing bacteria. Among the six isolated strains, Pseudomonas sp. LA18T and Rhodococcus hoagie LA6W degraded up to 70g/L LA in a high-cell-density system. The maximal accumulation of acetic acid by strain LA18T and propionic acid by strain LA6W was 13.6g/L and 9.1g/L, respectively, after a 4-day incubation. Another isolate, Burkholderia stabilis LA20W, produced trehalose extracellularly in the presence of 40g/L LA to approximately 2g/L. These abilities to produce useful compounds supported the potential of microbial LA conversion for future development and cellulosic biomass utilization. PMID:25479689

Habe, Hiroshi; Sato, Shun; Morita, Tomotake; Fukuoka, Tokuma; Kirimura, Kohtaro; Kitamoto, Dai

2015-02-01

158

Identification of Two prpDBC Gene Clusters in Corynebacterium glutamicum and Their Involvement in Propionate Degradation via the 2-Methylcitrate Cycle  

PubMed Central

Genome sequencing revealed that the Corynebacterium glutamicum genome contained, besides gltA, two additional citrate synthase homologous genes (prpC) located in two different prpDBC gene clusters, which were designated prpD1B1C1 and prpD2B2C2. The coding regions of the two gene clusters as well as the predicted gene products showed sequence identities of about 70 to 80%. Significant sequence similarities were found also to the prpBCDE operons of Escherichia coli and Salmonella enterica, which are known to encode enzymes of the propionate-degrading 2-methylcitrate pathway. Homologous and heterologous overexpression of the C. glutamicum prpC1 and prpC2 genes revealed that their gene products were active as citrate synthases and 2-methylcitrate synthases. Growth tests showed that C. glutamicum used propionate as a single or partial carbon source, although the beginning of the exponential growth phase was strongly delayed by propionate for up to 7 days. Compared to growth on acetate, the specific 2-methylcitrate synthase activity increased about 50-fold when propionate was provided as the sole carbon source, suggesting that in C. glutamicum the oxidation of propionate to pyruvate occurred via the 2-methylcitrate pathway. Additionally, two-dimensional gel electrophoresis experiments combined with mass spectrometry showed strong induction of the expression of the C. glutamicum prpD2B2C2 genes by propionate as an additional carbon source. Mutational analyses revealed that only the prpD2B2C2 genes were essential for the growth of C. glutamicum on propionate as a sole carbon source, while the function of the prpD1B1C1 genes remains obscure. PMID:11976302

Claes, Wilfried A.; Pühler, Alfred; Kalinowski, Jörn

2002-01-01

159

Enrichment of amino acid-oxidizing, acetate-reducing bacteria.  

PubMed

In anaerobic condition, amino acids are oxidatively deaminated, and decarboxylated, resulting in the production of volatile fatty acids. In this process, excess electrons are produced and their consumption is necessary for the accomplishment of amino acid degradation. In this study, we anaerobically constructed leucine-degrading enrichment cultures from three different environmental samples (compost, excess sludge, and rice field soil) in order to investigate the diversity of electron-consuming reaction coupled to amino acid oxidation. Constructed enrichment cultures oxidized leucine to isovalerate and their activities were strongly dependent on acetate. Analysis of volatile fatty acids (VFAs) profiles and community structure analysis during batch culture of each enrichment indicated that Clostridium cluster I coupled leucine oxidation to acetate reduction in the enrichment from the compost and the rice field soil. In these cases, acetate was reduced to butyrate. On the other hand, Clostridium cluster XIVb coupled leucine oxidation to acetate reduction in the enrichment from the excess sludge. In this case, acetate was reduced to propionate. To our surprise, the enrichment from rice field soil oxidized leucine even in the absence of acetate and produced butyrate. The enrichment would couple leucine oxidation to reductive butyrate synthesis from CO2. The coupling reaction would be achieved based on trophic link between hydrogenotrophic acetogenic bacteria and acetate-reducing bacteria by sequential reduction of CO2 and acetate. Our study suggests anaerobic degradation of amino acids is achieved yet-to-be described reactions. PMID:24630616

Ato, Makoto; Ishii, Masaharu; Igarashi, Yasuo

2014-08-01

160

Cellulose synthase interacting protein  

PubMed Central

Cellulose is the most abundant biopolymer on earth. The great abundance of cellulose places it at the forefront as a primary source of biomass for renewable biofuels. However, the knowledge of how plant cells make cellulose remains very rudimentary. Cellulose microfibrils are synthesized at the plasma membrane by hexameric protein complexes, also known as cellulose synthase complexes. The only known components of cellulose synthase complexes are cellulose synthase (CESA) proteins until the recent identification of a novel component. CSI1, which encodes CESA interacting protein 1 (CSI1) in Arabidopsis. CSI1, as the first non-CESA proteins associated with cellulose synthase complexes, opens up many opportunities. PMID:21150290

Somerville, Chris

2010-01-01

161

Cellulose membranes for reverse osmosis part II. Improving RO membranes prepared from non-woody cellulose  

Microsoft Academic Search

Experiments were carried out to minimize the stages of preparing reverse osmosis (RO) desalination membranes at economical cost and to improve the transport properties of RO membranes prepared from non-wood fibrous materials (cotton linters and bagasse pulp) to approach those prepared from imported viscose pulp and purchased cellulose acetate (see Part I). Further study was carried out on examining the

Altaf H. Basta; Houssni El-Saied; M. Elberry

2003-01-01

162

Properties of cellulose derivatives produced from radiation—Modified cellulose pulps  

NASA Astrophysics Data System (ADS)

The aim of project was elaboration of radiation methods for properties modification of cellulose pulps using for derivatives production. The selected cellulose pulps were exposed to an electron beam with energy 10 MeV in a linear accelerator. After irradiation pulps underwent the structural and physico-chemical investigations. The laboratory test for manufacturing carboxymethylocellulose (CMC), cellulose carbamate (CC) and cellulose acetate (CA) with cellulose pulps irradiated dose 10 and 15 kGy have been performed. Irradiation of the pulp influenced its depolimerisation degree and resulted in the drop of viscosity of CMC. However, the expected level of cellulose activation expressed as a rise of the substitution degree or increase of the active substance content in the CMC sodium salt was not observed. In the case of cellulose esters (CC, CA) formation, the action of ionising radiation on cellulose pulps with the dose 10 and 15 kGy enables obtaiment of the average values of polimerisation degree as required for CC soluble in aqueous sodium hydroxide solution. The properties of derivatives prepared by means of radiation and classic methods were compared.

Iller, Edward; Stupi?ska, Halina; Starostka, Pawe?

2007-07-01

163

Preparation of regenerated cellulose fiber via carbonation. I. Carbonation and dissolution in an aqueous NaOH solution  

Microsoft Academic Search

Cellulose carbonate was prepared by the reaction of cellulose pulp and CO2 with treatment reagents, such as aqueous ZnCl2 (20–40 wt%) solution, acetone or ethyl acetate, at ?5–0°C and 30–40 bar (CO2) for 2 hr. Among the treatment reagents, ethyl acetate was the most effective. Cellulose carbonate was dissolved in 10% sodium\\u000a hydroxide solution containing zinc oxide up to 3

Sang Youn Oh; Dong Il Yoo; Younsook Shin; Wha Seop Lee; Seong Mu Jo

2002-01-01

164

Cellulose Insulation  

NASA Technical Reports Server (NTRS)

Fire retardant cellulose insulation is produced by shredding old newspapers and treating them with a combination of chemicals. Insulating material is blown into walls and attics to form a fiber layer which blocks the flow of air. All-Weather Insulation's founders asked NASA/UK-TAP to help. They wanted to know what chemicals added to newspaper would produce an insulating material capable of meeting federal specifications. TAP researched the query and furnished extensive information. The information contributed to successful development of the product and helped launch a small business enterprise which is now growing rapidly.

1980-01-01

165

75 FR 51055 - Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...EPA-HQ-OPP-2010-0650; FRL-8840-5] Propionic Acid and Salts, and Urea Sulfate; Registration Review...decisions for the pesticides propionic acid and salts, and urea sulfate and opens a public comment...pesticide formulations. Propionic acid and its salts, sodium and calcium propionates,...

2010-08-18

166

Acetic acid pulping of wheat straw under atmospheric pressure  

Microsoft Academic Search

Atmospheric acetic acid pulping of wheat straw was carried out. Pulping conditions and their effects on pulp properties were\\u000a investigated in detail, and a comparison between acetic acid (AcOH) pulp and soda-anthraquinone (AQ) pulps of wheat straw\\u000a was made of the chemical composition, strength, and fiber morphology of the pulps. Wheat straw was successfully pulped and\\u000a fractionated into pulp (cellulose),

Xue-Jun Pan; Yoshihiro Sano

1999-01-01

167

Paludibacter jiangxiensis sp. nov., a strictly anaerobic, propionate-producing bacterium isolated from rice paddy field.  

PubMed

A mesophilic, obligately anaerobic, propionate-producing fermentative bacterium, designated strain NM7(T), was isolated from rural rice paddy field. Cells of strain NM7(T) are Gram-negative, non-motile, non-spore-forming, short rods, and negative for catalase. The strain grew optimally at 37 °C (the range for growth 15-40 °C) and pH 7.0 (pH 5.0-7.5). The strain could grow fermentatively on various sugars, including arabinose, xylose, fructose, galactose, glucose, mannose, cellobiose, lactose, maltose, sucrose, pectin and starch. The main end products of glucose fermentation were acetate and propionate. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe(III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of genomic DNA was 42.8 mol%. The major cellular fatty acids were C15:0, anteiso-C15:0, C16:0, and C17:0. The most abundant polar lipid of strain NM7(T) was phosphatidylethanolamine. 16S rRNA gene sequence analysis revealed that it belongs to the family Porphyromonadaceae of the phylum Bacteroidetes. The closest recognized species was Paludibacter propionicigenes (91.4 % similarity in 16S rRNA gene sequence). A novel species, Paludibacter jiangxiensis sp. nov., is proposed to accommodate strain NM7(T) (=JCM 17480(T) = CGMCC 1.5150(T) = KCTC 5844(T)). PMID:24419224

Qiu, Yan-Ling; Kuang, Xiao-Zhu; Shi, Xiao-Shuang; Yuan, Xian-Zheng; Guo, Rong-Bo

2014-03-01

168

Synthesis and pharmacological evaluation of carvacrol propionate.  

PubMed

This study aimed at synthesizing the carvacrol propionate (CP) and evaluating its pharmacological profile. CP was obtained from carvacrol and propionyl chloride through an esterification reaction. Male Swiss mice were treated with CP (25, 50, or 100 mg/kg). We evaluated the analgesic effect, mechanical hyperalgesia, and anti-inflammatory effect. Pre-treatment with CP inhibited (p<0.01 and 0.001) the formalin-induced nociception in both phases. CP inhibited (p<0.05, 0.01, and 0.001) the development of mechanical hyperalgesia. CP was able to decrease the leukocyte recruitment (p<0.001) and the amount of TNF-? (p<0.001), IL-1? (p<0.05), and protein leakage (p<0.01) into the pleural cavity. In addition, the paw edema was inhibited by CP (p<0.05, 0.01, and 0.001). The CP attenuates nociception, mechanical hyperalgesia, and inflammation, through an inhibition of cytokines. PMID:24710701

de Santana, Marilia Trindade; Silva, Viviane Barros; de Brito, Renan Guedes; dos Santos, Priscila Laíse; de Holanda Cavalcanti, Sócrates Cabral; Barreto, Emiliano Oliveira; de Souza Ferro, Jamylle Nunes; dos Santos, Márcio Roberto Viana; de Sousa Araújo, Adriano Antunes; Quintans-Júnior, Lucindo José

2014-10-01

169

Utilization of biocatalysts in cellulose waste minimization  

SciTech Connect

Cellulose, a polymer of glucose, is the principal component of biomass and, therefore, a major source of waste that is either buried or burned. Examples of biomass waste include agricultural crop residues, forestry products, and municipal wastes. Recycling of this waste is important for energy conservation as well as waste minimization and there is some probability that in the future biomass could become a major energy source and replace fossil fuels that are currently used for fuels and chemicals production. It has been estimated that in the United States, between 100-450 million dry tons of agricultural waste are produced annually, approximately 6 million dry tons of animal waste, and of the 190 million tons of municipal solid waste (MSW) generated annually, approximately two-thirds is cellulosic in nature and over one-third is paper waste. Interestingly, more than 70% of MSW is landfilled or burned, however landfill space is becoming increasingly scarce. On a smaller scale, important cellulosic products such as cellulose acetate also present waste problems; an estimated 43 thousand tons of cellulose ester waste are generated annually in the United States. Biocatalysts could be used in cellulose waste minimization and this chapter describes their characteristics and potential in bioconversion and bioremediation processes.

Woodward, J.; Evans, B.R.

1996-09-01

170

Np(v) complexation with propionate in 0.5-4 M NaCl solutions at 20-85 °C.  

PubMed

Low molecular weight organics (LMWO; e.g. acetate, propionate, lactate) can significantly impact the speciation and mobility of radionuclides in aqueous media. Natural clay rock formation, considered as a potential host rock for nuclear waste disposal, can contain a significant amount of organic matter. There are less thermodynamic data reported for the complexation of pentavalent actinides with LMWO, especially under elevated temperature conditions, relevant for assessing the long-term safety of disposal options for heat-producing high-level nuclear waste. In the present study, the complexation of Np(v) with propionate is studied using spectroscopic techniques in 0.5-4 M NaCl solutions by systematic variation of the ligand concentration and temperature. Slope analysis shows the formation of the 1?:?1 NpO2-propionate complex (NpO2Prop). The local structure of the NpO2-propionate complex is determined by extended X-ray absorption fine structure spectroscopy, the results of which suggest that propionate binds to Np(v) in a bidentate mode. Using the specific ion interaction theory (SIT), the stability constant at zero ionic strength and 25 °C is determined as log??°1,1 = 1.26 ± 0.03. The stability constants increase continuously with increasing temperature between 20 and 85 °C. The log??0 values are linearly correlated with the reciprocal temperature, indicating ?rH = const. and ?rC = 0, allowing the calculation of ?rH and ?rS for the formation of the NpO2-propionate complex using the integrated van't Hoff equation. The thermodynamic evaluation indicates that the reaction is endothermic and entropy driven. PMID:25611787

Vasiliev, Aleksandr N; Banik, Nidhu L; Marsac, Rémi; Froehlich, Daniel R; Rothe, Jörg; Kalmykov, Stepan N; Marquardt, Christian M

2015-02-10

171

Condensation of acetol and acetic acid vapor with sprayed liquid  

Technology Transfer Automated Retrieval System (TEKTRAN)

A cellulose-derived fraction of biomass pyrolysis vapor was simulated by evaporating acetol and acetic acid (AA) from flasks on a hot plate. The liquid in the flasks was infused with heated nitrogen. The vapor/nitrogen stream was superheated in a tube oven and condensed by contact with a cloud of ...

172

Cellulose- and Xylan-Degrading Thermophilic Anaerobic Bacteria from Biocompost ? †  

PubMed Central

Nine thermophilic cellulolytic clostridial isolates and four other noncellulolytic bacterial isolates were isolated from self-heated biocompost via preliminary enrichment culture on microcrystalline cellulose. All cellulolytic isolates grew vigorously on cellulose, with the formation of either ethanol and acetate or acetate and formate as principal fermentation products as well as lactate and glycerol as minor products. In addition, two out of nine cellulolytic strains were able to utilize xylan and pretreated wood with roughly the same efficiency as for cellulose. The major products of xylan fermentation were acetate and formate, with minor contributions of lactate and ethanol. Phylogenetic analyses of 16S rRNA and glycosyl hydrolase family 48 (GH48) gene sequences revealed that two xylan-utilizing isolates were related to a Clostridium clariflavum strain and represent a distinct novel branch within the GH48 family. Both isolates possessed high cellulase and xylanase activity induced independently by either cellulose or xylan. Enzymatic activity decayed after growth cessation, with more-rapid disappearance of cellulase activity than of xylanase activity. A mixture of xylan and cellulose was utilized simultaneously, with a significant synergistic effect observed as a reduction of lag phase in cellulose degradation. PMID:21317267

Sizova, M. V.; Izquierdo, J. A.; Panikov, N. S.; Lynd, L. R.

2011-01-01

173

Cellulose- and xylan-degrading thermophilic anaerobic bacteria from biocompost.  

PubMed

Nine thermophilic cellulolytic clostridial isolates and four other noncellulolytic bacterial isolates were isolated from self-heated biocompost via preliminary enrichment culture on microcrystalline cellulose. All cellulolytic isolates grew vigorously on cellulose, with the formation of either ethanol and acetate or acetate and formate as principal fermentation products as well as lactate and glycerol as minor products. In addition, two out of nine cellulolytic strains were able to utilize xylan and pretreated wood with roughly the same efficiency as for cellulose. The major products of xylan fermentation were acetate and formate, with minor contributions of lactate and ethanol. Phylogenetic analyses of 16S rRNA and glycosyl hydrolase family 48 (GH48) gene sequences revealed that two xylan-utilizing isolates were related to a Clostridium clariflavum strain and represent a distinct novel branch within the GH48 family. Both isolates possessed high cellulase and xylanase activity induced independently by either cellulose or xylan. Enzymatic activity decayed after growth cessation, with more-rapid disappearance of cellulase activity than of xylanase activity. A mixture of xylan and cellulose was utilized simultaneously, with a significant synergistic effect observed as a reduction of lag phase in cellulose degradation. PMID:21317267

Sizova, M V; Izquierdo, J A; Panikov, N S; Lynd, L R

2011-04-01

174

HPTLC-densitometric method for simultaneous determination of salmeterol xinafoate and fluticasone propionate in dry powder inhalers  

PubMed Central

A high performance thin layer chromatography (HPTLC) method was developed and validated for determination of two anti-asthmatic drugs, salmeterol xinafoate and fluticasone propionate in co-formulations. Study was performed on pre-coated silica gel HPTLC plates using n-hexane:ethyl acetate:acetic acid (5:10:0.2) as a mobile phase. A TLC scanner set at 250 nm was used for direct evaluation of the chromatograms in reflectance/absorbance mode. Method was validated according to ICH guidelines. Determination coefficients of calibration curves were found 0.9977 and 0.9936 in the ranges 100–1000 and 200–2000 ng band?1 for salmeterol and fluticasone, respectively. Method had an accuracy of 99.5% for salmeterol and 102.01% for fluticasone. Method had the potential to determine these drugs simultaneously from dosage forms without any interference. PMID:23964174

Kasaye, Lantider; Hymete, Ariaya; Mohamed, Abdel-Maaboud I.

2010-01-01

175

CCMR: Cellulose Fiber Spinning  

NSDL National Science Digital Library

The environmentally friendly production of cellulose fibers is the ultimate goal of this project, other factors need to be researched before they can be made, including the effects of different coagulants and molecular weight celluloses on cellulose recrystallization. With this, this project focused on studying the effects of 2 coagulants, methanol and ethanol, as well as the effects of a lower molecular weight and a higher molecular weight cellulose, Cellulose CC41 and Weyerhauser Flint River Lyocell August Trial wood pulp respectively, on cellulose recrystallization.

Carranco, Kristen

2004-08-17

176

Preparation and application of cationic cellulose fibers modified by in situ grafting of cationic PVA  

Microsoft Academic Search

Rendering the cellulose fiber cationic via in situ graft copolymerization has been regarded as one of the effective approaches to improve the filler retention and distribution. In this work, cationic cellulose fibers were prepared by in situ copolymerization of vinyl acetate (VAc) and diallyldimethyl ammonium chloride (DADMAC) onto softwood sulphite pulp fibers using ceric ammonium nitrate (CAN) as a free

Yizhou Sang; Huining Xiao

2009-01-01

177

Transports of acetate and haloacetate in Burkholderia species MBA4 are operated by distinct systems  

PubMed Central

Background Acetate is a commonly used substrate for biosynthesis while monochloroacetate is a structurally similar compound but toxic and inhibits cell metabolism by blocking the citric acid cycle. In Burkholderia species MBA4 haloacetate was utilized as a carbon and energy source for growth. The degradation of haloacid was mediated by the production of an inducible dehalogenase. Recent studies have identified the presence of a concomitantly induced haloacetate-uptake activity in MBA4. This uptake activity has also been found to transport acetate. Since acetate transporters are commonly found in bacteria it is likely that haloacetate was transported by such a system in MBA4. Results The haloacetate-uptake activity of MBA4 was found to be induced by monochloroacetate (MCA) and monobromoacetate (MBA). While the acetate-uptake activity was also induced by MCA and MBA, other alkanoates: acetate, propionate and 2-monochloropropionate (2MCPA) were also inducers. Competing solute analysis showed that acetate and propionate interrupted the acetate- and MCA- induced acetate-uptake activities. While MCA, MBA, 2MCPA, and butyrate have no effect on acetate uptake they could significantly quenched the MCA-induced MCA-uptake activity. Transmembrane electrochemical potential was shown to be a driving force for both acetate- and MCA- transport systems. Conclusions Here we showed that acetate- and MCA- uptake in Burkholderia species MBA4 are two transport systems that have different induction patterns and substrate specificities. It is envisaged that the shapes and the three dimensional structures of the solutes determine their recognition or exclusion by the two transport systems. PMID:23167477

2012-01-01

178

[On the nonexistence of propionic acid in various kinds of breeds (author's transl)].  

PubMed

Analyses of 45 samples of sour dough and various kinds of bread have shown that no appreciable amounts of propionic acid are formed during sour dough fermentation. Bread has no natural propionic acid content. PMID:1224794

Lück, E; Oeser, H; Remmert, K H; Sabel, J

1975-05-30

179

75 FR 78243 - Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review...  

Federal Register 2010, 2011, 2012, 2013, 2014

...EPA-HQ-OPP-2010-0650; FRL-8855-5] Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl...decisions for the pesticides propionic acid and salts, case no. 4078, urea sulfate, case...the table below--propionic acid and salts, case 4078, urea sulfate, case...

2010-12-15

180

40 CFR 180.325 - 2-(m-Chlorophenoxy) propionic acid; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false 2-(m-Chlorophenoxy) propionic acid; tolerances...Specific Tolerances § 180.325 2-(m-Chlorophenoxy) propionic acid; tolerances...negligible residues of the plant regulator 2-(m-chlorophenoxy) propionic acid from...

2010-07-01

181

Propionic-Acid-Terminated Silicon Nanoparticles: Synthesis and Optical Characterization  

E-print Network

Sato, and Mark T. Swihart*, Department of Chemical and Biological Engineering, UniVersity at Buffalo (SUNY), Buffalo, New York 14260-4200, and Graduate School of Material Science, UniVersity of Hyogo, 3 producing water-dispersible, propionic-acid-terminated particles. From transmission electron microscope (TEM

Swihart, Mark T.

182

Dialkylimidazolium ionic liquids hydrolyze cellulose under mild conditions.  

PubMed

The average molecular weight of cellulose derived from filter paper, poplar, and Avicel decreases by up to two orders of magnitude during typical mild dissolution protocols using ionic liquids (ILs). About an order of magnitude greater cellulose depolymerization rate during ionic liquid dissolution occurs in 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-ethyl-3-methylimidazolium chloride (EmimCl) compared to 1-ethyl-3-methylimidazolium acetate (EmimOAc), and, unintuitively, greater IL purity results in greater cellulose depolymerization. The following data support the mechanism of cellulose hydrolysis to be acid-catalyzed: (i) increase in number of reducing ends following cellulose dissolution in IL; (ii) addition of N-methylimidazolium base suppresses cellulose depolymerization during dissolution in IL; (iii) small amounts of glucose and traces of hydroxymethyl furfural are present following cellulose dissolution in IL. The acid is presumably synthesized via IL decomposition to generate a carbene and proton, consistent with hypothesis derived from molecular modeling. Titration experiments conducted here measure the amount of acid synthesized to be in the 4000 ppm range for high-purity BmimCl IL during mild processing conditions for cellulose dissolution. This data is relevant for understanding the extent of IL decomposition during biomass dissolution. PMID:22550059

Gazit, Oz M; Katz, Alexander

2012-08-01

183

Self-reinforced cellulose nanocomposites  

Microsoft Academic Search

A self-reinforced cellulosic material was produced exclusively from regenerated cellulose microcrystals. The level of reinforcement\\u000a was controlled by tailoring the crystallinity of cellulose by controlling the dissolution of microcrystalline cellulose (MCC)\\u000a before its regeneration process. After the cellulose regeneration a self-reinforced material was obtained in which cellulose\\u000a crystals reinforced amorphous cellulose. This structure was produced by dissolution of MCC in

Anthony Abbott; Alexander Bismarck

2010-01-01

184

Cost Effectiveness of Fluticasone Propionate Plus Salmeterol Versus Fluticasone Propionate Plus Montelukast in the Treatment of Persistent Asthma  

Microsoft Academic Search

Background: Asthma is a chronic disease, the two main components of which are inflammation and bronchoconstriction. Fluticasone propionate (FP) and salmeterol, a strategy that treats both main components of asthma, has been recently compared with FP plus montelukast in a randomised clinical trial. The present study reports economic evaluation of these two strategies. Objective: To determine the relative cost effectiveness

Richard D. OConnor; Harold Nelson; Rohit Borker; Amanda Emmett; Priti Jhingran; Kathleen Rickard; Paul Dorinsky

2004-01-01

185

Studies on cellulose acetate Polymethylmethacrylate and Polystyrene blend ultrafiltration Membranes;.  

E-print Network

??Membrane separation techniques are being used in various newlineindustries such as chemical pharmaceutical and metal finishing industries newlineThese techniques allow not only energy and cost… (more)

Vidya S

2014-01-01

186

Preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)

1998-01-01

187

Electrooxidation of tigogenin acetate  

Microsoft Academic Search

Electrooxidation of tigogenin acetate afforded two products: 3?-acetoxy-16?-hydroxy-23,24-dinor-5?-cholanoic acid lactone (2) and 20-epitigogenin acetate (3). The structure of the latter compound was confirmed by an X-ray analysis. The tentative mechanism of reaction is proposed.

Jacek W. Morzycki; Yliana López; Jolanta P?oszy?ska; Rosa Santillan; Leszek Siergiejczyk; Andrzej Sobkowiak

2007-01-01

188

Regenerating cellulose from ionic liquids for an accelerated enzymatic hydrolysis  

SciTech Connect

The efficient conversion of lignocellulosic materials into fuel ethanol has become a research priority in producing affordable and renewable energy. The pretreatment of lignocelluloses is known to be key to the fast enzymatic hydrolysis of cellulose. Recently, certain ionic liquids (ILs)were found capable of dissolving more than 10 wt% cellulose. Preliminary investigations [Dadi, A.P., Varanasi, S., Schall, C.A., 2006. Enhancement of cellulose saccharification kinetics using an ionic liquid pretreatment step. Biotechnol. Bioeng. 95, 904 910; Liu, L., Chen, H., 2006. Enzymatic hydrolysis of cellulose materials treated with ionic liquid [BMIM]Cl. Chin. Sci. Bull. 51, 2432 2436; Dadi, A.P., Schall, C.A., Varanasi, S., 2007. Mitigation of cellulose recalcitrance to enzymatic hydrolysis by ionic liquid pretreatment. Appl. Biochem. Biotechnol. 137 140, 407 421] suggest that celluloses regenerated from IL solutions are subject to faster saccharification than untreated substrates. These encouraging results offer the possibility of using ILs as alternative and nonvolatile solvents for cellulose pretreatment. However, these studies are limited to two chloride-based ILs: (a) 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), which is a corrosive, toxic and extremely hygroscopic solid (m.p. 70 C), and (b) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), which is viscous and has a reactive side-chain. Therefore, more in-depth research involving other ILs is much needed to explore this promising pretreatment route. For this reason, we studied a number of chloride- and acetate-based ILs for cellulose regeneration, including several ILs newly developed in our laboratory. This will enable us to select inexpensive, efficient and environmentally benign solvents for processing cellulosic biomass. Our data confirm that all regenerated celluloses are less crystalline (58 75% lower) and more accessible to cellulase (>2 times) than untreated substrates. As a result, regenerated Avicel cellulose, filter paper and cottonwere hydrolyzed 2 10 times faster than the respective untreated celluloses. A complete hydrolysis of Avicel cellulose could be achieved in 6 h given the Trichoderma reesei cellulase/substrate ratio (w/w) of 3:20 at 50 C. In addition,we observed that cellulase is more thermally stable (up to 60 C) in the presence of regenerated cellulose. Furthermore, our systematic studies suggest that the presence of various ILs during the hydrolysis induced different degrees of cellulase inactivation. Therefore, a thorough removal of IL residues after cellulose regeneration is highly recommended, and a systematic investigation on this subject is much needed.

Zhao, Hua [Savannah State University; Jones, Cecil L [Savannah State University; Baker, Gary A [ORNL; Xia, Shuqian [Tianjin University, Tianjin, China; Olubajo, Olarongbe [Savannah State University; Person, Vernecia [Savannah State University

2009-01-01

189

Rapid determination of cellulose.  

PubMed

The cellulose analysis results of four feedstocks and Avicel obtained by a one-step/two-step hydrolysis method were compared to the conventional cellulose assay according to Updegraff. Slightly lower cellulose levels were observed for Avicel (97%), corn stover (97%), poplar (96%), and Miscanthus (94%) but for pine the amounts were almost identical (101%). Despite these differences, the one-step/two-step method can be seen as a true alternative to the more labor-intensive Updegraff method. PMID:24909906

Bauer, Stefan; Ibáñez, Ana B

2014-11-01

190

Xyloglucan in cellulose modification  

Microsoft Academic Search

Xyloglucans are the principal polysaccharides coating and crosslinking cellulose microfibrills in the majority of land plants.\\u000a This review summarizes current knowledge of xyloglucan structures, solution properties, and the mechanism of interaction of\\u000a xyloglucans with cellulose. This knowledge base forms the platform for new biomimetic methods of cellulose surface modification\\u000a with applications within the fields of textile manufacture, papermaking, and materials

Qi Zhou; Mark W. Rutland; Tuula T. Teeri; Harry Brumer

2007-01-01

191

Measurement of Acetate Concentrations in Marine Pore Waters by Using an Enzymatic Approach †  

PubMed Central

Acetate concentrations in marine and freshwater matrices were measured by an enzymatic technique which coupled the synthesis of acetyl coenzyme A to AMP production. The resulting AMP was assayed by a sensitive and relatively rapid high-pressure liquid chromatography method, using an aqueous, isocratic mobile phase for elution. The method was insensitive to the presence of seawater salts and required no sample prepurification or distillation. Propionate caused a minor, but statistically insignificant, interference when equimolar with acetate; butyrate caused no interference, even at relatively high concentrations. Detection limits for acetate were approximately 100 nM with a precision of about 5%. Pore waters from two intertidal sediments contained approximately 1 to 12 ?M acetate; the concentrations were linearly but inversely correlated with porewater sulfate. PMID:16348598

King, Gary M.

1991-01-01

192

Surface esterification of cellulose nanofibers by a simple organocatalytic methodology.  

PubMed

Bacterial cellulose nanofibers were esterified with two short carboxylic acids by means of a simple and novel organic acid-catalyzed route. The methodology proposed relayed on the use of a non-toxic biobased ?-hydroxycarboxylic acid as catalyst, and proceeded under moderate reaction conditions in solventless medium. By varying the esterification interval, acetylated and propionized bacterial cellulose nanofibers with degree of substitution (DS) in the 0.02-0.45 range could be obtained. Esterified bacterial cellulose samples were characterized by means of Solid-State CP/MAS (13)C Nuclear Magnetic Resonance spectroscopy (CP/MAS (13)C NMR), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and chosen hydrophobicity test assays. TGA results showed that the esterified nanofibers had increased thermal stability, whereas XRD data evidenced that the organocatalytic esterification protocol did not alter their crystallinity. The analysis of the ensuing modified nanofibers by NMR, FTIR, XRD and TGA demonstrated that esterification occurred essentially at the surface of bacterial cellulose microfibrils, something highly desirable for changing their surface hydrophilicity while not affecting their ultrastructure. PMID:25263909

Avila Ramírez, Jhon Alejandro; Suriano, Camila Juan; Cerrutti, Patricia; Foresti, María Laura

2014-12-19

193

Regulation and Evolution of Malonate and Propionate Catabolism in Proteobacteria  

PubMed Central

Bacteria catabolize malonate via two pathways, encoded by the mdc and mat genes. In various bacteria, transcription of these genes is controlled by the GntR family transcription factors (TFs) MatR/MdcY and/or the LysR family transcription factor MdcR. Propionate is metabolized via the methylcitrate pathway, comprising enzymes encoded by the prp and acn genes. PrpR, the Fis family sigma 54-dependent transcription factor, is known to be a transcriptional activator of the prp genes. Here, we report a detailed comparative genomic analysis of malonate and propionate metabolism and its regulation in proteobacteria. We characterize genomic loci and gene regulation and identify binding motifs for four new TFs and also new regulon members, in particular, tripartite ATP-independent periplasmic (TRAP) transporters. We describe restructuring of the genomic loci and regulatory interactions during the evolution of proteobacteria. PMID:22505679

Suvorova, I. A.; Ravcheev, D. A.

2012-01-01

194

Acute psychosis in propionic acidemia: 2 case reports.  

PubMed

Propionic acidemia is an inborn deficiency of propionyl-coenzyme A (CoA) carboxylase activity, which leads to mitochondrial accumulation of propionyl-CoA and its by-products. Neurologic complications are frequent, but only a few cases presenting with psychiatric symptoms have been reported so far. We report 2 cases of children with chronic psychiatric symptoms who presented with an acute psychotic episode as teenagers. Both patients had hallucinations, panic and grossly disorganized behavior, for several weeks to several months. They had signs of moderate metabolic decompensation at the beginning of the episode, although the psychiatric symptoms lasted longer than the metabolic imbalance. We propose that these episodes were at least partially imputable to propionic acidemia. Such episodes require psychiatric examination and antipsychotic treatment, which may have to be adapted in case of cardiomyopathy or long QT syndrome. PMID:24334345

Dejean de la Bâtie, C; Barbier, V; Valayannopoulos, V; Touati, G; Maltret, A; Brassier, A; Arnoux, J B; Grévent, D; Chadefaux, B; Ottolenghi, C; Canouï, P; de Lonlay, P

2014-02-01

195

Microparticulate Based Topical Delivery System of Clobetasol Propionate  

Microsoft Academic Search

Psoriasis is a chronic, autoimmune skin disease affecting approximately 2% of the world's population. Clobetasol propionate\\u000a which is a superpotent topical corticosteroid is widely used for topical treatment of psoriasis. Conventional dosage forms\\u000a like creams and ointments are commonly prefered for the therapy. The purpose of this study was to develop a new topical delivery\\u000a system in order to provide

Ulya Bad?ll?; Tangül ?en; Nilüfer Tar?mc?

196

Propionic acid production by extractive fermentation. 1. Solvent considerations  

Microsoft Academic Search

Solvent selection for extractive fermentation for propionic acid was conducted with three systems: Alamine{reg_sign} 304-1 (trilaurylamine) in 2-octanol, 1-dodecanol, and Witcohol{reg_sign} 85 NF (oleyl alcohol). Among them, the solvent containing 2-octanol exhibited the highest partition coefficient in acid extraction, but it was also toxic to propionibacteria. The most solvent-resistant strain among five strains of the microorganism was selected. Solvent toxicity

Z. Gu; B. A. Glatz; C. E. Glatz

1998-01-01

197

Identification of a novel acetate-utilizing bacterium belonging to Synergistes group 4 in anaerobic digester sludge.  

PubMed

Major acetate-utilizing bacterial and archaeal populations in methanogenic anaerobic digester sludge were identified and quantified by radioisotope- and stable-isotope-based functional analyses, microautoradiography-fluorescence in situ hybridization (MAR-FISH) and stable-isotope probing of 16S rRNA (RNA-SIP) that can directly link 16S rRNA phylogeny with in situ metabolic function. First, MAR-FISH with (14)C-acetate indicated the significant utilization of acetate by only two major groups, unidentified bacterial cells and Methanosaeta-like filamentous archaeal cells, in the digester sludge. To identify the acetate-utilizing unidentified bacteria, RNA-SIP was conducted with (13)C(6)-glucose and (13)C(3)-propionate as sole carbon source, which were followed by phylogenetic analysis of 16S rRNA. We found that bacteria belonging to Synergistes group 4 were commonly detected in both 16S rRNA clone libraries derived from the sludge incubated with (13)C-glucose and (13)C-propionate. To confirm that this bacterial group can utilize acetate, specific FISH probe targeting for Synergistes group 4 was newly designed and applied to the sludge incubated with (14)C-acetate for MAR-FISH. The MAR-FISH result showed that bacteria belonging to Synergistes group 4 significantly took up acetate and their active population size was comparable to that of Methanosaeta in this sludge. In addition, as bacteria belonging to Synergistes group 4 had high K(m) for acetate and maximum utilization rate, they are more competitive for acetate over Methanosaeta at high acetate concentrations (2.5-10? mM). To our knowledge, it is the first time to report the acetate-utilizing activity of uncultured bacteria belonging to Synergistes group 4 and its competitive significance to acetoclastic methanogen, Methanosaeta. PMID:21562600

Ito, Tsukasa; Yoshiguchi, Kazumi; Ariesyady, Herto Dwi; Okabe, Satoshi

2011-12-01

198

Identification of a novel acetate-utilizing bacterium belonging to Synergistes group 4 in anaerobic digester sludge  

PubMed Central

Major acetate-utilizing bacterial and archaeal populations in methanogenic anaerobic digester sludge were identified and quantified by radioisotope- and stable-isotope-based functional analyses, microautoradiography-fluorescence in situ hybridization (MAR-FISH) and stable-isotope probing of 16S rRNA (RNA-SIP) that can directly link 16S rRNA phylogeny with in situ metabolic function. First, MAR-FISH with 14C-acetate indicated the significant utilization of acetate by only two major groups, unidentified bacterial cells and Methanosaeta-like filamentous archaeal cells, in the digester sludge. To identify the acetate-utilizing unidentified bacteria, RNA-SIP was conducted with 13C6-glucose and 13C3-propionate as sole carbon source, which were followed by phylogenetic analysis of 16S rRNA. We found that bacteria belonging to Synergistes group 4 were commonly detected in both 16S rRNA clone libraries derived from the sludge incubated with 13C-glucose and 13C-propionate. To confirm that this bacterial group can utilize acetate, specific FISH probe targeting for Synergistes group 4 was newly designed and applied to the sludge incubated with 14C-acetate for MAR-FISH. The MAR-FISH result showed that bacteria belonging to Synergistes group 4 significantly took up acetate and their active population size was comparable to that of Methanosaeta in this sludge. In addition, as bacteria belonging to Synergistes group 4 had high Km for acetate and maximum utilization rate, they are more competitive for acetate over Methanosaeta at high acetate concentrations (2.5–10?m). To our knowledge, it is the first time to report the acetate-utilizing activity of uncultured bacteria belonging to Synergistes group 4 and its competitive significance to acetoclastic methanogen, Methanosaeta. PMID:21562600

Ito, Tsukasa; Yoshiguchi, Kazumi; Ariesyady, Herto Dwi; Okabe, Satoshi

2011-01-01

199

Fractionation of wheat straw by atmospheric acetic acid process  

Microsoft Academic Search

Fractionation of wheat straw was investigated using an atmospheric acetic acid process. Under the typical conditions of 90% (v\\/v) aqueous AcOH, 4% H2SO4 (w\\/w, on straw), ratio of liquor to straw (L\\/S) 10 (v\\/w), pulping temperature 105°C, and pulping time 3h, wheat straw was fractionated to pulp (cellulose), lignin and monosaccharides mainly from hemicellulose with yields of approximately 50%, 15%

Xuejun Pan; Yoshihiro Sano

2005-01-01

200

Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.  

PubMed

X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration. PMID:24269347

Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

2014-01-01

201

Cellulose Degradation by Cellulose-Clearing and Non-Cellulose-Clearing Brown-Rot Fungi  

PubMed Central

Cellulose degradation by four cellulose-clearing brown-rot fungi in the Coniophoraceae—Coniophora prasinoides, C. puteana, Leucogyrophana arizonica, and L. olivascens—is compared with that of a non-cellulose-clearing brown-rot fungus, Poria placenta. The cellulose- and the non-cellulose-clearing brown-rot fungi apparently employ similar mechanisms to depolymerize cellulose; most likely a nonenzymatic mechanism is involved. PMID:16345675

Highley, Terry L.

1980-01-01

202

The Acetate Switch  

PubMed Central

To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the “acetate switch,” occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the “switch” (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl?P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl?P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl?P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl?P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to “flip the switch,” the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the “acetate switch” as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described. PMID:15755952

Wolfe, Alan J.

2005-01-01

203

Cellulose binding domain proteins  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc (Davis, CA); Doi, Roy (Davis, CA)

1998-01-01

204

Cellulose binding domain proteins  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

1998-11-17

205

Understanding of how Propionibacterium acidipropionici respond to propionic acid stress at the level of proteomics  

PubMed Central

Propionic acid (PA) is an important platform chemical in the food, agriculture, and pharmaceutical industries and is mainly biosynthesized by propionibacteria. Acid tolerance in PA-producing strains is crucial. In previous work, we investigated the acid tolerance mechanism of Propionibacterium acidipropionici at microenvironmental levels by analyzing physiological changes in the parental strain and three PA-tolerant mutants obtained by genome shuffling. However, the molecular mechanism of PA tolerance in P. acidipropionici remained unclear. Here, we performed a comparative proteomics study of P. acidipropionici CGMCC 1.2230 and the acid-tolerant mutant P. acidipropionici WSH1105; MALDI-TOF/MS identified 24 proteins that significantly differed between the parental and shuffled strains. The differentially expressed proteins were mainly categorized as key components of crucial biological processes and the acid stress response. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was used to confirm differential expression of nine key proteins. Overexpression of the secretory protein glyceraldehyde-3-phosphate dehydrogenase and ATP synthase subunit ? in Escherichia coli BL21 improved PA and acetic acid tolerance; overexpression of NADH dehydrogenase and methylmalonyl-CoA epimerase improved PA tolerance. These results provide new insights into the acid tolerance of P. acidipropionici and will facilitate the development of PA production through fermentation by propionibacteria. PMID:25377721

Guan, Ningzi; Shin, Hyun-dong; Chen, Rachel R.; Li, Jianghua; Liu, Long; Du, Guocheng; Chen, Jian

2014-01-01

206

Microbial production of propionic acid from propionibacteria: current state, challenges and perspectives.  

PubMed

Propionic acid (PA) is an important building block chemical and finds a variety of applications in organic synthesis, food, feeding stuffs, perfume, paint and pharmaceutical industries. Presently, PA is mainly produced by petrochemical route. With the continuous increase in oil prices, public concern about environmental pollution, and the consumers' desire for bio-based natural and green ingredients in foods and pharmaceuticals, PA production from propionibacteria has attracted considerable attention, and substantial progresses have been made on microbial PA production. However, production of PA by propionibacteria is facing challenges such as severe inhibition of end-products during cell growth and the formation of by-products (acetic acid and succinic acid). The integration of reverse metabolic engineering and systematic metabolic engineering provides an opportunity to significantly improve the acid tolerance of propionibacteria and reduce the formation of by-products, and makes it feasible to strengthen the commercial competition of biotechnological PA production from propionibacteria to be comparable to the petrochemical route. PMID:22299651

Liu, Long; Zhu, Yunfeng; Li, Jianghua; Wang, Miao; Lee, Pengsoon; Du, Guocheng; Chen, Jian

2012-12-01

207

Acetate transport across the intestinal epithelium of an herbivorous teleost. [Oreochromis mossambicus  

SciTech Connect

{sup 3}H-acetate transport across the upper intestine of the tilapia, Oreochromis mossabicus, using brush border and basolateral membrane vesicles, and intestinal sheets mounted in modified Ussing chambers was investigated. Brush border and basolateral vesicles demonstrated qualitatively similar anion antiport activity where, in the presence of a full profile of organic and inorganic anions, volatile fatty acids (VFA; acetate, propionate, butyrate) and bicarbonate showed reciprocal trans-stimulation and cis-inhibition of {sup 3}H-acetate influx, suggesting both membranes had the same VFA/bicarbonate exchange mechanism. Kinetic analysis of {sup 3}H-acetate influx into brush border and basolateral vesicles revealed different half-saturation constants (Km) as a function of external acetate concentrations (6.43 mM and 11.91 mM, respectively) and as a function of internal bicarbonate (5.89 mM and 0.41 mM, respectively). Intestinal sheets supported net absorptive fluxes when serosal acetate concentrations were held steady at 1.0 mM and mucosal acetate was varied from 1.60 to 10.0 mM. Unidirectional fluxes were significantly diminished by the addition of acetazolamide. This study postulates a transcellular transport pathway for VFA whereby qualitatively similar antiporters in series lead to a downhill flow of luminal acetate to the blood, which is driven by intracellular carbonic anhydrase and a transmural VFA concentration gradient.

Titus, E.; Ahearn, G.A. (Univ. of Hawaii, Honolulu (United States))

1990-02-26

208

Thermoanaerobacteriaceae oxidize acetate in methanogenic rice field soil at 50°C.  

PubMed

Rice field soils contain a thermophilic microbial community. Incubation of Italian rice field soil at 50°C resulted in transient accumulation of acetate, but the microorganisms responsible for methane production from acetate are unknown. Without addition of exogenous acetate, the ?(13)C of CH(4) and CO(2) indicated that CH(4) was exclusively produced by hydrogenotrophic methanogenesis. When exogenous acetate was added, acetoclastic methanogenesis apparently also operated. Nevertheless, addition of [2-(13)C]acetate (99% (13)C) resulted in the production not only of (13)C-labelled CH(4) but also of CO(2), which contained up to 27% (13)C, demonstrating that the methyl group of acetate was also oxidized. Part of the (13)C-labelled acetate was also converted to propionate which contained up to 14% (13)C. The microorganisms capable of assimilating acetate at 50°C were targeted by stable isotope probing (SIP) of ribosomal RNA and rRNA genes using [U-(13)C] acetate. Using quantitative PCR, (13)C-labelled bacterial ribosomal RNA and DNA was detected after 21 and 32 days of incubation with [U-(13)C]acetate respectively. In the heavy fractions of the (13)C treatment, terminal restriction fragments (T-RFs) of 140, 120 and 171 bp length predominated. Cloning and sequencing of 16S rRNA showed that these T-RFs were affiliated with the bacterial genera Thermacetogenium and Symbiobacterium and with members of the Thermoanaerobacteriaceae. Similar experiments targeting archaeal RNA and DNA showed that Methanocellales were the dominant methanogens being consistent with the operation of syntrophic bacterial acetate oxidation coupled to hydrogenotrophic methanogenesis. After 17 days, however, Methanosarcinacea increasingly contributed to the synthesis of rRNA from [U-(13)C]acetate indicating that acetoclastic methanogens were also active in methanogenic Italian rice field soil under thermal conditions. PMID:21966924

Liu, Fanghua; Conrad, Ralf

2010-08-01

209

Pyrolytic sugars from cellulosic biomass  

NASA Astrophysics Data System (ADS)

Sugars are the feedstocks for many promising advanced cellulosic biofuels. Traditional sugars derived from starch and sugar crops are limited in their availability. In principle, more plentiful supply of sugars can be obtained from depolymerization of cellulose, the most abundant form of biomass in the world. Breaking the glycosidic bonds between the pyranose rings in the cellulose chain to liberate glucose has usually been pursued by enzymatic hydrolysis although a purely thermal depolymerization route to sugars is also possible. Fast pyrolysis of pure cellulose yields primarily levoglucosan, an anhydrosugar that can be hydrolyzed to glucose. However, naturally occurring alkali and alkaline earth metals (AAEM) in biomass are strongly catalytic toward ring-breaking reactions that favor formation of light oxygenates over anhydrosugars. Removing the AAEM by washing was shown to be effective in increasing the yield of anhydrosugars; but this process involves removal of large amount of water from biomass that renders it energy intensive and thereby impractical. In this work passivation of the AAEM (making them less active or inactive) using mineral acid infusion was explored that will increase the yield of anhydrosugars from fast pyrolysis of biomass. Mineral acid infusion was tried by previous researchers, but the possibility of chemical reactions between infused acid and AAEM in the biomass appears to have been overlooked, possibly because metal cations might be expected to already be substantially complexed to chlorine or other strong anions that are found in biomass. Likewise, it appears that previous researchers assumed that as long as AAEM cations were in the biomass, they would be catalytically active regardless of the nature of their complexion with anions. On the contrary, we hypothesized that AAEM can be converted to inactive or less active salts using mineral acids. Various biomass feedstocks were infused with mineral (hydrochloric, nitric, sulfuric and phosphoric acids) and organic acids (formic and acetic acids) followed by analytical pyrolysis on a micropyrolyzer/GC/MS/FID system. It was found that sulfuric and phosphoric acids are very effective in passivating the AAEM thereby increasing the yield of anhydrosugars. An excellent correlation was discovered between the amount of acid required to obtain the maximum yield of anhydrosugars and the amount of AAEM contained in the biomass feedstock. In the micro-scale studies, up to 56% of the cellulose contained in the biomass was converted into anhydrosugars which is close to the 57% conversion obtained from pure cellulose pyrolysis. It is known that LG polymerization and subsequent charring occur at temperatures above 275°C depending on the vapor pressure of LG in the gas stream. A study of pyrolysis of acid-infused biomass feedstocks at various temperatures revealed that LG recovery is best at lower temperatures than the conventional pyrolysis temperature range of 450-500°C. Pyrolysis of acid-infused biomass failed in a continuous fluidized bed reactor due to clogging of the bed. The feedstock formed vitreous material along with the fluidizing sand that was formed from poor pyrolysis of lignin. However, more investigation of this phenomenon is a subject for future work. Pyrolysis experiments on an auger type reactor were successful in producing bio-oils with unprecedented amounts of sugars. Though there was increase in charring when compared to the control feedstock, pyrolysis of red oak infused with 0.4 wt% of sulfuric acid produced bio-oil with 18wt% of sugars. One of the four fractions of bio-oil collected contained most of the sugars, which shows significant potential for separating the sugars from bio-oil using simple means. This work points towards a new pathway for making advanced biofuels viz. upgrading pyrolytic sugars from biomass that could compete with enzymatic sugars from biomass.

Kuzhiyil, Najeeb

210

Separation and Characterization of Cellulose from Wheat Straw  

Microsoft Academic Search

Highly purified cellulose was separated from wheat straw by sequential treatments of dewaxed straw with 0.5?M aqueous KOH at 35°C for 2.5 h under ultrasonic irradiation time of 0 to 35 min, 2% H2O2–0.2% TAED at pH 11.8 for 12 h at 48°C, and with 80% acetic acid–70% nitric acid (10\\/1, v\\/v) at 120°C for 15 min. The yield of crude cellulose preparations obtained

RunCang Sun; Jeremy Tomkinson

2005-01-01

211

[Propionic acid fermentation by Propionibacterium freudenreichii CCTCC M207015 with a fibrous-bed bioreactor].  

PubMed

The production of propionic acid by Propionibacterium freudenreichii CCTCC M207015 was investigated in a Fibrous-bed bioreactor (FBB). The FBB was constructed by packing spiral cotton fibrous and immobilized into a bioreactor. By applying this bioreactor to propionic acid fermentation, the propionic acid yield had a significant improvement and reached 20.41 g/L, compared with the cell-free culture of 14.58 g/L (40 g/L of glucose). At the same time, the glucose exhausting time decreased from 120 h to 60 h. Batch fermentations at various glucose concentrations were carried out with FBB. Based on the analysis of the time course of production, fed-batch fermentation was also applied to produce propionic acid with FBB, the maximal propionic acid yield reached 45.91 g/L, and the proportion of propionic acid to total acids was about 72.31%. PMID:18807995

Feng, Xiaohai; Wu, Bo; Shen, Xiaobo; Xu, Hong

2008-06-01

212

Polymorphism of cellulose I family: reinvestigation of cellulose IVI.  

PubMed

Polymorphs of cellulose I, III(I), and IV(I) have been investigated by X-ray diffraction, FT-IR, and solid-state (13)C NMR spectroscopy. Highly crystalline cellulose III(I) samples were prepared by treating cellulose samples in supercritical ammonia at 140 degrees C for 1 h, and conventional cellulose III(I) samples were prepared by liquid ammonia treatment. The cellulose IV(I) sample of highest crystallinity was that prepared from Cladophora cellulose III(I) in supercritical ammonia, followed by the sample treated in glycerol at 260 degrees C for 0.5 h, whereas the lowest crystallinity was observed in ramie cellulose prepared by conventional liquid ammonia treatment followed by glycerol annealing. In general, the perfection of cellulose IV(I) depends on the crystallinity of the original material: either of the starting cellulose I or of the cellulose III(I) after ammonia treatment. The product thus obtained was analogous to cellulose I(beta), which is what it should be called rather than cellulose IV(I). If the existence of the polymorph cellulose IV(I) is not accepted, the observations on which it has been based may be explained by the fact that the structure termed cellulose IV(I) is cellulose I(beta) which contains lateral disorder. PMID:15244455

Wada, Masahisa; Heux, Laurent; Sugiyama, Junji

2004-01-01

213

Agglomerate behaviour of fluticasone propionate within dry powder inhaler formulations.  

PubMed

Due to their small size, the respirable drug particles tend to form agglomerates which prevent flowing and aerosolisation. A carrier is used to be mixed with drug in one hand to facilitate the powder flow during manufacturing, in other hand to help the fluidisation upon patient inhalation. Depending on drug concentration, drug agglomerates can be formed in the mixture. The aim of this work was to study the agglomeration behaviour of fluticasone propionate (FP) within interactive mixtures for inhalation. The agglomerate phenomenon of fluticasone propionate after mixing with different fractions of lactose without fine particles of lactose (smaller than 32 ?m) was demonstrated by the optical microscopy observation. A technique measuring the FP size in the mixture was developed, based on laser diffraction method. The FP agglomerate sizes were found to be in a linear correlation with the pore size of the carrier powder bed (R(2)=0.9382). The latter depends on the particle size distribution of carrier. This founding can explain the role of carrier size in de-agglomeration of drug particles in the mixture. Furthermore, it gives more structural information of interactive mixture for inhalation that can be used in the investigation of aerosolisation mechanism of powder. According to the manufacturing history, different batches of FP show different agglomeration intensities which can be detected by Spraytec, a new laser diffraction method for measuring aerodynamic size. After mixing with a carrier, Lactohale LH200, the most cohesive batch of FP, generates a lower fine particle fraction. It can be explained by the fact that agglomerates of fluticasone propionate with very large size was detected in the mixtures. By using silica-gel beads as ball-milling agent during the mixing process, the FP agglomerate size decreases accordingly to the quantity of mixing aid. The homogeneity and the aerodynamic performance of the mixtures are improved. The mixing aid based on ball-milling effect could be used to ameliorate the quality of inhalation mixture of cohesive drug, such as fluticasone propionate. However, there is a threshold where an optimal amount of mixing aids should be used. Not only the drug des-aggregation reaches its peak but the increase in drug-carrier adhesion due to high energy input should balance the de-agglomeration capacity of mixing process. This approach provides a potential alternative in DPI formulation processing. PMID:22198291

Le, V N P; Robins, E; Flament, M P

2012-04-01

214

Development of indole-3-propionic acid (OXIGON) for Alzheimer's disease.  

PubMed

The accumulation of amyloid-beta and concomitant oxidative stress are major pathogenic events in Alzheimer's disease. Indole-3-propionic acid (IPA, OXIGON) is a potent anti-oxidant devoid of pro-oxidant activity. IPA has been demonstrated to be an inhibitor of beta-amyloid fibril formation and to be a potent neuroprotectant against a variety of oxidotoxins. This review will summarize the known properties of IPA and outline the rationale behind its selection as a potential disease-modifying therapy for Alzheimer's disease. PMID:12212784

Bendheim, Paul E; Poeggeler, Burkhard; Neria, Eyal; Ziv, Vivi; Pappolla, Miguel A; Chain, Daniel G

2002-01-01

215

Methane from acetate.  

PubMed Central

The general features are known for the pathway by which most methane is produced in nature. All acetate-utilizing methanogenic microorganisms contain CODH which catalyzes the cleavage of acetyl-CoA; however, the pathway differs from all other acetate-utilizing anaerobes in that the methyl group is reduced to methane with electrons derived from oxidation of the carbonyl group of acetyl-CoA to CO2. The current understanding of the methanogenic fermentation of acetate provides impressions of nature's novel solutions to problems of methyl transfer, electron transport, and energy conservation. The pathway is now at a level of understanding that will permit productive investigations of these and other interesting questions in the near future. PMID:1512186

Ferry, J G

1992-01-01

216

Interactions of ionic liquids with polysaccharides 9. Hydroxyalkylation of cellulose without additional inorganic bases  

Microsoft Academic Search

Water-soluble hydroxyalkyl cellulose with a molar degree of substitution of up to 2.79 was prepared under completely homogeneous\\u000a reaction conditions in various ionic liquids without addition of inorganic bases. In acetate containing solvents the IL acts\\u000a as a catalyst. The substitution patterns of the cellulose ethers were analyzed by 13C NMR spectroscopy, 1H NMR spectroscopy after peracetylation and GLC\\/MS after

Sarah Köhler; Tim Liebert; Thomas Heinze; Antje Vollmer; Petra Mischnick; Eugen Möllmann; Winfried Becker

2010-01-01

217

NMR study of mesomorphic solutions of cellulose derivatives  

SciTech Connect

Highly concentrated solutions of hydroxypropylcellulose and cellulose acetate give mesomorphic phases in a precise range of temperatures and concentrations. The existence of an orientational anisotropy in such solutions induces typical parameters of the high-resolution NMR spectra (chemical shift, splitting) that are similar to those of liquid crystal spectra. In the present work, the high-resolution NMR spectra of nuclei belonging to the solute molecules (D/sub 2/O and trifluoroacetic acid) were recorded as a function of various physical parameters such as temperature, concentration, and temporal change of the solutions. The specific variation of the orientational degree of order for each mesophase is described. In the case of the cellulose acetate/trifluoroacetic acid solution, an order parameter is calculated and a model for the orientational organization of the solution is described. 34 references, 10 figures, 1 table.

Dayan, S.; Fried, F.; Gilli, J.M.; Sixou, P.

1983-01-01

218

Genomics of cellulosic biofuels.  

PubMed

The development of alternatives to fossil fuels as an energy source is an urgent global priority. Cellulosic biomass has the potential to contribute to meeting the demand for liquid fuel, but land-use requirements and process inefficiencies represent hurdles for large-scale deployment of biomass-to-biofuel technologies. Genomic information gathered from across the biosphere, including potential energy crops and microorganisms able to break down biomass, will be vital for improving the prospects of significant cellulosic biofuel production. PMID:18704079

Rubin, Edward M

2008-08-14

219

Method of saccharifying cellulose  

DOEpatents

A method is disclosed of saccharifying cellulose by incubation with the cellulase of Clostridium thermocellum in a broth containing an efficacious amount of thiol reducing agent. Other incubation parameters which may be advantageously controlled to stimulate saccharification include the concentration of alkaline earth salts, pH, temperature, and duration. By the method of the invention, even native crystalline cellulose such as that found in cotton may be completely saccharified.

Johnson, E.A.; Demain, A.L.; Madia, A.

1983-05-13

220

Method of saccharifying cellulose  

DOEpatents

A method of saccharifying cellulose by incubation with the cellulase of Clostridium thermocellum in a broth containing an efficacious amount of a reducing agent. Other incubation parameters which may be advantageously controlled to stimulate saccharification include the concentration of alkaline earth salts, pH, temperature, and duration. By the method of the invention, even native crystalline cellulose such as that found in cotton may be completely saccharified.

Johnson, Eric A. (Brookline, MA); Demain, Arnold L. (Wellesley, MA); Madia, Ashwin (Decatur, IL)

1985-09-10

221

Surface only modification of bacterial cellulose nanofibres with organic acids  

Microsoft Academic Search

Bacterial cellulose (BC) nanofibres were modified only on their surface using an esterification reaction with acetic acid,\\u000a hexanoic acid or dodecanoic acid. This reaction rendered the extremely hydrophilic surfaces of BC nanofibres hydrophobic.\\u000a The hydrophobicity of BC increased with increasing carbon chain length of the organic acids used for the esterification reaction.\\u000a Streaming (zeta-) potential measurements showed a slight shift

Koon-Yang Lee; Franck Quero; Jonny J. Blaker; Callum A. S. Hill; Stephen J. Eichhorn; Alexander Bismarck

2011-01-01

222

Measures of de novo synthesis of milk components from propionate in lactating goats  

SciTech Connect

Possible direct contributions of propionate to de novo synthesis of milk components by the mammary gland of lactating goats fed a concentrate-roughage diet have been studied in vivo by primed constant infusion of (1-carbon-14)propionate into the right mammary artery. Specific radioactivities of milk galactose, fatty acids, and protein were higher in the infused than in the uninfused half of the mammary gland, suggesting de novo synthesis of these compounds in the udder. Specific radioactivities of milk glucose in both udder halves were identical, ruling out any possibility of mammary gland-derived glucose from propionate of blood plasma under the experimental conditions. Of milk galactose, .8% was derived from propionate of blood plasma, and of milk glucose, 98% was derived from glucose of blood plasma. After intraruminal infusion of unlabeled propionic acid at 11 g/h, concentration of propionate in blood plasma was doubled, its contribution to milk galactose was increased to 1.5%, and proportions of milk odd-numbered fatty acids were increased. Propionate was incorporated largely into milk odd-numbered fatty acids. The authors conclude that small amounts of propionate can be incorporated into principal components of milk in the mammary gland of lactating goats.

Emmanuel, B.; Kennelly, J.J.

1985-02-01

223

Hepatic and portal drained viscera response to intramesenteric infusion of propionate  

E-print Network

Hepatic and portal drained viscera response to intramesenteric infusion of propionate in lactating physiological infusion of sodium proprionate, in the mesenteric vein, on liver and portal drained viscera (PDV yield and composition was observed during the infusion of propionate. It resulted in an increase (P

Boyer, Edmond

224

Salmeterol and Fluticasone Propionate and Survival in Chronic Obstructive Pulmonary Disease  

Microsoft Academic Search

We conducted a randomized, double-blind trial comparing salmeterol at a dose of 50 ?g plus fluticasone propionate at a dose of 500 ?g twice daily (combination regi- men), administered with a single inhaler, with placebo, salmeterol alone, or fluticasone propionate alone for a period of 3 years. The primary outcome was death from any cause for the comparison between the

Peter M. A. Calverley; Julie A. Anderson; Bartolome Celli; Gary T. Ferguson; Christine Jenkins; Paul W. Jones; Julie C. Yates; Jørgen Vestbo

2007-01-01

225

Adrenal suppression with chronic dosing of fluticasone propionate compared with budesonide in adult asthmatic patients  

Microsoft Academic Search

BACKGROUND: In a previous single dosing comparison between fluticasone propionate and budesonide differences in cortisol levels measured at 08.00 hours were observed at doses in excess of 1000 micrograms. The aim of this study was to compare the adrenal suppression caused by chronic twice daily dosing with inhaled fluticasone propionate (FP) and budesonide (B) given on a microgram equivalent basis

D. J. Clark; B. J. Lipworth

1997-01-01

226

Separation of hemicellulose and cellulose from wood pulp by means of ionic liquid/cosolvent systems.  

PubMed

Pulp of high cellulose content, also known as dissolving pulp, is needed for many purposes, including the production of cellulosic fibers and films. Paper-grade pulp, which is rich in hemicellulose, could be a cheap source but must be refined. Hitherto, hemicellulose extraction procedures suffered from a loss of cellulose and the non-recoverability of unaltered hemicelluloses. Herein, an environmentally benign fractionation concept is presented, using mixtures of a cosolvent (water, ethanol, or acetone) and the cellulose dissolving ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIM OAc). This cosolvent addition was monitored using Kamlet-Taft parameters, and appropriate stirring conditions (3 h at 60 °C) were maintained. This allowed the fractionation of a paper-grade kraft pulp into a separated cellulose and a regenerated hemicellulose fraction. Both of these exhibited high levels of purity, without any yield losses or depolymerization. Thus, this process represents an ecologically and economically efficient alternative in producing dissolving pulp of highest purity. PMID:23651266

Froschauer, Carmen; Hummel, Michael; Iakovlev, Mikhail; Roselli, Annariikka; Schottenberger, Herwig; Sixta, Herbert

2013-06-10

227

Preparation and characterization of regenerated cellulose from ionic liquid using different methods.  

PubMed

In this study, regenerated cellulose was prepared from ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim]Ac) solution using anti-solvent compressed CO2 of different pressures. And other anti-solvents like water, ethanol and acetonitrile were also employed to regenerate cellulose to provide comparisons. The two-dimensional nuclear magnetic resonance (2D NMR), namely heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond coherence (HMBC), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) indicated that carboxylate zwitterions [Bmim(+)-COO(-)] formed through the chemical reactions between CO2 and [Bmim]Ac. Besides, FTIR, wide-angle X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to provided structure characterization of native and regenerated cellulose using different anti-solvents. The results show that the crystallinity of cellulose decreases during the dissolution and regeneration process. And a crystal transformation of cellulose I to cellulose II was verified. The stability of the regenerated cellulose is lower than that of native cellulose. A higher compressed CO2 pressure results in a smoother surface, a thicker shape and a more homogeneous texture of regenerated cellulose. PMID:25498614

Liu, Zhenghui; Sun, Xiaofu; Hao, Mingyang; Huang, Chengyi; Xue, Zhimin; Mu, Tiancheng

2015-03-01

228

Cellulose Derivatives for Water Repellent Properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

Synthesis and structural characterizations of nitro-benzyl cellulose, amino-benzyl cellulose and pentafluoro –benzyl cellulose were carried out. Cellulose derivatives were synthesized by etherification process in lithium chloride/N,N-dimethylacetamide homogeneous solution. Nitrobenzylation was effec...

229

Syntrophic oxidation of propionate in rice field soil at 15 and 30°C under methanogenic conditions.  

PubMed

Propionate is one of the major intermediary products in the anaerobic decomposition of organic matter in wetlands and paddy fields. Under methanogenic conditions, propionate is decomposed through syntrophic interaction between proton-reducing and propionate-oxidizing bacteria and H(2)-consuming methanogens. Temperature is an important environmental regulator; yet its effect on syntrophic propionate oxidation has been poorly understood. In the present study, we investigated the syntrophic oxidation of propionate in a rice field soil at 15°C and 30°C. [U-(13)C]propionate (99 atom%) was applied to anoxic soil slurries, and the bacteria and archaea assimilating (13)C were traced by DNA-based stable isotope probing. Syntrophobacter spp., Pelotomaculum spp., and Smithella spp. were found significantly incorporating (13)C into their nucleic acids after [(13)C]propionate incubation at 30°C. The activity of Smithella spp. increased in the later stage, and concurrently that of Syntrophomonas spp. increased. Aceticlastic Methanosaetaceae and hydrogenotrophic Methanomicrobiales and Methanocellales acted as methanogenic partners at 30°C. Syntrophic oxidation of propionate also occurred actively at 15°C. Syntrophobacter spp. were significantly labeled with (13)C, whereas Pelotomaculum spp. were less active at this temperature. In addition, Methanomicrobiales, Methanocellales, and Methanosarcinaceae dominated the methanogenic community, while Methanosaetaceae decreased. Collectively, temperature markedly influenced the activity and community structure of syntrophic guilds degrading propionate in the rice field soil. Interestingly, Geobacter spp. and some other anaerobic organisms like Rhodocyclaceae, Acidobacteria, Actinobacteria, and Thermomicrobia probably also assimilated propionate-derived (13)C. The mechanisms for the involvement of these organisms remain unclear. PMID:22582054

Gan, Yanlu; Qiu, Qiongfen; Liu, Pengfei; Rui, Junpeng; Lu, Yahai

2012-07-01

230

Syntrophic Oxidation of Propionate in Rice Field Soil at 15 and 30°C under Methanogenic Conditions  

PubMed Central

Propionate is one of the major intermediary products in the anaerobic decomposition of organic matter in wetlands and paddy fields. Under methanogenic conditions, propionate is decomposed through syntrophic interaction between proton-reducing and propionate-oxidizing bacteria and H2-consuming methanogens. Temperature is an important environmental regulator; yet its effect on syntrophic propionate oxidation has been poorly understood. In the present study, we investigated the syntrophic oxidation of propionate in a rice field soil at 15°C and 30°C. [U-13C]propionate (99 atom%) was applied to anoxic soil slurries, and the bacteria and archaea assimilating 13C were traced by DNA-based stable isotope probing. Syntrophobacter spp., Pelotomaculum spp., and Smithella spp. were found significantly incorporating 13C into their nucleic acids after [13C]propionate incubation at 30°C. The activity of Smithella spp. increased in the later stage, and concurrently that of Syntrophomonas spp. increased. Aceticlastic Methanosaetaceae and hydrogenotrophic Methanomicrobiales and Methanocellales acted as methanogenic partners at 30°C. Syntrophic oxidation of propionate also occurred actively at 15°C. Syntrophobacter spp. were significantly labeled with 13C, whereas Pelotomaculum spp. were less active at this temperature. In addition, Methanomicrobiales, Methanocellales, and Methanosarcinaceae dominated the methanogenic community, while Methanosaetaceae decreased. Collectively, temperature markedly influenced the activity and community structure of syntrophic guilds degrading propionate in the rice field soil. Interestingly, Geobacter spp. and some other anaerobic organisms like Rhodocyclaceae, Acidobacteria, Actinobacteria, and Thermomicrobia probably also assimilated propionate-derived 13C. The mechanisms for the involvement of these organisms remain unclear. PMID:22582054

Gan, Yanlu; Qiu, Qiongfen; Liu, Pengfei; Rui, Junpeng

2012-01-01

231

Cellulose in Cyanobacteria. Origin of Vascular Plant Cellulose Synthase?  

E-print Network

Cellulose in Cyanobacteria. Origin of Vascular Plant Cellulose Synthase? David R. Nobles, Dwight K of Texas, Austin, Texas 78712 Although cellulose biosynthesis among the cyanobacteria has been suggested three of the five sections of cyanobacteria. Sequence analysis of the genomes of four cyanobacteria

Brown Jr., R. Malcolm

232

Propionic acid production by extractive fermentation. 1. Solvent considerations  

SciTech Connect

Solvent selection for extractive fermentation for propionic acid was conducted with three systems: Alamine{reg_sign} 304-1 (trilaurylamine) in 2-octanol, 1-dodecanol, and Witcohol{reg_sign} 85 NF (oleyl alcohol). Among them, the solvent containing 2-octanol exhibited the highest partition coefficient in acid extraction, but it was also toxic to propionibacteria. The most solvent-resistant strain among five strains of the microorganism was selected. Solvent toxicity was eliminated via two strategies: entrapment of dissolved toxic solvent in the culture growth medium with vegetable oils such as corn, olive, or soybean oils; or replacement of the toxic 2-octanol with nontoxic Witcohol 85 NF. The complete recovery of acids from the Alamine 304-1/Witcohol 85 NF was also realized with vacuum distillation.

Gu, Z.; Glatz, B.A.; Glatz, C.E. [Iowa State Univ., Ames, IA (United States)] [Iowa State Univ., Ames, IA (United States)

1998-02-20

233

Propionic acid production by extractive fermentation. I. Solvent considerations.  

PubMed

Solvent selection for extractive fermentation for propionic acid was conducted with three systems: Alamine 304-1 (trilaurylamine) in 2-octanol, 1-dodecanol, and Witcohol 85 NF (oleyl alcohol). Among them, the solvent containing 2-octanol exhibited the highest partition coefficient in acid extraction, but it was also toxic to propionibacteria. The most solvent-resistant strain among five strains of the microorganism was selected. Solvent toxicity was eliminated via two strategies: entrapment of dissolved toxic solvent in the culture growth medium with vegetable oils such as corn, olive, or soybean oils; or replacement of the toxic 2-octanol with nontoxic Witcohol 85 NF. The complete recovery of acids from the Alamine 304-1/Witcohol 85 NF was also realized with vacuum distillation. PMID:10099222

Gu, Z; Glatz, B A; Glatz, C E

1998-02-20

234

The cellulose resource matrix.  

PubMed

The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the feedstock and the performance in the end-application. The cellulose resource matrix should become a practical tool for stakeholders to make choices regarding raw materials, process or market. Although there is a vast amount of scientific and economic information available on cellulose and lignocellulosic resources, the accessibility for the interested layman or entrepreneur is very difficult and the relevance of the numerous details in the larger context is limited. Translation of science to practical accessible information with modern data management and data integration tools is a challenge. Therefore, a detailed matrix structure was composed in which the different elements or entries of the matrix were identified and a tentative rough set up was made. The inventory includes current commodities and new cellulose containing and raw materials as well as exotic sources and specialties. Important chemical and physical properties of the different raw materials were identified for the use in processes and products. When available, the market data such as price and availability were recorded. Established and innovative cellulose extraction and refining processes were reviewed. The demands on the raw material for suitable processing were collected. Processing parameters known to affect the cellulose properties were listed. Current and expected emerging markets were surveyed as well as their different demands on cellulose raw materials and processes. The setting up of the cellulose matrix as a practical tool requires two steps. Firstly, the reduction of the needed data by clustering of the characteristics of raw materials, processes and markets and secondly, the building of a database that can provide the answers to the questions from stakeholders with an indicative character. This paper describes the steps taken to achieve the defined clusters of most relevant and characteristic properties. These data can be expanded where required. More detailed specification can be obtained from the background literature and handbooks. Where gaps of information are ident

Keijsers, Edwin R P; Y?lmaz, Gülden; van Dam, Jan E G

2013-03-01

235

Size Effects of Nanocrystalline Cellulose  

Microsoft Academic Search

Natural cellulose with the crystal form of cellulose I, when treated with condensed lye (e.g. 18%NaOH), can change into new crystal form of cellulose II. But the nano-crystalline cellulose (NCC) can do it when only treated with dilute lye (e.g. 1%NaOH) at room temperature and even can dissolve into slightly concentrated lye (e.g. 4%NaOH).

Guo Kang LI; Xiao Fang LI; Yong JIANG; Mei Zhen ZENG; En Yong DING

2003-01-01

236

NANOFIBRILLAR CARBON FROM NATIVE CELLULOSE  

Microsoft Academic Search

Use of pyrolytic carbon from cellulose has been limited in practice to activated adsorbent carbon, but cellulose-derived carbon retaining the nanoscale microfibrillar morphology offers rich possibilities as an advanced material. Here we developed novel methods to prepare such materials by an improved drying of wet cellulose prior to pyrolysis. This procedure is an adaptation from electron microscopy techniques, i.e. rapid

O. Ishida; Y. Kim; S. Kuga; Y. Nishiyama

2002-01-01

237

Microfibrillar carbon from native cellulose  

Microsoft Academic Search

Use of pyrolytic carbon from cellulose has been limited in practice to activated adsorbent carbon, but cellulose-derived carbon retaining the nanoscale microfibrillar morphology offers rich possibilities as an advanced material. Here we developed novel methods to prepare such materials by an improved drying of wet cellulose prior to pyrolysis. This procedure is an adaptation from electron microscopy techniques, i.e. rapid

O. Ishida; D.-Y. Kim; S. Kuga; Y. Nishiyama

2004-01-01

238

Effect of nickelous and other metal ions on the inhibition of rumen bacterial metabolism by 3-(3'-isocyanocyclopent-2-enylidene)propionic acid and related isocyanides. [Phleum pratense  

SciTech Connect

3-(3'-isocyanocyclopent-2-enylidene) propionic acid at a concentration of 2 to 5 ..mu..g ml/sup -1/ inhibited cellulose digestion by a mixed culture of rumen microorganisms and in other experiments inhibited the degradation of timothy had (Phleum pratense) in a digestibility test. At isocyanide concentrations of 12 ..mu..g ml/sup -1/ the fermentation activity of rumen fluid, measured by its dehydrogenase activity, was inhibited but not abolished. All of these isocyanide effects were reversed by the incorporation of nickelous ion into the solutions of the systems under study. The activity of 1 mol of isocyanide is reversed by about 1 mol of Ni/sup 2 +/ and, in the case of the cellulose digestion test, by about 1 mol of Co/sup 2 +/. Of some 15 other ions tested only Pd/sup 2 +/ and possibly chromium reversed the effect of the isocyanide.

Brewer, D.; Calder, F.W.; Jones, G.A.; Tanguay, D.; Taylor, A.

1986-01-01

239

Binding behavior of amino acid conjugates of indole-3-acetic acid to immobilized human serum albumin.  

PubMed

The affinity of indole-3-acetic acid (IAA), indole-3-propionic acid, indole-3-butyric acid and 24 of their amino acid conjugates to immobilized human serum albumin, as expressed by the retention factor k (determined by HPLC), was dependent on (1) lipophilicity, (2) chirality and (3) functional groups in the amino acid moiety; in some cases conformation plays an additional role. Two lipophilicity-related parameters afforded quantitative correlations with k: retention on a C18 reversed-phase column (experimental approach) and the distance between the hydrophilic and hydrophobic poles of the molecules (in silico approach). Most compounds examined are possible metabolic precursors of IAA, an experimental tumor therapeutic. PMID:17459401

Tomasi?, Ana; Bertosa, Branimir; Tomi?, Sanja; Soski?, Milan; Magnus, Volker

2007-06-22

240

Sequential changes in propionate metabolism during the development of cobalt/vitamin B12 deficiency in sheep.  

PubMed

The changes in propionate metabolism that accompany cobalt deficiency in sheep are described. Two groups of sheep, fed either a cobalt sufficient or deficient diet, were given an iv propionate load at intervals during a 14 w experiment. There was a tendency towards increased propionate half-life as the animals became cobalt deficient. However, significant changes in the area under the plasma methylmalonic acid-time curve occurred very early, indicating significant impairment of propionate metabolism. Despite this, the area under the plasma glucose-time curve was unaffected by cobalt deficiency, suggesting that the impairment of propionate metabolism, although significant, is not extensive. PMID:1713046

Kennedy, D G; O'Harte, F P; Blanchflower, W J; Rice, D A

1991-03-01

241

Effect of different concentrations of acetic, citric, and propionic acid dipping solutions on bacterial contamination of raw chicken skin  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bacterial contamination of raw, processed poultry may include spoilage bacteria and foodborne pathogens. We evaluated different combinations of organic acid (OA) wash solutions for their ability to reduce bacterial contamination of raw chicken skin and to inhibit growth of spoilage bacteria and path...

242

Carbohydrate fermentation in the human colon and its relation to acetate concentrations in venous blood.  

PubMed Central

There is now substantial evidence that some dietary polysaccharides, notably dietary fiber, escape absorption in the small bowel and are then broken down in the large intestine of man. The main end products of this colonic digestive process, which is anerobic, are short chain fatty acids (SCFA), and acetic, propionic, and butyric acids. Although these acids are known to be absorbed from the colon, their subsequent fate and significance is unknown. We have measured venous blood SCFA levels in healthy subjects after a 16-h fast, and then following oral doses of either 50 mmol SCFA, 5, 10, or 20 g doses of the fermentable carbohydrate lactulose, or 20 g of pectin. Fasting venous blood acetate was 53.8 +/- 4.4 mumol/liter (SEM) (n = 14). Fasting arterial blood acetate, taken simultaneously with venous blood in six subjects, was higher; 125.6 +/- 13.5 mumol/liter (arterial) vs. 61.1 +/- 6.9 mumol/liter (venous). Significant levels of propionate or butyrate were not detected in any blood samples. Following an oral dose of 50 mmol mixed SCFA, venous blood acetate reached a peak of 194.1 +/- 57.9 mumol/liter at 45 min and returned to fasting levels at 2 h. Blood acetate also rose in response to lactulose, peak levels occurring 2-4 h after the dose: 5 g, 98.6 +/- 23.1 mumol/liter; 10 g, 127.3 +/- 18.2 mumol/liter; and 20 g, 181.3 +/- 23.9 mumol/liter. Pectin fermentation was much slower, with blood acetate levels starting to rise after 6 h and remaining elevated at about twice fasting levels for the subsequent 18 h. However, areas under the blood acetate curves were closely related (r = 0.97; n = 5), whatever the source of acetate. These studies show that the large intestine makes an important contribution to blood acetate levels in man and that fermentation may influence metabolic processes well beyond the wall of this organ. PMID:3998144

Pomare, E W; Branch, W J; Cummings, J H

1985-01-01

243

Cellulose, cellulases and cellulosomes  

Microsoft Academic Search

The structural complexity and rigidity of cellulosic substrates have given rise to a phenomenal diversity of degradative enzymes — the cellulases. Cellulolytic microorganisms produce a wide variety of different catalytic and noncatalytic enzyme modules, which form the cellulases and act synergistically on their substrate. In some microbes, several types of cellulases are organized into an elaborate multifunctional supramolecular complex, known

Edward A Bayer; Henri Chanzy; Raphael Lamed; Yuval Shoham

1998-01-01

244

Enzymatic hydrolysis of cellulose  

SciTech Connect

This book reviews the theory and application of enzymatic hydrolysis of cellulosic biomass; with implications for genetic engineering techniques. State of the art and potential industrial processes are detailed, including high productivity fermentation systems for the production of ethanol. Contents: Theory of Enzymatic Hydrolysis; Production of Cellulase and Xylanase; Hydrolysis of Agricultural Residues; Enzymatic Hydrolysis Processes; High Productivity Ethanol Fermentation; Ethanol Economics.

Wilke, C.R.

1983-01-01

245

Bioenergy- Cellulosic Biofuels Overview  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this presentation from James D. McMillan on cellulosic biofuels. The workshop is intended for high school and community college energy technology instructors. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Mcmillan, James D.

2011-05-06

246

Cellulose Synthesis and Its Regulation  

PubMed Central

Cellulose, the most abundant biopolymer synthesized on land, is made of linear chains of ß (1–4) linked D-glucose. As a major structural component of the cell wall, cellulose is important not only for industrial use but also for plant growth and development. Cellulose microfibrils are tethered by other cell wall polysaccharides such as hemicellulose, pectin, and lignin. In higher plants, cellulose is synthesized by plasma membrane-localized rosette cellulose synthase complexes. Despite the recent advances using a combination of molecular genetics, live cell imaging, and spectroscopic tools, many aspects of the cellulose synthesis remain a mystery. In this chapter, we highlight recent research progress towards understanding the mechanism of cellulose synthesis in Arabidopsis. PMID:24465174

Li, Shundai; Bashline, Logan; Lei, Lei; Gu, Ying

2014-01-01

247

Per-O-acetylation of cellulose in dimethyl sulfoxide with catalyzed transesterification.  

PubMed

Cellulose acetylation was investigated in dimethyl sulfoxide (DMSO) with isopropenyl acetate (IPA) as acetylating reagent and 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as catalyst at 70-130 °C for 3-12 h. The degree of substitution (DS) of acetylated cellulose was comparatively determined by titration and ¹H NMR and confirmed by FT-IR analysis. The results indicated that per-O-acetylation was achieved at >90 °C for a relatively long duration. The three well-resolved peaks of carbonyl carbons in ¹³C NMR spectra also provided evidence of per-O-acetylation. The solubility of cellulose acetates in common organic solvents was examined, and the result showed that chloroform can be an alternative choice as a solvent for fully acetylated cellulose formed in this study besides DMSO. The intrinsic viscosity of acetylated cellulose solution implied almost no degradation of cellulose during acetylation in DMSO except at higher temperature (130 °C) for a long time. PMID:24678805

Chen, Chao-Yi; Chen, Ming-Jie; Zhang, Xue-Qin; Liu, Chuan-Fu; Sun, Run-Cang

2014-04-16

248

Enzymatic hydrolysis of cellulose pretreated with ionic liquids and N-methyl Morpholine N-Oxide  

NASA Astrophysics Data System (ADS)

The effect of N-methyl Morpholine N-Oxide (NMMO), 1-ethyl-3-methyl-imidazolium acetate ([Emim]Ac) and 1-ethyl-3-methyl-imidazolium diethyl phosphate ([Emim]DEP) on pretreatment and enzymatic hydrolysis of dissolving pulp was studied. X-ray diffraction measurements of regenerated cellulose from these solvents showed that solvent pretreatment reduces the crystallinity of cellulose. However, crystallinity might not be a major factor affecting the in-situ enzymatic hydrolysis of cellulose in these solvents. Although regenerated cellulose from [Emim]DEP showed the lowest crystallinity index (˜15%), in-situ enzymatic hydrolysis of cellulose dissolved in NMMO showed the highest cellulose conversion (68% compared to 65% for [Emim]Ac and 37% for [Emim]DEP at enzyme loading of 122 FPU/g). Moreover, results showed that enzymes could tolerate up to NMMO concentration of 100 g/L and still yield full conversion of cellulose. Since it is not necessary to remove all the NMMO, less amount of water will be required for the washing step and thus the process will be more economical. The HCH-1 model was used in an attempt to model the enzymatic hydrolysis of cellulose in NMMO. With the incorporation of NMMO inhibition and a factor to account for unreacted cellulose, the model was able to correlate the experimental data of the enzymatic hydrolysis of cellulose (6.68 g/L) at various NMMO concentrations (0, 50, 100, 150 and 250 g/L). However, the experimental results also suggest that NMMO might be deactivating the enzymes rather than inhibiting them. More studies need to be done at varying cellulose, NMMO and enzyme concentrations to find the exact nature of this deactivation of NMMO.

Yau Li, Elizabeth

249

Efficient utilization of hemicellulose hydrolysate for propionic acid production using Propionibacterium acidipropionici.  

PubMed

Hemicellulose, which contains glucose, xylose, and arabinose as the 3 main sugars, is an important renewable source for biorefinery. In this study, propionic acid production from glucose, xylose, or arabinose using Propionibacterium acidipropionici ATCC 4875 was investigated. Using xylose, the predominant sugar in hemicellulose, a final propionic acid concentration of 53.2 g l(-1) was obtained via fed-batch fermentation. Using corncob molasses, a waste by-product from xylitol production as a representative of hemicellulose hydrolysate, the final concentration of propionic acid was 71.8 g l(-1), with a corresponding productivity of 0.28 g l(-1) h(-1). The present study suggests that hemicellulose hydrolysate is an excellent carbon source for efficient propionic acid production by this strain. PMID:22481002

Liu, Zhen; Ma, Cuiqing; Gao, Chao; Xu, Ping

2012-06-01

250

Co-inoculating ruminal content neither provides active hydrolytic microbes nor improves methanization of ¹³C-cellulose in batch digesters.  

PubMed

Cellulose hydrolysis often limits the kinetics and efficiency of anaerobic degradation in industrial digesters. In animal digestive systems, specialized microorganisms enable cellulose biodegradation at significantly higher rates. This study aims to assess the potential of ruminal microbial communities to settle and to express their cellulolytic properties in anaerobic digesters. Cellulose-degrading batch incubations were co-inoculated with municipal solid waste digester sludge and ruminal content. ¹³C-labeled cellulose degradation was described over time with Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry. Results were linked to the identification of the microorganisms assimilating ¹³C and to the monitoring of their relative dynamics. Cellulose degradation in co-inoculated incubations was efficient but not significantly improved. Transient disturbances in degradation pathways occurred, as revealed by propionate accumulation. Automated Ribosomal Intergenic Spacer Analysis dynamics and pyrosequencing revealed that expected classes of Bacteria and Archaea were active and degraded cellulose. However, despite the favorable co-inoculation conditions, molecular tools also revealed that no ruminal species settled in the bioreactors. Other specific parameters were probably needed for this to happen. This study shows that exploiting the rumen's cellulolytic properties in anaerobic digesters is not straightforward. Co-inoculation can only be successful if ruminal microorganisms manage to thrive in the anaerobic digester and outcompete native microorganisms, which requires specific nutritional and environmental parameters, and a meticulous reproduction of the selection pressure encountered in the rumen. PMID:24219327

Chapleur, Olivier; Bize, Ariane; Serain, Thibaut; Mazéas, Laurent; Bouchez, Théodore

2014-03-01

251

The effects of ethyl cellulose on PV performance of DSSC made of nanostructured ZnO pastes  

Microsoft Academic Search

Nanostructured ZnO aggregates are synthesized via a hydrolysis route using zinc acetate dehydrate and diethylene glycol as the starting materials under carefully controlled conditions. They are employed in making a series of pastes with various ratios of the ZnO to ethyl cellulose for dye-sensitized solar cells, where the ZnO films are formed by doctor blade technique. Use of ethyl cellulose

Hui Li; Zhibin Xie; Yu Zhang; John Wang

2010-01-01

252

High cell density propionic acid fermentation with an acid tolerant strain of Propionibacterium acidipropionici.  

PubMed

Propionic acid is an important chemical with wide applications and its production via fermentation is of great interest. However, economic production of bio-based propionic acid requires high product titer, yield, and productivity in the fermentation. A highly efficient and stable high cell density (HCD) fermentation process with cell recycle by centrifugation was developed for propionic acid production from glucose using an acid-tolerant strain of Propionibacterium acidipropionici, which had a higher specific growth rate, productivity, and acid tolerance compared to the wild type ATCC 4875. The sequential batch HCD fermentation at pH 6.5 produced propionic acid at a high titer of ?40?g/L and productivity of 2.98?g/L?h, with a yield of ?0.44?g/g. The product yield increased to 0.53-0.62?g/g at a lower pH of 5.0-5.5, which, however, decreased the productivity to 1.28?g/L?h. A higher final propionic acid titer of >55?g/L with a productivity of 2.23?g/L?h was obtained in fed-batch HCD fermentation at pH 6.5. A 3-stage simulated fed-batch process in serum bottles produced 49.2?g/L propionic acid with a yield of 0.53?g/g and productivity of 0.66?g/L?h. These productivities, yields and propionic acid titers were among the highest ever obtained in free-cell propionic acid fermentation. Biotechnol. Bioeng. 2014;9999: 1-10. © 2014 Wiley Periodicals, Inc. PMID:25257628

Wang, Zhongqiang; Jin, Ying; Yang, Shang-Tian

2014-09-25

253

Treatment of severe erosive gingival lesions by topical application of clobetasol propionate in custom trays  

Microsoft Academic Search

Objective. We sought to describe the response of patients with severe erosive gingival lesions to treatment with clobetasol propionate in Orabase paste administered in trays. The adverse effects were also recorded. Study Design. A descriptive pretest\\/posttest clinical study with no control group (33 patients total) was developed. All patients received repeated applications of 0.05% clobetasol propionate plus 100,000 IU\\/cc of

Miguel Angel Gonzalez-Moles; Isabel Ruiz-Avila; Alberto Rodriguez-Archilla; Patricia Morales-Garcia; Francisco Mesa-Aguado; Antonio Bascones-Martinez; Manuel Bravo

2003-01-01

254

Antioxidants successfully reduce ROS production in propionic acidemia fibroblasts.  

PubMed

Propionic acidemia (PA), caused by a deficiency of the mitochondrial biotin dependent enzyme propionyl-CoA carboxylase (PCC) is one of the most frequent organic acidurias in humans. Most PA patients present in the neonatal period with metabolic acidosis and hyperammonemia, developing different neurological symptoms, movement disorders and cardiac complications. There is strong evidence indicating that oxidative damage could be a pathogenic factor in neurodegenerative, mitochondrial and metabolic diseases. Recently, we identified an increase in ROS levels in PA patients-derived fibroblasts. Here, we analyze the capability of seven antioxidants to scavenge ROS production in PA patients' cells. Tiron, trolox, resveratrol and MitoQ significantly reduced ROS content in patients and controls' fibroblasts. In addition, changes in the expression of two antioxidant enzymes, superoxide dismutase and glutathione peroxidase, were observed in PA patients-derived fibroblasts after tiron and resveratrol treatment. Our results in PA cellular models establish the proof of concept of the potential of antioxidants as an adjuvant therapy for PA and pave the way for future assessment of antioxidant strategies in the murine model of PA. PMID:25159844

Gallego-Villar, Lorena; Pérez, Belén; Ugarte, Magdalena; Desviat, Lourdes R; Richard, Eva

2014-09-26

255

Reinforcement of bacterial cellulose aerogels with biocompatible polymers.  

PubMed

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

Pircher, N; Veigel, S; Aigner, N; Nedelec, J M; Rosenau, T; Liebner, F

2014-10-13

256

Responses of Blood Glucose, Insulin, Glucagon, and Fatty Acids to Intraruminal Infusion of Propionate in Hanwoo  

PubMed Central

This study was carried out to investigate the effects of intraruminal infusion of propionate on ruminal fermentation characteristics and blood hormones and metabolites in Hanwoo (Korean cattle) steers. Four Hanwoo steers (average body wt. 270 kg, 13 month of age) equipped with rumen cannula were infused into rumens with 0.0 M (Water, C), 0.5 M (37 g/L, T1), 1.0 M (74 g/L, T2) and 1.5 M (111 g/L, T3) of propionate for 1 hour per day and allotted by 4×4 Latin square design. On the 5th day of infusion, samples of rumen and blood were collected at 0, 60, 120, 180, and 300 min after intraruminal infusion of propionate. The concentrations of serum glucose and plasma glucagon were not affected (p>0.05) by intraruminal infusion of propionate. The serum insulin concentration at 60 min after infusion was significantly (p<0.05) higher in T3 than in C, while the concentration of non-esterified fatty acid (NEFA) at 60 and 180 min after infusion was significantly (p<0.05) lower in the propionate treatments than in C. Hence, intraruminal infusion of propionate stimulates the secretion of insulin, and decreases serum NEFA concentration rather than the change of serum glucose concentration. PMID:25557815

Oh, Y. K.; Eun, J. S.; Lee, S. C.; Chu, G. M.; Lee, Sung S.; Moon, Y. H.

2015-01-01

257

Responses of blood glucose, insulin, glucagon, and Fatty acids to intraruminal infusion of propionate in hanwoo.  

PubMed

This study was carried out to investigate the effects of intraruminal infusion of propionate on ruminal fermentation characteristics and blood hormones and metabolites in Hanwoo (Korean cattle) steers. Four Hanwoo steers (average body wt. 270 kg, 13 month of age) equipped with rumen cannula were infused into rumens with 0.0 M (Water, C), 0.5 M (37 g/L, T1), 1.0 M (74 g/L, T2) and 1.5 M (111 g/L, T3) of propionate for 1 hour per day and allotted by 4×4 Latin square design. On the 5th day of infusion, samples of rumen and blood were collected at 0, 60, 120, 180, and 300 min after intraruminal infusion of propionate. The concentrations of serum glucose and plasma glucagon were not affected (p>0.05) by intraruminal infusion of propionate. The serum insulin concentration at 60 min after infusion was significantly (p<0.05) higher in T3 than in C, while the concentration of non-esterified fatty acid (NEFA) at 60 and 180 min after infusion was significantly (p<0.05) lower in the propionate treatments than in C. Hence, intraruminal infusion of propionate stimulates the secretion of insulin, and decreases serum NEFA concentration rather than the change of serum glucose concentration. PMID:25557815

Oh, Y K; Eun, J S; Lee, S C; Chu, G M; Lee, Sung S; Moon, Y H

2015-02-01

258

Acetate and formate uptake into vesicles isolated from the basolateral region of the plasma membrane of ovine parotid acinar cells.  

PubMed

The transport of acetate and formate into plasma membrane vesicles derived from the basolateral face of the ovine parotid acinar cell has an absolute requirement for an anion to be present within the intravesicular space: bicarbonate, formate, acetate, propionate, and butyrate support the uptake of either acetate or formate. A pH gradient across the vesicle membrane, pHi 7.4, pH0 5.5, enhances the uptake of formate, but not acetate. There is no direct relationship between the rate of exchange and the degree of protonation of formate or acetate in the extravesicular medium. The process is saturable and can be inhibited by a range of functional group reagents. When mannitol is the main external osmoticum, the uptake of acetate and formate is still rapid; thus, no other ions are involved in the process apart from the external formate or acetate and the intravesicular anion. This activity could play a major role in the provision of energy in ruminant tissues. PMID:10364465

Nguyen, H V; Beechey, R B

1999-06-16

259

Effects of ethyl-3-nitrooxy propionate and 3-nitrooxypropanol on ruminal fermentation, microbial abundance, and methane emissions in sheep.  

PubMed

The aim of this work was to investigate the effect of feeding ethyl-3-nitrooxy propionate (E3NP) and 3-nitrooxypropanol (3 NP), 2 recently developed compounds with potential antimethanogenic activity, in vitro and in vivo in nonlactating sheep on ruminal methane production, fermentation pattern, the abundance of major microbial groups, and feed degradability. Three experiments were conducted, 1 in vitro and 2 in vivo. The in vitro batch culture trial (experiment 1) tested 2 doses of E3NP and 3 NP (40 and 80 ?L/L), which showed a substantial reduction of methane production (up to 95%) without affecting concentration of volatile fatty acids (VFA). The 2 in vivo trials were conducted over 16 d (experiment 2) and 30 d (experiment 3) to study their effects in sheep. In experiment 2, 6 adult nonpregnant sheep, with permanent rumen cannula and fed alfalfa hay and oats (60:40), were treated with E3NP at 2 doses (50 and 500 mg/animal per day). After 7, 14, and 15 d of treatment, methane emissions were recorded in respiration chambers and rumen fluid samples were collected for VFA analysis and quantification of bacterial, protozoal, and archaeal numbers by real-time PCR. Methane production decreased by 29% compared with the control with the higher dose of E3NP on d 14 to 15. A decrease in the acetate:propionate ratio was observed without detrimental effects on dry matter intake. In experiment 3, 9 adult nonpregnant sheep, with permanent rumen cannula and fed with alfalfa hay and oats (60:40), were treated with E3NP or 3 NP at one dose (100mg/animal per day) over 30 d. On d 14 and d 29 to 30, methane emissions were recorded in respiration chambers. Rumen fluid samples were collected on d 29 and 30 for VFA analysis and quantification of bacterial, protozoal, and archaeal numbers by real-time PCR. In addition, on d 22 and 23, samples of oats and alfalfa hay were incubated in the rumen of sheep to determine dry matter ruminal degradation over 24 and 48 h, respectively; no effect was observed (78.6, 78.3, and 78.8% of alfalfa and 74.2, 74.0, and 70.6% of oats in control, E3NP, and 3 NP groups, respectively). A reduction in methane production was observed for both additives at d 14 and d 29 to 30. In both treatments, the acetate:propionate ratio was significantly decreased. Likewise, total concentrations of the analyzed microbial groups in the rumen showed no difference among treatments and doses for both experiments. Both tested compounds showed promise as methane inhibitors in the rumen, with no detrimental effects on fermentation or intake, which would need to be confirmed in lactating animals. PMID:24731636

Martínez-Fernández, G; Abecia, L; Arco, A; Cantalapiedra-Hijar, G; Martín-García, A I; Molina-Alcaide, E; Kindermann, M; Duval, S; Yáñez-Ruiz, D R

2014-06-01

260

Cellulose synthesis: a complex complex.  

PubMed

Cellulose is the world's most abundant biopolymer and a key structural component of the plant cell wall. Cellulose is comprised of hydrogen-bonded beta-1,4-linked glucan chains that are synthesized at the plasma membrane by large cellulose synthase (CESA) complexes. Recent advances in visualization of fluorescently labelled complexes have facilitated exploration of regulatory modes of cellulose production. For example, several herbicides, such as isoxaben and 2,6-dichlorobenzonitrile that inhibit cellulose production appear to affect different aspects of synthesis. Dual-labelling of cytoskeletal components and CESAs has revealed dynamic feedback regulation between cellulose synthesis and microtubule orientation and organization. In addition, fluorescently tagged CESA2 subunits may substitute for another subunit, CESA6, which suggests both plasticity and specificity for one of the components of the CESA complex. PMID:18485800

Mutwil, Marek; Debolt, Seth; Persson, Staffan

2008-06-01

261

Preparation and biological activity of 2-[4-(thiazol-2-yl)phenyl]propionic acid derivatives inhibiting cyclooxygenase.  

PubMed

A series of 2-[4-(thiazol-2-yl)phenyl]propionic acids substituted at various positions were prepared by the reaction of diethyl 2-methyl-2-(4-thiocarbamoylphenyl)malonates with alpha-bromoaldehyde diethyl acetals or alpha-haloketones followed by hydrolysis of esters. The inhibition of prostaglandin H synthetase (cyclooxygenase) was assayed by use of an enzyme preparation from guinea pig polymorphonuclear leukocytes. Examination of the structure-activity relationship of these compounds indicated that the substitution pattern with halogens at position 3 (R1) of the benzene ring and a methyl group in position 4 (R2) and/or 5 (R3) of the thiazole ring were favorable for inhibitory activity. The compounds bearing bulky alkyl or polar functional groups at the R2 position were weak inhibitors. The potent inhibitors of cyclooxygenase were tested for their ability to reduce carrageenin-induced inflammation of rat paws. These derivatives had strong anti-inflammatory activity based on their strong inhibition of cyclooxygenase, with some exceptions, including those with a thiomethyl group at R1. PMID:1804546

Naito, Y; Goto, T; Akahoshi, F; Ono, S; Yoshitomi, H; Okano, T; Sugiyama, N; Abe, S; Hanada, S; Hirata, M

1991-09-01

262

Acetic acid bacteria in oenology  

Microsoft Academic Search

Acetic acid bacteria have always been considered the bad mi- croorganisms of oenology; responsible for wine spoiling (vine- gary taint). The taxonomy and our knowledge of the metabo- lism of acetic acid bacteria are rapidly evolving, especially as new molecular biology techniques are applied to this fastidious group of microorganisms, which are still rather difficult to work with. The dramatic

A. Mas; M. J. Torija; A. González; M. Poblet; J. M. Guillamón

263

Production of succinate from glucose, cellobiose, and various cellulosic materials by the ruminai anaerobic bacteria Fibrobacter succinogenes and Ruminococcus flavefaciens  

Microsoft Academic Search

The production of organic acids by two anaerobic ruminal bacteria,Fibrobacter succinogenes S85 andRuminococcus flavefaciens FD-1, was compared with glucose, cellobiose, microcrystalline cellulose, Walseth cellulose (acid swollen cellulose), pulped\\u000a paper, and steam-exploded yellow poplar as substrates. The major end product produced byF. succinogenes from each of these substrates was succinate (69.5–83%), the principal secondary product was acetate (16–30.5%). Maximum succinate\\u000a productivity

R. R. Gokarn; M. A. Eiteman; S. A. Martin; K.-E. L. Eriksson

1997-01-01

264

Molecular Structure of Phenylmercuric acetate  

NSDL National Science Digital Library

Phenylmercuric acetate is white to white-yellow crystalline powder that is odorless. This phenyl mercury compound is used mainly as a fungicide, herbicide, slimicide and bacteriocide. Phenylmercuric acid serves as a preservative in canned paint, eye ointments and drops, injectable solutions, skin disinfectants and in cosmetics products such as hair shampoos, mouthwashes and toothpastes. It is also used in contraceptive gels and foams. Phenylmercuric acetate is prepared by interaction of benzene with mercuric acetate in glacial acetic acid. Phenylmercuric acetate's former production and use as a fungicide and as a mildew inhibitor in paints may have resulted in its direct release to the environment. This substance is very toxic to aquatic organisms and may be hazardous to the environment.

2004-11-10

265

Comparison of the efficacy of combined fluticasone propionate and olopatadine versus combined fluticasone propionate and fexofenadine for the treatment of allergic rhinoconjunctivitis induced by conjunctival allergen challenge  

Microsoft Academic Search

Background: One approach to treating allergic rhinoconjunctivitis is the concomitant use of an intranasal spray such as fluticasone propionate to alleviate nasal symptoms and a topical or systemic agent to relieve ocular symptoms. It has not yet been determined whether a topical or systemic agent is more effective for the latter purpose.Objective: This study compared the efficacy of combined use

Bob Q. Lanier; Mark B. Abelson; William E. Berger; David B. Granet; Peter A. D'Arienzo; Dennis L. Spangler; Martin K. Kägi

2002-01-01

266

Supercapacitance from Cellulose and Carbon Nanotube Nanocomposite Fibers  

PubMed Central

Multiwalled carbon nanotube (MWNT)/cellulose composite nanofibers have been prepared by electrospinning a MWNT/cellulose acetate blend solution followed by deacetylation. These composite nanofibers were then used as precursors for carbon nanofibers (CNFs). The effect of nanotubes on the stabilization of the precursor and microstructure of the resultant CNFs were investigated using thermogravimetric analysis, transmission electron microscopy and Raman spectroscopy. It is demonstrated that the incorporated MWNTs reduce the activation energy of the oxidative stabilization of cellulose nanofibers from ?230 to ?180 kJ mol–1. They also increase the crystallite size, structural order, and electrical conductivity of the activated CNFs (ACNFs). The surface area of the ACNFs increased upon addition of nanotubes which protrude from the fiber leading to a rougher surface. The ACNFs were used as the electrodes of a supercapacitor. The electrochemical capacitance of the ACNF derived from pure cellulose nanofibers is demonstrated to be 105 F g–1 at a current density of 10 A g–1, which increases to 145 F g–1 upon the addition of 6% of MWNTs. PMID:24070254

2013-01-01

267

Supercapacitance from cellulose and carbon nanotube nanocomposite fibers.  

PubMed

Multiwalled carbon nanotube (MWNT)/cellulose composite nanofibers have been prepared by electrospinning a MWNT/cellulose acetate blend solution followed by deacetylation. These composite nanofibers were then used as precursors for carbon nanofibers (CNFs). The effect of nanotubes on the stabilization of the precursor and microstructure of the resultant CNFs were investigated using thermogravimetric analysis, transmission electron microscopy and Raman spectroscopy. It is demonstrated that the incorporated MWNTs reduce the activation energy of the oxidative stabilization of cellulose nanofibers from ?230 to ?180 kJ mol(-1). They also increase the crystallite size, structural order, and electrical conductivity of the activated CNFs (ACNFs). The surface area of the ACNFs increased upon addition of nanotubes which protrude from the fiber leading to a rougher surface. The ACNFs were used as the electrodes of a supercapacitor. The electrochemical capacitance of the ACNF derived from pure cellulose nanofibers is demonstrated to be 105 F g(-1) at a current density of 10 A g(-1), which increases to 145 F g(-1) upon the addition of 6% of MWNTs. PMID:24070254

Deng, Libo; Young, Robert J; Kinloch, Ian A; Abdelkader, Amr M; Holmes, Stuart M; De Haro-Del Rio, David A; Eichhorn, Stephen J

2013-10-23

268

Facile pulping of lignocellulosic biomass using choline acetate.  

PubMed

Treating ground bagasse or Southern yellow pine in the biodegradable ionic liquid (IL), choline acetate ([Cho][OAc]), at 100°C for 24h led to dissolution of hemicellulose and lignin, while leaving the cellulose pulp undissolved, with a 54.3% (bagasse) or 34.3% (pine) reduction in lignin content. The IL solution of the dissolved biopolymers can be separated from the undissolved particles either by addition of water (20 wt% of IL) followed by filtration or by centrifugation. Hemicellulose (19.0 wt% of original bagasse, 10.2 wt% of original pine, containing 14-18 wt% lignin) and lignin (5.0 wt% of original bagasse, 6.0 wt% of original pine) could be subsequently precipitated. The pulp obtained from [Cho][OAc] treatment can be rapidly dissolved in 1-ethyl-3-methylimidazolium acetate (e.g., 17 h for raw bagasse vs. 7h for pulp), and precipitated as cellulose-rich material (CRM) with a lower lignin content (e.g., 23.6% for raw bagasse vs. 10.6% for CRM). PMID:24874879

Cheng, Fangchao; Wang, Hui; Chatel, Gregory; Gurau, Gabriela; Rogers, Robin D

2014-07-01

269

Production of H(2) from cellulose by rumen microorganisms: effects of inocula pre-treatment and enzymatic hydrolysis.  

PubMed

H2 production from cellulose, using rumen fluid as the inoculum, has been investigated in batch experiments. Methanogenic archaea were inhibited by acid pre-treatment, which also inhibited cellulolytic microorganisms, and in consequence, the conversion of cellulose to H2. Positive results were observed only with the addition of cellulase. H2 yields were 18.5 and 9.6 mmol H2 g cellulose(-1) for reactors with 2 and 4 g cellulose l(-1) and cellulase, respectively. H2 was primarily generated by the butyric acid pathway and this was followed by formation of acetic acid, ethanol and n-butanol. In reactors using 4 g cellulose l(-1) and cellulase, the accumulation of alcohols negatively affected the H2 yield, which changed the fermentation pathways to solventogenesis. PCR-DGGE analysis showed changes in the microbial communities. The phylogenetic affiliations of the bands of DGGE were 99 % similar to Clostridium sp. PMID:24190478

Ratti, Regiane Priscila; Botta, Lívia Silva; Sakamoto, Isabel Kimiko; Silva, Edson Luiz; Varesche, Maria Bernadete Amâncio

2014-03-01

270

Cellulose biogenesis in Dictyostelium discoideum  

SciTech Connect

Organisms that synthesize cellulose can be found amongst the bacteria, protistans, fungi, and animals, but it is in plants that the importance of cellulose in function (as the major structural constituent of plant cell walls) and economic use (as wood and fiber) can be best appreciated. The structure of cellulose and its biosynthesis have been the subjects of intense investigation. One of the most important insights gained from these studies is that the synthesis of cellulose by living organisms involves much more than simply the polymerization of glucose into a (1{r_arrow}4)-{beta}-linked polymer. The number of glucoses in a polymer (the degree of polymerization), the crystalline form assumed by the glucan chains when they crystallize to form a microfibril, and the dimensions and orientation of the microfibrils are all subject to cellular control. Instead of cellulose biosynthesis, a more appropriate term might be cellulose biogenesis, to emphasize the involvement of cellular structures and mechanisms in controlling polymerization and directing crystallization and deposition. Dictyostelium discoideum is uniquely suitable for the study of cellulose biogenesis because of its amenability to experimental study and manipulation and the extent of our knowledge of its basic cellular mechanisms (as will be evident from the rest of this volume). In this chapter, I will summarize what is known about cellulose biogenesis in D. discoideum, emphasizing its potential to illuminate our understanding both of D. discoideum development and plant cellulose biogenesis.

Blanton, R.L.

1993-12-31

271

Propionic acid fermentation by Propionibacterium freudenreichii CCTCC M207015 in a multi-point fibrous-bed bioreactor.  

PubMed

Propionic acid was produced in a multi-point fibrous-bed (MFB) bioreactor by Propionibacterium freudenreichii CCTCC M207015. The MFB bioreactor, comprising spiral cotton fiber packed in a modified 7.5-l bioreactor, was effective for cell-immobilized propionic acid production compared with conventional free cell fermentation. Batch fermentations at various glucose concentrations were investigated in the MFB bioreactor. Based on analysis of the time course of production, a fed-batch strategy was applied for propionic acid production. The maximum propionic acid concentration was 67.05 g l(-1) after 496 h of fermentation, and the proportion of propionic acid to total organic acids was approximately 78.28% (w/w). The MFB bioreactor exhibited excellent production stability during batch fermentation and the propionic acid productivity remained high after 78 days of fermentation. PMID:20589397

Feng, Xiao-Hai; Chen, Fei; Xu, Hong; Wu, Bo; Yao, Jun; Ying, Han-Jie; Ouyang, Ping-Kai

2010-11-01

272

Development of an industrializable fermentation process for propionic acid production.  

PubMed

Propionic acid (PA) is a short-chain fatty acid with wide industrial application including uses in pharmaceuticals, herbicides, cosmetics, and food preservatives. As a three-carbon building block, PA also has potential as a precursor for high-volume commodity chemicals such as propylene. Currently, most PA is manufactured through petrochemical routes, which can be tied to increasing prices and volatility due to difficulty in demand forecasting and feedstock availability. Herein described are research advancements to develop an industrially feasible, renewable route to PA. Seventeen Propionibacterium strains were screened using glucose and sucrose as the carbon source to identify the best platform strain. Propionibacterium acidipropionici ATCC 4875 was selected as the platform strain and subsequent fermentation optimization studies were performed to maximize productivity and yield. Fermentation productivity was improved three-fold to exceed 2 g/l/h by densifying the inoculum source. Byproduct levels, particularly lactic and succinic acid, were reduced by optimizing fermentor headspace pressure and shear. Following achievement of commercially viable productivities, the lab-grade medium components were replaced with industrial counterparts to further reduce fermentation costs. A pure enzymatically treated corn mash (ECM) medium improved the apparent PA yield to 0.6 g/g (PA produced/glucose consumed), but it came at the cost of reduced productivity. Supplementation of ECM with cyanocobalamin restored productivity to near lab-grade media levels. The optimized ECM recipe achieved a productivity of 0.5 g/l/h with an apparent PA yield of 0.60 g/g corresponding to a media cost <1 USD/kg of PA. These improvements significantly narrow the gap between the fermentation and incumbent petrochemical processes, which is estimated to have a manufacturing cost of 0.82 USD/kg in 2017. PMID:24627047

Stowers, Chris C; Cox, Brad M; Rodriguez, Brandon A

2014-05-01

273

Electricity production from cellulose in a microbial fuel cell using a defined binary culture.  

PubMed

Microbial fuel cells (MFCs) convert biodegradable materials into electricity, potentially contributing to an array of renewable energy production strategies tailored for specific applications. Since there are no known microorganisms that can both metabolize cellulose and transfer electrons to solid extracellular substrates, the conversion of cellulosic biomass to electricity requires a syntrophic microbial community that uses an insoluble electron donor (cellulose) and electron acceptor (anode). Electricity was generated from cellulose in an MFC using a defined coculture of the cellulolytic fermenter Clostridium cellulolyticum and the electrochemically active Geobacter sulfurreducens. In fed-batch tests using two-chamber MFCs with ferricyanide as the catholyte, the coculture achieved maximum power densities of 143 mW/ m2 (anode area) and 59.2 mW/m2 from 1 g/L carboxymethyl cellulose (CMC) and MN301 cellulose, respectively. Neither pure culture alone produced electricity from these substrates. The coculture increased CMC degradation from 42% to 64% compared to a pure C. cellulolyticum culture. COD removal using CMC and MN301 was 38 and 27%, respectively, with corresponding Coulombic efficiencies of 47 and 39%. Hydrogen, acetate, and ethanol were the main residual metabolites of the binary culture. Cellulose conversion to electricity was also demonstrated using an uncharacterized mixed culture from activated sludge with an aerobic aqueous cathode. PMID:17695929

Ren, Zhiyong; Ward, Thomas E; Regan, John M

2007-07-01

274

Sequential changes in propionate metabolism during the development of cobalt\\/vitamin B 12 deficiency in sheep  

Microsoft Academic Search

The changes in propionate metabolism that accompany cobalt deficiency in sheep are described. Two groups of sheep, fed either\\u000a a cobalt sufficient or deficient diet, were given an iv propionate load at intervals during a 14 w experiment. There was a\\u000a tendency towards increased propionate half-life as the animals became cobalt deficient. However, significant changes in the\\u000a area under the

D. Glenn Kennedy; Finbarr P. M. O'Harte; W. John Blanchflower; Desmond A. Rice

1991-01-01

275

Tyrosine B10 triggers a heme propionate hydrogen bonding network loop with glutamine E7 moiety  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer H-bonding network loop by PheB10Tyr mutation is proposed. Black-Right-Pointing-Pointer The propionate group H-bonding network restricted the flexibility of the heme. Black-Right-Pointing-Pointer The hydrogen bonding interaction modulates the electron density of the iron. Black-Right-Pointing-Pointer Propionate H-bonding network loop explains the heme-ligand stabilization. -- Abstract: Propionates, as peripheral groups of the heme active center in hemeproteins have been described to contribute in the modulation of heme reactivity and ligand selection. These electronic characteristics prompted the question of whether the presence of hydrogen bonding networks between propionates and distal amino acids present in the heme ligand moiety can modulate physiological relevant events, like ligand binding association and dissociation activities. Here, the role of these networks was evaluated by NMR spectroscopy using the hemoglobin I PheB10Tyr mutant from Lucina pectinata as model for TyrB10 and GlnE7 hemeproteins. {sup 1}H-NMR results for the rHbICN PheB10Tyr derivative showed chemical shifts of TyrB10 OH{eta} at 31.00 ppm, GlnE7 N{sub {epsilon}1}H/N{sub {epsilon}2}H at 10.66 ppm/-3.27 ppm, and PheE11 C{sub {delta}}H at 11.75 ppm, indicating the presence of a crowded, collapsed, and constrained distal pocket. Strong dipolar contacts and inter-residues crosspeaks between GlnE7/6-propionate group, GlnE7/TyrB10 and TyrB10/CN suggest that this hydrogen bonding network loop between GlnE7, TyrB10, 6-propionate group, and the heme ligand contribute significantly to the modulation of the heme iron electron density as well as the ligand stabilization mechanism. Therefore, the network loop presented here support the fact that the electron withdrawing character of the hydrogen bonding is controlled by the interaction of the propionates and the nearby electronic environments contributing to the modulation of the heme electron density state. Thus, we hypothesize that in hemeproteins with similar electrostatic environment the flexibility of the heme-6-propionate promotes a hydrogen bonding network loop between the 6-propionate, the heme ligand and nearby amino acids, tailoring in this way the electron density in the heme-ligand moiety.

Ramos-Santana, Brenda J., E-mail: brenda.ramos@upr.edu [Department of Chemistry, University of Puerto Rico, Mayagueez Campus, P.O. Box 9019, Mayagueez 00681-9019 (Puerto Rico); Lopez-Garriga, Juan, E-mail: juan.lopez16@upr.edu [Department of Chemistry, University of Puerto Rico, Mayagueez Campus, P.O. Box 9019, Mayagueez 00681-9019 (Puerto Rico)] [Department of Chemistry, University of Puerto Rico, Mayagueez Campus, P.O. Box 9019, Mayagueez 00681-9019 (Puerto Rico)

2012-08-10

276

Molecular Structure of Sodium acetate  

NSDL National Science Digital Library

Sodium acetate is known for its ability to supercool. It freezes at 130 degrees, but can exist as a liquid at a much lower temperature. In order to melt solidified sodium acetate, however, every single crystal must liquify, otherwise the material will recrystallize. Sodium acetate has been used as a deicer for roads and runways. It is also used a component of buffer systems and in the manufacture of pharmaceuticals and heat pads. The compound is quite stable. It may act as an irritant and be harmful if inhaled or absorbed through the skin.

2002-08-26

277

Thermophilic microbial cellulose decomposition and methanogenesis pathways recharacterized by metatranscriptomic and metagenomic analysis  

PubMed Central

The metatranscriptomic recharacterization in the present study captured microbial enzymes at the unprecedented scale of 40,000 active genes belonged to 2,269 KEGG functions were identified. The novel information obtained herein revealed interesting patterns and provides an initial transcriptional insight into the thermophilic cellulose methanization process. Synergistic beta-sugar consumption by Thermotogales is crucial for cellulose hydrolysis in the thermophilic cellulose-degrading consortium because the primary cellulose degraders Clostridiales showed metabolic incompetence in subsequent beta-sugar pathways. Additionally, comparable transcription of putative Sus-like polysaccharide utilization loci (PULs) was observed in an unclassified order of Bacteroidetes suggesting the importance of PULs mechanism for polysaccharides breakdown in thermophilic systems. Despite the abundance of acetate as a fermentation product, the acetate-utilizing Methanosarcinales were less prevalent by 60% than the hydrogenotrophic Methanobacteriales. Whereas the aceticlastic methanogenesis pathway was markedly more active in terms of transcriptional activities in key genes, indicating that the less dominant Methanosarcinales are more active than their hydrogenotrophic counterparts in methane metabolism. These findings suggest that the minority of aceticlastic methanogens are not necessarily associated with repressed metabolism, in a pattern that was commonly observed in the cellulose-based methanization consortium, and thus challenge the causal likelihood proposed by previous studies. PMID:25330991

Xia, Yu; Wang, Yubo; Fang, Herbert H. P.; Jin, Tao; Zhong, Huanzi; Zhang, Tong

2014-01-01

278

Cellulose binding domain fusion proteins  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

Shoseyov, O.; Yosef, K.; Shpiegl, I.; Goldstein, M.A.; Doi, R.H.

1998-02-17

279

Cellulose binding domain fusion proteins  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc A. (Davis, CA); Doi, Roy H. (Davis, CA)

1998-01-01

280

Cellulose Synthesis in Agrobacterium tumefaciens  

SciTech Connect

We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants including CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried out one preliminary experiment of this type and have successfully complemented an A. tumefaciens CelC mutant with the homologous gene (yhjM) from E. coli.

Alan R. White; Ann G. Matthysse

2004-07-31

281

Mutations participating in interallelic complementation in propionic acidemia  

SciTech Connect

Deficiency of propionyl-CoA carboxylase (PCC; [alpha][sub 4][beta][sub 4]) results in the rare, autosomal recessive disease propionic acidemia. Cell fusion experiments have revealed two complementation groups, pccA and pccB, corresponding to defects of the PCCA ([alpha]-subunit) and PCCB ([beta]-subunit) genes, respectively. The pccBCC group includes subgroups, pccB and pccC, which are thought to reflect interallelic complementation between certain mutations of the PCCB gene. In this study, the authors have identified the mutations in two pccB, one pccC, and two pccBC cell lines and have deduced those alleles participating in interallelic complementation. One pccB line was a compound hetrozygote of Pro228Leu and Asn536Asp. The latter mutation was also detected in a noncomplementing pccBC line. This leaves Pro228Leu responsible for complementation in the pccB cells. The second pccB line contained an insertional duplication, dupKICK140-143, and a splice mutation IVS+1 G[yields]T, located after Lys466. The authors suggest that the dupKICK mutation is the complementing allele, since the second allele is incompatible with normal splicing. The pccC line studied was homozygous for Arg410Trp, which is necessarily the complementing allele in that line. For a second pccC line, they previously had proposed that [Delta]Ile408 was the complementing allele. They now show that its second allele, [open quotes]Ins[center dot]Del[close quotes], a 14-bp deletion replaced by a 12-bp insertion beginning at codon 407, fails to complement in homozygous form. The authors conclude that the interallelic complementation results from mutations in domains that can interact between [beta]-subunits in the PCC heteromer to restore enzymatic function. On the basis of sequence homology with the Propionibacterium shermanii transcarboxylase 12S subunit, they suggest that the pccC domain, defined by Ile408 and Arg410, may involve the propionyl-CoA binding site. 37 refs., 5 figs., 2 tabs.

Gravel, R.A.; Akerman, B.R.; Lamhonwah, A.M.; Loyer, M.; Leon-del-Rio, A.; Italiano, I. (McGill Univ., Montreal (Canada))

1994-07-01

282

Preclinical safety of anecortave acetate.  

PubMed

A number of preclinical safety pharmacology and toxicity studies have been performed on the angiostatic cortisene anecortave acetate in various species and using different routes of administration (oral, intravenous, subcutaneous, topical ocular, intraocular injection, posterior juxtascleral) and a wide range of doses (0-1,000 mg/kg). Anecortave acetate did not interact with a broad panel of pharmacological receptors and had no apparent pharmacological effects on major organ systems including the central nervous, gastrointestinal, renal, cardiovascular, and respiratory systems. Oral, topical ocular, and posterior juxtascleral administration of anecortave acetate had no significant ocular or systemic side effects or toxicity. In addition, there was no significant carcinogenic or reproductive/developmental toxicity associated with anecortave acetate in genotoxicity, carcinogenicity, and reproductive toxicity studies. PMID:17240255

Heaton, Jim; Kastner, Philip; Hackett, Robert

2007-01-01

283

Influence of a cellulose diacetate matrix on the complexation kinetics of tetraphenylporphin with Zn and Cd  

NASA Astrophysics Data System (ADS)

The dependence of the reaction rate of tetraphenylporphin zinc and cadmium complexes in a polymer matrix on a base of cellulose diacetate and low-molecular model solutions was investigated. The characteristics of the diffusive transport of aqueous solutions of zinc and cadmium acetates through the cellulose diacetate membrane were obtained. The kinetic control of the porphyrin reaction incorporated into the polymer, and the determining influence of the steric limitations of the matrix of a rigid chain polymer on macroheterocycle deformation (and thus its reactivity) are shown.

Trifonova, I. P.; Kononov, V. D.; Burmistrov, V. A.; Koifman, O. I.

2011-04-01

284

Bioaugmentation with an acetate-type fermentation bacterium Acetobacteroides hydrogenigenes improves methane production from corn straw.  

PubMed

The effect of bioaugmentation with an acetate-type fermentation bacterium in the phylum Bacteroidetes on the anaerobic digestion of corn straw was evaluated by batch experiments. Acetobacteroides hydrogenigenes is a promising strain for bioaugmentation with relatively high growth rate, hydrogen yields and acetate tolerance, which ferments a broad spectrum of pentoses, hexoses and polyoses mainly into acetate and hydrogen. During corn straw digestion, bioaugmentation with A. hydrogenigenes led to 19-23% increase of the methane yield, with maximum of 258.1mL/g-corn straw achieved by 10% inoculation (control, 209.3mL/g-corn straw). Analysis of lignocellulosic composition indicated that A. hydrogenigenes could increase removal rates of cellulose and hemicelluloses in corn straw residue by 12% and 5%, respectively. Further experiment verified that the addition of A. hydrogenigenes could improve the methane yields of methyl cellulose and xylan (models for cellulose and hemicelluloses, respectively) by 16.8% and 7.0%. PMID:25549904

Zhang, Jie; Guo, Rong-Bo; Qiu, Yan-Ling; Qiao, Jiang-Tao; Yuan, Xian-Zheng; Shi, Xiao-Shuang; Wang, Chuan-Shui

2015-03-01

285

Water requirements of the rayon- and acetate-fiber industry  

USGS Publications Warehouse

Water is required for several purposes in the manufacture of rayon and acetate fiber. These water requirements, as indicated by a survey of the water used by the plants operating in 1953, are both quantitative and qualitative. About 300 mgd (million gallons per day) of water was used in 1953 in the preparation of purified wood cellulose and cotton linters, the basic material from which the rayon and acetate fiber is made. An additional 620 mgd was used in the process of converting the cellulose to rayon and acetate fiber. The total, 920 mgd, is about 1 percent of the total estimated withdrawals of industrial water in the United States in 1953. The rayon- and acetate-fiber plants are scattered through eastern United States and generally are located in small towns or rural areas where there are abundant supplies of clean, soft water. Water use at a typical rayon-fiber plant was about 9 mgd, and at a typical acetate-fiber plant about 38 mgd. About 110 gallons of water was used to produce a pound of rayon fiber, 32 gallons per pound was process water and the remainder was used largely for cooling in connection with power production and air conditioning. For the manufacture of a pound of acetate fiber about 170 gallons of water was used. However, the field survey on which this report is based indicated a wide range in the amount of water used per pound of product. For example, in the manufacture of viscose rayon, the maximum unit water use was 8 times the minimum unit water use. Water use in summer was about 22 percent greater than average annual use. About 8 mgd Of water was consumed by evaporation in the manufacture of rayon and acetate fiber. More than 90 percent of the water used by the rayon and acetate industry was with- drawn from surface-water sources, about 8 percent from ground water, and less than 2 percent from municipal water supplies. All available analyses of the untreated waters used by the rayon and acetate industry were collected and studied. The untreated waters were generally cool, low in content of calcium and magnesium, and very low in iron and manganese. At many plants, water was obtained from more than one source, and thus had different quality characteristics. Dissolved solids in all the untreated waters analyzed ranged between 14 and 747 ppm (parts per million) but in those waters used in processing the dissolved solids content was less than 200 ppm. The cooling water used by the industry is also generally of very high quality, principally because the requirements for a high-quality process water necessitate location of the plants in areas where such water is available.

Mussey, Orville Durey

1957-01-01

286

Cellulose Derivatives for Water Repellent Properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this poster presentation, we will discuss the synthesis and structural characterizations of nitro-benzyl cellulose (1), amino-benzyl cellulose (2) and pentafluoro –benzyl cellulose (3). All cellulose derivatives are synthesized by etherification process in lithium chloride/N,N-dimethylacetamide h...

287

Thermophilic degradation of cellulosic biomass  

NASA Astrophysics Data System (ADS)

The conversion of cellulosic biomass to chemical feedstocks and fuel by microbial fermentation is an important objective of developing biotechnology. Direct fermentation of cellulosic derivatives to ethanol by thermophilic bacteria offers a promising approach to this goal. Fermentations at elevated temperatures lowers the energy demand for cooling and also facilitates the recovery of volatile products. In addition, thermophilic microorganisms possess enzymes with greater stability than those from mesophilic microorganisms. Three anaerobic thermophilic cocultures that ferment cellulosic substrate mainly to ethanol have been described: Clostridium thermocellum/Clostriidium thermohydrosulfuricum, C. thermocellum/Clostridium thermosaccharolyticum, and C. thermocellum/Thermoanaerobacter ethanolicus sp. nov. The growth characteristics and metabolic features of these cocultures are reviewed.

Ng, T.; Zeikus, J. G.

1982-12-01

288

Facile transformation of hydrophilic cellulose into superhydrophobic cellulose.  

PubMed

Superhydrophobic cellulose-based materials coupled with transparent, stable and nanoscale polymethylsiloxane coating have been successfully achieved by a simple process via chemical vapor deposition, followed by hydrolyzation and polymerization. PMID:18361348

Li, Shenghai; Xie, Haibo; Zhang, Suobo; Wang, Xianhong

2007-12-14

289

Radiation degradation of cellulose  

NASA Astrophysics Data System (ADS)

The application of straw and other cellulose polymers as feedstuff for ruminants is limited by its low digestibility. During recent decades it was attempted to increase the digestibility of straw by several chemical and physical methods. In this work some results of the degradation of gamma and electron treated wheat straw are reported. Complex methods of treatment (e.g. radiation influence and influence of lyes) are taken into consideration. In vitro-experiments with radiation treated straw show that the digestibility can be increased from 20 % up to about 80 %. A high pressure liquid chromatography method was used to analyze the hydrolysates. The contents of certain species of carbohydrates in the hydrolysates in dependence on the applied dose are given.

Leonhardt, J.; Arnold, G.; Baer, M.; Langguth, H.; Gey, M.; Hübert, S.

290

a Study of Molecular Dynamics in Water-Cellulose Systems Using NMR  

NASA Astrophysics Data System (ADS)

This thesis presents the application of Nuclear Magnetic Resonance (NMR) to the study of the water dynamics in water-cellulose systems. Both H_2O and D_2O were used in polycrystalline Sigmacell 50 cellulose and in cellulose acetate films. Both the spectral lineshapes and various spin relaxation times were studied as functions of temperature and moisture content of the samples. ^1H and ^2 H NMR spectra of rm H_2O and rm D_2O absorbed in cellulose acetate films were observed while changing the angle between the plane of the film and the static magnetic field. ^1H-NMR spectra show dipolar splittings that vary depending on the angle. The splitting has a maximum when the surface of the film is perpendicular to the magnetic field. From the angular dependence of the dipolar splittings, it is deduced that the motionally averaged axis of the dipole moments is perpendicular to the film surface. ^2H NMR spectra show quadrupolar splittings which indicate that the motionally averaged axis of the electric quadrupole interaction is oriented perpendicular to the film. A number of NMR parameters were determined as a function of moisture content at 20^circ C for water adsorbed on Sigmacell 50 cellulose. The NMR parameters indicate that the cellulose swells as the water is added. Ninety-two percent of the cellulose is in crystalline domains and undergoes very little swelling indicating that it is largely inaccessible to water, whereas the remaining 8% is in paracrystalline or amorphous domains which are accessible to water and undergo considerable swelling. A three state model is applied for the protons in these samples, consisting of cellulose protons, water in intimate contact with these cellulose portons, and water which is not in intimate contact. Exchange and/or cross relaxation occurs between the three different proton groups. All the data are consistent with this model. An NMR relaxation study of water dynamics in hydrated Sigmacell 50 cellulose and cellulose acetate films has also been performed. In dry cellulose, there was a broad distribution of correlation times. A relaxation contribution from the motion of a small fraction of trapped water molecules was identified. The deuteron relaxation provided the intrinsic water relaxation rates. The water molecules are found to undergo anisotropic motion with about 94% of them in Sigmacell 50 and about 95% of them in cellulose acetate films reorienting rapidly about the hydrogen bound direction while the remainder reorient more slowly with one of their deuteron-oxygen bonds colinear with the hydrogen bond. These anisotropic motions give rise to a bimodal distribution of correlation times. The mean correlation times and the activation energy for each of the two motions have been determined. (Abstract shortened by UMI.).

Waana, Charles Musannyana

291

Synthesis and characterization of microcrystalline cellulose produced from bacterial cellulose  

Microsoft Academic Search

In this study, microcrystalline cellulose (MCC) was prepared from the acid hydrolysis of bacterial cellulose (BC) produced\\u000a in culture medium of static Acetobacter xylinum. The MCC-BC produced an average particle size between 70 and 90 ?m and a degree of polymerization (DP) of 250. The characterization of samples was performed by thermogravimetric analysis, X-ray diffraction, and scanning electron\\u000a microscopy (SEM). The

Rafael Leite de Oliveira; Hernane da Silva Barud; Rosana M. N. de Assunção; Carla da Silva Meireles; Geandre Oliveira Carvalho; Guimes Rodrigues Filho; Younes Messaddeq; Sidney José Lima Ribeiro

292

pH gradients and a mirco-pore filter at the luminal surface affect fluxes of propionic acid across guinea pig large intestine  

Microsoft Academic Search

A neutral pH microclimate had been shown at the luminal surface of the large intestine. The aim was to estimate to what extent\\u000a fluxes of propionic acid\\/propionate are affected by changes of the luminal pH when this microclimate is present, largely reduced\\u000a or absent. Fluxes of propionic acid\\/propionate (J\\u000a Pr) across epithelia from the caecum, the proximal and the distal

Roger Busche; Wolfgang von Engelhardt

2007-01-01

293

Flux Analysis of the Metabolism of Clostridium cellulolyticum Grown in Cellulose-Fed Continuous Culture on a Chemically Defined Medium under Ammonium-Limited Conditions  

Microsoft Academic Search

An investigation of cellulose degradation by the nonruminal, cellulolytic, mesophilic bacterium Clostridium cellulolyticum was performed in cellulose-fed chemostat cultures with ammonium as the growth-limiting nu- trient. At any dilution rate (D), acetate was always the main product of the catabolism, with a yield of product from substrate ranging between 37.7 and 51.5 g per mol of hexose equivalent fermented and

MICKAEL DESVAUX; HENRI PETITDEMANGE

2001-01-01

294

Fabrication of cellulose self-assemblies and high-strength ordered cellulose films.  

PubMed

Based on the formation of cellulose hydrogels in NaOH/urea aqueous solvent media, cellulose self-assembly precursor is acquired. It is proved that the water uptake capability of the cellulose hydrogels depends highly on the cross-link degree (CLD) of cellulose. With varying CLD and concentration of cellulose, a variety of morphologies of cellulose self-assemblies, including sheets with perfect morphology, high-aspect-ratio fibers, and disorganized segments and network, are formed through evaporation. Furthermore, cellulose films are fabricated by diecasting and evaporating the cellulose hydrogels, resulting in a 3D-ordered structure of closely stacking of cellulose sheets. The mechanical test indicates both tensile strength and flexibility of the cellulose films are greatly improved, which is attributed to the formation of the orderly stacking of cellulose sheets. The study is expected to lay an important foundation on the preparation of ordered and high-strength cellulose materials. PMID:25498654

Yuan, Zaiwu; Zhang, Jingjing; Jiang, Anning; Lv, Wenting; Wang, Yuewen; Geng, Hongjuan; Wang, Jin; Qin, Menghua

2015-03-01

295

Lactate and acetate production in Listeria innocua.  

PubMed

Listeria innocua NCTC 11289 was grown aerobically in continuous culture in defined media at 30 degrees C. Both acetate and lactate were produced, the proportion of acetate decreased with increasing dilution rate. Enzymatic analysis showed lactate dehydrogenase was activated 10-fold by fructose-1, 6-bisphosphate. The presence of phosphate acetyltransferase and acetate kinase but not pyruvate oxidase was detected, suggesting the sequential action of phosphate acetyltransferase and acetate kinase to produce acetate from acetyl CoA via acetylphosphate. PMID:8987454

Kelly, A F; Patchett, R A

1996-08-01

296

Emulsion electrospinning of nanocrystalline cellulose reinforced nanocomposite fibres.  

E-print Network

??Cellulose is the most abundant renewable and biodegradable natural polymer. Cellulose can release nanocrystalline cellulose (NCC). NCC is light-weight, biodegradable and strong. The strength of… (more)

Li, Yingjie

2010-01-01

297

A synthetic auxin (NAA) suppresses secondary wall cellulose synthesis and enhances elongation in cultured cotton fiber.  

PubMed

Use of a synthetic auxin (naphthalene-1-acetic acid, NAA) to start (Gossypium hirsutum) ovule/fiber cultures hindered fiber secondary wall cellulose synthesis compared with natural auxin (indole-3-acetic acid, IAA). In contrast, NAA promoted fiber elongation and ovule weight gain, which resulted in larger ovule/fiber units. To reach these conclusions, fiber and ovule growth parameters were measured and cell wall characteristics were examined microscopically. The differences in fiber from NAA and IAA culture were underpinned by changes in the expression patterns of marker genes for three fiber developmental stages (elongation, the transition stage, and secondary wall deposition), and these gene expression patterns were also analyzed quantitatively in plant-grown fiber. The results demonstrate that secondary wall cellulose synthesis: (1) is under strong transcriptional control that is influenced by auxin; and (2) must be specifically characterized in the cotton ovule/fiber culture system given the many protocol variables employed in different laboratories. PMID:19479259

Singh, Bir; Cheek, Hannah D; Haigler, Candace H

2009-07-01

298

[Conditions for forming ethanol during bioconversion of cellulose-containing raw material].  

PubMed

Several natural associations composed by thermophilic anaerobic bacteria capable of utilizing various cellulose materials at 60 +/- 2 degrees C and pH 6.0-7.0 were isolated from the sludge of Kamchatka geothermal springs. The rate of ethanol production (up to 1.7 g/l per day) and the concentration of ethanol in the medium (up to 1.2%), as well as the fermentation period (10-15 days) were determined under anaerobic conditions in the presence of cellulose, coniferous sawdust, newsprint, or paper pulp as a carbon source. Microorganisms were found that inhibited the production of ethanol. The initial pH value was found to influence both the ethanol production rate and ethanol/acetate ratio. A pH decrease from 7.0 to 5.0 led to 6.7-fold increased the ethanol production and caused a 23.8-fold increase in the ethanol/acetate ratio. PMID:11605469

Ziabreva, N V; Isakova, E P; Biriukov, V V

2001-01-01

299

Selective degradation of the cellulose I ? component in Cladophora cellulose with Trichoderma viride cellulase  

Microsoft Academic Search

We previously reported that the algal-bacterial type cellulose microfibril was more susceptible to enzymatic attack than the cotton-ramie type cellulose. In cellulose crystallite (CC) of the algal-bacterial type cellulose, the cellulose I? crystal component was more selectively degraded than the cellulose I? crystal component. The shortened CC was observed frequently in the residue of Cladophora CC. Fibrillation was observed in

Noriko Hayashi; Junji Sugiyama; Takeshi Okano; Mitsuro Ishihara

1997-01-01

300

Propionate induced effects on feed intake and blood parameters in sheep  

E-print Network

), and the jugular vein (JV). The animals were fed grass pellet diets (- 22.7 % CP). Feed was offered for 90-minPropionate induced effects on feed intake and blood parameters in sheep HGD Leuvenink EJB Bleumer, P Kruys, LJGM Bongers Department of Human and Animal Physiology, Wageningen Institute of Animal

Paris-Sud XI, Université de

301

Monitoring Amyelois transitella Males and Females with Phenyl Propionate Traps in Almonds and Pistachios  

Technology Transfer Automated Retrieval System (TEKTRAN)

Attractants that lure both sexes and both mated and unmated females have been used to monitor the effect of mating disruption on the mating status and relative abundance of lepidopteran females. For the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), phenyl propionate attra...

302

Salmonella typhimurium LT2 Catabolizes Propionate via the 2-Methylcitric Acid Cycle  

PubMed Central

We previously identified the prpBCDE operon, which encodes catabolic functions required for propionate catabolism in Salmonella typhimurium. Results from 13C-labeling experiments have identified the route of propionate breakdown and determined the biochemical role of each Prp enzyme in this pathway. The identification of catabolites accumulating in wild-type and mutant strains was consistent with propionate breakdown through the 2-methylcitric acid cycle. Our experiments demonstrate that the ?-carbon of propionate is oxidized to yield pyruvate. The reactions are catalyzed by propionyl coenzyme A (propionyl-CoA) synthetase (PrpE), 2-methylcitrate synthase (PrpC), 2-methylcitrate dehydratase (probably PrpD), 2-methylisocitrate hydratase (probably PrpD), and 2-methylisocitrate lyase (PrpB). In support of this conclusion, the PrpC enzyme was purified to homogeneity and shown to have 2-methylcitrate synthase activity in vitro. 1H nuclear magnetic resonance spectroscopy and negative-ion electrospray ionization mass spectrometry identified 2-methylcitrate as the product of the PrpC reaction. Although PrpC could use acetyl-CoA as a substrate to synthesize citrate, kinetic analysis demonstrated that propionyl-CoA is the preferred substrate. PMID:10482501

Horswill, Alexander R.; Escalante-Semerena, Jorge C.

1999-01-01

303

ANTIANDROGENIC EFFECTS OF VINCLOZOLIN ON MALE RATS ARE PARTIALLY ATTENUATED BY TESTOSTERONE PROPIONATE  

EPA Science Inventory

ANTIANDROGENIC EFFECTS OF VINCLOZOLIN ON MALE RATS ARE PARTIALLY ATTENUATED BY TESTOSTERONE PROPIONATE Cynthia Wolf1,2 , Joe Ostby1, Jonathan Furr 1, Gerald A. LeBlanc2, and L. Earl Gray, Jr.1 1 US Environmental Protection Agency, NHEERL, RTD, RTP, NC 27711, 2 Departmen...

304

Cellulose granulomatosis of the lungs  

Microsoft Academic Search

.   Chest radiographs and high-resolution chest CT scans were performed in a 30-year-old man with a history of intravenous drug\\u000a abuse and diffuse micronodular infiltrates. Transbronchial biopsy gave a diagnosis of cellulose granulomatosis of the lung.\\u000a Cellulose granulomatosis should be considered in the differential diagnosis of pulmonary interstitial disease, especially\\u000a in the setting of intravenous drug abuse.

M. J. Diaz-Ruiz; X. Gallardo; E. Castañer; J. M. Mata; J. Catalá; J. C. Ferreres

1999-01-01

305

Wetting dynamics of alkyl ketene dimer on cellulosic model surfaces  

SciTech Connect

The dynamic wetting of a commercial alkyl ketene dimer (AKD) wax was measured on model cellulosic surfaces. The variables investigated were temperature and the surface composition. The model surfaces consisted of cellulose and cellulose acetate films as well as glass. These surfaces are smooth by industrial standards but not on a molecular level. The objective of the study was to predict the extent of AKD wetting during the time frame of papermaking. For smooth surfaces, AKD particles wet but do not spread on the hydrophilic surfaces investigated. AKD wetting proceeds from the balance of the interfacial forces with the viscous dissipation. The effect of gravity can be neglected for papermaking conditions. The Hoffman-Tanner equation modified for partial wetting provided a very good fit of the dynamic wetting. The slope of the graph is a function of temperature but not of the solid surface composition. Maslyiah's model also fits the experimental results well, but with a physically unrealistic value of the fitting parameter. For partial wetting, the complex but rigorous Cox equation is recommended to estimate the slip length over macroscopic wetting dimensions.

Garnier, G.; Bertin, M.; Smrckova, M.

1999-10-26

306

Surface modification of cellulose nanocrystals  

NASA Astrophysics Data System (ADS)

Chemical modification of cellulose nanocrystals is an increasingly popular topic in the literature. This review analyses the type of cellulose nanocrystal modification reactions that have been published in the literature thus far and looks at the steps that have been taken towards analysing the products of the nanocrystal modifications. The main categories of reactions carried out on cellulose nanocrystals are oxidations, esterifications, amidations, carbamations and etherifications. More recently nucleophilic substitutions have been used to introduce more complex functionality to cellulose nanocrystals. Multi-step modifications are also considered. This review emphasizes quantification of modification at the nanocrystal surface in terms of degree of substitution and the validity of conclusions drawn from different analysis techniques in this area. The mechanisms of the modification reactions are presented and considered with respect to the effect on the outcome of the reactions. While great strides have been made in the quality of analytical data published in the field of cellulose nanocrystal modification, there is still vast scope for improvement, both in data quality and the quality of analysis of data. Given the difficulty of surface analysis, cross-checking of results from different analysis techniques is fundamental for the development of reliable cellulose nanocrystal modification techniques.

Eyley, Samuel; Thielemans, Wim

2014-06-01

307

Visualization of biomass solubilization and cellulose regeneration during ionic liquid pretreatment of switchgrass  

Microsoft Academic Search

Auto-fluorescent mapping of plant cell walls was used to visualize cellulose and lignin in pristine switchgrass (Panicum virgatum) stems to determine the mechanisms of biomass dissolution during ionic liquid pretreatment. The addition of ground switchgrass to the ionic liquid 1-n-ethyl-3-methylimidazolium acetate resulted in the disruption and solubilization of the plant cell wall at mild temperatures. Swelling of the plant cell

Seema Singh; Blake A. Simmons; Kenneth P. Vogel

2009-01-01

308

High-flux Thin-film Nanofibrous Composite Ultrafiltration Membranes Containing Cellulose Barrier Layer  

Microsoft Academic Search

A novel class of thin-film nanofibrous composite (TFNC) membrane consisting of a cellulose barrier layer, a nanofibrous mid-layer scaffold, and a melt-blown non-woven substrate was successfully fabricated and tested as an ultrafiltration (UF) filter to separate an emulsified oil and water mixture, a model bilge water for on-board ship bilge water purification. Two ionic liquids: 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate,

Hongyang Ma; Kyunghwan Yoon; Lixia Rong; Yimin Mao; Zhirui Mo; Dufei Fang; Zachary Hollander; Joseph Gaiteri; Benjamin S. Hsiao; Benjamin Chu

2010-01-01

309

Co-electrospun poly(?-caprolactone)/cellulose nanofibers-fabrication and characterization.  

PubMed

We report fabrication of poly (?-caprolactone) (PCL)/cellulose (CEL) nanofiber blends via co-electrospinning for the possible use as biofilters and biosensor strips. Five different ratios of PCL to CEL were fabricated to investigate the wicking behavior. The cellulose acetate (CA) was taken as precursor to make cellulose nanofibers. Double nozzles were employed for jetting constituent polymers toward collector drum independently and resultant nanofibers webs were deacetylated in aqueous alkaline solution to convert CA into CEL as confirmed by FTIR spectra. FTIR further revealed that there is no effect of deacetylation on PCL nanofiber. The morphology of each blend webs under SEM showed uniform and bead-free nanofibers. Wicking behavior for five different ratios of PCL/CEL suggested that increasing CEL ratio in the blend enhanced the wicking front height; however, X-ray diffraction patterns of PCL/CEL showed a slight decrease in crystallinity. PMID:25439909

Ahmed, Farooq; Saleemi, Sidra; Khatri, Zeeshan; Abro, Muhammad Ishaque; Kim, Ick-Soo

2015-01-22

310

Nanomechanics of cellulose crystals and cellulose-based polymer composites  

NASA Astrophysics Data System (ADS)

Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on their nanomechanical properties were reported. Then the effect of CNC surface modification on the mechanical properties was studied and correlated to the crystalline structure of these materials.

Pakzad, Anahita

311

Batch- and continuous propionic acid production from glycerol using free and immobilized cells of Propionibacterium acidipropionici.  

PubMed

Propionic acid production from glycerol was studied using Propionibacterium acidipropionici DSM 4900 cells immobilized on polyethylenimine-treated Poraver (PEI-Poraver) and Luffa (PEI-Luffa), respectively. Using PEI-Luffa, the average productivity, yield and concentration of propionic acid from 40 g L(-1) glycerol were 0.29 g L(-1) h(-1), 0.74 mol(PA) mol(Gly)(-1) and 20 g L(-1), respectively, after four consecutive recycle-batches. PEI-Poraver supported attachment of 31 times higher amounts of cells than PEI-Luffa and produced 20, 28 and 35 g L(-1) propionic acid from 40, 65 and 85 g L(-1) glycerol, respectively (0.61 mol(PA) mol(Gly)(-1)). The corresponding production rates were 0.86, 0.43 and 0.35 g L(-1) h(-1), which are the highest reported from glycerol via batch or fed-batch fermentations for equivalent propionic acid concentrations. Using a continuous mode of operation at a dilution rate of 0.1 h(-1), cell washout was observed in the bioreactor with free cells; however, propionic acid productivity, yield and concentration were 1.40 g L(-1) h(-1), 0.86 mol(PA) mol(Gly)(-1), and 15 g L(-1), respectively, using immobilized cells in the PEI-Poraver bioreactor. The choice of the immobilization matrix can thus significantly influence the fermentation efficiency and profile. The bioreactor using cells immobilized on PEI-Poraver allowed the fermentation of higher glycerol concentrations and provided stable and higher fermentation rates than that using free cells or the cells immobilized on PEI-Luffa. PMID:22728152

Dishisha, Tarek; Alvarez, Maria Teresa; Hatti-Kaul, Rajni

2012-08-01

312

Role of the methylcitrate cycle in propionate metabolism and detoxification in Mycobacterium smegmatis.  

PubMed

Catabolism of odd-chain-length fatty acids yields acetyl-CoA and propionyl-CoA. A common pathway of propionyl-CoA metabolism in micro-organisms is the methylcitrate cycle, which includes the dedicated enzymes methylcitrate synthase (MCS), methylcitrate dehydratase (MCD) and methylisocitrate lyase (MCL). The methylcitrate cycle is essential for propionate metabolism in Mycobacterium tuberculosis. Unusually, M. tuberculosis lacks an MCL orthologue and this activity is provided instead by two isoforms of the glyoxylate cycle enzyme isocitrate lyase (ICL1 and ICL2). These bifunctional (ICL/MCL) enzymes are jointly required for propionate metabolism and for growth and survival in mice. In contrast, the non-pathogenic species Mycobacterium smegmatis encodes a canonical MCL enzyme in addition to ICL1 and ICL2. The M. smegmatis gene encoding MCL (prpB) is clustered with genes encoding MCS (prpC) and MCD (prpD). Here we show that deletion of the M. smegmatis prpDBC locus reduced but did not eliminate MCL activity in cell-free extracts. The residual MCL activity was abolished by deletion of icl1 and icl2 in the DeltaprpDBC background, suggesting that these genes encode bifunctional ICL/MCL enzymes. A DeltaprpB Deltaicl1 Deltaicl2 mutant was unable to grow on propionate or mixtures of propionate and glucose. We hypothesize that incomplete propionyl-CoA metabolism might cause toxic metabolites to accumulate. Consistent with this idea, deletion of prpC and prpD in the DeltaprpB Deltaicl1 Deltaicl2 background paradoxically restored growth on propionate-containing media. These observations suggest that the marked attenuation of ICL1/ICL2-deficient M. tuberculosis in mice could be due to the accumulation of toxic propionyl-CoA metabolites, rather than inability to utilize fatty acids per se. PMID:18048912

Upton, Anna M; McKinney, John D

2007-12-01

313

Kinetic analysis and pH-shift control strategy for propionic acid production with Propionibacterium Freudenreichii CCTCC M207015.  

PubMed

The production of propionic acid by Propionibacterium freudenreichii CCTCC M207015 was investigated in a 7.5-l stirred-tank fermentor. Batch fermentations by P. freudenreichii CCTCC M207015 at various pH values ranging from 5.5 to 7.0 were studied. Based on the analysis of the time course of specific cell growth rate (mu (x)) and specific propionic acid formation rate (mu (p)), a two-stage pH-shift control strategy was proposed. At first 48 h, pH was controlled at 6.5 to obtain the maximal mu (x), subsequently pH 6.0 was used to maintain high mu (p) to enhance the production of propionic acid. By applying this pH-shift control strategy in propionic acid fermentation, the maximal propionic acid and glucose conversion efficiency had a significant improvement and reached 19.21 g/l and 48.03%, respectively, compared with those of constant pH operation (14.58 g/l and 36.45%). Fed-batch fermentation with pH-shift control strategy was also applied to produce propionic acid; the maximal propionic acid yield and glucose conversion efficiency reached 25.23 g/l and 47.76%, respectively. PMID:18626579

Feng, Xiaohai; Xu, Hong; Yao, Jun; Li, Sha; Zhu, Hongyang; Ouyang, Pingkai

2010-01-01

314

Construction and evaluation of a genetic construct for specific detection and measurement of propionate by whole-cell bacteria.  

PubMed

Anaerobic digestion is a microbiological technology that converts biomass wastes into biogas, achieving both waste treatment and bioenergy production. Accumulation of volatile fatty acids (VFA) during acidogenesis, particularly propionate, often causes upset or failure of digesters. Early detection and monitoring of propionate concentration in digesters allow for just-in-time interventions to prevent irreversible costly process breakdown. In an attempt to develop a rapid method of measuring propionate concentration and bioavailability, we constructed a genetic construct for specific detection of bioavailable propionate. The genetic construct was constructed by transcriptional fusion of the regulatory gene (prpR) and the promoter of the prp operon (PprpB ) of Escherichia coli W3110 with the reporter gene cassette luxCDABE. When the genetic construct was carried on a plasmid and transformed into E. coli (referred to as plasmid-based biosensor), it resulted in stronger emission of luminescence than when it was inserted into the chromosome of E. coli (referred to as chromosome-based biosensor). The biosensor responded specifically to propionate. The luminescence signal increased linearly with increasing concentration of propionate from 1 to 10?mM. The utility of the biosensor was evaluated using samples collected from anaerobic digesters. Once instrumented in future studies, the whole-cell bacterial biosensor developed in this study may provide an alternative technology for real-time detection and measurement of propionate in digesters. Biotechnol. Bioeng. 2015;112: 280-287. © 2014 Wiley Periodicals, Inc. PMID:25131426

Li, Yueh-Fen; Yu, Zhongtang

2015-02-01

315

Acetate fuels the cancer engine.  

PubMed

Cancer cells have distinctive nutrient demands to fuel growth and proliferation, including the disproportionate use of glucose, glutamine, and fatty acids. Comerford et al. and Mashimo et al. now demonstrate that several types of cancer are avid consumers of acetate, which facilitates macromolecular biosynthesis and histone modification. PMID:25525870

Lyssiotis, Costas A; Cantley, Lewis C

2014-12-18

316

Desmopressin Acetate in Intracranial Haemorrhage  

PubMed Central

Introduction. The secondary increase in the size of intracranial haematomas as a result of spontaneous haemorrhage or trauma is of particular relevance in the event of prior intake of platelet aggregation inhibitors. We describe the effect of desmopressin acetate as a means of temporarily stabilising the platelet function. Patients and Methods. The platelet function was analysed in 10 patients who had received single (N = 4) or multiple (N = 6) doses of acetylsalicylic acid and 3 patients (control group) who had not taken acetylsalicylic acid. All subjects had suffered intracranial haemorrhage. Analysis was performed before, half an hour and three hours after administration of desmopressin acetate. Statistical analysis was performed by applying a level of significance of P ? 0.05. Results. (1) Platelet function returned to normal 30 minutes after administration of desmopressin acetate. (2) The platelet function worsened again after three hours. (3) There were no complications related to electrolytes or fluid balance. Conclusion. Desmopressin acetate can stabilise the platelet function in neurosurgical patients who have received acetylsalicylic acid prior to surgery without causing transfusion-related side effects or a loss of time. The effect is, however, limited and influenced by the frequency of drug intake. Further controls are needed in neurosurgical patients. PMID:25610644

Kapapa, Thomas; Röhrer, Stefan; Struve, Sabine; Petscher, Matthias; König, Ralph; Wirtz, Christian Rainer; Woischneck, Dieter

2014-01-01

317

Ionic liquid processing of cellulose.  

PubMed

Utilization of natural polymers has attracted increasing attention because of the consumption and over-exploitation of non-renewable resources, such as coal and oil. The development of green processing of cellulose, the most abundant biorenewable material on Earth, is urgent from the viewpoints of both sustainability and environmental protection. The discovery of the dissolution of cellulose in ionic liquids (ILs, salts which melt below 100 °C) provides new opportunities for the processing of this biopolymer, however, many fundamental and practical questions need to be answered in order to determine if this will ultimately be a green or sustainable strategy. In this critical review, the open fundamental questions regarding the interactions of cellulose with both the IL cations and anions in the dissolution process are discussed. Investigations have shown that the interactions between the anion and cellulose play an important role in the solvation of cellulose, however, opinions on the role of the cation are conflicting. Some researchers have concluded that the cations are hydrogen bonding to this biopolymer, while others suggest they are not. Our review of the available data has led us to urge the use of more chemical units of solubility, such as 'g cellulose per mole of IL' or 'mol IL per mol hydroxyl in cellulose' to provide more consistency in data reporting and more insight into the dissolution mechanism. This review will also assess the greenness and sustainability of IL processing of biomass, where it would seem that the choices of cation and anion are critical not only to the science of the dissolution, but to the ultimate 'greenness' of any process (142 references). PMID:22266483

Wang, Hui; Gurau, Gabriela; Rogers, Robin D

2012-02-21

318

Gravity effects on cellulose assembly  

NASA Technical Reports Server (NTRS)

The effect of microgravity on cellulose synthesis using the model system of Acetobacter xylinum was the subject of recent investigations using The National Aeronautics and Space Administration's Reduced Gravity Laboratory, a modified KC-135 aircraft designed to produce 20 sec of microgravity during the top of a parabolic dive. Approximately 40 parabolas were executed per mission, and a period of 2 x g was integral to the pullout phase of each parabola. Cellulose biosynthesis was initiated on agar surfaces, liquid growth medium, and buffered glucose during parabolic flight and terminated with 2.0% sodium azide or 50.0% ethanol. While careful ground and in-flight controls indicated normal, compact ribbons of microbial cellulose, data from five different flights consistently showed that during progression into the parabola regime, the cellulose ribbons became splayed. This observation suggests that some element of the parabola (the 20 sec microgravity phase, the 20 sec 2 x g phase, or a combination of both) was responsible for this effect. Presumably the cellulose I alpha crystalline polymorph normally is produced under strain, and the microgravity/hypergravity combination may relieve this stress to produce splayed ribbons. An in-flight video microscopy analysis of bacterial motions during a parabolic series demonstrated that the bacteria continue to synthesize cellulose during all phases of the parabolic series. Thus, the splaying may be a reflection of a more subtle alteration such as reduction of intermicrofibrillar hydrogen bonding. Long-term microgravity exposures during spaceflight will be necessary to fully understand the cellulose alterations from the short-term microgravity experiments.

Brown, R. M. Jr; Kudlicka, K.; Cousins, S. K.; Nagy, R.; Brown RM, J. r. (Principal Investigator)

1992-01-01

319

Geobacter sulfurreducens sp. nov., a hydrogen- and acetate-oxidizing dissimilatory metal-reducing microorganism.  

PubMed Central

A dissimilatory metal- and sulfur-reducing microorganism was isolated from surface sediments of a hydrocarbon-contaminated ditch in Norman, Okla. The isolate, which was designated strain PCA, was an obligately anaerobic, nonfermentative nonmotile, gram-negative rod. PCA grew in a defined medium with acetate as an electron donor and ferric PPi, ferric oxyhydroxide, ferric citrate, elemental sulfur, Co(III)-EDTA, fumarate, or malate as the sole electron acceptor. PCA also coupled the oxidation of hydrogen to the reduction of Fe(III) but did not reduce Fe(III) with sulfur, glucose, lactate, fumarate, propionate, butyrate, isobutyrate, isovalerate, succinate, yeast extract, phenol, benzoate, ethanol, propanol, or butanol as an electron donor. PCA did not reduce oxygen, Mn(IV), U(VI), nitrate, sulfate, sulfite, or thiosulfate with acetate as the electron donor. Cell suspensions of PCA exhibited dithionite-reduced minus air-oxidized difference spectra which were characteristic of c-type cytochromes. Phylogenetic analysis of the 16S rRNA sequence placed PCA in the delta subgroup of the proteobacteria. Its closest known relative is Geobacter metallireducens. The ability to utilize either hydrogen or acetate as the sole electron donor for Fe(III) reduction makes strain PCA a unique addition to the relatively small group of respiratory metal-reducing microorganisms available in pure culture. A new species name, Geobacter sulfurreducens, is proposed. Images PMID:7527204

Caccavo, F; Lonergan, D J; Lovley, D R; Davis, M; Stolz, J F; McInerney, M J

1994-01-01

320

Cellulose hydrogels prepared from micron-sized bamboo cellulose fibers.  

PubMed

We demonstrated for the first time that dimensionally stable hydrogels could be obtained from bamboo pulp fibers through dialysis against distilled water followed by a short time of ultrasonic treatment. Micron-sized short fibers rather than cellulose nanofibrils constituted the majority of fibers in the hydrogels. During the pulping process with HNO3 and KClO3, carboxylic groups could be introduced to cellulose due to the mild oxidation of hydroxyl groups. When presented in aqueous NaOH, the carboxylic groups could be converted into their sodium salt form. The subsequent dialysis treatment against water made the negatively charged COO(-) groups extensively exposed. The negatively charged cellulose fibers could induce considerable electrostatic repulsion between them, which was discovered to govern the formation of hydrogels. In addition, it was revealed that homogeneous hydrogels could be formed when the pH was at 7, 9 and 11. However, when salt was added, no dimensionally stable hydrogel was obtained. PMID:25263877

Zhang, Xiaofang; Wang, Yaru; Lu, Canhui; Zhang, Wei

2014-12-19

321

Inactivation of shiga toxin-producing Escherichia coli (STEC) and degradation and removal of cellulose from STEC surfaces by using selected enzymatic and chemical treatments.  

PubMed

Some Shiga toxin-producing Escherichia coli (STEC) strains produce extracellular cellulose, a long polymer of glucose with ?-1-4 glycosidic bonds. This study evaluated the efficacies of selected enzymatic and chemical treatments in inactivating STEC and degrading/removing the cellulose on STEC surfaces. Six cellulose-producing STEC strains were treated with cellulase (0.51 to 3.83 U/15 ml), acetic and lactic acids (2 and 4%), as well as an acidic and alkaline sanitizer (manufacturers' recommended concentrations) under appropriate conditions. Following each treatment, residual amounts of cellulose and surviving populations of STEC were determined. Treatments with acetic and lactic acids significantly (P < 0.05) reduced the populations of STEC, and those with lactic acid also significantly decreased the amounts of cellulose on STEC. The residual amounts of cellulose on STEC positively correlated to the surviving populations of STEC after the treatments with the organic acids (r = 0.64 to 0.94), and the significance of the correlations ranged from 83 to 99%. Treatments with cellulase and the sanitizers both degraded cellulose. However, treatments with cellulase had no influence on the fate of STEC, and those with the sanitizers reduced STEC cell populations to undetectable levels. Thus, the correlations between the residual amounts of cellulose and the surviving populations of STEC caused by these two treatments were not observed. The results suggest that the selected enzymatic and chemical agents degraded and removed the cellulose on STEC surfaces, and the treatments with organic acids and sanitizers also inactivated STEC cells. The amounts of cellulose produced by STEC strains appear to affect their susceptibilities to certain sanitizing treatments. PMID:22003030

Park, Yoen Ju; Chen, Jinru

2011-12-01

322

Inactivation of Shiga Toxin-Producing Escherichia coli (STEC) and Degradation and Removal of Cellulose from STEC Surfaces by Using Selected Enzymatic and Chemical Treatments?  

PubMed Central

Some Shiga toxin-producing Escherichia coli (STEC) strains produce extracellular cellulose, a long polymer of glucose with ?-1-4 glycosidic bonds. This study evaluated the efficacies of selected enzymatic and chemical treatments in inactivating STEC and degrading/removing the cellulose on STEC surfaces. Six cellulose-producing STEC strains were treated with cellulase (0.51 to 3.83 U/15 ml), acetic and lactic acids (2 and 4%), as well as an acidic and alkaline sanitizer (manufacturers' recommended concentrations) under appropriate conditions. Following each treatment, residual amounts of cellulose and surviving populations of STEC were determined. Treatments with acetic and lactic acids significantly (P < 0.05) reduced the populations of STEC, and those with lactic acid also significantly decreased the amounts of cellulose on STEC. The residual amounts of cellulose on STEC positively correlated to the surviving populations of STEC after the treatments with the organic acids (r = 0.64 to 0.94), and the significance of the correlations ranged from 83 to 99%. Treatments with cellulase and the sanitizers both degraded cellulose. However, treatments with cellulase had no influence on the fate of STEC, and those with the sanitizers reduced STEC cell populations to undetectable levels. Thus, the correlations between the residual amounts of cellulose and the surviving populations of STEC caused by these two treatments were not observed. The results suggest that the selected enzymatic and chemical agents degraded and removed the cellulose on STEC surfaces, and the treatments with organic acids and sanitizers also inactivated STEC cells. The amounts of cellulose produced by STEC strains appear to affect their susceptibilities to certain sanitizing treatments. PMID:22003030

Park, Yoen Ju; Chen, Jinru

2011-01-01

323

Improving fermentation performance of recombinant Zymomonas in acetic acid-containing media.  

PubMed

In the production of ethanol from lignocellulosic biomass, the hydrolysis of the acetylated pentosans in hemicellulose during pretreatment produces acetic acid in the prehydrolysate. The National Renewable Energy Laboratory (NREL) is currently investigating a simultaneous saccharification and cofermentation (SSCF) process that uses a proprietary metabolically engineered strain of Zymomonas mobilis that can coferment glucose and xylose. Acetic acid toxicity represents a major limitation to bioconversion, and cost-effective means of reducing the inhibitory effects of acetic acid represent an opportunity for significant increased productivity and reduced cost of producing fermentation fuel ethanol from biomass. In this study, the fermentation performance of recombinant Z. mobilis 39676:pZB4L, using a synthetic hardwood prehydrolysate containing 1% (w/v) yeast extract, 0.2% KH2PO4, 4% (w/v) xylose, and 0.8% (w/v) glucose, with varying amounts of acetic acid was examine. To minimize the concentration of the inhibitory undissociated form of acetic acid, the pH was controlled at 6.0. The final cell mass concentration decreased linearly with increasing level of acetic acid over the range 0-0.75% (w/v), with a 50% reduction at about 0.5% (w/v) acetic acid. The conversion efficiency was relatively unaffected, decreasing from 98 to 92%. In the absence of acetic acid, batch fermentations were complete at 24 h. In a batch fermentation with 0.75% (w/v) acetic acid, about two-thirds of the xylose was not metabolized after 48 h. In batch fermentations with 0.75% (w/v) acetic acid, increasing the initial glucose concentration did not have an enhancing effect on the rate of xylose fermentation. However, nearly complete xylose fermentation was achieved in 48h when the bioreactor was fed glucose. In the fed-batch system, the rate of glucose feeding (0.5 g/h) was designed to simulate the rate of cellulolytic digestion that had been observed in a modeled SSCF process with recombinant Zymomonas. In the absence of acetic acid, this rate of glucose feeding did not inhibit xylose utilization. It is concluded that the inhibitory effect of acetic acid on xylose utilization in the SSCF biomass-to-ethanol process will be partially ameliorated because of the simultaneous saccharification of the cellulose. PMID:9627380

Lawford, H G; Rousseau, J D

1998-01-01

324

Isolation of developing secondary xylem specific cellulose synthase genes and their expression profiles during hormone signalling in Eucalyptus tereticornis.  

PubMed

Cellulose synthases (CesA) represent a group of ?-1, 4 glycosyl transferases involved in cellulose biosynthesis. Recent reports in higher plants have revealed that two groups of CesA gene families exist, which are associated with either primary or secondary cell wall deposition. The present study aimed at identifying developing secondary xylem specific cellulose synthase genes from Eucalyptus tereticornis, a species predominantly used in paper and pulp industries in the tropics. The differential expression analysis of the three EtCesA genes using qRT-PCR revealed 49 to 87 fold relative expression in developing secondary xylem tissues. Three full length gene sequences of EtCesA1, EtCesA2 and EtCesA3 were isolated with the size of 2940, 3114 and 3123 bp, respectively. Phytohormone regulation of all three EtCesA genes were studied by exogenous application of gibberellic acid, naphthalene acetic acid, indole acetic acid and 2, 4-epibrassinolide in internode tissues derived from three-month-old rooted cuttings. All three EtCesA transcripts were upregulated by indole acetic acid and gibberellic acid. This study demonstrates that the increased cellulose deposition in the secondary wood induced by hormones can be attributed to the upregulation of xylem specific CesAs. PMID:25189235

Sundari, Balachandran Karpaga Raja; Dasgupta, Modhumita Ghosh

2014-08-01

325

Rheology of lyocell solutions from different cellulosic sources and development of regenerated cellulosic microfibers  

Microsoft Academic Search

The primary goals of the study were to develop manufactured cellulosic fibers and microfibers from wood pulps as well as from lignocellulosic agricultural by-products and to investigate alternative cellulosic sources as raw materials for lyocell solutions. A protocol was developed for the lyocell preparation from different cellulose sources. The cellulose sources included commercial dissolving pulps, commercial bleached hardwood, unbleached hardwood,

Zuopan Li

2003-01-01

326

Plant cellulose synthesis: CESA proteins crossing kingdoms.  

PubMed

Cellulose is a biopolymer of considerable economic importance. It is synthesised by the cellulose synthase complex (CSC) in species ranging from bacteria to higher plants. Enormous progress in our understanding of bacterial cellulose synthesis has come with the recent publication of both the crystal structure and biochemical characterisation of a purified complex able to synthesis cellulose in vitro. A model structure of a plant CESA protein suggests considerable similarity between the bacterial and plant cellulose synthesis. In this review article we will cover current knowledge of how plant CESA proteins synthesise cellulose. In particular the focus will be on the lessons learned from the recent work on the catalytic mechanism and the implications that new data on cellulose structure has for the assembly of CESA proteins into the large complex that synthesis plant cellulose microfibrils. PMID:25104231

Kumar, Manoj; Turner, Simon

2014-08-01

327

Cellulose Modifications and Their Future Application  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this poster, we will describe the synthesis and structural characterizations of a benzyl-, nitrobenzyl-, and aminobenzyl celluloses. Nitrobenzyl- and aminobenzyl cellulose derivatives are synthesized by etherification process in lithium chloride/N,N-dimethylacetamide homogeneous solution. Nitrobe...

328

DNA stickers promote polymer adsorption onto cellulose.  

PubMed

Adsorption of oligonucleotides onto model cellulose surfaces was investigated by comparing the Boese and Breaker's cellulose binding oligonucleotide (CBO) with a nonspecific oligonucleotide control (NSO). Measurements using the quartz crystal microbalance with dissipation technique confirmed that CBO adsorbed onto cellulose more than NSO, particularly at high ionic strengths (100 mM CaCl(2)). CBO showed a higher maximum adsorption on nanofibrillated and nanocrystalline cellulose than on regenerated cellulose, indicating a preference for the native cellulose I crystal structure under conditions that favored specific adsorption over calcium-mediated electrostatically driven adsorption. In addition, an anionic polyacrylamide (A-PAM) with grafted CBO also adsorbed onto the surface of cellulose in CaCl(2), whereas the unmodified A-PAM did not. This work shows that CBO performs as a "sticker", facilitating the adsorption of polyacrylamide onto cellulose, even under high ionic strength conditions where the adsorption of conventional polyelectrolytes is inhibited. PMID:22954359

Sato, Teruaki; Ali, Md Monsur; Pelton, Robert; Cranston, Emily D

2012-10-01

329

Development of nonflammable cellulosic foams  

NASA Technical Reports Server (NTRS)

The development of a moldable cellulosic foam for use in Skylab instrument storage cushions is considered. Requirements include density of 10 lb cu ft or less, minimal friability with normal handling, and nonflammability in an atmosphere of 70 percent oxygen and 30 percent nitrogen at 6.2 psia. A study of halogenated foam components was made, including more highly chlorinated binders, halogen-containing additives, and halogenation of the cellulose. The immediate objective was to reduce the density of the foam through reduction in inorganic phosphate without sacrificing flame-retarding properties of the foams. The use of frothing techniques was investigated, with particular emphasis on a urea-formaldehyde foam. Halogen-containing flame retardants were deemphasized in favor of inorganic salts and the preparation of phosphate and sulphate esters of cellulose. Utilization of foam products for civilian applications was also considered.

Luttinger, M.

1972-01-01

330

Structural characterization of cellulose with enzymatic treatment  

NASA Astrophysics Data System (ADS)

Different cellulosic materials were treated with different extraceller microbial enzymes. Changes in structure and properties of the cellulose caused by enzymatic treatment depend on the composition, the type of enzyme and the type of cellulosic materials. Both endoglucanase and crude cellulase have pronounced effects on the degree of polymerization and the structure of cellulose. The variation of supramolecular structure was found to wide variations in conformation caused by the change of the hydrogen bonding energy.

Cao, Yu; Tan, Huimin

2004-11-01

331

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2012 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2012-04-01

332

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2014 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2014-04-01

333

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2013-04-01

334

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2011 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2011-04-01

335

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2010 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2010-04-01

336

Cellulose fermentation by a rumen anaerobic fungus in both the absence and the presence of rumen methanogens.  

PubMed

The fermentation of cellulose by an ovine rumen anaerobic fungus in the absence and presence of rumen methanogens is described. In the monoculture, moles of product as a percentage of the moles of hexose fermented were: acetate, 72.7; carbon dioxide, 37.6; formate, 83.1; ethanol, 37.4; lactate, 67.0; and hydrogen, 35.3. In the coculture, acetate was the major product (134.7%), and carbon dioxide increased (88.7%). Lactate and ethanol production decreased to 2.9 and 19%, respectively, little formate was detected (1%), and hydrogen did not accumulate. Substantial amounts of methane were produced in the coculture (58.7%). Studies with [2-C]acetate indicated that acetate was not a precursor of methane. The demonstration of cellulose fermentation by a fungus extends the range of known rumen organisms capable of participating in cellulose digestion and provides further support for a role of anaerobic fungi in rumen fiber digestion. The effect of the methanogens on the pattern of fermentation is interpreted as a shift in flow of electrons away from electron sink products to methane via hydrogen. The study provides a new example of intermicrobial hydrogen transfer and the first demonstration of hydrogen formation by a fungus. PMID:16345902

Bauchop, T; Mountfort, D O

1981-12-01

337

Acetate kinase activity in mycoplasmas.  

PubMed

Acetate kinase activity was assayed in 13 mycoplasmas. Nine species exhibited the enzymic activity in the direction of either synthesis of acetylphosphate or adenosine triphosphate. On the other hand Mycoplasma orale, Mycoplasma arthritidis, Ureaplasma urealyticum (10 serotypes), and two strains of Anaeroplasma species exhibited only minimal levels of the enzymic activity. In these four species, the enzyme does not seem to play a key role in adenosine triphosphate formation. PMID:6263869

Muhlrad, A; Peleg, I; Robertson, J A; Robinson, I M; Kahane, I

1981-07-01

338

Effects of ruminal protozoa on cellulose degradation and the growth of an anaerobic ruminal fungus, Piromyces sp. strain OTS1, in vitro.  

PubMed Central

An anaerobic rumen fungus, Piromyces sp. strain OTS1, was incubated in the presence or absence of a mixed, A-type, protozoal population obtained from a goat, in a medium containing filter paper cellulose as energy source and antibiotics to suppress bacterial growth. Fermentation end products, cellulose degradation, and chitin as an indicator of fungal biomass were examined. In the presence of protozoa, total volatile fatty acids, notably propionate and butyrate, increased, and lactate decreased. In fungus-protozoan coincubations, formate was not detected at the end of the experiment and the amount of reducing sugars remained low throughout the incubation period. The fungal growth in the coincubations was negatively affected. While protozoal predation on zoospores was one mechanism of inhibition, mature fungal cells were also affected. Total cellulose degradation was greater in fungal monocultures, but the amount of cellulose degraded per unit of fungal biomass was 25% larger in the coincubations. The negative effects that the protozoal predatory activity had on the fungal growth and subsequently on the amount of cellulose degraded by Piromyces sp. strain OTS1 were partially attenuated by the protozoal fibrolytic activity or by an enhanced fungal activity due to a more favorable environment. PMID:7986044

Morgavi, D P; Sakurada, M; Mizokami, M; Tomita, Y; Onodera, R

1994-01-01

339

Crosslinking of platelet glycoprotein Ib by N-succinimidyl(4-azidophenyldithio)propionate and 3,3'-dithiobis(sulfosuccinimidyl propionate).  

PubMed

To examine the relationship between glycoprotein Ib and other proteins in the platelet membrane and the interaction of this protein with thrombin, platelets were crosslinked by two cleavable reagents, SADP (N-succinimidyl(4-azidophenyldithio)propionate) and DTSSP (3,3'-dithiobis(sulfosuccinimidyl propionate]. Two-dimensional, unreduced-reduced sodium dodecyl sulphate (SDS)-polyacrylamide electrophoresis and staining by silver or wheat germ agglutinin-conjugated peroxidase, after protein transfer to nitrocellulose, demonstrated that SADP intramolecularly crosslinked glycoprotein Ib and formed intermolecular complexes of glycorprotein IIb and some high molecular weight proteins. DTSSP intermolecularly crosslinked glycoprotein Ib, glycoprotein IIb, and other high molecular weight proteins. With a low concentration of 125I-labeled TLCK-thrombin (6 nM), crosslinking with SADP yielded a 200 000 Da complex containing radioactive-labeled thrombin, and high TLCK-thrombin concentration (0.1 microM) gave the complex and a 167 000 band. alpha- and TLCK-thrombin crosslinking with DTSSP also yielded the 200 000 complex formed by reaction with SADP or DTSSP was markedly reduced by preincubation of platelets with excess unlabeled TLCK-thrombin and had a pI similar to glycoprotein Ib. These results suggest that glycoprotein Ib is one of the proteins composing the high affinity receptor for thrombin. PMID:6228257

Jung, S M; Moroi, M

1983-12-13

340

Millimeterwave rotational spectrum and theoretical calculations of cis-propionic acid  

NASA Astrophysics Data System (ADS)

The millimeterwave rotational spectra of the cis conformer of propionic acid (C3H6O2) have been investigated in the ground vibrational state in the frequency range of 80.0-100.0 GHz. Many high J and K-1 (Jmax = 50, K-1 = 12) rotational lines have been assigned. A least-squares analysis of the measured and previously reported rotational transition frequencies resulted in the determination of an improved set of rotational and centrifugal distortion (CD) constants of the molecule. Detailed MP2 and DFT calculations were also carried out with various functional and basis sets to evaluate the spectroscopic constants, dipole moment, and various structural parameters of cis-propionic acid and compared with the corresponding experimental values. Potential energy surface has been calculated to identify other probable conformers in this molecule.

Jaman, A. I.; Chakraborty, Shamik; Chakraborty, Rangana

2015-01-01

341

[Analysis of PCCA and PCCB gene mutations in patients with propionic acidemia].  

PubMed

OBJECTIVE To analyze PCCA and PCCB gene mutations in 10 Chinese patients with propionic acidemia(PA). METHODS Genomic DNA was extracted from peripheral blood leukocytes. The 39 exons and flanking sequences of the PCCA and PCCB genes were amplified with polymerase chain reaction and subjected to direct DNA sequencing. RESULTS DNA sequencing has revealed that 7 patients have carried a PCCA gene mutation, 2 patients carried PCCB gene mutation and 1 patient carried mutations in both PCCA and PCCB genes. Ten PA mutations were confirmed, including 8 affecting the PCCA gene and 2 affecting the PCCB gene. Three PCCA mutations c.245G>A, IVS15+5del5, c.1288C>T and 2 PCCB mutations c.838insC, c.1087T>C were found for the first time. CONCLUSION Among Chinese patients with propionic acidemia patients, their genetic mutations are mainly found on the PCCA gene. PMID:25636094

Chen, Zhanling; Wen, Pengqiang; Wang, Guobing; Hu, Yuhui; Liu, Xiaohong; Chen, Li; Chen, Shuli; Wan, Lisheng; Cui, Dong; Shang, Yue; Li, Chengrong

2015-02-10

342

Iodine catalyzed acetylation of starch and cellulose  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch and cellulose, earth's most abundant biopolymers, are of tremendous economic importance. Over 90% of cotton and 50% of wood are made of cellulose. Wood and cotton are the major resources for all cellulose products such as paper, textiles, construction materials, cardboard, as well as such c...

343

Microbial Cellulose Utilization: Fundamentals and Biotechnology  

PubMed Central

Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts. PMID:12209002

Lynd, Lee R.; Weimer, Paul J.; van Zyl, Willem H.; Pretorius, Isak S.

2002-01-01

344

Cellulose hydrolysis in subcritical and supercritical water  

Microsoft Academic Search

In this paper we propose a new method to hydrolyze cellulose rapidly in supercritical water (SCW) to recover glucose, fructose and oligomers (cellobiose, cellotriose, cellotetraose, etc.). Cellulose decomposition experiments were conducted with a flow type reactor in the range of temperature from 290 to 400°C at 25MPa. A high pressure slurry feeder was developed to feed the cellulose–water slurries. Hydrolysis

Mitsuru Sasaki; Bernard Kabyemela; Roberto Malaluan; Satoshi Hirose; Naoko Takeda; Tadafumi Adschiri; Kunio Arai

1998-01-01

345

Facile synthesis of spherical cellulose nanoparticles  

Microsoft Academic Search

A practical procedure for synthesizing cellulose nanospheres with sizes ranging from 60 to over 570nm was developed. This methodology provides a near linear relationship between cellulose nanoparticle size and treatment time. The hydrolyzed nanocelluloses are predominantly cellulose II polymorphic crystalline structure and relatively uniform in particle size.

Jianguo Zhang; Thomas J. Elder; Yunqiao Pu; Arthur J. Ragauskas

2007-01-01

346

Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials  

PubMed Central

Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels. PMID:25000264

Isik, Mehmet; Sardon, Haritz; Mecerreyes, David

2014-01-01

347

Ionic liquids and cellulose: dissolution, chemical modification and preparation of new cellulosic materials.  

PubMed

Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels. PMID:25000264

Isik, Mehmet; Sardon, Haritz; Mecerreyes, David

2014-01-01

348

Kinetic calculations for the thermal decomposition of calcium propionate under non-isothermal conditions  

Microsoft Academic Search

Calcium propionate (CP) is shown to be useful for simultaneous SO2\\/NO reduction in coal-fired power plants and its thermal decomposition characteristics are measured by thermogravimetric analysis\\u000a in a feasibility study into more complete reduction of these hazardous gases. Calcium carbonate (CC), which has been used\\u000a primarily for in-furnace desulfuration, was used for comparison. The thermal decomposition of this organic calcium-based

ShengLi Niu; KuiHua Han; ChunMei Lu

2011-01-01

349

Stable-Isotope Probing of Microorganisms Thriving at Thermodynamic Limits: Syntrophic Propionate Oxidation in Flooded Soil  

Microsoft Academic Search

soil by rRNA-based stable-isotope probing (SIP). After 7 weeks of incubation with (13C)propionate (<10 mM) and the oxidation of 30 mol of 13C-labeled substrate per g dry weight of soil, we found that archaeal nucleic acids were 13C labeled to a larger extent than those of the bacterial partners. Nevertheless, both terminal restriction fragment length polymorphism and cloning analyses revealed

Tillmann Lueders; Bianca Pommerenke; Michael W. Friedrich

2004-01-01

350

Survival in COPD patients after regular use of fluticasone propionate and salmeterol in general practice  

Microsoft Academic Search

ABSTRACT: Despite substantial evidence regarding the benefits of combined,use of inhaled corticosteroids and long-acting b2-agonists in asthma, such evidence remains limited for chronic obstructive pulmonary,disease (COPD). Observational data may provide an insight into the expected survival in clinical trials of fluticasone propionate (FP) and salmeterol in COPD. Newly,physician-diagnosed,COPD patients identified in primary,care,during 1990?1999 aged o50 yrs, of both sexes and

J. B. Soriano; J. Vestbo; N. B. Pride; V. Kiri; C. Maden; W. C. Maier

2002-01-01

351

DICOUMAROL CONCENTRATIONS AND FORAGE QUALITY OF SWEETCLOVER FORAGE TREATED WITH PROPIONIC ACID OR ANHYDROUS AMMONIA 1  

Microsoft Academic Search

Three experiments were conducted to determine if propionic acid (PA) or anhydrous ammonia (NH z) could prevent spoiling and subsequent dicoumarol formation in sweetclover (Melilotus officinalis (L.) Lam.) hay. In Exp. 1, PA at 6, 9 or 12 g\\/kg of wet hay prevented dicoumarol formation in 417-g samples of sweetclover hay rewetted to 400-g\\/kg (wet-weight basis) moisture concentration, whereas PA

Matt A. Sanderson; D. W. Meyer; Howard Casper

2010-01-01

352

Topical clobetasol propionate in the treatment of psoriasis: a review of newer formulations.  

PubMed

Ultrapotent topical corticosteroids are the mainstay of psoriasis treatment, used either alone or in combination with a topical vitamin D analog. Traditionally used in an ointment vehicle for psoriasis, clobetasol propionate 0.05% is also available in spray, foam, lotion, and shampoo formulations, which may provide for improved convenience and acceptance in many patients with similar efficacy, safety, and tolerability as the traditional ointment and cream formulations. To compare newer formulations with traditional ointment and cream formulations, we performed a systematic review of the literature. Search terms included 'clobetasol propionate,' in combination with 'psoriasis,' 'vasoconstriction,' 'vasoconstrictor,' or 'absorption' for each of the four vehicles ('spray,' 'foam,' 'lotion,' and 'shampoo'). While there are very few direct comparison studies between clobetasol propionate in different vehicles, the efficacy rates (with success defined as clear or almost clear of psoriasis) for more recent formulations are high, with most patients achieving success after 2-4 weeks of treatment in well controlled clinical trials, with response rates that are similar to those with the traditional clobetasol propionate ointment. Small differences in vasoconstrictor potency or cutaneous absorption have been noted among the formulations, but the clinical significance of these observations is difficult to discern. Recent research has emphasized the importance of treatment adherence in the management of psoriasis. Adherence to treatment is likely to be a far more important determinant of success than are small differences in drug delivery, especially in actual clinical use as opposed to the well controlled environment of clinical trials. For patients who prefer a less messy vehicle, adherence and outcomes are likely to be better with the more recent formulations compared with the traditionally recommended ointment. PMID:19824740

Feldman, Steven R; Yentzer, Brad A

2009-01-01

353

Lecithin\\/chitosan nanoparticles of clobetasol-17-propionate capable of accumulation in pig skin  

Microsoft Academic Search

In this study, clobetasol-17-propionate (CP) loaded lecithin\\/chitosan nanoparticles were studied with special attention to the transport of the active agent across the skin in vitro. Nanoparticles were characterized by measuring particle size, zeta potential, polydispersity index and encapsulation efficiency. The morphology of nanoparticles was evaluated by transmission electron microscopy.Encapsulation experiments with CP showed high encapsulation efficiency (92.2%). To assess the

Taner ?enyi?it; Fabio Sonvico; Stefano Barbieri; Özgen Özer; Patrizia Santi; Paolo Colombo

2010-01-01

354

Comparative adrenal suppression with inhaled budesonide and fluticasone propionate in adult asthmatic patients  

Microsoft Academic Search

BACKGROUND: A study was performed to compare the adrenal suppression caused by inhaled fluticasone propionate and budesonide on a microgram equivalent basis, each given by metered dose inhaler to asthmatic patients. METHODS: Twelve asthmatic patients of mean age 29.9 years, with a forced expiratory volume in one second (FEV1) 92.9% predicted and forced expiratory flow 25-75% (FEF25-75) 69.5% predicted, on

D J Clark; A Grove; R I Cargill; B J Lipworth

1996-01-01

355

Short-term knemometry and urine cortisol excretion in children treated with fluticasone propionate and budesonide: a dose response study  

Microsoft Academic Search

Few thorough comparisons of the systemic effects of inhaled corti- costeroids in children are available. The aim of this study was to compare the effect of budesonide and fluticasone propionate on short-term lower leg growth. Fluticasone propionate, budesonide and placebo were administered for 2 weeks in a randomized, double-blind, double-dummy, cross-over design. Twenty four chil- dren aged 6-12 yrs received

L. Agertoft; S. Pedersen

1997-01-01

356

Simultaneous quantitative determinations of fluticasone propionate and salmeterol xinafote in diskus inhalers.  

PubMed

In the present study, two new methods were developed for the quantitative determination of active components of Seretide(®), commercially available pharmaceutical preparation in the diskus form. One of these methods was based on derivative spectrophotometry and used a zero-crossing technique. The determinations of fluticasone propionate and salmeterol xinafoate were performed by first order derivatisation at 216.5 nm and second order derivatisation at 250 nm, respectively. The concentration ranges were 5.0-32.5 ?g/mL for fluticasone propionate and 2-12 ?g/mL for salmeterol xinafoate. The second method developed also included high performance liquid chromatography. In this method, a methanol-water mobile phase mixture (95:5, v/v) and a C18 chromasil column as a stationary phase were used. The wavelength of the diode array UV detector was 260 nm; the flow rate was 1 mL/min. The concentration ranges were 2-16 ?g/mL for fluticasone propionate and 1-8 ?g/mL for salmeterol xinafoate. The results for both methods from diskus are in the pharmacopea limits. For the statistical determination of these results, these two methods were compared with t-test for the means and with F-test for the standard deviations. PMID:25313021

Duran, A; Dogan, H N; Ulgen, M

2014-01-01

357

Novel fermentation process strengthening strategy for production of propionic acid and vitamin B12 by Propionibacterium freudenreichii.  

PubMed

An efficient fermentation-strengthening approach was developed to improve the anaerobic production of propionic acid and vitamin B12 by co-fermentation with Propionibacterium freudenreichii. Vitamin B12 production from glucose resulted in relatively high productivity (0.35 mg/L h) but a low propionic acid yield (0.55 g/g). By contrast, glycerol gave a high propionic acid yield (0.63 g/g) but low productivity (0.16 g/L h). Co-fermentation of glycerol and glucose with a gradual addition strategy gave high yields (propionic acid: 0.71 g/g; vitamin B12: 0.72 mg/g) and productivities (propionic acid: 0.36 g/L h; vitamin B12: 0.36 mg/L h). Finally, the integrated feedstock and fermentation system strengthening strategy was demonstrated as an efficient method for the economic production of bio-based propionic acid and vitamin B12. PMID:25261985

Wang, Peng; Jiao, Youjing; Liu, Shouxin

2014-12-01

358

Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion†  

PubMed Central

Linear tetrapyrroles (bilins) perform important antioxidant and light harvesting functions in cells from bacteria to humans. To explore the role of the propionate moieties in bilin metabolism, we report the semisynthesis of mono- and di-amides of biliverdin IX? and those of its non-natural XIII? isomer. Initially, these were examined as substrates of two types of NADPH-dependent biliverdin reductase, BVR and BvdR, and of the representative ferredoxin-dependent bilin reductase, phycocyanobilin:ferredoxin oxidoreductase (PcyA). Our studies indicate that the NADPH-dependent biliverdin reductases are less accommodating to amidation of the propionic acid sidechains of biliverdin IX? than PcyA, which does not require free carboxylic acid sidechains to yield its phytobilin product, phycocyanobilin. Bilin amides were also assembled with BV-type and phytobilin-type apophytochromes, demonstrating a role for the 8-propionate in formation of the spectroscopically native Pr dark states of these biliprotein photosensors. Neither ionizable propionate sidechain proved essential to primary photoisomerization for both classes of phytochromes, but an unsubstituted 12-propionate was required for full photointerconversion of phytobilin-type phytochrome Cph1. Taken together, these studies provide insight into the roles of the ionizable propionate sidechains in substrate discrimination by two bilin reductase families while further underscoring the mechanistic differences between the photoconversions of BV-type and phytobilin-type phytochromes. PMID:20565135

Shang, Lixia; Rockwell, Nathan C.; Martin, Shelley S.; Lagarias, J. Clark

2010-01-01

359

Production of bacterial cellulose from alternate feedstocks.  

PubMed

Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low-solids (LS) and high-solids (HS) potato effluents, cheese whey permeate (CW), or sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did strain 10821 and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, and LS was unsuitable for production by strain 10821. However, strain 23770 produced 17% more cellulose from LS than from glucose, indicating that unamended LS could serve as a feedstock for bacterial cellulose. PMID:11963879

Thompson, D N; Hamilton, M A

2001-01-01

360

Production of bacterial cellulose from alternate feedstocks  

SciTech Connect

Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS and HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

D. N. Thompson; M. A. Hamilton

2000-05-07

361

Production of Bacterial Cellulose from Alternate Feedstocks  

SciTech Connect

Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS & HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

Thompson, David Neil; Hamilton, Melinda Ann

2000-05-01

362

A novel kinetic model for polysaccharide dissolution during atmospheric acetic acid pretreatment of sugarcane bagasse.  

PubMed

Acetic acid (AcH) pretreatment of sugarcane bagasse with the catalysis of sulfuric acid (SA) could greatly enhance the enzymatic digestibility of cellulose. However, polysaccharide dissolution happened inevitably during the pretreatment. It was found that the simplest model, which assumes that the total polysaccharides were reactive to be dissolved, could not well describe the kinetic behavior of polysaccharide dissolution. A novel pseudo-homogenous kinetic model was thus developed by introducing a parameter termed as "potential dissolution degree" (?(d)) based on the multilayered structure of cell wall. It was found that solid xylan and glucan dissolutions were a first-order reaction with respect to the dissolvable fraction. Due to the delignification action of AcH, polysaccharide dissolutions were enhanced in AcH media compared with those in aqueous system. Acetylizations of cellulose and sugars were also observed, and AcH concentration showed a significant influence on the degree of acetylization. PMID:24215769

Zhao, Xuebing; Morikawa, Yuichi; Qi, Feng; Zeng, Jing; Liu, Dehua

2014-01-01

363

Novel antimicrobial and biofilm-controlling cellulosic polymers  

NASA Astrophysics Data System (ADS)

Cotton and cellulose acetate (CA) are cellulosic polymers with versatile applications. Like any other polymeric materials, cellulosic materials are also susceptible to microbial contamination and cause serious nosocomial infections. Hence, there is a definite need to develop antimicrobial cellulosic materials to prevent microbial colonization. Henceforth, we prepared a suitable polycation to treat cotton fabrics and CA films by LbL self-assembly process to achieve potent antimicrobial functions. The treated fabrics demonstrated total kill against E. coli and S. aureus in 2 h contact time whereas treated CA films, even after 6 h, could inactivate only 98 % of bacteria. Since CA films are more hydrophobic, have less surface charge, and surface area than cotton fabrics, LbL procedure was not much effective for CA films to achieve potent antimicrobial functions. Yet, CA is another very important cellulosic polymer with various applications in which antimicrobial activity is often desired. So, to improve the antimicrobial activity of CA films, we designed a novel strategy to coat the surface of CaCO3 fillers with quaternary ammonium salts (QAS)based fatty acids to make the filler surface organophilic and accomplish antibacterial activity concurrently, rendering the resulting polymer-filler composites antimicrobial. Thus, a series of QAS-based fatty acids (C8-C16) were synthesized, coated onto CaCO 3, and used as antimicrobial additives (5 %) in CA films. Although C8-quat-CaCO 3 could only provide 94 % of reduction of bacteria, both C12- and C16- quats and their corresponding quat-coated CaCO3 provided a total kill of S. aureus and E. coli in 2 h. These findings suggested that it is feasible to use QAS-based fatty acids to coat CaCO3 and use them as antimicrobial additives of CA films to achieve potent antimicrobial effects. Building on these results, to further evaluate the applicability of the antimicrobial filler strategy, we synthesized an N-halamine based fatty acid, coated onto CaCO3 and used as antimicrobial additives in CA films; the resulting samples provided excellent antimicrobial and biofilm-controlling effects, confirming that the antimicrobial filler approach could be an effective strategy for the antimicrobial treatments of CA and potentially other related hydrophobic polymeric materials.

Padmanabhuni, Revathi V.

364

Molecular Structure of Ethyl acetate  

NSDL National Science Digital Library

Ethyl acetate is a colorless, volatile liquid with a mild and fragrant odor. It is used as solvent in chemistry laboratories but can also be found in many household products such as paints, coatings, and adhesives. The compound is also used in some extraction processes such as decaffeination or purification of antibiotics. It is present in both nail polish and removers. Some synthetic fruit essences may contain this and other esters. Etymologists like to use this solvent for insect collecting as the vapor kill the insect quickly and keep it soft for mounting.

2006-03-08

365

Isolation and characterization of an efficient bacterial cellulose producer strain in agitated culture: Gluconacetobacter hansenii P2A.  

PubMed

In this study, typical niches of acetic acid bacteria were screened for isolation of cellulose producer strains. Hestrin Schramm broth was used as enrichment and production media. Only nine out of 329 isolates formed thick biofilms on liquid surface and were identified as potential cellulose producers. Physiological and biochemical tests proved that all cellulose producers belonged to Gluconacetobacter genus. Most productive and mutation-resistant strain was subjected to 16S rRNA sequence analysis and identified as Gluconacetobacter hansenii P2A due to 99.8 % sequence similarity. X-ray diffraction analysis proved that the biofilm conformed to Cellulose I crystal structure, rich in I? mass fraction. Static cultivation of G. hansenii P2A in HS medium resulted with 1.89?±?0.08 g/l of bacterial cellulose production corresponding to 12.0?±?0.3 % yield in terms of substrate consumption. Shaking and agitation at 120 rpm aided in enhancement of the amount and yield of produced cellulose. Productivity and yield reached up to 3.25?±?0.11 g/l and 17.20?±?0.14 % in agitated culture while a slight decrease from 78.7 % to 77.3 % was observed in the crystallinity index. PMID:24190494

Ayd?n, Yasar Andelib; Aksoy, Nuran Deveci

2014-02-01

366

Investigation and characterization of oxidized cellulose and cellulose nanofiber films  

NASA Astrophysics Data System (ADS)

Over the last two decades, a large amount of research has focused on natural cellulose fibers, since they are "green" and renewable raw materials. Recently, nanomaterials science has attracted wide attention due to the large surface area and unique properties of nanoparticles. Cellulose certainly is becoming an important material in nanomaterials science, with the increasing demand of environmentally friendly materials. In this work, a novel method of preparing cellulose nanofibers (CNF) is being presented. This method contains up to three oxidation steps: periodate, chlorite and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidation. The first two oxidation steps are investigated in the first part of this work. Cellulose pulp was oxidized to various extents by a two step-oxidation with sodium periodate, followed by sodium chlorite. The oxidized products can be separated into three different fractions. The mass ratio and charge content of each fraction were determined. The morphology, size distribution and crystallinity index of each fraction were measured by AFM, DLS and XRD, respectively. In the second part of this work, CNF were prepared and modified under various conditions, including (1) the introduction of various amounts of aldehyde groups onto CNF by periodate oxidation; (2) the carboxyl groups in sodium form on CNF were converted to acid form by treated with an acid type ion-exchange resin; (3) CNF were cross-linked in two different ways by employing adipic dihydrazide (ADH) as cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide (EDC) as carboxyl-activating agent. Films were fabricated with these modified CNF suspensions by vacuum filtration. The optical, mechanical and thermo-stability properties of these films were investigated by UV-visible spectrometry, tensile test and thermogravimetric analysis (TGA). Water vapor transmission rates (WVTR) and water contact angle (WCA) of these films were also studied.

Yang, Han

367

Cellobiohydrolase hydrolyzes crystalline cellulose on hydrophobic faces.  

PubMed

Biodegradation of plant biomass is a slow process in nature, and hydrolysis of cellulose is also widely considered to be a rate-limiting step in the proposed industrial process of converting lignocellulosic materials to biofuels. It is generally known that a team of enzymes including endo- and exocellulases as well as cellobiases are required to act synergistically to hydrolyze cellulose to glucose. The detailed molecular mechanisms of these enzymes have yet to be convincingly elucidated. In this report, atomic force microscopy (AFM) is used to image in real-time the structural changes in Valonia cellulose crystals acted upon by the exocellulase cellobiohydrolase I (CBH I) from Trichoderma reesei. Under AFM, single enzyme molecules could be observed binding only to one face of the cellulose crystal, apparently the hydrophobic face. The surface roughness of cellulose began increasing after adding CBH I, and the overall size of cellulose crystals decreased during an 11-h period. Interestingly, this size reduction apparently occurred only in the width of the crystal, whereas the height remained relatively constant. In addition, the measured cross-section shape of cellulose crystal changed from asymmetric to nearly symmetric. These observed changes brought about by CBH I action may constitute the first direct visualization supporting the idea that the exocellulase selectively hydrolyzes the hydrophobic faces of cellulose. The limited accessibility of the hydrophobic faces in native cellulose may contribute significantly to the rate-limiting slowness of cellulose hydrolysis. PMID:21282110

Liu, Yu-San; Baker, John O; Zeng, Yining; Himmel, Michael E; Haas, Thomas; Ding, Shi-You

2011-04-01

368

Activation of crystalline cellulose to cellulose III(I) results in efficient hydrolysis by cellobiohydrolase.  

PubMed

The crystalline polymorphic form of cellulose (cellulose I(alpha)-rich) of the green alga, Cladophora, was converted into cellulose III(I) and I(beta) by supercritical ammonium and hydrothermal treatments, respectively, and the hydrolytic rate and the adsorption of Trichoderma viride cellobiohydrolase I (Cel7A) on these products were evaluated by a novel analysis based on the surface density of the enzyme. Cellobiose production from cellulose III(I) was more than 5 times higher than that from cellulose I. However, the amount of enzyme adsorbed on cellulose III(I) was less than twice that on cellulose I, and the specific activity of the adsorbed enzyme for cellulose III(I) was more than 3 times higher than that for cellulose I. When cellulose III(I) was converted into cellulose I(beta) by hydrothermal treatment, cellobiose production was dramatically decreased, although no significant change was observed in enzyme adsorption. This clearly indicates that the enhanced hydrolysis of cellulose III(I) is related to the structure of the crystalline polymorph. Thus, supercritical ammonium treatment activates crystalline cellulose for hydrolysis by cellobiohydrolase. PMID:17319934

Igarashi, Kiyohiko; Wada, Masahisa; Samejima, Masahiro

2007-04-01

369

Mercerization of primary wall cellulose and its implication for the conversion of cellulose I?cellulose II  

Microsoft Academic Search

The mercerization of homogenized primary wall cellulose extracted fromsugar beet pulp was investigated by transmission electron microscopy (TEM),X-ray diffraction together with 13C CP-MAS NMR, and FT-IR spectroscopy.For samples resulting from acid extraction, mercerization began at 9% NaOH, whereasfor samples purified by alkaline treatment, the mercerization started at 10%NaOH. The change in morphology when going from cellulose I to cellulose II

Elizabeth Dinand; Michel Vignon; Henri Chanzy; Laurent Heux

2002-01-01

370

Polyimide Cellulose Nanocrystal Composite Aerogels  

NASA Technical Reports Server (NTRS)

Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna

2014-01-01

371

Cellulose degradation by oxidative enzymes  

PubMed Central

Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs), cellobiose dehydrogenases (CDHs) and members of carbohydrate-binding module family 33 (CBM33). PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future. PMID:24688656

Dimarogona, Maria; Topakas, Evangelos; Christakopoulos, Paul

2012-01-01

372

Cellulose degradation by oxidative enzymes.  

PubMed

Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs), cellobiose dehydrogenases (CDHs) and members of carbohydrate-binding module family 33 (CBM33). PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future. PMID:24688656

Dimarogona, Maria; Topakas, Evangelos; Christakopoulos, Paul

2012-01-01

373

Oxidation and sulfonation of cellulosics  

Microsoft Academic Search

Bleached hardwood (HW) kraft pulp and derived nanocellulosic structures were modified by a periodate oxidation followed by\\u000a treatment with sodium bisulfite to yield the corresponding C2\\/3 sulfonates. The impact of this oxidative–reductive protocol\\u000a on the chemical and physical properties of cellulose was evaluated by determining physical dimensions, functional groups,\\u000a and their water absorbency properties. It was found that the water

Jianguo Zhang; Nan Jiang; Zheng Dang; Thomas J. Elder; Arthur J. Ragauskas

2008-01-01

374

Elastic properties of cellulose nanopaper  

Microsoft Academic Search

Nanopaper is a transparent film made of network-forming nanocellulose fibrils. These fibrils are several micrometers long with a diameter of 4--50\\\\,nm. The reported elastic modulus of nanopaper often falls short of even conservative theoretical predictions based on the modulus of crystalline cellulose, although such predictions usually perform very well for macroscopic fiber materials, such as paper or fiber composites. We

A. Kulachenko; T. Danoyelle; S. Galland; S. B. Lindström

2012-01-01

375

Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates.  

PubMed

The potential of microcristaline cellulose as sorbent in the separation of eight compounds: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), procyanidin B1 and procyanidin B2 was studied. Cellulose HPTLC plates prewashed in water (not necessary, when water was used as developing solvent) and dried with a hair dryer, bandwise application and development in horizontal developing chamber (sandwich configuration) gave the best results. Detection was performed using vanillin-H3PO4 reagent. Four new developing solvent systems were proposed: water, 1-propanol-water (20:80, v/v), 1-propanol-water-acetic acid (4:2:1, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v), and at least two of them were needed for the differentiation between all eight compounds. Surprisingly, water enabled the separation of epimers C from EC and GC from EGC, as well as the dimers procianidin B1 and B2. Additionally, C, EGC, B1 and B2 were separated from all the other compounds. The best choice for developing solvent is given for each of the studied compounds. The best separation of the five main catechins (EC, GC, EGC, ECg, EGCg) present in green tea extract was achieved using 1-propanol-water-acetic acid (20:80:1, v/v). The chromatograms of oak bark extract developed in solvents with higher water content (1-propanol-water (1:4, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v)) showed less bands than chromatograms developed in solvents with higher organic modifier content (e.g. 1-propanol-water-acetic acid (4:2:1, v/v)). It was proved that such behavior was due to the presence of procyanidins beside the main component catechin. PMID:16001555

Vovk, Irena; Simonovska, Breda; Vuorela, Heikki

2005-06-10

376

Isolation and Characterization of a Thermophilic Bacterium Which Oxidizes Acetate in Syntrophic Association with a Methanogen and Which Grows Acetogenically on H(2)-CO(2).  

PubMed

We previously described a thermophilic (60 degrees C), syntrophic, two-membered culture which converted acetate to methane via a two-step mechanism in which acetate was oxidized to H(2) and CO(2). While the hydrogenotrophic methanogen Methanobacterium sp. strain THF in the biculture was readily isolated, we were unable to find a substrate that was suitable for isolation of the acetate-oxidizing member of the biculture. In this study, we found that the biculture grew on ethylene glycol, and an acetate-oxidizing, rod-shaped bacterium (AOR) was isolated from the biculture by dilution into medium containing ethylene glycol as the growth substrate. When the axenic culture of the AOR was recombined with a pure culture of Methanobacterium sp. strain THF, the reconstituted biculture grew on acetate and converted it to CH(4). The AOR used ethylene glycol, 1,2-propanediol, formate, pyruvate, glycine-betaine, and H(2)-CO(2) as growth substrates. Acetate was the major fermentation product detected from these substrates, except for 1,2-propanediol, which was converted to 1-propanol and propionate. N,N-Dimethylglycine was also formed from glycine-betaine. Acetate was formed in stoichiometric amounts during growth on H(2)-CO(2), demonstrating that the AOR is an acetogen. This reaction, which was carried out by the pure culture of the AOR in the presence of high partial pressures of H(2), was the reverse of the acetate oxidation reaction carried out by the AOR when hydrogen partial pressures were kept low by coculturing it with Methanobacterium sp. strain THF. The DNA base composition of the AOR was 47 mol% guanine plus cytosine, and no cytochromes were detected. PMID:16347518

Lee, Monica J; Zinder, Stephen H

1988-01-01

377

Surface modification of natural fibers using bacteria: depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites.  

PubMed

Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of natural fibers by utilizing bacteria ( Acetobacter xylinum) to deposit nanosized bacterial cellulose around natural fibers, which enhances their adhesion to renewable polymers. This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation. The modified fibers were characterized by scanning electron microscopy, single fiber tensile tests, X-ray photoelectron spectroscopy, and inverse gas chromatography to determine their surface and mechanical properties. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate and poly(L-lactic acid) was quantified using the single fiber pullout test. PMID:18491942

Pommet, Marion; Juntaro, Julasak; Heng, Jerry Y Y; Mantalaris, Athanasios; Lee, Adam F; Wilson, Karen; Kalinka, Gerhard; Shaffer, Milo S P; Bismarck, Alexander

2008-06-01

378

Effect of presence of cellulose in the freshwater sediment on the performance of sediment microbial fuel cell.  

PubMed

The performance of sediment microbial fuel cells (SMFCs) was evaluated in the presence of cellulose in the aquaculture pond sediment as 2% (w/w) in SMFC-2, 4% in SMFC-3 and without adding cellulose in SMFC-1. From aquaculture water, average chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies of 80.6±0.3% and 83.0±0.01% were obtained in SMFC-1, 88.2±0.5% and 89.6±0.8% in SMFC-2 and 83.1±0.3% and 64.5±1.6% in SMFC-3, respectively. During the complete experimental period, acetic acid was the only short chain fatty acid detected in all three SMFCs. Sediment organic matter removal in SMFC-1, SMFC-2 and SMFC-3 were 16%, 22% and 18.6%, respectively. SMFCs demonstrated effective cellulose degradation from aquaculture pond sediment and maintained the oxidized sediment top layer favourable for aquaculture. PMID:24434698

Sajana, T K; Ghangrekar, M M; Mitra, A

2014-03-01

379

Effect of Topical Steroid (0.05% Clobetasol Propionate) Treatment in Children With Severe Phimosis  

PubMed Central

Purpose We report our experience with the use of a topical steroid, 0.05% clobetasol propionate, for the treatment of phimosis with clinical complications. Materials and Methods This was a retrospective analysis of the clinical outcomes of all patients presenting with phimosis to a single institution during the time period from October 2008 to May 2012. A total of 88 patients who had a Kikiros retractability grade of 4 or 5 and phimosis-associated clinical complications, such as ballooning of the prepuce, balanoposthitis, or a history of urinary tract infection (UTI), were instructed to apply 0.05% clobetasol propionate cream to the slightly retracted foreskin and to massage gently while retracting the foreskin. The efficacy of treatment was evaluated at 4 weeks from the initiation of therapy. Results A total of 60 of the 88 patients (68.2%) showed a complete response (i.e., full retraction of the foreskin) to the therapy. The phimotic ring disappeared in 25 of the 88 patients (28.4%) after treatment. Patients who had a history of balanoposthitis, smegma, ballooning of the prepuce, or UTI showed significantly poorer improvement in preputial retraction (p<0.001, p<0.001, p<0.001, and p=0.02, respectively) and phimotic ring disappearance (p<0.001, p=0.001, p<0.001, and p=0.001, respectively) after treatment. No significant local or systemic side effects were associated with the administration of topical steroids. Conclusions Topical application of 0.05% clobetasol propionate cream and skin stretching is a safe, simple, and effective procedure with no significant side effects for severe phimosis in prepubertal boys. PMID:24044098

Lee, Chan Ho

2013-01-01

380

Electrospinning of Cellulose and Carbon Nanotube-Cellulose Fibers for Smart Applications  

E-print Network

Cellulose is one of the Earth’s most abundant natural polymers and is used as a raw material in various applications. Recently, cellulose based electro-active paper (EAPap) has been investigated for its potential as a smart material...

Pankonien, Alexander

2008-08-19

381

Pyrolytic sugars from cellulosic biomass.  

PubMed

Depolymerization of cellulose offers the prospect of inexpensive sugars from biomass. Breaking the glycosidic bonds of cellulose to liberate glucose has usually been pursued by acid or enzymatic hydrolysis although a purely thermal depolymerization route to sugars is also possible. Fast pyrolysis of pure cellulose yields primarily the anhydrosugar levoglucosan (LG) whereas the presence of naturally occurring alkali and alkaline earth metals (AAEMs) in biomass strongly catalyzes ring-breaking reactions that favor formation of light oxygenates. Here, we show a method of significantly increasing the yield of sugars from biomass by purely thermal means through infusion of certain mineral acids (phosphoric and sulfuric acid) into the biomass to convert the AAEMs into thermally stable salts (particularly potassium sulfates and phosphates). These salts not only passivate AAEMs that normally catalyze fragmentation of pyranose rings, but also buffer the system at pH levels that favor glycosidic bond breakage. It appears that AAEM passivation contributes to 80?% of the enhancement in LG yield while the buffering effect of the acid salts contributes to the balance of the enhancement. PMID:22976992

Kuzhiyil, Najeeb; Dalluge, Dustin; Bai, Xianglan; Kim, Kwang Ho; Brown, Robert C

2012-11-01

382

Enzymatic Hydrolysis of Cellulosic Biomass  

SciTech Connect

Biological conversion of cellulosic biomass to fuels and chemicals offers the high yields to products vital to economic success and the potential for very low costs. Enzymatic hydrolysis that converts lignocellulosic biomass to fermentable sugars may be the most complex step in this process due to substrate-related and enzyme-related effects and their interactions. Although enzymatic hydrolysis offers the potential for higher yields, higher selectivity, lower energy costs, and milder operating conditions than chemical processes, the mechanism of enzymatic hydrolysis and the relationship between the substrate structure and function of various glycosyl hydrolase components are not well understood. Consequently, limited success has been realized in maximizing sugar yields at very low cost. This review highlights literature on the impact of key substrate and enzyme features that influence performance to better understand fundamental strategies to advance enzymatic hydrolysis of cellulosic biomass for biological conversion to fuels and chemicals. Topics are summarized from a practical point of view including characteristics of cellulose (e.g., crystallinity, degree of polymerization, and accessible surface area) and soluble and insoluble biomass components (e.g., oligomeric xylan, lignin, etc.) released in pretreatment, and their effects on the effectiveness of enzymatic hydrolysis. We further discuss the diversity, stability, and activity of individual enzymes and their synergistic effects in deconstructing complex lignocellulosic biomass. Advanced technologies to discover and characterize novel enzymes and to improve enzyme characteristics by mutagenesis, post-translational modification, and over-expression of selected enzymes and modifications in lignocellulosic biomass are also discussed.

Yang, Bin; Dai, Ziyu; Ding, Shi-You; Wyman, Charles E.

2011-08-22

383

Pyrolysis of cellulose and lignin  

NASA Astrophysics Data System (ADS)

X-ray and UV-induced photoelectron spectroscopy (XPS and UPS) and scanning electron microscopy (SEM) have been performed to characterise the pyrolysis of cellulose and lignin and their interaction with methanol. Clean highly oriented pyrolitic graphite (HOPG) was also analysed as a reference material. Asymmetric C1s core level fits and valence band XPS of the samples indicate a graphitic-like structure after the pyrolysis at 1200 °C. Due to the low polar contents in pyrolysed cellulose and lignin, an interaction with methanol under high vacuum conditions could not be identified. From a technical viewpoint a temperature of 1200 °C is attainable without high costs. Therefore, the pyrolysis of wood-based polymers containing high amounts of cellulose and lignin are potential low-cost materials for various applications. If it is possible to generate graphite in complex structures made of wood-based polymers, a cheap and energy-efficient method will become available for producing bipolar plates for fuel cells. Technical problems like form instability and foaming are discussed as well as further development and possible modifications of the ground material to achieve optimal compositions.

Haensel, T.; Comouth, A.; Lorenz, P.; Ahmed, S. I.-U.; Krischok, S.; Zydziak, N.; Kauffmann, A.; Schaefer, J. A.

2009-06-01

384

Green and economical production of propionic acid by Propionibacterium freudenreichii CCTCC M207015 in plant fibrous-bed bioreactor.  

PubMed

Propionic acid production by Propionibacterium freudenreichii from molasses and waste propionibacterium cells was studied in plant fibrous-bed bioreactor (PFB). With non-treated molasses as carbon source, 12.69 ± 0.40 g l(-1) of propionic acid was attained at 120 h in free-cell fermentation, whereas the PFB fermentation yielded 41.22 ± 2.06 g l(-1) at 120 h and faster cells growth was observed. In order to optimize the fermentation outcomes, fed-batch fermentation was performed with hydrolyzed molasses in PFB, giving 91.89 ± 4.59 g l(-1) of propionic acid at 254 h. Further studies were carried out using hydrolyzed waste propionibacterium cells as substitute nitrogen source, resulting in a propionic acid concentration of 79.81 ± 3.99 g l(-1) at 302 h. The present study suggests that the low-cost molasses and waste propionibacterium cells can be utilized for the green and economical production of propionic acid by P. freudenreichii. PMID:21421303

Feng, Xiaohai; Chen, Fei; Xu, Hong; Wu, Bo; Li, Hui; Li, Sha; Ouyang, Pingkai

2011-05-01

385

Proton-Coupled Electron Transfer Reactions at a Heme-Propionate in an Iron-Protoporphyrin-IX Model Compound  

PubMed Central

A heme model system has been developed in which the heme-propionate is the only proton donating/accepting site, using protoporphyrin IX-monomethyl esters (PPIXMME) and N-methylimidazole (MeIm). Proton-coupled electron transfer (PCET) reactions of these model compounds have been examined in acetonitrile solvent. (PPIXMME)FeIII(MeIm)2-propionate (FeIII~CO2) is readily reduced by the ascorbate derivative 5,6-isopropylidine ascorbate to give (PPIXMME)FeII(MeIm)2-propionic acid (FeII~CO2H). Excess of the hydroxylamine TEMPOH or of hydroquinone similarly reduce FeIII~CO2, and TEMPO and benzoquinone oxidize FeII~CO2H to return to FeIII~CO2. The measured equilibrium constants, and the determined pKa and E1/2 values, indicate that FeII~CO2H has an effective bond dissociation free energy (BDFE) of 67.8 ± 0.6 kcal mol–1. In these PPIX models, electron transfer occurs at the iron center and proton transfer occurs at the remote heme propionate. According to thermochemical and other arguments, the TEMPOH reaction occurs by concerted proton-electron transfer (CPET), and a similar pathway is indicated for the ascorbate derivative. Based on these results, heme propionates should be considered as potential key components of PCET/CPET active sites in heme proteins. PMID:21524059

2011-01-01

386

Propionate precursors and other metabolic intermediates as possible alternative electron acceptors to methanogenesis in ruminal fermentation in vitro.  

PubMed

Fifteen potential precursors of propionate were tested for their ability to decrease CH4 production by ruminal fluid in vitro. Sodium acrylate and sodium fumarate produced the most consistent effects in batch cultures, with 50 % of the added precursors being fermented to propionate and CH4 production decreasing by between 8 and 17 %, respectively. Additives were more effective when added as free acids, but this also decreased the pH and may have inhibited fibre digestion. Changing the dietary substrate from predominantly grass hay to predominantly concentrate had no influence on the effectiveness of acrylate and fumarate. In an in vitro fermentor (the rumen simulating technique, Rusitec) with a grass hay-concentrate (50:50, w/w) diet as substrate, both compounds were again fermented to propionate (33 and 44 % conversion to propionate, respectively). However, fumarate appeared more effective as a H2 sink compound. It was calculated to capture 44 % of the H2 previously used for CH4 formation compared with a 22 % capture of H2 with acrylate. Fumarate also caused a stimulation in fibre digestion. Thus, sodium fumarate was the preferred propionate precursor for use as a feed ingredient to decrease CH4 emissions from ruminants. PMID:16115329

Newbold, C J; López, S; Nelson, N; Ouda, J O; Wallace, R J; Moss, A R

2005-07-01

387

Clobetasol propionate shampoo 0.05% in the treatment of seborrheic dermatitis of the scalp: results of a pilot study.  

PubMed

Seborrheic dermatitis (SD), a common dermatosis associating hyperseborrhea, erythema, itching, and dandruff, has frequent scalp involvement. Malassezia furfur infection seems to play an important role in the condition's etiopathology. Treatment of SD usually consists of corticosteroids or antifungals, such as ketoconazole. The aim of this multicenter, randomized, investigator-blinded, parallel-group pilot study was to evaluate the efficacy and safety of clobetasol propionate shampoo 0.05% after different short-contact application times compared with its vehicle and ketoconazole foaming gel 2% in the treatment of SD of the scalp. For 4 weeks, 55 subjects received one of the following treatments twice weekly: clobetasol propionate shampoo for 2.5, 5, or 10 minutes; clobetasol propionate vehicle for 10 minutes; or ketoconazole foaming gel for 5 minutes before rinsing off. Efficacy criteria included total severity score (TSS) and individual scores of signs such as itching and global improvement. Safety included reporting of burning, overall tolerance, and adverse events. Results showed that an application of clobetasol propionate for 5 and 10 minutes provided a similar mean percentage decrease of TSS, and the mean percentage decrease of TSS for all active groups was significantly superior to that of the vehicle (P < .01). Overall and local safety were good for all treatment groups. The present pilot study demonstrated that a short-contact application of clobetasol propionate shampoo is effective and safe in the treatment of SD of the scalp. PMID:17569404

Reygagne, Pascal; Poncet, Michel; Sidou, Farzaneh; Soto, Pascale

2007-05-01

388

Adsorption of cellulase on cellulose: effect of physicochemical properties of cellulose on adsorption and rate of hydrolysis  

Microsoft Academic Search

In the cellulase-cellulose reaction system, the adsorption of cellulase on the solid cellulose substrate was found to be one of the important parameters that govern the enzymatic hydrolysis rate of cellulose. The adsorption of cellulase usually parallels the rate of hydrolysis of cellulose. The affinity for cellulase varies depending on the structural properties of cellulose. Adsorption parameters such as the

Sun Bok Lee; H. S. Shin; Dewey D. Y. Ryu; M. Mandels

1982-01-01

389

Effect of Cellulose Characteristic and Hydrolyze Conditions on Morphology and Size of Nanocrystal Cellulose Extracted from Wheat Straw  

Microsoft Academic Search

In this paper, preparation and characterization of cellulose and nanocrystalline celluloses (NCC) and the effect of cellulose characteristic and hydrolyze conditions on the morphology and size of the obtained NCC will be discussed. Two different celluloses were prepared by two procedures, A and B, then the cellulose obtained was hydrolyzed under the same conditions. The result showed that the morphology

Maryam Rahimi; Rabi Behrooz

2011-01-01

390

Oxidized Regenerated Cellulose Resembling Vaginal Cuff Abscess  

PubMed Central

Introduction: Application of oxidized regenerated cellulose is commonly performed in laparoscopy to achieve hemostasis during surgery. The appearance of an abscess resembles oxidized regenerated cellulose, causing imaging studies to be difficult to interpret. Case Description: We describe the cases of 3 patients who underwent oxidized regenerated cellulose placement during laparoscopic gynecologic surgery. They subsequently presented with signs and symptoms resembling an abscess. Computed tomographic imaging can be challenging to interpret in such cases; radiologic findings can be used to differentiate between the characteristics of oxidized regenerated cellulose and those of abscess formation on the vaginal cuff. Discussion: Oxidized regenerated cellulose has an appearance that often mimics postsurgical abscess formation. There are distinct characteristics that distinguish both findings. It is essential that patients' records accurately describe the presence and location of regenerated oxidized cellulose when placed intraoperatively, and this information must be relayed to the interpreting radiologist to facilitate medical diagnosis and guide clinical management. PMID:24960506

Harkins, Gerald; Dykes, Thomas; Gockley, Allison; Davies, Matthew

2014-01-01

391

Micromechanics and poroelasticity of hydrated cellulose networks.  

PubMed

The micromechanics of cellulose hydrogels have been investigated using a new rheological experimental approach, combined with simulation using a poroelastic constitutive model. A series of mechanical compression steps at different strain rates were performed as a function of cellulose hydrogel thickness, combined with small amplitude oscillatory shear after each step to monitor the viscoelasticity of the sample. During compression, bacterial cellulose hydrogels behaved as anisotropic materials with near zero Poisson's ratio. The micromechanics of the hydrogels altered with each compression as water was squeezed out of the structure, and microstructural changes were strain rate-dependent, with increased densification of the cellulose network and increased cellulose fiber aggregation observed for slower compressive strain rates. A transversely isotropic poroelastic model was used to explain the observed micromechanical behavior, showing that the mechanical properties of cellulose networks in aqueous environments are mainly controlled by the rate of water movement within the structure. PMID:24784575

Lopez-Sanchez, P; Rincon, Mauricio; Wang, D; Brulhart, S; Stokes, J R; Gidley, M J

2014-06-01

392

Hydrothermal pretreatment of bamboo and cellulose degradation.  

PubMed

A systematic hydrothermal pretreatment of bamboo chips had been conducted with an aim to trace the cellulose degradation. The results showed that cellulose chain cleavage basically occurred when the temperature exceeded 150°C. A slightly higher DP (degree of polymerization) than starting material had been observed at low temperature pretreatment. Treatment at higher temperature (? 170°C) caused severe cleavage of cellulose and therefore gave rise to low DP with more soluble species. DP of cellulose declined drastically without additional hemicelluloses dissolution when hemicelluloses removal reached to the limit level. Cellulose degradation under hydrothermal pretreatment generally followed the zero reaction kinetics with the activity energy of 121.0 kJ/mol. Besides, the increase of cellulose crystalline index and the conversion of I?-I? had also observed at the hydrothermal pretreatment. PMID:24077149

Ma, X J; Cao, S L; Lin, L; Luo, X L; Hu, H C; Chen, L H; Huang, L L

2013-11-01

393

Micropreparative electrophoresis of globin chains on cellulose acetate film in structural identification of abnormal human hemoglobins.  

PubMed

A simple and rapid micropreparative method for isolating 5 to 30 nmol of globin chain, followed by structural identification of abnormal human hemoglobins, is described. The method is based on the electrophoretic separation of globins on ordinary Cellogel films under denaturating conditions with subsequent cutting out of the protein zones and solubilization of Cellogel and the electrophoretic buffer components in a specially selected solvent in which the globin chain undergoes quantitative precipitation. The method makes it possible to simplify and speed up the structural identification of commonly occurring abnormal hemoglobins. The advantages and limitations of the method are discussed along with its potential uses in structural protein chemistry. PMID:3407907

Spivak, V A; Lutsenko, I N

1988-05-15

394

Cellulose Acetate Replica Cleaning Study of Genesis Non-Flight Sample 3CZ00327  

NASA Technical Reports Server (NTRS)

The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We are working interactively with the community of scientists analyzing Genesis samples, using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. That is, we are evaluating the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

2014-01-01

395

Nanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations  

E-print Network

silicate SAMH-3 and show that it can be exfoliated using a high shear rate generated by a high-speed mixer to synthesize economically on large scale. Hence, composite/hybrid (`mixed matrix') membranes are widely being materials and a low density of defects. Another approach towards hybrid membran

Nair, Sankar

396

Origins of threefold rotational barriers of molecule containing two methyl groups: Ethyl propionate as paradigm  

NASA Astrophysics Data System (ADS)

Origins of the rotational barriers of TG- form of ethyl propionate molecule have been investigated. The barrier heights, as determined from the Raman spectrum, are estimated to be 2.88 and 3.17 kcal/mol for the -CH3 (I) and -CH3 (II) methyl groups of the molecule respectively. The detail analyses suggest that the combined relaxations of the C2-C3, C2-C4 bond lengths and H10-C3-H11, C2-C4-H13 angles together play a significant role to control the barrier heights of methyl CH3 (I), CH3 (II) groups of the molecule.

Dutta, Bipan; Chowdhury, Joydeep

2014-09-01

397

Positron scattering from vinyl acetate  

NASA Astrophysics Data System (ADS)

Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

2014-09-01

398

Extractive fermentation of acetic acid  

SciTech Connect

In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

Busche, R.M. [Bio En-Gene-Er Associates, Inc., Wilmington, DE (United States)

1991-12-31

399

Isolation of levoglucosan from pyrolysis oil derived from cellulose  

DOEpatents

High purity levoglucosan is obtained from pyrolysis oil derived from cellulose by: mixing pyrolysis oil with water and a basic metal hydroxide, oxide, or salt in amount sufficient to elevate pH values to a range of from about 12 to about 12.5, and adding an amount of the hydroxide, oxide, or salt in excess of the amount needed to obtain the pH range until colored materials of impurities from the oil are removed and a slurry is formed; drying the slurry azeotropically with methyl isobutyl ketone solvent to form a residue, and further drying the residue by evaporation; reducing the residue into a powder; continuously extracting the powder residue with ethyl acetate to provide a levoglucosan-rich extract; and concentrating the extract by removing ethyl acetate to provide crystalline levoglucosan. Preferably, Ca(OH).sub.2 is added to adjust the pH to the elevated values, and then Ca(OH).sub.2 is added in an excess amount needed.

Moens, Luc (Lakewood, CO)

1994-01-01

400

Some Complexation Reactions of Cellulosic Ethers  

Microsoft Academic Search

Cellulose ethers were prepared by the reaction of sodium cellulosate with 1-chloromethylnaphthalene, 2-bromomethyl-pyridine, 2-chloropyridine, crotyl bromide, propargyl chloride, and 1-naphthyl glycidyl ether and their complexation ability was investigated. No ?-complex formation with picric acid or 2,4,6-trinitrobenzene took place. Results were attributed to steric hindrance from the cellulosic backbone. Complexation of some metal salts by the crotyl and propargyl ethers was

Yair Avny; Ron Rahman; Albert Zilkha

1972-01-01

401

Production of caproic acid by cocultures of ruminal cellulolytic bacteria and Clostridium kluyveri grown on cellulose and ethanol.  

PubMed

Ruminal cellulolytic bacteria (Fibrobacter succinogenes S85 or Ruminococcus flavefaciens FD-1) were combined with the non-ruminal bacterium Clostridium kluyveri and grown together on cellulose and ethanol. Succinate and acetate produced by the cellulolytic organisms were converted to butyrate and caproate only when the culture medium was supplemented with ethanol. Ethanol (244 mM) and butyrate (30 mM at pH 6.8) did not inhibit cellulose digestion or product formation by S85 or FD-1; however caproate (30 mM at pH 6.8) was moderately inhibitory to FD-1. Succinate consumption and caproate production were sensitive to culture pH, with more caproic acid being produced when the culture was controlled at a pH near neutrality. In a representative experiment under conditions of controlled pH (at 6.8) 6.0 g cellulose l-1 and 4.4 g ethanol l-1 were converted to 2.6 g butyrate l-1 and 4.6 g caproate l-1. The results suggest that bacteria that efficiently produce low levels of ethanol and acetate or succinate from cellulose should be useful in cocultures for the production of caproic acid, a potentially useful industrial chemical and bio-fuel precursor. PMID:8597554

Kenealy, W R; Cao, Y; Weimer, P J

1995-12-01

402

Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae.  

PubMed

A current challenge of the cellulosic ethanol industry is the effect of inhibitors present in biomass hydrolysates. Acetic acid is an example of one such inhibitor that is released during the pretreatment of hemicellulose. This study examined the effect of acetic acid on the cofermentation of glucose and xylose under controlled pH conditions by Saccharomyces cerevisiae 424A(LNH-ST), a genetically engineered industrial yeast strain. Acetic acid concentrations of 7.5 and 15 g L(-1), representing the range of concentrations expected in actual biomass hydrolysates, were tested under controlled pH conditions of 5, 5.5, and 6. The presence of acetic acid in the fermentation media led to a significant decrease in the observed maximum cell biomass concentration. Glucose- and xylose-specific consumption rates decreased as the acetic acid concentration increased, with the inhibitory effect being more severe for xylose consumption. The ethanol production rates also decreased when acetic acid was present, but ethanol metabolic yields increased under the same conditions. The results also revealed that the inhibitory effect of acetic acid could be reduced by increasing media pH, thus confirming that the undissociated form of acetic acid is the inhibitory form of the molecule. PMID:20402796

Casey, Elizabeth; Sedlak, Miroslav; Ho, Nancy W Y; Mosier, Nathan S

2010-06-01

403

Cellulose-binding domains confer an enhanced activity against insoluble cellulose to Ruminococcus albus endoglucanase IV  

Microsoft Academic Search

The gene encoding cellulose-binding domains (CBDs) from Clostridium stercorarium xylanase A was joined to the egIV gene encoding endoglucanase IV (EGIV) from Ruminococcus albus. The hybrid protein (EGIV + CBD) expressed from this fusion gene in Escherichia coli acquired the ability to adsorb onto insoluble celluloses such as ball-milled cellulose (BMC). EGIV + CBD was more active toward BMC at

Shuichi Karita; Kazuo Sakka; Kunio Ohmiya

1996-01-01

404

Formation of brown lines in paper: characterization of cellulose degradation at the wet-dry interface.  

PubMed

Brown lines were generated at the wet-dry interface on Whatman paper No. 1 by suspending the sheet vertically in deionized water. Formic acid and acetic acid were quantified in three areas of the paper defined by the wet-dry boundary (above, below, and at the tideline) using capillary zone electrophoresis with indirect UV detection. Their concentration increased upon accelerated aging of the paper and was highest in the tideline. The hydroperoxides have been quantified using reverse phase high performance liquid chromatography with UV detection based on the determination of triphenylphosphine oxide produced from the reaction with triphenylphosphine, and their highest concentration was found in the tideline as well. For the first time, it was shown that various types of hydroperoxides were present, water-soluble and non-water-soluble, most probably in part hydroperoxide functionalized cellulose. After accelerated aging, a significant increase in hydroperoxide concentration was found in all the paper areas. The molar masses of cellulose determined using size-exclusion chromatography with multiangle light scattering detection showed that, upon aging, cellulose degraded significantly more in the tideline area than in the other areas of the paper. The area below the tideline was more degraded than the area above. A kinetic study of the degradation of cellulose allowed determining the constants for glycosidic bond breaking in each of the areas of the paper. PMID:18715033

Souguir, Zied; Dupont, Anne-Laurence; de la Rie, E René

2008-09-01

405

Polypropylene (PP) nanocomposites incorporating nanocrystalline cellulose (NCC).  

E-print Network

??The main objective of this dissertation is to evaluate the feasibility of preparation of well dispersed polypropylene (PP)/nanocrystalline cellulose (NCC) nanocomposites by melt processing. There… (more)

Khoshkava, Vahid

2014-01-01

406

Cellulose Synthase Complexes: Composition and Regulation  

PubMed Central

Live cell imaging has greatly advanced our knowledge on the molecular mechanism by which cellulose is deposited. Both the actin and microtubule cytoskeleton are involved in assuring the proper distribution, organization, and dynamics of cellulose synthase complexes (CSCs). This review is an update on the most recent progress on the characterization of the composition, regulation, and trafficking of CSCs. With the newly identified cellulose synthase interactive protein 1 (CSI1) on hand, we begin to unveil the mystery of an intimate relationship between cellulose microfibrils and microtubules. PMID:22639663

Lei, Lei; Li, Shundai; Gu, Ying

2012-01-01

407

Systemic treatment with the enteric bacterial fermentation product, propionic acid, produces both conditioned taste avoidance and conditioned place avoidance in rats.  

PubMed

Propionic acid, an enteric bacterial fermentation product, has received recent attention in regards to satiety and obesity in humans. The possibility that propionic acid might produce internal aversive cues was investigated in two experiments using conditioned taste avoidance and place avoidance procedures to index the potential aversive nature of systemic treatment with propionic acid in male rats. Experiment 1 examined the effect of systemic treatment with propionic acid (500 mg/kg), LiCl (95 mg/kg) or vehicle (all corrected to pH 7.5) on the formation of conditioned taste avoidance using a lickometer procedure. On 3 acquisition days three groups of rats were injected with propionic acid, LiCl or vehicle, following 30 min access to 0.3M sucrose solution. Both the Propionic acid group and the LiCl group evidenced a conditioned taste avoidance by the end of the acquisition period. During a drug free extinction phase the Propionic acid group showed extinction of the taste avoidance whereas the LiCl group did not. Experiment 2 involved place preference conditioning with propionic acid treatment associated with one novel context and vehicle with a different novel context on 6 conditioning trials for each type of injection. Place avoidance was assessed on two drug free extinction trials. Multi-variable assessment of the unconditioned (Acquisition Trials) and conditioned effects (Extinction Trials) of propionic acid on locomotor activity was quantified as was chamber choice time on the extinction trials. Propionic acid induced a significant place avoidance and significantly reduced locomotor activity on some acquisition trials. During the extinction trials rats exhibited enhanced locomotor activity levels in the propionic acid associated chamber, likely due to the conditioned aversive nature of this chamber. PMID:22085877

Ossenkopp, Klaus-Peter; Foley, Kelly A; Gibson, James; Fudge, Melissa A; Kavaliers, Martin; Cain, Donald P; Macfabe, Derrick F

2012-02-01

408

A versatile and robust aerotolerant microbial community capable of cellulosic ethanol production.  

PubMed

The use of microbial communities in the conversion of cellulosic materials to bio-ethanol has the potential to improve the economic competitiveness of this biofuel and subsequently lessen our dependency on fossil fuel-based energy sources. Interactions between functionally different microbial groups within a community can expand habitat range, including the creation of anaerobic microenvironments. Currently, research focussing on exploring the nature of the interactions occurring during cellulose degradation and ethanol production within mixed microbial communities has been limited. The aim of this study was to enrich and characterize a cellulolytic bacterial community, and determine if ethanol is a major soluble end-product. Cellulolytic activity by the community was observed in both non-reduced and pre-reduced media, with ethanol and acetate being major fermentation products. Similar results were obtained when sterile wastewater extract was provided as nutrient. Several community members showed high similarity to Clostridium species with overlapping metabolic capabilities, suggesting clostridial functional redundancy. PMID:23238345

Ronan, Patrick; Yeung, C William; Schellenberg, John; Sparling, Richard; Wolfaardt, Gideon M; Hausner, Martina

2013-02-01

409

21 CFR 184.1005 - Acetic acid.  

Code of Federal Regulations, 2011 CFR

...as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2 H4 O2 , CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant...fermentation of carbohydrates or by organic synthesis. The principal...

2011-04-01

410

Facile fabrication of hierarchical cellulose nanospicules via hydrolytic hydrogenation.  

PubMed

A new spicule-like cellulose nanostructure is prepared from electrospun cellulose nanofibers using a one-pot bifunctional catalysis strategy namely hydrolytic hydrogenation. The electrospun cellulose nanofibers or cellulose film was treated in presence of catalyst consisting of an alkali and a metal to produce celluloses with structures like nanospicules, nanoflowers or nanorods, respectively. This work highlights the promising combination of electrospinning and hydrolysis/hydrogenation for facile production of hierarchical cellulose nanostructures such as nanospicules and nanorods. PMID:25498653

Devarayan, Kesavan; Kim, Hak-Yong; Kim, Byoung-Suhk

2015-03-01

411

Magnetite particles triggering a faster and more robust syntrophic pathway of methanogenic propionate degradation.  

PubMed

Interspecies electron transfer mechanisms between Bacteria and Archaea play a pivotal role during methanogenic degradation of organic matter in natural and engineered anaerobic ecosystems. Growing evidence suggests that in syntrophic communities electron transfer does not rely exclusively on the exchange of diffusible molecules and energy carriers such as hydrogen or formate, rather microorganisms have the capability to exchange metabolic electrons in a more direct manner. Here, we show that supplementation of micrometer-size magnetite (Fe3O4) particles to a methanogenic sludge enhanced (up to 33%) the methane production rate from propionate, a key intermediate in the anaerobic digestion of organic matter and a model substrate to study energy-limited syntrophic communities. The stimulatory effect most probably resulted from the establishment of a direct interspecies electron transfer (DIET), based on magnetite particles serving as electron conduits between propionate-oxidizing acetogens and carbon dioxide-reducing methanogens. Theoretical calculations revealed that DIET allows electrons to be transferred among syntrophic partners at rates which are substantially higher than those attainable via interspecies H2 transfer. Besides the remarkable potential for improving anaerobic digestion, which is a proven biological strategy for renewable energy production, the herein described conduction-based DIET could also have a role in natural methane emissions from magnetite-rich soils and sediments. PMID:24901501

Cruz Viggi, Carolina; Rossetti, Simona; Fazi, Stefano; Paiano, Paola; Majone, Mauro; Aulenta, Federico

2014-07-01

412

The 2-methylcitrate cycle is implicated in the detoxification of propionate in Toxoplasma gondii.  

PubMed

Toxoplasma gondii belongs to the coccidian subgroup of the Apicomplexa phylum. The Coccidia are obligate intracellular pathogens that establish infection in their mammalian host via the enteric route. These parasites lack a mitochondrial pyruvate dehydrogenase complex but have preserved the degradation of branched-chain amino acids (BCAA) as a possible pathway to generate acetyl-CoA. Importantly, degradation of leucine, isoleucine and valine could lead to concomitant accumulation of propionyl-CoA, a toxic metabolite that inhibits cell growth. Like fungi and bacteria, the Coccidia possess the complete set of enzymes necessary to metabolize and detoxify propionate by oxidation to pyruvate via the 2-methylcitrate cycle (2-MCC). Phylogenetic analysis provides evidence that the 2-MCC was acquired via horizontal gene transfer. In T.?gondii tachyzoites, this pathway is split between the cytosol and the mitochondrion. Although the rate-limiting enzyme 2-methylisocitrate lyase is dispensable for parasite survival, its substrates accumulate in parasites deficient in the enzyme and its absence confers increased sensitivity to propionic acid. BCAA is also dispensable in tachyzoites, leaving unresolved the source of mitochondrial acetyl-CoA. PMID:23279335

Limenitakis, Julien; Oppenheim, Rebecca D; Creek, Darren J; Foth, Bernardo J; Barrett, Michael P; Soldati-Favre, Dominique

2013-02-01

413

The 2-methylcitrate cycle is implicated in the detoxification of propionate in Toxoplasma gondii  

PubMed Central

Toxoplasma gondii belongs to the coccidian subgroup of the Apicomplexa phylum. The Coccidia are obligate intracellular pathogens that establish infection in their mammalian host via the enteric route. These parasites lack a mitochondrial pyruvate dehydrogenase complex but have preserved the degradation of branched-chain amino acids (BCAA) as a possible pathway to generate acetyl-CoA. Importantly, degradation of leucine, isoleucine and valine could lead to concomitant accumulation of propionyl-CoA, a toxic metabolite that inhibits cell growth. Like fungi and bacteria, the Coccidia possess the complete set of enzymes necessary to metabolize and detoxify propionate by oxidation to pyruvate via the 2-methylcitrate cycle (2-MCC). Phylogenetic analysis provides evidence that the 2-MCC was acquired via horizontal gene transfer. In T. gondii tachyzoites, this pathway is split between the cytosol and the mitochondrion. Although the rate-limiting enzyme 2-methylisocitrate lyase is dispensable for parasite survival, its substrates accumulate in parasites deficient in the enzyme and its absence confers increased sensitivity to propionic acid. BCAA is also dispensable in tachyzoites, leaving unresolved the source of mitochondrial acetyl-CoA. PMID:23279335

Limenitakis, Julien; Oppenheim, Rebecca D; Creek, Darren J; Foth, Bernardo J; Barrett, Michael P; Soldati-Favre, Dominique

2013-01-01

414

Mechanism and kinetic studies for OH radical-initiated atmospheric oxidation of methyl propionate  

NASA Astrophysics Data System (ADS)

DFT molecular orbital theory calculations were carried out to investigate OH radical-initiated atmospheric oxidation of methyl propionate. Geometry optimizations of the reactants as well as the intermediates, transition states and products were performed at the B3LYP/6-31G(d,p) level. As the electron correlation and basis set effect, the single-point energies were computed by using various levels of theory, including second-order Møller-Plesset perturbation theory (MP2) and the coupled-cluster theory with single and double excitations including perturbative corrections for the triple excitations (CCSD(T)). The detailed oxidation mechanism is presented and discussed. The results indicate that the formation of 3-oxo-methyl propionate (HC(O)CH2C(O)OCH3) is thermodynamically feasible and the isomerization of alkoxy radical IM17 (CH3CH(O)C(O)OCH3) can occur readily under the general atmospheric conditions. Canonical variational transition-state (CVT) theory with small curvature tunneling (SCT) contribution was used to predict the rate constants. The overall rate constants were determined, k(T)(CH3CH2COOCH3 + OH) = (1.35 × 10-12)exp(-174.19/T) cm3 molecule-1 s-1, over the possible atmospheric temperature range of 180-370 K.

Sun, Xiaoyan; Hu, Yueming; Xu, Fei; Zhang, Qingzhu; Wang, Wenxing

2012-12-01

415

Proposed guidelines for the diagnosis and management of methylmalonic and propionic acidemia.  

PubMed

Methylmalonic and propionic acidemia (MMA/PA) are inborn errors of metabolism characterized by accumulation of propionic acid and/or methylmalonic acid due to deficiency of methylmalonyl-CoA mutase (MUT) or propionyl-CoA carboxylase (PCC). MMA has an estimated incidence of?~?1: 50,000 and PA of?~?1:100'000 -150,000. Patients present either shortly after birth with acute deterioration, metabolic acidosis and hyperammonemia or later at any age with a more heterogeneous clinical picture, leading to early death or to severe neurological handicap in many survivors. Mental outcome tends to be worse in PA and late complications include chronic kidney disease almost exclusively in MMA and cardiomyopathy mainly in PA. Except for vitamin B12 responsive forms of MMA the outcome remains poor despite the existence of apparently effective therapy with a low protein diet and carnitine. This may be related to under recognition and delayed diagnosis due to nonspecific clinical presentation and insufficient awareness of health care professionals because of disease rarity. PMID:25205257

Baumgartner, Matthias R; Hörster, Friederike; Dionisi-Vici, Carlo; Haliloglu, Goknur; Karall, Daniela; Chapman, Kimberly A; Huemer, Martina; Hochuli, Michel; Assoun, Murielle; Ballhausen, Diana; Burlina, Alberto; Fowler, Brian; Grünert, Sarah C; Grünewald, Stephanie; Honzik, Tomas; Merinero, Begoña; Pérez-Cerdá, Celia; Scholl-Bürgi, Sabine; Skovby, Flemming; Wijburg, Frits; MacDonald, Anita; Martinelli, Diego; Sass, Jörn Oliver; Valayannopoulos, Vassili; Chakrapani, Anupam

2014-01-01

416

Co-cultivation of Lactobacillus zeae?and Veillonella cricetifor the production of propionic acid  

PubMed Central

In this work a defined co-culture of the lactic acid bacterium Lactobacillus zeae?and the propionate producer Veillonella criceti?has been studied in continuous stirred tank reactor (CSTR) and in a dialysis membrane reactor. It is the first time that this reactor type is used for a defined co-culture fermentation. This reactor allows high mixing rates and working with high cell densities, making it ideal for co-culture investigations. In CSTR experiments the co-culture showed over a broad concentration range an almost linear correlation in consumption and production rates to the supply with complex nutrients. In CSTR and dialysis cultures a strong growth stimulation of L. zeae?by V. criceti?was shown. In dialysis cultures very high propionate production rates (0.61 g L-1h-1) with final titers up to 28 g L-1?have been realized. This reactor allows an individual, intracellular investigation of the co-culture partners by omic-technologies to provide a better understanding of microbial communities. PMID:23705662

2013-01-01

417

A new procedure for the destructuring of vegetable matter at atmospheric pressure by a catalyst\\/solvent system of formic acid\\/acetic acid.Applied to the pulping of triticale straw  

Microsoft Academic Search

The selective separation of cellulose, hemicelluloses and lignin of triticale straw is achieved, at atmospheric pressure, using a mixture of formic acid\\/acetic acid\\/water. The chemical and mechanical characteristics of the obtained pulp are good. The majority of the silica derivatives are retained in the pulp because of the acidic cooking conditions. The cooking agents are easily recyclable without combustion of

Hoang Quoc Lam; Yves Le Bigot; Michel Delmas; Gérard Avignon

2001-01-01

418

Stable Coexistence of Five Bacterial Strains as a Cellulose-Degrading Community  

PubMed Central

A cellulose-degrading defined mixed culture (designated SF356) consisting of five bacterial strains (Clostridium straminisolvens CSK1, Clostridium sp. strain FG4, Pseudoxanthomonas sp. strain M1-3, Brevibacillus sp. strain M1-5, and Bordetella sp. strain M1-6) exhibited both functional and structural stability; namely, no change in cellulose-degrading efficiency was observed, and all members stably coexisted through 20 subcultures. In order to investigate the mechanisms responsible for the observed stability, “knockout communities” in which one of the members was eliminated from SF356 were constructed. The dynamics of the community structure and the cellulose degradation profiles of these mixed cultures were determined in order to evaluate the roles played by each eliminated member in situ and its impact on the other members of the community. Integration of each result gave the following estimates of the bacterial relationships. Synergistic relationships between an anaerobic cellulolytic bacterium (C. straminisolvens CSK1) and two strains of aerobic bacteria (Pseudoxanthomonas sp. strain M1-3 and Brevibacillus sp. strain M1-5) were observed; the aerobes introduced anaerobic conditions, and C. straminisolvens CSK1 supplied metabolites (acetate and glucose). In addition, there were negative relationships, such as the inhibition of cellulose degradation by producing excess amounts of acetic acid by Clostridium sp. strain FG4, and growth suppression of Bordetella sp. strain M1-6 by Brevibacillus sp. strain M1-5. The balance of the various types of relationships (both positive and negative) is thus considered to be essential for the stable coexistence of the members of this mixed culture. PMID:16269746

Kato, Souichiro; Haruta, Shin; Cui, Zong Jun; Ishii, Masaharu; Igarashi, Yasuo

2005-01-01

419

Metaproteomics of cellulose methanisation under thermophilic conditions reveals a surprisingly high proteolytic activity  

PubMed Central

Cellulose is the most abundant biopolymer on Earth. Optimising energy recovery from this renewable but recalcitrant material is a key issue. The metaproteome expressed by thermophilic communities during cellulose anaerobic digestion was investigated in microcosms. By multiplying the analytical replicates (65 protein fractions analysed by MS/MS) and relying solely on public protein databases, more than 500 non-redundant protein functions were identified. The taxonomic community structure as inferred from the metaproteomic data set was in good overall agreement with 16S rRNA gene tag pyrosequencing and fluorescent in situ hybridisation analyses. Numerous functions related to cellulose and hemicellulose hydrolysis and fermentation catalysed by bacteria related to Caldicellulosiruptor spp. and Clostridium thermocellum were retrieved, indicating their key role in the cellulose-degradation process and also suggesting their complementary action. Despite the abundance of acetate as a major fermentation product, key methanogenesis enzymes from the acetoclastic pathway were not detected. In contrast, enzymes from the hydrogenotrophic pathway affiliated to Methanothermobacter were almost exclusively identified for methanogenesis, suggesting a syntrophic acetate oxidation process coupled to hydrogenotrophic methanogenesis. Isotopic analyses confirmed the high dominance of the hydrogenotrophic methanogenesis. Very surprising was the identification of an abundant proteolytic activity from Coprothermobacter proteolyticus strains, probably acting as scavenger and/or predator performing proteolysis and fermentation. Metaproteomics thus appeared as an efficient tool to unravel and characterise metabolic networks as well as ecological interactions during methanisation bioprocesses. More generally, metaproteomics provides direct functional insights at a limited cost, and its attractiveness should increase in the future as sequence databases are growing exponentially. PMID:23949661

Lü, Fan; Bize, Ariane; Guillot, Alain; Monnet, Véronique; Madigou, Céline; Chapleur, Olivier; Mazéas, Laurent; He, Pinjing; Bouchez, Théodore

2014-01-01

420

Metaproteomics of cellulose methanisation under thermophilic conditions reveals a surprisingly high proteolytic activity.  

PubMed

Cellulose is the most abundant biopolymer on Earth. Optimising energy recovery from this renewable but recalcitrant material is a key issue. The metaproteome expressed by thermophilic communities during cellulose anaerobic digestion was investigated in microcosms. By multiplying the analytical replicates (65 protein fractions analysed by MS/MS) and relying solely on public protein databases, more than 500 non-redundant protein functions were identified. The taxonomic community structure as inferred from the metaproteomic data set was in good overall agreement with 16S rRNA gene tag pyrosequencing and fluorescent in situ hybridisation analyses. Numerous functions related to cellulose and hemicellulose hydrolysis and fermentation catalysed by bacteria related to Caldicellulosiruptor spp. and Clostridium thermocellum were retrieved, indicating their key role in the cellulose-degradation process and also suggesting their complementary action. Despite the abundance of acetate as a major fermentation product, key methanogenesis enzymes from the acetoclastic pathway were not detected. In contrast, enzymes from the hydrogenotrophic pathway affiliated to Methanothermobacter were almost exclusively identified for methanogenesis, suggesting a syntrophic acetate oxidation process coupled to hydrogenotrophic methanogenesis. Isotopic analyses confirmed the high dominance of the hydrogenotrophic methanogenesis. Very surprising was the identification of an abundant proteolytic activity from Coprothermobacter proteolyticus strains, probably acting as scavenger and/or predator performing proteolysis and fermentation. Metaproteomics thus appeared as an efficient tool to unravel and characterise metabolic networks as well as ecological interactions during methanisation bioprocesses. More generally, metaproteomics provides direct functional insights at a limited cost, and its attractiveness should increase in the future as sequence databases are growing exponentially. PMID:23949661

Lü, Fan; Bize, Ariane; Guillot, Alain; Monnet, Véronique; Madigou, Céline; Chapleur, Olivier; Mazéas, Laurent; He, Pinjing; Bouchez, Théodore

2014-01-01

421

Contribution of dialysate acetate to energy metabolism: Metabolic implications  

Microsoft Academic Search

Contribution of dialysate acetate to energy metabolism: Metabolic implications. During hemodialysis large amounts of acetate enter the bloodstream. Generally, it is assumed that this exogenous acetate load is oxidized immediately to carbon dioxide and water; however, the rate of plasma acetate oxidation and the effect of acetate oxidation on energy metabolism during hemodialysis has not been determined previously. The rates

Charles L Skutches; Miles H Sigler; Brendan P Teehan; Joseph H Cooper; George A Reichard

1983-01-01

422

Novel Cellulose Nanoparticles for Potential Cosmetic and Pharmaceutical Applications.  

E-print Network

??Cellulose is one of the most abundant biopolymers found in nature. Cellulose based derivatives have a number of advantages including recyclability, reproducibility, biocompatibility, biodegradability, cost… (more)

Dhar, Neha

2010-01-01

423

Milk fat content was changed by ruminal infusion of mixed VFAs solutions with different acetate\\/propionate ratios in lactating goats  

Microsoft Academic Search

Although it is well documented that conjugated linoleic acids (CLA), such as trans-10, cis-12CLA are potent inhibitors of milk fat synthesis, there might be other factors that could depress milk fat synthesis. Previous studies revealed that milk fat synthesis of dairy goats was not depressed by supplementing with either vegetable oil or fish oil [Morand-Fehr, P., Sauvant, D., Bas, P.,

B. Li; Z. H. Wang; F. C. Li; X. Y. Lin

2007-01-01

424

Heterologous enzyme immunoassay for the determination of free indole-3-acetic acid (IAA) using antibodies against ring-linked IAA.  

PubMed

A solid phase indirect enzyme immunoassay method for the plant growth substance indole-3-acetic acid (IAA) using polyclonal antibodies raised to IAA linked to rabbit serum albumin (RSA) is described. The sensitivity for IAA increased by more than three orders of magnitude as the number of IAA ligands on the coating antigen decreased. Further improvements in assay sensitivity were limited by the high affinity of the antibodies for the bridge group in the IAA conjugate. Substitution of the IAA in the coating antigen by either indole-3-propionic acid or indole-3-lactic acid reduced antibody recognition of the bridge group. The resulting heterologous assay compares favourably with existing homologous immunoassays for IAA in terms of sensitivity and specificity. PMID:1995713

Manning, K

1991-01-24

425

Once daily intranasal fluticasone propionate (200 ?g) reduces nasal symptoms and inflammation but also attenuates the increase in bronchial responsiveness during the pollen season in allergic rhinitis  

Microsoft Academic Search

BACKGROUND: Fluticasone propionate aqueous nasal spray, a new topical corticosteroid, has been proved to be an effective treatment for seasonal allergic rhinitis. OBJECTIVES: We studied the effect of fluticasone propionate on nasal symptoms, circulating eosinophils, and nasal inflammation in patients with seasonal allergic rhinitis after high-load pollen exposure. Moreover, we examined its efficacy in preventing the increase in bronchial responsiveness

Antonio Foresi; Andrea Pelucchi; Gemma Gherson; Berardino Mastropasqua; Anita Chiapparino; Renato Testi

1996-01-01

426

Photoresponsive cellulose fibers by surface modification with multifunctional cellulose derivatives.  

PubMed

Eucalyptus bleached kraft pulp fibers were modified by adsorption of novel bio-based multifunctional cellulose derivatives in order to generate light responsive surfaces. The cellulose derivatives used were decorated with both cationic groups (degree of substitution, DS of 0.34) and photoactive groups (DS of 0.11 and 0.37). The adsorption was studied by UV-vis spectroscopy, surface plasmon resonance (SPR) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The adsorption isotherms followed the Freundlich model and it turned out that the main driving force for the adsorption was electrostatic interaction. Moreover, strong indications for hydrophobic interactions between the fibers and the derivatives and the derivatives themselves were found. ToF-SIMS imaging revealed an even distribution of the derivatives on the fiber surfaces. The modified fibers underwent fast photocrosslinking under UV-irradiation as demonstrated by light absorbance and fluorescence measurements. Thus, our results proved that the modified fibers exhibited light-responsive properties and can potentially be used for the manufacture of smart bio-based materials. PMID:25037353

Grigoray, Olga; Wondraczek, Holger; Heikkilä, Elina; Fardim, Pedro; Heinze, Thomas

2014-10-13

427

Effect of rheological properties of dissolved cellulose/microfibrillated cellulose blend suspensions on film forming.  

PubMed

Enzymatically treated cellulose was dissolved in a NaOH/ZnO solvent system and mixed together with microfibrillated cellulose (MFC) in order to find the threshold in which MFC fibers form a percolation network within the dissolved cellulose solution and in order to improve the properties of regenerated cellulose films. In the aqueous state, correlations between the rheological properties of dissolved cellulose/MFC blend suspensions and MFC fiber concentrations were investigated and rationalized. In addition, rheological properties of diluted MFC suspensions were characterized and a correlation with NaOH concentration was found, thus partly explaining the flow properties of dissolved cellulose/MFC blend suspensions. Finally, based on results from Dynamic Mechanical Analysis (DMA), MFC addition had strengthening/plasticizing effect on regenerated cellulose films if low concentrations of MFC, below the percolation threshold (5.5-6 wt%, corresponding to 0.16-0.18 wt% of MFC in the blend suspensions), were used. PMID:25563945

Saarikoski, Eve; Rissanen, Marja; Seppälä, Jukka

2015-03-30

428

The preparation of graft copolymers of cellulose and cellulose derivatives using ATRP under homogeneous reaction conditions.  

PubMed

In this comprehensive review, we report on the preparation of graft-copolymers of cellulose and cellulose derivatives using atom transfer radical polymerization (ATRP) under homogeneous conditions. The review is divided into four sections according to the cellulosic material that is graft-copolymerised; (i) cellulose, (ii) ethyl cellulose, (iii) hydroxypropyl cellulose and (iv) other cellulose derivatives. In each section, the grafted synthetic polymers are described as well as the methods used for ATRP macro-initiator formation and graft-copolymerisation. The physical properties of the graft-copolymers including their self-assembly in solution into nanostructures and their stimuli responsive behaviour are described. Potential applications of the self-assembled graft copolymers in areas such as nanocontainers for drug delivery are outlined. PMID:25016958

Joubert, Fanny; Musa, Osama M; Hodgson, David R W; Cameron, Neil R

2014-10-21

429

Desvenlafaxinium chloranilate ethyl acetate solvate  

PubMed Central

In the cation of the title compound, C16H26NO2 +·C6HCl2O4 ?·C4H8O2, the 1-hy­droxy-cyclo­hexyl ring adopts a slightly distorted chair conformation. The dihedral angle between the mean planes of the 1-hy­droxy­cyclo­hexyl and 4-hy­droxy­phenyl rings is 84.0?(8)°. In the anion, the hydroxyl H atom is twisted slightly out of the ring plane with a C—C—O—H torsion angle of ?171.9°. Disorder was modeled for the methyl group of the acetate group in the solvate with an occupancy ratio of 0.583?(15): 0.417?(15). In the crystal, O—H?O hydrogen bonds are observed between cations and between cations and anions, while bifuricated N—H?(O,O) cation–anion hydrogen bonds are also present, forming chains along [010] and [100]. In addition weak cation–anion and cation–solvate C—H?O inter­actions occur. PMID:24098238

Kaur, Manpreet; Jasinski, Jerry P.; Butcher, Ray J.; Yathirajan, H. S.; Byrappa, K.

2013-01-01

430

Selective solvent extraction of cellulosic material  

DOEpatents

Cellulosic products having a high hemicellulose to lignin weight ratio are obtained by extracting a cellulosic composition with basic ethanol-water solution having a pH between about 12 and about 14 at a temperature between about 15 and about 70 C and for a time period between about 2 and about 80 hours. 6 figs.

Wang, D.I.C.; Avgerinos, G.C.

1983-07-26

431

Idealized powder diffraction patterns for cellulose polymorphs  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been determined with synchrotron X-radiation and neutron diffrac...

432

Nucleic acids encoding a cellulose binding domain  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc A. (Davis, CA); Doi, Roy H. (Davis, CA)

1996-01-01

433

Ultrastructural aspects of the acetylation of cellulose  

Microsoft Academic Search

An ultrastructural study of the acetylation of cellulose was achieved by subjecting well characterized cellulose samples fromValonia cell wall and tunicin tests to homogeneous and heterogeneous acetylation. The study involved transmission electron microscopy observations on negatively stained microcrystals as well as diffraction contrast images of the cross sections of wall fragments at various stages of the reaction. These observations showed

Jean-François Sassi; Henri Chanzy

1995-01-01

434

Cellulose Triacetate Dielectric Films For Capacitors  

NASA Technical Reports Server (NTRS)

Cellulose triacetate investigated for use as dielectric material in high-energy-density capacitors for pulsed-electrical-power systems. Films of cellulose triacetate metalized on one or both sides for use as substrates for electrodes and/or as dielectrics between electrodes in capacitors. Used without metalization as simple dielectric films. Advantages include high breakdown strength and self-healing capability.

Yen, Shiao-Ping S.; Jow, T. Richard

1994-01-01

435

BIOCOMPOSITE MATERIALS – INSPIRATIONAL CONCEPTS USING CELLULOSE NANOFIBERS  

E-print Network

Biocomposite materials based on cellulose are of great interest, often due to their renewable resource origin. The present review discusses some concepts leading to biocomposites of high performance. Cellulose is the fibrous reinforcement phase of the cell walls in plant tissue. It is present in the form of ”microfibrils”, a form of nanofiber with a diameter in the

Lars A. Berglund

436

Nematic Ordered Cellulose: Its Structure and Properties  

Microsoft Academic Search

The authors developed a unique form of ?-glucan association, “nematic ordered cellulose” (NOC) that is molecularly ordered, yet noncrystalline. NOC has unique characteristics; in particular, its surface properties provide with a function of tracks or scaffolds for regulated movements and fiber production of Acetobacter xylinum (=Gluconacetobacter xylinus), which produces cellulose ribbon-like nanofibers with 40–60 nm in width and moves due

Tetsuo Kondo

437

Reversible precipitation of proteins on carboxymethyl cellulose  

Microsoft Academic Search

Precipitation, one of the steps used most routinely in protein purifications, suffers from a general lack of selectivity. In an attempt to impart controllable selectivity of a definite nature, carboxymethyl cellulose was developed as a soluble ion-exchange precipitant for isolation and purification of proteins. Carboxymethyl cellulose was used as a reversibly soluble\\/insoluble ion exchange matrix, which after binding proteins from

Arvind Lali; Aruna N; Roshnnie John; Devika Thakrar

2000-01-01

438

Enzymatic degradation of (ligno)cellulose.  

PubMed

Glycoside-degrading enzymes play a dominant role in the biochemical conversion of cellulosic biomass into low-price biofuels and high-value-added chemicals. New insight into protein functions and substrate structures, the kinetics of recognition, and degradation events has resulted in a substantial improvement of our understanding of cellulose degradation. PMID:25136976

Bornscheuer, Uwe; Buchholz, Klaus; Seibel, Jürgen

2014-10-01

439

Effect of sulfur-containing compounds on anaerobic degradation of cellulose to methane by mixed cultures obtained from sewage sludge.  

PubMed Central

Tests were made to determine the effects of inorganic and organic sulfur sources on the degradation of cellulose to methane in a chemically defined medium with sulfur-poor inoculum prepared from sewage sludge. The results show that a sulfur source of about a 0.85 mM concentration is essential for the degradation of cellulose to CH4. However, the production of CH4 from CO2 and H2 provided in the headspace occurred with 0.1 mM sulfate or sulfide. At a 9 mM concentration, all inorganic sulfur compounds other than sulfate inhibited both cellulose degradation and methane formation, and this inhibition increased in the order thiosulfate less than sulfite less than sulfide less than H2S. It appears that the degradation of cellulose to CH4 in a sulfate-free medium by inoculum maintained in a low-sulfur medium is inhibited because of the lack of availability of sulfur for growth of bacteria and synthesis of cell materials and sulfur-containing cofactors involved in cellulose degradation and methanogenesis. The reduction of methanogenesis by higher levels of sulfate probably occurs as a result of stimulation of reactions converting acetate and H2 to end products other than CH4. PMID:677869

Khan, A W; Trottier, T M

1978-01-01

440

Solid-, solution-, and gas-state NMR monitoring of ¹³C-cellulose degradation in an anaerobic microbial ecosystem.  

PubMed

Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. ¹³C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and ¹³C-¹³C/¹³C-¹²C isotopomers in the microbial degradation of ¹³C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid. PMID:23899835

Yamazawa, Akira; Iikura, Tomohiro; Shino, Amiu; Date, Yasuhiro; Kikuchi, Jun

2013-01-01

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