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1

Electrical Conduction Mechanism and Optical Properties of Polyvinyl Acetate and Cellulose Acetate Propionate Blends  

NASA Astrophysics Data System (ADS)

Films of Polyvinyl acetate (PVAc), cellulose acetate propionate (CAP) homopolymers and their blends of compositions 0.85/0.15, 0.7/0.3, 0.5/0.5, 0.3/0.7 and 0.15/0.85 (wt/wt) were prepared to investigate the type of electrical conduction mechanism. The current-voltage characteristics have been studied under different conditions. Also, ultraviolet/visible spectra of all samples have been studied according to their different composition ratios. The conduction mechanisms at different temperatures and voltage ranges appear to be essentially a space charge limited current for the two individual polymers, while for the blend samples the predominance mechanism is Poole-Frenkel type. Ultraviolet/visible studies of the investigated samples showed that the blend sample of 0.5/0.5 (wt/wt) has the smallest absorption edge (4.58 eV) and highest band tail (0.61 eV). The composition blend sample 0.5/0.5 (wt/wt) has the most proper conduction and optical properties which has attractive attention in the view of its application in electronic and optical devices.

Abd El-Kader, F. H.; Shehap, A. M.; Basha, A. F.; El-Fewaty, N. H.

2011-06-01

2

Inhibition of the Fermentation of Propionate to Methane by Hydrogen, Acetate, and Propionate  

PubMed Central

Inhibition of the fermentation of propionate to methane and carbon dioxide by hydrogen, acetate, and propionate was analyzed with a mesophilic propionate-acclimatized sludge that consisted of numerous flocs (size, 150 to 300 ?m). The acclimatized sludge could convert propionate to methane and carbon dioxide stoichiometrically without accumulating hydrogen and acetate in a propionate-minimal medium. Inhibition of propionate utilization by propionate could be analyzed by a second-order substrate inhibition model (shown below) given that the substrate saturation constant, Ks, was 15.9 ?M; the substrate inhibition constant, Ki, was 0.79 mM; and the maximum specific rate of propionate utilization, qm, was 2.15 mmol/g of mixed-liquor volatile suspended solids (MLVSS) per day: qs = qmS/[Ks + S + (S2/Ki)], where qs is the specific rate of propionate utilization and S is the initial concentration of undissociated propionic acid. For inhibition by hydrogen and acetate to propionate utilization, a noncompetitive product inhibition model was used: qs = qm/[1 + (P/Kp)n], where P is the initial concentration of hydrogen or undissociated acetic acid and Kp is the inhibition constant. Kinetic analysis gave, for hydrogen inhibition, Kp(H2) = 0.11 atm (= 11.1 kPa, 71.5 ?M), qm = 2.40 mmol/g of MLVSS per day, and n = 1.51 and, for acetate inhibition, Kp(HAc) = 48.6 ?M, qm = 1.85 mmol/g of MLVSS per day, and n = 0.96. It could be concluded that the increase in undissociated propionic acid concentration was a key factor in inhibition of propionate utilization and that hydrogen and acetate cooperatively inhibited propionate degradation, suggesting that hydrogenotrophic and acetoclastic methanogens might play an important role in enhancing propionate degradation to methane and carbon dioxide.

Fukuzaki, Satoshi; Nishio, Naomichi; Shobayashi, Manabu; Nagai, Shiro

1990-01-01

3

Characteristics of thin cellulose ester films spin-coated from acetone and ethyl acetate solutions  

Microsoft Academic Search

Spin-coated films of cellulose acetate (CA), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB) and carboxymethylcellulose\\u000a acetate butyrate (CMCAB) have been characterized by ellipsometry, atomic force microscopy (AFM) and contact angle measurements.\\u000a The films were spin-coated onto silicon wafers, a polar surface. Mean thickness values were determined by means of ellipsometry\\u000a and AFM as a function of polymer concentration in

J. Amim Jr; P. M. Kosaka; D. F. S. Petri

2008-01-01

4

Effects of acetate, propionate, and butyrate on the thermophilic anaerobic degradation of propionate by methanogenic sludge and defined cultures.  

PubMed Central

The effects of acetate, propionate, and butyrate on the anaerobic thermophilic conversion of propionate by methanogenic sludge and by enriched propionate-oxidizing bacteria in syntrophy with Methanobacterium thermoautotrophicum delta H were studied. The methanogenic sludge was cultivated in an upflow anaerobic sludge bed (UASB) reactor fed with propionate (35 mM) as the sole substrate for a period of 80 days. Propionate degradation was shown to be severely inhibited by the addition of 50 mM acetate to the influent of the UASB reactor. The inhibitory effect remained even when the acetate concentration in the effluent was below the level of detection. Recovery of propionate oxidation occurred only when acetate was omitted from the influent medium. Propionate degradation by the methanogenic sludge in the UASB reactor was not affected by the addition of an equimolar concentration (35 mM) of butyrate to the influent. However, butyrate had a strong inhibitory effect on the growth of the propionate-oxidizing enrichment culture. In that case, the conversion of propionate was almost completely inhibited at a butyrate concentration of 10 mM. However, addition of a butyrate-oxidizing enrichment culture abolished the inhibitory effect, and propionate oxidation was even stimulated. All experiments were conducted at pH 7.0 to 7.7. The thermophilic syntrophic culture showed a sensitivity to acetate and propionate similar to that of mesophilic cultures described in the literature. Additions of butyrate or acetate to the propionate medium had no effect on the hydrogen partial pressure in the biogas of an UASB reactor, nor was the hydrogen partial pressure in propionate-degrading cultures affected by the two acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Van Lier, J B; Grolle, K C; Frijters, C T; Stams, A J; Lettinga, G

1993-01-01

5

Pathways of acetate, propionate, and butyrate formation by the human fecal microbial flora.  

PubMed

The pathways of short-chain fatty acid (SCFA; acetate, propionate, and butyrate) formation from glucose were determined for the human fecal microbial communities of two subjects. The pathways were identified by radioisotope analysis of the SCFA and CO2 obtained after incubation of fecal suspensions with glucose under 20% CO2 with [1-14C]glucose, [3,4-14C]glucose, or 14CO2. Acetate was chemically degraded to learn the labeling of the methyl and carboxyl carbons. The labeling of CO2 and acetate showed that the major route of glucose catabolism was the Embden-Meyerhof-Parnas pathway, with production of CO2 from pyruvate carboxyl carbon. Labeling of the methyl and carboxyl carbons of acetate by 14CO2 or [3,4-14C]glucose proved that acetate was formed from CO2 by the Wood-Ljungdahl pathway. CO2 reduction accounted for about one-third of the acetate formed by suspensions from subject 1 and about one-fourth of the acetate formed by suspensions from subject 2. Propionate was formed by a CO2 fixation pathway, and butyrate was formed by classical routes of acetyl-S coenzyme A condensation. The amount of CO2 formed from [1-14C] glucose and acetate labeling patterns obtained with the other 14C precursors indicated that the Entner-Doudoroff, transketolase-transaldolase, and heterolactic pathways were not significant. Fermentation of cabbage cellulose by subject 1 followed the same pathways as were used for glucose. The results with suspensions from subject 2 suggested that some radioactive acetate was formed from the C-3 of glucose by the Bifidobacterium pathway. PMID:8633856

Miller, T L; Wolin, M J

1996-05-01

6

Inhibition of propionate degradation by acetate in methanogenic fluidized bed reactors  

Microsoft Academic Search

Summary The degradation of acetate, propionate and butyrate was monitored during start-up of five lab-scale methanogenic fluidized bed reactors on an artificially prepared waste water. The acetate concentration in the reactor content was found to influence the degradation of propionate but not of butyrate. In general, at acetate levels over 200 mg\\/l the degradation of propionate was below 60%, whereas

L G M Gorris; J M A van Deursen; C van der Drift; G D Vogels

1989-01-01

7

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

8

Synthesis of Cellulose Acetate from Cotton Byproducts  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cotton burr and cottonseed hull are relatively inexpensive cotton byproducts. In an effort to derive greater value out of these natural renewable materials, we have succeeded in converting part of them into cellulose acetate without prior chemical breakdown or physical separation of cellulose, ligni...

9

Reversible acetylation regulates acetate and propionate metabolism in Mycobacterium smegmatis.  

PubMed

Carbon metabolic pathways are important to the pathogenesis of Mycobacterium tuberculosis, the causative agent of tuberculosis. However, extremely little is known about metabolic regulation in mycobacteria. There is growing evidence for lysine acetylation being a mechanism of regulating bacterial metabolism. Lysine acetylation is a post-translational modification in which an acetyl group is covalently attached to the side chain of a lysine residue. This modification is mediated by acetyltransferases, which add acetyl groups, and deacetylases, which remove the acetyl groups. Here we set out to test whether lysine acetylation and deacetylation impact acetate metabolism in the model mycobacteria Mycobacterium smegmatis, which possesses 25 candidate acetyltransferases and 3 putative lysine deacetylases. Using mutants lacking predicted acetyltransferases and deacetylases we showed that acetate metabolism in M. smegmatis is regulated by reversible acetylation of acetyl-CoA synthetase (Ms-Acs) through the action of a single pair of enzymes: the acetyltransferase Ms-PatA and the sirtuin deacetylase Ms-SrtN. We also confirmed that the role of Ms-PatA in regulating Ms-Acs regulation depends on cAMP binding. We additionally demonstrated a role for Ms-Acs, Ms-PatA and Ms-SrtN in regulating the metabolism of propionate in M. smegmatis. Finally, along with Ms-Acs, we identified a candidate propionyl-CoA synthetase, Ms5404, as acetylated in whole-cell lysates. This work lays the foundation for studying the regulatory circuit of acetylation and deacetylation in the cellular context of mycobacteria. PMID:23813678

Hayden, Jennifer D; Brown, Lanisha R; Gunawardena, Harsha P; Perkowski, Ellen F; Chen, Xian; Braunstein, Miriam

2013-06-27

10

36 CFR 1232.24 - Unstable cellulose-acetate film.  

Code of Federal Regulations, 2010 CFR

...Public Property 3 2009-07-01 2009-07-01 false Unstable cellulose-acetate film. 1232.24 Section 1232.24...MANAGEMENT Audiovisual Records Management § 1232.24 Unstable cellulose-acetate film. Cellulose-acetate film,...

2009-07-01

11

Assessment Guidelines for Managing Cellulose Acetate Collections  

NSDL National Science Digital Library

Photographic negatives, motion picture film, microfilm, and sound recordings produced from the 1930s into the 1950s often used cellulose acetate as the transparent plastic carrier. As anyone who has ever come in contact with it well knows, its strong vinegar-like scent is hard to miss. Unfortunately, over time, the material is prone to deterioration, which eventually renders it unusable. In an effort to help guide libraries in Australia with this problem, the National Library of Australia has created this document. It provides assistance in identification of cellulose acetate (vs. other similar materials) and establishes criteria to assess condition, cultural importance, and use within the library or storage context. The document guides readers through the first step in a strategy for preserving these collections.

2001-01-01

12

Two-stage fermentation process for the production of calcium magnesium acetate and propionate road deicers  

Microsoft Academic Search

Calcium magnesium acetate (CMA) and propionate (CMP) are environmentally benign deicing chemicals that can replace sodium chloride that is widely used on roads and highways at present for snow and ice control to provide safe driving conditions during winter. The price of CMA from petroleum-derived acetic acid is quite expensive. Anaerobic fermentations have not proven economical due to the low

Wenge Fu; Alexander P. Mathews

2005-01-01

13

Micro-mold fabrication using cellulose acetate  

NASA Astrophysics Data System (ADS)

Polymer materials offer numerous advantages including flexible, low cost large area displays, lightweight, easy processing, good compatibility with a variety of substrates, and easy for structural modifications. Recently electro-active polymers (EAP) have been attractive due to their potential advantages including ease of processing and control, mechanical flexibility, and economical advantage. Recently electro-active paper (EAPap) was discovered as a smart material and as an actuating material with ionic and piezoelectric effects. Before cellulose acetate (CA) micro-pattern fabrication, solvent effect of micro or nano-pore formation was investigated. Since the micropore scatter the visible light, micropores give negative effect to apply optical device. The solvent mixture of acetone/dimethylacetamide (DMAc) created large amount of micro or nanopores. The resulting films were not transparent. However, volatile single solvent (acetone) did not form pores and gave transparent film. The various shapes of photoresist, such as circle and honeycomb patterns, were fabricated onto the silicon wafer to use as the mold. Cellulose acetate (CA) was poured to the mold and peeled off from the mold. The resulting pattern exhibited uniform size of the circle or honeycomb shape without defect.

Cho, K. Y.; Lim, H. K.; Chen, Y.; Kim, Jaehwan; Kang, K. S.

2007-04-01

14

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

15

Pathways of Acetate, Propionate, and Butyrate Formation by the Human Fecal Microbial Flora  

Microsoft Academic Search

The pathways of short-chain fatty acid (SCFA; acetate, propionate, and butyrate) formation from glucose were determined for the human fecal microbial communities of two subjects. The pathways were identified by radioisotope analysis of the SCFA and CO2obtained after incubation of fecal suspensions with glucose under 20% CO2 with (1- 14 C)glucose, (3,4- 14 C)glucose, or 14 CO2. Acetate was chemically

TERRY L. MILLER; ANDMEYER J. WOLIN

1996-01-01

16

Highly conductive composites of polyaniline with plasticized cellulose acetate  

Microsoft Academic Search

Highly transparent, conductive blends can be prepared from plasticized cellulose acetate and polyaniline protonated with sulphonic acids, phosphonic acids and phosphoric acid diesters. Films cast from m-cresol solution exhibit percolation threshold below 0.5 wt% and excellent mechanical properties of plasticized cellulose acetate.

A. Pro?; M. Zagorska; Y. Nicolau; F. Genoud; M. Nechtschein

1997-01-01

17

Effects of calcium concentration, acetate, and propionate on calcium absorption in the human distal colon  

Microsoft Academic Search

Previous studies have shown that the short-chain fatty acids acetate (Ac) and propionate (Pr) enhance the absorption of calcium (Ca) in the rectum and distal colon of humans, with Pr being more effective than Ac. To investigate the effect of Ac and Pr on the kinetics of Ca absorption from the human rectum and distal colon, six healthy subjects were

Trinidad P Trinidad; Thomas M. S Wolever; Lilian U Thompson

1999-01-01

18

The Interactions of Cellulose Acetate and Ethyl Cellulose Inhibitors with Double-Base Propellants.  

National Technical Information Service (NTIS)

The interactions of nitroglycerine in double-base propellants with the inhibition materials cellulose acetate and ethyl cellulose are described. The distribution of nitroglycerine within the inhibitor and the effects of time, temperature, nitrocellulose c...

R. Stenson

1971-01-01

19

Water dispersible microbicidal cellulose acetate phthalate film  

PubMed Central

Background Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. Methods CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. Results The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ?50 to ?65% ethanol (EtOH). The films are ?100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. Conclusions Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP.

Neurath, A Robert; Strick, Nathan; Li, Yun-Yao

2003-01-01

20

Vapor–liquid equilibria in the ternary system isobutyl alcohol + isobutyl acetate + butyl propionate and the binary systems isobutyl alcohol + butyl propionate, isobutyl acetate + butyl propionate at 101.3 kPa  

Microsoft Academic Search

Consistent vapor–liquid equilibrium (VLE) data at 101.3kPa have been determined for the ternary system isobutyl alcohol (IBA)+isobutyl acetate (IBAc)+butyl propionate (BUP) and two constituent binary systems: IBA+BUP and IBAc+BUP. The IBA+BUP system show lightly positive deviation from Raoult's law and IBAc+BUP system exhibits no deviation from ideal behaviour. The activity coefficients of the solutions were correlated with its composition by

R. Muñoz; J. B. Montón; M. C. Burguet; J. de la Torre

2005-01-01

21

The Structure and Thermodynamics of Cellulose Acetates.  

NASA Astrophysics Data System (ADS)

Cellulose acetate (CA) polymers having different degrees of substitution (DS) vary widely in their properties, such as glass transition, miscibility, chemical resistance, and gas permeation. These variations hint at differences in their molecular structure. We have systematically studied the variation in the molecular structure of CA with DS, utilizing small angle neutron scattering (SANS). SANS measurements were carried out in 1% (w/v) solutions in dDMSO (which is sufficiently dilute to avoid intermolecular scattering). The polymer chains display rigidity along their main chain and have persistence lengths in the range of 12 to 14 nm. The effect of DS on the extent of miscibility is explained on the basis of available intra-molecular hydrogen bonding sites along the polymer chain. SANS measurements were also carried out on 50-50(w/w) miscible blends of two sets of CA, where the difference in the DS between the polymers varied from 0.05 to 0.25. Random phase approximation analysis provides an estimate of the Flory-Huggins interaction parameter between the two polymers in the blend. The influence of both the amount of substitution and hydrogen bonding on the polymer miscibility will be discussed.

Dadmun, Mark; Mehta, Rujul; Lynn, Gary

2008-03-01

22

Caloric Value of Acetate and Propionate for Lactating Dairy Cows[1] and [2  

Microsoft Academic Search

Two mature Holstein cows with rumen fistulas were fed hay, corn silage, and concentrate in a fixed ratio (air-dry basis) of 5:15:20 and in quantity intended to minimize tissue energy change. Acetate (A) or propionate (P) or an equicaloric mixture (M) of A and P, prepared by partially neutralizing (pH 4.4) respective acids with NaOH, was diluted, and in- fused

J. B. Holter; L. A. Jones; N. F. Colovos; W. E. Urban Jr.

1972-01-01

23

Isolation of cellulose from rice straw and its conversion into cellulose acetate catalyzed by phosphotungstic acid.  

PubMed

Cellulose was isolated from rice straw by pretreatment with dilute alkaline and acid solutions successively, and it was further transferred into cellulose acetate in the presence of acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The removal of hemicellulose and lignin was affected by the concentration of KOH and the immersion time in acetic acid solution, and 83wt.% content of cellulose in the treated rice straw was obtained after pretreatment with 4% KOH and immersion in acetic acid for 5h. Phosphotungstic acid was found to be an effective catalyst for the acetylation of the cellulose derived from rice straw. The degree of substitution (DS) values revealed a significant effect for the solubility of cellulose acetate, and the acetone-soluble cellulose acetate with DS values around 2.2 can be obtained by changing the amount of phosphotungstic acid and the time of acetylation. Both the structure of cellulose separated from rice straw and cellulose acetate were confirmed by FTIR and XRD. PMID:23544511

Fan, Guozhi; Wang, Min; Liao, Chongjing; Fang, Tao; Li, Jianfen; Zhou, Ronghui

2013-02-01

24

Aluminum phosphate dispersed on a cellulose acetate fiber surface  

Microsoft Academic Search

Cellulose acetate fibers with supported highly dispersed aluminum phosphate were prepared by reacting aluminum-containing cellulose acetate (Al2O3=3.5wt.%; 1.1mmolg?1 aluminum atom per gram of the material) with phosphoric acid. Solid-state NMR spectra (CPMAS 31P NMR) data indicated that HPO42? is the species present on the fiber surface. The specific concentration of acidic centers, determined by ammonia gas adsorption, is 0.50mmolg?1. The

Angelica M Lazarin; Claudemir A Borgo; Yoshitaka Gushikem; Yuriy V Kholin

2003-01-01

25

Degradation of Cellulose Acetate-Based Materials: A Review  

Microsoft Academic Search

Cellulose acetate polymer is used to make a variety of consumer products including textiles, plastic films, and cigarette\\u000a filters. A review of degradation mechanisms, and the possible approaches to diminish the environmental persistence of these\\u000a materials, will clarify the current and potential degradation rates of these products after disposal. Various studies have\\u000a been conducted on the biodegradability of cellulose acetate,

Juergen PulsSteven; Steven A. Wilson; Dirk Hölter

2011-01-01

26

New Analytical Method for Cellulose Acetate Electrophoresis Using Terahertz Imaging  

NASA Astrophysics Data System (ADS)

We propose a new method of analyzing the results of cellulose acetate electrophoresis by terahertz imaging. To verify accuracy of terahertz imaging of cellulose acetate electrophoresis, we compared the images obtained by terahertz imaging with those obtained by the one-side staining method. To obtain accurate information about the distribution of medical molecules in cellulose acetate by terahertz imaging, owing to the low concentration, a suitable imaging spatial resolution is required to estimate the distribution accurately in the cellulose acetate membrane. Here, we have improved the spatial resolution by reducing the absorption of the diffusion of the terahertz signal from the sample surface. Using the terahertz imaging system, we obtained terahertz images of the cellulose acetate with a glycine sensitivity of 3.71 ?g/mm2 and an l-methionine sensitivity of 6.22 ?g/mm2. Comparison of the terahertz and staining images showed that the new imaging method using the terahertz imaging system has a good possibility for cellulose acetate membrane electrophoresis analysis even for relatively low-concentration electrophoresis.

Zhang, Hong Bing; Mitobe, Kazutaka; Suzuki, Masafumi; Yoshimura, Noboru

2009-06-01

27

Response surface methodological approach for Rhizomucor miehei lipase-mediated esterification of ?-terpineol with propionic acid and acetic anhydride  

Microsoft Academic Search

Esterification of ?-terpineol with acetic anhydride or propionic acid mediated by Rhizomucor miehei lipase was subjected to a response surface study in order to optimize conditions for maximum esterification. The variables\\u000a were enzyme\\/substrate (acid) ratio, ?-terpineol concentration and incubation period using lipase from R. miehei. Between acetic anhydride and propionic acid, the former showed better yields at lower enzyme\\/substrate ratios

Pramila Rao; Soundar Divakar

2002-01-01

28

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

29

A quantitative method for blood lipoproteins using cellulose acetate electrophoresis  

PubMed Central

A rapid, inexpensive, and quantitative method is described for obtaining the levels of plasma very low, low, and high density lipoproteins using cellulose acetate electrophoresis and lipid assays without prior separation by ultracentrifuge or other techniques. It involves separation of the lipoproteins by cellulose acetate electrophoresis, followed by their identification with the ozone-Schiff reaction. The total lipoprotein concentration is estimated from the total plasma phospholipid, and the percentage of each component obtained by densitometric analysis of the stained electrophoretograms, using reflected light. For samples with a raised level of very low density lipoprotein, plasma triglyceride analysis is also required. The results obtained by the cellulose acetate electrophoresis method are in good agreement with those by the analytical ultracentrifuge and the preparative ultracentrifuge with refractometry. The theoretical assumptions on which the method is based have been shown to be valid. Images

Magnani, H. N.; Howard, A. N.

1971-01-01

30

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

31

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.

Gonzalez-Gil, Graciela; Holliger, Christof

2011-01-01

32

The Use of Polymeric Gels to Reduce Compaction in Cellulose Acetate Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

Polymeric gels were synthesized by crosslinking cellulose acetate in emulsion and solution reactions. These gels were used to replace a portion of the linear cellulose acetate in a standard Manjikian-type asymmetric membrane, with the aim of reducing long...

S. L. Rosen C. Irani L. Baayens

1972-01-01

33

The Effects of Porous and Solid Fillers on the Permeability of Cellulose Acetate Membranes.  

National Technical Information Service (NTIS)

Several types of filled cellulose acetate membranes were prepared to determine the effect of filler properties and polymer properties on permeability of the composite materials. Casting procedures were chosen to give a dense cellulose acetate phase and a ...

P. Harriott J. Wu F. Klunker

1973-01-01

34

PROCESS FOR OBTAINING CELLULOSE ACETATE FROM AGRICULTURAL BY-PRODUCTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A method of preparation of commercially useful product, cellulose acetate from discarded byproducts such as rice-straw, wheat hull and corn fiber will be discussed. This work will provide potential new markets and applications for low-value agricultural wastes and co-products. By converting the ce...

35

The thermal equation for ammonia sorption by cellulose acetate  

NASA Astrophysics Data System (ADS)

The thermal equation for ammonia sorption by cellulose acetate was obtained using the quasichemical model of the sorption of vapors by swelling polymeric sorbents suggested by Lindstrom and Laatikainen. The experimental data obtained by reversed gas chromatography and static methods are compared.

Vorotyntsev, I. V.; Gamayunova, T. V.

2009-05-01

36

Silver Nanoparticles in Cellulose Acetate Polymers: Rheological and Morphological Properties  

Microsoft Academic Search

Silver nitrate was incorporated in cellulose acetate with different substitution degrees as a dispersion medium. Silver-containing polymer solutions in 2-methoxyethanol were rheologically investigated, both before and after boiling, which permitted a better understanding of the morphological aspects of the corresponding cast films. The different distribution of the obtained silver nanoparticles in the polymer matrix, as well as the influence of

Adina Maria Necula; Iuliana Stoica; Niculae Olaru; Florica Doroftei; Silvia Ioan

2011-01-01

37

On the Structure of Cellulose Acetate Molecules in Acetone Solution  

Microsoft Academic Search

Data obtained from sedimentation velocity and viscosity measurements on a series of cellulose acetate fractions in acetone are interpreted in terms of two models, the impenetrable ellipsoid of rotation and the uniform density random coil. The lack of agreement using the former model is shown to be a real effect, rather than one determined by experimental inaccuracy. As other investigations

Seymour J. Singer; Herman Mark

1948-01-01

38

Conversion of cotton byproducts to mixed cellulose esters  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cotton byproducts, such as cotton burr and cottonseed hull, can be used as low-cost feedstock for the production of specialty chemicals. The conversion of these cellulosic byproducts into mixed cellulose esters, e.g., cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB), was stud...

39

Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites  

Microsoft Academic Search

Sisal nanowhiskers were used as novel reinforcement to obtain nanocomposites with polyvinyl acetate (PVAc) as matrix phase. They are seen as attractive materials due to the widespread availability and low cost of the sisal source material. Statistical analysis of the sisal whisker length and diameter resulted in average values of 250 nm and 4 nm, respectively, resulting in an average aspect ratio

Nancy Lis Garcia de Rodriguez; Wim Thielemans; Alain Dufresne

2006-01-01

40

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

Microsoft Academic Search

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

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

1985-01-01

41

Sorption of ammonia and nitrogen on cellulose acetate  

NASA Astrophysics Data System (ADS)

Adsorption isotherms of ammonia and nitrogen on cellulose acetate in the temperature range 303-333 K are measured by reversed-phase chromatography. It is established that ammonia specifically interacts with the polymer matrix of the sorbent. The experimental data are described in terms of the Laatikainen-Lindstrom quasi-chemical model of vapor sorption. The enthalpies of sorption are determined, and their dependences on the ammonia and nitrogen concentrations in the sorbent are established.

Vorotyntsev, I. V.; Drozdov, P. N.; Mochalov, G. M.; Smirnova, N. N.; Suvorov, S. S.

2006-12-01

42

Liquid crystalline solutions of cellulose acetate in phosphoric acid  

Microsoft Academic Search

The influence has been studied of both the acid strength of phosphoric acid and the degree of substitution of cellulose acetate on the formation of an anisotropic phase. The solvent composition is expressed as a P2O5 concentration. It was found that the clearing temperature increases strongly with decreasing amount of water in the solvent.The influence of the degree of substitution

H Boerstoel; H Maatman; S. J Picken; R Remmers; J. B Westerink

2001-01-01

43

Effects of electron beam irradiation of cellulose acetate cigarette filters  

NASA Astrophysics Data System (ADS)

A method to reduce the molecular weight of cellulose acetate used in cigarette filters by using electron beam irradiation is demonstrated. Radiation levels easily obtained with commercially available electron accelerators result in a decrease in average molecular weight of about six-times with no embrittlement, or significant change in the elastic behavior of the filter. Since a first step in the biodegradation of cigarette filters is reduction in the filter material's molecular weight this invention has the potential to allow the production of significantly faster degrading filters.

Czayka, M.; Fisch, M.

2012-07-01

44

Inability of Microorganisms To Degrade Cellulose Acetate Reverse-Osmosis Membranes †  

PubMed Central

Operational cellulose acetate reverse-osmosis membranes were examined for evidence of biological degradation. Numerous fungi and bacteria were isolated by direct and enrichment techniques. When tested, most of the fungi were active cellulose degraders, but none of the bacteria were. Neither fungi nor bacteria were able to degrade cellulose acetate membrane in vitro, although many fungi were able to degrade cellulose acetate membrane after it had been deacetylated. Organisms did not significantly degrade powdered cellulose acetate in pure or mixed cultures as measured by reduction in acetyl content or intrinsic viscosity or production of reducing sugars. Organisms did not affect the performance of cellulose triacetate fibers when incubated with them. The inability of the organisms to degrade cellulose acetate was attributed to the high degree of acetate substitution of the cellulose polymer. The rate of salt rejection decline was strongly correlated with chlorination of feed water and inversely with densities of microorganisms. These data suggest that microbial degradation of operational cellulose acetate reverse-osmosis membranes is unlikely.

Ho, Leighton C. W.; Martin, David D.; Lindemann, William C.

1983-01-01

45

Preparation of biomaterials on the basis of a water-soluble cellulose acetate  

NASA Astrophysics Data System (ADS)

Biomaterials were obtained on the basis of water-soluble cellulose acetate and diterpenoids group of plants Lagohulusa intoxicating having hemostatic properties. It is established that these biomaterials on the basis of water-soluble cellulose acetate and lagohilina (or lagohirzina) had increased hemostatic activity and reduce parenchymal hemorrhage 5-6 times compared to control.

Akmalova, G. Yu.; Gulyamova, N. S.; Zainutdinov, U. N.; Rakhmanberdiev, G. R.; Negmatova, K. S.; Negmatova, M. I.

2012-07-01

46

Sorption and longitudinal swelling kinetic behaviour in the system cellulose acetate-methanol  

Microsoft Academic Search

The kinetics of methanol vapour sorption and concurrent longitudinal swelling of cellulose acetate membranes has been studied and interpreted in terms of ‘viscous’ swelling and differential swelling stress effects, on the basis of previous modelling work. The close parallelism of the kinetic behaviour observed here and in a previous study of the cellulose acetate-acetone system, shows that both sorption and

M. Sanopoulou; J. H. Petropoulos

1997-01-01

47

Combination effect of pH and acetate on enzymatic cellulose hydrolysis.  

PubMed

The productivity and efficiency of cellulase are significant in cellulose hydrolysis. With the accumulation of volatile fatty acids (VFAs), the pH value in anaerobic digestion system is reduced. Therefore, this study will find out how the pH and the amount of acetate influence the enzymatic hydrolysis of cellulose. The effects of pH and acetate on cellulase produced from Bacillus coagulans were studied at various pH 5-8, and acetate concentrations (0-60 mmol/L). A batch kinetic model for enzymatic cellulose hydrolysis was constructed from experimental data and performed. The base hypothesis was as follows: the rates of enzymatic cellulose hydrolysis rely on pH and acetate concentration. The results showed that the suitable pH range for cellulase production and cellulose hydrolysis (represents efficiency of cellulase) was 2.6-7.5, and 5.3-8.3, respectively. Moreover, acetate in the culture medium had an effect on cellulase production (K(I) = 49.50 mmol/L, n = 1.7) less than cellulose hydrolysis (K(I) = 37.85 mmol/L, n = 2.0). The results indicated that both the pH of suspension and acidogenic products influence the enzymatic hydrolysis of cellulose in an anaerobic environment. To enhance the cellulose hydrolysis rate, the accumulated acetate concentration should be lower than 25 mmol/L, and pH should be maintained at 7. PMID:19862964

Romsaiyud, Angsana; Songkasiri, Warinthorn; Nopharatana, Annop; Chaiprasert, Pawinee

2009-01-01

48

Propionates and acetates of chiral secondary alcohols: novel sex pheromone components produced by a lichen moth Barsine expressa (Arctiidae: Lithosiinae).  

PubMed

Females of a lichen moth, Barsine expressa (Arctiidae, Lithosiinae), which inhabit Iriomote Island in Japan, were captured by a black-light trap, and the pheromone gland extract was analyzed by gas chromatography (GC) with an electroantennographic (EAG) detector, and by GC coupled with mass spectrometry. The females produced several EAG-active esters, and the mass spectrum of a major component indicated the mixture consists of propionates derived from C(17)-saturated secondary alcohols, which were inseparable on the capillary GC column. In addition to these main components, the pheromone glands included two acetate derivatives of C(17) alcohols, and other propionates of C(16) and C(15) alcohols. The crude extract was treated with K(2)CO(3), and a 1:1 mixture of C(17) alcohols with a C(6)- or C(7)-chain moiety was obtained. The two alcohols were uniformly converted into monodeuterated n-heptadecane by mesylation and succeeding LiAlD(4) reduction. This result revealed a straight-chain structure of the C(17) alcohols with the acyl groups located at the 7- or 8-position. Field tests on Iriomote Island showed that the synthetic esters were behaviorally active. A 1:1 mixture of racemic 7-propioxyheptadecane and 8-propioxyheptadecane, which were prepared from the secondary alcohols synthesized by a Grignard coupling reaction, attracted male moths. Furthermore, propionates of the alcohols synthesized enantioselectively by using a hydrolytic kinetic resolution with Jacobsen's catalyst were evaluated. Only the traps baited with a mixture of the two esters with the same S-configuration significantly attracted B. expressa males. In the Tokyo area, the propionate mixture attracted a closely related species, Barsine aberrans aberrans. PMID:23250706

Fujii, Toru; Yamakawa, Rei; Terashima, Yoshie; Imura, Shinya; Ishigaki, Keiichi; Kinjo, Masakatsu; Ando, Tetsu

2012-12-19

49

Development of nanofibrous cellulose acetate/gelatin skin substitutes for variety wound treatment applications.  

PubMed

The major component of fibrous extracellular matrix of dermis is composed of a complex combination of proteins and polysaccharides. Electrospun cellulose acetate/gelatin might be an effective simulator of the structure and composition of native skin and during this study, we electrospun cellulose acetate/gelatin membranes in various compositions and their performance as a scaffold for either skin tissue engineering or as a wound dressing was evaluated. Skin treatment products, whether tissue-engineered scaffolds or wound dressings, should be sufficiently hydrophilic to allow for gas and fluid exchange and absorb excess exudates while controlling the fluid loss. However, a wound dressing should be easily removable without causing tissue damage and a tissue-engineered scaffold should be able to adhere to the wound, and support cell proliferation during skin regeneration. We showed that these distinct adherency features are feasible just by changing the composition of cellulose acetate and gelatin in composite cellulose acetate/gelatin scaffolds. High proliferation of human dermal fibroblasts on electrospun cellulose acetate/gelatin 25:75 confirmed the capability of cellulose acetate/gelatin 25:75 nanofibers as a tissue-engineered scaffold, while the electrospun cellulose acetate/gelatin 75:25 can be a potential low-adherent wound dressing. PMID:23640859

Vatankhah, Elham; Prabhakaran, Molamma P; Jin, Guorui; Ghasemi Mobarakeh, Laleh; Ramakrishna, Seeram

2013-05-01

50

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

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

1985-01-01

51

Rheological and hydrodynamic properties of cellulose acetate/ionic liquid solutions.  

PubMed

Rheological properties of cellulose acetate/1-ethyl-3-methylimidazolium acetate (EMIMAc) solutions are studied using shear dynamic and steady state rheology in a large range of polymer concentrations (from 0.1 to 10 wt.%) and temperatures (from 0 °C to 80 °C). Master plots for storage and loss moduli and for dynamic viscosity were built and shift parameters determined. Cellulose acetate/EMIMAc behaves as a classical polymer solution and obeys Cox-Merz law. Cellulose acetate intrinsic viscosity [?] was determined as a function of temperature and compared with the literature data for cellulose acetates dissolved in other solvents and cellulose dissolved in EMIMAc. Cellulose acetate intrinsic viscosity turned out to be much less temperature sensitive than that of cellulose. Specific viscosity-C[?] master plot was built: the slopes in log-log scale are 1.2 and 3.1 in dilute and semi-dilute regions, respectively. The activation energy as a function of concentration follows a power-law dependence. PMID:23399245

Rudaz, Cyrielle; Budtova, Tatiana

2012-11-30

52

Acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in Arctic marine sediments, Svalbard.  

PubMed

The contribution of volatile fatty acids (VFA) as e(-)-donors for anaerobic terminal oxidation of organic carbon through iron and sulfate reduction was studied in Arctic fjord sediment. Dissolved inorganic carbon, Fe(2+), VFA concentrations, and sulfate reduction were monitored in slurries from the oxidized (0-2 cm) and the reduced (5-9 cm) zone. In the 0-2 cm layer, 2/3 of the mineralization could be attributed to sulfate reduction and 1/3 to iron reduction. In the 5-9 cm layer, sulfate reduction was the sole mineralization process. Acetate and lactate turnover rates were measured by radiotracer. Inhibition of sulfate reduction with selenate resulted in the accumulation of acetate, propionate, and isobutyrate. The acetate turnover rates determined by radiotracer and accumulation after inhibition were similar. VFA turnover accounted for 21% and 52% of the mineralization through sulfate reduction in the 0-2 and 5-9 cm layer, respectively. Acetate and lactate turnover in the inhibited 0-2 cm slurry was attributed to iron reduction and accounted for 10% and 2% of the iron reduction. Therefore, 88% and 79% of the iron and sulfate reduction in the 0-2 cm layer, respectively, must be fueled by alternative e(-)-donors. The accumulation of VFA in the selenate-inhibited 0-2 cm slurry did not enhance iron reduction, indicating that iron reducers were not limited by VFA availability. PMID:17069623

Finke, Niko; Vandieken, Verona; Jørgensen, Bo Barker

2006-10-27

53

Antimicrobial membrane cellulose acetate containing ionic liquid and metal nanoparticles.  

PubMed

Stable metallic Au(0), Ag(0) and Pt(0) nanoparticle-containing membrane films (20 microm thickness) were obtained by combining irregularly shaped nanoparticles of monomodal size distributions (11 +/- 1.5 nm Au(0), 8.9 +/- 2.1 nm Ag(0) and 2.8 +/- 0.4 nm Pt(0)) in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (BMI x (NTf)2) with a syrup of cellulose acetate (CA) in acetone. The presence of small and stable Au(0), Ag(0) or Pt(0) nanoparticles induced an augmentation in the CA/IL film surface areas. The addition of the IL to the membrane resulted in an increase of its elasticity and a decrease in its tenacity and toughness, whereas its stress at break was not influenced. High antimicrobial activity was observed in membranes containing Au(0), Ag(0) and Pt(0) metal concentrations as low as 1 mg of metal per 5 g of CA. The CA/IL/nanoparticle combination enhanced the activity and durability of the metal nanoparticles and provided greater antimicrobial activity against E. coli and S. aureus bacteria. PMID:21770152

Scheeren, Carla W; Hermes, Vanessa; Bianchi, Otávio; Hertz, Plinho F; Dias, Silvio L P; Dupont, Jairton

2011-06-01

54

Covalent biofunctionalization of cellulose acetate with thermostable chimeric avidin.  

PubMed

A stable, bioactive cellulose acetate (CA) surface was developed by functionalizing the surface with highly thermostable avidin form. The CA films were first functionalized with a mixture of 3-aminopropyltrimethoxysilane and tetraethoxysilane to introduce free amino groups onto the surface of CA films. Free amino groups were functionalized with glutaraldehyde to obtain an activated surface for covalent biomolecule immobilization. A genetically engineered, high-affinity biotin-binding protein chimeric avidin, ChiAVD(I117Y), was used for biofunctionalization of the surface. The chimeric avidin protein has an increased stability in chemically harsh conditions and at high temperature when compared to wt (strept)avidin. The biological activity, i.e., biotin-binding capacity, of the immobilized protein was probed by [(3)H]-biotin. The activity of the chimeric avidin on functionalized CA films was fully retained over the three months' study period. The biotin-binding capacity of the immobilized chimeric avidin was compared to that of immobilized streptavidin, chicken avidin, and rhizavidin and significant differences between proteins were detected. The developed material offers a valuable platform for the development of inexpensive in vitro diagnostics and also supports biosensing applications that are required to operate under demanding conditions. PMID:21612241

Heikkinen, Jarkko J; Riihimäki, Tiina A; Määttä, Juha A E; Suomela, Sini E; Kantomaa, Jukka; Kulomaa, Markku S; Hytönen, Vesa P; Hormi, Osmo E O

2011-06-16

55

Characteristics of Porous Cellulose Acetate Membranes for the Separation of Some Inorganic Salts in Aqueous Solution.  

National Technical Information Service (NTIS)

Experimental results are presented to illustrate the effect of operating variables on the separation and flow characteristics of porous cellulose acetate membranes. The results are discussed from the point of view of the preferential sorption and capillar...

S. Sourirajan

1964-01-01

56

Comments on the determination of isoenzyme polymorphism (ADA, AK, 6-PGD, PGM) by cellulose acetate electrophoresis  

Microsoft Academic Search

Summary The paper highlights certain peculiarities of isoenzyme polymorphism as determined by cellulose acetate electrophoresis, as compared to other supporting media at different pH levels and concentrations of the buffer.

H.-H. Sonneborn

1972-01-01

57

Specification, Selectivity, and Performance of Porous Cellulose Acetate Membranes in Reverse Osmosis.  

National Technical Information Service (NTIS)

The general specifications of the Loeb-Sourirajan type porous cellulose acetate membranes are given in terms of the pure water permeability constant, A, and the solute transport parameter for sodium chloride at different operating pressures. A scale of me...

J. P. Agrawal S. Sourirajan

1969-01-01

58

Cellulose Acetate Electrophoresis of Cerebrospinal Fluid Proteins with Normal Values of 135 Persons.  

National Technical Information Service (NTIS)

A study on cellulose acetate electrophoresis of cerebrospinal fluid (CSF) proteins is reported. Two methods are used for concentration, acetone precipitation and sephadex dialysis with slight modifications. They are both considered to be clinically valuab...

1980-01-01

59

Study of Methods to Retard Compaction of Cellulose Acetate Membranes in Reverse Osmosis Desalination.  

National Technical Information Service (NTIS)

Cellulose acetate can be effectively crosslinked with hexamethoxymethyl melamine, acetyl acetonate titanium chelate, sodium dichromate, or lead oxide to prevent desalination membrane compaction. Only pigment reinforcement was promising in preventing the c...

B. Baum S. A. Margosiak W. H. Holley

1969-01-01

60

Tsuji-Trost N-allylation with allylic acetates using cellulose-Pd catalyst  

EPA Science Inventory

Allylic amines are synthesized using heterogeneous cellulose-Pd catalyst via N-allylation of amines; aliphatic and benzyl amines undergo facile reaction with substituted and unsubstituted allyl acetates in high yields....

61

Effect of Sequential Mixing and Compounding Conditions on Cellulose Acetate\\/Layered Silicate Nanocomposites  

Microsoft Academic Search

Injection molded nanocomposites have been successfully fabricated from cellulose acetate (CA), eco-friendly triethyl citrate\\u000a (TEC) plasticizer, and organically modified clay with and without maleic anhydride grafted cellulose acetate butyrate (CAB-g-MA)\\u000a as a compatibilizer. The effects of processing conditions such as mixing methods, pre-plasticizing times, extruder retention\\u000a times (RT) and addition of compatibilizer on the performance of these nanocomposites have been

Hwan-Man Park; Amar K. Mohanty; Lawrence T. Drzal; Ellen Lee; Deborah F. Mielewski; Manjusri Misra

2006-01-01

62

[Kinetic model of enhanced biological phosphorus removal with mixed acetic and propionic acids as carbon sources. (II): Process simulation].  

PubMed

Two groups of sequencing batch reactors were used to study the metabolism substrate transformation of phosphorus-accumulating organisms (PAO) and glycogen-accumulating organisms (GAO) fed with mixed acetic and propionic acids. Seven stoichiometry parameters and 24 kinetic parameters were contained in the PAO and GAO kinetic model, and stoichiometry parameters were deduced from the stoichiometry models, while kinetic parameters were determined by experimental results. The kinetic model parameters of stoichiometry and kinetics were determined according the experiments and the literature. Subsequently, the substrate transformations of PAO and GAO were calculated by the Matlab software. The model curves matched the SBR experimental data well, indicating that the kinetic model based on SCFAs metabolism could be used to simulate PAO and GAO in anaerobic-aerobic conditions. PMID:23745407

Zhang, Chao; Chen, Yin-Guang

2013-03-01

63

Ultrafine cellulose fibers produced by Asaia bogorensis, an acetic acid bacterium.  

PubMed

The ability to synthesize cellulose by Asaia bogorensis, a member of the acetic acid bacteria, was studied in two substrains, AJ and JCM. Although both strains have identical 16S rDNA sequence, only the AJ strain formed a solid pellicle at the air-liquid interface in static culture medium, and we analyzed this pellicle using a variety of techniques. In the presence of cellulase, glucose and cellobiose were released from the pellicle suggesting that it is made of cellulose. Field emission electron microscopy allowed the visualization of a 3D knitted structure with ultrafine microfibrils (approximately 5-20 nm in width) in cellulose from A. bogorensis compared with the 40-100 nm wide microfibrils observed in cellulose isolated from Gluconacetobacter xylinus, suggesting differences in the mechanism of cellulose biosynthesis or organization of cellulose synthesizing sites in these two related bacterial species. Identifying these differences will lead to a better understanding of cellulose biosynthesis in bacteria. PMID:21650167

Kumagai, Akio; Mizuno, Masahiro; Kato, Naoto; Nozaki, Kouichi; Togawa, Eiji; Yamanaka, Shigeru; Okuda, Kazuo; Saxena, Inder M; Amano, Yoshihiko

2011-06-17

64

Enzymatic production of ethanol from cellulose using soluble cellulose acetate as an intermediate  

Microsoft Academic Search

A two-stage process for the enzymatic conversion of cellulose to ethanol is proposed as an alternative to currently incomplete and relatively slow enzymatic conversion processes employing natural insoluble cellulose. This alternative approach is designed to promote faster and more complete conversion of cellulose to fermentable sugars through the use of a homogeneous enzymatic hydrolysis reaction. Cellulose is chemically dissolved in

Kim M. Downing; Chester S. Ho; D. W. Zabriskie

1987-01-01

65

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.

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

66

Investigation of Intermolecular Association in Concentrated Solutions of Cellulose Acetate.  

National Technical Information Service (NTIS)

The role of intermolecular association in concentrated solutions of cellulose triacetate (CTA) is investigated with respect to its importance in controlling the properties of CTA films formed from concentrated solutions for use, for example, as membranes ...

G. C. Berry T. S. Sham M. A. Leech

1979-01-01

67

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

68

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

69

Synthesis, antiviral and contraceptive activities of nucleoside–sodium cellulose sulfate acetate and succinate conjugates  

Microsoft Academic Search

Chemical conjugates between sodium cellulose sulfate (CS), displaying contraceptive and HIV-entry inhibiting properties, and nucleoside reverse transcriptase inhibitors (NRTIs) (3?-azido-2?,3?-dideoxythymidine (AZT), 3?-fluoro-2?,3?-dideoxythymidine (FLT), or 2?,3?-dideoxy-3?-thiacytidine (3TC)) were designed to simultaneously provide contraceptive and anti-HIV activity. Two linkers, acetate and succinate, were used to conjugate the nucleoside analogs with CS. The conjugates containing cellulose sulfate-acetate (CSA) (e.g., AZT–CSA and FLT–CSA) were

Hitesh K. Agarwal; Anil Kumar; Gustavo F. Doncel; Keykavous Parang

2010-01-01

70

Evaluation of Cellulose Acetate and Chitosan Used for the Treatment of Historical Papers.  

NASA Astrophysics Data System (ADS)

A lot of papers in museums and libraries suffer from unsuitable environmental conditions that can lead to brittleness and fragility. This study aims to evaluate the efficiency of cellulose acetate and chitosan at different concentrations for the preservation of historical papers. The untreated and treated samples were submitted to different accelerated ageing cycles. Analytical techniques used for the evaluation process were tensile strength and elongation measurement, UV-spectrophotometer, XRD, and SEM. The results revealed that heat-moist-light ageing cycle affected the properties studies more than other ageing cycles. The lower concentrations gave an improvement better than the higher concentrations of cellulose acetate and chitosan.

Abdel-Maksoud, Gomaa; al-Saad, Ziad

71

Cellulose esterification with fatty acids and acetic anhydride in lithium chloride\\/ N,N -dimethylacetamide medium  

Microsoft Academic Search

Homogeneous esterification of cellulose with saturated fatty acids (n-octanoic to n-octadecanoic) was accomplished with acetic anhydride co-reactant in lithium chloride\\/N,N-dimethylacetamide (LiCl\\/DMAc) medium. Cellulose mixed triesters (CMT) were obtained after 5 h at 130°C with an average of\\u000a 2.2 acetyl groups and 0.8 fatty substituents per anhydroglucose unit. A mixed acetic-fatty anhydride, formed in situ, accounts for the grafting of the

C. Vaca-Garcia; S. Thiebaud; M. E. Borredon; G. Gozzelino

1998-01-01

72

Temperature dependence of the dielectric permittivity of acetic acid, propionic acid and their methyl esters: a molecular dynamics simulation study.  

PubMed

For most liquids, the static relative dielectric permittivity is a decreasing function of temperature, because enhanced thermal motion reduces the ability of the molecular dipoles to orient under the effect of an external electric field. Monocarboxylic fatty acids ranging from acetic to octanoic acid represent an exception to this general rule. Close to room temperature, their dielectric permittivity increases slightly with increasing temperature. Herein, the causes for this anomaly are investigated based on molecular dynamics simulations of acetic and propionic acids at different temperatures in the interval 283-363 K, using the GROMOS 53A6(OXY) force field. The corresponding methyl esters are also considered for comparison. The dielectric permittivity is calculated using either the box-dipole fluctuation (BDF) or the external electric field (EEF) methods. The normal and anomalous temperature dependences of the permittivity for the esters and acids, respectively, are reproduced. Furthermore, in the EEF approach, the response of the acids to an applied field of increasing strength is found to present two successive linear regimes before reaching saturation. The low-field permittivity ?, comparable to that obtained using the BDF approach, increases with increasing temperature. The higher-field permittivity ?' is slightly larger, and decreases with increasing temperature. Further analyses of the simulations in terms of radial distribution functions, hydrogen-bonded structures, and diffusion properties suggest that increasing the temperature or the applied field strength both promote a relative population shift from cyclic (mainly dimeric) to extended (chain-like) hydrogen-bonded structures. The lower effective dipole moment associated with the former structures compared to the latter ones provides an explanation for the peculiar dielectric properties of the two acids compared to their methyl esters. PMID:22383366

Riniker, Sereina; Horta, Bruno A C; Thijssen, Bram; Gupta, Saumya; van Gunsteren, Wilfred F; Hünenberger, Philippe H

2012-03-01

73

PROCESS FOR OBTAINING CELLULOSE ACETATE FROM AGRICULTURAL BY-PRODUCTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Agricultural residues such as corn fiber, rice hulls and wheat straw can be used as an abundant low-cost feedstock for the production of fuel ethanol. However, the cost of cellulase enzymes to saccharify cellulose to glucose is a major hindrance. As an alternative, a novel process method was devel...

74

Diffusion of Sodium Chloride in Cellulose and Amylose Acetates.  

National Technical Information Service (NTIS)

A method for measuring the resistance change of a film with time was used to determine the diffusion and apparent permeability coefficients of sodium chloride in the two polymeric films. The results with cellulose diacetate (CDA, 39.8% acetyl) were compar...

M. Barnes C. Skaar P. Luner

1972-01-01

75

Dependence of the mobility of molecular probes in cellulose acetate solutions on complexation and the solution structure  

Microsoft Academic Search

The spin echo technique with a magnetic field pulse gradient was used to measure the translational diffusion coefficients D of molecular probes in solutions of cellulose acetates in dimethyl sulfoxide. A linear dependence of coefficient D on the extent of substitution of the cellulose acetate was established and the sensitivity of D to the supermolecular structure of the polymer solution

O. D. Vetrov; A. M. Gladkii; V. A. Daragan; E. É. Il'ina; D. A. Moskalev; V. V. Myasoedova; A. É. Prizment

1990-01-01

76

Densities and excess molar volumes of formic acid, acetic acid and propionic acid in pure water and in water?+?Surf Excel solutions at different temperatures  

Microsoft Academic Search

Densities, ? of the systems formic acid, acetic acid and propionic acid in water and in 0.05% and 0.1% Surf Excel (SE) solutions in water were measured at temperatures 303.15, 308.15, 313.15, 318.15 and 323.15?K respectively covering the whole composition range. Excess molar volumes, for the systems were found to be negative and their values were found to increase with

M. A. Motin; M. H. Kabir; E. M. Huque

2005-01-01

77

Synthesis of polyhydroxyalkanoate (PHA) from excess activated sludge under various oxidation-reduction potentials (ORP) by using acetate and propionate as carbon sources  

Microsoft Academic Search

Accumulation of poly hydroxyalkanoate (PHA) from excess activated sludge (EAS) was monitored and controlled via the oxidation-reduction\\u000a potential (ORP) adjusting process. The ORP was adjusted and controlled by only regulating the gas-flow rate pumped into the\\u000a cultural broth in which sodium acetate (C2) and propionate (C3) were used as carbon sources. Productivity of PHA and the PHA\\u000a compositions at various

W. F. Hu; S. N. Sin; H. Chua; P. H. F. Yu

2005-01-01

78

Synthesis of Polyhydroxyalkanoate (PHA) from Excess Activated Sludge Under Various Oxidation-Reduction Potentials (ORP) by Using Acetate and Propionate as Carbon Sources  

Microsoft Academic Search

Accumulation of poly hydroxyalkanoate (PHA) from excess activated sludge (EAS) was monitored and controlled via the oxidation-reduction\\u000a potential (ORP) adjusting process. The ORP was adjusted and controlled by only regulating the gas-flow rate pumped into the\\u000a cultural broth in which sodium acetate (C2) and propionate (C3) were used as carbon sources. Productivity of PHA and the PHA\\u000a compositions at various

W. F. Hu; S. N. Sin; H. Chua; P. H. F. Yu

79

Wrinkle Resistant Fabric Produced by Crosslinking Cellulosic Materials with Acetals of Glyceraldehyde.  

National Technical Information Service (NTIS)

Acetals of glyceraldlehyde, when applied to cotton fabric by conventional pad-dry-cure procedures using special combined acid catalysts, were found to crosslink the cellulose hydroxyl groups at a very rapid rate (e.g., 10 seconds at 170 C), thereby impart...

L. H. Chance G. F. Danna

1987-01-01

80

Effects of Moisture and High Electric Fields on Conductivity in Alkali-Halide-Doped Cellulose Acetate  

Microsoft Academic Search

Several problems associated with ionic conduction in amorphous hydrophilic polymers have been investigated from a theoretical point of view and then discussed in the light of experiments with alkali-halide-doped cellulose 2.5 acetate. The main ideas emphasized are: (1) The major effects of moisture on conductivity ? in this class of polymers are to increase the dielectric constant &egr;? and therefore

R. E. Barker; Charles R. Thomas

1964-01-01

81

Effect of conjugated linoleic acid immobilization on the hemocompatibility of cellulose acetate membrane  

Microsoft Academic Search

Conjugated linoleic acid (CLA) was covalently immobilized onto cellulose acetate (CA) membranes. The effects of CLA immobilization on the blood coagulation, platelet aggregation, and oxidative stress were evaluated using human blood. The resulting CLA grafting CA membranes were characterized with X-ray photoelectronic spectroscopy (XPS). The complete blood count (CBC) and coagulation time (CT) was evaluated in vitro for the hemocompatibility.

F.-C. Kung; M.-C. Yang

2006-01-01

82

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

83

Morphological development of polypropylene in immiscible blends with cellulose acetate butyrate  

Technology Transfer Automated Retrieval System (TEKTRAN)

Isotactic polypropylenes (iPP) with different melt flow indexes were melt blended with cellulose acetate butyrate (CAB) and then prepared into microspheres or nanofibers following a novel process of producing well dispersed CAB/iPP immiscible blends and subsequent removal of the CAB matrix. The morp...

84

Utilization of Vinegar for Isolation of Cellulose Producing Acetic Acid Bacteria  

SciTech Connect

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{sup -1} for the strain AS14 which resembled Gluconacetobacter hansenii in terms of biochemical tests.

Aydin, Y. Andelib; Aksoy, Nuran Deveci [Chemical Engineering Department of Istanbul Technical University, Ayazaga, Maslak, Istanbul, 34469 (Turkey)

2010-06-17

85

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

86

Studies on the synthesis of acrylamidomethyl cellulose ester and its application in UV curable surface coatings induced by free radical photoinitiator. Part 1: Acrylamidomethyl cellulose acetate  

Microsoft Academic Search

This paper reports on the development of cellulose derivatives, which can undergo cross linking on exposure to UV radiation. To achieve this, cellulose acetate was reacted with N-methylol-acrylamide (NMA) in homogeneous phase catalyzed by acids. Analysis of computer aided statistically designed experiments showed that the NMA concentration and reaction temperature played a predominant role in the acrylamidomethylation process. FTIR spectroscopy

R. N. Kumar; Pieng Lay Po; H. D. Rozman

2006-01-01

87

Purification and characterization of an esterase involved in cellulose acetate degradation by Neisseria sicca SB.  

PubMed

An esterase catalyzing the hydrolysis of acetyl ester moieties in cellulose acetate was purified 1,110-fold to electrophoretic homogeneity from the culture supernatant of Neisseria sicca SB, which can assimilate cellulose acetate as the sole carbon and energy source. The purified enzyme was a monomeric protein with a molecular mass of 40 kDa and the isoelectric point was 5.3. The pH and temperature optima of the enzyme were 8.0-8.5 and 45 degrees C. The enzyme catalyzed the hydrolysis of acetyl saccharides, p-nitrophenyl esters of short-chain fatty acids, and was slightly active toward aliphatic and aromatic esters. The K(m) and Vmax for cellulose acetate (degree of substitution, 0.88) and p-nitrophenyl acetate were 0.0162% (716 microM as acetyl content in the polymer) and 36.0 microM, and 66.8 and 39.1 mumol/min/mg, respectively. The enzyme was strongly inhibited by phenylmethylsulfonyl fluoride and diisopropyl fluorophosphate, which indicated that the enzyme was a serine esterase. PMID:10586499

Moriyoshi, K; Ohmoto, T; Ohe, T; Sakai, K

1999-10-01

88

The formation of propionate and acetate as terminal processes in the energy metabolism of the adult liver fluke Fasciola hepatica  

Microsoft Academic Search

1. 1. The formation of propionate from succinate occurs in the mitochondria of the adult common liver fluke essentially by a reversal of the pathway operating in mammalian mitochondria in the conversion of propionate into succinate.\\u000a\\u000a2. 2. The conversion of succinate into its CoA ester is linked by a CoA transferase to the splitting of propionyl-CoA.\\u000a\\u000a3. 3. The

F. van Vugt; P. van der Meer; S. G. van den Bergh

1979-01-01

89

Osmotic water transport through cellulose acetate membranes produced from a latex system.  

PubMed

The advisability of a progressive curtailment of organic solvent film coating offers an incentive to develop latex systems. Here, the use of aqueous colloidal dispersions of cellulose acetate, plasticized with water-soluble additives, is proposed as an alternative way to obtain cellulose acetate membranes either by casting or spraying. The osmotic water permeability of both kinds of films was measured, as well as their loss of leachable materials and degree of swelling in a saturated solution of potassium chloride. The permeabilities varied over a wide range depending on the physicochemical properties of the plasticizer and its initial concentration in the latex, and on the conditions for coating (temperature, rate of spraying, and drying duration). High boiling point plasticizers gave more permeable films. Films prepared by casting were found to be sensitive to their sodium dodecyl sulfate content. PMID:3625490

Bindschaedler, C; Gurny, R; Doelker, E

1987-06-01

90

Storage of Cellulose Acetate Collections: A Preliminary Survey of Issues and Options  

NSDL National Science Digital Library

Photographic negatives, motion picture film, microfilm, and sound recordings produced from the 1930s into the 1950s often used cellulose acetate as the transparent plastic carrier. As anyone who has ever come in contact with it well knows, its strong vinegar-like scent is hard to miss. Unfortunately, over time, the material is prone to deterioration, which eventually renders it unusable. In an effort to help guide libraries in Australia with this problem, the National Library of Australia has created two documents. This resource draws upon recent "literature discussing preservation and storage of cellulose acetate based film" to guide librarians and collection managers in choosing storage options (lower temperatures and humidity slow the deterioration process). The report discusses the options and provides guidance for planning and evaluation of each, and an appendix directs one to specific Australian storage facilities. Together, both reports serve as a brief, easily readable introduction to this challenging preservation issue.

2002-01-01

91

Investigation of griseofulvin and hydroxypropylmethyl cellulose acetate succinate miscibility in ball milled solid dispersions.  

PubMed

Solid dispersions of varying weight ratios compositions of the nonionic drug, griseofulvin and the hydrophilic, anionic polymer, hydroxylpropylmethyl cellulose acetate succinate, have been prepared by ball milling and the resulting samples characterized using a combination of Fourier transform infra-red spectroscopy, X-ray powder diffraction and differential scanning calorimetry. The results suggest that griseofulvin forms hydrogen bonds with the hydroxylpropylmethyl cellulose acetate succinate polymer when prepared in the form of a solid dispersion but not when prepared in a physical mixture of the same composition. As anticipated, the actual measured glass transition temperature of the solid dispersions displayed a linear relationship between that predicted using the Gordon-Taylor and Fox equations assuming ideal mixing, but interestingly only at griseofulvin contents less than 50 wt%. At griseofulvin concentrations greater than this, the measured glass transition temperature of the solid dispersions was almost constant. Furthermore, the crystalline content of the solid dispersions, as determined by differential scanning calorimetry and X-ray powder diffraction followed a similar trend in that the crystalline content significantly decreased at ratios less than 50 wt% of griseofulvin. When the physical mixtures of griseofulvin and the hydroxylpropylmethyl cellulose acetate succinate polymer were analyzed using the Flory-Huggins model, a negative free energy of mixing with an interaction parameter of -0.23 were obtained. Taken together these results suggest that anionic hydrophilic hydroxylpropylmethyl cellulose acetate succinate polymer is a good solvent for crystalline nonionic griseofulvin with the solubility of griseofulvin in the solid dispersion being was estimated to be within the range 40-50 wt%. Below this solubility limit, the amorphous drug exists as amorphous glassy solution while above these values the system is supersaturated and glassy suspension and solution may coexist. PMID:23299082

Al-Obaidi, Hisham; Lawrence, M Jayne; Al-Saden, Noor; Ke, Peng

2013-01-06

92

Ester prodrug-loaded electrospun cellulose acetate fiber mats as transdermal drug delivery systems  

Microsoft Academic Search

Cellulose acetate (CA) fibers loaded with the ester prodrugs of naproxen, including methyl ester, ethyl ester and isopropyl\\u000a ester, were prepared through electrospinning using acetone\\/N,N-dimethylacetamide(DMAc)\\/ethanol (4:1:1, v\\/v\\/v) as solvent. The chemical and morphological characterizations of the medicated\\u000a fibers were investigated by means of SEM, DSC, XRD and FTIR, as well as the studies of the drug release properties. The results

Xiao-mei Wu; Christopher J. Branford-White; Li-min Zhu; Nichoals P. Chatterton; Deng-guang Yu

2010-01-01

93

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

94

Novel cellulose acetate membrane blended with phospholipid polymer for hemocompatible filtration system  

Microsoft Academic Search

To improve the blood compatibility of cellulose acetate (CA) membranes for hemofiltration, a novel CA membrane blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer was designed for a hemocompatible filtration system. The MPC copolymer (PMB30) was synthesized from MPC and n-butyl methacrylate. The polymer solution for making the membrane was prepared from a solvent mixture composed of N,N-dimethylformamide, acetone, and 2-propanol. The

Sang Ho Ye; Junji Watanabe; Yasuhiko Iwasaki; Kazuhiko Ishihara

2002-01-01

95

Effect of grafting cellulose acetate and methylmethacrylate as compatibilizer onto NBR\\/SBR blends  

Microsoft Academic Search

Compatibilizer is used for improving of processability, interfacial interaction and mechanical properties of polymer blends. In this study acrylonitrile butadiene rubber (NBR) and styrene-butadiene rubber (SBR) blends were compatibilized by a graft copolymer of acrylonitrile butadiene rubber (NBR) grafted with cellulose acetate (CA) i.e. (NBR-g-CA) and acrylonitrile butadiene rubber (NBR) grafted with methylmethacrylate i.e. (NBR-g-MMA). Compatibilizers were prepared by gamma

A. I. Khalf; D. E. El. Nashar; N. A. Maziad

2010-01-01

96

36 CFR 1237.30 - How do agencies manage records on nitrocellulose-base and cellulose-acetate base film?  

Code of Federal Regulations, 2011 CFR

...records on nitrocellulose-base and cellulose-acetate base film? (a) The nitrocellulose base, a substance akin to gun cotton, is chemically unstable and highly flammable. Agencies must handle nitrocellulose-base film (used in the...

2011-07-01

97

Synthesis, antiviral and contraceptive activities of nucleoside-sodium cellulose sulfate acetate and succinate conjugates.  

PubMed

Chemical conjugates between sodium cellulose sulfate (CS), displaying contraceptive and HIV-entry inhibiting properties, and nucleoside reverse transcriptase inhibitors (NRTIs) (3'-azido-2',3'-dideoxythymidine (AZT), 3'-fluoro-2',3'-dideoxythymidine (FLT), or 2',3'-dideoxy-3'-thiacytidine (3TC)) were designed to simultaneously provide contraceptive and anti-HIV activity. Two linkers, acetate and succinate, were used to conjugate the nucleoside analogs with CS. The conjugates containing cellulose sulfate-acetate (CSA) (e.g., AZT-CSA and FLT-CSA) were found to be more potent than CS and other conjugates (e.g., AZT-succinate-CS, and FLT-succinate-CS). The presence of both sulfate and the acetate groups on cellulose were critical for generating maximum anti-HIV activity. In addition to showing equal potency against wild-type and multidrug resistant HIV-1, the AZT-CSA conjugate displayed significant contraceptive activity in an animal model, providing the initial proof-of-concept for the design and synthesis of dual-activity compounds based on these combinations. PMID:20965725

Agarwal, Hitesh K; Kumar, Anil; Doncel, Gustavo F; Parang, Keykavous

2010-10-19

98

ac and dc percolative conductivity of magnetite-cellulose acetate composites  

NASA Astrophysics Data System (ADS)

ac and dc conductivity results for a percolating system, which consists of a conducting powder (magnetite) combined with an “insulating” powder (cellulose acetate), are presented. Impedance and modulus spectra are obtained in a percolation system. The temperature dependence of the resistivity of the cellulose acetate is such that at 170°C , it is essentially a conductor at frequencies below 0.059±0.002Hz , and a dielectric above. The percolation parameters, from the dc conductivity measured at 25 and 170°C , are determined and discussed in relation to the ac results. The experimental results scale as a function of composition, temperature, and frequency. An interesting result is the correlation observed between the scaling parameter (fce) , obtained from a scaling of the ac measurements, and the peak frequency (fcp) of the arcs, obtained from impedance spectra, above the critical volume fraction. Scaling at 170°C is not as good as at 25°C , probably indicating a breakdown in scaling at the higher temperature. The modulus plots show the presence of two materials: a conducting phase dominated by the cellulose acetate and the isolated conducting clusters below the critical volume fraction ?c , as well as the interconnected conducting clusters above ?c . These results are confirmed by computer simulations using the two exponent phenomenological percolation equation. These results emphasize the need to analyze ac conductivity results in terms of both impedance and modulus spectra in order to get more insight into the behavior of composite materials.

Chiteme, C.; McLachlan, D. S.; Sauti, G.

2007-03-01

99

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

100

Experience with cellulose acetate-coated activated charcoal haemoperfusion in the treatment of severe hypnotic drug intoxication.  

PubMed Central

A haemoperfusion column containing activated charcoal coated with cellulose acetate was used to treat 7 patients with barbiturate or ethchlorvynol poisoning. Six of the patients showed marked lightening of coma and all showed a significant fall in plasma drug concentration. Plasma drug clearance and platelet loss were similar to those reported for other coated charcoal columns. Cellulose acetate-coated charcoal haemoperfusion may reduce the period of coma in severe poisoning with barbiturates and other hypnotic drugs and thus the morbidity and mortality.

Crome, P.; Hampel, G.; Widdop, B.; Goulding, R.

1980-01-01

101

Effect of electro-chemical properties of chloride salts on their diffusional parameters in symmetrical cellulose acetate membranes  

Microsoft Academic Search

A relation was obtained between electro-chemical properties of alkali, alkali earth and aluminium chlorides (LiCl, NaCl, KCl, RbCl, CsCl, MgCl2, CaCl2, AlCl3) and the distribution coefficient K and the overall diffusion coefficients D in symmetrical cellulose acetate membranes. Symmetrical cellulose acetate membranes were cast to have a wider range of water content, 15–30%. K and D were measured by the

Haruhiko Ohya; Svetlana I Semenova; Toshinori Fujimoto; Jun Ogihara; Shinichi Fukaya; Kousuke Mori; Masahiko Aihara; Youichi Negishi

2001-01-01

102

Conversion of an electrospun nanofibrous cellulose acetate mat from a super-hydrophilic to super-hydrophobic surface  

NASA Astrophysics Data System (ADS)

We report a new approach to convert an electrospun nanofibrous cellulose acetate mat surface from super-hydrophilic to super-hydrophobic. Super-hydrophilic cellulose acetate nanofibrous mats can be obtained by electrospinning hydrophilic cellulose acetate. The surface properties of the fibrous mats were modified from super-hydrophilic to super-hydrophobic with a simple sol-gel coating of decyltrimethoxysilane (DTMS) and tetraethyl orthosilicate (TEOS). The resultant samples were characterized by field emission scanning electron microscopy (FE-SEM), x-ray photoelectron spectroscopy (XPS), water contact angle, Brunauer-Emmett-Teller (BET) surface area, atomic force microscopy (AFM), and UV-visible measurements. The results of FE-SEM and XPS showed that the sol-gel (I) films were formed on the rough fibrous mats only after immersion in sol-gel. After the sol-gel (I) coating, the cellulose acetate fibrous mats formed in both 8 and 10 wt% cellulose acetate solutions showed the super-hydrophobic surface property. Additionally, the average sol-gel film thickness coated on 10 wt% cellulose acetate fibrous mats was calculated to be 80 nm. The super-hydrophobicity of fibrous mats was attributed to the combined effects of the high surface roughness of the electrospun nanofibrous mats and the hydrophobic DTMS sol-gel coating. Additionally, hydrophobic sol-gel nanofilms were found to be transparent according to UV-visible measurements.

Ding, Bin; Li, Chunrong; Hotta, Yoshio; Kim, Jinho; Kuwaki, Oriha; Shiratori, Seimei

2006-09-01

103

Acetone-soluble cellulose acetate extracted from waste blended fabrics via ionic liquid catalyzed acetylation.  

PubMed

Isolation of cellulose from waste polyester/cotton blended fabrics (WBFs) is a bottleneck for recycling and exploiting waste textiles. The objective of this study was to provide a new environmental-friendly and efficient approach for extracting cellulose derivatives and polyester from WBFs. A Bronsted acidic ionic liquid (IL) N-methyl-imidazolium bisulfate, [Hmim]HSO4, was used as a novel catalyst for acetylation of cellulose rather than a solvent with the aim to overcome low isolation efficiency associated with the very high viscosity and relatively high costs of ILs. The extraction yield of acetone-soluble cellulose acetate (CA) was 49.3%, which corresponded to a conversion of 84.5% of the cellulose in the original WBFs; meanwhile, 96.2% of the original poly(ethylene terephthalate) (PET) was recovered. The extracted CA was characterized by (1)H NMR, FTIR, XRD and TGA analysis, and the results indicated that high purity acetone-soluble CA and carbohydrate-free PET could be isolated in this manner from WBFs. PMID:23987361

Sun, Xunwen; Lu, Canhui; Zhang, Wei; Tian, Dong; Zhang, Xinxing

2013-06-18

104

Metabolic Activity of Fatty Acid-Oxidizing Bacteria and the Contribution of Acetate, Propionate, Butyrate, and CO2 to Methanogenesis in Cattle Waste at 40 and 60?C  

PubMed Central

The quantitative contribution of fatty acids and CO2 to methanogenesis was studied by using stirred, 3-liter bench-top digestors fed on a semicontinuous basis with cattle waste. The fermentations were carried out at 40 and 60°C under identical loading conditions (6 g of volatile solids per liter of reactor volume per day, 10-day retention time). In the thermophilic digestor, acetate turnover increased from a prefeeding level of 16 ?M/min to a peak (49 ?M/min) 1 h after feeding and then gradually decreased. Acetate turnover in the mesophilic digestor increased from 15 to 40 ?M/min. Propionate turnover ranged from 2 to 5.2 and 1.5 to 4.5 ?M/min in the thermophilic and mesophilic digestors, respectively. Butyrate turnover (0.7 to 1.2 ?M/min) was similar in both digestors. The proportion of CH4 produced via the methyl group of acetate varied with time after feeding and ranged from 72 to 75% in the mesophilic digestor and 75 to 86% in the thermophilic digestor. The contribution from CO2 reduction was 24 to 29% and 19 to 27%, respectively. Propionate and butyrate turnover accounted for 20% of the total CH4 produced. Acetate synthesis from CO2 was greatest shortly after feeding and was higher in the thermophilic digestor (0.5 to 2.4 ?M/min) than the mesophilic digestor (0.3 to 0.5 ?M/min). Counts of fatty acid-degrading bacteria were related to their turnover activity.

Mackie, Roderick I.; Bryant, Marvin P.

1981-01-01

105

Role of endo-1,4-beta-glucanases from neisseria sicca SB in synergistic degradation of cellulose acetate.  

PubMed

An enzyme hydrolyzing beta-1,4 bonds in cellulose acetate was purified 10.5-fold to electrophoretic homogeneity from a culture supernatant of Neisseria sicca SB, which assimilate cellulose acetate as the sole carbon and energy source. The enzyme was an endo-1,4-beta-glucanase, to judge from the substrate specificity and hydrolysis products of cellooligosaccharides, we named it endo-1,4-beta-glucanase I (EG I). Its molecular mass was 50 kDa, 9 kDa larger than EG II from this strain, and its isoelectric point was 5.0. Results of N-terminal and inner-peptide sequences of both enzymes, and a similarity search, suggested that EG I contained a carbohydrate-binding module at the N-terminus and that EG II lacked this module. The pH and temperature optima of EG I were 5.0-6.0 and 45 degrees C. It hydrolyzed water-soluble cellulose acetate (degree of substitution, 0.88) and carboxymethyl cellulose. The Km and Vmax for these compounds were 0.296% and 1.29 micromol min(-1) mg(-1), and 0.448% and 13.6 micromol min(-1) mg(-1), respectively. Both glucanases and cellulose acetate esterase from this strain degraded water-insoluble cellulose acetate synergistically. PMID:12728982

Moriyoshi, Kunihiko; Ohmoto, Takashi; Ohe, Tatsuhiko; Sakai, Kiyofumi

2003-02-01

106

Chemical shift assignment of the complicated monomers comprising cellulose acetate by two-dimensional NMR spectroscopy.  

PubMed

(1)H and (13)C chemical shift assignment of the anhydroglucose units (AGUs) that comprise cellulose acetate with the total degree of substitution of 2.33 was performed by a combination of two-dimensional NMR spectra obtained from COSY, TOCSY, HSQC-TOCSY, and HSQC experiments. In the TOCSY spectra, there are 13 kinds of correlation networks for the H1 to H6' atoms of AGU; each (1)H resonance of the 13 AGUs was assigned from the changes in the intensities of the (1)H resonances with TOCSY spin-lock time during the TOCSY experiments. The ring (13)C resonances were assigned via analysis of HSQC spectra. Comparison of the shift data enabled the assignment of the 13 AGUs as three types of 2,3,6-tri-acetylated, one type of 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, and 3,6-di-acetylated AGU, and unsubstituted AGU, and three types of AGUs located in end units. These shift data will be useful for characterizing the molecular structures of cellulose derivatives as well as cellulose acetate (CA). PMID:23707362

Kono, Hiroyuki

2013-04-23

107

Cellulose Derivatives Membranes as Supports for Immobilisation of Enzymes  

Microsoft Academic Search

Cellulosic derivatives (cellulose acetate, cellulose propionate and cellulose acetate-butyrate) as membranes, were prepared in different ways. These were then characterised by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contact angle evaluation. Subsequently, catalase (H2O2:H2O2 oxireductase; EC 1.11.1.6), alcohol oxidase (Alcohol:oxygen oxireductase; EC 1.1.3.13) and glucose oxidase (ß-D- Glucose:oxygen 1-oxireductase; EC 1.1.3.4) were covalently linked to these membranes. The

D. Murtinho; A. R. Lagoa; F. A. P. Garcia; M. H. Gil

1998-01-01

108

Release kinetic studies of aspirin microcapsules from ethyl cellulose, cellulose acetate phthalate and their mixtures by emulsion solvent evaporation method.  

PubMed

The present study was oriented towards microencapsulation of aspirin and the study of its release kinetics. The desired encapsulation was achieved by emulsion solvent evaporation method using ethyl cellulose (EC), cellulose acetate phthalate (CAP) and their mixture (1:1) of polymeric constituents. Characterization of the formulations was performed by size, shape, drug loading efficiency and in-vitro drug release analysis. The in-vitro release profiles from different polymeric microcapsules were applied on different kinetic models. The prepared microcapsules were found free flowing and almost spherical in shape with particle sizes ranging from 300â700Îm, having a loading efficiency of 75â85%. The best fit model with the highest correlation coefficient was observed in Higuchi model, indicating diffusion controlled principle. The n value obtained from Korsemeyer-Peppas model varied between 0.5â0.7, confirming that the mechanism of drug release was diffusion controlled. Comparative studies revealed that the release of aspirin from EC microcapsules was slower as compared to that of CAP and their binary mixture. PMID:21179372

Dash, Vikas; Mishra, Sujeet K; Singh, Manoj; Goyal, Amit K; Rath, Goutam

2009-12-19

109

Release Kinetic Studies of Aspirin Microcapsules from Ethyl Cellulose, Cellulose Acetate Phthalate and their Mixtures by Emulsion Solvent Evaporation Method  

PubMed Central

The present study was oriented towards microencapsulation of aspirin and the study of its release kinetics. The desired encapsulation was achieved by emulsion solvent evaporation method using ethyl cellulose (EC), cellulose acetate phthalate (CAP) and their mixture (1:1) of polymeric constituents. Characterization of the formulations was performed by size, shape, drug loading efficiency and in-vitro drug release analysis. The in-vitro release profiles from different polymeric microcapsules were applied on different kinetic models. The prepared microcapsules were found free flowing and almost spherical in shape with particle sizes ranging from 300–700?m, having a loading efficiency of 75–85%. The best fit model with the highest correlation coefficient was observed in Higuchi model, indicating diffusion controlled principle. The n value obtained from Korsemeyer-Peppas model varied between 0.5–0.7, confirming that the mechanism of drug release was diffusion controlled. Comparative studies revealed that the release of aspirin from EC microcapsules was slower as compared to that of CAP and their binary mixture.

Dash, Vikas; Mishra, Sujeet K.; Singh, Manoj; Goyal, Amit K.; Rath, Goutam

2010-01-01

110

Bioconversion of Cellulose to Acetate with Pure Cultures of Ruminococcus albus and a Hydrogen-Using Acetogen  

PubMed Central

Bioconversion of cellulose to acetate was accomplished with cocultures of two organisms. One was the cellulolytic species Ruminococcus albus. It ferments crystalline cellulose (Avicel) to acetate, ethanol, CO(inf2), and H(inf2). The other organism (HA) obtains energy for growth by using H(inf2) to reduce CO(inf2) to acetate. HA is a gram-negative coccobacillus that was isolated from horse feces. Coculture of R. albus with HA in batch or continuous culture alters the fermentation products formed from crystalline cellulose by the ruminococcus via interspecies H(inf2) transfer. The major product of the fermentation by R. albus and HA coculture is acetate. High concentrations of acetate (333 mM) were obtained when batch cocultures grown on 5% cellulose were neutralized with Ca(OH)(inf2). Continuous cocultures grown at retention times of 2 and 3.1 days produced 109 and 102 mM acetate, respectively, when fed 1% cellulose with utilization of 84% of the substrate.

Miller, T. L.; Wolin, M. J.

1995-01-01

111

Electrospun cellulose acetate fibers: effect of solvent system on morphology and fiber diameter  

Microsoft Academic Search

This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field\\u000a strength (EFS) on the morphological appearance and\\/or size of as-spun cellulose acetate (CA) products. The single-solvent\\u000a systems were acetone, chloroform, N,N\\u000a -dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were\\u000a acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH,

Santi Tungprapa; Tanarinthorn Puangparn; Monchawan Weerasombut; Ittipol Jangchud; Porntiva Fakum; Somsak Semongkhol; Chidchanok Meechaisue; Pitt Supaphol

2007-01-01

112

Amphiphilic conjunct of methyl cellulose and well-defined polyvinyl acetate.  

PubMed

Tailor-made conjunct of methyl cellulose (MC) and polyvinyl acetate (PVAc) was synthesized through the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction. MC was firstly transferred into unsaturated MC (UMC), and then covalently connected with well-defined PVAc obtained by RAFT polymerization of vinyl acetate. The structure of the conjunct polymer (MCV) was confirmed with Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance ((1)H NMR). Well-defined MCV was amphiphilic and able to self-assemble into size controllable micelles, which was verified with transmission electron microscopy (TEM) and size distribution analysis. It was found that the mean diameters of the micelles in aqueous solution were 105.6, 96.0 and 75.9 nm when the number average molecular weights of PVAc segments of MCV were 49,300, 32,500 and 18,200, respectively. PMID:23107808

Xiao, Congming; Xia, Cunping

2012-10-26

113

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

114

Sorption and permeation behaviour of metal thiocyanate complexes on cellulose acetate polymers.  

PubMed

Various metal thiocyanate complexes in aqueous solution were sorbed on solid cellulose acetate polymers. The sorption selectivity increased in the order Zn(2+) > Fe(3+) > Cu(2+) > Co(2+) > Ni(2+). The sorption behaviour followed a Langmuir-type adsorption isotherm, and the maximum adsorption capacity was 6.1 x 10(-5) mole of complex per g of polymer under optimum conditions. The zinc species sorbed appear to be NH(4)Zn(H(2)O)(SCN)(3) or (NH(4))(2)Zn(SCN)(4) according to analysis of the sorption equilibrium. The ion-association species formed by the complex zinc anion and the ammonium ion was supposed to be sorbed (or "extracted") onto the polymer matrix. As an application of sorption of metal complexes, a new hyperfiltration process was proposed for selective separation of metal ions. Thus, a mixture of metal thiocyanate complexes was hyperfiltered through cellulose acetate membranes. Permeation of certain metal complexes was preferred, and the selectivity was found to be similar to the sorption selectivity. These findings lead to a generalized idea that hyperfiltration separation of ionic species, particularly anionic metal complexes, can be attained by using polymer membranes which selectively adsorb or extract such ionic species as ion-association complexes onto the polymer matrix. PMID:18963867

Hayashita, T; Takagi, M

1985-05-01

115

Cobalt (II) chloride promoted formation of honeycomb patterned cellulose acetate films.  

PubMed

CoCl(2) containing honeycomb patterned films were prepared from cellulose acetate (CA)/CoCl(2)/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA/CoCl(2) molar ratio and humidity. When replacing CoCl(2) with Co(NO(3))(2) or CoBr(2), no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron microscopy (SEM), Energy Dispersive X-ray Microanalysis (EDX), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the key role in the formation of honeycomb structures can be attributed to the physical and chemical properties of CoCl(2) - hygroscopicity, low interaction with CA, and extraction from CA/CoCl(2)/acetone solution by water droplets condensed on the surface of the CA/CoCl(2) solution. Obtained films are prospective for using in catalysis, hydrogen fuel cells, and optical sensing materials. PMID:22074692

Naboka, Olga; Sanz-Velasco, Anke; Lundgren, Per; Enoksson, Peter; Gatenholm, Paul

2011-10-20

116

Effect of electro-chemical properties of chloride salts on their diffusional parameters in symmetrical cellulose acetate membranes  

Microsoft Academic Search

A relation was obtained between electro-chemical properties of alkali, alkali-earth and aluminium-chlorides (LiCl, NaCl, KCl, RbCl, CsCl, MgCl2, CaCl2, AlCl3) and the distribution coefficient K and the overall diffusion coefficients D in symmetrical cellulose acetate membranes. Symmetrical cellulose acetate membranes was cast to have a wider range of water content, 15–30%. K and D were measured by the unsteady- and

Haruhiko Ohya; Svetlana I Semenova; Toshinori Fujimoto; Jun Ogihara; Shinichi Fukaya; Kousuke Mori; Masahiko Aihara; Youichi Negishi

2001-01-01

117

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

NASA Astrophysics Data System (ADS)

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 optical fiber sensor to gaseous ammonia at room temperature were investigated. The sensing probe showed different fluorescence intensity at 576 nm to different concentrations of trace ammonia in carrier gas of nitrogen. The response range was 50-400 ppm, with short response time within 500 ms. Furthermore, the response range could be tailored through CTAB co-entrapment process in the sensing film. These test results demonstrated that low cost, simple structured fiber optic sensors for detecting ammonia gas samples could be developed based on MOF.

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

2011-09-01

118

Cellulose acetate-zirconium (IV) phosphate nano-composite with enhanced photo-catalytic activity.  

PubMed

Cellulose acetate-zirconium (IV) phosphate nanocomposite (CA/ZPNC) was synthesized by sol-gel technique at pH 0-1 and was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Fourier infrared spectroscopy (FTIR) and thermal analysis (TGA/DTA/DSC). Ion exchange capacity, pH titration, elution concentration, elution behaviour, thermal stability and distribution coefficient were investigated to explore ion exchange behaviour of CA/ZPNC. The nanocomposite showed an ion-exchange capacity of 1.4 mequiv. g(-1) for Na(+) and was highly selective for Pb(2+) and Zn(2+) over many other metal ions. The photocatalytic activity of the CA/ZPNC was explored for degradation of a model Congo red dye from aqueous phase. 90% of dye was removed in 60 min of irradiation. Simultaneous adsorption and photocatalysis had synergetic effect on dye degradation. PMID:23618290

Gupta, Vinod Kumar; Pathania, Deepak; Singh, Pardeep; Rathore, Bhim Singh; Chauhan, Priyanka

2013-03-04

119

Cellulose acetate polymer film modified microstructured polymer optical fiber towards a nitrite optical probe  

NASA Astrophysics Data System (ADS)

A novel microstructured polymer optical fiber (MPOF) probe for nitrites (NO2-) detection was made by forming rhodamine 6G (Rh 6G)-doped cellulose acetate (CA) on the side wall of array holes in a MPOF. It was found that the MPOF probe only have a response to nitrites in a certain concentration of sulfuric acid solution. The calibration graph of fluorescence intensity versus nitrites concentration was linear in the range of 2.0 × 10- 4 g/ml-5.0 × 10- 3 g/ml. The method possesses ease of chemical modification, low cost design, and potential for direct integration with existing instrumentation, and has been applied to the determination of nitrites in real samples with satisfactory results.

Li, Dongdong; Wang, Lili

2010-07-01

120

Characterization of cellulose acetates according to DS and molar mass using two-dimensional chromatography.  

PubMed

A two-dimensional liquid chromatographic method (2D LC) was developed to analyze the heterogeneities of cellulose acetates (CA) in the DS-range DS=1.5-2.9 with respect to both, molar mass and degree of substitution (DS). The method uses gradient liquid chromatography (HPLC) as the first dimension in order to separate by DS followed by separation of the different fractions by size (SEC) in the second dimension. The 2D experiments revealed different correlations between gradient and SEC elution volume. These correlations might arise from differences in the synthetic conditions. The newly developed 2D LC separation therefore provides new insights into the heterogeneity of CAs. PMID:24053824

Ghareeb, Hewa Othman; Radke, Wolfgang

2013-08-06

121

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...

122

Role of membrane surface morphology in colloidal fouling of cellulose acetate and composite aromatic polyamide reverse osmosis membranes  

Microsoft Academic Search

Laboratory-scale colloidal fouling tests, comparing the fouling behavior of cellulose acetate and aromatic polyamide thin-film composite reverse osmosis (RO) membranes, are reported. Fouling of both membranes was studied at identical initial permeation rates so that the effect of the transverse hydrodynamic force (permeation drag) on the fouling of both membranes is comparable. Results showed a significantly higher fouling rate for

Menachem Elimelech; Xiaohua Zhu; Amy E. Childress; Seungkwan Hong

1997-01-01

123

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

2013-02-27

124

Enhancement of the wet properties of transparent chitosan-acetic-acid-salt films using microfibrillated cellulose.  

PubMed

This report presents a new route to enhance the wet properties of chitosan-acetic-acid-salt films using microfibrillated cellulose (MFC). The enhancement makes it easier to form chitosan-acetic-acid-salt films into various shapes at room temperature in the wet state. Chitosan with MFC was compared with the well-known buffer treatment. It was observed that films containing 5 wt % MFC were visually identical to the buffered/unbuffered films without MFC. Field-emission scanning electron microscopy indicated that MFC formed a network with uniformly distributed fibrils and fibril bundles in the chitosan matrix. The addition of MFC reduced the risk of creases and deformation in the wet state because of a greater wet stiffness. The wet films containing MFC were also extensible. Although the stiffness, strength and extensibility were highest for the buffered films, the wet strength of the MFC-containing unbuffered films was sufficient for wet forming operations. The effects of MFC on the mechanical properties of the dry chitosan films were small or absent. It was concluded that the addition of MFC is an acceptable alternative to buffering for shaping chitosan films/products in the wet state. The advantages are that the "extra" processing step associated with buffering is unnecessary and that the film matrix remains more water-soluble. PMID:17645308

Nordqvist, David; Idermark, Johan; Hedenqvist, Mikael S; Gällstedt, Mikael; Ankerfors, Mikael; Lindström, Tom

2007-07-24

125

Entrap-immobilization of biocatalysts on cellulose acetate-inorganic composite gel fiber using a gel formation ofcellulose acetate–metal (Ti, Zr) alkoxide  

Microsoft Academic Search

We developed a new entrap-immobilization method, using a gel formationof cellulose acetate and metal (Ti, Zr) alkoxide. Several biocatalysts(ß-galactosidase, a-chymotrypsine, invertase, urease, lipase andSaccharomyces cereviciae) were successfullyentrap-immobilized on this composite gel fiber. The immobilization process wassimple and the resultant immobilized biocatalysts on the gel fiber were easy tohandle. It is considered that the biocatalysts are physically entrapped amongthe gel networks

Yuko Ikeda; Youichi Kurokawa; Koji Nakane; Nobuo Ogata

2002-01-01

126

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

2012-12-10

127

Purification and characterization of an endo-1,4-beta-glucanase from Neisseria sicca SB that hydrolyzes beta-1,4 linkages in cellulose acetate.  

PubMed

An enzyme catalyzing hydrolysis of beta-1,4 bonds in cellulose acetate was purified 18.3-fold to electrophoretic homogeneity from a culture supernatant of Neisseria sicca SB, which can assimilate cellulose acetate as the sole carbon and energy source. The molecular mass of the enzyme was 41 kDa and the isoelectric point was 4.8. The pH and temperature optima of the enzyme were 6.0-7.0 and 60 degrees C. The enzyme catalyzed hydrolysis of water-soluble cellulose acetate (degree of substitution, 0.88) and carboxymethyl cellulose. The Km and Vmax for water-soluble cellulose acetate and carboxymethyl cellulose were 0.242% and 2.24 micromol/min/mg, and 2.28% and 12.8 micromol/min/mg, respectively. It is estimated that the enzyme is a kind of endo-1,4-beta-glucanase (EC 3.2.1.4) from the substrate specificity and hydrolysis products of cellooligosaccharides. The enzyme and cellulose acetate esterase from Neisseria sicca SB degraded water-insoluble cellulose acetate by synergistic action. PMID:12005042

Moriyoshi, Kunihiko; Ohmoto, Takashi; Ohe, Tatsuhiko; Sakai, Kiyofumi

2002-03-01

128

Acidic extracellular pH shifts colorectal cancer cell death from apoptosis to necrosis upon exposure to propionate and acetate, major end-products of the human probiotic propionibacteria  

Microsoft Academic Search

The human probiotic Propionibacterium freudenreichii kills colorectal adenocarcinoma cells through apoptosis in vitro via its metabolites, the short chain fatty acids (SCFA), acetate and propionate. However, the precise mechanisms, the kinetics\\u000a of cellular events and the impact of environmental factors such as pH remained to be specified. For the first time, this study\\u000a demonstrates a major impact of a shift

Annaïg Lan; Dominique Lagadic-Gossmann; Christophe Lemaire; Catherine Brenner; Gwénaël Jan

2007-01-01

129

Optical, bactericidal and water repellent properties of electrospun nano-composite membranes of cellulose acetate and ZnO.  

PubMed

In this report, ZnO nanoparticles embedded cellulose acetate (CA) fibrous membrane with multifunctional properties have been prepared through electrospinning method. The morphology of the electrospun composite membrane was analyzed by scanning electron microscope (SEM). It was found that the polymer concentration in the solution has a significant effect on the morphology of the fibers. The optical property of the sample was tested using photo luminescence (PL) spectra. There is no significant change in the emission features of cellulose acetate with the addition of ZnO. The anti-bacterial property of the sample was studied using disk diffusion method. The wettability of the pure and composite fibrous membrane was also studied by measuring the contact angle of water on the membrane. It was observed that the embedded ZnO in the CA was responsible for the hydrophobic nature of the surface. PMID:24066357

Anitha, S; Brabu, B; John Thiruvadigal, D; Gopalakrishnan, C; Natarajan, T S

2013-07-01

130

Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas, Phase 1. [Polyetherimide, cellulose acetate and ethylcellulose  

SciTech Connect

The goal of this program is to develop polymer membranes useful in the preparation of hydrogen from coal-derived synthesis gas. During this quarter the first experiment were aimed at developing high performance composite membranes for the separation of hydrogen from nitrogen and carbon monoxide. Three polymers have been selected as materials for these membranes: polyetherimide cellulose acetate and ethylcellulose. This quarter the investigators worked on polyetherimide and cellulose acetate membranes. The overall structure of these membranes is shown schematically in Figure 1. As shown, a microporous support membrane is first coated with a high flux intermediate layer then with an ultrathin permselective layer and finally, if necessary, a thin protective high flux layer. 1 fig., 4 tabs.

Not Available

1986-01-01

131

Diameter-tuning of electrospun cellulose acetate fibers: a Box-Behnken design (BBD) study.  

PubMed

This work focuses on the use of statistical approach in optimizing shape-size accord of electrospun cellulose acetate (CA) mats - an apt material for biomedical and industrial applications. Modulation of three processing parameters, namely potential difference, distance between tip-to-collector and feed rate led to myriad of fiber-morphology (beaded, bead free, branched and ribbon) with diverse size-spectrum. Response surface methodology using Box-Behnken design technique indicated significant linear and quadratic influence of the chosen parameters. Fibers with minimal diameter of ~139 nm (with a mean coherency co-efficient of 0.5192) were predicted for 30 kV (voltage), 15 cm (tip-to-collector distance) and 2 mL/h (feed rate). Reasonable agreement existed between the predicted R-squared value (0.9565) and adjusted R-squared value (0.9824) with similar observation for the experimental and model values over the entire factor space. The developed model may serve as a base model for understanding process - parametric influence on electrospinning CA and related polymers. PMID:23399134

Konwarh, Rocktotpal; Misra, Manjusri; Mohanty, Amar K; Karak, Niranjan

2012-10-30

132

Cytotoxicity and antitumour activity of 5-fluorouracil-loaded polyhydroxybutyrate and cellulose acetate phthalate blend microspheres.  

PubMed

Pharmacokinetics, biodistribution and antitumour activity of 5-fluorouracil (5-FU)-loaded polyhydroxybutyrate (PHB) and cellulose acetate phthalate (CAP) blend microspheres were investigated in chemically induced colorectal cancer in albino male Wistar rats and compared with pristine 5-FU given as a suspension. The microspheres were characterised for particle size, encapsulation efficiency, in vitro release and in vitro cytotoxicity on human HT-29 colon cancer cell line. Spherical particles with a mean size of 44?±?11?µm were obtained that showed sustained release of 5-FU. A high concentration of 5-FU was achieved in colonic tissues and significant reduction in tumour volume and multiplicity were observed in animals treated with 5-FU-loaded microspheres. The decreased levels of plasma albumin, creatinine, leucocytopenia and thrombocytopenia were observed in animals for 5-FU microspheres compared to the standard 5-FU formulation. The results suggest the extended release of 5-FU from the PHB-CAP blend microspheres in colonic region to enhance the antitumour efficacy. PMID:23078151

Chaturvedi, Kiran; Tripathi, Santosh Kumar; Kulkarni, Anandrao R; Aminabhavi, Tejraj M

2012-10-18

133

Carbon nanotube-incorporated multilayered cellulose acetate nanofibers for tissue engineering applications.  

PubMed

We report the fabrication of a novel carbon nanotube-containing nanofibrous polysaccharide scaffolding material via the combination of electrospinning and layer-by-layer (LbL) self-assembly techniques for tissue engineering applications. In this approach, electrospun cellulose acetate (CA) nanofibers were assembled with positively charged chitosan (CS) and negatively charged multiwalled carbon nanotubes (MWCNTs) or sodium alginate (ALG) via a LbL technique. We show that the 3-dimensional fibrous structures of the CA nanofibers do not appreciably change after the multilayered assembly process except that the surface of the fibers became much rougher than that before assembly. The incorporation of MWCNTs in the multilayered CA fibrous scaffolds tends to endow the fibers with improved mechanical property and promote fibroblast attachment, spreading, and proliferation when compared with CS/ALG multilayer-assembled fibrous scaffolds. The approach to engineering the nanofiber surfaces via LbL assembly likely provides many opportunities for new scaffolding materials design in various tissue engineering applications. PMID:23044152

Luo, Yu; Wang, Shige; Shen, Mingwu; Qi, Ruiling; Fang, Yi; Guo, Rui; Cai, Hongdong; Cao, Xueyan; Tomás, Helena; Zhu, Meifang; Shi, Xiangyang

2012-08-25

134

Disc-electrospun cellulose acetate butyrate nanofibers show enhanced cellular growth performances.  

PubMed

Cellulose acetate butyrate nanofibers were prepared separately by two electrospinning techniques; a needleless electrospinning using a disc as spinneret and a rotary drum as collector and a conventional needle electrospinning using a rotary drum as collector. Compared to the needle-electrospun nanofibers, the disc-electrospun nanofibers were coarser with a wider diameter distribution. Both fibers had a similar surface morphology and they showed no difference in chemical components, but the disc-electrospun nanofibers were slightly higher in crystallinity. The productivity of disc electrospinning was 150 times larger than that of needle electrospinning. The disc-electrospun nanofiber mats were found to have a three dimensional fibrous structure with an average pore size of 9.1 ?m, while the needle-electrospun nanofibers looked more like a two-dimensional sheet with a much smaller average pore size (3.2 ?m). Fibroblasts and Schwann cells were cultured on the fibrous matrices to assess the biocompatibility. The disc-electrospun nanofiber webs showed enhanced cellular growth for both fibroblasts and Schwann cells, especially in a long culture period. PMID:22826213

Huang, Chen; Niu, Haitao; Wu, Chunchen; Ke, Qinfei; Mo, Xiumei; Lin, Tong

2012-07-24

135

Biocompatibility and characteristics of chitosan/cellulose acetate microspheres for drug delivery  

NASA Astrophysics Data System (ADS)

In this work, chitosan/cellulose acetate microspheres (CCAM) were prepared by the method of W/O/W emulsion with no toxic reagents. The microspheres were spherical, free flowing, and non-aggregated, which had a narrow size distribution. More than 90% of the microspheres had the diameter ranging from 200 to 280 ?m. The hemolytic analysis indicated that CCAM was safe and had no hemolytic effect. The implanted CCAM did not produce any significant changes in the hematology of Sprague-Dawley (SD) rats, such as white blood cell, red blood cell, platelet, and the volume of hemoglobin. In addition, the levels of serum alanine aminotransferase, blood urea nitrogen, and creatinine had no obvious changes in SD rats implanted with CCAM, surger thread, or normal SD rats without any implantation. Thus, the CCAM had good blood compatibility and had no hepatotoxicity or renal toxicity to SD rats. Furthermore, CCAM with or without the model drug had good tissue compatibility with respect to the inflammatory reaction in SD rats and showed no significant difference from that of SD rats implanted with surgery thread. CCAM shows promise as a long-acting delivery system, which had good biocompatibility and biodegradability.

Zhou, Hui-Yun; Zhou, Dong-Ju; Zhang, Wei-Fen; Jiang, Ling-Juan; Li, Jun-Bo; Chen, Xi-Guang

2011-12-01

136

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

2012-07-31

137

Enzymatic activation of cellulose acetate membrane for reducing of protein fouling.  

PubMed

In this study, the surface of cellulose acetate (CA) ultrafiltration membrane was activated with serine protease (Savinase) enzyme to reduce protein fouling. Enzyme molecules were covalently immobilized with glutaraldehyde (cross-linking agent) onto the surface of CA membranes. The membrane activation was verified using filtration experiments and morphological analysis. Scanning electron microscopy (SEM) images and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy of the activated membrane when compared with raw membrane were confirmed that the enzyme was immobilized onto the membrane surface. The immobilization efficiencies changed from 13.2 to 41.2% according to the enzyme ratios from 2.5 to 10.0 mg/mL. However, the permeability values decreased from 232±6 to 121±4 L/m(2) h bar with increasing enzyme concentration from 2.5 to 10.0 mg/mL. In fouling experiments, bovine serum albumin (BSA) was used as the protein model solution and activated sludge was used as the model biological sludge. Enzyme-activated membranes exhibited good filtration performances and protein rejection efficiencies were compared with raw CA membrane. Also the relative flux reduction (RFR) ratios of membranes were calculated as 97% and 88% for raw CA and enzyme-activated membranes (5 mg/mL savinase), respectively. The membrane activated with Savinase enzyme could be proposed as a surface treatment method before filtration to mitigate protein fouling. PMID:22218336

Koseoglu-Imer, Derya Y; Dizge, Nadir; Koyuncu, Ismail

2011-12-20

138

Observation of SERS of picolinic acid and nicotinic acid using cellulose acetate films doped with Ag fine particles  

NASA Astrophysics Data System (ADS)

Surface enhanced Raman (SER) spectra of picolinic acid and nicotinic acid were observed using cellulose acetate (CA) films doped with Ag fine particles. The spectra obtained match those reported for silver colloids though some differences in SER band intensity were observed. The ease of preparation and handling of the CA film method renders it more useful than the colloid method for the observation of SER spectra.

Imai, Yoshika; Kurokawa, Yoichi; Hara, Masaru; Fukushima, Michiko

1997-10-01

139

Anti-HIV-1 activity of cellulose acetate phthalate: Synergy with soluble CD4 and induction of \\  

Microsoft Academic Search

BACKGROUND: Cellulose acetate phthalate (CAP), a promising candidate microbicide for prevention of sexual transmission of the human immunodeficiency virus type 1 (HIV-1) and other sexually transmitted disease (STD) pathogens, was shown to inactivate HIV-1 and to block the coreceptor binding site on the virus envelope glycoprotein gp120. It did not interfere with virus binding to CD4. Since CD4 is the

A Robert Neurath; Nathan Strick; Shibo Jiang; Yun-Yao Li; Asim K Debnath

2002-01-01

140

The Use of Cellulose Acetate for the Electrophoretic Separation and Quantitation of Serum Lactic Dehydrogenase Isozymes in Normal and Pathologic States.  

National Technical Information Service (NTIS)

Normal and abnormal lactic dehydrogenase (LDH) isozyme distribution in serum was studied using cellulose acetate electrophoresis with a p-iodonitro tetrazolium violet (INT) stain, and a graphing procedure devised to permit rapid visualization and evaluati...

M. Mager W. F. Blatt W. H. Abelmann

1966-01-01

141

Mode of action on deacetylation of acetylated methyl glycoside by cellulose acetate esterase from Neisseria sicca SB.  

PubMed

The regioselective deacetylation of purified cellulose acetate esterase from Neisseria sicca SB was investigated on methyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside and 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside. The substrates were used as model compounds of cellulose acetate in order to estimate the mechanism for deacetylation of cellulose acetate by the enzyme. The enzyme rapidly deacetylated at position C-3 of methyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside to accumulate 2,4,6-triacetate as the main initial reaction product in about 70% yield. Deacetylation was followed at position C-2, and generated 4,6-diacetate in 50% yield. The enzyme deacetylated the product at positions C-4 and C-6 at slower rates, and generated 4- and 6-monoacetates at a later reaction stage. Finally, it gave a completely deacetylated product. For 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside, CA esterase deacetylated at positions C-3 and C-6 to give 2,4,6- and 2,3,4-triacetate. Deacetylation proceeded sequentially at positions C-3 and C-6 to accumulate 2,4-diacetate in 55% yield. The enzyme exhibited regioselectivity for the deacetylation of the acetylglycoside. PMID:16041133

Moriyoshi, Kunihiko; Yamanaka, Hayato; Ohmoto, Takashi; Ohe, Tatsuhiko; Sakai, Kiyofumi

2005-07-01

142

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

143

Cellulose acetate-directed growth of bamboo-raft-like single-crystalline selenium superstructures: high-yield synthesis, characterization, and formation mechanism.  

PubMed

High-yield synthesis of bamboo-raft-like single-crystalline selenium superstructures has been realized for the first time via a facile solvothermal approach by reducing SeO2 with ethylene alcohol in the presence of cellulose acetate. The formation of a raftlike superstructure with various forms is strongly dependent on the temperature, amount of cellulose acetate, reaction time, and even preheating treatment. The suitable amount of cellulose acetate is essential for the formation of elegant and uniform raft Se. The morphology, microstructure, optical properties, and chemical compositions of bamboo-raft-like selenium were characterized using various techniques (X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution (HR) TEM, X-ray photoelectron spectroscopy, UV-vis spectroscopy, FTIR spectroscopy, and Raman spectroscopy). A possible growth mechanism has been proposed. Such special superstructures could provide a useful precursor for potential applications. PMID:17523685

Song, Ji-Ming; Zhan, Yong-Jie; Xu, An-Wu; Yu, Shu-Hong

2007-05-25

144

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

2010-09-07

145

Rapid detection of adulterations of fruit juices, lemonades etc. by electrophoresis on cellulose acetate membranes  

Microsoft Academic Search

Zusammenfassung Es wurde eine Schnellmethode zum Nachweis der Verfälschungen von Fruchtsäften und Getränken mittels Elektrophorese und Vergleich der Hauptaminosäurebanden (Cellulose-acetat-Membran; Pufferlösung aus 0,25n Essigsäure\\/0,65n Ameisensäure; Anfärbung mit Ninhydrin) entwickelt. Die untere Nachweisgrenze beträgt etwa 0,01 mg Aminosäure\\/ml.

Wilhelm F. van Gils; Johannes A. van den Bergh

1974-01-01

146

Investigation of the effect of cho groups in the cellulose molecule on the stability of the acetal bond in an acid medium using model compounds  

Microsoft Academic Search

1.Comparison of the hydrolysis rates of D'-methoxy-D-hydroxy-methyldiglycolaldehyde and a-methylglucoside showed that a CHO group in the a-position relative to an acetal bond lowers the stability of the latter in an acid medium.2.The formation of CHO groups at C2 and C3 in an oxidized unit of a cellulose molecule must lead to weakening of the acetal bond in it in an

Z. I. Kuznetsova; V. I. Ivanov

1960-01-01

147

Solid dispersion of quercetin in cellulose derivative matrices influences both solubility and stability.  

PubMed

Amorphous solid dispersions (ASD) of quercetin (Que) in cellulose derivative matrices, carboxymethylcellulose acetate butyrate (CMCAB), hydroxypropylmethylcellulose acetate succinate (HPMCAS), and cellulose acetate adipate propionate (CAAdP) were prepared with the goal of identifying an ASD that effectively increased Que aqueous solution concentration. Crystalline quercetin and Que/poly(vinylpyrrolidinone) (PVP) ASD were evaluated for comparison. Powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC) were used to examine the crystallinity of ASDs, physical mixtures (PM) and quercetin. ASDs were amorphous up to 50 wt% Que. Que stability against crystallization and solution concentrations from these ASDs were significantly higher than those observed for physical mixtures and crystalline Que. PVP stabilizes against both Que degradation and recrystallization; in contrast, these carboxylated cellulose derivatives inhibit recrystallization but release Que slowly. PVP ASDs afforded fast and complete drug release, while ASDs using these three cellulose derivatives provide slow, incomplete, pH-triggered drug release. PMID:23399255

Li, Bin; Konecke, Stephanie; Harich, Kim; Wegiel, Lindsay; Taylor, Lynne S; Edgar, Kevin J

2012-12-03

148

Cellulose acetate phthalate, a common pharmaceutical excipient, inactivates HIV1 and blocks the coreceptor binding site on the virus envelope glycoprotein gp120  

Microsoft Academic Search

BACKGROUND: Cellulose acetate phthalate (CAP), a pharmaceutical excipient used for enteric film coating of capsules and tablets, was shown to inhibit infection by the human immunodeficiency virus type 1 (HIV-1) and several herpesviruses. CAP formulations inactivated HIV-1, herpesvirus types 1 (HSV-1) and 2 (HSV-2) and the major nonviral sexually transmitted disease (STD) pathogens and were effective in animal models for

A Robert Neurath; Nathan Strick; Yun-Yao Li; Asim K Debnath

2001-01-01

149

Cellulose acetate butyrate–pH\\/thermosensitive polymer microcapsules containing aminated poly(vinyl alcohol) microspheres for oral administration of DNA  

Microsoft Academic Search

The aim of this work is to safely transport bioadhesive microspheres loaded with DNA to intestine and to test their bioadhesive properties. Poly(vinyl alcohol) (PVA) microspheres were prepared by dispersion reticulation with glutaraldehyde and further aminated. These microspheres were firstly loaded with plasmid DNA by electrostatic interactions and then entrapped in cellulose acetate butyrate (CAB) microcapsules for gastric protection. The

Gheorghe Fundueanu; Marieta Constantin; Fabrizio Bortolotti; Rita Cortesi; Paolo Ascenzi; Enea Menegatti

2007-01-01

150

Electrospun carboxymethyl cellulose acetate butyrate (CMCAB) nanofiber for high rate lithium-ion battery.  

PubMed

Cellulose derivative CMCAB was synthesized, and nanometer fiber composite material was obtained from lithium iron phosphate (LiFePO4, LFP)/CMCAB by electrospinning. Under the protection of inert gas, modified LFP/carbon nanofibers (CNF) nanometer material was obtained by carbonization in 600°C. IR, TG-DSC, SEM and EDS were performed to characterize their morphologies and structures. LFP/CNF composite materials were assembled into lithium-ion battery and tested their performance. Specific capacity was increased from 147.6 mAh g(-1) before modification to 160.8 mAh g(-1) after modification for the first discharge at the rate of 2C. After 200 charge-discharge cycles, when discharge rate was increased from 2C to 5C to 10C, modified battery capacity was reduced from 152.4 mAh g(-1) to 127.9 mAh g(-1) to 106 mAh g(-1). When the ratio was reduced from 10C to 5C to 2C, battery capacity can be quickly approximate to the original level. Cellulose materials that were applied to lithium battery can improve battery performance by electrospinning. PMID:23688476

Qiu, Lei; Shao, Ziqiang; Yang, Mingshan; Wang, Wenjun; Wang, Feijun; Xie, Long; Lv, Shaoyi; Zhang, Yunhua

2013-03-28

151

Mode of action of acetylesterases associated with endoglucanases towards water-soluble and -insoluble cellulose acetates  

Microsoft Academic Search

A screening of commercial enzyme preparations for the capability ofcellulose acetate (CA) deacetylation revealed that such enzyme activity ismore common than could be anticipated. Enzyme-aided deacetylation of celluloseacetate was clearly a function of the degree of substitution (DS). Celluloseacetates up to a DS of 1.4 were deacetylated by a large number of enzyme mixes.Interestingly, none of the investigated enzyme preparations

Clemens Altaner; Bodo Saake; Jürgen Puls

2001-01-01

152

Vibrational and theoretical studies of non-steroidal anti-inflammatory drugs Ibuprofen [2-(4-isobutylphenyl)propionic acid]; Naproxen [6-methoxy-?-methyl-2-naphthalene acetic acid] and Tolmetin acids [1-methyl-5-(4-methylbenzoyl)-1H-pyrrole-2-acetic acid  

NASA Astrophysics Data System (ADS)

Mid-, far-infrared, and Raman vibrational spectra of Ibuprofen [2-(4-isobutylphenyl) propionic] acid, Naproxen [6-methoxy-?-methyl-2-naphthalene acetic] acid and Tolmetin [1-methyl-5-(4-methylbenzoyl)-1H-pyrrole-2-acetic] acid have been measured at room and low temperatures and analyzed by means of ab initio calculations. The conformational space of these compounds has been scanned using molecular dynamics and complemented with functional density calculations that optimize the geometry of the lowest-energy conformers of each species as obtained in the simulations. The vibrational frequencies were assigned using functional density calculations. The Molecular Electrostatic Potential Maps were obtained and analyzed and the corresponding topological study was performed in the Bader's theory (atoms in molecules) framework.

Jubert, Alicia; Legarto, María Leticia; Massa, Néstor E.; Tévez, Leonor López; Okulik, Nora Beatriz

2006-02-01

153

Pathway of propionate formation in Desulfobulbus propionicus  

Microsoft Academic Search

Whole cells of Desulfobulbus propionicus fermented [1-13C]ethanol to [2-13C] and [3-13C]propionate and [1-13C]-acetate, which indicates the involvement of a randomizing pathway in the formation of propionate. Cell-free extracts prepared from cells grown on lactate (without sulfate) contained high activities of methylmalonyl-CoA: pyruvate transacetylase, acetase kinase and reasonably high activities of NAD(P)-independent L(+)-lactate dehydrogenase NAD(P)-independent pyruvate dehydrogenase, phosphotransacetylase, acetate kinase and

Alfons J. M. Stams; Diderik R. Kremer; Klaas Nicolay; Gerard H. Weenk; Theo A. Hansen

1984-01-01

154

Nanoincorporation of layered double hydroxides into a miscible blend system of cellulose acetate with poly(acryloyl morpholine).  

PubMed

Blend miscibility of cellulose acetate (CA) with poly(acryloyl morpholine) (PACMO) was examined by thermal transition measurements and solid-state (13)C NMR spectroscopy, in which CA materials of acetyl DS=1.80-2.95 were used. All the blends prepared gave a single Tg and formed an amorphous monophase homogeneous within a distance of ?2.0nm. An Al/Mg-based, layered double hydroxide (LDH) was modified with different ionic oligomers, and an attempt was made to incorporate the respective organophilic LDHs (3-3.5wt%) into blend films of the miscible PACMO/CA pair, via bulk polymerization of an ACMO monomer/organo-LDH mixture and then blending CA with the polymer/inorganic hybrid precursor. Particularly, 12-hydroxystearic acid-modified LDH was well exfoliated and ultimately dispersed in the PACMO/CA matrix on a scale of less than a few tens of nanometers in thickness. This gave rise to a successful reinforcement effect leading to the improvement in thermo-mechanical property of the polymer blends. PMID:23465938

Yoshitake, Sachi; Suzuki, Tetsuya; Miyashita, Yoshiharu; Aoki, Dan; Teramoto, Yoshikuni; Nishio, Yoshiyuki

2012-03-23

155

Facile fouling resistant surface modification of microfiltration cellulose acetate membranes by using amino acid L-DOPA.  

PubMed

A major obstacle in the widespread application of microfiltration membranes in the wet separation processes such as wastewater treatment is the decline of permeates flux as a result of fouling. This study reports on the surface modification of cellulose acetate (CA) microfiltration membrane with amino acid L-3,4-dihydroxy-phenylalanine (L-DOPA) to improve fouling resistance of the membrane. The membrane surface was characterised using Fourier transform infrared spectroscopy (FTIR), water contact angle and zeta potential measurement. Porosity measurement showed a slight decrease in membrane porosity due to coating. Static adsorption experiments revealed an improved resistance of the modified membranes towards the adhesion of bovine serum albumin (BSA) as the model foulant. Dead end membrane filtration tests exhibited that the fouling resistance of the modified membranes was improved. However, the effect of the modification depended on the foulant solution concentration. It is concluded that L-DOPA modification is a convenient and non-destructive approach to enable low-BSA adhesion surface modification of CA microfiltration membranes. Nevertheless, the extent of fouling resistance improvement depends on the foulant concentration. PMID:23985522

Azari, Sara; Zou, Linda; Cornelissen, Emile; Mukai, Yasushito

2013-01-01

156

Fouling propensity and separation efficiency of epoxidated polyethersulfone incorporated cellulose acetate ultrafiltration membrane in the retention of proteins  

NASA Astrophysics Data System (ADS)

Epoxidated polyethersulfone (EPES) incorporated cellulose acetate (CA) ultrafiltration membranes were prepared by diffusion induced precipitation technique in the absence and presence of pore former polyethyleneglycol-600. Effect of blend ratio on the compatibility, thermal stability, mechanical strength, hydrophilicity, morphology, pure water flux, protein adsorption resistance, protein separation efficiency and fouling propensity of the CA/EPES blend membranes was evaluated. Addition of EPES results in the formation of thin separating layer and spongy sub layer in CA/EPES blend membranes. The efficiency of these membranes in the separation of commercially important proteins such as bovine serum albumin, egg albumin, pepsin and trypsin was studied and found to be enhanced as compared to CA membranes. The fouling-resistant capability of the membranes was studied by bovine serum albumin as the model foulant and flux recovery ratio of the membranes were calculated. Attempts have been made to correlate the changes in membrane morphology with pure water flux, hydraulic resistance, thermal and mechanical stability, separation efficiency and antifouling property of the CA/EPES membranes. The optimal combination of CA and EPES, thus allows the preparation of high performance UF membranes which are sufficiently dense to retain proteins and at the same time give economically viable fluxes.

Jayalakshmi, A.; Rajesh, S.; Mohan, D.

2012-10-01

157

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

2012-11-28

158

Preparation of cellulose acetate nano-biocomposites using acidified gelatin-montmorillonite as nanofiller: Morphology and thermal properties  

NASA Astrophysics Data System (ADS)

Nano-biocomposites, based on natural polymer as matrix and layered silicates as inorganic nano-fillers, represent an emerging group of hybrid materials. Their advance has strong promise in designing eco-friendlynanocomposites with enhanced properties (mechanical, barrier, thermal...), at low filler levels, of great interest forseveral applications. Thus, this current contribution focuses on the development of Eco-friendly nanocomposites filmsbased on cellulose acetate (CA) and a novel organoclay, prepared from sodium montmorillonite and acidified gelatin asbio-modifier (MMT-AGe), using solution casting process. The effect of clay loading on morphology and properties ofbiomaterials was studied. The nano-hybrids materials elaborated at different clay content were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The clay dispersion was investigated by X-Ray Diffraction (XRD). It wassuggested the formation of disordered intercalated structures or partially exfoliated/intercalated ones, with small claytactoïds remaining. Tg and Tm values, evaluated using Differential Scanning Calorimeter analysis (DSC), were slightlyaffected with addition of clay compared to neat CA, while significant improvement in thermal stability, was observed bymeans of thermogravimetric analysis (TGA), being the highest at 5 wt % clay loading. The unique properties of thesenano-biocomposites may result from the interactions developed between the groups of CA and bio-modified MMT.

Ferfera-Harrar, Hafida; Dairi, Nassima

2012-07-01

159

Assessment of the elution of charcoal, cellulose acetate, and other particles from cigarettes with charcoal and activated charcoal/resin filters.  

PubMed

This experiment was designed to study the release of cellulose acetate fibers, charcoal, and other particles from cigarettes with charcoal and activated charcoal/resin filters. For the first time in such studies, efforts were made to identify the particles that were eluted using other analytical techniques in addition to light microscopy. Other corrective measures were also implemented. During the studies it was found that trimming of larger filters to fit smaller filter housings introduced cellulose acetate-like particles from the fibers of the filter material. Special, custom made-to-fit filters were used instead. Tools such as forceps that were used to retrieve filters from their housings were also found to introduce fragments onto the filters. It is believed that introduction of such debris may have accounted for the very large number of cellulose acetate and charcoal particles that had been reported in the literature. Use of computerized particle-counting microscopes appeared to result in excessive number of particles. This could be because the filter or smoke pads used for such work do not have the flat and level surfaces ideal for computerized particle-counting microscopes. At the high magnifications that the pads were viewed for particles, constant focusing of the microscope would be essential. It was also found that determination of total particles by using extrapolation of particle count by grid population usually gave extremely high particle counts compared to the actual number of particles present. This could be because particle distributions during smoking are not uniform. Lastly, a less complex estimation of the thickness of the particles was adopted. This and the use of a simple mathematical conversion coupled with the Cox equation were utilized to assess the aerodynamic diameters of the particles. Our findings showed that compared to numbers quoted in the literature, only a small amount of charcoal, cellulose acetate shards, and other particles are released. It was also shown that those particles would have a low likelihood of reaching the lung. PMID:16036754

Agyei-Aye, K; Appleton, S; Rogers, R A; Taylor, C R

2004-08-01

160

Effect of electro-chemical properties of sodium salts of various anions on their diffusional parameters in symmetrical cellulose acetate membranes  

Microsoft Academic Search

A relation was obtained between electro-chemical properties of sodium salts (NaCl, NaBr, and Na2SO4), and the thermodynamic property of permeability in symmetrical cellulose acetate membranes, the distribution coefficient K and the kinetic property, the overall diffusion coefficients D.K and D were obtained by the method we proposed using measured unsteady- and steady-state dialysis data. The K values increase with the

Haruhiko Ohya; Svetlana I Semenova; Aya Sawada; Shinichi Fukaya; Yohei Suzuki; Masahako Aihara; Youichi Negishi

2001-01-01

161

Electrospun cellulose acetate nanofibers as thin layer chromatographic media for eco-friendly screening of steroids adulterated in traditional medicine and nutraceutical products.  

PubMed

Nanofibers fabricated from cheap, naturally derived biopolymer, namely cellulose acetate via facile electrospinning technique were successfully applied for the first time to use as separation media for thin layer chromatography (TLC). From the optimization studies, uniform, bead-free nanofibers with good adherence to the backing plates were obtained by electrospinning 17% (w/v) cellulose acetate solution prepared in acetone/N,N-dimethylacetamide (2:1, v-v), using a feed rate of 0.6mL/h and an electrostatic field strength of 17.5kV/15cm for 4h. The nanofibers exhibited reversed phase characteristics, thereby offering the possibility to use simple, polar and more environmental friendly mixtures of water and alcohols as mobile phase. In this work, the application of the fabricated fibers was illustrated by using them combined with the optimal mobile phase e.g. ethanol/water (40:60, v-v) for the screening of steroids adulterated in traditional medicine and nutraceutical products. Due to the satisfactory separation performance, electrospun cellulose acetate nanofibers were shown to be an efficient alternative for TLC media and could be potentially used for the development of green and facile analytical methods. PMID:24054581

Rojanarata, Theerasak; Plianwong, Samarwadee; Su-Uta, Kosit; Opanasopit, Praneet; Ngawhirunpat, Tanasait

2013-05-03

162

Fragrance material review on benzyl propionate.  

PubMed

A toxicologic and dermatologic review of benzyl propionate when used as a fragrance ingredient is presented. Benzyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1 to 4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for benzyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, skin sensitization, elicitation, toxicokinetics, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414642

McGinty, D; Letizia, C S; Api, A M

2012-03-05

163

Fragrance material review on anisyl propionate.  

PubMed

A toxicologic and dermatologic review of anisyl propionate when used as a fragrance ingredient is presented. Anisyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for anisyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al., 2012 for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406577

McGinty, D; Letizia, C S; Api, A M

2012-03-03

164

Fragrance material review on 2-phenoxyethyl propionate.  

PubMed

A toxicologic and dermatologic review of 2-phenoxyethyl propionate when used as a fragrance ingredient is presented. 2-Phenoxyethyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-phenoxyethyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, skin sensitization, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414653

McGinty, D; Letizia, C S; Api, A M

2012-03-06

165

Fragrance material review on phenethyl propionate.  

PubMed

A toxicologic and dermatologic review of phenethyl propionate when used as a fragrance ingredient is presented. Phenethyl propionate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for phenethyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, and elicitation data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406565

McGinty, D; Vitale, D; Letizia, C S; Api, A M

2012-03-03

166

Fragrance material review on ?-methylbenzyl propionate.  

PubMed

A toxicologic and dermatologic review of ?-methylbenzyl propionate when used as a fragrance ingredient is presented. ?-Methylbenzyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate, and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for ?-methylbenzyl propionate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406572

McGinty, D; Letizia, C S; Api, A M

2012-03-03

167

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.

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

2010-01-01

168

21 CFR 184.1784 - Sodium propionate.  

Code of Federal Regulations, 2013 CFR

...C3 H5 NaO2 , CAS Reg. No. 137-40-6) is the sodium salt of propionic acid. It occurs as colorless, transparent crystals or a granular crystalline powder. It is odorless, or has a faint acetic-butyric acid odor, and is deliquescent. It...

2013-04-01

169

Biological effects of propionic acid in humans; metabolism, potential applications and underlying mechanisms  

Microsoft Academic Search

Undigested food is fermented in the colon by the microbiota and gives rise to various microbial metabolites. Short-chain fatty acids (SCFA), including acetic, propionic and butyric acid, are the principal metabolites produced. However, most of the literature focuses on butyrate and to a lesser extent on acetate; consequently, potential effects of propionic acid (PA) on physiology and pathology have long

Sa'ad H. Al-Lahham; Maikel P. Peppelenbosch; Han Roelofsen; Roel J. Vonk; Koen Venema

2010-01-01

170

Investigation of the pore structure and morphology of cellulose acetate membranes using small-angle neutron scattering. 2: Ultrafiltration and reverse-osmosis membranes  

SciTech Connect

Pore structure in cellulose acetate ultrafiltration (UF) and reverse-osmosis (RO) membranes has been studied using small-angle neutron scattering. Scattering experiments were carried out on dry membranes as well as on membranes swollen with deuterated solvents (D[sub 2]O and CD[sub 3]OD). In addition, the RO membranes were studied both before and after annealing (a process of heating a membrane in a water bath at [approximately]75 C to improve its separation properties). The pore surface in UF membranes was found to be smooth and nonfractal, as evidenced by the fourth power law behavior at high Q. Values of average pore sizes obtained for dry and solvent swollen membranes agree well with pore sizes obtained by other methods. For cellulose acetate RO membranes in their dry state, the unannealed membrane appears to consist of two discrete pore size distributions in the intermediate and high Q region while the annealed membrane contains a much wider distribution of pore sizes. These results give a good account of the changes occurring in the structure of RO membranes as a result of annealing, and agree well with the prediction of other authors.

Kulkarni, S.; Krause, S. (Rensselaer Polytechnic Inst., Troy, NY (United States)); Wignall, G.D. (Oak Ridge National Lab., TN (United States). Solid State Div.)

1994-11-07

171

Synthesis of ?-Heteroaryl Propionates via Trapping of Carbocations with ?-Nucleophiles  

PubMed Central

A variety of heterocyclic alcohols and acetates were coupled with silyl ketene acetals and other ?-nucleophiles in the presence of trimethylsilyl trifluoromethanesulfonate to provide an array of substituted ?-heteroaryl propionates, including those with contiguous quaternary centers, as well as vinylogs thereof. This reaction also proceeds with high diastereoselectivity when the ?-nucleophile bears a chiral auxiliary.

Fu, Tsung-hao; Bonaparte, Amy; Martin, Stephen F.

2009-01-01

172

Propionate in Heme Biosynthesis in Soybean Nodules 1  

PubMed Central

When soybean nodules are incubated with propionate-2-14C the heme moiety of leghemoglobin becomes labeled. The incorporation of propionate-2-14C into heme is linear with time and it appears that propionate is utilized without a lag period. The rate of incorporation of propionate-2-14C into heme is more rapid than the rate of incorporation of succinate-2-14C and citrate-1,5-14C, however, these rates of incorporation may be influenced by different sizes of endogenous pools of organic acids. Additional radioactive tracer experiments demonstrate that the supply of heme precursors from propionate is competitive with the supply of heme precursors from the citric acid cycle. When the concentration of propionate was high in the incubation mixture, the rate of succinate-2-14C incorporation into heme was decreased. Furthermore, when a large amount of succinate or acetate is added to the incubation mixture containing whole nodules, the rate of incorporation of propionate-2-14C into heme is reduced. The data support the hypothesis that propionate utilization makes possible a mechanism for the formation of succinyl-CoA in addition to that provided by the citric acid cycle. The fact that propionate is readily utilized by bacteroids suggested that this compound may be a normal metabolite in nodules. No detectable pool of propionate was found, however, in either soybean nodules or in isolated bacteroids suggesting that propionate, if present, is utilized as rapidly as it is formed. Experiments in which cell-free extracts of nodule bacteroids were used demonstrated the conversion of lactate to propionate. The cofactor requirements for these enzymic reactions are adenosine 5-triphosphate, Mg++ and reduced nicotinamide adenine dinucleotide.

Jackson, Earl K.; Evans, Harold J.

1966-01-01

173

Clobetasol Propionate shampoo_21644  

Center for Biologics Evaluation and Research (CBER)

Text Version... Drugs. Active ingredient: Clobetasol Propionate Form/Route: Shampoo/Topical I. Waiver option: a. To qualify for a waiver ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

174

Pathway of propionate oxidation by a syntrophic culture of Smithella propionica and Methanospirillum hungatei.  

PubMed

The pathway of propionate conversion in a syntrophic coculture of Smithella propionica and Methanospirillum hungatei JF1 was investigated by (13)C-NMR spectroscopy. Cocultures produced acetate and butyrate from propionate. [3-(13)C]propionate was converted to [2-(13)C]acetate, with no [1-(13)C]acetate formed. Butyrate from [3-(13)C]propionate was labeled at the C2 and C4 positions in a ratio of about 1:1.5. Double-labeled propionate (2,3-(13)C) yielded not only double-labeled acetate but also single-labeled acetate at the C1 or C2 position. Most butyrate formed from [2,3-(13)C]propionate was also double labeled in either the C1 and C2 atoms or the C3 and C4 atoms in a ratio of about 1:1.5. Smaller amounts of single-labeled butyrate and other combinations were also produced. 1-(13)C-labeled propionate yielded both [1-(13)C]acetate and [2-(13)C]acetate. When (13)C-labeled bicarbonate was present, label was not incorporated into acetate, propionate, or butyrate. In each of the incubations described above, (13)C was never recovered in bicarbonate or methane. These results indicate that S. propionica does not degrade propionate via the methyl-malonyl-coenzyme A (CoA) pathway or any other of the known pathways, such as the acryloyl-CoA pathway or the reductive carboxylation pathway. Our results strongly suggest that propionate is dismutated to acetate and butyrate via a six-carbon intermediate. PMID:11282636

de Bok, F A; Stams, A J; Dijkema, C; Boone, D R

2001-04-01

175

Pathway of Propionate Oxidation by a Syntrophic Culture of Smithella propionica and Methanospirillum hungatei  

PubMed Central

The pathway of propionate conversion in a syntrophic coculture of Smithella propionica and Methanospirillum hungatei JF1 was investigated by 13C-NMR spectroscopy. Cocultures produced acetate and butyrate from propionate. [3-13C]propionate was converted to [2-13C]acetate, with no [1-13C]acetate formed. Butyrate from [3-13C]propionate was labeled at the C2 and C4 positions in a ratio of about 1:1.5. Double-labeled propionate (2,3-13C) yielded not only double-labeled acetate but also single-labeled acetate at the C1 or C2 position. Most butyrate formed from [2,3-13C]propionate was also double labeled in either the C1 and C2 atoms or the C3 and C4 atoms in a ratio of about 1:1.5. Smaller amounts of single-labeled butyrate and other combinations were also produced. 1-13C-labeled propionate yielded both [1-13C]acetate and [2-13C]acetate. When 13C-labeled bicarbonate was present, label was not incorporated into acetate, propionate, or butyrate. In each of the incubations described above, 13C was never recovered in bicarbonate or methane. These results indicate that S. propionica does not degrade propionate via the methyl-malonyl-coenzyme A (CoA) pathway or any other of the known pathways, such as the acryloyl-CoA pathway or the reductive carboxylation pathway. Our results strongly suggest that propionate is dismutated to acetate and butyrate via a six-carbon intermediate.

de Bok, F. A. M.; Stams, A. J. M.; Dijkema, C.; Boone, D. R.

2001-01-01

176

Assessing accumulation and biological effect of hydrophobic organic contaminants in water using caged Japanese medaka and deployed triolein-embedded cellulose acetate membranes.  

PubMed

Applicability of triolein-embedded cellulose acetate membrane (TECAM) to accumulation and potential biological effect assessment for hydrophobic organic contaminants (HOCs) was investigated compared with Japanese medaka. The results of field exposure showed that medaka and TECAMs accumulated contaminants in a similar pattern with good correlations between concentrations in medaka and TECAMs based on lipid weight for OCPs (r=0.96, p=0.01, n=9) and PAHs (r=0.73, p=0.01, n=13). Meanwhile, 2,3,7,8-TCDD equivalents (TEQs) of TECAM extracts detected by in vitro H4IIE cell bioassay corresponded well to hepatic EROD activities of exposed fish and TEQs of water samples. We concluded that TECAM could be utilized as a surrogate for biomonitoring organisms to assess the bioaccumulation of HOCs and potential biological effect. PMID:18958381

Luo, Jianping; Ma, Mei; Zha, Jinmiao; Wang, Zijian

2008-10-29

177

Cellulose fermentation  

SciTech Connect

The fermentation of cellulose by microorganisms is accelerated by the presence of a small amount of 2-(chloromethyldithio)acetic acid (I). Bacteroides succinogenes amounted to 43.6% in the presence of 1 ..mu..g I as compared with 38.6% in the case of controls.

Singer, M.S.

1978-08-29

178

A direct pathway for the conversion of propionate into pyruvate in Moraxella lwoffi  

PubMed Central

1. The identity of the organism previously known as Vibrio O1 (N.C.I.B. 8250) with a species of Moraxella is established. 2. The ability of cells to oxidize propionate is present only in cells with an endogenous respiration and this ability is increased 80-fold when the organism is grown with propionate. 3. Isocitrate lyase activity in extracts from propionate-grown cells is the same as that in extracts from lactate-grown cells, about tenfold greater than that in extracts from succinate-grown cells and slightly greater than half the activity in extracts from acetate-grown cells. 4. With arsenite as an inhibitor conditions were found in which the organism would catalyse the quantitative oxidation of propionate to pyruvate. When propionate was completely utilized pyruvate was metabolized further to 2-oxoglutarate. 5. The oxidation of propionate by cells was incomplete both in a `closed system' with alkali to trap respiratory carbon dioxide and in an `open system' with an atmosphere of oxygen+carbon dioxide (95:5). Acetate accumulated. Under these conditions [2-14C]- and [3-14C]-propionate gave rise to [14C]acetate. The rate of conversion of [2-14C]propionate into 14CO2, although much less than the rate of conversion of [1-14C]propionate into 14CO2, was slightly greater than the rate of conversion of [3-14C]propionate into 14CO2. 6. The oxidation of propionate by cells was complete in an `open system' with an atmosphere of either oxygen or air. Under these conditions very little [1-14C]propionate was converted into 14C-labelled cell material. The conversion of [2-14C]- and [3-14C]-propionate into 14C-labelled cell material occurred at an appreciable rate, the rate for the incorporation of [3-14C]propionate being slightly more rapid. In the absence of a utilizable nitrogen source part of the [14C]propionate was incorporated into some reserve material, which was oxidized when added substrate had been completely utilized. 7. [14C]-Pyruvate produced from [14C]propionate was chemically degraded. The C(1) of propionate was found only in C(1) of pyruvate. At least 86% of C(2) of pyruvate was derived from C(2) of propionate and at least 92% of C(3) of pyruvate from C(3) of propionate. 8. These results are incompatible with the operation of any of the previously described pathways for propionate metabolism except the direct one, perhaps via an activated acrylate. ImagesPLATE 2PLATE 1

Hodgson, B.; McGarry, J. D.

1968-01-01

179

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

180

Start-up and operation of a propionate-degrading fluidized-bed reactor  

Microsoft Academic Search

A laboratory-scale fluidized-bed reactor was inoculated with a syntrophically propionate-degrading co-culture. After 24 days of batch operation with propionate and acetate in the medium, the reactor was operated for 8 months with propionate as the sole substrate. The loading rate was 8.5 kg chemical oxygen demand\\/m3 ·day, yielding a maximal gas production of 4.5 l\\/l·day at a removal efficiency of

Birgit Heppner; Gerhard Zellner; Hans Diekmann

1992-01-01

181

Triolein embedded cellulose acetate membrane as a tool to evaluate sequestration of PAHs in lake sediment core at large temporal scale.  

PubMed

Although numerous studies have addressed sequestration of hydrophobic organic compounds (HOCs) in laboratory, little attention has been paid to its evaluation method in field at large temporal scale. A biomimetic tool, triolein embedded cellulose acetate membrane (TECAM), was therefore tested to evaluate sequestration of six PAHs with various hydrophobicity in a well-dated sediment core sampled from Nanyi Lake, China. Properties of sediment organic matter (OM) varying with aging time dominated the sequestration of PAHs in the sediment core. TECAM-sediment accumulation factors (MSAFs) of the PAHs declined with aging time, and significantly correlated with the corresponding biota-sediment accumulation factors (BSAFs) for gastropod (Bellamya aeruginosa) simultaneously incubated in the same sediment slices. Sequestration rates of the PAHs in the sediment core evaluated by TECAM were much lower than those obtained from laboratory study. The relationship between relative availability for TECAM (MSAF(t)/MSAF(0)) and aging time followed the first order exponential decay model. MSAF(t)/MSAF(0) was well-related to the minor changes of the properties of OM varying with aging time. Compared with chemical extraction, sequestration reflected by TECAM was much closer to that by B. aeruginosa. In contrast to B. aeruginosa, TECAM could avoid metabolism and the influences from feeding and other behaviors of organisms, and it is much easier to deploy and ready in laboratory. Hence TECAM provides an effective and convenient way to study sequestration of PAHs and probably other HOCs in field at large temporal scale. PMID:22372719

Tao, Yuqiang; Xue, Bin; Yao, Shuchun; Deng, Jiancai; Gui, Zhifan

2012-03-14

182

Plasticizer effect and comparative evaluation of cellulose acetate and ethylcellulose-HPMC combination coatings as semipermeable membranes for oral osmotic pumps of naproxen sodium.  

PubMed

The objective of this study was to compare the performance of cellulose acetate (CA) and ethylcellulose (EC)-HPMC combination coatings as semipermeable membranes (SPMs) for osmotic pump tablets (OPTs) of naproxen sodium (NPS) so as to deliver a constant, predetermined amount of drug in solution form over a fixed span of time, independent of external environmental conditions. Osmotic pump tablets were designed with different coating variables and optimized in terms of nature of plasticizer, membrane thickness, and orifice diameter. The effect of insertion of an inner microporous film around the NPS core to minimize deformation of the SPM due to peristaltic movement of the gut was also studied. Osmotic pump tablets composed of membranes with water-soluble plasticizer, propyleneglycol (PG), released drug mainly through diffusion, whereas those designed with CA and EC-HPMC (4:1) coats containing water-insoluble plasticizer, castor oil, released their contents by perfect zero-order kinetics over a prolonged period of time, though the average release rate that could be achieved with the EC-HPMC (4:1) membrane was only about half the rate achieved with the CA membrane for the same membrane thickness. Release rates for both the membranes decreased with increasing membrane thickness and were found to be independent of orifice diameter, agitation intensity, and pH of the dissolution medium. PMID:12056533

Ramakrishna, N; Mishra, B

2002-04-01

183

Microbiological quality and other characteristics of refrigerated chicken meat in contact with cellulose acetate-based film incorporated with rosemary essential oil  

PubMed Central

Antimicrobial active packaging delays or inhibits microorganism growth in packed products, and it can be used in a variety of food systems. The objective of the present research was to develop packaging incorporated with natural antimicrobial agents (active film). The effects of the active film on the spoilage, pathogenic microorganism counts, pH and color of the refrigerated chicken breast cuts were analyzed. Cellulose acetate-based active films incorporating two concentrations (20% and 50%, v/w) of rosemary (Rosmarinus officinalis L.) essential oil were manufactured and placed in contact with the chicken breast cuts for six days. An analysis of variance and mean comparison tests (Tukey’s test, p<0.05) were performed on the results. The films that contained 20% essential oil and were intercalated with chicken breast samples did not demonstrate significant effects on the control of psychrotrophic or total coliform microorganisms during the storage period; however, the films incorporated with 50% essential oil demonstrated efficacy toward the control of coliforms during the storage of the samples (6 days, 2 ± 2ºC). The pH was related to the psychrotrophic microorganism count and was not influenced by the treatment. The color was not influenced by the time of storage or the treatment. The results demonstrate that active films incorporating 50% rosemary essential oil are effective at controlling certain microorganisms in chicken breast cuts.

de Melo, Adriane Alexandre Machado; Geraldine, Robson Maia; Silveira, Miriam Fontes Araujo; Torres, Maria Celia Lopes; e Rezende, Cintia Silva Minafra; Fernandes, Thiago Henrique; de Oliveira, Antonio Nonato

2012-01-01

184

Microbiological quality and other characteristics of refrigerated chicken meat in contact with cellulose acetate-based film incorporated with rosemary essential oil.  

PubMed

Antimicrobial active packaging delays or inhibits microorganism growth in packed products, and it can be used in a variety of food systems. The objective of the present research was to develop packaging incorporated with natural antimicrobial agents (active film). The effects of the active film on the spoilage, pathogenic microorganism counts, pH and color of the refrigerated chicken breast cuts were analyzed. Cellulose acetate-based active films incorporating two concentrations (20% and 50%, v/w) of rosemary (Rosmarinus officinalis L.) essential oil were manufactured and placed in contact with the chicken breast cuts for six days. An analysis of variance and mean comparison tests (Tukey's test, p<0.05) were performed on the results. The films that contained 20% essential oil and were intercalated with chicken breast samples did not demonstrate significant effects on the control of psychrotrophic or total coliform microorganisms during the storage period; however, the films incorporated with 50% essential oil demonstrated efficacy toward the control of coliforms during the storage of the samples (6 days, 2 ± 2ºC). The pH was related to the psychrotrophic microorganism count and was not influenced by the treatment. The color was not influenced by the time of storage or the treatment. The results demonstrate that active films incorporating 50% rosemary essential oil are effective at controlling certain microorganisms in chicken breast cuts. PMID:24031972

de Melo, Adriane Alexandre Machado; Geraldine, Robson Maia; Silveira, Miriam Fontes Araujo; Torres, Maria Célia Lopes; E Rezende, Cíntia Silva Minafra; Fernandes, Thiago Henrique; de Oliveira, Antonio Nonato

2012-06-01

185

Preparation and application of functionalized cellulose acetate/silica composite nanofibrous membrane via electrospinning for Cr(VI) ion removal from aqueous solution.  

PubMed

Novel NH(2)-functionalized cellulose acetate (CA)/silica composite nanofibrous membranes were successfully prepared by sol-gel combined with electrospinning technology. Tetraethoxysilane (TEOS) as a silica source, CA as precursor and 3-ureidopropyltriethoxysilane as a coupling agent were used in membrane preparation. The membrane's chemical and morphological structures were investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD), element analyzer, Fourier-transform infrared spectroscopy (FTIR) and N(2) adsorption-desorption isotherms. The composite nanofibrous membranes exhibited high surface area and porosity. The membranes were used for Cr(VI) ion removal from aqueous solution through static and dynamic experiments. The adsorption behavior of Cr(VI) can be well described by the Langmuir adsorption model, and the maximum adsorption capacity for Cr(VI) is estimated to be 19.46 mg/g. The membrane can be conveniently regenerated by alkalization. Thus the composite membrane prepared from biodegradable raw material has potential applications in the field of water treatment. PMID:22858801

Taha, Ahmed A; Wu, Yi-na; Wang, Hongtao; Li, Fengting

2012-08-02

186

Anaerobic Degradation of Propionate by a Mesophilic Acetogenic Bacterium in Coculture and Triculture with Different Methanogens  

PubMed Central

A mesophilic acetogenic bacterium (MPOB) oxidized propionate to acetate and CO2 in cocultures with the formate- and hydrogen-utilizing methanogens Methanospirillum hungatei and Methanobacterium formicicum. Propionate oxidation did not occur in cocultures with two Methanobrevibacter strains, which grew only with hydrogen. Tricultures consisting of MPOB, one of the Methanobrevibacter strains, and organisms which are able to convert formate into H2 plus CO2 (Desulfovibrio strain G11 or the homoacetogenic bacterium EE121) also degraded propionate. The MPOB, in the absence of methanogens, was able to couple propionate conversion to fumarate reduction. This propionate conversion was inhibited by hydrogen and by formate. Formate and hydrogen blocked the energetically unfavorable succinate oxidation to fumarate involved in propionate catabolism. Low formate and hydrogen concentrations are required for the syntrophic degradation of propionate by MPOB. In triculture with Methanospirillum hungatei and the aceticlastic Methanothrix soehngenii, propionate was degraded faster than in biculture with Methanospirillum hungatei, indicating that low acetate concentrations are favorable for propionate oxidation as well.

Dong, Xiuzhu; Plugge, Caroline M.; Stams, Alfons J. M.

1994-01-01

187

Identification of a group of tetracarboxylate porphyrins, containing one acetate and three propionate ?-substituents, in faeces from patients with symptomatic cutaneous hepatic porphyria and from rats with porphyria due to hexachlorobenzene  

PubMed Central

1. Three tetracarboxylate porphyrins, apart from coproporphyrin, were isolated from the faeces of patients with symptomatic cutaneous hepatic porphyria and of rats with porphyria caused by hexachlorobenzene poisoning. The porphyrins were not present in the urine of the porphyric rats or in the faeces of control rats. 2. Two of the porphyrins were identified as tris-(2-carboxyethyl)-carboxymethyl ethyl trimethyl porphin (isocoproporphyrin) and tris-(2-carboxyethyl)-carboxymethyl trimethyl porphin (de-ethyliso-coproporphyrin). 3. The third porphyrin, previously reported to be an analogue of coproporphyrin in which one propionate group is replaced by an ?- or ?-hydroxypropionate group, was shown to be tris-(2-carboxyethyl)-carboxymethyl-(1-hydroxyethyl)-trimethyl porphin (hydroxyisocoproporphyrin). 4. The order of ?-substituents around the porphin ring could not be determined for any of the compounds. 5. Evidence for the existence of a fourth porphyrin, tris-(2-carboxyethyl)-carboxymethyl trimethyl vinyl porphin (dehydroisocoproporphyrin), a postulated precursor of the others, is described. 6. It is suggested that dehydroisocoproporphyrinogen is produced by decarboxylation–dehydrogenation of one of the propionate groups of pentacarboxylate porphyrinogen III.

Elder, G. H.

1972-01-01

188

Anti-HIV-1 activity of cellulose acetate phthalate: Synergy with soluble CD4 and induction of "dead-end" gp41 six-helix bundles  

PubMed Central

Background Cellulose acetate phthalate (CAP), a promising candidate microbicide for prevention of sexual transmission of the human immunodeficiency virus type 1 (HIV-1) and other sexually transmitted disease (STD) pathogens, was shown to inactivate HIV-1 and to block the coreceptor binding site on the virus envelope glycoprotein gp120. It did not interfere with virus binding to CD4. Since CD4 is the primary cellular receptor for HIV-1, it was of interest to study CAP binding to HIV-1 complexes with soluble CD4 (sCD4) and its consequences, including changes in the conformation of the envelope glycoprotein gp41 within virus particles. Methods Enzyme-linked immunosorbent assays (ELISA) were used to study CAP binding to HIV-1-sCD4 complexes and to detect gp41 six-helix bundles accessible on virus particles using antibodies specific for the ?-helical core domain of gp41. Results 1) Pretreatment of HIV-1 with sCD4 augments subsequent binding of CAP; 2) there is synergism between CAP and sCD4 for inhibition of HIV-1 infection; 3) treatment of HIV-1 with CAP induced the formation of gp41 six-helix bundles. Conclusions CAP and sCD4 bind to distinct sites on HIV-1 IIIB and BaL virions and their simultaneous binding has profound effects on virus structure and infectivity. The formation of gp41 six-helical bundles, induced by CAP, is known to render the virus incompetent for fusion with target cells thus preventing infection.

Neurath, A Robert; Strick, Nathan; Jiang, Shibo; Li, Yun-Yao; Debnath, Asim K

2002-01-01

189

Novel, reagentless, amperometric biosensor for uric acid based on a chemically modified screen-printed carbon electrode coated with cellulose acetate and uricase.  

PubMed

Amperometry in stirred solution has been used for the systematic evaluation of modified screen-printed carbon electrodes (SPCEs) with a view to developing a reagentless biosensor for uric acid. The developed system consists of a base cobalt phthalocyanine (CoPC) electrode tailored to the electrocatalytic oxidation of H2O2 by means of a cellulose acetate (CA)-uricase bilayer. Uricase was immobilized by drop-coating the enzyme onto the CA membrane covering the CoPC-SPCE. The device exploits the near-universal H2O2-generating propensity of oxidases, the permselectivity of the CA film towards H2O2 and the electrocatalytic oxidation of this product at the CoPC-SPCE. The electrochemical oxidation of the resulting Co+ species was used as the analytical signal, facilitating the application of a greatly reduced operating potential when compared with that required for direct oxidation of H2O2 at unmodified electrodes. The time required to achieve 95% of the steady-state current (t95i(ss)) was 44 s [relative standard deviation = 7.5% (n = 10)]. Amperometric calibrations were linear over the range from 13 x 10(-6) to 1 x 10(-3) mol dm-3, with the former representing the limit of detection. The CA membrane extended the linear range of the biosensor by over two orders of magnitude, when apparent Michaelis-Menten constants (Km') of immobilized and free enzymes are compared. This suggests that the process is diffusion-controlled and not governed by the kinetics of the enzyme. The precision of electrode fabrication was determined by cyclic voltammetry to be 4.9% (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8067535

Gilmartin, M A; Hart, J P

1994-05-01

190

Bioinspired crystallization of CaCO3 coatings on electrospun cellulose acetate fiber scaffolds and corresponding CaCO3 microtube networks.  

PubMed

This article describes the mineralization behavior of CaCO(3) crystals on electrospun cellulose acetate (CA) fibers by using poly(acrylic acid) (PAA) as a crystal growth modifier and further templating synthesis of CaCO(3) microtubes. Calcite film coatings composed of nanoneedles can form on the surfaces of CA fibers while maintaining the fibrous and macroporous structures if the concentration of PAA is in a suitable range. In the presence of a suitable concentration of PAA, the acidic PAA molecules will first adsorb onto the surface of CA fibers by the interaction between the OH moieties of CA and the carboxylic groups of PAA, and then the redundant carboxylic groups of PAA can ionically bind Ca(2+) ions on the surfaces of CA fibers, resulting in the local supersaturation of Ca(2+) ions on and near the fiber surface, which can induce the nucleation of CaCO(3) on the CA fibers instead of in bulk solution. Calcite microtube networks on the macroscale can be prepared by the removal of CA fibers after the CA@CaCO(3) composite is treated with acetone. When the CA fiber scaffold is immersed in CaCl(2) solution with an extended incubation time, the first deposited calcite coatings can act as secondary substrate, leading to the formation of smaller calcite mesocrystal fibers. The present work proves that inorganic crystal growth can occur even at an organic interface without the need for commensurability between the lattices of the organic and inorganic counterparts. PMID:21534560

Liu, Lei; He, Dian; Wang, Guang-Sheng; Yu, Shu-Hong

2011-05-02

191

Selenomonas acidaminovorans sp. nov., a versatile thermophilic proton-reducing anaerobe able to grow by decarboxylation of succinate to propionate  

Microsoft Academic Search

A moderately thermophilic anaerobic bacterium (strain Su883), which decarboxylated succinate to propionate, was isolated from granular methanogenic sludge. The bacterium appeared to ferment a number of amino acids including glutamate, histidine, arginine, ornithine, citrulline, and threonine to propionate, acetate and hydrogen. Propionate was formed via the oxidative decarboxylation of a-ketoglutarate to succinyl-CoA. In addition, the strain degraded glucose, fructose, glycerol,

Cheng Guangsheng; Caroline M. Plugge; Wim Roelofsen; Frans P. Houwen; Alfons J. M. Stams

1992-01-01

192

Engineering Propionibacterium acidipropionici for enhanced propionic acid tolerance and fermentation.  

PubMed

Propionibacterium acidipropionici, a Gram-positive, anaerobic bacterium, has been the most used species for propionic acid production from sugars. In this study, the metabolically engineered mutant ACK-Tet, which has its acetate kinase gene knocked out from the chromosome, was immobilized and adapted in a fibrous bed bioreactor (FBB) to increase its acid tolerance and ability to produce propionic acid at a high final concentration in fed-batch fermentation. After about 3 months adaptation in the FBB, the propionic acid concentration in the fermentation broth reached approximately 100 g/L, which was much higher than the highest concentration of approximately 71 g/L previously attained with the wild-type in the FBB. To understand the mechanism and factors contributing to the enhanced acid tolerance, adapted mutant cells were harvested from the FBB and characterized for their morphology, growth inhibition by propionic acid, protein expression profiles as observed in SDS-PAGE, and H+-ATPase activity, which is related to the proton pumping and cell's ability to control its intracellular pH gradient. The adapted mutant obtained from the FBB showed significantly reduced growth sensitivity to propionic acid inhibition, increased H+-ATPase expression and activity, and significantly elongated rod morphology. PMID:19530125

Zhang, An; Yang, Shang-Tian

2009-11-01

193

Propionate inactivation of butane monooxygenase activity in 'Pseudomonas butanovora': biochemical and physiological implications.  

PubMed

Butane monooxygenase (BMO) catalyses the oxidation of alkanes to alcohols in the alkane-utilizing bacterium 'Pseudomonas butanovora'. Incubation of alkane-grown 'P. butanovora' with butyrate or propionate led to irreversible time- and O2-dependent loss of BMO activity. In contrast, BMO activity was unaffected by incubation with lactate or acetate. Chloramphenicol inhibited the synthesis of new BMO, but did not change the kinetics of propionate-dependent BMO inactivation, suggesting that the propionate effect was not simply due to it acting as a repressor of BMO transcription. BMO was protected from propionate-dependent inactivation by the presence of its natural substrate, butane. Although both the time and O2 dependency of propionate inactivation of BMO imply that propionate might be a suicide substrate, no evidence was obtained for BMO-dependent propionate consumption, or 14C labelling of BMO polypeptides by [2-(14)C]propionate during inactivation. Propionate-dependent BMO inactivation was also explored in mutant strains of 'P. butanovora' containing single amino acid substitutions in the alpha-subunit of the BMO hydroxylase. Propionate-dependent BMO inactivation in two mutant strains with amino acid substitutions close to the catalytic site differed from wild-type (one was more sensitive and the other less), providing further evidence that propionate-dependent inactivation involves interaction with the BMO catalytic site. A putative model is presented that might explain propionate-dependent inactivation of BMO when framed within the context of the catalytic cycle of the closely related enzyme, soluble methane monooxygenase. PMID:17975080

Doughty, D M; Halsey, K H; Vieville, C J; Sayavedra-Soto, L A; Arp, D J; Bottomley, P J

2007-11-01

194

CONVERSION OF LACTATE-C14 TO PROPIONATE BY THE RUMEN MICROFLORA12  

PubMed Central

Baldwin, R. L. (Michigan State University, East Lansing), W. A. Wood, and R. S. Emery. Conversion of lactate-C14 to propionate by the rumen microflora. J. Bacteriol. 83:907–913. 1962.—Rumen microflora enriched on five different diets calculated to present increasing carbohydrate or lactate availability were used to determine the contribution of the randomizing (succinate) and nonrandomizing (acrylate) routes to propionate with lactate-2-C14 and -3-C14 as substrates. Propionate was labeled as though 70 to 90% was formed via the nonrandomizing route. This percentage was highest on diets containing high levels of carbohydrate or lactate or both. Evidence for the presence of succinic dehydrogenase, acetokinase, phosphotransacetylase, and coenzyme A transphorase was obtained with cell-free extracts. Propionate-2-C14 and lactate-2-C14 were converted by extracts to the activated derivatives of acrylate, lactate, propionate, and acetate.

Baldwin, R. L.; Wood, W. A.; Emery, R. S.

1962-01-01

195

Interspecies distances between propionic acid degraders and methanogens in syntrophic consortia for optimal hydrogen transfer.  

PubMed

A mixed culture from an anaerobic biowaste digester was enriched on propionate and used to investigate interspecies hydrogen transfer in dependence of spatial distances between propionate degraders and methanogens. From 20.3 mM propionate, 20.8 mM acetate and 15.5 mM methane were formed. Maximum specific propionate oxidation and methane formation rates were 49 and 23 mmol?mg(-1)?day(-1), respectively. Propionate oxidation was inhibited by only 20 mM acetate by about 50 %. Intermediate formate formation during inhibited methanogensis was observed. The spatial distribution and the biovolume fraction of propionate degraders and of methanogens in relation to the total population during aggregate formation were determined. Measurements of interbacterial distances were conducted with fluorescence in situ hybridization by application of group-specific 16S rRNA-targeted probes and 3D image analyses. With increasing incubation time, floc formation and growth up to 54 ?m were observed. Propionate degraders and methanogens were distributed randomly in the flocs. The methanogenic biovolume fraction was high at the beginning and remained constant over 42 days, whereas the fraction of propionate degraders increased with time during propionate feeding. Interbacterial distances between propionate degraders and methanogens decreased with time from 5.30 to 0.29 ?m, causing an increase of the maximum possible hydrogen flux from 1.1 to 10.3 nmol?ml(-1)?min(-1). The maximum possible hydrogen flux was always higher than the hydrogen formation and consumption rate, indicating that reducing the interspecies distance by aggregation is advantageous in complex ecosystems. PMID:23233207

Felchner-Zwirello, Monika; Winter, Josef; Gallert, Claudia

2012-12-12

196

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

197

Effects of pH, temperature, and nutrients on propionate degradation by a methanogenic enrichment culture  

Microsoft Academic Search

Enrichment cultures were used to determine the conditions promoting fastest methanogenic propionate degradation and growth by adapting the cultures to various physical and chemical conditions and measuring the specific growth rate. They found that the fastest growth of propionate oxidizers occurred at pH 6.8 to 8.5 and 32 to 45°C. Acetate-degrading populations showed narrower optima for fastest growth (pH 6.8

DAVIDR. BOONE; L. Xun

1987-01-01

198

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

199

21 CFR 556.710 - Testosterone propionate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Testosterone propionate. 556.710 Section 556...Residues of New Animal Drugs § 556.710 Testosterone propionate. No residues of testosterone, resulting from the use of...

2009-04-01

200

Electrical conductance of some cellulose derivatives  

Microsoft Academic Search

The interrelation between the electrical conductance, s and some chemically modified cellulose molecule produced through partial substitution of the hydroxyl groups by different groups namely, acetate, methoxyl, carboxymethyl and sodium carboxymethyl has been studied in the temperature ranges 283–333 k. The results show that s of the examined samples change in the descending order: sodium carboxymethyl cellulose >carboxymethyl cellulose >methyl

Mohamed M. Abdel Moteleb

1992-01-01

201

Propionic acid production by cofermentation of Lactobacillus buchneri and Lactobacillus diolivorans in sourdough.  

PubMed

Cooperative metabolism of lactobacilli in silage fermentation converts lactate to propionate. This study aimed to determine whether propionate production by Lactobacillus buchneri and Lactobacillus diolivorans can be applied for bread preservation. Propionate formation was observed in cofermentation with L. buchneri and L. diolivorans in modified MRS broth as well as sourdough with low, medium and high ash contents. 48 mM of propionate was formed in sourdough with medium ash content, but only 9 and 28 mM propionate were formed in sourdoughs prepared from white wheat flour or whole wheat flour, respectively. Acetate levels were comparable in all three sourdoughs and ranged from 160 to 175 mM. Sourdough fermented with L. buchneri and L. diolivorans was used in breadmaking and its effect on fungal spoilage was compared to traditional sourdough or propionate addition to straight doughs. Bread slices were inoculated with Aspergillus clavatus, Cladosporium spp., Mortierella spp. or Penicillium roquefortii. The use of 20% experimental sourdough inhibited growth of three of the four moulds for more than 12 days. The use of 10% experimental sourdough deferred growth of two moulds by one day. Bread from traditional sourdough with added acetate had less effect in inhibiting mould growth. In conclusion, cofermentation with L. buchneri and L. diolivorans represents a process to increase antifungal capacities of bread. PMID:20227604

Zhang, Chonggang; Brandt, Markus J; Schwab, Clarissa; Gänzle, Michael G

2009-12-03

202

Bioavailability of Clobetasol Propionate in Different Vehicles  

Microsoft Academic Search

Topical clobetasol propionate is widely used for the treatment of psoriasis. One formulation of clobetasol propionate, Skin Cap, was thought by some practitioners and patients to be more effective than other formulations. Differences in corticosteroid bioavailability could account for differences in efficacy. The purpose of this study is to compare the relative bioavailability of clobetasol propionate from Skin Cap to

T. J. Franz; P. A. Lehman; S. R. Feldman; M. C. Spellman

2003-01-01

203

21 CFR 184.1221 - Calcium propionate.  

Code of Federal Regulations, 2013 CFR

... 3 2013-04-01 2013-04-01 false Calcium propionate. 184.1221 Section 184.1221...Specific Substances Affirmed as GRAS § 184.1221 Calcium propionate. (a) Calcium propionate (C6 H10 CaO4 , CAS Reg....

2013-04-01

204

Synthesis and characterization of cellulose acetate-polysulfone blend microfiltration membrane for separation of microbial cells from lactic acid fermentation broth  

Microsoft Academic Search

This work is focused on synthesis and characterization of a polymer blend microfiltration membrane for separation of microbial cells from lactic acid fermentation broth in a continuous process. The membranes were prepared by blending hydrophilic cellulose diacetate (CA) polymer with hydrophobic polysulfone (PSF) polymer in wet phase inversion method. Polymers were blended in N-methyl-2-pyrrolidone (NMP) solvent (70wt.%) where polyethylene glycol

J. Sikder; C. Pereira; S. Palchoudhury; K. Vohra; D. Basumatary; P. Pal

2009-01-01

205

Use of 2-hydroxypropyl-?-cyclodextrin as adjuvant for enhancing encapsulation and release characteristics of asiaticoside within and from cellulose acetate films  

Microsoft Academic Search

The inclusion complex between asiaticoside (AC), an active substance from the medicinal plant Centella asiatica L., and 2-hydroxypropyl-?-cyclodextrin (HP?CD) was investigated. The phase solubility profiles of AC in distilled water and 90:10 (v\\/v) mixture of 80vol.% acetic acid and N,N-dimethylacetamide (DMAc) both in the absence and the presence of HP?CD were classified as AL-type and indicated a 1:1 molar ratio

Jate Panichpakdee; Pitt Supaphol

2011-01-01

206

Divergent Metabolic Pathways for Propane and Propionate Utilization by a Soil Isolate1  

PubMed Central

The metabolism of propane and propionate by a soil isolate (Brevibacterium sp. strain JOB5) was investigated. The presence of isocitrate lyase in cells grown on isopropanol, acetate, or propane and the absence of this inducible enzyme in n-propanol- and propionate-grown cells suggested that propane is not metabolized via C-terminal oxidation. Methylmalonyl coenzyme A mutase and malate synthase are constitutive in this organism. The incorporation of 14CO2 into pyruvate accumulated during propionate utilization suggests that propionate is metabolized via the methyl-malonyl-succinate pathway. These results were further substantiated by radiorespirometric studies with propionate-1-14C, -2-14C, and -3-14C as substrate. Propane -2-14C was shown, by unlabeled competitor experiments, to be oxidized to acetone; acetone and isopropanol are oxidized in this organism to acetol. Cleavage of acetol to acetate and CO2 would yield the inducer for the isocitrate lyase present in propane-grown cells.

Vestal, J. R.; Perry, Jerome J.

1969-01-01

207

Stability and solubility enhancement of ellagic acid in cellulose ester solid dispersions.  

PubMed

Structurally varied, carboxyl-containing cellulose derivatives were evaluated for their ability to form amorphous solid dispersions (ASD) with ellagic acid (EA), in order to improve the solubility of this high-melting, poorly bioavailable, but highly bioactive natural flavonoid compound. ASDs of EA with carboxymethylcellulose acetate butyrate (CMCAB), cellulose acetate adipate propionate (CAAdP), and hydroxypropylmethylcellulose acetate succinate (HPMCAS) were prepared, and EA dissolution from these ASDs was compared with that from pure crystalline EA and from EA/poly(vinylpyrrolidinone) (PVP) solid dispersions (SD). Polymer/drug mixtures were characterized by powder X-ray diffraction (XRPD), modulated differential scanning calorimetry (MDSC), nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR). The XRPD and FT-IR results indicated that EA was amorphous in solid dispersions with EA concentration up to 25 wt%. The stability against crystallization and solution concentrations of EA from these solid dispersions were significantly higher than those observed for physical mixtures and pure crystalline EA. HPMCAS stabilized EA most effectively, among the polymers tested, against both chemical degradation and recrystallization. The relative ability to solubilize EA from ASDs at pH 6.8 was PVP>HPMCAS>CMCAB. EA dissolves from ASD in PVP quickly and completely (maximum 92%) at pH 6.8, but EA is also released from PVP at pH 1.2, and then crystallizes rapidly. Therefore PVP is not a practical candidate for EA ASD. In contrast, the cellulose derivative ASDs show very slow EA release at pH 1.2 (<4%) and faster but still incomplete drug release at pH 6.8 (maximum 35% for HPMCAS SD). The pH-triggered drug release from HPMCAS ASD makes HPMCAS a practical choice for EA solubility enhancement. PMID:23399175

Li, Bin; Harich, Kim; Wegiel, Lindsay; Taylor, Lynne S; Edgar, Kevin J

2012-10-29

208

21 CFR 522.842 - Estradiol benzoate and testosterone propionate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Estradiol benzoate and testosterone propionate. 522.842 Section...522.842 Estradiol benzoate and testosterone propionate. (a) Sponsors ...mg) estradiol benzoate and 200 mg testosterone propionate (one implant...

2009-04-01

209

Ultra-trace determination of lead(II) in water using electrothermal atomic absorption spectrometry after preconcentration by solid-phase extraction to a small piece of cellulose acetate type membrane filter.  

PubMed

A simple and inexpensive preconcentration technique has been developed for the ultra-trace determination of lead(II) using electrothermal atomic absorption spectrometry (ETAAS). The lead(II) complex with dicyclohexano-18-crown 6-ether (DC18C6) was extracted to a small piece of cellulose acetate-type membrane filter (2 × 5 mm) merely by vigorously eccentric stirring for 120 min under the coexistence of sodium dodecyl sulfate (SDS) at around pH 7. The extraction medium was inserted into a graphite cuvette for the determination of lead(II) by ETAAS. A linear relation was obtained for the range of 0.1-5.0 ng in 10 ml of lead(II) standard solution (r = 0.998). The detection limit was found to be 0.03 ng of lead(II) in 10 ml (0.003 µg l(-1)) of water sample. The proposed method was applied to the ultra-trace determination of lead(II) in river water, underground water, tap water, and snow fall samples. PMID:21233566

Mizuguchi, Hitoshi; Ishida, Mirai; Takahashi, Tomohiro; Sasaki, Atsushi; Shida, Junichi

2011-01-01

210

Characterization of the anaerobic propionate-degrading syntrophs Smithella propionica gen. nov., sp. nov. and Syntrophobacter wolinii.  

PubMed

A strain of anaerobic, syntrophic, propionate-oxidizing bacteria, strain LYPT (= OCM 661T; T = type strain), was isolated and proposed as representative of a new genus and new species, Smithella propionica gen. nov., sp. nov. The strain was enriched from an anaerobic digestor and isolated. Initial isolation was as a monoxenic propionate-degrading co-culture containing Methanospirillum hungateii JF-1T as an H2- and formate-using partner. Later, an axenic culture was obtained by using crotonate as the catabolic substrate. The previously described propionate-degrading syntrophs of the genus Syntrophobacter also grow in co-culture with methanogens such as Methanospirillum hungateii, forming acetate, CO2 and methane from propionate. However, Smithella propionica differs by producing less methane and more acetate; in addition, it forms small amounts of butyrate. Smithella propionica and Syntrophobacter wolinii grew within similar ranges of pH, temperature and salinity, but they differed significantly in substrate ranges and catabolic products. Unlike Syntrophobacter wolinii, Smithella propionica grew axenically on crotonate, although very slowly. Co-cultures of Smithella propionica grew on propionate, and grew slowly on crotonate or butyrate. Syntrophobacter wolinii and Syntrophobacter pfennigii grow on propionate plus sulfate, whereas Smithella propionica did not. Comparisons of 16S rDNA genes indicated that Smithella propionica is most closely related to Syntrophus, and is more distantly related to Syntrophobacter. PMID:10319475

Liu, Y; Balkwill, D L; Aldrich, H C; Drake, G R; Boone, D R

1999-04-01

211

Assembly of synthetic cellulose I.  

PubMed

Cellulose microfibrils with an electron diffraction pattern characteristic of crystalline native cellulose I have been assembled abiotically by means of a cellulase-catalyzed polymerization of beta-cellobiosyl fluoride substrate monomer in acetonitrile/acetate buffer. Substantial purification of the Trichoderma viride cellulase enzyme was found to be essential for the formation of the synthetic cellulose I allomorph. Assembly of synthetic cellulose I appears to be a result of a micellar aggregation of the partially purified enzyme and the substrate in an organic/aqueous solvent system favoring the alignment of glucan chains with the same polarity and extended chain conformation, resulting in crystallization to form the metastable cellulose I allomorph. PMID:7519776

Lee, J H; Brown, R M; Kuga, S; Shoda, S; Kobayashi, S

1994-08-01

212

Hypophagic effects of propionate increase with elevated hepatic acetyl coenzyme A concentration for cows in the early postpartum period.  

PubMed

Thirty multiparous lactating dairy cows were used in a randomized block design experiment to evaluate factors related to the degree of hypophagia from intraruminal infusion of propionate. Cows between 3 and 40 d postpartum at the start of the experiment were blocked by calving date and randomly assigned to treatment. Treatments were 1.0 mol/L propionic acid or 1.0 mol/L acetic acid adjusted to pH 6 with sodium hydroxide and infused at 0.5 mol of volatile fatty acid/h from 6h before feeding until 12h after feeding. Propionate infusion decreased dry matter intake by 20.0%, total metabolizable energy intake by 22.5%, and plasma ?-hydroxybutyrate concentration by 54.3% compared with acetate infusion. Effects of treatment on dry matter intake were related to concentration of acetyl coenzyme A (CoA) in the liver; hypophagic effects of propionate compared with acetate increased as liver acetyl CoA concentration increased. Hypophagic effects of propionate are greater for cows with elevated concentrations of acetyl CoA in the liver. PMID:22612960

Stocks, S E; Allen, M S

2012-06-01

213

Fermentation characteristics of Fusariumoxysporum grown on acetate.  

PubMed

In this study, the growth characteristics of Fusariumoxysporum were evaluated in minimal medium using acetate or different mixtures of acetate and glucose as carbon source. The minimum inhibitory concentration (MIC) of acetic acid that F.oxysporum cells could tolerate was 0.8%w/v while glucose was consumed preferentially to acetate. The activity of isocitrate lyase was high when cells were grown on acetate and acetate plus glucose indicating an activation of the glyoxylate cycle. Investigation of the metabolic fingerprinting and footprinting revealed higher levels of intracellular and extracellular TCA cycle intermediates when F.oxysporum cells were grown on mixtures of acetate and glucose compared to growth on only glucose. Our data support the hypothesis that a higher flux through TCA cycle during acetate consumption could significantly increase the pool of NADH, resulting in the activation of succinate-propionate pathway which consumes reducing power (NADH) via conversion of succinate to propionyl-CoA and produce propionate. PMID:18304808

Panagiotou, Gianni; Pachidou, Fotini; Petroutsos, Dimitris; Olsson, Lisbeth; Christakopoulos, Paul

2008-03-04

214

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids II. Incomplete oxidation of propionate by Desulfobulbus propionicus gen. nov., sp. nov  

Microsoft Academic Search

A new type of sulfate-reducing bacteria with ellipsoidal to lemon-shaped cells was regularly enriched from anaerobic freshwater and marine mud samples when mineral media with propionate and sulfate were used. Three strains (1pr3, 2pr4, 3pr10) were isolated in pure culture. Propionate, lactate and alcohols were used as electron donors and carbon sources. Growth on H2 required acetate as a carbon

Friedrich Widdel; Norbert Pfennig

1982-01-01

215

The first true obligately syntrophic propionate-oxidizing bacterium, Pelotomaculum schinkii sp.nov., co-cultured with Methanospirillum hungatei, and emended description of the genus Pelotomaculum  

Microsoft Academic Search

A Gram-positive, spore-forming, syntrophic propionate-oxidizing bacterium, Pelotomaculum schinkii sp. nov. strain HHT, was isolated as a co-culture with Methanospirillum hungatei JF-1T from anaerobic, freeze-dried granular sludge obtained from an upflow anaerobic sludge bed reactor treating sugar beet wastewater. The bacterium converted propionate to acetate in co-culture with Methanospirillum hungatei JF-1T or Methanobacterium formicicum MFNT, but not in co-culture with Methanobrevibacter

Bok de F. A. M; Hermie J. M. Harmsen; Caroline M. Plugge; Vries de M. C; Antoon D. L. Akkermans; Vos de W. M; Alfons J. M. Stams

2005-01-01

216

The study of factors affecting the enzymatic hydrolysis of cellulose after ionic liquid pretreatment  

Microsoft Academic Search

Cellulose resource has got much attention as a promising replacement of fossil fuel. The hydrolysis of cellulose is the key step to chemical product and liquid transportation fuel. In this paper a serials of chloride, acetate, and formate based ionic liquids were used as solvents to dissolve cellulose. The cellulose regenerated from ILs was characterized by FTIR and X-ray powder

Wenwen Xiao; Wang Yin; Shuqian Xia; Peisheng Ma

217

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

218

Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks  

SciTech Connect

Progress in studies on the production of reducing sugars and other products by Clostridium thermocellum on cellulosic biomass is reported. The rate of reducing sugar production using corn residue was found to be equal if not greater than on solka floc. Current work is being devoted towards elucidating discrepancies between reducing sugar analysis and high pressure liquid chromatography sugar analysis in order to permit accurate material balances to be completed. Studies are reported in further characterizing the plasmics of C. thermocellum and in the development of protoplasts of the same microorganism. A process and economic analysis for the production of 200 x 10/sup 6/ pounds (90 x 10/sup 6/ kilograms) per year of soluble reducing sugars from corn stover cellulose, using enzymes derived from Clostridium thermocellum was designed. Acrylic acid was produced in resting cell preparation of Clostridium propionicum from both ..beta..-alanine and from propionic acid. Results from the conversion of corn stover hydrolyzates to lactic acid, a precursor to acrylic acid, show that up to 70% of the sugars produced are converted to lactic acid. Efforts are proceeding to improve the conversion yield and carry out the overall conversion of corn stover to acrylic acid in the same fermentor. Results on the production of acetone and butanol by Clostridium acetobutylicum demonstrated the capability of the strain to produce mixed solvents in concentration and conversion similar to that achieved in industrial processes. Various studies on the production of acetic acid by Clostridium thermoaceticum are also reported.

Wang, D.I.C.; Cooney, C.L.; Demain, A.L.; Gomez, R.F.; Sinskey, A.J.

1977-11-01

219

Cellulosic biofuels.  

PubMed

The development of sustainable, low-carbon, liquid fuels from cellulosic biomass will require advances in many areas of science and engineering. This review describes the major topics of enquiry concerning cellulosic biofuels with an emphasis on those areas of research and development that include research problems of interest to plant biologists. PMID:19014348

Carroll, Andrew; Somerville, Chris

2009-01-01

220

Cellulose Shapes  

Microsoft Academic Search

This chapter surveys the shapes of cellulose molecules. New, high-resolution experiments on the various crystalline polymorphs are reviewed, and their similar twofold helical shapes are compared. Conversion between cellulose I and II is discussed, including interdigitation and chain-folding as possible mechanisms. Information on molecular shape from cellotriose and tetraose is also reviewed along with data for derivatives and complexes. To

Alfred D. French; Glenn P. Johnson

221

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

2012-09-12

222

Stable-isotope probing of microorganisms thriving at thermodynamic limits: syntrophic propionate oxidation in flooded soil.  

PubMed

Propionate is an important intermediate of the degradation of organic matter in many anoxic environments. In methanogenic environments, due to thermodynamic constraints, the oxidation of propionate requires syntrophic cooperation of propionate-fermenting proton-reducing bacteria and H(2)-consuming methanogens. We have identified here microorganisms that were active in syntrophic propionate oxidation in anoxic paddy soil by rRNA-based stable-isotope probing (SIP). After 7 weeks of incubation with [(13)C]propionate (<10 mM) and the oxidation of approximately 30 micromol of (13)C-labeled substrate per g dry weight of soil, we found that archaeal nucleic acids were (13)C labeled to a larger extent than those of the bacterial partners. Nevertheless, both terminal restriction fragment length polymorphism and cloning analyses revealed Syntrophobacter spp., Smithella spp., and the novel Pelotomaculum spp. to predominate in "heavy" (13)C-labeled bacterial rRNA, clearly showing that these were active in situ in syntrophic propionate oxidation. Among the Archaea, mostly Methanobacterium and Methanosarcina spp. and also members of the yet-uncultured "rice cluster I" lineage had incorporated substantial amounts of (13)C label, suggesting that these methanogens were directly involved in syntrophic associations and/or thriving on the [(13)C]acetate released by the syntrophs. With this first application of SIP in an anoxic soil environment, we were able to clearly demonstrate that even guilds of microorganisms growing under thermodynamic constraints, as well as phylogenetically diverse syntrophic associations, can be identified by using SIP. This approach holds great promise for determining the structure and function relationships of further syntrophic or other nutritional associations in natural environments and for defining metabolic functions of yet-uncultivated microorganisms. PMID:15466514

Lueders, Tillmann; Pommerenke, Bianca; Friedrich, Michael W

2004-10-01

223

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

PubMed Central

Propionate is an important intermediate of the degradation of organic matter in many anoxic environments. In methanogenic environments, due to thermodynamic constraints, the oxidation of propionate requires syntrophic cooperation of propionate-fermenting proton-reducing bacteria and H2-consuming methanogens. We have identified here microorganisms that were active in syntrophic propionate oxidation in anoxic paddy 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 Syntrophobacter spp., Smithella spp., and the novel Pelotomaculum spp. to predominate in “heavy” 13C-labeled bacterial rRNA, clearly showing that these were active in situ in syntrophic propionate oxidation. Among the Archaea, mostly Methanobacterium and Methanosarcina spp. and also members of the yet-uncultured “rice cluster I” lineage had incorporated substantial amounts of 13C label, suggesting that these methanogens were directly involved in syntrophic associations and/or thriving on the [13C]acetate released by the syntrophs. With this first application of SIP in an anoxic soil environment, we were able to clearly demonstrate that even guilds of microorganisms growing under thermodynamic constraints, as well as phylogenetically diverse syntrophic associations, can be identified by using SIP. This approach holds great promise for determining the structure and function relationships of further syntrophic or other nutritional associations in natural environments and for defining metabolic functions of yet-uncultivated microorganisms.

Lueders, Tillmann; Pommerenke, Bianca; Friedrich, Michael W.

2004-01-01

224

Syntrophobacter sulfatireducens sp. nov., a novel syntrophic, propionate-oxidizing bacterium isolated from UASB reactors.  

PubMed

Two obligate anaerobes, TB8106(T) and WZH410, which degraded propionate in syntrophic association with methanogens, were isolated from two upflow anaerobic sludge blanket reactors, one treating brewery wastewater and the other bean curd wastewater. The strains were Gram-negative, non-spore-forming and non-motile. Cells were egg-shaped, with a size of 1.0-1.3 x 1.8-2.2 microm. Growth was observed at 20-48 degrees C and pH 6.2-8.8. Both strains converted propionate to acetate and methane in co-culture with methanogens, and grew on propionate plus sulfate in pure culture, with a doubling time of 52-55 h at 37 degrees C. Sulfate and thiosulfate both served as electron acceptors for propionate degradation. The DNA G + C contents of the two strains were 58.5 and 58.7 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strains were closely related to a propionate-oxidizing syntrophic bacterium, Syntrophobacter fumaroxidans DSM 10017(T) (94.7 % similarity). However, the novel strains could not ferment fumarate, and grew at a more alkaline pH range than Syntrophobacter fumaroxidans. Moreover, the novel isolates had obviously higher growth rates on propionate plus sulfate (0.12 day(-1)) than Syntrophobacter fumaroxidans DSM 10017(T) (0.024 day(-1)). Therefore, a novel species, Syntrophobacter sulfatireducens sp. nov., is proposed, with strain TB8106(T) (=AS 1.5016(T) = DSM 16706(T)) as the type strain. PMID:15879275

Chen, Shuangya; Liu, Xiaoli; Dong, Xiuzhu

2005-05-01

225

Partial specific volume of cellulose acetate  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

226

Second virial coefficient of hydroxyethyl cellulose acetate  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

227

Second virial coefficient of cellulose acetate  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

228

Preparation and characterization of cellulose acetate organic ...  

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Source: Journal of Applied Polymer Science 58(8):1263-1274 ... The chemical, morphological, and mechanical properties of these films were evaluated with ... Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows ...

229

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.

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

1967-01-01

230

Enhanced propionic acid fermentation by Propionibacterium acidipropionici mutant obtained by adaptation in a fibrous-bed bioreactor.  

PubMed

Fed-batch fermentations of glucose by P. acidipropionici ATCC 4875 in free-cell suspension culture and immobilized in a fibrous-bed bioreactor (FBB) were studied. The latter produced a much higher propionic acid concentration (71.8 +/- 0.8 g/L vs. 52.2 +/- 1.1 g/L), indicating enhanced tolerance to propionic acid inhibition by cells adapted in the FBB. Compared to the free-cell fermentation, the FBB culture produced 20-59% more propionate (0.40-0.65 +/- 0.02 g/g vs. 0.41 +/- 0.02 g/g), 17% less acetate (0.10 +/- 0.01 g/g vs. 0.12 +/- 0.02 g/g), and 50% less succinate (0.09 +/- 0.02 g/g vs. 0.18 +/- 0.03 g/g) from glucose. The higher propionate production in the FBB was attributed to mutations in two key enzymes, oxaloacetate transcarboxylase and propionyl CoA: succinyl CoA transferase, leading to the production of propionic acid from pyruvate. Both showed higher specific activity and lower sensitivity to propionic acid inhibition in the mutant than in the wild type. In contrast, the activity of PEP carboxylase, which converts PEP directly to oxaloacetate and leads to the production of succinate from glucose, was generally lower in the mutant than in the wild type. For phosphotransacetylase and acetate kinase in the acetate formation pathway, however, there was no significant difference between the mutant and the wild type. In addition, the mutant had a striking change in its morphology. With a threefold increase in its length and approximately 24% decrease in its diameter, the mutant cell had an approximately 10% higher specific surface area that should have made the mutant more efficient in transporting substrates and metabolites across the cell membrane. A slightly lower membrane-bound ATPase activity found in the mutant also indicated that the mutant might have a more efficient proton pump to allow it to better tolerate propionic acid. In addition, the mutant had more longer-chain saturated fatty acids (C17:0) and less unsaturated fatty acids (C18:1), both of which could decrease membrane fluidity and might have contributed to the increased propionate tolerance. The enhanced propionic acid production from glucose by P. acidipropionici was thus attributed to both a high viable cell density maintained in the reactor and favorable mutations resulted from adaptation by cell immobilization in the FBB. PMID:15977254

Suwannakham, Supaporn; Yang, Shang-Tian

2005-08-01

231

Aerobic oxidation of ethane to acetic acid catalyzed by N,N?-dihydroxypyromellitimide combined with Co species  

Microsoft Academic Search

Aerobic oxidation of ethane to acetic acid was successfully performed through a catalytic radical process using N,N?-dihydroxypyromellitimide (NDHPI) combined with a Co(II) salt in acetonitrile or propionic acid. The turnover number of NDHPI reached 9.5 in acetonitrile and 15.3 in propionic acid.

Akihiro Shibamoto; Satoshi Sakaguchi; Yasutaka Ishii

2002-01-01

232

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.

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

1965-01-01

233

Propionate and butyrate dependent bacterial sulfate reduction at extremely haloalkaline conditions and description of Desulfobotulus alkaliphilus sp. nov.  

PubMed

Evidence on the utilization of simple fatty acids by sulfate-reducing bacteria (SRB) at extremely haloalkaline conditions are practically absent, except for a single case of syntrophy by Desulfonatronum on acetate. Our experiments with sediments from soda lakes of Kulunda Steppe (Altai, Russia) showed sulfide production with sulfate as electron acceptor and propionate and butyrate (but not acetate) as an electron donor at a pH 10-10.5 and a salinity 70-180 g l(-1). With propionate as substrate, a highly enriched sulfidogenic culture was obtained in which the main component was identified as a novel representative of the family Syntrophobacteraceae. With butyrate as substrate, a pure SRB culture was isolated which oxidized butyrate and some higher fatty acids incompletely to acetate. The strain represents the first haloalkaliphilic representative of the family Desulfobacteraceae and is described as Desulfobotulus alkaliphilus sp. nov. PMID:19888546

Sorokin, D Y; Detkova, E N; Muyzer, G

2009-11-04

234

Fragrance material review on 1,1-dimethyl-2-phenylethyl propionate.  

PubMed

A toxicologic and dermatologic review of 1,1-dimethyl-2-phenylethyl propionate when used as a fragrance ingredient is presented. 1,1-Dimethyl-2-phenylethyl propionate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 1,1-dimethyl-2-phenylethyl propionate were evaluated, then summarized, and includes: physical properties; acute toxicity; skin irritation; and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (submitted for publication) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406559

McGinty, D; Letizia, C S; Api, A M

2012-03-03

235

Propionic acid production in glycerol/glucose co-fermentation by Propionibacterium freudenreichii subsp. shermanii.  

PubMed

Propionibacterium freudenreichii subsp. shermanii can ferment glucose and glycerol to propionic acid with acetic and succinic acids as two by-products. Propionic acid production from glucose was relatively fast (0.19 g/Lh) but gave low product yield (~0.39 g/g) and selectivity (P/A: ~2.6; P/S: ~4.8). In contrast, glycerol with a more reduced state gave a high propionic acid yield (~0.65 g/g) and selectivity (P/A: ~31; P/S: ~11) but low productivity (0.11 g/L h). On the other hand, co-fermentation of glycerol and glucose at an appropriate mass ratio gave both a high yield (0.54-0.65 g/g) and productivity (0.18-0.23 g/L h) with high product selectivity (P/A: ~14; P/S: ~10). The carbon flux distributions in the co-fermentation as affected by the ratio of glycerol/glucose were investigated. Finally, co-fermentation with cassava bagasse hydrolysate and crude glycerol in a fibrous-bed bioreactor was demonstrated, providing an efficient way for economic production of bio-based propionic acid. PMID:23584412

Wang, Zhongqiang; Yang, Shang-Tian

2013-03-14

236

21 CFR 184.1784 - Sodium propionate.  

Code of Federal Regulations, 2010 CFR

...salt of propionic acid. It occurs as colorless, transparent crystals or a granular crystalline powder. It is odorless, or has...defined in § 170.3(n)(29) of this chapter; and soft candy as defined in § 170.3(n)(38) of this chapter....

2009-04-01

237

21 CFR 184.1784 - Sodium propionate.  

Code of Federal Regulations, 2010 CFR

...salt of propionic acid. It occurs as colorless, transparent crystals or a granular crystalline powder. It is odorless, or has...defined in § 170.3(n)(29) of this chapter; and soft candy as defined in § 170.3(n)(38) of this chapter....

2010-01-01

238

21 CFR 582.3081 - Propionic acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01 2013-04-01... 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 582.3081 Propionic acid....

2013-04-01

239

Reductive Carboxylation of Propionate to Butyrate in Methanogenic Ecosystems  

PubMed Central

During the batch degradation of sodium propionate by the anaerobic sludge from an industrial digestor, we observed a significant amount of butyrate formation. Varying the initial propionate concentrations did not alter the ratio of maximal butyrate accumulation to initial propionate concentration within a large range. By measuring the decrease in the radioactivity of [1-14C]butyrate during propionate degradation, we estimated that about 20% of the propionate was converted to butyrate. Labeled butyrate was formed from [1-14C]propionate with the same specific radioactivity, suggesting a possible direct pathway from propionate to butyrate. We confirmed this hypothesis by nuclear magnetic resonance studies with [13C]propionate. The results showed that [1-13C]-, [2-13C]-, and [3-13C]propionate were converted to [2-13C]-, [3-13C]-, and [4-13C]butyrate, respectively, demonstrating the direct carboxylation on the carboxyl group of propionate without randomization of the other two carbons. In addition, we observed an exchange reaction between C-2 and C-3 of the propionate, indicating that acetogensis may proceed through a randomizing pathway. The physiological significance and importance of various metabolic pathways involved in propionate degradation are discussed, and an unusual pathway of butyrate synthesis is proposed.

Tholozan, J. L.; Samain, E.; Grivet, J. P.; Moletta, R.; Dubourguier, H. C.; Albagnac, G.

1988-01-01

240

Spectrophotometric determination of clobetasol propionate, halobetasol propionate, quinagolide hydrochloride, through charge transfer complexation  

Microsoft Academic Search

Two spectrophotometric procedures are described for the determination of clobetasol propionate(I), halobetasol propionate(II) (corticosteroids) and quinagolide hydrochloride(III) (prolactin inhibitor). For corticosteroid drugs, the procedures are based on the formation of phenyl hydrazones of the corticosteroids which are subsequently subjected to charge transfer complexation reaction with either 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as ?-acceptor or with iodine as ?-acceptor. Prolactin inhibitor was reacted directly

Azza A. Mostafa; Lories I. Bebawy; Heba H. Refaat

2002-01-01

241

Enhancement of propionic acid fraction in volatile fatty acids produced from sludge fermentation by the use of food waste and Propionibacterium acidipropionici.  

PubMed

Volatile fatty acids (VFA) can be used as the additional carbon source of biological nutrient removal (BNR), and the increase of propionic acid percentage in VFA has been reported to facilitate the performance of BNR. In this study a new method for significantly improving the propionic acid fraction in VFA derived from waste activated sludge was reported, which included (1) mixing food waste with sludge and pre-fermenting the mixture (first stage), and (2) separating the mixture, sterilizing the pre-fermentation liquid and fermenting it after inoculating Propionibacterium acidipropionici (second stage). By optimizing the first stage with response surface methodology, a propionic acid content of 68.4% with propionic acid concentration of 7.13 g COD/L could be reached in the second stage, which was much higher than that reported previously. Lactic acid was found to be the most abundant product of the first stage and it served as the substrate for propionic acid production in the second stage. Further investigation showed that during the first stage the addition of food waste to the pre-fermentation system of sludge significantly increased the generation of lactic acid due to the synergistic effect, which resulted in the improvement of propionic acid production in the second stage. Finally, the use of propionic acid-enriched VFA as a superior carbon source of BNR was tested, and its performance was observed to be much better than using acetic acid-enriched VFA derived from sludge by the previously documented method. PMID:23219005

Chen, Yinguang; Li, Xiang; Zheng, Xiong; Wang, Dongbo

2012-10-29

242

Electrospun cellulose nanofiber as affinity membrane  

Microsoft Academic Search

The objective of this work is to study the feasibility of applying cellulose nanofiber membrane prepared by electrospinning as affinity membrane. Cellulose acetate (CA) solution (0.16g\\/ml) in a mixture solvent of acetone\\/DMF\\/trifluoroethylene (3:1:1) was electrospun into nonwoven fiber mesh with the fiber diameter ranging from 200nm to 1?m. The CA nanofiber mesh was heat treated under 208°C for 1h to

Zuwei Ma; M. Kotaki; S. Ramakrishna

2005-01-01

243

A rapid capillary gas chromatographic method for the determination of propionic acid and propionates in bread and bread products  

Microsoft Academic Search

A rapid method for the determination of propionic acid and propionates in bread and bread products is reported. The method employs solvent extraction, filtration and quantification by capillary gas chromatography using an internal standard. The limit of determination was l0 mg kg propionic acid. The mean recovery rates for spiked bread samples were 108% at approximately 1000 mg kg (range

M. J. Scotter; S. A. Thorpe; S. L. Reynolds; L. A. Wilson; P. R. Strutt

1994-01-01

244

Fragrance material review on 3-phenylpropyl acetate.  

PubMed

A toxicologic and dermatologic review of 3-phenylpropyl acetate when used as a fragrance ingredient is presented. 3-Phenylpropyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 3-phenylpropyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, skin sensitization, and toxicokinetics data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al., 2012 for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414651

McGinty, D; Letizia, C S; Api, A M

2012-03-04

245

Fragrance material review on anisyl acetate.  

PubMed

A toxicologic and dermatologic review of anisyl acetate when used as a fragrance ingredient is presented. Anisyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for anisyl acetate were evaluated, then summarized, and includes: physical properties, skin irritation, skin sensitization, elicitation, and phototoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al., 2012 for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414654

McGinty, D; Letizia, C S; Api, A M

2012-03-03

246

Fragrance material review on 4-methylbenzyl acetate.  

PubMed

A toxicologic and dermatologic review of 4-methylbenzyl acetate when used as a fragrance ingredient is presented. 4-Methylbenzyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 4-methylbenzyl acetate were evaluated, then summarized, and includes: physical properties, skin irritation, skin sensitization, and elicitation data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414643

McGinty, D; Letizia, C S; Api, A M

2012-03-05

247

Antibacterial Textile Finishes Utilizing Zirconyl Acetate Complexes of Inorganic Peroxides.  

National Technical Information Service (NTIS)

This invention relates to a new method of forming water-insoluble peroxide complexes of zirconyl acetate as deposits, films, and coatings on and within cellulosic fibers, yarns, and fabrics, as well as paper. Peroxides operative in forming these complexes...

C. M. Welch G. F. Danna T. L. Vigo

1977-01-01

248

Fluticasone Propionate Liposomes for Pulmonary Delivery  

PubMed Central

The objective of the present study was to entrap fluticasone propionate in liposomes and study in vitro lung deposition of both liposomal dispersion and dry powder inhalation using twin stage impinger and Anderson cascade impactor. Liposomes were prepared by lipid film hydration method and characterized for size, shape, morphology, entrapment efficiency and in vitro lung deposition. The spray dried liposomes were further characterized for various physicochemical properties such as physical appearance, density, flow properties, drug content and in vitro pulmonary deposition. Fine particle fraction was also determined. Liposomal dispersion of fluticasone propionate was successfully prepared with more than 90% entrapment. Spray dried liposomes had mean size of 3-4 ? and a fine powder fraction of 9-10 %. Inclusion of antistatic agents such as leucine and magnesium stearate did not improve the aerosolisation behaviour of dry inhalation powder in this study.

Nirale, N. M.; Vidhate, R. D.; Nagarsenker, M. S.

2009-01-01

249

Propyl propionate methanolysis kinetics: experiment and modeling.  

PubMed

In concentrated solutions, the reaction rate constant calculated from the law of mass action depends on a mixture composition. In this study, we suggest a new approach based on the dynamic equilibrium principle and modified equations of van Rysselberghe and de Donder. Experimental results obtained for propyl propionate methanolysis are in good agreement with calculated ones in the entire area of studied compositions. Such a method allows one to describe kinetics of reversible chemical reactions on both sides of the equilibrium. PMID:23991713

Povarov, Vladimir G; Keresten, Andrey A

2013-09-17

250

Polyhydroxyalkanoates production from cellulose hydrolysate in Escherichia coli LS5218 with superior resistance to 5-hydroxymethylfurfural.  

PubMed

Poly[3-hydroxybutyrate-co-3-hydroxyvalerate(3HV)] was produced in recombinant Escherichia coli LS5218 from ruthenium-catalyzed cellulose hydrolysate and propionate. The strain was found to be resistant to 5-hydroxymethylfurfural (5-HMF), which is a major inhibitory byproduct generated in the cellulose hydrolysis reaction. The 3HV fraction was successfully regulated in the range of 5.6-40 mol%. PMID:21993429

Nduko, John Masani; Suzuki, Wakako; Matsumoto, Ken'ichiro; Kobayashi, Hirokazu; Ooi, Toshihiko; Fukuoka, Atsushi; Taguchi, Seiichi

2011-10-12

251

Polyhydroxyalkanoates production from cellulose hydrolysate in Escherichia coli LS5218 with superior resistance to 5-hydroxymethylfurfural  

Microsoft Academic Search

Poly[3-hydroxybutyrate-co-3-hydroxyvalerate(3HV)] was produced in recombinant Escherichia coli LS5218 from ruthenium-catalyzed cellulose hydrolysate and propionate. The strain was found to be resistant to 5-hydroxymethylfurfural (5-HMF), which is a major inhibitory byproduct generated in the cellulose hydrolysis reaction. The 3HV fraction was successfully regulated in the range of 5.6–40mol%.

John Masani Nduko; Wakako Suzuki; Ken'ichiro Matsumoto; Hirokazu Kobayashi; Toshihiko Ooi; Atsushi Fukuoka; Seiichi Taguchi

252

Synthesis and charge\\/discharge properties of cellulose derivatives carrying free radicals  

Microsoft Academic Search

Ethyl cellulose derivatives [EC-T and EC-P] and cellulose acetate derivatives [CA-T and CA-P] carrying TEMPO or PROXY radicals (TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxy, PROXY=2,2,5,5-tetramethyl-1-pyrrolidinyloxy) were synthesized with moderate number-average molecular weights of 62?400–126?000 in 84–88% yield by the reaction of 4-carboxy-TEMPO or 3-carboxy-PROXY with residual hydroxyl group of ethyl cellulose or cellulose acetate. All the free radical-containing cellulose derivatives demonstrated reversible charge\\/discharge processes, whose

Jinqing Qu; Fareha Zafar Khan; Masaharu Satoh; Jun Wada; Hiroyuki Hayashi; Kenji Mizoguchi; Toshio Masuda

2008-01-01

253

Fermentation of cellulose and fatty acids with enrichments from sewage sludge  

Microsoft Academic Search

A mixed culture enriched from sewage sludge and anaerobic digestor effluent was able to degrade cellulose and acetate rapidly and quantitatively to methane and carbon dioxide. The maximum specific rate of gas production was 87 ml\\/gm cell-h, corresponding to a rate of cellulose utilization of 0.1 g\\/g cells-h. Acetate, an intermediate in cellulose degradation, was fermented much more rapidly than

Josef U. Winter; Charles L. Cooney

1980-01-01

254

N-carbamylglutamate augments ureagenesis and reduces ammonia and glutamine levels in patients with propionic acidemia  

PubMed Central

Objective To determine whether N-carbamylglutamate reduces plasma levels of ammonia and glutamine and increases ureagenesis rate in patients with propionic acidemia Patients and Methods Identical four-hour studies were performed before and immediately after a 3-day trial of oral N-carbamylglutamate in 7 patients with propionic acidemia. An oral bolus of [13C]-sodium acetate was administered at the start of each study, and sequential blood samples were obtained to measure [13C]-urea, ammonia, urea and amino acids. Results With longitudinal mixed effects linear regression, peak [13C]urea increased following treatment with N-carbamylglutamate (from 2.2 ?M to 3.8 ?M; p < 0.0005). There were concomitant decreases in mean plasma ammonia (59 to 43 ?M, p <0.0005)) and glutamine (552 to 331 ?M, p <0.0005). Conclusion N-carbamylglutamate augments ureagenesis and decreases plasma ammonia and glutamine in patients with propionic acidemia. The drug may serve as an important therapeutic adjunct in the treatment of acute hyperammonemia in this disorder.

Mew, Nicholas Ah; McCarter, Robert; Daikhin, Yevgeny; Nissim, Itzhak; Yudkoff, Marc; Tuchman, Mendel

2012-01-01

255

Effects of hydrogen and formate on the degradation of propionate and butyrate in thermophilic granules from an upflow anaerobic sludge blanket reactor.  

PubMed Central

Degradation of propionate and butyrate in whole and disintegrated granules from a thermophilic (55 degrees C) upflow anaerobic sludge blanket reactor fed with acetate, propionate, and butyrate as substrates was examined. The propionate and butyrate degradation rates in whole granules were 1.16 and 4.0 mumol/min/g of volatile solids, respectively, and the rates decreased 35 and 25%, respectively, after disintegration of the granules. The effect of adding different hydrogen-oxidizing bacteria (both sulfate reducers and methanogens), some of which used formate in addition to hydrogen, to disintegrated granules was tested. Addition of either Methanobacterium thermoautotrophicum delta H, a hydrogen-utilizing methanogen that does not use formate, or Methanobacterium sp. strain CB12, a hydrogen- and formate-utilizing methanogen, to disintegrated granules increased the degradation rate of both propionate and butyrate. Furthermore, addition of a thermophilic sulfate-reducing bacterium (a Desulfotomaculum sp. isolated in our laboratory) to disintegrated granules improved the degradation of both substrates even more than the addition of methanogens. By monitoring the hydrogen partial pressure in the cultures, a correlation between the hydrogen partial pressure and the degradation rate of propionate and butyrate was observed, showing a decrease in the degradation rate with increased hydrogen partial pressure. No significant differences in the stimulation of the degradation rates were observed when the disintegrated granules were supplied with methanogens that utilized hydrogen only or hydrogen and formate. This indicated that interspecies formate transfer was not important for stimulation of propionate and butyrate degradation.

Schmidt, J E; Ahring, B K

1993-01-01

256

Adsorption of carboxymethyl cellulose on polymer surfaces: evidence of a specific interaction with cellulose.  

PubMed

The adsorption of carboxymethyl cellulose (CMC), one of the most important cellulose derivatives, is crucial for many scientific investigations and industrial applications. Especially for surface modifications and functionalization of materials, the polymer is of interest. The adsorption properties of CMC are dependent not only on the solutions state, which can be influenced by the pH, temperature, and electrolyte concentration, but also on the chemical composition of the adsorbents. We therefore performed basic investigation studies on the interaction of CMC with a variety of polymer films. Thin films of cellulose, cellulose acetate, deacetylated cellulose acetate, polyethylene terephthalate, and cyclo olefin polymer were therefore prepared on sensors of a QCM-D (quartz crystal microbalance) and on silicon substrates. The films were characterized with respect to the thickness, wettability, and chemical composition. Subsequently, the interaction and deposition of CMC in a range of pH values without additional electrolyte were measured with the QCM-D method. A comparison of the QCM-D results showed that CMC is favorably deposited on pure cellulose films and deacetylated cellulose acetate at low pH values. Other hydrophilic surfaces such as silicon dioxide or polyvinyl alcohol coated surfaces did not adsorb CMC to a significant extent. Atomic force microcopy confirmed that the morphology of the adsorbed CMC layers differed depending on the substrate. On hydrophobic polymer films, CMC was deposited in the form of larger particles in lower amounts whereas hydrophilic cellulose substrates were to a high extent uniformly covered by adsorbed CMC. The chemical similarity of the CMC backbone seems to favor the irreversible adsorption of CMC when the molecule is almost uncharged at low pH values. A selectivity of the cellulose CMC interaction can therefore be assumed. All CMC treated polymer films exhibited an increased hydrophilicity, which confirmed their modification with the functional molecule. PMID:22759080

Kargl, Rupert; Mohan, Tamilselvan; Bra?i?, Matej; Kulterer, Martin; Doliška, Aleš; Stana-Kleinschek, Karin; Ribitsch, Volker

2012-07-23

257

Propionate metabolism in Saccharomyces cerevisiae: implications for the metabolon hypothesis.  

PubMed

Aerobic, glucose-limited chemostat of Saccharomyces cerevisiae CBS 8066 co-metabolized propionate when this compound was added to the reservoir medium. Co-metabolism of propionate led to an increase of the biomass and protein yields. Attempts to grow S. cerevisiae on propionate as a sole source of carbon and energy were not successful. Activities of propionyl-CoA synthetase in cell-free extracts were sufficient to account for the rates of propionate consumption observed in the chemostat cultures. Activities of propionyl-CoA carboxylase, a key enzyme of the methylmalonyl-CoA pathway of propionate metabolism, were negligible. In contrast, activities of 2-methylcitrate synthase, a key enzyme activity of the 2-methylcitrate pathway of propionate metabolism, increased substantially with increasing propionate-to-glucose ratios in the reservoir media, and were sufficient to account for the propionate consumption rates observed in the chemostat cultures. This suggested that the 2-methylcitrate pathway is the major pathway of propionate metabolism in S. cerevisiae. In the literature, labelling patterns observed after incubation of this yeast with [3-13C]propionate have been interpreted as evidence for channelling of tricarboxylic acid (TCA) cycle intermediates, possibly as a consequence of the organization of TCA cycle enzymes in a metabolon. However, this interpretation of 13C-labelling patterns rested on the assumption that propionate metabolism in S. cerevisiae occurs via the methylmalonyl-CoA pathway. Since the distribution of 13C in alanine reported in the literature is fully compatible with a major role of the 2-methylcitrate pathway in propionate metabolism, it cannot be interpreted as evidence for the existence of a TCA cycle metabolon in S. cerevisiae. PMID:7912143

Pronk, J T; van der Linden-Beuman, A; Verduyn, C; Scheffers, W A; van Dijken, J P

1994-04-01

258

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

259

Cellulose carbamates and derivatives as hemocompatible membrane materials for hemodialysis.  

PubMed

Dialysis membranes made from regenerated cellulose are under dispute because of their alleged lack of hemocompatibility. The introduction of membranes from synthetically modified cellulose, like cellulose acetate or Hemophan, has proven, however, that hemocompatible membranes can be fabricated from cellulose by means of chemical surface modifications. In addition to membranes made from modified cellulose like ethers or esters, which were investigated in earlier experiments, we looked for further cellulose modifications to be assessed for their hemocompatibility. For this purpose, we synthesized a series of cellulose carbamate derivatives to profit from the excellent hemocompatibility pattern of the urethane family. In vitro investigations on membranes made from these cellulose modifications proved a direct relationship between the degree of modification and hemocompatibility. This was proven for the following 3 representative hemocompatibility parameters: complement C5a generation, thrombin-antithrombin (TAT) III formation, and platelet count (PC). As already shown for modifications made from cellulose esters, a direct dependency between improved hemocompatibility and the degree of substitution (DS) in the cellulose molecule could be found. In our experiments, a degree of substitution below a value of 0.1 led to a nearly complete suppression of complement activation for all cellulose carbamates under investigation. In contrast to data on cellulose esters, we observed that molecular weight or molecular conformation of chemical substituents exerted only a minor effect on the hemocompatibility pattern. In addition, data on cellulose carbamate esters (e.g., cellulose succinate-phenyl-carbamate) show that a simultaneous but balanced substitution with hydrophilic and hydrophobic groups at the surface of the cellulose polymer is a further prerequisite for optimal hemocompatibility. It seems that the carbamate configuration per se has a positive effect on the hemocompatibility pattern of synthetically modified cellulose membranes. PMID:9950174

Diamantoglou, M; Platz, J; Vienken, J

1999-01-01

260

Purification of aqueous cellulose ethers  

SciTech Connect

Manufacture of cellulose ethers usually involves high amounts of salt by-products. For application of the product, salt must be removed. In this work, we have studied the injection of high-pressure CO{sub 2} into an aqueous polymer-salt solution; we find that upon addition of isopropanol in addition to CO{sub 2}, the solution separates into two phases. One phase is rich in polymer and water, and the other phase contains mostly isopropanol, water and CO{sub 2}. The salt distributes between the two phases, thereby offering interesting possibilities for development of a new purification process for water-soluble polymers. This work presents experimental phase-equilibrium data for hydroxyethyl cellulose and sodium carboxymethyl cellulose with sodium acetate and potassium sulfate, respectively, in the region 40{degree}C and 30 to 80 bar. Based on these data, we suggest a process for the manufacture and purification of water-soluble cellulose ethers. 15 refs., 14 figs., 9 tabs.

Bartscherer, K.A.; de Pablo, J.J.; Bonnin, M.C.; Prausnitz, J.M.

1990-07-01

261

An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.  

PubMed

An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30 g L(-1) h(-1), respectively, from 50 g L(-1) glycerol at initial cell density of 23.7 gCDW L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ~39% each. At glycerol concentrations of 85 and 120 g L(-1), respectively, 43.8 and 50.8 g L(-1) propionic acid were obtained at a rate of 0.88 and 0.29 g L(-1) h(-1) and yield of 84 and 78 mol%. Succinic acid was 13 g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source. PMID:23041117

Dishisha, Tarek; Ståhl, Åke; Lundmark, Stefan; Hatti-Kaul, Rajni

2012-08-31

262

21 CFR 175.230 - Hot-melt strippable food coatings.  

Code of Federal Regulations, 2010 CFR

...substances Limitations Acetylated monoglycerides Complying with 172.828 of this chapter. Cellulose acetate butyrate Cellulose acetate propionate Mineral oil, white For use only as a component of hot-melt strippable food...

2013-04-01

263

Design and control of acetic acid dehydration system via heterogeneous azeotropic distillation  

Microsoft Academic Search

Acetic acid dehydration is an important operation in the production of aromatic acid, such as terephthalic acid or in the manufacture of cellulose acetate. Although acetic acid and water does not form azeotrope, but using simple distillation to separate these two components is not practical. The reason is because the system has tangent pinch on the pure water end, thus

I. Lung Chien; Kai-Luen Zeng; Huan-Yi Chao; Jun Hong Liu

2004-01-01

264

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

265

Combination particles containing salmeterol xinafoate and fluticasone propionate: Formulation and aerodynamic assessment.  

PubMed

A precipitation process is used to produce combined particles consisting of two antiasthmatic drugs: salmeterol xinafoate and fluticasone propionate. To control the crystallisation of these particles, a micromixer is used to mix solvent and antisolvent flow. To produce particles in the respirable range, crystal growth inhibitors are added to the antisolvent flow. The obtained suspension is spray-dried afterwards to get a dry powder which can be further processed into inhalation drug products. It is found that a combination of polysorbate 80 and hydroxypropylmethyl cellulose (HPMC) represents the best excipient combination. It is supposed that the smaller molecule polysorbate rapidly stabilises the particle surface and with this inhibits crystal growth, whereas HPMC is observed to produce spherical particles during the spray-drying process acting as lubricant and dispersion-modifier. The processed particles show a needlelike habit and, therefore, tend to form aggregates. When dispersed from an inhaler device, they are only moderately disaggregated. The deposition of the single drugs salmeterol xinafoate and fluticasone propionate on the stages of the NGI shows a very uniform distribution, indicating that both drugs are evenly dispensed, with an FPF of about 22% for the combined particles which corresponds to the deposition of the marketed product. PMID:17879293

Westmeier, Regina; Steckel, Hartwig

2008-06-01

266

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

267

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

Federal Register 2010, 2011, 2012, 2013

...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

268

45-Year-old female with propionic acidemia, renal failure, and premature ovarian failure; late complications of propionic acidemia?  

PubMed

We describe a 45-year-old patient who was diagnosed with propionic acidemia in infancy, who experienced an unstable first two years of life but who eventually had a good developmental outcome. She developed severe renal failure requiring renal transplantation in her forties and premature ovarian failure. Renal failure and premature ovarian failure have not previously been associated with propionic acidemia. We hypothesize that propionic acidemia may have contributed to these complications, and discuss several possible mechanisms for this, emphasizing mainly the electron transport chain/mitochondrial energy deficiency hypothesis. PMID:21549625

Lam, Christina; Desviat, Lourdes R; Perez-Cerdá, Celia; Ugarte, Magdalena; Barshop, Bruce A; Cederbaum, Stephen

2011-04-22

269

Chronic management and health supervision of individuals with propionic acidemia.  

PubMed

Propionic acidemia is a relatively rare inborn error of metabolism. Individuals with propionic acidemia often have life-threatening episodes of hyperammonemia and metabolic acidosis, as well as intellectual disability. There are many reports of additional problems, including poor growth, stroke-like episodes of the basal ganglia, seizures, cardiomyopathy, long QTc syndrome, immune defects, pancreatitis and optic neuropathy; however, there is little information about the incidence of these problems in this rare disease. Additionally, there are no clear guidelines for medical or surgical management of individuals with propionic acidemia. Through a comprehensive and systematic review of the current medical literature and survey of expert opinion, we have developed practice guidelines for the chronic management of individuals with propionic acidemia, including dietary therapy, use of medications, laboratory monitoring, chronic health supervision, use of gastrostomy tubes and liver transplantation. PMID:21963082

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

2011-09-10

270

Chronic Kidney Disease in an Adult with Propionic Acidemia.  

PubMed

We report an adult male with classic propionic acidemia (PA) who developed chronic kidney disease in the third decade of his life. This diagnosis was recognized by an increasing serum creatinine and confirmed by reduced glomerular filtration on a (99m)Tc-diethylenetriamine pentaacetate (DTPA) scan. Histopathology of the kidney showed moderate glomerulo- and tubulointerstitial fibrosis with very segmental mesangial IgA deposits. This is the second reported case of kidney disease in an individual with propionic acidemia possibly indicating that chronic kidney disease may be a late-stage complication of propionic acidemia. Additionally, this is the first description of the histopathology of kidney disease in an individual with propionic acidemia. As more cases emerge, the clinical course and spectrum of renal pathology in this disorder will be better defined. PMID:23756992

Vernon, H J; Bagnasco, S; Hamosh, A; Sperati, C J

2013-06-12

271

Clobetasol propionate in the treatment of premenarchal vulvar lichen sclerosus  

Microsoft Academic Search

OBJECTIVE:To assess the effectiveness of treating premenarchal vulvar lichen sclerosus with clobetasol propionate.METHODS:A retrospective chart review was performed of girls presenting to the University of Michigan Pediatric and Adolescent Gynecology Clinic from January, 1995, to July, 2000, with premenarchal lichen sclerosus. Subjects in the study were treated with topical clobetasol propionate ointment 0.05% for 2–4 weeks, and then tapered to

Yolanda R Smith; Elisabeth H Quint

2001-01-01

272

Short chain fatty acid distributions of enema samples from a sigmoidoscopy population: an association of high acetate and low butyrate ratios with adenomatous polyps and colon cancer  

Microsoft Academic Search

We investigated the distribution of short chain fatty acids (SCFA) in enema samples taken from subjects before sigmoidoscopy as an indicator of possible microbial community differences between subjects subsequently diagnosed as normal or having colonic disorders. The major SCFA in all groups were acetic, propionic, and butyric acids. A significantly higher ratio of acetate to total SCFA and lower ratio

G A Weaver; J A Krause; T L Miller; M J Wolin

1988-01-01

273

Epilepsy in patients with propionic acidemia.  

PubMed

Propionic acidemia (PA) is an autosomal recessively inherited defect of propionyl-CoA carboxylase with an incidence of approximately 1:50 000. There are few reports on the occurrence of EEG findings and development of epilepsy in patients with PA. Retrospectively, the data of 17 patients with PA from one Italian and four Austrian centers were evaluated concerning EEG findings and the development of epilepsy. Nine patients showed a disturbance of background activity, as well as epileptiform discharges. All nine patients with pathological EEG discharges developed seizures compatible with the definition of symptomatic epilepsy. Five of these nine patients showed fever induced seizures at the beginning. Two of them suffered from symptomatic absence epilepsy. Six of the nine patients with seizures were treated with antiepileptic drugs (AED), which were tolerated without side-effects. Four patients showed photosensitivity, which so far has never been reported in PA. We hypothesize that patients with PA are prone to cortical dysfunction caused by one or several pathological metabolites - leading to changes in background and epileptiform activity with a high manifestation rate of clinical seizures. PMID:20020396

Haberlandt, E; Canestrini, C; Brunner-Krainz, M; Möslinger, D; Mussner, K; Plecko, B; Scholl-Bürgi, S; Sperl, W; Rostásy, K; Karall, D

2009-12-17

274

Fragrance material review on 2-hydroxy-2-phenylethyl acetate.  

PubMed

A toxicologic and dermatologic review of 2-hydroxy-2-phenylethyl acetate when used as a fragrance ingredient is presented. 2-Hydroxy-2-phenylethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-hydroxy-2-phenylethyl acetate was evaluated then summarized and includes physical properties data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414656

McGinty, D; Letizia, C S; Api, A M

2012-03-03

275

Fragrance material review on 2-(p-tolyloxy)ethyl acetate.  

PubMed

A toxicologic and dermatologic review of 2-(p-tolyloxy)ethyl acetate when used as a fragrance ingredient is presented. 2-(p-tolyloxy)ethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-(p-tolyloxy)ethyl acetate were evaluated, then summarized, and includes physical properties data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414652

McGinty, D; Letizia, C S; Api, A M

2012-03-04

276

Derivatization-free gel permeation chromatography elucidates enzymatic cellulose hydrolysis  

PubMed Central

Background The analysis of cellulose molecular weight distributions by gel permeation chromatography (GPC) is a powerful tool to obtain detailed information on enzymatic cellulose hydrolysis, supporting the development of economically viable biorefinery processes. Unfortunately, due to work and time consuming sample preparation, the measurement of cellulose molecular weight distributions has a limited applicability until now. Results In this work we present a new method to analyze cellulose molecular weight distributions that does not require any prior cellulose swelling, activation, or derivatization. The cellulose samples were directly dissolved in dimethylformamide (DMF) containing 10-20% (v/v) 1-ethyl-3-methylimidazolium acetate (EMIM Ac) for 60?minutes, thereby reducing the sample preparation time from several days to a few hours. The samples were filtrated 0.2??m to avoid column blocking, separated at 0.5?mL/min using hydrophilic separation media and were detected using differential refractive index/multi angle laser light scattering (dRI/MALLS). The applicability of this method was evaluated for the three cellulose types Avicel, ?-cellulose and Sigmacell. Afterwards, this method was used to measure the changes in molecular weight distributions during the enzymatic hydrolysis of the different untreated and ionic liquid pretreated cellulose substrates. The molecular weight distributions showed a stronger shift to smaller molecular weights during enzymatic hydrolysis using a commercial cellulase preparation for cellulose with lower crystallinity. This was even more pronounced for ionic liquid-pretreated cellulose. Conclusions In conclusion, this strongly simplified GPC method for cellulose molecular weight distribution allowed for the first time to demonstrate the influence of cellulose properties and pretreatment on the mode of enzymatic hydrolysis.

2012-01-01

277

TBAF-catalyzed deacylation of cellulose esters: Reaction scope and influence of reaction parameters.  

PubMed

In order to expand its utility and understand how to carry it out most efficiently, the scope of the highly regioselective, tetrabutylammonium fluoride (TBAF) catalyzed deacylation of cellulose acetates has been investigated, including the influence of key process parameters: solvent, temperature, and water content. Reactions in DMSO, THF, MEK and acetone afforded similar extents of deacylation and regioselectivity. Reaction with TBAF in DMSO at 50°C for 18h was the most efficient process providing regioselective deacylation at O-2/3. All results were consistent with our previous mechanistic proposals. Furthermore, we demonstrate that TBAF-catalyzed deacylation is also effective and regioselective with cellulose acetate, butyrate, and hexanoate triesters, and even with a cellulose ester devoid of alpha protons, cellulose tribenzoate. These reactions displayed regioselectivity for deacylation at O-2/3 similar to that observed earlier with cellulose acetate (DS 2.4). PMID:23987400

Zheng, Xueyan; Gandour, Richard D; Edgar, Kevin J

2013-06-20

278

Mechanochemical preparation of surface-acetylated cellulose powder to enhance mechanical properties of cellulose-filler-reinforced NR vulcanizates  

Microsoft Academic Search

Wood fibers composed mainly of cellulose were subjected to mechanochemical reaction with acetic anhydride to prepare surface-acetylated cellulose powder (SACP) through pan-milling in solid-state at ambient temperature. Fourier transform infrared spectroscopy and contact angle measurements confirmed the realization of chemical modification on the powder surface. Curing characteristics indicated that natural rubber (NR) compounds filled with SACP possessed better processability and

Wei Zhang; Xinxing Zhang; Mei Liang; Canhui Lu

2008-01-01

279

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.

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

2011-01-01

280

Cellulose of Salicornia brachiata.  

PubMed

Cellulose was extracted from the roots, stems and stem tips of Salicornia brachiata Roxb. Each crude cellulose sample obtained was fractionated into alpha- and beta-celluloses. The yields of crude cellulose from the stems and stem tips were greatest and lowest, respectively, while the yields of alpha- and beta-celluloses were in the order, roots > stems > stem tips. The cellulose samples were characterized by Fourier transform infrared spectroscopy (FT-IR), solid state cross polarisation magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CP/MAS 13C NMR), X-ray diffraction pattern (XRD), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). The data were compared with those of the celluloses (predominantly alpha-cellulose) isolated from Whatman filter paper No. 4 (WFP). PMID:20433080

Sanandiya, Naresh D; Prasad, Kamalesh; Meena, Ramavatar; Siddhanta, Arup K

2010-04-01

281

Microbiology and physiology of anaerobic fermentations of cellulose. Progress report, September 1, 1979May 15, 1980  

Microsoft Academic Search

Reseach progress is reported for the period September, 1979 to May, 1980. Studies on the mesophilic and thermophilic microorganisms fermenting cellulose to various products (ethanol, acetate, COâ, Hâ, and methane) are summarized. (ACR)

H. D. Jr. Peck; L. G. Ljungdahl

1980-01-01

282

MECHANISMS IN CELLULOSE BIOSYNTHESIS  

Microsoft Academic Search

Cellulose is a major industrial biopolymer in the forest products, textile, and chemical industries. It also forms a large portion of the biomass useful in the generation of energy. Moreover, cellulose-based biomass is a renewable energy source that can be used for the generation of ethanol as a fuel. Cellulose is synthesized by a variety of living organisms, including plants,

Inder M. Saxena; T. Dandekar; R. Malcolm Brown

283

Fragrance material review on phenethyl acetate.  

PubMed

A toxicologic and dermatologic review of phenethyl acetate when used as a fragrance ingredient is presented. Phenethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for phenethyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, elicitation, toxicokinetics, repeated dose, genotoxicity, and carcinogenicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414644

McGinty, D; Vitale, D; Letizia, C S; Api, A M

2012-03-05

284

Fragrance material review on ?-methylbenzyl acetate.  

PubMed

A toxicologic and dermatologic review of ?-methylbenzyl acetate when used as a fragrance ingredient is presented. ?-Methylbenzyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for ?-methylbenzyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, elicitation, and repeated dose data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406576

McGinty, D; Letizia, C S; Api, A M

2012-03-03

285

Fragrance material review on piperonyl acetate.  

PubMed

A toxicologic and dermatologic review of piperonyl acetate when used as a fragrance ingredient is presented. Piperonyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for piperonyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, toxicokinetics, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22445840

McGinty, D; Letizia, C S; Api, A M

2012-03-15

286

Fragrance material review on 2-phenylpropyl acetate.  

PubMed

A toxicologic and dermatologic review of 2-phenylpropyl acetate when used as a fragrance ingredient is presented. 2-Phenylpropyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-phenylpropyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22421639

McGinty, D; Letizia, C S; Api, A M

2012-03-06

287

Cellulose Catabolism by Clostridium cellulolyticum Growing in Batch Culture on Defined Medium  

Microsoft Academic Search

liter 21 , acetate, ethanol, H2, and CO2 were the main end products of the fermentation and cellulose degra- dation reached more than 85% in 5 days. The electron flow from the glycolysis was balanced by the production of H2 and ethanol, the latter increasing with increasing initial cellulose concentration. From 6.7 to 29.1 g of cellulose liter 21 ,

MICKAEL DESVAUX; EMMANUEL GUEDON; HENRI PETITDEMANGE

2000-01-01

288

Cellulose\\/chitosan hybrid nanofibers from electrospinning of their ester derivatives  

Microsoft Academic Search

A facile approach has been established to generate cellulose\\/chitosan hybrid nanofibers with full range of compositions by\\u000a electrospinning of their ester derivatives, cellulose acetate (CA) and dibutyryl chitin (DBC), followed by alkaline hydrolysis\\u000a to cellulose (Cell) and chitosan (CS). DBC was synthesized by acid-catalyzed acylation of chitin (CHI) with butyric anhydride\\u000a and the newly formed butyl groups on C3 and

Jian Du; You-Lo Hsieh

2009-01-01

289

Surface acetylation of cellulose nanocrystal and its reinforcing function in poly(lactic acid)  

Microsoft Academic Search

A novel and facile method for surface acetylation of cellulose nanocrystals (CN) was developed by reaction with acetic anhydride and hydroxyl groups on the surface of CN. The resultant acetylated cellulose nanocrystals (ACN) exhibited improved dispersion in various organic solvents and reduced polarity as compared with unmodified CN. These ACN were subsequently introduced into a poly(lactic acid) (PLA) polymeric matrix

Ning Lin; Jin Huang; Peter R. Chang; Jiwen Feng; Jiahui Yu

2011-01-01

290

Single step conversion of cellulose to ethanol by a mesophilic coculture  

Microsoft Academic Search

A coculture consisting of two mesophilic anaerobes, produced about 0.8 mole of ethanol per mole of cellulose from a variety of cellulosic materials. The non-cellulolytic member of this coculture, Clostridium saccharolyticum sp. nov. converted glucose and xylose to ethanol and acetic acid in ratios over 4 to 1.

A. W. Khan; William D. Murray

1982-01-01

291

Preparation and characterization of sodium caseinate films reinforced with cellulose derivatives  

Microsoft Academic Search

Edible composite films, based on glycerol-plasticized sodium caseinate (SC) and either carboxymethyl cellulose (CMC) or cellulose acetate (CA) fibers, were respectively prepared by suspension casting. The effects of mixing SC with very low amounts (up to 3wt%) of CMC or CA were systematically investigated through changes in morphology, surface hydrophilicity, moisture sorption, water vapor permeability, opacity, dynamic mechanical response and

Mariana Pereda; Guillermina Amica; Ilona Rácz; Norma E. Marcovich

2011-01-01

292

Analysis of polymer heterogeneity by sedimentation transport: 3. Hydroxypropyl cellulose derivatives in organic solvents  

Microsoft Academic Search

The sedimentation velocity of hydroxypropyl cellulose acetate and cyanoethylhydroxypropyl cellulose molecules has been investigated in dilute solution in organic solvents. For these polymers, a linear dependence of the standard deviation of the displacement spectrum of macromolecules in an ultracentrifuge field on the sedimentation boundary shift was observed. The method of moments with linear approximations was used to exclude the concentration

Peter N. Lavrenko; Alexander B. Melnikov

1996-01-01

293

Silica modified cellulosic aerogels  

Microsoft Academic Search

\\u000a Abstract  Shaped cellulosic aerogels—as the ‘young’ generation succeeding the well-established silica and synthetic polymer-based aerogels—are\\u000a intriguing materials that feature properties similar to those of their antecessors combined with the additional advantages\\u000a and characteristics of the re-growing biopolymer cellulose. Reinforced shaped cellulosic aerogels consisting of two interpenetrating\\u000a networks of cellulose and silica were prepared from shaped cellulose solutions by (1) regenerating (reprecipitating)

Marco Litschauer; Marie-Alexandra Neouze; Emmerich Haimer; Ute Henniges; Antje Potthast; Thomas Rosenau; Falk Liebner

2011-01-01

294

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

295

Ethanol Production by Thermophilic Bacteria: Fermentation of Cellulosic Substrates by Cocultures of Clostridium thermocellum and Clostridium thermohydrosulfuricum  

PubMed Central

The fermentation of various saccharides derived from cellulosic biomass to ethanol was examined in mono- and cocultures of Clostridium thermocellum strain LQRI and C. thermohydrosulfuricum strain 39E. C. thermohydrosulfuricum fermented glucose, cellobiose, and xylose, but not cellulose or xylan, and yielded ethanol/acetate ratios of >7.0. C. thermocellum fermented a variety of cellulosic substrates, glucose, and cellobiose, but not xylan or xylose, and yielded ethanol/acetate ratios of ?1.0. At nonlimiting cellulosic substrate concentrations (?1%), C. thermocellum cellulase hydrolysis products accumulated during monoculture fermentation of Solka Floc cellulose and included glucose, cellobiose, xylose, and xylobiose. A stable coculture that contained nearly equal numbers of C. thermocellum and C. thermohydrosulfuricum was established that fermented a variety of cellulosic substrates, and the ethanol yield observed was twofold higher than in C. thermocellum monoculture fermentations. The metabolic basis for the enhanced fermentation effectiveness of the coculture on Solka Floc cellulose included: the ability of C. thermocellum cellulase to hydrolyze ?-cellulose and hemicellulose; the enhanced utilization of mono- and disaccharides by C. thermohydrosulfuricum; increased cellulose consumption; threefold increase in the ethanol production rate; and twofold decrease in the acetate production rate. The coculture actively fermented MN300 cellulose, Avicel, Solka Floc, SO2-treated wood, and steam-exploded wood. The highest ethanol yield obtained was 1.8 mol of ethanol per mol of anhydroglucose unit in MN300 cellulose.

Ng, Thomas K.; Ben-Bassat, Arie; Zeikus, J. G.

1981-01-01

296

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.

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

2010-01-01

297

Fluticasone propionate in asthma: a long term dose comparison study  

PubMed Central

Background: Few dose ranging studies have investigated optimal dosing with inhaled corticosteroids in children with asthma. Aims: To compare the efficacy and tolerability of fluticasone propionate 100 or 200 µg twice daily in children with moderate to severe asthma for one year. Methods: One year, randomised, double blind, parallel group, multicentre study. Children aged 4–11 years (n = 528) with moderate to severe asthma who had previously received high dose inhaled corticosteroids were given fluticasone propionate 100 or 200 µg twice daily for the 52 week treatment period. Efficacy (exacerbations, lung function, and symptoms) and tolerability (adverse events and cortisol levels) were measured. Results: There was a non-significant decreased risk of experiencing an exacerbation at any time with fluticasone propionate 200 µg twice daily compared with fluticasone propionate 100 µg twice daily. This difference reached significance among patients with more severe asthma (defined by previous inhaled corticosteroid dose >800 µg/day). Daily record card morning peak expiratory flow (PEF) in the total population improved significantly more with the higher dose of fluticasone propionate (between group difference, weeks 1–52: 11.4 l/min). Clinic visit mean PEF improved from baseline with both doses, but the response was significantly greater with the higher dose (between group difference, week 52: 17.8 l/min). Both doses were equally well tolerated and overnight urinary cortisol concentrations were unchanged or slightly increased during treatment with either dose. Conclusion: This long term dose comparison study shows that treatment with fluticasone propionate 200 µg twice daily may offer benefits over a lower dose, particularly in children with more severe asthma.

Verona, E; Petrov, D; Cserhati, E; Hofman, J; Geppe, N; Medley, H; Hughes, S

2003-01-01

298

Research and Development of New and Improved Cellulose Ester Membranes.  

National Technical Information Service (NTIS)

The goal of the program was the preparation of membranes for demineralizing brackish waters and seawater with a retention of at least 80% of their initial flux after one year of operation. Two membranes, one made from a blend of cellulose acetates and one...

A. J. Secchi C. W. Saltonstall D. L. Hoernschemeyer O. S. Schaeffler

1973-01-01

299

Factors influencing cellulosome activity in Consolidated Bioprocessing of cellulosic ethanol  

Microsoft Academic Search

The cellulosome, a multi-subunit protein complex catalyzing cellulose degradation in cellulolytic Clostridium thermocellum, plays a crucial role in Consolidated Bioprocessing (CBP) of lignocellulose into ethanol. Here, activity of cellulosome was tested under varying concentrations of chemical compounds derived from lignocellulose pretreatment and fermentation. We found that, firstly, the cellulolytic activity of cellulosome was actually promoted by formate, acetate and lactate;

Chenggang Xu; Yong Qin; Yudong Li; Yuetong Ji; Jianzhong Huang; Houhui Song; Jian Xu

2010-01-01

300

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 ...

301

Studies on the cellulolytic bacteria and cellulose degradation in a cattle waste-fed biogas digester  

Microsoft Academic Search

Production of acetate, the key substrate for methane formation in anaerobic digesters, is limiting in cattle waste-fed biogas digesters due to the lignocellulosic nature of the substrate. Since the rate of cellulose hydrolysis affects acetate production, and the number and type of cellulolytic bacteria that exist in a cattle waste biogas digester is not known, 110 cellulolytic bacterial isolates belonging

Pratibha R. Singh; M. K. Jain

1986-01-01

302

Cellulose Biosynthesis in Enterobacteriaceae  

Microsoft Academic Search

Distinct bacterial species belonging to the family of Enterobacteriaceae harbor a characteristic cellulose biosynthesis operon (bcs). A regulatory network for cellulose biosynthesis has been identified in Salmonella typhimurium. Transcription of the bcs operon is constitutive, while cellulose biosynthesis is activated on the post-transcriptional level by AdrA, a GGDEF domain containing protein. AdrA is under the tight positive control of the

Ute Römling

303

ARTICLES: Vapor-Liquid Equilibrium Data of Carbon Dioxide+Methyl Propionate and Carbon Dioxide+Propyl Propionate Systems  

NASA Astrophysics Data System (ADS)

High-pressure vapor-liquid equilibrium data for the binary systems of methyl propionate+carbon dioxide and propyl propionate+carbon dioxide were measured at pressure from 1.00 MPa to 12.00 MPa and temperature in the range from 313 K to 373 K. Experimental results were correlated with the Peng-Robinson equation of state with the two-parameter van der Waals mixing rule. At the same time, the Henry's coefficient, partial molar enthalpy change and partial molar entropy change of CO2 during dissolution at different temperature were also calculated.

Xu, Wei; Xie, Chuan-xin; Li, Hong-ling; Tian, Yi-ling

2010-06-01

304

Propionic acid production by cofermentation of Lactobacillus buchneri and Lactobacillus diolivorans in sourdough  

Microsoft Academic Search

Cooperative metabolism of lactobacilli in silage fermentation converts lactate to propionate. This study aimed to determine whether propionate production by Lactobacillus buchneri and Lactobacillus diolivorans can be applied for bread preservation. Propionate formation was observed in cofermentation with L. buchneri and L. diolivorans in modified MRS broth as well as sourdough with low, medium and high ash contents. 48 mM of propionate

Chonggang Zhang; Markus J. Brandt; Clarissa Schwab; Michael G. Gänzle

2010-01-01

305

Rumen Propionate and Blood Glucose Kinetics in Growing Cattle Fed Isoenergetic Diets1'2  

Microsoft Academic Search

The relationship between rumen propionate production and blood glucose kinetics was examined in four rumen-fistulated Holstein steers fed isoenergetic amounts of 80\\/20 ( G ) and 30\\/70 ( R ) grain\\/chopped alfalfa hay diets at 2-hour intervals. Single-injection rumen propionate and blood glucose kinetics were determined in consecutive 4-hour periods by using (6-3H)glucose intravenously then (1-14C)propionate intraruminally. Rumen propionate specific

JOSEPH H. HERBEIN; RANDALL W. VAN MAANEN; A. DARE McGILLIARD ANDJERRY; W. YOUNG

2009-01-01

306

Proteomic analysis of Salmonella enterica serovar Enteritidis following propionate adaptation  

Microsoft Academic Search

BACKGROUND: Salmonella Enteritidis is a highly prevalent and persistent foodborne pathogen and is therefore a leading cause of nontyphoidal gastrointestinal disease worldwide. A variety of stresses are endured throughout its infection cycle, including high concentrations of propionate (PA) within food processing systems and within the gut of infected hosts. Prolonged PA exposure experienced in such milieus may have a drastic

Leona N Calhoun; Rohana Liyanage; Jackson O Lay Jr; Young Min Kwon

2010-01-01

307

Effect on adrenal function of topically applied clobetasol propionate (Dermovate)  

Microsoft Academic Search

Thirty-nine patients (15 outpatients and 24 inpatients) with a variety of skin diseases affecting variable areas of the body surface were treated with clobetasol propionate ointment (Dermovate). Before and after treatment the adrenal response to an intramuscular injection of tetracosactrin was rested and additional 9 am plasma cortisol levels were measured at intervals during treatment. A satisfactory initial therapeutic response

C F Allenby; R A Main; R A Marsden; C G Sparkes

1975-01-01

308

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

Federal Register 2010, 2011, 2012, 2013

...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

309

The Biosynthesis of Cellulose  

Microsoft Academic Search

Cellulose is one of the major commercial products of Sweden and constitutes the most abundant of the natural polymer systems. Thus, it is of interest to review the molecular design and architecture of cellulose with particular reference to the controls of its biosynthesis. The bioassembly process is highly ordered and structured, reflecting the intricate series of events which must occur

R. Malcolm Brown Jr

1996-01-01

310

Enzymology of cellulose degradation  

Microsoft Academic Search

In the last few years there has been a considerable improvement in the understanding of the mechanisms involved in the microbial degradation of cellulose, but there are still many uncertainties. As presently understood, it would appear that different mechanisms may operate in the various types of microorganism. Thus degradation of crystalline cellulose is effected by anaerobic bacteria by large Ca-dependent

Thomas M. Wood; Vicenta Garcia-Campayo

1990-01-01

311

Cellulose Graft Copolymers  

Microsoft Academic Search

Graft copolymerization reactions of fibrous cellulose with vinyl monomers were initiated at free radical sites formed on the cellulose molecule by interaction with high-energy radiation, by reaction with Ce ions in acidic solution, or by H abstraction by ·OH radicals fromed by reaction of Fe ions with HLOz in aqueous solution. The effects of experimental conditions on the nature, half-lives,

Jett C. Arthur Jr

1970-01-01

312

Experimental feed induction of ruminal lactic, propionic, or butyric acidosis in sheep.  

PubMed

A study was conducted to determine the feasibility to induce rumen acidosis with propionate, butyrate, or lactate as the major fermentation end products. Three rumen-cannulated Texel wethers were used in a 3 x 3 Latin square design. Each period consisted of 11 d of adaptation where wethers were daily fed at 90% of ad libitum intake a hay and wheat-based concentrate diet (4:1 ratio on a DM basis) in 2 equal portions followed by 3 d of acidosis induction. During the challenge, the morning feeding was replaced by an intraruminal supply of wheat (readily fermentable starch), corn (slowly fermentable starch), or beet pulp (easily digestible fiber), dosed at 1.2% of BW. Ruminal liquid samples were taken daily 1 h before (-1) and 1, 3, 5, and 6 h after intraruminal feed supply to measure pH, VFA, and lactic acid concentration. The differences between treatments accentuated throughout the 3-d challenge, being maximal and significant on d 3. Indeed, 6 h after the third day of the challenge, mean ruminal pH was less for wheat (4.85) than for corn (5.61; P = 0.008) and beet pulp (6.09; P = 0.001), and total VFA tended to be less for wheat (48.7 mM) than for corn and beet pulp (84.7 mM on average; P = 0.08). At the same time, the proportion of acetate was greater for wheat than for corn (75.5 and 62.2%, respectively; P = 0.005) but did not differ from beet pulp challenge (69.0%). The proportion of propionate was greatest for beet pulp compared with corn and wheat (21.0, 17.3, and 12.1%, respectively; P = 0.03), whereas the butyrate proportion was greatest for corn, intermediate for wheat, and least for beet pulp (16.3, 10.8, and 8.3%, respectively; P = 0.05). Lactate concentration was greatest for wheat (45.5 mM) compared with corn and beet pulp (8.3 mM on average; P = 0.01). Under our experimental conditions, ruminal lactic acidosis was successfully induced by wheat, whereas butyric and propionic subacute ruminal acidosis were respectively provoked by corn and beet pulp. We developed an original model that promoted differentiated fermentation pathways in the rumen of sheep. It will be used to study the ruminal microbiome changes involved in different acidosis situations. PMID:20495125

Lettat, A; Nozière, P; Silberberg, M; Morgavi, D P; Berger, C; Martin, C

2010-05-21

313

RED Facts: Tridecenyl Acetates.  

National Technical Information Service (NTIS)

This fact sheet summarizes the information in the RED document for reregistration case 4116, tridecenyl acetates. Tridecenyl acetates are sex attractant pheromones used in tomato fields to disrupt the mating behavior of tomato pinworms.

1996-01-01

314

2-O-Methyl- and 3,6-di-O-methyl-cellulose from natural cellulose: synthesis and structure characterization.  

PubMed

For the first time, 2-O-methyl- (2MC) and 3,6-di-O-methyl-cellulose (36MC) were synthesized via 3-O-allyl- and 3-O-methyl-cellulose, respectively. Position 6 of 3-O-allyl- and 3-O-methyl-cellulose was protected with the 4-methoxytrityl groups. The reaction time and temperature were optimized to achieve a high regioselectivity at C-6 and to prevent the introduction of the 4-methoxytrityl group at C-2 of the polymer. It was found that the substituent at C-3 of 3-O-functionalized celluloses influenced the reactivity of the hydroxyl group at C-6. The structure was characterized by means of (1)H and (13)C NMR spectroscopy of the acetates of 2MC and 36MC. 2MC and 36MC were soluble in water and did not show thermoreversible gelation. PMID:22817399

Nakagawa, Atsushi; Ishizu, Chiyo; Sarbova, Velina; Koschella, Andreas; Takano, Toshiyuki; Heinze, Thomas; Kamitakahara, Hiroshi

2012-08-07

315

Comparison between Compliance of Fluticasone Propionate Diskhaler and of Fluticasone Propionate Diskus in Adult Bronchial Asthma Patients  

Microsoft Academic Search

Background and Objectives: Because inhaled corticosteroids (ICS) play a central role in the management of asthma, new drug delivery systems for fluticasone propionate, Diskhaler (FPdh) and Diskus (FPdk), were developed. However, few studies have focused on compliance with these drug delivery systems, which can influence drug efficacy. Hence, we compared compliance with FPdk versus that with FPdh. Methods:Data were obtained

Takashi Hasegawa; Eiichi Suzuki; Katsuya Fujimori; Takuro Sakagami; Shinichi Toyabe; Kouhei Akazawa; Kenji Kawano; Michihiko Haraguchi; Joji Toyama; Masaaki Arakawa; Hiroshi Satoh; Fumitake Gejyo

2006-01-01

316

Propionic and butyric acids, formed in the caecum of rats fed highly fermentable dietary fibre, are reflected in portal and aortic serum.  

PubMed

SCFA are important end products formed during colonic fermentation of dietary fibre (DF). It has been suggested that propionic and butyric acids affect metabolic parameters, low-grade systemic inflammation, insulin resistance and obesity. The aim of the present study was to investigate whether the various SCFA profiles observed after fermentation in the caecum of rats fed pectin, guar gum and fructo-oligosaccharides (FOS) were also represented in hepatic portal and aortic serum. The SCFA in serum were extracted using hollow fibre-supported liquid membrane extraction before GLC analysis. The concentrations of acetic, propionic and butyric acids in caecal content correlated well with those in portal serum (P< 0·001) for all the three diets. A weaker correlation was found for propionic and butyric acids between the caecal content and aortic serum (P< 0·05). Butyric acid concentration in caecal content was also reflected in the aortic serum (P= 0·019) of rats fed FOS. FOS gave rather low amounts of the SCFA, especially butyric acid, but caecal tissue weight was higher with FOS than with the other two diets. This may be explained by rapid fermentation and quick utilisation/absorption of the SCFA. The present study also showed that propionic acid was metabolised/utilised to a higher extent than butyric acid by colonocytes before reaching the liver. We conclude that the formation of propionic and butyric acids in the caecum is reflected by increased concentrations in the aortic blood. This approach may therefore simplify the evaluation and study of SCFA from DF in human subjects. PMID:23531375

Jakobsdottir, Greta; Jädert, Cecilia; Holm, Lena; Nyman, Margareta E

2013-03-26

317

Coordination of Lanthanide Acetates  

SciTech Connect

A study of the structures of hydrated and anhydrous lanthanide acetates by X-ray diffraction, infrared spectra, and absorption spectra demonstrates that there are three separate structures for hydrated lanthanide acetates and four structures for anhydrous acetates. This paper discusses the results of that study.

Karraker, D.G.

2001-08-29

318

Preparation and characterization of fluorinated cellulose material  

NASA Astrophysics Data System (ADS)

Fluorinated derivative of cellulose acetate (CA) was prepared by simple homogeneous esterification reaction using pyridine as catalyst and pentadecafluorooctonyl chloride (PDFOC) as long chain aliphatic acid chloride. The process was optimized by changing the amount of pyridine and PDFOC. Obtained fluoro derivative of CA was freely soluble in common organic solvents such as acetone and THF. Fluorine content in the material was calculated by energy dispersive X-ray spectroscopy analyses and maximum 27.3 wt.% was achieved. X-ray diffraction results showed that fluorination reaction did not change the crystallinity of the CA.

Amalraj, John; Kang, Jin-Ho; Kim, Jaehwan

2011-03-01

319

Enhancement of enzymatic saccharification of cellulose by cellulose dissolution pretreatments  

Microsoft Academic Search

Attempts were made to enhance cellulose saccharification by cellulase using cellulose dissolution as a pretreatment step. Four cellulose dissolution agents, NaOH\\/Urea solution, N-methylmorpholine-N-oxide (NMMO), ionic liquid (1-butyl-3-methylimidazolium chloride; [BMIM]Cl) and 85% phosphoric acid were employed to dissolve cotton cellulose. In comparison with conventional cellulose pretreatment processes, the dissolution pretreatments were operated under a milder condition with temperature <130°C and ambient

Chia-Hung Kuo; Cheng-Kang Lee

2009-01-01

320

Cationic-cellulose nanofibers: preparation and dyeability with anionic reactive dyes for apparel application.  

PubMed

Continuous effort in research and development of nanofibers for apparel usage has been focused within their functional properties only. We investigated esthetic properties by producing colored cationic-cellulose nanofibers for the very first time for the potential application of apparel use. The cellulose acetate nanofibers were electrospun followed by deacetylation and cationization to produce functional cationic-cellulose nanofibers and then dyed with anionic reactive dyes. The spectrophotometric measurement of dyed samples was carried out to determine color coordinates and color yield values. The cationic-cellulose nanofibers showed enhanced color yield and dye fixation without addition of an electrolyte in comparison to cellulose nanofibers. The cationization of cellulose nanofibers significantly enhanced the color yield values of around 76% at dye concentrations of 5%. Excellent color fastness results demonstrate that these new colored and breathable materials can potentially be considered as future apparel for casual or fashion. PMID:23044154

Khatri, Zeeshan; Mayakrishnan, Gopiraman; Hirata, Yuichi; Wei, Kai; Kim, Ick-Soo

2012-08-22

321

Pallidol hexa-acetate ethyl acetate monosolvate  

PubMed Central

The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ?). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?Å) is 54.73?(6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)°]. In the crystal, a three-dimensional architecture is sustained by C—H?O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside.

Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

2013-01-01

322

Carbon partitioning to cellulose synthesis  

Microsoft Academic Search

This article discusses the importance and implications of regulating carbon partitioning to cellulose synthesis, the characteristics of cells that serve as major sinks for cellulose deposition, and enzymes that participate in the conversion of supplied carbon to cellulose. Cotton fibers, which deposit almost pure cellulose into their secondary cell walls, are referred to as a primary model system. For sucrose

Candace H. Haigler; Milka Ivanova-Datcheva; Patrick S. Hogan; Vadim V. Salnikov; Sangjoon Hwang; Kirt Martin; Deborah P. Delmer

2001-01-01

323

Grafting Studies on Cotton Cellulose  

Microsoft Academic Search

Graft copolymerization reactions of vinyl monomers with fibrous cotton cellulose that were initiated at free-radical sites formed on the cellulose molecule are discussed. The effects of experimental conditions on the methods of initiating these free-radical reactions and on the location of these sites on the cellulose molecule are outlined. Some of the properties of the fibrous cellulose graft copolymers are

Jett C. Arthur Jr

1976-01-01

324

Observations on the systemic effect of topical clobetasol propionate (Dermovate)  

Microsoft Academic Search

Topical application of clobetasol propionate in a strength of 0-05% in cream or ointment (Dermovate) suppressed the hypothalamic-pituitary-adrenal axis in both normal people and patients with diseased skin. In normal people the 9 am serum cortisol level was suppressed when between 45 and 90 g was applied weekly. Insulin stress test results in patients with diseased skin showed an abnormally

J A Carruthers; P J August; R C Staughton

1975-01-01

325

Successful Topical Dissolution of Cholesterol Gallbladder Stones Using Ethyl Propionate  

Microsoft Academic Search

Topical dissolution of cholesterol gallbladderstones using methyl tert-butyl ether (MTBE) is useful insymptomatic patients judged too ill for surgery.Previous studies showed that ethyl propionate (EP), a C5 ester, dissolves cholesterolgallstones rapidly in vitro, but differs from MTBE inbeing eliminated so rapidly by the liver that bloodlevels remain undetectable. Our aim was to test EP as atopical dissolution agent for cholesterol

Alan F. Hofmann; Andree Amelsberg; Oliver Esch; Claudio D. Schteingart; Kip Lyche; Horacio Jinich; Eric Vansonnenberg; Horacio B. D'Agostino

1997-01-01

326

The anti-inflammatory profile of fluticasone propionate.  

PubMed

Fluticasone propionate is a new corticosteroid based on the androstane nucleus. It is more lipophilic than beclomethasone dipropionate (BDP) and budesonide, and binds more avidly to human lung tissue. It has an absolute affinity (KD) of 0.5 nM for the glucocorticoid receptor and a relative receptor affinity 1.5- and 3.0-times greater than that of beclomethasone-17-monopropionate (17-BMP) and budesonide, respectively. The rate of association with the receptor is faster and the rate of dissociation slower than with standard corticosteroids. As a result, the half-life of the corticosteroid-receptor complex is > 10 h. Fluticasone propionate is also highly selective for the glucocorticoid receptor, with little or no activity at other steroid receptors. Pretreatment with fluticasone propionate significantly inhibits the increase in mast cell numbers in the nasal mucosa of rats chronically exposed to toluene di-isocyanate (TDI), and suppresses TDI-induced mast cell degranulation. It is more potent in vitro than dexamethasone, BDP and budesonide in inhibiting anti-CD3-induced human T-lymphocyte proliferation, in attenuating tumour necrosis factor-alpha-induced endothelial cell adhesion molecule expression, and in increasing secretory leucocyte protease inhibitor levels in airway epithelial cells. It is also more potent and longer-acting than other corticosteroids in inhibiting oedema formation, interleukin-5 (IL-5)-induced blood eosinophilia, and IL-5- or platelet activating factor-stimulated eosinophil accumulation in the lung. Fluticasone propionate therefore has increased intrinsic glucocorticoid potency and high topical anti-inflammatory activity. PMID:7604948

Johnson, M

1995-01-01

327

Energetics of Sheep Concerned with the Utilization of Acetic Acid1'2  

Microsoft Academic Search

The efficiency of utilization for growth-fattening, of the energy of diets resulting in high (5.4:1) and low (3.1:1) ratios of acetic acid to propionic acid in the ruminai ingesta was determined in 24 intact male and 24 female sheep by means of a slaughter-analysis experiment. To establish the chemical composition and energy value of the body at the beginning of

L. S. BULL; J. T. REID; E. JOHNSON

2010-01-01

328

[Glucocorticoid action of beclomethasone and its propionate ester derivatives].  

PubMed

In the present pharmacokinetic studies on beclomethasone dipropionate in rats, it was suggested that most of the beclomethasone-17, 21dipropionate is transformed rapidly into beclomethasone-17-monopropionate or beclomethasone in the blood or tissues and exerts the glucocorticoid effect in the form of beclomethasone. Glucocorticoid activity of beclomethasone was revealed to be 1-10% that of dexamethasone both in the hypothalamopituitaryadrenocortical suppressive effect and liver tyrosine amino transferase inducing efect in rats. Beclomethasone and its propionate derivatives were shown to have higher binding affinity to glucocorticoid receptors in rat liver, thymus and hypophysis than that of dexamethasone. The experimental results herein may serve to explain why beclomethasone and its propionate derivatives showed such a weak glucocorticoid action in comparison with that of dexamethasone. The amounts of receptor-beclomethasone (or its propionate derivatives) complexes which bound specifically to liver nuclei were only 10% or less than those of receptordexamethasone complexes and the in vivo metabolism of beclomethasone and beclomethasone-dipropionate was more rapid than that of dexamethasone. PMID:16814

Yamamoto, S

1977-01-01

329

Crosslinkable cellulose derivatives  

SciTech Connect

This patent describes a method for treating a subterranean formation. It comprises: preparing a treating fluid composition with or without a particulate agent by admixing an aqueous liquid, a cellulose ether derivative consisting essentially of the reaction product of a cellulose ether with a ceric salt, the reaction occurring under acidic conditions and at a temperature in the range of from about 20{degree} to about 60{degree}C. and a cross-linking agent; and injecting the treating fluid composition into the subterranean formation through a wellbore. This patent also describes a method of treating a subterranean formation. It comprises: preparing a treating fluid composition with or without a particulate agent by admixing an aqueous liquid, a cellulose ether derivative that is chemically modified by reacting under acidic conditions the cellulose ether derivative with a vinyl phosphonic acid and a ceric salt, and a crosslinking agent; and injecting the treating fluid composition into the subterranean formation through a wellbore.

Holtmeyer, M.D.; Hunt, C.V.; Harms, W.M.

1991-01-08

330

Enzymatic Saccharification of Cellulose.  

National Technical Information Service (NTIS)

Studies of the use of certain cellulases and B-glucosidase for the hydrolytic degradation of cellulose are described. Cellulase systems from a bacterium Cellulomonas and a fungus Aspergillus and a B-glucosidase from Alcaligenes faecalis were prepared and ...

V. R. inivasan

1973-01-01

331

Biodegradation of Cellulosic Substrates.  

National Technical Information Service (NTIS)

Mechanisms for accelerated biodegradation of cellulosic substrates have been examined, especially analyses and optimization of pre-treatment of the fiber prior to microbial digestion. Methodology has been developed for enumeration of cellulolytic microorg...

S. P. Meyers

1976-01-01

332

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

333

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

334

Effects of Dietary Inclusion of Chromium Propionate and Calcium Propionate on Glucose Disposal and Gastrointestinal Development in Dairy Calves1  

Microsoft Academic Search

In experiment 1, 21 male Holstein calves (43.9 kg) were fed only milk replacer at 1.4% of their body weight as dry matter for 6 wk. Dietary treatments included a commercial milk replacer (22% protein, 15% fat) con- taining (dry basis) either 6.4% Ca propionate or 6.4% dextrose (control) and either 0 or 0.5 mg\\/kg of supple- mental Cr as

L. D. Bunting; T. A. Tarifa; B. T. Crochet; J. M. Fernandez; C. L. Depew; J. C. Lovejoy

2000-01-01

335

Acetic acid production of Vibrio halioticoli from alginate: a possible role for establishment of abalone– V. halioticoli association  

Microsoft Academic Search

Acetic acid, which is converted from cellulose by means of the metabolism of their gut microbes, is an important oxidizable energy source and precursors of anabolism in ruminant animals and xylophagus insects. However, acetic acid production from algal polysaccharides by means of the metabolism of gut microbes of marine herbivorous invertebrates is not well studied. Abundance of Vibrio halioticoli, which

Tomoo Sawabe; Naka Setoguchi; Sahoko Inoue; Reiji Tanaka; Masashi Ootsubo; Mamoru Yoshimizu; Yoshio Ezura

2003-01-01

336

Determination of carboxymethyl substitution in cellulose ethers by Zeisel reaction and liquid chromatography  

SciTech Connect

A new method has been developed for the determination of the carboxymethyl substitution in cellulose ethers. The carboxymethyl groups are cleaved using hydriodic acid with the formation of acetic acid. The acetic acid is quantitated using A Zorbax C/sub 8/ column with UV detection at 205 nm. Before quantitation, most of the iodide and iodine from the hydriodic acid must be removed due to their interference in the chromatography and detection. With the combination of oxidation and extraction, most of the iodide and iodine is removed. This method is applicable to the determination of carboxymethyl groups in the presence of other cellulose ether substituents. A model compound has shown reaction yields of +97%. The relative precision for 10 determinations at the 95% confidence level for a carboxymethyl cellulose (CMC) and a carboxymethyl hydroxyethyl cellulose (CMHEC) was found to be +/-2.4% and +/-3.0%, respectively. 12 references, 1 figure, 2 tables.

Miller, T.G.; Hronek, R.J.

1985-09-01

337

[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

338

Effect of propionate toxicity on methanogenesis of night soil at phychrophilic temperature.  

PubMed

The effect of propionate concentrations on biodegradation of human waste (night soil) was studied at 10 degrees C. Propionate was toxic for the biomethanation at all the pH tested (6.0, 7.0 and 8.0). The maximum reduction in biogas production in presence of 200 mM propionate was observed at pH 7.0 followed by 8.0. The methane content in biogas also followed a similar trend and at pH 7.0 an 11.5% decrease was observed. Propionate caused the reduction of methanogenic count by an approximately 2log value. Total volatile fatty acids increased with the increase in propionate concentration and particularly accumulation of propionate was observed. The results were also compared with the 30 degrees C fermentation. PMID:12507871

Dhaked, Ram Kumar; Waghmare, Chandra Kant; Alam, Syed Imteyaz; Kamboj, Dev Vrat; Singh, Lokendra

2003-05-01

339

Cellulose Catabolism by Clostridium cellulolyticum Growing in Batch Culture on Defined Medium  

PubMed Central

A reinvestigation of cellulose degradation by Clostridium cellulolyticum in a bioreactor with pH control of the batch culture and using a defined medium was performed. Depending on cellulose concentration, the carbon flow distribution was affected, showing the high flexibility of the metabolism. With less than 6.7 g of cellulose liter?1, acetate, ethanol, H2, and CO2 were the main end products of the fermentation and cellulose degradation reached more than 85% in 5 days. The electron flow from the glycolysis was balanced by the production of H2 and ethanol, the latter increasing with increasing initial cellulose concentration. From 6.7 to 29.1 g of cellulose liter?1, the percentage of cellulose degradation declined; most of the cellulase activity remained on the cellulose fibers, the maximum cell density leveled off, and the carbon flow was reoriented from ethanol to acetate. In addition to that of previously indicated end products, lactate production rose, and, surprisingly enough, pyruvate overflow occurred. Concomitantly the molar growth yield and the energetic yield of the biomass decreased. Growth arrest may be linked to sufficiently high carbon flow, leading to the accumulation of an intracellular inhibitory compound(s), as observed on cellobiose (E. Guedon, M. Desvaux, S. Payot, and H. Petitdemange, Microbiology 145:1831–1838, 1999). These results indicated that bacterial metabolism exhibited on cellobiose was distorted compared to that exhibited on a substrate more closely related to the natural ecosystem of C. cellulolyticum. To overcome growth arrest and to improve degradation at high cellulose concentrations (29.1 g liter?1), a reinoculation mode was evaluated. This procedure resulted in an increase in the maximum dry weight of cells (2,175 mg liter?1), cellulose solubilization (95%), and end product concentrations compared to a classical batch fermentation with a final dry weight of cells of 580 mg liter?1 and 45% cellulose degradation within 18 days.

Desvaux, Mickael; Guedon, Emmanuel; Petitdemange, Henri

2000-01-01

340

Understanding the interactions of cellulose with ionic liquids: a molecular dynamics study.  

PubMed

Ionic liquids (ILs) have recently been demonstrated to be highly effective solvents for the dissolution of cellulose and lignocellulosic biomass. To date, there is no definitive rationale for selecting ionic liquids that are capable of dissolving these biopolymers. In this work, an all-atom force field for the IL 1-ethyl-3-methylimidazolium acetate [C2mim][OAc] was developed and the behavior of cellulose in this IL was examined using molecular dynamics simulations of a series of (1-4) linked beta-d-glucose oligomers with a degree of polymerization n = 5, 6, 10, and 20. Molecular dynamics simulations were also carried out on cellulose oligomers in two common solvents, water and methanol, which are known to precipitate cellulose from IL solutions, to determine the extent and energetics of the interactions between these solvents and the cellulosic oligomers. Thermodynamic properties, such as density and solubility, as well as the two-body solute-solvent interaction energy terms, were calculated. The structural and dynamic behavior of solutions was analyzed and the conformations of cellulose oligomers were compared in ionic liquid and water mixtures. It was found that the interaction energy between the polysaccharide chain and the IL was stronger than that for either water or methanol. In addition to the anion acetate forming strong hydrogen bonds with hydroxyl groups of the cellulose, some of the cations were found to be in close contact with the polysaccharides through hydrophobic interactions. These results support the concept that the cation may play a significant role in the dissolution of cellulose by [C2mim][OAc]. It is also observed that the preferred beta-(1,4)-glycosidic linkage conformation of the cellulose was altered when dissolved in [C2mim][OAc] as compared to that found in crystalline cellulose dispersed in water. To our knowledge, this report is the first theoretical study that addresses the key factors in cellulose dissolution using an ionic liquid. PMID:20218725

Liu, Hanbin; Sale, Kenneth L; Holmes, Bradley M; Simmons, Blake A; Singh, Seema

2010-04-01

341

High resolution affinity chromatography of an anti-steroid antiserum by gradient elution with propionic acid  

Microsoft Academic Search

Chromatographic resolution of polyclonal antibodies is a challenging analytical problem and a successful method may have many applications. We have resolved polyclonal antibodies against testosterone 3-(O-carboxymethyl)oxime on a homologous testosterone-Sepharose matrix by using a ternary gradient system of propionate-1 M propionic acid-2 M propionic acid. Nineteen peaks were detected, sixteen of which were characterized by steroid binding activity and IgG

Chandan K Jana; Esahak Ali

1999-01-01

342

Bacterial cellulose scaffolds and cellulose nanowhiskers for tissue engineering.  

PubMed

As the principle structural polysaccharide in plants, cellulose has been extensively characterized over many decades. In recent years, however, exciting new cellulosic materials have been developed with nanoscale fibrillar structures that have particularly promising applications in the growing field of tissue engineering. The majority of recent studies on cellulose nanomaterials for tissue engineering have employed bacterial cellulose, a material with a profile of properties unique among biomaterials commonly used in tissue engineering scaffolds. In addition, a number of recent studies have explored the biomedical applications of discrete colloidal nanocellulose fibrils known as cellulose nanowhiskers or cellulose nanocrystals. The literature on bacterial cellulose scaffolds for tissue engineering is reviewed, and studies on the biocompatibility of cellulose nanowhiskers and their potential for tissue engineering are discussed. Challenges for future development of these materials and potential future advances are also considered. PMID:23394157

Dugan, James M; Gough, Julie E; Eichhorn, Stephen J

2013-02-01

343

Effective cellulose production by a coculture of Gluconacetobacter xylinus and Lactobacillus mali  

Microsoft Academic Search

A microbial colony that contained a marked amount of cellulose was isolated from vineyard soil. The colony was formed by the associated growth of two bacterial strains: a cellulose-producing acetic acid bacterium (st-60-12) and a lactic acid bacterium (st-20). The 16S rDNA-based taxonomy indicated that st-60-12 belonged to Gluconacetobacter xylinus and st-20 was closely related to Lactobacillus mali. Cocultivation of

Akira Seto; Yu Saito; Mayumi Matsushige; Hiroki Kobayashi; Yasuyuki Sasaki; Naoto Tonouchi; Takayasu Tsuchida; Fumihiro Yoshinaga; Kenji Ueda; Teruhiko Beppu

2006-01-01

344

Cellulose fermentation by a coculture of a mesophilic cellulolytic Clostridium and Clostridium acetobutylicum  

Microsoft Academic Search

A coculture of a mesophilic cellulolytic Clostridium with Clostridium acetobutylicum can yield a direct conversion of cellulose into chemicals. In 13 days 30 g\\/l Solka Floc is degraded and fermented into 14 g\\/l butyric acid, 4 g\\/l acetic acid, 3 g\\/l ethanol, and 1 g\\/l butanol. A four times higher rate of cellulose hydrolysis than in pure culture of the

O. Fond; E. Petitdemange; H. Petitdemange; J. M. Engasser

1983-01-01

345

Layer-by-layer structured polysaccharides film-coated cellulose nanofibrous mats for cell culture  

Microsoft Academic Search

For the first time, a novel fibrous polysaccharide scaffold for cell culture was fabricated by the combination of electrospinning and electrostatic layer-by-layer (LBL) self-assembly technique. Oppositely charged chitosan (CS) and alginate (ALG) in aqueous media were alternatively deposited onto the negatively charged cellulose nanofibrous mats which hydrolyzed from electrospun cellulose acetate mats. The morphology and biocompatibility of the resultant scaffolds

Hongbing Deng; Xue Zhou; Xiaoying Wang; Chunyan Zhang; Bin Ding; Qiuhua Zhang; Yumin Du

2010-01-01

346

Mercerized linters cellulose: characterization and acetylation in N, N-dimethylacetamide\\/lithium chloride  

Microsoft Academic Search

Linters cellulose was subjected to different treatments (mercerization and ionized air) before acetylation with acetic anhydride, in homogeneous medium, using DMAc\\/LiCl as solvent system. Before derivatization, the treated fibres were characterized by Scanning Electron Microscopy, X-ray diffraction, alpha-cellulose content, Inverse Gas Chromatography and viscosimetry. It was shown that except a decrease in the dispersive surface energy, the treatments induced small

Beatriz A. P. Ass; Mohamed N. Belgacem; Elisabete Frollini

2006-01-01

347

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...

348

Method of Obtaining Nonflammable Cellulose Ethers.  

National Technical Information Service (NTIS)

The method is given for obtaining nonflammable cellulose ethers by treating cellulose-containing raw material with phosphorylating agents in an organic solvent at a high temperature. Vinyl cellulose ethers were used as the cellulose-containing raw materia...

A. I. Polyakov V. V. Smagin L. A. Ilina

1970-01-01

349

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.

King, Gary M.

1991-01-01

350

Phylogenetic and functional diversity of propionate-oxidizing bacteria in an anaerobic digester sludge.  

PubMed

The phylogenetic and functional diversity of syntrophic propionate-oxidizing bacteria (POB) present in an anaerobic digester was investigated by microautoradiography combined with fluorescent in situ hybridization (MAR-FISH) that can directly link 16S rRNA phylogeny with in situ metabolic function. The syntrophic POB community in the anaerobic digester sludge consisted of at least four phylogenetic groups: Syntrophobacter, uncultured short rod Smithella (Smithella sp. SR), uncultured long rod Smithella (Smithella sp. LR), and an unidentified group. The activities of these POB groups were dependent on the propionate concentrations. The uncultured Smithella sp. SR accounted for 52-62% of the total active POB under all the propionate concentrations tested (0.5-15 mM). In contrast, uncultured Smithella sp. LR was active only at lower propionate concentrations and became a dominant active POB at 0.5 mM of propionate. Syntrophobacter accounted for 16-31% of the total active POB above 2.5 mM propionate, whereas the active Syntrophobacter population became low (ca. 6%) at 0.5 mM of propionate. The anaerobic digester was operated in a fill and draw mode, resulting in periodical changes in propionate concentration ranging from 0 to 10 mM. These phylogenetically and functionally diverse, to some extent functionally redundant, active POB communities were dynamically responding to the periodical changes in propionate concentration. PMID:17262205

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

2007-01-30

351

Functionalisation and chemical characterisation of cellulose-derived carbon aerogels  

Microsoft Academic Search

A series of nitrogen- and oxygen-functionalised carbon aerogels was produced from a carbon aerogel derived from cellulose acetate. Samples were oxidised by H2O2 or HNO3 and\\/or enriched in nitrogen by reaction with gaseous ammonia or co-heating of the carbon aerogel and melamine. Porosity variations and morphology were monitored using N2 adsorption and helium pycnometry. The surface chemistry was characterised by

Bartosz Grzyb; Claudia Hildenbrand; Sandrine Berthon-Fabry; Dominique Bégin; Nathalie Job; Arnaud Rigacci; Patrick Achard

2010-01-01

352

Gel permeation chromatography of crystalline cellulose from the secondary wall of intact cotton fibers  

SciTech Connect

({sup 14}C)glucose or UDP-({sup 14}C)-glucose incorporation into polysaccharides in cotton fiber during secondary wall formation predominantly labels {beta} 1,3- and {beta} 1,4-glucan. The amount of radioactivity in the individual {beta}-glucans was determined by analyzing the partially methylated alditol acetates from the ({sup 14}C) glucans before and after treatment with Updegraff's acetic-nitric reagent. Hot acetic-nitric hydrolyzes {beta} 1,3-glucan leaving resistant crystalline cellulose. In this research we have determined the mol wt characteristics of the crystalline cellulose polymer synthesized from ({sup 14}C) glucose in intact cotton fibers. The ({sup 14}C)-crystalline cellulose in the secondary wall was isolated using the acetic-nitric reagent, dissolved in a non-degrading solvent of lithium chloride/N,N-dimethylacetamide and separated on columns of Ultrastyragel by gel permeation chromatography. The ({sup 14}C)-crystalline cellulose separates into individual cellulose chains with mol wts of 10{sup 7} to 10{sup 4}. The weight average mol wt (Mw) of the polymer is 710,000. The distribution of the chains within the polymer approximates a normal distribution with 95% of the chains distributed with {plus minus} 2 std dev of the mean typical of other biopolymers.

Greenblatt, G.A.; Kohel, R.J.; Benedict, C.R. (Texas A M Univ., College Station (USA))

1990-05-01

353

Microwave Spectra of Fluorinated Propionic Acids and Their Hydrates  

NASA Astrophysics Data System (ADS)

The microwave spectra of three fluorinated propionic acids, namely pentafluoropropionic acid, 2,2,3,3-tetrafluoropropionic acid, and 2,3,3,3-tetrafluoropropionic acid have been observed and assigned. The spectra of pentafluoropropionic acid and its monohydrate were reported in this meeting last year. The conformational analysis of 2,2,3,3-tetrafluoropropionic acid and 2,3,3,3-tetrafluoropropionic acid will be compared to that of pentafluoropropionic acid. The structures of the three monohydrates will be discussed in terms of hydrogen bonding.

Obenchain, Daniel A.; Grubbs, G. S. Grubbs, Ii; Novick, Stewart E.; Cooke, Stephen A.; Serrato, Agapito Serrato, Iii; Lin, Wei

2013-06-01

354

Pharmacokinetic and pharmacodynamic evaluation of fluticasone propionate after inhaled administration  

Microsoft Academic Search

Objective: To evaluate the pharmacokinetic and systemic pharmacodynamic properties of inhaled fluticasone propionate (FP).\\u000a \\u000a \\u000a \\u000a Methods: Single doses of 0.25, 0.5, 1.0 and 3.0?mg FP were administered to groups of six healthy subjects. Serum concentration profiles\\u000a of FP were monitored over 24?h by means of high-performance liquid chromatography\\/mass spectrometry (HPLC\\/MS–MS). Systemic\\u000a pharmacodynamic effects were evaluated by measuring endogenous serum cortisol and

H. Möllmann; M. Wagner; B. Meibohm; G. Hochhaus; J. Barth; R. Stöckmann; M. Krieg; H. Weisser; C. Falcoz; H. Derendorf

1998-01-01

355

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

356

GRAS Notice 000470: Ethyl cellulose  

Center for Food Safety and Applied Nutrition (CFSAN)

Text Version... Figure 1. Chemical Structure of Ethyl Cellulose ... Given the strong hydrophobic character of ethyl cellulose together with its high molecular mass ... More results from www.fda.gov/downloads/food/ingredientspackaginglabeling

357

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.

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

2011-01-01

358

Crosslinkable cellulose derivatives  

SciTech Connect

This paper reports method of treating a subterranean formation. It comprises: preparing a treating fluid composition with or without a particulate agent by admixing: an aqueous liquid, a cellulose ether derivative that is chemically modified by reacting the cellulose ether derivative with a vinyl phosphonic acid in the presence of the reaction product of hydrogen peroxide and a ferrous salt and a crosslinking agent; and injecting the treating fluid composition into the subterranean formation through a wellbore; injecting the treating fluid composition into the subterranean formation through a wellbore.

Holtmyer, M.; Hunt, C.V.

1991-11-26

359

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

2013-05-07

360

Molecular Weight of Native Cellulose  

Microsoft Academic Search

THE molecular weight of cellulose is of great interest to cellulose chemistry, and many attempts have been made to determine it. The cellulose derivatives, esters and ethers, can in general be dissolved in simple organic solvents, and their molecular weights determined by the osmotic pressure method. It is questionable, however, if the derivatives can be prepared without degradation of the

Nils Gralén

1943-01-01

361

Fragrance material review on ethyl phenyl carbinyl acetate.  

PubMed

A toxicologic and dermatologic review of ethyl phenyl carbinyl acetate when used as a fragrance ingredient is presented. Ethyl phenyl carbinyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for ethyl phenyl carbinyl acetate were evaluated, then summarized, and includes: physical properties; acute toxicity; skin irritation; and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22433983

McGinty, D; Letizia, C S; Api, A M

2012-03-13

362

Fragrance material review on p-isopropylbenzyl acetate.  

PubMed

A toxicologic and dermatologic review of p-isopropylbenzyl acetate when used as a fragrance ingredient is presented. p-Isopropylbenzyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1 to 4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for p-isopropylbenzyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22406560

McGinty, D; Letizia, C S; Api, A M

2012-03-03

363

Fragrance material review on 2,4-dimethylbenzyl acetate.  

PubMed

A toxicologic and dermatologic review of 2,4-dimethylbenzyl acetate when used as a fragrance ingredient is presented. 2,4-Dimethylbenzyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, iso-butyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2,4-dimethylbenzyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414641

McGinty, D; Letizia, C S; Api, A M

2012-03-05

364

Fragrance material review on p-anisyl acetate.  

PubMed

A toxicologic and dermatologic review of p-anisyl acetate when used as a fragrance ingredient is presented. p-Anisyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for p-anisyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22417777

McGinty, D; Letizia, C S; Api, A M

2012-03-06

365

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

366

IR spectrum of cellulose  

Microsoft Academic Search

model the total spectrum in the given region, and the results are compared with the experimental data. The mean square deviation of the fitting contour from the experimental curve is no more than 5%. It is known that the set of properties of the physical structure of cellulose is determined by the possibility of existence of rotamers of hydroxyl and

N. V. Ivanova; E. A. Korolenko; E. V. Korolik; R. G. Zhbankov

1989-01-01

367

Modeling of cellulose crystals  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cotton fibers are single cells, and the substance of the fiber is the secondary cell wall that is nearly pure, microcrystalline cellulose. Normally there is about 5% moisture in cotton fiber, but variations of a few percent make differences as large as 40% in the strength, with more water resulting ...

368

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

369

Acetals and Ketals.  

National Technical Information Service (NTIS)

Thirteen open-chain simple cyclic and spirocyclic acetals and ketals were studied. The synthesis of all the cyclic compounds was accomplished by an alcoholysis reaction. The infrared and proton magnetic resonance spectra were measured and correlated. (Aut...

J. Radell R. E. Rondeau

1970-01-01

370

Sodium Acetate Hand Warmers  

NSDL National Science Digital Library

In this activity, sodium acetate hand warmers are used to introduce learners to supersaturated solutions, crystallization, and exothermic reactions. This activity guide includes background information, extension ideas, and resources.

Johnson, Jill

2006-01-01

371

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

Microsoft Academic Search

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,\\u000a IAA). In contrast, NAA promoted fiber elongation and ovule weight gain, which resulted in larger ovule\\/fiber units. To reach\\u000a these conclusions, fiber and ovule growth parameters were measured and cell wall characteristics were examined

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

2009-01-01

372

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

373

Mixed Culture Pre-Ferments of Lactic and Propionic Acid Bacteria for Baking.  

National Technical Information Service (NTIS)

The main aim of the present work was to develop an optimal lactic and propionic acid bacteria mixed culture pre-ferment with naturally fermented propionic acid in a sufficient quantity to prevent bread molding. For this purpose controlled formation of lac...

P. Javanainen

1993-01-01

374

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

375

Study of producing ethanol from cellulose using Clostridium themocellum  

SciTech Connect

The feasibility of producing ethanol in a continuous system from cellulose using Clostridium themocellum was investigated. This anaerobic and thermophilic bacterium was able to degrade cellulose directly into ethanol with acetic acid, hydrogen, and carbon dioxide as by-products of this fermentation. The fermentation was first carried out in a batch mode to study the effects of buffers, temperature, and agitation on microbial growth and ethanol production. From the compounds used to control pH, sodium bicarbonate had the most preferred effects on generation time and ethanol production. As expected, there was a positive relationship between temperature and growth rate. On the other hand, agitation did not benefit from ethanol production or microbial growth. The possibility of noncompetitive inhibition within such a system was deduced from the calculation of the kinetic constants K/sub m/ and V/sub max/. Continuous fermentations were carried out at 60/sup 0/C and pH 7.0 using 1.5 and 3% pure cellulose as a limiting substrate: The maximum ethanol concentration reached during the 1.5% cellulose fermentation was 0.3%, and 0.9% during the 3% cellulose fermentation. The yield of ethanol was about 0.3 grams per gram of consumed cellulose. The overall yield in both schemes was around 0.45 and 0.75 grams per gram of cellulose degraded. It was concluded that cellulos could be degraded continuously in a system with C. themocellum for production of ethanol. While the continuous system like the batch method is feasible, it may not be promising as yet because of the slow generation time of this microorganism.

Zertuche, L.; Zall, R.R.

1982-01-01

376

Cellulose in Cyanobacteria. Origin of Vascular Plant Cellulose Synthase?  

PubMed Central

Although cellulose biosynthesis among the cyanobacteria has been suggested previously, we present the first conclusive evidence, to our knowledge, of the presence of cellulose in these organisms. Based on the results of x-ray diffraction, electron microscopy of microfibrils, and cellobiohydrolase I-gold labeling, we report the occurrence of cellulose biosynthesis in nine species representing three of the five sections of cyanobacteria. Sequence analysis of the genomes of four cyanobacteria revealed the presence of multiple amino acid sequences bearing the DDD35QXXRW motif conserved in all cellulose synthases. Pairwise alignments demonstrated that CesAs from plants were more similar to putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and Nostoc punctiforme American Type Culture Collection 29133 than any other cellulose synthases in the database. Multiple alignments of putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and N. punctiforme American Type Culture Collection 29133 with the cellulose synthases of other prokaryotes, Arabidopsis, Gossypium hirsutum, Populus alba × Populus tremula, corn (Zea mays), and Dictyostelium discoideum showed that cyanobacteria share an insertion between conserved regions U1 and U2 found previously only in eukaryotic sequences. Furthermore, phylogenetic analysis indicates that the cyanobacterial cellulose synthases share a common branch with CesAs of vascular plants in a manner similar to the relationship observed with cyanobacterial and chloroplast 16s rRNAs, implying endosymbiotic transfer of CesA from cyanobacteria to plants and an ancient origin for cellulose synthase in eukaryotes.

Nobles, David R.; Romanovicz, Dwight K.; Brown, R. Malcolm

2001-01-01

377

[beta]-Glucan Synthesis in the Cotton Fiber (IV. In Vitro Assembly of the Cellulose I Allomorph).  

PubMed Central

In vitro assembly of cellulose from plasma membrane extracts of the cotton (Gossypium hirsutum) fiber was enriched by a combination of 3-(N-morpholino)propanesulfonic acid extraction buffer and two independent digitonin solubilization steps consisting of 0.05% digitonin (SE1) followed by 1% digitonin (SE2). Glucan synthase activity assays revealed that, although the SE2 fraction possessed higher activity, only 8.6% of the in vitro product survived acetic/nitric acid treatment. On the other hand, the SE1 fraction was less active, but 32.1% of the total glucan in vitro product was resistant to acetic/nitric acid. In vitro products synthesized from the SE1 fraction contained [beta]-1,3-glucan and fibrillar cellulose I, whereas the SE2 fraction produced [beta]-1,3-glucan and cellulose II. Both celluloses assembled in vitro were labeled with cellobiohydrolase I-gold complex, and the electron diffraction patterns of both products from SE1 and SE2 revealed cellulose I and cellulose II, respectively. Contamination of native cellulose was ruled out by extensive evidence from autoradiography of the ethanol-insoluble and acetic/nitric acid-insoluble materials, including three different controls.

Kudlicka, K.; Brown, R. M.; Li, L.; Lee, J. H.; Shin, H.; Kuga, S.

1995-01-01

378

[beta]-Glucan Synthesis in the Cotton Fiber (IV. In Vitro Assembly of the Cellulose I Allomorph).  

PubMed

In vitro assembly of cellulose from plasma membrane extracts of the cotton (Gossypium hirsutum) fiber was enriched by a combination of 3-(N-morpholino)propanesulfonic acid extraction buffer and two independent digitonin solubilization steps consisting of 0.05% digitonin (SE1) followed by 1% digitonin (SE2). Glucan synthase activity assays revealed that, although the SE2 fraction possessed higher activity, only 8.6% of the in vitro product survived acetic/nitric acid treatment. On the other hand, the SE1 fraction was less active, but 32.1% of the total glucan in vitro product was resistant to acetic/nitric acid. In vitro products synthesized from the SE1 fraction contained [beta]-1,3-glucan and fibrillar cellulose I, whereas the SE2 fraction produced [beta]-1,3-glucan and cellulose II. Both celluloses assembled in vitro were labeled with cellobiohydrolase I-gold complex, and the electron diffraction patterns of both products from SE1 and SE2 revealed cellulose I and cellulose II, respectively. Contamination of native cellulose was ruled out by extensive evidence from autoradiography of the ethanol-insoluble and acetic/nitric acid-insoluble materials, including three different controls. PMID:12228346

Kudlicka, K.; Brown, R. M.; Li, L.; Lee, J. H.; Shin, H.; Kuga, S.

1995-01-01

379

Ethanol production by thermophilic bacteria: fermentation of cellulosic substrates by cocultures of Clostridium thermocellum and Clostridium thermohydrosulfuricum  

SciTech Connect

The fermentation of various saccharides derived from cellulosic biomass to ethanol was examined in mono- and cocultures of Clostridium thermocellum strain LQRI and C. thermohydrosulfuricum strain 39E. C. thermohydrosulfuricum fermented glucose, cellobiose, and xylose, but not cellulose or xylan, and yielded ethanol/acetate ratios of >7.0 C. thermocellum fermented a variety of cellulosic substrates, glucose, and cellobiose, but not xylan or xylose, and yielded ethanol/acetate ratios of approx. 1.0. A stable coculture that contained nearly equal numbers of C. thermocellum and C. thermohydrosulfuricum was established that fermented a variety of cellulosic substrates, and the ethanol yield observed was twofold higher than in C. thermocellum monoculture fermentations. The metabolic basis for the enhanced fermentation effectiveness of the coculture on Solka Floc cellulose included: the ability of C. thermocellum cellulase to hydrolyze ..cap alpha..-cellulose and hemicellulose; the enhanced utilization of mono- and disaccharides by C. thermohydrosulfuricum; increased cellulose consumption; threefold increase in the ethanol production rate; and twofold decrease in the acetate production rate.

Ng, T.K.; Ben-Bassat, A.; Zeikus, J.G.

1981-06-01

380

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

2012-05-11

381

Survival of a Salmonella typhimuriumPoultry Isolate in the Presence of Propionic Acid under Aerobic and Anaerobic Conditions  

Microsoft Academic Search

Propionic acid is commonly found as a fermentation product in the gastrointestinal tracts of food animals and has also been used to limit the microbial contaminants in animal feeds. Because propionic acid is known to have antibacterial activity, the propionic acid encountered by foodborne pathogens during their life cycles may play an important role in inhibiting the survival of the

Y. M. Kwon; S. C. Ricke

1998-01-01

382

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)

1998-02-20

383

Fractionation of wheat straw by atmospheric acetic acid process.  

PubMed

Fractionation of wheat straw was investigated using an atmospheric acetic acid process. Under the typical conditions of 90% (v/v) aqueous AcOH, 4% H(2)SO(4) (w/w, on straw), ratio of liquor to straw (L/S) 10 (v/w), pulping temperature 105 degrees C, and pulping time 3h, wheat straw was fractionated to pulp (cellulose), lignin and monosaccharides mainly from hemicellulose with yields of approximately 50%, 15% and 35%, respectively. Acetic acid pulp from the straw had an acceptable strength for paper and could be bleached to a high brightness over 85% with a short bleaching sequence. Acetic acid pulp was also a potential feedstock for fuels and chemicals. The acetic acid process separated pentose and hexose in wheat straw to a large extent. Most of the pentose (xylan) was dissolved, whereas the hexose (glucan) remained in the pulp. Approximately 30% of carbohydrates in wheat straw were hydrolyzed to monosaccharides during acetic acid pulping, of which xylose accounted for 70% and glucose for 12%. The acetic acid lignin from wheat straw showed relatively lower molecular weight and fusibility, which made the lignin a promising raw material for many products, such as adhesive and molded products. PMID:15734313

Pan, Xuejun; Sano, Yoshihiro

2004-12-19

384

Microbiology and physiology of anaerobic fermentations of cellulose. Progress report, September 1982March 1983  

Microsoft Academic Search

Research progress for the period September 1982-March 1983 is reported. The cellulose enzyme system of the anaerobic thermophile Clostridium thermocellum is being studied. Mutants have been obtained from thermoanaerobacter ethanolicus which produce higher amounts of ethanol than does the wild type. Clostridium thermoautotrophicum has been studied with respect to the pathway of acetate synthesis from COâ. Progress has been achieved

H. D. Jr. Peck; L. G. Ljungdahl

1983-01-01

385

Self-organization and electrooptical characteristics of a nematic liquid crystal-cellulose diacetate composite  

NASA Astrophysics Data System (ADS)

Stable self-organization process has been observed during the formation of thin films of a composite based on a nematic liquid crystal and a cellulose acetate polymer matrix. Optical transmission characteristics and electrooptical response time of the composite have been theoretically calculated and experimentally studied.

Sadovoy, A. V.; Shipovskaya, A. B.; Nazvanov, V. F.

2008-12-01

386

Miscibility studies of the blends of chitosan with some cellulose ethers  

Microsoft Academic Search

The polymeric films have been prepared based on blends of chitosan with two cellulose ethers—hydroxypropylmethylcellulose and methylcellulose by casting from acetic acid solutions. The films were transparent and brittle in a dry state but an immersion of the samples in deionized water for over 24h leads to their disintegration or partial dissolution. The miscibility of the polymers in the blends

Jingbo Yin; Kun Luo; Xuesi Chen; Vitaliy V. Khutoryanskiy

2006-01-01

387

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

388

21 CFR 172.870 - Hydroxypropyl cellulose.  

Code of Federal Regulations, 2010 CFR

...The food additive hydroxypropyl cellulose may be safely used in food...of the following: (1) A cellulose ether containing propylene glycol groups...solution at 25 °C. (2) A cellulose ether containing propylene glycol...

2010-01-01

389

21 CFR 172.870 - Hydroxypropyl cellulose.  

Code of Federal Regulations, 2010 CFR

...The food additive hydroxypropyl cellulose may be safely used in food...of the following: (1) A cellulose ether containing propylene glycol groups...solution at 25 °C. (2) A cellulose ether containing propylene glycol...

2009-04-01

390

21 CFR 172.868 - Ethyl cellulose.  

Code of Federal Regulations, 2013 CFR

...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...conditions: (a) The food additive is a cellulose ether containing ethoxy (OC2 H5 ) groups...

2013-04-01

391

21 CFR 172.868 - Ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...conditions: (a) The food additive is a cellulose ether containing ethoxy (OC2 H5 ) groups...

2010-01-01

392

21 CFR 172.870 - Hydroxypropyl cellulose.  

Code of Federal Regulations, 2013 CFR

...The food additive hydroxypropyl cellulose may be safely used in food...of the following: (1) A cellulose ether containing propylene glycol groups...solution at 25 degrees C. (2) A cellulose ether containing propylene glycol...

2013-04-01

393

21 CFR 172.868 - Ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...conditions: (a) The food additive is a cellulose ether containing ethoxy (OC2 H5 ) groups...

2009-04-01

394

21 CFR 573.420 - Ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance...conditions: (a) The food additive is a cellulose ether containing ethoxy (OC2 H5 ) groups...

2009-04-01

395

21 CFR 573.420 - Ethyl cellulose.  

Code of Federal Regulations, 2013 CFR

...Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance...conditions: (a) The food additive is a cellulose ether containing ethoxy (OC2 H5 ) groups...

2013-04-01

396

Simultaneous saccharification and fermentation of cellulose to lactic acid.  

PubMed

Recent interest in the industrial manufacture of ethanol and other organic chemicals from biomass has led to the utilization of surplus grain and cane juice as a fermentation feedstock. Since those starting materials are also foods, they are expensive. As an alternative, cellulosic substances-the most abundant renewable resources on earth(1)-have long been considered for conversion to readily utilizable hydrolyzates.(2, 3)For the production of ethanol from cellulose, we have proposed the simultaneous saccharification and fermentation (SSF) process.(4) In SSF, enzymatic cellulose hydrolysis and glucose fermentation to ethanol by yeast proceed simultaneously within one vessel. The process advantages-reduced reactor volume and faster saccharification rates-have been confirmed by many researchers.(5-8) During SSF, the faster saccharification rates result because the glucose product is immediately removed, considerably diminishing its inhibitory effect on the cellulase system.(9)To effectively apply the SSF method to produce substances fermented from glucose, several conditions should be satisfied. One is coincident enzymatic hydrolysis and fermentation conditions, such as pH and temperature. The other is that cellulase inhibition by the final product is less than that by glucose and/or cellobiose. One of us has reported that acetic acid, citric acid, itaconic acid, alpha-ketoglutaric acid, lactic acid, and succinic acid scarcely inhibit cellulase.(10) This suggests that if the microorganisms which produce these organic acids were compatible with cellulase reaction conditions, the organic acids could be produced efficiently from cellulosic substrates by SSF.In this article, the successful application of SSF to lactic acid production from cellulose is reported. Though there have been several reports of direct cellulose conversion to organic acids by anaerobes such as Clostridium, only trace amounts of lactic acid were detected in the fermentation medium among the low-molecular-weight fatty acid components.(11-13) Lactic acid is one of the most important organic acids and has a wide range of food-related and industrial applications. PMID:18597311

Abe, S; Takagi, M

1991-01-01

397

Genome-wide overexpression screen for sodium acetate resistance in Saccharomyces cerevisiae.  

PubMed

The production of biofuels from cellulosic biomass is a promising technology for developing a renewable source of energy. Efforts to produce ethanol from cellulosic biomass using microbes, such as the yeast Saccharomyces cerevisiae, face major challenges, including the need for detoxification. Here, we apply a strategy to discover genetic alterations that lead to improved robustness of S. cerevisiae in the presence of acetate, which is present at toxic concentrations in hemicellulose hydrolysates. Acetate in its protonated form (acetic acid) enters the cell through passive diffusion and dissociates into a proton and acetate, acidifying the cytosol and inhibiting cell function, an effect that is exacerbated in the presence of sodium. Through flow cytometry analysis, implemented as part of a novel cell culture technique, the Cytostat, we characterized the deleterious effects of sodium acetate on growth and on cell size homeostasis. Further, using the Cytostat to screen a genome-wide, gene overexpression library, we identified that overexpressing the ENA2 gene, a P-type sodium pump ATPase, provides a significant growth improvement in the presence of sodium acetate. Together, our data support the proposed mechanism for the synergistic growth inhibition exerted by acetate and sodium, as well as the mechanism that develops resistance. PMID:23262128

Peña, Pedro V; Glasker, Steven; Srienc, Friedrich

2012-12-20

398

Synthesis and characterization of Eu(III) complexes of modified cellulose and poly(N-isopropylacrylamide).  

PubMed

A series of thermo-responsive copolymers of poly(N-isopropylacrylamide) (PNIPAM) and cellulose were synthesized via atom transfer radical polymerization (ATRP) using N-isopropylacrylamide as the monomer, cellulose acetate as the initiator, and CuCl/tris(2-dimethylaminoethyl)amine (Me6TREN) as a catalytic system. The resulting polymers had a narrow range of polydispersity indexes 1.27-1.37, and molecular weights of 8600-17,300 g mol(-1). Novel functional complexes of cellulose-g-PNIPAM/Eu(III) with excellent thermosensitive and fluorescent properties were then formed by the chelation of copolymers and europium(III) ions. The maximum emission intensity of the complexes at 613 nm was enhanced by a factor of approximately 10 relative to that of the corresponding Eu(III) complexes. Additionally, the lower critical solution temperatures (LCSTs) of cellulose-g-PNIPAM/Eu(III) were slightly greater than those of the copolymers. PMID:23544512

Cui, Guihua; Li, Yanhui; Shi, Tiantian; Gao, Zhengguo; Qiu, Nannan; Satoh, Toshifumi; Kakuchi, Toyoji; Duan, Qian

2013-01-25

399

Development of Cellulosic Biofuels  

ScienceCinema

Chris Somerville, Director of the Energy Biosciences Institute and an award-winning plant biochemist with Berkeley Lab's Physical Biosciences Division, is a leading authority on the structure and function of plant cell walls. He discusses an overview of some of the technical challenges associated with the production of cellulosic biofuels, which will require an improved understanding of a diverse range of topics in fields such as agronomy, chemical engineering, microbiology, structural biology, genomics, environmental sciences, and socioeconomics. His talk was presented June 20, 2007.

400

Competition between acetate and oleate for the formation of malonyl-CoA and mitochondrial acetyl-CoA in the perfused rat heart  

PubMed Central

We previously showed that in the perfused rat heart, the capacity of n-fatty acids to generate mitochondrial acetyl-CoA decreases as their chain length increases. In the present study, we investigated whether the oxidation of a long-chain fatty acid, oleate, is inhibited by short-chain fatty acids, acetate or propionate (which do and do not generate mitochondrial acetyl-CoA, respectively). We perfused rat hearts with buffer containing 4 mM glucose, 0.2 mM pyruvate, 1 mM lactate, and various concentrations of either (i) [U-13C]acetate, (ii) [U-13C]acetate plus [1-13C]oleate, or (iii) unlabeled propionate plus [1-13C]oleate. Using mass isotopomer analysis, we determined the contributions of the labeled substrates to the acetyl moiety of citrate (a probe of mitochondrial acetyl-CoA) and to malonyl-CoA. We found that acetate, even at low concentration, markedly inhibits the oxidation of [1-13C]oleate in the heart, without change in malonyl-CoA concentration. We also found that propionate, at a concentration higher than 1 mM, decreases (i) the contribution of [1-13C]oleate to mitochondrial acetyl-CoA, and (ii) malonyl-CoA concentration. The inhibition by acetate or propionate of acetyl-CoA production from oleate probably results from a competition for mitochondrial CoA between the CoA-utilizing enzymes.

Bian, Fang; Kasumov, Takhar; Jobbins, Kathryn A.; Minkler, Paul E.; Anderson, Vernon E.; Kerner, Janos; Hoppel, Charles L.; Brunengraber, Henri

2007-01-01

401

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.

2013-01-01

402

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

2013-10-11

403

Cushing's syndrome and pituitary-adrenal suppression due to clobetasol propionate  

Microsoft Academic Search

Widespread application of clobetasol propionate resulted in suppression of the hypothalamic pituitary axis in four patients. Three patients showed Cushigoid features and developed symptoms of adrenocortical insufficiency on withdrawal of clobetasol.

R C Staughton; P J August

1975-01-01

404

Pancreatic Amylase, Plasma Glucose, and Insulin Responses to Propionate or Monensin in Sheep1  

Microsoft Academic Search

Yearling wethers fitted with reentrant bile-pancreatic duct cannulae were in a two-part study of effects of duodenal propionate infusions or increased ruminaI propionate caused by dietary monensin on pancreatic a-amylase secretion and glucose and insulin in blood plasma. Continuous duodenal infusion of propi- onate increased concentrations of glucose and insulin in blood plasma of wethers fed alfalfa. Results supported a

D. D. Johnson; G. E. Mitchell; R. E. Tucker; R. B. Muntifering

1986-01-01

405

[Sensitivity of Sherman's propionic acid bacilli to antibacterial preparations and vitamin B12 synthesis].  

PubMed

Sherman propionic acid bacilli were sensitive to benzylpenicillin, ampicillin, ceporin, tetracyclines, oleandomycin, oletetrin, tetraolean, sigmamycin, levomycetin and furadonine. Methicillin, oxacillin, monomycin, kanamycin, polymyxin and furazolidone had an insignificant effect on the above organism. The subbacteriostatic concentrations of methicillin, oxacillin, streptomycin, monomycin, kanamycin, neomycin, tetraolean, sigmamycin, polymyxin M and ristomycin increased the biosynthesis of vitamin B12 by Sherman propionic acid bacilli, while benzylpenicillin, ampicillin, tetracyclines, oleandomycin, oletetrin, levomycetin and furadonine in the subbacteriostatic concentrations inhibited this process. PMID:596839

Sidorchuk, I I

1977-11-01

406

Monitoring and control of the biogas process based on propionate concentration using online VFA measurement  

Microsoft Academic Search

Simple logic control algorithms were tested for automatic control of a lab-scale CSTR manure digester. Using an online VFA monitoring system, propionate concentration in the reactor was used as parameter for control of the biogas process. The propionate concentration was kept below a threshold of 10 mM by manipulating the feed flow. Other online parameters such as pH, biogas production,

Kanokwan Boe; Irini Angelidaki; Jean-Philippe Steyer

2008-01-01

407

Clobetasol propionate 0.05% under occlusion in the treatment of alopecia totalis\\/universalis  

Microsoft Academic Search

Background: Efficacy of topical steroids in alopecia areata is still discussed. Objective: The purpose of this study was to evaluate the efficacy of clobetasol propionate 0.05% ointment under occlusion in 28 patients with alopecia areata totalis (AT) or AT\\/alopecia universalis. Methods: A total of 28 patients were instructed to apply 2.5 g of clobetasol propionate to the right side of

Antonella Tosti; Bianca Maria Piraccini; Massimiliano Pazzaglia; Colombina Vincenzi

2003-01-01

408

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

409

Steroid-Induced Dermal Thinning: Discontinuous Application of Clobetasol-17Propionate Ointment  

Microsoft Academic Search

The skin thinning effect of discontinuous topical clobetasol-17-propionate applications was tested in human volunteers. Application frequencies were daily (1\\/0), every third day (1\\/2), every fifth day (1\\/4), every seventh day (1\\/6) and every ninth day (1\\/8). Clobetasol-17-propionate was administered topically under occlusion for 1 h. The treatment period was 41 days. There were no differences of the skin thinning effect

D. Lubach; J. Rath; M. Kietzmann

1992-01-01

410

Case report: birth of healthy twins after preimplantation genetic diagnosis of propionic acidemia  

Microsoft Academic Search

Purpose  Development of an ad hoc protocol for the preimplantion genetic diagnosis of propionic acidemia in a couple carrying the mutations c.737G>T (G246V)\\u000a and c.1218del14ins12 (ins\\/del) in the PCCB gene. Propionic acidemia is an autosomal recessive metabolic disorder where the body is unable to process certain parts of\\u000a proteins and lipids. Symptoms manifest few days after birth and sometimes progress to

Trinitat M. Alberola; Rosa Bautista-Llácer; Xavier Vendrell; Elena García-Mengual; Merche Pardo; Maria Vila; Carmen Calatayud

2011-01-01

411

Oxime Acetates: Substrates for Acetylcholinesterase.  

National Technical Information Service (NTIS)

Oxime acetates function as typical substrates for acetylcholinesterase (AChE). Both syn 3- and syn 4-PAM acetates are rapidly hydrolyzed. Both are highly water soluble and give large changes in molar absorbance upon hydrolysis. Hence, they have potential ...

G. M. Steinberg J. P. Maddox L. J. Szafraniec L. M. Berkowitz N. C. Thomas

1971-01-01

412

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

413

Proteomic analysis of Salmonella enterica serovar Enteritidis following propionate adaptation  

PubMed Central

Background Salmonella Enteritidis is a highly prevalent and persistent foodborne pathogen and is therefore a leading cause of nontyphoidal gastrointestinal disease worldwide. A variety of stresses are endured throughout its infection cycle, including high concentrations of propionate (PA) within food processing systems and within the gut of infected hosts. Prolonged PA exposure experienced in such milieus may have a drastic effect on the proteome of Salmonella Enteritidis subjected to this stress. Results In this study, we used 2 D gel electrophoresis to examine the proteomes of PA adapted and unadapted S. Enteritidis and have identified five proteins that are upregulated in PA adapted cultures using standard peptide mass fingerprinting by MALDI-TOF-MS and sequencing by MALDI LIFT-TOF/TOF tandem mass spectrometry. Of these five, two significant stress-related proteins (Dps and CpxR) were shown (via qRT-PCR analysis) to be upregulated at the transcriptional level as well. Unlike the wild type when adapted to PA (which demonstrates significant acid resistance), PA adapted S. Enteritidis ?dps and S. Enteritidis ?cpxR were at a clear disadvantage when challenged to a highly acidic environment. However, we found the acid resistance to be fully restorable after genetic complementation. Conclusions This work reveals a significant difference in the proteomes of PA adapted and unadapted S. Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.

2010-01-01

414

Successful topical dissolution of cholesterol gallbladder stones using ethyl propionate.  

PubMed

Topical dissolution of cholesterol gallbladder stones using methyl tert-butyl ether (MTBE) is useful in symptomatic patients judged too ill for surgery. Previous studies showed that ethyl propionate (EP), a C5 ester, dissolves cholesterol gallstones rapidly in vitro, but differs from MTBE in being eliminated so rapidly by the liver that blood levels remain undetectable. Our aim was to test EP as a topical dissolution agent for cholesterol gallbladder stones. Five high-risk patients underwent topical dissolution of gallbladder stones by EP. In three patients, the solvent was instilled via a cholecystostomy tube placed previously to treat acute cholecystitis; in two patients, a percutaneous transhepatic catheter was placed in the gallbladder electively. Gallstone dissolution was assessed by chromatography, by gravimetry, and by catheter cholecystography. Total dissolution of gallstones was obtained in four patients after 6-10 hr of lavage; in the fifth patient, partial gallstone dissolution facilitated basketing of the stones. In two patients, cholesterol dissolution was measured and averaged 30 mg/min. Side effects were limited to one episode of transient hypotension and pain at the infusion site; no patient developed somnolence or nausea. Gallstone elimination was associated with relief of symptoms. EP is an acceptable alternative to MTBE for topical dissolution of cholesterol gallbladder stones in high-risk patients. The lower volatility and rapid hepatic extraction of EP suggest that it may be preferable to MTBE in this investigational procedure. PMID:9201095

Hofmann, A F; Amelsberg, A; Esch, O; Schteingart, C D; Lyche, K; Jinich, H; Vansonnenberg, E; D'Agostino, H B

1997-06-01

415

Binding kinetics of fluticasone propionate to the human glucocorticoid receptor.  

PubMed

Receptor-ligand interactions of fluticasone propionate (FP), a glucocorticoid used for inhalation therapy, were determined and compared with dexamethasone, budesonide, and beclomethasone-17-monopropionate, the active metabolite of beclomethasone dipropionate. Two approaches, evaluation of binding kinetics and competition assays, were applied to obtain relative receptor affinities (RRAs) with dexamethasone as reference. A higher association rate constant and a distinctly lower dissociation rate constant for FP compared with the other glucocorticoids resulted in an equilibrium dissociation constant (Kd) of 0.49 nmol/l. Kd dexamethasone was 9.36 nmol/l; derived RRA of FP was 1910. The calculated half-time of the FP-receptor complex was 10 h, thus exceeding the half-times of all other glucocorticoids as well as their RRAs. Competition assays clearly confirmed the rank order of the tested glucocorticoids, although RRAs were generally lower than those found in kinetic assays and strongly dependent on the assay conditions. The high receptor affinity of FP is reflected by clinical trials demonstrating its superiority to other glucocorticoids. For therapeutic application, the long half-time of the FP-receptor complex should support the practicality of longer dose-intervals. PMID:7878687

Högger, P; Rohdewald, P

1994-10-01

416

Decomposition of beclomethasone propionate esters in human plasma.  

PubMed

The kinetics of decomposition of beclomethasone dipropionate (BDP), the 17-monopropionate ester (17-BMP), and beclomethasone (BOH) were characterized in whole human plasma (HP), pH 7.1, and in solutions of 1% human serum albumin (HSA), pH 7.4, and 0.067 M phosphate buffer, pH 7.4 (mu = 0.17). A reversed-phase, high-performance liquid chromatography (HPLC) assay enabled simultaneous separation and quantification of beclomethasone propionate esters and six degradation products including three unidentified products, D1-D3, not previously reported. Following incubation of BDP, products were formed in the following sequence, D1, 17-BMP, beclomethasone-21-monopropionate (21-BMP), D3, BOH, and D2. Following incubation of 17-BMP, the same sequence of degradation products was formed with the exception of D1. Following incubation of BOH, only D2 was formed. The decomposition reactions of BDP, 17-BMP, and BOH in HP exhibit pseudo-first-order kinetics. However the degradation reactions of BDP in solutions of 1% HSA and phosphate buffer were found to follow pseudo-zero-order kinetics. At an initial concentration of 40 micrograms mL-1, the half-lives for BDP, 17-BMP, and BOH in HP were 10.9 +/- 0.4, 3.0 +/- 0.2 and 24.8 +/- 0.2 h, respectively. PMID:9510979

Foe, K; Brown, K F; Seale, J P

1998-01-01

417

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

418

Solid acid-catalyzed cellulose hydrolysis monitored by in situ ATR-IR spectroscopy.  

PubMed

The solid acid-catalyzed hydrolysis of cellulose was studied under elevated temperatures and autogenous pressures using in situ ATR-IR spectroscopy. Standards of cellulose and pure reaction products, which include glucose, fructose, hydroxymethylfurfural (HMF), levulinic acid (LA), formic acid, and other compounds, were measured in water under ambient and elevated temperatures. A combination of spectroscopic and HPLC analysis revealed that the cellulose hydrolysis proceeds first through the disruption of the glycosidic linkages of cellulose to form smaller cellulose molecules, which are readily observed by their distinctive C-O vibrational stretches. The continued disruption of the linkages in these oligomers eventually results in the formation and accumulation of monomeric glucose. The solid-acid catalyst accelerated the isomerization of glucose to fructose, which then rapidly reacted under hydrothermal conditions to form degradation products, which included HMF, LA, formic acid, and acetic acid. The formation of these species could be suppressed by decreasing the residence time of glucose in the reactor, reaction temperature, and contact with the metal reactor. The hydrolysis of regenerated cellulose proceeded faster and under milder conditions than microcrystalline cellulose, which resulted in increased glucose yield and selectivity. PMID:22315193

Zakzeski, Joseph; Grisel, Ruud J H; Smit, Arjan T; Weckhuysen, Bert M

2012-02-07

419

Kallolide A acetate pyrazoline  

PubMed Central

In the crystal structure of kallolide A acetate pyrazoline [systematic name: 7-methyl-16-oxo-4,10-bis­(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza­tetra­cyclo­[9.4.2.16,9.01,12]octa­deca-6,8,14-trien-5-yl acetate], C23H28N2O5, there is a 12-member­ed carbon macrocyclic structure. In addition, there is a tris­ubstituted furan ring, an approximately planar ?-lactone ring [maximum deviation of 0.057?(3)?Å] and a pyraz­oline ring, the latter in an envelope conformation. The pyrazoline and the ?-lactone rings are fused in a cis configuration. In the crystal, mol­ecules are linked by weak C—H?O inter­actions, forming a two-dimensional network parallel to (001). An intra­molecular C—H?O hydrogen bond is also present.

Rodriguez-Escudero, Idaliz; Marrero, Jeffrey; Rodriguez, Abimael D.

2012-01-01

420

Synthesis, absolute configuration and biological activities of both enantiomers of 2-(5,7-Dichloro-3-indolyl)propionic acid: a novel dichloroindole auxin and antiauxin.  

PubMed

Racemic 2-(5,7-dichloro-3-indolyl)propionic acid (5,7-Cl(2)-2-IPA) was synthesized from 5,7-dichloroindole-3-acetic acid by successive esterification, methoxycarbonylation, methylation, and double hydrolysis. The racemate was converted to diastereomeric esters of l-menthol; these were separated by recycling HPLC into two optically active diastereomers that were then hydrolyzed with p-TsOH to two optically active enantiomers of 5,7-Cl(2)-2-IPA. The absolute configurations of both these enantiomers were determined by comparing the (1)H-NMR spectra of their diastereomeric l-menthyl esters with those of the diastereomeric l-menthyl esters of 2-(3-indolyl)propionic acid (2-IPA) of known absolute configurations.An assay by the coleoptile elongation of Avena sativa showed the (S)-(+)-enantiomer of 5,7-Cl(2)-2-IPA to have weak auxin activity, whereas the (R)-(-)-antipode had no auxin activity at any concentration tested. Interestingly, the (R)-(-)-enantiomer had antiauxin activity very close to that of 2-(5,7-dichloro-3-indolyl)isobutyric acid (5,7-Cl(2)-IIBA), a strong antiauxin. These data indicate that, of the two methyl groups in its molecule, the antiauxin activity of 5,7-Cl(2)-IIBA was due only to the (R)-methyl group. PMID:15215593

Katayama, Masato; Kato, Yasuhito; Marumo, Shingo

2004-06-01

421

Complete Oxidation of Propionate, Valerate, Succinate, and Other Organic Compounds by Newly Isolated Types of Marine, Anaerobic, Mesophilic, Gram-Negative, Sulfur-Reducing Eubacteria  

PubMed Central

Anaerobic enrichment cultures with either propionate, succinate, lactate, or valerate and elemental sulfur and inocula from shallow marine or deep-sea sediments were dominated by rod-shaped motile bacteria after three transfers. By application of deep-agar dilutions, five eubacterial strains were obtained in pure culture and designated Kyprop, Gyprop, Kysw2, Gylac, and Kyval. All strains were gram negative and grew by complete oxidation of the electron donors and concomitant stoichiometric reduction of elemental sulfur to hydrogen sulfide. The isolates used acetate, propionate, succinate, lactate, pyruvate, oxaloacetate, maleate, glutamate, alanine, aspartate, and yeast extract. All isolates, except strain Gylac, used citrate as an electron donor but valerate was oxidized only by strain Kyval. Fumarate and malate were degraded by all strains without an additional electron donor or acceptor. Kyprop, Gyprop, and Gylac utilized elemental sulfur as the sole inorganic electron acceptor, while Kysw2 and Kyval also utilized nitrate, dimethyl sulfoxide, or Fe(III)-citrate as an electron acceptor. Images

Finster, Kai; Bak, Friedhelm

1993-01-01

422

Plasma acetate turnover and oxidation.  

PubMed Central

Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.

Skutches, C L; Holroyde, C P; Myers, R N; Paul, P; Reichard, G A

1979-01-01

423

Putative ABC Transporter Responsible for Acetic Acid Resistance in Acetobacter aceti  

PubMed Central

Two-dimensional gel electrophoretic analysis of the membrane fraction of Acetobacter aceti revealed the presence of several proteins that were produced in response to acetic acid. A 60-kDa protein, named AatA, which was mostly induced by acetic acid, was prepared; aatA was cloned on the basis of its NH2-terminal amino acid sequence. AatA, consisting of 591 amino acids and containing ATP-binding cassette (ABC) sequences and ABC signature sequences, belonged to the ABC transporter superfamily. The aatA mutation with an insertion of the neomycin resistance gene within the aatA coding region showed reduced resistance to acetic acid, formic acid, propionic acid, and lactic acid, whereas the aatA mutation exerted no effects on resistance to various drugs, growth at low pH (adjusted with HCl), assimilation of acetic acid, or resistance to citric acid. Introduction of plasmid pABC101 containing aatA under the control of the Escherichia coli lac promoter into the aatA mutant restored the defect in acetic acid resistance. In addition, pABC101 conferred acetic acid resistance on E. coli. These findings showed that AatA was a putative ABC transporter conferring acetic acid resistance on the host cell. Southern blot analysis and subsequent nucleotide sequencing predicted the presence of aatA orthologues in a variety of acetic acid bacteria belonging to the genera Acetobacter and Gluconacetobacter. The fermentation with A. aceti containing aatA on a multicopy plasmid resulted in an increase in the final yield of acetic acid.

Nakano, Shigeru; Fukaya, Masahiro; Horinouchi, Sueharu

2006-01-01

424

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.

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

1985-01-01

425

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...

426

Cellulose: Its Regeneration in the Native Lattice  

Microsoft Academic Search

The regeneration of cellulose from solutions in 85 percent phosphoric acid into glycerol at 170 degrees C resulted in its recovery wholly in the native or cellulose I lattice. Identification of the structure of the regenerated material is based on comparisons of its x-ray diffractogram and its Raman spectrum with those of the native fiber, cellulose II, and cellulose IV.

Rajai H. Atalla; Seelye C. Nagel

1974-01-01

427

Effects of fluticasone propionate in COPD patients with bronchial hyperresponsiveness  

PubMed Central

Background: Treatment of chronic obstructive pulmonary disease (COPD) with inhaled corticosteroids does not appear to be as effective as similar treatment of asthma. It seems that only certain subgroups of patients with COPD benefit from steroid treatment. A study was undertaken to examine whether inhaled fluticasone propionate (FP) had an effect on lung function and on indices of inflammation in a subgroup of COPD patients with bronchial hyperresponsiveness (BHR). Methods: Twenty three patients with COPD were studied. Patients had to be persistent current smokers between 40 and 70 years of age. Non-specific BHR was defined as a PC20 for histamine of ?8 mg/ml. Patients received either 2 x 500 µg FP or placebo for 6 months. Expiratory volumes were measured at monthly visits, BHR was determined at the start of the study and after 3 and 6 months, and bronchial biopsy specimens were taken at the start and after 6 months of treatment. Biopsy specimens from asymptomatic smokers served as controls. Results: In contrast to asthma, indices of BHR were not significantly influenced by treatment with FP. Forced expiratory volume in 1 second (FEV1) showed a steep decline in the placebo group but remained stable in patients treated with FP. FEV1/FVC, and maximal expiratory flows at 50% and 25% FVC (MEF50, MEF25) were significantly increased in the FP treated patients compared with the placebo group. Biopsy specimens were analysed for the presence of CD3+, CD4+, CD8+, MBP+, CD15+, CD68+, CD1a, and tryptase cells. FP treatment resulted in marginal reductions in these indices of inflammation. Conclusion: In patients with COPD and BHR, FP has a positive effect on indices of lung function compared with placebo. Bronchial inflammation analysed in bronchial biopsy specimens is only marginally reduced.

Verhoeven, G; Hegmans, J; Mulder, P; Bogaard, J; Hoogsteden, H; Prins, J

2002-01-01

428

Development of fluticasone propionate and comparison with other inhaled corticosteroids.  

PubMed

Fluticasone propionate (FP) is a trifluorinated glucocorticoid based on the androstane nucleus. It was selected for development from structure-activity relationships (topical anti-inflammatory, cutaneous vasoconstriction, and hypothalamic-pituitary-adrenal axis suppression) of a series of 17beta-carbothioates. FP is 3-, 300-, and 1000-fold more lipophilic than beclomethasone dipropionate, budesonide, and triamcinolone acetonide, respectively. FP has an absolute affinity (KD) for the glucocorticoid receptor of 0.5 nmol/L and a relative receptor affinity 1.5-fold higher than beclomethasone-17-monopropionate (17-BMP) and mometasone furoate, 3-fold higher than budesonide, and 20-fold higher than flunisolide and triamcinolone acetonide. The rate of association of FP with the receptor is faster and the rate of dissociation slower than other corticosteroids. The resulting half-life of the FP active steroid-receptor complex is >10 hours, compared with approximately 5, 7.5, and 4 hours for budesonide, 17-BMP, and triamcinolone acetonide, respectively. FP has high selectivity for the glucocorticoid receptor, with little or no activity at other steroid receptors. FP is more potent than beclomethasone dipropionate, budesonide, triamcinolone acetonide, and mometasone furoate in inhibiting human T-cell migration and proliferation, inhibiting CD4+ T-cell cytokine and basophil histamine release, attenuating adhesion molecule expression, stimulating inflammatory cell apoptosis, and inducing cellular antiprotease release. In asthma patients, FP decreases the number of CD3+, CD4+, CD8+, and CD25+ T cells, mast cells, and eosinophils in bronchial biopsies, in addition to suppressing CD1a-dendritic and IgE+ cells and HLA-DR. FP, therefore, has a good pharmacologic profile for a topical steroid with increased intrinsic glucocorticoid potency and potent anti-inflammatory activity. PMID:9563368

Johnson, M

1998-04-01

429

Detection of testosterone propionate administration in horse hair samples.  

PubMed

A sensitive and specific method has been developed to detect semi-quantitatively testosterone in horse hair samples. The method involved a washing step with sodium dodecylsulfate aqueous solution. The mane and tail hair samples (100mg) were dissolved in 1 mL of sodium hydroxide for 15 min at 95 degrees C in the presence of d3-boldenone used as internal standard. The next three steps involved diethyl ether extraction and a solid phase extraction on Isolute C18 (EC) cartridges eluted with methanol. The residue was derivatized by adding 100 microL of acetonitrile and 30 microL of PFPA then incubating for 15 min at 60 degrees C. After evaporation, 30 microL of hexane was added and 2.5 microL was injected into the column (a bonded phase fused silica capillary column DB5MS, 30 m x 0.25 mm i.d. x 0.25 microm film thickness) of a Trace GC chromatograph. In order to improve the sensitivity of the method, damping gas flow has been optimized. Testosterone was identified in MS(2) full scan mode on the Polaris Q instrument. The assay was capable of detecting less than 1 pg mg(-1). The recovery was close to 90%. The analysis of tail and mane samples collected from a gelding horse having received a single dose of testosterone propionate (1 mg kg(-1)) showed the presence of testosterone in the range of 1-6 pg mg(-1) in hair collected during 5 months after administration. PMID:17383946

Boyer, S; Garcia, P; Popot, M A; Steiner, V; Lesieur, M

2007-03-14

430

Iodine-containing cellulose mixed esters as radiopaque polymers for direct embolization of cerebral aneurysms and arteriovenous malformations.  

PubMed

The present study deals with the synthesis and characterization of radiopaque polymers which could, when solubilized in an appropriate water-miscible solvent, be useful embolic materials for the treatment of cerebral aneurysms and arteriovenous malformations. For this purpose cellulose (both microcrystalline and powdered) and partially substituted cellulose acetate (two different viscosity grades) were selected as starting materials to prepare iodine-containing polymers through various synthetic routes. The materials obtained were characterized by IR and NMR spectroscopy, molecular weight, iodine content, radiopacity and solubility in selected injectable organic solvents. The embolic liquids were evaluated for their precipitation behavior in a phosphate buffer solution (pH 7.4) mimicking physiological conditions using an in vitro aneurysm model. A sheep model was also used to assess in vivo the radiopacity and precipitation properties of a highly concentrated solution of a cellulose acetate 2,3,4-triiodobenzoate mixed ester. All materials with 4-iodo- and 2,3,5-triiodobenzoyl groups gave sufficient radiopacity to be regarded as possible embolization materials, whereas iododeoxycellulose and iododeoxycellulose acetate were not radiopaque because of their low iodine content. Esters synthesized using cellulose as starting material were not soluble in the selected organic solvents due to the presence of many residual hydroxyl groups, but could be used for other biomedical applications where insoluble radiopaque materials are used. In contrast, solubility of the materials as well as satisfactory precipitation properties were ensured using cellulose acetate as the starting material. In conclusion, cellulose acetate iodobenzoate mixed esters dissolved in diglyme or dimethyl isosorbide (dimethyl sulfoxide is probably less appropriate because of its toxicity and hemolytic properties) could be useful embolic liquids for the treatment of cerebral aneurysms or arteriovenous malformations. PMID:11762830

Mottu, F; Rüfenacht, D A; Laurent, A; Doelker, E

2002-01-01

431

Magnetic cellulose-derivative structures  

DOEpatents

Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

Walsh, Myles A. (Falmouth, MA); Morris, Robert S. (Fairhaven, MA)

1986-09-16

432

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

433

77 FR 31722 - New Animal Drugs; Change of Sponsor; Estradiol; Estradiol Benzoate and Testosterone Propionate...  

Federal Register 2010, 2011, 2012, 2013

...for cattle and for melengestrol acetate liquid Type A medicated article and use in combination...500 558.342 (melengestrol acetate) Liquid Premix. 200-346...500 558.342 (melengestrol acetate) Liquid Premix/RUMENSIN...

2012-05-30

434

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

PubMed Central

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. 1H-NMR results for the rHbICN PheB10Tyr derivative showed chemical shifts of TyrB10 OH? at 31.00ppm, GlnE7 N?1H/N?2H at 10.66ppm/?3.27ppm, and PheE11 C?H at 11.75ppm, indicating the presence of a crowded, collapsed, and constrained distal pocket. Strong dipolar contacts and inter-residues crosspeaks between Gln E7/6-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 hemeligand moiety.

Ramos-Santana, Brenda J.; Lopez-Garriga, Juan

2012-01-01

435

Bioavailability of Clobetasol Propionate – Quantification of Drug Concentrationsin the Stratum Corneum by Dermatopharmacokinetics UsingTape Stripping  

Microsoft Academic Search

The concentration of clobetasol propionate in the stratum corneum after application of three different formulations was determined, quantifying the influence of the formulations on the bioavailability of the drug. The stratum corneum was sampled by tape stripping. The concentrations of clobetasol propionate were determined quantitatively by HPLC. After application of Clobetasol Propionate Cream USP, 0.05%, and Temovate Cream, 0.05%, identical

H.-J. Weigmann; J. Lademann; R. v. Pelchrzim; W. Sterry; T. Hagemeister; R. Molzahn; M. Schaefer; M. Lindscheid; H. Schaefer; V. P. Shah

1999-01-01

436

Integration of cellulases into bacterial cellulose: Toward bioabsorbable cellulose composites.  

PubMed

Cellulose biodegradation resulting from enzymolysis generally occurs in nature rather than in the human body because of the absence of cellulose degrading enzymes. In order to achieve in-vivo degradation in human body for in-vivo tissue regeneration applications, we developed a bioaborbable bacterial cellulose (BBC) material, which integrates one or more cellulose degrading enzymes (cellulases), and demonstrated its degradability in vitro using buffers with pH values relevant to wound environments. We introduced a double lyophilizing process to retain the microstructure of the bacterial cellulose as well as the activity of embedded enzymes allowing for long-term storage of the material, which only requires hydration before use. Enzymes and their combinations have been examined to optimize the in-vitro degradation of the BBC material. In-vitro studies revealed that acidic cellulases from Trichoderma viride showed reasonable activity for pH values ranging from 4.5 to 6.0. A commercial cellulase (cellulase-5000) did not show good activity at pH 7.4, but its degrading ability increased when used in conjunction with a ?-glucosidase from Bacillus subtilis or a ?-glucosidase from Trichoderma sp. Given the harmless glucose product of the enzymatic degradation of cellulose, the BBC material may be ideal for many wound care and tissue engineering applications for the bioabsorbable purpose. PMID:21290589

Hu, Yang; Catchmark, Jeffrey M

2011-02-02

437

Variations in Cellulosic Ultrastructure of Poplar  

Microsoft Academic Search

A key property involved in plant recalcitrance is cellulose crystallinity. In an attempt to establish the typical diversity\\u000a in cellulose ultrastructure for poplar, the variation and distribution of supramolecular and ultrastructural features, including\\u000a the fraction of crystalline cellulose forms $$ {\\\\text{I}}_{\\\\alpha } $$ and $$ {\\\\text{I}}_{\\\\beta } $$, para-crystalline cellulose and amorphous cellulose content were characterized. In this study, the

Marcus Foston; Christopher A. Hubbell; Mark Davis; Arthur J. Ragauskas

2009-01-01

438

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

439

A propionate CoA-transferase of Ralstonia eutropha H16 with broad substrate specificity catalyzing the CoA thioester formation of various carboxylic acids.  

PubMed

In this study, we have investigated a propionate CoA-transferase (Pct) homologue encoded in the genome of Ralstonia eutropha H16. The corresponding gene has been cloned into the vector pET-19b to yield a histidine-tagged enzyme which was expressed in Escherichia coli BL21 (DE3). After purification, high-performance liquid chromatography/mass spectrometry (HPLC/MS) analyses revealed that the enzyme exhibits a broad substrate specificity for carboxylic acids. The formation of the corresponding CoA-thioesters of acetate using propionyl-CoA as CoA donor, and of propionate, butyrate, 3-hydroxybutyrate, 3-hydroxypropionate, crotonate, acrylate, lactate, succinate and 4-hydroxybutyrate using acetyl-CoA as CoA donor could be shown. According to the substrate specificity, the enzyme can be allocated in the family I of CoA-transferases. The apparent molecular masses as determined by gel filtration and detected by SDS polyacrylamide gel electrophoresis were 228 and 64 kDa, respectively, and point to a quaternary structure of the native enzyme (?4). The enzyme exhibited similarities in sequence and structure to the well investigated Pct of Clostridium propionicum. It does not contain the typical conserved (S)ENG motif, but the derived motif sequence EXG with glutamate 342 to be, most likely, the catalytic residue. Due to the homo-oligomeric structure and the sequence differences with the subclasses IA-C of family I CoA-transferases, a fourth subclass of family I is proposed, comprising - amongst others - the Pcts of R. eutropha H16 and C. propionicum. A markerless precise-deletion mutant R. eutropha H16?pct was generated. The growth and accumulation behaviour of this mutant on gluconate, gluconate plus 3,3'-dithiodipropionic acid (DTDP), acetate and propionate was investigated but resulted in no observable phenotype. Both, the wild type and the mutant showed the same growth and storage behaviour with these carbon sources. It is probable that R. eutropha H16 is upregulating other CoA-transferase(s) or CoA-synthetase(s), thereby compensating for the lacking Pct. The ability of R. eutropha H16 to substitute absent enzymes by isoenzymes has been already shown in different other studies in the past. PMID:23250223

Lindenkamp, Nicole; Schürmann, Marc; Steinbüchel, Alexander

2012-12-19

440

Coagulation of Microcrystalline Cellulose Dispersions.  

National Technical Information Service (NTIS)

The coagulation effects on microcrystalline cellulose sols of simple ions, hydrolyzed metal ions, chelate complexes, and a series of alkylammonium chlorides differing in length of the hydrocarbon chain have been investigated. It was found that these sols ...

S. Kratohvil G. E. Janauer E. Matijevic

1968-01-01

441

Metabolic Fate of 3,4-Dichloropropionanilide in Plants: The Metabolism of the Propionic Acid Moiety  

PubMed Central

3,4-Dichloropropionanilide-14C (propanil) labeled in either the C-1 or C-3 carbon atoms of the propionic acid moiety was applied to the roots of pea (Pisum sativum L.) and rice (Oryza sativa L.) plants in nutrient solution (0.1 mm-0.28 mm). Radioactivity was detected throughout the treated plants, but the greatest labeling was found in the roots. None of the products that contained aniline were radioactive, suggesting that the plants split the propionic acid moiety from propanil. The fate of the propionate moiety of propanil was determined by recovery of 14CO2 from plants exposed to propanil-14C. The time-course of the 14CO2 production demonstrated that the intact propionic acid was cleaved from the propanil and subsequently catabolized by the ?-oxidation catabolic sequence. The appearance of radioactivity in the shoots was attributed to the incorporation of products of propionate metabolism. Both the susceptible pea plants and the tolerant rice plants converted a high percentage of the administered propanil-14C to 14CO2. Images

Still, G. G.

1968-01-01

442

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

443

Acetate metabolism in Methanosarcina barkeri  

Microsoft Academic Search

Methanosarcina barkeri was grown by acetate fermentation in complex medium (N2 gas phase). The molar growth yield was 1.6–1.9 g cells\\/mol methane formed. Under these conditions 63–82% of the methane produced byMethanosarcina strains was derived from the methyl carbon of acetate, indicating that some methane was derived from other media components. Growth was not demonstrated in complex media lacking acetate

P. J. Weimer; J. G. Zeikus

1978-01-01

444

L-carnitine enhances excretion of propionyl coenzyme A as propionylcarnitine in propionic acidemia.  

PubMed Central

Treatment with L-carnitine greatly enhanced the formation and excretion of short-chain acylcarnitines in three patients with propionic acidemia and in three normal controls. The use of fast atom bombardment mass spectrometry and linked scanning at constant magnetic (B) to electric (E) field ratio identified the acylcarnitine as propionylcarnitine in patients with propionic acidemia. The normal children excreted mostly acetylcarnitine. Propionic acidemia and other organic acidurias are characterized by the intramitochondrial accumulation of short-chain acyl-Coenzyme A (CoA) compounds. The substrate specificity of the carnitine acetyltransferase enzyme and its steady state nature appears to facilitate elimination of propionyl groups while restoring the acyl-CoA:free CoA ratio in the mitochondrion. We suggest that L-carnitine may be a useful therapeutic approach for elimination of toxic acyl CoA compounds in several of these disorders.

Roe, C R; Millington, D S; Maltby, D A; Bohan, T P; Hoppel, C L

1984-01-01

445

[Nomegestrol acetate: clinical pharmacology].  

PubMed

Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678

Lello, S

2009-10-01

446