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1

Permeation performance of Cellulose acetate propionate\\/polyvinylidine fluoride blend membranes by phase inversion  

Microsoft Academic Search

In this study, cellulose acetate propionate (CAP) and polyvinylidene fluoride (PVDF) were selected to prepare porous-blend membrane by wet phase inversion method. The effect of the CAP and PVDF concentration of the casting solution on membrane morphology structure and thermal stability was investigated by scanning electron microscopy (SEM) and thermal gravimetry\\/differential scanning calorimetry (TGA\\/DSC). The pure water flux by the

Kuo-Liang Chuang; Ming-Chi Hsieh; Yun-Chieh Su; Hui-Hsin Tseng; Li-Luen Huang

2010-01-01

2

Incorporation of low-mass compound to alter the orientation birefringence in cellulose acetate propionate  

NASA Astrophysics Data System (ADS)

A blend of cellulose acetate propionate (CAP) with bisphenoxyethanolfluorene (BPEF), a low-mass compound (LMC), was prepared using melt-mixing method. The effect of BPEF addition on the orientation birefringence of CAP films was analyzed and compared to the blend added with tricresyl phosphate (TCP), an LMC known to increase the orientation birefringence of cellulose esters. Contrary to TCP, BPEF addition is found to decrease the positive birefringence of CAP. Moreover, it is observed that stress-optical law is not applicable for the CAP/LMC blend. The different effect on the orientation birefringence shown by BPEF and TCP is due to the different polarizability anisotropy. The decrease in orientation birefringence indicates that the polarizability ellipsoid of BPEF molecules is aligned in a direction perpendicular to the stretching direction, as opposed to that of TCP molecules which is parallel to the stretching direction. This alignment is thought to be resulted from the so called nematic interaction, in which LMC molecules are forced to orient to the stretching direction by the alignment of polymer chains. Furthermore, it is found that the magnitude of orientation birefringence of BPEF is larger than that of TCP at the same stress value, i.e., the same degree of orientation of CAP molecules, despite having a smaller intrinsic birefringence. This suggests that the nematic interaction with CAP chains of BPEF is stronger than TCP.

Abd Manaf, Mohd Edeerozey; Miyagawa, Azusa; Nobukawa, Shogo; Aoki, Yoshihiko; Yamaguchi, Masayuki

2013-05-01

3

Nanofabrication in cellulose acetate.  

PubMed

We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health. PMID:19224020

Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua

2009-03-01

4

The assimilation of acetate and propionate by Prototheca zopfi  

PubMed Central

1. The tricarboxylic acid and glyoxylate cycles are of major importance in the assimilation of acetate and propionate by Prototheca zopfii. The pattern of assimilation of [2-14C]acetate and [2-14C]propionate by whole cells growing with their respective substrates is similar except that, with propionate, ?-hydroxypropionate is the first labelled intermediate detected. 2. Carbon dioxide fixation is of little quantitative importance for the growth of this organism with propionate. 3. The yield of cells obtained/mole of acetate is similar to that obtained/mole of propionate and about half that obtained/mole of n-butyrate, these substrates acting as sole sources of carbon and energy.

Lloyd, D.; Callely, A. G.

1965-01-01

5

Biodegradable Plastics Based on Cellulose Acetate  

Microsoft Academic Search

It is generally known that secondary cellulose acetate (with 53 to 56% acetyl groups) is suitable for thermoplastic processing. With appropriate plasticizers a plastic material is obtained which excels in transparency and pleasant texture, and it is therefore often used for tool handles, combs, spectacle frames, and the like. In principle, cellulose acetate with such a degree of substitution is

Alexander Ach

1993-01-01

6

36 CFR 1232.24 - Unstable cellulose-acetate film.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Unstable cellulose-acetate film. 1232.24 Section 1232...Audiovisual Records Management § 1232.24 Unstable cellulose-acetate film. Cellulose-acetate film, also known as safety...

2009-07-01

7

Water dispersible microbicidal cellulose acetate phthalate film  

Microsoft Academic Search

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 \\

A Robert Neurath; Nathan Strick; Yun-Yao Li

2003-01-01

8

Miscibility of cellulose acetate with vinyl polymers  

Microsoft Academic Search

Binary blend films of cellulose acetate (CA) with flexible syntheticpolymers including poly(vinyl acetate) (PVAc), poly(N-vinyl pyrrolidone) (PVP),and poly(N-vinyl pyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] were preparedfrommixed polymer solutions by solvent evaporation. Thermal analysis by DSC showedthat CA of any degree of substitution (DS) was not miscible with PVAc, but CAwith DS less than 2.8 was miscible with PVP to form homogeneous blends. Thestate

Yoshiharu Miyashita; Tetsuya Suzuki; Yoshiyuki Nishio

2002-01-01

9

Blend miscibility of cellulose propionate with poly(N-vinyl pyrrolidone-co-methyl methacrylate).  

PubMed

The blend miscibility of cellulose propionate (CP) with poly(N-vinyl pyrrolidone-co-methyl methacrylate) (P(VP-co-MMA)) was investigated. The degree of substitution (DS) of CP used ranged from 1.6 to >2.9, and samples for the vinyl polymer component were prepared in a full range of VP:MMA compositions. Through DSC analysis and solid-state (13)C NMR and FT-IR measurements, we revealed that CPs of DS<2.7 were miscible with P(VP-co-MMA)s of VP?~10mol% on a scale within a few nanometers, in virtue of hydrogen-bonding interactions between CP-hydroxyls and VP-carbonyls. When the DS of CP exceeded 2.7, the miscibility was restricted to the polymer pairs using P(VP-co-MMA)s of VP=ca. 10-40 mol%; the scale of mixing in the blends concerned was somewhat larger (ca. 5-20 nm), however. The appearance of such a "miscibility window" was interpretable as an effect of intramolecular repulsion in the copolymer component. Results of DMA and birefringence measurements indicated that the miscible blending of CP with the vinyl polymer invited synergistic improvements in thermomechanical and optical properties of the respective constituent polymers. Additionally, it was found that the VP:MMA composition range corresponding to the miscibility window was expanded by modification of the CP component into cellulose acetate propionate. PMID:23987378

Sugimura, Kazuki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

2013-10-15

10

Effect of acetate and propionate on calcium absorption from the rectum and distal colon of humans.  

PubMed

To determine the effects of acetate and propionate on calcium absorption from the human distal colon and rectum, six healthy human subjects were given rectal infusions containing 50 mmol CaCl2/L on four separate occasions. Addition of 56.3 mmol acetate/L, 18.7 mmol propionate/L, or acetate and propionate together increased calcium disappearance (expressed as the change in the ratio of calcium to polyethylene glycol) from -5.5 +/- 1.4 to -22.6 +/- 2.8, -23.2 +/- 3.2, and -19.7 +/- 4.6, respectively; P < 0.05. To determine the effects of different acetate and propionate concentrations, six different subjects were studied further. The effects of 18.7 or 56.3 mmol acetate/L on calcium absorption were the same as those of 18.7 mmol propionate/L (-15.7 +/- 1.4), and less than those of 56.3 mmol propionate/L (-20.3 +/- 2.4, P < 0.05). We conclude that both acetate and propionate enhance calcium absorption from the human distal colon, but that propionate has a greater effect at higher concentrations. Further studies are needed to determine the mechanism of calcium absorption from the colon. PMID:8599322

Trinidad, T P; Wolever, T M; Thompson, L U

1996-04-01

11

Regeneration of Cellulose Acetate Membranes.  

National Technical Information Service (NTIS)

Several simple methods for in situ one-step regeneration of both flux and salt-retention properties of service-deteriorated membranes have been developed. Membranes have been successfully regenerated using hot, 4% acetic acid, and a one-step cleaning meth...

P. A. Cantor W. S. Higley C. W. Saltonstall

1970-01-01

12

Ultrasound-assisted dyeing of cellulose acetate.  

PubMed

The possibility of reducing the use of auxiliaries in conventional cellulose acetate dyeing with Disperse Red 50 using ultrasound technique was studied as an alternative to the standard procedure. Dyeing of cellulose acetate yarn was carried out by using either mechanical agitation alone, with and without auxiliaries, or coupling mechanical and ultrasound agitation in the bath where the temperature range was maintained between 60 and 80 °C. The best results of dyeing kinetics were obtained with ultrasound coupled with mechanical agitation without auxiliaries (90% of bath exhaustion value at 80 °C). Hence the corresponding half dyeing times, absorption rate constants according to Cegarra-Puente modified equation and ultrasound efficiency were calculated confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound added to mechanical agitation was evidenced by the lower value (48 kJ/mol) in comparison with 112 and 169 kJ/mol for mechanical stirring alone with auxiliaries and without, respectively. Finally, the fastness tests gave good values for samples dyed with ultrasound technique even without auxiliaries. Moreover color measurements on dyed yarns showed that the color yield obtained by ultrasound-assisted dyeing at 80 °C of cellulose acetate without using additional chemicals into the dye bath reached the same value yielded by mechanical agitation, but with remarkably shorter time. PMID:24457001

Udrescu, C; Ferrero, F; Periolatto, M

2014-07-01

13

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

14

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

15

Preference for flavored wheat straw by lambs conditioned with intraruminal infusions of acetate and propionate.  

PubMed

We hypothesized that volatile fatty acids in rumen fluid are feedback signals that can condition food preferences or aversions in sheep. Three predictions were tested based on this hypothesis: 1) low doses of sodium propionate or sodium acetate condition preferences, but high doses condition aversions (Exp. 1 and 2); 2) preferences are not caused by osmotic load (Exp. 3 and 4); and 3) low doses of mixtures of acetate:propionate condition preferences (Exp. 4). In Exp. 1, 2, and 4, lambs were divided into four groups (10 lambs/group), and lambs in Exp. 3 were divided into two groups (five lambs/group). In all experiments, alfalfa pellets were the basal diet. On even days, half of the lambs were offered chopped wheat straw containing a distinctive flavor, whereas the other half received straw with a different flavor. During straw ingestion, different groups of lambs received intraruminal infusions of different concentrations (4, 8, or 12% of the daily DE received) of sodium propionate (Exp. 1), sodium acetate (Exp. 2), NaCl at osmotic loads equivalent to those when propionate supplied 4% of the daily DE received (Exp. 3), or different proportions of sodium acetate:sodium propionate (55:45 or 75:25% of the DE of the infusion [4% of the daily DE received]), or equimolar amounts of NaCl (Exp. 4). On odd days, the flavors were switched, and no infusions were administered. After 8 d of conditioning, lambs were offered a choice of wheat straw with the two distinctive flavors. Lambs preferred the flavor paired with the lowest doses of propionate (P = .07) and acetate (P = .08) but avoided the highest doses (P < .001). Excesses of VFA may condition aversions due to increases in rumen fluid osmolality and(or) excessive rates of supply of energy or sodium to the rumen. Lambs also preferred flavored straw associated with combinations of acetate and propionate (P < .001), especially at the highest concentration of propionate (P = .10). Lambs avoided NaCl in Exp. 3 (P < .001) and did not form preferences for NaCl in Exp. 4 (P > .05). Thus, osmolalities were not responsible for flavor preferences. In conclusion, our results support the hypothesis that food preferences and aversions reside along a continuum that depends on the amount of VFA infused. PMID:9374303

Villalba, J J; Provenza, F D

1997-11-01

16

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

17

Temperature effect on acetate and propionate consumption by sulfate-reducing bacteria in saline wastewater.  

PubMed

Seawater toilet flushing, seawater intrusion in the sewerage, and discharge of sulfate-rich industrial effluents elevates sulfate content in wastewater. The application of sulfate-reducing bacteria (SRB) in wastewater treatment is very beneficial; as for example, it improves the pathogen removal and reduces the volume of waste sludge, energy requirement and costs. This paper evaluates the potential to apply biological sulfate reduction using acetate and propionate to saline sewage treatment in moderate climates. Long-term biological sulfate reduction experiments at 10 and 20 °C were conducted in a sequencing batch reactor with synthetic saline domestic wastewater. Subsequently, acetate and propionate (soluble organic carbon) conversion rate were determined in both reactors, in the presence of either or both fatty acids. Both acetate and propionate consumption rates by SRB were 1.9 times lower at 10 °C than at 20 °C. At 10 °C, propionate was incompletely oxidized to acetate. At 10 °C, complete removal of soluble organic carbon requires a significantly increased hydraulic retention time as compared to 20 °C. The results of the study showed that biological sulfate reduction can be a feasible and promising process for saline wastewater treatment in moderate climate. PMID:24463759

van den Brand, T P H; Roest, K; Brdjanovic, D; Chen, G H; van Loosdrecht, M C M

2014-05-01

18

Extraction equilibria of acetic and propionic acids from dilute aqueous solution by several solvents  

SciTech Connect

Extraction equilibria of acetic acid and propionic acid with hexane solutions of trioctyl amine, trioctyl phosphine oxide, and tributyl phosphate were studied. The species formed in the systems were estimated, and the distribution coefficients and the equilibrium constants for these species were evaluated.s

Fahim, M.A. (Univ. of United Arab Emirates, Al-Ain (United Arab Emirates))

1992-10-01

19

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

20

Ester hydrolysis of cellulose acetate and cellulose acetate phthalate in aqueous suspension and solution, and solid state  

Microsoft Academic Search

The increasing usage of aqueous film coating in the pharmaceutical industry has generated interest concerning the stability of polymer film forming agents to ester hydrolysis. Cellulose acetate phthalate (CAP) and cellulose acetate (CA) are examples of polymers which either have or are being considered for film coating applications in the form of aqueous dispersions. This study was undertaken to determine

Thomas Patrick Garcia

1989-01-01

21

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

22

Continuous cellulose fiber-reinforced cellulose ester composites III. Commercial matrix and fiber options  

Microsoft Academic Search

Thermoplastic composites were prepared using two continuous regenerated cellulose fiber types, rayon and lyocell, and with several different commercially-available thermoplastic cellulose esters as matrix. Matrix options included cellulose acetate propionate (CAP), and several cellulose acetate butyrates (CAB) with different butyryl content, having different molecular weights and different methods of plasticization (adipates and very low molecular weight cellulose ester fractions). Choice

Amara Franko; Kevin C. Seavey; James Gumaer; Wolfgang G. Glasser

2001-01-01

23

Grafting of Maleic Anhydride Copolymers onto Cellulose Acetate and Methyl Cellulose  

Microsoft Academic Search

A high level of control over grafting reactions onto cellulose derivatives was achieved by an acyl transfer reaction mechanism. Ethylene\\/maleic anhydride copolymer (EMA) and styrene\\/maleic anhydride copolymer (SMA) were grafted onto cellulose acetate (CA) and methyl cellulose (MC) in a simple and effective way under homogeneous reaction conditions. While pyridine, a commonly used catalyst for the reaction of an anhydride

Myoung-Ku Lee; Christopher J. Biermann

1992-01-01

24

Biodegradable cellulose acetate nanofiber fabrication via electrospinning.  

PubMed

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

Christoforou, Theopisti; Doumanidis, Charalabos

2010-09-01

25

Nanocomposites of Cellulose Acetate Butyrate Reinforced with Cellulose Nanocrystals  

Microsoft Academic Search

Nanocrystals were prepared by acid hydrolysis of bacterial cellulose microfibrils. These were topochemically trimethylsilylated, in an attempt to reduce their hydrophilicity. Composites were made by dispersing either native or silylated crystals in cellulose acetatebutyrate matrixes and solution casting of the dispersions. Particles were characterized by transmission electron microscopy. The composites were characterized by differential scanning calorimetry and dynamic mechanical analysis.

Maren Grunert; William T. Winter

2002-01-01

26

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

PubMed

Fed-batch propionic and acetic acid fermentations were performed in semi-defined laboratory medium and in corn steep liquor with Propionibacterium acidipropionici strain P9. On average, over four experiments, 34.5 milligrams propionic acid and 12.8 milligrams acetic acid were obtained in about 146 h in laboratory medium with 79 milligrams glucose added over five feeding periods. The highest concentration of propionic acid, 45 milligrams, was obtained when the glucose concentration was not allowed to drop to zero. In corn steep liquor 35 milligrams propionic acid and 11 milligrams acetic acid were produced in 108 h from 59.4 milligrams total lactic acid provided as seven feedings of corn steep liquor. Extractive fed-batch fermentations were conducted in semi-defined medium using either flat-sheet-supported liquid membranes or hollow-fiber membrane extraction to remove organic acids from the culture medium. As operated during the course of the fermentation, these systems extracted 25% and 22% of the acetic acid and 36.5% and 44.5% of the propionic acid, respectively, produced in the fermentation. Total amounts of acids produced were about the same as in comparable nonextractive fermentations: 30-37 milligrams propionic acid and 13 milligrams acetic acid were produced in 150 h. Limitations on acid production can be attributed to limited substrate feed, not to failure of the extraction system. PMID:8867628

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

1996-02-01

27

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

28

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

Microsoft Academic Search

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

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

2003-01-01

29

Tensile properties of cellulose acetate butyrate composites reinforced with bacterial cellulose  

Microsoft Academic Search

Composites of cellulose acetate butyrate reinforced with cellulose sheets synthesised by Gluconacetobacter xylinus were produced by solvent evaporation casting. The composites contained 10% and 32% volume cellulose, and showed a Young’s modulus of 3.2 and 5.8 GPa, and a strength of 52.6 and 128.9 MPa, respectively, in tensile tests. Stress–strain curves showed bi-phasic material characteristics, with an initial linear behaviour,

Wolfgang Gindl; Jozef Keckes

2004-01-01

30

Phosphorylated cellulose propionate derivatives as thermoplastic flame resistant\\/retardant materials: influence of regioselective phosphorylation on their thermal degradation behaviour  

Microsoft Academic Search

Cellulose ester derivatives having phosphoryl side-chains were synthesized by phosphorylation of two types of cellulose propionate\\u000a (CP); the difference between the two CPs was whether the primary hydroxyl group at C6 had been fully propionylated or not.\\u000a Dimethyl phosphate, dimethyl thiophosphate, diethyl phosphate, or diethyl thiophosphate was introduced into the residual hydroxyl\\u000a positions of the CPs. Chemical composition of the

Dan Aoki; Yoshiyuki Nishio

2010-01-01

31

Levoglucosan, cellobiose and their acetates as model compounds for the thermally assisted hydrolysis and methylation of cellulose and cellulose acetate  

Microsoft Academic Search

Levoglucosan (1,6-anhydro-?-d-glucopyranose), cellobiose (?-d-glucopyranosyl-[1?4]-d-glucopyranose), tri-O-acetyl-levoglucosan (1,6-anhydro-?-d-glucopyranose-2,3,4-triacetate) and cellobiose octaacetate have been studied with regard to their suitability as model compounds for thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide of cellulose and cellulose acetate. In addition, the results of analytical pyrolysis of methyl cellulose were compared with those of thermally assisted hydrolysis and methylation, to distinguish between products arising from

C Schwarzinger; I Tanczos; H Schmidt

2002-01-01

32

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

33

Demixing and gelation behavior of ternary cellulose acetate solutions  

Microsoft Academic Search

The demixing behavior on cooling of ternary systems of cellulose acetate\\/solvent\\/water has been examined for CA concentrations up to 40 wt% CA in several solvents. Cloud points have been measured as a function of cooling rate. The rapid process of liquid - liquid demixing can be discriminated from the slow process of aggregate formation by examining the dependence of the

A. J. Reuvers; F. W. Altena; C. A. Smolders

1986-01-01

34

Plasticization of Fibrous Cellulose Acetate I - Synthesis and Characterisation  

Microsoft Academic Search

Synthesis and characterisation of fibrous cellulose triacetate -CTA are reported using an acetic acid \\/ anhydride \\/ perchloric acid toluene catalysed route. The fibrous product exhibits a high degree of nano crystallinity. An optimum concentration of the reactants for substitution and minimization of fibre degradation were studied. Chain degradation was promoted by the acetylium ion and lead to a loss

Richard A. Pethrick; Anne Marie Wilton

2012-01-01

35

Studies on Cellulose Acetate Phthalate. 3. Osmotic Pressure Measurements  

Microsoft Academic Search

Osmotic pressure measurements of aqueous solutions of cellulose acetate phthalate (CAP) were carried out with the help of a highspeed membrane osmometer. The value of the osmotic coefficient, g, for different concentrations of CAP, as well as at different degree of neutralization for various concentrations, were estimated. The effect of concentration and degree of neutralization on the value of g

C. P. Patel; H. C. Trivedi; K. C. Patel; R. D. Patel

1986-01-01

36

Photoelectrochemistry of polyaniline supported in a microporous cellulose acetate membrane  

Microsoft Academic Search

We studied the photoelectrochemical response of polyaniline dispersed in a microporous membrane structure. Films of the composite were obtained by electropolymerization of aniline on a platinum electrode coated with a microporous cellulose acetate membrane. They were characterized by UV—Visible spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. We compared the results with a electrochemically synthesized polyaniline and a composite film

S. das Neves; M.-A. De Paoli

1998-01-01

37

Electrospun cellulose acetate-garnet nanocomposite magnetic fibers for bioseparations.  

PubMed

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

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

2014-01-01

38

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

39

Cellulose acetate graft copolymers with nano-structured architectures: Synthesis and characterization  

Microsoft Academic Search

Cellulose acetate is a very good film-forming polymer with major applications in cigarette filters, photographic films, cosmetics and pharmaceutics formulations and membrane separation processes. Nevertheless, its rigidity and relative hydrophobic character can be limiting drawbacks for some applications. In this work, new cellulose acetate materials with highly flexible and hydrophilic grafts were obtained with different hydrophilic\\/hydrophobic balances. Cellulose acetate was

M. Billy; A. Ranzani Da Costa; P. Lochon; R. Clément; M. Dresch; S. Etienne; J. M. Hiver; L. David; A. Jonquières

2010-01-01

40

Cellulose acetate nanofiltration hollow fiber membranes for forward osmosis processes  

Microsoft Academic Search

Cellulose acetate (CA) nanofiltration (NF) hollow fiber membranes have been fabricated and tested in the forward osmosis (FO) process. A two-step heat-treatment, i.e., 60min at 60°C and 20min at 95°C, effectively shrinks the membrane mean pore radius from 0.63 to 0.30nm. The molecular weight cut off (MWCO) of the resultant CA NF membrane is 186Da. In the NF experiments under

Jincai Su; Qian Yang; Joo Fuat Teo; Tai-Shung Chung

2010-01-01

41

Competition between polyphosphate and glycogen accumulating organisms in enhanced biological phosphorus removal systems with acetate and propionate as carbon sources.  

PubMed

Enhanced biological phosphorus removal (EBPR) is a widely used process for achieving phosphorus removal from wastewater. A potential reason for EBPR failure is the undesirable growth of glycogen accumulating organisms (GAOs), which can compete for carbon sources with the bacterial group responsible for phosphorus removal from wastewater: the polyphosphate accumulating organisms (PAOs). This study investigates the impact of carbon source on EBPR performance and the competition between PAOs and GAOs. Two sequencing batch reactors (SBRs) were operated during a 4-6 month period and fed with a media containing acetate or propionate, respectively, as the sole carbon source. It was found that the acetate fed SBR rarely achieved a high level of phosphorus removal, and that a large portion of the microbial community was comprised of "Candidatus Competibacter phosphatis", a known GAO. The propionate fed SBR, however, achieved stable phosphorus removal throughout the study, apart from one brief disturbance. The bacterial community of the propionate fed SBR was dominated by "Candidatus Accumulibacter phosphatis", a known PAO, and did not contain Competibacter. In a separate experiment, another SBR was seeded with a mixture of PAOs and a group of alphaproteobacterial GAOs, both enriched with propionate as the sole carbon source. Stable EBPR was achieved and the PAO population increased while the GAOs appeared to be out-competed. The results of this paper suggest that propionate may provide PAOs with a selective advantage over GAOs in the PAO-GAO competition, particularly through the minimisation of Competibacter. Propionate may be a more suitable substrate than acetate for enhancing phosphorus removal in EBPR systems. PMID:16293332

Oehmen, Adrian; Saunders, Aaron M; Vives, M Teresa; Yuan, Zhiguo; Keller, Jürg

2006-05-01

42

Combined sorption\\/transport of sodium dodecyl sulfate and hydrochloric acid in a blend of cellulose acetate butyrate with cellulose acetate hydrogen phthalate  

Microsoft Academic Search

The transport of hydrochloric acid (0.001–0.1 M) and sodium dodecyl sulfate (0.001–0.1 M) has been measured through a membrane consisting of a blend of cellulose acetate butyrate and cellulose acetate hydrogen phthalate. The cellulose derivative blend is suggested to suffer an alteration in the degree of hydrophobicity when in equilibrium with sodium dodecyl sulfate (SDS) through hemimicelle formation. An increase

Artur J. M. Valente; Hugh D. Burrows; Alexandre Ya. Polishchuk; Maria G. Miguel; Victor M. M. Lobo

2004-01-01

43

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

PubMed

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 studied. Solutions containing various concentrations of CaCl2.H2O with 56.3 mmol/L Ac, Pr, or NaCl were rectally infused to each subject. Rectal fluid was sampled at the end of the infusion (0 min), and 30 min later colonic contents were collected. Ca absorption for all treatments increased linearly with Ca concentration. For Ca + NaCl, the slope of regression line was 62 mumol.mmol-1.L Ca. With Ac + Ca, the slope of Ca absorption increased significantly to 113 mumol.mmol-1.L Ca, and with Pr + Ca, the slope increased to 159 mumol.mmol-1.L (P = 0.043 versus Ac + Ca) Ac and Pr absorption were increased by Ca. The data suggest that, over a physiologic range of Ca concentration, in the absence or presence of Ac and Pr, Ca is absorbed in the human rectum and distal colon by a non-saturable diffusion process, and that Ca absorption is enhanced by Ac and Pr. The data also suggest that both Ac and Pr absorption is stimulated by Ca. PMID:10422081

Trinidad, T P; Wolever, T M; Thompson, L U

1999-01-01

44

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

45

Transport Parameters in a Porous Cellulose Acetate Membrane  

PubMed Central

The transport parameters of a cellulose acetate membrane prepared from a mixture of cellulose acetate, formamide, and acetone, 25:25:50 by weight, were studied. The membrane consists of a thin, porous layer, the skin, in series with a thick, highly porous layer, the coarse support. In the skin the diffusional permeability coefficient, ?, of a number of small amides and alcohols depends critically upon the partition coefficient, Ks, the size of the molecule, and the apparent hydrogen-bonding ability, Ns, of the solute. These observations are in general agreement with our earlier conclusions on the properties of nonporous membranes. On the other hand, the corrected reflection coefficient, ?', is not a very sensitive function of either Ns or Ks taken separately. The correlation between ?' and molecular diameter is reasonably good; however, it is much improved when both Ns and Ks are taken into consideration. Isotope interaction was also studied in the present preparation and was found to provide only a small (5–8%) contribution to the diffusional permeability coefficient of ethylene glycol. The contribution of solute-water friction was found to be less than 24% of the total solute friction.

DiPolo, R.; Sha'afi, R. I.; Solomon, A. K.

1970-01-01

46

Ion selective permeation through cellulose acetate membranes in forward osmosis.  

PubMed

Solute-solute interactions can have a dramatic impact on the permeation of solutes through dense polymeric membranes. In particular, understanding how solute-solute interactions can affect the design of osmotically driven membrane processes (ODMPs) is critical to the successful development of these emerging water treatment and energy generation processes. In this work, we investigate the influence that solute-solute interactions have on nitrate permeation through an asymmetric cellulose acetate forward osmosis membrane. A series of experiments that included systematic modifications to the cation paired with nitrate, the identity of the draw solute, and the solution pH were conducted. These experiments reveal that in the unique operating geometry of ODMPs, where solute containing solutions are present on both sides of the membrane, nitrate fluxes are significantly higher (>15 times in some cases) than predicted by existing models for solute permeation in ODMPs. The identity of the cation paired with nitrate influences the flux of nitrate; the identity of the cation in the draw solution does not affect the flux of nitrate; however, the identity of the anion in the draw solution has the most significant impact on the flux of nitrate. These results suggest that an ion exchange mechanism, which allows nitrate to switch rapidly with anions from the draw solution, is present when cellulose acetate based membranes are used in ODMPs. PMID:24152190

Irvine, Gavin J; Rajesh, Sahadevan; Georgiadis, Michael; Phillip, William A

2013-12-01

47

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

48

Comparison of polycarbonate and cellulose acetate membrane filters for isolation of Campylobacter concisus from stool samples.  

PubMed

One thousand seven hundred ninety-one diarrheic stool samples were cultivated for Campylobacter spp. We found a high prevalence of Campylobacter concisus with use of a polycarbonate filter (n = 114) compared to a cellulose acetate filter (n = 79) (P < .0001). The polycarbonate filter is superior to the commonly used cellulose acetate filter for detection of C. concisus. PMID:23743174

Nielsen, Hans Linde; Engberg, Jørgen; Ejlertsen, Tove; Nielsen, Henrik

2013-08-01

49

Morphological Properties and Antibacterial Activity of Nano-Silver-Containing Cellulose Acetate Phthalate Films  

Microsoft Academic Search

Modification of the rheological properties of cellulose acetate phthalate in 2-methoxyethanol\\/acetone\\/water, at different compositions of solvent mixtures, allowed the identification of optimal composition of solvent mixtures for obtaining fibers with controlled diameters. Changing the solvent content in the casting solutions favors modification of the morphological aspects of cellulose acetate phthalate (CAP) films, as observed from atomic force microscopy images. Silver

Adina Maria Necula; Simona Dunca; Iuliana Stoica; Niculae Olaru; Liliana Olaru; Silvia Ioan

2010-01-01

50

Biodegradability and process characterization of nonwovens formed from cotton and cellulose acetate fibers  

Microsoft Academic Search

A possible candidate as an environmentally friendly nonwoven fabric is one which can be formed from the thermal calendering of a cotton\\/cellulose acetate blend. The results presented have focused on biodegradable properties of the fibers, physical properties of the fabric, and process optimization of the thermal calendering. Biodegradation of cellulose has been intensively studied, and cellulose is believed to be

Hageun Suh

1997-01-01

51

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

Code of Federal Regulations, 2010 CFR

...manage records on nitrocellulose-base and cellulose-acetate base film? 1237.30 Section...manage records on nitrocellulose-base and cellulose-acetate base film? (a) The...base). (b) Agencies must inspect cellulose-acetate film periodically for...

2010-07-01

52

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; Mobarakeh, Laleh Ghasemi; Ramakrishna, Seeram

2014-02-01

53

Permeability of cellulose polymers: water vapour transmission rates.  

PubMed

The water vapour transmission rates (WVTR) through solvent cast polymer films prepared from cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate have been determined. They were influenced by the relative humidity, the substituent type and the extent of substitution. Increasing the relative humidity from 32 to 90% increased the WVTR 3 to 5 times depending on the polymer used. The WVTR increased in the order of butyrate less than propionate less than acetate. An increase in the extent of substitution with acetyl and/or butyryl groups resulted in an exponential decline in the WVTR. PMID:1974608

Sprockel, O L; Prapaitrakul, W; Shivanand, P

1990-03-01

54

Cellulose acetate electrospun fiber mats for controlled release of silymarin.  

PubMed

In this research, the silymarin-loaded electrospun cellulose acetate (CA) fibers were prepared which containing silymarin in various amounts (i.e., 2.5-20 wt.% based on the weight of CA powder). Incorporation of silymarin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the silymarin-loaded CA fibers were smooth. The average diameters of silymarin-loaded CA fiber ranged between 550-900 nm. No presence of the silymarin aggregates of any kind was observed on the surfaces of these fibers, suggesting that the silymarin was encapsulated well within the fibers. These results were confirmed by lowering the glass transition temperature and the melting temperature of the silymarin-loaded electrospun CA fibers which is determined by DSC technique. The release characteristic of silymarin from the silymarin-loaded CA fiber mats was investigated by the total immersion in the solution of 1/1 phosphate buffer/methanol medium pH 7.4 at 37 degrees C. The silymarin release from the silymarin-loaded electrospun CA fiber mat is monotonously increased to reach the maximum value at 480 min. The maximum amount of silymarin released from these materials increases with the increasing of initial silymarin loading in the spinning CA solutions. Since no aggregation of silymarin was found on the surface of the silymarin-loaded fibers, the release of the silymarin from fiber mats was mainly by the diffusion. PMID:22524059

Phiriyawirut, Manisara; Phaechamud, Thawatchai

2012-01-01

55

Net portal appearance of volatile fatty acids in sheep intraruminally infused with mixtures of acetate, propionate, isobutyrate, butyrate, and valerate.  

PubMed

The net portal appearance of volatile fatty acids (VFA) was investigated in four ruminally fistulated and multicatheterized sheep. During the experiments, the sheep were fed once every hour for 14 h and intraruminally infused with mixtures of VFA for the 12 h commencing 2 h after the initiation of the hourly feeding protocol. Paired arterial and portal blood samples were obtained hourly during the last 6 h of the experiments. In the control treatment (1), only water was infused intraruminally. In Treatments 2 through 4, the intraruminal infusion rates of propionate (40 mmol/h), isobutyrate (5 mmol/h), and valerate (5 mmol/h) were unchanged. In Treatments 2, 3, and 4, the acetate infusion rate was 100, 60, and 20 mmol/h, respectively, and the butyrate infusion rate was 10, 30, and 50 mmol/h, respectively. Thus, the infusion rate of VFA carbon was constant across Treatments 2 through 4. Portal recovery estimated from the increased net portal appearance in Treatments 2 through 4 compared to the control treatment was 85% for propionate and 60% for isobutyrate, and these recoveries were unaffected by treatment. The portal recovery of butyrate increased (from 21 to 32%) with increasing infusion rate of butyrate and decreasing infusion rate of acetate, as did the portal recovery of valerate (from 14 to 31%). The portal recovery of acetate was 55%, when measured as net portal appearance. Thus, it seems that the capacity for beta-oxidation in ruminal epithelium is limited, which would explain the increasing portal recovery of butyrate and valerate with increasing infusion rate of butyrate, when infusion rate of VFA carbon is unchanged. PMID:10834594

Kristensen, N B; Pierzynowski, S G; Danfaer, A

2000-05-01

56

In Situ Formation of Cellulose Acetate Carbamate Dry-RO (Trade Name) Membranes.  

National Technical Information Service (NTIS)

The in situ formation of cellulose acetate (CA) carbamates was investigated to increase the performance of Dry-RO membranes of CA. The CA casting solutions were charged with reversibly blocked isocyanate monomers, which when heated, formed CA carbamates. ...

R. E. Kesting J. Ditter A. Murray J. Newman

1980-01-01

57

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....

58

Application of cellulose acetate butyrate-based membrane for osmotic drug delivery  

Microsoft Academic Search

The release rate of drugs from an OROS is controlled by semipermeable membranes composed typically of cellulose acetate (CA) with various flux enhancers. Cellulose\\u000a acetate butyrate (CAB) was identified as a viable alternative. The CAB membrane matched the CA membrane in robustness but\\u000a had superior drying properties, offering particular advantages for thermolabile formulations. Studies were conducted to characterize\\u000a CAB membrane

Anant Shanbhag; Brian Barclay; Joanna Koziara; Padmaja Shivanand

2007-01-01

59

Synthesis and characterization of cellulose acetate–calcium carbonate hybrid nanocomposite  

Microsoft Academic Search

A hybrid nanocomposite composed of calcium carbonate (CaCO3) and cellulose acetate (CA) was fabricated by bubbling CO2 gas into the mixture of CA and Ca(OH)2 solution. Cellulose acetate–calcium carbonate (CA–CC) nanocomposite was characterized by spectral, thermal and optical methods. FTIR and XRD analysis confirmed the formation of the hybrid nanocomposite and XRD confirmed the formation of CaCO3 with calcite polymorph.

Amalraj John; Yi Chen; Jaehwan Kim

60

Effect of process engineering on the performance of natural fiber reinforced cellulose acetate biocomposites  

Microsoft Academic Search

Eco-friendly green\\/biocomposites were fabricated from chopped hemp fiber and cellulose ester biodegradable plastic through two process engineering approaches: powder impregnation through compression molding (process I) and extrusion followed by injection molding (process II). Cellulose ester, e.g. cellulose acetate (CA) plasticized with 30wt% citrate plasticizer (CAP) was used as the matrix polymer for biocomposite fabrication. Intimate mixing due to shear forces

A. K Mohanty; A Wibowo; M Misra; L. T Drzal

2004-01-01

61

Water soluble cellulose acetate: a versatile polymer for film coating.  

PubMed

The objective of this study was to investigate the use of water soluble cellulose acetate (WSCA) as a film coating material for tablets. Aspirin (ASA) tablets were prepared by direct compression and coated with either WSCA or HPMC (hydroxypropyl methylcellulose) dispersions. Coatings of 1-3%, depending on the intended application, were applied to the model drug (ASA) tablets employing a side-vented coating pan. Free films of WSCA, prepared by cast method, are crystal clear and, depending on the viscosity grade, are flexible, strong and durable. WSCA has the capability of forming free films without plasticizers and the films dry at room temperature. Glass transition temperature, Tg, was determined by differential scanning calorimetry. The Tg of WSCA is significantly higher relative to HPMC. Inclusion of plasticizer lowers the Tg of WSCA and effective plasticizers were PEG 400 and glycerin. Low viscosity WSCA was more soluble in water (25-30%) relative to medium viscosity WSCA (10-15%). WSCA solutions exhibited no increase in viscosity with an increase in temperature. Samples of coated (WSCA and HPMC) tablets and uncoated ASA cores were packaged for stability studies at room and elevated temperature storage. Physical stability of ASA tablets coated with 2:1 LV: MV (low viscosity: medium viscosity) WSCA formulations was better when compared to tablets coated with HPMC. Dissolution stability of WSCA coated ASA was similar to the physical stability results. After three months at elevated temperature (35 and 45 degrees C), the WSCA coated tablets complied with USP dissolution requirements for ASA, while the HPMC coated tablets did not. There was no difference in moisture (weight) gain of ASA tablets coated with either WSCA or HPMC. The WSCA coated tablets were not sticky or tacky, while the HPMC coated tablets were tacky and stuck together. PMID:17454061

Wheatley, Thomas A

2007-03-01

62

Photoluminescence of cellulose acetate and silica sphere composite  

NASA Astrophysics Data System (ADS)

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

Kang, Kwang-Sun

2014-08-01

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

2011-07-11

64

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

PubMed

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

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

2014-07-20

65

Preparation, characterization and effect of annealing on performance of cellulose acetate\\/sulfonated polysulfone and cellulose acetate\\/epoxy resin blend ultrafiltration membranes  

Microsoft Academic Search

Polymeric membranes based on cellulose acetate (CA)––sulfonated polysulfone blends at three different polymer compositions were prepared by solution blending and phase inversion technique, characterized and subjected to annealing at 70, 80 and 90 °C. The permeate water flux, separation of bovine serum albumin and its flux by the blend membranes before and after thermal treatment, have been compared and discussed.

R Mahendran; R Malaisamy; D Mohan

2004-01-01

66

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

67

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

PubMed

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

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

2013-03-01

68

Identification and Characterization of a Bacterial Transport System for the Uptake of Pyruvate, Propionate, and Acetate in Corynebacterium glutamicum?  

PubMed Central

The metabolism of monocarboxylic acids is of central importance for bacteria in their natural habitat as well as during biotechnological production. Although biosynthesis and degradation are well understood, the transport of such compounds is still a matter of discussion. Here we present the identification and characterization of a new transport system in Corynebacterium glutamicum with high affinity for acetate and propionate and with lower affinity for pyruvate. Biochemical analysis of this monocarboxylic acid transporter (MctC) revealed for the first time a quantitative discrimination of passive diffusion and active transport of acetate by bacterial cells. MctC is a secondary transporter and belongs to the class of sodium solute symporters, but it is driven by the electrochemical proton potential. The mctC gene is preceded by and cotranscribed with cg0952, a locus encoding a small membrane protein, and the transcription of the cg0952-mctC operon is under the control of the transcriptional regulators RamA and RamB. Both of these proteins directly bind to the promoter region of the operon; RamA is essential for expression and RamB exerts a slightly negative control on expression of the cg0952-mctC operon. mctC expression is induced in the presence of pyruvate and beneficial under substrate-limiting conditions for C. glutamicum.

Jolkver, Elena; Emer, Denise; Ballan, Stefan; Kramer, Reinhard; Eikmanns, Bernhard J.; Marin, Kay

2009-01-01

69

Identification and characterization of a bacterial transport system for the uptake of pyruvate, propionate, and acetate in Corynebacterium glutamicum.  

PubMed

The metabolism of monocarboxylic acids is of central importance for bacteria in their natural habitat as well as during biotechnological production. Although biosynthesis and degradation are well understood, the transport of such compounds is still a matter of discussion. Here we present the identification and characterization of a new transport system in Corynebacterium glutamicum with high affinity for acetate and propionate and with lower affinity for pyruvate. Biochemical analysis of this monocarboxylic acid transporter (MctC) revealed for the first time a quantitative discrimination of passive diffusion and active transport of acetate by bacterial cells. MctC is a secondary transporter and belongs to the class of sodium solute symporters, but it is driven by the electrochemical proton potential. The mctC gene is preceded by and cotranscribed with cg0952, a locus encoding a small membrane protein, and the transcription of the cg0952-mctC operon is under the control of the transcriptional regulators RamA and RamB. Both of these proteins directly bind to the promoter region of the operon; RamA is essential for expression and RamB exerts a slightly negative control on expression of the cg0952-mctC operon. mctC expression is induced in the presence of pyruvate and beneficial under substrate-limiting conditions for C. glutamicum. PMID:19028892

Jolkver, Elena; Emer, Denise; Ballan, Stefan; Krämer, Reinhard; Eikmanns, Bernhard J; Marin, Kay

2009-02-01

70

Transparent and flexible haptic array actuator made with cellulose acetate for tactile sensation  

NASA Astrophysics Data System (ADS)

This paper reports an array type film haptic actuator based on cellulose acetate. Suggested actuator can vibrate with faster response time and various frequencies to give a range of haptic feedbacks to users which can be used in touch screen devices. Fabrication process, performance evaluation and electrostatic behavior of haptic actuator are reported for tactile sensation. Cellulose acetate film is suitable for haptic actuator for its transparency, flexibility and high dielectric constant. An element of haptic actuator is made by using cellulose acetate film with patterned adhesive tape spacer, then haptic actuator elements arrayed to 3 x 3 to embed in haptic devices. Experiment to measure vibration acceleration is carried out on wide range of actuation frequency and voltage for single actuator to evaluate 3x3 array actuator.

Mohiuddin, Md; Kim, Hyun-Chan; Kim, Sang-Yeon; Kim, Jaehwan

2014-04-01

71

Plasticizing effect of ionic liquid on cellulose acetate obtained by melt processing.  

PubMed

Cellulose acetate (CA) plasticized by 1-butyl-3-methylimidazolium chloride (BMIMCl) and with diethylphtalate (DEP) was obtained by melt processing at 150°C. The effect and the interaction of ionic liquid with the cellulose acetate and their influence on structural, thermo-mechanical, rheological and tensile properties of CA materials were investigated. Ionic liquid (BMIMCl) has shown a good plasticization and more efficient destruction of the crystalline structure of cellulose acetate than the DEP plasticized CA. BMIMCl interacts intensively with CA molecules due to the pronounced van der Waals interactions, hydrogen bonding and electrostatic nature of ionic liquid. The tensile test and the low Young's modulus for plasticized CA suggest a strong reduction of the interaction between the CA chains due to the presence of the ionic liquid. PMID:24751249

Bendaoud, Amine; Chalamet, Yvan

2014-08-01

72

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

73

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

74

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

75

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

76

A concise asymmetric synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl Acetate and propionate, the sex pheromones of pine sawflies.  

PubMed

(2S,3S,7S)-3,7-Dimethylpentadecan-2-yl acetate (2) and its propionate analogue (3) are the main sex pheromones of all Neodiprion species and Diprion similes, respectively. Starting from (S)-malic acid and employing a highly chemo-, regio-, and stereoselective tandem ester reduction-epoxide formation-reductive epoxide-opening reaction protocol, an efficient total synthesis of (2S,3S,7S)-2 and -3 is reported herein. PMID:15153034

Huang, Pei-Qiang; Lan, Hong-Qiao; Zheng, Xiao; Ruan, Yuan-Ping

2004-05-28

77

Water and ions transport mechanism in hyperfiltration with symmetric cellulose acetate membranes  

Microsoft Academic Search

Hyperfiltration is carried out under reverse osmotic conditions by the application of mechanical energy to force the solvent from higher to lower concentration of solute across semipermeable membranes. In the present investigation, experimental work has been performed to measure the water and inorganic cation transport fluxes across cellulose acetate homogeneous hyperfiltration membranes. The osmosis, reverse osmosis, kinetic conductance and membrane

M. Ashraf Chaudry

2002-01-01

78

An ATR-FTIR study of water in cellulose acetate membranes prepared by phase inversion  

Microsoft Academic Search

The state of water in the active layer of a series of cellulose acetate asymmetric membranes, prepared by the phase inversion process, was investigated using attenuated total reflection infrared spectroscopy (ATR-FTIR). The relative amount of water present in the active layer depends on the inherent surface or skin layer morphology; the more permeable ultrafiltration asymmetric membranes contain more water compared

Damien Murphy; Maria Norberta de Pinho

1995-01-01

79

Effect of Additive Concentration on Cellulose Acetate Blend Membranes-Preparation, Characterization and Application Studies  

Microsoft Academic Search

Ultrafiltration techniques have particular advantages for simultaneous purification, concentration, and fractionation of macromolecules. A comparative study is presented on novel ultrafiltration polymeric blend membranes based on cellulose acetate (CA) prepared in the absence and presence of polymeric additives such as polyethylene Glycol 200 (PEG) and polyvinylpyrrolidone (PVP) by phase inversion technique using N,N?-dimethylformamide (DMF) as solvent. Polymer blend composition, additive

S. Vidya; A. Vijayalakshmi; A. Nagendran; D. Mohan

2008-01-01

80

Separation of nutmeg essential oil and dense CO 2 with a cellulose acetate reverse osmosis membrane  

Microsoft Academic Search

The association of membrane separation processes to the supercritical fluid extraction of essential oils from vegetable matrices can be an alternative to the reduction of recompression costs derived from the depressurization step necessary for the recovering of the extracts. In this work, a cellulose acetate reverse osmosis membrane was applied to perform the separation of nutmeg essential oil and dense

Cinthia Bittencourt Spricigo; Ariovaldo Bolzan; Ricardo Antonio Francisco Machado; Luiz Henrique Castelan Carlson; José Carlos Cunha Petrus

2001-01-01

81

THE DYNAMIC FRICTION BETWEEN CELLULOSE ACETATE YARN AND A CYLINDRICAL METAL SURFACE  

Microsoft Academic Search

Measurement of the dynamic friction between cellulose acetate yarn and a chromium plated cylinder, using the Buckle and Pollitt tester, is described. Trials determining the variation of friction with (a) initial tension, (b) radius of test surface, (c) yarn speed, (d) twist, (e) oil content and (f) oil viscosity have been carried out.The results of trials (a) and (b) have

A. F. W. Coulson; D. G. Lyne

1955-01-01

82

Decolorization of Distillery Effluent Using Poly(Vinyl Chloride) and Cellulose Acetate Phthalate as Adsorbents  

Microsoft Academic Search

Decolorization of distillery effluents, using low cost polymer adsorbents, is one of the challenging areas for environmental technologists. Untreated distillery effluents are harmful to the environment, causing foul smell, spoiling fresh water sources and killing aquatic life. The color of distillery effluents have been decolorized by using polymer based adsorbents, such as poly(vinyl chloride) (PVC) and cellulose acetate phthalate (CAP),

Valluru Ravi; Subhash Chandra Bose; T. M. Pramod Kumar; Siddaramaiah

2006-01-01

83

Electrospun cellulose acetate phthalate fibers for semen induced anti-HIV vaginal drug delivery  

Microsoft Academic Search

Despite many advances in modern medicine, human immunodeficiency virus (HIV) still affects the health of millions of people world-wide and much effort is put in developing methods to either prevent infection or to eradicate the virus after infection has occurred. Here, we describe the potential use of electrospun cellulose acetate phthalate (CAP) fibers as a tool to prevent HIV transmission.

Chaobo Huang; Stefaan J. Soenen; Ellen van Gulck; Guido Vanham; Joanna Rejman; Serge Van Calenbergh; Chris Vervaet; Tom Coenye; Hans Verstraelen; Marleen Temmerman; Jo Demeester; Stefaan C. De Smedt

84

Hydration and plasticization effects in cellulose acetate: a solid-state NMR study  

Microsoft Academic Search

The conjoint effects of water and diethyl phthalate (DEP) plasticizer on molecular motion in cellulose acetate (CA) have been examined. 1H, 13C and cross polarization NMR data reveal a number of interesting features. As in other hydrated polymers, there are different types of water ranging from tightly bound to bulk-like water in CA. Both tightly and loosely bound water can

Christopher M. Keely; Xiaoqing Zhang; Vincent J. McBrierty

1995-01-01

85

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

PubMed

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

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

2014-07-01

86

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

87

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

88

Acetate, propionate and butyrate in plasma: determination of the concentration and isotopic enrichment by gas chromatography/mass spectrometry with positive chemical ionization.  

PubMed

This study describes a rapid and simple method to determine short-chain fatty acid (SCFA) concentrations and their isotopic enrichments (M(0) + 1 and M(0) + 2) in human plasma. Sample preparation involves SCFA extraction and derivatization with 1-(tert-butyldimethylsilyl)imidazole. Gas chromatography/mass spectrometry was performed using chemical ionization with ammonia as the reagent gas. Outstanding resolution, excellent linearity and good detection limits were obtained. Inter-assay and intra-assay repeatability was below 10% and 3% respectively for SCFA concentration. Inter-assay repeatability was below 5%, 4%, 6%, and 14% for isotopic enrichment determination of [1-(13)C]acetate and [1,2-(13)C(2)]acetate, [1-(13)C]propionate and [1-(13)C]butyrate respectively, with intra-assay being below 6%. Such SCFA concentrations and isotopic enrichments were determined in the plasma of rats infused with a (13)C-labeled SCFA. The turnovers of acetate, propionate and butyrate in rats were 19 micromol kg(-1) min(-1), 2.6 micromol kg(-1) min(-1), 0.3 micromol kg(-1) min(-1) respectively. PMID:11473403

Pouteau, E; Meirim, I; Métairon, S; Fay, L B

2001-07-01

89

In situ modification on cellulose acetate hollow fiber membrane modified with phospholipid polymer for biomedical application  

Microsoft Academic Search

The hollow fiber membrane (HFM) made from synthetic polymers need improvement in terms of hemocompatibility or biocompatibihty, for use in the medical field. In this study, cellulose acetate (CA) HFM modified with the water-soluble amphiphilic 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer (poly (MPC-co-n-butyl methacrylate) (PMB80, MPC:BMA=80:20 (mol%)) was prepared by a dry-jet wet spinning process. The PMB80 was coated on the CA

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

2005-01-01

90

Kinetics of release of a model disperse dye from supersaturated cellulose acetate matrices  

Microsoft Academic Search

A study has been made of the kinetics of release into water of a model disperse dye (4-aminoazobenzene) from supersaturated solvent-cast cellulose acetate films at room temperature. Excess dye was introduced into the polymer matrix by: (i) sorption from aqueous solution at 100°C; (ii) sorption from the vapour phase at 110°C; or (iii) prior dissolution in the casting solvent. The

K. G Papadokostaki; J. H Petropoulos

1998-01-01

91

Towards green membranes: preparation of cellulose acetate ultrafiltration membranes using methyl lactate as a biosolvent  

Microsoft Academic Search

Ultrafiltration membranes were prepared using cellulose acetate (CA) as a polymer, LiCl and CaCl2 as porogens and methyl-(S)-lactate as a solvent. CA, methyl lactate and the porogens used in this work are obtained from renewable resources; they are biodegradable, non-toxic and non-volatile organic compounds. Flat sheet ultrafiltration membranes were prepared by the phase inversion technique. A molecular weight cut-off between

Y. Medina-Gonzalez; P. Aimar; J.-F. Lahitte; J.-C. Remigy

2011-01-01

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

Nonsolvent effects on morphology of cellulose acetate films prepared by dry-cast process  

Microsoft Academic Search

Cellulose acetate (CA) porous films were prepared by a dry-cast process from CA\\/acetone\\/nonsolvent systems. Isopropanol, ethanol and water were used as the nonsolvent and their effects on the formation of the porous structure of the CA matrix were investigated. As acetone evaporated from the solution, the mass ratios of both CA and the nonsolvent increased, finally inducing a porous structure

C. F. Wang; Y. An; Q. H. Li; S. J. Wan; W. X. Chen; X. D. Liu

2012-01-01

94

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

95

Electrospun membrane of cellulose acetate for heavy metal ion adsorption in water treatment  

Microsoft Academic Search

Cellulose acetate (CA) nonwoven membrane for heavy metal ion adsorption was prepared by electrospinning and surface modification with poly(methacrylic acid) (PMAA). The morphology and graft modification of the membrane were characterized by SEM and ATR-FTIR. The adsorption of heavy metal ions Cu2+, Hg2+ and Cd2+ on this membrane was investigated. The adsorption capacity increased with the increasing of initial pH

Ye Tian; Min Wu; Ruigang Liu; Yanxiang Li; Deqian Wang; Junjun Tan; Rongcheng Wu; Yong Huang

2011-01-01

96

Study of cellulose acetate hydrogen phthalate(CAP)-poly methyl methacrylate (PMMA) blends by thermogravimetric analysis  

Microsoft Academic Search

Thermal degradation of cellulose acetate hydrogen phthalate (CAP) and its blends with poly methyl methacrylate (PMMA) has been investigated by thermogravimetric analysis. TG\\/DTG curves show two decomposition stages for pure CAP. Decomposition behaviour is changed with addition of PMMA. For 90\\/10 CAP\\/PMMA and 70\\/30 CAP\\/PMMA blends, there are three decomposition stages. With further addition of PMMA, the decomposition behaviour shifts

R Vijayalakshmi Rao; P. V Ashokan; M. H Shridhar

2000-01-01

97

Distribution analysis of cellulose acetate phthalate by ion-exclusion-moderated size exclusion chromatography  

Microsoft Academic Search

Ion-exclusion is the electrostatic repulsive interaction between a charged polymer and charges of the same sign on the surface of a column packing. Controlled ion-exclusion allows compensation of hydrophobic adsorption in size exclusion chromatography of negatively charged cellulose acetate phthalate (CAP) polymers in acetone\\/water\\/LiCl (80\\/20) as a mobile phase. Properly selected low-ionic-strength conditions provide correct separation in size-exclusion mode also

B Porsch; I Hillang; A Karlsson; L.-O Sundelöf

2002-01-01

98

Properties of heat-humidity cured cellulose acetate phthalate free films  

Microsoft Academic Search

Cellulose acetate phthalate (CAP) free films containing diethyl phthalate (DEP) or triethyl citrate (TEC) as the plasticizer were prepared by the spray method. The chemical and mechanical properties of films were compared following heat-only (50°C for 24 h) and heat-humidity curing (50°C\\/75% RH for 24 h) conditions. The surface roughness of the heat-humidity cured films decreased compared to that of

Jiping Liu; Robert O Williams

2002-01-01

99

Long-term stability of heat–humidity cured cellulose acetate phthalate coated beads  

Microsoft Academic Search

The objective of this study was to investigate the influence of stability storage conditions on the enteric release of heat–humidity cured cellulose acetate phthalate (CAP) coated beads. Theophylline beads were coated with 25 or 35% diethyl phthalate plasticized CAP dispersion (Aquacoat® CPD), and cured at a heat–humidity condition (50°C\\/75% RH) for 24h. The cured beads were then stored in various

Jiping Liu; Robert O Williams

2002-01-01

100

Drug Release from Tablets Containing Cellulose Acetate Phthalate As an Additive or Enteric-Coating Material  

Microsoft Academic Search

A formulation containing cellulose acetate phthalate for preparing enteric-coated granules was developed with the use of granulation and microencapsulation techniques. Drug release from tablets or tabletted microcapsules was measured in a disintegration apparatus and an in vitro variable-pH release simulator of the flow type. The release mechanism for the tablets or tabletted microcapsules was determined with the Higuchi matrix model,

Shan-Yang Lin; Y. Kawashima

1987-01-01

101

Enzymatic degradation of cellulose acetate plastic by Novel degrading bacterium Bacillus sp. S2055  

Microsoft Academic Search

Cellulose acetate (CA)-degrading bacteria were isolated from samples obtained from environments at a population size of 6.7 × 101 to 1.0 × 108 halo-forming cfu\\/ml-water or g-solid, suggesting their ubiquitous presence. The classification of 35 isolated strains of CA-degrading bacteria into 15 genera indicates that CA-degrading activity is over a wide range of taxonomical groups. From these isolates, Bacillus sp.

Tomonori Ishigaki; Wataru Sugano; Michihiko Ike; Masanori Fujita

2000-01-01

102

Polyethersulfone (PES)\\/cellulose acetate phthalate (CAP) blend ultrafiltration membranes: Preparation, morphology, performance and antifouling properties  

Microsoft Academic Search

Polyethersulfone (PES)\\/cellulose acetate phthalate (CAP) blend ultrafiltration (UF) membranes were prepared with phase inversion induced by immersion precipitation method. CAP was employed to improve the hydrophilicity of PES membranes. Polyvinylpyrrolidone (PVP) was selected as pore former. Dimethylacetamide (DMAc) and water+isopropyl alcohol (IPA) (80\\/20vol%) were used as solvent and coagulant respectively. The contact angle measurements indicate that the hydrophilicities of PES\\/CAP

A. Rahimpour; S. S. Madaeni

2007-01-01

103

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

NASA Technical Reports Server (NTRS)

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

Wydeven, T.; Leban, M.

1973-01-01

104

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

PubMed

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

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

2014-09-01

105

Mechanical properties, biocompatibility, and biodegradation of cross-linked cellulose acetate-reinforced polyester composites.  

PubMed

Composites of treated (cross-linked) cellulose acetate (t-CA) and acrylic acid-grafted poly(hydroxyalkanoate) (PHA-g-AA/t-CA) exhibited noticeably superior mechanical properties compared with PHA/CA composites due to greater compatibility between the two components. The dispersion covering of t-CA in the PHA-g-AA matrix was highly homogeneous as a result of condensation reactions. Human lung fibroblasts (FBs) were seeded on these two series of composites to characterize the biocompatibility properties. In a time-dependent course, the FB proliferation results demonstrated higher performance from the PHA/CA series of composites than from the PHA-g-AA/t-CA composites. The water resistance of PHA-g-AA/t-CA was higher than that of PHA/CA, although the weight loss of both composites buried in Acetobacter pasteurianus (A. pasteurianus) indicated that they were both biodegradable, especially at higher levels of cellulose acetate substitution. The PHA/CA and PHA-g-AA/t-CA composites were more biodegradable than pure PHA, implying a strong connection between cellulose acetate content and biodegradability. PMID:24708950

Wu, Chin-San

2014-05-25

106

Investigation of size effect on film type haptic actuator made with cellulose acetate  

NASA Astrophysics Data System (ADS)

The most important factor in haptic interaction with hand-held devices is to develop a thin film type actuator which can be easily inserted into the devices and create vibrotactile signals with wide frequency bandwidth. This paper reports a film type vibrotactile actuator which is tiny enough to be embedded into small hand-held devices. The vibration mechanism and experiment results for the suggested vibrotactile actuator are explained. The aim of the actuator is to convey a vibrotactile force greater than a human’s vibrotactile threshold with broad frequency bandwidth to users. To achieve the requirement, we fabricate a film type vibrotactile actuator with cellulose acetate. When an AC voltage is applied to the actuator, the cellulose acetate film gets charged and then generates vibration. The suggested vibrotactile actuator is fabricated in two sizes: 50 mm × 25 mm and 25 mm × 25 mm. For each size of actuator, three kinds of actuator are fabricated with different pillar materials to support the cellulose acetate films. An experiment for measuring vibrational amplitude is conducted over a wide frequency range of actuation voltage. It is known that the proposed film type actuator is feasible for haptic application in the small hand-held devices.

Kim, Sang-Youn; Kim, Jaehwan; Kim, Ki-Baek

2014-04-01

107

Development of a gel permeation chromatographic assay to achieve mass balance in cellulose acetate phthalate stability studies  

Microsoft Academic Search

Cellulose acetate phthalate (CAP, cellulose acetate 1,2-benzenedicarboxylate) is a common polymeric oral tablet coating. CAP is also a vaginal microbicide candidate that potently inhibits HIV-1 proliferation. This paper describes the development of a precise, stability-indicating gel permeation chromatography (GPC) assay for CAP. During accelerated stability studies monitored by separate reversed-phase high performance liquid chromatography (RP-HPLC) and GPC analyses, an apparent

James W. Mayhew; Lulu T. Gideon; Bryan Ericksen; John J. Hlavaty; Simon M. Yeh; Charles G. Chavdarian; Nathan Strick; A. Robert Neurath

2009-01-01

108

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

109

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

110

Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.  

PubMed

Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO(2) plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0-15 min for CTA and 5-60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO(2) plasma treatment whereas CF(4) plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained. PMID:16290368

Olde Riekerink, M B; Engbers, G H M; Wessling, M; Feijen, J

2002-01-15

111

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

112

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

2010-01-01

113

Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes.  

PubMed

The mechanical properties and hydraulic permeabilities of biomaterial scaffolds play a crucial role in their efficacy as tissue engineering platforms, separation processors, and drug delivery vehicles. In this study, electrospun cellulose acetate fiber meshes of random orientations were created using four different concentrations, 10.0, 12.5, 15.0, and 17.5 wt % in acetone or ethyl acetate. The tensile mechanical properties and the hydraulic permeabilities of these meshes were measured, and a multiscale model was employed to predict their mechanical behavior. Experimentally, the elastic modulus ranged from 3.5 to 12.4 MPa depending on the polymer concentration and the solvent. Model predictions agreed well with the experimental measurements when a fitted single-fiber modulus of 123.3 MPa was used. The model also predicted that changes in fiber alignment may result in a 3.6-fold increase in the elastic modulus for moderately aligned meshes and a 8.5-fold increase for highly align meshes. Hydraulic permeabilities ranged from 1.4 x 10(-12) to 8.9 x 10(-12) m(2) depending on polymer concentration but not the choice of solvent. In conclusion, polymer concentration, fiber alignment, and solvent have significant impact on the mechanical and fluid transport properties of electrospun cellulose acetate fiber meshes. PMID:22887702

Stylianopoulos, Triantafyllos; Kokonou, Maria; Michael, Stefanos; Tryfonos, Antonia; Rebholz, Claus; Odysseos, Andreani D; Doumanidis, Charalambos

2012-11-01

114

Application of cellulose acetate to the selective adsorption and recovery of Au(III).  

PubMed

Cellulose acetyl derivatives were examined for the selective recovery of Au(III) from acidic chloride solutions as an adsorbent, and cellulose acetate fibers (CAF) were found to be effective for the separation of Au(III) from other metal ions, including the precious metal ions Pt(IV) and Pd(II). The amount of Au(III) adsorbed by the fibers increased with an increase in the hydrochloric acid concentration, but decreased with an increase in the ionic strength of the solution. The adsorption of Au(III) onto CAF took place quickly and an adsorption equilibrium was reached within 1h. The maximum adsorption capacity of Au(III) was determined to be 110mg/g at 2M hydrochloric acid. The loaded Au(III) was readily recovered by incineration. PMID:25037414

Yang, Jian; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2014-10-13

115

Performances of poly(vinylpyrrolidone-co-vinyl acetate)-cellulose acetate blend membranes in the pervaporation of ethanol–ethyl tert-butyl ether mixtures  

Microsoft Academic Search

High performance pervaporation membranes for the selective removal of ethanol from ethyl t-butyl ether (ETBE) were prepared by blending cellulose acetate with poly(vinylpyrrolidone-co-vinyl acetate) in different proportions and studied in sorption and pervaporation of ethanol–ETBE mixtures of compositions ranging from 5 to 25wt% ethanol. The membrane performances are improved when the copolymer content is higher due to strong flux enhancement.

Quang-Trong Nguyen; Robert Clément; Irwan Noezar; Pierre Lochon

1998-01-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

117

Adsorption of N-alkylpyridinium chlorides from water and salt solutions on cellulose acetate ultrafiltration membranes  

SciTech Connect

A study has been made of the adsorption of three homologues in the N-alkylpyridinium chloride series from water and salt solutions, over a wide range of concentrations, on cellulose acetate ultrafiltration membranes, Grades UAM-500 and UAM-150. When adsorption takes place from true solutions, the membrane surface is hydrophobized. In the region of micellar solutions, nonassociated molecules and micelles are adsorbed in the mesopores and supermicropores, forming a mosaic adsorption layer. The thickness of the modifying layer depends on the length of the hydrophobic radical and on the composition of the system.

Klimenko, N.A.; Yaroshenko, N.A.; Kondratova, T.B.

1988-09-01

118

Cellulose Acetate Decoupler for On-Column Electrochemical Detection in Capillary Electrophoresis  

PubMed Central

A new decoupler for on-column electrochemical detection in capillary electrophoresis is presented. The decoupler is constructed by etching a series of holes through the side of the separation capillary with a CO2 laser and then coating the holes with cellulose acetate. The decoupler shows isolation of the detection circuit for separation currents up to 30 ?A. Detection limits below 1 nM were achieved for four model compounds, including anions, neutrals, and cations, using the laser-etched decoupler. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture.

Osbourn, Damon M.; Lunte, Craig E.

2008-01-01

119

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

Microsoft Academic Search

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

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

2003-01-01

120

Development of a LCST membrane forming system for cellulose acetate ultrafiltration hollow fiber  

Microsoft Academic Search

A novel lower critical solution temperature (LCST) membrane forming system containing cellulose acetate (CA)\\/poly (vinyl pyrrolidone) (PVP 360K)\\/N-methyl-2-pyrrolidone (NMP)\\/1,2-propanediol with a weight ratio of 24.0:5.0:62.6:8.4 had been developed. CA hollow fiber ultrafiltration (UF) membranes were fabricated using the dry–wet spinning technique. The fibers were post-treated with a 200mg\\/L hypochlorite solution over a period of 6h at pH 7. The experimental

Jian-Jun Qin; Maung Htun Oo; Yi-Ming Cao; Leng-Siang Lee

2005-01-01

121

Cellulose acetate\\/poly(methyl methacrylate) interpenetrating networks: synthesis and estimation of thermal and mechanical properties  

Microsoft Academic Search

IPN-type composites consisting of cellulose acetate (CA) and poly(methyl methacrylate; PMMA) were successfully synthesized\\u000a in film form. In this synthesis, a mercapto group (SH)-containing CA, CA-MA, was prepared in advance by esterification of\\u000a CA with mercaptoacetic acid, and then intercomponent cross-linking between CA-MA and PMMA was attained by thiol–ene polymerization\\u000a of methyl methacrylate (MMA) onto the CA-MA substrate. For comparison,

Dan Aoki; Yoshikuni Teramoto; Yoshiyuki Nishio

122

Cellulose acetate decoupler for on-column electrochemical detection in capillary electrophoresis.  

PubMed

A new decoupler for on-column electrochemical detection in capillary electrophoresis is presented. The decoupler is constructed by etching a series of holes through the side of the separation capillary with a CO2 laser and then coating the holes with cellulose acetate. The decoupler shows isolation of the detection circuit for separation currents up to 30 microA. Detection limits below 1 nM were achieved for four model compounds, including anions, neutrals, and cations, using the laser-etched decoupler. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture. PMID:11791566

Osboum, D M; Lunte, C E

2001-12-15

123

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

2013-01-01

124

Dispersibility and emulsion-stabilizing effect of cellulose nanowhiskers esterified by vinyl acetate and vinyl cinnamate.  

PubMed

The surface of cotton cellulose nanowhiskers (CNW's) was esterified by vinyl acetate (VAc) and vinyl cinnamate (VCin), in the presence of potassium carbonate as catalyst. Reactions were performed under microwave activation and monitored by Fourier transform infrared (FT-IR) spectroscopy. The supramolecular structure of CNW's before and after modification was characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). Distinctively from the acetylation treatment, an increase in particles dimensions was noted after esterification with VCin, which was assigned to ?-? stacking interactions that may exist between cinnamoyl moieties. The dispersibility and emulsion stabilizing effect of acylated CNW's was examined in ethyl acetate, toluene, and cyclohexane, three organic solvents of medium to low polarity. The acylated nanoparticles could never be dispersed in toluene nor cyclohexane, but they formed stable dispersions in ethyl acetate while remaining dispersible in water. Stable ethyl acetate-in-water, toluene-in-water, and cyclohexane-in-water emulsions were successfully prepared with CNW's grafted with acetyl moieties, whereas the VCin-treated particles could stabilize only the cyclohexane-in-water emulsions. The impact of esterification treatment on emulsion stability and droplets size was particularly discussed. PMID:23883187

Sèbe, Gilles; Ham-Pichavant, Frédérique; Pecastaings, Gilles

2013-08-12

125

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

PubMed

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

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

2014-04-01

126

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

2012-02-01

127

Formation of micro- and nano-spheric particles (filter dust) during the preparation of cellulose acetate membranes  

Microsoft Academic Search

Membranes were prepared from six samples of cellulose acetate (CA) differing in their average molecular weight (75–260kg\\/mole) and molecular weight distribution using methyl acetate as solvent and 2-propanole as precipitant. The routes through the phase diagram and the evaporation times were varied in these experiments. Electron microscopy demonstrates that the amount of filter dust (CA particles deposited on the membrane

J. Eckelt; S. Loske; M. C. Gonçalves; B. A. Wolf

2003-01-01

128

Method for the preparation of cellulose acetate flat sheet composite membranes for forward osmosis—Desalination using MgSO 4 draw solution  

Microsoft Academic Search

A lab scale method for the preparation of defect free flat sheet composite membranes for forward osmosis (FO) has been developed. Membranes containing a thin layer of cellulose acetate (CA) cast on a nylon fabric of 50?m thick were prepared by phase inversion in water. Cellulose acetate (CA) membranes with an overall thickness of 70–80?m have been prepared with lactic

M. Sairam; E. Sereewatthanawut; K. Li; A. Bismarck; A. G. Livingston

2011-01-01

129

Low Vacuum Annealing of Cellulose Acetate on Nickel Towards Transparent Conductive CNT-Graphene Hybrid Films.  

PubMed

We report a versatile method based on low vacuum annealing of cellulose acetate on nickel (Ni) surface for rapid fabrication of graphene and carbon nanotube (CNT)-graphene hybrid films with tunable properties. Uniform films mainly composed of tri-layer graphene can be achieved via a surface precipitation of dissociated carbon at 800 °C for 30 seconds under vacuum conditions of ?0.6 Pa. The surface precipitation process is further found to be efficient for joining the precipitated graphene with pre-coated CNTs on the Ni surface, consequently, generating the hybrid films. As expected, the hybrid films exhibit substantial opto-electrical and field electron emission properties superior to their individual counterparts. The finding suggests a promising route to hybridize the graphene with diverse nanomaterials for constructing novel hybrid materials with improved performances. PMID:24852931

Nguyen, Duc Dung; Tiwari, Rajanish N; Matsuoka, Yuki; Hashimoto, Goh; Rokuta, Eiji; Chen, Yu-Ze; Chueh, Yu-Lun; Yoshimura, Masamichi

2014-06-25

130

A novel polymer based on MtCu2+/cellulose acetate with antimicrobial activity.  

PubMed

Cellulose acetate (CA)/copper montmorillonite modified (MtCu(2+)) antimicrobial nanocomposites for food packaging containing 1, 3 and 5 wt.% nanoparticles were prepared by solution casting technique. X-ray diffraction (XRD) and transmission electron microscopy revealed the existence of intercalated and no intercalated clay form in the CA matrix. The thermal stability of the MtCu(2+)/CA nanocomposites was measured by TGA and DSC, which indicated that the nanocomposites were less thermally stable in comparison to CA pure. Mechanical testing of material did not show differences when MtCu(2+) was added in CA. On the other hand, antimicrobial effect was observed for nanocomposites films, obtaining a 98% reduction against Escherichia coli. PMID:24507287

Bruna, J E; Galotto, M J; Guarda, A; Rodríguez, F

2014-02-15

131

Cell Growth on In Situ Photo-Cross-Linked Electrospun Acrylated Cellulose Acetate Butyrate.  

PubMed

In this study, electrospinning was combined with UV curing technology for producing in situ photo cross-linked fibers from methacrylated cellulose acetate butyrate (CABIEM). ECV304 and 3T3 cells were seeded on electrospun fibrous scaffolds. Collagen modified CABIEM fibers were also prepared for improving cell adhesion and proliferation. Cross-linking and the morphology of the fibers were characterized by ATR-FT-IR spectrometry and environmental scanning electron microscopy (ESEM). The cytotoxicity of the fibers was examined using the MTT cytotoxicity assay. According to the results, electrospun fibrous scaffolds are non-toxic and cell viability depends on the amount of collagen. It was found that cell adhesion and cell growth were enhanced as the collagen percentage was increased. PMID:21457618

Cakmakç?, Emrah; Güngör, Atilla; Kayaman-Apohan, Nilhan; Kuruca, Serap Erdem; Cetin, Muzaffer Beyza; Dar, Kadriye Akgün

2011-03-31

132

Electrospun antibacterial polyurethane-cellulose acetate-zein composite mats for wound dressing.  

PubMed

In this study, an antibacterial electrospun nanofibrous scaffolds with diameters around 400-700 nm were prepared by physically blending polyurethane (PU) with two biopolymers such as cellulose acetate (CA) and zein. Here, PU was used as the foundation polymer, was blended with CA and zein to achieve desirable properties such as better hydrophilicity, excellent cell attachment, proliferation and blood clotting ability. To prevent common clinical infections, an antimicrobial agent, streptomycin sulfate was incorporated into the electrospun fibers and its antimicrobial ability against the gram negative and gram positive bacteria were examined. The interaction between fibroblasts and the PU-CA and PU-CA-zein-drug scaffolds such as viability, proliferation, and attachment were characterized. PU-CA-zein-drug composite nanoscaffold showed enhanced blood clotting ability in comparison with pristine PU nanofibers. The presence of CA and zein in the nanofiber membrane improved its hydrophilicity, bioactivity and created a moist environment for the wound, which can accelerate wound recovery. PMID:24507360

Unnithan, Afeesh Rajan; Gnanasekaran, Gopalsamy; Sathishkumar, Yesupatham; Lee, Yang Soo; Kim, Cheol Sang

2014-02-15

133

Effect of adhesive on the morphology and mechanical properties of electrospun fibrous mat of cellulose acetate.  

PubMed

Ultrafine fibers of cellulose acetate/poly(butyl acrylate) (CA/PBA) composite in which PBA acted as an adhesive and CA acted as a matrix, were successfully prepared as fibrous mat via electrospinning. The morphology observation from the electrospun CA/PBA composite fibers, after treatment with heat hardener, revealed that the fibers were cylindrical and had point-bonded structures. SEM, FT-IR spectra, Raman spectra, TGA analysis, and mechanical properties measurement were used to study the different properties of hybrid mats. The tensile strength of blend fibrous electrospun mats was found to be effectively increased. This resultant enhancement of the mechanical properties of polymer fibrous mats, caused by generating the point-bonded structures (due to adhesive), could increase the number of potential applications of mechanically weak electrospun CA fibers. PMID:21718972

Baek, Woo-Il; Pant, Hem Raj; Nam, Ki-Taek; Nirmala, R; Oh, Hyun-Ju; Kim, Il; Kim, Hak-Yong

2011-09-27

134

Electrospun cellulose acetate nanofibers: the present status and gamut of biotechnological applications.  

PubMed

Cellulose acetate (CA) has been a material of choice for spectrum of utilities across different domains ranging from high absorbing diapers to membrane filters. Electrospinning has conferred a whole new perspective to polymeric materials including CA in the context of multifarious applications across myriad of niches. In the present review, we try to bring out the recent trend (focused over last five years' progress) of research on electrospun CA fibers of nanoscale regime in the context of developmental strategies of their blends and nanocomposites for advanced applications. In the realm of biotechnology, electrospun CA fibers have found applications in biomolecule immobilization, tissue engineering, bio-sensing, nutraceutical delivery, bioseparation, crop protection, bioremediation and in the development of anti-counterfeiting and pH sensitive material, photocatalytic self-cleaning textile, temperature-adaptable fabric, and antimicrobial mats, amongst others. The present review discusses these diverse applications of electrospun CA nanofibers. PMID:23318668

Konwarh, Rocktotpal; Karak, Niranjan; Misra, Manjusri

2013-01-01

135

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

PubMed

Cellulose acetate (CA) fibers loaded with the ester prodrugs of naproxen, including methyl ester, ethyl ester and isopropyl 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 fibers were investigated by means of SEM, DSC, XRD and FTIR, as well as the studies of the drug release properties. The results indicated that the morphology and diameter of the fibers were influenced by the concentration of spinning solution, applied voltage, electrospun solvent and the surfactants. The average diameters of the fibers ranged between 100 and 500 nm for three prodrugs. There was good compatibility between CA and three prodrugs in the blended fibers, respectively. In vitro release indicated that constant drug release from the fiber was observed over 6 days. The prodrugs were successfully encapsulated into the fibers, and this system was stable in terms of effectiveness in release. PMID:20499138

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

2010-08-01

136

Identification and Characterization of a Bacterial Transport System for the Uptake of Pyruvate, Propionate, and Acetate in Corynebacterium glutamicum  

Microsoft Academic Search

The metabolism of monocarboxylic acids is of central importance for bacteria in their natural habitat as well as during biotechnological production. Although biosynthesis and degradation are well understood, the trans- port of such compounds is still a matter of discussion. Here we present the identification and characterization of a new transport system in Corynebacterium glutamicum with high affinity for acetate

Elena Jolkver; Denise Emer; Stefan Ballan; Reinhard Kramer; Bernhard J. Eikmanns; Kay Marin

2009-01-01

137

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

138

Chlorophyll Photochemistry in Condensed Media: Triplet State Quenching and Electron Transfer to Quinone in Cellulose Acetate Films.  

National Technical Information Service (NTIS)

Chlorophyll a was incorporated into cellulose acetate films and the triplet decay and electron transfer to p-benzoquinone in aqueous solution was studied using laser flash photolysis and ESR. The triplet was found to decay by first order kinetics with the...

G. Cheddar F. Castelli G. Tollin

1979-01-01

139

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

Microsoft Academic Search

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

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

140

Sorption of sodium dodecyl sulfate by polyaniline–cellulose acetate polymeric blends as seen by UV–vis spectroscopy  

Microsoft Academic Search

The interaction between sodium dodecyl sulfate (SDS) and a blend of polyaniline (PANi) and cellulose acetate (CA) is discussed. This interaction is shown to lead to a red shift of the maximum absorption wavelength in the visible spectrum. The behaviour, which is similar to what is seen on protonation of PANi at pH?3, may be due to alteration in the

Artur J. M. Valente; Hugh D. Burrows; Victor M. M. Lobo

2006-01-01

141

Preparation and characterisation of poly (amide-imide) incorporated cellulose acetate membranes for polymer enhanced ultrafiltration of metal ions  

Microsoft Academic Search

Polymeric membranes intended to use in industrial separations must maintain excellent thermal and mechanical properties over their targeted operating conditions. Therefore, cellulose acetate (CA) membranes with superior properties were prepared by phase inversion technique using high performance thermoplastic poly (amide-imide) (PAI) as the modification agent. The prepared membranes were characterised using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential

S. Rajesh; P. Maheswari; S. Senthilkumar; A. Jayalakshmi; D. Mohan

2011-01-01

142

Preparation and Characterization of Cellulose Acetate?Sulfonated Poly (Ether Imide) Blend Ultrafiltration Membranes and their Applications  

Microsoft Academic Search

Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, polyetherimide (PEI) was functionalized by sulfonation and ultrafiltration membranes were prepared based on cellulose acetate (CA) and sulfonated poly (ether imide) (SPEI) in various blend compositions in N?methyl?2?pyrrolidone (NMP) as solvent by phase inversion technique. Prepared membranes were subjected to

A. Nagendran; S. Vidya; D. Mohan

2008-01-01

143

Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer  

Microsoft Academic Search

The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates

Sui Zhang; Kai Yu Wang; Tai-Shung Chung; Hongmin Chen; Y. C. Jean; Gary Amy

2010-01-01

144

Effect of a Cellulose Acetate Phthalate Topical Cream on Vaginal Transmission of Simian Immunodeficiency Virus in Rhesus Monkeys  

Microsoft Academic Search

Human immunodeficiency virus type 1 (HIV-1) infection continues to spread in developing countries, mostly through heterosexual transmission. The development of a safe and cost-effective topical microbicide, effective against a range of STDs including HIV-1, would greatly impact the ongoing epidemic. When formulated in a vehicle, a micronized form of cellulose acetate phthalate (CAP), which is an inactive pharmaceutical excipient, has

KELLEDY H. MANSON; MICHAEL S. WYAND; CHRISTOPHER MILLER; A. ROBERT NEURATH

2000-01-01

145

Studies on the compatibility and specific interaction in cellulose acetate hydrogen phthalate (CAP) and poly methyl methacrylate (PMMA) blend  

Microsoft Academic Search

Compatibility of cellulose acetate hydrogen phthalate (CAP) and poly methyl methacrylate (PMMA) has been investigated by solution viscometric, ultrasonic and differential scanning calorimetric (DSC) methods. From viscosity measurements, Krigbaum and Wall polymer–polymer interaction parameter is evaluated. Ultrasonic velocity and adiabatic compressibilites versus blend composition are plotted, and found to be linear. Tg values are calculated using Gordon–Taylor and Fox equations.

V Rao; P. V Ashokan; M. H Shridhar

1999-01-01

146

Development of a gel permeation chromatographic assay to achieve mass balance in cellulose acetate phthalate stability studies.  

PubMed

Cellulose acetate phthalate (CAP, cellulose acetate 1,2-benzenedicarboxylate) is a common polymeric oral tablet coating. CAP is also a vaginal microbicide candidate that potently inhibits HIV-1 proliferation. This paper describes the development of a precise, stability-indicating gel permeation chromatography (GPC) assay for CAP. During accelerated stability studies monitored by separate reversed-phase high performance liquid chromatography (RP-HPLC) and GPC analyses, an apparent loss of mass balance was observed. This deficit was corrected by recalculating the response factor (RF) for each degraded sample, proportional to the fraction of phthalate remaining bound to the polymeric CAP. The correction factor enabled CAP and the degradation product phthalic acid (PA) to be quantitated by a single GPC analysis. The chromatographic approach taken here could potentially apply to any polymer containing degradable chromophores. PMID:19070984

Mayhew, James W; Gideon, Lulu T; Ericksen, Bryan; Hlavaty, John J; Yeh, Simon M; Chavdarian, Charles G; Strick, Nathan; Neurath, A Robert

2009-02-20

147

Microstructural characterization of low-density foams. [Silica, resorcinol/formaldehyde, cellulose/acetate  

SciTech Connect

Low-density foams (of the order 0.1 g/cm/sup 3/) synthesized from silica aerogel, resorcinol/formaldehyde, and cellulose acetate have fine, delicate microstructures that are extremely difficult to characterize. Improved low-voltage resolution of an SEM equipped with a field-emission gun (FESEM) does permit these materials to be examined directly without coating and at sufficient magnification to reveal the microstructures. Light coatings applied by ion-beam deposition can stabilize the specimens to some extent and reduce electron charging without seriously altering the microstructure, but coatings applied by conventional techniques usually obliterate these microstructures. Transmission electron microscopy (TEM) is required to provide unambiguous microstructural interpretations. However, TEM examinations of these materials can be severely restricted by specimen preparation difficulties and electron-beam damage, and considerable care must be taken to ensure that reasonably accurate TEM results have been obtained. This work demonstrates that low-voltage FESEM analyses can be used to characterize microstructures in these foams, but TEM analyses are required to confirm the FESEM analyses and perform quantitative measurements. 19 refs., 11 figs.

Price, C.W.

1988-01-01

148

Calcium channel blockers correct in vitro mitochondrial toxicity of cellulose acetate.  

PubMed

We studied the action of rinse solutions from cellulose acetate hemodialyzers on isolated mitochondria. We showed that concentrates from the rinses impaired the adenosine 5'-triphosphate (ATP) synthesis as reflected by the decrease in respiration during state 3 and in P/O ratio. This impairment results from a calcium release from mitochondria that is induced by rinse solution concentrates. The release, triggering the mitochondrial calcium carrier, would explain the decrease in ATP synthesis. Moreover, rinse solution concentrates hinder mitochondrial calcium storage. The rise in cytosolic calcium in hemodialyzed patients may be related, at least in part, to these findings, since a lack of ATP impairs the ATP-dependent cellular calcium-extrusion pumps. We also showed that calcium channel blockers, at therapeutically relevant doses, restore ATP synthesis and calcium storage in mitochondria impaired by rinse solution concentrates. Finally, these in vitro results were confirmed by experiments on cells in culture proving that Diltiazem counteracts the cytotoxicity of rinse solution concentrates. These findings are consistent with observations that these drugs suppress the increase in leukocyte cytosolic calcium in dialyzed patients. Moreover, this would help explain the efficiency of calcium channel blockers in cells without L-calcium channels. PMID:9350663

Tabouy, L J; Chauvet-Monges, A M; Carles, G P; Brunet, P J; Braguer, D L; Rebouillon, P A; Berland, Y F; Crevat, A D

1997-11-01

149

Adsorptive removal of phenolic compounds using cellulose acetate phthalate-alumina nanoparticle mixed matrix membrane.  

PubMed

Mixed matrix membranes (MMMs) were prepared using alumina nanoparticles and cellulose acetate phthalate (CAP) by varying concentration of nanoparticles in the range of 10 to 25wt%. The membranes were characterized by scanning electron micrograph, porosity, permeability, molecular weight cut off, contact angle, surface zeta potential, mechanical strength. Addition of nanoparticles increased the porosity, permeability of the membrane up to 20wt% of alumina. pH at point of zero charge of the membrane was 5.4. Zeta potential of the membrane became more negative up to 20wt% of nanoparticles. Adsorption of phenolic derivatives, catechol, paranitrophenol, phenol, orthochloro phenol, metanitrophenol, by MMMs were investigated. Variation of rejection and permeate flux profiles were studied for different solutes as a function of various operating conditions, namely, solution pH, solute concentration in feed and transmembrane pressure drop. Difference in rejection of phenolic derivatives is consequence of interplay of surface charge and adsorption by alumina. Adsorption isotherm was fitted for different solutes and effects of pH were investigated. Catechol showed the maximum rejection 91% at solution pH 9. Addition of electrolyte reduced the rejection of solutes. Transmembrane pressure drop has insignificant effects on solute rejection. Competitive adsorption reduced the rejection of individual solute. PMID:24333710

Mukherjee, Raka; De, Sirshendu

2014-01-30

150

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

151

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

NASA Astrophysics Data System (ADS)

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

Celebioglu, Asli; Demirci, Serkan; Uyar, Tamer

2014-06-01

152

Cellulose acetate phthalate microparticles containing Vibrio cholerae: steps toward an oral cholera vaccine.  

PubMed

Abstract Oral cholera vaccine (OCV) has been recommended in some endemic areas and epidemic situations since 1999. Although safe and effective vaccines are currently on the market, the burden of transport and storage remains an issue. Herein, we report an approach to develop an alternative OCV in the form of a gastro-resistant powder. Heat-killed Vibrio cholerae (VC) was encapsulated with a spray-drying technique at different temperatures. Cellulose acetate phthalate (Aquacoat® CPD) was chosen as the core polymer and the addition of alginate was studied. The microparticles (MPs) produced were characterized by surface morphology, particle size, drug loading, antigenicity and gastro resistance. The MPs obtained were 6?µm in size and had appropriate drug content, ranging from 8.16 to 8.64%. Furthermore, antigenicity was maintained, never dropping below 85%, and enteric properties were achieved for all the formulations. Next, an in vivo study was carried out with Aquacoat® CPD MP prepared at 80?°C with and without alginate. Two different doses were assayed, 30 and 60?mg, and compared to the VC suspension. The evoked immune responses showed that alginate containing MPs, especially at the 30?mg dose, displayed values that were very similar to those of VC. In conclusion, spray-dried alginate VC MPs seem to be a promising step toward a powder-form cholera vaccination. PMID:24731056

Pastor, Marta; Esquisabel, Amaia; Marquínez, Iratxe; Talavera, Arturo; Pedraz, José Luis

2014-07-01

153

Composite membrane of niobium(V) oxide and cellulose acetate: Preparation and characterization  

SciTech Connect

Composite membranes of niobium(V) oxide and cellulose acetate (Cel/Nb{sub 2}O{sub 5}) were prepared with the following Nb{sub 2}O{sub 5} loadings (in wt%): 1.1, 6.1, 9.8, 15.6, and 20.9. The thermal stability of the membranes slightly decreased in relation to the pure membrane on incorporation of the metal oxide into the matrix. Scanning electron microscopy and niobium mapping with an X-ray EDS microprobe showed that the metal oxide particles are homogeneously dispersed in the matrix. The electronic absorption bands indicated that the oxide particle size varies from that of the monomer to those of oligomer species on increased Nb{sub 2}O{sub 5} loading in the matrix. The dispersed oxide possesses mainly Lewis acid character, a clear indication that on increasing the oxide loading in the matrix, the coordination number of the metal is not saturated by formation of the Nb-O-Nb bond. These materials can be useful in ion-exchange process, as supports for enzymes, in catalytic reactions, and in reverse osmosis experiments.

Campos, E.A.; Gushikem, Y. [Unicamp, Campinas, Sao Paulo (Brazil). Inst. de Quimica] [Unicamp, Campinas, Sao Paulo (Brazil). Inst. de Quimica

1997-09-01

154

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

2013-01-01

155

Effects of Boundary Conditions on Thermal Response of a Cellulose Acetate Layer Using Hottel's Zonal Method  

NASA Astrophysics Data System (ADS)

Energy can transfer internally by radiation in addition to conduction in translucent polymers. Since radiant propagation is very rapid, it can provide energy within the layer more quickly than diffusion by heat conduction. Thus, the transient thermal response of a layer for combined radiative and conduction may be extremely different from that of conduction alone. In this paper, the behavior of a heat conducting, absorbing, and emitting layer of Cellulose Acetate layer is investigated during the transient interval when both conductive and radiative heat transfer are considered. Specifically, the effects of boundary conditions on the response of the layer are considered here. These boundary conditions include both conductive boundary conditions, such as convection coefficient and convective fluid temperature, and radiation boundary conditions, like radiation surrounding temperature and specular reflectivity. To this end, the governing differential equations including the equation of radiative heat transfer within the material coupled to the transient energy equation with radiative terms are presented. The solution procedure is based on nodal analysis and Hottel's zonal method extended by the ray tracing method. The transient energy equation including the radiative internal energy source is solved using a time marching finite difference procedure with variable space and time increments.

Safavisohi, Babak; Sharbati, Ehsan; Aghanajafi, Cyrus; Firoozabadi, Seyed Reza Khatami

2006-12-01

156

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

2013-01-01

157

Cellulose acetate phthalate microencapsulation and delivery of plasmid DNA to the intestines.  

PubMed

Cellulose acetate phthalate (CAP) microcapsules were formulated to deliver plasmid DNA (pDNA) to the intestines. The microcapsules were characterized and were found to have an average diameter of 44.33 ± 30.22 ?m, and were observed to be spherical with smooth surface. The method to extract pDNA from CAP was modified to study the release profile of the pDNA. The encapsulated pDNA was found to be stable. Exposure to the acidic and basic pH conditions, which simulates the pH environment in the stomach and the intestines, showed that the release occurred in a stable manner in the former, whereas it was robust in the latter. The loading capacity and encapsulation efficiency of the microcapsules were low but the CAP recovery yield was high which indicates that the microcapsules were efficiently formed but the loading of pDNA can be improved. In vitro transfection study in 293FT cells showed that there was a significant percentage of green-fluorescent-protein-positive cells as a result of efficient transfection from CAP-encapsulated pDNA. Biodistribution studies in BALB/c mice indicate that DNA was released at the stomach and intestinal regions. CAP microcapsules loaded with pDNA, as described in this study, may be useful for potential gene delivery to the intestines for prophylactic or therapeutic measures for gastrointestinal diseases. PMID:23192729

Hanafi, Aimi; Nograles, Nadine; Abdullah, Syahril; Shamsudin, Mariana Nor; Rosli, Rozita

2013-02-01

158

Hydration and plasticization effects in cellulose acetate: a solid-state NMR study  

NASA Astrophysics Data System (ADS)

The conjoint effects of water and diethyl phthalate (DEP) plasticizer on molecular motion in cellulose acetate (CA) have been examined. 1H, 13C and cross polarization NMR data reveal a number of interesting features. As in other hydrated polymers, there are different types of water ranging from tightly bound to bulk-like water in CA. Both tightly and loosely bound water can act as a plasticizer. In CA which is devoid of DEP, water preferentially interacts with carbonyl groups in the side chains whereas in the plasticized and filled polymer, water associates with oxygen atoms in both main and side chains via weak hydrogen bonding. Hydration significantly enhances chain motions but, as expected, reduces the ability to cross-polarize carbons and protons. Information is obtained on the relaxation behaviour of CA and the manner in which it is affected by water and DEP plasticizer. From a practical point of view, it is significant that water and plasticizer act in concert to alter the properties of the material quite dramatically. That these property changes can be induced, for example, by climatic changes in humidity has important bearing on the processability of the material.

Keely, Christopher M.; Zhang, Xiaoqing; McBrierty, Vincent J.

1995-08-01

159

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

PubMed

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

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

2012-08-01

160

Comparative evaluation of chitosan, cellulose acetate, and polyethersulfone nanofiber scaffolds for neural differentiation.  

PubMed

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

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

2014-01-01

161

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

2013-01-01

162

Electrospun cellulose acetate phthalate fibers for semen induced anti-HIV vaginal drug delivery.  

PubMed

Despite many advances in modern medicine, human immunodeficiency virus (HIV) still affects the health of millions of people world-wide and much effort is put in developing methods to either prevent infection or to eradicate the virus after infection has occurred. Here, we describe the potential use of electrospun cellulose acetate phthalate (CAP) fibers as a tool to prevent HIV transmission. During the electrospinning process, anti-viral drugs can easily be incorporated in CAP fibers. Interestingly, as a result of the pH-dependent solubility of CAP, the fibers are stable in vaginal fluid (the healthy vaginal flora has a pH of below 4.5), whereas the addition of small amounts of human semen (pH between 7.4 and 8.4) immediately dissolves the fibers which results in the release of the encapsulated drugs. The pH-dependent release properties have been carefully studied and we show that the released anti-viral drugs, together with the CAP which has been reported to have intrinsic antimicrobial activity, efficiently neutralize HIV in vitro. PMID:22018388

Huang, Chaobo; Soenen, Stefaan J; van Gulck, Ellen; Vanham, Guido; Rejman, Joanna; Van Calenbergh, Serge; Vervaet, Chris; Coenye, Tom; Verstraelen, Hans; Temmerman, Marleen; Demeester, Jo; De Smedt, Stefaan C

2012-01-01

163

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

2013-02-15

164

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

2012-04-01

165

Synthesis and characterization of composite based on cellulose acetate and hydroxyapatite application to the absorption of harmful substances.  

PubMed

The aim of this work is to develop composite materials with hydroxyapatite (HAp) mineral and organic matrix such as cellulosic polymers. We use cellulose acetate with different percentages, and then inorganic-organic films were fabricated by evaporation of solvent. The composite films were characterized using emission scanning electron microscopy (FEG-SEM), thermo-gravimetric analysis (TGA) and Fourier transform infra-red (FT-IR) spectra. Test results show that these films are uniform and have good ductility. A strong interaction existed between HAp and cellulosic polymers, and the method allows the production of very fine particles size of about 92nm. We have developed a new chromatographic method for the quantification of bisphenol A (BPA) in samples of baby food. The result of this study demonstrates how to use this type of composite materials to remove pollutants. PMID:25037327

Azzaoui, Khalil; Lamhamdi, Abdelatif; Mejdoubi, El Miloud; Berrabah, Mohammed; Hammouti, Belkheir; Elidrissi, Abderrahman; Fouda, Moustafa M G; Al-Deyab, Salem S

2014-10-13

166

Liquid crystalline phase and gel-sol transitions for concentrated microcrystalline cellulose (MCC)/1-ethyl-3-methylimidazolium acetate (EMIMAc) solutions.  

PubMed

Liquid crystalline (LC) phase transition and gel-sol transition in the solutions of microcrystalline cellulose (MCC) and ionic liquid (1-ethyl-3-methylimidazolium acetate, EMIMAc) have been investigated through a combination of polarized optical microscope (POM) observation and rheological measurements. Molecular LC phase forms at the 10 wt % cellulose concentration, as observed by POM, whereas the critical gel point is 12.5 wt % by rheological measurements according to the Winter and Chambon theory, for which the loss tangent, tan ?, shows frequency independence. Dramatic decreases of G' and G'' in the phase transition temperature range during temperature sweep are observed due to disassembling of the LC domain junctions. The phase diagram describing the LC phase and gel-sol transitions is obtained and the associated mechanisms are elucidated. A significant feature shown in the phase diagram is the presence of a narrow lyotropic LC solution region, which potentially has a great importance for the cellulose fiber wet spinning. PMID:21361275

Song, Hongzan; Niu, Yanhua; Wang, Zhigang; Zhang, Jun

2011-04-11

167

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

Microsoft Academic Search

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

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

2010-01-01

168

Study on cellulose acetate membranes for reverse osmosis and polyethersulfone membranes for ultrafiltration by electron spin resonance technique  

Microsoft Academic Search

Electron spin resonance (ESR) technique was used to study cellulose acetate (CA) membranes for reverse osmosis (RO) and polyethersulfone (PES) membranes for ultrafiltration. TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy — free radical) was used as a spin probe that was brought into the membranes by immersing the membranes into solutions involving TEMPO, or by blending TEMPO into membrane casting solutions. It was found that

K. C. Khulbe; T. Matsuura; C. Y. Feng

2002-01-01

169

FTIR imaging coupled with multivariate analysis for study of initial diffusion of different solvents in cellulose acetate butyrate films  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopic imaging was used to study the initial diffusion of different solvents in cellulose\\u000a acetate butyrate (CAB) films containing different amounts of acetyl and butyryl substituents. Different solvents and solvent\\/non-solvent\\u000a mixtures were also studied. The FTIR imaging system allowed acquisition of sequential images of the CAB films as solvent penetration\\u000a proceeded without disturbing the system. The

Margaretha Söderqvist Lindblad; Brian M. Keyes; Lynn M. Gedvilas; Timothy G. Rials; Stephen S. Kelley

2008-01-01

170

Effects of annealing on the microstructure and performance of cellulose acetate membranes for pressure-retarded osmosis processes  

Microsoft Academic Search

The effects of annealing on the microstructure and performance of cellulose acetate (CA) forward osmosis (FO) hollow fiber membranes have been studied. The mean pore radius decreases from 0.63nm to 0.39, 0.36, 0.30 and 0.30 upon annealing at 70, 80, 85 and 90°C, respectively. The density of free volume in the depth range of 0.31–1.33?m significantly decreases with depth with

Jincai Su; Sui Zhang; Hangzheng Chen; Hongmin Chen; Y. C. Jean; Tai-Shung Chung

2010-01-01

171

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

172

Preparation of electrospun silk fibroin\\/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption  

Microsoft Academic Search

Silk fibroin (SF)\\/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal\\u000a absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised\\u000a of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the\\u000a anti-felting properties of the blend nanofibrous membranes were markedly

Weitao Zhou; Jianxin He; Shizhong Cui; Weidong Gao

2011-01-01

173

Studies of dielectric relaxation and a.c. conductivity in cellulose acetate hydrogen phthalate–poly(methyl methacrylate) blends  

Microsoft Academic Search

Dielectric constant, dielectric loss and a.c. conductivity of polyblends of cellulose acetate hydrogen phthalate(CAP) and poly(methyl methacrylate) (PMMA) of different compositions have been measured in the temperature range 300–430 K and in the frequency range 50–100 kHz. Variations in dielectric constant with temperature of the blends exhibit unique behavior, different from the component polymers. In the blends, the dielectric loss

Vijayalakshmi Rao; P. V Ashokan; M. H Shridhar

2000-01-01

174

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

Microsoft Academic Search

The influence of fluidized-bed processing conditions, as well as curing parameters with and without humidity, on drug release from beads coated with cellulose acetate phthalate (CAP) aqueous dispersion was investigated. Theophylline beads prepared by extrusion–spheronization were coated with diethyl phthalate (DEP)-plasticized CAP dispersion (Aquacoat® CPD) using a Strea-1 fluidized-bed coater. The parameters investigated were plasticizer level, outlet temperature, spray rate

Robert O. Williams III; Jiping Liu

2000-01-01

175

Coagulation of chitin and cellulose from 1-ethyl-3-methylimidazolium acetate ionic-liquid solutions using carbon dioxide.  

PubMed

Chemisorption of carbon dioxide by 1-ethyl-3-methylimidazolium acetate ([C2 mim][OAc]) provides a route to coagulate chitin and cellulose from [C2 mim][OAc] solutions without the use of high-boiling antisolvents (e.g., water or ethanol). The use of CO2 chemisorption as an alternative coagulating process has the potential to provide an economical and energy-efficient method for recycling the ionic liquid. PMID:24115399

Barber, Patrick S; Griggs, Chris S; Gurau, Gabriela; Liu, Zhen; Li, Shan; Li, Zengxi; Lu, Xingmei; Zhang, Suojiang; Rogers, Robin D

2013-11-18

176

Use of immuno-electro-diffusion on cellulose acetate for the research of the precipitating antibodies in the screening of patients suspected of farmer's lung disease  

Microsoft Academic Search

The authors show the use of Electro-Immuno-Diffusion on cellulose acetate in the diagnosis of Farmer's lung. This technique with its simplicity, its rapiditity, its sensibility is an interesting routine method in the detecting of this disease.

M. GariJ; P. Smets; J. M. PinonJ; P. Recco; J. P. Seguela

1982-01-01

177

Functional analysis of cellulose acetate flat membranes prepared via casting technique  

Microsoft Academic Search

Cellulosic membranes reflect better utilization of renewable resources with minimum impacts on the environment. Significant market for medium pressure application is encountered in water filtration and reclamation. Thus, endeavors are needed to balance advancement of cellulose membrane and manufacturing technology modification. Cellulose membranes have been prepared via phase inversion process from different blends of polymers\\/solvents\\/additives. The casting solutions comprising polymer

S. A. Ahmed; M. H. Sorour; H. A. Talaat; S. S. Ali

2010-01-01

178

Kinetics of release of a model disperse dye from supersaturated cellulose acetate matrices.  

PubMed

A study has been made of the kinetics of release into water of a model disperse dye (4-aminoazobenzene) from supersaturated solvent-cast cellulose acetate films at room temperature. Excess dye was introduced into the polymer matrix by: (i) sorption from aqueous solution at 100 degrees C; (ii) sorption from the vapour phase at 110 degrees C; or (iii) prior dissolution in the casting solvent. The effect of the method of introduction of the dye, the degree of supersaturation and the rate of agitation of the bath were investigated. Under conditions of strong agitation, the release kinetics from films dyed by method (i) or (iii) were in general accord with the theoretical model which assumes solute in the film in excess of the saturation limit to be in the form of immobile aggregates at equilibrium with mobile dye; although the value of the diffusion coefficient of the solute in the film was found to be substantially higher than that in the unsaturated film. On the other hand, when dyeing had been effected from the vapour phase, Fickian kinetics was followed and the diffusion coefficient was found to be equal to that observed in unsaturated film. It was concluded that under these conditions, the excess dye in the film tends to remain molecularly dispersed. Under conditions of slow agitation, the square root of t kinetics was not attained in many instances. General and early-time approximate expressions based on the Roseman-Higuchi model proved useful for the interpretation of the results in such cases; while the said model was extended to include the effect of significant variation of the partition coefficient of the solute with concentration. PMID:9766245

Papadokostaki, K G; Petropoulos, J H

1998-08-14

179

Long-term stability of heat-humidity cured cellulose acetate phthalate coated beads.  

PubMed

The objective of this study was to investigate the influence of stability storage conditions on the enteric release of heat-humidity cured cellulose acetate phthalate (CAP) coated beads. Theophylline beads were coated with 25 or 35% diethyl phthalate plasticized CAP dispersion (Aquacoat CPD), and cured at a heat-humidity condition (50 degrees C/75% RH) for 24h. The cured beads were then stored in various container/closure systems (open glass containers, sealed glass containers with and without desiccant) and exposed to 40 degrees C/75% RH for 6 months or 25 degrees C/60% RH for 12 months. At accelerated conditions (40 degrees C/75% RH), only beads stored in sealed glass containers with desiccant displayed stable release profiles throughout the exposure period. The beads stored in sealed glass containers without desiccant showed increased theophylline release in acidic media at 2h, and did not maintain enteric resistance at 6 months. The release profiles of beads stored in open containers, directly exposed to 40 degrees C/75% RH, were the least stable. The decrease in enteric protection of the beads stored at these two packaging conditions was correlated to an increased phthalic acid content in the films. At ambient storage conditions (25 degrees C/60% RH), all samples possessed enteric release properties, irrespective of the container/closure system. Beads stored in sealed glass containers with desiccant remained the most stable compared to those at the other two packaging conditions. The results indicated that although humidity significantly contributed to coalescence of CAP coating during the curing process, the optimum packaging condition for the heat-humidity cured CAP coated beads was with desiccant to maintain the chemical stability of the CAP. PMID:11879999

Liu, Jiping; Williams, Robert O

2002-03-01

180

The influence of plasticizer on heat-humidity curing of cellulose acetate phthalate coated beads.  

PubMed

The objectives of the present study are to investigate the effect of plasticizer type and level on the curing of cellulose acetate phthalate (CAP) coated beads with and without the presence of humidity. Theophylline beads were coated in a fluidized-bed with CAP dispersion (Aquacoat CPD) plasticized by a water-insoluble plasticizer, diethyl phthalate (DEP), or a water-soluble plasticizer, triethyl citrate (TEC), at various levels. The coated heads were cured at a heat-only condition (50 degrees C for 24 hr) and a heat-humidity condition (50 degrees C/75% RH for 24 hr). Rapid drug release in the acidic media was found for both heat-only and heat-humidity cured beads when plasticizer was not used in the coating dispersion, indicating that the heat-humidity curing is ineffective without the presence of plasticizers. When plasticizer was incorporated in the coating formulations, heat-humidity curing effectively improved the acid resistance of the coated films at all plasticizer levels investigated. The minimum plasticizer level required to obtain enteric release profiles for heat-humidity cured beads coated at an outlet coating temperature of 46 degrees C was 15%. This limit was further decreased when the beads were coated at a lower temperature due to a less plasticizer loss at the lower coating temperature. Between the two plasticizers, less TEC was lost during the coating process, and TEC was more effective compared to DEP with regards to heat-humidity curing at the 10% plasticizer level. The enteric release profiles were reproducible following a 7-day drying period at 40 degrees C for all heat-humidity cured beads that had initially passed the enteric release dissolution test. The rapid leaching of TEC and DEP into the. PMID:11775961

Williams, R O; Liu, J

2001-11-01

181

Properties of heat-humidity cured cellulose acetate phthalate free films.  

PubMed

Cellulose acetate phthalate (CAP) free films containing diethyl phthalate (DEP) or triethyl citrate (TEC) as the plasticizer were prepared by the spray method. The chemical and mechanical properties of films were compared following heat-only (50 degrees C for 24 h) and heat-humidity curing (50 degrees C/75% RH for 24 h) conditions. The surface roughness of the heat-humidity cured films decreased compared to that of the uncured and heat-only cured films. The heat-humidity curing condition suppressed evaporation of the plasticizer, resulting in higher plasticizer levels remaining in the films, as compared to the heat-only curing condition. The heat-humidity curing also significantly increased the mechanical strength and decreased the water vapor permeability of the films. When exposed to the acidic media, despite rapid leaching of plasticizer, the heat-humidity cured films retained the most mechanical strength of the films prior to exposure. The moisture content and phthalic acid content after heat-humidity curing were increased slightly, but did not reach a level that would interfere with enteric performance. TEC was less volatile and produced films with increased % elongation, and decreased tensile strength and elastic modulus compared to the films plasticized with DEP. However, the DEP plasticized films were less permeable than TEC-plasticized films following heat-humidity curing. The results indicated that a short-term exposure of the CAP films to heat and humidity during the curing process greatly improved the degree of film coalescence and mechanical strength, without causing significant chemical degradation of the polymer. PMID:12356418

Liu, Jiping; Williams, Robert O

2002-10-01

182

In vitro biological evaluation of electrospun cellulose acetate fiber mats containing asiaticoside or curcumin.  

PubMed

Ultra-fine cellulose acetate (CA; M(w) approximately 30,000 Da; degree of acetyl substitution approximately 2.4) fiber mats containing either asiaticoside [from the plant Centella asiatica (L.); either in the form of a crude extract (CACE) or pure substance (PAC)] or curcumin (CM; from the plant Curcuma longa L.) were successfully prepared. The proposed use of these materials is as topical/transdermal patches or wound dressings. Here, the potential for use of these herb-loaded CA fiber mats as wound dressings was evaluated in terms of the stability and the antioxidant activity of the as-loaded herbal substances, the ability to support both the attachment and the proliferation of fibroblasts and the ability of the cultured fibroblasts to synthesize collagen. Normal human dermal fibroblasts (NHDF) were used as the reference fibroblastic cells. The results showed that the as-loaded herbal substances were stable even after the herb-loaded CA fiber mats had been aged either at room temperature or at 40 degrees C for a period of up to 4 months. The inclusion of asiaticoside [either 2% (w/w) CACE or 40% (w/w) PAC] rendered the resulting CA fiber mats their superiority in supporting the attachment, promoting the proliferation, and upregulating the production of collagen of the seeded and/or the cultured NHDF to the corresponding solvent-cast films and the neat CA fiber mats. On the other hand, the presence of CM imparted the antioxidant activity to the resulting CA fiber mats. PMID:20694988

Suwantong, Orawan; Ruktanonchai, Uracha; Supaphol, Pitt

2010-09-15

183

Evaluation of the change in defectiveness of cellulose and acetate fibres in thermal aging with the scale dependence of the mechanical properties  

Microsoft Academic Search

The kinetics of the change in the mechanical properties (strength, elongation, and strain energy at break) of viscose, acetate, and triacetate fibres during thermal aging were investigated. The coefficients of variation and scale dependence of the fracture characteristics and their standardized values were calculated for evaluating the defectiveness of chemical fibres based on cellulose and its acetates. The data obtained

K. E. Perepelkin; S. A. Baranova; T. A. Matvienko

1996-01-01

184

Metabolic activity of fatty acid-oxidizing bacteria and the contribution of acetate, propionate, butyrate, and CO/sub 2/ to methanogenesis in cattle waste at 40 and 60/sup 0/C  

SciTech Connect

The quantitative contribution of fatty acids and CO/sub 2/ 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/sup 0/C under identical loading conditions. In the thermophilic digestor, acetate turnover increased from a prefeeding level of 16 ..mu..M/min to a peak (49 ..mu..M/min. Acetate turnover in the mesophilic digester increased fron 15 to 40 ..mu..M/min. Propionate turnover ranged from 2 to 5.2 and 1.5 to 4.5 ..mu..M/min in the thermophilic and mesophilic digestors, respectively. Butyrate turnover (0.7 to 1.2 ..mu..M/min) was similar in both digestors. The proportion of CH/sub 4/ 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 CO/sub 2/ reduction was 24 to 19% and 19 to 27%, respectively. Propionate and butyrate turnover accounted for 20% of the total CH/sub 4/ produced. Counts of fatty acid-degrading bacteria were related to their turnover activity.

Mackie, R.I.; Bryant, M.P.

1981-06-01

185

Efficient approach to design stable water-dispersible nanoparticles of hydrophobic cellulose esters.  

PubMed

Commercially prepared cellulose acetate, cellulose acetate propionate, -butyrate, and -phthalate as well as cellulose acetates prepared in the laboratory scale with varying degree of substitution (DS) self-assemble into regular nanoparticles, ranging in size from 86 to 368 nm, by using two different techniques of nanoprecipitation. Dialysis of polymers dissolved in N,N-dimethylacetamide results in the formation of regular nanospheres whereas the preparation in acetone by successive adding of water leads to bean-shaped particles in the nanoscale. One criterion for nanoprecipitation is the existence of dilute polymer solutions. Furthermore, the formation of nanoparticles strongly depends on DS and distribution of the substituents. Concerning this issue, quantitative (13)C NMR spectroscopy was applied for detailed structure characterization of selected cellulose acetates. The stability of the nanoparticle suspensions in the physiological pH range was observed by zeta potential measurements. PMID:18393524

Hornig, Stephanie; Heinze, Thomas

2008-05-01

186

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

NASA Technical Reports Server (NTRS)

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 spaceflight experiment was to devise a method of holding seeds to the cylindrical porous tube. The seed holder must provide water and air to the 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, Corinne F.; Dreschel, Thomas W.; Brown, Christopher S.; Wheeler, Raymond M.

1994-01-01

187

The regulation of propionate oxidation in Prototheca zopfii  

PubMed Central

1. Whole cell suspensions of Prototheca zopfii grown on propionate oxidize propionate, acrylate, malonic semialdehyde and acetate immediately, whereas acetate-grown cells only oxidize acrylate or propionate rapidly after a lag of 20–30min. This adaptation to propionate is slowed down by 8-azaguanine or p-fluorophenylalanine, and is not influenced by adding an ammonium salt or an amino acid mixture. 2. The adaptation involves induction of the enzymes of ?-oxidation of propionate. 3. A small proportion (5–8%) of the activities of propionyl-CoA dehydrogenase, ?-hydroxypropionate dehydrogenase and malonic semialdehyde dehydrogenase are consistently associated with mitochondria isolated from propionate-grown cells. 4. Such mitochondria will oxidize propionyl-CoA, ?-hydroxypropionate and malonic semialdehyde, and the respiration rates with these substrates in the presence of inorganic phosphate are ADP-dependent. 5. Mitochondria from acetate-grown cells do not contain detectable activities of the enzymes of propionate oxidation.

Lloyd, D.; Venables, Susan E.

1967-01-01

188

Preparation, characterization and dielectric studies on carbonyl iron/cellulose acetate hydrogen phthalate core/shell nanoparticles for drug delivery applications.  

PubMed

A method to prepare composite colloidal nanoparticles, consisting of a magnetic core (carbonyl iron) and a biodegradable polymeric shell (cellulose acetate hydrogen phthalate) was described and also particle size was characterized by Optical Microscope and Scanning Electron Microscopy. Dielectric properties of Cellulose Acetate Hydrogen Phthalate (CAP) and carbonyl iron/CAP (core/shell) tablets were studied in the frequency range of 70 Hz-400 kHz at 300 K using LCR meter and compared the dielectric parameters of core/shell and ordinary phase of CAP tablets. From the dielectric results, the importance of core/shell nanoparticles in controlled drug delivery was discussed. PMID:18775769

Reshmi, G; Mohan Kumar, P; Malathi, M

2009-01-01

189

Evidence for phytotoxic effects of cellulose acetate in UV exclusion studies  

Microsoft Academic Search

Cellulose diacetate (CA) has been widely used in UV-B enhancement studies and has also been used along with Aclar and Teflon in UV-B exclusion studies. In recent UV exclusion studies conducted at Beltsville, MD under solar UV, cucumber plants were found to develop marginal chlorosis under CA filters. To test the hypothesis that CA was responsible for the phytotoxic effects

Donald T. Krizek; Roman M. Mirecki

2004-01-01

190

Remarkably regioselective deacylation of cellulose esters using tetraalkylammonium salts of the strongly basic hydroxide ion.  

PubMed

Tetraalkylammonium hydroxides have been found to mediate regioselective deacylation of cellulose esters. This deacylation surprisingly shows substantial selectivity for the removal of the acyl groups at O-2/3, affording cellulose-6-O-esters by a simple, efficient one-step process. The mechanism for this deacylation was investigated by studying the effect of tetraalkylammonium cation size upon ester deacylation selectivity. We hypothesize that coordination of the tetraalkylammonium cation by the ester oxygen atoms of the vicinal 2,3-acetate groups may drive the unexpected regioselectivity at the secondary alcohol esters. Broad scope with respect to ester type was demonstrated; regioselective O-2,3 deacylation was observed with cellulose acetate, propionate, butyrate, hexanoate and benzoate triesters. The scope of this deacylation of cellulose acetates has been investigated to understand how to carry it out most efficiently. Reaction with TBAOH in pyridine was the most effective process, providing the highest selectivity. PMID:25037325

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

2014-10-13

191

Catalase immobilization in cellulose acetate beads and determination of its hydrogen peroxide decomposition level by using a catalase biosensor.  

PubMed

Catalase enzyme (EC 1.11.1.6) was immobilized by entrapping in cellulose acetate beads. This organic matrix is highly resistant to mechanical stability and can be used under various conditions. Initial studies were conducted to examine the immobilization ability of catalase on the matrix previously activated with a series of reagent normally and the best results were obtained with the beads activated with Ce(SO4)2. In the optimization studies of the immobilized enzyme optimum pH and temperature were found as pH:7.0 (Tris-HCl, 50 mM) and 35 degrees C. In the characterization studies of the immobilized enzyme some parameters such as storage and thermal stability were investigated. Finally, the immobilized enzyme was used for the decomposition of hydrogen peroxide in milk samples and also by using a catalase biosensor prepared the decomposition level of hydrogen peroxide was detected. PMID:15508280

Yildiz, Hatice; Akyilmaz, Erol; Dinçkaya, Erhan

2004-01-01

192

Phase inversion cellulose acetate membranes for suppression of protein interferences in anodic stripping voltammetry 2 1. Improvement of the membrane preparation procedure  

Microsoft Academic Search

Phase inversion (PI) cellulose acetate membranes were cast on glassy carbon electrodes from a solution containing acetone as solvent and aqueous magnesium perchlorate as pore former. It is shown that a significant improvement of the reproducibility and permselective properties of the membrane is obtained by allowing complete evaporation of the solvent in a controlled humidity environment before the membrane is

Boy Hoyer; Nina Jensen

1996-01-01

193

EFFECT OF METHANOL CONCENTRATION ON THE PERFORMANCE OF ASYMMETRIC CELLULOSE ACETATE REVERSE OSMOSIS MEMBRANES USING DRY\\/WET PHASE INVERSION TECHNIQUE  

Microsoft Academic Search

Asymmetric membranes were prepared from a multicomponent dope polymer so- lution consisting of cellulose acetate, acetone, formamide and methanol. In this work, the dry\\/wet phase inversion technique is used and the presence of methanol is studied. In addition, this work also presents the fundamental issues involved in altering flat sheet casting solutions to produce solutions, potentially useful for preparing hollow

ANI IDRIS; AHMAD FAUZI ISMAIL; S. ISWANDI; SIMON J. SHILTON

194

Surface modification of commercial cellulose acetate membranes using surface-initiated polymerization of 2-hydroxyethyl methacrylate to improve membrane surface biofouling resistance  

Microsoft Academic Search

To improve biofouling resistance, cellulose acetate (CA) reverse osmosis membranes were modified by reacting surface hydroxyl groups with an atom transfer radical polymerization (ATRP) initiator, 2-bromoisobutyryl bromide, followed by polymeric grafting of 2-hydroxyethyl methacrylate (pHEMA) using activators regenerated by electron transfer (ARGET) ATRP. Thermogravimetric analysis (TGA), atomic force microscopy (AFM) and water contact angle (WCA) measurements of pristine and modified

Clare H. Worthley; Kristina T. Constantopoulos; Milena Ginic-Markovic; Rachel J. Pillar; Janis G. Matisons; Stephen Clarke

2011-01-01

195

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

NSDL National Science Digital Library

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

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

1999-01-01

196

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

197

Preparation of enteric-coated microspheres of Mycoplasma hyopneumoniae vaccine with cellulose acetate phthalate: The effect of swine serum on micromeritic properties  

Microsoft Academic Search

Cellulose acetate phthalate was used to prepare the Mycoplasma hyopneumoniae vaccine (MHV) microspheres using a solvent evaporation method. Swine serum was used as an additive in the antigen to form the core materials. The addition of serum had a significant effect on surface topography of the MHV microspheres. By using this modified solvent evaporation method, the recoveries of antigens in

Y. L. Tzan; S. Y. Lin; C. N. Weng; C. J. Lee

1991-01-01

198

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

PubMed

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

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

2014-06-01

199

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

2013-07-01

200

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

201

Effect of Hydrostatic Pressure on the Phase Transitions in Acetate-Substituted Dicalcium Strontium Propionate, Ca2Sr[(C2H5COO)1-x(CH3COO)x]6  

NASA Astrophysics Data System (ADS)

The effect of hydrostatic pressure on phase transitions has been studied by dielectric measurements for acetate-substituted dicalcium strontium propionate, Ca2Sr[(C2H5COO)1-x(CH3COO)x]6 with x{=}0.045, 0.10, 0.14. The I-II and II-III transition temperatures of x{=}0.045 crystal (256 K and 120 K at 0 MPa, respectively) increase linearly with increasing pressure. The ferroelectric II phase of x{=}0.10 crystal narrows with application of pressure and disappears at 110 MPa. In the x{=}0.14 crystal, which does not show ferroelectricity, the temperature at which the dielectric constant shows a broad maximum increases with increasing pressure. The pressure dependence of the peak value \\varepsilonmax is expressed by \\varepsilonmax{=}\\varepsilon0+C/(p-pc) where C{=}225 MPa and pc{=}-27 MPa. There is a parallelism between the effects of hydrostatic pressure and acetate-substitution on the phase transitions.

Gesi, Kazuo; Takashige, Masaaki

1992-06-01

202

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

SciTech Connect

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

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

2008-01-01

203

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.  

PubMed

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes. PMID:16860465

Arthanareeswaran, G; Thanikaivelan, P; Jaya, N; Mohan, D; Raajenthiren, M

2007-01-01

204

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

PubMed

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

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

2013-02-15

205

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

206

Eudragit-S, Eudragit-L and cellulose acetate phthalate coated polysaccharide tablets for colonic targeted delivery of azathioprine.  

PubMed

The present work deals with the formulation and evaluation of polymer-coated polysaccharide tablets of azathioprine prepared by direct compression method using different ratios of avicel (MCC), inulin and triacetin. The tablets formulations containing 25 mg of azathioprine were prepared and evaluated for thickness, hardness, friability, weight variation, content uniformity and in vitro dissolution test. Hardness and percentage friability were in the range of 7.23-7.43 kg/cm(2) and 0.21-0.41%, respectively, and showed 99-100% uniformity in drug content. The coated tablets exploiting different polymer combinations were evaluated for drug release under different pH conditions. The formulation containing Eudragit-S, Eudragit-L and cellulose acetate phthalate (ES, EL and CAP) (1:1:1) displayed desired release pattern with only 9.75% drug release in first 5 h (lag phase) and satisfactory release in lowered pH conditions. Drug release increased with the plasticizer (triacetin) concentration. Increase in the concentration of inulin and citric acid above 5% w/w increases the drug release. The addition of inulin in the formulation with coating level 28% w/w demonstrated increased drug release in presence of rat cecal content. Thus inulin containing ES, EL and CAP (1:1:1) polymer-coated formulation system can be used for the targeted delivery of azathioprine with desired release pattern. PMID:20236031

Kotagale, Nandkishor; Maniyar, Mithun; Somvanshi, Sachin; Umekar, Milind; Patel, Chirag J

2010-01-01

207

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

208

In vitro biocompatibility of sheath-core cellulose-acetate-based electrospun scaffolds towards endothelial cells and platelets.  

PubMed

Typically, tissue-engineered scaffolds mimic the topographical properties of the native extracellular matrix. However, other physical properties, such as the scaffold mechanical stiffness, are not imitated. The purpose of this study was to fabricate scaffolds with improved mechanical properties and investigate their biocompatibility towards endothelial cells and platelets. To enhance mechanical properties, an electrospinning apparatus was developed that fabricates fibers with sheath-core morphologies. Different combinations of cellulose acetate and chitosan were chosen to modulate the mechanical properties of the formed fibers. We hypothesized that mechanically stiffer scaffolds would improve endothelial cell growth and that all scaffolds would be compatible towards endothelial cells and platelets. Endothelial cell-culture conditions were quantified up to 5 days. Migration onto scaffolds was monitored for 10 days. Platelet aggregation, antagonized by thrombin receptor agonist peptide 6, was measured after scaffold incubation. A platelet activation time-course was assessed with the modified prothrombinase assay. As scaffold mechanical stiffness increased, endothelial cell growth within and adhesion to and migration throughout the scaffolds was promoted. Also, scaffolds did not induce platelet aggregation or activation. These results indicate that the mechanical stiffness of engineered scaffolds regulates endothelial cell-culture parameters and that these sheath-core electrospun scaffolds are compatible towards endothelial cells and platelets. PMID:20537251

Rubenstein, David A; Venkitachalam, Subramaniam M; Zamfir, Dan; Wang, Fang; Lu, Hongbing; Frame, Mary D; Yin, Wei

2010-01-01

209

Cellulose acetate butyrate as multifunctional additive for poly(butylene succinate) by melt blending: Mechanical properties, biomass carbon ratio, and control of biodegradability  

Microsoft Academic Search

We have evaluated the plasticizing effect of poly(butylene succinate) (PBS) and cellulose acetate butyrate (CAB). PBS and CAB were mixed with a melt-kneading machine. The tensile strength and strain at break in the case of the blend with 10% CAB in the PBS matrix were 547% and 35 MPa. It showed that CAB acted as a plasticizer for PBS. The biomass

Yuya Tachibana; Nguyen Thien Truong Giang; Fumi Ninomiya; Masahiro Funabashi; Masao Kunioka

2010-01-01

210

[Value of co-immunoelectrodiffusion on cellulose acetate for the demonstration of remarkable precipitating systems in the diagnosis of farmer's lung].  

PubMed

Farmer's Lung is an extrinsic allergic alveolitis due to the inhalation of actinomycetes thermophiles. Micropolyspora faeni is the principal allergen implicated in this disease which is very difficult to diagnose. The authors discuss the value of immuno-electro-diffusion on cellulose acetate which is a rapid and sensitive technique for the demonstration of remarkable precipitating systems: polysaccharide and chymotrypsin arcs. This investigation enables subjects who really have the disease to be distinguished from "contact" subjects. PMID:6324358

Gari, M; Recco, P; Pinon, J M; Séguéla, J P

1984-03-01

211

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

Microsoft Academic Search

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

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

2010-01-01

212

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 0.6 mL/h and an electrostatic field strength of 17.5 kV/15 cm 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

2013-10-15

213

Determination of Ca, K, Mg, Na, sulfate, phosphate, formate, acetate, propionate, and glycerol in biodiesel by capillary electrophoresis with capacitively coupled contactless conductivity detection  

Microsoft Academic Search

In this work, a new method employing capillary electrophoresis (CE) for the determination of several species in biodiesel is introduced. The concentrations of inorganic species (Na+, K+, Ca2+, Mg2+, SO42?, and PO43?) and glycerol are of interest to the regulatory authorities due to their ability to form undesirable compounds in engines. Additionally, other species of low molecular weight (e.g., acetate,

Thiago Nogueira; Claudimir Lucio do Lago

2011-01-01

214

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

215

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

PubMed

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

Makhija, Sapna N; Vavia, Pradeep R

2003-04-14

216

Propionate assimilation in the flagellate Polytomella caeca. An inducible mitochondrial enzyme system  

PubMed Central

1. The assimilation of propionate by Polytomella caeca involves the ?-oxidation of this fatty acid. 2. Propionate-grown cells immediately oxidize propionate, ?-hydroxypropionate, malonic semialdehyde and acetate; acetate-grown cells oxidize propionate rapidly only after a lag of 2hr., and this adaptation of resting cells to propionate involves the formation of the enzymes of ?-oxidation. 3. The ?-hydroxypropionate dehydrogenase and malonic semialdehyde dehydrogenase activities of both propionate-grown and propionate-adapted cells are partly located in mitochondrial fractions. 4. Mitochondria isolated from propionate-grown cells, and also those from acetate-grown cells fully adapted to propionate, oxidize succinate, ?-oxoglutarate, ?-hydroxypropionate and malonic semialdehyde; oxidation of these substrates is tightly coupled to the phosphorylation of ADP. 5. Mitochondria from acetate-grown cells exhibit ADP-dependent oxidation of succinate and ?-oxoglutarate, but do not oxidize ?-hydroxypropionate or malonic semialdehyde. Mitochondria isolated from acetate-grown cells adapted to propionate for 5hr. slowly oxidize ?-hydroxypropionate and malonic semialdehyde, but no tightly coupled phosphorylation is detectable. 6. Two of the inducible enzymes of propionate oxidation are located within the NAD-impermeable barrier and appear to be membrane-bound. 7. The formation of the inducible enzymes is inhibited by cycloheximide and actinomycin D, but not by chloramphenicol. ImagesPLATE 1

Lloyd, D.; Evans, D. A.; Venables, Susan E.

1968-01-01

217

Cellulose acetates from linters and sisal: Correlation between synthesis conditions in DMAc\\/LiCl and product properties  

Microsoft Academic Search

We report the acetylation of celluloses from sisal (untreated and alkali treated) and cotton linters (alkali treated), under homogeneous solution conditions, using DMAc\\/LiCl as solvent system. Our target was to evaluate the effects of cellulose dissolution and reactions conditions on the product properties. The products were characterized in terms of degree of substitution (DS) by 1H NMR, and molar weight

Beatriz A. P. Ass; Gabriela T. Ciacco; Elisabete Frollini

2006-01-01

218

Molecular imprinting of cellulose acetate-sulfonated polysulfone blend membranes for Rhodamine B by phase inversion technique  

Microsoft Academic Search

A functional polymer, sulfonated polysulfone (SPS) with a degree of substitution of 0.10, was prepared and then blended with cellulose diacetate (CA) as the matrix polymer for the preparation of molecularly imprinted polymer (MIP) membranes via phase inversion from a casting solution containing a template. Polyethylene glycol was found to be compatible with these polymers and was subsequently used as

Malaisamy Ramamoorthy; Mathias Ulbricht

2003-01-01

219

Propionate. Anti-obesity and satiety enhancing factor?  

PubMed

Propionate is produced along with acetate and butyrate as a result of fermentative activity of gut microflora on dietary fiber. It has long been known to exhibit hypophagic effects in ruminants, however, its potential physiological roles in non-ruminants as well as humans remained unnoticed over the years. In view of various studies pointing towards the hypophagic as well as hypocholesterolemic effects of propionate in humans, it may act as an important factor in amelioration of obesity, a lifestyle disease arising due to energy imbalance and growing at a startling rate globally. Short chain fatty acids have recently been ascribed as ligands to G-protein coupled receptors (GPRs) 41 and 43. Thus, propionate along with acetate may also be involved in the regulation of adipogenesis and adipokine release mediated via GPRs. The present review summarizes the evidence which collectively raise the possibility of propionate as a dietary factor to depress appetite and combat the obesity epidemic. PMID:21255628

Arora, Tulika; Sharma, Rajkumar; Frost, Gary

2011-04-01

220

Biodegradable Plastics from Cellulose  

Microsoft Academic Search

Brief history of the attempts trying to develop biodegradable plastics from cellulose acetates were reviewed in the first part. Then, two kinds of authors' trials were introduced. One of them is a plasticization trial for cellulose acetates (CAs) that is based on the reaction with dibasic acid anhydrides and monoepoxides during melt processing under practical process conditions. This reactive melt-processing

Mariko Yoshioka; Nobuo Shiraishi

2000-01-01

221

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

222

Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers  

PubMed Central

The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 ?m for CAP-microspheres and 358-442 ?m for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation.

Jelvehgari, Mitra; Hassanzadeh, Davoud; Kiafar, Farhad; Delf Loveym, Badir; Amiri, Sara

2011-01-01

223

Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers.  

PubMed

The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 ?m for CAP-microspheres and 358-442 ?m for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation. PMID:24250377

Jelvehgari, Mitra; Hassanzadeh, Davoud; Kiafar, Farhad; Delf Loveym, Badir; Amiri, Sara

2011-01-01

224

Castor oil-derived plasticizers. Some nitrogen-containing derivatives as plasticizers for vinyl chloride-vinyl acetate copolymer and cellulose acetate resins  

Microsoft Academic Search

Summary  Eight nitrogen-containing derivatives of ricinoleic acid, namely, 4-ricinoleoylmorpholine, 4-(12-hydroxystearoyl) morpholine,\\u000a 4-(12-acetoxyoleoyl) morpholine, 4-(12-acetoxystearoyl) morpholine, 4-(12-?-cyanoethoxyoleoyl) morpholine, 4-(12-?-cyanoethoxystearoyl)\\u000a morpholine, 1,12-bis(?-cyanoethoxy)-9-octadecene, and 1,12-bis(?-cyanoethoxy)octadecane were screened for their plasticizer\\u000a characteristics. 1,12-Diacetoxy-9-octadecene and 1,12-diacetoxyoctadecane were also screened to compare cyanoethylated with\\u000a acetylated derivatives.\\u000a \\u000a All of these materials, except 4-(12-hydroxystearoyl)morpholine, were found to be satisfactory primary plasticizers for vinyl\\u000a chloride-vinyl acetate copolymer. In general, these

Frank C. Magne; Harold P. Dupuy; Leo A. Goldblatt

1959-01-01

225

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

PubMed

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

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

2011-09-01

226

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

227

Controlled-release cellulose esters matrices for water-soluble diclofenac sodium: compression and dissolution studies.  

PubMed

Matrix tablets comprising of a blend of cellulose acetate butyrate (CAB) or cellulose acetate propionate (CAP) and alpha-lactose monohydrate were prepared by direct compression to control the release of diclofenac sodium. Tablet formulations containing CAP75000 or CAB50-54 exhibited highest extents, but lowest onsets of plastic deformation and lowest release rates in buffer medium, while tablets containing CAP15000 or CAB35-39 exhibited lowest extents, but highest rates of plastic deformation and highest release rates in buffer medium. The DA values obtained from Heckel plots and the DI values obtained from Kawakita plots showed similar trends. A plot of compression pressure or crushing strengths against T50% showed curvilinear relationship for all tablets. Tablets containing 40 % CAB35-39 (formulation F7D) was considered the best formulation in terms of T50%, compressibility and compactability. PMID:24640597

Obeidat, W M; Alzoubi, N M

2014-02-01

228

Metabolic pathway to propionate of Pectinatus frisingensis , a strictly anaerobic beer-spoilage bacterium  

Microsoft Academic Search

Pectinatus frisingensis, a recently described species of anaerobic mesophilic beer-spoilage bacteria, grows by fermenting various organic compounds,\\u000a and produces mainly propionate, acetate, and succinate. Although acrylate and succinate were both dismutated by dense resting-cell\\u000a suspensions, propionate production proceeded through the succinate pathway: [3-13C]pyruvate consumption led to equal 13C-labeling of propionate on methyl and methylene groups. Growth on glucose or glycerol

Jean-Luc Tholozan; Jean-Philippe Grivet; Christelle Vallet

1994-01-01

229

Vitamin-loaded electrospun cellulose acetate nanofiber mats as transdermal and dermal therapeutic agents of vitamin A acid and vitamin E.  

PubMed

The present contribution reports the use of mats of electrospun cellulose acetate (CA; acetyl content=39.8%; Mw=30,000 Da) nanofibers as carriers for delivery of the model vitamins, all-trans retinoic acid or vitamin A acid (Retin-A) and alpha-tocopherol or vitamin E (Vit-E). The amounts of Vit-E and Retin-A loaded in the base CA solution [17% w/v in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc)] were 5 and 0.5 wt% (based on the weight of CA), respectively. Cross-sectionally round and smooth fibers were obtained. The average diameters of these fibers ranged between 247 and 265 nm. The total immersion of the vitamin-loaded as-spun CA fiber mats in the acetate buffer solutions containing either 0.5 vol % Tween 80 or 0.5 vol % Tween 80 and 10 vol % methanol was used to arrive at the cumulative release of the vitamins from the fiber mat samples. The same was also conducted on the vitamin-loaded solution-cast CA films for comparison. In most cases, the vitamin-loaded as-spun fiber mats exhibited a gradual and monotonous increase in the cumulative release of the vitamins over the test periods (i.e., 24 h for Vit-E-loaded samples and 6 h for Retin-A-loaded ones), while the corresponding as-cast films exhibited a burst release of the vitamins. PMID:17498935

Taepaiboon, Pattama; Rungsardthong, Uracha; Supaphol, Pitt

2007-09-01

230

Cellulose acetate phthalate, a common pharmaceutical excipient, inactivates HIV-1 and blocks the coreceptor binding site on the virus envelope glycoprotein gp120  

PubMed Central

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 vaginal infection by HSV-2 and simian immunodeficiency virus. Methods Enzyme-linked immunoassays and flow cytometry were used to demonstrate CAP binding to HIV-1 and to define the binding site on the virus envelope. Results 1) CAP binds to HIV-1 virus particles and to the envelope glycoprotein gp120; 2) this leads to blockade of the gp120 V3 loop and other gp120 sites resulting in diminished reactivity with HIV-1 coreceptors CXCR4 and CCR5; 3) CAP binding to HIV-1 virions impairs their infectivity; 4) these findings apply to both HIV-1 IIIB, an X4 virus, and HIV-1 BaL, an R5 virus. Conclusions These results provide support for consideration of CAP as a topical microbicide of choice for prevention of STDs, including HIV-1 infection.

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

2001-01-01

231

Gypsum (CaSO4?2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis  

PubMed Central

We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

2013-01-01

232

Cellulose-based aerogels  

Microsoft Academic Search

New organic aerogels were prepared using cellulose derivatives as precursors. The elaboration process and the structural characterisations of these porous cellulose-based materials are described in the present study. Series of monolithic gels were synthesised in acetone by crosslinking cellulose acetate with a non-toxic isocyanate via sol–gel route, using tin-based catalyst. Gelation times (ranging from 15 to 150min) were significantly dependent

F. Fischer; A. Rigacci; R. Pirard; S. Berthon-Fabry; P. Achard

2006-01-01

233

Effect of the dispersion of Eudragit S100 powder on the properties of cellulose acetate butyrate microspheres containing theophylline made by the emulsion-solvent evaporation method.  

PubMed

The dispersion/incorporation of Eudragit S100 powder as a filler in cellulose acetate butyrate (CAB-551-0.01) microsphere containing theophylline was investigated as a means of controlling drug release. Microspheres of CAB-551-0.01 of different polymer solution concentrations/viscosities were prepared (preparations Z(0), Z(A), Z(B) and Z(C)) and evaluated and compared to microspheres of a constant concentration of CAB-551-0.01 containing different amounts of Eudragit S100 powder as a filler (preparations X(A), X(B) and X(C)). The organic solvent acetonitrile used was capable of dissolving the matrix former CAB-551-0.01 only but not Eudragit S100 powder in the emulsion-solvent evaporation method. The CAB-551-0.01 concentration in Z(A), Z(B) and Z(C) was equal to the total polymer concentration (CAB-551-0.01 and Eudragit S100 powder) in X(A), X(B) and X(C), respectively. Scanning electron microscopy (SEM) was used to identify microspheres shape and morphology. In vitro dissolution studies were carried out on the microspheres at 37 degrees C (+/-0.5 degrees C) at two successive different pH media (1.2 +/- 0.2 for 2 h and 6.5 +/- 0.2 for 10 h). Z preparations exhibited low rates of drug release in the acidic and the slightly neutral media. On the other hand, X preparations showed an initial rapid release in the acidic medium followed by a decrease in the release rate at the early stage of dissolution in the slightly neutral pH which could be due to some relaxation and gelation of Eudragit S100 powder to form a gel network before it dissolves completely allowing the remained drug to be released. PMID:17454437

Obeidat, Wasfy M; Obaidat, Ihab M

2007-05-01

234

Down-modulation of toll-like receptor 2 expression on granulocytes and suppression of interleukin-8 production due to in vitro treatment with cellulose acetate beads.  

PubMed

The Adacolumn, which is filled with cellulose acetate beads (CA beads), has been used as a medical device for inflammatory diseases. The CA beads selectively adsorb granulocytes and monocytes and remove them from the peripheral blood. The anti-inflammatory effects of the Adacolumn are possibly caused by removal of these cells but also due to the functional changes in the processed cells. In this study, we investigated the effects of CA beads treatment on modulation of the expression of innate immunity receptors such as the Toll-like receptor (TLR) family and production of an inflammatory cytokine, interleukin-8 (IL-8). Changes in the expressions of TLR1, 2, 4 and 6 in peripheral leukocytes exposed to CA beads were examined by flow cytometry. TLR2 expression on the surface of granulocytes exposed to CA beads was decreased, but the amount of intracellular TLR2 was increased, possibly by internalization. These changes were not observed in monocytes or lymphocytes. Peptidoglycan (PGN) treatment produced similar changes in TLR2 on granulocytes. We also measured the amounts of IL-8 in cultured blood treated with lipopolysaccharide (LPS) and PGN, which are known TLR agonists. PGN-induced IL-8 production was lower in CA beads-treated leukocytes than that in non-treated leukocytes, but LPS did not induce these changes. Based on these findings, we conclude that the down-modulation of TLR2 and suppression of IL-8 production on granulocytes by CA beads, may play an important role in the anti-inflammatory effects of the Adacolumn. PMID:22107694

Hidaka, Mayumi; Fukuzawa, Kenji

2011-12-01

235

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

2011-06-01

236

Survey of baked goods for propionic acid and propionates  

Microsoft Academic Search

One hundred and thirty samples comprising bread (64), hamburger buns (33), pittas (16), cakes (9) and Christmas puddings (8) from various retail outlets in the UK, have been analysed for the preservative propionic acid. Only one sample of bread, two samples of hamburger buns and three samples of pitta contained propionic acid in excess of 1000 mg\\/ kg (range 1110–2625

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

1996-01-01

237

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

PubMed Central

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

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

2013-01-01

238

Kinetics of lactate, acetate and propionate in unadapted and lactate-adapted thermophilic, anaerobic sewage sludge: the influence of sludge adaptation for start-up of thermophilic UASB-reactors  

Microsoft Academic Search

A thermophilic anaerobic sludge digestor was adapted to lactate metabolism. The adapted sludge showed an improved capacity for lactate degradation when tested by a batch activity test, compared to the performance of unadapted sludge. Acetate was the major intermediate produced during the degradation. When adapted sludge was used as the inoculum for a lactate-fed, upflow anaerobic sludge blanket (UASB) reactor,

Anders Hay Sørensen; Margrethe Winther-Nielsen; Birgitte K. Ahring

1991-01-01

239

Unconventional Cellulose Esters: Synthesis, Characterization and Structure–Property Relations  

Microsoft Academic Search

This paper summarizes selected results obtained during a two-year research project in the framework of the focus program ‘Cellulose and cellulose derivatives’ (SPP 1011), sponsored by the German Science Foundation (DFG). New synthesis paths for the preparation of the most important cellulose ester, cellulose acetate, were investigated. In contrast to conventional methods, cellulose was converted in a homogeneous phase reaction

Thomas Heinze; Tim F. Liebert; Katy S. Pfeiffer; Muhammad A. Hussain

2003-01-01

240

Continuous cellulose fiber-reinforced cellulose ester composites. II. Fiber surface modification and consolidation conditions  

Microsoft Academic Search

We prepared thermoplastic composite panels using solution impregnation of continuous lyocell (regenerated cellulose) fibers with a cellulose mixed-ester (cellulose acetate butyrate) matrix. We examined both fiber-matrix adhesion and melt consolidation in an effort to produce uniform panels having low void content and high mechanical strength. We characterized the effect of surface modification by acetylation on interfacial adhesion between the cellulose

Kevin C. Seavey; Wolfgang G. Glasser

2001-01-01

241

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

242

[Subpopulations of t and B lymphocytes, rosette tests, levels of immunoglobulins in peripheral blood and NBT test in the initial period of hemodialysis conducted with cuprophan or cellulose acetate dialysers in patients with chronic renal failure].  

PubMed

In 10 patients with chronic renal failure treated with haemodialyses (HD) T and B cell populations were determined in peripheral blood, together with immunoglobulin concentration and NBT test in the first two hours of the procedure using cuprophan and cellulose acetate dialysers. It was found that the per cent proportions of T4, T8 and T11 were not significantly changed. The proportions of B cells with sIg, sIgG, sIgM, sIgA were not significantly altered during HD with cuprophan dialysers. The per cent of B cells with sIg, sIgG decreased significantly during HD with cellulose acetate dialysers. The per cent proportions of active and late E rosettes decreased significantly, the per cent of stable E rosettes rose significantly, while that of EAC rosettes was not significantly changed in the initial HD period with the use of both dialyser types. IgG concentration rose significantly in the initial period of HD with either dialyser, while there was no significant change in the concentration of IgA and IgM. The value of the NBT test was not altered significantly during HD with either dialyser type. PMID:7817571

Starzyk, J; Sarnecka, S; Bartelik, S; Heltman, H; Partyka, M

1993-11-01

243

Influence of the acetate concentration on the recovery time of a perturbed anaerobic digester  

Microsoft Academic Search

Summary Imbalance in a fluidized bed reactor was simulated by injecting pure or mixed acetate and propionate salts into the digester. For acetate levels higher than 13–15 mM, propionate degradation was inhibited. In these cases, the time required by the system to reduce the propionate concentration up to steady-state values was approximately 60–70 % higher than the recovery time found

M. S. Alonso

1992-01-01

244

Pathway of Succinate and Propionate Formation in Bacteroides fragilis  

PubMed Central

Cell suspensions of Bacteroides fragilis were allowed to ferment glucose and lactate labeled with 14C in different positions. The fermentation products, propionate and acetate, were isolated, and the distribution of radioactivity was determined. An analysis of key enzymes of possible pathways was also made. The results of the labeling experiments showed that: (i) B. fragilis ferments glucose via the Embden-Meyerhof pathway; and (ii) there was a randomization of carbons 1, 2, and 6 of glucose during conversion to propionate, which is in accordance with propionate formation via fumarate and succinate. The enzymes 6-phosphofrucktokinase (pyrophosphate-dependent), fructose-1,6-diphosphate aldolase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarate reductase, and methylmalonyl-coenzyme A mutase could be demonstrated in cell extracts. Their presence supported the labeling results and suggested that propionate is formed from succinate via succinyl-, methylmalonyl-, and propionyl-coenzyme A. From the results it also is clear that CO2 is necessary for growth because it is needed for the formation of C4 acids. There was also a randomization of carbons 1, 2, and 6 of glucose during conversion to acetate, which indicated that pyruvate kinase played a minor role in pyruvate formation from phosphoenolpyruvate. Phosphoenolpyruvate carboxykinase, oxaloacetate decarboxylase, and malic enzyme (nicotinamide adenine dinucleotide phosphate-dependent) were present in cell extracts of B. fragilis, and the results of the labeling experiments agreed with pyruvate synthesis via oxaloacetate and malate if these acids are in equilibrium with fumarate. The conversion of [2-14C]- and [3-14C]lactate to acetate was not associated with a randomization of radioactivity.

Macy, Joan M.; Ljungdahl, Lars G.; Gottschalk, Gerhard

1978-01-01

245

Salmeterol/fluticasone propionate combination.  

PubMed

Current evidence suggests that addition of the long-acting beta2-agonist salmeterol to an inhaled corticosteroid in patients with persistent asthma symptoms provides greater clinical benefit than doubling the dosage of the inhaled corticosteroid. Fixed combination salmeterol/fluticasone propionate in 3 different fluticasone propionate dosage strengths administered via the Diskus powder inhaler does not result in any untoward interaction that affects the pharmacodynamic or pharmacokinetic profiles of the individual drugs, or their adverse effect profiles - including the influence of the corticosteroid on plasma cortisol levels. Administration of fixed combination salmeterol/ fluticasone propionate to both adults and children with persistent asthma provides greater improvements in lung function than either agent alone, and at least equal effectiveness to the same dosages of the 2 agents given by separate powder inhalers. Preliminary reports indicate that combination therapy has also demonstrated superior efficacy to budesonide (fluticasone propionate dosages were 25% those of budesonide). The most commonly encountered adverse effects in clinical trials with combined salmeterol/fluticasone propionate therapy have been oropharyngeal candidiasis. hoarseness/dysphonia, throat irritation, headache, tachycardia/palpitations, tremor and dizziness (all in < or =5% of patients). PMID:10400406

Spencer, C M; Jarvis, B

1999-06-01

246

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

NASA Astrophysics Data System (ADS)

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength).

Rapp, F.; Schneider, A.; Elsner, P.

2014-05-01

247

21 CFR 556.710 - Testosterone propionate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 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...

2013-04-01

248

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

PubMed

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

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

2012-08-01

249

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

Microsoft Academic Search

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

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

250

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

251

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

252

Cholesterol Metabolism Increases the Metabolic Pool of Propionate in M. tuberculosis†  

PubMed Central

Mycobacterium tuberculosis can metabolize cholesterol to both acetate and propionate. The mass of isolated phthiocerol dimycoserate, a methyl-branched fatty acylated polyketide, was used as a reporter for intracellular propionate metabolic flux. When Mycobacterium tuberculosis is grown using cholesterol as the only source of carbon, a 42 a.m.u increase in average phthiocerol dimycoserate molecular weight is observed, consistent with the cellular pool of propionate and thus, methylmalonyl CoA increasing upon cholesterol metabolism. In contrast, no shift in phthiocerol dimycoserate molecular weight is observed upon supplementation of medium containing glycerol and glucose with cholesterol. We conclude that cholesterol is only a significant source of propionate in the absence of sugar carbon sources.

Yang, Xinxin; Nesbitt, Natasha M.; Dubnau, Eugenie; Smith, Issar; Sampson, Nicole S.

2009-01-01

253

Liver transplantation in propionic acidaemia  

Microsoft Academic Search

Despite the improvement in dietary therapy during the past 20 years, the overall outcome of severe forms of propionic acidaemia (PA) remains often disappointing. Good results can be obtained at a very high price in terms of medical attention, family burden and high cost. In most early onset forms of PA, the intake of natural protein must be rigidly restricted

J. M. Saudubray; G. Touati; P. Delonlay; P. Jouvet; J. Schlenzig; C. Narcy; J. Laurent; D. Rabier; P. Kamoun; D. Jan; Y. Revillon

1999-01-01

254

Wheat flour based propionic acid fermentation: an economic approach.  

PubMed

A process for the fermentative production of propionic acid from whole wheat flour using starch and gluten as nutrients is presented. Hydrolysis of wheat flour starch using amylases was optimized. A batch fermentation of hydrolysate supplemented with various nitrogen sources using Propionibacterium acidipropionici NRRL B 3569 was performed. The maximum production of 48.61, 9.40, and 11.06 g of propionic acid, acetic acid and succinic acid, respectively, was found with wheat flour hydrolysate equivalent to 90 g/l glucose and supplemented with 15 g/l yeast extract. Further, replacement of yeast extract with wheat gluten hydrolysate showed utilization of gluten hydrolysate without compromising the yields and also improving the economics of the process. The process so developed could be useful for production of animal feed from whole wheat with in situ production of preservatives, and also suggest utilization of sprouted or germinated wheat for the production of organic acids. PMID:23357590

Kagliwal, Lalit D; Survase, Shrikant A; Singhal, Rekha S; Granström, Tom

2013-02-01

255

Propionate for Fatty Acid Synthesis by the Mammary Gland of the Lactating Goat  

Microsoft Academic Search

Isolated mammary glands of lactating goats were perfused with heparinized and oxygenated blood for 8 to 15 h. Adequate quantities of glucose, acetate, and amino acids were added to the perfusate. After addition of propionate to the perfusion blood, concentrations of odd-numbered and of monomethyl-substituted fatty acids other than those with iso and anteiso configuration increased in the milk fat.

A. M. Massart-Leën; E. Roets; G. Peeters; R. Verbeke

1983-01-01

256

Propionate Oxidation by and Methanol Inhibition of Anaerobic Ammonium-Oxidizing Bacteria  

PubMed Central

Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min?1 mg of protein?1) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO2, with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed.

Guven, Didem; Dapena, Ana; Kartal, Boran; Schmid, Markus C.; Maas, Bart; van de Pas-Schoonen, Katinka; Sozen, Seval; Mendez, Ramon; Op den Camp, Huub J. M.; Jetten, Mike S. M.; Strous, Marc; Schmidt, Ingo

2005-01-01

257

Propionate oxidation by and methanol inhibition of anaerobic ammonium-oxidizing bacteria.  

PubMed

Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min(-1) mg of protein(-1)) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO(2), with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed. PMID:15691967

Güven, Didem; Dapena, Ana; Kartal, Boran; Schmid, Markus C; Maas, Bart; van de Pas-Schoonen, Katinka; Sozen, Seval; Mendez, Ramon; Op den Camp, Huub J M; Jetten, Mike S M; Strous, Marc; Schmidt, Ingo

2005-02-01

258

Effect of oral antibiotics on intestinal production of propionic acid  

Microsoft Academic Search

BACKGROUNDPropionic acid derived from colonic bacterial fermentation contributes substantially to overall propionate load in children with disorders of propionate metabolism, and its reduction is important for adequate metabolic control.AIMSTo evaluate the in vitro and in vivo effects of antibiotic treatment on propionate production by colonic bacteria, and plasma propionate concentrations in a child with propionic acidaemia.METHODSIn vitro fermentation techniques were

A F Mellon; S A Deshpande; J C Mathers; K Bartlett

2000-01-01

259

Acet-oxy-?-valerolactone  

PubMed Central

Levulinyl cellulose esters have been produced as an effective renewable binder for architectural coatings. The title compound, C7H10O4 (systematic name: 2-methyl-5-oxo­tetra­hydro­furan-2-yl acetate), assigned as the esterifying species, was isolated and crystallized to confirm the structure. In the crystal, the mol­ecules pack in layers parallel to (102) utilizing weak C—H?O inter­actions.

Tristram, Cameron; Gainsford, Graeme J.; Hinkley, Simon

2013-01-01

260

21 CFR 522.842 - Estradiol benzoate and testosterone propionate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 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...

2013-04-01

261

40 CFR 721.8657 - Cerium, hydroxy oleate propionate complexes.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Cerium, hydroxy oleate propionate complexes...Specific Chemical Substances § 721.8657 Cerium, hydroxy oleate propionate complexes...The chemical substance identified as Cerium, hydroxy oleate propionate...

2010-07-01

262

40 CFR 721.8657 - Cerium, hydroxy oleate propionate complexes.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Cerium, hydroxy oleate propionate complexes...Specific Chemical Substances § 721.8657 Cerium, hydroxy oleate propionate complexes...The chemical substance identified as Cerium, hydroxy oleate propionate...

2009-07-01

263

Surface acetylation of bacterial cellulose  

Microsoft Academic Search

Bacterial cellulose was partially acetylated by the fibrous acetylationmethod to modify its physical properties, while preserving the microfibrillarmorphology. The overall degree of substitution was varied from 0.04 to 2.77 bychanging the amount of acetic anhydride added. X-ray diffraction of thepartially acetylated samples showed the crystalline pattern of unmodified celluloseI up to moderate degrees of acetylation, and the change in peak

Dae-Young Kim; Yoshiharu Nishiyama; Shigenori Kuga

2002-01-01

264

Development of New and Improved Cellulose Ester Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

High retention membranes having fluxes of 8 to 11 gfd and sodium chloride rejections of 99.4 to 99.75% have been made from a variety of cellulose esters including blends of cellulose diacetate and triacetate, homopolymer cellulose acetate and several mixe...

C. W. Saltonstall

1969-01-01

265

Vibrational spectroscopic study of fluticasone propionate  

NASA Astrophysics Data System (ADS)

Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

2009-03-01

266

Hydrocasting Reverse Osmosis Membranes, Development of Porous Support Tubes, Study of the Mechanism of Membrane Formation and Development of Non-Cellulosic Desalination Membranes.  

National Technical Information Service (NTIS)

The report discusses the results from on going research on hydrocasting cellulose acetate membranes in porous support tubes and porous tubes development, characterization of cellulosic and non cellulosic membrane tubules hydrocast in solid tubes, radii op...

A. Gollan M. Frommer R. Matz M. Tulin

1973-01-01

267

Cellulose Digestion and Metabolism Induced Biocatalytic Transitions in Anaerobic Microbial Ecosystems  

PubMed Central

Anaerobic digestion of highly polymerized biomass by microbial communities present in diverse microbial ecosystems is an indispensable metabolic process for biogeochemical cycling in nature and for industrial activities required to maintain a sustainable society. Therefore, the evaluation of the complicated microbial metabolomics presents a significant challenge. We here describe a comprehensive strategy for characterizing the degradation of highly crystallized bacterial cellulose (BC) that is accompanied by metabolite production for identifying the responsible biocatalysts, including microorganisms and their metabolic functions. To this end, we employed two-dimensional solid- and one-dimensional solution-state nuclear magnetic resonance (NMR) profiling combined with a metagenomic approach using stable isotope labeling. The key components of biocatalytic reactions determined using a metagenomic approach were correlated with cellulose degradation and metabolic products. The results indicate that BC degradation was mediated by cellulases that contain carbohydrate-binding modules and that belong to structural type A. The degradation reactions induced the metabolic dynamics of the microbial community and produced organic compounds, such as acetic acid and propionic acid, mainly metabolized by clostridial species. This combinatorial, functional and structural metagenomic approach is useful for the comprehensive characterization of biomass degradation, metabolic dynamics and their key components in diverse ecosystems.

Yamazawa, Akira; Iikura, Tomohiro; Morioka, Yusuke; Shino, Amiu; Ogata, Yoshiyuki; Date, Yasuhiro; Kikuchi, Jun

2013-01-01

268

78 FR 70953 - Draft Guidance for Industry on Bioequivalence Recommendations for Fluticasone Propionate...  

Federal Register 2010, 2011, 2012, 2013

...Fluticasone Propionate; Salmeterol Xinafoate; Reopening of the Comment...Fluticasone Propionate; Salmeterol Xinafoate'', published in the Federal...Fluticasone Propionate; Salmeterol Xinafoate.'' Interested...

2013-11-27

269

Fragrance material review on cyclotene propionate.  

PubMed

A toxicologic and dermatologic review of cyclotene propionate when used as a fragrance ingredient is presented. Cyclotene propionate is a member of the fragrance structural group ketones cyclopentanones and cyclopentenones. The common characteristic structural element of the group members is a cyclopentanone or cyclopentenone ring with a straight or branched chain alkane or alkene substituent. 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 cyclotene propionate were evaluated then summarized and includes physical properties data. A safety assessment of the entire Ketones cyclopentanones and cyclopentenones 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 Ketones Cyclopentanones and Cyclopentenones in fragrances. PMID:22449539

Scognamiglio, J; Jones, L; Letizia, C S; Api, A M

2012-10-01

270

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

2013-02-01

271

Acetate absorption in the normal and secreting rat jejunum.  

PubMed Central

Acetate absorption was studied in rat jejunum using steady state perfusion in vivo. Absorption conformed to apparent saturation kinetics and was similar in magnitude to glucose absorption. When compared with normal saline, acetate perfusion was associated with luminal alkalinisation. There was no difference in total CO2 secretion when similar rates of acetate and glucose absorption were compared, suggesting that total CO2 secretion was the result of mucosal metabolism. Absorption of acetate and propionate were mutually inhibitory. Acetate absorption was also inhibited by Tris-Hepes pH 7.0. When the gut was pretreated with cholera toxin to induce a secretory state, acetate absorption was reduced by 41.9%. This effect could be reproduced if similar water secretion was osmotically induced by the addition of mannitol. These data suggest that acetate is absorbed, at least, partially by non-ionic diffusion in the rat jejunum and that its absorption is reduced in the secreting intestine by solvent drag.

Watson, A J; Elliott, E J; Rolston, D D; Borodo, M M; Farthing, M J; Fairclough, P D

1990-01-01

272

Diffusion of propionic acid (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid; (2) air

Winkelmann, J.

273

Cellulose based bulk pH optomembranes  

Microsoft Academic Search

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

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

1998-01-01

274

Abiraterone acetate.  

PubMed

Abiraterone acetate (CB 7630; CB7630; JNJ-212082), the 3?-acetate prodrug of abiraterone, is structurally related to ketoconazole and is being developed by Cougar Biotechnology as a hormonal therapy for advanced prostate and breast cancers. As a selective inhibitor of adrenal androgens, it is thought to be a safer product than existing second-line hormonal therapies. This review discusses the key development milestones and therapeutic trials of this drug. PMID:21171672

2010-01-01

275

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

PubMed

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

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

2014-04-01

276

Biodegradability of PMMA Blends with Some Cellulose Derivatives  

Microsoft Academic Search

High polymer blends of Polymethyl methacrylate (PMMA) with cellulose acetate (CA) and Cellulose acetate phthalate (CAP) of varying blend compositions have been prepared to study their biodegradation behavior and blend miscibility. Films of PMMA–CA, and PMMA–CAP blends have been prepared by solution casting using Acetone and Dimethyl formamide(DMF) as solvents respectively. Biodegradability of these blends has been studied by four

D. Krishna Bhat; M. Selva Kumar

2006-01-01

277

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

Microsoft Academic Search

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

Ruslan N Ivanovsky; Elena N Krasilnikova; Ivan A Berg

1997-01-01

278

Esterification of cellulose with acyl-1 H -benzotriazole  

Microsoft Academic Search

For the first time, the acylation of cellulose was realized by activation of carboxylic acid with 1H-benzotriazole. The reaction could be carried out under mild conditions. The acyl-1H-benzotriazole reacts with cellulose leading to cellulose acetate, butyrate, caproate, benzoate, myristate, and stearate with\\u000a DS values between 1.07 and 1.89. The reaction proceeds completely homogeneously in dimethyl sulfoxide (DMSO)\\/TBAF × 3H2O (tetrabutylammonium fluoride trihydrate)

Matilde C. V. Nagel; Thomas Heinze

2010-01-01

279

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

280

Cellulose whiskers reinforced polyvinyl alcohol copolymers nanocomposites  

Microsoft Academic Search

Nanocomposite materials were prepared from copolymers of polyvinyl alcohol and polyvinyl acetate and a colloidal aqueous suspension of cellulose whiskers prepared from cotton linter. The degree of hydrolysis of the matrix was varied in order to vary the hydrophilic character of the polymer matrix and then the degree of interaction between the filler and the matrix. Nanocomposite films were conditioned

Mehdi Roohani; Youssef Habibi; Naceur M. Belgacem; Ghanbar Ebrahim; Ali Naghi Karimi; Alain Dufresne

2008-01-01

281

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

Federal Register 2010, 2011, 2012, 2013

...Propionic Acid and Salts, and Urea Sulfate...propionic acid and salts, and urea sulfate...2777 S. Crystal Dr., Arlington...2777 S. Crystal Dr., Arlington...pre-cleaned food contact surfaces...Propionic acid and its salts, sodium and calcium propionates...Propionic acid and salts, are exempt...

2010-08-18

282

Electrospun fullerenol-cellulose biocompatible actuators.  

PubMed

Though there are many stimuli-responsive polymer actuators based on synthetic polymers, electroactive natural biopolymer actuators are very rare. We developed an electrospun fullernol-cellulose biocompatible actuator with much lower power consumption and larger electromechanical displacement in comparison with a pure cellulose acetate actuator. Morphology of the electrospun membranes resembles the nanoporous structure of extracellular matrix in natural muscles. Presence of minute concentrations of fullerenol leads to sharp increase in the degree of crystallinity and substantial increase in tensile strength of membranes. Chemical interactions between cellulose acetate and fullerenols are confirmed by three shifts in carboxylate, carboxy, and carbonyl linkages from the Fourier-transform infrared spectrometry. Much larger tip displacement, nearly 3-fold even at 0.5 wt % fullerenol content, was observed with much lower power consumption under both alternating and direct current conditions. PMID:21517072

Li, Jia; Vadahanambi, Sridhar; Kee, Chang-Doo; Oh, Il-Kwon

2011-06-13

283

Acs is essential for propionate utilization in Escherichia coli.  

PubMed

Bacteria like Escherichia coli can use propionate as sole carbon and energy source. All pathways for degradation of propionate start with propionyl-CoA. However, pathways of propionyl-CoA synthesis from propionate and their regulation mechanisms have not been carefully examined in E. coli. In this study, roles of the acetyl-CoA synthetase encoding gene acs and the NAD(+)-dependent protein deacetylase encoding gene cobB on propionate utilization in E. coli were investigated. Results from biochemical analysis showed that, reversible acetylation also modulates the propionyl-CoA synthetase activity of Acs. Subsequent genetic analysis revealed that, deletion of acs in E. coli results in blockage of propionate utilization, suggesting that acs is essential for propionate utilization in E. coli. Besides, deletion of cobB in E. coli also results in growth defect, but only under lower concentrations of propionate (5mM and 10mM propionate), suggesting the existence of other propionyl-CoA synthesis pathways. In combination with previous observations, our data implies that, for propionate utilization in E. coli, a primary amount of propionyl-CoA seems to be required, which is synthesized by Acs. PMID:24835953

Liu, Fengying; Gu, Jing; Wang, Xude; Zhang, Xian-En; Deng, Jiaoyu

2014-07-01

284

Effect of sorbitan-based surfactants on glass transition temperature of cellulose esters  

Microsoft Academic Search

Thermal behavior of mixtures composed of cellulose acetate butyrate (CAB), carboxymethylcellulose acetate butyrate (CMCAB),\\u000a or cellulose acetate phthalate (CAPh), and sorbitan-based surfactants was investigated as a function of mixture composition\\u000a by means of differential scanning calorimetry (DSC). Surfactants with three different alkyl chain lengths, namely, polyoxyethylenesorbitan\\u000a monolaurate (Tween 20), polyoxyethylenesorbitan monopalmitate (Tween 40), and polyoxyethylene sorbitan monostearate (Tween\\u000a 60) were

Jorge Amim Jr; Leandro S. Blachechen; Denise F. S. Petri

285

Utilization of d-xylose as carbon source for production of bacterial cellulose  

Microsoft Academic Search

Utilization of d-xylose as carbon source for production of bacterial cellulose was studied. Seventeen strains of acetic acid bacteria were screened for their cellulose productivity in d-glucose, d-xylose, and d-xylose\\/d-xylulose mixed media, respectively. d-Xylose was not well metabolized by any bacterial strains that exhibited high cellulose production in d-glucose medium. Consequently, bacterial cellulose production in d-xylose medium was unsuccessful. d-Xylose,

Mitsuro Ishihara; Masahiro Matsunaga; Noriko Hayashi; Vesna Tišler

2002-01-01

286

Syntrophobacter pfennigii sp. nov., new syntrophically propionate-oxidizing anaerobe growing in pure culture with propionate and sulfate  

Microsoft Academic Search

A new strain of syntrophically propionate-oxidizing fermenting bacteria, strain KoProp1, was isolated from anoxic sludge\\u000a of a municipal sewage plant. It oxidized propionate or lactate in cooperation with the hydrogen- and formate-utilizing Methanospirillum hungatei and grew as well in pure culture without a syntrophic partner with propionate or lactate plus sulfate as energy source. In\\u000a all cases, the substrates were

Christina Wallrabenstein; Elisabeth Hauschild; Bernhard Schink

1995-01-01

287

21 CFR 175.230 - Hot-melt strippable food coatings.  

Code of Federal Regulations, 2013 CFR

...of 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

288

Electrospun nanofibrous cellulose scaffolds with controlled microarchitecture.  

PubMed

Introducing porosity in electrospun scaffolds is critical to improve cell penetration and nutrient diffusion for tissue engineering. Nanofibrous cellulose scaffolds were prepared by electrospinning cellulose acetate (CA) followed by saponification to regenerate cellulose. Using a computer-assisted design approach, scaffolds underwent laser ablation resulting in pores with diameters between 50 and 300 ?m without damaging or modifying the surrounding scaffold area. A new mineralization method was employed in conjunction with microablation using commercial phosphate buffered saline (PBS) to soak carboxymethylcellulose surface-modified electrospun scaffolds. The resulting crystals within the scaffold on the interior of the pore had a calcium to phosphate ratio of 1.56, similar to hydroxyapatite. It was observed that porosity of the cellulose scaffolds enhanced osteoblast cell attachment at the edge of the pores, while mineralization enhanced overall cell density. PMID:24188848

Rodríguez, Katia; Sundberg, Johan; Gatenholm, Paul; Renneckar, Scott

2014-01-16

289

Enhanced biofuel production through coupled acetic acid and xylose consumption by engineered yeast.  

PubMed

The anticipation for substituting conventional fossil fuels with cellulosic biofuels is growing in the face of increasing demand for energy and rising concerns of greenhouse gas emissions. However, commercial production of cellulosic biofuel has been hampered by inefficient fermentation of xylose and the toxicity of acetic acid, which constitute substantial portions of cellulosic biomass. Here we use a redox balancing strategy to enable efficient xylose fermentation and simultaneous in situ detoxification of cellulosic feedstocks. By combining a nicotinamide adenine dinucleotide (NADH)-consuming acetate consumption pathway and an NADH-producing xylose utilization pathway, engineered yeast converts cellulosic sugars and toxic levels of acetate together into ethanol under anaerobic conditions. The results demonstrate a breakthrough in making efficient use of carbon compounds in cellulosic biomass and present an innovative strategy for metabolic engineering whereby an undesirable redox state can be exploited to drive desirable metabolic reactions, even improving productivity and yield. PMID:24105024

Wei, Na; Quarterman, Josh; Kim, Soo Rin; Cate, Jamie H D; Jin, Yong-Su

2013-01-01

290

Cellulose synthase interacting protein  

PubMed Central

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

Somerville, Chris

2010-01-01

291

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

292

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

Microsoft Academic Search

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

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

2003-01-01

293

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

PubMed

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 pi-acceptor or with iodine as sigma-acceptor. Prolactin inhibitor was reacted directly with the previous reagents. The molar ratios of the reactants were established and the experimental conditions were studied giving maximum absorption at 588 and 290 nm with DDQ and iodine methods, respectively for the three drugs. The concentration ranges were 20-150,50-300, and 20-80 microg ml(-1) in DDQ method for (I), (II), and (III), respectively and 13-20,15-40, and 8-32 microg ml(-1) in iodine method for (I), (II) and (III), respectively. PMID:11836053

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

2002-03-01

294

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

295

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

296

Cellulose metabolism in plants.  

PubMed

Many bacterial genomes contain a cellulose synthase operon together with a cellulase gene, indicating that cellulase is required for cellulose biosynthesis. In higher plants, there is evidence that cell growth is enhanced by the overexpression of cellulase and prevented by its suppression. Cellulase overexpression could modify cell walls not only by trimming off the paracrystalline sites of cellulose microfibrils, but also by releasing xyloglucan tethers between the microfibrils. Mutants for membrane-anchored cellulase (Korrigan) also show a typical phenotype of prevention of cellulose biosynthesis in tissues. All plant cellulases belong to family 9, which endohydrolyzes cellulose, but are not strong enough to cause the bulk degradation of cellulose microfibrils in a plant body. It is hypothesized that cellulase participates primarily in repairing or arranging cellulose microfibrils during cellulose biosynthesis in plants. A scheme for the roles of plant cellulose and cellulases is proposed. PMID:16344110

Hayashi, Takahisa; Yoshida, Kouki; Park, Yong Woo; Konishi, Teruko; Baba, Kei'ichi

2005-01-01

297

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

2014-01-01

298

Liver transplantation in two cases of propionic acidaemia  

Microsoft Academic Search

Orthotopic liver transplantation (OLT) was performed in two patients with propionic acidaemia, a 7-year-old boy and a 9-year-old girl, diagnosed with a severe neonatal form with high risk of metabolic decompensation. In both cases the metabolic liver functions recovered within the 12 postoperative hours; no clinical symptoms of propionic acid toxicity, metabolic acidosis, severe hyperammonaemia, hyperglycinaemia or haematological abnormalities were

J. S. Schlenzig; F. Poggi-Travert; J. Laurent; D. Rabier; D. Jan; U. Wendel; A. C. Sewell; Y. Revillon; P. Kamoun; J. M. Saudubray

1995-01-01

299

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

300

Metabolism of [14C]propionic acid in broiler chicks.  

PubMed

Broiler chicks were given 4 or 120 mumol propionic[1-14C] acid by gavage to determine its chemical fate and distribution of radiolabel among organs and tissues [foregut (crop, gizzard, and proventriculus), intestine (small and large), ceca, liver, and serum]. At 15 and 60 min postgavage, most of the extractable radiolabel remaining in the chicks was found in the foregut. Significantly higher percentages of the administered radiolabel were detected at 15 min in the serum and liver extracts of chicks given 120 mumol of propionic acid than in chicks given only 4 mumol. After 15 min, 41 and 30%, respectively, of the total radiolabel administered was accounted for in extracts of the digestive tract and tissues of chicks given 4 or 120 mumol of [14C]propionic acid. Only about 12% of the administered radiolabel was extracted from body compartments at 60 min postgavage from chicks given 4 mumol of propionic acid. Collection of respired [14C]CO2 during a 3-h postgavage period indicated that orally administered propionic acid is largely (about 75%) used as an energy source or is metabolized and assimilated into body components. The present studies indicate that little if any dietary propionic acid reaches the lower digestive tract and the ceca. PMID:8502603

Hume, M E; Corrier, D E; Ivie, G W; Deloach, J R

1993-05-01

301

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

302

Cellulose Fibre Concrete.  

National Technical Information Service (NTIS)

In this investigation concretes and mortars containing different kinds of cellulose fibers were developed. The aim was to select suitable types of fibers for various kinds of concrete products. Four types of cellulose fibres and three manufacturing method...

S. Vares L. Sarvaranta M. Lanu

1997-01-01

303

Methyl Cellulose Nitrate.  

National Technical Information Service (NTIS)

Methyl cellulose nitrate was prepared by nitration of methyl cellulose with 98% nitric acid dissolved in methylene chloride and, in 98% nitric acid without a solvent. With both procedures nitration is apparently complete within fifteen minutes. The hetero...

J. Bobinski Y. P. Carignan

1967-01-01

304

Impact of phenolic compounds on hydrothermal oxidation of cellulose.  

PubMed

The effect of phenolic compounds on hydrothermal oxidation of cellulose was studied using a batch reactor at 300 degrees C with H(2)O(2) as oxidant. Intermediate products, as well as the yields of acetic acid produced in the oxidation of cellulose, phenolic compounds, and cellulose-phenolic compound mixtures were examined. Phenolic compounds used were phenol, 1,4-benzenediol, 2-methoxy-4-methylphenol, and 2,6-di-tert-butyl-4-methylphenol. In the case of oxidation of cellulose-phenolic compound mixtures, (1) formic acid, a basic oxidation product from carbohydrates, decreased considerably, (2) 5-hydroxymethyl-2-furaldehyde and 2-furaldehyde, acid-catalyzed dehydration products from carbohydrates, appeared, and (3) the yield of acetic acid increased compared to that in the oxidation of cellulose. From these results, phenolic compounds seem to inhibit the oxidation of cellulose under hydrothermal conditions. The inhibition of the oxidation of cellulose by phenolic compounds seems to be related closer to the stability of phenolic compounds under oxidation conditions rather than the ease to remove phenolic hydrogen on the OH group. PMID:17336951

Jin, Fangming; Cao, Jianxun; Kishida, Hisanori; Moriya, Takehiko; Enomoto, Heiji

2007-06-11

305

Blockade of Dendritic Cell Development by Bacterial Fermentation Products Butyrate and Propionate through a Transporter (Slc5a8)-dependent Inhibition of Histone Deacetylases  

PubMed Central

Mammalian colon harbors trillions of bacteria, yet there is no undue inflammatory response by the host against these bacteria under normal conditions. The bacterial fermentation products acetate, propionate, and butyrate are believed, at least in part, to be responsible for these immunosuppressive effects. Dendritic cells play an essential role in presentation of antigens to T lymphocytes and initiation of adaptive immune responses. Here we report that butyrate and propionate block the generation of dendritic cells from bone marrow stem cells, without affecting the generation of granulocytes. This effect is dependent on the Na+-coupled monocarboxylate transporter Slc5a8, which transports butyrate and propionate into cells, and on the ability of these two bacterial metabolites to inhibit histone deacetylases. Acetate, which is also a substrate for Slc5a8 but not an inhibitor of histone deacetylases, does not affect dendritic cell development, indicating the essential role of histone deacetylase inhibition in the process. The blockade of dendritic cell development by butyrate and propionate is associated with decreased expression of the transcription factors PU.1 and RelB. Butyrate also elicits its biologic effects through its ability to activate the G-protein-coupled receptor Gpr109a, but this mechanism is not involved in butyrate-induced blockade of dendritic cell development. The participation of Slc5a8 and the non-involvement of Gpr109a in butyrate effects have been substantiated using bone marrow cells obtained from Slc5a8?/? and Gpr109a?/? mice. These findings uncover an important mechanism underlying the anti-inflammatory functions of the bacterial fermentation products butyrate and propionate.

Singh, Nagendra; Thangaraju, Muthusamy; Prasad, Puttur D.; Martin, Pamela M.; Lambert, Nevin A.; Boettger, Thomas; Offermanns, Stefan; Ganapathy, Vadivel

2010-01-01

306

Blockade of dendritic cell development by bacterial fermentation products butyrate and propionate through a transporter (Slc5a8)-dependent inhibition of histone deacetylases.  

PubMed

Mammalian colon harbors trillions of bacteria, yet there is no undue inflammatory response by the host against these bacteria under normal conditions. The bacterial fermentation products acetate, propionate, and butyrate are believed, at least in part, to be responsible for these immunosuppressive effects. Dendritic cells play an essential role in presentation of antigens to T lymphocytes and initiation of adaptive immune responses. Here we report that butyrate and propionate block the generation of dendritic cells from bone marrow stem cells, without affecting the generation of granulocytes. This effect is dependent on the Na(+)-coupled monocarboxylate transporter Slc5a8, which transports butyrate and propionate into cells, and on the ability of these two bacterial metabolites to inhibit histone deacetylases. Acetate, which is also a substrate for Slc5a8 but not an inhibitor of histone deacetylases, does not affect dendritic cell development, indicating the essential role of histone deacetylase inhibition in the process. The blockade of dendritic cell development by butyrate and propionate is associated with decreased expression of the transcription factors PU.1 and RelB. Butyrate also elicits its biologic effects through its ability to activate the G-protein-coupled receptor Gpr109a, but this mechanism is not involved in butyrate-induced blockade of dendritic cell development. The participation of Slc5a8 and the non-involvement of Gpr109a in butyrate effects have been substantiated using bone marrow cells obtained from Slc5a8(-/-) and Gpr109a(-/-) mice. These findings uncover an important mechanism underlying the anti-inflammatory functions of the bacterial fermentation products butyrate and propionate. PMID:20601425

Singh, Nagendra; Thangaraju, Muthusamy; Prasad, Puttur D; Martin, Pamela M; Lambert, Nevin A; Boettger, Thomas; Offermanns, Stefan; Ganapathy, Vadivel

2010-09-01

307

Development of new chitosan–cellulose multicore microparticles for controlled drug delivery  

Microsoft Academic Search

Chitosan (CS) is a very interesting biomaterial for drug delivery; however its use in oral administration is restricted by its fast dissolution in the stomach and limited capacity for controlling the release of drugs. To address this limitation, a new microparticulate CS controlled release system, consisting of hydrophilic CS microcores entrapped in a hydrophobic cellulosic polymer, such as cellulose acetate

C Remuñán-López; M. L Lorenzo-Lamosa; J. L Vila-Jato; M. J Alonso

1998-01-01

308

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

309

Optimization of cellobiose dehydrogenase and ?-glucosidase production by cellulose-degrading cultures of Phanerochaete chrysosporium  

Microsoft Academic Search

The effect of succinate, acetate, and phosphate on the production of cellobiose dehydrogenase (CDH), cellobiose: quinone oxidoreductase (CBQase), ß-glucosidase, and protease by Phanerochaete chrysosporium in media containing cotton linters, filterpaper, microcrystalline cellulose, or acid-treated cellulose was investigated. The succinate medium,with an initial pH of 4.5 and with cotton linters as the cellulose source, has been demonstrated to yield the highest

W. Bao; E. Lymar; V. Renganathan

1994-01-01

310

Liquid-crystalline behavior of the cellulose derivatives suspended in the photocuring polymer binder  

NASA Astrophysics Data System (ADS)

Cellulose derivatives have been shown to form liquid crystalline solutions at high polymer concentration in a wide range of organic solvents. This paper describes the liquid crystalline behavior of the cellulose derivatives suspended in UV-curable polyester resin. The diffusion phenomena of the acetic acid and methanol to cellulose domain suspended in UV-curable liquid polyester resin was used for obtaining crystalline phase. The samples were investigated by thermo-optical, light and x-ray scattering methods.

Wojciechowski, Piotr; Mucha, Maria

1993-10-01

311

Emerging trends in management of propionic acidemia.  

PubMed

Objetivo : To evaluate the therapeutic agents used during metabolic crises and in long-term management of patients with propionic acidemia (PA).Materials and methods : The records of PA patients were retrospectively evaluated.Results : The study group consisted of 30 patients with 141 admissions. During metabolic crises, hyperammonemia was found in 130 (92%) admissions and almost all patients were managed with normal saline, ? 10% dextrose, and restriction of protein intake. In 56 (40%) admissions, management was done in intensive care unit, 31 (22%) with mechanical ventilation, 10 (7%) with haemodialysis, 16 (11%) with vasopressor agents, and 12 (9%) with insulin. In the rescue procedure, L-carnitine was used in 135 (96%) patients, sodium bicarbonate in 116 (82%), sodium benzoate in 76 (54%), and metronidazole in 10 (7%), biotin in about one-quarter, L-arginine in one third, and antibiotics in three-quarter of the admissions. Blood/packed RBCs were used in 28 (20%) patients, platelets in 26 (18%), fresh frozen plasma in 8 (6%), and granulocyte-colony stimulating factors in 10 (7%) admissions. All patients were managed completely/partially with medical nutrition formula plus amino acid mixture, vitamins and minerals. For long-term management 24 (80%) patients were on L-carnitine, 22 (73%) on sodium benzoate, 6 (20%) on biotin, one half on alkaline therapy and 4 (13%) on regular metronidazole use. Almost all patients were on medical formula and regular follow-up.Conclusion : Aggressive and adequate management of acute metabolic crises with restriction of protein intake, stabilization of patient, reversal of catabolism, and removal of toxic metabolites are essential steps. Concerted efforts to ensure adequate nutrition, to minimize the risk of acute decompensation and additional therapeutic advances are imperative to improve the outcome of PA patients. Arq Bras Endocrinol Metab. 2014;58(3):237-42. PMID:24863085

Rafique, Muhammad

2014-04-01

312

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

313

Liquid crystalline cellulose derivatives  

SciTech Connect

Following the observation that (hydroxypropyl)cellulose in water forms an ordered cholesteric liquid crystalline phase at high polymer concentrations, reports that many other cellulose derivatives in a wide variety of solvents also form liquid crystalline solutions have appeared in the scientific and patent literature. A tabulation of cellulose-based liquid crystalline systems is presented. The formation of the ordered phase is attributed to the limited flexibility of the cellulose chain. However, some cellulose derivatives form liquid crystalline phases only in specific solvents; concentrated solutions in other solvents remain isotropic. Other cellulose derivatives, such as (hydroxypropyl)cellulose, appear to form liquid crystalline solutions in any solvent that dissolves sufficiently high concentrations of the polymer. It has been suggested that the role of flexible side-chain substituents is to allow the main chains to achieve their equilibrium orientational order. The presence of many large substituents on the cellulose backbone also increases the effective chain radius and may change the chain conformation. The effect of side-chain structure on the properties of cellulose liquid crystalline phases is thus of interest. A series of esters of (hydroxypropyl)cellulose have been prepared. In addition to forming liquid crystalline solutions in organic solvents, these materials also were found to form cholesteric thermotropic phases in the absence of solvent. The thermotropic phases show spontaneous molecular orientation and cholesteric reflection. On heating, a transformation to the isotropic melt occurs. The liquid crystalline state of cellulose and its derivatives is thus widely observed. 42 references, 4 figures, 3 tables.

Gray, D.G.

1983-01-01

314

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

315

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

316

Self-reinforced cellulose nanocomposites  

Microsoft Academic Search

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

Anthony Abbott; Alexander Bismarck

2010-01-01

317

Dialkylimidazolium ionic liquids hydrolyze cellulose under mild conditions.  

PubMed

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

Gazit, Oz M; Katz, Alexander

2012-08-01

318

Fractionation of Serum Protein by cm-Cellulose Column.  

National Technical Information Service (NTIS)

Employing CM-cellulose column, serum protein is eluted with pH 5.4 acetate buffer, and the composition of each fraction is identified by the paper electrophoresis of each fraction and the comparison of its chromatogram with that of standard albumin and gl...

Y. Tanaka Y. Iwashita Y. Nakakima T. Kohi S. Noguchi

1966-01-01

319

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

320

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

PubMed Central

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

2012-01-01

321

Xyloglucan in cellulose modification  

Microsoft Academic Search

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

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

2007-01-01

322

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

323

The use of polyurethane foam for microbial retention in methanogenic fermentation of propionate  

Microsoft Academic Search

The use of polyurethane foam (PUF) as a microbial support carrier was evaluated with a mesophilic propionate-acclimatized sludge. The acclimatized sludge could be immobilized rapidly and stably in PUF of smaller pore size under shaking conditions. The sludge retained in PUF could maintain a high propionate metabolic activity for a long period. High conversion rates of propionate to methane of

Satoshi Fukuzaki; Naomichi Nishio; Shiro Nagai

1990-01-01

324

Stable Crystalline Cellulose III Polymorphs.  

National Technical Information Service (NTIS)

The invention relates to production of ammonia mercerized cellulose. More specifically, the invention relates to treating cellulose fiber with vapors of ammonia to produce stable cellulose III polymorphs. The primary objective is to provide a method for p...

L. Y. Yatsu T. A. Calamari R. R. Benerito

1987-01-01

325

Diffusion of propionic acid ethyl ester (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid ethyl ester; (2) air

Winkelmann, J.

326

Diffusion of propionic acid pentyl ester (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid pentyl ester; (2) air

Winkelmann, J.

327

Diffusion of propionic acid methyl ester (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid methyl ester; (2) air

Winkelmann, J.

328

Diffusion of propionic acid isobutyl ester (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid isobutyl ester; (2) air

Winkelmann, J.

329

Diffusion of propionic acid butyl ester (1); air (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) propionic acid butyl ester; (2) air

Winkelmann, J.

330

In vitro evaluation of cashew nut shell liquid as a methane-inhibiting and propionate-enhancing agent for ruminants.  

PubMed

Cashew nut shell liquid (CNSL) containing antibacterial phenolic compounds was evaluated for its potency as a feed additive for ruminants. In experiment 1, ruminal responses to CNSL supplementation were assessed using a batch culture system. Rumen fluid from cattle was diluted with artificial saliva and incubated for 18h in a batch culture with a mixed diet containing a 30:70 hay:concentrate diet to which raw or heated CNSL was added at a final concentration of 500 ?g/mL. In experiment 2, a Rusitec, using rumen fluid from the same cattle, was operated over a period of 7 d during which only raw CNSL was tested at concentrations of 0, 50, 100, or 200 ?g/mL, and variations in fermentation and bacterial population were assessed. In experiment 3, a pure culture study was conducted using selected bacteria to determine their susceptibility to CNSL. In experiment 1, methane production was inhibited by raw CNSL (56.9% inhibition) but not by heated CNSL. Total volatile fatty acid concentration was not affected, whereas increased concentrations of propionate and decreased concentrations of acetate and butyrate were observed using either raw or heated CNSL. These changes were more obvious when raw CNSL was tested. In experiment 2, raw CNSL inhibited methanogenesis and increased propionate production in a dose-dependent manner, showing maximum methane inhibition (70.1%) and propionate enhancement (44.4%) at 200 ?g/mL supplementation. Raw CNSL increased total volatile fatty acid concentration and dry matter digestibility. Raw CNSL also appeared to induce a dramatic shift in the population of rumen microbiota, based on decreased protozoa numbers and changes in quantitative PCR assay values for representative bacterial species. In experiment 3, using pure cultures, raw CNSL prevented the growth of hydrogen-, formate-, and butyrate-producing rumen bacteria, but not the growth of bacteria involved in propionate production. Based on these data, raw CNSL, rich in the antibacterial phenolic compound anacardic acid, is a potential candidate feed additive with selective activity against rumen microbes, leading to fermentation that results in decreased methane and enhanced propionate production. PMID:20965342

Watanabe, Y; Suzuki, R; Koike, S; Nagashima, K; Mochizuki, M; Forster, R J; Kobayashi, Y

2010-11-01

331

Effect of Nickelous and Other Metal Ions on the Inhibition of Rumen Bacterial Metabolism by 3-(3?-Isocyanocyclopent-2-Enylidene)Propionic Acid and Related Isocyanides †  

PubMed Central

3-(3?-Isocyanocyclopent-2-enylidene)propionic acid at a concentration of 2 to 5 ?g ml?1 inhibited cellulose digestion by a mixed culture of rumen microorganisms and in other experiments inhibited the degradation of timothy hay (Phleum pratense) in a digestibility test. At isocyanide concentrations of 12 ?g ml?1 the fermentation activity of rumen fluid, measured by its dehydrogenase activity, was inhibited but not abolished. All of these isocyanide effects were reversed by the incorporation of nickelous ion into the solutions of the systems under study. The activity of 1 mol of isocyanide is reversed by about 1 mol of Ni2+ and, in the case of the cellulose digestion test, by about 1 mol of Co2+. Of some 15 other ions tested only Pd2+ and possibly chromium reversed the effect of the isocyanide.

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

1986-01-01

332

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

333

Retention of Cationic Starch onto Cellulose Fibres  

NASA Astrophysics Data System (ADS)

Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV-vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan-based molecules and quantifying the ensuing mixture by measuring their absorbance at a ? of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro-acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.

Missaoui, Mohamed; Mauret, Evelyne; Belgacem, Mohamed Naceur

2008-08-01

334

Single Particle Friction Tests with Cellulose Acetate Sphere Samples.  

National Technical Information Service (NTIS)

This report represents a detailed account of all the experimental work carried out for LLNL using the ''single particle shear cell'' in the department of Chemical & Process Engineering of Surrey University, Guildford, United Kingdom. Experimental work wit...

U. Tuezen

1989-01-01

335

Single particle friction tests with cellulose acetate sphere samples  

SciTech Connect

This reporter represents a detailed account of all the experimental work carried out for LLNL using the ''single particle shear cell'' in the department of Chemical Process Engineering of Surrey University, Guildford, United Kingdom. Experimental work with two spheres in contact was performed. Particles were positioned into the specially made sample holders by the micro screws. The contact centres were lined up under the magnifying glass. The behavior of the interparticle contact region between the two spheres was examined by performing the following series of tests: (i) normal force versus normal displacement test, (ii) tangential force limit at gross sliding with increased normal load and decreasing normal load, (iii) tangential force versus micro displacement during initial loading to friction limit and during unloading from friction limit. Work was also performed on single sphere against a flat wall surface. Results are discussed. 34 figs.

Tuezen, U.

1989-05-31

336

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

337

Nanofibrillar cellulose aerogels  

Microsoft Academic Search

Highly porous aerogels consisting of cellulose nanofibrils were prepared by dissolution\\/regeneration of cellulose in aq. calcium thiocyanate followed by regeneration and carefully controlled drying. The influence of drying method (regular freeze drying, rapid freeze drying, and solvent exchange drying) on resulting porosity was studied by electron microscopy and nitrogen adsorption. While regular freeze drying caused significant coalescence of microfibrillar units,

Hao Jin; Yoshiharu Nishiyama; Masahisa Wada; Shigenori Kuga

2004-01-01

338

Wrinkle resistant cellulosic textiles  

SciTech Connect

This patent describes a process for treating a cellulosic textile material so as to impart wrinkle resistance and smooth drying properties. It comprises treating the cellulosic textile material with an aqueous solution comprising trans-1,2,3,4-cyclobutane tetracarboxylic acid, and a curing catalyst, and heating the treated material so as to produce esterification and crosslinking of the material with the acid.

Kitchens, J.D.; Patton, R.T.; Nadar, R.S.

1991-08-27

339

Design and Evaluation of Ethyl Cellulose Based Matrix Tablets of Ibuprofen with pH Modulated Release Kinetics  

PubMed Central

Controlled release preparations have been reported to reduce the gastro irritant and ulcerogenic effects of non steroidal antiinflammatory drugs. In the present study, an attempt was made to develop matrix tablet-based controlled release formulations of ibuprofen, using ethyl cellulose as the rate-controlling polymer. In order to prevent initial release of the drug in the acidic environment of the stomach, cellulose acetate phthalate was incorporated in the matrix in varying amounts. It was found that with increasing the proportion of ethyl cellulose in the matrix, the drug release was extended for 14-16 h. Incorporation of cellulose acetate phthalate in ethyl cellulose matrix provided very low initial release of the drug in the first 2-3 h followed by enhanced release rate in alkaline medium owing to the high solubility of cellulose acetate phthalate at basic pH which led to creation of a porous matrix. It was concluded that combination of cellulose acetate phthalate with ethyl cellulose in the matrix base can be an effective means of developing a controlled release formulation of ibuprofen with very low initial release followed with controlled release up to 14-16 h.

Chandran, S.; Asghar, Laila F. A.; Mantha, Neelima

2008-01-01

340

Design and Evaluation of Ethyl Cellulose Based Matrix Tablets of Ibuprofen with pH Modulated Release Kinetics.  

PubMed

Controlled release preparations have been reported to reduce the gastro irritant and ulcerogenic effects of non steroidal antiinflammatory drugs. In the present study, an attempt was made to develop matrix tablet-based controlled release formulations of ibuprofen, using ethyl cellulose as the rate-controlling polymer. In order to prevent initial release of the drug in the acidic environment of the stomach, cellulose acetate phthalate was incorporated in the matrix in varying amounts. It was found that with increasing the proportion of ethyl cellulose in the matrix, the drug release was extended for 14-16 h. Incorporation of cellulose acetate phthalate in ethyl cellulose matrix provided very low initial release of the drug in the first 2-3 h followed by enhanced release rate in alkaline medium owing to the high solubility of cellulose acetate phthalate at basic pH which led to creation of a porous matrix. It was concluded that combination of cellulose acetate phthalate with ethyl cellulose in the matrix base can be an effective means of developing a controlled release formulation of ibuprofen with very low initial release followed with controlled release up to 14-16 h. PMID:21394255

Chandran, S; Asghar, Laila F A; Mantha, Neelima

2008-09-01

341

Preparation of cellulose and cellulose derivative azo compounds  

Microsoft Academic Search

Wood pulp and cotton linter are the most common sources of cellulose forindustrial use. Methyl cellulose (MC) and cellulose sulfate (CS) were preparedusing bleached wood pulp and cotton linter. Coloured azo compounds were alsoprepared from coupling cellulose, wood pulp, MC and CS with aromatic diazoniumsalt. The presence of electron-releasing or withdrawing substituents affectedthe electrophilic substitution reaction. The produced azo compounds

Maha Ibrahim

2002-01-01

342

Cellulose Metabolism by the Termite Flagellate Trichomitopsis termopsidis  

PubMed Central

The end products of cellulose metabolism by the trichomonad flagellate Trichomitopsis termopsidis from the termite Zootermopsis sp. were investigated by growing axenic flagellates on [14C]cellulose. The growth of T. termopsidis resulted in the release of label into the supernatant fraction of the culture fluid, and > 75% was volatile under acid conditions. The label was analyzed for 14CO2 and for [14C]volatile compounds by vacuum distillation under acid and alkaline conditions in disposable micro-distillation vessels. The distillate and undistilled culture supernatant fluid were chromatographed on cellulose thin layers to identify the labeled end product. T. termopsidis produced 14CO2 and [14C]acetate which accounted for 25 to 30% and 55 to 60% of the labeled end products, respectively. The ratio of label in CO2 to acetate suggests that they are produced in equimolar amounts. No neutral volatile compounds were produced. The remaining unidentified end product (10 to 20%) was not volatile nor extractable into ether. Hydrogen was produced by T. termopsidis, and the cells were killed by the drug metronidazole. Enzymatic activities were found which account for these end products: pyruvate:ferredoxin oxidoreductase and hydrogenase. The results indicate that acetate is the end product of T. termopsidis cellulose metabolism and is available to the termite for energy metabolism and biosynthesis.

Yamin, Michael A.

1980-01-01

343

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

344

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

PubMed

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

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

2014-01-01

345

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

2013-01-01

346

[13C]propionate oxidation in wild-type and citrate synthase mutant Escherichia coli: evidence for multiple pathways of propionate utilization.  

PubMed Central

The metabolism of propionate was examined in wild-type Escherichia coli and cells lacking citrate synthase by high-resolution 13C n.m.r. Spectra of cell extracts from wild-type E. coli show that glutamate becomes highly enriched in 13C when 13C-enriched propionate is the sole carbon source. No glutamate labelling was detected when the tricarboxylic acid cycle was blocked either by deletion of citrate synthase or by inhibition of succinate dehydrogenase by malonate. The 13C fractional enrichment in glutamate C-2, C-3 and C-4 in wild-type cells was quantitatively and qualitatively different when [2-13C]propionate as opposed to [3-13C]propionate was supplied. Approximately equal labelling occurred in the C-2, C-3 and C-4 positions of glutamate when [3-13C]propionate was available, and multiplets due to carbon-carbon spin-spin coupling were observed. However, in cells supplied with [2-13C]propionate, very little 13C appeared in the glutamate C-4 position, and the remaining glutamate resonances all appeared as singlets. The unequal and non-identical labelling of glutamate in cells supplied with [2-13C]- as opposed to [3-13C]propionate is consistent with the utilization of propionate by E. coli via two pathways, oxidation of propionate to pyruvate and carboxylation of propionate to succinate. These intermediates are further metabolized to glutamate by the action of the tricarboxylic acid cycle. The existence of an organized tricarboxylic acid cycle is discussed as a consequence of the ability to block utilization of propionate in tricarboxylic acid-cycle-defective E. coli.

Evans, C T; Sumegi, B; Srere, P A; Sherry, A D; Malloy, C R

1993-01-01

347

Higher plant cellulose synthases  

PubMed Central

Cellulose, an aggregate of unbranched polymers of ?-1,4-linked glucose residues, is the major component of wood and thus paper, and is synthesized by plants, most algae, some bacteria and fungi, and even some animals. The genes that synthesize cellulose in higher plants differ greatly from the well-characterized genes found in Acetobacter and Agrobacterium sp. More correctly designated as 'cellulose synthase catalytic subunits', plant cellulose synthase (CesA) proteins are integral membrane proteins, approximately 1,000 amino acids in length. The sequences for more than 20 full-length CesA genes are available, and they show high similarity to one another across the entire length of the encoded protein, except for two small regions of variability. There are a number of highly conserved residues, including several motifs shown to be necessary for processive glycosyltransferase activity. No crystal structure is known for cellulose synthase proteins, and the exact enzymatic mechanism is unknown. There are a number of mutations in cellulose synthase genes in the model organism Arabidopsis thaliana. Some of these mutants show altered morphology due to the lack of a properly developed primary or secondary cell wall. Others show resistance to well-characterized cellulose biosynthesis inhibitors.

Richmond, Todd

2000-01-01

348

Seasonal allergic rhinitis: fluticasone propionate and fluticasone furoate therapy evaluated  

PubMed Central

Seasonal allergic rhinitis (SAR) is increasing in prevalence such that 1 in 4 persons is affected in the UK. It represents a considerable burden of disease since in a significant proportion of individuals the severity of nasal–ocular symptoms has an important effect on daily activity, performance and quality of life. Intranasal steroids (INS) form the mainstay of treatment, having been shown in meta-analyses to be superior to oral antihistamines, intranasal antihistamines and anti-leukotrienes. Fluticasone propionate is an established INS for the treatment of rhinitis, including SAR. Its favorable pharmacological profile combining high local efficacy with low systemic bioavailability has established fluticasone propionate as an effective intervention. The more recent introduction of structurally related fluticasone furoate with similar but enhanced pharmacological characteristics with a novel delivery device may confer further therapeutic advantages.

Kariyawasam, Harsha H; Scadding, Glenis K

2010-01-01

349

Acute psychosis in propionic acidemia: 2 case reports.  

PubMed

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

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

2014-02-01

350

Hepatic metabolism of propionate and methylmalonate in growing lambs  

Microsoft Academic Search

The hepatic extraction ratio of propionate and the net hepatic flux of methylmalonate (MMA) were investigated in six Suffolk lambs (32.7±1.7 kg BW) implanted with catheters in a mesenteric artery and in the portal, hepatic, and ruminal veins and a cannula in the rumen. The lambs were fed a pelleted barley-based diet (1.1 kg DM per day) and subjected to

V Berthelot; S. G Pierzynowski; D Sauvant; N. B Kristensen

2002-01-01

351

Bioavailability of fluticasone propionate and mometasone furoate aqueous nasal sprays  

Microsoft Academic Search

Objectives To compare the systemic exposure for intranasal mometasone furoate (MF) and fluticasone propionate (FP) aqueous nasal sprays (ANS) in terms of serum and urinary cortisol parameters and plasma pharmacokinetics. Methods Twelve healthy subjects completed this three-way, cross-over study. They received FPANS (50 µg\\/spray), MFANS (50 µg\\/spray) or placebo ANS, eight sprays per nostril every 8 h for 4 days. Cortisol measurements were made

P. T. Daley-Yates; R. L. Kunka; Y. Yin; S. M. Andrews; S. Callejas; C. Ng

2004-01-01

352

Synthesis and Mesomorphic Properties of Naphthyl Propionate Ferroelectric Liquid Crystals  

Microsoft Academic Search

Ferroelectric liquid crystalline compounds containing (2 S )-2-(6-hydroxy-2-naphthyl)propionic acid moiety were synthesized from ( S )-naproxen ( 1 ). Reactions of ( S )-naproxen chloride with alkanols (C 4 -C 6 ) in the presence of propylene oxide gave chiral esters 4 . Demethylation of 4 with dimethylsulfide-AlCl 3 produced naphthols 5 . Esterfication of naphthols 5 with 4-(4-alkoxyphenyl)benzoic acid

Kyung-Tae Kang; Chang Mo Kim; Seng Kue Lee; Myung Soo Shin; Kyung Uk Lee; Jong Gun Lee; Jin Wook Choi; Yong Bae Kim

2002-01-01

353

[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

354

The role of the heme propionates in heme biochemistry.  

PubMed

There are numerous studies, relying on both experimental and theoretical observations, illustrating the active role of the heme propionates in regulating electron delivery to the iron center as well as biochemical properties of the heme. Evidences for this come from a wide variety of heme containing systems: cytochromes, heme peroxidases, globins, etc. Here, we shortly summarize these studies and revisit previous theoretical calculations (V. Guallar, M.H. Baik, S.J. Lippard, R.A. Friesner, Proc. Natl. Acad. Sci. USA 100 (2003) 6998-7002) where the propionate groups induced the delocalization of the spin density in the cytochrome P450cam putative active species, Compound I. We introduce novel data, obtained by means of mixed quantum mechanics and molecular mechanics methods, indicating a larger electron delocalization into the protein. We also present novel results based on the recent migration of spin density observed by Barrows et al. (T.P. Barrows, T.L. Poulos, Biochemistry 44 (2005) 14062-68) on an ascorbate peroxidase mutant. All this data strongly supports the importance of the propionate groups in tuning the heme electronic properties. PMID:16513175

Guallar, Victor; Olsen, Brett

2006-04-01

355

Cellulose, Food and Energy.  

National Technical Information Service (NTIS)

The potential of cellulose as a source of energy and food is reviewed with consideration of raw material sources, processing methods, and economics. A tentative scheme for production of Torula yeast and ethanol from sugars produced by enzymatic hydrolysis...

C. R. Wilke

1977-01-01

356

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

357

Preparation of vinyl acetate  

DOEpatents

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

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

1998-01-01

358

Preparation of vinyl acetate  

DOEpatents

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

Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

1998-03-24

359

Characterization of epitaxial YBa2Cu3O7-? films deposited by metal propionate precursor solution  

NASA Astrophysics Data System (ADS)

YBa2Cu3O7-?(YBCO) films were deposited with a low-fluorine modified trifluoroacetate metalorganic deposition (TFA-MOD) method on SrTiO3 single crystals and buffered Ni-W metallic tape with a thickness ranging from 450 to 600 nm. The method consists in the substitution of yttrium and copper trifluoroacetates with Cu and Y acetates dispersed in propionic acid. A reduced pyrolysis time with respect to the usual TFA method is obtained. Apart from CuO, no traces of second phases are revealed by x-ray measurements. The films are compact without cracks, and exhibit a slight superficial porosity, but they still remain well connected, and therefore the observed porosity does not affect either the critical current density or the normal state resistivity values, which are indicative of high-quality YBCO films. Moreover, YBCO films were also obtained on Pd-buffered Ni-W, with a CeO2/YSZ/CeO2 buffer layer architecture. These films show good morphological, structural, and superconductive properties with high critical temperature (higher than 91 K) and critical current density higher than 1 MA cm-2 at 77 K in self-field.

Angrisani Armenio, A.; Augieri, A.; Ciontea, L.; Contini, G.; Davoli, I.; Galluzzi, V.; Mancini, A.; Rufoloni, A.; Petrisor, T.; Vannozzi, A.; Celentano, G.

2008-12-01

360

Mass isotopomer study of anaplerosis from propionate in the perfused rat heart  

PubMed Central

Anaplerosis from propionate was investigated in rat hearts perfused with 0–2 mM [13C3]propionate and physiological concentrations of glucose, lactate and pyruvate. The data show that when the concentration of [13C3]propionate was raised from 0 to 2 mM, total anaplerosis increases from 5 to 16% of the turnover of citric acid cycle intermediates. Then, [13C3]propionate abolished anaplerosis from endogenous substrates, glucose, lactate and pyruvate. Also, while the contents of propionyl-CoA and methylmalonyl-CoA increased with [13C3]propionate concentration, the content of succinyl-CoA decreased, presumably via activation of succinyl-CoA hydrolysis by a decrease in free CoA. Under our conditions, [13C3]propionate was a purely anaplerotic substrate since there was no labeling of mitochondrial acetyl-CoA, reflected by the labeling of the acetyl moiety of citrate.

Kasumov, Takhar; Cendrowski, Andrea V.; David, France; Jobbins, Kathryn A.; Anderson, Vernon E.; Brunengraber, Henri

2007-01-01

361

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

362

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

363

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

364

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

365

Biological production of hydrogen from cellulose by natural anaerobic microflora  

Microsoft Academic Search

The capability of natural anaerobic microflora to produce hydrogen was examined with artificial wastewater containing cellulose. The microflora in sludge compost was found to produce a significant amount of hydrogen (2.4 mol\\/mol-hexose). Among the fermentation products other than hydrogen and carbon dioxide, the lower fatty acids, mainly acetate and butyrate, constituted more than approximately 90% of the total soluble metabolites.

Yoshiyuki Ueno; Tatsushi Kawai; Susumu Sato; Seiji Otsuka; Masayoshi Morimoto

1995-01-01

366

Ethanol from cellulosics  

SciTech Connect

The current major research and development effort in the U.S. to improve technology for the conversion of cellulosic waste is justified by the potential utilization of hundreds of millions of tons per year of agricultural and forest wastes. Cellulose must first be hydrolyzed to hexose monosacharides (mainly glucose) before it can be fermented to ethanol. Although many hydrolysis processes have been investigated, only hydrolysis using dilute mineral acid has been commercialized. In the reported experiments, an ethanol-from-cellulose process simulation was developed for implementation on an IBM 5120 computer, utilizing APL computer language. The model calculates material balances, utility balances and factored capital costs for the entire process, starting with any cellulosic feedstock and producing anhydrous ethanol and other by-products. Data are presented which demonstrate that prehydrolysis is the most useful pretreatment. It can accomplish virtually the same physical changes as steam explosion, while also performing a mild hydrolysis on accessible cellulose. Yields are higher with this step than without, and formation of by-product HMF and furfural is minimized.

Mednick, R.L.; Weiss, L.H.; Xippolitos, E.G.

1982-08-01

367

Fermentative degradation of nonionic surfactants and polyethylene glycol by enrichment cultures and by pure cultures of homoacetogenic and propionate-forming bacteria.  

PubMed

Linear alkyl ethoxylates (polyethylene glycol alkyl ethers) were fermented completely to methane and CO2 in enrichment cultures inoculated with anoxic sewage sludge. Long-chain fatty acids were released as intermediates. No degradation was found with polypropylene glycol and polypropylene glycol-containing surfactants. Two types of primary ethoxylate-degrading bacteria were isolated and characterized. Both degraded polyethylene glycols with molecular weights of 1,000 completely. Strain KoB35 fermented polyethylene glycol, ethoxyethanol, and lactate to acetate and propionate and was assigned to the described species Pelobacter propionicus. Strain KoB58 converted polyethylene glycol and many other substrates to acetate only and was assigned to the genus Acetobacterium. The pathways of anaerobic degradation of nonionic surfactants are discussed with respect to their limitations and the various groups of bacteria involved. PMID:3355141

Wagener, S; Schink, B

1988-02-01

368

Temporal Integration in Nasal Lateralization of Homologous Propionates  

PubMed Central

For nasal irritation from volatile chemicals, a version of Haber’s rule (k = CnT) can model the trade-off between concentration (C) and duration of exposure (T) to achieve a fixed sensory impact, e.g., threshold-level irritation or a fixed supra-threshold intensity. The term “k” is a constant. The exponent, n, represents how well the system integrates over time. An exponent of 1 indicates complete temporal integration: an x-fold increase in stimulus-duration exactly compensates for cutting concentration 1/x. An exponent greater than 1 indicates incomplete temporal integration: more than an x-fold increase in duration is needed. In a previous study of homologous alcohols, n varied systematically with number of methylene units: integration became more compete as the length of the carbon chain increased. To explore the generality of this finding, we tested homologous esters that differ in number of methylene units: n-ethyl propionate, n-propyl propionate, and n-butyl propionate. Nasal lateralization was used to measure irritation thresholds. Human subjects received a fixed concentration of a single compound within each experimenal session. Stimulus-duration was varied to find the briefest stimulus that caused lateralizable irritation. Concentration and compound varied across sessions. Consistent with results with n-alcohols, integration became more complete as the number of methylene units increased. Lipid solubility varies with chain-length; hence solubility in the nasal mucosa may play a role in the dynamics of irritation. Further, preliminary analyses suggest that, for data pooled across both chemical series, n varied systematically with molecular parameters related to solubility and diffusion.

Wise, Paul M.; Toczydlowski, Sean E.; Zhao, Kai; Wysocki, Charles J.

2009-01-01

369

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

370

The cellulose resource matrix.  

PubMed

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

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

2013-03-01

371

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

PubMed

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

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

2013-06-10

372

Purification and properties of the Streptomyces peucetius DpsC beta-ketoacyl:acyl carrier protein synthase III that specifies the propionate-starter unit for type II polyketide biosynthesis.  

PubMed

Biosynthesis of the polyketide-derived carbon skeleton of daunorubicin (DNR) begins with propionate rather than acetate, which is the starter unit for most other aromatic polyketides. The dpsCgene has been implicated in specifying the unique propionate-starter unit, and it encodes a protein that is very similar to the Escherichia coli beta-ketoacyl:acyl carrier protein (ACP) synthase III (FabH or KS III) enzyme of fatty acid biosynthesis. Purified DpsC was found to use propionyl-coenzyme A as substrate and to be acylated by propionate at the Ser-118 residue. DpsC exhibits KS III activity in catalyzing the condensation of propionyl-CoA and malonyl-ACP, and also functions as an acyltransferase in the transfer of propionate to an ACP. The DpsC enzyme has a high-substrate specificity, utilizing only propionyl-CoA, and not malonyl-CoA, 2-methylmalonyl-CoA or acetyl-CoA, as the starter unit of DNR biosynthesis. PMID:10423255

Bao, W; Sheldon, P J; Hutchinson, C R

1999-07-27

373

Size Effects of Nanocrystalline Cellulose  

Microsoft Academic Search

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

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

2003-01-01

374

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

375

Mechanisms of acetate formation and acetate activation in halophilic archaea  

Microsoft Academic Search

The halophilic archaea Halococcus (Hc.) saccharolyticus, Haloferax (Hf.) volcanii, and Halorubrum (Hr.) saccharovorum were found to generate acetate during growth on glucose and to utilize acetate as a growth substrate. The mechanisms of acetate formation from acetyl-CoA and of acetate activation to acetyl-CoA were studied. Hc. saccharolyticus, exponentially growing on complex medium with glucose, formed acetate and contained ADP-forming acetyl-CoA

Christopher Bräsen; Peter Schönheit

2001-01-01

376

[Advances in functional genomics studies underlying acetic acid tolerance of Saccharomyces cerevisiae].  

PubMed

Industrial microorganisms are subject to various stress conditions, including products and substrates inhibitions. Therefore, improvement of stress tolerance is of great importance for industrial microbial production. Acetic acid is one of the major inhibitors in the cellulosic hydrolysates, which affects seriously on cell growth and metabolism of Saccharomyces cerevisiae. Studies on the molecular mechanisms underlying adaptive response and tolerance of acetic acid of S. cerevisiae benefit breeding of robust strains of industrial yeast for more efficient production. In recent years, more insights into the molecular mechanisms underlying acetic acid tolerance have been revealed through analysis of global gene expression and metabolomics analysis, as well as phenomics analysis by single gene deletion libraries. Novel genes related to response to acetic acid and improvement of acetic acid tolerance have been identified, and novel strains with improved acetic acid tolerance were constructed by modifying key genes. Metal ions including potassium and zinc play important roles in acetic acid tolerance in S. cerevisiae, and the effect of zinc was first discovered in our previous studies on flocculating yeast. Genes involved in cell wall remodeling, membrane transport, energy metabolism, amino acid biosynthesis and transport, as well as global transcription regulation were discussed. Exploration and modification of the molecular mechanisms of yeast acetic acid tolerance will be done further on levels such as post-translational modifications and synthetic biology and engineering; and the knowledge obtained will pave the way for breeding robust strains for more efficient bioconversion of cellulosic materials to produce biofuels and bio-based chemicals. PMID:25007573

Zhao, Xinqing; Zhang, Mingming; Xu, Guihong; Xu, Jianren; Bai, Fengwu

2014-03-01

377

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

378

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

Federal Register 2010, 2011, 2012, 2013

...Federal Register Volume 75, Number 240 (Wednesday, December...FRL-8855-5] Propionic Acid and Salts, Urea Sulfate...identification (ID) number EPA-HQ-OPP-2010-0650...Docket Facility telephone number is (703) 305-5805...table below--propionic acid and salts, case...

2010-12-15

379

Solvent infusion processing of all-cellulose composite materials.  

PubMed

Continuous fibre-reinforced all-cellulose composite (ACC) laminates were produced in the form of a dimensionally thick (>1 mm) laminate using an easy-to-use processing pathway termed solvent infusion processing (SIP) from a rayon (Cordenka™) textile using the ionic liquid 1-butyl-3-methylimidazolium acetate. SIP facilitates the infusion of a solvent through a dry cellulose fibre preform with the aim of partially dissolving the outer surface of the cellulose fibres. The dissolved cellulose is then regenerated by solvent exchange to form a matrix phase in situ that acts to bond together the undissolved portion of the fibres. SIP is capable of producing thick, dimensionally stable ACC laminates with high volume fractions of continuous fibres (>70 vol.%) due to the combination of two factors: (i) homogeneous and controlled partial dissolution of the fibres and (ii) the application of pressure during regeneration and drying that provides a high level of fibre compaction, thereby overcoming void formation associated with material shrinkage. The effect of inlet and outlet positioning, and applied pressure on the macro- and microstructure of all-cellulose composites is examined. Finally, SIP expands the applications for ACCs by enabling the production of thick ACC laminates to overcome the limitations of conventional thin-film ACCs. PMID:24751100

Huber, Tim; Bickerton, Simon; Müssig, Jörg; Pang, Shusheng; Staiger, Mark P

2012-09-01

380

Alcohol from cellulose  

SciTech Connect

A process is described which completely converts cellulose to fermentable sugars as compared to 50-70% conversion obtained with other methods. The process uses chemical solvents followed by hydrolysis. The new method was tried using corn residue and bagasse. It is stated that the pretreated substances showed much improved conversions over untreated corn residue and bagasse.

Hsu, T.A.; Ladisch, M.R.; Tsao, G.T.

1980-05-01

381

Alcohol from cellulose  

SciTech Connect

A process is described which completely converts cellulose to fermentable sugars as compared to 50 to 70% conversion obtained with other methods. The process uses chemical solvents followed by hydrolysis. The new method was tried using corn residue and bagasse. 18 references. 18 references. It is stated that the pretreated substances showed much improved conversions over untreated corn residue and bagasse.

Hsu, T.A.; Ladisch, M.R.; Tsao, G.T.

1980-05-01

382

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

383

Cellulose Synthesis and Its Regulation  

PubMed Central

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

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

2014-01-01

384

Cellulose synthesis and its regulation.  

PubMed

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

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

2014-01-13

385

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

PubMed Central

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

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

2012-01-01

386

Cellulose in cyanobacteria. Origin of vascular plant cellulose synthase?  

PubMed

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 x 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. PMID:11598227

Nobles, D R; Romanovicz, D K; Brown, R M

2001-10-01

387

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

388

Feasibility of e-paper made with cellulose  

NASA Astrophysics Data System (ADS)

Cellulose is a beneficial material that has low cost, light weight, high compatibility, and biodegradability. Recently electro-active paper (EAPap) composed with cellulose was discovered as a smart material for application to variety industrial fields such as smart wall-paper, actuator, and magic carpet. It also exhibited actuator property through ion migration and piezoelectric effect. Since cellulose acetate (CA) film has optically transparent property, we focused on optical field application, such as electronic paper, prismsheet, and polarized film. Since CA can be easily dissolved in variety of organic solvent, various weight % (from 1 to 25 wt. %) of CA solution in acetone was prepared. Polydimethylsilane (PDMS) master pattern was fabricated on the silicone wafer. CA solution was poured to the master mold and dried using spin-coating or tape casting method. Various shape and height patterns, such as circle, honeycomb, and rectangular patterns were fabricated using 12 wt. % CA solution. The resulting pattern showed uniform size in the large area without defect. These patterns can be utilized as a substrate and cell pattern for the electronic paper. To investigate saponification (SA) effect to convert CA to regenerated cellulose, CA film was immersed into the sodium methoxide solution in methanol for various times. The fabricated CA films were stretched and immersed into the sodium methoxide solution in methanol to desubstitute the acetate group. These regenerated cellulose films have larger mechanical strength than CA films. Although the UV-visible transmittance was decreased as increasing SA time, the transmittance of the further SA process and stretched film backed up near untreated CA film. Although the cross-sectional image of the saponified and unstretched CA film did not have specific directional structure, the cross-sectional FESEM image of the saponified and stretched CA film had one directional fiber structure. The fiber was aligned to the stretched direction. Most of the compositions were one directional ordered nanofibers having diameter of approximately 30nm.

Yoo, K. H.; Han, K. J.; Chen, Yi; Kang, K. S.; Kim, Jaehwan

2008-04-01

389

Phase diagram, solubility limit and hydrodynamic properties of cellulose in binary solvents with ionic liquid.  

PubMed

Cellulose solubility phase diagrams in two binary solvents based on 1-ethyl-3-methylimidazolium acetate (EmimAc) mixed with water and with dimethylsulfoxide (DMSO) were built. The minimal amount of EmimAc molecules needed to dissolve cellulose is 2.5-3moles per anhydroglucose unit. This proportion allows calculation of the maximal cellulose concentration soluble in EmimAc-DMSO at any composition; in EmimAc it is around 25-27wt%. Water forms hydrogen bonds with EmimAc and thus competes with cellulose for ionic liquid; the solubility of cellulose in EmimAc-water is much lower than that in EmimAc-DMSO. Hydrodynamic properties of cellulose in two solvent systems were compared. In EmimAc-DMSO cellulose intrinsic viscosity practically does not depend on DMSO content as predicted by the phase diagram. The intrinsic viscosity in EmimAc-water first increases with water content due to cellulose self-aggregation and then abruptly decreases due to coagulation. PMID:24708976

Le, Kim Anh; Rudaz, Cyrielle; Budtova, Tatiana

2014-05-25

390

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

PubMed

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

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

1998-02-20

391

Novel cellulose derivative, process for preparing the same and sulfur dioxide gas permselective membrane comprising the same  

SciTech Connect

This patent relates to a novel cellulose derivative and a sulfur dioxide gas permselective membrane comprising the same, and particularly to hydrocarbylsulfinylethyl cellulose, a process for preparing the same and the sulfur dioxide gas permselective membrane comprising the same. An object of the present invention is to provide hydrocarbylsulfinylethyl cellulose which is a novel cellulose derivative and useful as a material for the sulfur dioxide gas permselective membrane and a process for preparing the same. Another object of the present invention is to supply a novel sulfur dioxide gas permselective membrane having an excellent sulfur dioxide gas permselectivity. The present invention provides hydrocarbylsulfinylethyl cellulose. The novel hydrocarbylsulfinylethyl cellulose of the present invention indicates markedly high sulfur dioxide gas permselectivity compared with the conventional cellulose derivatives, for example, cellulose acetate, ethyl cellulose, etc. Accordingly, the sulfur dioxide gas permselective membrane of the present invention can be utilized for separation, purification of sulfur dioxide gas from a gas mixture such as air or for concentration of sulfur dioxide gas in a gas mixture, and is highly practical in industrial use. More specifically, the sulfur dioxide gas permselective membrane is useful for, for example, removal of harmful sulfur dioxide gas from discharged gases from the viewpoint of environmental protection and purification of starting gases for synthesis, etc. from the viewpoint of industrial production. Further, the hydrocarbylsulfinylethyl cellulose of the present invention is useful for a thickening agent, binder, protective colloidal agent, etc.

Imai, K.; Shiomi, T.; Tezuka, Y.

1987-09-15

392

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

PubMed

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

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

2014-03-01

393

Reinforcement of bacterial cellulose aerogels with biocompatible polymers.  

PubMed

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

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

2014-10-13

394

Enzymatic hydrolysis of bacterial cellulose  

Microsoft Academic Search

Native cellulose from the bacterium Acetobacter xylinum as well as acid-treated bacterial cellulose prepared from partial hydrolysis of the native bacterial cellulose with 2.5 N HCl were subjected to enzymatic hydrolysis by Trichoderma viride cellobiohydrolase I (CBH I) and endoglucanase II (EG II). The activities of the two enzymes were continuously monitored with an oxidation-reduction potential electrode based on the

Masahiro Samejima; Junji Sugiyama; Kiyohiko Igarashi; Karl-Erik L. Eriksson

1997-01-01

395

Acylcarnitines in amniotic fluid: application to the prenatal diagnosis of propionic acidaemia.  

PubMed

Acylcarnitines were assayed in amniotic fluid by isotope dilution tandem mass spectrometry. Control values for propionylcarnitine, C4 and C5 acylcarnitines were established. Propionylcarnitine was elevated by a factor of 5 relative to controls in the amniotic fluid of three pregnancies affected with propionic acidaemia. This may provide a convenient new method for prenatal diagnosis of propionic acidaemia. One pregnancy at risk for propionic acidaemia but unaffected according to methylcitrate analysis had an intermediate level of propionylcarnitine, indicating the need for further studies to determine the range of concentration in probable heterozygotes. PMID:8411998

Van Hove, J L; Chace, D H; Kahler, S G; Millington, D S

1993-01-01

396

Radiation sterilization of hydrocortisone acetate.  

National Technical Information Service (NTIS)

The feasibility of using high energy ionizing radiation for the sterilization of hydrocortisone acetate was investigated. Hydrocortisone acetate in the form of powder was exposed to different dose levels of gamma radiation using a Cobalt-60 source. The ir...

A. Charef A. Boussaha

1989-01-01

397

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

Microsoft Academic Search

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

Hui Li; Zhibin Xie; Yu Zhang; John Wang

2010-01-01

398

Acetate Production by Methanogenic Bacteria  

PubMed Central

Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H2-CO2, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 ?mol of acetate per mmol of CH4 formed, but M. mazei produced only 8 to 9 ?mol of acetate per mmol of CH4.

Westermann, Peter; Ahring, Birgitte K.; Mah, Robert A.

1989-01-01

399

21 CFR 172.870 - Hydroxypropyl cellulose.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 false Hydroxypropyl cellulose. 172.870 Section 172.870 Food...Multipurpose Additives § 172.870 Hydroxypropyl cellulose. The food additive hydroxypropyl cellulose may be safely used in food, except...

2009-04-01

400

21 CFR 172.870 - Hydroxypropyl cellulose.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2009-04-01 true Hydroxypropyl cellulose. 172.870 Section 172.870 Food...Multipurpose Additives § 172.870 Hydroxypropyl cellulose. The food additive hydroxypropyl cellulose may be safely used in food, except...

2010-01-01

401

Conversion of Cellulosic Materials to Sugar.  

National Technical Information Service (NTIS)

A process is claimed for the production of sugar, mainly glucose, by the enzymatic degradation of cellulosic materials, particularly cellulosic wastes, which comprises hydrolyzing the cellulosic material in the presence of cellulase enzyme to produce a su...

C. R. Wilke G. Mitra

1976-01-01

402

Photocatalytic activities of cellulose-based nanofibers with different silver phases: silver ions and nanoparticles.  

PubMed

Cellulose acetate (CA) nanofibers with 5 wt% AgNO3 were fabricated by electrospinning. The Ag ions in as-spun CA nanofibers were photo-reduced to Ag nanoparticles (NPs) using a UV irradiation, and the UV-irradiated CA nanofibers were then transformed to cellulose nanofibers containing Ag NPs by deacetylation reaction. The size and content of Ag NPs in CA fibers was further increased under the deacetylation condition. The catalytic activity of the CA and cellulose nanofibers with different Ag ions/NPs ratios was examined by two model reactions; photodegradation reaction of methylene blue (MB) and chemiluminescent (CL) reaction of luminol. The Ag ions played an important role as a reducing catalyst of MB, whereas the Ag NPs are more effective than Ag ions in the CL reaction. Therefore, the CA and cellulose nanofibrous matrices with Ag ions or NPs have diverse potential applications as catalytic membranes for sensing to specific chemicals. PMID:24507369

Jang, Ki Hyuk; Kang, Yun Ok; Lee, Taek Seung; Park, Won Ho

2014-02-15

403

Comparison of laboratory delignification methods, their selectivity, and impacts on physiochemical characteristics of cellulosic biomass.  

PubMed

Two established delignification methods employing sodium chlorite-acetic acid (SC/AA) and peracetic acid (PAA) are often used, and are reportedly highly selective. However, these reports are mostly for highly recalcitrant and unpretreated softwoods and hardwoods species, and information for less recalcitrant lignocellulosic feedstocks and pretreated biomass is scarce. Furthermore, the effects on cellulose structure are not documented. Thus, in this study, delignification kinetics and selectivity were evaluated when SC/AA and PAA were applied to untreated switchgrass, poplar, corn stover, and pine sawdust; poplar subjected to AFEX, controlled pH, lime, and SO(2) pretreatments; and the cellulose model compounds. Both methods proved effective in removing >90% lignin, but selectivity for lignin and carbohydrates removal was substrate and pretreatment dependent. For untreated biomass, PAA was more selective in removing lignin than SC/AA; however, both methods were less selective for pretreated solids. Cellulose characterizations revealed that PAA had less pronounced impacts on cellulose structure. PMID:23313683

Kumar, Rajeev; Hu, Fan; Hubbell, Christopher A; Ragauskas, Arthur J; Wyman, Charles E

2013-02-01

404

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

2013-04-15

405

Sugar beet cellulose nanofibril-reinforced composites  

Microsoft Academic Search

Cellulose was isolated from sugar beet chips, a by-product of sugar production, by wet chemistry. Further processing of the\\u000a cellulose with a high-pressure homogeniser led to the disruption of cell walls into nanofibrils. Cellulose sheets obtained\\u000a by casting and slow evaporation of water showed higher strength and stiffness when homogenised cellulose was used compared\\u000a to unhomogenised cellulose. These cellulose sheets

Johannes Leitner; Barbara Hinterstoisser; Marnik Wastyn; Jozef Keckes; Wolfgang Gindl

2007-01-01

406

The cellulose contents of Indian seaweeds  

Microsoft Academic Search

Cellulose content as well as alpha (?) and beta (?) celluloses were evaluated in 21 seaweed species belonging to different\\u000a classes growing in Indian waters. The greatest yields of cellulose (crude) and ?-cellulose were obtained from Caulerpa taxifolia (approx. 11.0% and 5.2%, respectively), whilst ?-cellulose (approx. 8.2%) was the greatest in Padina tetrastromatica. The lowest cellulose (crude), ?- and ?-

A. K. Siddhanta; Mahesh U. Chhatbar; Gaurav K. Mehta; Naresh D. Sanandiya; Sanjay Kumar; Mihir D. Oza; Kamalesh Prasad; Ramavatar Meena

407

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

408

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

409

Carbonylation of lower olefins in the presence of complexes of BF 3 with propionic, acetic, or monochloroacetic acids  

Microsoft Academic Search

Conclusions The 3BF3·2CH2C1COOH+BF3-2CH3COOH system effectively catalyzes the selective carbonylation of propylene and n-butylenes. At 95–105°C and a CO pressure of 200 atm, with an equimolar ratio catalyst:olefin: water, propylene or mixed n-butylenes give isobutyric ora-methylbutyric acid in near-quantitative yield.

S. D. Pirozhkov; K. V. Puzitskii; T. N. Myshenkova; K. G. Ryabova

1978-01-01

410

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

411

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

412

Identification of Heme Propionate Vibrational Modes in the Resonance Raman Spectra of Cytochrome c Oxidase  

PubMed Central

The propionate groups of heme a and a3 in cytochrome c oxidase (CcO), have been postulated to mediate both the electron and proton transfer within the enzyme. To establish structural markers for the propionate groups, their associated vibrational modes were identified in the resonance Raman spectra of CcO from bovine (bCcO) and Rhodobacter sphaeroides (RsCcO). The distinction between the modes from the propionates of heme a and heme a3, as well as those from the propionates on the pyrrole rings A and D in each heme, was made on the basis of H2O-D2O isotope substitution experiments, combined with wavelength-selective resonance enhancement (for bCcO) or mutagenesis studies (for RsCcO).

Egawa, Tsuyoshi; Lee, Hyun Ju; Ji, Hong; Gennis, Robert B.; Yeh, Syun-Ru; Rousseau, Denis L.

2012-01-01

413

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.

Chris Somerville

2013-06-17

414

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.

LBNL

2009-09-01

415

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.

Chris Somerville

2010-01-08

416

Development of Cellulosic Biofuels  

SciTech Connect

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.

Chris Somerville

2008-03-12

417

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

418

The role of propionates in substrate binding to heme oxygenase from Neisseria meningitidis; A NMR study†  

PubMed Central

Heme oxygenase, HO, cleaves hemin into biliverdin, iron and CO. For mammalian HOs, both native hemin propionates are required for substrate binding and activity. The HO from the pathogenic bacterium Neisseria meningitidis, NmHO, possesses a crystallographically undetected C-terminal fragment that by solution 1H NMR is found to fold and interact with the active site. One of the substrate propionates has been proposed to form a salt bridge to the C-terminus rather than to the conventional buried cationic side chain in other HOs. Moreover, the C-terminal dipeptide Arg208His209 cleaves spontaneously over ~24 hours at a rate dependent on substituent size. 2D 1H NMR of NmHO azide complexes with hemins with selectively deleted or rearranged propionates all bind to NmHO with a structurally conserved active site as reflected in optical spectra and NMR NOESY cross peak and hyperfine shift patterns. In contrast to mammalian HOs, NmHO requires only a single propionate interacting with the buried terminus of Lys16 to exhibit full activity and tolerates the existence of a propionate at the exposed 8-position. The structure of the C-terminus is qualitatively retained upon deletion of the 7-propionate but a dramatic change in the 7-propionate carboxylate 13C chemical shift upon C-terminal cleavage confirms its role in the interaction with the C-terminus. The stronger hydrophobic contacts between pyrroles A and B with NmHO contribute more substantially to the substrate binding free energy than in mammalian HOs, “liberating” one propionate to stabilize the C-terminus. The functional implications of the C-terminus in product release are discussed.

Peng, Dungeng; Ma, Li-Hua; Smith, Kevin M.; Zhang, Xuhong; Sato, Michihiko; La Mar, Gerd N.

2012-01-01

419

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

420

Use of Sodium Propionate in the Prevention of Ketosis in Dairy Cattle1  

Microsoft Academic Search

SUMMARY In a study involving 100 high-producing cows, one-half served as controls and one- half was fed 0.25 lb. of sodimn propionate daily for a period of 6 wk., starting at calv- ing. Blood analyses and milk production showed an advantage for the propionate-fed cows in terms of higher blood sugar levels, lower blood ketones, and higher milk produc- tion.

L. H. Schultz

1958-01-01

421

Inhibition of the growth of Salmonella typhimurium ST10 by propionic acid and chloride salts  

Microsoft Academic Search

The ability of propionic acid and chloride salts to inhibit Salmonella typhimurium growth was determined. Brain–heart infusion (BHI) was supplemented with 0, 250, 500, or 750 m M of potassium chloride (KCl), sodium chloride (NaCl), or 0, 125, 250, or 375 m M of both KCl and NaCl. Propionic acid was added to the BHI and BHI salts to produce

A. Hinton Jr

1999-01-01

422

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

423

Environmental implications of microbial cellulose  

Microsoft Academic Search

The strong, tough, highly pure cellulose synthesized by microorganisms is just emerging as a new industrial product with exciting new applications in medicine, in foods, and in paper and packaging as well as potential for use in industrial separations. Making a polymer by bioprocessing is inherently much less damaging to the environment than are petrochemical processes, and this cellulose may

Henry R. Bungay; Gonzalo Serafica; Richard Mormino

1997-01-01

424

Permeability of bacterial cellulose membranes  

Microsoft Academic Search

Mass transfer experiments were conducted to determine the transport and interaction parameters of selected molecules in hydrated bacterial cellulose (BC) membranes. The objective was to determine physiochemical characteristics and elucidate the mechanisms governing transport in relation to the membrane structure. Pore and sorption models developed previously for the analysis of transport in hydrogel membranes were relevant to the cellulose membrane

Adam M. Sokolnicki; Robert J. Fisher; Timothy P. Harrah; David L. Kaplan

2006-01-01

425

The Cellulose of Marine Algæ  

Microsoft Academic Search

THE term `algic cellulose' was applied by Stanford1 to an insoluble residue obtained from seaweeds after the removal of algin, and many workers have assumed that this material is identical with the cellulose of land plants. Although denied by some2, this view has been supported by Kylin3 on the evidence of the colour reaction with iodine and sulphuric acid, and

E. G. V. Percival; Alan G. Ross

1948-01-01

426

THERMAL EFFECTS ON CELLULOSIC MATERIALS  

Microsoft Academic Search

Cellulosic materials were exposed to thermal radiation to determine ; minimum thermal-ignition energies for kindling fuels and depth of char in wcod as ; a check on equations developed from laboratory data. Test specimens of alpha-; cellulose paper of various thicknesses, densities, and carbon contents; six ; common kindling fuels (cotton denim, rayon cloth, newspaper, pine needles, dry ; grass,

W. L. Fons; C. P. Butler; H. D. Bruce

1959-01-01

427

Cellulose biogenesis in Dictyostelium discoideum.  

National Technical Information Service (NTIS)

Organisms that synthesize cellulose can be found amongst the bacteria, protistans, fungi, and animals, but it is in plants that the importance of cellulose in function (as the major structural constituent of plant cell walls) and economic use (as wood and...

R. L. Blanton

1993-01-01

428

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

PubMed

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 the two organisms in corn steep liquor/sucrose liquid medium resulted in a threefold higher cellulose yield when compared to the st-60-12 monoculture. A similar enhancement was observed in a coculture with various L. mali strains but not with other Lactobacillus spp. The enhancement of cellulose production was most remarkable when sucrose was supplied as the substrate. L. mali mutants for exocellular polysaccharide (EPS) production were defective in promoting cellulose production, but the addition of EPS to the monoculture of st-60-12 did not affect cellulose productivity. Scanning electron microscopic observation of the coculture revealed frequent association between the st-60-12 and L. mali cells. These results indicate that cell-cell interaction assisted by the EPS-producing L. mali promotes cellulose production in st-60-12. PMID:17093989

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

2006-12-01

429

Biomimetic calcium phosphate crystal mineralization on electrospun cellulose-based scaffolds.  

PubMed

Novel cellulose based-scaffolds were studied for their ability to nucleate bioactive calcium phosphate crystals for future bone healing applications. Cellulose-based scaffolds were produced by electrospinning cellulose acetate (CA) dissolved in a mixture of acetone/dimethylacetamide (DMAc). The resulting nonwoven CA mats containing fibrils with diameters in the range of 200 nm to 1.5 ?m were saponified by NaOH/ethanol for varying times to produce regenerated cellulose scaffolds. Biomimetic crystal growth nucleated from the fiber surface was studied as a function of surface chemistry. Regenerated cellulose scaffolds of varying treatments were soaked in simulated body fluid (SBF) solution. Scaffolds that were treated with CaCl(2), a mixture of carboxymethyl cellulose (CMC) and CaCl(2), and NaOH and CaCl(2), were analyzed using X-ray photoelectron spectroscopy, X-ray powder diffraction, and scanning electron microscopy to understand the growth of bioactive calcium phosphate (Ca-P) crystals as a function of surface treatment. The crystal structure of the nucleated Ca-P crystals had a diffraction pattern similar to that of hydroxyapatite, the mineralized component of bone. The study shows that the scaffold surface chemistry can be manipulated, providing numerous routes to engineer cellulosic substrates for the requirements of scaffolding. PMID:21355545

Rodríguez, Katia; Renneckar, Scott; Gatenholm, Paul

2011-03-01

430

Unusual Presentation of Propionic Acidemia as Isolated Cardiomyopathy  

PubMed Central

Summary Propionic acidemia (PA) is an autosomal recessive disease that results from deficiency of propionyl-CoA carboxylase (PCC). In virtually all reported cases of PA, the phenotype includes metabolic acidosis and/or neurological deficits. We report on a 14-year-old Asian male with PA who presented with isolated cardiomyopathy without any episodes of metabolic acidosis or evidence of any neurocognitive deficits. On routine metabolic screening, the patient was found to have urine organic acids suggestive of PA. Biochemical and genetic characterization confirmed a PCC deficiency with two novel mutations in PCCB: IVS7+2 T>G (c.763+2 T>G) and p.R410Q (c.1229 G>A). Residual enzyme activity likely explains our patient’s mild phenotype. Splicing mutations tend to result in a milder phenotype as these mutations may still produce small amounts of normal enzyme. In addition, the similar p.R410W mutation has been shown to have partial residual activity. Moreover, this case illustrates the important but under-recognized manifestation of isolated cardiomyopathy as the sole clinical presentation in PA. A thorough metabolic evaluation should be performed in all pediatric patients with cardiomyopathy. Such an evaluation has important implications for clinical management and genetic counseling.

Lee, T. M.; Addonizio, L. J.; Barshop, B. A.; Chung, W. K.

2013-01-01

431

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

432

Cellulose nanocrystals/cellulose core-in-shell nanocomposite assemblies.  

PubMed

We report herein for the first time how a co-electrospinning technique can be used to overcome the issue of orienting cellulose nanocrystals within a neat cellulose matrix. A home-built co-electrospinning apparatus was fabricated that was comprised of a high-voltage power supply, two concentric capillary needles, and one screw-type pump syringe. Eucalyptus-derived cellulose was dissolved in N-methylmorpholine oxide (NMMO) at 120 degrees C and diluted with dimethyl sulfoxide (DMSO) which was used in the external concentric capillary needle as the shell solution. A cellulose nanocrystal suspension obtained by the sulfuric acid hydrolysis of bleached sisal and cotton fibers was used as the core liquid in the internal concentric capillary needle. Three flow rate ratios between the shell and core, four flow rates for the shell dope solution, and four high voltages were tested. The resultant co-electrospun composite fibers were collected onto a grounded metal screen immersed in cold water. Micrometer and submicrometer cellulose fiber assemblies were obtained which were reinforced with cellulose nanocrystals and characterized by FESEM, FTIR, TGA, and XRD. Surprisingly, it was determined that the physical properties for the cellulose controls are superior to the composites; in addition, the crystallinity of the controls was slightly greater. PMID:19731951

Magalhães, Washington Luiz Esteves; Cao, Xiaodong; Lucia, Lucian A

2009-11-17

433

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

PubMed

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

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

2014-06-01

434

Investigation on isobaric vapor liquid equilibrium for acetic acid + water + ( n-propyl acetate or iso-butyl acetate)  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+n-propyl acetate, acetic acid+iso-butyl acetate, acetic acid+water+n-propyl acetate, acetic acid+water+iso-butyl acetate are measured at 101.33kPa with a modified Rose still. The nonideal behavior in vapor phase caused by the association of acetic acid are corrected by the chemical theory and Hayden–O’Connell method, and analyzed by calculating the second virial coefficients and

Chundong Zhang; Hui Wan; Lijun Xue; Guofeng Guan

2011-01-01

435

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

436

The Young's modulus of a microcrystalline cellulose  

Microsoft Academic Search

This research is concerned with an investigation into the determination of the micromechanical properties of particulate form of cellulose; namel microcr stalline cellulose. Using the technique of Raman spectroscop the shift in the 1095cm-1 Raman band, characteristic of cellulose, with strain is monitored and compared to the deformation of natural cellulose fibres (flax and hemp). From the values of the

S. J. Eichhorn; R. J. Young

2001-01-01

437

Magnetic field effect for cellulose nanofiber alignment  

Microsoft Academic Search

Regenerated cellulose formed into cellulose nanofibers under strong magnetic field and aligned perpendicularly to the magnetic field. Well-aligned microfibrils were found as the exposure time of the magnetic field increased. Better alignment and more crystalline structure of the cellulose resulted in the increased decomposition temperature of the material. X-ray crystallograms showed that crystallinity index of the cellulose increased as the

Jaehwan Kim; Yi Chen; Kwang-Sun Kang; Young-Bin Park; Mark Schwartz

2008-01-01

438

Effects of aqueous sulfur dioxide on cellulose  

Microsoft Academic Search

The reaction of aqueous sulfur dioxide with cellulose pulp and cotton linters was investigated to determine the effect of this lignocellulosic pretreatment method on the cellulosic portion. Sulfur dioxide treatment dramatically reduced the DP of the cellulose but did not affect its enzymatic digestibility, and did not decrystallize the cellulose as recently reported by Leeet al. (1979).

Anthony H. Conner

1980-01-01

439

Development of an industrializable fermentation process for propionic acid production.  

PubMed

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

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

2014-05-01

440

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

441

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

442

Cellulose conversion under heterogeneous catalysis.  

PubMed

In view of current problems such as global warming, high oil prices, food crisis, stricter environmental laws, and other geopolitical scenarios surrounding the use of fossil feedstocks and edible resources, the efficient conversion of cellulose, a non-food biomass, into energy, fuels, and chemicals has received much attention. The application of heterogeneous catalysis could allow researchers to develop environmentally benign processes that lead to selective formation of value-added products from cellulose under relatively mild conditions. This Minireview gives insight into the importance of biomass utilization, the current status of cellulose conversion, and further transformation of the primary products obtained. PMID:19021143

Dhepe, Paresh L; Fukuoka, Atsushi

2008-01-01

443

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 sorption agents can be incorporated during the manufacture of the structure. 3 figs.

Walsh, M.A.; Morris, R.S.

1986-09-16

444

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

445

Reinforcing effect of carboxymethylated nanofibrillated cellulose powder on hydroxypropyl cellulose  

Microsoft Academic Search

Bionanocomposites of hydroxypropyl cellulose (HPC) and nanofibrillated cellulose (NFC) were prepared by solution casting.\\u000a The various NFC were in form of powders and were prepared from refined, bleached beech pulp (RBP) by mechanical disintegration,\\u000a optionally combined with a pre- or post mechanical carboxymethylation. Dynamic mechanical analysis (DMA) and tensile tests\\u000a were performed to compare the reinforcing effects of the NFC

Ch. Eyholzer; F. Lopez-Suevos; P. Tingaut; T. Zimmermann; K. Oksman

2010-01-01

446

[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

447

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

2011-04-01

448

Thermogravimetric analysis of the relationship among calcium magnesium acetate, calcium acetate and magnesium acetate  

Microsoft Academic Search

Thermal decomposition characteristic of calcium magnesium acetate (CMA), calcium acetate (CA) and magnesium acetate (MA) are investigated through thermogravimetric (TG) analysis at the heating rates of 5Kmin?1, 7.5Kmin?1, 10Kmin?1 and 15Kmin?1. After dehydration, the evaporation of carboxylic radical and carbon dioxide of CMA and CA exist in two separate segments, but for MA, this occurs together in just one segment

Shengli Niu; Kuihua Han; Chunmei Lu; Rongyue Sun

2010-01-01

449

Facile pulping of lignocellulosic biomass using choline acetate.  

PubMed

Treating ground bagasse or Southern yellow pine in the biodegradable ionic liquid (IL), choline