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1

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

2

Propionate stimulates pyruvate oxidation in the presence of acetate.  

PubMed

Flux through pyruvate dehydrogenase (PDH) in the heart may be reduced by various forms of injury to the myocardium, or by oxidation of alternative substrates in normal heart tissue. It is important to distinguish these two mechanisms because imaging of flux through PDH based on the appearance of hyperpolarized (HP) [(13)C]bicarbonate derived from HP [1-(13)C]pyruvate has been proposed as a method for identifying viable myocardium. The efficacy of propionate for increasing PDH flux in the setting of PDH inhibition by an alternative substrate was studied using isotopomer analysis paired with exams using HP [1-(13)C]pyruvate. Hearts from C57/bl6 mice were supplied with acetate (2 mM) and glucose (8.25 mM). (13)C NMR spectra were acquired in a cryogenically cooled probe at 14.1 Tesla. After addition of hyperpolarized [1-(13)C]pyruvate, (13)C NMR signals from lactate, alanine, malate, and aspartate were easily detected, in addition to small signals from bicarbonate and CO2. The addition of propionate (2 mM) increased appearance of HP [(13)C]bicarbonate >30-fold without change in O2 consumption. Isotopomer analysis of extracts from the freeze-clamped hearts indicated that acetate was the preferred substrate for energy production, glucose contribution to energy production was minimal, and anaplerosis was stimulated in the presence of propionate. Under conditions where production of acetyl-CoA is dominated by the availability of an alternative substrate, acetate, propionate markedly stimulated PDH flux as detected by the appearance of hyperpolarized [(13)C]bicarbonate from metabolism of hyperpolarized [1-(13)C]pyruvate. PMID:25320331

Purmal, Colin; Kucejova, Blanka; Sherry, A Dean; Burgess, Shawn C; Malloy, Craig R; Merritt, Matthew E

2014-10-15

3

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

4

Reversible acetylation regulates acetate and propionate metabolism in Mycobacterium smegmatis  

PubMed Central

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

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

2013-01-01

5

Drying Cellulose Acetate Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

The membranes currently used in reverse osmosis for desalination are made of cellulose acetate. Modified membranes, because they contain a large number of pores, contain large quantities of water, 60 to 70 wt. %. If this water is allowed to evaporate unde...

K. D. Vos, F. O. Burris

1967-01-01

6

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

7

Thermochemical characteristics of cellulose acetates with different degrees of acetylation  

NASA Astrophysics Data System (ADS)

The standard enthalpies of combustion and formation of cellulose acetates with different degrees of acetylation are determined. It is established that there is a proportional dependence of these thermochemical characteristics vs. the degree of acetylation, weight fraction of bonded acetic acid, and molar mass of the repeating unit of cellulose acetates.

Larina, V. N.; Ur'yash, V. F.; Kushch, D. S.

2012-12-01

8

The efficiency of enhanced biological phosphorus removal from real wastewater affected by different ratios of acetic to propionic acid  

Microsoft Academic Search

The effect of different ratios of propionic to acetic acid on the efficiency of enhanced biological phosphorus removal (EBPR) from real wastewater supplemented with volatile fatty acids (VFAs) was investigated. Two sequencing batch reactors (SBRs) were used to acclimate two types (SBR1 and SBR2) of biomass. They were cultured and studied using real wastewater with an average propionic to acetic

Yinguang Chen; Andrew A. Randall; Terrence McCue

2004-01-01

9

Cellulose production by acetic acid-resistant Acetobacter xylinum  

Microsoft Academic Search

A bacterium that could produce a gelatinous cellulosic pellicle in the presence of more than 2% acetic acid was isolated as a contaminant in a continuous surface culture for acetic acid production using Acetobacter aceti. The bacterium was identified as a strain belonging to Acetobacter xylinum and designated as strain DA. The production of cellulose in a static culture of

Kiyoshi Toda; Tomoko Asakura; Masahiro Fukaya; Etsuzo Entani; Yoshiya Kawamura

1997-01-01

10

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. PMID:14617380

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

2003-01-01

11

Dynamical characterization of a cellulose acetate polysaccharide.  

PubMed

This work brings together dynamical and structural information at a molecular level for cellulose acetate being an original contribution to the general description of polysaccharide properties. In particular, it allowed reinterpreting the secondary relaxation mechanisms that are still controversial in the literature; a compilation of data provided by different authors is provided. Detailed dynamical information is provided by dielectric relaxation spectroscopy (DRS) (10(-1)-10(6) Hz) for cellulose acetate (CA) in the sub-T(g) region below ambient temperature; results were compared with cellulose acetate structured as an asymmetric membrane (CAmb). In samples with low water content, two secondary relaxation processes between 173 and 298 K were identified by DRS, associated with localized mobility. The process located at the lowest temperatures (process I) has a different mobility in CA relative to CAmb. The identical crystalline/amorphous state of both materials allowed rationalizing the distinct behavior in terms of polymeric arrangement and ability for water uptake. The looser structure of the CA relative to CAmb as confirmed by FTIR, TGA, and DSC analysis makes more sites accessible to water molecules, resulting in a higher water retention in CA (2.73% w/w) relative to CAmb (1.60% w/w) and an increased molecular mobility in the former due to a plasticizing effect. In both materials, process I is significantly influenced by hydration, shifting to higher frequencies and lower temperatures upon water uptake. This process seems to be associated with mobility occurring within the monomeric unit, which embraces the two anhydroglucose rings connected by the glycosidic linkage and the polar groups directly attached to it. It should involve a very limited length scale, as suggested by its location, far below the glass transition, and the tau(infinity) value with a low entropic effect. The relaxation process that emerges later, process II, is similar for both samples being much less influenced by water but experiencing a slight antiplasticizing effect shifting to lower frequencies and higher temperatures upon hydration. It should involve side group motions, strongly coupled to the mobility of the anhydroglucose rings, which become hindered probably due to establishment of H-bonds with water molecules. The plasticizing/antiplasticizing effect is being discussed only on the basis of the frequency position of the relaxation peak. Processes I and II merge into a broad relaxation (gamma(dry)) upon water removal in both CA and CAmb, however evolving slower in the former with drying, due to a more disordered structure of CA that allows water to interact with more internal sites in the polymer. At higher temperatures (T > or = 353 K), a process emerges in the high frequency side of the dynamic alpha-relaxation which is compatible with a beta(JG)-relaxation. The structured specimen CAmb provided an additional way to probe the morphological changes undergone by the material when annealed to temperatures higher than 353 K, originating an increase in the dielectric response. This effect can be associated with a skin densification and partial collapse of the membrane porous network, as observed by SEM. PMID:20690651

Sousa, Miriam; Brás, Ana Rita; Veiga, Helena Isabel M; Ferreira, Frederico Castelo; de Pinho, Maria Norberta; Correia, Natália T; Dionísio, Madalena

2010-09-01

12

Broiler chick responses to anorectic agents: dietary acetic and propionic acids and the blood metabolites.  

PubMed

The effects of dietary supplementation with acetic or propionic acid, given at a level of 3% of diets containing 2,500 or 2,750 kcal of metabolizable energy per kg, on levels of blood glucose, and on lipid, protein, and energy metabolisms were studied in female broiler chicks. Voluntary feed and energy intakes, as well as body weight gain, decreased significantly with the inclusion of the acids in either diet, in decreasing order of effect: propionate > acetate > nonsupplemented controls. The relative weight of the abdominal adipose tissue decreased significantly with the inclusion of either acid, but was unaffected by dietary energy level. In contrast, the weight of the liver was higher in birds fed the low-energy diet, but was unaffected by the anorectic agents. Inclusion of the acids increased the concentration of volatile fatty acids in the cecum and blood plasma. The rate of clearance of plasma propionate was greater than that of acetate. Anorectic agents and dietary energy density exhibited a synergistic effect on feed intake. These agents altered blood metabolites involved in lipid and energy metabolisms, but not in that of protein. Plasma metabolites and enzymes, particularly beta-hydroxybutyrate and alkaline phosphatase, reflected the degree of feed restriction, supporting the hypothesis that the hypophagic effect of these acids is due to metabolic intervention. PMID:7625770

Pinchasov, Y; Elmaliah, S

1995-01-01

13

Permeability of cellulose acetate membranes to selected solutes  

Microsoft Academic Search

The permeability of cellulose 2.5-acetate films to several electrolytes and nonelectrolytes was measured. Permeabilities were determined by a desorption-rate method in which diffusion and distribution coefficients were measured. The rejection of the same solutes by modified cellulose acetate membranes in reverse osmosis experiments was also measured. A comparison was made between intrinsic water and solute permeabilities and the reverse osmosis

H. K. Lonsdale; B. P. Cross; F. M. Graber; C. E. Milstead

1971-01-01

14

BIOCA - Biomass Streams to Produce Cellulose Acetate  

Microsoft Academic Search

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

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

15

Cellulose 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

16

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

SciTech Connect

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

Emmanuel, B.; Kennelly, J.J.

1985-03-01

17

7—STUDIES ON THE SORPTION OF MOISTURE BY POLYMERS PART III—CELLULOSE ACETATE AND CELLULOSE TRIACETATE FIBRES  

Microsoft Academic Search

The adsorption isotherms of water vapour on a wide range of commercial secondary cellulose acetate and cellulose triacetate fibres have been measured at 22°C. Conversion of cellulose acetate flake into fibres causes a drop in sorption, but otherwise the sorption is almost unaffected by the filament denier, conversion into staple fibres, solution-dyeing, or delustrant. Stretchspinning, as in the production of

D. K. Beever; L. Valentine

1958-01-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

19

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

PubMed

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

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

2014-11-01

20

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

21

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. PMID:5410490

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

1970-01-01

22

Nanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations  

E-print Network

. The exfoliated SAMH-3 flakes were used to form SAMH-3/cellulose acetate (CA) membranes. Their micro- structureNanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations Wun are of interest because they can exploit the high aspect ratio of exfoliated selective flakes/layers to enhance

Nair, Sankar

23

Improved Fixation of Cellulose-Acetate Reverse-Osmosis Membrane for Scanning Electron Microscopy  

PubMed Central

Fixation of cellulose-acetate membranes with either glutaraldehyde-osmium tetroxide or glutaraldehyde-ruthenium tetroxide resulted in extensive electron beam damage. Beam damage was eliminated and the bacterial surface structure was preserved, however, when cellulose-acetate membranes were fixed with glutaraldehyderuthenium tetroxide and treated successively with thiocarbohydrazide and osmium tetroxide. Images PMID:16346735

Kutz, S. M.; Bentley, D. L.; Sinclair, N. A.

1985-01-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

25

Influence of cellulose on ion diffusivity in 1-ethyl-3-methyl-imidazolium acetate cellulose solutions.  

PubMed

Solutions of microcrystalline cellulose in 1-ethyl-3-methyl-imidazolium acetate have been investigated using pulsed-field gradient (1)H NMR. In all cases the geometrically larger cation was found to diffuse faster than the smaller anion. Arrhenius temperature analysis has been applied to the ion diffusivities giving activation energies. The diffusion and published viscosity data for these solutions were shown to follow the Stokes-Einstein relationship, giving hydrodynamic radii of 1.6 Å (cation) and 1.8 Å (anion). Theories for obstruction, free-volume and hydrodynamic effects on solvent diffusion have been applied. The Mackie-Meares and Maxwell-Fricke obstruction models provided a correct trend only when assuming a certain fraction of ions are bound to the polymer. From this fraction it was shown that the maximum dissolvable cellulose concentration is ?27% w/w, which is consistent with the highest known prepared concentration of cellulose in this ionic liquid. The Phillies' hydrodynamic model is found to give the best description for the cellulose concentration dependence of the ion diffusivities. PMID:20923202

Lovell, Christopher S; Walker, Adam; Damion, Robin A; Radhi, Asanah; Tanner, Steven F; Budtova, Tatiana; Ries, Michael E

2010-11-01

26

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

PubMed

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

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

2014-10-13

27

Preparation and characterization of novel oxidized cellulose acetate methyl esters.  

PubMed

In this paper, we report the preparation of oxidized cellulose acetate methyl esters (OCAM) from OCA (OC14A: carboxylic acid content 10.6% (w/w), degree of acetyl group substitution: 1.89; OC21A: carboxylic acid content 15.7% (w/w), degree of acetyl group substitution: 1.70) by treatment with methanol at room temperature using 4-dimethylaminopyridine (DMAP) as a catalyst and dicyclohexylcarbodiimide (DCC) as a coupling agent. The new polymers were characterized by Fourier-transform infrared (FT-IR) and (1)H and (13)C nuclear magnetic resonance spectroscopies, carboxylic acid content determination, moisture sorption isotherms, intrinsic viscosity, and powder X-ray diffractometry. The new polymers are amorphous powders. It is practically insoluble in water but show solubility in a range of organic solvents. PMID:22944406

Yang, D; Kumar, V

2012-11-01

28

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

PubMed

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

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

2013-01-01

29

Transport properties of polyaniline-cellulose-acetate blends  

NASA Astrophysics Data System (ADS)

Transport properties of polyaniline (PANI)-cellulose acetate (CA) conducting blends have been investigated at various length scales and temperatures. We report on the results of dc and ac conductivity measurements, magnetoresistance and electron-spin resonance (ESR) performed on composite films with PANI weight fraction p ranging from the percolation threshold-pc~=0.1%-to a few percent. Three different PANI doping agents have been tested, namely, camphor sulfonic acid (CSA), di(i-octyl phosphate) (DiOP) and phenyl phosphonic acid (PPA). The percolative behavior of ?dc resembles that of published results on PANI/PMMA blends. The onset frequency ?? of the dispersion in ?ac appears to follow the scaling law: ??~?zdc with z~=1. The temperature dependence is of the form of ln?(T)~-(T0/T)? the exponent decreasing from 0.75 to 0.5 with increasing p. The microscopic metallic character of transport is found in ESR and microwave measurements. Spin-dependent conductivity is inferred from the (B/T)2 universal behavior of magnetoresistance. Those results are discussed in conjunction with the ongoing debate on the nature of disorder in conducting polymers-homogeneous versus heterogeneous.

Planès, Jérôme; Wolter, Andreas; Cheguettine, Yasmina; Pro?, Adam; Genoud, Françoise; Nechtschein, Maxime

1998-09-01

30

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

31

Methanogenesis from acetate and propionate by thermophilic down-flow anaerobic packed-bed reactor  

Microsoft Academic Search

The maximum propionate removal rate was 13.7g\\/L-reactor\\/day at the organic loading rate of 66.4kg-CODcr\\/m3-reactor\\/day (HRT, 4.75h); however, the removal efficiency was very low. Clone library analysis and quantification by real-time PCR using 16S rRNA gene revealed that the population of methanogenic archaea in the biofilm fraction that developed on the packed bed was higher than that in the liquid fraction.

Masahiro Tatara; Takashi Makiuchi; Yoshiyuki Ueno; Masafumi Goto; Koji Sode

2008-01-01

32

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

PubMed

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

Zhang, Chao; Chen, Yin-Guang

2013-03-01

33

Transport of solutes through calix[4]pyrrole-containing cellulose acetate films  

Microsoft Academic Search

Films of cellulose acetate containing different concentrations of meso-octamethyl-porphyrinogen (calix[4]pyrrole) were prepared and characterized using UV–vis and FTIR spectroscopy, DSC and SEM. Incorporation of calix[4]pyrrole into cellulose acetate leads to a decrease in the degree of hydrophilicity of the polymeric matrix. However, a slight increase in the percentage of water uptake of the polymer is found with an increase of

A. J. M. Valente; A. Jiménez; A. C. Simões; H. D. Burrows; A. Ya. Polishchuk; V. M. M. Lobo

2007-01-01

34

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

35

Cellulose acetate butyrate/poly(caprolactonetriol) blends: Miscibility, mechanical properties, and in vivo inflammatory response.  

PubMed

This study reports the results of the characterization of cellulose acetate butyrate and polycaprolactone-triol blends in terms of miscibility, swelling capacity, mechanical properties, and inflammatory response in vivo. The cellulose acetate butyrate film was opaque and rigid, with glass transition (T g ) at 134? and melting temperature of 156?. The cellulose acetate butyrate/polycaprolactone-triol films were transparent up to a polycaprolactone-triol content of 60%. T g of the cellulose acetate butyrate films decreased monotonically as polycaprolactone-triol was added to the blend, thus indicating miscibility. FTIR spectroscopy revealed a decrease in intramolecular hydrogen bonding in polycaprolactone-triol, whereas no hydrogen bonding was observed between cellulose acetate butyrate and -OH from polycaprolactone-triol. The increase in polycaprolactone-triol content in the blend decreased the water uptake. An increase in polycaprolactone-triol content decreased the modulus of elasticity and increased the elongation at break. A cellulose acetate butyrate/polycaprolactone-triol 70/30 blend implanted in rats showed only an acute inflammatory response 7 days after surgery. No change in inflammation mediators was observed. PMID:25015652

Kanis, Luiz A; Marques, Ellen L; Zepon, Karine M; Pereira, Jefferson R; Pamato, Saulo; de Oliveira, Marcelo T; Danielski, Lucinéia G; Petronilho, Fabricia C

2014-11-01

36

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

37

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

38

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

PubMed

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

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

2014-01-01

39

Atomic Layer Deposition of Titania on Cellulose Acetate for Enhanced Hemostasis  

PubMed Central

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

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

2012-01-01

40

Acidic ionic liquid as "quasi-homogeneous" catalyst for controllable synthesis of cellulose acetate.  

PubMed

In this paper, we demonstrated that acidic ionic liquids (ILs) can be used as "quasi-homogeneous" catalysts for the efficient acetylation of cellulose. Unlike existing techniques that use large amount of ILs as solvent to dissolve and acetylate cellulose, a small amount of acidic ILs was used as catalyst in this study to overcome the low efficiency associated with relatively high viscosity and costs of ILs during homogeneous acetylation. Fully substituted cellulose acetate with a conversion of 88.8% was obtained by using only 9mol% IL 1-vinyl-3-(3-sulfopropyl) imidazolium hydrogen sulfate as catalyst, which is much higher than that of common commercialized solid acid catalysts. The degree of substitution and solubility of the obtained cellulose acetate can be facilely controlled by varying the concentration of ILs and reaction time. The dual function of swelling and catalyzing of acidic ILs for the acetylation of cellulose is responsible for the excellent catalytic performance. PMID:25256462

Tian, Dong; Han, Yangyang; Lu, Canhui; Zhang, Xinxing; Yuan, Guiping

2014-11-26

41

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

42

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

43

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

Microsoft Academic Search

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

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

2005-01-01

44

Effects of Short or Long-Term Infusions of Acetate or Propionate on Luteinizing Hormone, Insulin, and Metabolite Concentrations in Beef Heifers1,2  

Microsoft Academic Search

Two trials were conducted to evaluate the effects of short- (Trial 1) or long-term (Trial 2) in- traruminal isocaloric infusions of acetate or propionate on secretion of LH, insulin, and selected metabolites in short- or long-term energy-restricted beef heifers. In Trial 1, 16 Angus heifers were assigned on d 6 to 12 of a synchronized estrous cycle (estrus = d

A. DiCostanzo; J. E. Williams; D. H. Keisler

2010-01-01

45

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

46

Association for Biology Laboratory Education (ABLE) ~ http://www.zoo.utoronto.ca/able Demystifying Hardy-Weinberg: Using Cellulose Acetate  

E-print Network

Demystifying Hardy-Weinberg: Using Cellulose Acetate Electrophoresis of the Lap Locus to Study Population From: Peroni, P. A. and D. E. McCauley. 1999. Demystifying Hardy-Weinberg: Using cellulose acetate................................................................114 Appendix B: Calculation of Allele and Genotype Frequencies and Hardy-Weinberg Review

47

The voluntary intake of hay and silage by lactating cows in response to ruminal infusion of acetate or propionate, or both, with or without distension of the rumen by a balloon.  

PubMed

In order to test the hypothesis that negative feedback signals from abdominal receptors are integrated in an additive manner in the control of voluntary food intake, cows with rumen fistulas were given intraruminal infusions of sodium acetate or sodium propionate, or both, with or without distension of the rumen by balloon. Intakes were monitored during the 3 h experimental period and for 2 h after and samples of rumen fluid were taken for estimation of short-chain fatty acid concentrations and osmolality. Six cows in mid-lactation were fed on hay and concentrates and given, into the rumen, 5.5 mol sodium acetate, 5.2 mol sodium propionate and 7.5 l of distension. Compared with the control (water infusion), neither acetate, propionate nor distension significantly depressed hay intake when given separately. When given in combination, however, the following significantly depressed intake during the 3 h treatment period: propionate + distension, acetate + distension, acetate + propionate + distension. Seven cows in early lactation were fed on silage and concentrates and given, into the rumen, 9.0 mol sodium acetate, 4.0 mol sodium propionate and 10.0 litres of distension. Again, none of the three given alone depressed silage intake to a significant extent during the 3 h treatment period, whereas the following combinations had a significant effect: propionate + distension, acetate + distension, acetate + propionate + distension. Basal rumen osmolalities were similar for the two types of feed but infusion of the sodium salts caused a very much greater increase with silage than with hay.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8329347

Mbanya, J N; Anil, M H; Forbes, J M

1993-05-01

48

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

Microsoft Academic Search

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

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

2012-01-01

49

Selective hydrogenation of cyclopentadiene in a catalytic cellulose acetate hollow-fiber reactor  

Microsoft Academic Search

A catalytic membrane reactor was established with catalytic hollow fibers prepared by supporting polymer anchored palladium catalysts on the inside wall of cellulose acetate hollow fibers. The selective hydrogenation of cyclopentadiene was carried out in the catalytic membrane reactor at 40°C in two ways: (1) by hydrogen permeating into the hollow fibers, and (2) by hydrogen premixed in the gas

Hanrong Gao; Shijian Liao; Yun Xu; Ren Liu; Jing Liu; Decai Li

1994-01-01

50

Nanoprecipitation of cellulose acetate using solvent\\/nonsolvent mixtures as dispersive media  

Microsoft Academic Search

An efficient nanoprecipitation technique using good cellulose acetate (CA) solvents as modifier for the dispersive media (nonsolvent) was developed for the generation of CA nanoparticles. Addition of tetrahydrofuran (THF) to the nonsolvent leads to smaller particles than obtained with pure water or standard stabilizing agents like surfactants and block copolymers. Sonication, efficient agitation, and optimization of process parameters like temperature,

Martin R. Kulterer; Martin Reischl; Victoria E. Reichel; Silvo Hribernik; Ming Wu; Stefan Köstler; Rupert Kargl; Volker Ribitsch

2011-01-01

51

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

52

Properties of cellulose acetate nanofiltration membranes. Application to brackish water desalination  

Microsoft Academic Search

In this work, we report about cellulose acetate nanofiltration (NF) membrane preparation according to the phase inversion process. Pore size was monitored by using dope solutions of two polymer concentrations (20 and 22 wt?%) and annealing temperatures from 60–80°C. Membrane characterization included a morphologic analysis using scanning electron microscopy (SEM) and hydraulic permeability (Lp0) determined from pure water filtration. SEM

Randa Haddada; Ezzedine Ferjani; Mohamed Sadok Roudesli; André Deratani

2004-01-01

53

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

PubMed

Bacterial contamination of raw, processed poultry may include spoilage bacteria and foodborne pathogens. We evaluated different combinations of organic acid (OA) wash solutions for their ability to reduce bacterial contamination of raw chicken skin and to inhibit growth of spoilage bacteria and pathogens on skin during refrigerated storage. In experiment 1, raw chicken skin samples were dipped into a suspension of either 10(8) cfu/mL of Salmonella Typhimurium, Escherichia coli O157:H7, or Listeria monocytogenes for 30 s and then immersed in PBS or an OA wash solution mixture of 0.8% citric, 0.8% acetic, and 0.8% propionic acid (at equal wt/vol concentrations) for an additional 30 s. In experiment 2, three different concentrations of the OA wash solution (0.2, 0.4, and 0.6% at equal wt/vol concentrations) were tested against chicken skin samples contaminated with Salmonella Typhimurium. Viable pathogenic bacteria on each skin sample were enumerated after 1 and 24 h of storage at 4°C in both experiments. In experiment 3, skin samples were initially treated on d 1 with PBS or 2 concentrations of the OA mixture (0.4 and 0.8%), and total aerobic bacteria were enumerated during a 2-wk storage period. In all experiments, significant (P < 0.05) differences were observed when skin samples were treated with the OA wash solution and no spoilage organisms were recovered at any given time point, whereas increasing log10 numbers of spoilage organisms were recovered over time in PBS-treated skin samples. These results suggest that 0.2 to 0.8% concentrations of an equal-percentage mixture of this OA combination may reduce pathogens and spoilage organisms and improve food safety properties of raw poultry. PMID:23873572

Menconi, A; Shivaramaiah, S; Huff, G R; Prado, O; Morales, J E; Pumford, N R; Morgan, M; Wolfenden, A; Bielke, L R; Hargis, B M; Tellez, G

2013-08-01

54

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

PubMed

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

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

2014-01-01

55

Rates of Production of Acetate, Propionate, and Butyrate in the Rumen of Lactating Dairy Cows Given Normal and Low-Roughage Diets  

Microsoft Academic Search

Five lactating dairy cows with a permanent cannula in the rumen were given (kg DM\\/d) a normal diet (7.8 concentrates, 5.1 hay) or a low-roughage (LR) diet (11.5concentrates,1.2hay)intwomealsdailyinatwo- period crossover design. Milk fat (g\\/kg) was severely reduced on diet LR. To measure rates of production of individual volatile fatty acids (VFA) in the rumen, 0.5 mCi 1-14C-acetic acid, 2-14C-propionic acid,

J. D. Sutton; M. S. Dhanoa; S. V. Morant; D. J. Napper; E. Schuller

2003-01-01

56

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

PubMed

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

Bindschaedler, C; Gurny, R; Doelker, E

1987-06-01

57

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

NSDL National Science Digital Library

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

2002-01-01

58

Laboratory-Scale Composting Test Methods to Determine Polymer Biodegradability: Model Studies on Cellulose Acetate  

Microsoft Academic Search

Studies have been conducted to determine the time dependence of film normalized weight loss using in-laboratory simulations of a compost environment. The composting bioreactors contained a fresh synthetic waste mixture formulation which was maintained at 53°C and 60% moisture. An important result from these studies is that cellulose acetate (CA) films (approximate film thickness of between 0.025 and 0.051 mm)

Richard A. Gross; Ji-dong Gu; David Eberiel; Stephen P. McCarthy

1995-01-01

59

INTERFEROMETRIC EVALUATION OF ASSOCIATION EQUILIBRIUM IN THE CELLULOSE ACETATE\\/ACETONE\\/WATER TERNARY SYSTEM  

Microsoft Academic Search

The paper studies the conformational modifications of cellulose acetate with a 2.21 substitution degree, in 85\\/15, 90\\/10 and 95\\/5 v\\/v acetone\\/water solvent mixtures. The behavior is influenced by the preferential adsorption of acetone, which was evaluated from interferometer data. The miscibility of the ternary system is attained by competitive specific interactions between the solvent-solvent and solvent-polymer systems, which determine the

Adina Maria NECULA; Liliana OLARU; Niculae OLARU; Silvia IOAN

60

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

61

ac and dc percolative conductivity of magnetite-cellulose acetate composites  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

62

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

63

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

PubMed

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

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

2014-12-19

64

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. PMID:16345789

Mackie, Roderick I.; Bryant, Marvin P.

1981-01-01

65

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. PMID:21179372

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

2010-01-01

66

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

NASA Astrophysics Data System (ADS)

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 readily biodegraded by many microorganisms due to the activity of cellulase enzymes. However, the biodegradability of cellulose acetate (CA) is less than certain. To determine a semi-quantitative measure of the biodegradation of CA fibers, the AATCC test method 30-1988 was selected. After a 12-week soil burial test, evidence of microbial attack on CA fabric was obtained on the basis of 27% strength loss. As a more reliable method, the ASTM test method D5209-91, an aerobic sludge test, was adopted, in which the amount of COsb2 evolved from the decomposition of CA, cotton and fiber blends was measured. The biodegradability of CA fibers was confirmed by showing COsb2 evolution, and the synergistic effects of multi-enzyme systems between cellulase and esterase were suggested based on the increased biodegradation rates in fiber blends. Opening, blending, carding, and thermal calendering processes were used in the fabrication of the nonwovens. Pretreatment with solvent vapors was introduced for modifying the softening temperatures of the cellulose acetate and for lowering the calendering temperatures required otherwise. The success of the solvent-assisted thermal calendering is demonstrated in enhanced tensile strengths of the nonwoven obtained with lower calendering temperatures. For process optimization, the experiment was designed for a 3-way factorial design with the following factors: bonding temperature, blend ratio and solvent treatment time. The effects of the factors on 18 physical properties were determined by analysis of variance, least-square-means comparison, regression and correlation techniques. The results indicated that the physical properties were significantly influenced by the factors. For optimization, four responses were selected for stronger, softer, more extensible and more breathable nonwovens. The optimal processing conditions in a given blend ratio were suggested by a response surface technique based on multivariate-multiresponse analysis, and distance and desirability functions.

Suh, Hageun

67

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

68

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

69

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

Microsoft Academic Search

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

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

2007-01-01

70

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

PubMed

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

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

2014-11-01

71

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

72

Surface modification of electrospun cellulose acetate nanofibers via RAFT polymerization for DNA adsorption.  

PubMed

We report on a facile and robust method by which surface of electrospun cellulose acetate (CA) nanofibers can be chemically modi?ed with cationic polymer brushes for DNA adsorption. The surface of CA nanofibers was functionalized by growing poly[(ar-vinylbenzyl)trimethylammonium chloride)] [poly(VBTAC)] brushes through a multi-step chemical sequence that ensures retention of mechanically robust nanofibers. Initially, the surface of the CA nanofibers was modified with RAFT chain transfer agent. Poly(VBTAC) brushes were then prepared via RAFT-mediated polymerization from the nanofiber surface. DNA adsorption capacity of CA nanofibrous web surface functionalized with cationic poly(VBTAC) brushes was demonstrated. The reusability of these webs was investigated by measuring the adsorption capacity for target DNA in a cyclic manner. In brief, CA nanofibers surface-modified with cationic polymer brushes can be suitable as membrane materials for filtration, purification, and/or separation processes for DNA. PMID:25256476

Demirci, Serkan; Celebioglu, Asli; Uyar, Tamer

2014-11-26

73

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

74

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

75

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

NASA Astrophysics Data System (ADS)

A novel microstructured polymer optical fiber (MPOF) probe for nitrites (NO 2-) detection was made by forming rhodamine 6G (Rh 6G)-doped cellulose acetate (CA) on the side wall of array holes in a MPOF. It was found that the MPOF probe only have a response to nitrites in a certain concentration of sulfuric acid solution. The calibration graph of fluorescence intensity versus nitrites concentration was linear in the range of 2.0 × 10 - 4 g/ml-5.0 × 10 - 3 g/ml. The method possesses ease of chemical modification, low cost design, and potential for direct integration with existing instrumentation, and has been applied to the determination of nitrites in real samples with satisfactory results.

Li, Dongdong; Wang, Lili

2010-07-01

76

Polyethylene-supported polyvinylidene fluoride-cellulose acetate butyrate blended polymer electrolyte for lithium ion battery  

NASA Astrophysics Data System (ADS)

The polyethylene (PE)-supported polymer membranes based on the blended polyvinylidene fluoride (PVDF) and cellulose acetate butyrate (CAB) are prepared for gel polymer electrolyte (GPE) of lithium ion battery. The performances of the prepared membranes and the resulting GPEs are investigated by scanning electron microscopy, electrochemical impedance spectroscopy, linear potential sweep, and charge-discharge test. The effect of the ratio of PVDF to CAB on the performance of the prepared membranes is considered. It is found that the GPE based on the blended polymer with PVDF:CAB = 2:1 (in weight) has the largest ionic conductivity (2.48 × 10-3 S cm-1) and shows good compatibility with anode and cathode of lithium ion battery. The LiCoO2/graphite battery using this GPE exhibits superior cyclic stability at room temperature, storage performance at elevated temperature, and rate performance.

Liu, Jiansheng; Li, Weishan; Zuo, Xiaoxi; Liu, Shengqi; Li, Zhao

2013-03-01

77

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

78

Synthesis, characterization and antibacterial activity of cellulose acetate-tin (IV) phosphate nanocomposite.  

PubMed

Cellulose acetate-tin (IV) phosphate nanocomposite (CA/TPNC) was prepared using simple method at 0-1 pH. The nanocomposite ion exchanger was characterized using some techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA/DTA/DSC). The nanocomposite material was explored for different properties such as ion exchange capacity, pH titration, elution behavior, thermal stability, and distribution coefficient. The ion exchange capacity of CA/TPNC was found higher compared to their inorganic counterpart. The distribution coefficient studies of nanocomposite ion exchanger were investigated for different metal ions. On the basis of distribution coefficient studies CA/TPNC material was found more selective for Cd(2+) and Mg(2+). CA/TPNC ion exchange was explored for antibacterial activities against E. coli bacteria. PMID:24528723

Rathore, Bhim Singh; Sharma, Gaurav; Pathania, Deepak; Gupta, Vinod Kumar

2014-03-15

79

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

80

In vitro methane emission and acetate:propionate ratio are decreased when artificial stimulation of the rumen wall is combined with increasing grain diets in sheep.  

PubMed

The interaction of retention time in the rumen and concentrate diet on methane production in vitro and acetate:propionate ratio was examined. Twenty-four fistulated sheep were used in a complete factorial design with the sheep randomly divided into 4 groups. The sheep had a 5-wk acclimatization period on an oaten chaff diet, followed by two 3-wk diet phases. Two of the 4 groups were maintained on the oaten chaff diet for the duration of the experiment, with pot scrubbers added to the rumen of 1 of the 2 groups. The remaining 2 groups were offered a low-grain diet (35% grain) in the first diet phase followed by a high-grain diet (70% grain) in the second diet phase. Pot scrubbers were also added to the rumen of 1 of these 2 groups of grain-fed sheep. Pot scrubbers in combination with a low-grain diet decreased the amount of methane produced in vitro from 4.25 to 3.71 mmol/mL of digesta when compared with oaten chaff-fed sheep without pot scrubbers (P < 0.05). The acetate:propionate ratio was 1.6 in sheep fed a high-grain diet with pot scrubbers compared with 2.4 in sheep fed a high-grain diet without pot scrubbers in their rumen (P < 0.05). At high levels of grain, when employing a multivariate statistical analysis including all data, sheep given the combined treatment of grain and pot scrubbers were different from all other sheep groups in this experiment (P < 0.05). Furthermore, sheep fed a high-grain diet were different from sheep receiving the oaten chaff diets with and without pot scrubbers (P < 0.01 and P < 0.05, respectively). In conclusion, pot scrubbers combined with grain alter the rumen fermentation, and introducing pot scrubbers into the rumens of livestock consuming low levels of grain may be a way to lower methane emissions. PMID:18042816

Christophersen, C T; Wright, A-D G; Vercoe, P E

2008-02-01

81

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

PubMed

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

Ramesh, S; Shanti, R; Morris, Ezra

2013-01-01

82

Amperometric glucose biosensor based on a gold nanorods/cellulose acetate composite film as immobilization matrix.  

PubMed

We report on the utilization of gold nanorods to create a highly responsive glucose biosensor. The feasibility of an amperometric glucose biosensor based on immobilization of glucose oxidase (GOx) in gold nanorod is investigated. GOx is simply mixed with gold nanorods and cross-linked with a cellulose acetate (CA) medium by glutaraldehyde. The adsorption of GOx on the gold nanorods is confirmed by X-ray photoelectron spectroscopy (XPS) measurements. Circular dichroism (CD) and UV-spectrum results show that the activity of GOx was preserved after conjugating with gold nanorods. The current response of modified electrode is 10 times higher than that of without gold nanorods. Under optimal conditions, the biosensor shows high sensitivity (8.4 microA cm(-2) mM(-1)), low detection limit (2x10(-5) M), good storage stability and high affinity to glucose (K(m)(app)=3.84 mM). A linear calibration plot is obtained in the wide concentration range from 3x10(-5) to 2.2x10(-3) M. PMID:19414241

Ren, Xiangling; Chen, Dong; Meng, Xianwei; Tang, Fangqiong; Du, Aiming; Zhang, Lin

2009-09-01

83

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

PubMed

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

84

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

85

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

86

Polymorphism of spray-dried microencapsulated sulfamethoxazole with cellulose acetate phthalate and colloidal silica, montmorillonite, or talc.  

PubMed

Sulfamethoxazole was microencapsulated with cellulose acetate phthalate and talc, colloidal silica, or montmorillonite clay by a spray-drying technique. The surface topography of the products varied with the type of excipient used and the pH of the suspending medium. The products without the excipient were coated with flake-like crusts, while the products containing the excipient tended to become well-rounded spheres. In addition, the crystalline form of sulfamethoxazole converted from Form I to an amorphism and Form II during the spray-drying process. This polymorphic transformation was attributed to the interaction of cellulose acetate phthalate with sulfamethoxazole. Increasing the concentration of cellulose acetate phthalate in the formulation increased the attainment of amorphism. Form II was also obtained by freeze and vacuum drying. Talc was the only excipient that contributed to polymorphism, which occurred in the alkaline suspension medium. Montmorillonite products prepared from the acidic medium exhibited an exothermic differential scanning calorimetry thermogram, which might be interpreted in terms of adsorption of the fused sulfamethoxazole with the internal surface of montmorillonite, PMID:6271946

Takenaka, H; Kawashima, Y; Lin, S Y

1981-11-01

87

Poly(vinyl chloride) blend with biodegradable cellulose acetate in presence of N-(phenyl amino) maleimides.  

PubMed

Wider plastic applications of poly(vinyl chloride) (PVC) has raised serious problem to the environment. Since (PVC) waste products resist biodegradation and persist in the environment for longer time. The object of this study is to blend (PVC) with biodegradable cellulose acetate to thermally support the polymer during the molding process as well as to enhance the biodegradability of (PVC) waste products. Blending of poly(vinyl chloride) and cellulose acetate (CA) in presence of N-(phenyl amino) maleimides (R-PhAM) where (R=H, 4-NO2) led to improvement in the thermal stability of the blend film at high temperatures as shown from the high values of initial decomposition temperature (To) determined from their thermogravimetry (TG) curves. Also, blending (PVC) with (CA) led to improvement in the mechanical properties of the blend films as compared to (PVC). The crystalline regions of cellulose acetate enhanced the elasticity of the blend films as shown from their high Young's modulus values. PMID:24973650

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

2014-09-01

88

Comparison of Capillary Electrophoresis with Cellulose Acetate Electrophoresis for the Screening of Hemoglobinopathies  

PubMed Central

Background ?-thalassemia is primarily found in individuals of Mediterranean and Southeast Asian ancestry. With rapid growth in the Southeast Asian segments of the Korean population, the geographic distribution of hemoglobinopathies is expected to become significantly different from what it is today. In this study, Hb fractions were measured in patients with hypochromic microcytosis to detect thalassemia and Hb variants. To evaluate the feasibility of replacing cellulose acetate electrophoresis (CA) with capillary electrophoresis (CE) in a clinical laboratory, both techniques were performed and the outcomes were compared. Methods To evaluate hemoglobinopathies, complete blood cell counts (CBC), CA, and CE were carried out on samples from healthy and microcytic hypochromic groups. The microcytic hypochromic group consisted of 103 patients whose mean corpuscular volume (MCV) was less than 75 fL and mean corpuscular hemoglobin (MCH) was less than 24 pg. Quantitative analysis of Hb fractions was performed on 143 whole blood samples. Results There was a good correlation for measurements of HbA (r=0.9370, P<0.0001), HbA2 (r=0.8973 P<0.0001), and HbF (r= 0.8010, P=0.0304) between the two methods. In the microcytic hypochromic group, there were 29 cases (28.2%) with decreased HbA2, 2 cases (1.9%) with increased HbA2, 3 cases (2.9%) with increased HbF, and 2 cases (1.9%) with increased HbA2 and HbF. Conclusions CE is comparable to CA for reliable measurement of Hb fractions. It is suitable for screening of hemoglobinopathies in many clinical laboratories. PMID:22016676

Kim, Ji-Eun; Kim, Bo-Ram; Woo, Kwang-Sook; Kim, Jeong-Man; Park, Joo-In

2011-01-01

89

Responses in the voluntary intake of hay or silage by lactating cows to intraruminal infusions of sodium acetate or sodium propionate, the tonicity of rumen fluid or rumen distension.  

PubMed

Rumen-fistulated lactating cows were individually fed on hay or silage and intakes were monitored during 3 h treatment periods and for 2 h after. Each experiment used five, six or seven animals and the treatments were applied in a Latin Square design. Sodium acetate infusions of 1.8-11.0 mol in 4.5 litres water caused a dose-related depression in hay intake, the extent being 82 g dry matter (DM)/mol infused (P < 0.01). Sodium acetate infusions of 6.0-15.0 mol in 4.5 litres water caused a dose-related depression in silage intake of 118 g DM/mol infused. Rumen fluid pH for both diets was unaffected by treatment. Acetate and Na concentrations were increased and significantly negatively correlated with intake of both diets. Infusions of 2-8 mol sodium propionate caused a dose-related depression of hay intake which was significant when cow and day effects were accounted for. Sodium propionate infusions of 4-8 mol significantly depressed silage intake by 140 g DM/mol infused (P < 0.001). Rumen fluid pH was unaffected by treatment while propionate and Na concentrations were elevated and significantly negatively correlated with intake for both diets. Inflation of a rubber balloon in the rumen with 12.5-20 litres warm water resulted in a dose-dependent depression in hay intake of 66 g DM/l distension (P < 0.05). There was significant overeating during the 2 h following the 20 litre treatment. With silage, 15-25 litres of balloon distension for 3 h resulted in a dose-dependent depression in intake of 28 g DM/l distension (P < 0.001). There was no significant overeating during the 2 h following distension. When given in physiological amounts, at the lower end of the range used in these experiments, acetate, propionate and distension of the rumen did not significantly affect hay intakes. However, in each case the linear relationship between intake depression and level of treatment suggested that these factors could contribute to the control of feed intake. PMID:8329346

Anil, M H; Mbanya, J N; Symonds, H W; Forbes, J M

1993-05-01

90

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

91

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

NASA Astrophysics Data System (ADS)

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

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

1996-01-01

92

Microbial degradation of poly-b-esters: A mechanistic study, cellulose acetate biodegradability. Final report, 1 May 1990-31 July 1993  

SciTech Connect

In this Final Report, work carried out under ARO grant C-DAAL03-G-0111 is described. The investigations performed include the following: (1) isolation, purification and characterization of a poly(3-hydroxybutyrate) depolymerase enzyme from Penicillium funiculosum, (2) determination that the depolymerase is a serine esterase, (3) study of the effect of polymer stereochemistry and crystalline order in a semi-crystalline polymer film substrate on enzyme specificity and activity, (3) isolation, purification and characterization of cellulose acetate degrading microorganisms and (4) determination of the biodegradability of cellulose acetate with degrees of substitution up to 2.5 under aerobic thermophilic conditions. Poly(3-hydroxybutyrate) biodegradation, Poly(3-hydroxybutyrate) depolymerase enzyme, Depolymerase from Penicillium funiculosum, Cellulose acetate degrading microorganisms, Composting polymer biodegradable.

Gross, R.A.

1993-08-30

93

Dissolution enthalpies of cellulose in ionic liquids.  

PubMed

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

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

2014-11-26

94

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

95

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

PubMed Central

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 been shown to inactivate HIV-1, herpes simplex virus types 1 and 2, cytomegalovirus, Neisseria gonorrhoeae, Trichomonas vaginalis, Haemophilus ducreyi, and Chlamydia trachomatis in vitro. Formulated CAP was also shown to be effective against herpes simplex virus type 2 in vivo. Here we show that a formulation of CAP protected four of six rhesus monkeys from vaginal infection with simian immunodeficiency virus. Thus, CAP may be a candidate for use as a topical microbicide for preventing HIV-1 infection in humans. PMID:11036053

Manson, Kelledy H.; Wyand, Michael S.; Miller, Christopher; Neurath, A. Robert

2000-01-01

96

Burning of solids in oxygen-rich environments in normal and reduced gravity. [combustion of cellulose acetates  

NASA Technical Reports Server (NTRS)

An experimental program was conducted to investigate the combustion characteristics of solids burning in a weightless environment. The combustion characteristics of thin cellulose acetate material were obtained from specimens burned in supercritical as well as in low pressure oxygen atmospheres. Flame spread rates were measured and found to depend on material thickness and pressure in both normal gravity (1-g) and reduced gravity (0-g). A gravity effect on the burning process was also observed; the ratio of 1-g to 0-g flame spread rate becomes larger with increasing material thickness. Qualitative results on the combustion characteristics of metal screens (stainless steel, Inconel, copper, and aluminum) burning in supercritical oxygen and normal gravity are also presented. Stainless steel (300 sq mesh) was successfully ignited in reduced gravity; no apparent difference in the flame spread pattern was observed between 1-g and 0-g.

Andracchio, C. R.; Cochran, T. H.

1974-01-01

97

Effect of varying drug loading on particle size distribution and drug release kinetics of verapamil hydrochloride microspheres prepared with cellulose esters.  

PubMed

Microspheres containing two different drug loadings of a calcium channel blocker, verapamil hydrochloride, were prepared with three different cellulose esters namely cellulose acetate (CA), cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) of approximately similar molecular weights using the emulsion-solvent evaporation method. Increasing the drug loading from 33.3 to 50% w/w increased the geometric mean diameter of the microspheres as well as the T50% values, i.e. time required to release 50% of the drug from microspheres prepared with all the three cellulose esters. Drug release from the microspheres was affected by the nature of polymer. Mathematical modelling of drug release data by fitting the data to various equations revealed that the data did not fit the conventional Higuchi's and Baker-Lonsdale's models for drug release from spherical matrices. Instead, the data fitted the log-probability and the Weibull models quite well. PMID:7730959

Bhardwaj, S B; Shukla, A J; Collins, C C

1995-01-01

98

A novel support for laccase immobilization: cellulose acetate modified with ionic liquid and application in biosensor for methyldopa detection.  

PubMed

A material based on cellulose acetate (CA) and the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI·N(Tf)(2)) was developed and characterized by scanning electron microscopy, electron dispersive spectroscopy and infrared analysis. Laccase (Lac) from Aspergillus oryzae was immobilized in this material to investigate the behavior of methyldopa by square-wave voltammetry. Under optimized conditions, the Lac biosensor based on CA/BMI·N(Tf)(2) exhibited an excellent electrocatalytic performance: the analytical curve showed good linear range for methyldopa concentrations from 34.8 to 370.3 ?M with a detection limit of 5.5 ?M. This sensor demonstrated acceptable stability (ca. 60 days; at least 350 determinations), good repeatability and reproducibility (relative standard deviations of 1.5 and 4.3%, respectively). The recovery study of methyldopa in pharmaceutical formulations ranged from 94.1 to 105.9%. The determination of this substance using the biosensor compared favorably with that using a spectrophotometry procedure at the 95% confidence level, and indicated potential application to methyldopa determination in pharmaceutical samples. PMID:21353521

Moccelini, Sally K; Franzoi, Ana C; Vieira, Iolanda C; Dupont, Jairton; Scheeren, Carla W

2011-04-15

99

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

100

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

101

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

PubMed

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

Li, Renjie; Liu, Lifen; Yang, Fenglin

2014-09-15

102

Adsorption and desorption of a gold–iodide complex onto cellulose acetate membrane coated with polyaniline or polypyrrole: a comparative study  

Microsoft Academic Search

Cellulose acetate membranes (M1) with controlled thickness were coated with an electroconductive polymer, and the resulting\\u000a composites were characterized by SEM, XPS, electrical conductivity, and mechanical measurements. A comparative study of M1\\u000a coated with polyaniline (PANI) or with polypyrrole (PPy) for adsorption and subsequent desorption of a gold–iodide complex\\u000a was performed. The PANI-coated M1 (M2) and that coated with PPy

M. M. Castillo-Ortega; I. Santos-Sauceda; J. C. Encinas; D. E. Rodriguez-Felix; T. del Castillo-Castro; F. Rodriguez-Felix; J. L. Valenzuela-García; L. S. Quiroz-Castillo; P. J. Herrera-Franco

2011-01-01

103

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

PubMed Central

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

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

2010-01-01

104

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

PubMed

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

Jelvehgari, M; Maghsoodi, M; Nemati, H

2010-01-01

105

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

106

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. PMID:24250377

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

2011-01-01

107

Kinetics of sulfate reduction and sulfide toxicity in anaerobic systems fed propionate  

Microsoft Academic Search

Kinetics of substrate utilization for different groups of bacteria in an anaerobic system fed propionate (HPr) and sulfate (SO[sub 4]) were determined using batch experiments. Six major COD flow pathways were identified based on thermodynamics: incomplete oxidation of propionate by sulfate reducing bacteria (SRB), propionate fermentation to acetate (HAc) and hydrogen (H[sub 2]), HAc utilization by SRB, aceticlastic methanogenesis, H[sub

Maillacheruvu

1993-01-01

108

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

109

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. PMID:24957062

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

2013-01-01

110

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

PubMed Central

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

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

2012-01-01

111

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

PubMed

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. PMID:24957062

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

2013-01-01

112

Synthesis at the Air-Water Interface of a Two-Dimensional Semi-Interpenetrating Network Based on Poly(dimethylsiloxane) and Cellulose Acetate Butyrate.  

PubMed

The UV-induced cross-linking of methacryloxypropyl-terminated poly(dimethylsiloxane) oligomers was studied at the air-water interface either in pure PDMS Langmuir monolayers or in mixed films containing cellulose acetate butyrate. Surface pressure-area isotherms, area measurement at constant surface pressure, Brewster angle microscopy observations, and infrared-visible sum frequency generation (SFG) spectroscopy were combined to follow the evolution of the monolayers upon in situ UV photoirradiation. For both systems, the mean area per repeat unit decreases with irradiation time reflecting the monolayer contraction. In addition, SFG measurements evidence the conversion of the methacrylate groups into unconjugated poly(methacrylate) ones. These results demonstrate PDMS cross-linking, leading to the formation of either a single PDMS network or a PDMS network entrapped in a CAB matrix. The network formation is accompanied by morphology changes as shown by atomic force microscopy on the transferred monolayer. Indeed, filamentous structures appear on both pure and mixed preirradiated monolayers. PMID:25238044

El Haitami, Alae; Backus, Ellen H G; Cantin, Sophie

2014-10-14

113

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

PubMed Central

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

Alpat, Senol; Telefoncu, Azmi

2010-01-01

114

Preparation and in vitro evaluation of propylthiouracil microspheres made of Eudragit RL 100 and cellulose acetate butyrate polymers using the emulsion-solvent evaporation method.  

PubMed

The objectives of this investigation are to evaluate the encapsulation efficiency of the anti-thyroid agent 6-n-propyl-2-thiouracil using two polymers of different characteristics (cellulose acetate butyrate polymer, (CAB-551-0.01) and ammonio methacrylate copolymer (Eudragit RL 100) and to study the effect of this encapsulation on the drug release properties. Polymers were used separately and in combination to prepare different microspheres. Also, the effect of polymer solution phase viscosity was studied for each of the polymers and for their combinations. An Ostwald viscometer was used to evaluate the relative viscosities of polymer solution phases and their combinations. Microspheres with 25% theoretical drug loading of 6-n-propyl-2-thiouracil core material were prepared by the emulsion solvent evaporation method. Microspheres prepared from CAB-551-0.01, which has higher relative polymer phase viscosity than Eudragit RL 100, showed significantly lower drug release rates and a noticeable lag time. Polymer combinations of CAB-551-0.01 and Eudragit RL 100 (1:1) showed an interesting synergistic increase in relative polymer solution viscosities at all concentrations. Unlike microspheres prepared from the two polymers separately which follow Higuchi spherical matrix release kinetics, microspheres prepared using a combination (1:1) of the two polymers showed near zero order with faster rates compared to those prepared using CAB-551-0.01 equivalent polymer concentrations. The results of this study suggest that 6-n-propyl-2-thiouracil was successfully and efficiently encapsulated and release rates of matrix microspheres are related to polymer solution phase viscosity, but when polymer combinations were used other factors such as structural effects must be considered. PMID:16019914

Obeidat, W M; Price, J C

2005-05-01

115

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

116

Cellulose acetate microspheres as floating depot systems to increase gastric retention of antidiabetic drug: formulation, characterization and in vitro-in vivo evaluation.  

PubMed

Gastric emptying is a complex process that is highly variable and makes the in vivo performance of drug delivery systems uncertain. In order to avoid this variability, efforts have been made to increase the retention time of the drug delivery systems for more than 12 hours utilizing floating or hydrodynamically controlled drug delivery systems. The objective of this investigation was to develop a floating, depot-forming drug delivery system for an antidiabetic drug based on microparticulate technology to maintain constant plasma drug concentrations over a prolonged period of time for effective control of blood sugar levels. Formulations were optimized using cellulose acetate as the polymer and evaluated in vitro for physicochemical characteristics and drug release in phosphate buffered saline (pH 7.4), and evaluated in vivo in healthy male albino mice. The shape and the surface morphology of the prepared microspheres were characterized by optical microscopy and scanning electron microscopy. In vitro drug release studies were performed and drug release kinetics were calculated using the linear regression method. Effects of stirring rate during preparation and polymer concentration on the size of microspheres and drug release were observed. The prepared microspheres exhibited prolonged drug release (more than 10 hours) and remained buoyant for over 10 hours. Spherical and smooth-surfaced microspheres with encapsulation efficiency ranging from 73% to 98% were obtained. The release rate decreased and the mean particle size increased at higher polymer concentrations. Stirring speed affected the morphology of the microspheres. This investigation revealed that upon administration, the biocompatible depot-forming polymeric microspheres controlled the drug release and plasma sugar levels more efficiently than plain orally given drug. These formulations, with their reduced frequency of administration and better control over drug disposition, may provide an economic benefit to the user compared with products currently available for diabetes control. PMID:18401776

Choudhury, Pratim K; Kar, Mousumi; Chauhan, Chetan S

2008-04-01

117

Studies on electrochemical characterization and performance prediction of cellulose acetate and Zeocarb-225 composite membranes in aqueous NaCl solutions.  

PubMed

We have mixed cellulose acetate and Zeocarb-225 in different ratios, leading to the preparations of Membrane-1 and Membrane-2. Membrane potential, water content, and conductance measurements have been carried out to estimate and analyze the data in terms of equilibria and important electrochemical parameters. The Donnan equilibrium has been incorporated to estimate the activity coefficient of counterions, y(p)M, and solute, y(+/-)M in the membrane phase along with the parameter, so called varphi expressing non-ideality. Dependence of the extent of hydrophilicity of both membranes on mean electrolyte concentrations has been examined. Selectivity in membranes is discussed in terms of dissociation equilibria, K(d)s and K(d)f. It has been found that membrane surface charge density sigma(s) increases with increasing of external NaCl concentration. Dependence of water transport number and cationic transport number on electrolyte concentration shows a similar trend of variation. At higher mean concentration of electrolyte, water transport number in Membrane-2 has a negative value. Membrane-2 has a higher value of water transport number than Membrane-1. The entropy production due to solute and water transport has been quantified for both the membranes in the light of nonequilibrium thermodynamics. The various type of interactions such as solute-membrane, solute-water, and water-membrane are analyzed in terms of friction coefficients (f(ij)) of Spiegler's frictional pore model. In our case, an f(wm) < f(sm) < f(sw)-like trend is observed in both membranes. These frictional coefficients show close dependence on external electrolyte concentrations. Pore potential values of Membrane-1 and Membrane-2 have been worked out using the Poisson-Boltzmann equation. In both systems pore potential values increase with increasing mean electrolyte concentrations. The transport through Membrane-1 and Membrane-2 tends to follow diffusion-control criteria, i.e., (D(+/-) . C. d/D(+/-)M C(M) . delta) > 2. A slightly higher value of solute rejection is found in Membrane-2. PMID:16499917

Tiwari, A K; Ahmad, Suhail

2006-06-01

118

Microbial production of propionic acid and vitamin B12 using molasses or sugar.  

PubMed

With a cell concentration of 125 g dry biomass l-1 and a dilution rate of 0.1 h-1, Propionibacterium acidipropionici produces 30 g propionic acid l-1 from sugar with a productivity of 3 g l-1 h-1. The yield of propionic acid is approx. 0.36-0.45 g propionic acid g-1 sucrose and is independent of the dilution rate and cell concentration. Acetic acid is an unwanted by-product in the production of propionic acid. The concentration of acetic acid only increases slightly when the cell concentration is increased. A two-stage fermentation process was developed for the conversion of sugar or molasses of various types to propionic acid and vitamin B12. By fermentation of blackstrap molasses (from sugar beet and sugar cane) in the first fermentation stage 17.7 g propionic acid l-1 with a yield of 0.5 g propionic acid g-1 carbohydrate was produced with a dilution rate of 0.25 h-1. In the second stage 49 mg vitamin B12 1-1 was produced at a dilution rate of 0.03 h-1. PMID:7765100

Quesada-Chanto, A; Afschar, A S; Wagner, F

1994-06-01

119

21 CFR 184.1221 - Calcium propionate.  

...propionate (C6 H10 CaO4 , CAS Reg. No. 4075-81-4) is the calcium salt of propionic acid. It occurs as white crystals or a crystalline solid, possessing not more than a faint odor of propionic acid. It is prepared by neutralizing...

2014-04-01

120

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

121

Acute Management of Propionic Acidemia  

PubMed Central

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

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

2014-01-01

122

21 CFR 582.3081 - Propionic acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01...2013-04-01 false Propionic acid. 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.3081 Propionic acid. (a) Product....

2013-04-01

123

21 CFR 582.3081 - Propionic acid.  

21 Food and Drugs 6 2014-04-01...2014-04-01 false Propionic acid. 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.3081 Propionic acid. (a) Product....

2014-04-01

124

21 CFR 582.3081 - Propionic acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01...2010-04-01 false Propionic acid. 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.3081 Propionic acid. (a) Product....

2010-04-01

125

21 CFR 582.3081 - Propionic acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01...2012-04-01 false Propionic acid. 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.3081 Propionic acid. (a) Product....

2012-04-01

126

21 CFR 582.3081 - Propionic acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01...2011-04-01 false Propionic acid. 582.3081 Section 582.3081 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.3081 Propionic acid. (a) Product....

2011-04-01

127

21 CFR 556.710 - Testosterone propionate.  

Code of Federal Regulations, 2010 CFR

...Testosterone propionate. No residues of testosterone, resulting from the use of testosterone propionate, are permitted in excess of the following increments above the concentrations of testosterone naturally present in untreated animals: (a) In uncooked edible tissues of heifers: (1) 0.64 part per billion in muscle. (2) 2.6 parts per billion in fat. (3) 1.9 parts per billion in......

2010-04-01

128

Effect of Intraruminal Propionic Acid Infusion on Metabolism of Mesenteric and Portal-Drained Viscera in Growing Steers Fed a Forage Diet: I. Volatile Fatty Acids, Glucose, and Lactate1  

Microsoft Academic Search

This experiment investigated the effect of intraruminal infusion of propionic acid on ruminal VFA metabolism and the absorption of nutrients by the mesenteric- and portal-drained viscera of seven Friesian steers, average BW 127 kg, fed a dried grass-pellet diet. Each received by random allocation 0 (control), .5, or 1.0 mol of propionic acidd for 7 d. Ruminal acetate and propionate

C. J. Seal; D. S. Parker

2010-01-01

129

Effect of propionate on in vivo carbohydrate metabolism in streptozocin-induced diabetic rats.  

PubMed

Undigested carbohydrates and some dietary fibers are fermented in the large intestine to form short-chain fatty acids (SCFA), including acetate, propionate, and butyrate. It has been suggested that some of the beneficial effects of high-carbohydrate, high-fiber diets on carbohydrate and lipid metabolism are mediated by the metabolism of SCFA in the liver. Propionate has been shown in vitro to decrease glucose production in rat hepatocytes. The aim of the present study was to investigate the effects of propionate on carbohydrate metabolism in normal and streptozocin (STZ)-induced diabetic male Sprague-Dawley rats. Rats were fed a high-fat diet with or without sodium propionate supplementation (either 0.5% or 5% wt/wt) for 4 weeks. At the completion of the feeding period, body weight and liver glycogen concentrations were significantly decreased in STZ-diabetic rats and were unaffected by propionate supplementation. Although STZ-diabetic animals had elevated fasting plasma glucose, cholesterol, and triglyceride levels relative to nondiabetic rats, propionate supplementation had no significant effect on these parameters in either group. Basal and insulin-stimulated carbohydrate metabolism were assessed using the euglycemic clamp technique in overnight-fasted animals with 3(H)-6-glucose infusion. As expected, basal hepatic glucose production (HGP) was higher and the metabolic clearance rate of glucose (MCR) was lower in STZ-diabetic rats. High-dose insulin infusion (3 mU.kg-1.min-1) suppressed HGP in nondiabetic and diabetic animals and increased the MCR in nondiabetic animals. However, propionate supplementation did not alter basal or insulin-stimulated HGP or the MCR in either nondiabetic or diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8201962

Cameron-Smith, D; Collier, G R; O'Dea, K

1994-06-01

130

Assembly of synthetic cellulose I.  

PubMed Central

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

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

1994-01-01

131

Propionic acid accumulation and degradation during restart of a full-scale anaerobic biowaste digester.  

PubMed

The methane formation rate of 300 m(3) of sludge from a full scale biowaste reactor, that was stored without feeding for six weeks during a maintenance period, was about 60% of the methanogenic activity before maintenance. The 300 m(3) sludge was then pumped back into the biowaste reactor. On the third day, after refilling of the stored biowaste suspension, anaerobic conditions were obtained and feeding was started by addition of 36.1 m(3) of fresh biowaste suspension (=11.3 tons biowaste). The pH dropped from originally pH 7.7 to pH 7.3 and later on to pH 6.8, which was considered the minimum allowed pH for methanogenesis to recover. Maximum concentrations of acetate (1.78 gl(-1)), n-butyrate (0.57 gl(-1)) and n-valerate (0.44 gl(-1)) accumulated during the following days with feeding of 11.8 tons on day 5 and twice 6.5 tons on days 7 and 9, respectively. Thereafter, acetate, n-butyrate and n-valerate were degraded completely, whereas the concentration of propionate was still increasing. Propionic acid was the dominant fatty acid during the restart period and reached its maximum concentration of 6.2 gl(-1) 17 days after start of feeding. This high level of propionate was degraded completely in about 5 days with maximum degradation rates of 2.14 gl(-1)d(-1), and the pH of the anaerobic sludge increased from 7.1 to 7.4. During restart, the methane content of the biogas increased successively to 65%. Samples that were taken at different time intervals during the restart phase of the methane reactor showed different fatty acid degradation capabilities. After 10 days, when acetate and n-butyrate still accumulated in the methane reactor the maximum acetate degradation rate was 1.52 gl(-1)d(-1) and the n-butyrate degradation rate was 0.51 gl(-1)d(-1). Oxidation of n-valerate caused an increase of propionate, which was degraded after a lag phase of 6 days with a maximum rate of 0.6 gl(-1)d(-1). In the samples taken after 16 and 23 days, the propionate degradation rate increased to 1.42 gl(-1)d(-1) and 1.55 gl(-1)d(-1), respectively, and the lag phase for propionate degradation was reduced or had disappeared completely. The maximum propionate degradation rate was measured in the methane reactor in the fourth week after restart. The synthrophic propionate oxidizing bacteria were apparently the most suffering bacteria during sludge storage. If the propionate oxidizing bacteria could be kept active and the propionate degrading activity of the biowaste suspension of 6.16 gl(-1)d(-1) before the maintenance period could be maintained, then accumulation of 6.2 gl(-1) propionate in the methane reactor after restart could be avoided and full activity reached even earlier. PMID:17197176

Gallert, C; Winter, J

2008-01-01

132

Methylmalonic and propionic acidaemias: Management and outcome  

Microsoft Academic Search

Organic acidurias comprise many various disorders. Methylmalonic aciduria (MMA) and propionic aciduria (PA) are the most frequent diseases and the two organic acidurias for which we have better knowledge of the long-term outcome.

H. OGIER DE BAULNY; J. F. Benoist; O. Rigal; G. Touati; D. Rabier; J. M. Saudubray

2005-01-01

133

Enhancing the cellulose-degrading activity of cellulolytic bacteria CTL-6 (Clostridium thermocellum) by co-culture with non-cellulolytic bacteria W2-10 (Geobacillus sp.).  

PubMed

The effect of a non-cellulolytic bacterium W2-10 (Geobacillus sp.) on the cellulose-degrading activity of a cellulolytic bacterium CTL-6 (Clostridium thermocellum) was determined using cellulose materials (paper and straw) in peptone cellulose solution (PCS) medium under aerobic conditions. The results indicated that in the co-culture, addition of W2-10 resulted in a balanced medium pH, and may provide the required anaerobic environment for CTL-6. Overall, addition of W2-10 was beneficial to CTL-6 growth in the adverse environment of the PCS medium. In co-culture with W2-10, the CTL-6 cellulose degradation efficiency of filter paper and alkaline-treated wheat straw significantly increased up to 72.45 and 37.79 %, respectively. The CMCase activity and biomass of CTL-6 also increased from 0.23 U ml(-1) and 45.1 ?g ml(-1) (DNA content) up to 0.47 U ml(-1) and 112.2 ?g ml(-1), respectively. In addition, co-culture resulted in accumulation of acetate and propionate up to 4.26 and 2.76 mg ml(-1). This was a respective increase of 2.58 and 4.45 times, in comparison to the monoculture with CTL-6. PMID:23975281

Lü, Yucai; Li, Ning; Yuan, Xufeng; Hua, Binbin; Wang, Jungang; Ishii, Masaharu; Igarashi, Yasuo; Cui, Zongjun

2013-12-01

134

Spectrophotometric determination of dissociation constants for propionic acid and 2,5-dinitrophenol at elevated temperatures  

Microsoft Academic Search

Using the temperature dependence of pKa for acetic acid, the pKa for 2,5-dinitrophenol have been spectrophotometrically determined in acetate buffer at elevated temperatures under the saturation vapor pressures. For 2,5-dinitrophenol\\u000a$$pK_a = - 33.206 + 2106.7\\/T + 5.495\\\\ln T$$\\u000a where T is in Kelvin. Similarly, pKa values of propionic acid were obtained at temperatures from 25°C to 175°C producing\\u000a$$pK_a

In-Ja Lee; Gang-Sook Jung; Keon Kim

1994-01-01

135

Effect of oral antibiotics on intestinal production of propionic acid  

PubMed Central

BACKGROUND—Propionic 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.?AIMS—To 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.?METHODS—In vitro fermentation techniques were used to study the effects of addition of antibiotics (metronidazole, clindamycin, erythromycin, and vancomycin) on net faecal production of short chain fatty acids including propionic acid. Courses of oral antibiotics of 7 days duration were used to assess the in vivo effects on faecal propionate production and metabolic control including plasma propionate concentrations.?RESULTS—Metronidazole produced the largest and most consistent reduction (77-84%) in the production in vitro of propionate from faecal homogenates. Oral administration of metronidazole reduced faecal propionate production by 43% within 24 hours of treatment; a 7day course virtually eliminated it for the next 3 weeks. These reductions were accompanied by substantially lowered plasma propionate concentrations during the same period.?CONCLUSIONS—Intermittent courses of oral metronidazole might be as effective as continuous treatment in reducing gut propionate production in children with disorders of propionate metabolism.?? PMID:10648377

Mellon, A; Deshpande, S; Mathers, J; Bartlett, K

2000-01-01

136

ATTACHMENT 6 Crosslinkingof CelluloseAcetate with  

E-print Network

that if trifluoromethanesulfonic (triflic) anhydride could be formed in situ from triflic acid in the pyridine reaction mixture, only catalytic amounts of triflic acid would be required to form crosslinks. Triflic anhydride is produced from triflic acid in the presence of P205 at ambient temperature? Furthermore, triflic anhydride

Narayan, Ramani

137

Cellulose digestion and metabolism induced biocatalytic transitions in anaerobic microbial ecosystems.  

PubMed

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. PMID:24958386

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

2013-01-01

138

Original article The effect of supplemental propionate on insulin  

E-print Network

utilization in response to insulin infusion or enhance glucose production from propionate. @ Inra réponse à l'infusion d'insuline ou augmenter la production de glucose à partir du propionate. (@ InraOriginal article The effect of supplemental propionate on insulin responsiveness to glucose

Boyer, Edmond

139

Effect of Acetic, Lactic and other Organic Acids on the Formation of Artificial Carious Lesions  

Microsoft Academic Search

Artificial carious lesions were produced in human enamel using a diphosphonate\\/organíc acid system over periods up to 30 days, and progress assessed by depth measurement. Acids studied were lactic, acetic, propionic, isobutyric, succinic, tartaric, hydrochloric and hydrofluoric. The rate of lesion progress was found to be a function of calculated unionized acid concentration, and acid dissociation constant. Acetic acid made

J. D. B. Featherstone; B. E. Rodgers

1981-01-01

140

Enhanced biological phosphorus removal in a sequencing batch reactor using propionate as the sole carbon source.  

PubMed

An enhanced biological phosphorus removal (EBPR) system was developed in a sequencing batch reactor (SBR) using propionate as the sole carbon source. The microbial community was followed using fluorescence in situ hybridization (FISH) techniques and Candidatus 'Accumulibacter phosphatis' were quantified from the start up of the reactor until steady state. A series of SBR cycle studies was performed when 55% of the SBR biomass was Accumulibacter, a confirmed polyphosphate accumulating organism (PAO) and when Candidatus 'Competibacter phosphatis', a confirmed glycogen-accumulating organism (GAO), was essentially undetectable. These experiments evaluated two different carbon sources (propionate and acetate), and in every case, two different P-release rates were detected. The highest rate took place while there was volatile fatty acid (VFA) in the mixed liquor, and after the VFA was depleted a second P-release rate was observed. This second rate was very similar to the one detected in experiments performed without added VFA.A kinetic and stoichiometric model developed as a modification of Activated Sludge Model 2 (ASM2) including glycogen economy, was fitted to the experimental profiles. The validation and calibration of this model was carried out with the cycle study experiments performed using both VFAs. The effect of pH from 6.5 to 8.0 on anaerobic P-release and VFA-uptake and aerobic P-uptake was also studied using propionate. The optimal overall working pH was around 7.5. This is the first study of the microbial community involved in EBPR developed with propionate as a sole carbon source along with detailed process performance investigations of the propionate-utilizing PAOs. PMID:14705012

Pijuan, M; Saunders, A M; Guisasola, A; Baeza, J A; Casas, C; Blackall, L L

2004-01-01

141

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

142

Shear and Extensional Rheology of Cellulose/Ionic Liquid Solutions  

E-print Network

In this study, we characterize the shear and extensional rheology of dilute to semidilute solutions of cellulose in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIAc). In steady shear flow, the semidilute solutions ...

Haward, Simon J.

143

Bioconversion of cellulose into electrical energy in microbial fuel cells  

NASA Astrophysics Data System (ADS)

In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57.5, 53 and 47 mWm-2, respectively. The anode potential varied under the different circuit loads employed. Higher coulombic efficiencies were achieved in MFCs with lower external resistance. The effect of different external resistances on the bacterial diversity and metabolism in cellulose-fed MFCs was investigated as the fourth objective. DGGE analysis of partial 16S rRNA genes showed clear differences between the planktonic and the anode-attached populations at various external resistances. Cellulose degradation was complete (< 0.1% residual), and there were no discernible differences among the MFCs. HPLC analysis of short chain fatty acids (SCFA) revealed that anaerobic degradation of cellulose was accompanied by production of acetic, propionic, butyric, isobutyric, valeric, isovaleric, and lactic acids, with acetic acid being predominant. The profile of metabolites was different among the MFCs. The concentrations of SCFA were higher in MFCs with larger external resistance. High levels of SCFA indicated that fermentative metabolism dominated over anaerobic respiration, resulting in relatively low coulombic efficiencies. The accumulation of SCFA at higher circuit resistances corresponded to lower power outputs. Methanogenesis shifts the flow of electrons available from the substrate away from electricity generation in MFCs. The fifth objective of this research was to assess the influence of methane formation on the performance of cellulose-fed MFCs under long-term operation. A maximum volumetric power density of 3.5 W m-3 was achieved in R20O MFCs, which was three times greater than that obtained with R100O MFCs (1.03 W m-3). The diversity of methanogens in cellulose-fed MFCs was also characterized. It was shown that the suppression of methanogenesis was accompanied by a decrease in the diversity of methanogens and changes in the concentration of SCFA, as revealed by DGGE analysis of PCR-amplified 16S rRNA genes and HPLC analysis, respectively. Analysis of partial 16S rRNA gene Sequences indicated that the most predominant methanogens were related to the fam

Rismani-Yazdi, Hamid

144

Hydroxypropylation of cellulose as a pretreatment for enzymatic hydrolysis  

E-print Network

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

Brix, Scott Tyson

2012-06-07

145

Syntrophic butyrate and propionate oxidation processes: from genomes to reaction mechanisms.  

PubMed

In anoxic environments such as swamps, rice fields and sludge digestors, syntrophic microbial communities are important for decomposition of organic matter to CO2 and CH4 . The most difficult step is the fermentative degradation of short-chain fatty acids such as propionate and butyrate. Conversion of these metabolites to acetate, CO2 , formate and hydrogen is endergonic under standard conditions and occurs only if methanogens keep the concentrations of these intermediate products low. Butyrate and propionate degradation pathways include oxidation steps of comparably high redox potential, i.e. oxidation of butyryl-CoA to crotonyl-CoA and of succinate to fumarate, respectively, that require investment of energy to release the electrons as hydrogen or formate. Although investigated for several decades, the biochemistry of these reactions is still not completely understood. Genome analysis of the butyrate-oxidizing Syntrophomonas wolfei and Syntrophus aciditrophicus and of the propionate-oxidizing Syntrophobacter fumaroxidans and Pelotomaculum thermopropionicum reveals the presence of energy-transforming protein complexes. Recent studies indicated that S. wolfei uses electron-transferring flavoproteins coupled to a menaquinone loop to drive butyryl-CoA oxidation, and that S. fumaroxidans uses a periplasmic formate dehydrogenase, cytochrome b:quinone oxidoreductases, a menaquinone loop and a cytoplasmic fumarate reductase to drive energy-dependent succinate oxidation. Furthermore, we propose that homologues of the Thermotoga maritima bifurcating [FeFe]-hydrogenase are involved in NADH oxidation by S. wolfei and S. fumaroxidans to form hydrogen. PMID:23766220

Müller, Nicolai; Worm, Petra; Schink, Bernhard; Stams, Alfons J M; Plugge, Caroline M

2010-08-01

146

Alpacas fed calcium propionate seem to moderate their energy intake.  

PubMed

Alpacas have evolved digestive and metabolic adaptations that enable them to survive in environments where the available feed varies in nutritional quality. Alpacas are thought to derive glucose from the deamination of amino acids in the liver, rather than via the conversion of propionate like true ruminants. Because fibre growth is dependent on the availability of absorbed amino acids, alpacas using amino acids as a source of energy should leave less amino acids available for fibre growth. If alpacas were to obtain glucose from a source of propionate, such as calcium propionate, the dependence on amino acids would be reduced leaving more available for fibre growth. Calcium propionate was added to the ration fed to 32 alpaca wethers, and fibre production was measured to monitor important fibre attributes in response to calcium propionate. Although the diets supplemented with calcium propionate should have provided more energy than the diets without calcium propionate, the metabolisable energy intake of all animals was similar (p = 0.278). It seems that rather than sparing amino acids, the alpacas regulated their energy intake and refused to consume the additional energy offered as calcium propionate. Consequently, they produced less fibre, and the diameter of their fibre was smaller than those alpacas that were not fed calcium propionate. It seems that alpacas rely on their digestive and metabolic adaptations to efficiently obtain and conserve energy for their survival. PMID:24621322

Lund, K E; Milton, J T B; Maloney, S K; Blache, D

2014-12-01

147

Fermentation of cellulose and fatty acids with enrichments from sewage sludge  

Microsoft Academic Search

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

Josef U. Winter; Charles L. Cooney

1980-01-01

148

Alkaline thermochemical degradation of cellulose to organic acids  

SciTech Connect

Cellulose can be degraded entirely to water-soluble products in aqueous, alkaline solutions. The degradation process is described reasonably well by second-order kinetics, with the hydroxide ion concentration determined by the stoichiometry of cellulose conversion to organic acids. Formic, acetic, glycolic, and lactic acids are major products of alkaline cellulose degradation. Maximum total yield found was approximately 40% based on starting weight of celluose with 4% NaOH at 280 degrees C for 10 min. At 360 degrees C, the formic, glycolic, and lactic acid yields were significantly reduced, acetic acid yield increased, and ethanol, propanol, acetone, and 2-butanone appeared as new degradation products.

Krochta, J.M.; Hudson, J.S.; Drake, C.W.; Wang, D.I.C. (ed.)

1984-01-01

149

Metabolic changes associated with hyperammonemia in patients with propionic acidemia  

Microsoft Academic Search

Propionic acidemia is an autosomal recessive disorder caused by deficiency of propionyl CoA carboxylase. Affected patients can develop severe hyperammonemia, whose causative mechanism is unknown. In this study, we monitored changes in metabolic parameters associated with hyperammonemia in patients with propionic acidemia. Levels of ammonia were correlated with plasma levels of individual amino acids and carnitine and with urinary organic

Heather R. Filipowicz; Sharon L. Ernst; Carrie L. Ashurst; Marzia Pasquali; Nicola Longo

2006-01-01

150

Microparticulate based topical delivery system of clobetasol propionate.  

PubMed

Psoriasis is a chronic, autoimmune skin disease affecting approximately 2% of the world's population. Clobetasol propionate which is a superpotent topical corticosteroid is widely used for topical treatment of psoriasis. Conventional dosage forms like creams and ointments are commonly prefered for the therapy. The purpose of this study was to develop a new topical delivery system in order to provide the prolonged release of clobetasol propionate and to reduce systemic absorption and side effects of the drug. Clobetasol propionate loaded-poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres were prepared by oil-in-water emulsion-solvent evaporation technique. Particle size analysis, morphological characterization, DSC and XRD analyses and in vitro drug release studies were performed on the microparticle formulations. Emulgel formulations were prepared as an alternative for topical delivery of clobetasol propionate. In vitro drug release studies were carried out from the emulgel formulations containing pure drug and drug-loaded microspheres. In addition, the same studies were performed to determine the drug release from the commercial cream product of clobetasol propionate. The release of clobetasol propionate from the emulgel formulations was significantly higher than the commercial product. In addition, the encapsulation of clobetasol propionate in the PLGA microspheres significantly delayed the drug release from the emulgel formulation. As a result, the decrease in the side effects of clobetasol propionate by the formulation containing PLGA microspheres is expected. PMID:21748539

Bad?ll?, Ulya; Sen, Tangül; Tar?mc?, Nilüfer

2011-09-01

151

Effect of Propionic Acid in the Germination of Rice Genotypes  

Microsoft Academic Search

The objective of this work was to evaluate the germination of 12 rice genotypes under propionic acid stress, a phytotoxic com- pound produced in low drainage soils with high organic matter content. The tests were conducted with the first count of germination (PCG) and germination (G) of the genotypes subjected to 0, 3, 6, and 9 mM propionic acid concentrations.

Mauricio Marini Kopp; Viviane Kopp da Luz; Luciano Carlos da Mai; Rogério Oliveira de Sous; Antonio Costa de Oliveira

152

Cellulose Insulation  

NASA Technical Reports Server (NTRS)

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

1980-01-01

153

Purification of aqueous cellulose ethers  

SciTech Connect

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

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

1990-07-01

154

Thermoanaerobacteriaceae oxidize acetate in methanogenic rice field soil at 50Cemi_2289 2341..2354  

E-print Network

oxidized. Part of the 13 C-labelled acetate was also converted to propionate which con- tained up to 14% 13 and 171 bp length predominated. Cloning and sequencing of 16S rRNA showed that these T-RFs were affiliated

Lovley, Derek

155

DESOXYCORTICOSTERONE ACETATE  

PubMed Central

1. Desoxycorticosterone acetate (DCA) and NaCl, in the dosage employed in normal rats, caused renal and cardiac hypertrophy, characteristic changes in the renal tubular epithelium, atrophic changes in the subcapsular zone of the adrenal cortex, and serum electrolyte changes characterized by a rise in sodium and fall in potassium. 2. In rats rendered nephritic with a rabbit anti-rat-kidney serum, the same regimen caused similar changes. In addition, DCA given concurrently with NaCl greatly intensified the nephritic process and gave rise to striking arterial hypertension. 3. A diet, virtually sodium-free, administered to normal and nephritic rats receiving daily injections of DCA abolished or reduced to a minimum the effects of this steroid; i.e., a liberal ingestion of NaCl was essential for the potentiation of the action of DCA. 4. The addition of KCl to the drinking water of rats receiving DCA and NaCl tended to correct the depression of the level of potassium in the serum, but had no effect upon the hypertension in nephritic animals nor upon the anatomical lesions. 5. The mechanism by which the sodium ion potentiates the activity of DCA has not been established. PMID:19871607

Knowlton, Abbie I.; Loeb, Emily N.; Stoerk, Herbert C.; Seegal, Beatrice C.

1947-01-01

156

Synthesis and pharmacological evaluation of carvacrol propionate.  

PubMed

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

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

2014-10-01

157

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

PubMed

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

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

2014-03-01

158

Utilization of biocatalysts in cellulose waste minimization  

SciTech Connect

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

Woodward, J.; Evans, B.R.

1996-09-01

159

CCMR: Cellulose Fiber Spinning  

NSDL National Science Digital Library

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

Carranco, Kristen

2004-08-17

160

Comparative study of crude and purified cellulose from wheat straw.  

PubMed

A sequential totally chlorine-free procedure for isolation of cellulose from wheat straw was proposed in this study. The dewaxed straw was pretreated with 0.5 M NaOH in 60% methanol at 60 degrees C for 2.5 h under ultrasonic irradiation for 0-35 min and sequentially posttreated with 2% H(2)O(2)-0.2% TAED at pH 11.8 for 12 h at 48 degrees C, which together solubilized 85.3-86.1% of the original hemicelluloses and 91.7-93.2% of the original lignin, respectively. The yield of crude cellulose ranged between 46.2 and 49.2% on a dry weight basis related to wheat straw, which contained 11.2-12.2% residual hemicelluloses and 2.5-2.9% remaining lignin. Further treatment of the corresponding crude cellulosic preparations with 80% acetic acid-70% nitric acid under the condition given yielded 36.8-37.7% of the purified cellulose, which contained minor amounts of bound hemicelluloses (2.5-2.8%) and was relatively free of associated lignin (0.1-0.2%). The isolated crude and purified cellulose samples were comparatively studied by FT-IR and CP/MAS (13)C NMR spectroscopy, and the relative crystallinity was also estimated. The final stage treatment with 80% acetic acid-70% nitric acid decreased the hemicelluloses and lignin associated in the crude cellulose but led to 3.1-5.4% degradation of the original cellulose; in addition, the purity of the obtained cellulose was high. However, it was found that the final stage treatment is not severe enough to cause decrystallization of cellulose. The thermal stability of the purified cellulose is higher than that of the corresponding crude cellulose. PMID:14969539

Sun, Xiao-Feng; Sun, Run-Cang; Su, Yinquan; Sun, Jing-Xia

2004-02-25

161

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

SciTech Connect

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, CO/sub 2/, H/sub 2/, and methane) are summarized. (ACR)

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

1980-01-01

162

Sulfate Reducing Rate of SRB with Acetic, Propionic, n-Butyric Acids as Carbon Sources  

Microsoft Academic Search

The aim of this work was to determine the kind of short-chain volatile fatty acid, which is apt to be used by sulfate reducing bacteria (SRB). SRB was feed with culture media used sodium lactate as carbon source. Sulfate reducing rate and different short-chain volatile fatty acids (VFA) utilization rate with SRB were studied. Sulfate variation curves were drawn and

Xiulan Song; Zhimin Zhang

2011-01-01

163

Electrophysiological effects of propionate and bicarbonate on gallbladder epithelium.  

PubMed

The effects of propionate and HCO3- on cell membrane potentials in Necturus gallbladder epithelium were investigated using microelectrode techniques in vitro. Bilateral exposure to either propionate or HCO3- (25 mM each) hyperpolarized both cell membranes by about 12 mV. Mucosal addition of either substance produced cyclic changes in voltage of both cell membranes, which attenuated spontaneously, whereas serosal addition caused sustained hyperpolarization. By intraepithelial cable analysis it was shown that both cell membrane conductances rose during the hyperpolarization. Experiments using substitution of mucosal K+ for Na+ revealed that the relative K+ permeability (PK) of the apical membrane was enhanced during the hyperpolarization induced by mucosal (or serosal) propionate (or HCO3-). These effects are mediated by increases in PK at both membranes, with a larger basolateral effect. We suggest that this mechanism accounts for the higher cell membrane potential values measured in epithelia bathed in HCO3--or propionate-containing solutions. Inasmuch as both propionate and HCO3- stimulate fluid absorption in gallbladder epithelium, the increase in cell membrane PK may represent an adaptive response of the cells to regulate their solute content. PMID:2981476

Petersen, K U; Reuss, L

1985-01-01

164

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

PubMed Central

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

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

2010-01-01

165

Preparation and characterization of sodium caseinate films reinforced with cellulose derivatives  

Microsoft Academic Search

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

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

2011-01-01

166

Structure and mechanical properties of cellulose based scaffolds fabricated by selective laser sintering  

Microsoft Academic Search

This work presents the rapid fabrication of starch–cellulose and cellulose acetate scaffolds by selective laser sintering and the evaluation of the laser power, laser scan speed and the polymer particle size influence on the scaffold properties. The specimens were prepared using two different particle sizes and characterized by density measurements, scanning electronic microscopy (SEM) and a flexural test. The fine

Gean V. Salmoria; Priscila Klauss; Rodrigo A. Paggi; Luiz A. Kanis; Alexandre Lago

2009-01-01

167

Fluticasone propionate in asthma: a long term dose comparison study  

PubMed Central

Background: Few dose ranging studies have investigated optimal dosing with inhaled corticosteroids in children with asthma. Aims: To compare the efficacy and tolerability of fluticasone propionate 100 or 200 µg twice daily in children with moderate to severe asthma for one year. Methods: One year, randomised, double blind, parallel group, multicentre study. Children aged 4–11 years (n = 528) with moderate to severe asthma who had previously received high dose inhaled corticosteroids were given fluticasone propionate 100 or 200 µg twice daily for the 52 week treatment period. Efficacy (exacerbations, lung function, and symptoms) and tolerability (adverse events and cortisol levels) were measured. Results: There was a non-significant decreased risk of experiencing an exacerbation at any time with fluticasone propionate 200 µg twice daily compared with fluticasone propionate 100 µg twice daily. This difference reached significance among patients with more severe asthma (defined by previous inhaled corticosteroid dose >800 µg/day). Daily record card morning peak expiratory flow (PEF) in the total population improved significantly more with the higher dose of fluticasone propionate (between group difference, weeks 1–52: 11.4 l/min). Clinic visit mean PEF improved from baseline with both doses, but the response was significantly greater with the higher dose (between group difference, week 52: 17.8 l/min). Both doses were equally well tolerated and overnight urinary cortisol concentrations were unchanged or slightly increased during treatment with either dose. Conclusion: This long term dose comparison study shows that treatment with fluticasone propionate 200 µg twice daily may offer benefits over a lower dose, particularly in children with more severe asthma. PMID:12765916

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

2003-01-01

168

Highly efficient propionylation and butyralation of cellulose in an ionic liquid catalyzed by 4-dimethylminopyridine.  

PubMed

Using 4-dimethylaminopyridine (DMAP) as the catalyst, highly efficient propionylation and butyralation of cellulose were successfully carried out in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) under mild conditions. Cellulose propionate (CP) and cellulose butyrate (CB) with a degree of substitution (DS) in the range from 0.89 to 2.89 were synthesized within only 30 min at 30 °C. The DS values of the products could be well controlled just by molar ratio of acid anhydride/anhydroglucose unit (AGU). More interestingly, the conversions of acid anhydrides in both propionylation and butyralation were as high as above 90%, even 96%. Therefore, this work provides a facile and highly efficient way for the synthesis of cellulose esters CP and CB. PMID:23218299

Luan, Yihao; Zhang, Jinming; Zhan, Maosheng; Wu, Jin; Zhang, Jun; He, Jiasong

2013-01-30

169

Pea Xyloglucan and Cellulose  

PubMed Central

Since xyloglucan is believed to bind to cellulose microfibrils in the primary cell walls of higher plants and, when isolated from the walls, can also bind to cellulose in vitro, the binding mechanism of xyloglucan to cellulose was further investigated using radioiodinated pea xyloglucan. A time course for the binding showed that the radioiodinated xyloglucan continued to be bound for at least 4 hours at 40°C. Binding was inhibited above pH 6. Binding capacity was shown to vary for celluloses of different origin and was directly related to the relative surface area of the microfibrils. The binding of xyloglucan to cellulose was very specific and was not affected by the presence of a 10-fold excess of (1?2)-?-glucan, (1?3)-?-glucan, (1?6)-?-glucan, (1?3, 1?4)-?-glucan, arabinogalactan, or pectin. When xyloglucan (0.1%) was added to a cellulose-forming culture of Acetobacter xylinum, cellulose ribbon structure was partially disrupted indicating an association of xyloglucan with cellulose at the time of synthesis. Such a result suggests that the small size of primary wall microfibrils in higher plants may well be due to the binding of xyloglucan to cellulose during synthesis which prevents fasciation of small fibrils into larger bundles. Fluorescent xyloglucan was used to stain pea cell wall ghosts prepared to contain only the native xyloglucan:cellulose network or only cellulose. Ghosts containing only cellulose showed strong fluorescence when prepared before or after elongation; as predicted, the presence of native xyloglucan in the ghosts repressed binding of added fluorescent xyloglucan. Such ghosts, prepared after elongation when the ratio of native xyloglucan:cellulose is substantially reduced, still showed only faint fluorescence, indicating that microfibrils continue to be coated with xyloglucan throughout the growth period. Images Fig. 5 Fig. 6 PMID:16665254

Hayashi, Takahisa; Marsden, Margery P. F.; Delmer, Deborah P.

1987-01-01

170

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

PubMed Central

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

2012-01-01

171

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

172

Cellulose Biosynthesis in Enterobacteriaceae  

Microsoft Academic Search

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

Ute Römling

173

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

Microsoft Academic Search

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

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

2006-01-01

174

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

PubMed

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

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

2013-11-14

175

Cellulose gels produced in room temperature ionic liquids by ionizing radiation  

NASA Astrophysics Data System (ADS)

Cellulose-based gels were produced in room temperature ionic liquids (RTILs) by ionizing radiation. Cellulose was dissolved at the initial concentration of 20 wt% in 1-ethyl-3-methylimidazolium (EMI)-acetate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEMA)-formate with a water content of 18 wt%, and irradiated with ?-rays under aerated condition to produce new cellulose gels. The gel fractions of the cellulose gels obtained in EMI-acetate and DEMA-formate at a dose of 10 kGy were 13% and 19%, respectively. The formation of gel fractions was found to depend on the initial concentration of cellulose, water content, and irradiation temperature. The obtained gel readily absorbed water, methanol, ethanol, dichloromethane, N,N-dimethylacetamide, and RTILs.

Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa

2014-10-01

176

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

E-print Network

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

Vidya S

2014-01-01

177

Regenerating cellulose from ionic liquids for an accelerated enzymatic hydrolysis  

SciTech Connect

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

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

2009-01-01

178

Surface esterification of cellulose nanofibers by a simple organocatalytic methodology.  

PubMed

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

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

2014-12-19

179

Cellulose binding domain proteins  

DOEpatents

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

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

1998-11-17

180

Cellulose binding domain proteins  

DOEpatents

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

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

1998-01-01

181

Regulation and Evolution of Malonate and Propionate Catabolism in Proteobacteria  

PubMed Central

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

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

2012-01-01

182

Use of cellulose-based carbon aerogels as catalyst support for PEM fuel cell electrodes: Electrochemical characterization  

Microsoft Academic Search

New nanostructured carbons have been developed through pyrolysis of organic aerogels, based on supercritical drying of cellulose acetate gels. These cellulose acetate-based carbon aerogels (CA) are activated by CO2 at 800°C and impregnated by PtCl62?; the platinum salt is then chemically or electrochemically reduced. The resulting platinized carbon aerogels (Pt\\/CA) are characterized with transmission electron microscopy (TEM) and electrochemistry. The

Elodie Guilminot; Florent Fischer; Marian Chatenet; Arnaud Rigacci; Sandrine Berthon-Fabry; Patrick Achard; Eric Chainet

2007-01-01

183

Pharmaceutical properties of fluticasone propionate nasal drops: a new formulation.  

PubMed

A variety of corticosteroid delivery systems have been considered for the treatment of nasal polyposis. Safety considerations favour local delivery of the drug to the nasal cavity. No topical delivery system is entirely without problems, however, and formulations must address issues of microbiological quality, drug stability, reproducible drug delivery and adequate drug distribution at site, while also offering environmental and patient acceptability. Fluticasone propionate has been formulated in a new nasal drop preparation. As a highly water-insoluble compound, the active fluticasone propionate requires micronization to an optimal particle size and subsequent dispersion with a surface-active wetting agent. The product is presented in a unit dose low-density polyethylene container, manufactured by a blow-fill-seal process and stored in an aluminium foil overwrap. Micronized active has been used to promote optimal local drug delivery, and excipients have been selected for low irritancy potential and high formulation stability. There is no microbiological risk with fluticasone propionate unit dose nasal drops 400 microg and therefore no need to include a preservative in the preparation. They provide a convenient and effective treatment option for patients with nasal polyposis. PMID:10442546

Denyer, S

1999-01-01

184

The effect of testosterone propionate on growth of broiler chickens.  

PubMed

The effects of testosterone propionate (TP) on body weight, tissue percentages of body weight, serum IgM, and rectal temperature (2 h postinjection) of male and female broiler chickens were investigated at 28 and 48 days posthatching. Testosterone propionate was dissolved in sesame oil and was injected at 2 mg/kg of body weight every other day, and controls were treated with sesame oil at similar volume, starting Day 7 posthatching. Administration of TP reduced (P < .05) body weight and percentages of liver, testes, and bursa of Fabricius at 28 and 48 days of age. At 28 and 48 days of age, muscle percentage and comb growth of TP-treated birds increased (P < .05) but ovarian weight was unaffected. Concentrations of IgM in serum of TP-injected birds was unchanged at Day 28, but increased (P < .05) at Day 48. Testosterone propionate did not affect percentages of bone or abdominal fat in either sex. Rectal temperature was depressed (P < .05) by TP treatment in both sexes at both ages. PMID:1437979

Deyhim, F; Moreng, R E; Kienholz, E W

1992-11-01

185

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

Microsoft Academic Search

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

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

2010-01-01

186

Pyrolytic sugars from cellulosic biomass  

NASA Astrophysics Data System (ADS)

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

Kuzhiyil, Najeeb

187

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

188

Rapid determination of cellulose.  

PubMed

The cellulose analysis results of four feedstocks and Avicel obtained by a one-step/two-step hydrolysis method were compared to the conventional cellulose assay according to Updegraff. Slightly lower cellulose levels were observed for Avicel (97%), corn stover (97%), poplar (96%), and Miscanthus (94%) but for pine the amounts were almost identical (101%). Despite these differences, the one-step/two-step method can be seen as a true alternative to the more labor-intensive Updegraff method. Biotechnol. Bioeng. 2014;111: 2355-2357. © 2014 Wiley Periodicals, Inc. PMID:24909906

Bauer, Stefan; Ibáñez, Ana B

2014-11-01

189

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

PubMed Central

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

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

2014-01-01

190

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

PubMed

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

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

2014-01-01

191

Improved biological phosphorus removal performance driven by the aerobic/extended-idle regime with propionate as the sole carbon source.  

PubMed

Our previous studies proved that biological phosphorus removal (BPR) could be achieved in an aerobic/extended-idle (AEI) process employing two typical substrates of glucose and acetate as the carbon sources. This paper further evaluated the feasibility of another important substrate, propionate, serving as the carbon source for BPR in the AEI process, and compared the BPR performance between the AEI and anaerobic/oxic (A/O) processes. Two sequencing batch reactors (SBRs) were operated, respectively, as the AEI and A/O regimes for BPR using propionate as the sole substrate. The results showed that the AEI-reactor removed 2.98 ± 0.04-4.06 ± 0.06 mg of phosphorus per g of total suspended solids during the course of the steady operational trial, and the phosphorus content of the dried sludge was reached 8.0 ± 0.4% after 56-day operation, demonstrating the good performance of phosphorus removal. Then, the efficiencies of BPR and the transformations of the intracellular storages were compared between two SBRs. It was observed that the phosphorus removal efficiency was maintained around 95% in the AEI-reactor, and about 83% in the A/O-reactor, although the latter showed much greater transformations of both polyhydroxyalkanoates and glycogen. The facts clearly showed that BPR could be enhanced by the AEI regime using propionate as the carbon source. Finally, the mechanisms for the propionate fed AEI-reactor improving BPR were investigated. It was found that the sludge cultured by the AEI regime had more polyphosphate containing cells than that by the A/O regime. Further investigation revealed that the residual nitrate generated in the last aerobic period was readily deteriorated BPR in the A/O-SBR, but a slight deterioration was observed in the AEI-SBR. Moreover, the lower glycogen transformation measured in the AEI-SBR indicated that the biomass cultured by the AEI regime contained less glycogen accumulating organisms activities than that by the A/O regime. PMID:22609408

Wang, Dongbo; Li, Xiaoming; Yang, Qi; Zheng, Wei; Wu, Yan; Zeng, Tianjing; Zeng, Guangming

2012-08-01

192

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

193

Method of saccharifying cellulose  

DOEpatents

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

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

1985-09-10

194

Proton magnetic resonance studies of the chemical shifts occurring in propionic acid-dioxane solutions  

E-print Network

LIB' OF FIQUHRB PIGUBRB 1, Observers ohemi, cal shiftsoccurring in aqueous solutions of propiolLic acid o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 23 2 ~ Chemical shifts occurring in propionic acyl-diarane solull iona... ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ 35 LIET OF TABES TAEIR6 l, Chemical shiftsoccurring in aqueous solutions of propionic PAGE ac id ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 21 2, Chemical shifts occurring in propionic ac1d-dioxane solut1ons 22 3. C...

Oldham, William J. Bryan

2012-06-07

195

Investigation of the fumarate metabolism of the syntrophic propionate-oxidizing bacterium strain MPOB  

Microsoft Academic Search

The growth of the syntrophic propionate-oxidizing bacterium strain MPOB in pure culture by fumarate disproportionation into\\u000a carbon dioxide and succinate and by fumarate reduction with propionate, formate or hydrogen as electron donor was studied.\\u000a The highest growth yield, 12.2 g dry cells\\/mol fumarate, was observed for growth by fumarate disproportionation. In the presence\\u000a of hydrogen, formate or propionate, the growth

Bernardina L. M. Van Kuijk; Elvire Schlösser; Alfons J. M. Stams

1998-01-01

196

Agglomerate behaviour of fluticasone propionate within dry powder inhaler formulations.  

PubMed

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

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

2012-04-01

197

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

PubMed

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

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

2011-12-01

198

The Acetate Switch  

PubMed Central

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

Wolfe, Alan J.

2005-01-01

199

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

200

Survey of health status and complications among propionic acidemia patients.  

PubMed

Propionic acidemia (PA) is a rare organic acidemia that is due to deficiency in the enzyme propionyl-coA carboxylase. Complications are currently described mostly in the form of case reports. We sampled a population of affected individuals in order to estimate the frequency of complications amongst the sample. The study is a cross-sectional retrospective review with a survey instrument and recruitment through the Propionic Acidemia Foundation. Responses for 58 individuals were tabulated for each question as how frequently the complication was reported among responders. Commonly reported findings included seizures, arrhythmia, leucopenia, and anemia. Developmental and cognitive disabilities were reported in the majority of individuals. Heart failure or cardiomyopathy was reported in over half of deceased individuals at time of death. Pancreatitis was reported in a minority of the sample, yet more than half of these reported a recurrence. These results update and extend our current knowledge of recognized complications among individuals with PA. The results also provide new information regarding developmental outcomes and previously unreported morbidity from cardiac and gastrointestinal complications. Longitudinal studies exploring associated biochemical and clinical parameters are necessary to further our understanding of the pathophysiology of PA and its complications. PMID:22678880

Pena, Loren; Burton, Barbara K

2012-07-01

201

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

202

Non-Crystalline Cellulose and Production Thereof.  

National Technical Information Service (NTIS)

A non crystalline or low crystallinity cellulose. A method of making a non crystalline or low crystallinity cellulose comprising providing cellulosic material, adding an effective acid in an amount effective to at least wet the cellulosic material, mixing...

H. M. Harraz, Y. Y. Lee

2005-01-01

203

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

204

Cellulose pyrolysis kinetics: Revisited  

SciTech Connect

In the same thermogravimetric analyzer (TGA) under identical conditions, samples of pure, ash-free cellulose (i.e., Avicel PH-105, Whatman CF-11, Millipore ash-free filter pulp, and Whatman No. 42) obtained from different manufacturers undergo pyrolysis at temperatures which differ by as much as 30 C. Thus, the pyrolysis chemistry of a sample of pure cellulose is not governed by a universal rate law, as is the case with a pure hydrocarbon gas (for example). Nevertheless, the pyrolytic weight loss of all the samples studied in this work is well represented by a high activation energy (228 kJ/mol), first-order rate law at both low and high heating rates. These results do not corroborate the recent findings of Milosavljevic and Suuberg. For a particular cellulose sample (for example, Avicel PH-105), variations in the preexponential constant determined at different heating rates reflect uncontrolled, systematic errors in the dynamic sample temperature measurement (thermal lag).

Antal, M.J. Jr. [Univ. of Hawaii, Honolulu, HI (United States)] [Univ. of Hawaii, Honolulu, HI (United States); Varhegyi, G.; Jakab, E. [Hungarian Academy of Sciences, Budapest (Hungary). Research Lab. for Materials and Environmental Chemistry] [Hungarian Academy of Sciences, Budapest (Hungary). Research Lab. for Materials and Environmental Chemistry

1998-04-01

205

Acid hydrolysis of cellulose  

SciTech Connect

One of the alternatives to increase world production of etha nol is by the hydrolysis of cellulose content of agricultural residues. Studies have been made on the types of hydrolysis: enzimatic and acid. Data obtained from the sulphuric acid hydrolysis of cellulose showed that this process proceed in two steps, with a yield of approximately 95% glucose. Because of increases in cost of alternatives resources, the high demand of the product and the more economic production of ethanol from cellulose materials, it is certain that this technology will be implemented in the future. At the same time further studies on the disposal and reuse of the by-products of this production must be undertaken.

Salazar, H.

1980-12-01

206

Salmeterol and Fluticasone Propionate and Survival in Chronic Obstructive Pulmonary Disease  

Microsoft Academic Search

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

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

2007-01-01

207

Propionate induces cell swelling and K+ accumulation in shark rectal gland  

SciTech Connect

Small organic anions have been reported to induce cell solute accumulation and swelling. To investigate the mechanism of swelling, we utilized preparations of rectal gland cells from Squalus acanthias incubated in medium containing propionate. Propionate causes cells to swell by diffusing across membranes in its nonionic form, acidifying cell contents, and activating the Na+-H+ antiporter. The Na+-H+ exchange process tends to correct intracellular pH (pHi), and thus it maintains a favorable gradient for propionic acid diffusion and allows propionate to accumulate. Activation of the Na+-H+ antiport also facilitates Na+ entry into the cell and Nai accumulation. At the same time Na+-K+-ATPase activity, unaffected by propionate, replaces Nai with Ki, whereas the K+ leak rate, decreased by propionate, allows Ki to accumulate. As judged by {sup 86}Rb+ efflux, the reduction in K+ leak was not due to propionate-induced cell acidification or reduction in Cli concentration. Despite inducing cell swelling, propionate did not disrupt cell structural elements and F actin distribution along cell membranes.

Feldman, G.M.; Ziyadeh, F.N.; Mills, J.W.; Booz, G.W.; Kleinzeller, A. (Mount Desert Island Biological Laboratory, Salsbury Cove, ME (USA))

1989-08-01

208

Syntrophic propionate degradation response to temperature decrease and microbial community shift in an UASB reactor.  

PubMed

Propionate is an important intermediate product during the methane fermentation of organic matter, and its degradation is crucial for maintaining the performance of an anaerobic digester. In order to understand the effect of temperature on propionate degradation, an upflow anaerobic sludge blanket (UASB) reactor with synthetic wastewater containing propionate as a sole carbon source was introduced. Under the hydraulic retention time (HRT) of 10 h and influent propionate of 2,000 mg/l condition, propionate removal was above 94% at 30-35°C, whereas propionate conversion was inhibited when temperature was suddenly decreased stepwise from 30°C to 25°C, to 20°C, and then to 18°C. After a long-term operation, the propionate removal at 25°C resumed to the value at 30- 35°C, whereas that at 20°C and 18°C was still lower than the value at 35°C by 8.1% and 20.7%, respectively. Microbial community composition analysis showed that Syntrophobacter and Pelotomaculum were the major propionate-oxidizing bacteria (POB), and most POB had not changed with temperature decrease in the UASB. However, two POB were enriched at 18°C, indicating they were low temperature tolerant. Methanosaeta and Methanospirillum were the dominant methanogens in this UASB and remained constant during temperature decrease. Although the POB and methanogenic composition hardly changed with temperature decrease, the specific CODPro removal rate of anaerobic sludge (SCRR) was reduced by 21.4%-46.4% compared with the control (35°C) in this system. PMID:23462012

Ban, Qiaoying; Li, Jianzheng; Zhang, Liguo; Jha, Ajay Kumar; Zhang, Yupeng; Ai, Binling

2013-03-01

209

[Double-blind-study on treatment with clobetasol-17-propionate and other topical corticoids (author's transl)].  

PubMed

90 patients suffering from chronic skin diseases-mainly psoriasis vulgaris-were treated in a double-blind-study for two weeks with topical Clobetasol-17-propionate compared with other topical corticoids. In 81% was seen a better therapeutical effect on the Clobetasol-17-propionate treated skin area. PMID:7027655

Beck, M; Berger, C; Filipp, N; Hundertmark, U; Loewel, R

1981-08-15

210

Metabolic engineering of Propionibacterium freudenreichii: effect of expressing phosphoenolpyruvate carboxylase on propionic acid production.  

PubMed

Propionic acid is currently produced mainly via petrochemicals, but there is increasing interest in its fermentative production from renewable biomass. However, the current propionic acid fermentation process suffers from low product yield and productivity. In this work, the gene encoding phosphoenolpyruvate carboxylase (PPC) was cloned from Escherichia coli and expressed in Propionibacterium freudenreichii. PPC catalyzes the conversion of phosphoenolpyruvate to oxaloacetate with the fixation of one CO2. Its expression in P. freudenreichii showed profound effects on propionic acid fermentation. Compared to the wild type, the mutant expressing the ppc gene grew significantly faster, consumed more glycerol, and produced propionate to a higher final titer at a faster rate. The mutant also produced significantly more propionate from glucose under elevated CO2 partial pressure. These effects could be attributed to increased CO2 fixation and resulting changes in the flux distributions in the dicarboxylic acid pathway. PMID:24878752

Ammar, Ehab Mohamed; Jin, Ying; Wang, Zhongqiang; Yang, Shang-Tian

2014-09-01

211

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

PubMed

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

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

2012-07-01

212

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

213

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

214

Genetics of propionic acidemia in a Mennonite-Amish kindred.  

PubMed Central

A large Mennonite kindred was found to have propionic acidemia (complementation group pcc C) in at least four different sibships. Even within this kindred and this complementation group (where etiology may be assumed to be identical), there is a wide range of symptoms exhibited by homozygous pcc C-deficient individuals. The inbreeding coefficients (f) for the affected sibships ranged from 4.776 X 10(3) to 2.003 X 10(-2). Data from this study strongly support the single-locus autosomal recessive mode of inheritance. Three couples were found to be common in the ancestry (9--11 generations ago) of all eight parents of the four affected sibships. Relative likelihoods for a member of each of those couples to have been the early carrier of the defective allele were calculated at 1539, 278, and 1. Thus, one couple was designated the most likely earliest-known transmitter of the pcc-deficient allele. PMID:7386459

Kidd, J R; Wolf, B; Hsia, E; Kidd, K K

1980-01-01

215

Acceleration of gluconeogenesis from propionate by dl-carnitine in the rat kidney cortex  

PubMed Central

1. The rate of gluconeogenesis from propionate in rat kidney-cortex slices was stimulated up to 3·5-fold by dl-carnitine and by bicarbonate, and was inhibited by inorganic phosphate or high concentrations of propionate (above 3mm). 2. The stimulatory effect of carnitine was dependent on the bicarbonate concentration and could be replaced at low propionate concentration by addition of 25mm-bicarbonate–carbon dioxide buffer. At low bicarbonate concentration the carnitine concentration can be rate-limiting. 3. All observations are in accordance with the view that the action of carnitine is in principle the same as that established for other fatty acids in other tissues, namely that carnitine promotes the appearance of propionyl-CoA within the mitochondrion by acting as a carrier. 4. The accelerating effects of carnitine and bicarbonate and the inhibitory effect of phosphate can be explained on the basis of the known properties of key enzymes of propionate metabolism, i.e. the reversibility of the reactions leading to the formation of methylmalonyl-CoA from propionyl-CoA. 5. 5mm-Propionate caused a five- to ten-fold fall in the free CoA content of the tissue. This fall can account for the inhibition of respiration and gluconeogenesis caused by high propionate concentration. 6. Relatively large quantities of propionyl-l-carnitine (15% of the propionate removed) were formed when dl-carnitine was present; thus the `activation' of propionate proceeded at a faster rate than the carboxylation of propionyl-CoA. The metabolism of added propionyl-l-carnitine was accompanied by glucose synthesis. 7. The appearance of radioactivity from [2-14C]propionate in both glucose and carbon dioxide was as expected on account of the randomization of C-2 and C-3 of propionate, i.e. the formation of succinate as an intermediate. 8. The maximum rate of glucose synthesis from propionate (93·3±3·3?moles/g. dry wt./hr.) was not affected by dietary changes aimed at varying the rate of caecal volatile fatty acid formation in the rat. 9. Inhibition of gluconeogenesis by high propionate concentration was not found in those species where the rate of caecal or ruminal propionate production is high under normal conditions (rabbit, sheep and cow). PMID:4887195

Weidemann, M. J.; Krebs, H. A.

1969-01-01

216

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

217

Cellulose Synthesis and Its Regulation  

PubMed Central

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

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

2014-01-01

218

Characterization of propionate CoA-transferase from Ralstonia eutropha H16.  

PubMed

In this study, a propionate CoA-transferase (H16_A2718; EC 2.8.3.1) from Ralstonia eutropha H16 (Pct(Re)) was characterized in detail. Glu342 was identified as catalytically active amino acid residue via site-directed mutagenesis. Activity of Pct(Re) was irreversibly lost after the treatment with NaBH? in the presence of acetyl-CoA as it is shown for all CoA-transferases from class I, thereby confirming the formation of the covalent enzyme-CoA intermediate by Pct(Re). In addition to already known CoA acceptors for Pct Re such as 3-hydroxypropionate, 3-hydroxybutyrate, acrylate, succinate, lactate, butyrate, crotonate and 4-hydroxybutyrate, it was found that glycolate, chloropropionate, acetoacetate, valerate, trans-2,3-pentenoate, isovalerate, hexanoate, octanoate and trans-2,3-octenoate formed also corresponding CoA-thioesters after incubation with acetyl-CoA and Pct(Re). Isobutyrate was found to be preferentially used as CoA acceptor amongst other carboxylates tested in this study. In contrast, no products were detected with acetyl-CoA and formiate, bromopropionate, glycine, pyruvate, 2-hydroxybutyrate, malonate, fumarate, itaconate, ?-alanine, ?-aminobutyrate, levulate, glutarate or adipate as potential CoA acceptor. Amongst CoA donors, butyryl-CoA, crotonyl-CoA, 3-hydroxybutyryl-CoA, isobutyryl-CoA, succinyl-CoA and valeryl-CoA apart from already known propionyl-CoA and acetyl-CoA could also donate CoA to acetate. The highest rate of the reaction was observed with 3-hydroxybutyryl-CoA (2.5 ?mol mg?¹ min?¹). K(m) values for propionyl-CoA, acetyl-CoA, acetate and 3-hydroxybutyrate were 0.3, 0.6, 4.5 and 4.3 mM, respectively. The rather broad substrate range might be a good starting point for enzyme engineering approaches and for the application of Pct(Re) in biotechnological polyester production. PMID:24057402

Volodina, Elena; Schürmann, Marc; Lindenkamp, Nicole; Steinbüchel, Alexander

2014-04-01

219

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

PubMed Central

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

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

1995-01-01

220

Acidbase interaction in the acetic acid-acetic anhydride system  

Microsoft Academic Search

1.The electroconductivity and dielectric permeability of the acetic acid-acetic anhydride system have been measured. The electroconductivity of the system has a maximum close to 50% of the anhydride. The curve of the dielectric permeability is concave toward the composition axis.2.The dependence of the electroconductivity on the composition is explained by the formation of a complex between acetic acid and acetic

V. E. Bel'skii; M. I. Vinnik

1963-01-01

221

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

222

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

223

Antioxidants successfully reduce ROS production in propionic acidemia fibroblasts.  

PubMed

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

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

2014-09-26

224

Reinforcement of bacterial cellulose aerogels with biocompatible polymers  

PubMed Central

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 77 K 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.

2014-01-01

225

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

Microsoft Academic Search

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

Kanokwan Boe; Irini Angelidaki; Jean-Philippe Steyer

2008-01-01

226

Propionate lowers blood glucose and alters lipid metabolism in healthy subjects13  

Microsoft Academic Search

Incorporation of 3.3 g sodium propionate per 50 g available carbohydrate portion of bread reduced acutely the blood glucose response area in six healthy volunteers by 47.6 ± 12.4% (P < 0.02). Similarly, in vitro digestibility was reduced by 47.4 ± 1. 1% (P < 0.01). One week ofdietary supplementation with 9.9 g sodium propionate in bread\\/d reduced the blood

Tiziana Todesco; A Venketshwer Rao; Ottavio Bose; David JA Jenkins

227

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. PMID:16391084

Nakano, Shigeru; Fukaya, Masahiro; Horinouchi, Sueharu

2006-01-01

228

Short-term effect of acetate and ethanol on methane formation in biogas sludge.  

PubMed

Biochemical processes in biogas plants are still not fully understood. Especially, the identification of possible bottlenecks in the complex fermentation processes during biogas production might provide potential to increase the performance of biogas plants. To shed light on the question which group of organism constitutes the limiting factor in the anaerobic breakdown of organic material, biogas sludge from different mesophilic biogas plants was examined under various conditions. Therefore, biogas sludge was incubated and analyzed in anaerobic serum flasks under an atmosphere of N2/CO2. The batch reactors mirrored the conditions and the performance of the full-scale biogas plants and were suitable test systems for a period of 24 h. Methane production rates were compared after supplementation with substrates for syntrophic bacteria, such as butyrate, propionate, or ethanol, as well as with acetate and H2+CO2 as substrates for methanogenic archaea. Methane formation rates increased significantly by 35 to 126 % when sludge from different biogas plants was supplemented with acetate or ethanol. The stability of important process parameters such as concentration of volatile fatty acids and pH indicate that ethanol and acetate increase biogas formation without affecting normally occurring fermentation processes. In contrast to ethanol or acetate, other fermentation products such as propionate, butyrate, or H2 did not result in increased methane formation rates. These results provide evidence that aceticlastic methanogenesis and ethanol-oxidizing syntrophic bacteria are not the limiting factor during biogas formation, respectively, and that biogas plant optimization is possible with special focus on methanogenesis from acetate. PMID:24903810

Refai, Sarah; Wassmann, Kati; Deppenmeier, Uwe

2014-08-01

229

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

230

Cellulose binding domain fusion proteins  

DOEpatents

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

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

1998-02-17

231

Cellulose binding domain fusion proteins  

DOEpatents

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

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

1998-01-01

232

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

233

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

234

Interaction of propionate and carnitine metabolism in isolated rat hepatocytes  

SciTech Connect

Propionate (P) and its metabolic products P-CoA and methylmalonyl-CoA can disrupt normal hepatic metabolism. Carnitine (Cn) has been shown to partially restore cellular function in the presence of P. This effect of Cn may result from removal of propionyl groups as propionylcarnitine (P-Cn). The present study examined the kinetics of P-Cn formation in rat hepatocytes, and the consequence of P-Cn formation on P and Cn metabolism. /sup 14/C-P was converted to CO/sub 2/, glucose and P-Cn in the hepatocyte system. Increasing concentrations of Cn up to 10.0 mM increased P-Cn formation from P without affecting CO/sub 2/ or glucose formation. Thus, 10.0 mM Cn increased total P metabolism by 40%. Metabolism of P was associated with a decrease in Cn concentration and an increase in short chain acylcarnitines (SCCn). In the absence of added Cn, 60 min incubation with P decreased Cn from 6.8 to 2.5 ..mu..M with a corresponding increase in SCCn. This effect of P to deplete free Cn was not seen to the same degree with butyrate in place of P. Similar increases in the formation of SCCn in the presence of P at the expense of free Cn were seen when the incubation Cn concentration was increased to 50 ..mu..M or 150 ..mu..M. HPLC methodologies to study specific acylcarnitines demonstrated the accumulation of large amounts of P-Cn in the incubations containing P, accounting for the depletion of free Cn.

Brass, E.P.; Beyerinck, R.A.

1987-05-01

235

Cellulose Synthesis in Agrobacterium tumefaciens  

SciTech Connect

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

Alan R. White; Ann G. Matthysse

2004-07-31

236

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

PubMed

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

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

2014-03-01

237

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

SciTech Connect

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

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

2012-08-10

238

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

PubMed

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

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

2014-01-01

239

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

PubMed Central

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

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

2014-01-01

240

Atomic force microscopy study of cellulose surface interaction controlled by cellulose binding domains  

Microsoft Academic Search

Colloidal probe microscopy has been used to study the interaction between model cellulose surfaces and the role of cellulose binding domain (CBD), peptides specifically binding to cellulose, in interfacial interaction of cellulose surfaces modified with CBDs.The interaction between pure cellulose surfaces in aqueous electrolyte solution is dominated by double layer repulsive forces with the range and magnitude of the net

R. Nigmatullin; R. Lovitt; C. Wright; M. Linder; T. Nakari-Setälä; M. Gama

2004-01-01

241

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

242

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

243

Thermophilic degradation of cellulosic biomass  

NASA Astrophysics Data System (ADS)

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

Ng, T.; Zeikus, J. G.

1982-12-01

244

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

245

Multilayers of cellulose derivatives and chitosan on nanofibrillated cellulose.  

PubMed

The aim of this work was to study the effect of solution conditions and polysaccharide structure on their Layer-by-Layer (LbL) deposition on nanofibrillated cellulose (NFC). Multilayer build-up of cellulose derivatives and chitosan on NFC model surfaces was studied using Quartz Crystal Microbalance with Dissipation (QCM-D) and Colloidal Probe Microscopy (CPM). The type of cationic polysaccharide was found to significantly affect the multilayer build-up and surface interactions. Cationic cellulose derivative quaternized hydroxyethyl cellulose ethoxylate (HECE) formed highly water-swollen layers with carboxymethyl cellulose (CMC), and the build-up was markedly influenced by both the ionic strength and pH. The ionic strength did not significantly influence the multilayer build-up of chitosan-CMC system, and adsorbed chitosan layers decreased the viscoelasticity of the system. Based on the results, it was also confirmed that electrostatic interaction is not the only driving force in case of the build-up of polysaccharide multilayers on nanofibrillated cellulose. PMID:24751244

Junka, Karoliina; Sundman, Ola; Salmi, Jani; Osterberg, Monika; Laine, Janne

2014-08-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

247

Acetic Acid Catalyzed Carbon Aerogels  

Microsoft Academic Search

We prepared carbon aerogels with a wide range of structural properties and densities using the weak acetic acid as a catalyst. Two series of acetic acid catalyzed carbon aerogels with different dilution of the catalyst and the monomers were investigated accurately. Structural investigation was performed via (U)SAXS, gas sorption and SEM. The pore and particle size can be tailored according

R. Brandt; R. Petricevic; H. Pröbstle; J. Fricke

2003-01-01

248

Acetate metabolism in Methanothrix soehngenii  

Microsoft Academic Search

Acetate is quantitatively the most important intermediate in the anaerobic degradation of soluble organic matter. The conversion rate of acetate by methanogenic bacteria is proposed to be the rate limiting step in this degradation The study of acetoclastic methanogens, therefore is of relevance to our understanding of anaerobic processes and their optimal application in treatment of waste water from various

M. S. M. Jetten

1991-01-01

249

Acetic acid bacteria in oenology  

Microsoft Academic Search

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

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

250

Early onset of effect of salmeterol and fluticasone propionate in chronic obstructive pulmonary disease  

PubMed Central

Background: Combined treatment with inhaled corticosteroids and long acting ß2 agonists is approved for the treatment of chronic obstructive pulmonary disease (COPD), but little is known about the onset of effect of the combination. Methods: Data were used from 1465 patients with COPD entered into a large 1 year double blind trial with daily measurements of peak expiratory flow (PEF) and symptom scores. Results: PEF was significantly higher after 1 day in patients treated with salmeterol 50 µg twice daily or the salmeterol/fluticasone propionate combination 50/500 µg twice daily than placebo. In patients treated with fluticasone propionate 500 µg twice daily alone, PEF differed from placebo after 2 days. The differences after 2 weeks compared with placebo were 16 l/min (95% confidence interval (CI) 11 to 21), 11 l/min (95% CI 6 to 16), and 27 l/min (95% CI 22 to 33) for salmeterol, fluticasone propionate, and the salmeterol/fluticasone propionate combination, respectively. For all treatments the effect on PEF after 2 weeks was comparable to that seen at the end of the study. The difference between the salmeterol/fluticasone propionate combination and placebo after 2 weeks as a percentage of baseline was similar for PEF and clinic forced expiratory volume in 1 second (FEV1). Differences in breathlessness scores were statistically significant after 1 day for the group treated with salmeterol alone and after 2 days for the combination group. The 2 week change in FEV1 was only partly indicative of a long term response in individual patients. Conclusions: The effects of salmeterol and fluticasone propionate, alone or in combination, on PEF and breathlessness are seen within days and most of the obtainable effect on these parameters is reached within 2 weeks. PMID:15790985

Vestbo, J; Pauwels, R; Anderson, J; Jones, P; Calverley, P; on, b

2005-01-01

251

Molecular Structure of Phenylmercuric acetate  

NSDL National Science Digital Library

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

2004-11-10

252

Adduct complexes of ruthenium(II,III) propionate dimer with pyridyl nitroxides  

Microsoft Academic Search

The synthesis, structural characterization and magnetic properties of new mixed-valent(II,III) complexes are reported. The reaction of ruthenium(II,III) propionate with pyridyl nitroxide produces polymer chain complexes [Ru2(pro)4(m- and p-nitpy)]nXn and dimer complexes [Ru2(pro)4(m- and p-nitpy)2]X (Hpro=propionic acid, X=BF4 and PF6). The chain and dimer structures were confirmed by X-ray structure analyses of [Ru2(pro)4(m-nitpy)]PF6 and [Ru2(pro)4(p-nitpy)2]BF4; the axial sites of Ru(II,III) dimer

Masahiro Mikuriya; Katsunori Tanaka; Makoto Handa; Ichiro Hiromitsu; Daisuke Yoshioka; Dominique Luneau

2005-01-01

253

Conductance of Dilute Sodium Acetate Solutions to 469 K and of Acetic Acid and Sodium Acetate\\/Acetic Acid Mixtures to 548 K and 20 MPa  

Microsoft Academic Search

In order to obtain accurate association constants for sodium acetate, a very precise flow method was used to measure the electrical conductivity of dilute aqueous solutions of sodium acetate at ambient conditions and 469 K and 20 MPa. Measurements at ambient conditions, 469 and 548 K and 20 MPa, were also made on sodium acetate\\/acetic acid mixtures and acetic acid.

G. H. Zimmerman; R. H. Wood

2002-01-01

254

Surface modification of cellulose nanocrystals  

NASA Astrophysics Data System (ADS)

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

Eyley, Samuel; Thielemans, Wim

2014-06-01

255

Surface modification of cellulose nanocrystals.  

PubMed

Chemical modification of cellulose nanocrystals is an increasingly popular topic in the literature. This review analyses the type of cellulose nanocrystal modification reactions that have been published in the literature thus far and looks at the steps that have been taken towards analysing the products of the nanocrystal modifications. The main categories of reactions carried out on cellulose nanocrystals are oxidations, esterifications, amidations, carbamations and etherifications. More recently nucleophilic substitutions have been used to introduce more complex functionality to cellulose nanocrystals. Multi-step modifications are also considered. This review emphasizes quantification of modification at the nanocrystal surface in terms of degree of substitution and the validity of conclusions drawn from different analysis techniques in this area. The mechanisms of the modification reactions are presented and considered with respect to the effect on the outcome of the reactions. While great strides have been made in the quality of analytical data published in the field of cellulose nanocrystal modification, there is still vast scope for improvement, both in data quality and the quality of analysis of data. Given the difficulty of surface analysis, cross-checking of results from different analysis techniques is fundamental for the development of reliable cellulose nanocrystal modification techniques. PMID:24937092

Eyley, Samuel; Thielemans, Wim

2014-07-21

256

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

PubMed Central

BACKGROUND: A study was performed to compare the adrenal suppression caused by inhaled fluticasone propionate and budesonide on a microgram equivalent basis, each given by metered dose inhaler to asthmatic patients. METHODS: Twelve asthmatic patients of mean age 29.9 years, with a forced expiratory volume in one second (FEV1) 92.9% predicted and forced expiratory flow 25-75% (FEF25-75) 69.5% predicted, on less than or equal to 400 micrograms/day inhaled corticosteroid, were studied in a double blind placebo controlled crossover design comparing single doses of inhaled budesonide 400, 1000, 1600, 2000 micrograms and fluticasone propionate 500, 1000, 1500, 2000 micrograms. Doses were administered at 22.00 hours by metered dose inhaler with mouth rinsing and measurements were made in the laboratory 10 hours later. RESULTS: Serum cortisol levels compared with placebo (mean 325.2 nmol/l) were suppressed by fluticasone at doses of 1500 micrograms (211.6 nmol/l) and 2000 micrograms (112.3 nmol/l) and by budesonide at 2000 micrograms (243.4 nmol/l). Fluticasone propionate 2000 micrograms produced lower absolute serum cortisol levels than budesonide 2000 micrograms (95% CI for difference 42.9 to 219.2). The dose ratio (geometric mean) for the relative potency was 2.89 fold (95% CI 1.19 to 7.07). In terms of percentage suppression versus placebo, fluticasone propionate also produced greater effects (means and 95% CI for difference): budesonide 1600 micrograms (16.0) versus fluticasone propionate 1500 micrograms (40.9) (95% CI -0.6 to 50.6), budesonide 2000 micrograms (26.0) versus fluticasone 2000 micrograms (65.2) (95% CI 10.5 to 67.8). Individual serum cortisol levels at the two highest doses showed 15 of 24 patients below the normal limit of the reference range (150 nmol/l) for fluticasone and five of 24 for budesonide. Fluticasone propionate also caused greater ACTH suppression than budesonide (as % versus placebo): budesonide 1600 micrograms (12.0) versus fluticasone propionate 1500 micrograms (31.9) (95% CI 7.6 to 32.1), budesonide 2000 micrograms (13.5) versus fluticasone propionate 2000 micrograms (44.4) (95% CI 13.2 to 48.7). For overnight 10 hour urinary cortisol (nmol/10 hours) there was a difference between the lowest doses of the two drugs: budesonide 400 micrograms (37.2) versus fluticasone propionate 500 micrograms (19.9) (95% CI 6.9 to 27.8). CONCLUSIONS: Like budesonide the systemic bioactivity of fluticasone propionate is mainly due to lung vascular absorption. Fluticasone propionate exhibited at least twofold greater adrenal suppression than budesonide on a microgram equivalent basis in asthmatic patients. PMID:8779128

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

1996-01-01

257

Encapsulation of antihypertensive drugs in cellulose-based matrix microspheres: characterization and release kinetics of microspheres and tableted microspheres.  

PubMed

This study is an attempt to prepare microspheres loaded with two antihypertensive drugs viz., nifedipine (NFD) and verapamil hydrochloride (VRP) using cellulose-based polymers viz., ethyl cellulose (EC) and cellulose acetate (CA). Emulsification and solvent evaporation methods were optimized using ethyl acetate as a dispersing solvent. The particles are spherical in shape and have smooth surfaces, as evidenced by the scanning electron microscopy. The microspheres were characterized for their particle size and distribution, tapped density and encapsulation efficiency. Smaller sized particles with a narrow size distribution were produced with EC when compared to CA matrices. Molecular level drug distribution in the microspheres was confirmed by differential scanning calorimetry. The microspheres were directly compressed into tablets using different excipients. The drug release from CA was faster than EC microspheres and, also, the VRP release was faster than NFD. The excipients used in tableting showed an effect on the release as well as the physical properties of the tablets. PMID:11308229

Soppimath, K S; Kulkarni, A R; Aminabhavi, T M

2001-01-01

258

Dielectric Relaxation in Cellulose and its Derivatives  

NASA Astrophysics Data System (ADS)

The relaxation processes in cellulose, methyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose were studied by dielectric spectroscopy. The dielectric spectra for these polysaccharides were measured in the frequency range from 100 Hz to 1 MHz and in the temperature range from 100 to 450 K. The dielectric relaxation data for cellulose, methyl cellulose, hydroxypropylmethyl cellulose were described by Arrhenius and Eyring equations and interpreted as due to a local motion of chain segments via the glucosidic linkages, so-called ?-relaxation. The same relaxation process was also determined for the hydroxypropyl cellulose polymer in the temperature range of 240-270 K. At higher temperature in hydroxypropyl cellulose another relaxation mechanism occurs due to the reorientation of the side chain built of a few hydroxypropylene groups. The activation parameters of the observed dielectric relaxation processes were determined.

Rachocki, A.; Markiewicz, E.; Tritt-Goc, J.

2006-07-01

259

Impact of trace element addition on degradation efficiency of volatile fatty acids, oleic acid and phenyl acetate and on microbial populations in a biogas digester.  

PubMed

The effect of trace element addition on anaerobic digestion of food industry- and household waste was studied using two semi-continuous lab-scale reactors, one (R30+) was supplied with Fe, Co and Ni, while the other (R30) acted as a control. Tracer analysis illustrated that methane production from acetate proceeded through syntrophic acetate oxidation (SAO) in both digesters. The effect of the trace elements was also evaluated in batch assays to determine the capacity of the microorganisms of the two digesters to degrade acetate, phenyl acetate, oleic acid or propionate, butyrate and valerate provided as a cocktail. The trace elements addition improved the performance of the process giving higher methane yields during start-up and early operation and lower levels of mainly acetate and propionate in the R30+ reactor. The batch assay showed that material from R30+ gave effects on methane production from all substrates tested. Phenyl acetate was observed to inhibit methane formation in the R30 but not in the R30+ assay. A real-time PCR analysis targeting methanogens on the order level as well as three SAO bacteria showed an increase in Methanosarcinales in the R30+ reactor over time, even though SAO continuously was the dominating pathway for methane production. Possibly, this increase explains the low VFA-levels and higher degradation rates observed in the R30+ batch incubations. These results show that the added trace elements affected the ability of the microflora to degrade VFAs as well as oleic acid and phenyl acetate in a community, where acetate utilization is dominated by SAO. PMID:22683024

Karlsson, Anna; Einarsson, Peter; Schnürer, Anna; Sundberg, Carina; Ejlertsson, Jörgen; Svensson, Bo H

2012-10-01

260

Shear and extensional rheology of cellulose/ionic liquid solutions.  

PubMed

In this study, we characterize the shear and extensional rheology of dilute to semidilute solutions of cellulose in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIAc). In steady shear flow, the semidilute solutions exhibit shear thinning, and the high-frequency complex modulus measured in small amplitude oscillatory shear flow exhibits the characteristic scaling expected for solutions of semiflexible chains. Flow curves of the steady shear viscosity plotted against shear rate closely follow the frequency dependence of the complex viscosity acquired using oscillatory shear, thus satisfying the empirical Cox-Merz rule. We use capillary thinning rheometry (CaBER) to characterize the relaxation times and apparent extensional viscosities of the semidilute cellulose solutions in a uniaxial extensional flow that mimics the dynamics encountered in the spin-line during fiber spinning processes. The apparent extensional viscosity and characteristic relaxation times of the semidilute cellulose/EMIAc solutions increase dramatically as the solutions enter the entangled concentration regime at which fiber spinning becomes viable. PMID:22480203

Haward, Simon J; Sharma, Vivek; Butts, Craig P; McKinley, Gareth H; Rahatekar, Sameer S

2012-05-14

261

Determination of neutral sugars in soil by capillary gas chromatography after derivatization to aldononitrile acetates  

Microsoft Academic Search

We have quantified ribose, rhamnose, arabinose, xylose, fucose, mannose, glucose, and galactose in soil by gas chromatography (GC) simultaneously after converting to aldononitrile acetate derivatives. A recommended single-hydrolytic step by 4M trifluoroacetic acid (TFA) at 105°C for 4h was more effective for releasing soil neutral sugars from non-cellulosic carbohydrates and better suited to our purification procedure compared with the sulphuric

Wei Zhang; Hongbo He; Xudong Zhang

2007-01-01

262

Point mutation of H3/H4 histones affects acetic acid tolerance in Saccharomyces cerevisiae.  

PubMed

The molecular mechanism of acetic acid tolerance in yeast remains unclear despite of its importance for efficient cellulosic ethanol production. In this study, we examined the effects of histone H3/H4 point mutations on yeast acetic acid tolerance by comprehensively screening a histone H3/H4 mutant library. A total of 24 histone H3/H4 mutants (six acetic acid resistant and 18 sensitive) were identified. Compared to the wild-type strain, the histone acetic acid-resistant mutants exhibited improved ethanol fermentation performance under acetic acid stress. Genome-wide transcriptome analysis revealed that changes in the gene expression in the acetic acid-resistant mutants H3 K37A and H4 K16Q were mainly related to energy production, antioxidative stress. Our results provide novel insights into yeast acetic acid tolerance on the basis of histone, and suggest a novel approach to improve ethanol production by altering the histone H3/H4 sequences. PMID:25093933

Liu, Xiangyong; Zhang, Xiaohua; Zhang, Zhaojie

2014-10-10

263

Phosphorus limitation strategy to increase propionic acid flux towards 3-hydroxyvaleric acid monomers in Cupriavidus necator.  

PubMed

Properties of polyhydroxybutyrate-co-hydroxyvalerate (P(3HB-co-3HV)) depend on their 3HV content. 3HV can be produced by Cupriavidus necator from propionic acid. Few studies explored carbon distribution and dynamics of 3HV and 3HB monomers production, and none of them have been done with phosphorus as limiting nutrient. In this study, fed-batch cultures of C. necator with propionic acid, as sole carbon source or mixed with butyric acid, were performed. Phosphorus deficiency allowed sustaining 3HV production rate and decreasing 3HB production rate, leading to an instant production of up to 100% of 3HV. When a residual growth is sustained by a phosphorus feeding, the maximum 3HV percentage produced from propionic acid is limited to 33% (Mole.Mole(-1)). The association of a second carbon source like butyric acid lead to higher conversion of propionic acid into 3HV. This study showed the importance of the limiting nutrient and of the culture strategy to get the appropriate product. PMID:24365742

Grousseau, Estelle; Blanchet, Elise; Déléris, Stéphane; Albuquerque, Maria G E; Paul, Etienne; Uribelarrea, Jean-Louis

2014-02-01

264

MASCULINIZATION OF FEMALE RATS BY PRENATAL TESTOSTERONE PROPIONATE IS PARTIALLY ATTENUATED BY VINCLOZOLIN  

EPA Science Inventory

MASCULINIZATION OF FEMALE RATS BY PRENATAL TESTOSTERONE PROPIONATE IS PARTIALLY ATTENUATED BY VINCLOZOLIN Cynthia Wolf1,2, Gerald LeBlanc2, Andrew Hotchkiss3, Jonathan Furr1, L Earl Gray, Jr.1 1USEPA, Reproductive Toxicology Division, RTP, NC 27711, 2Dept. Molecular and En...

265

Enhanced Propionate Formation by Propionibacterium freudenreichii subsp. freudenreichii in a Three-Electrode Amperometric Culture System  

PubMed Central

In order to influence the fermentation pattern of Propionibacterium freudenreichii towards enhanced propionate formation, growth and product formation with glucose and lactate as energy sources were studied in a three-electrode poised-potential amperometric culture system. With anthraquinone 2,6-disulfonic acid (E0? = ?184 mV; poised electron potential = ?224 mV) or cobalt sepulchrate (E0? = ?350 mV; ?390 mV) as mediator and an activated platinum working electrode, reduction of bacterially oxidized mediator occurred fast enough to keep more than 50% of the respective mediator (in minimum 0.4 mM) in the reduced state, up to a current of 2 mA. With glucose as substrate, 90.0 or 97.3% propionate was formed during exponential growth in the presence of 0.5 mM anthraquinone 2,6-disulfonic acid or 0.4 mM cobalt sepulchrate, respectively. Growth yields of 56.3 or 53.8 g of cell material per mol of substrate degraded were calculated, respectively, and the electrons were transferred quantitatively from the working electrode to the bacterial cells. With l-lactate, only 68.6 or 72.9% propionate was formed with the same mediators. The results are discussed with respect to energetics, electron transfer potentials, and potential application of the new technique in technical propionate production. PMID:16348285

Emde, Rainer; Schink, Bernhard

1990-01-01

266

Assessment of the main engineering parameters controlling the electrodialytic recovery of sodium propionate from aqueous solutions  

Microsoft Academic Search

The main engineering parameters (i.e. ion transport numbers in solution and electro-membranes; effective solute and water transport numbers; effective membrane surface area, membrane surface resistances, limiting current intensity and mass transfer coefficient) controlling the recovery of sodium propionate from model solutions by electrodialysis were determined in accordance with a sequential experimental procedure. Such parameters allowed a satisfactorily simulation of training

Marcello Fidaleo; Mauro Moresi

2006-01-01

267

Cellulose hydrogels prepared from micron-sized bamboo cellulose fibers.  

PubMed

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

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

2014-12-19

268

Inhibition of Listeria monocytogenes by propionic acid-based ingredients in cured deli-style Turkey.  

PubMed

Listeria monocytogenes growth can be controlled on ready-to-eat meats through the incorporation of antimicrobial ingredients into the formulation or by postlethality kill steps. However, alternate approaches are needed to provide options that reduce sodium content but maintain protection against pathogen growth in meats after slicing. The objective of this study was to determine the inhibition of L. monocytogenes by propionic acid-based ingredients in high-moisture, cured turkey stored at 4 or 7°C. Six formulations of sliced, cured (120 ppm of NaNO2 ), deli-style turkey were tested, including control without antimicrobials, 3.2% lactate-diacetate blend (LD), 0.4% of a liquid propionate-benzoate-containing ingredient, or 0.3, 0.4, and 0.5% of a liquid propionate-containing ingredient. Products were inoculated with 5 log CFU L. monocytogenes per 100-g package (3 log CFU/ml rinsate), vacuum-sealed, and stored at 4 or 7°C for up to 12 weeks; and populations were enumerated by plating on modified Oxford agar. As expected, the control without antimicrobials supported rapid growth, with >2 log average per ml rinsate increase within 4 weeks of storage at 4°C, whereas growth was observed at 6 weeks for the LD treatment. For both replicate trials, all treatments that contained liquid propionate or propionate-benzoate limited L. monocytogenes growth to an increase of <1 log through 9 weeks storage at 4°C. Sporadic growth (>1-log increase) was observed in individual samples for all propionate-containing treatments at weeks 10, 11, and 12. As expected, L. monocytogenes grew more rapidly when products were stored at 7°C, but trends in relative inhibition were similar to those observed at 4°C. These results verify that propionate-based ingredients inhibit growth of L. monocytogenes on sliced, high-moisture, cured turkey and can be considered as an alternative to reduce sodium-based salts while maintaining food safety. PMID:24290685

Glass, Kathleen A; McDonnell, Lindsey M; Von Tayson, Roxanne; Wanless, Brandon; Badvela, Mani

2013-12-01

269

Degradation of cellulosic biomass and its subsequent utilization for the production of chemical feedstocks. Progress report, March 1-August 31, 1980  

SciTech Connect

Progress is reported in this coordinated research program to effect the microbiological degradation of cellulosic biomass by anaerobic microorganisms possessing cellulolytic enzymes. Three main areas of research are discussed: increasing enzyme levels through genetics, mutations, and genetic manipulation; the direct conversion of cellulosic biomass to liquid fuel (ethanol); and the production of chemical feedstocks from biomass (acrylic acid, acetone/butanol, and acetic acid). (DMC)

Wang, D. I.C.

1980-09-01

270

Systemic treatment with the enteric bacterial fermentation product, propionic acid, produces both conditioned taste avoidance and conditioned place avoidance in rats  

Microsoft Academic Search

Propionic acid, an enteric bacterial fermentation product, has received recent attention in regards to satiety and obesity in humans. The possibility that propionic acid might produce internal aversive cues was investigated in two experiments using conditioned taste avoidance and place avoidance procedures to index the potential aversive nature of systemic treatment with propionic acid in male rats. Experiment 1 examined

Klaus-Peter Ossenkopp; Kelly A. Foley; James Gibson; Melissa A. Fudge; Martin Kavaliers; Donald P. Cain; Derrick F. MacFabe

271

Response of Cellulose detectors to different doses of 62 MeV protons  

NASA Astrophysics Data System (ADS)

Optical and thermal responses of two cellulose detectors, Cellulose triacetate (Triafol-TN) and Cellulose acetate butyrate (Triafol-BN), to four different doses of 62 MeV protons were studied using spectroscopic, thermal and track-etching techniques. The spectroscopic analysis revealed that though the optical band-gap in the polymers was affected by proton irradiation, the polymers showed high resistance against any major structural modification by radiation. The thermal stability of the polymers was found to be affected by proton irradiation. The activation energy of etching was found to be almost constant for both the polymers even after irradiation. It is hoped that the findings in this work would be of significant relevance to material science and applications of polymers.

Tripathy, S. P.; Mishra, R.; Dwivedi, K. K.; Ghosh, S.; Fink, D.; Khathing, D. T.

2003-08-01

272

Development of nonflammable cellulosic foams  

NASA Technical Reports Server (NTRS)

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

Luttinger, M.

1972-01-01

273

Electrically generated lead(IV) acetate and manganese(III) acetate as reagents for coulometric redox titrations in acetic acid  

Microsoft Academic Search

Summary The conditions were investigated for electrochemical generation of lead(IV) acetate in acetic acid by oxidation of lead(II) acetate on a lead dioxide electrode and on a platinum electrode. Bivalent manganese ions are quantitatively oxidized on a platinum electrode to the tervalent state in the same solvent. Coulometric titration methods for the determination of small amounts of hydroquinone in acetic

Tibor J. Pastor; Vilim J. Vajgand; Zorica Kicovic

1976-01-01

274

Propionate absorbed from the colon acts as gluconeogenic substrate in a strict carnivore, the domestic cat (Felis catus).  

PubMed

In six normal-weight and six obese cats, the metabolic effect of propionate absorbed from the colon was assessed. Two colonic infusions were tested in a crossover design with intervals of 4?weeks. The test solution contained 4?mmol sodium propionate per kg ideal body weight in a 0.2% NaCl solution. Normal saline was given as control solution. Solutions were infused into the hindgut over 30?min. Blood samples were obtained prior to and at various time points after starting the infusion. As body condition did not affect evaluated parameters, all data were pooled. Plasma glucose concentrations showed differences neither over time nor during or after infusion with propionate or control. Plasma amino acid concentrations rose over time (p?propionate infusion and decreased afterwards (p?propionate infusions and acetylcarnitine tended to fall at the same time points (p?=?0.079; p?=?0.080), suggesting inhibition of gluconeogenesis from pyruvate and amino acids, but initiation of propionate-induced gluconeogenesis. In conclusion, propionate absorbed from the colon is hypothesized to act as gluconeogenic substrate, regardless of the cat's body condition. PMID:21895780

Verbrugghe, A; Hesta, M; Daminet, S; Polis, I; Holst, J J; Buyse, J; Wuyts, B; Janssens, G P J

2012-12-01

275

Adsorption and desorption of cellulose derivatives  

Microsoft Academic Search

Cellulose derivatives, in particular carboxymethyl cellulose (CMC) are used in many (industrial) applications. The aim of this work is to obtain insight into the adsorption mechanism of cellulose derivatives on solid-liquid interfaces.In chapter 1<\\/strong> of this thesis we discuss some applications of cellulose derivatives. Application of CMC in pelleting of iron ore and in papermaking and the role of adsorption

C. W. Hoogendam

1998-01-01

276

Cellulose Oligomers: Preparation from Cellulose Triacetate, Chemical Transformations and Reactions  

Microsoft Academic Search

Cellulose oligomers obtained by a new degradation method (pivaloylysis) are used as starting materials in organic synthesis. On the one hand these oligomers are functionalized to potent glycosyl donors, on the other hand several methods are shown to generate different types of hydroxy compounds (glycosyl acceptors). Glycosidation reactions performed with these two types of building blocks allow an access to

P. Arndt; K. Bockholt; R. Gerdes; S. Huschens; J. Pyplo; H. Redlich; K. Samm

2003-01-01

277

Mascoma Announces Major Cellulosic Biofuel Technology Breakthrough  

E-print Network

Mascoma Announces Major Cellulosic Biofuel Technology Breakthrough Lebanon, NH - May 7, 2009 bioprocessing, or CBP, a low-cost processing strategy for production of biofuels from cellulosic biomass. CBP much, much closer to billions of gallons of low cost cellulosic biofuels," said Michigan State

278

Natural cellulose fibers from soybean straw  

Microsoft Academic Search

This paper reports the development of natural cellulose technical fibers from soybean straw with properties similar to the natural cellulose fibers in current use. About 220 million tons of soybean straw available in the world every year could complement the byproducts of other major food crops as inexpensive, abundant and annually renewable sources for natural cellulose fibers. Using the agricultural

Narendra Reddy; Yiqi Yang

2009-01-01

279

IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION  

Microsoft Academic Search

This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms.

Leschine

2009-01-01

280

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

PubMed Central

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

Isik, Mehmet; Sardon, Haritz; Mecerreyes, David

2014-01-01

281

Fuel ethanol from cellulosic biomass  

Microsoft Academic Search

Ethanol produced from cellulosic biomass is examined as a large-scale transportation fuel. Desirable features include ehtanol's fuel properties as well as benefits with respect to urban air quality, global climate change, balance of trae, and energy security. Energy balance, feedstock supply, and environmental impact considerations are not seen as significant barriers to the widespread use of fuel ethanol derived from

L. R. Lynd; J. H. Cushman; R. J. Nichols; C. E. Wyman

1991-01-01

282

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria  

Microsoft Academic Search

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Ga. europaeus exhibited the highest resistance to acetic acid (10%), whereas Ga. intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal

Janja Trcek; Hirohide Toyama; Jerzy Czuba; Anna Misiewicz; Kazunobu Matsushita

2006-01-01

283

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

PubMed Central

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

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

1994-01-01

284

Influence of buffered propionic acid on the development of micro-organisms in hay.  

PubMed

We tested the benefit of using buffered propionic acid (BPA) as a means of preventing farmer's lung disease (FLD). BPA, a new formulation of propionic acid, a hay preservative with no deleterious effect on farm machinery or cattle, reduces the development of micro-organisms in hay. Twenty pairs of round bales were analysed for concentration of micro-organisms measured in the winter following hay treatment. Each pair included one untreated bale and one bale treated with BPA during haymaking. Our results showed the following decreases in concentration in treated bales: total fungal species, 40% (P < 0.05); Eurotium amstelodami (the main species found), 65% (P < 0.01); and thermophilic actinomycetes, 60% (not significant), respectively. We conclude that BPA could be used to prevent FLD. PMID:12100537

Reboux, G; Dalphin, J-C; Polio, J-C; Millon, L; Baverel, J; Martinez, J; Girard, L; Piarroux, R

2002-06-01

285

Acetic Acid bacteria: physiology and carbon sources oxidation.  

PubMed

Acetic acid bacteria (AAB) are obligately aerobic bacteria within the family Acetobacteraceae, widespread in sugary, acidic and alcoholic niches. They are known for their ability to partially oxidise a variety of carbohydrates and to release the corresponding metabolites (aldehydes, ketones and organic acids) into the media. Since a long time they are used to perform specific oxidation reactions through processes called "oxidative fermentations", especially in vinegar production. In the last decades physiology of AAB have been widely studied because of their role in food production, where they act as beneficial or spoiling organisms, and in biotechnological industry, where their oxidation machinery is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid and cellulose. The present review aims to provide an overview of AAB physiology focusing carbon sources oxidation and main products of their metabolism. PMID:24426139

Mamlouk, Dhouha; Gullo, Maria

2013-12-01

286

The Plant Growth-Regulating Activity of Dextro and Laevo alpha -(2-naphthoxy) Propionic Acid  

Microsoft Academic Search

(±)-alpha -(2-naphthoxy)propionic acid, an active plant growth-regulating substance, has been resolved into its dextro and laevo rotatory enantiomorphs by fractional crystallization of its (+)-cinchonine salts. The pure stereoisomers have been examined for their effect in inducing a range of growth responses, depending upon cell division, cell enlargement, or both. For these purposes, the Went pea test and the Avena cylinder

M. S. Smith; R. L. Wain

1951-01-01

287

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

Microsoft Academic Search

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

ShengLi Niu; KuiHua Han; ChunMei Lu

2011-01-01

288

Comparative mutagenic and genotoxic effects of three propionic acid derivatives ibuprofen, ketoprofen and naproxen  

Microsoft Academic Search

The mutagenicity of three propionic acid derivatives, namely ibuprofen, ketoprofen and naproxen, was tested in the Ames mutagenicity assay (in strains TA97a, TA100 and TA102) and in vivo genotoxicity was tested by sister chromatid exchange (SCE) in bone marrow cells of mice. These are the anti-inflammatory drugs frequently used in different parts of the world. Mutagenicity results showed no mutagenic

B Philipose; R Singh; K. A Khan; A. K Giri

1997-01-01

289

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

Microsoft Academic Search

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

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

2002-01-01

290

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

SciTech Connect

The fermentation of cellulose by an ovine rumen anaerobic fungus in the absence and presence of rumen methanogens is described. In the monoculture, moles of product as a percentage of the moles of hexose fermented were: acetate, 72.7; carbon dioxide, 37.6; formate, 83.1; ethanol, 37.4; lactate, 67.0; and hydrogen 35.3. In the coculture, acetate was the major product (134.7%), and carbon dioxide increased (88.7%). Lactate and ethanol production decreased to 2.9 and 19% respectively, little formate was detected (1%), and hydrogen did not accumulate. Substantial amounts of methane were produced in the coculture (58.7%). Studies with (2-14C) acetate indicated that acetate was not a precursor of methane. The demonstration of cellulose fermentation by a fungus extends the range of known rumen organisms capable of participating in cellulose digestion and provides further support for a role of anaerobic fungi in rumen fiber digestion. The effect of the methanogens on the pattern of fermentation is interpreted as a shift in flow of electrons away from electron sink products to methane via hydrogen. The study provides a new example of intermicrobial hydrogen transfer and the first demonstration of hydrogen formation by a fungus. (Refs. 27).

Bauchop, T.; Mountfort, D.O.

1981-12-01

291

Friedel–Crafts acylation of anisole with propionic anhydride over mesoporous superacid catalyst UDCaT-5  

Microsoft Academic Search

The synthesis of 4-methoxypropiophenone, an intermediate for the production of fine chemicals and pharmaceuticals, was carried out via Friedel–Crafts acylation of anisole with propionic anhydride by using various solid acid catalysts. The reactions were carried out under solvent-free conditions. A novel mesoporous superacid catalyst UDCaT-5 developed in our laboratory was the most active, selective and robust. The conversion of propionic

Ganapati D. Yadav; Ginish George

2006-01-01

292

Effects of sodium lactate and sodium propionate on the sensory, microbial, and chemical characteristics of fresh aerobically stored ground beef  

E-print Network

effects of benzoic and propionic acid on Bacillus subtilis, Bacillus cereus, E, coli, Pseudomonas aeruginosa, S. aureus, and Candida albicans, and determined the minimum growth inhibitory concentration for each organism. The researchers found... effects of benzoic and propionic acid on Bacillus subtilis, Bacillus cereus, E, coli, Pseudomonas aeruginosa, S. aureus, and Candida albicans, and determined the minimum growth inhibitory concentration for each organism. The researchers found...

Eckert, Laura Anne

2012-06-07

293

Ground beef shelf life assessment as influenced by sodium lactate, sodium propionate, sodium diacetate, and soy protein concentrate  

E-print Network

. This data was supported by Eklund (1985) who found the minimum growth inhibitory concentration of propionic acid for Bacillus subiti lis, Bacillus cereus, E coli, Pseudomonas aeruginosa, S. aureus and Candida albicans. In 1989, El-Shenawy and Marth (1989.... This data was supported by Eklund (1985) who found the minimum growth inhibitory concentration of propionic acid for Bacillus subiti lis, Bacillus cereus, E coli, Pseudomonas aeruginosa, S. aureus and Candida albicans. In 1989, El-Shenawy and Marth (1989...

Grones, Kelly Leann

2012-06-07

294

Ln[DO3A-N-?-(pyrenebutanamido)propionate] complexes: optimized relaxivity and NIR optical properties.  

PubMed

We have proposed recently that the DO3A-N-?-(amino)propionate chelator and its amide conjugates are leads to targeted, high relaxivity, safe contrast agents for magnetic resonance imaging. In this work we illustrate further the expeditious nature and robustness of the synthetic methodologies developed by preparing the DO3A-N-(?-pyrenebutanamido)propionate chelator. Its Gd(3+) chelate retains the optimized water exchange, high stability and inertness of the parent complex. The pyrene moiety imparts concentration-dependent self-assembly properties and aggregation-sensitive fluorescence emission to the Gd(3+) complex. The Gd(3+) complex displays pyrene-centred fluorescence whilst the Yb(3+) and Nd(3+) complexes exhibit sensitized lanthanide-centred near-infrared luminescence. The aggregated form of the complex displays high relaxivity (32 mM(-1) s(-1), 20 MHz, 25 °C) thanks to simultaneous optimization of the rotational correlation time and of the water exchange rate. The relaxivity is however still limited by chelate flexibility. This report demonstrates that the DO3A-N-(?-amino)propionate chelator is a valuable platform for constructing high relaxivity CA using simple design principles and robust chemistries accessible to most chemistry labs. PMID:24343660

Ferreira, M F; Pereira, G; Martins, A F; Martins, C I O; Prata, M I M; Petoud, S; Toth, E; Ferreira, P M T; Martins, J A; Geraldes, C F G C

2014-02-28

295

Effect of chemical structure on the release of certain propionic acid derivatives from their dosage forms.  

PubMed

The aim of this study was to investigate the relationship between the chemical structure and release properties of certain drug products. Propionic acid derivatives were used as a model. These include ibuprofen (I), ketoprofen (K), tiaprofenic acid (T), flurbiprofen (F), and naproxen (N). They are all aryl derivatives of propionic acid and differ only in the aryl group. Such an aryl group may be either isobutylphenyl, benzoylphenyl, benzoylthienyl, fluorobiphenyl, or methoxynaphthyl group in I, K, T, F, and N, respectively. Three dosage forms were selected for this study: capsules, suppositories, and creams. The release of propionic acid derivatives from the capsules and suppositories decreased in the order ibuprofen > tiaprofenic acid > ketoprofen > flurbiprofen > naproxen, and for the creams the release decreased in the order ibuprofen > tiaprofenic acid > flurbiprofen > ketoprofen > naproxen. The difference in drug release in the first case was attributed to the difference in the chain length, and in the creams which are composed of two phases, the partition coefficient was found to affect the drug release. The molecular weight of the drug had no effect on the release. The drug release from different dosage forms was not affected after 1 month storage. PMID:9876606

el-Bary, A A; el-Nabarawi, M A; Mohamed, M I

1998-05-01

296

Salmeterol combined with fluticasone propionate improved COPD in patients during stable stage  

PubMed Central

Purpose: To evaluate the clinical effect of inhaled Salmeterol with Fluticasone propionate (50:500 ?g) in patients with moderate to severe chronic obstructive pulmonary disease (COPD) during the stable stage of the disease. Methods: Sixty patients with moderate to severe COPD were randomly divided into trial and control groups (N=30 each). In the trial group, patients inhaled Salmeterol with Fluticasone (50:500 ?g) propionate twice daily via turbuhaler for 3 months. In the control group, patients used slow- released theophylline, 200 mg, twice daily for 3 months; patients took an expectorant (Ambroxol Hydrochloride, 10 ml, three times daily) if necessary. Clinical symptoms and physical signs were graded using St. George’s respiratory disease questionnaire (SGRQ). Changes in lung function were assessed. Results: Indicators of lung function including the values of FEV1, FEV1/FVC, and FEV1/predicted values were significantly higher after treatment in the trial group than in the control group (P<0.05). SGRQ values in the trial group decreased significantly after treatment (P<0.05). Conclusion: Inhaled Salmeterol 50 ?g and Fluticasone propionate 500 ?g can significantly improve the lung function and clinical symptoms of patients with stable moderate to severe COPD.

Lu, Dongmei; Ma, Junpeng; Yang, Xiaohong

2014-01-01

297

Investigation and characterization of oxidized cellulose and cellulose nanofiber films  

NASA Astrophysics Data System (ADS)

Over the last two decades, a large amount of research has focused on natural cellulose fibers, since they are "green" and renewable raw materials. Recently, nanomaterials science has attracted wide attention due to the large surface area and unique properties of nanoparticles. Cellulose certainly is becoming an important material in nanomaterials science, with the increasing demand of environmentally friendly materials. In this work, a novel method of preparing cellulose nanofibers (CNF) is being presented. This method contains up to three oxidation steps: periodate, chlorite and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidation. The first two oxidation steps are investigated in the first part of this work. Cellulose pulp was oxidized to various extents by a two step-oxidation with sodium periodate, followed by sodium chlorite. The oxidized products can be separated into three different fractions. The mass ratio and charge content of each fraction were determined. The morphology, size distribution and crystallinity index of each fraction were measured by AFM, DLS and XRD, respectively. In the second part of this work, CNF were prepared and modified under various conditions, including (1) the introduction of various amounts of aldehyde groups onto CNF by periodate oxidation; (2) the carboxyl groups in sodium form on CNF were converted to acid form by treated with an acid type ion-exchange resin; (3) CNF were cross-linked in two different ways by employing adipic dihydrazide (ADH) as cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide (EDC) as carboxyl-activating agent. Films were fabricated with these modified CNF suspensions by vacuum filtration. The optical, mechanical and thermo-stability properties of these films were investigated by UV-visible spectrometry, tensile test and thermogravimetric analysis (TGA). Water vapor transmission rates (WVTR) and water contact angle (WCA) of these films were also studied.

Yang, Han

298

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

PubMed Central

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

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

1994-01-01

299

Novel antimicrobial and biofilm-controlling cellulosic polymers  

NASA Astrophysics Data System (ADS)

Cotton and cellulose acetate (CA) are cellulosic polymers with versatile applications. Like any other polymeric materials, cellulosic materials are also susceptible to microbial contamination and cause serious nosocomial infections. Hence, there is a definite need to develop antimicrobial cellulosic materials to prevent microbial colonization. Henceforth, we prepared a suitable polycation to treat cotton fabrics and CA films by LbL self-assembly process to achieve potent antimicrobial functions. The treated fabrics demonstrated total kill against E. coli and S. aureus in 2 h contact time whereas treated CA films, even after 6 h, could inactivate only 98 % of bacteria. Since CA films are more hydrophobic, have less surface charge, and surface area than cotton fabrics, LbL procedure was not much effective for CA films to achieve potent antimicrobial functions. Yet, CA is another very important cellulosic polymer with various applications in which antimicrobial activity is often desired. So, to improve the antimicrobial activity of CA films, we designed a novel strategy to coat the surface of CaCO3 fillers with quaternary ammonium salts (QAS)based fatty acids to make the filler surface organophilic and accomplish antibacterial activity concurrently, rendering the resulting polymer-filler composites antimicrobial. Thus, a series of QAS-based fatty acids (C8-C16) were synthesized, coated onto CaCO 3, and used as antimicrobial additives (5 %) in CA films. Although C8-quat-CaCO 3 could only provide 94 % of reduction of bacteria, both C12- and C16- quats and their corresponding quat-coated CaCO3 provided a total kill of S. aureus and E. coli in 2 h. These findings suggested that it is feasible to use QAS-based fatty acids to coat CaCO3 and use them as antimicrobial additives of CA films to achieve potent antimicrobial effects. Building on these results, to further evaluate the applicability of the antimicrobial filler strategy, we synthesized an N-halamine based fatty acid, coated onto CaCO3 and used as antimicrobial additives in CA films; the resulting samples provided excellent antimicrobial and biofilm-controlling effects, confirming that the antimicrobial filler approach could be an effective strategy for the antimicrobial treatments of CA and potentially other related hydrophobic polymeric materials.

Padmanabhuni, Revathi V.

300

Cellobiohydrolase hydrolyzes crystalline cellulose on hydrophobic faces.  

PubMed

Biodegradation of plant biomass is a slow process in nature, and hydrolysis of cellulose is also widely considered to be a rate-limiting step in the proposed industrial process of converting lignocellulosic materials to biofuels. It is generally known that a team of enzymes including endo- and exocellulases as well as cellobiases are required to act synergistically to hydrolyze cellulose to glucose. The detailed molecular mechanisms of these enzymes have yet to be convincingly elucidated. In this report, atomic force microscopy (AFM) is used to image in real-time the structural changes in Valonia cellulose crystals acted upon by the exocellulase cellobiohydrolase I (CBH I) from Trichoderma reesei. Under AFM, single enzyme molecules could be observed binding only to one face of the cellulose crystal, apparently the hydrophobic face. The surface roughness of cellulose began increasing after adding CBH I, and the overall size of cellulose crystals decreased during an 11-h period. Interestingly, this size reduction apparently occurred only in the width of the crystal, whereas the height remained relatively constant. In addition, the measured cross-section shape of cellulose crystal changed from asymmetric to nearly symmetric. These observed changes brought about by CBH I action may constitute the first direct visualization supporting the idea that the exocellulase selectively hydrolyzes the hydrophobic faces of cellulose. The limited accessibility of the hydrophobic faces in native cellulose may contribute significantly to the rate-limiting slowness of cellulose hydrolysis. PMID:21282110

Liu, Yu-San; Baker, John O; Zeng, Yining; Himmel, Michael E; Haas, Thomas; Ding, Shi-You

2011-04-01

301

Cellobiohydrolase Hydrolyzes Crystalline Cellulose on Hydrophobic Faces*  

PubMed Central

Biodegradation of plant biomass is a slow process in nature, and hydrolysis of cellulose is also widely considered to be a rate-limiting step in the proposed industrial process of converting lignocellulosic materials to biofuels. It is generally known that a team of enzymes including endo- and exocellulases as well as cellobiases are required to act synergistically to hydrolyze cellulose to glucose. The detailed molecular mechanisms of these enzymes have yet to be convincingly elucidated. In this report, atomic force microscopy (AFM) is used to image in real-time the structural changes in Valonia cellulose crystals acted upon by the exocellulase cellobiohydrolase I (CBH I) from Trichoderma reesei. Under AFM, single enzyme molecules could be observed binding only to one face of the cellulose crystal, apparently the hydrophobic face. The surface roughness of cellulose began increasing after adding CBH I, and the overall size of cellulose crystals decreased during an 11-h period. Interestingly, this size reduction apparently occurred only in the width of the crystal, whereas the height remained relatively constant. In addition, the measured cross-section shape of cellulose crystal changed from asymmetric to nearly symmetric. These observed changes brought about by CBH I action may constitute the first direct visualization supporting the idea that the exocellulase selectively hydrolyzes the hydrophobic faces of cellulose. The limited accessibility of the hydrophobic faces in native cellulose may contribute significantly to the rate-limiting slowness of cellulose hydrolysis. PMID:21282110

Liu, Yu-San; Baker, John O.; Zeng, Yining; Himmel, Michael E.; Haas, Thomas; Ding, Shi-You

2011-01-01

302

Cellulose degradation by oxidative enzymes  

PubMed Central

Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs), cellobiose dehydrogenases (CDHs) and members of carbohydrate-binding module family 33 (CBM33). PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future. PMID:24688656

Dimarogona, Maria; Topakas, Evangelos; Christakopoulos, Paul

2012-01-01

303

Cellulose nanofibers from curaua fibers  

Microsoft Academic Search

Curaua nanofibers extracted under different conditions were investigated. The raw fibers were mercerized with NaOH solutions;\\u000a they were then submitted to acid hydrolysis using three different types of acids (H2SO4, a mixture of H2SO4\\/HCl and HCl). The fibers were analyzed by cellulose, lignin and hemicellulose contents; viscometry, X-ray diffraction (XRD)\\u000a and thermal stability by thermogravimetric analysis (TG). The nanofibers were

Ana Carolina Corrêa; Eliangela de Morais Teixeira; Luiz Antonio Pessan; Luiz Henrique Capparelli Mattoso

2010-01-01

304

Enzymatic Hydrolysis of Cellulosic Biomass  

SciTech Connect

Biological conversion of cellulosic biomass to fuels and chemicals offers the high yields to products vital to economic success and the potential for very low costs. Enzymatic hydrolysis that converts lignocellulosic biomass to fermentable sugars may be the most complex step in this process due to substrate-related and enzyme-related effects and their interactions. Although enzymatic hydrolysis offers the potential for higher yields, higher selectivity, lower energy costs, and milder operating conditions than chemical processes, the mechanism of enzymatic hydrolysis and the relationship between the substrate structure and function of various glycosyl hydrolase components are not well understood. Consequently, limited success has been realized in maximizing sugar yields at very low cost. This review highlights literature on the impact of key substrate and enzyme features that influence performance to better understand fundamental strategies to advance enzymatic hydrolysis of cellulosic biomass for biological conversion to fuels and chemicals. Topics are summarized from a practical point of view including characteristics of cellulose (e.g., crystallinity, degree of polymerization, and accessible surface area) and soluble and insoluble biomass components (e.g., oligomeric xylan, lignin, etc.) released in pretreatment, and their effects on the effectiveness of enzymatic hydrolysis. We further discuss the diversity, stability, and activity of individual enzymes and their synergistic effects in deconstructing complex lignocellulosic biomass. Advanced technologies to discover and characterize novel enzymes and to improve enzyme characteristics by mutagenesis, post-translational modification, and over-expression of selected enzymes and modifications in lignocellulosic biomass are also discussed.

Yang, Bin; Dai, Ziyu; Ding, Shi-You; Wyman, Charles E.

2011-08-22

305

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2013 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2013-04-01

306

21 CFR 184.1721 - Sodium acetate.  

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2014-04-01

307

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2012 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2012-04-01

308

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2011 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2011-04-01

309

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2010 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2010-04-01

310

Concentrating aqueous acetate solutions with tertiary amines  

E-print Network

Water may be extracted from aqueous calcium acetate or sodium acetate solutions using low miscibility, low molecular weight tertiary amines, e.g. triethylamine (TEA) and N,N- dietliylmethylaniine (DEMA). This novel extraction technology...

Lee, Champion

2012-06-07

311

Specific and efficient N-propionylation of histones with propionic acid N-hydroxysuccinimide ester for histone marks characterization by LC-MS.  

PubMed

Histones participate in epigenetic regulation via a variety of dynamic posttranslational modifications (PTMs) on them. Mass spectrometry (MS) has become a powerful tool to investigate histone PTMs. With the bottom-up mass spectrometry approach, chemical derivatization of histones with propionic anhydride or deuterated acetic anhydride followed by trypsin digestion was widely used to block the hydrophilic lysine residues and generate compatible peptides for LC-MS analysis. However, certain severe side reactions (such as acylation on tyrosine or serine) caused by acid anhydrides will lead to a number of analytical issues such as reducing results accuracy and impairing the reproducibility and sensitivity of MS analysis. As an alternative approach, we report a novel derivatization method that utilizes N-hydroxysuccinimide ester to specifically and efficiently derivatize both free and monomethylated amine groups in histones. A competitive inhibiting strategy was implemented in our method to effectively prevent the side reactions. We demonstrated that our method can achieve excellent specificity and efficiency for histones derivatization in a reproducible manner. Using this derivatization method, we succeeded to quantitatively profile the histone PTMs in KMS11 cell line with selective knock out of translocated NSD2 allele (TKO) and the original parental KMS11 cell lines (PAR) (NSD2, a histone methyltransferase that catalyzes the histone H3 K36 methylation), which revealed a significant crosstalk between H3 protein K27 methylation and adjacent K36 methylation. PMID:23339652

Liao, Rijing; Wu, Haiping; Deng, Haibing; Yu, Yanyan; Hu, Min; Zhai, Huili; Yang, Pengyuan; Zhou, Shaolian; Yi, Wei

2013-02-19

312

Micromechanics and poroelasticity of hydrated cellulose networks.  

PubMed

The micromechanics of cellulose hydrogels have been investigated using a new rheological experimental approach, combined with simulation using a poroelastic constitutive model. A series of mechanical compression steps at different strain rates were performed as a function of cellulose hydrogel thickness, combined with small amplitude oscillatory shear after each step to monitor the viscoelasticity of the sample. During compression, bacterial cellulose hydrogels behaved as anisotropic materials with near zero Poisson's ratio. The micromechanics of the hydrogels altered with each compression as water was squeezed out of the structure, and microstructural changes were strain rate-dependent, with increased densification of the cellulose network and increased cellulose fiber aggregation observed for slower compressive strain rates. A transversely isotropic poroelastic model was used to explain the observed micromechanical behavior, showing that the mechanical properties of cellulose networks in aqueous environments are mainly controlled by the rate of water movement within the structure. PMID:24784575

Lopez-Sanchez, P; Rincon, Mauricio; Wang, D; Brulhart, S; Stokes, J R; Gidley, M J

2014-06-01

313

Comparison of the effects of salmeterol/fluticasone propionate with fluticasone propionate on airway physiology in adults with mild persistent asthma  

PubMed Central

Background This study compared the effect of inhaled fluticasone propionate (FP) with the combination of salmeterol/fluticasone propionate (SFC) on lung function parameters in patients with mild asthma. Methods Adult patients with mild persistent asthma (? 80% predicted FEV1) receiving 200–500 ?g of BDP or equivalent were randomised to receive either FP 100 ?g or SFC 50/100 ?g twice daily from a Diskus® inhaler for four weeks. The primary outcome was the change from baseline in airway resistance (sRaw) at 12 hrs post dose measured by whole body plethysmography. Impulse oscillometry and spirometry were also performed. Results A comparison of the geometric mean sRaw at 12 hrs post dose in the SFC group to the FP group gave a ratio of 0.76 (0.66 – 0.89, p < 0.001) at week 2 and 0.81 (0.71 – 0.94, p = 0.006) at week 4. Similarly, significant results in favour of SFC for oscillometry measurements of resistance and reactance were observed. FEV1 was also significantly superior at week 2 in the SFC group (mean difference 0.16L, 95% CI; 0.03 – 0.28, p = 0.015), but not at week 4 (mean difference 0.17L, 95% CI -0.01 – 0.34, p = 0.060). Conclusion SFC is superior to FP in reducing airway resistance in mild asthmatics with near normal FEV1 values. This study provides evidence that changes in pulmonary function in patients with mild asthma are detected more sensitively by plethysmography compared to spirometry Trial registration number NCT00370591. PMID:17629923

Houghton, Catherine M; Lawson, Naomi; Borrill, Zoe L; Wixon, Claire L; Yoxall, Sally; Langley, Stephen J; Woodcock, Ashley; Singh, Dave

2007-01-01

314

Bioengineering cellulose-hemicellulose networks in plants  

Microsoft Academic Search

The interactions between cellulose and hemicellulose in the cell walls are important in the industrial application of the cellulose (natural) fibres. We strive to modify these interactions (i<\\/span>) by interfering with cellulose biosynthesis and (ii) by direct interference of the interactions through the use of carbohydrate binding modules (CBMs<\\/span>). Additionally, we strive to establish a link between the

Olawole O. Obembe

2006-01-01

315

Cellulose wet wiper sheets prepared with cationic polymer and carboxymethyl cellulose using a papermaking technique  

Microsoft Academic Search

Carboxymethyl cellulose (CMC)-rich cellulose sheets were prepared with a cationic retention aid, poly[N,N,N-trimethyl-N-(2-methacryloxyethyl)ammonium chloride] (PTMMAC), using a papermaking technique. When 5% PTMMAC and 5% CMC were added to\\u000a cellulose slurries, approximately 94% of the polymers were retained in the sheets by formation of polyion complexes between\\u000a the two polymers. When the PTMMAC\\/CMC\\/cellulose sheets were soaked in solutions consisting of ethanol,

Takehiko Uematsu; Yoshiaki Matsui; Shusuke Kakiuchi; Akira Isogai

2011-01-01

316

Novel bioactive amino-functionalized cellulose nanofibers.  

PubMed

Amino-cellulose-based nanofibers are prepared by electrospinning of blended solutions of 6-deoxy-6-trisaminoethyl-amino (TEAE) cellulose and polyvinyl alcohol (PVA). The TEAE cellulose with a degree of substitution of 0.67 is synthesized via a nucleophilic displacement reaction starting from cellulose-p-toluenesulfonic acid ester. Several solution characteristics such as polymer concentration, electrical conductivity, and surface tension as well as setup parameters are investigated to optimize the ability of nanofiber formation. These parameters are evaluated using the rheological studies of the solutions. The nanofibers obtained are characterized by scanning electron microscopy (SEM) and show a high antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae. PMID:24151239

Roemhild, Katrin; Wiegand, Cornelia; Hipler, Uta-Christina; Heinze, Thomas

2013-11-01

317

Synergistic effect of delignification and treatment with the ionic liquid 1-ethyl-3-methylimidazolium acetate on enzymatic digestibility of poplar wood.  

PubMed

This study examined the effects of removing key recalcitrance factors by ionic liquid (IL) treatment on the cellulase digestibility of poplar wood. Ground biomass was subjected to chlorite delignification and IL (1-ethyl-3-methylimidazolium acetate) treatment alone or in combination. The compositional and structural features of differentially treated biomass samples and their hydrolysis performance at various cellulase loadings were investigated. IL treatment caused minor compositional changes but drastically decreased cellulose crystallinity; in particular, when administered after delignification, an X-ray diffractogram similar to that of cellulose II polymorph was observed, suggesting that in the absence of lignin, the cellulose was dissolved in the IL and regenerated in water with a polymorphic transformation. The structural changes induced by the combined delignification-IL treatment facilitated the enzymatic hydrolysis of cellulose; the biomass could be fully degraded within 72 h by 4 FPU of cellulase per gram glucan, with cellobiose degradation being the rate-limiting step. PMID:24755318

Wu, Long; Kumagai, Akio; Lee, Seung-Hwan; Endo, Takashi

2014-06-01

318

Effect of Topical Steroid (0.05% Clobetasol Propionate) Treatment in Children With Severe Phimosis  

PubMed Central

Purpose We report our experience with the use of a topical steroid, 0.05% clobetasol propionate, for the treatment of phimosis with clinical complications. Materials and Methods This was a retrospective analysis of the clinical outcomes of all patients presenting with phimosis to a single institution during the time period from October 2008 to May 2012. A total of 88 patients who had a Kikiros retractability grade of 4 or 5 and phimosis-associated clinical complications, such as ballooning of the prepuce, balanoposthitis, or a history of urinary tract infection (UTI), were instructed to apply 0.05% clobetasol propionate cream to the slightly retracted foreskin and to massage gently while retracting the foreskin. The efficacy of treatment was evaluated at 4 weeks from the initiation of therapy. Results A total of 60 of the 88 patients (68.2%) showed a complete response (i.e., full retraction of the foreskin) to the therapy. The phimotic ring disappeared in 25 of the 88 patients (28.4%) after treatment. Patients who had a history of balanoposthitis, smegma, ballooning of the prepuce, or UTI showed significantly poorer improvement in preputial retraction (p<0.001, p<0.001, p<0.001, and p=0.02, respectively) and phimotic ring disappearance (p<0.001, p=0.001, p<0.001, and p=0.001, respectively) after treatment. No significant local or systemic side effects were associated with the administration of topical steroids. Conclusions Topical application of 0.05% clobetasol propionate cream and skin stretching is a safe, simple, and effective procedure with no significant side effects for severe phimosis in prepubertal boys. PMID:24044098

Lee, Chan Ho

2013-01-01

319

Monitoring of clobetasol propionate and betamethasone dipropionate as undeclared steroids in cosmetic products manufactured in Korea.  

PubMed

Some cosmetic products manufactured in Korea have been suspected to contain anti-inflammatory corticosteroids, such as clobetasol propionate and betamethasone dipropionate, for the treatment of eczema, seborrhea and psoriasis, without any indication on the label of the cosmetic products. Due to their severe side effects, such as permanent skin atopy, these two corticosteroids in cosmetic products need to be monitored from a forensic point of view. Cosmetic product samples (number of samples=47) of manufacturers charged by consumers have been collected in local and online markets of Korea, and they were validated and analyzed by a simple high performance liquid chromatography (HPLC) method with ultraviolet diode array (UV-DAD). LC-MS/MS and LC-MS were used to confirm these steroids in cosmetic samples with diagnostic ions (m/z) and isotope ratio. Linearity was studied with 0.5-10?g/mL range in both steroids. Good correlation coefficients (r(2)?0.999) were found, and their limits of quantifications were 0.59?g/mL and 0.66?g/mL in clobetasol propionate and betamethasone dipropionate, respectively. At three different concentrations spanning the linear dynamic ranges, mean recoveries were always higher than 93%, and precisions for intra-day and inter-day analyses were both less than 3.5%. The results show 32-96.4?g/g levels of clobetasol propionate in five different cosmetic products. Also, betamethasone dipropionate in a sample was monitored at the level of 195.1?g/g. This fact reveals that some manufacturers have added these steroids in their cosmetic products to advertise the treatment effect for skin atopy. Thus, these cosmetic products need to be monitored carefully, and ultimately removed from the market. PMID:21474261

Nam, Yun Sik; Kwon, Il Keun; Lee, Kang-Bong

2011-07-15

320

16 CFR 501.6 - Cellulose sponges, irregular dimensions.  

Code of Federal Regulations, 2010 CFR

...false Cellulose sponges, irregular dimensions. 501.6 Section 501.6 Commercial...6 Cellulose sponges, irregular dimensions. Variety packages of cellulose sponges of irregular dimensions, are exempted from the...

2010-01-01

321

16 CFR 501.6 - Cellulose sponges, irregular dimensions.  

Code of Federal Regulations, 2011 CFR

...false Cellulose sponges, irregular dimensions. 501.6 Section 501.6 Commercial...6 Cellulose sponges, irregular dimensions. Variety packages of cellulose sponges of irregular dimensions, are exempted from the...

2011-01-01

322

Isolation of levoglucosan from pyrolysis oil derived from cellulose  

DOEpatents

High purity levoglucosan is obtained from pyrolysis oil derived from cellulose by: mixing pyrolysis oil with water and a basic metal hydroxide, oxide, or salt in amount sufficient to elevate pH values to a range of from about 12 to about 12.5, and adding an amount of the hydroxide, oxide, or salt in excess of the amount needed to obtain the pH range until colored materials of impurities from the oil are removed and a slurry is formed; drying the slurry azeotropically with methyl isobutyl ketone solvent to form a residue, and further drying the residue by evaporation; reducing the residue into a powder; continuously extracting the powder residue with ethyl acetate to provide a levoglucosan-rich extract; and concentrating the extract by removing ethyl acetate to provide crystalline levoglucosan. Preferably, Ca(OH)[sub 2] is added to adjust the pH to the elevated values, and then Ca(OH)[sub 2] is added in an excess amount needed. 3 figures.

Moens, L.

1994-12-06

323

A novel kinetic model for polysaccharide dissolution during atmospheric acetic acid pretreatment of sugarcane bagasse.  

PubMed

Acetic acid (AcH) pretreatment of sugarcane bagasse with the catalysis of sulfuric acid (SA) could greatly enhance the enzymatic digestibility of cellulose. However, polysaccharide dissolution happened inevitably during the pretreatment. It was found that the simplest model, which assumes that the total polysaccharides were reactive to be dissolved, could not well describe the kinetic behavior of polysaccharide dissolution. A novel pseudo-homogenous kinetic model was thus developed by introducing a parameter termed as "potential dissolution degree" (?(d)) based on the multilayered structure of cell wall. It was found that solid xylan and glucan dissolutions were a first-order reaction with respect to the dissolvable fraction. Due to the delignification action of AcH, polysaccharide dissolutions were enhanced in AcH media compared with those in aqueous system. Acetylizations of cellulose and sugars were also observed, and AcH concentration showed a significant influence on the degree of acetylization. PMID:24215769

Zhao, Xuebing; Morikawa, Yuichi; Qi, Feng; Zeng, Jing; Liu, Dehua

2014-01-01

324

Orally inhaled fluticasone propionate improved chronic rhinosinusitis with co-morbid asthma: report of a case.  

PubMed

Chronic rhinosinusitis and asthma are expressions of airway inflammatory diseases that frequently coexist, especially in the case of adult-onset asthma. Both conditions have similar pathological features, while one affects the upper airways and the other the lower airways. Whether the treatment of bronchial inflammation affects the severity of sinus disease remains an unanswered question. We report a case of refractory chronic rhinosinusitis with co-morbid adult-onset asthma that effectively improved upon treatment with a daily dose of 200 ?g (100 ?g b.i.d.) of inhaled fluticasone propionate (FP). PMID:23517399

Nonaka, Manabu; Tanaka, Yukako; Pawankar, Ruby; Yoshihara, Toshio

2013-03-01

325

Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates.  

PubMed

The potential of microcristaline cellulose as sorbent in the separation of eight compounds: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), procyanidin B1 and procyanidin B2 was studied. Cellulose HPTLC plates prewashed in water (not necessary, when water was used as developing solvent) and dried with a hair dryer, bandwise application and development in horizontal developing chamber (sandwich configuration) gave the best results. Detection was performed using vanillin-H3PO4 reagent. Four new developing solvent systems were proposed: water, 1-propanol-water (20:80, v/v), 1-propanol-water-acetic acid (4:2:1, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v), and at least two of them were needed for the differentiation between all eight compounds. Surprisingly, water enabled the separation of epimers C from EC and GC from EGC, as well as the dimers procianidin B1 and B2. Additionally, C, EGC, B1 and B2 were separated from all the other compounds. The best choice for developing solvent is given for each of the studied compounds. The best separation of the five main catechins (EC, GC, EGC, ECg, EGCg) present in green tea extract was achieved using 1-propanol-water-acetic acid (20:80:1, v/v). The chromatograms of oak bark extract developed in solvents with higher water content (1-propanol-water (1:4, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v)) showed less bands than chromatograms developed in solvents with higher organic modifier content (e.g. 1-propanol-water-acetic acid (4:2:1, v/v)). It was proved that such behavior was due to the presence of procyanidins beside the main component catechin. PMID:16001555

Vovk, Irena; Simonovska, Breda; Vuorela, Heikki

2005-06-10

326

Surface modification of natural fibers using bacteria: depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites.  

PubMed

Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of natural fibers by utilizing bacteria ( Acetobacter xylinum) to deposit nanosized bacterial cellulose around natural fibers, which enhances their adhesion to renewable polymers. This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation. The modified fibers were characterized by scanning electron microscopy, single fiber tensile tests, X-ray photoelectron spectroscopy, and inverse gas chromatography to determine their surface and mechanical properties. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate and poly(L-lactic acid) was quantified using the single fiber pullout test. PMID:18491942

Pommet, Marion; Juntaro, Julasak; Heng, Jerry Y Y; Mantalaris, Athanasios; Lee, Adam F; Wilson, Karen; Kalinka, Gerhard; Shaffer, Milo S P; Bismarck, Alexander

2008-06-01

327

Cellulose Acetate Replica Cleaning Study of Genesis Non-Flight Sample 3CZ00327  

NASA Technical Reports Server (NTRS)

The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We are working interactively with the community of scientists analyzing Genesis samples, using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. That is, we are evaluating the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

2014-01-01

328

Mechanical response of PHB- and cellulose acetate natural fiber-reinforced composites for construction applications  

Microsoft Academic Search

Biobased composites are being evaluated for construction applications where wood or petroleum-based composites are currently used. The biobased composites studied are made from biopolymers and plant-based fibers and have been demonstrated to rapidly biodegrade in anaerobic conditions to methane thereby reducing construction-related landfill waste and producing a useful end product, namely fuel for energy or feedstock to grow more biopolymer.

S. J. Christian; S. L. Billington

2011-01-01

329

The quantification of oxygen toxicity by the technique of cellulose acetate electrophoresis of rat serum proteins  

E-print Network

Proteins. (December 1979) Marcia Wagner Barker, B. S. , Southwestern at Memphis Chairman of Advisory Committee: Dr. William P. Fife Exposure to hyperbaric oxygen is known to cause pulmonary damage, central nervous system dysfunctions, circulatory.... , Equivalent Pressure, for 24 or 48 Hours. . 71 LIST OF ABBREVIATIONS ata ? atmospheres, absolute C. N. S. ? central nervous system f. s. w. - feet of sea water GABA ? gamma-aminobutyric acid HBO ? hyperbaric oxygen OHP ? oxygen at high pressure psia...

Barker, Marcia Wagner

2012-06-07

330

Anodically generated cobalt(III) acetate as reagent for coulometric titrations in acetic acid  

Microsoft Academic Search

Summary Conditions for the anodic generation of cobalt(III) acetate with high current efficiency in non-aqueous solutions of potassium acetate in acetic acid have been investigated. The presence of water or acetic anhydride in the anolyte diminishes the amount of the generated oxidant. The stability of the generated cobalt(III) acetate solution is decreased in the presence of water and at elevated

T. J. Pastor; I. ?iri?

1985-01-01

331

Domain structure of cellulose triacetate  

NASA Astrophysics Data System (ADS)

The topology of the surface of thin films obtained from cellulose triacetate solutions has been studied using electron microscopy. The domain structure of the physical network of macromolecules (percolation cluster) with the maximum size L ? 30 nm of regions with a local orientational order has been established. With an increase in the volume fraction ? of the cluster to the critical value ? = 0.91, repacking of domains takes place, which is connected with a decrease in the parameter ?, L doubling bifurcation of the size L, and formation of regions of long-range orientational order: the mesophase of the polymer.

Novikov, D. V.; Krasovskii, A. N.; Mnatsakanov, S. S.

2012-02-01

332

Ethanol from municipal cellulosic wastes  

NASA Astrophysics Data System (ADS)

This paper addresses the use of municipal cellulosic wastes as a feedstock for producing ethanol fuels, and describes the application of enzymatic hydrolysis technology for their production. The concept incorporates recent process technology developments within the framework of an existing industry familiar with large-scale ethanol fermentation (the brewing industry). Preliminary indications are that the cost of producing ethanol via enzymatic hydrolysis in an existing plant with minimal facility modifications (low capital investment) can be significantly less than that of ethanol from grain fermentation.

Parker, A. J., Jr.; Timbario, T. J.; Mulloney, J. A., Jr.

333

Biomimetic mineralisation of apatites on Ca 2+ activated cellulose templates  

Microsoft Academic Search

We investigated the activation of regenerated cellulose 2D model thin films and 3D fabric templates with calcium dihydroxide. The Langmuir–Blodgett (LB) film technique was applied for manufacturing of the model thin films using a trimethylsilyl derivative of cellulose (TMS-cellulose). Regenerated cellulose films were obtained by treating the TMS-cellulose LB-films with hydrochloric acid vapours. For 3D templates, regenerated cellulose fabrics (Lyocell®)

Peter Cromme; Cordt Zollfrank; Lenka Müller; Frank A. Müller; Peter Greil

2007-01-01

334

Extraction and dissolution of cellulose from nypa fruit husk for nanofibers fabrication  

NASA Astrophysics Data System (ADS)

In this study, cellulose was extracted by alkali and acid protocols from nypa fruit husk, the agricultural waste in order to produce nanofiber. In acid protocol, the pretreated sample was hydrolyzed with 10 % and 17 % sodium hydroxide (NaOH), and then refluxed using a mixture of sodium chlorite (NaClO2) and acetic acid (CH3COOH). Alkali protocol was a reverse process of acid protocol where the pretreated sample was refluxed and then hydrolyzed. The celluloses from both protocols were characterized and compared. The cellulose with high purity and crystallinity was then dissolved in NaOH/urea aqueous solution to prepare for electrospinning. In terms of yield based on mass, acid protocol is higher. However, since the celulose from the alkali protocol is pure, fibril and with low crystallinity, it was chosen for dissolution to be electrospun into nanofiber. Since the formation of nanofiber is very much affected by shear viscosity, few compositions of cellulose solution was prepared for further investigation.

Fauzee, Siti Norfatihah; Othaman, Rizafizah

2013-11-01

335

The preparation of graft copolymers of cellulose and cellulose derivatives using ATRP under homogeneous reaction conditions.  

PubMed

In this comprehensive review, we report on the preparation of graft-copolymers of cellulose and cellulose derivatives using atom transfer radical polymerization (ATRP) under homogeneous conditions. The review is divided into four sections according to the cellulosic material that is graft-copolymerised; (i) cellulose, (ii) ethyl cellulose, (iii) hydroxypropyl cellulose and (iv) other cellulose derivatives. In each section, the grafted synthetic polymers are described as well as the methods used for ATRP macro-initiator formation and graft-copolymerisation. The physical properties of the graft-copolymers including their self-assembly in solution into nanostructures and their stimuli responsive behaviour are described. Potential applications of the self-assembled graft copolymers in areas such as nanocontainers for drug delivery are outlined. PMID:25016958

Joubert, Fanny; Musa, Osama M; Hodgson, David R W; Cameron, Neil R

2014-09-22

336

Selective solvent extraction of cellulosic material  

DOEpatents

Cellulosic products having a high hemicellulose to lignin weight ratio are obtained by extracting a cellulosic composition with basic ethanol-water solution having a pH between about 12 and about 14 at a temperature between about 15 and about 70 C and for a time period between about 2 and about 80 hours. 6 figs.

Wang, D.I.C.; Avgerinos, G.C.

1983-07-26

337

Cellulose Triacetate Dielectric Films For Capacitors  

NASA Technical Reports Server (NTRS)

Cellulose triacetate investigated for use as dielectric material in high-energy-density capacitors for pulsed-electrical-power systems. Films of cellulose triacetate metalized on one or both sides for use as substrates for electrodes and/or as dielectrics between electrodes in capacitors. Used without metalization as simple dielectric films. Advantages include high breakdown strength and self-healing capability.

Yen, Shiao-Ping S.; Jow, T. Richard

1994-01-01

338

Composites reinforced with cellulose based fibres  

Microsoft Academic Search

This review article concerning natural and man-made cellulose fibre reinforced plastics, introduces possible applications of this material group. The physical properties of natural fibres are mainly determined by the chemical and physical composition, such as the structure of fibres, cellulose content, angle of fibrils, cross-section, and by the degree of polymerization. Only a few characteristic values, but especially the specific

A. K Bledzki; J Gassan

1999-01-01

339

Selective solvent extraction of cellulosic material  

DOEpatents

Cellulosic products having a high hemicellulose to lignin weight ratio are obtained by extracting a cellulosic composition with basic ethanol-water solution having a pH between about 12 and about 14 at a temperature between about 15.degree. and about 70.degree. C. and for a time period between about 2 and about 80 hours.

Wang, Daniel I. C. (Belmont, MA); Avgerinos, George C. (Newton Center, MA)

1983-01-01

340

Enzymatic Degradation of (Ligno)cellulose.  

PubMed

Glycoside-degrading enzymes play a dominant role in the biochemical conversion of cellulosic biomass into low-price biofuels and high-value-added chemicals. New insight into protein functions and substrate structures, the kinetics of recognition, and degradation events has resulted in a substantial improvement of our understanding of cellulose degradation. PMID:25136976

Bornscheuer, Uwe; Buchholz, Klaus; Seibel, Jürgen

2014-10-01

341

Role of fragmentation activity in cellulose hydrolysis  

Microsoft Academic Search

Most studies of cellulose hydrolysis have been carried out on three components of the cellulolytic systems, viz, endoglucanases, exoglucanases, and cellobiases. Little attention has been paid to the fragmentation activity of certain cellulolytic systems. We have noticed that despite being a more powerful degrader of modified cellulose (CMC), the 7-day grown culture filtrate of Myrothecium verrucaria was less effective than

Abdul Aala Najmus Saqib; Philip John Whitney

2006-01-01

342

Nucleic acids encoding a cellulose binding domain  

DOEpatents

A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 15 figs.

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

1996-03-05

343

Nucleic acids encoding a cellulose binding domain  

DOEpatents

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

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

1996-01-01

344

Molecular Structure of Ethyl acetate  

NSDL National Science Digital Library

Ethyl acetate is a colorless, volatile liquid with a mild and fragrant odor. It is used as solvent in chemistry laboratories but can also be found in many household products such as paints, coatings, and adhesives. The compound is also used in some extraction processes such as decaffeination or purification of antibiotics. It is present in both nail polish and removers. Some synthetic fruit essences may contain this and other esters. Etymologists like to use this solvent for insect collecting as the vapor kill the insect quickly and keep it soft for mounting.

2006-03-08

345

Enterovirus Concentration on Cellulose Membranes  

PubMed Central

Cellulose nitrate membranes were used as one of the adsorbents in concentrating viruses from water. For adsorption to occur, salts were required. With increase in valency of salt, less salt was necessary for enhanced virus adsorption to membranes. Trivalent salts were more effective because they could be used at only 1% the concentration required for divalent salts. Thus, 0.5 mM AlCl3 was as effective as 50 mM MgCl2. For testing 500 gal of water, only 0.24 kg of AlCl3 was required in contrast to 20 kg of MgCl2. Virus could then be eluted from such membranes, having an area of 486 cm2, with 250 ml of pH 11.5 buffer. Lowering the pH of the eluate and adding AlCl3 permitted the virus to be quickly readsorbed on a smaller cellulose membrane, i.e., 4 cm2. Virus for assay was eluted from the small membrane in 1 ml. This procedure has provided the basis for concentrating minute amounts of virus from large volumes of water. PMID:4336660

Wallis, Craig; Henderson, Marilyn; Melnick, Joseph L.

1972-01-01

346

A versatile and robust aerotolerant microbial community capable of cellulosic ethanol production.  

PubMed

The use of microbial communities in the conversion of cellulosic materials to bio-ethanol has the potential to improve the economic competitiveness of this biofuel and subsequently lessen our dependency on fossil fuel-based energy sources. Interactions between functionally different microbial groups within a community can expand habitat range, including the creation of anaerobic microenvironments. Currently, research focussing on exploring the nature of the interactions occurring during cellulose degradation and ethanol production within mixed microbial communities has been limited. The aim of this study was to enrich and characterize a cellulolytic bacterial community, and determine if ethanol is a major soluble end-product. Cellulolytic activity by the community was observed in both non-reduced and pre-reduced media, with ethanol and acetate being major fermentation products. Similar results were obtained when sterile wastewater extract was provided as nutrient. Several community members showed high similarity to Clostridium species with overlapping metabolic capabilities, suggesting clostridial functional redundancy. PMID:23238345

Ronan, Patrick; Yeung, C William; Schellenberg, John; Sparling, Richard; Wolfaardt, Gideon M; Hausner, Martina

2013-02-01

347

Single-cell protein from waste cellulose  

NASA Technical Reports Server (NTRS)

The recycle, reuse, or reclamation of single cell protein from liquid and solid agricultural waste fibers by a fermentation process is reported. It is shown that cellulose comprises the bulk of the fibers at 50% to 55% of the dry weight of the refuse and that its biodegradability is of prime importance in the choice of a substrate. The application of sodium hydroxide followed by heat and pressure serves to de-polymerize and disrupt lignin structure while swelling the cellulose to increase water uptake and pore volume. Some of the lignin, hemi-celluloses, ash, and cellulose of the material is hydrolized and solubilized. Introduction of microorganisms to the substrate fibers mixed with nutrients produces continuous fermentation of cellulose for further protein extraction and purification.

Dunlap, C. E.; Callihan, C. D.

1973-01-01

348

Magnetite particles triggering a faster and more robust syntrophic pathway of methanogenic propionate degradation.  

PubMed

Interspecies electron transfer mechanisms between Bacteria and Archaea play a pivotal role during methanogenic degradation of organic matter in natural and engineered anaerobic ecosystems. Growing evidence suggests that in syntrophic communities electron transfer does not rely exclusively on the exchange of diffusible molecules and energy carriers such as hydrogen or formate, rather microorganisms have the capability to exchange metabolic electrons in a more direct manner. Here, we show that supplementation of micrometer-size magnetite (Fe3O4) particles to a methanogenic sludge enhanced (up to 33%) the methane production rate from propionate, a key intermediate in the anaerobic digestion of organic matter and a model substrate to study energy-limited syntrophic communities. The stimulatory effect most probably resulted from the establishment of a direct interspecies electron transfer (DIET), based on magnetite particles serving as electron conduits between propionate-oxidizing acetogens and carbon dioxide-reducing methanogens. Theoretical calculations revealed that DIET allows electrons to be transferred among syntrophic partners at rates which are substantially higher than those attainable via interspecies H2 transfer. Besides the remarkable potential for improving anaerobic digestion, which is a proven biological strategy for renewable energy production, the herein described conduction-based DIET could also have a role in natural methane emissions from magnetite-rich soils and sediments. PMID:24901501

Cruz Viggi, Carolina; Rossetti, Simona; Fazi, Stefano; Paiano, Paola; Majone, Mauro; Aulenta, Federico

2014-07-01

349

Co-cultivation of Lactobacillus zeae and Veillonella cricetifor the production of propionic acid  

PubMed Central

In this work a defined co-culture of the lactic acid bacterium Lactobacillus zeae?and the propionate producer Veillonella criceti?has been studied in continuous stirred tank reactor (CSTR) and in a dialysis membrane reactor. It is the first time that this reactor type is used for a defined co-culture fermentation. This reactor allows high mixing rates and working with high cell densities, making it ideal for co-culture investigations. In CSTR experiments the co-culture showed over a broad concentration range an almost linear correlation in consumption and production rates to the supply with complex nutrients. In CSTR and dialysis cultures a strong growth stimulation of L. zeae?by V. criceti?was shown. In dialysis cultures very high propionate production rates (0.61 g L-1h-1) with final titers up to 28 g L-1?have been realized. This reactor allows an individual, intracellular investigation of the co-culture partners by omic-technologies to provide a better understanding of microbial communities. PMID:23705662

2013-01-01

350

Co-cultivation of Lactobacillus zeae?and Veillonella cricetifor the production of propionic acid.  

PubMed

: In this work a defined co-culture of the lactic acid bacterium Lactobacillus zeae?and the propionate producer Veillonella criceti?has been studied in continuous stirred tank reactor (CSTR) and in a dialysis membrane reactor. It is the first time that this reactor type is used for a defined co-culture fermentation. This reactor allows high mixing rates and working with high cell densities, making it ideal for co-culture investigations. In CSTR experiments the co-culture showed over a broad concentration range an almost linear correlation in consumption and production rates to the supply with complex nutrients. In CSTR and dialysis cultures a strong growth stimulation of L. zeae?by V. criceti?was shown. In dialysis cultures very high propionate production rates (0.61 g L-1h-1) with final titers up to 28 g L-1?have been realized. This reactor allows an individual, intracellular investigation of the co-culture partners by omic-technologies to provide a better understanding of microbial communities. PMID:23705662

Dietz, David; Sabra, Wael; Zeng, An-Ping

2013-01-01

351

Impact of clobetasol propionate 0.05% spray on health-related quality of life in patients with plaque psoriasis.  

PubMed

Psoriasis causes significant distress and impairment in health-related quality of life (QOL) in afflicted patients. For this reason, QOL is an essential and important measure of treatment outcome in patients with the disease. Clobetasol propionate is a super-highpotent class I topical corticosteroid. The spray formulation is approved for twice-daily use for up to 4 weeks by patients 18 years and older with moderate to severe plaque psoriasis. Data collected from 2,236 patients enrolled in 5 clinical trials demonstrate consistent improvement in QOL measures using multiple instruments. In a randomized, double-blind trial in patients with scalp psoriasis, treatment with clobetasol propionate 0.05% spray produced significantly greater improvement in QOL compared with vehicle, as measured by the Scalpdex QOL instrument. In another randomized trial in patients with moderate to severe plaque psoriasis, clobetasol propionate 0.05% spray produced significantly greater reductions in mean affected body surface area and significantly greater improvements in QOL, as measured by the Dermatology Life Quality Index (DLQI), compared with a 0.05% foam formulation. When compared with calcipotriene/betamethasone dipropionate ointment, clobetasol propionate 0.05% spray produced greater rates of lesion clearance and similar improvement in QOL scores after 2 or 4 weeks of treatment. When clobetasol propionate 0.05% spray was used as monotherapy or as an add-on therapy for 4 weeks in a large, observational trial, approximately 80% of patients experienced consistent and significant improvement in QOL on 2 separate, validated QOL instruments (DLQI and the Koo-Menter Psoriasis Index). In conclusion, clobetasol propionate 0.05% spray is an efficacious and safe treatment for plaque psoriasis and produces significant improvement in QOL for affected patients. PMID:23135087

Menter, M Alan; Caveney, Scott W; Gottschalk, Ronald W

2012-11-01

352

Metaproteomics of cellulose methanisation under thermophilic conditions reveals a surprisingly high proteolytic activity.  

PubMed

Cellulose is the most abundant biopolymer on Earth. Optimising energy recovery from this renewable but recalcitrant material is a key issue. The metaproteome expressed by thermophilic communities during cellulose anaerobic digestion was investigated in microcosms. By multiplying the analytical replicates (65 protein fractions analysed by MS/MS) and relying solely on public protein databases, more than 500 non-redundant protein functions were identified. The taxonomic community structure as inferred from the metaproteomic data set was in good overall agreement with 16S rRNA gene tag pyrosequencing and fluorescent in situ hybridisation analyses. Numerous functions related to cellulose and hemicellulose hydrolysis and fermentation catalysed by bacteria related to Caldicellulosiruptor spp. and Clostridium thermocellum were retrieved, indicating their key role in the cellulose-degradation process and also suggesting their complementary action. Despite the abundance of acetate as a major fermentation product, key methanogenesis enzymes from the acetoclastic pathway were not detected. In contrast, enzymes from the hydrogenotrophic pathway affiliated to Methanothermobacter were almost exclusively identified for methanogenesis, suggesting a syntrophic acetate oxidation process coupled to hydrogenotrophic methanogenesis. Isotopic analyses confirmed the high dominance of the hydrogenotrophic methanogenesis. Very surprising was the identification of an abundant proteolytic activity from Coprothermobacter proteolyticus strains, probably acting as scavenger and/or predator performing proteolysis and fermentation. Metaproteomics thus appeared as an efficient tool to unravel and characterise metabolic networks as well as ecological interactions during methanisation bioprocesses. More generally, metaproteomics provides direct functional insights at a limited cost, and its attractiveness should increase in the future as sequence databases are growing exponentially. PMID:23949661

Lü, Fan; Bize, Ariane; Guillot, Alain; Monnet, Véronique; Madigou, Céline; Chapleur, Olivier; Mazéas, Laurent; He, Pinjing; Bouchez, Théodore

2014-01-01

353

Stable coexistence of five bacterial strains as a cellulose-degrading community.  

PubMed

A cellulose-degrading defined mixed culture (designated SF356) consisting of five bacterial strains (Clostridium straminisolvens CSK1, Clostridium sp. strain FG4, Pseudoxanthomonas sp. strain M1-3, Brevibacillus sp. strain M1-5, and Bordetella sp. strain M1-6) exhibited both functional and structural stability; namely, no change in cellulose-degrading efficiency was observed, and all members stably coexisted through 20 subcultures. In order to investigate the mechanisms responsible for the observed stability, "knockout communities" in which one of the members was eliminated from SF356 were constructed. The dynamics of the community structure and the cellulose degradation profiles of these mixed cultures were determined in order to evaluate the roles played by each eliminated member in situ and its impact on the other members of the community. Integration of each result gave the following estimates of the bacterial relationships. Synergistic relationships between an anaerobic cellulolytic bacterium (C. straminisolvens CSK1) and two strains of aerobic bacteria (Pseudoxanthomonas sp. strain M1-3 and Brevibacillus sp. strain M1-5) were observed; the aerobes introduced anaerobic conditions, and C. straminisolvens CSK1 supplied metabolites (acetate and glucose). In addition, there were negative relationships, such as the inhibition of cellulose degradation by producing excess amounts of acetic acid by Clostridium sp. strain FG4, and growth suppression of Bordetella sp. strain M1-6 by Brevibacillus sp. strain M1-5. The balance of the various types of relationships (both positive and negative) is thus considered to be essential for the stable coexistence of the members of this mixed culture. PMID:16269746

Kato, Souichiro; Haruta, Shin; Cui, Zong Jun; Ishii, Masaharu; Igarashi, Yasuo

2005-11-01

354

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

SciTech Connect

A novel class of thin-film nanofibrous composite (TFNC) membrane consisting of a cellulose barrier layer, a nanofibrous mid-layer scaffold, and a melt-blown non-woven substrate was successfully fabricated and tested as an ultrafiltration (UF) filter to separate an emulsified oil and water mixture, a model bilge water for on-board ship bilge water purification. Two ionic liquids: 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate, were chosen as the solvent to dissolve cellulose under mild conditions. The regenerated cellulose barrier layer exhibited less crystallinity (determined by wide-angle X-ray diffraction, WAXD) than the original cotton linter pulps, but good thermal stability (determined by thermal gravimetric analysis, TGA). The morphology, water permeation, and mechanical stability of the chosen TFNCmembranes were thoroughly investigated. The results indicated that the polyacrylonitrile (PAN) nanofibrous scaffold was partially imbedded in the cellulose barrier layer, which enhanced the mechanical strength of the top barrier layer. The permeation flux of the cellulose-based TFNCmembrane was significantly higher (e.g. 10x) than comparable commercial UFmembranes (PAN10 and PAN400, Sepro) with similar rejection ratios for separation of oil/water emulsions. The molecular weight cut-off (MWCO) of TFNC membranes with cellulose barrier layer was evaluated using dextran feed solutions. The rejection was found to be higher than 90% with a dextran molecular weight of 2000 KDa, implying that the nominal pore size of the membrane was less than 50 nm. High permeation flux was also observed in the filtration of an emulsified oil/water mixture as well as of a sodium alginate aqueous solution, while high rejection ratio (above 99.5%) was maintained after prolonged operation. A variation of the barrier layer thickness could dramatically affect the permeation flux and the rejection ratio of the TFNCmembranes, while different sources of cellulose, ionic liquids, and non-woven supports did not. As ionic liquids can be recycled and reused without obvious decomposition, the chosen method also demonstrates a benign pathway to fabricate the cellulose barrier layer for other types of membranes.

Ma, H.; Yoon, K; Rong, L; Mao, Y; Mo, Z; Fang, D; Hollander, Z; Gaiteri, J; Hsiao , B; Chu, B

2010-01-01

355

Improvement of cellulose catabolism in Clostridium cellulolyticum by sporulation abolishment and carbon alleviation  

SciTech Connect

Background Clostridium cellulolyticum can degrade lignocellulosic biomass, and ferment the soluble sugars to produce valuable chemicals such as lactate, acetate, ethanol and hydrogen. However, the cellulose utilization efficiency of C. cellulolyticum still remains very low, impeding its application in consolidated bioprocessing for biofuels production. In this study, two metabolic engineering strategies were exploited to improve cellulose utilization efficiency, including sporulation abolishment and carbon overload alleviation. Results The spo0A gene at locus Ccel_1894, which encodes a master sporulation regulator was inactivated. The spo0A mutant abolished the sporulation ability. In a high concentration of cellulose (50 g/l), the performance of the spo0A mutant increased dramatically in terms of maximum growth, final concentrations of three major metabolic products, and cellulose catabolism. The microarray and gas chromatography mass spectrometry (GC-MS) analyses showed that the valine, leucine and isoleucine biosynthesis pathways were up-regulated in the spo0A mutant. Based on this information, a partial isobutanol producing pathway modified from valine biosynthesis was introduced into C. cellulolyticum strains to further increase cellulose consumption by alleviating excessive carbon load. The introduction of this synthetic pathway to the wild-type strain improved cellulose consumption from 17.6 g/l to 28.7 g/l with a production of 0.42 g/l isobutanol in the 50 g/l cellulose medium. However, the spo0A mutant strain did not appreciably benefit from introduction of this synthetic pathway and the cellulose utilization efficiency did not further increase. A technical highlight in this study was that an in vivo promoter strength evaluation protocol was developed using anaerobic fluorescent protein and flow cytometry for C. cellulolyticum. Conclusions In this study, we inactivated the spo0A gene and introduced a heterologous synthetic pathway to manipulate the stress response to heavy carbon load and accumulation of metabolic products. These findings provide new perspectives to enhance the ability of cellulolytic bacteria to produce biofuels and biocommodities with high efficiency and at low cost directly from lignocellulosic biomass.

Li, Yongchao [ORNL] [ORNL; Xu, Tao [University of Oklahoma, Norman] [University of Oklahoma, Norman; Tschaplinski, Timothy J [ORNL] [ORNL; Engle, Nancy L [ORNL] [ORNL; Graham, David E [ORNL] [ORNL; He, Zhili [University of Oklahoma, Norman] [University of Oklahoma, Norman; Zhou, Jizhong [University of Oklahoma, Norman] [University of Oklahoma, Norman

2014-01-01

356

Evaluation of cellulose and carboxymethyl cellulose/poly(vinyl alcohol) membranes.  

PubMed

Cellulose was isolated from rice straw and converted to carboxymethyl cellulose (CMC). Both polymers were crosslinked with poly(vinyl alcholo) (PVA). The physical properties of the resulting membranes were characterized by FT-IR, TGA, DSC and SEM. The cellulose and CMC were first prepared from bleached rice straw pulp. The infrared spectroscopy of the resulting polymer membranes indicated a decrease in the absorbance of the OH group at 3300-3400 cm(-1), which is due to bond formation with either the cellulose or CMC with the PVA. The thermal stability of PVA/cellulose and PVA/CMC membranes was lower than PVA membrane. The surface of the resulting polymer membranes showed smooth surface in case of the PVA/CMC membrane and rough surface in case of the PVA/cellulose membrane. Desalination test, using 0.2% NaCl, showed that pure PVA membranes had no effect while membranes containing either cellulose or CMC as filler were able to decrease the content of the NaCl from the solution by 25% and 15%, respectively. Transport properties, including water and chloroform vapor were studied. The moisture transport was reduced by the presence of both cellulose and CMC. Moreover, the membranes containing cellulose and CMC showed significantly reduced flux compared to the pure PVA. The water sorption, solubility and soaking period at different pH solutions were also studied and showed that the presence of both cellulose and CMC influences the properties. PMID:23618287

Ibrahim, Maha M; Koschella, Andreas; Kadry, Ghada; Heinze, Thomas

2013-06-01

357

Effects of Dilute Acid Pretreatment on Cellulose DP and the Relationship Between DP Reduction and Cellulose Digestibility  

SciTech Connect

The degree of polymerization(DP) of cellulose is considered to be one of the most important properties affecting the enzymatic hydrolysis of cellulose. Various pure cellulosic and biomass materials have been used in a study of the effect of dilute acid treatment on cellulose DP. A substantial reduction in DP was found for all pure cellulosic materials studied even at conditions that would be considered relatively mild for pretreatment. The effect of dilute acid pretreatment on cellulose DP in biomass samples was also investigated. Corn stover pretreated with dilute acid under the most optimal conditions contained cellulose with a DPw in the range of 1600{approx}3500, which is much higher than the level-off DP(DPw 150{approx}300) obtained with pure celluloses. The effect of DP reduction on the saccharification of celluloses was also studied. From this study it does not appear that cellulose DP is a main factor affecting cellulose saccharification.

Wang, W.; Chen, X.; Tucker, M.; Himmel, M. E.; Johnson, D. K.

2012-01-01

358

PROPIONATE METABOLISM IN DIFFERENT SPECIES OF RUMINANTS K.W.J. WAHLE W.R.H. DUNCAN G.A. GARTON  

E-print Network

PROPIONATE METABOLISM IN DIFFERENT SPECIES OF RUMINANTS K.W.J. WAHLE W.R.H. DUNCAN G.A. GARTON not (table 1, c.f. Duncan and Garton, 1978). The capacity of sheep and goats to metabolize the amounts of propionate derived from the ruminal fermenta- tion of cereal starch appears to be impaired, resulting

Paris-Sud XI, Université de

359

Nanocrystalline cellulose for optical encryption  

NASA Astrophysics Data System (ADS)

Nanocrystalline cellulose (NCC) exhibits unusual optical properties that make it of interest for hierarchical optical encryption in nanostructured films. The color-travel phenomenon of iridescence is exhibited by NCC when cast as a film from chiral nematic aqueous phase suspensions of the nanocrystals. "Iridescence by self-assembly" has potential for overt encryption as an anti-counterfeiting measure. It also offers an intrinsic level of covert encryption by reflecting leftcircularly polarized light. We show that addition of a UV sensitive dye adds another level of (covert) encryption, and that specially prepared films manifest a rare form of optical non-reciprocity that does not require the application of an external field. Chirality parameters and stokes vector analyses suggest a simple authentication scheme. The method uses a UV light source and a circular polarizer in conjunction with an iridescent feature that can be verified by the eye or by chiral spectrometry.

Zhang, Yu Ping; Allahverdyan, Karen; Morse, Timothy; Chodavarapu, Vamsy P.; Kirk, Andrew G.; Galstian, Tigran; Andrews, Mark P.

2014-08-01

360

Solid-, solution-, and gas-state NMR monitoring of ¹³C-cellulose degradation in an anaerobic microbial ecosystem.  

PubMed

Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. ¹³C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and ¹³C-¹³C/¹³C-¹²C isotopomers in the microbial degradation of ¹³C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid. PMID:23899835

Yamazawa, Akira; Iikura, Tomohiro; Shino, Amiu; Date, Yasuhiro; Kikuchi, Jun

2013-01-01

361

Metabolism of steroid acetates by Streptomyces albus.  

PubMed

Fermentation of 16-dehydropregnenolone acetate (1a) with Streptomyces albus yielded 16-dehydropregnenolone (1b) and 16-dehydroprogesterone (IIa). Similar incubation of pregnenolone acetate (Ic) with the strain afforded pregnenolone (Id), progesterone (IIb) and 20 alpha-hydroxy progesterone (IIc) while dehydroepiandrosterone acetate (IIIa) under the conditions was converted to dehydroepiandrosterone (IIIb), androstenedione (IVa) and testosterone (IVc). The strain was also capable of converting testosterone acetate (IVb) having the 17-acetoxy function in the 5-membered D-ring to testosterone (IVc) and androstenedione (IVa). All the products were identified by the application of various chemical and spectrometric techniques. PMID:6708550

Mukherjee, A; Mahato, S B

1984-03-01

362

Positron scattering from vinyl acetate  

NASA Astrophysics Data System (ADS)

Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

2014-09-01

363

Fermentation of cellulose to methane and carbon dioxide by a rumen anaerobic fungus in a triculture with Methanobrevibacter sp. strain RA1 and Methanosarina barkeri  

SciTech Connect

The fermentation of cellulose by a rumen anaerobic fungus in the presence of Methanobrevibacter sp. strain RA1 and Methanosarcina barkeri strain 227 resulted in the formation of 2 mol each of methane and carbon dioxide per mol of hexose fermented. Coculture of the fungus with either Methanobrevibacter sp. or M. barkeri produced 0.6 and 1.3 mol of methane per mol of hexose, respectively. Acetate, formate, ethanol, hydrogen, and lactate, which are major end products of cellulose fermentation by the fungus alone, were either absent or present in very low quantities at the end of the triculture fermentation (less than or equal to 0.08 mol per mol of hexose fermented). During the time course of cellulose fermentation by the triculture, hydrogen was not detected (less than 1 x 10 to the power of -5 atmosphere; less than 0.001 kilopascal) and only acetate exhibited transitory accumulation; the maximum was equivalent to 1.4 mol per mol of hexose at 6 days which was higher than the total acetate yield of 0.73 in the fungus monoculture. The effect of methanogens is interpreted as a shift in the flow of electrons away from the formation of electron sink products lactate and ethanol to methane via hydrogen, favoring an increase in acetate, which is in turn converted to methane and carbon dioxide by M. barkeri. The maximum rate of cellulose degradation in the triculture (3 mg/ml per day) was faster than previously reported for bacterial cocultures and within 16 days degradation was complete. The triculture was used successfully also in the production of methane from cellulose in the plant fibrous materials, sisal (fiber from leaves of Agave sisalona L.) and barley straw leaf.

Mountfort, D.O.; Asher, R.A.; Bauchop, T.

1982-07-01

364

CELLULOSE EXTRACTION FROM PALM KERNEL CAKE USING LIQUID PHASE OXIDATION  

Microsoft Academic Search

Cellulose is widely used in many aspect and industries such as food industry, pharmaceutical, paint, polymers, and many more. Due to the increasing demand in the market, studies and work to produce cellulose are still rapidly developing. In this work, liquid phase oxidation was used to extract cellulose from palm kernel cake to separate hemicellulose, cellulose and lignin. The method

FARM YAN YAN; DUDUKU KRISHNIAH; MARIANI RAJIN; AWANG BONO

365

Colonization of Crystalline Cellulose by Clostridium cellulolyticum ATCC 35319.  

PubMed

Cellulose colonization by Clostridium cellulolyticum was studied by using [methyl-H]thymidine incorporation. The colonization process indicated that a part of the bacterial population was released from cellulose to the liquid phase before binding and colonizing another adhesion site of the cellulose. We postulate that cellulose colonization occurs according to the following process: adhesion, colonization, release, and readhesion. PMID:16349055

Gelhaye, E; Gehin, A; Petitdemange, H

1993-09-01

366

Colonization of Crystalline Cellulose by Clostridium cellulolyticum ATCC 35319  

PubMed Central

Cellulose colonization by Clostridium cellulolyticum was studied by using [methyl-3H]thymidine incorporation. The colonization process indicated that a part of the bacterial population was released from cellulose to the liquid phase before binding and colonizing another adhesion site of the cellulose. We postulate that cellulose colonization occurs according to the following process: adhesion, colonization, release, and readhesion. PMID:16349055

Gelhaye, E.; Gehin, A.; Petitdemange, H.

1993-01-01

367

Production of permeable cellulose triacetate membranes  

DOEpatents

A phase inversion process for the preparation of cellulose triacetate (CTA) and regenerated cellulose membranes is disclosed. Such membranes are useful as supports for liquid membranes in facilitated transport processes, as microfiltration membranes, as dialysis or ultrafiltration membranes, and for the preparation of ion-selective electrodes. The process comprises the steps of preparing a casting solution of CTA in a solvent comprising a mixture of cyclohexanone and methylene chloride, casting a film from the casting solution, and immersing the cast film in a methanol bath. The resulting CTA membrane may then be hydrolyzed to regenerated cellulose using conventional techniques.

Johnson, B.M.

1986-12-23

368

New carboxymethyl cellulose tosylate with low biodeterioration.  

PubMed

Microbial biodegradation and biodeterioration of cellulose based thickeners is a serious problem in industry. A new tosylic ester of carboxymethyl cellulose (TsCMC) was prepared with anhydride of p-toluensulphonic acid. The TsCMC has improved rheological properties, higher viscosity and pseudoplasticity, superior emulsification properties and decreased wettability compared to parental CMC. The biodeterioration of TsCMC was significantly reduced compared to parental CMC or other commercially used modified cellulose thickeners in water based paint industry. Improved rheological properties combined with low biodeterioration make TsCMC a promising new material for industrial applications with a potential to reduce the use of hazardous antimicrobial agents. PMID:25256453

Orehek, Janez; Petek, Klemen; Dogsa, Iztok; Stopar, David

2014-11-26

369

Characterization of a novel cellulose synthesis inhibitor.  

PubMed

The physiological effects of an experimental herbicide and cellulose synthesis inhibitor, N2-(1-ethyl-3-phenylpropyl)-6-(1-fluoro-1-methylethyl)-1,3,5-triazine-2,4-diamine, called AE F150944, are described. In the aminotriazine molecular class, AE F150944 is structurally distinct from other known cellulose synthesis inhibitors. It specifically inhibits crystalline cellulose synthesis in plants without affecting other processes that were tested. The effects of AE F150944 on dicotyledonous plants were tested on cultured mesophyll cells of Zinnia elegans L. cv. Envy, which can be selectively induced to expand via primary wall synthesis or to differentiate into tracheary elements via secondary wall synthesis. The IC50 values during primary and secondary wall synthesis in Z. elegans were 3.91 x 10(-8) M and 3.67 x 10(-9) M, respectively. The IC50 in suspension cultures of the monocot Sorghum halapense (L.) Pers., which were dividing and synthesizing primary walls, was 1.67 x 10(-10) M. At maximally inhibitory concentrations, 18-33% residual crystalline cellulose synthesis activity remained, with the most residual activity observed during primary wall synthesis in Z. elegans. Addition to Z. elegans cells of two other cellulose synthesis inhibitors, 1 microM 2,6-dichlorobenzonitrile and isoxaben, along with AE F150944 did not eliminate the residual cellulose synthesis, indicating little synergy between the three inhibitors. In differentiating tracheary elements, AE F150944 inhibited the deposition of detectable cellulose into patterned secondary wall thickenings, which was correlated with delocalization of lignin as described previously for 2, 6-dichlorobenzonitrile. Freeze-fracture electron microscopy showed that the plasma membrane below the patterned thickenings of AE F150944-treated tracheary elements was depleted of cellulose-synthase-containing rosettes, which appeared to be inserted intact into the plasma membrane followed by their rapid disaggregation. AE F150944 also inhibited cellulose-dependent growth in the rosette-containing alga, Spirogyra pratensis, but it did not inhibit cellulose synthesis in Acetobacter xylinum or Dictyostelium discoideum, both of which synthesize cellulose via linear terminal complexes. Therefore, AE F150944 may inhibit crystalline cellulose synthesis by destabilizing plasma membrane rosettes. PMID:12883883

Kiedaisch, Brett M; Blanton, Richard L; Haigler, Candace H

2003-10-01

370

Cellulose-builder: a toolkit for building crystalline structures of cellulose.  

PubMed

Cellulose-builder is a user-friendly program that builds crystalline structures of cellulose of different sizes and geometries. The program generates Cartesian coordinates for all atoms of the specified structure in the Protein Data Bank format, suitable for using as starting configurations in molecular dynamics simulations and other calculations. Crystalline structures of cellulose polymorphs I?, I?, II, and III(I) of practically any size are readily constructed which includes parallelepipeds, plant cell wall cellulose elementary fibrils of any length, and monolayers. Periodic boundary conditions along the crystallographic directions are easily imposed. The program also generates atom connectivity file in PSF format, required by well-known simulation packages such as NAMD, CHARMM, and others. Cellulose-builder is based on the Bash programming language and should run on practically any Unix-like platform, demands very modest hardware, and is freely available for download from ftp://ftp.iqm.unicamp.br/pub/cellulose-builder. PMID:22419406

Gomes, Thiago C F; Skaf, Munir S

2012-05-30

371

Conversion of cellulose to ethanol by mesophilic bacteria. Progress report and third year budget  

SciTech Connect

Much of our research has dealt with eight strains of obligately anaerobic bacteria that we isolated from various natural environments as described in last year's progress report. These eight strains (referred to as C strains) are strains of mesophilic, spore-forming, rod-shaped bacteria that ferment cellulose with production of ethanol. We determined quantitatively the fermentation products formed by C strains from cellulose and various other carbohydrates. In all cases ethanol was produced, as well as acetate, CO/sub 2/ and H/sub 2/. The C strains utilized, for ethanol production and growth, a variety of cellulosic substrates ranging from paper to alpha-cellulose. Enzymatic assays and growth studies showed that C strains possessed a celluloase system consisting of endoglucanase, exoglucanase, and cellobiase components. Studies indicated that growth substrates have a regulatory effect(s) on components of the cellulase system of the C strains. another experimental approach is aimed at cloning cellobiase, endoglucanase and exoglucanase genes from the C strains into a suitable vector plasmid and, eventually, at introducing the plasmid into cells of Zymomonas mobilis. The objective of this part of our research is to obtain a Z. mobilis strain capable of fermenting cellobiose and/or cellulose. Plasmids that contained DNA inserts were used to transform E. coli C600 recA. E. coli transformants that had acquired the cellobiase gene were obtained by this procedure. At present, we are attempting to introduce into Z. mobilis cells the vector plasmid purified from the E. coli transformants. In another series of experiments, we have used a new selective procedure to isolate four additional strains of mesophilic, obligately anaerobic, cellulolytic bacteria from natural environments.

Canale-Parola, E.

1982-11-24

372

Oxygen17 and proton nuclear magnetic resonance studies on acetic acid exchange processes of the chloride, nitrate, and acetate of nickel(II) in acetic acid  

Microsoft Academic Search

The exchange rates of acetic acid coordinating to nickel(II) chloride, nickel(II) nitrate, and nickel(II) acetate in neat acetic acid and acetic acid\\/dichloromethane-d2 mixtures were measured by the oxygen-17 and proton NMR line-broadening methods. The activation parameters for the acetic acid exchange on these nickel(II) salts were independent of the concentration of acetic acid (HOAc) in the mixed solvents. The first-order

A. Hioki; S. Funahashi; M. Tanaka

1985-01-01

373

EFFECTS OF PRENATAL TESTOSTERONE PROPIONATE AND VINCLOZOLIN ON PERINATAL AND INFANTILE DEVELOPMENT OF MALE AND FEMALE RATS  

EPA Science Inventory

Effects of Prenatal Testosterone Propionate and Vinclozolin on Perinatal and Infantile Development of Male and Female Rats Cynthia Wolf1,2, Jonathan Furr1, Gerald A. LeBlanc2, and L. Earl Gray, Jr.1 1USEPA, NHEERL, RTD, EB, RTP, NC 27711, 2Dept. of Environmental and Molecu...

374

Economic and environmental assessment of propionic acid production by fermentation using different renewable raw materials.  

PubMed

Production of propionic acid by fermentation of glycerol as a renewable resource has been suggested as a means for developing an environmentally-friendly route for this commodity chemical. However, in order to quantify the environmental benefits, life cycle assessment of the production, including raw materials, fermentation, upstream and downstream processing is required. The economic viability of the process also needs to be analysed to make sure that any environmental savings can be realised. In this study an environmental and economic assessment from cradle-to-gate has been conducted. The study highlights the need for a highly efficient bioprocess in terms of product titre (more than 100g/L and productivity more than 2g/(L · h)) in order to be sustainable. The importance of the raw materials and energy production for operating the process to minimize emissions of greenhouse gases is also shown. PMID:24103218

Tufvesson, Pär; Ekman, Anna; Sardari, Roya R R; Engdahl, Kristina; Tufvesson, Linda

2013-12-01

375

Intractable metabolic acidosis in a child with propionic acidemia undergoing liver transplantation -a case report-  

PubMed Central

Propionic acidemia (PA) is a rare autosomal recessive disorder of metabolism caused by deficient activity of the mitochondrial enzyme propionyl-CoA carboxylase. The clinical manifestations are metabolic acidosis, poor feeding, lethargy, vomiting, osteoporosis, neurological dysfunction, pancytopenia, developmental retardation and cardiomyopathy. Liver transplantation has recently been considered as one of the treatment options for patients with PA. This case report describes several anesthetic considerations for patients with PA undergoing liver transplantation. Understanding the patient's status and avoiding events that may precipitate metabolic acidosis are important for anesthetic management of patients with PA. In conclusion, anesthesia should be focused on minimizing the severity of metabolic acidosis with following considerations: (1) maintaining optimal tissue perfusion by avoiding hypotension, (2) preventing hypoglycemia, and (3) providing bicarbonate to compensate for the acidosis. PMID:24101962

Ryu, Jiyoung; Shin, Young Hee; Gwak, Mi Sook; Kim, Gaab-Soo

2013-01-01

376

3-[3-(2-Fluoro-benzo-yl)thio-ureido]propionic acid  

PubMed Central

In the title compound, C10H11FN3O3S, the 2-fluoro­benzoyl and proponic acid groups maintain a trans–cis conformation with respect to the thiono C=S bond across their C—N bonds. The propionic acid group adopts an anti conformation about the C—C bond, with an N—C—C—C torsion angle of 173.8?(2)°. The amino groups are involved in the formation of intra­molecular N—H?O and N—H?F hydrogen bonds. In the crystal, pairs of O—H?O hydrogen bonds link mol­ecules into inversion dimers. PMID:24940277

Ngah, Nurziana; Mohamed, Nor Azanita; Yamin, Bohari M.; Mohd Zaki, Hamizah

2014-01-01

377

[Animal experiment studies on the topical and systemic effectiveness of prednisolone-17-ethylcarbonate-21-propionate].  

PubMed

Prednisolone-17-ethyl carbonate-21-propionate (PrEP, Hoe 777) was tested for antiinflammatory activity in various animal models by topical and systemic administration. In those models being indicative of topical efficacy, the potency of PrEP was the same as that of desoximetasone. However, systemic effects after topical administration of PrEP in shaved skin of the dorsum of rats were relatively weak compared with the reference compound. Moreover, there were less systemic corticoid effects after s.c. administration of PrEP than after desoximetasone. Thus, PrEP is obviously a compound with a considerable split of topical and systemic activity, suggesting its testing in man for systemic effects after topical administration. PMID:3705675

Alpermann, H G; Sandow, J; Vogel, H G

1986-01-01

378

[Experimental animal studies on the topical and systemic activity of prednisolone-17-ethylcarbonate-21-propionate].  

PubMed

Prednisolone-17-ethylcarbonate-21-propionate (PrEP, Hoe 777) was tested for antiinflammatory activity in various animal models by topical and systemic administration. In those models being indicative of topical efficacy, the potency of PrEP was the same as that of desoximetasone. However, systemic effects after topical administration of PrEP in shaved skin of the dorsum of rats were relatively weak compared with the reference compound. Moreover, there were less systemic glucocorticoid effects after s.c. administration of PrEP than after desoximetasone. Thus, PrEP is obviously a compound with a considerable split of topical and systemic activity, suggesting its testing in man for systemic effects after topical administration. PMID:6981416

Alpermann, H G; Sandow, J; Vogel, H G

1982-01-01

379

Synthesis of aldehyde building blocks protected as acid labile N-Boc N,O-acetals: toward combinatorial solid phase synthesis of novel peptide isosteres.  

PubMed

The synthesis of (RS)-3'-tert-butoxycarbonyl-perhydro-1', 3'-oxazine-2'-yl acetic acid and the syntheses of the simple and C-2 substituted 3'-tert-butoxycarbonyl-perhydro-1',3'-oxazine-2'(RS)-yl propionic acids from simple starting materials are presented. The simple compounds were prepared from 1,3-propanediol and 1, 4-butanediol, respectively, via a short series of facile steps, in 70% overall yield in both cases. For the syntheses of the C-2 substituted compounds of the longer homologue, (RS)-3'-tert-butoxycarbonyl-perhydro-1',3'-oxazine-2'-yl propionic acid, a malonic ester route was selected, thus allowing easy incorporation of various side chains. The stability of the novel aldehyde protection group, the N-Boc N,O-acetal moiety, under various acidic conditions was investigated, and it was found to cleanly and rapidly yield the aldehyde under strong acidic conditions or, if desired, slower under less harsh conditions. As a demonstration of the use of the building blocks, one building block was coupled to a solid support and, after unmasking of the aldehyde, submitted to three different types of nucleophilic reactions (Pictet-Spengler condensation, reductive amination, Horner-Wadsworth-Emmons olefination) followed by further chemical modification, and the identity of the structures were verified after cleavage from the resin. PMID:11148062

Groth, T; Meldal, M

2001-01-01

380

Disease severity and the effect of fluticasone propionate on chronic obstructive pulmonary disease exacerbations.  

PubMed

Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with worse health and increased healthcare utilisation. The Inhaled Steroids in Obstructive Lung Disease in Europe (ISOLDE) study in COPD showed a 26% reduction in the yearly rate of exacerbations in patients treated with fluticasone propionate (FP) compared to placebo, but did not indicate which patients showed greatest benefit. In this study the patients were stratified into mild and moderate-to-severe COPD using the American Thoracic Society criterion of forced expiratory volume in one second (FEV1) 50% predicted, and the total number of exacerbations and those requiring treatment with oral corticosteroids were examined. There were 391 (195 FP) patients with mild COPD and 359 (180 FP) patients with moderate-to-severe disease. The exacerbation rate was highly skewed in mild disease, but more normally distributed in moderate-to-severe disease. FP reduced the overall exacerbation rate in moderate-to-severe disease (FP median rate 1.47 yr(-1), placebo 1.75 yr(-1)), but not in mild disease (FP 0.67 yr(-1), placebo 0.92 yr(-1)). FP use was associated with fewer patients with > or = 1 exacerbation x yr(-1) being treated with oral corticosteroids (mild: FP 8%, placebo 16%; moderate-to-severe: FP 17%, placebo 30%). Effects of fluticasone propionate on exacerbations were seen predominantly in patients with a postbronchodilator forced expiratory volume in one second <50% predicted. These data support recommendations in the Global Initiative for Chronic Obstructive Disease treatment guidelines that inhaled corticosteroids should be considered in patients with moderate-to-severe chronic obstructive pulmonary disease who experience recurrent exacerbations. PMID:12570111

Jones, P W; Willits, L R; Burge, P S; Calverley, P M A

2003-01-01

381

Adrenal insufficiency in a woman secondary to standard-dose inhaled fluticasone propionate therapy  

PubMed Central

Summary A 55-year-old woman with asthma presented with adrenal insufficiency of unknown origin. She was referred to our Division of Reproductive Endocrinology to further evaluate an undetectable morning cortisol level discovered during the evaluation of a low serum DHEA-S level. She was asymptomatic other than having mild fatigue and weight gain. Her medication list included 220??g of inhaled fluticasone propionate twice daily for asthma, which she was taking as prescribed. On presentation, the undetectable morning cortisol level was confirmed. A urinary measurement of fluticasone propionate 17?-carboxylic acid was markedly elevated. Fluticasone therapy was discontinued and salmeterol therapy initiated with supplemental hydrocortisone. Hydrocortisone therapy was discontinued after 2 months. A repeat urinary fluticasone measurement 4 months after the discontinuation of fluticasone therapy was undetectably low and morning cortisol level was normal at 18.0??g/dl. Inhaled fluticasone is generally considered to be minimally systemically absorbed. This patient's only clinical evidence suggesting adrenal insufficiency was fatigue accompanying a low serum DHEA-S level. This case demonstrates that adrenal insufficiency can be caused by a routine dose of inhaled fluticasone. Missing this diagnosis could potentially result in adrenal crisis upon discontinuation of fluticasone therapy. Learning points Standard-dose inhaled fluticasone can cause adrenal insufficiency.Adrenal insufficiency should be considered in patients taking, or who have recently discontinued, inhaled fluticasone therapy and present with new onset of nonspecific symptoms such as fatigue, weakness, depression, myalgia, arthralgia, unexplained weight loss, and nausea that are suggestive of adrenal insufficiency.Adrenal insufficiency should be considered in postoperative patients who exhibit signs of hypoadrenalism after fluticasone therapy has been withheld in the perioperative setting.Routine screening for hypoadrenalism in patients without clinical signs or symptoms of adrenal insufficiency after the discontinuation of inhaled fluticasone therapy is not indicated due to the apparently low incidence of adrenal insufficiency caused by fluticasone. PMID:24683484

Hay, Casey M; Spratt, Daniel I

2014-01-01

382

The Solvent Mediated Thermodynamics of Cellulose Deconstruction  

E-print Network

solvent accessible, chain collapse occurred spontaneously in the freeand free energy simulations of cellulose-dissolving processes are conducted in four solventFree’ 18 Chain System55 3.6.7 Convergence of Solvent

Gross, Adam S

2012-01-01

383

La texture de la cellulose animale  

Microsoft Academic Search

Summary Electron micrographs of animal cellulose (tunicin ofPhallusia mammillata) show continuous fibrils of 200 Å width. The fibrils are flattened and seem to exhibit a longitudinal periodicity of 200 Å. Anastomoses have not been observed.

Kurt H. Meyer; L. Huber; E. Kellenberger

1951-01-01

384

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01...2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2012-04-01

385

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01...2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2013-04-01

386

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01...2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2011-04-01

387

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01...2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2010-04-01

388

21 CFR 582.1005 - Acetic acid.  

21 Food and Drugs 6 2014-04-01...2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2014-04-01

389

Manufacturing Ethyl Acetate From Fermentation Ethanol  

NASA Technical Reports Server (NTRS)

Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

Rohatgi, Naresh K.; Ingham, John D.

1991-01-01

390

Influence of Delivery Devices on Efficacy of Inhaled Fluticasone Propionate: A Comparative Study in Stable Asthma Patients  

PubMed Central

Background: Inhaled corticosteroids are the preferred treatment for long-term control of all grades of persistent asthma. These are administered by various delivery devices with very little information whether these devices can affect the efficacy of inhaled corticosteroids. Fluticasone propionate is a relatively new inhalational corticosteroid compared to older ones like beclomethasone and budesonide. Aims & Objective: To assess the relative efficacy of fluticasone propionate administered from different delivery devices to adult patients of chronic stable bronchial asthma as measured by pulmonary function test parameters. Material and Methods: This prospective study was undertaken to assess the relative efficacy of fluticasone propionate administered from different delivery devices to adult patients of chronic stable bronchial asthma as measured by pulmonary function test parameters. Fourty eight subjects were administered, fluticasone propionate (250 ?g) by dry powder inhaler, metered dose inhaler, metered dose inhaler with spacer and fluticasone (1mg) via nebulizer consecutively each week for four weeks under direct supervision. Pulmonary function test was done before and one hour after administration of the drug on each visit. Results: After excluding nine patients who were lost to follow up, data was analysed for the remaining thirty nine patients and no significant difference in peak expiratory flow rate (p=0.77), forced expiratory volume in one second (p=0.95), forced vital capacity (p=0.24) and forced expiratory volume in one second and forced vital capacity ratio (p=0.22) was seen after giving fluticasone by different devices. Conclusion: Fluticasone propionate delivered by different devices like dry powder inhaler, metered dose inhaler, metered dose inhaler with spacer and nebulizer have similar effect on lung function in patients of chronic stable bronchial asthma and may be used interchangeably. PMID:24179895

Kolasani, Bhanu Prakash; Lanke, Venu Madhavi; Diyya, Sudheer

2013-01-01

391

Bioprospecting for cellulose-degrading microbes  

NSDL National Science Digital Library

This is a long-term inquiry activity in which students investigate locations they believe harbor cellulose-digesting microbes, collect samples, isolate them on selective media, and screen them for cellulase activity. These novel microbes may be useful for the production of cellulosic ethanol. In the process they learn about plating techniques, serial dilutions, symbiotic relationships and enzyme specificity. Two methods are provided, one focusing on isolation of pure microbial strains, the other focusing on finding symbiotic communities of microbes.

Center, Great L.; Energy, U. S.

392

FT Raman investigation of sodium cellulose sulfate  

Microsoft Academic Search

FT Raman investigation of sodium cellulose sulfates (NaCS) was reported. Different NaCS were prepared by two diverse sulfation\\u000a methods and their total degrees of substitution (DS) of sulfate groups were determined through either 13C-NMR spectroscopy or elemental analysis. Subsequently, these NaCS were characterized with FT Raman spectroscopy. The caused\\u000a bands through the introduction of the sulfate groups in cellulose chain

Kai Zhang; Erica Brendler; Steffen Fischer

2010-01-01

393

Cellulose biosynthesis and function in bacteria.  

PubMed Central

The current model of cellulose biogenesis in plants, as well as bacteria, holds that the membranous cellulose synthase complex polymerizes glucose moieties from UDP-Glc into beta-1,4-glucan chains which give rise to rigid crystalline fibrils upon extrusion at the outer surface of the cell. The distinct arrangement and degree of association of the polymerizing enzyme units presumably govern extracellular chain assembly in addition to the pattern and width of cellulose fibril deposition. Most evident for Acetobacter xylinum, polymerization and assembly appear to be tightly coupled. To date, only bacteria have been effectively studied at the biochemical and genetic levels. In A. xylinum, the cellulose synthase, composed of at least two structurally similar but functionally distinct subunits, is subject to a multicomponent regulatory system. Regulation is based on the novel nucleotide cyclic diguanylic acid, a positive allosteric effector, and the regulatory enzymes maintaining its intracellular turnover: diguanylate cyclase and Ca2(+)-sensitive bis-(3',5')-cyclic diguanylic acid (c-di-GMP) phosphodiesterase. Four genes have been isolated from A. xylinum which constitute the operon for cellulose synthesis. The second gene encodes the catalytic subunit of cellulose synthase; the functions of the other three gene products are still unknown. Exclusively an extracellular product, bacterial cellulose appears to fulfill diverse biological roles within the natural habitat, conferring mechanical, chemical, and physiological protection in A. xylinum and Sarcina ventriculi or facilitating cell adhesion during symbiotic or infectious interactions in Rhizobium and Agrobacterium species. A. xylinum is proving to be most amenable for industrial purposes, allowing the unique features of bacterial cellulose to be exploited for novel product applications. Images PMID:2030672

Ross, P; Mayer, R; Benziman, M

1991-01-01

394

Antimicrobial silver nanoparticles generated on cellulose nanocrystals  

Microsoft Academic Search

We describe a new approach to the formation of silver nanoparticles (Ag NPs) using cellulose nanocrystals. The process involves\\u000a periodate oxidation of cellulose nanocrystals, generating aldehyde functions which, in turn, are used to reduce Ag+ into Ag0 in mild alkaline conditions. The nanoparticles were characterized using transmission electron microscopy (TEM) and ultraviolet–visible\\u000a absorption spectroscopy. From the microscope studies (TEM) we

Nicolas DrogatRobert; Robert Granet; Vincent Sol; Abdelmajid Memmi; Naïma Saad; Carmen Klein Koerkamp; Philippe Bressollier; Pierre Krausz

2011-01-01

395

Physical insight into switchgrass dissolution in the ionic liquid 1-ethyl-3-methylimidazolium acetate  

SciTech Connect

Small-angle neutron scattering was used to characterize solutions of switchgrass and the constituent biopolymers cellulose, hemicellulose, and lignin, as well as a physical mixture of them mimicking the composition of switchgrass, dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate. The results demonstrate that the IL dissolves the cellulose fibrils of switchgrass, although a supramolecular biopolymer network remains that is not present in solutions of the individual biopolymers and that does not self-assemble in a solution containing the physical mixture of the individual biopolymers. The persistence of a network-like structure indicates that dissolving switchgrass in the IL does not disrupt all of the physical entanglements and covalent linkages between the biopolymers created during plant growth. Reconstitution of the IL-dissolved switchgrass yields carbohydrate-rich material containing cellulose with a low degree of crystallinity, as determined by powder X-ray diffraction, which impacts potential down-stream uses of the biopolymers produced by the process. The data suggests that the use of chemical additives which would break bonds that exist between the lignin and hemicellulose might improve the purity of the resulting product, but may not be able to disrupt the highly physically-entangled biopolymer network sufficiently to facilitate their separation.

Wang, Hui [University of Alabama, Tuscaloosa] [University of Alabama, Tuscaloosa; Gurau, Gabriela [University of Alabama, Tuscaloosa] [University of Alabama, Tuscaloosa; Pingali, Sai Venkatesh [ORNL] [ORNL; O'Neil, Hugh [ORNL] [ORNL; Evans, Barbara R [ORNL] [ORNL; Urban, Volker S [ORNL] [ORNL; Heller, William T [ORNL] [ORNL; Rogers, Robin D [University of Alabama, Tuscaloosa] [University of Alabama, Tuscaloosa

2014-01-01

396

Kinetics of Cellulose Digestion by Fibrobacter succinogenes S85.  

PubMed

Growing cultures of Fibrobacter succinogenes S85 digested cellulose at a rapid rate, but nongrowing cells and cell extracts did not have detectable crystalline cellulase activity. Cells that had been growing exponentially on cellobiose initiated cellulose digestion and succinate production immediately, and cellulose-dependent succinate production could be used as an index of enzyme activity against crystalline cellulose. Cells incubated with cellulose never produced detectable cellobiose, and cells that were preincubated for a short time with thiocellobiose lost their ability to digest cellulose (competitive inhibition [K(infi)] of only 0.2 mg/ml or 0.56 mM). Based on these results, the crystalline cellulases of F. succinogenes were very sensitive to feedback inhibition. Different cellulose sources bound different amounts of Congo red, and the binding capacity was HCl-regenerated cellulose > ball-milled cellulose > Sigmacel > Avicel > filter paper. Congo red binding capacity was highly correlated with the maximum rates of metabolism of cellulose digestion and inversely related to K(infm). Congo red (250 (mu)g/ml) did not inhibit the growth of F. succinogenes S85 on cellobiose, but this concentration of Congo red inhibited the rate of ball-milled cellulose digestion. A Lineweaver-Burk plot of ball-milled cellulose digestion rate versus the amount of cellulose indicated that Congo red was a competitive inhibitor of cellulose digestion (K(infi) was 250 (mu)g/ml). PMID:16535519

Maglione, G; Russell, J B; Wilson, D B

1997-02-01

397

New Insights into Hydrogen Bonding and Stacking Interactions in Cellulose  

SciTech Connect

In this quantum chemical study, we explore hydrogen bonding (H-bonding) and stacking interactions in different crystalline cellulose allomorphs, namely cellulose I and cellulose IIII. We consider a model system representing a cellulose crystalline core, made from six cellobiose units arranged in three layers with two chains per layer. We calculate the contributions of intrasheet and intersheet interactions to the structure and stability in both cellulose I and cellulose IIII crystalline cores. Reference structures for this study were generated from molecular dynamics simulations of water-solvated cellulose I and IIII fibrils. A systematic analysis of various conformations describing different mutual orientations of cellobiose units is performed using the hybrid density functional theory (DFT) with the M06-2X with 6-31+G (d, p) basis sets. We dissect the nature of the forces that stabilize the cellulose I and cellulose IIII crystalline cores and quantify the relative strength of H-bonding and stacking interactions. Our calculations demonstrate that individual H-bonding interactions are stronger in cellulose I than in cellulose IIII. We also observe a significant contribution from cooperative stacking interactions to the stabilization of cellulose I . In addition, the theory of atoms-in-molecules (AIM) has been employed to characterize and quantify these intermolecular interactions. AIM analyses highlight the role of nonconventional CH O H-bonding in the cellulose assemblies. Finally, we calculate molecular electrostatic potential maps for the cellulose allomorphs that capture the differences in chemical reactivity of the systems considered in our study.

Langan, Paul [ORNL

2011-01-01

398

Calculation of stoichiometric dissociation constants of monoprotic carboxylic acids in dilute aqueous sodium or potassium chloride solutions and p[m(H(+))] values for acetate and formate buffers at 25 degrees C.  

PubMed

Equations are given for calculation of the stoichiometric (molality scale) dissociation constants, K(m), of weak acids in dilute aqueous electrolyte solutions at 298.15 K from the thermodynamic dissociation constant, K(a), of the acid and the ionic strength, I(m), of the solution. The equations for K(m) were based on the single-ion activity coefficient equations of the Hückel type. The equations were tested with the conductivity data for formic, acetic, propionic, n-butyric, lactic, chloroacetic, alpha-crotonic and cyanoacetic acids, and with data measured by Harned cells for formic, acetic, propionic, n-butyric and glycolic acids. These data were taken from the literature. According to these tests, K(m) can be obtained by the Hückel method within experimental error at least up to I(m) of about 0.1 mol kg(-1). On the basis of the equations for K(m), it is suggested p(m(H)) values {p(m(H))=-lg[m(H(+))/(mol kg(-1))] where m refers to the molality} for buffer solutions containing acetic or formic acid. A new calibration method is suggested for glass electrode cells, and this method is based on the p(m(H)) values instead of pH values (pH=-lg[a(H(+))] where a refers to the activity). PMID:18968046

Partanen, J I

2000-08-16

399

A novel green approach for the preparation of cellulose nanowhiskers from white coir.  

PubMed

The aim of this work was to optimize the extraction of cellulose nanowhiskers (CNW) from unripe coconut husk fibers (CHF). The CHF was delignified using organosolv process, followed by alkaline bleaching (5% (w/w) H2O2+4% (w/w) NaOH; 50°C, 90 min). The CHF was subsequently hydrolyzed with 30% (v/v) sulfuric acid (60°C, 360 min). The process yielded a partially delignified acetosolv cellulose pulp and acetic black liquor, from which the lignin was recovered. The CNW from the acetosolv pulp exhibited an average length of 172±88 nm and a diameter of 8±3 nm, (aspect ratio of 22±8). The surface charge of the CNW was -33 mV, indicating a stable aqueous colloidal suspension. The nanocrystals presented physical characteristics close to those extracted from cellulose pulp made by CHF chlorine-pulping. This approach offers the additional advantage of extracting the lignin as an alternative to eradication. PMID:24906779

Nascimento, Diego M; Almeida, Jessica S; Dias, Amanda F; Figueirêdo, Maria Clea B; Morais, João Paulo S; Feitosa, Judith P A; de F Rosa, Morsyleide

2014-09-22

400

A monolithic functional film of nanotubes/cellulose/ionic liquid for high performance supercapacitors  

NASA Astrophysics Data System (ADS)

A novel monolithic, pre-fabricated, fully functional film made of a nanostructured free-standing layer is presented for a new and competitive class of easy-to-assemble flexible supercapacitors whose design is in-between the all solid state and the traditional liquid electrolyte. The film is made of two vertically aligned multi-walled carbon nanotube (VANT) electrodes that store ions, embedded-in, and monolithically interspaced by a solution of microcrystalline cellulose in a room temperature ionic liquid (RTIL) electrolyte (1-ethyl-3-methylimidazolium acetate-EMIM Ac). The fine tuning of VANTs length and electrolyte/cellulose amount leads, in a sole and continuous block, to ions storage and physical separation between the electrodes without the need of the additional separator layer that is typically used in supercapacitors. Thus, physical discontinuities that can induce disturbances to ions mobility, are fully eliminated significantly reducing the equivalent series resistance and increasing the knee frequency, hence outclassing the best supercapacitors based on VANTs and non-aqueous electrolytes. The excellent electrochemical response can also be addressed to the chosen electrolyte that, not only has the advantage of leading to a significantly simpler and more affordable fabrication procedure, but has higher ionic conductivity, lower viscosity and higher ions mobility than other electrolytes capable of dissolving cellulose.

Basiricò, Lucia; Lanzara, Giulia

2014-12-01

401

21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.  

...2014-04-01 2014-04-01 false Ethyl alcohol containing ethyl acetate. 584.200...Affirmed as GRAS § 584.200 Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the...

2014-04-01

402

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria.  

PubMed

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Gluconacetobacter europaeus exhibited the highest resistance to acetic acid (10%), whereas Gluconacetobacter intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal acetic acid production rate of Ga. europaeus slowly increased, but specific growth rates decreased concomitant with increased concentration of acetic acid in medium. The lag phase of A. pasteurianus was twice and four times longer in comparison to the lag phases of Ga. europaeus and Ga. intermedius, respectively. PQQ-dependent ADH activity was twice as high in Ga. europaeus and Ga. intermedius as in A. pasteurinus. The purified enzymes showed almost the same specific activity to each other, but in the presence of acetic acid, the enzyme activity decreased faster in A. pasteurianus and Ga. intermedius than in Ga. europaeus. These results suggest that high ADH activity in the Ga. europaeus cells and high acetic acid stability of the purified enzyme represent two of the unique features that enable this species to grow and stay metabolically active at extremely high concentrations of acetic acid. PMID:16133326

Trcek, Janja; Toyama, Hirohide; Czuba, Jerzy; Misiewicz, Anna; Matsushita, Kazunobu

2006-04-01

403

Biocompatibility of Bacterial Cellulose Based Biomaterials  

PubMed Central

Some bacteria can synthesize cellulose when they are cultivated under adequate conditions. These bacteria produce a mat of cellulose on the top of the culture medium, which is formed by a three-dimensional coherent network of pure cellulose nanofibers. Bacterial cellulose (BC) has been widely used in different fields, such as the paper industry, electronics and tissue engineering due to its remarkable mechanical properties, conformability and porosity. Nanocomposites based on BC have received much attention, because of the possibility of combining the good properties of BC with other materials for specific applications. BC nanocomposites can be processed either in a static or an agitated medium. The fabrication of BC nanocomposites in static media can be carried out while keeping the original mat structure obtained after the synthesis to form the final nanocomposite or by altering the culture media with other components. The present article reviews the issue of biocompatibility of BC and BC nanocomposites. Biomedical aspects, such as surface modification for improving cell adhesion, in vitro and in vivo studies are given along with details concerning the physics of network formation and the changes that occur in the cellulose networks due to the presence of a second phase. The relevance of biocompatibility studies for the development of BC-based materials in bone, skin and cardiovascular tissue engineering is also discussed. PMID:24955750

Torres, Fernando G.; Commeaux, Solene; Troncoso, Omar P.

2012-01-01

404

Acetic acid fermentation of acetobacter pasteurianus: relationship between acetic acid resistance and pellicle polysaccharide formation.  

PubMed

Acetobacter pasteurianus strains IFO3283, SKU1108, and MSU10 were grown under acetic acid fermentation conditions, and their growth behavior was examined together with their capacity for acetic acid resistance and pellicle formation. In the fermentation process, the cells became aggregated and covered by amorphous materials in the late-log and stationary phases, but dispersed again in the second growth phase (due to overoxidation). The morphological change in the cells was accompanied by changes in sugar contents, which might be related to pellicle polysaccharide formation. To determine the relationship between pellicle formation and acetic acid resistance, a pellicle-forming R strain and a non-forming S strain were isolated, and their fermentation ability and acetic acid diffusion activity were compared. The results suggest that pellicle formation is directly related to acetic acid resistance ability, and thus is important to acetic acid fermentation in these A. pasteurianus strains. PMID:20699583

Kanchanarach, Watchara; Theeragool, Gunjana; Inoue, Taketo; Yakushi, Toshiharu; Adachi, Osao; Matsushita, Kazunobu

2010-01-01

405

Fluorescence quenching of etilefrine by acetate anion  

NASA Astrophysics Data System (ADS)

Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH<7 and is related to phenolic group dissociation. However, intensity of etilefrine fluorescence diminishes as the concentration of the acetate anion increases at pH>7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47×10 -9 and 0.216×10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( ?0'=0.58×10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98×10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.

Quintero Osso, B.; Carazo Rodríguez, F. M.; Morales Domingo, J. J.; Cabeza González, M. C.; Thomas Gómez, J.

1999-02-01

406

Acetate limitation and nitrite accumulation during denitrification  

SciTech Connect

Nitrite accumulated in denitrifying activated sludge mixed liquor when the carbon and electron source, acetate, was limited. If acetate was added to obtain a carbon-to-nitrogen (C:N) ratio in the range of 2:1 to 3:1, nitrate was completely consumed at the same rate with no nitrite accumulation, indicating that nitrate concentration controlled the respiration rate as long as sufficient substrate was present. However, when acetate was reduced to a C:N ratio of 1:1, while nitrate continued to be consumed, > 50% of the initial nitrate-nitrogen accumulated as nitrite and 29% persisted as nitrite throughout an endogenous denitrification period of 8--9 h. While nitrite accumulated during acetate-limited denitrification, the specific nitrate reduction rate increased significantly compared with the rate when excess acetate was provided as follows: 0.034 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h versus 0.023 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h, respective. This may be explained by nitrate respiration out-competing nitrite respiration for limited acetate electrons. Complete restoration of balanced denitrification and elimination of nitrite accumulation during denitrification required several weeks after the C:N ratio was increased back to 2:1.

Oh, J. [Pohang Univ. of Science and Technology (Korea, Republic of). School of Environmental Engineering] [Pohang Univ. of Science and Technology (Korea, Republic of). School of Environmental Engineering; Silverstein, J. [Univ. of Colorado, Boulder, CO (United States)] [Univ. of Colorado, Boulder, CO (United States)

1999-03-01

407

Improved growth and nutrition status in children with methylmalonic or propionic acidemia fed an elemental medical food  

Microsoft Academic Search

Background: Failure-to-thrive (FTT) has been described in patients with organic acidemias treated with low protein diets. Objective: To determine if patients with methylmalonic (MMA) or propionic acidemia (PA) can achieve normal growth and nutrition status. Methods: A 6-month multicenter outpatient study was conducted with infants and toddlers treated with Propimex-1 Amino Acid-Modified Medical Food With Iron (Ross Products Division, Abbott

Steven Yannicelli; Phyllis B Acosta; Antonio Velazquez; Hans-Georg Bock; Barbara Marriage; Thaddeus W Kurczynski; Marvin Miller; Mark Korson; Robert D Steiner; Laurie Bernstein; Jeffrey Chinsky; Patricia Galvin-Parton; Georgianne L Arnold

2003-01-01

408

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source  

Microsoft Academic Search

Inthemicrobial competition observedinenhanced biological phosphorusremoval(EBPR) systems, an undesirable group of micro-organisms known as glycogen-accumulating organisms (GAOs) compete for carbon in the anaerobic period with the desired polyphosphate-accumulating organisms (PAOs). Some studies have suggested that a propionate carbon source provides PAOs with acompetitive advantage over GAOs in EBPRsystems; however, the metabolism ofGAOs with this carbon source has not been previously investigated.

Adrian Oehmen; Raymond J. Zeng; Aaron M. Saunders; Linda L. Blackall; Jurg Keller; Zhiguo Yuan

2006-01-01

409

Complex formation in rare-earth metal-propionic acid-diamagnetic salt systems by 1 H NMR spectroscopy  

Microsoft Academic Search

Complex formation of propionic acid with ions of rare-earth metals of the yttrium subgroup (D2O, 5.0 M NaNO3) in the absence and presence of diamagnetic Mg2+ cations was studied by 1H NMR spectroscopy in combination with mathematic simulation of complicated equilibria. Stability constants for monopropionate\\u000a complexes of rare-earth ions decrease when the rare-earth cation and Mg2+ are present in the

I. V. Sukhno; V. Yu. Buz’ko; V. T. Panyushkin

2006-01-01

410

Hydrogen yield from a hydrogenase in Frankia R43 at different levels of the carbon source propionate.  

PubMed

Fermentative hydrogen yield was investigated in the Frankia strain R43, which was grown in different amounts of the carbon source propionate. In relation to hydrogen yield, the hydrogenase enzyme was characterized by use of Western blot. A bioreactor study revealed a 10-fold increase in growth within 50 h. The study showed that there is an active anaerobic hydrogen production in Frankia R43 and that this hydrogenase is immunologically related to the subunit HoxU of Ralstonia eutropha. PMID:21276650

Chatchai, Kosawang; Lasanthi, Kudahettige Rasika; Lars, Resman; Anita, Sellstedt

2012-03-01

411

Vibrational spectra and natural bond orbital analysis of the herbicidal molecule 2(4-chlorophenoxy)-2-methyl propionic acid  

Microsoft Academic Search

The herbicide 2(4-chlorophenoxy)-2-methyl propionic acid (MCPP) has been subjected to NIR FT–Raman and infrared spectral studies. The optimized molecular structure, vibrational wavenumbers, IR intensities and Raman activities have been calculated by using density functional method (B3LYP) with the standard 6-31G(d) basis set. The calculated molecular geometry has been compared with the XRD data. The detailed assignments of the normal modes

J. Clemy Monicka; C. James

2011-01-01

412

Temperature responsive cellulose-graft-copolymers via cellulose functionalization in an ionic liquid and RAFT polymerization.  

PubMed

Well-defined cellulose-graft-polyacrylamide copolymers were synthesized in a grafting-from approach by reversible addition-fragmentation chain transfer polymerization (RAFT). A chlorine moiety (degree of substitution DS(Cl) ? 1.0) was introduced into the cellulose using 1-butyl-3-methylimidazolium chloride (BMIMCl) as solvent before being substituted by a trithiocarbonate moiety resulting in cellulose macro-chain transfer agents (cellulose-CTA) with DS(RAFT) of 0.26 and 0.41. Poly(N,N-diethylacrylamide) (PDEAAm) and poly(N-isopropylacrylamide) (PNIPAM) were subsequently grafted from these cellulose-CTAs and the polymerization kinetics, the molecular weight characteristics and the product composition were studied by nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and size exclusion chromatography of the polyacrylamides after cleavage from the cellulose chains. The number-average molecular weights, Mn, of the cleaved polymers ranged from 1100 to 1600 g mol(-1) for PDEAAm (dispersity ? = 1.4-1.8) and from 1200 to 2600 g mol (-1) for PNIPAM (? = 1.7-2.1). The LCST behavior of the cellulose-graft-copolymers was studied via the determination of cloud point temperatures, evidencing that the thermoresponsive properties of the hybrid materials could be finely tuned between 18 and 26 °C for PDEAAm and between 22 and 26 °C for PNIPAM side chains. PMID:24833429

Hufendiek, Andrea; Trouillet, Vanessa; Meier, Michael A R; Barner-Kowollik, Christopher

2014-07-14

413

Chemical genetics to examine cellulose biosynthesis  

PubMed Central

Long-term efforts to decode plant cellulose biosynthesis via molecular genetics and biochemical strategies are being enhanced by the ever-expanding scale of omics technologies. An alternative approach to consider are the prospects for inducing change in plant metabolism using exogenously supplied chemical ligands. Cellulose biosynthesis inhibitors (CBIs) have been identified among known herbicides, during diverse combinatorial chemical libraries screens, and natural chemical screens from microbial agents. In this review, we summarize the current knowledge of the inhibitory effects of CBIs and further group them by how they influence fluorescently tagged cellulose synthase A proteins. Additional attention is paid to the continuing development of the CBI toolbox to explore the cell biology and genetic mechanisms underpinning effector molecule activity. PMID:23372572

Brabham, Chad; DeBolt, Seth

2013-01-01

414

Development of bioconversion of cellulosic wastes  

SciTech Connect

Improvements during the past decade in cellulolytic enzymes for conversion of cellulosic and lignocellulosic materials to glucose and by fermentation to ethanol and other products have led to development of a practical commercial process. A pilot plant based on utilization of the advanced Trichoderma reesei fungal enzyme systems available, utilized in a fed-batch simultaneous saccharification and fermentation system, has been operated successfully at an eastern pulp and paper mill. Successive improvements in techniques and operating conditions for this pilot plant, with a capacity of 1 t/d feedstock input, has led to production of ethanol with conversions of 80-90% of theoretical, based on cellulose content of the feedstock. With the data and knowledge in hand, this technology is now ready for use in a proposed demonstration facility with a nominal capacity of 50-100 t/d of feedstock. Projected economics are presented for proposed commercial facilities processing up to 500 t/d of cellulosic wastes.

Katzen, R.; Monceaux, D.A. [Raphael Katzen Associates International, Inc., Cincinnati, OH (United States)

1995-12-31

415

An ecotoxicological characterization of nanocrystalline cellulose (NCC).  

PubMed

The pulp and paper industry in Canada is developing technology for the production and use of nanocrystalline cellulose (NCC). A key component of the developmental work is an assessment of potential environmental risks. Towards this goal, NCC samples as well as carboxyl methyl cellulose (CMC), a surrogate of the parent cellulosic material, were subjected to an ecotoxicological evaluation. This involved toxicity tests with rainbow trout hepatocytes and nine aquatic species. The hepatocytes were most sensitive (EC20s between 10 and 200 mg/l) to NCC, although neither NCC nor CMC caused genotoxicity. In tests with the nine species, NCC affected the reproduction of the fathead minnow at (IC25) 0.29 g/l, but no other effects on endpoints such as survival and growth occurred in the other species at concentrations below 1 g/l, which was comparable to CMC. Based on this ecotoxicological characterization, NCC was found to have low toxicity potential and environmental risk. PMID:20795908

Kovacs, Tibor; Naish, Valerie; O'Connor, Brian; Blaise, Christian; Gagné, Francois; Hall, Lauren; Trudeau, Vance; Martel, Pierre

2010-09-01

416

Low-energy irradiation effects in cellulose  

NASA Astrophysics Data System (ADS)

Using molecular dynamics simulations, we determined the threshold energy for creating defects as a function of the incident angle for all carbon and oxygen atoms in the cellulose monomer. Our analysis shows that the damage threshold energy is strongly dependent on the initial recoil direction and on average slightly higher for oxygen atoms than for carbon atoms in cellulose chain. We also performed cumulative bombardment simulations mimicking low-energy electron irradiation (such as TEM imaging) on cellulose. Analyzing the results, we found that formation of free molecules and broken glucose rings were the most common forms of damage, whereas cross-linking and chain scission were less common. Pre-existing damage was found to increase the probability of cross-linking.

Polvi, Jussi; Nordlund, Kai

2014-01-01

417

Inhaled fluticasone propionate impairs pulmonary clearance of Klebsiella Pneumoniae in mice  

PubMed Central

Background Recent trials demonstrate increased pneumonia risk in chronic obstructive pulmonary disease patients treated with the inhaled corticosteroid (ICS) fluticasone propionate (FP). There is limited work describing FP effects on host defenses against bacterial pneumonia. Methods C57BL/6 mice received daily, nose-only exposure to nebulized FP or vehicle for 8?days, followed by pulmonary challenge with Klebsiella pneumoniae. Bacterial burden, phagocytosis, leukocyte recruitment, cytokine expression, nitric oxide release, and survival were measured. Results Inhaled FP increased bacterial burden in lungs and blood 48?h after infection but affected neither in vivo phagocytosis of bacteria by alveolar macrophages (AM) nor alveolar neutrophil recruitment. AM from FP-treated mice showed impaired expression of infection induced TNF-alpha, IP-10 (CXCL-10), and interleukin 6 (IL-6), and AM also showed a trend towards impaired intracellular pathogen control following in vivo infection. In vitro FP treatment resulted in a dose-dependent impairment of cytokine expression by AM. Furthermore, infection-induced nitric oxide (but not hydrogen peroxide) production was impaired by FP in vivo and in vitro. FP decreased survival in this model. Conclusions Exposure to inhaled FP impairs pulmonary clearance of K. pneumoniae in mice, an effect associated with greater systemic bacteremia and death. Decreased AM cytokine and nitric oxide expression parallel the failure to control infection. These results support the study of ICS effects on human pulmonary host defenses. PMID:22651370

2012-01-01

418

Acetylated and propionated derivatives of swertiamarin have anti-adipogenic effects  

PubMed Central

Objective: To investigate whether the acetylated and propionated derivatives (LMP-09-1 and -2) of swertiamarin have anti-adipogenic effects. Materials and Methods: 3T3-L1 pre-adipocytes were grown in Dulbecco's Modified Eagle's Medium (DMEM) containing 10% calf serum; fully confluent cells were differentiated with insulin, dexamethasone, and 3-isobutylmethylxanthine in the presence and absence of LMP-09-1 and -2 (100 ?g/mL) for 10 days. Control cells received same amount of dimethylsulfoxide (DMSO). On day ten, cells were analyzed for triglycerides accumulation and the expression of genes involved in adipogenesis, lipogenesis, and lipolysis. In another set of experiment, effects of LMP-09-1 and 2 were studied for isoproterenol induced lipolysis using fully mature adipocytes. Results: LMP-09-1 and -2 caused a significant (P < 0.001) reduction in intracellular triglycerides accumulation. Both LMP-09-1 and -2 significantly (P < 0.001) decreased the mRNA expression of peroxisome proliferator activated receptor-? and acetyl-CoA carboxylase-1, and increased isoproterenol induced lipolysis in adipocytes. LMP-09-1 induced lipolysis even in the absence of isoproterenol, and also showed a significant up-regulation of carnitine palmitoyl transferase-1? and hormone sensitive lipase (HSL) gene expression. Conclusions: These findings show that swertiamarin derivatives, LMP-09-1 and -2 have a potent anti-adipogenic effect.

Vaidya, Hitesh B; Goyal, Ramesh K; Cheema, Sukhinder K

2014-01-01

419

Accelerated Stability Testing of a Clobetasol Propionate-Loaded Nanoemulsion as per ICH Guidelines  

PubMed Central

The physical and chemical degradation of drugs may result in altered therapeutic efficacy and even toxic effects. Therefore, the objective of this work was to study the stability of clobetasol propionate (CP) in a nanoemulsion. The nanoemulsion formulation containing CP was prepared by the spontaneous emulsification method. For the formulation of the nanoemulsion, Safsol, Tween 20, ethanol, and distilled water were used. The drug was incorporated into an oil phase in 0.05% w/v. The lipophilic nature of the drug led to the O/W nanoemulsion formulation. This was characterized by droplet size, pH, viscosity, conductivity, and refractive index. Stability studies were performed as per ICH guidelines for a period of three months. The shelf life of the nanoemulsion formulation was also determined after performing accelerated stability testing (40°C ± 2°C and 75% ± 5% RH). We also performed an intermediate stability study (30°C ± 2°C/65% RH ± 5% RH). It was found that the droplet size, conductivity, and refractive index were slightly increased, while the viscosity and pH slightly decreased at all storage conditions during the 3-month period. However, the changes in these parameters were not statistically significant (p?0.05). The degradation (%) of the optimized nanoemulsion of CP was determined and the shelf life was found to be 2.18 years at room temperature. These studies confirmed that the physical and chemical stability of CP were enhanced in the nanoemulsion formulation. PMID:24482775

Ali, Mohammad Sajid; Alam, Mohammad Sarfaraz; Alam, Nawazish; Anwer, Tarique; Safhi, Mohammed Mohsen A.

2013-01-01

420

Generation of a Hypomorphic Model of Propionic Acidemia Amenable to Gene Therapy Testing  

PubMed Central

Propionic acidemia (PA) is a recessive genetic disease that results in an inability to metabolize certain amino acids and odd-chain fatty acids. Current treatment involves restricting consumption of these substrates or liver transplantation. Deletion of the Pcca gene in mice mimics the most severe forms of the human disease. Pcca? mice die within 36 hours of birth, making it difficult to test intravenous systemic therapies in them. We generated an adult hypomorphic model of PA in Pcca? mice using a transgene bearing an A138T mutant of the human PCCA protein. Pcca?/?(A138T) mice have 2% of wild-type PCC activity, survive to adulthood, and have elevations in propionyl-carnitine, methylcitrate, glycine, alanine, lysine, ammonia, and markers associated with cardiomyopathy similar to those in patients with PA. This adult model allowed gene therapy testing by intravenous injection with adenovirus serotype 5 (Ad5) and adeno-associated virus 2/8 (AAV8) vectors. Ad5-mediated more rapid increases in PCCA protein and propionyl-CoA carboxylase (PCC) activity in the liver than AAV8 and both vectors reduced propionylcarnitine and methylcitrate levels. Phenotypic correction was transient with first generation Ad whereas AAV8-mediated long-lasting effects. These data suggest that this PA model may be a useful platform for optimizing systemic intravenous therapies for PA. PMID:23648696

Guenzel, Adam J; Hofherr, Sean E; Hillestad, Matthew; Barry, Mary; Weaver, Eric; Venezia, Sarah; Kraus, Jan P; Matern, Dietrich; Barry, Michael A

2013-01-01

421

The development of unusual B-cell functions in the testosterone-propionate-treated chicken.  

PubMed Central

Chickens were treated with 4 mg of testosterone propionate on the twelfth day of embryonic life. Bursal remnants of testosterone-treated chickens were very small in size and had very few or no bursal follicles: the lymphoid tissue was replaced substantially by fibrosis. Testosterone-treated chickens formed almost exclusively IgM antibodies to sheep red blood cells and influenza virus, whereas no IgM or IgG response to Brucella abortus or Salmonella pullorum, and no IgG response to sheep red blood cells was demonstrable. Surgical removal of bursal remnants of testosterone-treated chickens at hatching did not significantly affect IgM response to sheep red blood cells. These B-cell functions of testosterone-treated chickens were not improved by addition of T cells, as shown by adoptive cell transfer experiments. Thus, there appears to be an unusual type B-cell development which is independent of the bursa of Fabricius. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:6966602

Hirota, Y; Suzuki, T; Bito, Y

1980-01-01

422

Factors determining the sequence of oxidative decarboxylation of the 2- and 4-propionate substituents of coproporphyrinogen III by coproporphyrinogen oxidase in rat liver  

PubMed Central

Coproporphyrinogen oxidase (EC 1.3.3.3) catalyses the oxidative decarboxylation of the 2- and 4-propionate substituents of coproporphyrinogen III to form protoporphyrinogen IX. A 4-propionate-substituted porphyrinogen, harderoporphyrinogen, which is also a substrate for coproporphyrinogen oxidase, is formed during the reaction. Synthetic [14C]coproporphyrinogens III, specifically labelled in the carboxyl carbon atoms of either the 2- or 4-propionate substituents, were used to measure the rate of decarboxylation of each substituent by rat liver coproporphyrinogen oxidase. The experimental results, together with the recognition that in all known substrates of coproporphyrinogen oxidase only those propionate groups flanked by a specific arrangement of substituents are decarboxylated, indicate that the 4-propionate group of coproporphyrinogen III cannot be attacked until the 2-propionate group has been decarboxylated. Production of 14CO2 from the substrate labelled in the 2-propionate group therefore measures the formation of harderoporphyrinogen, whereas 14CO2 from the 4-propionate-labelled substrate measures protoporphyrinogen IX formation. The rate of harderoporphyrinogen formation is about twice that of protoporphyrinogen, and this ratio is unchanged by varying the concentration of coproporphyrinogen III or by competitive inhibition of the enzyme. When coproporphyrinogen III is present in an excess, two fractions of harderoporphyrinogen can be distinguished. One accumulates during the reaction, and the other, which is destined to become protoporphyrinogen IX, does not equilibrate with added harderoporphyrinogen. It is suggested that both decarboxylations take place at the same active centre, which becomes temporarily inaccessible to coproporphyrinogen III and added harderoporphyrinogen, and that the molecule rotates after the first decarboxylation to allow the second to take place. PMID:629747

Elder, George H.; Evans, J. Olwyn; Jackson, J. Richard; Jackson, Anthony H.

1978-01-01

423

Synthesis of 1-[ 11c]methylpiperidin-4-yl propionate ([ 11c]pmp) for in vivo measurements of acetylcholinesterase activity  

Microsoft Academic Search

Synthesis of 1-[11C]methylpiperidin-4-yl propionate ([11C]PMP), an in vivo substrate for acetylcholinesterase,